WO2008002114A1 - Method for reprocessing lead-containing materials - Google Patents

Abstract

The invention relates to non-ferrous metallurgy, in particular to methods for reprocessing lead-containing materials. The aim of the invention is to increase a lead extraction into a crude metal, to improve a specific performance and to simultaneously reduce the unit costs of energy vectors. The inventive method consists in preparing and drying a mix material, in carrying out roast melting in a suspended state in oxygen atmosphere in such a way that an oxide melt and mixtures of dusts with roast smelting gases are obtained, in reducing the melt during the filtration thereof through a layer of hot parts of a carbon reducing medium in such a way that a pure metal lead, a zinc-containing oxide melt and gases are obtained. The mix material is ground and classified and the separated fraction of dry mix material, 90% of the mass of which consists of particles having size of 0.01-0.10 mm, is supplied at the roast smelting stage. The moisture content of the mix material, during the preparation thereof, is equal to 8-16 % and a coal, in the dry mass of which a total carbon content ranges from about 49 to about 80% and a volatile content from about 11 to about 27%, is used in the form of a ground carbon reducing medium.

Description

 A method of processing lead-containing materials

FIELD OF THE INVENTION The invention relates to non-ferrous metallurgy, and more particularly, to methods for processing lead-containing materials of various origins.

There is an extensive group of lead-containing materials, such as cakes of hydrometallurgical processes, dust of conversion of copper matte, sludge for neutralization and purification of technological solutions that are not processed or are insufficiently processed by known methods and therefore accumulate in dumps. In addition to lead, these materials contain significant amounts of zinc and copper, which reduces the complexity of the extraction of non-ferrous metals from natural mineral raw materials in the processes of its metallurgical processing. At the same time, the storage of lead-containing materials creates complex environmental problems. Thus, expanding the range of processed lead-containing materials is an urgent task of technology and environmental protection.

State of the art

There is a method of processing lead-containing materials with an increased proportion of sulfates and oxides such as lead cakes, pies, battery pastes, etc. mixed with fine-grained lead concentrates, circulating dusts, fluxes, coal dust - QSL method, based on the principle of bubble bubbling (Mager K., Schulte A. Production and Technological Aspects of the First Four Industrial QSL Plants. Proceedings of the International Symposium on Primary and Secondary Lead Processing. Halifax, Nova Scotia, Canada, August 20-24, 1989, published Pergamon Press, New York, pp. 15-26). The method consists in the fact that the mixture is granulated and the resulting wet granules are loaded onto the surface of the oxide melt, which contains from 35 to 60% lead in the form of oxides. An oxygen-containing gas is blown through this oxide melt and a layer of metallic lead beneath it. As a result of the interaction at a temperature of 850-950 ° C of sulfides of raw materials with lead oxides, draft lead is formed, which partially passes into the oxide melt as a result of its oxidation with an oxygen-containing gas. By regulating the loading of granules and the flow rate of oxygen-containing gas, a constantly high concentration of lead oxides in the slag is achieved and the rate of formation of blister lead over its oxidation by oxygen-containing gas prevails. The resulting oxide melt with a temperature not exceeding 95O ⁰ C continuously enters the reduction zone, where, as the slag moves to the outlet the melt temperature is gradually increased to 1150-1250 ⁰ C due to gas heating. At the same time, the reduction of lead oxides to rough lead is carried out by blowing the melt with a mixture of air with a tear-shaped or gaseous carbon material (coal, natural gas, etc.). The disadvantages of this method are the low extraction of lead into the crude metal, low specific productivity of the process and at the same time high specific costs energy carriers (oxygen-containing gas, carbon materials). This is due to the fact that a decrease in the concentration of lead in the oxide melt leads to the need to increase the temperature of this melt at the oxidative and reduction stages of the process and, accordingly, to increase the yield of lead in smelting dust (up to 50% or more of its mass in the charge). When processing lead-containing materials with a lead concentration of less than 30% and an oxidation state of iron of more than 50-60%, the smelting process is practically disrupted due to the formation of a viscous oxide melt unsuitable for gas purging. There is also a method for processing lead-containing materials with an increased proportion of sulfates and oxides such as lead cakes, dusts, battery pastes, etc. mixed with lead sulfide concentrates, circulating dusts, fluxes, coal dust - the Ausmelt method, also based on the principle of bubble melting (Moncy EH , Piret, H. L., “Aycmelt Lead Smelting Technology Review. Proceedings of the 2000 Lead and Zinc Symposium. Pittsburgh, USA, October 22–25, 2000, 149-169). The method consists in the fact that the specified well-averaged mixture in a fine-grained or granular form is loaded onto the surface of the oxide melt with a lead concentration of 25 to 60%. From above, an oxygen-containing gas is blown into the volume of the oxide melt, and with a deficiency in the heat balance of the process, also pulverized, liquid or gaseous carbonaceous fuel. As a result of the interaction at a temperature of 1000-1100 ° C of sulphides of raw materials with lead oxides, draft lead is formed, which partially passes into the oxide melt as a result of its oxidation with an oxygen-containing gas. By controlling the charge of the charge and the flow rate of oxygen-containing gas, a constantly high concentration of lead oxides in the slag is achieved and the rate of formation of blister lead over the rate of its oxidation by oxygen is prevailing. The resulting oxide melt with a temperature not higher than HOO ⁰ C is transferred to the reduction stage of the process in a continuous or batch mode, or it is released and granulated for the subsequent processing of solid lead slag in the reduction stage to obtain crude lead. The reduction of lead oxides to rough lead from the rich lead slag of the oxidative stage of the process is carried out by blowing melt by a mixture of air with dusty, liquid or gaseous carbonaceous material (coal, fuel oil, natural gas, etc.). A significant increase in energy costs with a concomitant increase in the temperature of the oxide melt allows us to transfer this process from the mode of smelting crude lead to the mode of sublimation of lead (and partially zinc) in dust, melts, which can then be separately processed in the same way to produce crude lead.

