Lead-zinc combined smelting method based on lead-zinc integrated reduction furnace

Abstract

The invention discloses a lead-zinc combined smelting method based on a lead-zinc integrated reduction furnace, and belongs to the technical field of lead-zinc smelting. Raw materials including lead and zinc materials are added into an oxygen-enriched molten pool smelting furnace for oxygen-enriched smelting; flue gas generated by oxygen-enriched smelting enters an acid making system, lead-zinc slag generated by oxygen-enriched smelting is discharged into a lead-zinc integrated reduction furnace for reduction smelting, and low-zinc slag generated by the lead-zinc integrated reduction furnace is further smelted by a fuming furnace to recover zinc; according to the method, pyrogenic process lead-zinc smelting equipment is improved, a new lead-zinc combined smelting technical thought of oxidation smelting desulfurization, lead-zinc integrated reduction and fuming smelting purification is designed based on the improvement of the equipment, short-process and continuous smelting of lead-zinc materials can be achieved, and lead ingots and zinc ingots are directly obtained; the technical problems of low smelting strength, long technological process, high energy consumption, poor equipment adaptability, high lead and zinc recovery cost and the like in existing pyrogenic process lead and zinc smelting are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a lead-zinc smelting method, in particular to a method for realizing joint continuous smelting and efficient short-process recovery of lead-zinc resources based on improvement of lead-zinc pyrometallurgical equipment, and belongs to the technical field of lead-zinc smelting. BACKGROUND

[0002] The main lead-zinc joint smelting process in the prior art includes sintering-closed blast furnace smelting process and three-continuous-furnace process of oxidation smelting-reduction smelting-fuming smelting. The sintering-closed blast furnace smelting process can directly obtain metal lead-zinc products, but has problems of low efficiency, large amount of flue gas, and the need to use coke, etc. At present, only a small number of enterprises in China still use this process for lead-zinc production. The three-continuous-furnace smelting process has advantages of high smelting efficiency, strong adaptability to raw materials, and small amount of flue gas, but zinc can only be recovered in the form of low-grade secondary zinc oxide, which still needs to be extracted through a complex wet process.

[0003] At present, there are a large number of technologies related to lead-zinc joint smelting. For example, Chinese patent (CN106086464A) discloses a lead-zinc smelting equipment, which needs to use coke bed filling in the reduction area, Chinese patent (CN 203559108U) discloses a lead-zinc joint smelting system, but does not introduce the specific form and structure of the equipment used in the system, and the reduction and slag-gold separation processes are not integrated; Chinese patent (CN 201729861U) discloses a lead-zinc integrated smelting furnace, but the equipment does not consider electrode strengthening, and the device is more suitable for smelting of lead concentrates with low zinc content, and is not suitable for lead-zinc mixed ore with high zinc grade; Chinese patent (CN 103205581A) discloses a bottom-blown smelting electric heating reduction lead-zinc smelting equipment, which uses a bottom-blown smelting furnace and an electric furnace in combination, but does not consider the difference in the properties of lead and zinc for segmented recovery, Chinese patent (CN101200777A) discloses a method and equipment for continuous smelting of lead sulfide concentrate, which divides the furnace body into three regions, but it is only suitable for processing single lead concentrate.

[0004] In summary, the existing related lead-zinc joint smelting technologies are difficult to adapt to the actual lead-zinc joint smelting process. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a lead-zinc combined smelting method, which is characterized in that the fire method lead-zinc smelting equipment is improved, and a new lead-zinc combined smelting technical idea of "oxidation smelting desulfurization + lead-zinc integrated reduction + fuming smelting purification" is designed based on the improvement of the equipment, so that the short process and continuous smelting of lead-zinc materials can be realized, and lead ingots and zinc ingots can be directly obtained, thereby solving the technical problems of low smelting intensity, long process flow, high energy consumption, poor equipment adaptability and high lead-zinc recovery cost existing in the prior art fire method lead-zinc smelting process.

[0006] In order to achieve the above technical purpose, the present application provides a lead-zinc combined smelting method, which comprises the following steps: adding raw materials including lead-zinc materials into a rich-oxygen smelting furnace for rich-oxygen smelting; the flue gas generated by the rich-oxygen smelting is sent to an acid-making system, and the lead-zinc smelting slag generated by the rich-oxygen smelting is discharged into a lead-zinc integrated reduction furnace for reduction smelting.

[0007] One end of the lead-zinc integrated reduction furnace is provided with a slag inlet, and the other end is provided with a slag outlet, and the lead-zinc integrated reduction furnace is divided into a heat preservation zone, a weak reduction zone, a strong reduction zone and a slag depletion zone from the slag inlet end to the slag outlet end; heating electrodes are arranged in each of the heat preservation zone, the strong reduction zone and the slag depletion zone; a lead discharge port is arranged at the bottom of the heat preservation zone; a water jacket partition wall is arranged between the heat preservation zone and the weak reduction zone, and a molten slag passage is left at the lower part of the water jacket partition wall; reduction agent lances are arranged on the side walls of the weak reduction zone and the strong reduction zone; a feeding port is arranged at the top of the strong reduction zone; a bottom slag port is arranged on one side wall of the slag depletion zone, and a zinc vapor outlet is arranged at the port.

