The scraper conveyor SPK301 (Fig. 16.4) consists of the head and end drives 1 , transition sections 6, linear pans 8, transitional 7 and drift 3 , scraper chain 2 , and attachments, consisting of linear boards 5 and drift frames 4.
Rice. 16.4. Scraper conveyor SPK301
Linear pan consists of sidewalls, bottom and locks. The sides of the pan at the ends are equipped with wear-resistant cast attachments. The connection of the pans is boltless, which ensures the bending of the conveyor in the process of moving it with hydraulic jacks along the longwall.
The drift grates installed in the middle drift divide the lava, as it were, into two parts 100 mm long (see Fig. 13.2). With this scheme of mining of potash ores, the simultaneous operation of two combines is possible, which makes it possible to increase the load on the face. The middle drift is ventilated, due to which the sanitary and hygienic working conditions in the longwall are significantly improved. To ensure movement along the middle drift, two special skis are welded to the lower shelves of the drift pans.
Attached equipment is located on the linear part of the conveyor pan stack: a guide (round shape) for harvester gripping, a cable layer chute, guides for the chain of the remote feed system and brackets for cable laying.
Scraper conveyors with the upper working branch, as well as with the lower working branch, were tested on the delivery of hard abrasive ores from under the bulk, however, due to the rapid wear of the chains, the traction body floating to the surface of the transported ore and the jamming of ore pieces between chain I and the teeth of the drive sprocket, they not recommended for use in such severe operating conditions.
Scraper conveyors are also used in some transport installations for special purposes, such as loaders, self-propelled wagons and mechanized bunkers. With a room-and-pillar system for the development of potash ores (see Fig. 5.9, a) together with a tunneling and mining combine, a bunker-loader is used, in the bottom of which a double-chain scraper conveyor is built. The bunker-loader is a mobile storage tank on wheels, designed to smooth out uneven cargo flow and increase the utilization rate of the harvester over time. When the self-propelled wagon moves, the combine works continuously, filling the bunker-loader with ore. The ore is reloaded from the bunker to the wagon by a bottom scraper conveyor.
Abroad, short powerful scraper feeders are used, the working body of which consists of 5 or 7 traction chains, on which the scrapers are staggered along the width of the feeder chute. This type of feeder is designed to unload abrasive hard ores from bunkers.
Calculation of scraper conveyors. For a delivery scraper conveyor operating in a mining block with rock mass loaded onto it, a check calculation of productivity, strength of traction chains, drive power, as well as the possible maximum length of the conveyor in one line for specific operating conditions is carried out.
The initial data for the verification calculation are: the estimated cargo flow from the shearer or transport unit, from which the rock mass enters the scraper conveyor; conveyor length and angle of inclination; density of delivered rock mass; data technical specifications conveyor.
Scraper conveyor technical productivity, t/h
Q t = 3600 Ω 0 k 3 γ k β ν
where Ω 0 - nominal cross-sectional area of the gutter, m 2; k 3- filling factor of the chute, taken equal to 0.6 ÷ 0.8 - for horizontal conveyors, 0.4 ÷ 0.5 - for inclined conveyors transporting up, 1 - the same for transporting down; kβ- coefficient taking into account the change in conveyor performance depending on the angle of inclination of the conveyor installation:
| β , degree | -16 to -10 -5 0 +10 +20 | ||
| kβ | 1,5 1,3 1 0,7 0,3 | ||
Speed (m/s) chain v taken according to the characteristics of the conveyor.
Conveyor performance Q t must be greater than the estimated traffic Q p entering the conveyor, i.e. Q t>Q p.
The strength of traction chains is determined by their maximum tension, which is calculated by the method of bypassing the contour by points (see 2.2). For a conveyor with a chain traction body, the tension is S 1 = 2500÷3000 N. Tension at the next point S 2 \u003d S 1 + W then, where
Tension S 3 \u003d (1.05 ÷ 1.07) S 2, S 4 \u003d S max \u003d S 3 + W gr, where
where q t and q- weight per 1 m of the length of the conveyor, respectively, of the chain with scrapers and the transported load, kg/m; f 1 = 0.35÷0.4 - coefficient of friction of the chain with scrapers along the chute; f 2 = 0.6÷0.8 - the same rock mass along the chute; L- conveyor length, m
Chain margin
m = S times λ/S max
where S times- breaking force of one chain, N; λ - coefficient taking into account the uneven distribution of traction force between the chains, taken equal to 1.8 - for double-chain conveyors with round-link chains and 1 - for single-chain conveyors.
Permissible margin of safety of chains m≥ 4÷6. Total pulling force (N) on the drive shaft of the conveyor F = S 4 - S 1 or
F \u003d k (W gr + W then),(16.3)
where k= l,l - coefficient taking into account the resistance on the end sprockets.
Scraper Conveyor Motor Power (kW)
where η = 0.8÷0.85 - drive transmission efficiency; k zap= 1.15÷1.2 - power reserve factor.
If drives are installed at the head and tail of the conveyor, then the maximum chain tension can be determined graphically. First, it is necessary to build a tension diagram of the scraper conveyor traction body with one drive, equal in power to two drives (Fig. 16.5, a, dashed line). Next break down the total tractive effort F between drives on F1 and F2 according to their powers, build a real tension diagram (see Fig. 16.6, a, solid line) and determine the tension at various points of the traction body.
Rice. 16.5. Tension diagram of the scraper conveyor traction unit when installing the head and tail drives ( a) and a graph of the dependence of the length of the scraper conveyor on the angle of its installation at different conveyor performance ( b): I- delivery up; II- shipping down
At a constant installed power of the drive motor, the length of the conveyor depends on the angle of installation of the conveyor and its performance. Substituting the values W gr and W then from formulas (16.1) and (16.2) and the value F from formula (16.4) to formula (16.3), you can determine the length of the conveyor (m) in one stave:
According to the graph of the dependence of the length of the conveyor L K on the angle of its installation b and productivity, it is possible to establish the possibility of using the conveyor in certain conditions operation (Fig. 16.5, b).
16.3. Operation and maintenance of scraper conveyors
The installation of the scraper conveyor must be carried out in strict sequence. First, the head drive station is installed, then the pans, the scraper chain and the necessary auxiliary equipment are laid out, then the tail station is placed, the pans are connected to each other and the conveyor chains are tensioned.
In order to check the correct installation of the conveyor, its test run is carried out. With short-term inclusions, the chain is inspected for its complete revolution, then the conveyor is run in idle for 30-50 minutes. If the conveyor is idling normally, then it is run-in at 50% load for two days. In the process of running-in, the work of all assembly units of the conveyor is carefully monitored and any defects are eliminated.
To control the movement, serviceability of the state and integrity of the chains of the scraper conveyor, magnetic inductive sensors are used, installed at the drive station under the idle branch of the traction body. If 1 or 2 circuits are broken in the sensor, the balance of the magnetic system is disturbed, as a result of which an impulse is given to turn off the conveyor drive.
During the operation of the scraper conveyor, its maintenance, current repairs and elimination possible faults and failures are carried out in accordance with the Manual for the maintenance and current repair of equipment using work orders.
According to the PPR system, maintenance includes shift, daily, weekly and monthly technical services, which include lubrication, adjustment, cleaning, inspection and verification of the condition and operation of all assembly units of the conveyor.
For example, the 1st repair inspection of the SPK301 scraper conveyor is carried out after the issuance of 40 thousand tons of potash ore, and the 2nd - after the issuance of 120 thousand tons of ore. Planned current repairs of this conveyor are carried out in the following sequence: the 1st - after the issuance of 240 thousand tons of ore, the 2nd - 360 thousand tons. The conveyor is overhauled after 12 months. work or after the delivery of 480 thousand tons of potash ore.
Basic safety rules: before starting the conveyor, make sure that the protective covers of the drive and guards are in good condition and give a warning sound signal; the working start of the conveyor is carried out 5-7 seconds after the warning sound signal; it is not allowed to operate the conveyor with an incorrectly assembled traction chain, twisted chain segments and deformed scrapers, with open pan lock joints, loose drive bolt connections. All work on the repair and maintenance of the scraper conveyor is carried out with the starter switched off and blocked.