The disadvantages of this method are the low extraction of lead into the raw metal, low specific productivity of the process and at the same time high specific costs of energy carriers (oxygen-containing gas, carbon materials). The closest in technical essence is the method of processing lead-containing materials, such as lead and zinc cakes, converter dust, sludges for hydrolytic cleaning of technological solutions, in which mainly simple and complex sulfates and metal oxides are present, including thermally stable sulfates (lead, calcium) and higher iron oxides (patent PK N ° 9, C 22 V 13/02, 1997).

According to this method, a wet mixture is prepared from the initial lead-containing materials and fluxes with the introduction of a pulverized sulfide material into it to reduce the mass ratio of the sum of sulfide, elemental and pyrite sulfur to the total sulfur content of the mixture from 0.08 to 0.87 and / or pulverized carbonaceous material based on from 4 to 12 kg of pure carbon per 100 kg of ferric iron and from 20 to 140 kg of pure carbon per 100 kg of sulfate sulfur. In this case, a pulverized carbonaceous material with an activation energy of the carbon gasification reaction in the range of 56-209 kJ / mol is introduced. Lead sulfide concentrates or lead (polymetallic) ore are used as pulverized sulfide material. The resulting wet mixture with a recommended moisture content of 2 to 16% is dried to a residual moisture content of less than 1%. The dried mixture is fed to the stage of firing-smelting in suspension in an atmosphere of oxygen-containing gas to obtain a dispersed oxide melt and a mixture of powders with firing gases-smelting. The dispersed oxide melt obtained in the firing-smelting stage is restored by filtering it through a layer of heated particles of crushed carbon material (coke or coal) with a grain size of 2-50 mm to produce blister lead, lead-depleted zinc-containing slag and gases mixed with firing gases swimming trunks. Dust is separated from the reaction gas mixture and returned to the smelting step. At the stage of preparing a wet mixture, under conditions of thorough mixing materials containing natural binders (soluble salts, metal hydroxides and hydrates, gypsum), and in the presence of free moisture in the charge of at least 2%, it is structured with the formation of “complex” microconglomerates from heterogeneous particles, including oxidized components (sulfates and oxides metals), as well as reducing agents (metal sulfides and carbon). Bundles formed at the stage of preparation of the wet mixture between dissimilar particles in microconglomerates are hardened at the stage of the mixture drying. This provides thermal stability of the microconglomerates of particles under conditions of rapid heating of a dry pulverulent charge at the stage of firing-smelting. The presence of close contact of sulfate and oxide components with sulfides and carbon in the volumes of microconglomerates provides a significant acceleration of the process of desulphurization of the charge and decomposition of higher iron oxides at the stage of firing and smelting of the tinned charge in suspension at temperatures of 1250-1350 ⁰ C. Acceleration of the decomposition of sulfates and higher oxides iron at temperatures of 300-500 ⁰ C below their thermal decomposition temperatures due to the occurrence of intense amounts of particles are chemically dissimilar mikrokonglomeratov x species interactions:

Me ¹ SO ₄ + Me ² S → Me ¹ O (Me ¹ ) + Me ² O (Me ² ) + SO ₂ ; (one)

Me ¹ O + Me ² S → Me ¹ O (Me ¹ ) + Me ² O (Me ² ) + SO ₂ ; (2)

Fe ₂ O ₃ + MeS → Fe ₃ O ₄ + MeO + SO ₂ ; (3)

Fe ₃ O ₄ + MeS → FeO + MeO + SO ₂ ; (4) "MeSO ₄ + C → MeO (Me, MeS) + CO ₂ + SO ₂ ; (5)

MeO + C → Me + CO; (6)

Fe ₂ O ₃ + C → Fe ₃ O ₄ + СО; (7)

Fe ₃ O ₄ + C → FeO + CO. (8)

The disadvantages of this method are the low extraction of lead into the raw metal, the low specific productivity of the process and at the same time high specific costs of energy carriers (oxygen-containing gas, carbon materials and electricity).

These disadvantages are determined by the fact that the known method does not provide a sufficiently high content and optimal sizes of thermally stable "complex" microconglomerates in a dry charge fed to the stage of firing-smelting in suspension. Both of these factors are due to the uncontrolled process of adhesion or disintegration of microconglomerates of particles at the stage of drying a wet mixture.

When the moisture content of the mixture supplied to the drying stage is 2-7%, regardless of the content of the binder components in it, free moisture is not enough for the formation of ligaments between particles sufficient for the mechanical and thermal stability of the formed microconglomerates. This leads to mechanical disintegration and decription of thermally unstable microconglomerates at the stages of drying and firing-melting of the charge. As a result, the content of "commercially available" microconglomerates of particles decreases and the mass fraction of individual dispersed particles in the mixture at the firing-smelting stage increases. With a higher moisture content of the charge supplied to the drying stage, the amount of free moisture becomes enough to form a significant amount of stable bonds between particles. However, uncontrolled adhesion of particles during the drying of the material leads to the formation of a coarse-grained structure of a dry mixture with the possible formation of excessively large pieces of adhering particles, the firing of which in suspension is impossible without additional grinding.

