SU1285033A1 - Method of preparing cao-co-containing additive to granulation burden and device for effecting same - Google Patents

Abstract

Currently, it belongs to the field of preparation of fluxing and binding additives 13 of the batch and can be used in scoop metallurgy in the production of iron ore pellets. The purpose of the invention is to increase the chemical activity and the amount of iosoest in the CaO-containing additive. In the method of preparing the CaO-containing additive from the heat flux from the decarbo-ized 1P material before directing it to the grinding and drying zone of the carbonate raw material, part of the stream is separated in the amount of -60-90% of the total flow and guide and cyclones of the second step. In the device by aut. St. By 1120026, the output of a 1GZ-cyclo1P (the second furnace is additionally connected by a flue to cyclones of the second stage of capture, and the cyclops of the first CTyneini of trapping connect the diplips to the receiving branch pipe of the 1. with shutoff valves. 2 cf f-ly, pl ,, i table. sh JfWA VTO “4 GO Q1 О CO 00

Description

The invention relates to the field of preparation of fluxing and bonding materials into the pelletizing mixture and can be used in ferrous metallurgy in the production of iron ore pellets

The purpose of the invention is to increase the chemical activity and the amount of lime in the CaO-containing additive.

Figure 1 shows a diagram of an apparatus for carrying out the method for preparing a CaO-containing additive for pelletizing.

The device contains bulk material hoppers located along the process, under which feeders 2 are installed for feeding the material into. crushers 3, hopper 4 crushed limestone with a feeder 5, mill 6 with a sump 7, which is connected to exit 8 of a cyclone furnace 9 by a flue 10 with a locking device P, separator 12 of aerodynamic action, connected with return line 13 to nozzle 7, cyclones 14 of the first collecting stage, connected to the pipe 7 by the duct 15 with the recycle exhaust fan 16 installed on and the locking device 17. The cyclones 18 of the second stage of trapping, equipped with bins 19 with valves 20, are connected to the outlet 8 of the furnace 9 by the duct 21, cyclones 18 The second stage of trapping is equipped with a device 22 for fine purification of gases (nanpi-iMep electrostatic precipitator) and gas-blowing means — exhaust fan 23. Cyclops I4 of the first stage of trapping are connected through a pneumopump 24 and transporting device 25 to the inlet 26 of the cyclone furnace 9.

The cyclone furnace 9 is equipped with a fan 27 for supplying air to the combustion and exit 8 for cooling the pyramidal gases, redistributing the air is carried out by throttle valves 28. At the outlet of the recirculation exhaust fan 1b, the duct 15 is connected to cyclones 18 of the second degree trapping through the duct 21 bypass a duct 29 with a locking device 30. On the duct 2 to reduce the temperature of the gas stream in front of the cyclones I8, there is a cushioning device 31, which is connected to the conveying device 25.

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Separating the flow of the coolant with carbonized material before directing the grinding and drying of the carbonate raw material into two streams, which is achieved by additionally combining an cyclone furnace with a cyclone in the secondary flue trap, allows a flow of 60-90% of the calcined material to lime to the second stage cyclones. At the same time, the main part of the dispersed flow passes the mill aggregate, the separator and the cyclones of the first entrainment stage, and in these aggregates a smaller part of the resulting lime is precipitated, and only a small portion of ground lime is contained in the lime. In addition, the lime does not return to the cyclone kiln for reprocessing and its quality indicators do not deteriorate.

The lower limit of the flow to be separated (60%) is selected from the grinding conditions of the most important material, when high heat consumption is required for drying. The upper limit of the separated flow (90%) corresponds to the grinding of carbonate raw materials with low humidity.

The connection of the cyclones of the first stage of trapping with the receiving pipe of the mill unit with a flue gas with recirculation gas gas 5 means forms a closed circulation loop (mill aggregate t - separator - cyclones of the first stage trapping - gas duct with recirculation gas blower means - the milling unit of the first stage of trapping - the gas pipe with the recirculation gas blower means - the mill stage; from the mill through the separator is transported to the cyclones of the first stage of capture, where it settles. At the same time, the ground limestone does not contain lime or contains only insignificant inclusions of lime, due to which, during calcination, lime is obtained without reburning with high chemical activity and constant chemical composition, which improves the accuracy of the dosage of the oxide components of CaO-containing additives in the pelletizing mixture.

