RU63259U1 - TECHNOLOGICAL COMPLEX FOR CLEANING AND DYNAMIC AIR-DRY ENRICHMENT OF GRAIN BULK MATERIAL - Google Patents

Abstract

The utility model is intended for purification and dynamic air-dry enrichment of granular bulk materials, for example, natural quartz sand.

The source material of natural moisture, for example, quartz sand, for exfoliating a surface film on particles and burning organic impurities, is briefly heated and then cooled in a drum dryer 1 and fed to a transport module 16 using an air pump 14, where it is rubbed and cleaned by friction of particles each other in a turbulent flow and on the walls of sand channels, which are formed by changing the direction of motion of particles up to 90 ° in, installed on the pneumatic pipeline of the transport module, 16 T-shaped tubes 31 and 36, with the output closed in the direction of movement of the sand stream, in two-way flow switches 38 having a design similar to T-shaped pipes and in segment bends 33 formed of four links in the form of hollow cylinders that are connected in series with each other and with a pneumatic line through a flange connection, moreover, one of the bases of the first three cylinders is beveled at an angle of 17-19 °, and one of the bases of the fourth cylinder is beveled at an angle of 35-37 °, the diameter of each cylinder refers to the length of the largest as 0.6: 1, the first link is connected by a direct base to the pneumatic channel channel, and the beveled base with the direct base of the second link, the second link is connected by the beveled base with the direct base of the third link, and the third and fourth links are connected by beveled bases in this way that form an acute angle, the fourth link with a direct base is connected with the continuation of the pneumatic pipe, and the cross-sectional area of each subsequent link is 1.1 times larger than the previous one, and the diameter of the internal channel of the pneumatic pipe refers to the inner diameter of the input and output links of the segment outlet, as 1: 2-2,15, and to the inner diameter of the flange connection, as 1: 1,2-1,3 and to the inner diameter of the channels of the T-shaped pipe, as 1: 1, 6. From the transport module, the material is fed into an intermediate tank 17 and a pneumatic classifier 21 for classification according to a given lower limit and additional cooling. The speed of the sand stream through the pneumatic pipeline is maintained within the limits providing maximum abrasion of particles of associated minerals having lower hardness than particles of the main material, for example quartz. The invention allows to obtain molding sand with a quartz content of 99% in the total mass of sand.

1 s.p.f. 9 zpf 9 pic.

Description

The utility model relates to devices for mechanical cleaning of the surface of bulk granular materials, in particular, natural quartz sand, and their enrichment, and can be used in mining, chemical, metallurgical, mining, agriculture, in the production of building materials and other industries .

Quartz natural sands are minerals, are natural chemical compounds, the mineralogical composition of which determines the scope of their application. The main substance that forms the grain part of sand is quartz in the form of silica (silicon oxide), which is up to 99% of the total mass of each particle, and the rest is made-up “secular films” containing oxides and hydrates of iron oxides, sulfates, sodium carbonates , potassium, magnesium and other inorganic substances. Moreover, silica accounts for 90-97% of the total mass of sand, and the rest of the sand mass is associated minerals: aluminosilicates, mica, feldspars and other minerals, as well as silty inclusions and other mineral products.

One of the main areas of application of natural quartz sand is their use as molding material in the manufacture of foundry molds and cores. In this case, the main criteria for the initial preparation of molding sand for use are:

- the content of quartz in each particle in the range of 99-99.5%;

- the content of quartz in the total mass of sand in the range of 97-98.5%;

- the content of oxides and hydrates of iron oxides in the particles of not more than 0.3-0.5%;

- the content of sulfates, carbonates and other alkaline components in the particles is not more than 0.3-0.4%;

- the content of clay inclusions in the mass of sand is not more than 0.2%;

- moisture mass of sand not more than 0.2

- the content of associated minerals in the mass of sand is not more than 0.3-0.6%.

Therefore, before using sand as a molding material, it is pre-washed, dried and enriched.

A device for cleaning sand from harmful impurities, comprising a housing, a shaft with a drive, oval disks with holes located at an angle to the shaft and to each other, where, to increase the frequency of contact of the grains of material with each other and with the disks, the shaft and disks are hollow, moreover, the disks are mounted relative to the shaft with an inclination, in two mutually perpendicular directions relative to the major and minor axes of the oval (SU No. 1166819, 03 V 1/00, publ. 07.15.1985).

A disadvantage of the known device is that the cleaning of sand from harmful impurities is inactive throughout the entire volume of the sand mass and in this regard, the required quality is not provided.

A device is known that contains a container equipped with an inlet and outlet for bulk material and equipped for forming a fluidized bed with a perforated bottom and a gas-permeable base, above which at least one nozzle is connected, connected to a source of compressed air, and for fluidizing the material, compressed air is supplied to the capacity below the nozzle through the pipeline (RU No. 2044576, 07 V 9/00, publ. 09/27/95).

The disadvantage of this device is low productivity, low quality cleaning and enrichment of bulk material.

Closest to the proposed device is a technological complex for air-dry enrichment of bulk materials, which contains sequentially interconnected loading unit, a vibrating dryer and a dynamic air-dry enrichment unit, including an accelerating pipe with a high-pressure fan, connected at the outlet to a separation a camera equipped with a baffle plate with a vibration exciter, a vertical vibroclassifier with a cascade of inclined patter screens installed under each other with large fraction withdrawals and an air classifier of small fractions, the installation also contains fraction storage bins and transport lines for unloading fractions from storage bins and returning fractions to the loading unit, as well as a mechanism for transferring flows from the corresponding transport lines for supplying finished products to the fraction return line and aspiration system, associated with the dividing and horizontal chambers and under the sieve spaces of vibration classifiers (SU No. 1752451, B 07 B 4/00, published 07.08.92).