[0008] The reduction smelting process of the lead-zinc smelting slag is as follows: the lead-zinc smelting slag enters the heat preservation zone from the slag inlet of the lead-zinc integrated reduction furnace after preheating, and then flows into the weak reduction zone to react with the reduction agent sprayed by the reduction agent lances to generate liquid lead and high-zinc smelting slag, and the liquid lead is enriched at the bottom; the high-zinc smelting slag flows into the strong reduction zone to react with the reduction agent sprayed by the reduction agent lances to generate primary zinc vapor and medium-zinc smelting slag; the medium-zinc smelting slag flows into the slag depletion zone to further generate secondary zinc vapor and low-zinc smelting slag; the secondary zinc vapor and the primary zinc vapor are mixed and discharged from the zinc vapor outlet to enter a condensing system together after condensation to form a lead-zinc mixed liquid; the lead-zinc mixed liquid is separated by melting and cast into ingots to obtain zinc ingot products; and the low-zinc smelting slag flows into a fuming furnace to be reduced and volatilized, the flue gas generated by the fuming furnace is collected to obtain secondary zinc oxide which is returned to the lead-zinc integrated reduction furnace, and the smelting tail slag generated by the fuming furnace is water quenched to obtain a vitrification product.

[0009] The key of the application lies in improving the device of lead-zinc reduction smelting, developing a lead-zinc integrated reduction furnace, and designing a new lead-zinc combined smelting method based on the lead-zinc integrated reduction furnace device. The method can realize short process, continuous smelting of lead-zinc materials and directly obtain lead ingots and zinc ingots, and solves the technical problems of low smelting intensity, long process flow, high energy consumption, poor equipment adaptability and high lead-zinc recovery cost existing in the existing fire lead-zinc smelting. The lead-zinc integrated reduction furnace designed by the application is provided with a slag inlet at one end and a slag outlet at the other end, and is divided into a heat preservation zone, a weak reduction zone, a strong reduction zone and a slag depletion zone in sequence from the slag inlet to the slag outlet. The heat preservation zone is provided with a lead outlet, and a water jacket partition wall is arranged between the heat preservation zone and the weak reduction zone to form a relatively independent space, and a lead-zinc molten slag channel is left at the lower part of the water jacket partition wall. The setting of the heat preservation zone is very beneficial to improving the reduction smelting effect of lead-zinc molten slag. The heat preservation zone adopts electrode heating, which can preheat the lead-zinc molten slag on one hand, ensure the temperature of the lead-zinc molten slag when entering the weak reduction zone, and improve the subsequent reduction smelting effect, and on the other hand, ensure the fluidity of the lead-zinc molten slag, and avoid the supercooling crystallization of the lead-zinc molten slag in the conveying process. The main feature of the design of the weak reduction zone is that no heating electrode is designed, and a reducing agent lance is arranged on the side wall. The main reason is that the reduction process of lead oxide is an exothermic reaction, therefore, the weak reduction zone can not use electrode heating, and only the reducing agent is sprayed. The heat consumed in the reduction process can be supplemented by the reduction exothermic of lead oxide, and the reducing agent is directly sprayed into the lead-zinc molten slag layer through the reducing agent lance on the side wall, which can stir the molten pool and strengthen the reaction efficiency of the reducing agent and the lead-zinc molten slag. Based on the characteristics that lead oxide is easier to reduce than zinc oxide, the weak reduction zone can preferentially reduce lead oxide to generate liquid lead which is enriched at the bottom by gravity and discharged from the lead outlet to obtain crude lead product, and the remaining zinc slag enters the strong reduction zone. The lead outlet is arranged in the heat preservation zone instead of the weak reduction zone in order to avoid the complete separation of lead liquid and slag in the weak reduction zone caused by the stirring of the molten pool by the reducing agent lance. The key design of the strong reduction zone is to design electrode heating and arrange a reducing agent lance on the side wall, which completely changes the existing zinc reduction smelting method. The reducing agent directly enters the zinc molten slag layer through the spraying mode, improves the reaction efficiency of the reducing agent and the zinc molten slag, and the reduction reaction is more complete. At the same time, based on the fact that the reducing agent is light and easy to float on the molten pool, the spraying mode can effectively stir the molten pool, so that the reducing agent floating on the zinc molten slag layer reacts with the zinc molten slag, greatly improving the reaction efficiency. The slag depletion zone maintains the smelting temperature by designing multiple electrodes, and realizes the further reduction of zinc by using the residual reducing agent in the low-zinc slag to generate secondary zinc-containing flue gas, and mixes the primary zinc-containing flue gas generated in the strong reduction stage into the condensing system for condensation, segregation and separation to obtain zinc ingots. The reduced low-zinc tailings flow into the fuming furnace for further refining, the zinc in the reduced low-zinc tailings is reduced into flue gas, and is oxidized into secondary zinc oxide in the subsequent flue gas treatment system. The secondary zinc oxide is returned to the lead-zinc integrated reduction furnace through the lance.

[0010] As a preferred scheme, the element ratio of Fe, Ca and Si in the raw material satisfies Fe / Si = 0.2-2.0 and Ca / Si = 0.2-2.0. Further preferably, Fe / Si = 1.0-2.0 and Ca / Si = 0.5-1.0. In addition to the lead-zinc material, the raw material of the present application also contains a slagging agent. The slagging agent is mainly used to adjust the element ratio of Fe, Ca and Si in the raw material to a suitable range, so that the oxidation slag with low melting point and good fluidity can be obtained. The slagging agent can be quartzite, limestone, pyrite and the like, which are used in appropriate proportions. According to the needs, the addition amount of quartzite and limestone can be arbitrarily controlled within the range of 0-20% of the lead-zinc material; pyrite can not only be used for slagging, but also can provide heat, and the addition amount of pyrite can be arbitrarily controlled within the range of 0-20% of the lead-zinc material; when the effective sulfur content in the lead-zinc mixture is low, an appropriate amount of fuel is added to supplement the heat required for smelting, and the addition amount of fuel is 0-20% of the lead-zinc material.

