RU2137997C1 - Method and equipment for production of expanded vermiculite - Google Patents

Abstract

FIELD: construction materials industry. SUBSTANCE: method and equipment can be used for production of expanded vermiculite directly from non-concentrated ore with content of waste rock mass from 15 to 85%. According to method, raw material before delivery into main calcining passage of kiln is partly dried and heated to 80-120 deg. in additional drying and heating passage by means of exhaust gases taken after main calcining passage. Heating of raw material in both passages of kiln is initially performed in direct-flow process when material is in suspended pulverized condition, and then in counter-flow process when material naturally flows down over inclined surface of material bed. Heating of vermiculite is performed at temperature of 300-600 deg. to 800-1000 deg. Application of aforesaid method and equipment allows for enhancing quality and output of expanded material. EFFECT: higher efficiency. 2 cl, 2 dwg, 2 tbl

Description

 The invention relates to the building materials industry, mainly to the production of expanded vermiculite, directly from non-enriched ore with gangue content of 15 to 85%.

 In world practice, there is no efficient production of expanded vermiculite from non-enriched ore.

 As shown by feasibility studies, in the production from quarry unenriched ore, expanded vermiculite is obtained with equal quality 1.5-2 times cheaper than from concentrate raw materials.

 A known method for the production of expanded material and a device for its implementation (AS USSR N 1043456, CL F 27 B 15/00).

 A method for the production of expanded material, mainly vermiculite, consists in feeding raw materials to a stream of hot gases at a speed greater than the flow rate of hot gases.

 A device for implementing this method is made in the form of a vertical tube furnace, in the lower part of which there is a device for supplying raw materials and a nozzle, and in the upper part a reflector in the form of a tent arch and receiving chambers.

 The disadvantages of the above method and device for its implementation are the low degree of expansion and extraction of expanded vermiculite when the content of waste rock in the feed is above 15%, as well as the irrational use of heat from a stream of hot gases.

 The closest to the invention in technical essence and the achieved result is an aggregate for expansion and enrichment of granular material, mainly vermiculite, containing a furnace with an inclined hearth, a burner device, an air-injection device for loading raw materials, a precipitation chamber with an exhaust device, silos for raw materials and waste rock and a screen installed at the end of the furnace channel (a.s. N 765628, class F 27 B 15/00).

 The method implemented by this unit consists in the fact that the raw material is supplied by a pneumo-ejection device to the stream of hot gases at a speed greater than the speed of the latter. At the same time, grains of raw materials with a size of less than 0.5 mm in a stream of hot gases swell in suspension and are carried out into the precipitation chamber, and large thick grains of 0.5 - 3 mm in size are thrown by an air-ejection device to the screen, impacting which are delayed and roll down an inclined hearth , as they roll down selectively for fractions and mineralogy, they swell, acquiring windage, are captured by the flow of gases that are carried into the precipitation chamber. At the same time, gases are constantly removed by an exhaust device, and the waste rock falls out of the stream and rolls down the inclined hearth into the waste rock bin.

 Thus, thick grains 0.5-3 mm in size are subjected to two-stage heating, first flying by inertia up to the screen, and then when rolling down an inclined hearth down. Grains with a thickness of more than 3 mm when rolling along an inclined hearth do not have time to swell and, together with gangue, slide into an gangue bin.

 The disadvantage of the unit for expanding the material and the method implemented by it is the impossibility of heating and full expansion of vermiculite with a granular thickness of more than 3 mm and, therefore, the low efficiency of its expansion, especially from raw materials with an empty rock content of 15-85%.

Moreover, for heating from 20-30 ^o C to 300-600 ^o C, at a temperature of the gas medium in the furnace 800-1000 ^o C and full expansion of vermiculite from raw ore with a high content of vermiculite granules with a thickness of more than 3 mm, a higher fuel consumption is required.

 The aim of the invention is the provision of obtaining expanded vermiculite from non-enriched ore, while increasing the specific productivity of the process, the quality and yield of expanded material, as well as reducing energy costs.

This goal is achieved by the fact that according to the method for the production of expanded material, mainly vermiculite, by supplying raw materials to the stream of hot gases at a higher flow rate, and then counter-flow to this stream, before feeding it into the stream of hot gases in the furnace, the raw material is heated to a temperature of 80-120 ^o C, giving initially in suspension atomized into the gas stream with a temperature of 150-230 ^o C parallel flow, and then countercurrently in the form of naturally sliding down on the inclined plane of the bulk layer, the tempo rature flow of hot gases in the furnace, which is then fed to the preheated feed is 800-1000 ^o C, at which heating is carried out only vermiculite to 300-600 ^o C.

 A device for implementing the method, comprising a furnace with an inclined channel provided with a screen in the upper part, a burner device and a pneumatic ejection device for supplying raw materials installed in the lower part of the furnace channel, a raw material hopper, a settling chamber with an exhaust gas intake and a gas outlet, according to the stated purpose, an additional drying and heating channel located above the inclined channel, and a bypass channel connecting the lower part of the additional channel to the exhaust gas intake, the second ejection a structure associated with a feed hopper, a estrus connecting the lower part of the drying and heating channel with a pneumo-ejection device for feeding raw materials to the inclined channel of the furnace and a device for regulating the volume of heated gases supplied to the additional drying and heating channel installed in the gas outlet.

