A method for harmless resource utilization of zinc oxide leaching residue

Abstract

This invention discloses a method for the harmless resource utilization of zinc oxide leaching residue. First, the zinc oxide leaching residue undergoes low-temperature arsenic removal to obtain white arsenic and arsenic-removed leaching residue. Then, the arsenic-removed leaching residue is subjected to low-acid washing to remove cadmium, yielding a cadmium solution and cadmium-removed leaching residue. The cadmium solution is then subjected to a zinc powder displacement reaction to obtain sponge cadmium. The cadmium-removed leaching residue is subjected to sulfidation-grinding treatment for extraction of valuable components (zinc and lead). Chemical flotation yields lead-zinc concentrate (containing arsenic and cadmium) and tailings (containing arsenic and cadmium). The lead-zinc concentrate and tailings are then subjected to low-temperature arsenic removal to obtain white arsenic, arsenic-removed lead-zinc concentrate, and arsenic-removed tailings. The arsenic-removed lead-zinc concentrate and tailings are then subjected to low-acid washing to remove cadmium, yielding a cadmium solution, cadmium-removed lead-zinc concentrate, and cadmium-removed tailings (harmless tailings). The cadmium solution is then subjected to a zinc powder displacement reaction to obtain sponge cadmium. Ultimately, this method achieves effective lead and zinc recovery and harmless tailings disposal.

Description

Technical Field

[0001] This invention relates to a method for the harmless and resource-based utilization of zinc oxide leaching residue, belonging to the fields of mineral processing and metallurgical technology. Background Technology

[0002] In recent years, with the increasing level of national economic development, the accelerated pace of market industrialization, and the rapid development of emerging industries such as new energy vehicles, the demand for lead and zinc smelting products in my country has been expanding. The lead and zinc smelting industry has entered a period of rapid development, with the production volume of lead and zinc smelters continuously increasing. China has become a global center for lead and zinc production and consumption, ranking first in the world in both production and consumption for many consecutive years. Data from the National Bureau of Statistics shows that in 2023, my country's lead and zinc production were 7.564 million tons and 7.152 million tons, respectively, representing year-on-year growth rates of 17.73% and 11.32%. In 2023, the national zinc concentrate production was 4.06 million tons, a year-on-year increase of 0.5%. According to customs data, China imported 4.713 million tons of zinc concentrate in 2023, a year-on-year increase of 14.6%, bringing the total zinc concentrate imports to 8.773 million tons.

[0003] Zinc and lead smelting technologies are mainly classified into two categories: pyrometallurgical and hydrometallurgical processes. Hydrometallurgical smelting is the primary method for zinc and lead smelting today, and currently, hydrometallurgical zinc production accounts for more than 80% of my country's total zinc production. The hydrometallurgical leaching process mainly produces a mixture of zinc sulfate solution and insoluble residue. When the leaching reaction reaches its endpoint, solid-liquid separation is required. The resulting solid residue is the leaching residue, which falls under the category of HW48 non-ferrous metal smelting hazardous waste in the National Hazardous Waste List (2021 edition), specifically the leaching residue produced by conventional leaching methods for zinc roasted ore and zinc oxide ore during lead-zinc smelting (item 321-004-48). Statistics show that the production of each ton of zinc generates an average of 0.85 to 1.0 tons of leaching residue, which is a large amount. The residue mainly contains zinc and other valuable metal elements, such as rare and precious metals like indium, germanium, gold, and silver, as well as heavy metals like copper, lead, cadmium, arsenic, and mercury. The zinc content in the leaching residue produced by conventional hydrometallurgical processes ranges from 1% to 10%. The resource value and environmental hazards are intertwined, and how to properly utilize and dispose of the leaching residue has become an urgent problem for lead and zinc smelting enterprises.

[0004] Currently, the utilization of leaching residue mainly relies on pyrometallurgical methods, employing side-blown furnaces for reduction smelting to recover lead and zinc, or rotary kilns for volatilization recovery of zinc. These methods consume enormous amounts of reducing agents and energy, resulting in high costs and making them unsuitable for the comprehensive utilization of leaching residue with low zinc content. Furthermore, they generate significant amounts of greenhouse gases. Simultaneously, the byproduct of water-quenched slag is substantial, and its recovery efficiency for non-volatile metals such as silver is poor, hindering the effective harmless and resource-based utilization of leaching residue. Since high-value precious and rare metals such as silver, indium, gallium, and germanium have low grades in leaching residue, achieving their full recovery and utilization is currently subject to significant technological and economic limitations.