This device provides the possibility of operational independent cleaning of each fraction to improve the quality of enrichment.

The disadvantages of the known device include the complexity of the design, energy consumption and low quality of cleaning, due to shock-vibration impact on the material when impacted with a break-off metal shield in the separation chamber of the vibration classifier, which is the source of the appearance of harmful impurities in the commercial material in the form of metal powder, as a result of collision, for example, of quartz sand (abrasive) with a break-away metal shield, moreover, the metal powder, in density as a substance, is more than twice as large Chez than quartz density and output it as the dust particles is almost impossible.

The objective of the proposed technical solution is to improve the quality of the target product by increasing the degree of purification and enrichment, as well as reducing the energy intensity of the process and simplifying the process and design of the installation.

The specified task is implemented using a technological complex that includes a loading unit, a drying circuit, a cleaning and dynamic air-dry enrichment unit, a classification and cooling scheme, a finished product storage tank, a substandard material collection scheme, and an aspiration system, in which according to According to the invention, the drying scheme includes a horizontally mounted drum dryer, with a drum installed with a slope of 2-8 ° in the direction of movement of the bulk material and with to a circular sieve fixed at the end of the drum, under which a distribution tank is installed for collecting bulk material leaving the dryer, the installation of dynamic air-dry enrichment and cleaning of bulk material includes at least one transport module that contains straight sections oriented horizontally, vertically and inclinedly pneumatic pipelines connected to each other through T-shaped pipes and segment bends, and the initial section of the pneumatic piping is horizontal and at The ode is connected to one of the chambers of a two- or three-chamber pneumatic pump, each chamber of which is connected to a distribution tank, and the output of the horizontal section of the pneumatic pipe is connected to the vertical section of the pneumatic pipe through a T-shaped pipe with a damped horizontal output channel, and the remaining sections of the pneumatic pipe are interconnected via segment bends, each of which is a structure consisting of four links in the form of hollow cylinders, connected in series with each other by means of a tsevogo compounds wherein one of

the bases of the first three cylinders are beveled at an angle of 18 °, and one of the bases of the fourth cylinder is beveled at an angle of 36 °, the first link is connected with a direct base to the air duct channel, and the beveled base with a direct base of the second link, the second link is connected with a beveled base with a direct base of the third link , the third and fourth links are interconnected by beveled bases in such a way that they form an acute angle, and the fourth link is connected by a direct base to the continuation of the air line, the diameter of each cylinder is the length of the largest side, as 0.6: 1, and the cross section of each subsequent link is 1.1 times larger than the previous one, and the diameter of the internal channel of the pneumatic pipe refers to the inner diameter of the input and output links of the segment outlet, as 1: 2-2.15 , to the inner diameter of the flange connection, as 1: 1.2-1.3, and to the inner diameter of the channels of the T-shaped pipe, as 1: 1.6.

The transport module additionally includes at least two auxiliary vertical pneumatic pipelines of different lengths, each of which is connected to the initial horizontal section of the main pneumatic piping through additional T-shaped pipes with shut-off valves installed on the horizontal and upward vertical outlet channels of the pipe, and a short pneumatic pipe is connected with a long through a T-shaped pipe mounted on its upper end with an outlet muffled in the direction of movement of the material flow, and through an angular two-way flow switch, and a long pneumatic pipeline is in turn connected through a T-shaped pipe with an outlet muffled in the direction of movement of the material flow installed on the upper end of the pneumatic pipeline, and through a two-way flow switch connected to a vertical section of the main pneumatic pipeline.

The classification and cooling scheme includes an intermediate tank, a dust separator tank that acts as a damper and at least one pneumatic classifier, an intermediate tank is connected to the outlet of the final section of each pneumatic pipe through a T-shaped pipe with a muffled horizontal outlet and a vertical output channel pointing downward to the walls of which in the last third of its length are made through holes arranged evenly around the circumference in two rows, and spray installed inside in the form of a screw with a rubberized fixed screw; on the cover of the intermediate tank there is a tap with a non-return valve designed to enter atmospheric air into the tank, and the tap section is equal to the section of the pneumatic duct channels,

the lower conical parts of the intermediate tank and the dust collector tank are connected with the atmosphere through the shut-off valve, and the upper parts of the intermediate tank and the dust collector tank are connected by a pipeline, the cross section of which exceeds the cross-section of the pneumatic pipe channels by 2-2.5 times; the lower conical part of the intermediate tank is connected by a pipe inclined at an angle of 35-40 ° to the vertical with the upper part of the pneumatic classifier housing, the pneumatic classifier has a cylindrical body with a conical outlet connected to the storage tank, in the pneumatic classifier cavity on the housing cover in front of the outlet of the inclined pipeline, a vertical the plate, and under it is installed, as a continuation of the inclined pipeline, the guide plate, which form a flat gap between them, under a perforated plate with a hole diameter of 3-5 mm, which occupies half the section of the pneumatic classifier from the inlet side, an inlet channel for supplying atmospheric air is made under the perforated plate at a half height of the pneumatic classifier; an outlet channel is made above it to draw air out of the classifier cavity, and the cross-sections of these channels correspond to the cross-section of the cylindrical part of the pneumatic classifier housing as 1: 1: 9;

The substandard product collection scheme includes the inclined lower part of the bottom of the exhaust chamber of the dryer, connected by a vertical loading channel to the inlet of the pneumatic pump chamber, the outlet of which is connected by a pipeline to the storage tank of the substandard product.

Each functional unit of the technological complex has its own isolated aspiration system.

Figure 1 presents the General scheme of the technological complex.

Figure 2 - diagram of the pneumatic installation of a dynamic air-dry enrichment.

Figure 3 is an intermediate tank, view aa.