16.4. Plate conveyors
In lamellar conveyors, the functions of the traction body are performed by 1 or 2 chains, and the functions of the carrier body are carried out by a load-carrying canvas formed from steel plates, fixed on the traction body. On the plates, running rollers are fixed, which roll along the guides during the operation of the conveyor.
Advantages apron conveyors: the possibility of transporting large-sized abrasive rock mass; the possibility of installing a conveyor along a curved route with small curvature radii and in workings with large inclination angles; lower than in scraper conveyors, resistance to movement and energy consumption; the possibility of installing intermediate drives, which allows you to increase the length of the conveyor in one line. Disadvantages of apron conveyors: high metal consumption and large mass of moving parts; the complex design of the lamellar canvas and the difficulty of cleaning it from the remnants of the wet and sticky rock mass; low reliability.
The device and the main assembly units. The main elements of the apron conveyor (Fig. 16.6, a) are lamellar canvas 1, traction ring chain 2, running rollers 3, moving along the top 4 and bottom guide 5, a drive station located at the head of the conveyor, and an end take-up station.
Rice. 16.6. Cross sections of the stack of the ore apron conveyor (a) and the heavy apron feeder (b)
The cross-sectional shape of the plates can be rectangular or trapezoidal. The plates are stamped from sheet steel with a thickness of 6-8 mm. At the bottom of the plates, stiffening ribs are stamped, which keep the cargo from sliding on inclined conveyors. When assembling the canvas, the individual plates are overlapped and fixed to the chain (every plate is required). Plate length 200-400 mm.
To the plates (in several pieces) are attached with the help of short cantilever or through axles running rollers mounted on ball bearings and equipped with flanges that ensure the passage of curves with a radius of 15¸20 m. bearing plates and is 1000-2000 mm.
The metal structure of the conveyor stack is assembled from separate sections, consisting of upper and lower guides fixed on support posts.
The end drive and tension stations of the apron conveyor are fundamentally similar in design to the stations of the scraper conveyor. On apron conveyors, it is possible to install caterpillar-type intermediate drives, in which fists are fixed on the drive chain, interacting with the links of the conveyor traction chain. When installing intermediate drives, the length of the apron conveyor in one line can reach 1200-1500 m.
Types of plate conveyors. In the mining industry, in the underground development of strong abrasive ores, experimental designs of face plate conveyors designed to deliver ore from under the bulk, and accumulating or main plate conveyors were used.
In face plate conveyors, the load-carrying canvas had to have high strength and be well protected from getting ore fines on the roller guides. Two chains were used as a traction body. The speed of movement of the canvas under the pile did not exceed 0.2 m/s. The apron conveyors installed in accumulating or main workings had a web width of up to 800 mm, a traction body speed of 0.6-0.7 m/s, and a technical capacity of up to 500 t/h. To prevent spillage of ore fines between the plates, the working surface of the plate cloth was covered with pieces of a conveyor belt that are attached to the plates. However, due to the unreliability of operation, the complexity of installation and other shortcomings, apron conveyors have not found wide application in the underground mining of hard abrasive ores.
For transportation of non-abrasive small-sized rock mass, it is possible to use lamellar conveyors of a parametric series designed for coal industry: main curving conveyors type P - for workings with inclination angles of 0-24°; main inclined type PN - for straight workings with inclination angles of 24-35°. P-65M plate bending conveyors with a width of 650 mm and a capacity of up to 300 t/h were operated in coal mines.
For uniform supply of abrasive ore to crushers and from under crushers, apron feeders are used (Fig. 16.6, b) 5-15 m long, with a bearing canvas 1200-1800 mm wide, and sometimes more. The feeder blades are made of wear-resistant steel, cast, capable of withstanding heavy loads. In contrast to apron conveyors in feeders, the apron web usually moves along permanently installed upper 6 and lower 7 rollers mounted on a frame on plain bearings 8 and 9, which are centrally lubricated. The speed of movement of the lamellar web of the feeder is 0.1-0.35 m/s, the productivity is 300-500 m 3 /h.
Questions for self-examination
1. Describe the basic structures of traction chains and explain the principle of transmission of traction force by engagement.
2. Draw the main schemes of scraper conveyors, indicate the main assembly units and explain the principle of operation of the scraper conveyor.
3. Draw circuit diagram scraper conveyor and describe the procedure for its calculation.
4. Specify the main areas of application of scraper conveyors in the mining industry.
5. Explain the principle of operation of apron conveyors and indicate their areas of application.
17. PNEUMATIC AND HYDRAULIC PIPELINE TRANSPORT
17.1. Schemes of pipeline transport and areas of its application
The movement of various materials and mixtures through pipes under the action of a static pressure created by a mixture column in a vertical pipeline stav, or the movement of a working medium (air or water) is called pipeline transport.
In underground mining of ores, pipeline transport is used mainly for the delivery of filling materials and mixtures to the goaf. Hydraulic delivery of ore is used very limitedly, mainly in sloping deposits, where the ore is washed away with a pressure jet of water, and the pulp (a mixture of water and solids) flows down the sloping soil of the mine. Therefore, further we will consider pipeline transport only for the transportation of filling materials and mixtures.
Currently, the backfill is used in the development of valuable ores of non-ferrous, rare and radioactive metals, high-quality iron ores, and some types of mining and chemical raw materials. The use of backfill allows to reduce losses and dilution of ore, to replace ore pillars with artificial ones, to keep the earth's surface undisturbed, to simultaneously develop the deposit by open and underground methods, to mine ores that are prone to spontaneous combustion by isolating the mined-out space from air access, to ensure safety in difficult mining and geological conditions works, as well as partially place production waste underground. Backfilling is of particular relevance when developing deposits at great depths, where strong backfilling masses prevent rock bursts at high rock pressure.
The disadvantage of backfilling is the rise in the cost of mining, however, in some cases, the value of additionally obtained ore can cover the cost of backfilling.
Depending on the method of laying and the type of transport, dry, hydraulic and hardening bookmarks are used. As materials for the initially dry backfilling, waste rocks, sand, and gravel, which were mined along the way or entering the mine, were used. During dry backfilling, backfilling material was delivered to the mined-out space by gravity, under the action of gravity, by scraper installations, loading and transport machines, conveyors, pneumatic pipeline transport. Later, dry backfilling began to be replaced by hydraulic backfilling, and now hardening backfilling has become widespread, providing high strength and density of the backfilling array. With the use of a hardening backfill, it became possible to create high-performance mining systems when extracting valuable, low-stable or spontaneously combustible ores, as well as working at depths with high rock pressure. For example, at mining enterprises of non-ferrous metallurgy, about 85% of the total volume of backfilling is hardening backfill.
The composition of the hardening filling mixture includes binders (cement, ground slags of ferrous and non-ferrous metallurgy), inert aggregates (sand, tailings of processing plants, rock from dumps, gravel, crushed stone) and water. To increase the plasticity and transportability of hardening filling mixtures, plasticizing additives (for example, polycryamide, etc.) are introduced, which make up tenths and hundredths of a percent by weight of the binder.
For the delivery of hardening filling mixtures, gravity is used (Fig. 17.1, a) and gravity-pneumatic (Fig. 17.1, b) pipeline transport.
The pipeline of gravity installation consists of vertical and horizontal parts. Stowing mixture flows continuously into the intake funnel of the vertical pipeline (see Fig. 17.1, a) and moves a certain distance along the horizontal part due to the static head of the mixture column in the vertical part of the pipeline. Horizontal transportation distance is 3-5 times greater than the height of the vertical column of the filling mixture, the movement speed is 0.3-0.8 m/s (depending on the composition of the mixture), the pipeline diameter is from 76 to 220 mm.
