EA038200B1 - Method and system for extracting zinc from low-grade lead-zinc ore - Google Patents

Abstract

The invention provides a method and a system for extracting zinc from low-grade lead-zinc ore. The device used in the method comprises a reduction smelting device and a dust collecting device, which are mutually connected, wherein the total content of a lead element and a zinc element in low-grade lead-zinc ores is less than 20 wt.%, and the zinc element and the lead element are is the form of zinc silicate, zinc carbonate, zinc sulfide, lead carbonate and lead sulfide, wherein the method comprises performing a reduction and smelting reaction on the low-grade lead-zinc ore, reducing fuel and white lead ore to obtain zinc oxide smoke and lead-containing slag. The use of the low-grade lead-zinc ore provides lower cost. Zinc sulfide and lead oxide have a redox reaction, and zinc is enriched in the form of a high-grade zinc oxide smoke, thereby zinc and lead are effectively separated from raw ores.

Description

Technology area

The present invention relates to the field of metallurgy and, in particular, to a method and system for the extraction of zinc from low-grade lead-zinc ore.

State of the art

Lead-zinc mineral resources are abundant in China. In terms of production capacity, consumption and export in general, they occupy leading positions in the world. It is a promising type of mineral in China. China's zinc reserves are the third largest in the world after Australia and the United States, accounting for 10.7% of the world's zinc reserves. China's lead reserves are the second largest in the world after Australia, accounting for 12.5% of the world's lead reserves. General characteristics of lead-zinc mineral resources in China: fewer high-grade ores, but more numerous low-grade ores, fewer coarse-grained ores, but numerous fine- and medium-grained ores, more associated elements, complex and difficult-to-mine ores. Most deposits are usually associated with elements such as Cu, Fe, Ag, Au, Sn, Sb, Mo, W, Hg, Co, Cd, In, Ga, Se, Ti, and Sc. Some deposits contain more than 50 types of accompanying elements. With the depletion of zinc sulphide and lead sulphide reserves in China, processing and disposal of low-grade lead-zinc oxide ores has been put on the agenda.

The lead and zinc content of low-grade lead-zinc oxide ores is usually less than 20%. Zinc is mainly present in the form of zinc silicate, zinc carbonate and zinc sulfide. Lead is mainly present in the form of lead carbonate and lead sulphide. The gangue minerals are mainly calcite, dolomite, quartz and iron oxide. The extraction of zinc metal and lead metal from inexpensive lead-zinc oxide ores is currently the focus of researchers around the world.

The known method of separation of poor lead-zinc oxide ores with a high oxidation rate. First, the lean lead-zinc oxide ores are crushed at a high oxidation rate. Secondly, for flotation, a vulcanizing agent, a manifold and a regulator are added to obtain the lead-zinc mixed concentrate I and sieve material. Thirdly, lead and zinc are separated in the material passed through the sieve using a cationic amine collector to obtain a lead-zinc mixed concentrate II and tailings. Finally, the lead-zinc blended concentrate I and the lead-zinc blended concentrate II are mixed to obtain a lead concentrate and a zinc concentrate by gravity separation.

Another document discloses a direct smelting process for the simultaneous production of lead metal and zinc metal. Lead-zinc concentrate, lead-zinc oxide ore or lead and zinc containing secondary material is mixed with a solvent, granulated and smelted in an oxygen-enriched side-blast furnace to produce blister lead and slag with a high zinc content, with the blister lead being vented through the inlet siphon, and slag with a high zinc content enters the smoke zone. Coal is added to the smoke zone to reduce zinc, oxygen-enriched air is introduced, and zinc vapor is obtained during the reduction. Then, a lead-zinc solution is obtained in a capacitor, and crude zinc is obtained by cooling liquid zinc and liquid lead.

To date, little research has been done on flare smelting of low grade lead-zinc oxide ores in China and other countries. Flotation or hydrometallurgy is used to separate and enrich elemental lead and zinc during smelting. Low grade lead zinc oxide ore, which occurs in the form of zinc silicate, zinc carbonate, zinc sulfide, lead carbonate and lead sulfide, is usually difficult to separate by flotation or hydrometallurgy.

Brief description of the invention

The main objective of the present invention is to provide a method and system for recovering zinc from low grade lead-zinc ore in order to solve the current problem that low grade lead-zinc oxide ores that occur in the form of zinc silicate, zinc carbonate, sulfide zinc, lead carbonate and lead sulfide are difficult to separate by flotation or hydrometallurgy.

To achieve the above object, the present invention provides a method for recovering zinc from low-grade lead-zinc ores, in which the device used in the method includes a smelter reduction device and a dust collector connected to each other, while the total content of lead and zinc in low-grade lead-zinc ore is less than 20 wt.%, and zinc and lead are present in the form of zinc silicate, zinc carbonate, zinc sulfide, lead carbonate and lead sulfide, and the method includes conducting a smelting reduction reaction with low-grade lead-zinc ore, reducing fuel and cerussite to obtain fine zinc oxide and lead-containing slag.

In addition, the melt reduction temperature is 1000 to 1300 ° C, and the reaction time is 0.5 to 2 hours; preferably, the melt reduction temperature is 1100 to 1300 ° C, and the reaction time is 0.5 to 1 hour; preferably the smelting reduction process is carried out at a programmed temperature.

- 1 038200

Further, the programmed temperature method includes heating the reaction material of the smelting reduction process to the smelting reduction temperature at a rate of 5 to

15 ° C / min; holding the reaction material at the melting reduction temperature for from

0.5 to 2 hours; cooling the reaction material to room temperature at a rate of 5 to

15 ° C / min.

In addition, the smelting reduction apparatus is a rotary kiln, and the smelting reduction process is carried out in a rotary kiln; preferably, the rotary kiln has a rotation speed of 0.3 to 1.5 rpm and the rotary kiln has an inclination of 2 to 8 ° with respect to the horizontal plane; more preferably, the inclination of the rotary kiln relative to the horizontal plane is 4-6 °.

In addition, the smelting reduction device is a vacuum smelting reduction device, and the method includes performing a smelting reduction process with low grade lead-zinc ore, reducing fuel and cerussite in a vacuum smelting reduction device to produce zinc metal and lead-containing slag; preferably, the degree of vacuum in the smelting reduction process is 1 to 200 Pa, the reaction temperature is 900 to 1200 ° C, and the reaction time is 0.5 to 2 hours; more preferably, the degree of vacuum in the smelting reduction process is 1 to 100 Pa, the reaction temperature is 1100 to 1200 ° C, and the reaction time is 1 to 2 hours.

