Method for realizing deep enrichment of secondary zinc oxide in reduction smelting furnace

Abstract

This invention provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace. High-zinc, high-lead slag is added to the reduction smelting furnace for a reduction smelting reaction. Stone powder is added from the feed inlet. The method is achieved by controlling the molten pool temperature, slag shape, and coal-oxygen ratio, producing reduction slag and crude lead. The reduction slag is then fed into a fuming furnace for zinc extraction. Zinc vapor generated during the reduction smelting process is discharged from the furnace's exhaust port and enters a dust collection system where it is oxidized into secondary zinc oxide dust, achieving deep enrichment of secondary zinc oxide. This invention avoids the formation of low-grade zinc-containing ash from the high-lead slag, which is then returned to the oxidation smelting furnace. This reduces the amount of ash circulating in the oxidation-reduction system, accelerates production, reduces energy consumption, and lowers processing costs. Simultaneously, it increases the zinc content of the feed material to the oxidation furnace, maximizing zinc recovery.

Description

Technical Field

[0001] This invention relates to the field of metal smelting technology, and specifically to a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace. Background Technology

[0002] Currently, methods for enriching zinc oxide from zinc-rich, high-lead slag often involve reduction smelting to obtain liquid zinc-rich reducing slag and flue dust. The reducing slag is then processed in a fuming furnace to extract zinc, producing zinc oxide as a byproduct. The flue dust is returned and properly mixed with other materials in an oxidation smelting furnace to regenerate zinc-rich, high-lead slag. The drawback of this method is that while some zinc is generated in the reduction smelting process, the zinc content in the flue dust is low, making direct zinc recovery impossible. The ash must be returned to the oxidation furnace for further smelting to generate zinc-rich, high-lead slag, which is then subjected to reduction smelting again. This process is repeated, resulting in high energy consumption and processing costs. Summary of the Invention

[0003] To address the problem of low zinc content in the flue dust obtained from existing reduction smelting processes, which prevents direct zinc recovery and necessitates reprocessing in an oxidation furnace, leading to high energy consumption, this invention provides a method for deep enrichment of secondary zinc oxide in a reduction smelting furnace. By controlling the molten pool temperature, coal-oxygen ratio, and slag type within the furnace, the resulting products are reduction slag, crude lead, and zinc vapor. The zinc vapor is discharged from the furnace's flue outlet and enters a dust collection system where it is oxidized into secondary zinc oxide flue dust, achieving deep enrichment of secondary zinc oxide. This invention avoids the conversion of zinc from high-lead zinc slag obtained from oxidation smelting into low-grade zinc-containing flue dust that needs to be returned to the oxidation smelting furnace, reducing flue dust recycling, accelerating production, reducing energy consumption, lowering processing costs, increasing the zinc content of the feed material, maximizing zinc recovery, and simultaneously reducing the lead content in the reduction slag, thus improving lead metal recovery.

[0004] The present invention adopts the following technical solution: A method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace includes the following steps: The zinc-rich, high-lead slag obtained from oxidation smelting is added to a reduction smelting furnace for reduction smelting. Stone powder is added to the reduction smelting furnace, and pulverized coal and oxygen are introduced. By controlling the temperature of the molten pool, the coal-oxygen ratio, and the slag shape in the reduction smelting furnace, after smelting for 2 hours, reduction slag, crude lead, and zinc vapor are obtained. The reduction slag is discharged from the slag outlet of the reduction smelting furnace, and the crude lead is discharged from the lead outlet of the reduction smelting furnace. The zinc vapor generated during the smelting process is discharged from the flue gas outlet of the reduction smelting furnace and enters the dust collection system to be oxidized into secondary zinc oxide flue gas, thereby achieving deep enrichment of secondary zinc oxide. The molten pool temperature is 1250–1350℃, and the coal-oxygen ratio is 1.2–1.7. By controlling the molten pool temperature and the coal-oxygen ratio, the reducing atmosphere in the furnace is controlled, creating fuming conditions that facilitate the enrichment of zinc in the flue ash. The amount of stone powder added is 0.5-2% of the mass of zinc-rich lead slag, in order to control the slag type of the reducing slag to a calcium-silicon ratio of 0.5-0.7, ensuring a high calcium content in the slag, which is conducive to the volatilization of zinc.

[0005] Furthermore, the zinc-containing high-lead slag is a product of the oxidation smelting process, and the lead content in the zinc-containing high-lead slag is 30% to 43% and the zinc content is 6% to 18%; the slag type of the zinc-containing high-lead slag is an iron-silicon ratio of 1.7 to 2.8 and a calcium-silicon ratio of 0.2 to 0.4.