Rice. 17.1. Schemes of pipeline transport of filling materials: a- gravity; b - gravity-pneumatic; in- pneumatic with filling machine; G - gravity hydraulic on sloping soil or chute: d- gravity hydraulic with vertical and horizontal pipelines - e - pressure hydraulic; Well, the same with the feeder; h - hydraulic elevator - 1 - pipeline- 2 - filling machine; 3 - inclined chute; 4 - slurry pump; 5 - feeder; 6 - pump
The advantages of gravity pipeline transport are rather high productivity (up to 60-180 m 3 /h) and simplicity of design, the disadvantage is a limited transportation distance, depending on the height of the vertical part of the pipeline and the hardening time of backfill mixtures.
The use of gravity-flow pneumatic transport makes it possible to significantly increase the length of filling mixtures delivery due to the energy of compressed air supplied to the horizontal parts of the pipeline through pneumatic ejectors (pneumatic tie-ins) mounted at an angle of 25-30 ° to the longitudinal axis of the pipeline in the direction of filling mixture movement (see Fig. Fig. 17.1, 6 ) and connected by flexible hoses to the air line. Pneumatic tie-in diameter 1.5- 2", the distance between them is 60-100 m. The speed of the mixture in the pneumatic transport section reaches 4-10 m/s. The mixture is separated by compressed air into portions and then pushed in separate portions through a horizontal pipeline to the place of laying.
The advantages of gravity-flow pneumatic transport are the supply of filling mixture over long distances with high productivity and reliability in operation, the disadvantage is increased energy consumption (compared to gravity transport) due to the use of compressed air. This type of transport of hardening backfill mixtures is becoming more and more widespread.
Consider the scheme of pneumatic pipeline transport in a continuous stream (Fig. 17.1, in). Backfilling material is introduced into the pipeline with the help of a backfilling machine, through which the material in suspension is moved by the air medium and thrown into the mined-out space. The speed of the air flow at which the particles of the transported material are in suspension is called soaring speed. If a particle of material is likened to a sphere with a diameter d(m), then the equation of equilibrium of a ball placed in the air in the pipeline can be written in the following form:
where g t is the density of the material, kg / m 3; l B - resistance coefficient, depending on the shape of the particle and the state of the surface; g B \u003d l,2 - air density, kg / m 3; u V - soaring speed (m / s), determined by the formula
The speed of transportation of backfill material is assumed to be greater than the speed of soaring.
Such a scheme of pneumatic transport (see Fig. 17.1, e) is used for dry laying. Backfilling material - non-abrasive crushed rock with a particle size of 5-80 mm, transportation distance 20-80 mm, productivity 30-60 m 3 /h, compressed air consumption - about 150 m 3 per 1 m 3 backfilling material.
Disadvantages of pneumatic transport of dry filling materials: large dust formation; high wear of pipes and filling machines; high consumption of compressed air; high requirements for backfill material in terms of its granulometric composition and abrasiveness, etc. This type of transport is unacceptable for the delivery of hardening backfill mixtures due to the violation of the structure of the mixture, and, consequently, the strength of the laid massif. Pneumatic transport of filling materials in a continuous stream is not widely used in ore mines.
Hydraulic transport units are divided into self-flowing and pressure. In gravity installations, the material is transported by a jet of water along inclined gutters and pipes (Fig. 17.1, G) or through pipes under the action of static pressure created by the pulp in the vertical part of the pipeline (Fig. 17.1, e). Ready slurry or filling material is fed into the receiving funnel from the bunker to the chute and washed off with a hydraulic monitor into the receiving funnel of the vertical pipeline. The ratio of the height of the vertical part of the pipeline to the horizontal is approximately 1:4 for lumpy and 1:15 for fine-grained materials. The particle size of the material should not exceed 50 - 80 mm. Tailings of processing plants, granulated slags, sands mixed with clay and crushed rocks are used for hydraulic backfilling. The consistency of the pulp - the ratio of solid and liquid (S:L), which depends on the size of the filling material, is taken in a ratio of 1:0.6 to 1:5. The advantage of the hydrotransport scheme (see Fig. 17.1, d) - simplicity of design, the disadvantage is the limited distance of transportation.
Slurry pumps are installed in the pressure hydraulic transport system (Fig. 17.1, e) or other mechanisms that ensure the suction of the pulp and its transportation through the pipeline. When using slurry pumps, it is most effective to use fine-grained backfill materials (for example, sands and tailings of processing plants), which move quite easily in the pressure pipeline and provide high quality bookmark array.
With a different scheme of pressure hydraulic transport (Fig. 17.1 , and) bulk cargo with a particle size of up to 60 mm is loaded into the pipeline by a special loading device - a feeder, and water is supplied to the pipeline by a pump.
When developing alluvial deposits, hydraulic elevators are used to transport the pulp to flushing devices (Fig. 17.1, h). The hydraulic elevator works as follows. Water is supplied under pressure through the pipeline to the nozzle. Due to the significant speed of the water jet coming out of the nozzle, a vacuum is created in the hydraulic elevator chamber, the pulp is sucked into the chamber through the nozzle and enters the pipeline under the pressure of the water jet. The pulp lifting height by hydraulic elevators can reach 10 - 15 m, horizontal transportation length - up to 100 m, productivity 30 - 75 m 3 /h. The disadvantages of hydraulic elevators are low efficiency (about 20%), limitation on the size of the transported rock mass.
The soaring speed in hydrotransport installations is called critical speed, in which the particles of the transported material are in a suspended state in the water stream, and individual large particles move in an abrupt manner. The force of gravity of a particle equivalent to a ball with a diameter d( m ), in a suspended state (in an upward flow of water) is balanced by the buoyancy force (according to the law of Archimedes) and the resistance to displacement:
where g 0 is the density of water, kg / m 3; l is the drag coefficient at free fall particles in water.
Critical speed (m/s)
The calculated speed of the pulp is assumed to be greater than the critical one - u = (1.1¸1.2) u cr. In practice, it is 2.5 - 3.5 m / s.
The advantages of pressure hydraulic transport are high productivity and the supply of backfill material over long distances, the disadvantages are increased wear of the pipeline, low strength of the backfill mass, high water content in the backfill material and an increase in the cost of dehydration, drainage and pumping of water.
Hydraulic transport is not used to deliver hardening backfill mixtures, since a large amount of water disrupts the structure of the mixture, liquefies and removes the cement pulp, which leads to a decrease in the strength of the backfill mass.
17.2. Pipeline transport equipment
The stowing complex includes mechanisms for the preparation and dosing of raw materials and stowing mixtures, as well as pipeline transport equipped with the necessary control devices.
Known stowing complexes differ from each other in the use of various starting materials for the preparation of stowing mixtures and the location of ore mines in different climatic zones. The main requirements for modern stowing complexes: versatility and the ability to prepare stowing mixtures of various properties for hardening and hydraulic backfilling; deviation from the specified characteristics of mixtures by no more than 10%; extensive mechanization and automation of everything technological process preparation of backfill mixture and backfill operations.
Two methods of preparing hardening mixtures are used - joint and separate. The most common is the joint method, in which, on the surface of an ore mine, “inert materials are first prepared separately (dispersed and crushed, cleaned of impurities) and a binder, and then they are dosed and fed into a mixer for mixing with each other and water. The finished mixture enters the receiving funnel of the vertical part of the pipeline. With the separate method, which is used very rarely, the components of the filling mixture are transported separately to the worked-out space and mixed only during the laying process.
Backfill complexes, depending on the purpose, can be central, serving to prepare the backfill mixture for the entire deposit, and local, serving individual sections.
Depending on the duration of operation, stationary and mobile (or temporary) backfilling complexes are distinguished. The latter are intended for the preparation of small volumes of mixtures for remote areas of goaf and can be located on the surface or in the mine.
Necessary condition to ensure the transportability of filling mixtures and the normalized strength of the artificial massif, accurate dosing of the mixture components is essential. Dosing of aggregates and binder is carried out by sliding gates or screw feeders installed on supply bins. More accurate automatic weighing batchers are also used, and for mixing components, high-performance continuous mixers with forced mixing of the mixture with blades.