[0005] Against the backdrop of comprehensively advancing carbon peaking and carbon neutrality, building a beautiful China, deepening the battle against pollution, accelerating the construction of a waste recycling system, and promoting the comprehensive green transformation of economic and social development, the harmless and resource-based utilization of leaching residue is of great significance for improving the environment, alleviating resource shortages, and implementing the sustainable development strategy. In recent years, the harmless and resource-based utilization of leaching residue has become a research hotspot both domestically and internationally. Developing utilization technologies with high comprehensive recovery rates and economic reliability is currently the focus of leaching residue treatment and disposal. However, most current leaching residue treatment technologies struggle to simultaneously achieve harmlessness and resource utilization, failing to meet the national requirements for pollution reduction and carbon reduction. Therefore, there is an urgent need to develop and construct a technology that balances the harmlessness and resource utilization of leaching residue. Summary of the Invention

[0006] The purpose of this invention is to provide a method for the harmless and resource-based utilization of zinc oxide leaching residue. By performing beneficiation and smelting combined treatment on the zinc oxide leaching residue, following the process of low-temperature arsenic removal, low-acid cadmium removal, flotation enrichment and recovery of lead and zinc, low-temperature arsenic removal, and low-acid cadmium removal, valuable metals such as lead and zinc in the zinc oxide leaching residue can be effectively recovered, and the tailings can be safely disposed of in landfills as general tailings, thereby achieving the purpose of harmlessness and resource utilization.

[0007] The technical solution of this invention is as follows: First, the zinc oxide leaching residue is subjected to low-temperature arsenic removal to obtain white arsenic and arsenic-removed leaching residue. Then, utilizing the critical pH difference in the solubility of zinc, lead, and cadmium in acid, the arsenic-removed leaching residue is subjected to low-acid washing to remove cadmium (i.e., under acidic conditions of pH < 6.7, cadmium exists in the solution as cadmium ions; zinc ions begin to hydrolyze to form zinc hydroxide precipitate when the pH rises to around 5.2. Therefore, strictly controlling the acid washing pH above 5.2 ensures that most of the zinc remains in solid form in the concentrate, while cadmium is preferentially dissolved into the liquid phase, thus achieving the purpose of "washing cadmium and preserving zinc"; under conditions of pH > 5.2, lead elements... The lead cannot dissolve, ensuring maximum enrichment of lead. A cadmium solution and cadmium-removed leaching residue are obtained. The cadmium solution undergoes a zinc powder displacement reaction to produce sponge cadmium. The cadmium-removed leaching residue is then subjected to sulfidation-grinding treatment to extract valuable components (zinc and lead). Chemical flotation yields lead-zinc concentrate (containing arsenic and cadmium) and tailings (containing arsenic and cadmium). The lead-zinc concentrate and tailings undergo low-temperature arsenic removal to obtain white arsenic, arsenic-removed lead-zinc concentrate, and arsenic-removed tailings. The arsenic-removed lead-zinc concentrate and tailings undergo low-acid washing to remove cadmium, yielding a cadmium solution, cadmium-removed lead-zinc concentrate, and cadmium-removed tailings (harmless tailings). The cadmium solution undergoes a zinc powder displacement reaction to produce sponge cadmium. Ultimately, this process achieves effective lead and zinc recovery and harmless tailings disposal.

[0008] A method for the harmless and resource-based utilization of zinc oxide leaching residue, comprising the following specific steps: (1) Low-temperature arsenic removal: The zinc oxide leaching residue is subjected to low-temperature arsenic removal to obtain white arsenic and arsenic-removed leaching residue: (2) Low acid cadmium removal: The arsenic removal leaching residue obtained in step (1) is subjected to low acid washing to remove cadmium. The acid washing pH is 5.2~6.7 to obtain cadmium solution and cadmium removal leaching residue. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction. (3) Flotation enrichment and recovery of lead and zinc: The cadmium-de-leaching residue is subjected to sulfidation-grinding treatment and then floated to obtain arsenic-cadmium-containing lead and zinc concentrate and arsenic-cadmium-containing tailings; (4) Low-temperature arsenic removal: The arsenic-containing cadmium lead-zinc concentrate and arsenic-containing cadmium tailings obtained in step (3) are subjected to low-temperature arsenic removal to obtain white arsenic, arsenic-removed lead-zinc concentrate and arsenic-removed tailings. (5) Low acid cadmium removal: The arsenic-removed lead-zinc concentrate and arsenic-removed tailings from step (4) are subjected to low acid cadmium removal to obtain cadmium solution, cadmium-removed lead-zinc concentrate and cadmium-removed tailings. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction.