In addition, before the smelting reduction process, the method further includes grinding and pressing a mixture of low-grade lead-zinc ore, reducing fuel and cerussite sequentially to obtain a billet and performing a smelting reduction reaction of the billet to obtain metallic zinc and lead-containing slag; preferably the grinding process includes the step of grinding the mixture in a ball mill, more preferably the ball mill has a rotation speed of 100 to 600 rpm and a grinding time of 2 to 10 hours; preferably the pressing process includes the step of pressing the mixture under a pressure of 150 to 250 MPa.

In addition, the device used in the method also includes a cooling device, and after performing the smelting reduction process, the method further includes using a cooling device to cool the gaseous product obtained in the smelting reduction reaction to produce zinc metal; preferably, the device used in the method further includes a waste heat recovery device located in the flow path between the vacuum smelting reduction device and the cooling device, and the method also includes using the waste heat recovery device to recover waste heat of the gaseous product obtained in the smelting reduction reaction, and then cooling the gaseous product subjected to the waste heat recovery step with a cooling device to produce zinc metal.

In addition, the molar ratio of zinc sulfide to lead carbonate in a mixture of low-grade lead-zinc ore, reducing fuel and cerussite is 1: (0.5-2); preferably, the molar ratio of zinc sulfide to lead carbonate in the mixture of low grade lead-zinc ore, reducing fuel and cerussite is 1: (0.8-1.2); preferably, the reducing fuel is selected from one or more materials from the group consisting of charcoal, activated carbon, graphite, petroleum coke, coal and soot; preferably more than 90 wt% elemental zinc in the low grade lead zinc ore is in the form of zinc silicate, zinc carbonate or zinc sulfide, and more than 90 wt% elemental lead is in the form of lead carbonate and / or lead sulfide.

In yet another aspect of the present invention, there is also provided a system for recovering zinc from low grade lead-zinc ores, including a cerussite feed device, a smelter reduction device, and a dust collector. The cerussite feeding device is provided with an opening for cerussite feeding; the smelting reduction device is provided with a feed hole and an outlet for the reduction product, and the feed hole is connected to the cerussite feed hole. The dust collector is provided with a flue gas extraction port, the flue gas extraction port is connected to the reduction product outlet through the reduction product supply line.

In addition, the system further includes a low grade lead-zinc ore feeder and a reducing fuel feeder. The low-grade lead-zinc ore feed device is provided with a feed port for low-grade lead-zinc ore, and the feed port for low-grade lead-zinc ore is connected to the feed port. The reducing fuel supply device is provided with an opening for supplying the reducing fuel, and the reducing fuel supply opening is connected to the supply opening.

In addition, the system further includes a crushing and sifting device provided with an inlet for the material to be sieved and an outlet for the material to be sieved. The inlet for the screened material is respectively connected to the cerussite feed port, the low grade lead-zinc ore feed port and the reducing fuel feed port, and the outlet for

- 2,038,200 of the material to be sieved is connected to the feed hole; preferably, the system further includes a temperature monitoring device for monitoring the temperature of the smelting reduction device in real time; preferably, the system further includes a waste heat recovery device located on the reduced product feed line.

In addition, the system further includes a compression device located on the feed line between the crushing and screening device and the smelting reduction device.

In addition, the smelting reduction apparatus is a rotary kiln; preferably, the lower surface of the combustion chamber of the smelting reduction device has an inclination of 2 ° to 8 ° with respect to the horizontal plane; more preferably, the lower surface of the combustion chamber of the smelting reduction device has an inclination of 4 ° to 6 ° with respect to the horizontal plane.

In addition, the system further includes an evacuating device connected to the reduction product outlet for providing a vacuum environment in the smelting reduction device; preferably, the system further includes a cooling device located on the zinc vapor feed line between the reduction product outlet and the evacuation device, and the cooling device is configured to solidify the zinc vapor removed from the smelting reduction device.

Compared with other raw materials for producing zinc metal and lead metal, the low-grade lead-zinc oxide ore used in the present invention has a lower cost. Therefore, the application of the technical solution of the present invention is beneficial for the use and development of low-grade lead-zinc oxide ore in China. In the smelting reduction process, a redox reaction is carried out between zinc sulfide and lead oxide of the starting materials. Elemental zinc in low-grade lead-zinc oxide ores is beneficiated and separated as high-grade fine zinc oxide, whereby elemental zinc and lead are effectively separated from the raw ores. In addition, the high-grade fine zinc oxide and lead sulfide-rich furnace slag obtained in the present invention can also be used to produce zinc metal and lead metal, and the method can improve the efficiency of using raw materials. In conclusion, it should be noted that the above recovery method improves the separation efficiency of elemental lead and zinc from low-grade lead-zinc ores, thereby increasing the economic benefit.

Brief Description of Drawings

The drawings, as part of the specification, are used to provide a further understanding of the description of the invention; the schematic embodiments of the invention and their description are used to illustrate the essence of the invention, and they are not intended to unduly limit the invention. In the drawings:

in fig. 1 is a schematic diagram of a system for recovering zinc from low grade lead-zinc ores in accordance with a typical embodiment of the present invention;

in fig. 2 is a schematic diagram of a system for recovering zinc from low grade lead-zinc ores in accordance with a preferred embodiment of the present invention.

The above drawings include the following conventions:

10: cerussite feeding device; 11: hole for feeding cerussite; 20: smelting reduction device; 21: feed hole; 22: recovery product exit; 30: dust collector; 31: opening for flue gas extraction; 40: low grade lead-zinc ore feeder; 41: feed port for low grade lead-zinc ore; 50: grinding and sieving device; 51: inlet for screened material; 52: sieved material outlet; 60: waste heat recovery device; 70: reducing fuel supply device; 71: opening for the supply of reducing fuel; 80: pressing device; 90: evacuation device; 91: cooling device.

Detailed description of incarnations

It should be noted that the embodiments in the description of the invention and the features in the embodiments may be mutually combined as long as they do not contradict each other. In the description of the invention, a detailed explanation is presented with reference to the drawings in combination with the following embodiments.

As described in the Background section, existing low grade lead zinc oxide ores that occur in the form of zinc silicate, zinc carbonate, zinc sulfide, lead carbonate and lead sulfide are difficult to separate by flotation or hydrometallurgy. To solve this problem, in a typical embodiment of the present invention, there is provided a method for recovering zinc from low-grade lead-zinc ores, in which the apparatus used in the method includes a smelter reduction device and a dust collector connected to each other, with the total content of lead and zinc in low-grade lead - zinc ore is less than 20 wt.%, and

- 3,038,200 zinc and lead are in the form of zinc silicate, zinc carbonate, zinc sulfide, lead carbonate and lead sulfide, the method comprising carrying out a smelting reduction reaction of low grade lead-zinc ore, reducing fuel and cerussite to produce zinc oxide and lead-containing slag.