The cost of hardening backfill is 30 - 40% of the cost of 1 m 3 of ore brought to the surface, and the cost of raw materials for backfill mixtures reaches 50 - 70% of the total cost of backfill. Consumption of the most expensive component - cement - 120¸400 kg per 1 m 3 of filling mixture (on average, about 200 kg). Large cement consumption rates are necessary to improve the plasticity and transportability of filling mixtures in order to reduce possible cases of pipeline blockage and increase the length of transportation with a gravity-flow delivery method. The use of ground slags from ferrous and non-ferrous metallurgy in the amount of up to 300 - 350 kg per 1 m 3 of filling allows reducing cement consumption by 80 - 100 kg / m 3. An increase in the transportability of the mixture and a slight decrease in the consumption of cement is achieved by introducing plasticizers or fillers into the binder, such as finely ground sandstones, limestone, clay, etc.
Developed new technology vibration mixing of components, which ensures a more complete use of enrichment tailings as fillers and obtaining a homogeneous, high-density mixture by transmitting vibration impulses to it with a frequency exceeding the frequency of rotation of the mixer blades.
The spatial layout of the backfill pipelines depends on the layout of the opening and mining of the deposit and the general plan of the mine surface. According to their purpose, backfill pipelines are divided into main stationary pipelines laid vertically in shafts or in; wells and horizontally along the main workings, and local temporary, laid near the places of laying. The latter are often remounted as stowing works are performed.
For pipelines, seamless steel, less often cast iron and polyethylene pipes are used. Promising are polyethylene pipes, which do not rust, are much lighter than steel pipes, are strong enough and have a lower specific resistance to the movement of the mixture, which makes it possible to increase the transportation range. The cost of polyethylene pipes is 20 - 30% lower than steel pipes.
The inner diameter of the pipes is chosen taking into account the given productivity and the size of the aggregate piece, and the wall thickness - taking into account the purpose, type of transported material and installation conditions. Vertical main pipelines have a wall thickness of 12 - 16 mm, horizontal - 8¸10 mm, on bends of curvature - 12¸15 mm.
Connection of individual pipe sections - welded or bolted flange (for main) and flanged quick-release (for local pipelines). On the main pipeline, it is recommended to install flange inserts 500 - 800 mm long after 150 - 200 m to ensure the elimination of pipeline blockage.
The vertical part of the pipeline is connected to the horizontal part using a support elbow installed on the foundation (Fig. 17.2). By horizontal workings the pipeline is laid on supports or wooden beds and give it a slope of 0.005 - 0.008 in the direction of the mixture movement. The radius of curvature of the pipeline is taken at least 10 of its diameters.
Rice. 17.2. Scheme of fastening of the backfill pipeline: 1 - concrete base; 2 - emphasis; 3 - manometer; 4 - flange insert; 5 - pneumoejector nozzle
Due to the abrasiveness of the transported mixtures, the pipeline is subject to wear, the intensity of which depends on the composition of the mixture, the quality of the pipe steel, the manufacturing technology and the thickness of the pipe walls, as well as on the mode of transportation. For example, with an increase in speed from 0.7 - 0.8 m / s (gravity-flowing) to 2 m / s or more (gravity-pneumatic transport), pipe wear more than doubles. The consumption of steel pipes is 0.02 - 0.25 tons per 1000 m 3 of the transported mixture. The throughput of steel pipes, depending on the abrasive properties of the transported material and the steel grade, is 500 - 700 thousand m 3. Polyethylene pipes are subject to less wear.
In order to increase the durability of pipes, their inner surface is lined with stone casting, rubber or other materials. There is a practice of lining the inner surfaces of the knees with hard alloy.
On a horizontal pipeline of gravity-flow pneumatic transport, at certain distances at an angle of 15 - 30 °, pneumoejectors are cut (Fig. 17.3), connected by rubber hoses to an air line laid along the pipeline. The diameter of the pneumoejector nozzle is 10 - 20 mm (depending on the diameter of the pipeline). In order to eliminate the blockage on the pipeline, reserve pneumoejectors are installed. To prevent the hardening mixture from entering the compressed air network, pneumatic ejectors are equipped with check valves.
Rice. 17.3. Pneumatic ejector: 1 - pipe branch; 2 - ejector housing; 3 - stock; 4 - locking device; 5 - steel plate; 6 - rubber; 7 - pipeline
Next to the pneumoejectors, at the same interval, water inlet devices are installed on the pipeline to eliminate emergency plugs and flush the pipeline. The device is a branch pipe welded in the upper part of the pipeline, closed with a plug or a screw needle valve. Water is supplied to the device under pressure up to 4 MPa from a water main laid along the pipeline.
Pressure gauges are installed at the points of tie-in of pneumatic ejectors and at the bend of the transition of the vertical pipeline to the horizontal one to measure the air pressure in the backfill pipeline.
To prevent and eliminate pipeline blockages, vibration installations are used (Fig. 17.4). As a result of vibration-pipeline, the coefficient of resistance to movement is reduced concrete mix, which allows you to eliminate blockages and increase the efficiency of transporting mixtures.
Rice. 17.4. Pipeline vibrator: 1 - electric motor; 2 - clutch; 3 - vibrator; 4 - pipeline; 5 - shock absorber; 6 - foundation
17.3. Calculation of the main parameters of pipeline transport
The main parameters of pipeline transport are productivity, pipeline diameter, transportation length, etc.
Technical productivity of gravity pipeline transport for filling mixture (m 3 / h)
from where pipeline diameter (m)
The speed of movement of the mixture during gravity transportation is taken from the condition of its stability to stratification and the throughput of the pipeline. The optimal speed is u = 0.5¸0.7 m/s (less often l.5¸2m/s).
Maximum horizontal gravity conveying length
where H k 3= 0.7¸0.8 - filling factor of the vertical part; g is the density of the mixture, t / m 3; Dr- specific pressure loss during the movement of the mixture through the pipeline, Pa/m; b- angle of inclination of the pipeline to the horizon, degree; - total equivalent length of bends and turns located along the length of the pipeline, m.
Equivalent length l e(90°) for an elbow with a 90° angle and a radius of curvature of 2 m is 12 m, and with a radius of curvature of 1 m - 20 m. For elbows with an angle of rotation a k<90º эквивалентная длина (м)
Specific pressure loss (Pa/m)
where t0- static shear stress, Pa; m cm- viscosity of the mixture, Pa-s. Approximately accept Dr= 0.1 MPa/m.
The length of the horizontal section of the pipeline can be increased by switching from gravity to gravity-pneumatic transportation.
Distance from the vertical part of the pipeline to the first pneumoejector (m)
where P B is the pressure of compressed air, MPa.
Maximum length of the horizontal section of pneumatic conveying (m)
where u P and u c- the speed of the mixture, respectively, in the sections of pneumatic transport and by gravity, m/s. As a rule, they take u P=4¸10 m/s.
The first working pneumatic ejector is installed at the end of the gravity section, the second - at a distance of 60-100 m from the first, etc. The possible length of delivery by gravity-pneumatic transport can reach up to 2000-2500 m.
Technical productivity (m 3 /h) of the hydrotransport plant for pulp
Pulp velocity u = (1.1¸1.2) u cr. Practically u = 2.5¸3.5 m/s.
Productivity for solid filling material (M 3 / h)
where s = 0.25¸0.4 - pulp concentration.
Substituting value V P from formula (17.12) to formula (17.13), it is possible to determine the required diameter of the pipeline (m,) at which the specified productivity for solid backfill material is ensured:
The greatest length of horizontal transportation (m) under the action of static pressure for gravity hydraulic transport (see Fig. 17.1, d).
where H- height of the vertical part of the pipeline, m; h- residual (velocity) head of the pulp at its exit from the pipeline, m (usually h£20m); l 1 - coefficient of resistance to movement of the pulp, determined by the formula
where g P - pulp density, t/m 3 ; åL equiv - the total equivalent length of the elbows (with a pipe diameter of 50 and 200 mm, åL equiv is 0.5 and 3 m for valves, respectively, for elbows - 0.3 and 2 m).