Both the low content of thermally stable “complex” micro-conglomerates in the dry charge fed to the firing-smelting stage, and their too large sizes noticeably reduce the efficiency of processing lead-containing materials with an increased proportion of sulfates, higher iron oxides and zinc oxides in a known manner. A low proportion of “complex” microconglomerates in a dry charge reduces the degree of contact of dissimilar reagent particles, and the large sizes of microconglomerates reduce their heating rate at the stage of firing and smelting of the charge. Both of these lead to a decrease in the intensity of low-temperature interactions of charge components by reactions (l) - (8), and necessitates increasing the firing temperature-melting 1400-145O to ⁰ c for more complete decomposition of thermally stable sulfates and increasing the fluidity of the oxide melt with a high content you Shih iron oxides.

Elevated firing-melting temperatures lead to relatively high specific consumption of pulverized carbonaceous fuel and oxygen for its oxidation, as well as to a significant increase in the yield of recycled dusts, while not allowing to reduce the content of higher iron oxides in the dispersed oxide melt.

The viscosity of oxide melts saturated with higher iron oxides increases as lead oxide is reduced in a layer of crushed carbon material. As a result, the inhibition of the filtration process and the reduction of oxide melt increases, aggravated by significant heat absorption on the reduction of higher iron oxides. Maintaining high fluidity and increasing the degree of reduction of the oxide melt under these conditions requires an increase in heat supply or a decrease in the load of the oxide melt at the reduction stage of the process. Thus, the known method does not provide an effective implementation low-temperature interactions of the charge components at the firing-smelting stage and subsequent effective reduction of oxide melts in a layer of crushed carbonaceous reducing agent.

Moreover, one of the significant factors in reducing the effectiveness of the known method is the underestimated lower limit of the recommended range of free moisture content in the wet mixture supplied to the drying stage.

Additional factors of reduced effectiveness of the known method may be the use of recommended carbon materials to form a layer of crushed carbonaceous reducing agent. The use of coke, which has the lowest reactivity in a series of carbon materials, causes a relatively low rate of reduction of the oxide melt when it is filtered through a layer of crushed reducing agent, thereby limiting the specific productivity of the process.In order to increase the rate of reduction, an increase in the temperature of the oxide melt is required. However, an increase in its temperature at the stage of firing-smelting of the charge leads not only to an increase in the specific consumption of energy carriers (pulverized fuel and oxygen for its combustion), but also to a decrease in the extraction of lead into the crude metal due to an increase in the degree of transition of lead in firing-smelting dust. At the same time, an increase in the proportion of recycled pews in the charge can reduce the specific productivity of the process to a greater extent than allows it to increase the increase in temperature of the oxide melt at the stage of firing and smelting of the charge.

The reactivity of coal is higher than that of coke. However, unlike coke, not all coals are thermally stable under conditions of rapid heating and, falling on the surface of the slag bath, they can de-crush. In this case, the permeability of the crushed carbonaceous reducing agent layer for the dispersed oxide melt is noticeably reduced or completely broken. Accordingly, the surface and the rate of reduction reactions decrease. This leads to a corresponding decrease in the extraction of lead in the crude metal and the specific productivity of the process (up to its complete violation). In addition, the need to increase the fluidity and, accordingly, the temperature of the oxide melt with a decrease in the permeability of the crushed reducing agent layer causes an inevitable increase in the specific consumption of energy carriers in this case.

The basis of the invention is the task of changing the known method of processing lead-containing materials with an increased concentration of thermally stable sulfates and higher iron oxides in such a way as to increase the recovery of lead in the base metal and the specific productivity of the process while reducing unit costs of energy carriers.

Summary of the invention. This object is achieved in that in a method for processing lead-containing materials, including the preparation of a mixture by thoroughly mixing moist sulfide and oxidized lead-containing materials with fluxes and dusty carbonaceous material, in which the mass ratio of the sum of sulfide, elemental and pyrite sulfur to the total sulfur content in the charge is 0 , 08-0.87, and a pulverized carbonaceous material with an activation energy of the carbon gasification reaction in the range of 56-209 kJ / mol is introduced as a reducing agent based on 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulfate sulfur in the charge; drying the resulting wet mixture to a residual moisture content of less than 1%; firing-melting of a dry charge in suspension in an oxygen atmosphere to obtain a dispersed oxide melt and a mixture of dusts with firing gases; restoration of the dispersed oxide melt during its filtration through a layer of heated particles of crushed carbon reducing agent with a particle size of 2-50 mm to obtain metallic lead, zinc-containing oxide melt and gases mixed with dusts and firing gases; separation of the obtained mixture of dusts and reaction gases with the return of dusts to the firing-smelting stage, the dry charge is subjected to grinding and classification, and the separated fraction of the dry charge is fed to the firing-melting stage, at least 90% of the mass of which is made up of particles with sizes 0.01-0 , 10 mm.

It is desirable that the free moisture content in the charge at the stage of its preparation was 8-16%.

It is advisable that, as a crushed carbon reducing agent, coal is fed to the stage of recovery of the dispersed oxide melt with a total carbon content of about 49 to about 80% and a volatile content of about 11 to about 27% in the dry mass.