Figure 4 - intermediate capacity, view GG.

Figure 5 - spray installed in the intermediate tank.

Figure 6 - pneumatic classifier view BB.

In Fig.7 - pneumatic classifier, view BB.

On Fig - segment retraction.

In Fig.9 - T-shaped pipe.

The technological complex contains a dryer 1 with a rotating drum mounted obliquely in the direction of movement of bulk material with an angle of inclination of 2 ÷ 8 ° to the horizontal with a circular sieve rigidly installed at the end of the drum, which also includes a furnace with a burner and pipelines for supplying fuel and compressed air (for diagram not shown); node 2 for feeding the source material into the dryer 1; distribution tank 3 with loading channels 4, an exhaust chamber 5 connected by a pipe 6 to the chamber of the pneumatic pump 7, equipped with a compressed air supply line 8 with a control panel for supplying compressed air 9 and a pipe 10 connecting the pneumatic pump 7 with a tank 11 for collecting and storing substandard material, having a discharge pipe 12 with a shut-off valve 13; an air-dry enrichment purification unit including at least one transport module 16 (two transport modules are shown in FIG. 1) and at least one two- or three-chamber pneumatic pump 14 (one two-chamber pneumatic pump is shown in FIG. 1), which is equipped with supply lines compressed air 15, from the console 9, and each chamber of the air pump is connected by pipelines 4 with a capacity of 3 and with a horizontal pneumatic pipe, which is the initial section of the transport module 16, the output of which is connected to an intermediate tank 17 of cylindrical shape , the lower conical part of which through the pipe 18 with shut-off valves 19 is connected to the atmosphere, and the pipe 20 inclined at an angle of 35-40 ° to the vertical is connected to the pneumatic classifier 21. The upper cylindrical part of the tank 17 is connected by a pipe 22 to the dust collector 23, which performs the function the damper and consists of two cylindrical chambers interconnected by a cylindrical part, which are equipped with partitions 24, and the conical parts of the chambers, designed to collect dust, through nozzles 25 with shutoff valves 26 connected to the atmosphere. On the lid of the tank 17 there is an outlet 27 with a check valve 28 (see Fig. 3), intended only for supplying atmospheric air to the tank, and inside the tank 17 in the upper part of the housing wall T-shaped pipes 29 with a damped horizontal outlet and directional down with a vertical output channel (see Fig. 5), on the walls of which in the last third of its length there are through holes arranged evenly around the circumference in two rows, and inside there are mounted nozzles 30 in the form of a screw with a rubberized fixed screw, count honors the T-shaped pipes

29 corresponds to the number of transport modules, and the input of each T-shaped pipe is connected to the output of the transport module 16. The transport module 16 (see Fig. 2) includes a pneumatic pipe, which contains straight sections oriented in horizontal, vertical and inclined directions, interconnected through T-shaped pipes and segment bends, the initial section of the pneumatic pipe being horizontal and its inlet connected to one of the chambers of the air pump 14, and a T-shaped pipe 31 with muffled g With a horizontal outlet, in addition, there are two additional T-shaped branch pipes 31 with shut-off valves 32 on the horizontal pneumatic line, the vertical outlet of the T-shaped branch pipe 31 with a muffled horizontal outlet is connected to the vertical section of the main pneumatic pipe, consisting of series-connected vertical, inclined and horizontal sections, between which segment bends 33 are installed, each containing four links “a”, “b”, “c” and “d” in the form of hollow cylinders, with the links “a”, “b”, “c” they are of the same type and each has a lower straight base and an upper one, beveled at an angle of 18 ± 1 °, where ± 1 ° is the permissible deviation in accordance with tolerances and fittings on smooth cylindrical mates (V.D. Myagkov “Designer Quick Reference”, Mashizdat. M: 1963, pp. 30-63), the ratio of the diameter of the link to its largest side is 0.6: 1, and the link "g" has an upper straight base and a lower beveled angle of 36 ± 1 °, the ratio of the diameter of the link to the largest side 0.6: 1. The segments of the segment outlet 33 are interconnected by means of flange connections, and the cross-sectional area of the link “b” is larger than the cross-sectional area of the link “a”, but 1.1 times less than the cross-sectional area of the “c” section, and the links “c” and “g” are connected to each other with other beveled bases, so that they form an acute angle (54 ± 1 °), the ratio of the inner diameter of the pneumatic duct channels to the inner diameter of the input (“a”) and output (“g”) links of the segment branch 33 is 1: 2-2 , 15, and to the inner diameter of the flange connection 1: 1.2-1.3; the transport module 16 also includes two auxiliary vertical sections of the pneumatic conduit 34 and 35 of different lengths connected to the vertical exits of the through-passage T-shaped nozzles 31 through shut-off valves 37, the short pneumatic conduit being connected to the long pneumatic conduit through the T-shaped nozzle 36 with a muffled vertical outlet installed at the upper end of the air line and through an angular two-way flow switch 38, which has a design similar to a T-shaped nozzle in the process