17.4. Automation, operation and safety rules
The main requirements for automated stowing complexes are: maintaining a given mixture composition and obtaining an artificial mass of normalized strength; ensuring automatic control over the stability of the mode of transportation of the mixture. The automation scheme should perform the following functions: automatic dosing of aggregates, binder and water; control of mixture movement speed, air pressure, mixture viscosity and mixture level in the vertical pipeline; automatic protection in case of emergencies.
Currently, work is underway to create automated stowing complexes. The modern equipment of the complexes allows the operator to remotely control the parameters of the filling mixture transportation and take timely measures to prevent emergencies.
Maintaining the specified composition of the mixture is carried out using automatic weighing devices for binder and aggregate and using a water flow meter.
The operator's console displays the readings of the pressure gauge installed on the pipeline at the transition point of the vertical section to the horizontal, the mixture presence sensor, and the pressure gauge installed on the compressed air line. When the pressure in the pipeline reaches 2.5 MPa, sound and light alarms are triggered, since an increase in pressure to such a value indicates an increase in the resistance to the movement of the mixture and the possibility of traffic jams. The reasons for the formation of plugs can be uneven supply of the backfill mixture, non-observance of the ratio of liquid and solid, low speeds in the gravity section, foreign objects entering the pipeline or a decrease in its cross section due to blocking, insufficient supply of compressed air to the pneumatic conveying section, etc.
In order to avoid possible setting of the hardening filling mixture and loss of its mobility, the blockage of the pipeline must be eliminated as soon as possible. The sequence of operations in the elimination of pipeline blockages: tapping the pipeline; activation of vibration devices located on the pipeline; activation of backup ejectors at the pneumatic conveying section; arrangement of the pipeline in the places of installation of flange inserts and water supply to the pipeline.
During the operation of the stowing complex, it is necessary to monitor the tightness of the pipeline and its fastening, to control the thickness of the pipe walls using radioisotope thickness gauges. On the horizontal sections of the pipeline, the wear of the inner walls of the pipes by 1 mm of thickness occurs when delivering 100-120 thousand m 3 of the mixture. The throughput of metal pipes until complete wear depends on the abrasiveness of the mixture, the steel grade of the pipe and can reach 500-700 thousand m 3. To increase the service life on a horizontal section, it is necessary to regularly turn the pipes by 120 ° after passing through them 10 thousand m 3 of the mixture. At the end of the next cycle of backfilling works, the pipeline is washed with water.
During the operation of pipeline transport, safety rules must be strictly observed: the pressure in the pipeline must not exceed the design pressure; it is not allowed to eliminate plugs by tapping with a sledgehammer if the residual thickness of the pipe wall is less than 4 - 5 mm; when eliminating plugs and undocking the pipeline, the operating personnel must be at a distance of at least 25 - 30 m in the direction of the mixture supply. Other security measures are regulated by the operating instructions for the stowing complex.
Questions for self-examination
1. Indicate the scope of pipeline transport in ore mines.
2. Draw the main schemes of pipeline transport and explain their principle of operation.
3. Explain the principle of operation of pneumatic transport. What is the soaring speed?
4. Explain the principle of hydraulic transport. What is called the critical speed and how to determine the calculated speed of the pulp?
5. List the main equipment of hydro- and pneumotransport installations.
6. How can blockage of the pipeline be eliminated when backfilling mixtures are moved through it?
Tasks and exercises
1. Determine the required diameter of the pipeline for transporting the stowing mixture at a technical capacity of V t =50 m 3 / h and a speed of movement of the mixture u = 0.7 m/s.
2. Write a formula for determining the maximum horizontal length of gravity transport, accept the initial data yourself and perform the calculation.
3. Set out in writing the procedure for calculating the hydrotransport installation.
IV. AUXILIARY MINING TRANSPORT FOR DELIVERY OF MATERIALS, EQUIPMENT AND PEOPLE
18. TRANSPORT MACHINES FOR DELIVERY OF MATERIALS, EQUIPMENT AND PEOPLE
18.1. Auxiliary means of transport and their areas of application
For the uninterrupted operation of stopes and preparatory faces, it is necessary to ensure the regular delivery of people to the ore mine and a large number of auxiliary loads of various sizes, weights and shapes, the main of which are: long materials (rails, pipes); timber; metal support; reinforced concrete products; bulk materials (ballast, cement); liquid fuels and lubricants; equipment, components and spare parts of machines, etc. For the transportation of these goods, complex mechanization means are used, including auxiliary transport installations, containers, packages and pallets for packing goods on the surface of the mine and delivering them to workplaces, mechanisms for loading and unloading operations.
Depending on the type of auxiliary cargo transported, mining and technical and mining and geological operating conditions, various types of auxiliary transport are used, which are divided into ground and suspended funds. Ground vehicles include rail vehicles, locomotive and cable haulage, trackless self-propelled transport vehicles or special conveyors. Suspended means of auxiliary transport include cable cars and monorails with cable and locomotive traction.
According to the norms of technological design of ore mines for the extraction of hard ores, as well as taking into account the main types of transport in operation, the transportation of people and the delivery of materials and equipment, it is recommended to carry out:
On horizontal workings equipped with rail tracks - by electric locomotive transport with special platforms and passenger trolleys;
On horizontal and inclined (up to 15 °) trackless mine workings - by auxiliary self-propelled machines on pneumatic tires, less often caterpillar movement mechanisms;
On inclined shafts equipped with rail tracks and cable traction - special trolleys or skips (for materials), special passenger trolleys equipped with parachute devices (for people);
On inclined workings - for people and auxiliary cargo of small mass by monocable overhead roads (in coal mines, overhead monorails are used for this purpose).
Basic requirements for auxiliary transport:
Coordination of the parameters of technological transport schemes of the mine with mining and geological conditions of development, schemes of stripping and preparation, development systems and operating conditions of the main transport vehicles in the mine;
Transportation of materials in enlarged units (packages, containers) collected in storage areas on the surface;
Ensuring, as far as possible, non-reloading delivery of materials and equipment to the places of consumption;
Delivery of materials and equipment according to schedules and plans for equipping faces, taking into account the need to deliver dismantled equipment, scrap metal, waste oils, etc. to the surface;
Equipping with stationary, portable or mobile lifting equipment for loading and unloading operations in places of consumption and at loading points;
Compliance with the regulated time for transporting people to their workplaces in the mine, while ensuring minimal fatigue and maximum comfort during the movement of vehicles.
In ore mines, for the transportation of auxiliary cargo, mainly electric locomotive transport and self-propelled transport vehicles are used, less often - rope haulage. Overhead vehicles are also being introduced.
18.2. Ground support vehicles
When using rail transport with electric traction for the transportation of auxiliary goods, ordinary freight cars and special cars are used; platforms for containers, packages and equipment; logging trolleys, ballast trolleys with valve unloading, for dust-like materials with a hermetically sealed body, for binding solutions, liquids, explosive materials; trolleys and specially equipped platforms for the transportation of conveyor belts, ropes, cables, gas cylinders and fire extinguishers, etc.
For the delivery of various materials and products (for example, sleepers, tubing, reinforced concrete puffs, drainage trays, etc.), packages, pallets and containers are used, adapted for mechanized methods of loading, unloading and warehousing, as well as for transportation by various modes of transport without repacking throughout their travel paths. The parameters and type of cargo units depend on the dimensions of the rolling stock and the dimensions of the cross sections of mine workings. At the same time, the dimensions and weight of cargo units are established based on the conditions for ensuring the maximum use of transport and lifting equipment.
Rice. 18.1 Unified Platform
Containers intended for the delivery of piece, liquid and bulk cargo are transported on platforms (Fig. 18.1). The main assembly units of the platform are the undercarriage 1 on which the plate is fixed 2, mechanism 3 fixing containers, restrictive racks 4 and end walls 5 . Depending on the carrying capacity of the platform, one or two containers can be installed on it. Packages or piece goods transported on the platform must be limited in length by end walls.
