UA4720U - A method for reprocessing zinc-containing WASTE of metallurgy - Google Patents

Abstract

A method for reprocessing zinc-containing products of metallurgy, in which powder-gas mixture withdrawn from the cold end of the kiln is blown through the layer of carbon deoxidizer heated to the temperature of 910-1100 AС, and directed to the gas purification for catching formed zinc stages.

Description

The useful model refers to the processing of zinc-containing waste, namely sludge and dust of wet and dry blast furnace, blast furnace, envelope, electrosmelting and other industries and can be used in ferrous and non-ferrous metallurgy.

There is a known method of obtaining a commercial zinc product from dust of metallurgical production, mainly electric steel smelting, which includes mixing and granulation of primary zinc dust with iron-containing material, high-temperature recovery of the obtained charge with a carbon reducing agent, cleaning of the dust and gas stream with capture in the gas treatment during cooling of zinc vapors, return of the iron-containing product to redistribution of iron mining. Cleaning of dusty gases is carried out by sucking them through a layer of lumpy limestone until the zinc content in it is 5-25 95, after which the limestone is crushed and fed to the charge of primary zinc-containing dust in the amount of 30-4095 of the weight of the dust, while a new portion of limestone is fed to clean the dust, the size of the granules is 1-3 mm (Ass. of the USSR Mo1749282 dated 22.03.92). At the same time, the zinc content in the received commercial zinc product reaches 62905.

The disadvantage of this method is the incomplete extraction of zinc from the raw material (up to 6295), the low through-grade degree of zinc extraction from the raw material (up to 9895) and the contamination of the obtained commercial zinc product with calcium compounds contained in the lumpy limestone layer, as well as environmental pollution with zinc-containing emissions gas treatment

The method closest to the claimed method is the method of processing zinc-containing metallurgical waste, chosen as a prototype, which includes mixing the waste with a carbon reducing agent, drying, high-temperature treatment of the resulting mixture in a furnace, distilling zinc and capturing the race with the production of zinc oxides, while the resulting mixture is dried to a moisture content of 11-15 wt. 95, granulated to obtain granules with a size of 4-10 mm, high-temperature processing of the mixture is carried out at a temperature of 910-1100 C for 1-2 hours, zinc distillation is captured by diverting 70-8095 from the total volume of the zinc-containing dust-gas mixture from the reaction zone of the firing furnace , and the remaining volume of the dust-gas mixture is removed from the cold end of the firing furnace (patent of Ukraine Mo 57382 - A, publ. 16.06.2003.).

This method makes it possible to increase the degree of extraction of a commercial zinc product with a minimum content of impurities and reduce the harmful impact of emissions on the environment.

However, the disadvantage of this method is the low overall degree of extraction of zinc from the raw material (up to 9895), as well as environmental pollution by zinc-containing gas treatment emissions.

The useful model is based on the task of creating a method of processing zinc-containing waste from metallurgical production, in which, by sucking the dust-gas mixture diverted from the cold end of the firing furnace through a layer of carbon reducing agent heated to a temperature of 910 - 1100"C, an increase in the overall degree of zinc extraction from raw materials is achieved and improve the quality of the commercial zinc product, as well as reduce environmental pollution.

The problem is solved by the fact that in a known method of processing zinc-containing products of metallurgical production, which includes mixing metallurgical production waste with a carbon reducing agent, granulation of the resulting charge, drying and high-temperature processing of granules in a firing furnace, capture of zinc distillates by removing the main volume of the dust-gas mixture with of the reaction zone of the firing furnace and the removal of the remaining part of the dust-gas mixture from the cold end of the firing furnace, according to the invention, the dust-gas mixture withdrawn from the cold end of the firing furnace is sucked through a layer of carbon reducing agent heated to a temperature of 910 - 1100"C and sent to the gas treatment for capture of the formed zinc race.

It is preferable to soak the dust-gas mixture through a layer of carbon reducing agent with a thickness of 400-900 mm.

It is preferable to soak the dust-gas mixture through a layer of carbon reducing agent, which has a particle size of 5-10 mm.

The causal relationship between the set of features of the invention and the achieved result is explained as follows.