[0009] The temperature for low-temperature arsenic removal in steps (1) and (5) is 300~600℃.

[0010] Steps (2) and (5) The pH value of the low-acid cleaning solution for removing cadmium is 5.2~6.7.

[0011] The grinding process in step (3) involves grinding the cadmium-depleted leaching residue to a mass of -0.074 mm, which accounts for 75-85%.

[0012] The cadmium-degraded leaching residue from step (3) is subjected to sulfidation. The sulfidation agent is sodium sulfide, and the dosage is 3000g / t~5000g / t.

[0013] The chemical flotation in step (3) involves two roughing and two cleaning processes. In the first roughing process, 10-30 g / t of a combined collector (a combination of butyl xanthate, ethyl thiocyanate, and butylamine black) and 5-15 g / t of frother pine oil are added sequentially. In the second roughing process, 5-15 g / t of the combined collector and 5-15 g / t of frother pine oil are added sequentially. In the first cleaning process, 5-15 g / t of the combined collector is added. No reagents are added in the second cleaning process.

[0014] The beneficial effects of this invention are: (1) This invention makes effective resource utilization of zinc oxide leaching residue, which not only yields lead, zinc concentrate, white arsenic, and sponge cadmium, but also achieves the purpose of harmlessness after the tailings are dearsenic and cadmium removed, and can be safely landfilled as general tailings, thus achieving the purpose of harmlessness and resource utilization.

[0015] (2) Through the combined process of beneficiation and smelting, the present invention achieves a removal rate of over 95% for arsenic and over 95% for cadmium in zinc oxide leaching residue, and a recovery rate of about 75% for lead and zinc, with good effects in removing arsenic, cadmium and recovering valuable metals.

[0016] (3) The process of this invention is simple, the amount of reagents used is small, it does not pollute the environment, it is green and environmentally friendly, the resource utilization rate is high, and the application prospects are broad. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] Example 1: A method for the harmless and resource-based utilization of zinc oxide leaching residue, such as... Figure 1 As shown, the specific steps are as follows: (1) Low-temperature arsenic removal: The zinc oxide leaching residue is subjected to arsenic removal at 300℃ to obtain white arsenic and arsenic-removed leaching residue; (2) Low acid cadmium removal: The arsenic removal leaching residue obtained in step (1) is subjected to low acid cleaning to remove cadmium. The pH value of the cleaning solution is controlled to be 5.5 to obtain cadmium solution and cadmium removal leaching residue. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction. (3) Flotation enrichment and recovery of lead and zinc: The cadmium-depleted leaching residue from step (2) is subjected to sulfidation-grinding treatment and ground to 75% by mass of -0.074mm. The amount of sodium sulfide added during sulfidation is 3000g / t. Then flotation is carried out, with two roughing and two cleaning processes. In the first roughing process, 10g / t of combined collector and 5g / t of frother pine oil are added sequentially. In the second roughing process, 5g / t of combined collector and 5g / t of frother pine oil are added sequentially. In the first cleaning process, 5g / t of combined collector is added. No reagents are added in the second cleaning process. The combined collector is a combination of butyl xanthate, ethyl thiocyanate and butylamine black (combination ratio 2:1:1) to obtain arsenic-cadmium lead-zinc concentrate and arsenic-cadmium tailings. (4) Low-temperature arsenic removal: The arsenic-containing cadmium lead-zinc concentrate and arsenic-containing cadmium tailings obtained in step (3) are subjected to arsenic removal treatment at 300℃ to obtain white arsenic, arsenic-removed lead-zinc concentrate and arsenic-removed tailings. (5) Low acid cadmium removal: The arsenic-removed lead-zinc concentrate and arsenic-removed tailings obtained in step (5) are subjected to low acid washing to remove cadmium. The pH value of the washing solution is controlled at 5.5 to obtain cadmium solution, cadmium-removed lead-zinc concentrate and cadmium-removed tailings (harmless tailings). The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction.

