A method of redox smelting of a zinc sulphide concentrate

Abstract

The application discloses a method for oxidizing and reducing smelting of zinc sulfide concentrate and relates to the technical field of pyrometallurgy, and comprises the following steps: step one, batching; step two, granulation; step three, oxidizing smelting; step four, reducing smelting, the zinc oxide melt after oxidizing desulfurization is added into a reducing side-blown furnace, granular coal is added, the proportion of the granular coal accounts for 15%-18% of the weight of the zinc oxide melt, oxygen-enriched air is introduced for reducing smelting, water gas generated in a producer is added into the upper space of the furnace, the volume ratio of furnace gas (H2+CO) / CO2 is controlled to be 1.5-2.0; step five, fuming; step six, condensation separation; and step seven, rectification. The water gas generated in the producer is added into the upper space of the reducing side-blown furnace, the volume ratio of furnace gas (H2+CO) / CO2 is controlled to be 1.5-2.0, the oxygen-enriched air can be completely combusted and a steady-state reducing atmosphere is formed, and the zinc vapor is prevented from being oxidized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pyrometallurgy, in particular to a method for oxidizing and reducing smelting of zinc sulfide concentrate. BACKGROUND

[0002] At present, in the process of zinc smelting, the main process flow is wet zinc smelting, and the proportion of wet zinc smelting products is more than 80%. Wet zinc smelting has the characteristics of wide raw material adaptability and good comprehensive recovery, but also has the problems of long process flow, wet residue needing harmless treatment by fire, high energy consumption, etc. There are two process methods for zinc smelting by fire, namely electric furnace zinc smelting and closed blast furnace zinc smelting. Electric furnace zinc smelting has the characteristics of shorter process flow and lower investment, but has the problems of low single furnace capacity and high power consumption. Closed blast furnace zinc smelting has the advantages of short process flow and strong raw material adaptability, but has the problems of complex sintering and crushing, poor waste heat recovery, and consumption of coke in blast furnace.

[0003] With the maturity and development of oxygen-enriched side-blown smelting technology, more and more smelting units focus on using this technology to process zinc-containing materials to achieve efficient zinc smelting. In the prior art, the treatment of zinc sulfide concentrate often cannot accurately control the proportioning and smelting conditions, resulting in low smelting efficiency and unstable product quality. In the process of reducing smelting of zinc in zinc sulfide concentrate, zinc vapor is easily oxidized to zinc oxide in the condensation process, which not only reduces the recovery rate of zinc, but also increases the complexity and cost of subsequent treatment. SUMMARY

[0004] The purpose of the present application is to provide a method for oxidizing and reducing smelting of zinc sulfide concentrate to solve the problems raised in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a method for oxidizing and reducing smelting of zinc sulfide concentrate, which is based on the principle of using oxygen to oxidize and desulfurize zinc sulfide concentrate at high temperature, and then reducing the zinc oxide after oxidation and desulfurization to produce zinc vapor, and the chemical reaction formula is as follows:

[0006] ZnS(s) + 1.5O2(g) = ZnO(s) + SO2(g)

[0007] ZnO(s) + CO(g) = Zn(g) + CO2(g)

[0008] In order to prevent the zinc vapor produced by reduction smelting from being oxidized to zinc oxide in the condensation process, the present application adds water gas from the furnace in the upper space of the reduction side-blown furnace to maintain a stable reducing atmosphere, which specifically includes the following steps:

[0009] Step one: batching, the zinc sulfide concentrate is batched with flux in a batching bin, wherein the component content of the zinc sulfide concentrate is Zn: 48%-54%, Pb: 1%-3%, Fe: 5%-10%, S: 28%-35%;

[0010] Step two: granulation, the mixed material is put into a cylindrical granulator for mixing and granulation, and the particle size of the material after granulation is required to be 8-10 mm, and the water content is 8%-10%;