the process performs a similar function, and the long pneumatic pipe, in turn, is also connected through a similar T-shaped pipe 36 and through an angular two-way flow switch 38 to the vertical section of the main pneumatic pipe of the transport module 16. Inside the pneumatic classifier 21 at a certain distance from the input of the inclined pipe 20 to the housing cover a vertical plate 39 is fixed to the pneumatic classifier and a guide plate 40 is installed under the inlet of the pipeline 20, as a continuation of the pipeline 20, (i.e., the angle of inclination, tvetstvuyuet angle conduit 20) under the plate 40 at half height pnevmoklassifikatora body 21 installed inclined at an angle of 35-40 ° to the horizontal plate 41 perforated with holes 3-5 mm in diameter, which is located under the inlet conduit 42 for supplying air. The pneumatic classifier 21 is communicated with a lower conical part with a storage tank 43 of a commodity product, which at the outlet is equipped with a discharge pipe 44 with a shut-off damper 45. All functional units of the technological complex are equipped with their own insulated aspiration system, namely, the exhaust chamber 5 is connected via a line 46 to the dust removal unit 47 and through the control flap 48 with the atmosphere, tanks 17 and 23 are connected via line 50 to the dedusting unit 51 and through the control flap 49 with the atmosphere, a pneumatic classifier 21 is connected via line 53 with is one with the dust removal unit 54 and through the control damper 52 with the atmosphere, the storage tank 43 and the lower part of the loading pipe 44 are connected via line 56 to the dust control unit 57 and through the control damper 55 with the atmosphere, and the storage tank 11 for substandard material and the lower part boot pipe 12 through line 59 are connected to the dust removal unit 60 and through the control valve 58 with the atmosphere.

Depending on the productivity of the technological complex, the installation for cleaning and dynamic air-dry enrichment of granular granular material may include several transport modules 16 and two-three-chamber air pumps 14, which operate in parallel. In Fig. 1, two transport modules 16 are shown connected with one double-chamber pneumatic pump 14.

The technological complex works as follows:

The source material, for example, quartz sand of natural humidity through an inclined conveyor of unit 2, continuously enters the dryer 1, where it is heated to a temperature of 573-600 ° C in the loading chamber to destroy the polluting

film "on the surface of particles and complete combustion of silty inclusions, during rotation of the dryer drum 1, the material is mixed, dried to the desired residual moisture, cooled to a temperature of 110-145 ° C due to suction of atmospheric air through openings structurally provided on the dryer drum, and at the same time moves due to the inclination of the drum to the outlet of the dryer, then it is sifted through a circular polygonal sieve to the distribution tank 3 through an inclined output outlet, and the substandard material: clay ag omerates, random particles of another material, particles of a larger size than those specified by the technological process, etc., due to the inclination of the sieve, its edge comes out, under the action of gravity it enters the lower part of the exhaust chamber 5 and is loaded into the chamber through a pipe 6 air pump 7, where after filling it to a predetermined level, the camera’s level meter gives a signal to the control panel 9 for short-term closing of the pipeline 6 and supplying compressed air through line 8 to the chamber of the air pump 7 to move the assembled substandard material the pipe through pipe 10 to the storage tank 11. After the chamber of the pneumatic pump 7 is completely emptied, the level gauge sends a signal to the control panel 9 to stop the supply of compressed air and open the pipe 6 to load the next portion of substandard material into the chamber of the pneumatic pump 7. At the same time, the dried bulk material from the dryer drum through a circular sieve enters the distribution tank 3 under the action of gravity through one of the pipelines 4 is moved to one of the chambers of the air pump 14 and after filling the chamber to a predetermined level, the camera’s transmitter sends a signal to the control panel 9 to close the pipeline 4 for loading into this chamber with switching the supply of material through the second pipeline 4 to another chamber of the air pump 14 with the supply of compressed air through the line 15 to the first chamber of the air pump 14 to move a portion of the material on the initial horizontal section of the pneumatic pipeline transport module 16 to the next stage of the process.

Moreover, the source material, before processing, is subjected to mandatory analysis for the chemical composition of the particles of the bulk material and the chemical composition of the mass of the bulk material and the parameters of the process are established according to the results of the analysis.

In the presence of a small percentage of harmful impurities, the dried material is passed from the drying circuit through a cleaning unit and dynamic air-dry

enrichment in mode I, with the lowest velocity of the material flow, i.e. along the initial horizontal section of the pneumatic pipeline through the vertical outlet of the first T-shaped pipe 31 with a closed shut-off valve 32, an open shut-off valve 37, through a short additional vertical pneumatic pipe 35, through a T-shaped pipe 36, a two-way flow switch 38, the upper part of a long additional vertical pneumatic pipe 34, through the next T-shaped pipe 36, two-way flow switch 38, the upper part of the vertical section of the main pneumatic pipe, the first segment tap 33, inclined This is the main section of the main air line, the second segment branch 33, the horizontal section at the inlet of the tank 17.

In the presence of an average percentage of harmful impurities, the dried material is passed from the drying circuit through a dynamic air-dry enrichment purification unit in mode II with an average material flow movement, i.e. along the initial horizontal section of the pneumatic pipe through the first T-shaped pipe 31 with a closed shutter 37 and an open shutter 32, a horizontal shutter, because the vertical exit of the T-nozzle is closed, the material flow passes into the second tee 31 with the shut-off valve 32 and is directed through the vertical exit of the second T-nozzle with the open damper 37 to the long additional vertical air line 34, then through the T-shaped nozzle 36 with the drowned vertical output, two-way flow switch 38, the upper part of the vertical section of the main pneumatic pipeline, through the first segment branch 33, the inclined section of the pneumatic pipe, the second segment branch 33 horizontal part of the pneumatic line to the inlet of the tank 17.

In the presence of a large amount of harmful impurities, the material is passed from the drying circuit through the treatment unit and dynamic air-dry enrichment in mode III with the maximum estimated speed of the material flow, i.e. along the initial horizontal section of the pneumatic pipeline through both T-shaped nozzle 31 with closed vertical shut-off valves 37 and open horizontal shut-off valves 32, through the vertical outlet of the T-shaped nozzle 31 with a constantly muffled horizontal outlet, the vertical section of the main pneumatic pipeline, then through the first segment outlet 33 , the inclined section of the pneumatic pipe, the second segmented tap 33, the horizontal section of the pneumatic pipe to the inlet of the tank 17.