The zinc-containing dust-gas mixture discharged from the cold end of the countercurrent firing furnace, with the oxidizing composition of the atmosphere in the firing furnace, contains mainly dust-like particles of zinc oxide, contaminated by unreacted particles of the charge, which come from the granules that are erased during the movement of the furnace. This ensures zinc content in the resulting commercial zinc product in the range of up to 6595.

The suction of the dust-gas mixture discharged from the cold end of the firing furnace through a layer of carbon reducing agent heated to a temperature of 910 - 1100"C with a layer thickness of 400 - 900 mm with the size of dispersed particles of 5 - 10 mm allows for the recovery of the particles remaining in the previously unreacted charge and additionally to extract the zinc compounds contained in it. This is due to the fact that under the influence of high temperature, additional recovery of zinc from the dust-gas mixture occurs. At the same time, the optimal temperature for zinc recovery is chosen to be 910 - 11007C, taking into account the fact that at a temperature below 9107C, a decrease occurs the degree of zinc extraction and the formation of intermediate zinc compounds that are not extracted from the mixture.

Increasing the temperature above 1100"7C is impractical, because a further increase in temperature does not lead to an increase in the degree of zinc extraction.

As a result of the suction of the dust-gas mixture through the heated carbon reducer, the overall zinc extraction rate is increased to more than 9895 and a commercial zinc product of higher quality is obtained.

Figure 1 shows a technological diagram of the process of processing zinc-containing waste from the main metallurgical industry.

The method of processing zinc-containing metallurgical waste is carried out in the following way.

Zinc-containing slurries or their mixtures with zinc-containing dust are dried in a rotating countercurrent drum dryer at a temperature of 200 - 4007C for one hour to a moisture content of 11-1595 using natural gas or fuel oil or their mixture as fuel.

The dried mixture is mixed with a carbon reducing agent (coke screenings or oil scale-containing waste from rolling production) at a mass ratio of 1:0.1 - 0.3, respectively, in a mixer and sent for granulation in a plate granulator, the rotation speed of which is set in the range from 1 to 5 rpm ./min., the angle of inclination of the plate - 20 - 40" to the horizon, the removable knife is installed in the lower section of the plate.

The obtained granules with a diameter of 4 - 10 mm are sent for drying in a belt dryer, they are dried to a moisture content of 5 - 695 at a temperature of 200 - 300 "C for 0.5 - 1 hour, then sent to a countercurrent firing drum rotary furnace for high-temperature processing for distillation of zinc and capture of zinc runoff, which is part of the granules, with a carbon reducing agent and partial reduction of iron.

High-temperature processing is carried out at a temperature in the reaction zone of the furnace of 910 - 11007C for 1 - 2 hours.

The zinc-containing dust-gas mixture is removed from the reaction zone of the firing furnace in the amount of 70 - 8095 of the total volume of the dust-gas mixture, passed through the boiler-utilizer, and zinc runoff is captured to obtain a commercial zinc product.

The remaining volume of the dust-gas mixture (20 - 3095) is removed from the cold end of the countercurrent firing furnace, it is sucked through a layer of carbon reducing agent 400 - 900 mm thick with the size of dispersed particles of 5 - 10 mm at a temperature in the layer of 910 - 1100 "C, passed through a heat-utilizing boiler and catch zinc fumes in a cloth gas-cleaning filter to obtain a high-grade commercial zinc product.

Dezincified granules with a zinc content of up to 0.0895 and an iron content of more than 6790 are sent to blast furnace production.

The resulting high-grade commercial zinc product with a zinc content of up to 7595 is sent to the consumer.

The overall degree of zinc extraction is 99.1 - 99.55.

Example 1.

The dust of dry gas cleaning after the oxygen converter was used as the initial zinc-containing raw material

Mariupol metallurgical plant named after Ilyich with the main chemical composition, mass. 95: BegOz - 59.7; 7p - 2.9;

Mp - 2.8; Ca - 3.4; AI25Oz - 3.6; BIO" - 5.9; Mod - 2.4; In MagO, KO - 0.8; Pb - 0.4. Phase composition:

Mpz2p; 2p x 25102; 7pRegOml; 2pEegOz; 2p Pp2Oz; Without Oh Fractional composition - up to 100 μm.