[0011] Step three: oxidation smelting, the granulated material is added into 5-10 mm particle coal into an oxidation side-blown furnace, the added 5-10 mm particle coal accounts for 6%-8% of the weight of the material, and oxygen-enriched air with an oxygen concentration of 70-80 vol% is introduced for oxidation smelting, and the produced zinc oxide melt is sent to reduction smelting;

[0012] Step four: reduction smelting, the zinc oxide melt after oxidation desulfurization is added into a reduction side-blown furnace, 5-10 mm particle coal is added, the 5-10 mm particle coal accounts for 15%-18% of the weight of the zinc oxide melt, oxygen-enriched air is introduced for reduction smelting, and reduction flue gas is produced, the component of the reduction flue gas is Zn: 18-25 vol%, CO: 7-12 vol%, CO2: 20-26 vol%, and producer gas is added into the upper space of the furnace, which accounts for 40-60 vol% of the amount of the reduction flue gas, the volume ratio of (H2+CO) / CO2 in the furnace gas is controlled to be 1.5-2.0, the produced zinc-containing vapor furnace gas is sent to a lead rain condenser, and the produced reduction slag is sent to a fuming furnace for blowing;

[0013] Step five: fuming, the reduction slag is sent into a fuming furnace, and pulverized coal is sprayed into the furnace for fuming and blowing;

[0014] Step six: condensation and separation, the zinc-containing vapor produced from the reduction side-blown furnace is sent to a lead rain condenser for cooling, the condensing medium is lead liquid, the lead liquid traps zinc vapor to form lead-zinc liquid which is sent to a separation system, the furnace gas is burned to recover heat value, and lead and zinc are separated by clarification due to different specific gravities;

[0015] Step seven: rectification, the crude zinc liquid separated from the lead rain condenser is sent to a rectification furnace.

[0016] Further, in step one, the flux is limestone, quartz, iron filings or iron sulfide.

[0017] Further, in step three, the temperature of the oxidation smelting is 1200-1250℃, the time is 2-2.5 h, the dust-containing flue gas produced by the oxidation smelting is sent to acid production after waste heat utilization and dust collection.

[0018] Further, in step four, the oxygen concentration of the introduced oxygen-enriched air is 45-55 vol%, the temperature of the reduction smelting is 1250-1300℃, and the time is 2-2.5 h.

[0019] Further, in the step four, the producer gas is a mixed gas generated by the reaction of solid fuel coal with gasification agent, water vapor under high temperature conditions, and the composition of the producer gas is H2: 40%-50vol%, CO: 30%-40vol%, CO2: 5%-10vol%, and the temperature is 600-700℃.

[0020] Further, in the step five, the proportion of the injected pulverized coal is 18%-20% of the weight of the reduction slag, the control temperature of the fuming and blowing is 1250-1300℃, and the time is 2-2.5h.

[0021] Further, in the step five, the generated dust-containing flue gas is sent to a flue gas treatment system after waste heat utilization and dust collection, and the collected zinc oxide is returned to the batching system, and the generated slag is sold after water quenching.

[0022] Further, in the step six, the lower lead liquid is returned to the lead rain condenser for recycling, and the upper zinc liquid enters the zinc storage tank to generate crude zinc liquid, and the high-temperature lead liquid in the separation system is cooled by water vapor to 100-120℃.

[0023] Further, in the step seven, the rectification furnace includes a lead tower and a cadmium tower, the zinc liquid flows into the lead tower, most of the zinc and the contained cadmium therein are volatilized in vapor state at a temperature of 750-850℃, and the lead and other high-boiling-point impurities are discharged in liquid alloy for separation, the generated cadmium-containing zinc in the lead tower is introduced into the cadmium tower by a channel, and the zinc and cadmium are separated at a temperature of 800-900℃, and the pure zinc liquid enters the pure zinc tank from the lower part.