During the reduction and smelting process, zinc carbonate and lead carbonate in the material are first decomposed to zinc oxide and lead oxide. As the reaction temperature rises, zinc oxide and zinc silicate react with the reducing fuel to form zinc vapor. The zinc vapor is collected with a dust collector and then oxidized to produce fine zinc oxide. Since the atmosphere in the smelter reduction apparatus is a highly reducing atmosphere, lead sulfide and zinc sulfide in the material are not reduced or vaporized. While the zinc oxide in the material undergoes a reduction reaction, a redox reaction occurs between lead oxide and zinc sulfide to produce lead sulfide and zinc oxide, and then the zinc oxide reacts with the reducing fuel, and finally, elemental zinc in zinc sulfide is also enriched. to fine zinc oxide collected by the dust collector.

Compared to other raw materials for producing zinc metal and lead metal, the low grade lead zinc oxide ore used in the present invention provides a lower cost, which is advantageous for the use and development of low grade lead zinc oxide ore in China. In the smelting reduction process, a redox reaction occurs between zinc sulfide and lead oxide of the starting materials. Elemental zinc in low-grade lead-zinc oxide ores is enriched and separated in the form of high-grade finely dispersed zinc oxide, while the degree of reduction and evaporation of elemental zinc from the source material is more than 98%, thereby elemental zinc and lead are effectively separated from the original ores. In addition, the high-grade lead-zinc oxide ore and lead sulfide-rich furnace slag obtained in the present invention can be further used to produce zinc metal and lead metal, and the method can improve the efficiency of using raw materials. In conclusion, it should be noted that the above recovery method improves the efficiency of separating the elements of lead and zinc from low-grade lead-zinc ores, thereby increasing the economic benefit.

The main component of cerussite is lead carbonate, with lead sometimes being partially replaced by silver or chromium.

In a preferred embodiment, the melt reduction temperature is from 1000 to 1300 ° C and the reaction time is from 0.5 to 2 hours. The melt reduction temperature includes, but is not limited to, the above range, while limiting it to the above range is advantageous in terms of increasing evaporation efficiency zinc and the rate of formation of lead sulfide. Preferably, the melt reduction temperature is 1100 to 1300 ° C and the reaction time is 0.5 to 1 hour.

To further increase the efficiency of the smelting reduction process, preferably the smelting reduction process is carried out at a programmed temperature. The programmed temperature will allow the smelting reduction process to be carried out under stabilized temperature conditions, thereby increasing the conversion of the reacted starting materials to improve the separation efficiency of elemental zinc and elemental lead.

In a preferred embodiment, the programmed temperature raising method comprises heating a melt reduction reaction system to a melt reduction temperature at a rate of 5 to 15 ° C / min and maintaining a temperature of the melt reduction reaction system at a melt reduction temperature for 0.5 to 2 hours; reducing the temperature of the smelting reduction reaction system to room temperature at a rate of 5 to 15 ° C / min.

The temperature in each temperature control section and the rate of temperature rise or fall during the temperature programmed process include, but are not limited to, the above ranges, while limiting these parameters to the above ranges has the advantage of further improving separation efficiency and elemental zinc and elemental lead conversion. thereby increasing the economic benefits of the above recovery method.

In the above reduction and smelting method, the smelting reduction process can be performed in a reduction apparatus commonly used in the art. In a preferred embodiment, the smelting reduction process is carried out in a rotary kiln. Performing the smelting reduction process in a rotary kiln offers the advantage of further increasing the smelting reduction efficiency, thereby increasing the recovery of elemental zinc and lead.

Preferably, the rotary kiln has a rotational speed of 0.3 to 1.5 rpm and the rotary kiln has an inclination of 2 to 8 degrees from the horizontal plane. The rotational speed and tilt of the rotary kiln include, but are not limited to, the above ranges, while limiting

- 4038200 of these parameters in the above ranges provides advantages in terms of increasing the efficiency of the reduction of the starting material, increasing the contact area between the low-grade lead-zinc ore and the reducing starting material, thereby also increasing the recovery of elemental zinc and lead. More preferably, the angle of inclination of the oven relative to the horizontal plane is 4-6 °.

In another preferred embodiment, the smelting reduction apparatus is a vacuum smelting reduction apparatus, and the method comprises performing a smelting reduction process with low grade lead-zinc ore, reducing fuel and cerussite in a vacuum smelting reduction apparatus to produce zinc metal and lead-containing slag.

During vacuum reduction and smelting, zinc carbonate and lead carbonate in the feed material first decompose to zinc oxide and lead oxide as the temperature rises, and then zinc oxide and zinc silicate interact with the reducing fuel to separate zinc from low-grade lead-zinc oxide ore with obtaining vapors of metallic zinc. Since the atmosphere in the vacuum smelter reduction apparatus is a highly reducing atmosphere, lead sulfide and zinc sulfide in the feed are not reduced or vaporized. The non-volatile zinc sulfide undergoes a redox reaction with the lead oxide in the feedstock to produce lead sulfide and zinc oxide, and the resulting zinc oxide undergoes a redox reaction with the reducing feedstock. Finally, elemental zinc from zinc sulfide is also separated in the form of zinc vapor.

Compared to other raw materials for producing zinc metal and lead metal, the low grade lead zinc oxide ore used in the present specification provides lower cost, which is advantageous for the use and development of low grade lead zinc oxide ore in China. By this recovery method, elemental zinc in low-grade lead-zinc oxide ores is beneficiated and separated as elemental zinc, whereby the reduction and evaporation of zinc in the starting material can reach about 99%, and at the same time a lead-containing slag is obtained. Finally, the above recovery method is effective for separating elemental lead and zinc from low grade lead-zinc ores, thereby enhancing economic benefits.

In a preferred embodiment, the vacuum degree of the smelting reduction process is 1 to 200 Pa, the reaction temperature is 900 to 1200 ° C, and the reaction time is 0.5 to 2 hours. The reaction time in the smelting reduction process, the smelting reduction temperature and the vacuum degree include the above ranges, but not limited to them, while limiting these parameters to the above ranges is advantageous in terms of the evaporation efficiency of zinc and the rate of formation of lead sulfide. More preferably, the degree of vacuum of the smelting reduction process is 1 to 100 Pa, the reaction temperature is 1100 to 1200 ° C, and the reaction time is 1 to 2 hours.