Then the material flow enters the tank 17, through the T-shaped pipe 29 the horizontal outlet of which is always muffled, and a sprayer 30 is installed in the vertical outlet channel downward and through holes are made in the channel walls.

T-shaped nozzles 31, 36 and a two-way flow switch 38, having a similar design to the T-shaped nozzle 31, work the same way, although the nozzles 36 are made with a permanent plug on one of the output channels, and the nozzles 31 are continuous, but with the horizontal shut-off valves 32 closed installed behind the nozzles in the direction of movement of the material, are full analogues of the nozzles 36.

In segmented bends, T-shaped nozzles and in two-way flow switches, the surface of the particles is rubbed and peeled off due to their friction against each other in the turbulent flow and on the walls of the sand channels that are formed inside the T-shaped nozzles and segments of the segmented branch due to a change in direction movement of particles and expansion of the diameter of the flow at the boundary of the connection of the pneumatic conduit and the links of the seminal outlet (through a flange connection) or a T-shaped pipe.

In this case, in the segment bends, the process proceeds as follows: initially the bulk volume of the link is filled, then, under the pressure of compressed air, the bulk mass moves along the path of least resistance and is directed upward through the flange connection to the next link, forming an additional channel with a smaller cross section than the cross section link channel, consisting of a fixed layer of bulk material between the wall of the link and the resulting flow of bulk material, where as a result of compression of the flow and friction of the particles about each other there is a constant change of the near-wall layer of the flow and the layer of the stationary layer of granular material with scrubbing and peeling of the surface film from particles of granular material and with intensive abrasion of softer minerals.

A similar process takes place in T-shaped nozzles, for a given ratio of the sections of the output channels of the T-shaped nozzles and the sections of the pneumatic duct channels equal to 1.6: 1 during the transportation of bulk material through the transport module, first the horizontal space of the T-shaped nozzle is filled to the plug, and then, under the pressure of compressed air, the granular mass is directed upward along the pipe channel, forming a channel with a smaller cross section than the channel section of the T-shaped pipe with an additional stationary layer of granular about

material between the wall of the T-shaped pipe and the resulting flow from bulk material, where as a result of compression of the flow and friction of the particles against each other, the surface film is scrubbed from the particles of the bulk material and the soft materials are worn away.

Bulk material passing through the transport module 16, including particles cleaned from the surface film and the entire mass formed during the cleaning and enrichment process, consisting of fine dust and fragments of minerals smaller than 100 microns, is sent to the intermediate tank 17, from which through the pipe 22 the bulk of the coarser dust is discharged into the container 23, which by design acts as a damper, i.e. it is designed to smooth out sharp pneumatic shocks in the cooling and dedusting scheme, as well as to deposit medium and coarse dust fractions, and the fine dust fraction along line 50 is collected by the dedusting unit 51. After the portion of bulk material is transported to the container 17, the compressed air supply stops due to the operation of the fan of the dedusting unit 51, the valve 28 opens and through the outlet 27, atmospheric air begins to flow into the container 17 to cool the bulk material, which due to gravity pipe 20 moves to the pneumatic classifier 21, where due to the vertical 39 and inclined 40 plates the material flow is distributed along their width and poured through the gap between them onto the inclined perforated plate 41, rolled along it and sifted through holes, being divided into small unconnected trickles, which are cooled and simultaneously classified according to a predetermined lower limit (dedusted) by the flow of atmospheric air entering through inlet 42 due to the operation of the fan Nia 54, creating air flow inside pnevmoklassifikatora 21, the speed of which is regulated by valve 52 and is set equal to half the maximum speed Withania particle enriched fraction. After cooling and classification, the purified and enriched bulk material through the outlet pipe in the conical part of the classifier 21 is stored and dispensed to consumers in the storage tank 43, which is constantly in the dedusting mode along line 56 and the dedusting unit 57 with flow rate control by the damper 55. First the dedusting stage is carried out before transporting the granular mass through the transport module 16 from the exhaust chamber 5 along line 46 by the dedusting unit 47, where the flow rate is controlled by a shutter oh 48. Work

dedusting unit 60 is carried out both in the mode of loading the tank, and in the mode of emptying the tank, where the flow rate is regulated by the valve 58.

The angle of the drum in the range from 2-8 ° is determined by calculation and is one of the conditions for regulating the residence time of the bulk material in the dryer, taking into account the technical characteristics of the dryer to ensure the moisture content of the bulk material leaving the dryer is not more than 0.2% and depends on the following characteristics:

- the number of drum revolutions indicated in the passport data of drum dryers, for example, for drum dryers manufactured by Uralhimmash and the Progress plant in Berdichev, this figure is in the range from 5.0 to 9 rpm (P.D. Lebedev and others . "Thermal insulation installations of industrial enterprises" Course design. Publishing house "Energy", M; 1970, p.100-103);

- the value of the voltage of the drum by moisture (the maximum possible amount of evaporation of moisture from the processed material in 1 hour per 1 m ^{3 of the} volume of the drum depending on the value of the initial and specified final humidity), for example, for quartz sand, the voltage of the dryer drum is on average 80- 88 kg / m h (see ibid. P. 103, Table 5-3, p. 14), and under certain conditions it can reach 100-120 kg / m ³ (A.G. Kasatkin “The main processes and apparatuses of chemical technology "Publishing house" Chemistry ", M; 1971, p.656);

- the degree of filling of the drum with material, and depending on the technical characteristics of the drum its filling with bulk material can reach up to 20% of its volume;

- the moisture content of the starting bulk material, which is determined before loading the material into the dryer, for example, the natural humidity of silica sand, ranges from 3.5% in hot, dry summers and up to 6.5% in rainy and cold, wet seasons;

As an example, confirming the possibility of obtaining a finished material (for example, quartz sand) with a final moisture content of not more than 0.2% for drum tilt values in the range of 2-8 °, a drum dryer with a length of L = 6.0 m and having a working volume of 4 , 7 m ³ .

