A method for efficient resource utilization of acidified antimony slag by directional crystallization

Abstract

The present invention discloses a method for directional crystallization and efficient resource utilization of acidified antimony slag, which relates to the technical field of solid waste resource utilization. The method subjects the acidified antimony slag produced in the process of treating raw antimony crystal salt to water slurrying, high-temperature and high-pressure directional crystallization, solid-liquid separation, water washing, drying, and crystallization steps to produce high-grade antimony concentrate and anhydrous sodium sulfate products. The method accurately achieves efficient dehydration and desalination of the acidified antimony slag through a directional crystallization process, greatly reduces the volume of the acidified antimony slag, reduces its on-site storage, and simultaneously produces high-grade antimony concentrate and anhydrous sodium sulfate products without generating secondary pollution and secondary solid waste, thereby having good economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method for efficient resource utilization of acidified antimony slag through directional crystallization. Background Art

[0002] Antimony-bearing gold concentrate typically contains 4-12% antimony and 40-70g / t gold. Due to the coexistence of antimony and gold, effective separation of antimony and gold through the grinding-flotation process is difficult. Currently, the main method for separating antimony and gold from antimony-bearing gold concentrate in China is alkaline wet leaching-electrowinning. Antimony is recovered as crude antimony or gross antimony, while gold is primarily concentrated in the alkaline leaching residue, which is used as a raw material for gold smelting.

[0003] During the alkaline wet process for treating antimony-bearing gold concentrate, a large amount of crystalline antimony salt is produced. This crystalline antimony salt, primarily composed of sodium sulfide, sodium hydrosulfide, sodium thiosulfate, and antimony sulfide, is considered solid waste and cannot be sold or stored long-term. A domestic method (ZL 2019 1 0954359.5) utilizes crystalline antimony salt by reacting it with sulfuric acid. This method can fully utilize the sulfur, antimony, and sodium elements in the crystalline antimony salt.

[0004] However, the acidified antimony slag produced by this method has problems such as high moisture content, high salt content, and difficulty in solid-liquid separation. The moisture content of the acidified antimony slag is generally 60-65%, the sodium sulfate content is 20-22%, and the antimony sulfide content is 16-20%. Since antimony sulfide mainly exists in an amorphous form, the acidified antimony slag contains high levels of free water and sodium sulfate crystals, and the acidified antimony slag is large in volume. At present, the main method for treating acidified antimony slag is to return the acidified antimony slag to the antimony workshop for recycling through the leaching process. Due to its high moisture content, it needs to be aired for a long time before returning to the antimony workshop for the leaching process. Its high salt content makes it impossible to recover it through alkaline leaching alone. It needs to be mixed with other antimony gold concentrates for treatment, which reduces the processing capacity of antimony gold concentrates in the antimony workshop. Summary of the Invention

[0005] The present invention overcomes the shortcomings of the prior art and provides a method for efficient resource utilization of acidified antimony slag through directional crystallization. Through high-temperature and high-pressure directional crystallization, solid-liquid separation, and water washing, the acidified antimony slag is efficiently dehydrated and desalted. The acidified antimony slag is simultaneously converted into high-quality antimony concentrate. Furthermore, through crystallization and drying, the sodium sulfate in the filtrate is recovered as a product.

[0006] The present invention is achieved through the following technical solution: a method for directional crystallization and efficient resource utilization of acidified antimony slag, comprising the following process steps:

[0007] (1) Add water to the acidified antimony slag to make a slurry with a slurry concentration of 40-50%, and then transfer it into a high-pressure reactor;

[0008] (2) adding an appropriate amount of clean water to the slurried acidified antimony slag, with a mass ratio of clean water to acidified antimony slag of 1 to 1.2:1, a reaction temperature of 200 to 220°C, a reaction pressure of 1.6 to 2.3 MPa, a reaction time of 2 to 6 h, and a blade speed of 100 to 150 rpm in the autoclave to achieve directional crystallization of the acidified antimony slag, and further achieve efficient solid-liquid separation and dehydration and desalination of the acidified antimony slag;

[0009] (3) The filter residue after separation contains a large amount of antimony sulfide and a small amount of sodium sulfate. The filter residue is sent for secondary water washing, and the filtrate is sent for evaporation and crystallization;

[0010] (4) During the secondary water washing process of the filter residue, the mass ratio of clean water to filter residue is controlled to be 3:1 to 5:1, the filter residue after water washing is subjected to filter pressing to produce high-grade antimony sulfide concentrate, and the washing water is returned to step (2) and step (1) for recycling;

[0011] (5) The filtrate produced in step (3) is evaporated, concentrated, and crystallized to produce sodium sulfate crystals, which are then dried to obtain anhydrous sodium sulfate product.

[0012] The main mechanisms involved in the method for efficient resource utilization of acidified antimony slag by directional crystallization described in the present invention are as follows:

[0013] Amorphous antimony sulfide (Sb2S3, Sb2S5) is transformed into shaped antimony sulfide under high temperature and high pressure. At the same time, the free water and sodium sulfate crystalline salt entrained in the acidified antimony slag are released, completing the directional crystallization and realizing the efficient separation and enrichment of antimony sulfide, sodium sulfate and water.