The achievement of the task in the implementation of the proposed solutions is ensured by the following factors: - the formation of the microstructure of the mixture with a high proportion of mechanically and thermally stable microconglomerates of heterogeneous particles, including sulfate, oxide, sulfide and carbon components;

- stabilization of the optimal fractional composition and microstructure of the dry mixture fed to the stage of firing-smelting in suspension; - intensification of low-temperature interactions of sulfate and oxide components with sulfides and carbon at the stage of firing-melting of the mixture in suspension;

- intensification of the reduction of oxide melt while maintaining the porous structure and permeability of the crushed carbon reducing agent layer. Morphological studies of the mixture found that the minimum size

“Complex” microconglomerates of heterogeneous particles amount to about 0.01 mm. The more dispersed fractions of the charge are individual, unassociated particles, or microconglomerates of the same type of highly dispersed particles of lead-containing materials with enhanced adhesive properties (such as dust, cake, sludge).

From the analysis of the results of the experimental melts, it is known that an increase in the fraction of fine fractions with particle sizes less than 0.01 mm, as well as an increase in the fraction of coarse fractions with individual or associated particle sizes greater than 0.1 mm in a dry charge, leads to a decrease in its rate and degree of conversion components at the stage of firing-smelting in suspension and prevents the achievement of the task.

The negative effect on the process indicators of the increased proportion of fine and coarse fractions in the material of the dry charge is successfully eliminated by the introduction of successive operations of grinding and classification of the dry charge before feeding it to the firing-smelting stage.

The combination of grinding and classification operations ensures the production of a selected fraction of a dry mixture, at least 90% of the particle mass of which is in the size range of 0.01-0.10 mm, which allows:

- to keep in a dry charge after grinding the microconglomerates of heterogeneous particles, including sulfate, oxide, sulfide and carbon components;

- limit the entry to the stage of smelting an excessively small (less than 0.01 mm) and excessively large (more than 0 D0 mm) individual particles and microconglomerates that prevent an increase in the degree of desulfurization of the charge and decomposition of higher iron oxides at the stage of firing and smelting of the mixture at low temperature conditions process.

Thus, stabilization of the fractional composition of the dry charge in the range of prevailing particle sizes of 0.01-0.10 mm allows you to effectively solve the problem.

An increase in direct extraction of lead into the crude metal, an increase in the specific productivity of the process, and a simultaneous decrease in specific energy consumption achieved by:

- prevent the formation of poor matte;

- reduction of dust removal and the proportion of recycling dust of the smelting in the mixture;

- increasing the degree of reduction of lead from a fluid oxide melt in a layer of crushed carbonaceous reducing agent;

- reducing the consumption of pulverized carbonaceous fuel, oxygen for its combustion and electricity to compensate for heat losses from the reduction reactions of higher iron oxides in the layer of carbonaceous reducing agent.

Reducing the lower limit of particle size of a dry charge to less than 0.01 mm reduces the degree of low-temperature interactions of its components at the stage of smelting by reactions (l) - (8) due to a decrease in the fraction of “complex” microconglomerates in the charge. This necessitates an increase in the temperature of the process. In addition, the mechanical removal of fine particles in the firing dust is increasing. In aggregate, this leads to a decrease in the extraction of lead into the crude metal, a decrease in the specific productivity of the process, and an increase in the specific consumption of energy carriers.

An increase in the upper size limit of dry batch particles above 0.10 mm reduces the degree of low-temperature interactions of its components at the firing stage by reducing the heating rate of large particles and reducing the total reaction surface of the components, which also necessitates an increase in the process temperature and impedes the achievement of the task .

A decrease in the mass fraction of particles with sizes from 0.01 to 0.10 mm in a dry charge is lower than 90%, as in the case of changing the limits of the optimal range of particle sizes, causes a decrease in the degree of low-temperature interactions of its components at the stage of firing-smelting. This can occur both due to a decrease in the share of “complex” microconglomerates, and due to an increase in the share of excessively large individual particles and microconglomerates in a charge. Both that and another necessitates an increase in the temperature of the process. As a result, the extraction of lead into the crude metal and the specific productivity of the process are reduced, and the specific consumption of energy carriers increases.

According to the patented method, thorough mixing of the materials at the stage of preparation of the wet mixture is preferably carried out with a free moisture content of the mixture mixture of 8-16%. Based on the experimental data, this allows you to:

1) to form a homogeneous microstructure of the mixture with a large share of "complex" microconglomerates of heterogeneous particles, including sulfate, oxide, sulfide and carbon components;

2) to form a sufficient number of strong bonds between dissimilar particles, providing thermal stability of "complex" microconglomerates at the stage of firing-melting of a dry mixture. The indicated range of free moisture contents is optimal, since it provides the most significant increase in the share of “complex” microconglomerates in the charge at the stage of its preparation and hardening of these microconglomerates at the stage of drying the wet mixture.

When the free moisture content is less than 8%, the proportion of “complex” microconglomerates in the wet charge supplied to the drying stage, as well as the mechanical and thermal stability of such microconglomerates in the dry charge is reduced. This reduces the degree of interaction of the components of the charge at the stage of firing-smelting and leads to a deterioration of the process in the framework of solving the problem.

