Method for short-process recovery of zinc smelting slag

Abstract

The invention discloses a zinc smelting slag short-process recovery method which comprises the following steps: 1) mixing first zinc smelting slag and second zinc smelting slag, drying, and granulating; (2) the granulated zinc smelting slag is added into a smelting furnace to be smelted, and smoke and high-zinc slag are obtained; and 3) adding the high-zinc slag into a fuming furnace, and performing fuming blowing in a reducing atmosphere to obtain blowing slag and zinc-containing flue gas. According to the method, the first zinc smelting slag and the second zinc smelting slag are cooperatively treated, chemical reaction heat of combustible sulfur in the second zinc smelting slag is fully utilized to replace part of fuel heat release, and the zinc smelting slag recovery energy consumption is reduced to 250-300 kg / t. Based on the difference of volatilization characteristics of lead and zinc oxides, the content of Pb in the smoke dust is enriched to 40% or above in the smelting stage, the smoke dust is directly fed into a lead smelting system to be comprehensively recycled, the material circulation amount in the slag smelting link is reduced by 5-8%, and the technological process is simplified. The lead content in the secondary zinc oxide obtained by fuming and volatilizing the high-zinc slag is reduced by 50% or above, the leaching slag generated in the subsequent wet treatment process is reduced by 40% or above, and the working efficiency of a recovery system is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of nonferrous metallurgical solid waste, and specifically relates to a short-process recovery method for zinc smelting slag. Background Art

[0002] Zinc smelting processes are usually divided into two types: hydrometallurgical process and pyrometallurgical process. Among them, the hydrometallurgical process is the main one, and its output accounts for more than 85% of the total zinc metal output. According to the different process steps, the hydrometallurgical process is mainly divided into roasting + conventional leaching, roasting + high temperature and high acid leaching, pressurized direct leaching, etc. Therefore, there are many types of smelting slag produced in the hydrometallurgical zinc smelting process, such as conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag, sulfur concentrate flotation tailings, etc. According to the "National List of Hazardous Wastes (2021 Edition)", hydrometallurgical zinc smelting slag is defined as hazardous waste. In 2023, my country's zinc metal production was 7.15 million tons, and the production of smelting slag was about 0.8-1.0 times the production of metallic zinc. It can be seen that my country's annual zinc smelting slag production is very large. If it cannot be properly disposed of, it will pose a threat to the environment. At the same time, there are a large number of valuable metals in the slag, which is a valuable secondary metal resource. Therefore, the development of low-carbon and clean recycling technology for zinc smelting slag is an inevitable trend in the development of the industry.

[0003] At present, the processes for disposing zinc smelting slag in the industry are divided into two categories: pyrometallurgy and hydrometallurgy. Since zinc slag treatment needs to solve the problem of harmless solid waste and full quality utilization, pyrometallurgy is generally used, among which the rotary kiln volatilization method is the most typical. This method has simple process, large processing capacity, and strong raw material adaptability, but its disadvantages are also very obvious, such as low heat utilization rate, high energy consumption, inability to produce acid from flue gas, and low volatilization rate of some metals.

[0004] The oxygen-enriched side-blowing method is a new slag treatment technology independently developed in China in recent years. It usually adopts a side-blowing smelting furnace with a fuming furnace. The process has the advantages of large processing capacity, strong raw material adaptability, low energy consumption, small flue gas volume, acid production, and long furnace life. It is a preferred technology for zinc smelting enterprises to upgrade and transform in the future. However, there are still some problems in using oxygen-enriched side-blowing technology to treat zinc smelting slag alone. For example, the metal elements that need to be recycled first in zinc smelting slag are Zn, Pb, Ag, etc., and the content of Pb and Ag is usually low. Some companies use lead smelting processes such as Kifuset to treat zinc smelting slag. In the smelting stage, crude lead can be used to capture Pb and Ag to achieve lead-zinc separation. However, when using oxygen-enriched side-blowing to treat zinc slag alone, it is difficult to generate a metal phase due to the low Pb content. The usual design idea is that the smelting section only carries out chemical desulfurization, enriches the metal elements in the slag, and the smoke dust needs to be returned to the smelting batch for secondary smelting due to the low Pb content (content 15-25%). In the fuming section, Zn, Pb, Ag, etc. in the slag are volatilized into the secondary zinc oxide smoke dust for wet recovery. Since lead and zinc cannot be separated, new lead-silver leaching slag will be produced during the leaching of smoke dust in the subsequent process, which needs to be transported to the lead smelting pyrometallurgical system for disposal again. A large amount of lead elements are ineffectively circulated in the process, which is a problem that needs to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for short-process recovery of zinc smelting slag based on the difference in the volatility characteristics of lead and zinc oxides, with the aim of realizing the step-by-step extraction of Pb and Zn in the slag during the zinc slag pyrometallurgical treatment process, avoiding the ineffective circulation of the Pb element in the subsequent process, and improving the working efficiency of the system.