As a carbon reducing agent, coke screenings with the chemical composition, wt. o: Z - 85.7; 5-1.5; ash - 12.6. Fractional composition - up to 100 μm.

A charge was made with a mass ratio of zinc-containing dust: sifting coke - 1:01, respectively, with a moisture content of 1095 wt. Granules with an optimal diameter of 4 - 10 mm were selected. After drying the pellets to a moisture content of 695, they were fed into a countercurrent rotating drum firing furnace with a temperature in the reaction zone of 95076.

Firing duration - 1 hour. After firing and cooling, the granules were analyzed for the content of zinc and ferric iron. The content of these components is 0.08 and 58.0 wt. 95, respectively.

The dust-gas mixture from the cold end of the furnace was sucked through a layer of carbon reducing agent 900 mm thick with a particle size of 5 - 10 mm and a temperature of 910 "С, it was sent for heat utilization and then sent to gas treatment by known methods, followed by dosing, packaging and sending to the consumer. The captured commercial zinc product contained 72.5 wt. 95 zinc.

The overall degree of zinc extraction was 99.4905.

The results of experiments using different charge components and technological modes are given in Table 1.

Example 2.

The used zinc-containing sludge of wet gas treatment plants of the Mariupol Metallurgical Plant named after Ilyich with chemical composition, mass. 90: 2p - 8.5; Beg2Oz - 59.5; as a carbon reducer, coke screenings were used, similar to example 1, with an initial grain size of 0-10 mm, which had previously been ground to a grain size of less than 100 μm.

The composition of the charge: zinc-containing sludge: fine-dispersed initial carbon reducing agent, respectively - 1:0.2.

Pellets with a diameter of 4 - 10 mm were used for the rebuilding firing in a countercurrent firing furnace after drying them to a moisture content of 5-65.

Firing modes: the temperature in the reaction zone of the firing countercurrent furnace is 1100 "С, the duration of the granules' stay in the reaction zone of the furnace is 1.5 hours.

The efficiency of the process was evaluated by the quality of the commercial zinc product obtained (content of 2p), dezincified granules (content of 21 and Ee) and the overall degree of extraction of 2p from the initial charge.

The dust-gas mixture from the cold end of the furnace was sucked through a layer of the original carbon reducing agent 400 mm thick with particle sizes of 5-10 mm and a temperature of 1000 "С, passed through a heat recovery boiler, sent to gas treatment by known methods with the supply of captured commercial zinc product for dosing and packaging. The content of 7p in the commercial product was 72.8 95. The dezincified granules after the firing furnace contained 0.075 wt. 9o 2p and 59.4 wt. 95 Ev.

The overall degree of zinc extraction was 99.5,905.

Example 3.

A mixture of raw zinc-containing raw materials was used - sludge from the gas treatment plants of the Marteniv shop of the metallurgical plant of JSC "Severstal" with a content of 2p - 2.0 95 and dust from gas treatment plants with a content of 2p - 0.9 95 with a mass ratio of zinc-containing components in the batch of 50:5095. The iron content in both components was approximately 58.8 wt. 95.

A mixture of zinc-containing components with a carbon reducing agent - hard coal up to 100 μm in size was prepared at a ratio of components of 1:0.3 by weight. The moisture content of the granular charge is 14 wt. 95.

Granules with a diameter of 4-10 mm were selected.

Firing mode in a countercurrent firing furnace: temperature 1100 "С, duration of stay of granules in the reaction zone of the furnace - 2 hours.

The dust-gas mixture from the cold end of the furnace was sucked through a layer of carbon reducing agent 600 mm thick with particle sizes of 5-100 mm and a temperature of 1100 °C, then it was sent to heat recovery, then it was sent to gas treatment by known methods with the supply of captured commercial zinc product for dosing and packaging.

The zinc content in the obtained commercial zinc product is 72.195 by mass, the zinc content in dezincified granules is 0.08 mass. 95, iron - 59.8 wt. 95.