The recovery method is effective for separating elemental lead and zinc from low-grade lead-zinc ores. In a preferred embodiment, prior to smelting reduction, the method further comprises grinding and compressing a mixture of low grade lead-zinc ore, reducing fuel, and cerussite sequentially to form a billet, and performing a smelting reduction reaction of the billet to produce zinc metal and lead-containing slag.

Before smelting reduction, the raw materials are crushed and then pressed into billets, which not only improves the efficiency of smelting reduction, but also helps to reduce the formation of dust. Thus, the addition of the above stages contributes not only to an improvement in the economic parameters of the entire extraction method, but also to an increase in environmental safety.

Preferably, the grinding method includes the step of grinding the mixture with a ball mill, more preferably the ball mill has a rotation speed of 100 to 600 rpm and a grinding time of 2 to 10 hours. In the grinding process, the rotation speed and grinding time of the ball mill include the above ranges, but not limited to them, while limiting these parameters to the above ranges is advantageous in terms of reducing pressing problems. Preferably, the pressing process includes the step of pressing the mixture at a pressure of 150 to 250 MPa. The pressure during pressing includes, but is not limited to, the above range, while limiting it to the above range helps not only to compress the starting material into a predetermined shape while reducing the amount of dust, but also to improve the conversion of the workpieces in the smelting reduction process.

To facilitate the collection of the produced zinc metal, preferably the apparatus used in the above recovery method further includes a cooling device, and after the smelting reduction process, the recovery method also includes using a cooling apparatus to cool the gaseous product obtained from the smelting reduction reaction, with

- 5 038200 obtaining metallic zinc; preferably, the device used in the method further comprises a waste heat recovery device located in the flow path between the vacuum smelting reduction device and the cooling device, and the method further comprises using the waste heat recovery device to recover waste heat of the gaseous product obtained in the smelting reduction reaction, and then cooling the gaseous product that has been subjected to a waste heat recovery step with a cooling device to produce zinc metal.

Preferably, the vacuum smelting reduction apparatus is a vacuum furnace.

In a preferred embodiment, the molar ratio of zinc sulfide to lead carbonate in the mixture of low grade lead-zinc ore, reducing fuel and cerussite is 1: (0.5-2). The molar ratio of zinc sulfide to lead carbonate includes, but is not limited to, the above range, and limiting it to the above range is advantageous in terms of improving the recovery and separation efficiency of elemental zinc and lead. Preferably, the molar ratio of zinc sulfide to lead carbonate in the mixture of low grade lead zinc ore, reducing fuel and cerussite is 1: (0.8-1.2).

For the above reduction and smelting process, conventional reducing agents for the art can be selected. In a preferred embodiment, the reducing fuel includes, but is not limited to, one or more materials from the group consisting of charcoal, activated carbon, graphite, petroleum coke, coal and soot.

Preferably more than 90 wt% elemental zinc in the low grade lead zinc ore is in the form of zinc silicate, zinc carbonate or zinc sulfide, and more than 90 wt% elemental lead is in the form of lead carbonate and / or lead sulfide. The use of a material of the above composition has the advantage of further increasing the recovery of elemental zinc and lead.

In another aspect, the present invention also provides a system for recovering zinc from low grade lead-zinc ores. As shown in FIG. 1, the system includes a cerussite feeding device 10, a smelting reduction device 20, and a dust collector 30. The cerussite feeding device 10 is provided with an opening 11 for feeding cerussite; the smelting reduction device 20 is provided with a feed opening 21 and a reduction product outlet 22. The feed port 21 is connected to the cerussite feed port 11, the dust collector 30 is provided with a flue gas extraction port 31, and the flue gas extraction port 31 is connected to the reduction product outlet 22 via a reduced product feed line.

The system includes a cerussite feeding device 10, a smelting reduction device 20 and a dust collector 30. Cerussite is fed to a smelting reduction unit 20 using a cerussite feeding device 10. Subsequently, during the reduction and smelting process, zinc carbonate and lead carbonate in the material are first decomposed to zinc oxide and lead oxide. As the reaction temperature rises, zinc oxide and zinc silicate react with the reducing fuel to form zinc vapor. The zinc vapor is collected in a dust collector and then oxidized to form fine zinc oxide. Since the atmosphere in the smelter reduction apparatus 20 is a highly reducing atmosphere, lead sulfide and zinc sulfide in the material are not reduced or vaporized.

While the zinc oxide in the material undergoes a reduction reaction, a redox reaction occurs between lead oxide and zinc sulfide to produce lead sulfide and zinc oxide, and then the resulting zinc oxide reacts with the reducing fuel, and finally, the zinc in zinc sulfide is also enriched. to fine zinc oxide collected by dust collector 30. When processing low-grade lead-zinc oxide ore, the degree of evaporation of zinc from the original ore is more than 98%, and the zinc content in the resulting fine zinc oxide is more than 60 wt.%.

The recovery of zinc from low grade lead-zinc ores using a recovery system offers the advantage of increasing the efficiency of zinc recovery. In a preferred embodiment, as shown in FIG. 1, the above recovery system further comprises a low grade lead-zinc ore feeder 40 and a reducing fuel feeder 70. The low-grade lead-zinc ore feeding device 40 is provided with an opening 41 for feeding low-grade lead-zinc ore, the reducing fuel feeding device 70 is provided with an opening 71 for supplying a reducing fuel, and both openings, an opening 41 for feeding low-grade lead-zinc ore and a reducing fuel supply port 71 fuel connected to feed port 21. Providing low grade lead-zinc ore feed device 40 and reducing fuel feed device 70 will increase the automation of the recovery device, thereby reducing operator labor and allowing control of the conversion rate of the smelting reduction process by adjusting the feed rate.

Low grade lead-zinc ore feeder 40 greatly reduces labor intensity

- 6,038200 zinc extraction from low-grade lead-zinc ore. In a preferred embodiment, as shown in FIG. 1, the system further includes a grinding and sifting device 50 provided with an inlet 51 for screened material and an outlet 52 for screened material. The screening inlet 51 is respectively connected to the cerussite feed port 11 and the low grade lead-zinc ore feeder 40, and the screened material outlet 52 is connected to the feeding port 21, respectively. smelting reduction, which increases the contact area of the reacting raw materials and increases the yield of smelting reduction.

In a preferred embodiment, the system further includes a temperature monitoring device for monitoring the temperature of the smelter reduction device 20 in real time. The temperature monitoring device is installed to monitor the temperature in the smelting reduction apparatus 20 in real time, thereby providing accurate temperature control during the smelting reduction process and increasing the efficiency of reducing zinc-containing components.