[0006] The method for recovering zinc smelting slag in a short process of the present invention comprises the following steps:

[0007] 1) mixing the first zinc smelting slag and the second zinc smelting slag, drying them, and then granulating them to obtain mixed granulated zinc smelting slag;

[0008] 2) adding the mixed granulated zinc smelting slag obtained in step 1) into a smelting furnace, blowing in oxygen-enriched air and fuel, and adding an acidic flux, smelting in an oxidizing atmosphere, and obtaining flue gas and high-zinc slag after the smelting is completed;

[0009] 3) adding the high-zinc slag obtained in step 2) into a fuming furnace, blowing in oxygen-enriched air and fuel, and performing fuming blowing in a reducing atmosphere to obtain blowing slag and zinc-containing smoke.

[0010] In the smelting stage of step 2), SO2 produced by the decomposition of sulfate in the zinc smelting slag and the oxidation of sulfur enters the flue gas, and metal elements such as Pb and Ag in the zinc smelting slag volatilize under high temperature conditions to form lead-rich smoke. ZnO is difficult to volatilize, and forms high-zinc slag with other impurity elements and flux, thereby separating Pb and Zn in the zinc smelting slag.

[0011] In the fuming and blowing stage of step 3), ZnO in the high-zinc slag is reduced to Zn element in a reducing atmosphere, volatilizes from the slag into the flue gas to form zinc-containing flue gas, and the Zn element in the zinc-containing flue gas is secondary oxidized to form secondary zinc oxide dust. After the blowing slag is treated with water quenching, a glassy general solid waste is formed, which can be used as an active material for the preparation of building materials.

[0012] In step 1), the first zinc smelting slag and the second zinc smelting slag are mixed, dried, and then granulated to reduce the generation of smoke and dust when entering the furnace. There will be some powder in the dried charge, which is light in weight. If it is directly put into the furnace, it will be directly brought into the flue by the flue gas flow in the smelting furnace, resulting in an increase in the amount of smoke and dust.

[0013] Preferably, in step 1), the first zinc smelting slag is roasted sand leaching slag. In roasted sand leaching slag, the S element is mostly present in the form of sulfate. The second zinc smelting slag is direct leaching slag. In direct leaching slag, the S element is mostly present in the form of combustible sulfur such as sulfur.

[0014] Further preferably, the roasted sand leaching residue includes at least one of conventional leaching residue, iron precipitate residue, etc.; the direct leaching residue includes at least one of oxygen pressure leaching residue, sulfur concentrate flotation tailings, etc.

[0015] Preferably, in step 1), the mass ratio of the first zinc smelting slag to the second zinc smelting slag can be any ratio. Preferably, in terms of process applicability, the mass ratio of the first zinc smelting slag to the second zinc smelting slag can be 0-100:100-0.

[0016] Preferably, in step 1), the zinc smelting slag after mixed granulation contains H2O 10% or less, Fe20-25%, SiO210-15%, Zn 10-15%, Pb 3-5%, and S15-20%.

[0017] When the roasted sand leaching slag is treated alone, the S element in the slag mostly exists in the form of sulfate, which absorbs heat during the chemical reaction process, resulting in high energy consumption for slag treatment. When the direct leaching slag is treated alone, the S element in the slag mostly exists in the form of sulfur, etc., and it is easy for a large amount of sulfur to volatilize to the upper flue and the waste heat boiler and incompletely burn, making it difficult to fully transfer heat to the molten pool. The present invention adopts a method of combining roasted sand leaching slag + direct leaching slag for treatment. Specifically, several of conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag, sulfur concentrate flotation tailings, etc. are mixed. On the one hand, the chemical combustion heat of combustible sulfur in oxygen pressure leaching slag, sulfur concentrate flotation tailings, etc. is used to reduce coal consumption. On the other hand, conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag, sulfur concentrate flotation tailings, etc. are used to wrap each other during granulation to reduce the sulfur volatilization rate during smelting.