[0011] As a preferred scheme, the oxygen-enriched smelting furnace includes an oxygen-enriched bottom-blowing smelting furnace, an oxygen-enriched side-blowing smelting furnace or an oxygen-enriched bottom-blowing smelting furnace. The most preferred oxygen-enriched smelting furnace is an oxygen-enriched side-blowing smelting furnace.

[0012] As a preferred scheme, the conditions of the oxygen-enriched smelting are that the temperature is 900-1400°C, and the oxygen volume concentration of the oxygen-enriched air used is 30-80%. The temperature of the oxidation smelting is further preferably controlled within the range of 1000-1200°C, so as to ensure that the lead-zinc material is completely melted and has good fluidity. The oxygen-enriched air is further preferably oxygen with a volume concentration of 60-80%, which can reduce the amount of flue gas and increase the concentration of SO2 in the flue gas, which is beneficial to the subsequent acid production process. During the smelting process, the lead-zinc sulfide is oxidized to generate ZnO, PbO and SO2, SO2 leaves the furnace with the flue gas, and ZnO and PbO form molten lead-zinc slag with SiO2, Fe2O3 and CaO and the like.

[0013] As a preferred scheme, the holding zone is provided with a set of three-phase electrodes, and the heating temperature of the three-phase electrodes is 1200-1400°C. The holding zone is only heated by electrodes to ensure that the temperature of the lead-zinc slag is 1200-1400°C, and the purpose is to prevent the lead-zinc slag from supercooling and crystallizing, to ensure that the lead-zinc slag has good fluidity, and to improve the efficiency of the subsequent reduction smelting.

[0014] As a preferred scheme, at least one set of reducing agent injection lances is arranged on the side wall of the weak reduction zone, and the distance between adjacent reducing agent injection lances is 400-2000 mm. As a preferred scheme, the weak reduction zone is supplied with reducing agent through the reducing agent injection lances, and the amount of reducing agent is 0-20% of the mass of lead-zinc smelting slag, so as to control the CO / CO2 volume ratio to be 0-1.0. As a preferred scheme, the reducing agent is pulverized coal. As a preferred scheme, compressed nitrogen or air is used as the carrier gas of the pulverized coal during injection, and the ratio of carrier gas to pulverized coal is 1-15 Nm 3 / kg. The weak reduction zone is supplied with reducing agent through the reducing agent injection lances, and the reducing agent includes reducing gases such as pulverized coal, natural gas, crushed coke, and solid reducing agents with small particle sizes, and is further preferably pulverized coal. The carrier can be compressed air, compressed nitrogen, compressed oxygen-enriched air, etc. In order to ensure that the weak reduction zone is in a reducing atmosphere and avoid oxidation of the electrode, compressed nitrogen is preferably used as the carrier gas, and the air-coal ratio is 0.1-15 Nm 3 / kg, and is further preferably 3-12 Nm 3 / kg. The amount of reducing agent is further preferably 3-10% of the mass of lead-zinc smelting slag, so as to control the CO / CO2 volume ratio to be 0-0.5. The smelting temperature is controlled to be in the range of 1000-1400°C, and is further preferably 1100-1300°C. Under the preferred conditions, the lead oxide can be preferentially reduced. The distance between the reducing agent injection lances is further preferably 800-1200 mm. The purpose of arranging the reducing agent injection lances is to inject reducing agent and at the same time stir the molten pool by injecting compressed gas, to strengthen the mass transfer in the molten pool and promote the progress of the reduction reaction.

[0015] As a preferred embodiment, a DC electrode is installed within the strong reduction zone. The DC electrode is encased in an air jacket and sealed with a nitrogen gas curtain. The DC electrode is heated to a temperature of 1300-1600°C, and a reducing agent is sprayed through a reducing agent spray gun to maintain a CO / CO2 volume ratio of 1.0-3.0 in the flue gas. The strong reduction zone utilizes DC electrode heating, with reducing agent sprayed on both sides of the furnace. Zinc slag undergoes intense reduction within this strong reduction zone, volatilizing to form primary zinc vapor. In addition to maintaining the fluidity of the zinc slag, DC electrode heating also serves to increase the smelting temperature, promote the reduction of zinc oxides within the slag, increase the concentration of zinc vapor, and thereby enhance the capture efficiency of the condensation system. The smelting temperature in the strong reduction zone is more preferably 1300-1500°C. Heating can be performed using either single electrode heating or a mixed heating method. In this mixed heating method, a certain amount of compressed air or oxygen-enriched air is introduced into the spray gun, and the combustion of the reducing agent provides heat to the furnace interior. Single electrode heating is a further preferred heating method. The injection amount of the reducing agent is 20~80% of the mass of the high-zinc slag. The purpose is to ensure that the reducing atmosphere in the reduction furnace meets CO / CO2=1.0~3.0, and further preferably CO / CO2=1.5~2.0, so as to ensure sufficient reduction of zinc oxide.

[0016] As a preferred solution, 2 to 7 pairs of DC electrodes are provided in the strong reduction zone, and the electrode spacing between each pair of DC electrodes is 1 to 6 m.

[0017] As a preferred solution, a group of reducing agent spray guns are respectively provided on the side walls of the strong reduction zone, and the spacing between adjacent reducing agent spray guns is 400-2000 mm.