In a preferred embodiment, as shown in FIG. 1, the system further includes a waste heat recovery device 60 located on the reduced product feed line. The provision of a waste heat recovery device 60 in the reduced product feed line has the advantage of increasing the energy efficiency of the overall process and improving the efficiency of converting zinc-containing vapor to fine zinc oxide.

In a preferred embodiment, as shown in FIG. 2, the retrieval system further includes a compression device 80 located in the feed line between the crushing and screening device 50 and the smelting reduction device 20. Before smelting reduction, the starting material withdrawn from the grinding and sieving device 50 is introduced into the pressing device 80, in which the starting material is pressed into billets. This not only improves the efficiency of smelting reduction, but also reduces the formation of dust. Thus, the added stages mentioned above not only improve the economic parameters of the extraction method as a whole, but also increase environmental safety.

In the above recovery system, a melter commonly used in the art can be used as the smelting reduction device 20. In a preferred embodiment, the smelting reduction apparatus 20 is a rotary kiln. The use of a rotary kiln as the smelting reduction apparatus 20 has the advantage of further improving the zinc reduction efficiency in the smelting reduction process.

The tilt angle of the lower surface of the combustion chamber of the above rotary kiln may be a conventional tilt angle in the art. In a preferred embodiment, the bottom surface of the combustion chamber of the smelting reduction apparatus 20 (rotary kiln) has an inclination of 2 ° to 8 ° with respect to the horizontal plane. The inclination of the bottom surface of the combustion chamber of the smelting reduction apparatus 20 (rotary kiln) includes, but is not limited to, the above range, while limiting it to the above range has the advantage of further improving zinc recovery efficiency.

More preferably, the bottom surface of the combustion chamber of the smelting reduction apparatus (rotary kiln) 20 has an inclination of 4 ° to 6 ° with respect to the horizontal plane. Limiting the inclination of the lower surface of the combustion chamber of the smelting reduction apparatus 20 (rotary kiln) to the above range has the advantage of further improving the zinc recovery efficiency.

In another preferred embodiment, the system further includes an evacuator 90 in communication with the reduction product outlet 22 to provide a vacuum environment to the smelter reduction device 20.

In another preferred embodiment, the recovery system further includes a cooling device 91 located in the zinc vapor feed line between the reduction product outlet 22 and the evacuation device 90, and the cooling device 91 is configured to convert the zinc vapor removed from the smelting reduction device 20 into solid condition.

The present invention is described in further detail below in connection with embodiments that should not be construed as limiting the protection scope of the present invention.

The main phase components of the lead-zinc oxide ore in examples 1-14 and comparative example 2 are dolomite (CaMg (CO ₃ ) ₂ ), sphalerite (Zn ₀ , ₇₇₆ Fe ₀ , ₂₂₄ S), calcite (CaCO ₃ ), cerussite (PbCO ₃ ) and hemimorphite ore (Zn4Si ₂ O ₇ (OH) ₂ -H ₂ O). The samples had a size of 0.074 mm, and the chemical phases of lead and zinc were investigated in the samples. In the ore, the chemical phases of lead are mainly lead carbonate and lead sulphide, which account for 74.10 and 15.47 wt.% Of the total amount of the lead phase; The chemical phases of zinc are mainly zinc carbonate, zinc silicate and zinc sulfide, which account for 28.14, 43.36 and 25.24 wt.%, respectively, of the total amount of the zinc phase. The waste rock in the samples is mainly calcite and dolomite, plus small amounts of quartz, feldspar, barite, mica and apatite, etc. The mineral composition and content of components in the ore are given in table. 1-3.

Table 1

Phase Lead sulphate Lead carbonate Lead sulphide Limonite Total lead content Lead content, wt% 0.026 3.88 0.81 0.52 5.236 Share of lead,% 0.5 74.1 15.47 9.93 100

table 2

Phase Zinc carbonate Zinc silicate Zinc sulphide Limonite Total zinc content Zinc content, wt.% 3.2 4.93 2.87 0.37 11.37 Zinc content,% 28.14 43.36 25.24 3.25 100 Mineral name Cerussite Anglesite Galena The content of the masses. % 5 0.04 0.94 Mineral name Limonite Dolomite Calcite Table 3 Content, mass. % 18.5 27.2 17.96 Hemimorphite Ore 9.09 Quartz 1.27 Smithsonite 6.69 Mica 0.97 Sphalerite 4.46 Feldspar 0.86 Pyrite 6.18 Other 0.84

(I) Direct reductive melting.

In Examples 1-8, zinc is recovered from the low grade lead-zinc ore using the recovery apparatus shown in FIG. 1.

Example 1.

Low-grade lead-zinc oxide ore, coal dust and cerussite are uniformly mixed in accordance with a mass ratio of 100: 10: 3 (the molar ratio of zinc sulfide to lead carbonate in the starting material is 1: 1.1), while the low-grade lead-zinc oxide ore contains 4 , 95 wt% S, 5.28 wt% Pb, 11.4 wt% Zn, 14.50 wt% Fe, 13.14 wt% Ca, 3.60 wt% Mg, 0.17 wt% Na, 0.14 wt% K, 0.42 wt% Al, 0.0045 wt% Ge, etc .; the fixed carbon content of the coal powder is 48.59 wt% and the lead content of cerussite is 71.11 wt%.

The mixed raw material is fed into a rotary kiln (tilt is 5 °), into which nitrogen gas is introduced at a rate of 0.8 l / min, heated to a temperature of 1200 ° C at a temperature rise rate of 5 ° C / min, and held at this temperature for 1 hour and then cooled to room temperature at a rate of 5 ° C / min, during which the rotary kiln was rotated at a speed of 0.56 rpm.

During the experiment, zinc sulfide in low-grade lead-zinc oxide ore undergoes a redox reaction with lead oxide in the feedstock to form lead sulfide and zinc oxide, and zinc silicate and zinc oxide in the feedstock undergo a reduction reaction with coal powder and vaporize to obtain zinc vapor. The zinc vapor is collected with a dust collector and the zinc vapor is re-oxidized to high grade fine zinc oxide during the collection process. After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 98.2 and 6.8%, respectively. The zinc content in the obtained fine zinc oxide is 60.5 wt%. The content of zinc and lead in the furnace slag is 0.42 and 7.58 wt%, respectively. High-grade fine zinc oxide and the resulting furnace slag can be further used to produce metallic zinc and metallic lead.

Example 2.