The essence of the proposed method for the production of expanded material, mainly vermiculite, and the unit for its implementation is to use the heat of the exhaust gases from the main channel of the kiln for preliminary drying and heating of raw materials before being fed into the main channel of the furnace. In this case, large, thick grains of vermiculite are heated to a full depth up to 80-120 ^o C for subsequent explosive, more complete swelling of it during a sharp high-temperature heating mode.

The heating of vermiculite in the range of 300-600 ^o C at a coolant temperature in the channel of the furnace 800-1000 ^o C due to the fact that in these limits of heating provides the highest degree of expansion and strength of the granules of expanded vermiculite.

Pre-heating of vermiculite in the range of 80-120 ^o C followed by a sharp explosive heating at a temperature of the coolant in the furnace channel 800-1000 ^o C to a temperature of 300-600 ^o C makes it possible to obtain from this raw ore from 15-85% gangue ore expanded vermiculite with a bulk mass in the range of 50-125 kg / m ³ , deformability of the granular bulk layer for compression of 8-10% and brittleness of 6-7%, which exceeds these indicators when it is obtained from a raw material concentrator enriched in concentration plants.

 The essence of the invention is illustrated by the drawing, where in FIG. 1 shows an aggregate for the production of expanded material, a General view; in FIG. 2 is a section along AA in FIG. 1.

 The unit consists of a furnace made in the form of an inclined channel 1 with a screen 2 located in its upper part and an additional drying and heating channel 3 parallel to the bottom of the channel 1 above it and located in the lower part of the end of the channel 1 of the burner device 4 and the pneumo-ejection device 5, and the lower part of the end of the channel 3 of the ejection device 6, the precipitation chamber 7 with the outlet of exhaust gases 8 and the hopper for raw materials 9 located in its upper part.

 The ejection device 6 is connected to the feed hopper 9, the lower part of the channel 3 is estrus 10 with a pneumo-ejection device 5. In parallel to the additional channel 3, a bypass channel 11 is located, communicating in the lower part with the channel 3, and in the upper part with the exhaust gas intake 8.

 In the upper part of the additional channel 3 there is a device for regulating the volume of exhaust gases, consisting of a gate 12 at the outlet of the channel 3 and gates 13 at the inlet of the exhaust gas intake 8 and 14 at the inlet of the gas outlet 15.

 To control the vacuum in the channel 1, a tractor 16 is located, and to control the temperature of the raw materials after drying and heating of the raw materials in the additional channel 3, before the thermocouple 17 is fed into the channel 1 in heat 10, and the thermocouple is in the channel 1.

 The unit operates as follows.

The hood is turned on, which ensures the suction of gases through the gas outlet 15 from the precipitation chamber 7. The vacuum in the channel 1 of the furnace is regulated by the shutters 14 and 13 with the shutter 12 closed. Then, compressed air from the compressor is supplied to the ejection devices 5 and 6, and after the establishment of a stable aerodynamic mode, the burner device 4. By controlling the fuel and air consumption, as well as the amount of vacuum in channel 1, stable combustion is established, which ensures heating to the limit depending on the quality of the raw materials and performance ah 800-1000 ^o C.

After establishing a stable heating mode in channel 1, the gate 12 opens and, by adjusting the gate 12, 13 and 14, the heating mode in the additional drying and heating channel 3 is set by the gases coming from the exhaust gas intake 8 through the bypass channel 11 to the input of channel 3, the gas temperature entering the channel, is set in the range of 150-230 ^o C.

Then from the hopper 9 to the ejection device 6 is fed raw material, which in a suspended atomized state by this device is thrown into the channel 3 and flies through it to the upper end, hitting which rolls down the bottom of the channel in the form of a bulk layer. When this raw material is dried and heated to a temperature of 80-120 ^o C. The heating temperature is provided by the temperature and amount of gases passing through channel 3, as well as its length. The temperature of the raw materials during the operation of the unit in the additional channel 3 is controlled by opening the gate 12 and pressing the gate 13 according to the readings of the thermocouple 17.

Heated raw material from channel 3 through estrus 10 enters the pneumatic ejection device 5, by which it is accelerated by compressed air to speeds of 30-50 m / s and by inertia is thrown out by spraying into channel 1 of the furnace. In this case, preheated small and thin grains of raw materials (vermiculite) swell immediately, falling into the stream of hot gases with a temperature of 800-1000 ^o C, heating up to 300-600 ^o C, swell and are carried out into the precipitation chamber 7. Large thick grains, also heated in the additional channel 3, in accordance with their kinetic energy acquired in the ejector 5, fly through a stream of hot gases with a large velocity gradient, hit the screen 3, stop and fall on under the channel 1 of the furnace. The optimal length and height of the channel 1 of the furnace provide the necessary time in the high temperature zone of different fractions and mineralogical components of hydromica and vermiculite for their full and selective expansion, and the specified flow rate of hot gases in channel 1 of the furnace ensures selectively timely removal of well-expanded from the high temperature zone particles of vermiculite without burning in the precipitation chamber 7.