Provided that the moisture stress value for quartz sand is 80 kg / m ³ h, the total voltage in the drum volume will be:

W = 80 × 4.7 = 376 kg / h, is the amount of moisture removed by drying the bulk material from the drum for an hour.

Provided that the drum is filled with 20% material, the volume of loaded sand will be: 4.7 m ³ × 0.2 = 0.94 m ³

then, the weight of the loaded sand will be:

0.94 m ³ × ρ _us = 0.94 m ³ × 1565 kg / m ³ = 1471.1 kg,

where ρ _us is the bulk density of quartz sand, which is 1565 kg / m ³ .

We determine the maximum drying capacity of quartz sand in a drum dryer by evaporated moisture in 1 hour using the basic equation of the material balance of drying:

Where,

W is the amount of moisture removed from the material (376 kg / h);

w _{n is the} initial moisture content of the starting bulk material (taken from the range of natural moisture of 3.5%, 4.5% and 6.5%);

w _to - the final moisture content of the dried material (0.2%).

(K.F. Pavlov et al. “Examples and tasks on the course of processes and chemical apparatuses) technology” Goskhimizdat, L; 1961, p. 272).

We calculate the amount of dried material (G ₂ ) according to a given amount of removed moisture W (376 kg / h) depending on the value of the initial and final moisture content of the material according to the equation derived from equation (1).

For w _n = 6.5%

Similarly, we determine the amount of dried material at the initial moisture content of 4.5% and 3.5%:

when w _n = 4.5% G ₂ = 8350.7 kg / h;

with w _n = 3.5% G ₂ = 10995.1 kg / h

Next, we analyze the drying process of quartz sand, depending on the slope of the drum in the range of 2-8 ° and on the rotation speed of the drum in the range from 0.5 to 9.0 rpm.

1. It was established by calculation that at a drum angle of 2 °, the mass of sand with a volume of 0.94 m ³ per revolution of the drum will move in the direction of the drum at a distance l = 40 mm, and at an angle of 8 ° at a distance l ₁ = 160 mm .

2. At a minimum drum rotation speed of 0.5 rpm, 1 revolution is made for t = 120 seconds, then to move the entire mass of material with a volume of V = 0.94 m ³ to a distance L = 6.0 m with a drum angle of 2 ° required number of revolutions equal to: C _about = L: l = 6000: 40 = 150 (vol.).

Where does the time t ¹ for moving the mass V = 0.94 m ³ along the length L equal to:

t ¹ = С _rev × t = 150 × 120 = 18000 sec (5 hours)

those. hourly productivity of movement is equal to:

0.94 m ³ or 1471.1 kg: 5 = 294.22 kg / h.

In a similar way, we calculate the hourly capacity of the dryer depending on the maximum drum rotation speed (9.0 rpm) at an angle of inclination of 2 ° and on the minimum and maximum drum rotation speed (0.5 and 9.0 rpm) at an angle of inclination 8 °. The results are presented in the table. one

Table 1 Drum angle 2 ° 8 ° Drum rotation speed, rpm 0.5 9.0 0.5 9.0 Dryer productivity kg / h 294.22 2648.8 1176.9 10591.9

Based on the above, it follows that to obtain a given amount of the final product in the range from 5580 to 11000 kg / h, taking into account the initial moisture content of the starting bulk material in the range from 3.5 to 6.5% according to the basic equation of the material balance of drying (1) for a given the amount of moisture removed is possible with an adjustable tilt of the dryer drum within 2-8 °. Moreover, the higher the initial moisture content of the material, the smaller the angle of inclination of the drum is required. With a slope of less than 2 °, the material will practically not move towards the exit; with a slope of more than 8 °, the material will leave the dryer insufficiently dried, which will subsequently affect the quality of the finished product.

The selected interval of values of the angle of inclination of the pipe 20 and the perforated plate 41 is justified as follows. Due to the fact that the natural slope angle of finely divided bulk material with a particle size of 0.1 to 1 mm, for example, quartz sand (the angle at which the bulk material is on an inclined plane at rest, i.e. does not crumble), is, depending on humidity, 29-33 °, so that the material being processed is evenly poured along an inclined pipe 20 from an intermediate container 17 into a pneumatic classifier 21 and along a plate 41 installed in the air classifier 21, the slope of the pipe 20 and plate 41 should be at least 35 ° . An increase in the slope of more than 40 ° is not advisable, because will lead to an increase in the volume of bulk material entering dust removal and cooling in the pneumatic classifier 21, which in turn will lead to an increase in the dust content in the target product and an increase in the temperature of the finished product at the outlet of the pneumatic classifier.

The inclined perforated plate 41 can be made with holes of various diameters in the range from 3 to 5 mm., Which are necessary for converting the bound flow of granular material into unbound (distribution on a separate trickle) to facilitate the process of dust removal and additional cooling of the processed material. When the hole diameter is less than 3 mm, most of the material will slip past the holes without being distributed into separate trickles, and vice versa, when the hole diameter is more than 5 mm, too large trickles will be obtained, which in both cases worsens the dust removal and cooling process and leads to a decrease in the quality of the target product.

The ratio of the inner diameter of the pneumatic duct channel to the inner diameter of the flange connection within 1: 1.2-1.3 and to the inner diameter of the input and output links 1: 2, -2.15 is necessary for guaranteed formation in the cavity of the segments of the segmented removal of sand channels in which scouring and exfoliation of the surface layer on the particles of the processed material. If the ratio of the inner diameter of the pneumatic duct channel to the inner diameter of the flange connection is less than 1.2, this will lead to abrasion of the flange material, and to the inner diameter of the input and output segments of the segment outlet less than 2, this will increase the resistance of the walls of the links and increase the friction between the particles, which ultimately lead to an increase in the content of dusty particles and a smaller final product.