[0006] Furthermore, multiple end-wall spray guns are added to the end wall of the reduction smelting furnace to introduce natural gas and oxygen as a supplement to adjust the furnace temperature and slag fluidity. The outlet end of the end-wall spray gun is inserted into the slag layer, and natural gas and oxygen are directly introduced into the slag layer. The natural gas consumption is 15-30 Nm³ / h, and the oxygen consumption is 50-90 Nm³ / h.

[0007] Furthermore, the amount of pulverized coal added is 5.4-6.8% of the mass of zinc-containing high-lead slag, and the amount of oxygen added is 43-57 Nm³ / t.

[0008] Furthermore, the reduction smelting furnace includes a reaction zone and a slag-lead separation zone. The oxygen lance pressure enables zone control of the reaction zone and the slag-lead separation zone, thereby controlling the reaction atmosphere and slag-lead separation within the furnace. The reaction zone occupies approximately three-fifths of the furnace body. The oxygen lance pressure in the reaction zone is 0.7–0.8 MPa to ensure sufficient reaction, while the oxygen lance pressure in the slag-lead separation zone is 0.5–0.6 MPa to ensure sufficient slag-lead separation and reduce lead loss in the reduction slag.

[0009] Furthermore, the zinc oxide flue dust contains 20-35% lead and 55-65% zinc oxide.

[0010] Furthermore, the lead content in the reducing slag is 1-1.48%, and the zinc content is 11-15%.

[0011] Compared with the prior art, the present invention has the following technical effects: 1. This invention provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, increasing the weight percentage of zinc oxide in flue dust from 40%–54% to 55%–65%, reaching the level of secondary zinc oxide. This allows for direct zinc extraction in the next process without needing to return the material to the oxidation smelting process as raw material. Consequently, the effective feed rate of the oxidation smelting process is significantly improved, and the overall processing capacity of raw materials (i.e., lead- and high-zinc materials) in the oxidation smelting process increases by 5–10%, resulting in significant economic benefits. Furthermore, it reduces the zinc content in the reduction slag from 17%–20% to 11%–15%, decreasing the zinc content in the reduction slag entering the fuming furnace, laying the foundation for energy conservation and consumption reduction in the fuming furnace, and lowering the processing cost per ton by 15–20%.

[0012] 2. This invention further optimizes the control of the temperature and slag shape of the reduction smelting pool, effectively controls the presence of lead inclusions in the reduction slag produced in the reduction smelting furnace, and optimizes the coal-oxygen ratio to further enhance the reducing atmosphere in order to ensure the formation of fuming conditions in the reduction smelting furnace, thereby improving the reaction effect and ensuring that the lead content of the reduction slag is less than 1.48% at the current reaction time. Detailed Implementation

[0013] The present invention will be further described below with reference to specific embodiments.

[0014] Example 1 This embodiment provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, comprising the following steps: Zinc-rich high-lead slag obtained from oxidation smelting (by weight, the zinc-rich high-lead slag contains 35.5% lead, 13.2% zinc, 17.65% FeO, 9.41% SiO2, and 3.52% CaO) is fed into the reduction smelting furnace through the slag inlet at a rate of 40t. Simultaneously, 320kg of stone powder is added through the discharge port of the reduction smelting furnace. During the smelting process, the temperature inside the reduction smelting furnace is controlled at 1300℃. During the process, pulverized coal (with a weight percentage of ash, volatile matter, sulfur, and fixed carbon of 10.21%, 8.54%, 0.45%, and 78.54% respectively) and oxygen (98% concentration) are blown into the slag pool of the reduction smelting furnace from the bottom using oxygen lances to carry out the reduction reaction. The oxygen lance pressure in the reaction zone is controlled at 0.75 MPa, and the oxygen lance pressure in the slag-lead separation zone is controlled at 0.54 MPa. The coal-oxygen ratio is controlled at 1.27, the pulverized coal consumption is 2300 kg / (40t high-zinc, zinc-containing, high-lead slag), and the total oxygen supply is 1800 Nm³. 3 (40t high-zinc, high-lead slag) was blown in, and natural gas and oxygen were introduced into the slag layer through the end-wall spray gun. The natural gas consumption was 20 Nm³ / h, and the oxygen consumption was 60 Nm³ / h. The material was smelted in the reduction smelting furnace for 2 hours. After smelting, the reducing slag was discharged from the slag outlet of the reduction smelting furnace (the calcium-silicon ratio was tested to be 0.58, and the weight percentage of lead in the reducing slag was 1.46% and the weight percentage of zinc was 14.21%). 13.8t of crude lead was discharged from the lead outlet of the reduction smelting furnace. The zinc vapor generated during the smelting process was discharged from the flue gas outlet of the reduction smelting furnace and entered the dust collection system to be oxidized into secondary zinc oxide dust (the weight percentage of lead and zinc oxide in the secondary zinc oxide was tested to be 21.21% and 61.35%, respectively).