[0024] In the above technical solution, the present application provides technical effects and advantages:

[0025] 1. The producer gas is added to the upper space of the reduction side-blown furnace, the volume ratio of the furnace gas (H2+CO) / CO2 is controlled to be 1.5-2.0, the oxygen-rich air can be completely combusted to form a stable reduction atmosphere, and the zinc vapor is prevented from being oxidized;

[0026] 2. For the zinc sulfide concentrate with the composition of Zn: 48%-54%, Pb: 1%-3%, Fe: 5%-10%, and S: 28%-35%, the precise control of the batching ratio and the smelting conditions ensures the efficiency and stability of the smelting process, and improves the product quality;

[0027] 3. The coal instead of coke is adopted, the production cost is reduced, the comprehensive utilization rate of resources is improved, and good economic benefits are obtained;

[0028] 4. The lead rain condenser has good adaptability to the fluctuation of the zinc vapor concentration, can handle a large amount of furnace gas, and is suitable for large-scale industrial production.

[0029] 5. In the process of zinc smelting by side-blown furnace oxidation-reduction, zinc is volatilized in vapor form, and after condensation recovery, the recovery rate of zinc can reach more than 97%. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0031] Figure 1 The process flow chart of the present application. DETAILED DESCRIPTION

[0032] In order to make those skilled in the art better understand the technical solutions of the present application, the present application will be further described in detail with reference to the drawings.

[0033] The water gas used in the present application is a mixed gas generated by the reaction of solid fuel coal with gasification agent, water vapor under high temperature conditions, and its main components include: H2: 40-50vol%, CO: 30-40vol%, CO2: 5-10vol%.

[0034] The device used in the present application includes: a batching bin, a cylindrical granulator, an oxidation side-blown furnace, a reduction side-blown furnace, a fuming furnace, a lead rain condenser, a separation system, and a rectification furnace.

[0035] Example 1: Please refer to Figure 1 The present application provides a method for zinc sulfide concentrate oxidation-reduction smelting, comprising the following steps:

[0036] Step 1: batching, the zinc sulfide concentrate is batched with flux in the batching bin, wherein the component content of the zinc sulfide concentrate is Zn: 48%-54%, Pb: 1%-3%, Fe: 5%-10%, S: 28%-35%, and the flux is limestone, quartz, iron filings or iron sulfide;

[0037] Step 2: granulation, the mixed material is mixed and granulated in the cylindrical granulator to ensure uniform mixing and sufficient wetting of the material, and the particle size of the material after granulation is 8mm and the water content is 8%;

[0038] Step 3: oxidation smelting, the granulated material is mixed with 5mm coal into the oxidation side-blown furnace, the 5mm coal accounts for 6% of the weight of the material, and the oxidation smelting is carried out by introducing oxygen-enriched air with an oxygen concentration of 70vol%, the temperature is controlled at 1200℃, and the time is 2h, the dust-containing flue gas produced is sent to the acid production after waste heat utilization and dust collection, and the zinc oxide melt produced is sent to reduction smelting;

[0039] Step four: reduction smelting, the oxidized desulfurized zinc oxide melt is added into the reduction side-blown furnace, 5mm granular coal is added, the 5mm granular coal accounts for 16% of the weight of the zinc oxide melt, oxygen-enriched air with an oxygen concentration of 45vol% is blown in for reduction smelting, the temperature is controlled at 1250℃, and the time is 2h, reduction flue gas is produced, the composition of the reduction flue gas is Zn: 18-25vol%, CO: 7-12vol%, and CO2: 20-26vol%; and water gas is added into the upper space of the furnace, the temperature is 600℃, the volume accounts for 40vol% of the amount of the reduction flue gas, the volume ratio of (H2+CO) / CO2 in the furnace gas is controlled at 1.5-2.0, the zinc-containing vapor furnace gas produced is sent to the lead rain condenser, and the reduction slag produced is sent to the fuming furnace for blowing;

[0040] Step five: fuming, the reduction slag is sent into the fuming furnace, pulverized coal is sprayed into the furnace for fuming and blowing, the temperature is controlled at 1250℃, and the time is 2h, wherein the pulverized coal accounts for 18% of the mass of the reduction slag, the dust-containing flue gas produced is sent to the flue gas treatment system after waste heat utilization and dust collection, and the zinc oxide collected by dust collection is returned to the batching;