With a free moisture content of 8% or more, the proportion of “complex” microconglomerates in the wet mixture fed to the drying stage increases markedly. The mechanical and thermal stability of such microconglomerates in a dry charge also increases. Despite the fact that in this case, as in the prototype, uncontrolled adhesion of particles occurs at the drying stage, the use in the patented method of sequential grinding and classification of the dry charge eliminates the ingress of its excessively large fractions to the firing-smelting stage. Thus, the possibility of the most effective process.

An increase in the free moisture content in the charge of more than 16% is impractical, since it does not lead to a noticeable increase in the share of “complex” microconglomerates in the dry charge at the stage of firing and smelting and, thereby, to improve process performance in the framework of solving the problem. At the same time, the evaporation of excess moisture requires an increase in fuel consumption for drying the charge, that is, it increases the total specific costs of energy carriers.

As a crushed carbonaceous reducing agent of the dispersed oxide melt from the stage of firing and smelting the charge in the prototype, coke or coal is proposed. Due to the presence of active hydrocarbons (volatile) and lower activation energy of the gasification reaction of solid carbon, coal, as a rule, has a higher reducing ability than coke. However, unlike coke, not all coals have thermal stability and can be decrypted upon rapid heating on the surface of the slag bath, which is not taken into account in the prototype. At the same time, coal decryptation can not only drastically reduce the degree of reduction of oxide melt

Yu in the layer of crushed carbon reducing agent, but also completely disrupt the course of the recovery process. The thermal stability of coal is directly related to the property of its sintering during calcination. The higher the sintering ability of coal, the higher its thermal stability. Based on this relationship and the analysis of experimental data, the optimal range of quality of coals with a sufficiently high thermal stability is identified. According to the patented method, it is advisable to use coal with a total carbon content of about 49% to about 80% and a volatile content of about 11% to about 27% as a crushed carbon reducing agent.

The use of coal with a specified range of total carbon and volatile as a crushed carbon reducing agent enhances the efficiency of the reduction stage of the process by increasing the activity of the reducing agent while maintaining the developed reaction surface and high permeability of the crushed reducing agent layer for the dispersed oxide melt. This allows you to further increase the extraction of lead in the raw metal and the specific productivity of the process without increasing the temperature of the oxide melt, thereby providing additional savings in specific energy costs.

On the one hand, the total carbon in the dry mass of coal consists of solid carbon and volatile carbon, and on the other hand, solid carbon and volatiles form the basis of the dry mass of coal. Thus, the recommended limits for the total carbon and volatiles in the dry mass of coal are closely interrelated, and therefore it is advisable to consider them together.

With a decrease in the total carbon content in the dry mass of coal below about 52% and a concomitant increase in this mass of volatiles above about 27%, the sintering ability of the coal upon calcination and its thermal stability under conditions of rapid heating noticeably decrease. An increase in the degree of decription of pieces of crushed coal on the surface of the slag bath reduces the permeability of the carbonaceous reducing agent layer. As a result, the rate of reduction of the oxide melt, the degree of extraction of lead into the crude metal, and the specific productivity of the process are interconnectedly reduced. In addition, a decrease in the intensity of the recovery stage of the process leads to an increase in the specific costs of energy carriers, due to the need to increase the fluid flow rate and, accordingly, the temperature of the oxide melt, as well as to compensate for the increasing heat loss due to its recovery and settling.

With an increase in the solid carbon content in the dry mass of coal above about 80% and a concomitant decrease in this mass of volatiles below about 10%, the sintering ability of the coal during calcination and its thermal stability under conditions of rapid heating is also markedly reduced. This is determined by the optimal character of coal sintering due to the presence of bituminous substances in their composition - products of the conversion of waxes, resins and fatty substances contained in coal-forming plants. The share of such substances decreases both in coals with a low degree of metamorphism - lignites, and in coals with a high degree of metamorphism - anthracites. The dependences of the coal sintering capacity on the content of total carbon and volatiles in their dry mass, expressed in arbitrary units, are shown in figures 1 and 2. From the presented data it is seen that the recommended in the patented method coal with a total carbon content in the dry mass of from about 49% to about 80% and volatile from about 11% to about 27% have the highest sintering ability. The decrease in sintering ability and thermal stability of coal, as described above, leads to a deterioration in the performance of the process as part of the solution of the problem.

The method is carried out in the unit, the schematic diagram of which is shown in figure 3. The unit consists of a vertical reaction shaft 1 of rectangular cross section, in the arch of which is installed a burner device 2 for feeding the charge, oxygen, recycling pans and crushed carbon reducing agent; a vertical partition 3 with water-cooled copper elements separating the reaction shaft 1 from the gas outlet shaft 4 while maintaining a gas clearance above the slag bath to discharge reaction gases; an electric furnace 5 adjacent to the melting chamber and separated from it by a vertical partition 6 with water-cooled copper elements immersed in a slag bath; common to the reaction shaft 1, electric furnace 5 and gas exhaust shaft 4 hearth 7; coffered belt 8 and devices for the release of smelting products 9.

The method is as follows.