The practice of introducing container delivery of goods in coal mines has shown that containers, as enlarged cargo units, have a significant dead weight and, in addition, their return from the mine requires high costs. Therefore, in the future, the most common will be the packaging of goods using slings, which simplifies the organization of transport operations, since the packaging material is not returned to the surface. At the same time, the container coefficient and capital costs are significantly reduced.
Long loads, rails and pipes are transported formed into packages and fixed on double swivel carts (Fig. 18.2, a). The delivery of the package with rails from the mine warehouse to the horizon of the mine is carried out as follows. On the surface, using two cassettes, a package is formed 1 (see fig. 18.2, a) from rails or pipes weighing up to 3.5 tons and fix it on two swivel carts 2. A roller suspension is fixed on the package 3, which, before being lowered down the shaft, is introduced into the guides of the supporting suspension of the stand. Then the package, together with the carts, is lifted into the pile driver (Fig. 18.2, b), while one of the carts moves along the rails. When re-lifting the cage, the package is kept from vibrations by the rope of the additional winch 4. The descent of the stand with the package is carried out at a speed of not more than 4 m/s. In the near-shaft development, the package, together with the trolleys, is pulled in by a winch 5 in conjugation of the trunk with the near-stem yard. When the cage is slowly lowered, the package is installed by trolleys on the rail track with the help of a winch, along which it is delivered by an electric locomotive to the place of work.
Rice. 18.2. Formed package of rails on bogies ( a) and the package delivery scheme from the warehouse to the mine horizon ( b)
For the transportation of people along horizontal workings, passenger trolleys VPG-12 (Fig. 18.3) with six double seats and VPG-18 with six triple seats are used. The trolleys are equipped with hand-operated shoe brakes. To protect against electric shock in the event of a break in the contact wire, the body is grounded to the rails through the frame and half slopes.
Rice. 18.3. Passenger trolley VPG-12: 1 - carts; 2 - frame; 3 - body
In inclined workings (from 6 to 80°) for the transportation of people, special passenger cars of the VLN type with seats for 6 to 15 people can be used. These trolleys are moved by a single-ended rope haulage, which includes a rope, trailers and a small hoist equipped with main and additional safety brakes and other means in accordance with the PB. Cars for inclined workings, unlike cars for horizontal workings, are equipped with inclined seats and special parachute devices for catching and subsequent smooth braking of the car in the event of a break in the traction rope or hitch, or exceeding the permissible speed by 20%, the value of which should not exceed 5 m/s.
Various mechanisms and devices are used for efficient transportation of grain crops, flour, animal feed. One of them is the chain-drag conveyor. It can move bulk cargo both horizontally and at a certain slope. This device is used in granaries, elevators, mills, plants for the production of vegetable oils, animal feed, grain processing.
Design
The structure of the scraper conveyor includes the following main components:
- a closed metal case (usually a rectangular box);
- driving mechanism (reducer motor with chain transmission);
- linear sections;
- tension section.
The number and length of the linear sections of the chain conveyor can vary widely. If necessary, unloading sections with an autonomous electric drive are included in the design of the transport device.
Scraper Conveyor Features
As a working element of the scraper conveyor, a steel chain is used, on which rubberized or metal scrapers with an overlay made of polymeric material are attached. Strength parameters and chain configuration are selected depending on the planned load. Traction leaf chains are usually used.
Scrapers, as a rule, are made of heat-resistant steel and rubber-fabric overlays or polymer materials resistant to abrasion and chemical attack - caprolon, fluoroplast, etc.
In order to reduce sticking, increase wear resistance and extend the service life of the chain conveyor, the walls and bottom of its box can have a special polymer coating.
The main technical characteristics of the transport device include its overall dimensions, performance, power of the driving engine.
Conveyor Benefits
Chain conveyors manufactured by LLC NPP "Agromashregion" have such advantages as:
- simplicity of design, installation, operation and ongoing maintenance;
- wide choice of transported materials;
- high power and low power consumption of the drive;
- the possibility of equipping with sensors for the speed of the chain, monitoring its breakage and others.
scraper for conveyor
The scraper is necessary for cleaning the conveyor belts from contamination after the cargo has been transported. The belt itself is easily soiled, and at the same time, its service life is reduced.
Using this polyurethane product, you clean the conveyor belt for subsequent transportation, thereby increasing its service life. All you need to do is press a button, everything else happens automatically.
Why is it better to order a chain-drag conveyor from us?
LLC NPP "Agromashregion" produces reliable, inexpensive, productive and economical conveyors. Our experts are ready to provide you with a wide range of additional services for the delivery, installation, adjustment and repair of these transport devices.
PurposeThe chain scraper conveyor is designed for transportation of grain, products of its processing, as well as other bulk materials in a horizontal and inclined direction.
Principle of operationThe friction force of the product against the walls and bottom of the box is less than the internal friction force that occurs when the chain with the scrapers moves through the product layer, so the latter is carried away by the scrapers in the direction of the chain movement.
Design- Consists of sections: drive, a number of intermediate, tension.
- At the request of the customer, the conveyor can be equipped with additional unloading sections with an electric drive.
- The working body is a chain with metal or rubberized scrapers.
Grain, as a delicate product, has special requirements not only for storage and processing, but also for transportation. Scraper conveyors are the best choice for moving such sensitive material. With their help, grain is transported in three ways: horizontal, gently inclined and horizontally inclined.
Distinctive features of conveyors
- Most preferred for bulk products due to closed transport bed.
- The movement is carried out in a closed box, which reduces the release of dust into the environment.
- Transportation is possible simultaneously in the upper and lower boxes or in one of them to choose from. It is also possible to change the direction of movement in the opposite direction.
Thanks to the design features of the conveyor, even at full load, it is possible to quickly start and stop the equipment, and also to locate branch pipes at almost any point through which grain will be loaded and unloaded.
Conveyor control - automatic, remote.
Conveyor device:
- drive unit;
- drive and tension stations;
- loading and unloading nozzles;
- mounting hardware;
- a traction mechanism consisting of a chain break, product pressure sensors and the chain itself with rubber-coated scrapers stretched between two stars, one of which is located in the drive station, the other in the tension one.
The sections that are part of the conveyor box are of two types: unloading and walk-through. The shape of its cross section is rectangular. Sections of the pass-through type are assembled from the bottom and connected to the side walls with bolts. The working branch of the chain is the lower one, the idle branch is the upper one, and its support is carried out by the guides of the same name.
Chain conveyors in a full range of options are manufactured by SkandiaElevator. The breadth of the assortment provides scope for the implementation of a transport solution of any complexity.
Grain conveyors KTIF
Skandia KTIF Chain Conveyors are equipment for commercial use as a “main conveyor” designed for the horizontal conveying of flour, grains and various granular products. Its capabilities match those of Skandia SEI elevators.
Grain conveyors KTIF manufactured by SkandiaElevator fully comply with EC directives in mechanical engineering. They are made of galvanized galvanized material, classified as category II 2D/OD conveyors and designed to work with products in granular or powder form.
The company offers five models of this conveyor: 20/33-40, 20/33-60, 30/33-80, 30/33-100, 40/33-120.
The Nord motors used in this equipment vary in power, and depending on the model chosen, the speed of the conveyor chain may also be different. In accordance with it, suitable gearboxes are selected. The range of available conveyors is very diverse and covers all possible speed and power ranges.
The KTIF conveyor is designed for loading from Skandia SEI elevators. The theoretical performance depends on the speed of the gearbox shaft and corresponds to the following indicators: grain moisture 15%, bulk density - 750 kg/m³.
SkandiaElevator took into account the requirements and wishes of customers regarding the convenience, quality and performance of the produced transport equipment. Unique lines were created for him:
- I-line - productivity 20-150 t/h;
- H-line - productivity 60-600 t/h.