[0018] In step 2), the smelting process conditions include: the smelting atmosphere is a weak oxidizing atmosphere, the oxygen excess coefficient is 1.05-1.10, the oxygen-enriched air concentration is 75-85%, the coal rate is 10-13%, the flux rate is 4%-5%, the smelting temperature is maintained at 1350-1450°C, and the smelting time is 1.5-2h. Here, the coal rate = fuel mass / total mass of zinc smelting slag × 100%; the flux rate = flux mass / total mass of zinc smelting slag × 100%.

[0019] Under the smelting conditions, SO2 produced by the decomposition of sulfate in zinc smelting slag and oxidation of sulfur enters the flue gas, and then enters the acid-making process after waste heat recovery, dust collection and purification; metal elements such as Pb and Ag in zinc smelting slag volatilize at the smelting temperature to form lead-rich smoke, which can be directly sent to the lead smelting system for comprehensive recovery; ZnO is difficult to volatilize, and forms high-zinc slag with other impurity elements and flux. After smelting is completed, the slag is discharged from the slag port and flows into the fuming furnace charging port through the chute for fuming and blowing treatment.

[0020] Specifically, in step 2), the fuel is at least one of pulverized coal, natural gas, etc.

[0021] Specifically, in step 2), the acidic flux is silica. The addition of the acidic flux silica makes the slag type of high zinc slag ZnO-Fe x O-SiO2 ternary smelting slag, the FeO / SiO2 in the slag is controlled at 1.8-2.0.

[0022] Preferably, in step 2), the smelting furnace is an oxygen-enriched side-blown furnace; the oxygen-enriched side-blown furnace includes a furnace body, which is a rectangular structure, and a solid charge feeding port and a flue are arranged on the top thereof, and the rear end of the flue is connected to a flue gas treatment system; a plurality of submerged side-blowing spray guns are arranged in the middle part of the furnace side wall, and the spray guns are made of multiple layers of concentric sleeves; a secondary air port is arranged on the upper part of the furnace side wall; a slag port is arranged in the middle part of the end wall, which is connected to the feed port of the volatilization blowing device through a chute, and an emptying port is arranged at the bottom. The solid charge feeding port is used to add zinc smelting slag and flux, block fuel, etc. after mixed granulation; the flue gas treatment system can be used for waste heat recovery and smoke dust capture; the side-blowing spray gun can be used to simultaneously blow in oxygen-enriched air and fuel, and the oxygen partial pressure in the furnace can be flexibly controlled by adjusting the ratio of oxygen to fuel; the secondary air port is used to ignite sulfur and other combustible components in the flue gas to suppress slagging in the flue.

[0023] Preferably, in step 3), the fuming and blowing is a periodic operation, and its process conditions include: controlling the slag layer height in the fuming furnace to 500-600mm per furnace, the oxygen concentration to 21-25%, the coal rate to 15-20%, the oxygen excess coefficient to be controlled between 0.65-0.95, the fuming and blowing temperature to 1200-1300°C, and the blowing time to 1-1.5h. The coal rate here refers to the ratio of the mass of the fuel to the mass of the hot slag entering the furnace. Under the fuming and blowing conditions, the ZnO in the high-zinc slag is reduced to Zn elemental substance in a reducing atmosphere, which volatilizes from the slag into the flue gas to obtain zinc-containing flue gas; ZnO-Fe x Conversion of O-SiO2 ternary high zinc slag into Fe x O-SiO2 binary blowing slag, containing Zn <1.5%, Pb <0.1%. Zinc-containing flue gas is secondary oxidized to form secondary zinc oxide dust, which is discharged after waste heat recovery, dust collection and purification to meet the standards; the blowing slag is discharged from the fuming furnace slag outlet and then quenched with water to form glassy general solid waste, which can be used as an active material for preparing building materials.