Using the data of chemical analysis of lead-containing materials, such as lead concentrates, dusts, cakes and pshamas from hydrometallurgical plants, battery pastes, blasting lead refining rates and others, they calculate the proportions and mix these materials in such a ratio that the mass ratio of the sum of sulfide, elemental and pyrite sulfur to the total sulfur content in the charge is 0.08-0.87. Fluxes (limestone, silica sand, etc.) and a dusty carbonaceous reducing agent are added to the resulting mixture of wet lead-containing materials. Various types of coals (lignites, bituminous and charcoal), coal concentrates obtained from clinker from Wielding, coke production wastes and others can be used as a pulverized carbonaceous reducing agent. To achieve the optimal combination of the zones of heat generation and absorption according to the reactions of the transformation of the charge components at the stage of firing-melting, it is advisable to introduce pulverized carbonaceous materials into it with an activation energy of the carbon gasification reaction in the range of 56-209 kJ / mol. The addition of a carbon-like carbon reducing agent is carried out at the rate of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulfate sulfur in the charge. The resulting mixture with a free moisture content of 8-16% is subjected to homogenization by thoroughly mixing the materials. This allows you to form a homogeneous microstructure of the mixture with a large share of "complex" microconglomerates of heterogeneous particles, including sulfate, oxide, sulfide and carbon components. If the free moisture content in the charge is less than 8%, first moisten the charge to this minimum level, and then homogenize it. When the content of free moisture in the mixture is more than 16%, it is advisable to first homogenize it, and then remove the excess of free moisture (for example, by filtering the material) in order to avoid excessive fuel consumption for drying the mixture.

Wet homogenized mixture is fed to the drying stage, where it is dried to a residual moisture content of less than 1%.

The obtained dry mixture containing large fractions of adhering particles is subjected to grinding, and the crushed tanned material is classified. A large fraction of a dry pulverulent mixture with a predominant particle size of more than 0.10 mm is returned to grinding, a dispersed fraction with a predominant particle size of less than 0.01 mm is returned to the stage of preparation of a wet mixture, and a fraction of at least 90% of the mass is made up of particles with a size of 0 , 01-0.10 mm - at the stage of firing-smelting. This ensures that a significant fraction of thermally stable “complex” microconglomerates formed at the stages of preparation and drying of the wet mixture is preserved in the dry pulverized charge fed to the firing-smelting stage. If there is a lack of calorific value of the dry charge, the required amount of carbon-like carbon fuel is introduced into it. As such, the same tan carbonaceous material can be used, which was introduced into the wet mixture as a reducing agent of higher iron oxides and sulfates at the stage of its preparation, or another dusty carbonaceous material having a high calorific value. Before feeding to the firing-smelting stage, recycled process dusts and a carbonaceous reducing agent crushed to a particle size of 2-50 mm, preferably 5-20 mm, are added to the charge. As a crushed carbon reducing agent, various carbon materials can be used - coal or petroleum coke, Weltz clinker, charcoal and others. However, according to the patented method, it is preferable to use coal as a crushed carbonaceous reducing agent, the dry mass of which contains from about 49 to about 80% of the total carbon and from about 11 to about 27% volatile. Coals of this quality have a sufficiently high sintering ability and thermal resistance, which allows forming a stable porous structure of the crushed carbon reducing agent layer with a developed reaction surface and high permeability for the reduced oxide melt. Due to the presence of an active hydrocarbon component and reduced activation energy of the carbon gasification reaction, such coals are a more active carbon reducing agent than carbon materials that have undergone heat treatment (cokes). A dry tanned mixture together with pulverized carbonaceous fuel (if necessary), circulating dusts and crushed carbonaceous reducing agent is fed through a vertical burner 2 to the reaction shaft 1 for suspended calcination in an atmosphere of oxygen-containing gas.

Oxygen consumption is set based on the total degree of desulfurization and oxidation of lead, zinc and iron sulfides to oxides and carbon fuel to carbon dioxide and water vapor minus the consumption of metal sulfates and higher iron oxides in the reaction with sulfide, elemental and pyrite sulfur and carbon dust reducing agent in accordance with the stoichiometry of the total reactions: 3Me ¹ SO ₄ + Me ² S → 3Me ¹ O + Me ² O + 4SO ₂ ; (9)

3Fe ₂ O ₃ + MeS → _. 6FeO + MeO + SO ₂ ; (10)

2MeSO ₄ + C → 2MeO + CO ₂ + 2SO ₂ ; (eleven)

2Fe ₂ O ₃ + C → 4FeO + CO ₂ . (12)

In other words, the oxygen consumption is reduced by an amount determined by the amount of oxygen “bound” to sulfates and higher iron oxides. In addition, oxygen is not introduced to oxidize the pure carbon of the carbonaceous reducing agent.

Under the influence of high temperatures in the reaction shaft, the pulverized charge ignites, quickly heats up to temperatures of 1250-1350 ⁰ C due to the oxidation by oxygen of the gas phase of a part of sulfides and pulverized carbonaceous material. At the same time, intense interactions of sulfates and metal oxides (including higher iron oxides) with sulfides and carbon occur in volumes of “complex” microconglomerates of particles in the temperature range 350–700 ° C. The result is a dispersed oxide melt with a lower content of higher iron oxides, which has high fluidity, and a mixture of dusts with sulfurous reaction gases. Crushed carbonaceous reducing agent supplied with the charge, thanks to the large sizes of its pieces (mainly 5-20 mm), as well as the rapid decrease in the concentration of oxygen in the gas phase along the height of the reaction shaft 1 (above the mirror of the slag bath, the oxygen concentration is about 1-2%), does not have time to burn in the reaction shaft 1 and forms on the surface of the slag melt under the burner 2 a porous, continuously replenished recovery layer of highly heated pieces of carbon material. The dispersed oxide melt obtained by firing and smelting the mixture is filtered through this layer of crushed carbonaceous reducing agent. In this case, lead oxides are reduced to metal, higher iron oxides - to wustite, and zinc oxides do not have time to recover to a significant degree and together with wustite and fluxing components form lead-depleted zinc slag. Copper oxides, similarly to lead oxides, are reduced in a layer of a carbon reducing agent to a metal and converted to crude lead, while non-ferrous metal sulfides present in a dispersed fusion-smelting melt are either distributed between the metal and slag phases (with a degree of desulfurization of the charge of more than 90-94% ), or form a dispersed matte phase. The gaseous products of the reduction reactions (CO, CO ₂ and zinc vapors) come out of the crushed reducing agent layer and mix with the gases and dusts of the smelting-firing.