[0020] The results of this embodiment are shown in Tables 1 and 2 below. After this harmless and resource-based treatment, the recovery rates of valuable metals lead and zinc concentrates in the zinc oxide leaching residue were 65.35% and 63.81%, respectively. The arsenic removal rates in steps (1) and (4) were 90.12% and 95.33%, respectively, which showed good results.

[0021] Table 1

[0022] Table 2

[0023] Example 2: A method for the harmless and resource-based utilization of zinc oxide leaching residue, such as... Figure 1 As shown, the specific steps are as follows: (1) Low-temperature arsenic removal: The zinc oxide leaching residue was subjected to arsenic removal at 450℃ to obtain white arsenic and arsenic-removed leaching residue; (2) Low acid cadmium removal: The arsenic removal leaching residue obtained in step (1) is subjected to low acid cleaning to remove cadmium. The pH value of the cleaning solution is controlled to be 5.3 to obtain cadmium solution and cadmium removal leaching residue. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction. (3) Flotation enrichment and recovery of lead and zinc: The cadmium-depleted leaching residue from step (2) is subjected to sulfidation-grinding treatment until 80% of the residue is -0.074 mm by mass. The amount of sodium sulfide added during sulfidation is 4000 g / t. Then, flotation is carried out, with two roughing and two cleaning processes. In the first roughing process, 20 g / t of combined collector and 10 g / t of frother pine oil are added sequentially. In the second roughing process, 10 g / t of combined collector and 6 g / t of frother pine oil are added sequentially. In the first cleaning process, 6 g / t of combined collector is added. No reagents are added in the second cleaning process. The combined collectors are all combinations of butyl xanthate, ethyl thiocyanate and butylamine black (combination ratio 2:1:1), to obtain arsenic-cadmium lead-zinc concentrate and arsenic-cadmium tailings. (4) Low-temperature arsenic removal: The arsenic-containing cadmium lead-zinc concentrate and arsenic-containing cadmium tailings obtained in step (3) are subjected to arsenic removal treatment at 450℃ to obtain white arsenic, arsenic-removed lead-zinc concentrate and arsenic-removed tailings. (5) Low acid cadmium removal: The arsenic-removed lead-zinc concentrate and arsenic-removed tailings obtained in step (5) are respectively subjected to low acid washing to remove cadmium. The pH value of the washing solution is controlled to be 5.3 to obtain cadmium solution, cadmium-removed lead-zinc concentrate and cadmium-removed tailings (harmless tailings). The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction.

[0024] The results of this embodiment are shown in Tables 1 and 2 below. After this harmless and resource-based treatment, the recovery rates of valuable metals lead and zinc concentrates in the zinc oxide leaching residue were 73.61% and 70.12%, respectively. The removal rates of arsenic and cadmium in steps (1) and (5) were 98.53% and 98.15%, respectively, which showed good results.