[0024] Preferably, in step 3), the fuming furnace includes a furnace body, which is a rectangular structure, with a liquid feeding port on the upper part of one side end wall, a solid charge feeding port and a flue on the top, and the rear end of the flue is connected to the flue gas treatment system; a plurality of submerged side-blowing spray guns are arranged at the lower part of the furnace side wall, and the spray guns are made of multiple layers of concentric sleeves; a secondary air port is arranged on the upper part of the furnace side wall; a slag discharge port and an emptying port are arranged at the bottom of the furnace end wall; the solid charge feeding port is used for adding flux, block fuel, etc.; the flue gas treatment system is used for waste heat recovery and smoke dust capture; the side-blowing spray gun is used for simultaneously blowing in oxygen-enriched air and fuel; the secondary air port is used to ignite combustible components such as CO in the flue gas.

[0025] Specifically, in step 3), the fuel is at least one of pulverized coal, natural gas, etc.

[0026] Principles and beneficial effects of the present invention:

[0027] 1) The direct leaching slag and roasted sand leaching slag are processed in a coordinated manner, making full use of the chemical reaction heat of combustible sulfur in solid waste to replace part of the fuel heat release, and reducing the energy consumption of zinc smelting slag recovery to 250-300kg / t, which is significantly lower than the traditional rotary kiln process. 2) The oxidation of the atmosphere is enhanced in the smelting stage, and the lead-containing phase in the slag is converted into PbO. By increasing the smelting temperature, the volatile vapor pressure of PbO and Ag phases is increased by one order of magnitude, and Pb and Ag are enriched in the smoke. Since ZnO is difficult to volatilize and enrich in the smelting slag, the separation of lead and zinc is achieved in the smelting section. The Pb content in the lead-rich smoke is increased to more than 40%, which can be directly sent to the lead smelting system for comprehensive recovery, without the need to return to the smelting batching link as return material, so the material circulation volume in the slag treatment link can be reduced by 5-8%, simplifying the process flow. 3) The lead content in the secondary zinc oxide obtained by fuming and volatilizing high-zinc slag is reduced by more than 50%, and the leaching slag produced in the subsequent wet treatment process has a significant reduction effect, which significantly reduces the ineffective circulation of hazardous wastes between the wet and pyrometallurgical smelting systems. The Pb element directly enters the lead smelting system mainly in the form of smelting dust, shortening the lead recovery process of the existing process and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a short-process recovery process flow chart of zinc smelting slag in Examples 1 to 3. DETAILED DESCRIPTION

[0029] The following is a further description of the zinc smelting slag short-process recovery process of the present invention in conjunction with the embodiments.

[0030] In the following examples, the main chemical components of conventional leaching slag include Zn 15%, Pb 4.5%, Fe 29%, and S9%; the main chemical components of iron precipitate slag include Zn 13%, Fe 30%, and S11%; the main chemical components of oxygen pressure leaching slag include Zn 3%, Pb 6%, Fe 2%, and S 65%; the main chemical components of sulfur concentrate flotation tailings include Zn 1%, Pb 10%, Fe 1.5%, and S20%.