[0015] Example 2 This embodiment provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, comprising the following steps: High-zinc, high-lead zinc slag (by weight percentage, the high-zinc, high-lead zinc slag contains 35.6% lead, 12.6% zinc, 15.86% FeO, 8.24% SiO2, and 3.34% CaO) is fed into the reduction smelting furnace through the slag inlet at a rate of 44 tons. Simultaneously, 240 kg of stone powder is added through the furnace outlet. During the smelting process, the temperature inside the reduction smelting furnace is controlled at 1310°C. During the process, pulverized coal (with a weight percentage of ash, volatile matter, sulfur, and fixed carbon of 10.21%, 8.54%, 0.45%, and 78.54% respectively) and oxygen (98% concentration) are blown into the slag pool of the reduction smelting furnace using oxygen lances from the bottom of the furnace for reduction reaction. The oxygen lance pressure in the reaction zone is controlled at 0.72 MPa, and the oxygen lance pressure in the slag-lead separation zone is controlled at 0.56 MPa. The coal-oxygen ratio is controlled at 1.42. The pulverized coal consumption is 3000 kg / (44t high-zinc, zinc-containing, high-lead slag) and the oxygen quantity is 2100 Nm³. 3 (44t high-zinc, high-lead slag) was blown in, and natural gas and oxygen were introduced into the slag layer through the end-wall spray gun. The natural gas consumption was 21 Nm³ / h, and the oxygen consumption was 62 Nm³ / h. The material was smelted in the reduction smelting furnace for 2 hours. After smelting, the reducing slag was discharged from the slag outlet of the reduction smelting furnace (the calcium-silicon ratio was tested to be 0.56, and the weight percentage of lead in the reducing slag was 1.42% and the weight percentage of zinc was 13.31%). 13.8t of crude lead was discharged from the lead outlet of the reduction smelting furnace. The zinc vapor generated during the smelting process was discharged from the flue gas outlet of the reduction smelting furnace and entered the dust collection system to be oxidized into secondary zinc oxide dust (the weight percentage of lead and zinc oxide in the secondary zinc oxide was tested to be 25.36% and 66.42%, respectively).

[0016] Example 3 This embodiment provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, comprising the following steps: High-zinc, high-lead slag (by weight, the high-zinc, high-lead slag contains 38.34% lead, 13.7% zinc, 14.65% FeO, 7.87% SiO2, and 3.04% CaO) is fed into the reduction smelting furnace through the slag inlet at a rate of 42t. Simultaneously, 240kg of stone powder is added through the furnace outlet. During the smelting process, the temperature inside the reduction smelting furnace is controlled at 1300℃. During the process, pulverized coal (with a weight percentage of ash, volatile matter, sulfur, and fixed carbon of 10.21%, 8.54%, 0.45%, and 78.54% respectively) and oxygen (98% concentration) are blown into the slag pool of the reduction smelting furnace using oxygen lances from the bottom of the furnace for reduction reaction. The oxygen lance pressure in the reaction zone is controlled at 0.72 MPa, and the oxygen lance pressure in the slag-lead separation zone is controlled at 0.58 MPa. The coal-oxygen ratio is controlled at 1.23. The pulverized coal consumption is 2600 kg / (42t high-zinc, zinc-containing, high-lead slag), and the oxygen consumption is 2100 Nm³. 3 (42t high-zinc, high-lead slag) was blown in, and natural gas and oxygen were introduced into the slag layer through the end-wall spray gun. The natural gas consumption was 21 Nm³ / h, and the oxygen consumption was 62 Nm³ / h. The material was smelted in the reduction smelting furnace for 2 hours. After smelting, the reducing slag was discharged from the slag outlet of the reduction smelting furnace (the calcium-silicon ratio was tested to be 0.61, and the weight percentage of lead and zinc in the reducing slag was 1.34% and 13.67%, respectively). 13.8t of crude lead was discharged from the lead outlet of the reduction smelting furnace. The zinc vapor generated during the smelting process was discharged from the flue gas outlet of the reduction smelting furnace and entered the dust collection system to be oxidized into secondary zinc oxide dust (the weight percentage of lead and zinc oxide in the secondary zinc oxide was tested to be 24.35% and 67.24%, respectively).