The overall degree of zinc extraction was 99.1,905.

Example 4.

The used zinc-containing dust of dry gas treatment after the electric steel melting furnace of the Moldavian Metallurgical Plant with the content of n - 9.9 95 and Re - 60.1 wt. 95. Granules were prepared from a charge consisting of zinc-containing dust and finely dispersed carbon reducing agent (1:0.3), which contains 80 to 95 dusty coke and 20 to hard coal. The moisture content of the initial charge is 15 95.

Pellets with a diameter of 4-10 mm, dried to a moisture content of 5-695, were selected for firing in the furnace.

The regime of the recovery firing of pellets in a countercurrent firing furnace: the temperature in the reaction zone of the furnace is 1100 "С, the duration of the stay of the pellets in the reaction zone of the furnace is 1.8 hours.

The dust-gas mixture from the cold end of the furnace was sucked through a layer of carbon reducing agent 900 mm thick with particle sizes of 5-10 mm at a layer temperature of 910 "С, followed by heat utilization and gas purification by known methods. The zinc content in the obtained commercial zinc product is 65.0 wt. 95, zinc content in dezincified granules - 0.07595, iron - 60.795. The total degree of zinc extraction - 99.0 95.

Example 5. The conditions of the experiment correspond to the data of example 4 with the exception of: - the temperature in the reducing agent layer - 9507C, - the size of the reducing agent particles in the layer - 6 - 15 mm, - the thickness of the reducing agent layer - 350 mm.

It was noted that there was a deterioration in the operation of the gas treatment gas path as a result of an increase in the gas permeability of the carbon reductant layer when working on particles with a size of more than 5 mm and an increase in the slippage of the charge particles through the thin filter layer of the reductant.

The caught commercial zinc product contained 71.095 zinc, zinc content in dezincified granules - 0.0895, iron - 60.195. The total degree of zinc extraction is 98.095.

Thus, this method of processing zinc-containing metallurgical waste due to the absorption of the dust-gas mixture diverted from the cold end of the firing furnace through a layer of carbon reducing agent heated to a temperature of 910 - 1100 "C, allows to increase the through-grade degree of zinc extraction from raw materials and to improve the quality of the commercial zinc product, and as well as to reduce environmental pollution.

Table!

Temperature Size Thickness Through. - layer of dezincification and

Mo: Initial layer of particles in the degree of experiment and type and carbon content n | carbon | carbon commodity extraction of raw materials; ; (c) granules mass 95 | restorer, | restorer, | . zinkovom i zinc, ES MM reducing agent, products still in/,

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Z. Martenovsky sludge and domain dust 5.0-2.9 1100 5-10 721 0.08 | 59.4 98.9 50:5090 4. Dust of electric steel mill 2.5 91- 3-4 65.5 0.0751 60.7 97.0 Vilna 5. Dust of Yuveryurna 0026 |in | in yayu 0 lab osv vve tu 2.8 1150 5-10 400 72.5 0.08 159.8 97.2 converter 7. Converter dust and sludge 2.1-3.5 1000 2-10 800 63.1 0 ... 21 | 80 | about | lu | ee |osvivy shlam Martenovskyi 50:5090

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Claims (3)

1. The method of processing zinc-containing products of metallurgical production, which includes mixing metallurgical production waste with a carbon reducing agent, granulation of the resulting charge, drying and high-temperature processing of granules in a firing furnace, catching zinc distillates by removing the main volume of the dust-gas mixture from the reaction zone of the firing furnace and the outlet the remaining part of the dust-gas mixture from the cold end of the firing furnace, which is characterized by the fact that the dust-gas mixture removed from the cold end of the firing furnace is sucked through a layer of carbon reducing agent heated to a temperature of 910-11002C, and directed to the gas treatment for catching the formed zinc fumes. 2. The method according to claim 1, which differs in that the dust-gas mixture is sucked through a layer of carbon reducing agent with a thickness of 400-900 mm. 3. The method according to one of claims 1, 2, which differs in that the dust-gas mixture is soaked through a layer of carbon reducing agent, which has a size of dispersed particles of 5-10 mm.