[0031] Example 1

[0032] Refer to Figure 1In the process shown, conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag, and sulfur concentrate flotation tailings are mixed, dried, and granulated to obtain mixed granulated zinc smelting slag, wherein the mass proportion of oxygen pressure leaching slag and sulfur concentrate flotation tailings is 30%; the mixed granulated zinc smelting slag contains 10% H2O, 20% Fe, 11.8% Zn, 3.9% Pb, and 18.5% S. The mixed granulated zinc smelting slag is added into the oxygen-enriched side-blowing furnace molten pool from the upper feeding port, oxygen-enriched air and pulverized coal are blown in from the side-blowing lance, and the oxygen excess coefficient is adjusted to 1.05 to perform weak oxidizing atmosphere smelting, with an oxygen-enriched air concentration of 85% and a coal rate of 11%; at the same time, silica flux is added from the upper feeding port to make slag, and the flux rate is 4%; the smelting temperature is controlled to be maintained at 1400°C, and the smelting is performed for 2 hours to obtain high zinc slag and flue gas. The concentration of SO2 in the flue gas is 18%. After waste heat recovery and dust collection, it enters the acid-making process. At the same time, metal elements such as Pb and Ag volatilize at high temperature to form lead-rich smoke. The smoke rate of lead-rich smoke is 5%, containing 40.5% Pb and 2900g / t Ag. The lead-rich smoke is sent to the lead smelting system for comprehensive recovery. x O-SiO2 is a smelting slag, the FeO / SiO2 in the slag is controlled at 2.0, containing 17.5% Zn and 2.8% Pb; the high zinc slag flows into the fuming furnace through the chute between the oxygen-enriched side-blowing furnace and the fuming furnace for fuming blowing. Oxygen-enriched air and pulverized coal are blown into the furnace by the side-blowing lance, with an oxygen concentration of 25%, a coal rate of 15%, and an oxygen excess coefficient of 0.7. The furnace is blown at 1250℃ in a reducing atmosphere for 1 hour to generate blowing slag and zinc-containing flue gas. The blowing slag is Fe x O-SiO2 binary slag contains 1.4% Zn and 0.03% Pb; the blowing slag is discharged from the slag outlet and quenched with water to obtain water-quenched slag, which can be used as an active raw material for preparing building materials. Zinc-containing flue gas is recovered through waste heat and dust collection to obtain low-lead zinc oxide dust and flue gas, which is discharged after being purified and meets the standards. Low-lead zinc oxide dust contains 61% Zn and 9.5% Pb, which is sent to the wet method system for recovery.

[0033] In this embodiment, four types of zinc smelting slag are processed in a coordinated manner, and the chemical reaction heat of combustible sulfur in solid waste is fully utilized to replace part of the fuel heat release, and the energy consumption of zinc smelting slag recovery is reduced to 280kg / t, which is significantly lower than the traditional rotary kiln process and the oxygen-enriched side blowing process of treating conventional slag alone. By changing the process parameters, the separation of lead and zinc is achieved in the smelting section, and the smelting dust does not need to be returned to the smelting batching link as return material, reducing the material circulation volume by 5%. The lead content in the secondary zinc oxide smoke is reduced by 50%, which significantly reduces the ineffective circulation of hazardous waste between the hydrometallurgical and pyrometallurgical smelting systems.

[0034] Example 2

[0035] Refer to Figure 1In the process shown, conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag, and sulfur concentrate flotation tailings are mixed, dried, and granulated to obtain mixed granulated zinc smelting slag, wherein the mass proportion of oxygen pressure leaching slag and sulfur concentrate flotation tailings is 30%; the mixed granulated zinc smelting slag contains 10% H2O, 22% Fe, 13% Zn, 4.5% Pb, and 16% S. The mixed granulated zinc smelting slag is added into the oxygen-enriched side-blowing furnace molten pool from the upper feeding port, oxygen-enriched air and pulverized coal are blown in from the side-blowing lance, and the oxygen excess coefficient is adjusted to 1.05 to perform weak oxidizing atmosphere smelting, with an oxygen-enriched air concentration of 80% and a coal rate of 12%; at the same time, silica flux is added from the upper feeding port to slag, and the flux rate is 4.4%; the smelting temperature is maintained at 1450°C, and the smelting is performed for 1.8 hours to obtain high-zinc slag and flue gas. The concentration of SO2 in the flue gas is 18%. After waste heat recovery and dust collection, it enters the acid-making process and volatilizes at high temperature to form lead-rich smoke. The smoke rate of lead-rich smoke is 5.2%, containing 41% Pb and 2800g / t Ag. The lead-rich smoke is sent to the lead smelting system for comprehensive recovery. x O-SiO2 is a smelting slag, the FeO / SiO2 in the slag is controlled at 1.9, containing Zn18%, Pb3%; high zinc slag flows into the fuming furnace through the chute between the oxygen-enriched side-blowing furnace and the fuming furnace for fuming blowing. Oxygen-enriched air and pulverized coal are blown into the furnace by the side-blowing lance, the oxygen concentration is 24%, the coal rate is 16%, and the oxygen excess coefficient is controlled at 0.7. It is blown at 1200℃ and a reducing atmosphere for 1h to generate blowing slag and zinc-containing flue gas. The blowing slag is Fe x O-SiO2 binary slag contains 1.3% Zn and 0.07% Pb; the blowing slag is discharged from the slag outlet and quenched with water to obtain water-quenched slag, which can be used as an active raw material for preparing building materials. Zinc-containing flue gas is recovered through waste heat and dust collection to obtain low-lead zinc oxide dust and flue gas, which is discharged after being purified and meets the standards. Low-lead zinc oxide dust contains 62% Zn and 10% Pb, which is sent to the wet method system for recovery.

