Method for redox smelting of lead-zinc materials

Abstract

The invention discloses a lead-zinc material redox smelting method, which relates to the technical field of thermometallurgy, and comprises the following steps: step 1, proportioning; step 2, performing granulation; step 3, oxidizing and smelting; 4, reduction smelting is conducted, specifically, the desulfurized lead-zinc oxide melt is added into a side-blown furnace, pea coal is added, the pea coal accounts for 12%-14% of the weight of the lead-zinc oxide melt, oxygen-enriched air is introduced for reduction smelting, generator water gas is added into the upper space of the furnace, and the volume ratio of furnace gas (H2 + CO) / CO2 is controlled to be 1.5-2.0; step 5, fuming; step 6, condensation separation; and step 7, rectification. Generator water gas is added into the upper space of the reduction side-blown furnace, the volume ratio of furnace gas (H2 + CO) / CO2 is controlled to be 1.5-2.0, oxygen-enriched air can be completely combusted, and the possibility that zinc steam generates zinc oxide is avoided.

Description

Technical Field

[0001] This invention relates to the field of pyrometallurgical technology, specifically to a method for redox smelting of lead and zinc materials. Background Technology

[0002] Currently, there is only one method for simultaneously producing lead and zinc from lead-zinc materials: zinc smelting in a closed blast furnace. In this method, the lead and zinc materials are sintered and then fed into the blast furnace. Lead is produced as liquid from the bottom of the furnace, while zinc is produced as vapor from the top of the furnace, which evaporates and enters the condenser to produce crude zinc. This method has the advantages of wide adaptability to raw materials and a short process flow, but it also has problems such as large sintering and crushing equipment, poor waste heat utilization, and the need for coke consumption in the blast furnace.

[0003] With the development of oxygen-enriched side-blown smelting technology, metallurgists are also studying the use of this technology to process lead and zinc materials. However, during the reduction process, zinc vapor is easily oxidized to zinc oxide, which reduces the zinc recovery rate. At the same time, in the existing technology, it is often difficult to accurately control the proportion of raw materials and smelting conditions for the processing of lead-zinc mixtures, resulting in an imbalance in the recovery rates of lead and zinc during the smelting process, which increases the difficulty of subsequent separation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for redox smelting of lead and zinc materials to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for oxidation-reduction smelting of lead-zinc materials, the principle of which is to use oxygen in the air to oxidize and desulfurize the lead-zinc materials, and then use carbon to reduce the desulfurized lead-zinc oxides into zinc vapor and liquid lead, the chemical reaction formula of which is as follows: ZnS + 1.5O2 → ZnO + SO2 PbS + 1.5O2 → PbO + SO2 ZnO + CO → Zn (gas) + CO2 PbO + CO → Pb (liquid) + CO2 To prevent zinc vapor from oxidizing into zinc oxide, producer water gas is added to the upper space of the reducing side-blown furnace to maintain a steady reducing atmosphere. This includes the following steps: Step 1: Batching. The lead and zinc materials are batched with the flux in the batching silo. The lead and zinc materials include lead concentrate, zinc concentrate, lead-zinc mixed ore, and lead-zinc mixed materials. The required Pb / Zn weight ratio is 0.4-0.6, the total lead and zinc content is 30%-60%, and the sulfur content of the mixed material is 18%-24%. Step 2: Granulation. Add the prepared mixture into a cylindrical pellet mill for mixing and granulation. The particle size of the granulated material should be 8-10mm, and the moisture content should be 8%-10%. Step 3: Oxidation smelting. The granulated material is mixed with 5-10mm coal granules and then added to the side-blown furnace. The 5-10mm coal granules account for 6%-8% of the material weight. Oxygen-enriched air is introduced for oxidation smelting. The dust-containing flue gas produced is sent to acid production after waste heat recovery and dust collection. The lead-zinc oxide melt produced is sent to reduction smelting. Step 4: Reduction smelting. The desulfurized lead-zinc oxide melt is added to a side-blown furnace, along with 5-10mm granular coal, which accounts for 12%-14% of the weight of the lead-zinc oxide melt. Oxygen-enriched air with a concentration of 45-55 vol% is introduced for reduction smelting, producing reduction flue gas. The composition of the reduction flue gas is Zn: 10-15 vol%, CO: 8-12 vol%, and CO2: 20-26 vol%. Producer water gas is added to the upper space of the furnace, and the volume ratio of furnace gas (H2+CO) / CO2 is controlled at 1.5-2.0. The zinc-containing steam produced is sent to the lead rain condenser, and the reduction slag is sent to the fuming furnace for blowing. The reduction produces crude lead, which is further refined to remove impurities. Step 5: Fuming. The reducing slag enters the fuming furnace, and pulverized coal is injected into the furnace for fuming and smelting. The pulverized coal accounts for 18%-20% of the weight of the reducing slag. Step Six: Condensation and Separation. The zinc-containing vapor produced from the reduction side-blown furnace enters the lead rain condenser for cooling. The condensing medium is molten lead. The molten lead captures the zinc vapor to form a lead-zinc liquid, which enters the separation system. The furnace gas is burned to recover the calorific value. The lead and zinc are clarified and separated based on their different specific gravities. Step 7: Distillation. The crude zinc liquid condensed and separated from the lead rain condenser enters the distillation furnace.