[0041] Step six: condensation and separation, the zinc-containing vapor furnace gas is sent into the lead rain condenser for cooling, the condensation medium is lead liquid, the lead liquid traps the zinc vapor to form lead-zinc liquid which enters the separation system, and the furnace gas is burned to recover the heat value; the lead-zinc is clarified and separated according to the different specific gravities, the lower layer of lead liquid is returned to the lead rain condenser for recycling, the upper layer of zinc liquid enters the zinc storage tank to produce crude zinc liquid, the high-temperature lead liquid in the separation system is cooled by steam to 100℃, and power generation can be realized by waste heat utilization;

[0042] Step seven: rectification, the crude zinc liquid is sent into the rectification furnace for rectification, the rectification furnace includes a lead tower and a cadmium tower, the zinc liquid flows into the lead tower, most of the zinc and the cadmium contained therein are volatilized in the vapor state at a temperature of 750℃, while the lead and other high-boiling-point impurities are discharged in the form of liquid alloy for separation, the cadmium-containing zinc produced by the lead tower is introduced into the cadmium tower by a chute, and the zinc and cadmium are separated at a temperature of 800℃, and the pure zinc liquid enters the pure zinc tank from the lower part, thereby obtaining the rectified zinc.

[0043] Example two: a zinc sulfide concentrate with a composition of Zn: 49%, Pb: 3%, Fe: 10%, and S: 33% is subjected to oxidation and reduction smelting according to the above steps in example one to produce reduction flue gas, the composition of the reduction flue gas is Zn: 19%, CO: 9%, and CO2: 23%, water gas with a composition of H2: 46%, CO: 39%, and CO2: 8% is added into the upper space of the reduction furnace, the mixed furnace gas (H2+CO) / CO2=1.6 is obtained, the zinc-containing vapor furnace gas enters the lead rain condenser to recover zinc, the reduction slag enters the fuming furnace for blowing, and the final zinc recovery rate is 97.2%.

[0044] Example 3: A zinc sulphide concentrate with composition Zn: 51%, Pb: 2%, Fe: 9%, S: 31% is subjected to redox smelting according to the above steps of Example 1 to produce a reducing offgas with composition Zn: 21%, CO: 8%, CO2: 24%. A producer gas with composition H2: 47%, CO: 37%, CO2: 7% is added to the upper space of the reduction furnace to obtain a mixed furnace gas (H2+CO) / CO2=1.6. The zinc containing steam furnace gas is passed to a lead rain condenser to recover zinc and a reduction slag is produced which is passed to a converting furnace for converting, resulting in a final zinc recovery of 98.0%.

[0045] Example 4: A zinc sulphide concentrate with composition Zn: 53%, Pb: 1%, Fe: 7%, S: 29% is subjected to redox smelting according to the above steps of Example 1 to produce a reducing offgas with composition Zn: 24%, CO: 7%, CO2: 25%. A producer gas with composition H2: 49%, CO: 35%, CO2: 6% is added to the upper space of the reduction furnace to obtain a mixed furnace gas (H2+CO) / CO2=1.5. The zinc containing steam furnace gas is passed to a lead rain condenser to recover zinc and a reduction slag is produced which is passed to a converting furnace for converting, resulting in a final zinc recovery of 98.4%.

[0046] The foregoing merely illustrates some exemplary embodiments of the present application and is not intended to limit the scope of the present application. It will be apparent to those having ordinary skill in the art that various changes can be made without departing from the spirit and scope of the present application. Thus, the present application is not intended to be limited to the illustrative embodiments described herein but rather is to be accorded the full scope consistent with the language of the claims, namely, that of a patent issued on the present application.