Exceeding the ratio of the inner diameter of the pneumatic duct channel to the inner diameter of the input and output links of more than 2.15 will lead to the cessation of the process of scouring and exfoliation of the particle surface and, accordingly, to reduce the quality of the finished product.

Exceeding the ratio of the inner diameter of the pneumatic duct channel to the inner diameter of the flange connection more than 1.3 will violate the conditions for the ratio of the inner diameter of the pneumatic duct channel to the inner diameter of the input and output links 1: 2, -2.15.

An increase in the cross-section of the pipeline connecting the upper parts of the intermediate tank and the dust collector tank with respect to the cross-section of the pneumatic pipe is not less than 2 times necessary to prevent larger particles (target fractions) from falling into this pipeline along with dust-like particles, and increase the pipe cross-section by more than 2.5 times does not make sense.

Example. Spent enrichment of a batch of quartz sand fraction 0.3 according to GOST 2138-92 weighing 200 kg. on the installation described above with the following technical characteristics: in the segment bends, the bases of the first three cylinders are beveled at an angle of 18 °, the base of the fourth cylinder is beveled at an angle of 36 °, the inner diameter of the air duct channels is 1: 2 in the inner diameter of the input and output segments of the segment branch, and to the inner diameter of the flange connection as 1: 1.25. The pipeline connecting the intermediate tank with the pneumatic classifier and the perforated plate in the pneumatic classifier have a slope of 37 ° to the horizontal, the perforated plate has holes with a diameter of 3.5-4 mm. The cross-section of the pipeline connecting the intermediate tank with the dust collector exceeds the cross-section of the channels of the pneumatic pipe by 2 times.

A preliminary analysis was carried out on the chemical composition of quartz sand, moisture content, pH of the aqueous extract and the presence of clay inclusions in the mass of sand of each portion.

We used a convective dryer with a productivity of up to 100 kg / h on dry material, the angle of the drum was set to 6 °, taking into account the initial moisture content of the material - 3.8%.

The selected batch was loaded into a drum dryer into which flue gases with a temperature of 1100-1300 ° C were fed. During their stay in the loading chamber of the dryer, quartz sand has time to warm up to 600 ° C, then it moves to a rotating drum where it is evenly mixed, dried to the required humidity (0.2%) and cooled to an outlet temperature of 110-145 ° C due to atmospheric air blown through the drum chamber from the openings in the walls of the loading chamber by the fan of the dedusting unit through the exhaust chamber of the dryer.

The batch of quartz sand after drying was reanalyzed for the chemical composition of the sand particles, the chemical composition of the sand mass, moisture content, clay inclusions, pH of the aqueous extract. The dried material, sieved during the exit from the dryer drum, was divided into three portions of 65-70 kg and each portion was passed through the cleaning and dynamic air-dry enrichment unit according to options I, II and III, and then fed to the classification and cooling scheme, followed by Warehousing in the storage tank of the finished product.

The process in each of the options I, II and III differed in the air velocity at the exit of the transport module 16, depending on the reduced length (length) of the pneumatic pipe, which is the sum of the actual geometric lengths of all straight sections of the pneumatic pipe of the transport module 16 and the equivalent lengths of the T-shaped channels branch pipes, flow switches and segment bends. The minimum air flow rate for option I was 4.5-5.0 m / s, for option II - 10.0-11.0 m / s and no more than 16.0-18.0 m / s for option III

Because the difference in the movement of the material according to options I, II and III consists in the difference in the calculated resistance to the movement of the air mixture over the transport module, where at the air velocity at the exit of the transport module is less than 4.0-4.5 m / s, the particle surface is practically not cleaned and abrasion is softer associated minerals passes within less than 1% of the total mass of the material. When the air velocity at the exit of the transport line is more than 18.0 m / s, not only related minerals, but also the main mineral, quartz, are subjected to intensive abrasion, while the fraction is crushed and goes beyond the specified particle size range of the molding sands. The results of the experiment are presented in table 2.

From the data shown in table 2, it is seen that the proposed technological complex for cleaning and air-dry enrichment can improve the quality of the resulting product, for example, foundry sand, by increasing the content of silicon oxide to 99 wt.%.

table 2 sand quartz molding fraction 0.3 Enriched material
option II
Chemical composition, % Raw material
Chemical composition, % Dried material
Chemical composition, % option I
Chemical composition, % Option III
Chemical composition, % SiO ₂ 97.19 SiO ₂ 97.6 SiO ₂ 98.3 SiO ₂ 98.38 SiO ₂ 98.56 Fe ₂ O ₃ 0.6 Fe ₂ O ₃ 0.6 Fe ₂ About ₃ 0.4 Fe ₂ O ₃ 0.37 Fe ₂ O ₃ 0.35 Cao 0.4 Cao 0.4 CaO 0.35 Cao 0.34 Cao 0.32 MgO 0.56 MgO 0.55 MgO 0.41 MgO 0.32 MgO 0.24 K ₂ O + Na ₂ O 0.45 K ₂ O + Na ₂ O 0.44 K ₂ O + Na ₂ O 0.37 K ₂ O + Na ₂ O 0.29 K ₂ O + Na ₂ O 0.26 S ^2- S ^2- S ^2- S ^2- S ^2- RFP 0.3 RFP 0.21 RFP 0.16 RFP 0.14 ppp 0.13 The content of the clay component,% 0.5 The content of the clay component,% 0.2 The content of the clay component,% 0.16 The content of the clay component,% 0.16 The content of the clay component,% 0.14 Moisture content, % 3.8 Moisture content, % 0.12 Moisture content, % 0.11 Moisture content, % 0.1 Moisture content, % 0.1 pH of the aqueous extract 7 pH of the aqueous extract 7 pH of the aqueous extract 7 pH of the aqueous extract 7 pH of the aqueous extract 7