Particularly large particles of vermiculite and hydromica, reflected from the screen 2, roll along the inclined bottom of the channel 1 of the furnace and are heated to the required temperature of 300-600 ^o C. As a result, these particles also swell and, acquiring a certain windage, are picked up by a stream of gases and carried into sedimentation chamber 7. A gas stream with particles of expanded vermiculite when they exit the channel of the furnace 1 sharply loses speed and expanded particles of vermiculite fall out of it and sink to the bottom of the precipitation chamber 7.

 Gases with vermiculite dust carried away by them enter through the intake 8 and the bypass channel 11 into the additional channel 3 and from it through the gas outlet to the treatment facilities.

 The gangue in channel 1 does not swell and, therefore, does not acquire the required windage for the flow of hot gases into the sedimentation chamber 17, but is poured along the bottom of channel 1 through its lower end into the waste bin (not shown).

 The test results of the proposed method and device for its implementation are shown in tables 1 and 2.

 Conclusions: as can be seen from the test results of the method and the device that implements it, shown in tables 1 and 2, we get expanded vermiculite from raw ore with a moisture content of up to 10%, which corresponds to international standards in quality.

The calculation of economic efficiency by comparing the cost of expanded vermiculite obtained from the concentrate of the beneficiation plant and from non-enriched ore at prices of 1992 and 1993. The proposed method and unit for its implementation are given below:
1. The concentrate of vermiculite raw materials KV-150 of the Kovdor enrichment plant in 1992 prices cost 30 thousand rubles. per ton, and in 1993 - 53 thousand rubles / ton.

Moreover, the output from one ton of its expanded vermiculite with a bulk density of up to 150 kg / m ³ was 6 m ³ .

Consequently, the unit cost of raw materials for the production of one m ^{3 of} expanded vermiculite was 1992 prices - 5000 rubles / m ³ , and 1993-8833 rubles / m ³ .

 2. Raw ore mined in open pits in open pits, at prices of 1992, was about 4,000 rubles / ton, and 1993–6,000 rubles / ton.

The output from one ton of ore with a vermiculite content of 34%, after screening out gangue fractions of more than 10 mm, was 2.5 m ³ / t.

Consequently, the unit cost of raw materials for the production of 1 m ^{3 of} expanded vermiculite was in 1992 prices 1,600 rubles / m ³ , 1993 - 2,400 rubles / m ³ .

Thus, the production of expanded vermiculite from raw ore using this method and the unit for its implementation allows to obtain a specific economic effect in 1992 prices - 5000-1600 = 3400 rub / m ³ , i.e. 3.125 times, and in 1993 prices - 8833 - 2400 = 6433 rub / m ³ , i.e. 3.69 times than in the production of concentrate KV-150.

 Accordingly, labor and energy costs are significantly reduced.

 Naturally, in the production of expanded vermiculite from unenriched ore, huge capital costs for the construction of expensive processing plants are eliminated and hundreds of small deposits of vermiculite that are left without use all over the world are also used, in addition, associated vermiculite-containing overburden ores can be used in the development of large deposits for other minerals .

 In the proposed two-channel furnace with preheating of the ore by the heat of the exhaust gases from the furnace, fuel economy is achieved in relation to the prototype, i.e. single-channel furnace by 12-20% depending on the moisture content of the ore.

Claims (2)

1. A method for the production of expanded material, mainly vermiculite, by supplying raw materials to a stream of hot gases at a speed greater than the flow rate, and then countercurrent to this stream, characterized in that before feeding into the stream of hot gases in the furnace, the raw material is heated to 80 - 120 ^o C feeding first in a suspended atomized state into a gas stream with a temperature of 150 - 230 ^o C straight-through, and then counter-flow in the form of a bulk layer naturally rolling down an inclined plane, and the temperature of the stream of hot gases into which it serves heated raw material is 800 - 1000 ^o C, while vermiculite is heated to 300 - 600 ^o C.  2. A unit for the production of expanded material, mainly vermiculite, comprising a furnace with an inclined channel provided with a screen in the upper part, a burner device and a pneumo-ejection device for supplying raw materials installed in the lower part of the furnace channel, a hopper for raw materials, a precipitation chamber with an exhaust gas intake and gas outlet, characterized in that it contains an additional drying and heating channel located above the inclined channel of the furnace, and a bypass channel connecting the lower part of the additional channel to flue gas exhaust gas, a second ejection device associated with a feed hopper, a heat pipe connecting the lower part of the drying and heating channel with a pneumo-ejection device for supplying raw materials to the inclined channel and a device for controlling the volume of heated gases supplied to the additional drying and heating channel installed in gas outlet.

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