[0018] The present invention utilizes an electrode heating method in combination with a spray gun stirring smelting method, which can solve the problem of low smelting efficiency caused by the static molten pool in the existing electric furnace smelting process. At the same time, through the reasonable layout of the reducing agent spray gun, the disturbance and oxidation of the electrodes by the compressed gas are avoided, thereby achieving efficient smelting of lead and zinc materials.

[0019] As a preferred solution, the reducing agent is coal powder. As a preferred solution, the coal powder is injected with compressed nitrogen or air as carrier gas, and the ratio of carrier gas to coal powder is 0.1~15Nm 3 / kg.

[0020] The reducing agent includes reducing gases such as pulverized coal, natural gas, crushed coke, or solid reducing agents with smaller particle sizes. The most preferred reducing agent is pulverized coal. During the process of spraying the reducing agent with the reducing agent spray gun, compressed air, compressed nitrogen, compressed oxygen-enriched air, etc. are used as carrier gases to ensure that the strong reduction zone is in a strong reducing atmosphere and to avoid oxidation of the electrode. Compressed nitrogen is preferred, and the air-to-coal ratio is 0.1~15Nm 3 / kg, the higher the wind coal ratio, the more intense the molten pool agitation, but too high wind coal ratio will lead to increased production cost, therefore the wind coal ratio is further preferably 0.6~5Nm 3 / kg.

[0021] As a preferred scheme, the slag-lean zone is provided with at least one set of direct current electrodes, and the heating temperature of the direct current electrodes is 1200~1500℃. The slag-lean zone uses the residual reducing agent of the electrode-enhanced reduction zone for reduction, without additional reducing agent. The secondary zinc vapor generated in the slag-lean zone and the primary zinc vapor generated in the strong reduction zone enter the condensing system (the condensing system is a lead rain condensing system) together, are cooled to about 500℃ by heat exchange with low-temperature lead liquid, and are separated by fractional crystallization to obtain liquid zinc, which is cast into zinc ingots to obtain zinc ingot products, and the remaining flue gas is purified to obtain clean gas. The smelting final slag is water quenched to obtain a harmless vitrification product.

[0022] As a preferred scheme, the area of the heat preservation zone, the weak reduction zone, the strong reduction zone and the slag-lean zone accounts for 5~40%, 5~20%, 20~70% and 15~65% of the area of the bottom of the inner cavity of the lead-zinc integrated reduction furnace, respectively. The area of the heat preservation zone is the smallest, which is only used for the heat preservation of lead-zinc smelting slag, equivalent to an emergency device to avoid the supercooling crystallization of oxidized slag. If the area of the heat preservation zone is too large, the heat preservation energy consumption will increase; if the area of the heat preservation zone is too small, the heating efficiency will be low. Therefore, the preferred area of the heat preservation zone accounts for 5~20%. The weak reduction zone is mainly used for the reduction of lead oxide, and a small area ratio will lead to incomplete reduction of lead, which is easy to volatilize into zinc ingots, and a large area ratio will affect the subsequent zinc reduction process. Therefore, the preferred area of the weak reduction zone accounts for 5~15%. The strong reduction zone is mainly used for the volatilization of zinc, and a large area ratio of the strong reduction zone will lead to a long strong reduction reaction time, which may cause the reduction of iron in the slag and affect the continuous operation of the process; a small area ratio of the strong reduction zone will lead to a high zinc content in the smelting slag entering the slag-lean zone, which is not conducive to the direct metallization recovery of zinc. Therefore, the preferred area of the strong reduction zone accounts for 40~70%. The volatilization efficiency of zinc is generally low, especially in the lean zone with low reaction temperature and weak reducing atmosphere. Therefore, the slag-lean zone needs a certain reaction area. The preferred area accounts for 20~50%.

[0023] The electrodes in the heat preservation zone of the lead-zinc integrated reduction furnace are indirectly heated, that is, when the temperature of the lead-zinc smelting slag entering the furnace decreases to a certain temperature, the heat supplement is started, and the heat supplement is usually in a closed state.

[0024] The smelting temperature of the smoke furnace is 1200-1400 DEG C, and the reducing agent addition amount is 5-20 %, so that the CO / CO2 volume ratio is controlled to be 0.1-1.0, the residual zinc in the reduction tailings is reduced into the flue gas, and the zinc is oxidized into zinc suboxide in the subsequent flue gas treatment system, and the zinc suboxide is returned into the lead-zinc integrated reduction furnace through a spray gun.

[0025] The water jacket partition wall material in the lead-zinc integrated reduction furnace can be carbon steel water jacket, stainless steel water jacket, copper water jacket, composite material water jacket, etc., and the copper water jacket is preferred.

[0026] Compared with the prior art, the technical scheme of the present application has the following beneficial technical effects:

[0027] 1. The present application breaks through the bottleneck of the existing lead-zinc smelting technology, combines the advantages of the closed blast furnace and the three-in-one furnace process, and adopts the process of "oxidation smelting desulfurization + lead-zinc integrated reduction + smoke smelting purification" to realize efficient separation and metallization recovery of lead and zinc, and directly obtain lead ingots and zinc ingots products, which greatly shortens the existing process flow.

[0028] 2. The present application designs a lead-zinc integrated reduction furnace with a multi-region structure, realizes regional smelting of lead and zinc, and reduces the heat loss caused by the gasification of lead.

[0029] 3. The present application innovatively proposes a smelting method of electrode heating combined with spray gun stirring, solves the problem of low smelting efficiency caused by the static molten pool in the electric furnace smelting process, and realizes efficient smelting of lead and zinc through reasonable spray gun layout.