Claims (10)

1. Technological complex for cleaning and dynamic air-dry enrichment of granular bulk materials, which includes a loading unit sequentially interconnected, a drying circuit, a cleaning and dynamic air-dry enrichment plant, a classification and cooling scheme, a finished product storage tank, a collection scheme substandard material and suction system, characterized in that the drying circuit includes a horizontally mounted drum dryer, with a drum installed with a slope of 2-8 ° in the direction the movement of bulk material and with a circular sieve rigidly fixed at the end of the drum, under which a distribution tank is installed to collect bulk material leaving the dryer through a sieve, the cleaning and dynamic air-dry enrichment unit includes at least one transport module that contains horizontally oriented vertical and inclined directions, straight sections of the pneumatic pipe, interconnected through T-shaped pipes and segment bends, the initial section of the pneumatic pipe being horizontal and at the inlet is connected to one of the chambers of a two- or three-chamber pneumatic pump, each chamber of which is connected to a distribution tank, and the output of the horizontal section of the pneumatic pipe is connected to the vertical section through a T-shaped pipe with a damped horizontal output channel, the remaining sections of the pneumatic pipe are interconnected through segmented bends, each of which is a structure consisting of four links in the form of hollow cylinders connected in series to each other flange connection, moreover, one of the bases of the first three cylinders is beveled at an angle of 18 °, and one of the bases of the fourth cylinder is beveled at an angle of 36 °, the first link is connected with a direct base to the air duct and the beveled base with a direct base of the second link, the second link is connected beveled base with a direct base of the third link, the third and fourth links are interconnected by beveled bases in such a way that they form an acute angle, and with a direct base the fourth link is connected with the continuation of Mon evmovoda, the diameter of each cylinder relates to the length of the largest side, as 0.6: 1, and the cross section of each subsequent link is 1.1 times larger than the previous one, and the inner diameter of the pneumatic duct channel refers to the inner diameter of the input and output links of the segment outlet, as 1: 2-2.15, and to the inner diameter of the flange connection, as 1: 1.2-1.3, and to the inner diameter of the channels of the T-shaped pipe, as 1: 1.6. 2. The technological complex according to claim 1, characterized in that the classification and cooling scheme includes an intermediate tank, a dust separator tank that acts as a damper and at least one pneumatic classifier. 3. The technological complex according to claim 2, characterized in that the intermediate tank is connected to the outlet of the final section of the pneumatic pipe through T-shaped nozzles with a muffled horizontal outlet and a vertical outlet channel pointing downward on the walls and installed in the upper part of its housing which, in the last third of its length, through holes are made, uniformly arranged in a circle in two rows, and inside there is a spray gun in the form of a screw with a rubberized fixed screw. 4. The technological complex according to claim 3, characterized in that the lower conical parts of the intermediate tank and the dust collector are connected to the atmosphere through shut-off valves, and the upper parts of the intermediate tank and the dust collector are connected by a pipeline whose cross section exceeds the cross-section of the channels of the transport pneumatic pipeline module 2-2.5 times. 5. The technological complex according to claim 4, characterized in that on the cover of the intermediate tank there is a tap with a non-return valve designed to enter atmospheric air into the tank, and the tap section is equal to the section of the channels of the pneumatic pipeline of the transport module. 6. The technological complex according to claim 2, characterized in that the lower conical part of the intermediate tank is connected by a pipe inclined at an angle of 35-40 ° to the vertical with the upper part of the pneumatic classifier housing. 7. The technological complex according to claim 6, characterized in that the pneumatic classifier has a cylindrical body, and in the cavity of the pneumatic classifier on the housing cover in front of the outlet of the inclined pipeline, a vertical plate is installed, and below it is installed, as a continuation of the inclined pipeline, a guide plate that form a flat gap between them, under the guide plate, at the level of half the height of the pneumatic classifier, a perforated plate with a diameter of 35-40 ° to the horizontal is installed with a hole of 3-5 mm, occupying half the section of the pneumatic classifier on the inlet side, an inlet channel for supplying atmospheric air is placed under the perforated plate, the inlet channel is used for supplying atmospheric air, and an outlet channel is made above it to discharge air from the classifier cavity, moreover the cross-sections of these channels correspond with the cross-section of the cylindrical part of the pneumatic classifier housing, as 1: 1: 9. 8. The technological complex according to claim 1, characterized in that the transport module further includes at least two auxiliary vertical pneumatic pipelines of different lengths, each of which is connected to the initial horizontal section of the main pneumatic pipelines through additional T-shaped nozzles with shutoff valves mounted on a horizontal and on the upward vertical outlet channels of each nozzle, the short pneumatic conduit being connected to the long one via a T-shaped nozzle mounted on its upper end with an outlet muffled in the direction of movement of the material flow, and through an angular two-way flow switch having a design similar to a T-shaped nozzle, a long pneumatic pipe is in turn connected through a T-shaped nozzle with an outlet muffled in the direction of movement of the material flow installed at its upper end, and through a two-way flow switch connected to a vertical section of the main air line. 9. The technological complex according to claim 1, characterized in that the substandard product collection circuit includes an inclined lower part of the bottom of the exhaust chamber of the dryer, connected by a vertical feed channel to the inlet of the additional air pump chamber, the outlet of which is connected by a pipeline to the storage tank of the substandard product. 10. The technological complex according to claim 1, characterized in that each functional unit of the technological complex has its own isolated aspiration system.