Top conveyor KTIF, forward and return conveyor KTIF FR
| Type of | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|
| Productivity, t/h | 48 | 71 | 89 | 115 | 139 |
| Productivity, m³/h | 64 | 95 | 119 | 154 | 185 |
| Chain speed, m/s | 0.45 | 0.59 | 0.51 | 0.65 | 0.55 |
| Pref. speed shaft rpm | 31 | 46 | 38 | 49 | 41 |
The basic equipment of the KTIF conveyor consists of the following elements:
- Nord reducer (Germany) with IP55 electric motor. 230/400 V (1.5-3.0 kW) resp. 400/690 V (from 4.0 kW) 50 Hz.
- Intermediate sections to desired conveyor length.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers located on steel spans. A cleaning scraper is provided every 5 meters of the chain.
- The return branch of the chain runs on plastic rollers mounted on centers of 1000 mm.
The basic equipment of the KTIF FR conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Tail section 1.0 m with chain tensioner and service hatch.
- Various intermediate sections with intermediate floor for forward and reverse transport.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have a steel bottom with a thickness of 2.5 mm.
- The reverse branch of the chain runs along plastic guides.
- 2 inlet/outlet pipes.
Bottom conveyor KTIFB, under-hopper receiving conveyor KTIFG
| Type of | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|
| Productivity, t/h | 41 | 61 | 78 | 101 | 124 |
| Productivity, m³/h | 55 | 81 | 104 | 135 | 166 |
| Chain speed, m/s | 0.45 | 0.59 | 0.51 | 0.65 | 0.55 |
| Pref. speed shaft rpm | 31 | 46 | 38 | 49 | 41 |
The basic equipment of the KTIFB conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Tail section 1.0 m with chain tensioner and service hatch.
- Various
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have a steel bottom with a thickness of 2.5 mm.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers mounted on steel spans. A cleaning scraper is located every 5 meters of the conveyor chain.
- The return branch of the chain runs on plastic rollers mounted at 1000 mm centers in a calibrated inlet on plastic guides.
- Outlet pipe.
The basic equipment of the KTIFg conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Reducer Nord (Germany) (4) with IP55 electric motor. 230/400 V (1.5-3.0 kW) resp. 400/690 V (from 4.0 kW) 50 Hz.
- Tail section 1.0 m with chain tensioner and service hatch.
- Under-bunker sections with supports, length is 2 m less than the total length of the conveyor.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have a steel bottom with a thickness of 2.5 mm.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers mounted on steel spans. A cleaning scraper is located every 5 meters of the conveyor chain. The return branch of the chain runs on plastic rollers mounted on centers of 1000 mm.
- Tail section inlet and drive section outlet.
Inclined top conveyor KTIA, curved top conveyor KTIB
| Type of | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|
| Productivity, t/h | 45 | 66 | 86 | 105 | 125 |
| Productivity, m³/h | 60 | 88 | 115 | 140 | 167 |
| Chain speed, m/s | 0.64 | 0.86 | 0.79 | 0.75 | 0.86 |
| Pref. speed shaft rpm | 44 | 65 | 57 | 52 | 62 |
The basic equipment of the KTIA conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Tail section 1.0 m with chain tensioner and service hatch.
- Intermediate sections for required conveyor length.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have a steel bottom with a thickness of 2.5 mm.
- Tail section inlet and drive section outlet.
The basic equipment of the KTIB conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Reducer "Nord" (Germany) with IP55 electric motor. 230/400 V (1.5-3.0 kW) resp. 400/690 V (from 4.0 kW) 50 Hz.
- Intermediate sections for required conveyor length.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have an intermediate floor for the return chain of the conveyor.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers mounted on steel spans.
- Outlet for drive section. The inlet pipe is included in a curved section.
Curved Bottom Conveyor KTIBU
| Type of | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|
| Productivity, t/h | 43 | 61 | 82 | 101 | 121 |
| Productivity, m³/h | 57 | 81 | 109 | 135 | 161 |
| Chain speed, m/s | 0.59 | 0.79 | 0.71 | 0.645 | 0.79 |
| Pref. speed shaft rpm | 42 | 60 | 54 | 50 | 60 |
The basic equipment of the KTIBU conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Reducer "Nord" (Germany) with IP55 electric motor. 230/400 V (1.5-3.0 kW) resp. 400/690 V (from 4.0 kW) 50 Hz. Power requirements are based on a 45º conveyor.
- Tail section 0.6 m with chain tensioner and service hatch.
- Horizontal conveyor sections with supporting support of required length.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have an intermediate floor for chain return.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers mounted on steel spans. A cleaning scraper is located every 5 meters of the conveyor chain.
- Power requirements are valid for tail section, curved section + straight conveyor. If the inclined part of the conveyor is lengthened, then the power requirements must be increased in accordance with KTIA.
Curved Under Hopper Intake Conveyor KTIG
| Type of | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|
| Productivity, t/h | 40 | 57 | 79 | 99 | 119 |
| Productivity, m³/h | 53 | 76 | 105 | 132 | 159 |
| Chain speed, m/s | 0.59 | 0.79 | 0.71 | 0.64 | 0.79 |
| Pref. speed shaft rpm | 42 | 60 | 54 | 50 | 60 |
The basic equipment of the KTIG conveyor consists of:
- Drive section 1.0 m with pressure sensor and microswitch in the top cover. Base frame for mounting all sizes of gearboxes included.
- Reducer "Nord" (Germany) with IP55 electric motor. 230/400 V (1.5-3.0 kW) resp. 400/690 V (from 4.0 kW) 50 Hz.
- Tail section 0.6 m with chain tensioner and service hatch.
- The under hopper sections with support legs are 1.6 m shorter than the entire conveyor.
- The drive section, tail section and intermediate sections are made of galvanized and galvanized material and have a steel bottom with a thickness of 2.5 mm.
- M80A-100 conveyor chain (breaking force 80 kN) with plastic scrapers mounted on steel spans. The return branch of the chain runs on plastic rollers mounted on centers of 1000 mm.
- The outlet is included in a curved section.
- The performance figures from the tables above, given in cubic meters per hour and tons per hour, are calculated based on the nominal shaft speed for grain with a moisture content of 15% and a specific gravity of 750 kg/m³.
Equipment performance
If the specific gravity of the material differs from the specified, you can calculate its performance by weight. To do this, you need to multiply the value of the productivity by volume, which is indicated in the table above, by the specific gravity of the desired material shown below:
If the conveyor is installed at an angle, the loss in productivity is 0% at a 5° incline, 5% at a 10° incline.
Need more information about this equipment? Download our brochures and .
Designed for transportation of wood chips with bulk density up to 300 kg/m3 relative humidity up to 80% with the possibility of intermediate unloading.| Specifications: | |||
| Performance* | t/h | up to 5.5 | |
| Bulk wood chips | kg/m3 | 300 | |
| Scraper speed | m/s | 0,46 | |
| Scraper pitch* | mm | 320 | |
| Scraper height* | mm | 200 | |
| Scraper width* | mm | 465 | |
| Installed power of electric motor drive* | kW | From 0.75 up to 15 |
|
| Drive type electromechanical | Coaxial-cyl. | MNF 3 Italy | |
| Dimensions: length Dimensions: width |
mm | up to 40000* | |
| up to 1400 | |||
| Height of intermediate unloading unit* | mm | up to 8000* up to 4000* | |
| Weight | kg | up to 7946 | |
| * Specified by the Customer in those. task | |||
In scraper conveyors, the movement of cargo is carried out by scrapers that move in the cavity of a pipe or trough. Such a transport scheme allows you to move bulk and lumpy goods, evenly entering the receiving opening through the hopper. The lower branch usually acts as a worker. Much less often upper or both at the same time. The shape of the scrapers must fully correspond to the section of the gutter and can be trapezoidal, rectangular or semicircular. Scrapers are made of steel by stamping or casting. Gutters are often metal, in some cases - wooden. The main advantages of scraper conveyors in comparison with apron conveyors are:
- low weight of the structure;
- the ability to load and unload anywhere along the route.