[0030] 4. The present application realizes the sealing of the furnace body inlet, the feeding port and the electrode port by using water jacket isolation, air curtain sealing and other methods, greatly avoids the infiltration of external air, and creates necessary conditions for the condensation and recovery of zinc vapor.

[0031] 5. The present application uses multiple electrodes to supply heat, effectively maintains the temperature of the molten pool, uses spray guns to spray reducing agents and stir, effectively strengthens the smelting efficiency of the molten pool, uses multiple sealing methods to avoid air entering, and uses regional smelting to realize the strengthening of zinc reduction and the avoidance of lead gasification. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The present application is a lead-zinc combined smelting process flow diagram.

[0033] Figure 2Structure schematic diagram of the lead-zinc integrated reduction furnace of the present application.

[0034] Figure 3 Sectional schematic diagram of the strong reduction zone of the lead-zinc integrated reduction furnace of the present application.

[0035] Figure 4 Sectional schematic diagram of the water jacket partition wall of the lead-zinc integrated reduction furnace of the present application.

[0036] Figure 5 Pb-Zn-Fe-CO-CO2 reduction phase diagram.

[0037] In the figure, 1 is a slag inlet, 2 is a three-phase electrode, 3 is a water jacket partition wall, 4 is a direct current electrode, 5 is a feeding inlet, 6 is a reducing agent spray gun, 7 is a slag outlet, 8 is a bottom slag outlet, 9 is a heat preservation zone, 10 is a strong reduction zone, 11 is a slag depletion zone, 12 is a zinc vapor outlet, 13 is a lead outlet, and 14 is a weak reduction zone. DETAILED DESCRIPTION

[0038] The following specific examples are intended to further illustrate the content of the present application in conjunction with the accompanying drawings of the specification, but the scope of protection of the claims of the present application is not limited by the following examples.

[0039] The specific structure of the lead-zinc integrated reduction furnace of the present application is shown in Figures 2-4. The lead-zinc integrated reduction furnace is provided with a slag inlet at one end and a slag discharge port at the other end. The furnace body of the lead-zinc integrated reduction furnace is divided into four areas, namely, a heat preservation zone, a weak reduction zone, a strong reduction zone and a slag depletion zone, from one end of the slag inlet to one end of the slag discharge port. The areas of the heat preservation zone, the weak reduction zone, the strong reduction zone and the slag depletion zone account for 10%, 10%, 50% and 30% of the area of ​​the bottom of the inner cavity of the zinc deep reduction furnace respectively. A set of three-phase electrodes is provided in the heat preservation zone, which is mainly used to preheat the lead-zinc smelting slag. The heat preservation zone and the weak reduction zone are separated by a copper water jacket to form a relatively independent space, and a lead-zinc slag channel is left at the bottom of the copper water jacket. A lead outlet is provided at the bottom of the heat preservation zone. A set of reducing agent spray guns are respectively provided on the side walls of the weak reduction zone, and the spacing between adjacent reducing agent spray guns is 1000 mm. The number of reducing agent spray guns on the two side walls of the weak reduction zone is determined according to the length of the weak reduction zone. A set of reducing agent spray guns is installed on opposite side walls of the intensive reduction zone, with adjacent spray guns spaced 1000 mm apart. The specific number of spray guns is determined by the length of the intensive reduction zone. The intensive reduction zone houses three pairs of DC electrodes made of graphite. These electrodes are enclosed in air jackets and sealed with a nitrogen gas curtain to prevent air infiltration through the access openings, ensuring the furnace is airtight. Each pair of electrodes is spaced 3 meters apart. The reducing agent spray guns on the intensive reduction zone side walls are positioned between the electrode pairs to prevent the compressed gas injected by the spray guns from disturbing the electrodes and, when the carrier is air, from oxidizing the graphite electrodes. A charging port is located above the top of the intensive reduction zone, between each pair of electrodes. Due to the limited volume delivered by the reducing agent spray guns during actual operation, additional charging ports are required to accommodate large-scale additions of high-zinc materials and reducing agents. These ports utilize a dual-feed bell or spiral sealed feeding method to ensure the airtightness of the reduction furnace. A pair of DC electrodes made of graphite are installed in the slag depletion zone, with a spacing of 3m between the electrodes. A bottom slag outlet is provided on one side wall of the slag depletion zone, and a slag discharge outlet and zinc-containing fume outlet are provided at the end.