Low-grade lead-zinc oxide ore, coal dust and cerussite are uniformly mixed in accordance with a mass ratio of 100: 20: 5, while low-grade lead-zinc

- 8 038200 oxide ore contains 4.95 wt% S, 5.28 wt% Pb, 11.4 wt% Zn, 14.50 wt% Fe, 13.14 wt% Ca,

3.60 wt% Mg, 0.17 wt% Na, 0.14 wt% K, 0.42 wt% Al, 0.0045 wt% Ge, etc .; the fixed carbon content of the coal powder is 48.59 wt%, and the lead content of cerussite is 71.11 wt%. the molar ratio of PbCO ₃ to ZnS is 1: 0.87.

The mixed starting material is fed into a rotary kiln (tilt is 5 °), into which nitrogen gas is introduced at a rate of 0.8 l / min, heated to a temperature of 1250 ° C at a temperature rise rate of 5 ° C / min, and held at this temperature for 1 hour and then cooled to room temperature at a rate of 5 ° C / min, during which the rotary kiln was rotated at a speed of 0.56 rpm.

During the experiment, zinc sulfide in low-grade lead-zinc oxide ore undergoes a redox reaction with lead oxide in the feedstock to form lead sulfide and zinc oxide, and zinc silicate and zinc oxide in the feedstock undergo a reduction reaction with coal powder and vaporization. The zinc vapor is collected using a dust collector and the zinc vapor is re-oxidized to high grade fine zinc oxide during the collection process. After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 98.8 and 7.3%, respectively. The zinc content in the obtained fine zinc oxide is 61.2 wt%. The content of zinc and lead in the furnace slag is 0.33 and 6.68 wt%, respectively. High-grade fine zinc oxide and the resulting furnace slag can be further used to produce metallic zinc and metallic lead.

Example 3.

The difference between this example and example 1 is that the molar ratio of zinc sulfide to lead carbonate in the reacting starting material is 1: 2.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 95.9 and 9.5%, respectively. The zinc content in the obtained fine zinc oxide is 55.7 wt%. The content of zinc and lead in the furnace slag is 0.39 and 9.06 wt%, respectively.

Example 4.

The difference between this example and example 1 is that the molar ratio of zinc sulfide to lead carbonate in the reacting starting material is 1: 0.5.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 93.80 and 5.4%, respectively. The zinc content in the obtained fine zinc oxide is 53.3 wt%. The content of zinc and lead in the furnace slag is 0.94 and 9.1 wt%, respectively.

Example 5.

The difference between this example and example 1 consists in the programmed temperature method, including heating the smelting reduction reaction material to the smelting reduction temperature at a rate of 20 ° C / min and holding at the smelting reduction temperature for 1 hour; reducing the temperature of the smelting reduction reaction system to room temperature at a rate of 10 ° C / min.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 96.0 and 5.4%, respectively. The zinc content in the obtained fine zinc oxide is 55 wt%. The content of zinc and lead in the furnace slag is 0.66 and 8.23 wt%, respectively.

Example 6.

The difference between this example and example 1 is that the smelting reduction method is carried out by means of direct heating.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 95 and 8.44%, respectively. The zinc content in the obtained fine zinc oxide is 53 wt%. The content of zinc and lead in the furnace slag is 0.57 and 7.20 wt%, respectively.

Example 7.

The difference between this example and example 1 is that the temperature of the smelting reduction process is 1100 ° C and the reaction time is 1 hour.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead in the original ore is 94 and 5.2%, respectively. The zinc content in the obtained fine zinc oxide is 51 wt%. The content of zinc and lead in the furnace slag is 0.98 and 8.43 wt%, respectively.

Example 8.

The difference between this example and example 1 is that the inclination of the rotary kiln is 2 °.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 95.1 and 5.8%, respectively. The zinc content in the resulting finely dispersed

- 9 038200 zinc oxide is 53 wt.%. The content of zinc and lead in the furnace slag is 0.58 and

8.29 wt%, respectively.

Comparative example 1.

The difference between this example and example 1 is that no cerussite is added.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 80 and 2.1%, respectively. The zinc content in the obtained fine zinc oxide is 39 wt%. The content of zinc and lead in the furnace slag is 8.20 and 9.78 wt%, respectively.

From the above description, it can be seen that in the examples of the present invention, the following technical effects are achieved.

From a comparison of Example 1 and Comparative Example 1, it can be seen that the method provided herein is advantageous in terms of increasing the separation and recovery of zinc and lead from low grade lead-zinc oxide ore.

Comparing Examples 1-4, it can be seen that limiting the molar ratio of zinc sulfide to lead carbonate in the reaction feed to the preferred range of the present invention has the advantage of improving separation and recovery of zinc and lead from low grade lead zinc oxide ore.

Comparing Examples 1, 5 and 6, it can be seen that limiting the programmed temperature rise and process parameters to the preferred ranges of the present invention has the advantage of increasing the separation and recovery of zinc and lead from low grade lead zinc oxide ore.

Comparing Examples 1 and 7, it can be seen that limiting the smelting reduction temperature and time to the preferred ranges of the present invention has the advantage of increasing the separation and recovery of zinc and lead from low grade lead-zinc oxide ore.

Comparing Examples 1 and 8, it can be seen that limiting the inclination of the rotary kiln to the preferred range of the present invention has the advantage of increasing the separation and recovery of zinc and lead from low grade lead zinc oxide ore.

(II) Vacuum smelting method.

Example 9.

Low-grade lead-zinc oxide ore, activated carbon and cerussite are uniformly mixed in accordance with a mass ratio of 100: 5: 3, while the low-grade lead-zinc oxide ore contains 4.95 wt.% S, 5.28 wt.% Pb, 11.4 wt% Zn, 14.50 wt% Fe, 13.14 wt% Ca, 3.60 wt% Mg, 0.17 wt% Na, 0.14 wt% K, 0.42 wt% % Al and 0.0045 wt% Ge; the purity of the activated carbon is 97% by weight and the lead content of the cerussite is 71.11% by weight. The molar ratio of ZnS to PbCO ₃ in the starting material is 1: 0.91.

The raw materials are ground in a ball mill for 2 hours. The rotational speed of the ball mill is 350 rpm, so that the raw materials are completely and uniformly mixed. The raw materials crushed in a ball mill are pressed into cylindrical blocks using a pressing device under a pressure of 230 MPa, and the cylindrical blocks have a size of 01.8x0.5 cm.

The blocks are placed in a vacuum smelting reduction device (vacuum furnace), heated to a temperature of 1200 ° C while raising the temperature at a rate of 5 ° C / min, held at this temperature for 1 hour, and then cooled to room temperature at a rate of 5 ° C / min. while the pressure in the vacuum smelting reduction device (vacuum furnace) is maintained at 100 Pa.