[0025] Table 1

[0026] Table 2

[0027] Example 3: A method for the harmless and resource-based utilization of zinc oxide leaching residue, such as... Figure 1 As shown, the specific steps are as follows: (1) Low-temperature arsenic removal: The zinc oxide leaching residue was subjected to arsenic removal at 600℃ to obtain white arsenic and arsenic-removed leaching residue; (2) Low acid cadmium removal: The arsenic removal leaching residue obtained in step (1) is subjected to low acid cleaning to remove cadmium. The pH value of the cleaning solution is controlled to be 6.7 to obtain cadmium solution and cadmium removal leaching residue. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction. (3) Flotation enrichment and recovery of lead and zinc: The cadmium-depleted leaching residue from step (2) is subjected to sulfidation-grinding treatment until 85% of the residue is -0.074 mm by mass. The amount of sodium sulfide added during sulfidation is 5000 g / t. Then, flotation is carried out, with two roughing and two cleaning processes. In the first roughing process, 30 g / t of combined collector and 15 g / t of frother pine oil are added sequentially. In the second roughing process, 15 g / t of combined collector and 15 g / t of frother pine oil are added sequentially. In the first cleaning process, 15 g / t of combined collector is added. No reagents are added in the second cleaning process. The combined collectors are all combinations of butyl xanthate, ethyl thiocyanate and butylamine black (combination ratio 2:1:1). Arsenic-cadmium-containing lead and zinc concentrate and arsenic-cadmium-containing tailings are obtained. (4) Low-temperature arsenic removal: The arsenic-containing cadmium lead-zinc concentrate and arsenic-containing cadmium tailings obtained in step (3) are subjected to arsenic removal treatment at 600℃ to obtain white arsenic, arsenic-removed lead-zinc concentrate and arsenic-removed tailings. (5) Low acid cadmium removal: The arsenic-removed lead-zinc concentrate and arsenic-removed tailings obtained in step (5) are subjected to low acid washing to remove cadmium. The pH value of the washing solution is controlled at 6.7 to obtain cadmium solution, cadmium-removed lead-zinc concentrate and cadmium-removed tailings (harmless tailings). The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction.

[0028] The results of this embodiment are shown in Tables 1 and 2 below. After this harmless and resource-based treatment, the recovery rates of valuable metals lead and zinc concentrates in the zinc oxide leaching residue were 75.19% and 73.86%, respectively. The removal rates of arsenic and cadmium in steps (1) and (5) were 99.72% and 93.13%, respectively, which showed good results.

[0029] Table 1

[0030] Table 2

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for harmless resource utilization of zinc oxide leaching residue, characterized in that Follow these steps: (1) Low-temperature arsenic removal: The zinc oxide leaching residue is subjected to low-temperature arsenic removal to obtain white arsenic and arsenic-removed leaching residue: (2) Low acid cadmium removal: The arsenic removal leaching residue obtained in step (1) is subjected to low acid washing to remove cadmium. The acid washing pH is 5.2~6.7 to obtain cadmium solution and cadmium removal leaching residue. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction. (3) Flotation enrichment and recovery of lead and zinc: The cadmium-de-leaching residue is subjected to sulfidation-grinding treatment and then floated to obtain arsenic-cadmium-containing lead and zinc concentrate and arsenic-cadmium-containing tailings; (4) Low-temperature arsenic removal: The arsenic-containing cadmium lead-zinc concentrate and arsenic-containing cadmium tailings obtained in step (3) are subjected to low-temperature arsenic removal to obtain white arsenic, arsenic-removed lead-zinc concentrate and arsenic-removed tailings. (5) Low acid cadmium removal: The arsenic-removed lead-zinc concentrate and arsenic-removed tailings from step (4) are subjected to low acid cadmium removal to obtain cadmium solution, cadmium-removed lead-zinc concentrate and cadmium-removed tailings. The cadmium solution is used to obtain sponge cadmium through zinc powder replacement reaction.

2. The method for harmless resource utilization of zinc oxide leaching residue according to claim 1, characterized in that: The temperature for low-temperature arsenic removal in steps (1) and (5) is 300~600℃.

3. The method for harmless resource utilization of zinc oxide leaching residue according to claim 1, characterized in that: Step (5) The pH value of the low-acid cleaning solution for removing cadmium is 5.2~6.

7.

4. The method for harmless and resource-based utilization of zinc oxide leaching residue according to claim 1, characterized in that: The grinding process in step (3) involves grinding the cadmium-depleted leaching residue to a mass of -0.074 mm, which accounts for 75-85%.

5. The method for harmless and resource-based utilization of zinc oxide leaching residue according to claim 1, characterized in that: In step (3), the sulfidation agent is sodium sulfide, and the dosage is 3000g / t~5000g / t.

6. The method for harmless and resource-based utilization of zinc oxide leaching residue according to claim 1, characterized in that: Step (3) flotation includes two roughing and two cleaning processes. In the first roughing process, 10-30 g / t of combined collector and 5-15 g / t of frother pine oil are added sequentially. In the second roughing process, 5-15 g / t of combined collector and 5-15 g / t of frother pine oil are added sequentially. In the first cleaning process, 5-15 g / t of combined collector is added. No reagents are added in the second cleaning process. The combined collector is a combination of butyl xanthate, ethyl thiocyanate and butylamine black.

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