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To maintain the necessary aerodynamic conditions in the mill; unit, providing the required fineness of grinding lime and its drying.

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recirculating gas :() The blowing agent at the outlet is connected to the cyclones of the second stage of capture by the bypass duct, through which excess gas from the closed circulation loop is generated as a result of suction, drying of the raw material and a heated partial flow of heat carrier from the cyclone. a mill unit controlled by valves on the bypass duct.

The method of preparing the CaO-containing additive to the pelletizing of the osus is as follows:

Lumpy limestones from hoppers 1 are fed by feeders 2 to hammermills 3, after which crushed limestones are fed to intermediate tank 4 and from there crushed nuts by nutrient 5 to ball 6 via 6 inlet 7. 6, the grinding of the material is carried out, and the crushed lime is removed from the mill aggregate 6 ra3OBbLM by the flow generated by the recirculation gas dispenser 16, and the separator 12 and into the cyclones 14 of the first entrainment stage. In the separator 12, large fractions of ground limestone are separated, returned to the ground by a transnorting device — a return line 3. In cyclones 14 of the first stage, the limestones are captured and sent for firing by means of a mnevmopump 24 via a conveying device 25 pa inlet, 26 of a cyclone furnace 9 and for metering into the pelletizing mixture, and the gas stream from cyclones 14 through a recirculation flue 15 with a locking device 17 smoke exhauster 16 is directed to the inlet 7 of the mill unit 6.

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in a cyclone furnace 9, ground limestone is subjected to decarbonization as a result of exposure to high-temperature heat-transfer agent. Air to the combustion furnace 9 is supplied by the fan 27, and air is supplied to the outlet 8 of the furnace 9 if necessary to cool the dispersed flow. Flow control and redistribution of air for combustion and cooling are carried out by shutoff valves - throttle valves 28.

From the cyclone furnace 9 calcined material - lime. With a gas stream

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Iap)) are passed through the flue duct 21 with heat utilization installed on it by a device 31 for converting the temperature of the dispersed stream to cyclones 18 of the second stage of trapping, where lime is deposited. From the cyclops 18, the gas flow enters the apparatus-22 of the gas cleaning gas exhaust and then is blown off by the fan 23 to the atmosphere. The captured lime from the bunker 19 of the cyclones 18 through the valves 20 and from the fine gas cleaning 22 is fed to the dosage for entry into the pelletized mixture .

In the heat treatment device 31 installed on the duct 21 between the outlet 8 from the furnace 9 and the cyclones 18 and on the transporting device 25 between the cyclones 14 and the inlet 26 of the furnace 9, the ground heat of 15 ka, directed to the burner air, is heated by the heat of the dispersed flow coming out of the pheppe 9. At the same time, iIijahs with the fuel flow ia decarbonization of known in cyclonic night 9 and the condition of the cyclones 18 of the second stage of the trap improved.

Transition 1 mA of gas flow in a closed circulator contour1) e; chalk L1Itsa 6 - separator 12 - CYCLOP. 14 — flue duct 15 with smoke exhauster 16 — mill 6 is installed with a shut-off device 17 n maintained at the required level by transferring some of the flue gases from the circulating smoke fluid to the atmosphere, which is achieved by connecting the exhaust fan outlet 16 with cyclones 18 of the second stage - a gas flue 29 with a loadable device 30 - a throttle that receives a quantity of bypass gas flow.

During the period of operation of installations on a material with high humidity, a part of the gas flow (up to 40% of the cyclone furnace 9 through the duct 10 with the shut-off device 11 - throttle is directed through pipe 7 into the mill 6 for sunflower ground limestone. This is an excess gas flow in a closed circulation unit, they are withdrawn in the same way as we suck in 1) TH air of the Gyurapkoy gas flue 29.

5,) 2 The small fraction of the coolant introduced into the mill 6 from the furnace 9 has virtually no effect on the quality indicators of the oxide component of CaO-containing additive in the pelletizing mixture. When the material is low in moisture, the shut-off device 11 partially overlaps the gas duct 10, up to 10% of the heat carrier flow enters the mill 6 and the ground limestone is dried mainly due to the heat absorbed by the material. The CaO-containing additive produced in the installation consists of materials with contrasting properties: ground lime and highly active lime, which serve as fluxing and binding additives in the pelletizing mixture in the production of iron ore pellets, and the increase in chemical activity of oxides the same component of the additive - lime improves wortiness of the charge and increases the strength characteristics of the pellets.