[0006] Furthermore, in step one, the lead-zinc mixed materials consist of dust and slag, and the flux includes limestone, quartz, iron filings, or iron sulfides.

[0007] Furthermore, in step three, the oxygen concentration of the oxygen-enriched air is 70-80 vol%, the controlled temperature of the oxidative smelting is 1200-1250℃, and the time is 2-2.5h.

[0008] Furthermore, in step four, the reduction smelting temperature is controlled at 1250-1300℃, and the time is 2-2.5h.

[0009] Furthermore, in step four, the producer water gas is a mixed gas generated by reacting solid fuel coal with a gasifying agent and steam under high temperature conditions. The volume percentage of the producer water gas is 40-60 vol% of the reducing flue gas, and the composition of the producer water gas is H2: 40% - 50 vol%, CO: 30% - 40 vol%, CO2: 5% - 10 vol%, and the temperature is 600-700℃.

[0010] Furthermore, in step five, the controlled temperature for fuming blowing is 1250-1300℃, and the time is 2-2.5h.

[0011] Furthermore, in step five, the dust-laden flue gas produced is sent to the flue gas treatment system after being collected by waste heat utilization, the zinc oxide obtained from the dust collection is returned to the batching, and the produced slag is sold after water quenching.

[0012] Furthermore, in step six, the lower layer of lead liquid is returned to the lead rain condenser for recycling, and 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 water vapor to 100-120℃.

[0013] Furthermore, in step seven, the distillation furnace includes a lead tower and a cadmium tower. Zinc liquid flows into the lead tower, and at a temperature of 750-850°C, most of the zinc and the cadmium it contains evaporate in a vapor state, while lead and other high-boiling-point impurities are discharged and separated as liquid alloys. The cadmium-containing zinc produced by the lead tower is introduced into the cadmium tower through a sluice box, and zinc-cadmium separation is carried out at a temperature of 800-900°C. Pure zinc liquid enters the pure zinc tank from the bottom, thus obtaining distilled zinc.

[0014] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. By adopting steady-state reduction control technology, producer water gas is added to the upper space of the reduction side-blown furnace, and the volume ratio of furnace gas (H2+CO) / CO2 is controlled at 1.5-2.0. The oxygen-enriched air can be completely burned, avoiding the possibility of zinc vapor generating zinc oxide. 2. For lead-zinc mixtures, including lead concentrate, zinc concentrate, lead-zinc mixed ore, and lead-zinc mixed materials, the proportion of ingredients is precisely controlled. The Pb / Zn weight ratio is 0.4-0.6, the total lead and zinc content is 30%-60%, and the sulfur content of the mixture is 18%-24%. This ensures the adaptability of the smelting process to different materials and improves the recovery rate of lead and zinc. 3. Lead rain condensers are suitable for fluctuating zinc vapor concentrations in furnace gas, can handle large volumes of furnace gas, and can be used for large-scale industrial production. 4. A side-blown furnace is used to smelt lead and zinc. Zinc is recovered by steam volatilization and condensation, while lead is recovered in liquid form. Lead and zinc are recovered simultaneously in the same furnace, with a lead recovery rate of >97% and a zinc recovery rate of >95%. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1This is a process flow diagram of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] The gas used in this invention is a mixed gas generated by reacting solid fuel coal with a gasifying agent and steam under high temperature conditions. Its main components are as follows: H2: 40-50 vol%, CO: 30-40 vol%, CO2: 5-10 vol%.

[0019] The apparatus used in this invention includes: a batching silo, 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 distillation furnace.