Lead depleted of zinc zinc slag with a dispersed suspension of metallic lead (and matte, if one is formed) flows into an electric furnace 5 adjacent to the reaction shaft 1 under a partition 6 separating them from water-cooled copper elements buried in a slag bath. In an electric furnace 5, a dispersed suspension of metal (and matte) settles with the formation of phases of melting products: rough lead, zinc-slag depleted in lead, and polymetallic matte, if any. As a rule, the matte phase is formed when the processed lead-containing materials contain an increased amount of copper. This makes it possible to carry out crude decontamination of crude lead with the release of excess copper from the processed lead-containing materials into polymetallic gptein directly in the unit. After settling, zinc slag, rough lead (and matte) are discharged from the electric furnace through devices for the release of smelting products 9 and sent for further processing by known methods to obtain marketable products (not shown in FIG. 3). Refined lead is refined, zinc-slag is fumigated or welded with zinc extracted into oxidized zinc sublimates, polymetallic matte is converted to blister copper.

The resulting mixture of reaction gases and firing firing dusts flows under the baffle 3 into the gas exhaust shaft 4 adjacent to the reaction shaft 1 .. B gas exhaust shaft 4, the reaction gases are burned to the complete oxidation of carbon monoxide and zinc vapor and are cooled by heat exchange with the surfaces of the water-cooled elements built into the shaft. Cooled to 800-1000 ⁰ C, the mixture of reaction gases and poods enters the recovery boiler, where it is cooled to 400-500 ⁰ C, and then to the electrostatic precipitator (not shown in figure 3), where the dust is separated from the sulfurous reaction gases and returned to firing-melting with the charge. Sulfur gases are sent to utilize sulfur to produce marketable products (sulfuric acid, elemental sulfur, sulfuric anhydride or salts).

For a better understanding of the present invention, examples are provided illustrating the proposed method.

Example 1 (prototype). In a semi-industrial installation, according to the known method, the mixture was prepared from sulfide lead concentrates, lead dust, lead-containing zinc cake, battery paste, quartz and lime fluxes, the mass ratio of the total sulfide, elemental and pyrite sulfur to the total sulfur content of which was 0 , 6. As a reducing agent for sulfates and higher iron oxides, brown coal was introduced into the charge with an activation energy of the carbonization gasification reaction of 135.2 kJ / mol at the rate of 10 kg of pure carbon per 100 kg of ferric iron and 80 kg of pure carbon per 100 kg of sulfate sulfur. The prepared mixture having the composition,%: 28.27 lead; 8.29 zinc; 0.97 copper; 13.02 total iron (including ferric iron - 10.03); 8.01 total sulfur (including sulfate - 3.09); 12.01 silicon dioxide; 6.01 calcium oxide and a free moisture content of 10.7% were dried to a residual moisture content of 0.8% and charged through a burner to a smelting kiln in suspension in a technical oxygen atmosphere (96%). To compensate for the low calorific value, the required amount of pulverized coal used in the preparation of the wet mixture and having the composition: 43.76% solid carbon, 38.46% volatile and 17.78% ash containing,%: 6 was added to the charge as fuel. 4 iron, 52.1 silicon dioxide, 5.2 calcium oxide. Together with the charge, circulating smelting dust and crushed carbonaceous reducing agent were loaded into the burner, as coke breeze with a particle size of 5-20 mm, composition,%: 86.64 solid carbon, 4.31% volatile and 9.05% ash containing,%: 12.6 iron, 57.1 silicon dioxide, 10.3 calcium oxide.

Lead-containing materials and fluxes were transferred to a dispersed oxide melt in a psc-oxygen torch of the burner, and coke fines, not having time to burn, fell on the surface of the slag bath, forming a heated layer on it carbon reducing agent. The dispersed oxide melt of the firing-melting mixture in suspension, seeping through this layer, was restored. In this case, lead oxides were reduced to metal, higher iron oxides - to wustite, and zinc remained in the oxide melt (slag). As a result, crude lead, zinc slag, and dusty gases from the reaction shaft were obtained, which were cooled and cleaned of dust that was continuously returned to smelting together with the charge.

The melting mode was controlled by the degree of desulfurization of the charge and the temperature of the oxide melt at the bottom of the plume. For this purpose, sampling of the flare melt over a layer of carbon reducing agent was carried out and analyzed for sulfur content. At the same time, the temperature was measured at the same point, which was controlled by changing the flow rate of the charge, pulverized coal, and oxygen.