PRI me R. At the pilot plant, equipped in accordance with the invention, the method of production of CaO-containing additives was carried out. Lime from the warehouse entered the source material bunker, then it was crushed in hammer crushers to a class of 15 mm and sent to the crushed limestone bunker, and then to a ball mill in an amount of 30 t / h. After grinding in a mill, limestone was captured by first-stage cyclones, and the following sieve composition of limestone was obtained with a gel: 100-71 µm - 3-4%; 71-50 microns - 3.6%; 50-25 microns 11, 4%; less than 26 microns - 81.6%. I

Ms of cyclones of the first stage of ground limestone containing CaO - 52.12%; MgO - 2.50%; SiO — 1.68%; The CO, -, - 43.7%, in the amount of 7000 kg / h, was sent for firing into a cyclone furnace, at the same time receiving 4500 kg / h of lime. The consumption of natural gas per kiln was 630 m / h. From the cyclone furnace, the main part of the flue gas and lime stream at 600-800 ° C was directed to second-stage cyclones, and another part to the mill to dry the material to be ground. The temperature of the dispersed stream was removed by diluting with cold atmospheric air to 150-200. C before cyclones second

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steps and up to 50-300 ° C before the stranded.

The results of the CaO-containing additive in the pelletizing mixture are shown in the table, from which it is clear that separating a portion of the heat carrier flow with decarbonated material before directing the flow from the cyclone furnace to the grinding zone and drying the carbonate raw material provides a CaO-containing additive with a large amount of lime. in it (experiments 1-4 and 5); The direction of the flow (90-60%) into cyclones of the second stage does not impair the drying of the crushed limestone at different humidity (experiments 1 and 2-4), the material deposited in the second stage cyclones has a high activity (experiments 3 and 4).

The use of the resulting CaO-containing additive in the pelletizing mixture (when the content in the blend is 5% j is known to - 10% and the basicity of the charge is 0.6) it increased the strength characteristics of the raw pellets (crush strength 1.65 kg / approx. Against. 1.3 -1.5 kg / ok and drop resistance 7–8 times Against 5–6 times) and reduced the content of fines in the baked alumina ah to 4-6% versus 7-8.5%. The strength indicators of burned pellets remained at the same level, however, the ranges of fluctuations of the chemical composition (basicity 0.62 - 0.58 versus 0.65 - 0.55) and the strength of the latter (255-265 kg / approx. 250-270 kg / OK) .

The invention has several advantages;

provide the contrasting properties of the components of CaO-containing additive to the pelletizing mixture

without their dilution, which improves the accuracy of the dosage of the oxide components when they are introduced into the pelletizing mixture, resulting in the production of oxygen with stable qualitative indicators;

the oxide component of the additive (precipitated in cyclones of the second stage) has higher quality indicators: (CaO + MgO), OBSch 85.8-87, 2%, (CaO + MgO). 73.8-77.2%; .time of hydration 1.0-1.08 min. against the values of the quality indicators of the product deposited in cyclones of the second stage and obtained by a known method - 64.9%, respectively; 24.4%; 3 min. 40 s;

The use of the resulting CaO-containing additive in the pelletizing mixture allows for an increase in the strength characteristics of raw vegetables (increases the crushing strength from 1.3–1.5 kg / ok to 1.65 kg / ok, for dropping - from 5 -6 times up to 7-8 times) and reduce the content of trifles in the baked pellets to 4-6% against 7-8.5%.

Claims (2)

Invention Formula . The method of preparing CaO-containing additives in the pelletizing mixture according to bus No. 1120026, is valid for the reason that, in order to increase the chemical activity and the amount of lime in the CaO-containing In addition to the addition of heat from the flow of heat transfer agent with a decarbonated mat talom before being sent to the grinding and drying zone of the carbonate raw material, a part of the flow is separated in the amount of 60-90% of the total flow and sent to the second stage cyclones. 2. A device for the preparation of CaO containing additives in the bundle of bundles of ed. St. No. 1120026, which is related to the fact that the outlet from the cyclone furnace is additionally connected by a flue to cyclones. the second stage of trapping, and the cyclones of the first stage of trapping are connected to the receiving pipe of the mill aggregate by a gas duct with gas blowing means, which at the exit is connected with the second stage cyclones of trapping by a bypass duct with stop valves. , /, 23