[0040] The combined smelting process of lead-zinc materials of the present invention is shown in Figure 1 :like Figure 1 The lead-zinc mixture shown is dried and mixed with flux (quartz, limestone, pyrite, etc.) and reducing agent (coal powder, etc.), and then enters an oxygen-enriched side-blown oxidation furnace for oxidation smelting and desulfurization. The conditions for oxygen-enriched smelting are: temperature of 900°C to 1400°C, oxygen concentration of 30% to 80% by volume in the oxygen-enriched air, and the mixture ensures that the slag composition has a Fe / Si ratio of 1.0 to 2.0 and a Ca / Si ratio of 0.5 to 1.0, thus obtaining a lead-zinc slag with good fluidity. The lead-zinc slag flows into the lead-zinc integrated reduction furnace through a chute, is preheated in the holding zone, and maintained at a temperature of 1200 to 1400°C, and then flows into the weak reduction zone; 0 to 20% pulverized coal is sprayed into the weak reduction zone for reduction, and the air-to-coal ratio is 0.1 to 15 Nm 3 / kg, smelting temperature is 1100~1300℃, lead liquid and high zinc slag are obtained, lead liquid is discharged through lead outlet to obtain lead ingot, high zinc slag flows into electric heating strengthening reduction area; 30~80% pulverized coal is sprayed into the strong reduction area for reduction, to ensure that CO / CO2=1.5~2.0 in the flue gas, and the air-coal ratio is 0.6~5 Nm 3 / kg, smelting temperature is 1300~1500℃, the obtained primary zinc vapor and the middle zinc slag, the middle zinc slag flows into the slag depletion area; the slag depletion area maintains the smelting temperature at 1200~1400℃ through electrodes, the zinc in the middle zinc slag is further reduced to generate secondary zinc vapor, which is mixed with the primary zinc vapor generated in the strong reduction stage to enter the lead rain condensing system, is condensed and captured, and is separated through crystallization to obtain zinc ingot, and the reduction tailings flow into the fuming furnace for further refining; the smelting temperature of the fuming furnace is 1200~1400℃, the reduction agent addition amount is 5~20%, and the zinc in the reduction tailings is reduced into the flue gas and is oxidized to generate secondary zinc oxide in the subsequent flue gas treatment system, which is returned to the lead-zinc integrated reduction furnace through a spray gun.

[0041] Example 1

[0042] A certain lead-zinc mixed concentrate contains Zn 25%, Pb 22%, and S 18%, and is subjected to oxidative smelting under the conditions of Fe / Si=1.2 and Ca / Si=0.7, the smelting conditions are: the temperature is 1100℃, the oxygen volume concentration of the oxygen-enriched air used is 50%, and a lead-zinc slag with good fluidity is obtained. 7% pulverized coal is sprayed into the weak reduction area for reduction, compressed nitrogen is used as the carrier, and the air-coal ratio is 2 Nm 3 / kg, the smelting temperature is 1200℃, the lead is smoothly discharged through the lead outlet in the holding area, lead ingot is obtained, and the lead recovery rate reaches 98%. 35% pulverized coal is sprayed into the electric heating strong reduction area for reduction, compressed nitrogen is used as the carrier, and the air-coal ratio is 2 Nm 3 / kg, the smelting temperature is 1350℃, zinc vapor is obtained, after condensation and capture, zinc ingot is obtained, the zinc recovery rate reaches 90.2%, and the slag contains 6.72% zinc. The low-zinc smelting slag flows into the slag depletion area for smelting, and a smelting final slag containing 0.32% zinc is obtained at 1300℃.

[0043] Example 2

[0044] A certain lead-zinc mixed concentrate contains Zn 35%, Pb 20%, and S 19%, and is subjected to oxidative smelting under the conditions of Fe / Si=1.3 and Ca / Si=0.6, the smelting conditions are: the temperature is 1150℃, the oxygen volume concentration of the oxygen-enriched air used is 48%, and a lead-zinc slag with good fluidity is obtained. 6% pulverized coal is sprayed into the weak reduction area for reduction, compressed nitrogen is used as the carrier, and the air-coal ratio is 3 Nm 3 / kg, smelting temperature is 1150 ℃, lead is successfully discharged at the lead discharge port in the holding zone, lead ingot is obtained, and the lead recovery rate reaches 99.1%. The electric heating strong reduction zone sprays 42% pulverized coal for reduction, compressed nitrogen is used as the carrier, the air-coal ratio is 3 Nm 3 / kg, smelting temperature is 1380 ℃, zinc vapor is obtained, after the zinc vapor is captured by condensation, zinc ingot is obtained, the direct zinc recovery rate reaches 92.6%, and the slag contains 5.42% zinc. The low-zinc smelting slag flows into the slag depletion zone for smelting, and the final smelting slag containing 0.41% zinc is obtained at 1330 ℃.

[0045] Example 3

[0046] A certain lead-zinc mixed concentrate contains 33% Zn, 18% Pb and 15% S, and is subjected to oxidative smelting under the conditions of Fe / Si = 1.0 and Ca / Si = 0.8. The conditions for oxygen-enriched smelting are as follows: the temperature is 1200 ℃, the oxygen-enriched air used contains 40% oxygen by volume, and a lead-zinc smelting slag with good fluidity is obtained. In the weak reduction zone, 7% pulverized coal is sprayed for reduction, compressed air is used as the carrier, and the air-coal ratio is 2 Nm 3 / kg, smelting temperature is 1250 ℃, lead is successfully discharged at the lead discharge port in the holding zone, lead ingot is obtained, and the lead recovery rate reaches 98.9%. The electric heating strong reduction zone sprays 40% pulverized coal for reduction, compressed air is used as the carrier, and the air-coal ratio is 2 Nm 3 / kg, smelting temperature is 1380 ℃, zinc vapor is obtained, after the zinc vapor is captured by condensation, zinc ingot is obtained, the direct zinc recovery rate reaches 87.7%, and the slag contains 8.32% zinc. The low-zinc smelting slag flows into the slag depletion zone for smelting, and the final smelting slag containing 0.28% zinc is obtained at 1300 ℃.