However, they are not without some drawbacks. In particular, when using them, it must be remembered that the transported cargo is subjected to grinding and leads to rapid wear of the gutters, especially if it is any kind of abrasive material. Scraper conveyors are rather uneconomical devices. This is due to the fact that when the load moves, a lot of resistance arises that must be overcome, and, accordingly, energy must be expended. On average, the speed of movement along the conveyor can reach 0.5 m/s, in some cases - 1.0 m/s, with a capacity of up to 350 t/h. Scraper conveyors are mainly used for organizing a transport scheme for a distance of up to 100 m.
There are modifications of scraper conveyors, in which the scrapers cover not the entire section of the chute, but only part of it. In this case, the transported cargo fills the entire cavity. They are effective for moving fine bulk materials, and their route can have sections with a horizontal, vertical and inclined direction of movement. The average speed of movement is 0.18 m/s. Tubular scraper conveyors are taken out in a separate group. In them, the scrapers, which fill the entire cross-sectional area, and the traction chain are placed in the pipe cavity. With the help of such devices it is possible to organize spatial transport schemes.
Unlike other types of conveyors, models equipped with driving and carrying chains do not have a load-carrying body and are used mainly in conveyor assembly shops. The initial load is placed directly on the traction chain, which moves through fixed guides. The movement of the load can be carried out on the surface of fixed support tracks, or directly on the floor of the workshop, being equipped with wheels or caterpillars. Quite often, in production workshops that provide for the serial assembly of equipment, trolley conveyors are used. In them, a closed traction chain is equipped with trolleys that move along a given path and play the role of a desktop for assembling a machine, individual components, or performing certain stages of foundry production (molding, pouring, cooling).
Scraper conveyors represent the bulk of the devices included in the group of continuous transport, in which the movement process is based on dragging the load along the deck, chute or by means of scrapers mounted on a traction mechanism. To date, there are several options for devices based on the above principle of operation. Among themselves, they differ in the nature of the interaction of the load with the scraper mechanism, the design of the chute, scraper, traction mechanism. In one of the modifications, the load is set in motion under the action of high scrapers, which rest on guides with their rollers. High scrapers are those whose height is equal to or greater than the height of the sides. In this case, the load moves in strictly defined proportions in front of the scraper.
Moving in this way inevitably causes friction of the load against the walls of the chute. Significant energy losses cannot be avoided. The dragging body (in simple terms, a portion of the load) must have a vertical size not exceeding the height of the side, otherwise overflow occurs, which is not permissible. The conveyors built on this principle are called batch conveyors. Their distinguishing feature is high scrapers that completely cover the cross section of the tray. They also include conveyors, the scrapers of which are equipped with side walls that act as movable sides, and the chute is used only as a bottom. The mobility of the sides has a positive effect on energy efficiency, since thanks to them, the number of resistances during the movement of the load is significantly reduced. Scrapers equipped with side walls are boxes that do not have a bottom. That is why they are usually called box-type conveyors with movable sides. They can also be equipped with scrapers with a height much lower than the height of the trough. This increases the speed of movement, but reduces productivity.
By continuous drawing, it is customary to understand the process, as a result of which the resulting adhesion force between the lower forcibly moved layer and the upper free layer significantly exceeds the sum of the friction forces that occur between the upper layer of the load and the walls of the chute, as well as the force required for descent and ascent. On the described principle, continuous drag conveyors with low scrapers work, which, compared to high ones, practically do not mix the load and do not contribute to its destruction. Cargo enters them through a branch of an idle chute or a hole in the lid. When using scrapers, the shape of which completely coincides with the outlines of the gutter, the adhesion force increases several times. This phenomenon makes it possible to use steeply inclined and even vertical sections in scraper conveyors. This design is typical for wire-drawn conveyors with contour scrapers. The friction force to a large extent also depends on such factors as the coherence of the load, its rolling at certain angles of natural inclination. Low scrapers are not effective with all types of cargo. Solid scrapers are considered more versatile, which allow you to cover the entire section of the gutter. This allows you to move the load in any direction and at any speed, regardless of its composition. These are tubular conveyors.
In conveyors of low productivity, scrapers may be completely absent. Their role is performed by a traction round link chain. Constantly making translational movements, the load picked up by the chain gradually moves along the working channel to its destination.
In rod conveyors, the traction body performs reciprocating movements during operation. The scraper moved along the movement of the load, before being in the mass of the load, has a perpendicular position relative to the traction body. At the moment of immersion, it folds, clinging to the chain as much as possible, and freely enters the material. At the moment of turning, the scraper turns again, taking up a perpendicular position, while capturing the next portion.
In these conveyors, rods, on which the scrapers are fixed with a hinge assembly, often act as a traction element. Transportation on such lifts of a cohesive load, such as metal chips or straw, is associated with such a negative phenomenon as the entrainment of the load by the scraper back into the tank. It is avoided by pullers (“ruffs”), which help to ensure that the scrapers are completely released until the moment of folding. A similar principle is used in conveyors, where rods play the role of a traction mechanism. There are the following types of scraper conveyors: portable, stationary, mobile wheeled, rotary, suspended and built-in machines. As a rule, a flexible traction element is a chain, which in some cases is replaced by a rope or tape.
If the chain is used as a traction mechanism, then the distance between the scrapers is equal to the chain pitch. Depending on the type of track, there are horizontal, vertical, inclined and combined containers. Each of them may have one or two working branches, reversible or single-acting. The number of contour chains in scraper conveyors can be different: one, two or three. Each of them is located parallel to each other. Depending on the location of the chain in space, single-chain conveyors can be vertically closed (the chain closes in a vertical plane) and horizontally closed. The chute can be open or closed (sealed). In some cases, it may be absent altogether. Key features and specifications:
- the occurrence of large resistances during movement, reducing energy efficiency and causing rapid wear of the scrapers and chute walls;
- significant restrictions on the range of movement of cargo;
- the speed of movement is 0.16-0.4 m/s, in some cases, for example, when moving coal and grain crops, it can reach 1 m/s.
The length of the transport scheme, made on the basis of a scraper conveyor, as a rule, does not exceed 100 meters, and only with rare exceptions, for example, when cleaning manure, can reach 200 meters. Its productivity is in a very wide range: from 10 to 900 t/h. Compared to belt and apron conveyors, drag conveyors have a small cross-sectional height. Among the advantages that they possess, first of all, I would like to highlight the simplicity of design, low height, versatility in terms of the type of cargo being transported (from bulk to poisonous and chemically active), high operational safety, tightness, which eliminates dustiness of the room and formation of an explosive mixture, ease of unloading at several points at once, automation of basic processes, etc. The disadvantages include the low energy efficiency, which has already been voiced more than once, which is associated with a significant consumption of electricity during operation, increased wear of parts during the transportation of abrasive goods, the noise created by the transported load, the inevitable occurrence of periodic jams as a result of jamming of the scrapers when folding. Scope: transportation of small, medium, large-sized, coherent and light-bulk cargo in various industries and the national economy.
Scraper conveyors are one of the most versatile types of transport, the length of the working body of which is much longer than that of a belt conveyor. This type of conveyor with an open chute is ideal for transporting bulk, cohesive and lumpy goods, with a hermetically closed one - for dusty, granular and small-sized. With the help of batch drawing conveyors equipped with high scrapers, products of the coal and food industries are moved. Continuous drag conveyors are mainly used in the food industry, where cereals, flour, bran, animal feed and other ingredients are transported. The chemical industry cannot do without them, in which they are used to organize the transport of lime, calcium carbide, granulated soot, soda, pesticides, soda, etc.
Solid drawing conveyors are also used:
- in the woodworking and pulp and paper industries for transporting ground lime, alumina, sulfur, chalk, sawdust, wood chips;
- in metallurgy for transportation of coke, bauxites, concentrates, crushed ore, non-ferrous metal cinders;
- in foundries for transporting sand, clay, earth;
- in the energy sector for the transportation of milled peat, fine coal, ashes, boiler and coal dust;
- in the transport sector for the organization of loading and unloading operations.