Claims

1. A method for the redox smelting of a zinc sulphide concentrate, characterized in that, The method comprises the following steps: Step one: batching, the zinc sulfide concentrate is batched with flux in a batching bin, wherein the component content of the zinc sulfide concentrate is Zn: 48%-54%, Pb: 1%-3%, Fe: 5%-10%, S: 28%-35%; Step two: granulation, the mixed material is put into a cylindrical granulator for mixing and granulation, and the particle size of the material after granulation is 8-10 mm, and the water content is 8%-10%; Step three: oxidation smelting, the granulated material is added into 5-10 mm particle coal into an oxidation side-blown furnace, the added 5-10 mm particle coal accounts for 6%-8% of the weight of the material, and oxygen-enriched air with an oxygen concentration of 70-80 vol% is introduced for oxidation smelting, and the produced zinc oxide melt is sent to reduction smelting; Step four: reduction smelting, the zinc oxide melt after oxidation desulfurization is added into a reduction side-blown furnace, 5-10 mm particle coal is added, the 5-10 mm particle coal accounts for 15%-18% of the weight of the zinc oxide melt, oxygen-enriched air is introduced for reduction smelting, and reduction flue gas is produced, the component of the reduction flue gas is Zn: 18-25 vol%, CO: 7-12 vol%, CO2: 20-26 vol%, water gas is added into the upper space of the furnace, the volume accounts for 40-60 vol% of the amount of the reduction flue gas, the volume ratio of H2+CO / CO2 is controlled to be 1.5-2.0, the produced zinc-containing vapor furnace gas is sent to a lead rain condenser, and the produced reduction slag is sent to a fuming furnace for blowing; Step five: fuming, the reduction slag is sent into a fuming furnace, and pulverized coal is sprayed into the furnace for fuming and blowing; Step six: condensation and separation, the zinc-containing vapor produced from the reduction side-blown furnace is sent into a lead rain condenser for cooling, the condensing medium is lead liquid, the lead liquid traps the zinc vapor to form lead-zinc liquid which is sent into a separation system, the furnace gas is burned to recover heat value, and the lead and zinc are separated by clarification due to different specific gravities; Step seven: rectification, the crude zinc liquid separated from the lead rain condenser is sent into a rectification furnace.

2. A method of redox smelting of a zinc sulphide concentrate according to claim 1 characterised in that: In the step one, the flux is limestone, quartz, iron scrap or iron sulfide.

3. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterised by: In the step three, the temperature of the oxidation smelting is 1200-1250 ℃, the time is 2-2.5 h, the dust-containing flue gas produced by the oxidation smelting is sent to an acid production system after waste heat utilization and dust collection.

4. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterised by: In the step four, the oxygen concentration of the introduced oxygen-enriched air is 45-55 vol%, the temperature of the reduction smelting is 1250-1300 ℃, and the time is 2-2.5 h.

5. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterised by: In the step four, the water gas generated by the solid fuel coal under high temperature conditions is a mixed gas generated by reacting with a gasification agent and steam, and the component of the water gas is H2: 40%-50 vol%, CO: 30%-40 vol%, CO2: 5%-10 vol%, and the temperature is 600-700 ℃.

6. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterised by: In the step five, the sprayed pulverized coal accounts for 18%-20% of the weight of the reduction slag, the control temperature of the fuming and blowing is 1250-1300 ℃, and the time is 2-2.5 h.

7. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterised by: In the step five, the produced dust-containing flue gas is sent to a flue gas treatment system after waste heat utilization and dust collection, the collected zinc oxide is returned to the batching, and the produced slag is sold after water quenching.

8. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterized by: In step six, the lower lead liquid returns to the lead rain condenser for recycling, and the upper zinc liquid enters the zinc storage tank to produce crude zinc liquid. The high-temperature lead liquid in the separation system is cooled by water vapor to 100-120°C.

9. A method of redox smelting of zinc sulphide concentrates according to claim 1, characterized by: In step seven, the rectification furnace includes a lead tower and a cadmium tower. The zinc liquid flows into the lead tower, and most of the zinc and the cadmium contained therein are volatilized in vapor state at a temperature of 750-850°C, while the lead and other high-boiling-point impurities are discharged in liquid alloy for separation. The cadmium-containing zinc produced by the lead tower is introduced into the cadmium tower by a channel, and zinc and cadmium are separated at a temperature of 800-900°C. The pure zinc liquid enters the pure zinc tank from the lower part.

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