[0036] Example 3

[0037] Refer to Figure 1The process shown is to mix, dry and granulate conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag and sulfur concentrate flotation tailings to obtain mixed granulated zinc smelting slag, wherein the mass proportion of oxygen pressure leaching slag and sulfur concentrate flotation tailings is 30%; the mixed granulated zinc smelting slag contains H2O 9%, Fe 25%, Zn 15%, Pb 5%, and S20%. The mixed granulated zinc smelting slag is added into the oxygen-enriched side-blowing furnace molten pool from the upper feeding port, oxygen-enriched air and pulverized coal are blown in from the side-blowing lance, and the oxygen excess coefficient is adjusted to 1.1 to perform weak oxidizing atmosphere smelting, with an oxygen-enriched air concentration of 75% and a coal rate of 10%; at the same time, silica flux is added from the upper feeding port to slag, and the flux rate is 5%; the smelting temperature is maintained at 1350°C, and the smelting is performed for 1.5 hours to obtain high zinc slag and flue gas. The concentration of SO2 in the flue gas is 20%. After waste heat recovery and dust collection, it enters the acid making process and volatilizes at high temperature to form lead-rich smoke. The smoke rate of lead-rich smoke is 4.5%, containing 40% Pb and 2700g / t Ag. The lead-rich smoke is sent to the lead smelting system for comprehensive recovery. x O-SiO2 is a smelting slag, the FeO / SiO2 in the slag is controlled at 2.0, containing 18.5% Zn and 3.3% Pb; the high zinc slag flows into the fuming furnace through the chute between the oxygen-enriched side-blowing furnace and the fuming furnace for volatilization and blowing. Oxygen-enriched air and pulverized coal are blown into the furnace by the side-blowing lance, with an oxygen concentration of 22%, a coal rate of 18%, and an oxygen excess coefficient of 0.65. The furnace is blown at 1300℃ and a reducing atmosphere for 1 hour to generate blowing slag and zinc-containing flue gas. The blowing slag is Fe x O-SiO2 binary slag contains 1.3% Zn and 0.05% Pb; the blowing slag is discharged from the slag outlet and quenched with water to obtain water-quenched slag, which can be used as an active raw material for preparing building materials. Zinc-containing flue gas is recovered through waste heat and dust collection to obtain low-lead secondary zinc oxide dust and flue gas, which are discharged after being purified and meet the standards. Low-lead secondary zinc oxide dust contains 65% Zn and 11% Pb, which is sent to the wet method system for recovery.

[0038] Comparative Example 1

[0039] The mixed zinc smelting slag is recovered according to the conventional oxygen-enriched side-blowing smelting zinc slag method. The conventional leaching slag, iron precipitate slag, oxygen pressure leaching slag and sulfur concentrate flotation tailings in Example 1 are mixed, dried and granulated. The proportion of oxygen pressure leaching slag and sulfur concentrate flotation tailings in the mixed zinc smelting slag containing combustible sulfur is reduced from 30% to 13%. The mixed zinc smelting slag contains 13.3% Zn, 3.8% Pb and 11.8% S. Specifically, the mixed zinc smelting slag is slaged with silica flux under the conditions of 85% oxygen-enriched air concentration, 19% coal rate and oxygen excess coefficient of 1.0, and the flux rate is 10%. The mixed zinc smelting slag is smelted at 1250℃ for 2h, the smelting smoke rate is 5.8%, and the Pb content in the smoke is only 22%, which needs to be returned to the smelting ingredients, increasing the ineffective circulation of materials. The smelting high-zinc slag was fumed and volatilized at 1250°C for 1 hour under the conditions of oxygen concentration of 25%, coal rate of 16%, and oxygen excess coefficient of 0.7, and the secondary zinc oxide smoke dust containing 16% Pb was produced. The smoke dust entered the subsequent wet treatment link and the leaching slag hazardous waste produced increased by more than 60% compared with Example 1. The energy consumption of zinc slag treatment under this process condition was 350kg / t, which was 25% higher than that of Example 1.