[0014] The beneficial effects of the present invention are:

[0015] (1) This process is simple to operate, easy to realize industrial production, and has low production costs;

[0016] (2) This process can realize the recycling of acidified antimony slag. The antimony sulfide therein is recovered in the form of high-quality antimony sulfide concentrate product. The product meets the requirements of the first-grade powder concentrate in YS / T 385-2019. It can also be used as a raw material for the production of fireworks and firecrackers (the technical indicators meet the requirements of the first-grade product in GBT 26197-2010). The crystalline salt therein is recovered in the form of anhydrous sodium sulfate product. The product meets the Class I requirements in GB / T 6009-2003.

[0017] (3) This process has a high level of resource utilization. Antimony and sodium salt are both discharged as products, without the generation of general solid waste and hazardous waste. It also avoids the use of sulfuric acid and the generation of hydrogen sulfide gas in the existing method. At the same time, the process has a high dehydration rate. After the acidified antimony slag is treated by this process, the volume of the acidified antimony slag is reduced by more than 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0020] The element analysis of acidified antimony slag is as follows:

[0021] materials Moisture (%) S（%） Sb (%) Na (%) O（%） Acidified antimony slag 61.37 12.00 15.52 4.52 6.30

[0022] A certain amount of acidified antimony slag is stirred and slurried at a wet weight liquid-to-solid ratio of 2:1; after slurrying, it is transferred to an autoclave for reaction, and the reaction temperature is controlled at 200°C, the reaction pressure is 1.8 MPa, the reaction time is 3 hours, and the stirring speed is 120 rpm. After the reaction, solid-liquid separation is performed; the filter residue is washed with water, and the clean water and the filter residue are washed twice with water at a wet weight liquid-to-solid ratio of 3:1. After washing, liquid-solid separation is performed, and the washing water can be returned to the slurrying and autoclave for use. After washing, the filter residue becomes high-quality antimony concentrate and can be sold externally; the filtrate is evaporated, concentrated, crystallized, and dried to obtain a white sodium sulfate powder with a sodium sulfate content of 99.62%. Example 2

[0023] The element analysis of acidified antimony slag is as follows:

[0024] materials Moisture (%) S（%） Sb (%) Na (%) O（%） Acidified antimony slag 63.72 11.19 14.72 4.28 5.92

[0025] A certain amount of acidified antimony slag is stirred and slurried at a wet weight liquid-to-solid ratio of 2.2:1; after slurrying, it is transferred to an autoclave for reaction, and the reaction temperature is controlled at 220°C, the reaction pressure is 2.3MPa, the reaction time is 2h, and the stirring speed is 150rpm. After the reaction, solid-liquid separation is performed; the filter residue is washed with water, and the clean water and the filter residue are washed twice with water at a wet weight liquid-to-solid ratio of 2.5:1. After washing, liquid-solid separation is performed, and the washing water can be returned to the slurrying and autoclave for use. After washing, the filter residue becomes high-quality antimony concentrate and can be sold externally; the filtrate is evaporated, concentrated, crystallized, and dried to obtain a white sodium sulfate powder with a sodium sulfate content of 99.67%. Example 3

[0026] The element analysis of acidified antimony slag is as follows:

[0027] materials Moisture (%) S（%） Sb (%) Na (%) O（%） Acidified antimony slag 60.42 12.15 15.92 4.81 6.44

[0028] A certain amount of acidified antimony slag is stirred and slurried at a wet weight liquid-to-solid ratio of 2.1:1; after slurrying, it is transferred to an autoclave for reaction, and the reaction temperature is controlled at 210°C, the reaction pressure is 2.1 MPa, the reaction time is 2.5 hours, and the stirring speed is 130 rpm. After the reaction, solid-liquid separation is performed; the filter residue is washed with water, and the clean water and the filter residue are washed twice with water at a wet weight liquid-to-solid ratio of 3:1. After washing, liquid-solid separation is performed, and the washing water can be returned to the slurrying and autoclave for use. After washing, the filter residue becomes high-quality antimony concentrate and can be sold externally; the filtrate is evaporated, concentrated, crystallized, and dried to obtain a white sodium sulfate powder with a sodium sulfate content of 99.76%.

Claims

1. A method for efficient resource utilization of acidified antimony slag by directional crystallization, characterized in that The process steps include: (1) Add water to the acidified antimony slag to make a slurry with a slurry concentration of 40-50%, and then transfer it into a high-pressure reactor; (2) adding an appropriate amount of clean water to the slurried acidified antimony slag, with a mass ratio of clean water to acidified antimony slag of 1 to 1.2:1, a reaction temperature of 200 to 220°C, a reaction pressure of 1.6 to 2.3 MPa, a reaction time of 2 to 6 h, and a blade speed of 100 to 150 rpm in the autoclave to achieve directional crystallization of the acidified antimony slag, and further achieve efficient solid-liquid separation and dehydration and desalination of the acidified antimony slag; (3) The filter residue after separation contains a large amount of antimony sulfide and a small amount of sodium sulfate. The filter residue is sent for secondary water washing, and the filtrate is sent for evaporation and crystallization; (4) During the secondary water washing process of the filter residue, the mass ratio of clean water to filter residue is controlled to be 3:1 to 5:1, the filter residue after water washing is subjected to filter pressing to produce high-grade antimony sulfide concentrate, and the washing water is returned to step (2) and step (1) for recycling; (5) The filtrate produced in step (3) is evaporated, concentrated, and crystallized to produce sodium sulfate crystals, which are then dried to obtain anhydrous sodium sulfate product.

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