[0020] Example 1: Please refer to Figure 1 This invention provides a method for redox smelting of lead-zinc materials, comprising the following steps: Step 1: Batching. Lead and zinc materials and flux are batched through a batching silo. The lead and zinc materials include lead concentrate, zinc concentrate, lead-zinc mixed ore, and lead-zinc mixed materials. The flux includes limestone, quartz, iron filings, or iron sulfides. The required Pb / Zn weight ratio is 0.4-0.6, the total lead and zinc content is 30%-60%, and the sulfur content of the mixed material is 18%-24%. Step 2: Granulation. The prepared mixture is fed into a cylindrical granulator for mixing and granulation. The particle size of the granulated material is 8-10mm, and the moisture content is 8%-10%. Step 3: Oxidation smelting. The granulated material is mixed with 5mm coal granules and then added to a side-blown furnace. The 5mm coal granules account for 6% of the material weight. Oxidation smelting is carried out by introducing oxygen-enriched air with a concentration of 70 vol%. The temperature is controlled at 1200℃ and the time is 2 hours. The dust-containing flue gas produced is sent to acid production after waste heat recovery and dust collection. The lead-zinc oxide melt produced is sent to reduction smelting. Step 4: Reduction smelting. The desulfurized lead-zinc oxide melt is added to a side-blown furnace, along with 5mm coal granules, which account for 12% of the weight of the lead-zinc oxide melt. 45 vol% oxygen-enriched air is introduced for reduction smelting, with the temperature controlled at 1250℃ for 2 hours, producing reduction flue gas. The composition of the reduction flue gas is Zn: 10-15 vol%, CO: 8-12 vol%, and CO2: 20-26 vol%. Producer water gas is added to the upper space of the furnace at 600℃, accounting for 40 vol% of the reduction flue gas volume. The volume ratio of furnace gas (H2+CO) / CO2 is controlled at 1.5-2.0. The zinc-containing steam produced is sent to a lead rain condenser, and the reduction slag is sent to a fuming furnace for blowing. The crude lead produced from the reduction process is recovered and further refined to remove impurities. Step 5: Fuming. The reducing slag is fed into the fuming furnace, and pulverized coal is injected into the furnace for fuming and blowing. The pulverized coal accounts for 18% of the mass of the reducing slag. The temperature is controlled at 1250℃ for 2 hours. The dust-containing flue gas produced is sent to the flue gas treatment system after waste heat utilization and dust collection. The zinc oxide obtained from dust collection is returned to the batching. The produced slag is water quenched. Step 6: Condensation and separation. Zinc vapor is introduced into the lead rain condenser for cooling. The condensing medium is molten lead. The molten lead captures the zinc vapor to form a lead-zinc liquid, which enters the separation system. Lead and zinc are separated by their different specific gravities. The lower layer of molten lead is returned to the lead rain condenser for recycling, while the upper layer of molten zinc enters the zinc storage tank to produce crude zinc liquid. The high-temperature molten lead in the separation system is cooled by 100°C using water vapor. Step 7: Distillation. The separated crude zinc liquid is fed into a distillation furnace for distillation. The distillation furnace includes a lead column and a cadmium column. The zinc liquid flows into the lead column, where most of the zinc and the cadmium it contains evaporates in vapor form at 750°C. The lead and other high-boiling-point impurities are discharged as liquid alloys and separated. The cadmium-containing zinc produced in the lead column is introduced into the cadmium column through a sluice. Zinc and cadmium are separated at 800°C. The pure zinc liquid enters the pure zinc tank from the bottom, thus obtaining distilled zinc.

[0021] Example 2: The lead-zinc material had a Pb / Zn weight ratio of 0.6, a total lead and zinc content of 32%, and a sulfur content of 19%. It was subjected to oxidation-reduction smelting according to the steps described in Example 1. The resulting reduction flue gas had the following composition: Zn: 9 vol%, CO: 10 vol%, CO2: 22 vol%. Producer water gas with the following composition was added to the upper space of the reduction furnace: H2: 45 vol%, CO: 35 vol%, CO2: 8 vol%, resulting in a mixed furnace gas (H2+CO) / CO2 volume ratio of 1.7. The zinc-containing steam furnace gas entered the lead rain condenser to recover zinc, reducing to produce crude lead. The resulting reduction slag was then fed into a fuming furnace for smelting. The final lead recovery rate was 97.2%, and the zinc recovery rate was 95.6%.

[0022] Example 3: The lead-zinc material had a Pb / Zn weight ratio of 0.5, a total lead and zinc content of 45%, and a sulfur content of 21%. It was subjected to oxidation-reduction smelting according to the steps described in Example 1. The resulting reduction flue gas had the following composition: Zn: 10 vol%, CO: 9 vol%, CO2: 23 vol%. Producer water gas with the following composition was added to the upper space of the reduction furnace: H2: 48 vol%, CO: 34 vol%, CO2: 9 vol%, resulting in a mixed furnace gas (H2+CO) / CO2 volume ratio of 1.6. The zinc-containing steam furnace gas entered the lead rain condenser to recover zinc, reducing to produce crude lead. The resulting reduction slag was then sent to a fuming furnace for smelting. The final lead recovery rate was 97.8%, and the zinc recovery rate was 96.1%.