[0047] Example 4

[0048] A certain lead-zinc mixed concentrate contains 40% Zn, 13% Pb and 16% S, and is subjected to oxidative smelting under the conditions of Fe / Si = 1.8 and Ca / Si = 0.6. The conditions for oxygen-enriched smelting are as follows: the temperature is 1000 ℃, the oxygen-enriched air used contains 60% oxygen by volume, and a lead-zinc smelting slag with good fluidity is obtained. In the weak reduction zone, 7% pulverized coal is sprayed for reduction, oxygen-enriched air is used as the carrier, and the air-coal ratio is 1.5 Nm 3 / kg, smelting temperature is 1300 ℃, lead is successfully discharged at the lead discharge port in the holding zone, lead ingot is obtained, and the lead recovery rate reaches 99.2%. The electric heating strong reduction zone sprays 38% pulverized coal for reduction, oxygen-enriched air is used as the carrier, and the air-coal ratio is 1.5 Nm 3 / kg, the smelting temperature is 1400 ℃, the zinc-containing flue gas is obtained, the zinc-containing flue gas is captured by condensation, the zinc ingot is obtained, the zinc recovery rate reaches 83.6%, and the slag contains 12.42% of zinc. The low-zinc smelting slag flows into the slag depletion area for smelting, and the smelting final slag containing 0.34% of zinc is obtained at 1300 ℃.

[0049] Comparative Example 1

[0050] Similar to Example 2, the difference is that the pulverized coal is not sprayed in the weak reduction zone, and the pulverized coal is directly put into from the feeding port. The lead liquid can be smoothly discharged from the lead discharge port of the holding zone, but the direct recovery rate of lead is only 91.4%; the direct recovery rate of zinc is slightly reduced to 83.3%, and the slag contains 10.35% of zinc. This may be due to the lack of pulverized coal spraying, poor reduction conditions, and incomplete reduction of lead in the weak reduction zone, but volatilization into the lead rain condensation system in the strong reduction zone. The volatilization of lead absorbs a large amount of heat, which reduces the temperature in the furnace, and further affects the reduction and volatilization of zinc.

[0051] Comparative Example 2

[0052] Similar to Example 2, the difference is that the pulverized coal is not sprayed in the strong reduction zone, and the pulverized coal is directly put into from the feeding port. The lead liquid can be smoothly discharged from the lead discharge port of the holding zone, the direct recovery rate of lead is 96.9%; but the direct recovery rate of zinc is reduced to 75.3%, and the slag contains 17.42% of zinc. This may be due to the lack of pulverized coal spraying, and the pulverized coal and molten slag cannot fully contact in the strong reduction zone, making it difficult for zinc inside the molten slag to be reduced, resulting in a decrease in zinc recovery rate.

[0053] Example 5

[0054] Similar to Example 2, the difference is that the air-coal ratio in the strong reduction zone is 4.0 Nm 3 / kg. The lead liquid can be smoothly discharged from the lead discharge port of the holding zone, the direct recovery rate of lead is 97.8%; due to the increase of stirring intensity, the direct recovery rate of zinc is slightly increased to 93.8%, and the slag contains 4.82% of zinc.

[0055] Example 6

[0056] Similar to Example 2, the difference is that the air-coal ratio in the strong reduction zone is 5.0 Nm 3 / kg. The lead liquid can be smoothly discharged from the lead discharge port of the holding zone, the direct recovery rate of lead is 98.4%; due to the increase of stirring intensity, the direct recovery rate of zinc is slightly increased to 94.1%, and the slag contains 4.22% of zinc.

[0057] Example 7

[0058] Similar to Example 2, the difference is that the air-coal ratio in the strong reduction zone is 6.0 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 98.9%; the direct recovery rate of zinc was 93.1%, and the zinc content of the slag was 5.12%, indicating that further increasing the air-coal ratio had little effect on the direct recovery rate of zinc.

[0059] Example 8

[0060] Similar to Example 3, except that the air-coal ratio in the strong reduction zone was 2.5 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 98.9%; the direct recovery rate of zinc was 93.1%, and the zinc content of the slag was 5.12%, indicating that further increasing the air-coal ratio had little effect on the direct recovery rate of zinc.

[0061] Example 9

[0062] Similar to Example 3, except that the air-coal ratio in the strong reduction zone was 3.0 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 99.3%; but the direct recovery rate of zinc was slightly reduced to 85.6% due to the weakening of the reducing atmosphere in the furnace as the amount of air injection increased, and the zinc content of the slag was 8.24%.

[0063] Example 10

[0064] Similar to Example 3, except that the air-coal ratio in the strong reduction zone was 4.0 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 97.6%; but the direct recovery rate of zinc was slightly reduced to 82.1% due to the weakening of the reducing atmosphere in the furnace as the amount of air injection increased, and the zinc content of the slag was 10.72%.

[0065] Example 11

[0066] Similar to Example 4, except that the air-coal ratio in the strong reduction zone was 2.0 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 98.7%; the direct recovery rate of zinc was increased to 88.4% due to the increased stirring intensity during the reduction process, and the zinc content of the slag was 9.73%.

[0067] Example 12

[0068] Similar to Example 4, except that the air-coal ratio in the strong reduction zone was 2.5 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 99.3%; the direct recovery rate of zinc was little affected, being 84.7%, and the zinc content of the slag was 11.32%.

[0069] Example 13

[0070] Similar to Example 4, except that the air-to-coal ratio in the strong reduction zone was 3.0 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 97.9%; however, the direct recovery rate of zinc was reduced to 81.2% and the slag contained 14.15% zinc because the amount of oxygen-enriched air injected was increased and the reducing atmosphere in the furnace was weakened.

[0071] Example 14

[0072] Similar to Example 4, except that the air-to-coal ratio in the strong reduction zone was 0.4 Nm 3 / kg. The lead liquid was smoothly discharged from the lead discharge port of the holding zone, and the direct recovery rate of lead was 95.8%; however, the direct recovery rate of zinc was reduced to 80.3% and the slag contained 14.33% zinc because the air-to-coal ratio was too low and the stirring intensity was too weak.