[0040] In summary, the method of the present invention appropriately increases the proportion of sulfur-containing zinc slag, which helps reduce coal consumption. At the same time, increasing the temperature of the smelting section and the oxidizing atmosphere helps the direct volatilization of Pb and Ag, reducing their ineffective circulation in the smelting process.

[0041] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for short-process recovery of zinc smelting slag, comprising the following steps: 1) mixing the first zinc smelting slag and the second zinc smelting slag, drying them, and then granulating them to obtain mixed granulated zinc smelting slag; 2) adding the mixed granulated zinc smelting slag obtained in step 1) into a smelting furnace, blowing in oxygen-enriched air and fuel, and adding an acidic flux, smelting in an oxidizing atmosphere, and obtaining flue gas and high-zinc slag after the smelting is completed; 3) adding the high-zinc slag obtained in step 2) into a fuming furnace, blowing in oxygen-enriched air and fuel, and performing fuming blowing in a reducing atmosphere to obtain blowing slag and zinc-containing flue gas.

2. The method according to claim 1, characterized in that In step 1), the first zinc smelting slag is roasted sand leaching slag, and the second zinc smelting slag is direct leaching slag.

3. The method according to claim 2, characterized in that The roasted sand leaching residue includes at least one of conventional leaching residue and iron precipitate residue; the direct leaching residue includes at least one of oxygen pressure leaching residue and sulfur concentrate flotation tailings.

4. The method according to claim 1, characterized in that In step 1), the zinc smelting slag after mixed granulation contains H2O 10% or less, Fe 20-25%, SiO2 10-15%, Zn 10-15%, Pb 3-5%, and S 15-20%.

5. The method according to claim 1, characterized in that In step 2), the smelting process conditions include: the smelting atmosphere is a weak oxidizing atmosphere, the oxygen excess coefficient is 1.05-1.10, the oxygen-enriched air concentration is 75-85%, the coal rate is 10-13%, the flux rate is 4%-5%, the smelting temperature is maintained at 1350-1450°C, and the smelting time is 1.5-2h.

6. The method according to claim 1, characterized in that In step 2), the fuel includes at least one of pulverized coal and natural gas; the acidic flux is silica; the high zinc slag is ZnO-Fe x O-SiO2 is a smelting slag, and the FeO / SiO2 ratio in the slag is controlled at 1.8-2.

0.

7. The method according to claim 1, characterized in that In step 2), the smelting furnace is an oxygen-enriched side-blowing furnace; the oxygen-enriched side-blowing furnace includes a furnace body, which is a rectangular structure, with a solid charge feeding port and a flue on the top, and the rear end of the flue is connected to the flue gas treatment system; a plurality of submerged side-blowing spray guns are arranged in the middle part of the furnace side wall, and the spray guns are made of multiple layers of concentric sleeves; a secondary air inlet is arranged on the upper part of the furnace side wall; a slag outlet is arranged in the middle part of the end wall, which is connected to the feed port of the volatilization blowing device through a chute, and an emptying port is arranged at the bottom.

8. The method according to claim 1, characterized in that In step 3), fuming and blowing is a periodic operation, and its process conditions include: controlling the slag layer height in the fuming furnace to 500-600mm per furnace, the oxygen concentration to 21-25%, the coal rate to 15-20%, the oxygen excess coefficient to be controlled between 0.65-0.95, the fuming and blowing temperature to 1200-1300°C, and the blowing time to 1-1.5h.

9. The method according to claim 1, characterized in that: In step 3), the fuel includes at least one of pulverized coal and natural gas.

10. The method according to claim 1, characterized in that In step 3), the fuming furnace includes a furnace body, which is a rectangular structure, with a liquid feeding port on the upper part of one side end wall, a solid charge feeding port and a flue on the top, and a flue connected to a flue gas treatment system at the rear end; a plurality of submerged side-blowing spray guns are arranged at the lower part of the furnace side wall, and the spray guns are made of multiple layers of concentric sleeves; a secondary air port is arranged on the upper part of the furnace side wall; a slag discharge port and an emptying port are arranged at the bottom of the furnace end wall.

Images