[0017] Comparative Example 1 This embodiment provides a method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, comprising the following steps: High-zinc, high-lead slag (by weight, the high-zinc, high-lead slag contains 34.3% lead, 11.8% zinc, 16.52% FeO, 8.54% SiO2, and 3.24% CaO) is fed into the reduction smelting furnace through the slag inlet at a rate of 40 tons. Simultaneously, 120 kg of stone powder is added through the furnace outlet. During the smelting process, the temperature inside the reduction smelting furnace is controlled at 1320°C. During the process, pulverized coal (with ash, volatile matter, sulfur, and fixed carbon weight percentages of 10.21%, 8.54%, 0.45%, and 78.54%, respectively) and oxygen (98% concentration) are blown into the slag pool of the reduction smelting furnace from the bottom using oxygen lances for reduction reaction. The oxygen lance pressure in the reaction zone and the slag-lead separation zone are both controlled at 0.72 MPa, with a coal-oxygen ratio of 1.14. The pulverized coal consumption is 2400 kg / (40t high-zinc, zinc-containing, high-lead slag) and the oxygen consumption is 2100 Nm³ / min. 3 (40t high-zinc, high-lead slag) was blown in, and natural gas and oxygen were introduced into the slag layer through the end-wall spray gun. The natural gas consumption was 22 Nm³ / h, and the oxygen consumption was 64 Nm³ / h. The material was smelted in the reduction smelting furnace for 2 hours. After smelting, the reducing slag was discharged from the slag outlet of the reduction smelting furnace (the calcium-silicon ratio was tested to be 0.42, and the weight percentage of lead and zinc in the reducing slag was 2.32% and 16.54%, respectively). 13.2t of crude lead was discharged from the lead outlet of the reduction smelting furnace. The zinc vapor generated during the smelting process was discharged from the flue gas outlet of the reduction smelting furnace and entered the dust collection system to be oxidized into secondary zinc oxide dust (the weight percentage of lead and zinc oxide in the secondary zinc oxide was tested to be 38.21% and 47.52%, respectively).

[0018] As can be seen from Comparative Example 1, the proportion of 120 kg of stone powder added at the feed port was 0.3% (stone powder / zinc-high lead slag), which was too low. The calcium-silicon ratio of the reduction slag was also too low at 0.42, resulting in excessively low calcium content in the slag, which was not conducive to zinc volatilization. The weight percentages of lead and zinc oxide in the secondary zinc oxide were 38.21% and 47.52%, respectively, with the lead content being too high and the zinc oxide content being too low. At the same time, the oxygen lance pressure was controlled at 0.72 MPa in both the east and west zones without zone control, resulting in poor slag-lead separation. The weight percentage of lead in the reduction slag was too high at 2.32%, and the lead loss was significant.

[0019] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made to the principles and process conditions of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace, characterized in that, Includes the following steps: Zinc-rich lead slag is added to a reduction smelting furnace for reduction smelting. Stone powder is added to the reduction smelting furnace, and pulverized coal and oxygen are introduced. By controlling the temperature of the molten pool, the coal-oxygen ratio and the slag shape in the reduction smelting furnace, reduction slag, crude lead and zinc vapor are obtained after smelting. The zinc vapor is discharged from the flue of the reduction smelting furnace and enters the dust collection system to be oxidized into secondary zinc oxide flue ash. The molten pool temperature is 1250–1350℃, and the coal-oxygen ratio is 1.2–1.7; the amount of stone powder added is 0.5–2% of the mass of the zinc-high lead slag, so as to control the slag type of the reducing slag to a calcium-silicon ratio of 0.5–0.7; The zinc-rich high-lead slag is a product of the oxidation smelting process, with a lead content of 30%–43% and a zinc content of 6%–18%. The slag type of the zinc-rich high-lead slag is an iron-silicon ratio of 1.7–2.8 and a calcium-silicon ratio of 0.2–0.

4. The reduction smelting furnace includes a reaction zone and a slag-lead separation zone. The oxygen lance pressure in the reaction zone is 0.7–0.8 MPa, and the oxygen lance pressure in the slag-lead separation zone is 0.5–0.6 MPa.

2. The method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace according to claim 1, characterized in that, Multiple end-wall spray guns are added to the end wall near the slag outlet of the reduction smelting furnace. Natural gas and oxygen are introduced into the slag layer through the end-wall spray guns. The natural gas consumption is 15-30 Nm³ / h and the oxygen consumption is 50-90 Nm³ / h.

3. The method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace according to claim 1, characterized in that, The amount of pulverized coal added is 5.4-6.8% of the mass of zinc-containing high-lead slag, and the amount of oxygen added is 43-57 Nm³ / t.

4. The method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace according to claim 1, characterized in that, The zinc oxide flue dust contains 20-35% lead and 55-65% zinc oxide.

5. The method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace according to claim 1, characterized in that, The reducing slag contains 1-1.48% lead and 11-15% zinc.

6. The method for achieving deep enrichment of secondary zinc oxide in a reduction smelting furnace according to claim 1, characterized in that, The reduction smelting time is 2 hours.