Claims

1. A lead-zinc combined smelting method, characterized in that: Adding raw materials including lead and zinc materials into an oxygen-enriched molten pool smelting furnace for oxygen-enriched smelting; the flue gas generated by the oxygen-enriched smelting enters the acid-making system, and the lead-zinc slag generated by the oxygen-enriched smelting is discharged into a lead-zinc integrated reduction furnace for reduction smelting; The lead-zinc integrated reduction furnace is provided with a slag inlet at one end and a slag discharge port at the other end. The furnace is sequentially divided into a heat preservation zone, a weak reduction zone, a strong reduction zone and a slag depletion zone along the length from the slag inlet to the slag discharge port, and heating electrodes are provided in each of the heat preservation zone, the strong reduction zone and the slag depletion zone; a lead discharge port is provided at the bottom of the heat preservation zone, a water jacket partition wall is provided between the heat preservation zone and the weak reduction zone, and a slag channel is left at the lower part of the water jacket partition wall; reducing agent spray guns are provided on both side walls of the weak reduction zone and the strong reduction zone; a feeding port is provided on the top of the strong reduction zone; a bottom slag port is provided on one side wall of the slag depletion zone, and a zinc vapor outlet is provided at the port; The reduction smelting process of the lead-zinc slag is as follows: the lead-zinc slag enters the insulation zone from the slag inlet of the lead-zinc integrated reduction furnace for preheating, then flows into the weak reduction zone and undergoes a reduction reaction with the reducing agent sprayed by the reducing agent spray gun to generate liquid lead and high-zinc slag, the liquid lead settles and accumulates at the bottom, the high-zinc slag flows into the strong reduction zone and undergoes a reduction reaction with the reducing agent sprayed by the reducing agent spray gun to generate primary zinc vapor and medium-zinc slag, the medium-zinc slag flows into the slag depletion zone and undergoes further reduction to generate secondary zinc vapor and low-zinc slag, the secondary zinc vapor and the primary zinc vapor are mixed and discharged from the zinc vapor outlet, and both enter the condensation system for condensation to form a lead-zinc mixed liquid, which is separated from the lead-zinc mixed liquid by smelting and casting to obtain a zinc ingot product; the low-zinc slag flows into the fuming furnace for reduction and volatilization, the flue gas generated by the fuming furnace is subjected to dust collection to obtain secondary zinc oxide, which is returned to the lead-zinc integrated reduction furnace, and the smelting tailings generated by the fuming furnace are water quenched to obtain a vitrified product.

2. A lead-zinc combined smelting method according to claim 1, characterized in that: The element ratios of Fe, Ca and Si in the raw materials satisfy Fe / Si=0.2~2.0 and Ca / Si=0.2~2.

0.

3. A lead-zinc combined smelting method according to claim 1, characterized in that: The oxygen-enriched molten pool smelting furnace includes an oxygen-enriched bottom-blowing molten pool smelting furnace, an oxygen-enriched side-blowing molten pool smelting furnace or an oxygen-enriched bottom-blowing molten pool smelting furnace.

4. A lead-zinc combined smelting method according to claim 1 or 3, characterized in that: The conditions for the oxygen-enriched smelting are: a temperature of 900° C. to 1400° C., and an oxygen volume concentration of 30% to 80% in the oxygen-enriched air.

5. A lead-zinc combined smelting method according to claim 1, characterized in that: The insulation zone is provided with a set of three-phase electrodes, and the heating temperature of the three-phase electrodes is 1200-1400°C.

6. A lead-zinc combined smelting method according to claim 1, characterized in that: At least one group of reducing agent spray guns is provided on the side wall of the weak reduction zone, and the spacing between adjacent reducing agent spray guns is 400-2000 mm; The weak reduction zone is sprayed with a reducing agent through a reducing agent spray gun, and the spraying amount of the reducing agent is 0-20% of the mass of the lead-zinc slag to control the CO / CO2 volume ratio to be 0-1.0; The reducing agent is pulverized coal; The pulverized coal is injected using compressed nitrogen or air as a carrier gas, with a ratio of carrier gas to pulverized coal of 0.1 to 15 Nm 3 / kg.

7. A lead-zinc combined smelting method according to claim 1, characterized in that: A DC electrode is provided in the strong reduction zone, which is wrapped with an air jacket and sealed with a nitrogen air curtain. The DC electrode is heated to a temperature of 1300-1600°C, and a reducing agent is sprayed through a reducing agent spray gun to maintain a CO / CO2 volume ratio in the flue gas of 1.0-3.

0.

8. A lead-zinc combined smelting method according to claim 1 or 7, characterized in that: The strong reduction zone is provided with 2 to 7 pairs of DC electrodes, and the electrode spacing between each pair of DC electrodes is 1 to 6 m; At least one group of reducing agent spray guns is provided on each side wall of the strong reduction zone, and the spacing between adjacent reducing agent spray guns is 400-2000 mm.

9. A lead-zinc combined smelting method according to claim 7, characterized in that: The reducing agent is pulverized coal; The pulverized coal is injected using compressed nitrogen or air as a carrier gas, with a ratio of carrier gas to pulverized coal of 0.1 to 15 Nm 3 / kg.

10. A lead-zinc combined smelting method according to claim 1, characterized in that: The slag depletion zone is provided with at least one set of DC electrodes, and the heating temperature of the DC electrodes is 1200-1500°C.

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