In total, 28 tons of dry charge were processed in the experiment. The resulting average performance indicators of the process within the solved problem of the patented method are shown in table 1, experiment 1. Example 2. According to the claimed method, the experiment is carried out as in Example 1, but differs in that the mixture is dried to a residual content of 0.8% grinding in various modes and classification, in which three fractions are distinguished. A large fraction of the charge is sent for re-grinding, a small fraction for the preparation of a wet mixture, and the middle for firing. Depending on the grinding conditions and classification, the upper and lower limits of the particle size range are changed, the mass fraction of which is 90% of the dry charge fed to the firing and smelting stage. The results of swimming trunks are shown in table 1, experiments 2-6.

Example 3. The method is carried out as in Example 2, but differs in that the selected dry charge fraction with a predominant particle size range from 0.01 to 0.1 mm is fed to the smelting furnace, and the mass fraction of this fraction in the charge varies depending from the conditions of its grinding and classification. The results are shown in table 1, experiments 7-8.

As can be seen from the table (experiments 1-8), the objectives of the patented method, namely: increasing the extraction of lead in ferrous metal (column 7), increasing the specific productivity of the process (column 8) and reducing the specific energy costs (columns 9-12), are simultaneously achieved when introducing the operations of grinding and classification of a dry mixture, as a result of which a selected fraction of the mixture is fed to the firing melting, at least 90% of the mass of which is made up of particles with sizes of 0.01-0.10 mm. With the optimal fractional composition of the dry charge is observed (compare experiments 1, 3-5 and 7): an increase in the extraction of lead in the crude metal by 2.5-2.7%, an increase specific productivity on the charge of 5.3-6.1%, a decrease in the unit cost of energy for smelting by 13.4-14.8%.

Example 4. The method is carried out, as in Example 2, under the conditions of grinding and classification of a dry mixture, in which 90% of the mass supplied to the firing-melting mixture is made up of particles with sizes of 0.01 - OD 0 mm (experiment 3), but differs in that that the free moisture content in the charge at the stage of its preparation is different (2, 8, 16 and 20%), and it is dried to the same residual moisture content of 0.8%. As follows from the results obtained in Table 2, experiments 9-12, the optimal process indicators are achieved with 8-16% free moisture in the charge at the stage of its preparation, due to the allocation of the optimal fractional composition of the dry charge. An additional effect due to the formation of a more stable microstructure of the mixture with a recommended increase in the minimum permissible free moisture content in the mixture from 2 to 8% is (compare experiments 9 and 10): increase in the extraction of lead in ferrous metal by 2.0%, increase in specific productivity by charge by 0.3%, a decrease in specific energy costs for smelting by 1.6%.

Example 5. The method is carried out, as in Example 2, experiment 3, but differs in that as a crushed carbon reducing agent, instead of coke breeze with a particle size of 5-20 mm, coal of different quality with the same grain size is used. The results are shown in table 3, experiments 13-17. According to the data obtained, the use of coal as a crushed reducing agent can increase the efficiency of the process (compare with experiment 3), and the maximum additional effect is observed in the recommended range of contents in the dry weight of coal from about 49 to about 80% of the total carbon and from about And to about 27 % volatile. The maximum additional effect from the use of coal as a crushed carbon reducing agent was observed in experiment 15 and amounts to: an increase in lead extraction into a ferrous metal by 2.3%, an increase in the specific productivity of a charge by 0.3%, a decrease in specific energy costs for smelting by 5, 5%. The mass of dry mixture processed in each of experiments 2-18, is from 22 to 24 tons

Thus, the above examples show that the patented method allows to solve the problem. Table 1 - the Impact of the fractional composition of the dry charge on the performance of the processing of lead-containing material

Table 2 - the Impact of the initial moisture content of the mixture on the performance of the processing of lead-containing material

Table 3 - the Impact of the quality of the carbon reducing agent on the performance of the processing of lead-containing material

k * o

Notes: - based on pure oxygen; - based on pure carbon, - including fuel for drying the mixture

Claims

CLAIM 1. A method of processing lead-containing materials, including the preparation of a mixture by thoroughly mixing moist sulfide and oxidized lead-containing materials with fluxes and pulverized carbonaceous material, in which the mass ratio of the sum of sulfide, elemental and pyrite sulfur to the total sulfur content in the charge is 0.08-0, 87, and a pyriform carbonaceous material with an activation energy of the carbon gasification reaction in the range of 56-209 kJ / mol is introduced as a reducing agent at the rate of 4-12 kg of pure carbon per 100 kg ferrous iron and 20-140 kg of pure carbon per 100 kg of sulfate sulfur in the charge, drying the resulting wet mixture to a residual moisture content of less than 1%, firing and melting the dry charge in suspension in an oxygen atmosphere to obtain a dispersed oxide melt and a mixture of dusts with firing gases -melting, reduction of a dispersed oxide melt during its filtration through a layer of heated particles of crushed carbon reducing agent with a particle size of 2-50 mm to produce metallic lead, zinc-containing oxide melt and gas s, miscible with dusts and gases of firing-melting of a dry charge, separation of the resulting mixture of dusts and reaction gases with the return of dusts to firing-melting of a dry charge, characterized in that the dry charge is subjected to grinding and classification, and a separated fraction is fed to the firing step dry mixture, at least 90% of the mass of which are particles with sizes of 0.01-0.10 mm 2. The method of processing lead-containing materials according to claim 1, characterized in that the free moisture content in the charge at the stage of its preparation is 8-16%. 3. A method of processing lead-containing materials according to claim 1, characterized in that coal is used as a crushed carbon reducing agent with a total carbon content of about 49 to about 80% and a volatile content of about 11 to about 27% in the dry mass.