During the experiment, zinc sulfide in low-grade lead-zinc oxide ore undergoes a redox reaction with lead oxide in the feedstock to form lead sulfide and zinc oxide, zinc silicate and zinc oxide in the feedstock undergo a reduction reaction with coal powder and evaporation, and zinc vapor collected using a condensation device. After separation, the degree of evaporation of zinc and lead from the original ore is 99.5 and 5.3%, respectively. The resulting zinc metal contains small amounts of lead and germanium, with a zinc content of 93.4% by weight. The content of zinc and lead in the furnace slag is 0.22 and 7.38 wt%, respectively. High purity zinc metal and the resulting furnace slag can then be used to produce zinc metal and lead metal.

Example 10.

Low-grade lead-zinc oxide ore, coal dust and cerussite are uniformly mixed in accordance with a mass ratio of 100: 10: 5, while the low-grade lead-zinc oxide ore contains 4.95 wt.% S, 5.28 wt.% Pb, 11 , 4 wt% Zn, 14.50 wt% Fe, 13.14 wt% Ca, 3.60 wt% Mg, 0.17 wt% Na, 0.14 wt% K, 0.42 wt% Al and 0.0045 wt% Ge; the purity of the activated carbon is 97% by weight and the lead content of the cerussite is 71.11% by weight. The molar ratio of ZnS to PbCO3 is 1: 1.15.

The starting materials are ground in a ball mill for 5 hours. The rotation speed of the ball

- 10,038,200 mill is 600 rpm, so that the raw materials are completely and uniformly mixed.

The raw materials crushed in a ball mill are pressed into cylindrical blocks using a pressing device under a pressure of 230 MPa, and the cylindrical blocks have a size

01.8x0.5 cm.

The blocks are placed in a vacuum smelting reduction device (vacuum furnace), heated to a temperature of 1200 ° C while raising the temperature at a rate of 5 ° C / min, held at this temperature for 1 hour, and then cooled to room temperature at a rate of 5 ° C / min. while the pressure in the vacuum smelting reduction device (vacuum furnace) is maintained at 50 Pa.

During the experiment, zinc sulfide in low-grade lead-zinc oxide ore undergoes a redox reaction with lead oxide in the feedstock to form lead sulfide and zinc oxide, zinc silicate and zinc oxide in the feedstock undergo a reduction reaction with coal powder and evaporation, and vapors zinc is collected using a condensation device. After separation, the degree of evaporation of zinc and lead from the original ore is 99.8 and 5.6%, respectively. The resulting zinc metal contains small amounts of lead and germanium, with a zinc content of 92.7% by weight. The content of zinc and lead in the furnace slag is 0.12 and 7.78 wt%, respectively. High purity zinc metal and the resulting furnace slag can then be used to produce zinc metal and lead metal.

Example 11.

The difference between this example and example 9 is that the molar ratio of zinc sulfide to lead carbonate in the reaction starting material is 1: 2.

After reduction and evaporation, the degree of evaporation of zinc and lead from the original ore is 99.7 and 7.4%, respectively. The zinc content of the resulting metallic zinc is 92.9% by weight. The content of zinc and lead in the furnace slag is 0.08 and 8.12 wt%, respectively.

Example 12.

The difference between this example and example 9 is that the molar ratio of zinc sulfide to lead carbonate in the reaction starting material is 1: 0.5.

After reduction, the degree of evaporation of zinc and lead from the original ore is 90.03 and 6.7%, respectively. The zinc content of the resulting metallic zinc is 93.5% by weight. The content of zinc and lead in the furnace slag is 0.56 and 9.1 wt%, respectively.

Example 13.

The difference between this example and example 9 is that the programmed temperature rise method includes heating the smelting reduction reaction system to the smelting reduction temperature at a rate of 20 ° C / min and holding at the smelting reduction temperature for 1 hour; reducing the temperature of the smelting reduction reaction system to room temperature at a rate of 10 ° C / min.

After reduction, the degree of evaporation of zinc and lead from the original ore is 99.1 and 6.2%, respectively. The zinc content of the resulting metallic zinc is 92.0 wt%. The content of zinc and lead in the furnace slag is 0.31 and 7.89 wt%, respectively.

Example 14.

The difference between this example and example 9 is that the smelting reduction method is carried out by means of direct heating.

After reduction, the degree of evaporation of zinc and lead from the original ore is 98.3 and 6.4%, respectively. The zinc content of the resulting metallic zinc is 90.7% by weight. The content of zinc and lead in the furnace slag is 0.38 and 8.02 wt%, respectively.

Example 15.

The difference between this example and example 9 is that the temperature of the smelting reduction process is 1000 ° C and the reaction time is 1 hour.

After reduction, the degree of evaporation of zinc and lead from the original ore is 93.88% and 5.0%, respectively. The zinc content of the resulting metallic zinc is 91.74% by weight. The content of zinc and lead in the furnace slag is 0.36 and 8.20 wt%, respectively.

Comparative example 2.

Unlike example 9, no cerussite is added, and a rotary kiln is used for reduction and evaporation.

After reduction and evaporation in a rotary kiln, the degree of evaporation of zinc and lead from the original ore is 60 and 2.1%, respectively. The zinc content in the obtained fine zinc oxide is 39 wt%. The content of zinc and lead in the furnace slag is 8.20 and 3.11 wt%, respectively.

It is evident from the above description that the following technical effects are achieved in the examples of the present invention.

From a comparison of Example 9 and Comparative Example 2, it can be seen that the method provided in the present invention is advantageous in improving the separation and recovery of zinc and lead from low grade lead-zinc oxide ore.

- 11 038200

Comparing Examples 9-13, it can be seen that limiting the molar ratio of zinc sulfide to lead carbonate in the reaction of the starting material to the preferred range of the present invention has the advantage of increasing the separation and recovery of zinc and lead in low grade lead zinc oxide ore.

Comparing Examples 9, 13 and 14, it can be seen that limiting the programmed temperature rise and process parameters to the preferred ranges of the present invention has the advantage of improving separation and recovery of zinc and lead in low grade lead zinc oxide ore.

Comparing Examples 9 and 15, it can be seen that limiting the smelting reduction temperature and time to the preferred ranges of the present invention has the advantage of increasing the separation and recovery of zinc and lead from low grade lead-zinc oxide ore.

The above is a description of only possible embodiments of the present invention and is not intended to limit the protection scope of the invention. Specialists in the art can implement the invention with various modifications and changes. Any changes, equivalent replacements, improvements, etc., which do not change the essence of the invention, fall within the protection scope of the invention.