[0023] Example 4: The lead-zinc material had a Pb / Zn weight ratio of 0.4, a total lead and zinc content of 56%, and a sulfur content of 23%. It was subjected to oxidation-reduction smelting according to the steps described in Example 1. The resulting reduction flue gas had the following composition: Zn: 11 vol%, CO: 8 vol%, CO2: 24 vol%. Producer water gas with the following composition was added to the upper space of the reduction furnace: H2: 44 vol%, CO: 40 vol%, CO2: 7 vol%, resulting in a mixed furnace gas (H2+CO) / CO2 volume ratio of 1.6. The zinc-containing steam furnace gas entered the lead rain condenser to recover zinc, reducing to produce crude lead. The resulting reduction slag was then fed into a fuming furnace for smelting. The final lead recovery rate was 98.1%, and the zinc recovery rate was 96.8%.

[0024] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for redox smelting of lead-zinc materials, characterized in that, Includes the following steps: Step 1: Batching. The lead and zinc materials are batched with the flux in the batching silo. The lead and zinc materials include lead concentrate, zinc concentrate, lead-zinc mixed ore, and lead-zinc mixed materials. The required Pb / Zn weight ratio is 0.4-0.6, the total lead and zinc content is 30%-60%, and the sulfur content of the mixed material is 18%-24%. Step 2: Granulation. Add the prepared mixture into a cylindrical pellet mill for mixing and granulation. The particle size of the granulated material should be 8-10mm, and the moisture content should be 8%-10%. Step 3: Oxidation smelting. The granulated material is mixed with 5-10mm coal granules and then added to the side-blown furnace. The 5-10mm coal granules account for 6%-8% of the material weight. Oxygen-enriched air is introduced for oxidation smelting. The dust-containing flue gas produced is sent to acid production after waste heat recovery and dust collection. The lead-zinc oxide melt produced is sent to reduction smelting. Step 4: Reduction smelting. The desulfurized lead-zinc oxide melt is added to a side-blown furnace, along with 5-10mm granular coal, which accounts for 12%-14% of the weight of the lead-zinc oxide melt. Oxygen-enriched air with a concentration of 45-55 vol% is introduced for reduction smelting, producing reduction flue gas. The composition of the reduction flue gas is Zn: 10-15 vol%, CO: 8-12 vol%, and CO2: 20-26 vol%. Producer water gas is added to the upper space of the furnace, and the volume ratio of furnace gas (H2+CO) / CO2 is controlled at 1.5-2.

0. The zinc-containing steam produced is sent to the lead rain condenser, and the reduction slag is sent to the fuming furnace for blowing. The reduction produces crude lead, which is further refined to remove impurities. Step 5: Fuming. The reducing slag enters the fuming furnace, and pulverized coal is injected into the furnace for fuming and smelting. The pulverized coal accounts for 18%-20% of the weight of the reducing slag. Step Six: Condensation and Separation. The zinc-containing vapor produced from the reduction side-blown furnace enters the lead rain condenser for cooling. The condensing medium is molten lead. The molten lead captures the zinc vapor to form a lead-zinc liquid, which enters the separation system. The furnace gas is burned to recover the calorific value. The lead and zinc are clarified and separated based on their different specific gravities. Step 7: Distillation. The crude zinc liquid condensed and separated from the lead rain condenser enters the distillation furnace.

2. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step one, the lead-zinc mixed materials consist of dust and slag, and the flux includes limestone, quartz, iron filings or iron sulfides.

3. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step three, the oxygen concentration of the oxygen-enriched air is 70-80 vol%, the controlled temperature of the oxidative smelting is 1200-1250℃, and the time is 2-2.5h.

4. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step four, the reduction smelting temperature is controlled at 1250-1300℃, and the time is 2-2.5h.

5. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step four, the producer water gas is a mixed gas generated by reacting solid fuel coal with a gasifying agent and steam under high temperature conditions. The volume ratio of the producer water gas is 40-60 vol% of the reducing flue gas. The composition of the producer water gas is H2: 40%-50 vol%, CO: 30%-40 vol%, CO2: 5%-10 vol%, and the temperature is 600-700℃.

6. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step five, the controlled temperature for fumigation blowing is 1250-1300℃, and the time is 2-2.5h.

7. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step five, the dust-laden flue gas produced is sent to the flue gas treatment system after being collected by waste heat utilization. The zinc oxide obtained from the dust collection is returned to the batching process, and the produced slag is sold after water quenching.

8. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step six, the lower layer of lead liquid is returned to the lead rain condenser for recycling, while 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 water vapor to 100-120℃.

9. The method for redox smelting of lead-zinc materials according to claim 1, characterized in that: In step seven, the distillation furnace includes a lead tower and a cadmium tower. Zinc liquid flows into the lead tower, and at a temperature of 750-850°C, most of the zinc and the cadmium it contains evaporate in vapor form, while lead and other high-boiling-point impurities are discharged and separated as liquid alloys. The cadmium-containing zinc produced by the lead tower is introduced into the cadmium tower through a sluice box, and zinc-cadmium separation is carried out at a temperature of 800-900°C. Pure zinc liquid enters the pure zinc tank from the bottom, thus obtaining distilled zinc.

Images