Claims (14)

CLAIM 1. A method for extracting zinc from low-grade lead-zinc ore, characterized in that the device used in the method includes a smelting reduction device and a dust collector connected to each other, while the total content of lead and zinc in low-grade lead-zinc ores is less than 20 wt. %, and elemental zinc and lead are in the form of zinc silicate, zinc carbonate, zinc sulfide, zinc carbonate and zinc sulfide, and the method includes carrying out a smelting reduction reaction with low-grade lead-zinc ore, reducing fuel and cerussite to obtain fine zinc oxide and slag containing lead. 2. The method according to claim 1, characterized in that the melting reduction temperature is from 1000 to 1300 ° C and the reaction time is from 0.5 to 2 hours; preferably, the melt reduction temperature is 1100 to 1300 ° C and the reaction time is 0.5 to 1 hour; preferably the smelting reduction process is carried out at a programmed temperature. 3. The method according to claim 2, characterized in that the programmed temperature method includes heating the reaction material of the smelting reduction reaction to the smelting reduction temperature at a rate of 5 to 15 ° C / min; holding the reaction material at the melting reduction temperature for from 0.5 to 2 h; cooling the smelting reduction reaction system to room temperature at a rate of 5 to 15 ° C / min. 4. A method according to any one of claims 1 to 3, characterized in that the smelting reduction device is a rotary kiln and the smelting reduction process is carried out in a rotary kiln; preferably, the rotary kiln has a rotation speed of 0.3 to 1.5 rpm and the rotary kiln has an inclination of 2 to 8 ° with respect to the horizontal plane; more preferably, the inclination of the rotary kiln relative to the horizontal plane is between 4 ° and 6 °. 5. The method according to claim 1, characterized in that the smelting reduction device is a vacuum smelting reduction device, and the method includes performing a smelting reduction process with low-grade lead-zinc ore, reducing fuel and cerussite for smelting reduction to obtain metallic zinc and containing lead slag; preferably, the degree of vacuum of the smelting reduction process is 1 to 200 Pa, the reaction temperature is 900 to 1200 ° C, and the reaction time is 0.5 to 2 hours; more preferably, the degree of vacuum of the smelting reduction process is 1 to 100 Pa, the reaction temperature is 1100 to 1200 ° C, and the reaction time is 1 to 2 hours. 6. The method according to claim 4 or 5, characterized in that, before the smelting reduction process, the method further comprises grinding and pressing a mixture of low-grade lead-zinc ore, reducing fuel and cerussite sequentially to obtain a billet and carrying out a smelting reduction reaction with the billet to obtain a metal zinc and lead-containing slag; preferably the grinding process includes the step of grinding the mixture with a ball mill, more preferably the rotation speed of the ball mill is 100 to 600 rpm and the grinding time is 2 to 10 hours; preferably the pressing process includes the step of pressing the mixture under a pressure of 150 to 250 MPa. - 12 038200 7. The method according to claim 6, characterized in that the device used in the method further comprises a cooling device, and after performing the smelting reduction process, the method further comprises using a cooling device to cool the gaseous product obtained in the smelting reduction reaction to produce zinc metal ; preferably, the device used in the method further includes a waste heat recovery device located in the flow path between the vacuum smelting reduction device and the cooling device, and the method further comprises using the waste heat recovery device to recover waste heat of the gaseous product obtained in the smelting reduction reaction, and then cooling the gaseous product that has been subjected to a waste heat recovery step with a cooling device to produce zinc metal. 8. The method according to claim 1, characterized in that the molar ratio of zinc sulfide to lead carbonate in a mixture of low-grade lead-zinc ore, reducing fuel and cerussite is 1: (0.5-2); preferably, the molar ratio of zinc sulfide to lead carbonate in the mixture of low grade lead-zinc ore, reducing fuel and cerussite is 1: (0.8-1.2); preferably, the reducing fuel is selected from one or more materials selected from the group consisting of charcoal, activated carbon, graphite, petroleum coke, coal and soot; preferably more than 90 wt% elemental zinc in the low grade lead-zinc ore is in the form of zinc silicate, zinc carbonate or zinc sulfide, more than 90 wt% elemental lead is in the form of lead carbonate and / or lead sulfide. 9. A system for extracting zinc from low-grade lead-zinc ore, characterized in that it includes a cerussite supply device (10) provided with an opening (11) for cerussite supply; a smelting reduction device (20) provided with a feed opening (21) and an outlet (22) for the reduction product, the feed opening (21) being connected to the cerussite supply opening (11); a dust collector (30) provided with a flue gas extraction opening (31), the flue gas extraction opening (31) being connected to the reduction product outlet (22) through a reduction product supply line. 10. The system according to claim 9, characterized in that it further comprises a device (40) for feeding low-grade lead-zinc ore, provided with an opening (41) for feeding low-grade lead-zinc ore, and the opening (41) for feeding low-grade lead-zinc ore ore is connected to the feed hole (21); a reducing fuel supply device (70) provided with an opening (71) for supplying a reducing fuel, wherein the reducing fuel supply opening (71) is connected to the supply opening (21). 11. The system according to claim 10, characterized in that the system further comprises a grinding and sieving device (50) provided with an inlet (51) for the material to be sieved and an outlet (52) for the material to be sieved, and the inlet (51) for the material to be sieved is respectively connected with an opening (11) for supplying cerussite, an opening (41) for supplying low-grade lead-zinc ore and an opening (71) for supplying reducing fuel, and the outlet (52) for the material to be screened is connected to the supply opening (21); preferably, the system further includes a temperature monitoring device for monitoring the temperature of the smelting reduction device (20) in real time; preferably, the system further includes a waste heat recovery device (60) located on the reduced product feed line. 12. The system according to claim 11, characterized in that the system further comprises a pressing device (80) located on the feed line for the raw material, between the grinding and sieving device (50) and the smelting reduction device (20). 13. The system according to claim 9, characterized in that the smelting reduction device (20) is a rotary kiln; preferably, the lower surface of the combustion chamber of the smelting reduction device (20) has an inclination of 2 to 8 ° with respect to the horizontal plane; more preferably, the lower surface of the combustion chamber of the smelting reduction device (20) has an inclination of 4 ° to 6 ° with respect to the horizontal plane. 14. The system according to any one of claims 11-13, characterized in that the system further includes a vacuum device (90) connected to the outlet (22) for the reduction product to provide a vacuum environment in the device (20) smelting reduction; preferably, the system further includes a cooling device (91) located on the zinc vapor supply line between the reduction product outlet (22) and the evacuating device (90), and the cooling device (91) is designed to convert zinc vapor removed from the device (20) smelting reduction, into a solid state.