A method for co-smelting arsenic alkali residue leaching residue and tungsten-containing waste residue

Abstract

The application discloses a method for collaborative smelting of arsenic alkali residue leaching residue and tungsten-containing waste residue. The method is that after the arsenic alkali residue leaching residue and the tungsten-containing waste residue are crushed and ground, the crushed and ground arsenic alkali residue leaching residue and the tungsten-containing waste residue are mixed with carbonaceous reducing agent, silicon dioxide and binder to form granules, the granules are roasted, arsenic and antimony components are recovered from roasting flue gas in the roasting process, the roasting product is subjected to water leaching to recover sodium tungstate product, and the remaining solid is used as a ceramisite product. The method can realize harmless removal of arsenic and resource recovery of antimony in the arsenic alkali residue leaching residue, realizes resource utilization of tungsten in the tungsten-containing waste residue, obtains the ceramisite product with added value, and truly realizes resource utilization of the arsenic alkali residue leaching residue and the tungsten-containing waste residue.

Description

Technical Field

[0001] This invention relates to a method for co-smelting arsenic-alkali leaching residue and tungsten-containing waste residue, and particularly to a method for co-firing arsenic-alkali leaching residue and tungsten-containing waste residue into ceramsite, and recovering arsenic and antimony components through volatilization and sodium tungstate components through leaching, thereby realizing the resource utilization of arsenic-alkali leaching residue and tungsten-containing waste residue, belonging to the field of solid waste disposal technology. Background Technology

[0002] Arsenic-alkali slag is a waste product from antimony smelting, posing a significant environmental impact. Currently, an increasing number of technologies focus on the safe and resource-based disposal of arsenic-containing solid waste, arsenic-alkali slag, from antimony smelting. Compared to traditional pyrometallurgical processes, wet leaching offers advantages such as high efficiency, low cost, and low pollution, and is widely used in numerous arsenic-containing waste disposal processes. The main process involves: arsenic-alkali slag undergoing a pretreatment system. In the centralized slag silo, the slag is initially crushed by a blasting machine, then fed by a loader into a jaw crusher for further crushing to a particle size below 25mm. It is then transported to a loading hopper and transported to the slag silo by dedicated enclosed dump trucks. In the ball mill system, the primary crushed arsenic-alkali slag is fed via a belt metering system to a sand-making machine (secondary crushing) for further crushing. After further crushing, it enters a wet ball mill via a chute. A suitable amount of secondary leaching solution and supplementary water are injected into the sand-making machine to prevent dust generation and control the liquid-solid ratio of the ball mill slurry. The slurry after ball milling then enters the leaching process. The waste residue after ball milling is treated with a neutral, medium-temperature selective leaching method. The slurry is leached at a solid-liquid ratio of 1:4. During the leaching process, easily soluble arsenic and antimony components and alkaline components are separated from the arsenic-alkali residue, while the poorly soluble arsenic and antimony components, as well as aluminum and silicon components, remain as precipitates, becoming low-arsenic leaching residue. Because the arsenic leaching toxicity of this low-arsenic leaching residue reaches approximately 170 mg / L, it poses a high environmental risk and therefore requires arsenic removal treatment. In addition, the leaching residue contains 2%–4% antimony and 20% sodium carbonate and sodium bicarbonate alkaline components, which have certain economic value. Current conventional disposal processes typically employ stabilization and solidification followed by flexible landfilling. This not only increases the amount of residue and causes severe secondary pollution but also results in the inability to recover the antimony components. Solving the safe disposal problem of leaching residue is of great significance for protecting environmental health and safety and promoting the green and sustainable development of the antimony smelting industry. Summary of the Invention

[0003] To address the shortcomings of existing technologies in the resource-efficient and efficient recycling of arsenic-alkali slag leaching residue and tungsten slag, this invention aims to provide a method for the co-smelting of arsenic-alkali slag leaching residue and tungsten-containing waste residue. This method utilizes pyrometallurgical co-processing of the arsenic-alkali slag and tungsten-containing waste residue into pellets. During the pyrometallurgical roasting process, the arsenic component in both the arsenic-alkali slag and tungsten slag is volatilized and removed, and the antimony component is effectively recovered. This method efficiently promotes the transformation of arsenic and antimony components in the arsenic slag into volatile Sb₂O₃ and As₂O₃, while simultaneously achieving the high-temperature transformation of the alkali and tungsten-containing components into soluble sodium tungstate components, which are easily recovered through water leaching. The final leaching residue is ceramsite, which can be sold as building material, truly achieving deep resource utilization of arsenic-alkali slag leaching residue and arsenic-containing waste residue. This method is fast, efficient, low-cost, simple, and easy to operate, meeting the requirements of industrial production. Compared to the separate treatment of the two types of slag, the pyrometallurgical co-processing technology is relatively simple to operate, has high productivity, preferentially removes arsenic and separates it from other valuable metals, thus avoiding complex separation steps and wastewater discharge.

[0004] To achieve the above-mentioned technical objectives, the present invention provides a method for co-smelting arsenic-alkali slag leaching residue and tungsten-containing waste residue. The method involves crushing and grinding the arsenic-alkali slag leaching residue and tungsten-containing waste residue, then mixing them with a carbonaceous reducing agent, silica-like substances and a binder to form granules. The resulting granules are then roasted. During the roasting process, arsenic and antimony components are recovered from the roasting flue gas. The roasting product is then leached with water to recover sodium tungstate. The remaining solid is used as ceramsite.

[0005] This invention combines arsenic-alkali leaching residue and tungsten-containing waste residue for pyrometallurgical processing. Utilizing the mineral components in both solid wastes, a solid-phase reaction is achieved. With the aid of a carbonaceous reducing agent, the volatilization and removal of arsenic from both the arsenic-alkali and tungsten slags are efficiently promoted, and the antimony components are effectively recovered. The arsenic and antimony components are transformed into volatile Sb₂O₃ and As₂O₃. Simultaneously, the alkali and tungsten-containing components undergo high-temperature transformation into soluble sodium tungstate, which is easily recovered through water leaching. The final leaching residue is ceramsite, which can be sold as building material, truly achieving deep resource utilization of both arsenic-alkali leaching residue and arsenic-containing waste residue. The main components of the arsenic-alkali leaching residue include As, Sb, Si, Al, and a large amount of alkali components, while the main components of the tungsten slag are W, Si, and Al. During pyrometallurgical processing, both have inherent advantages in terms of phase composition. On the one hand, the main components of calcined ceramsite include matrix components (mainly composed of silicon and aluminum compounds), oxide fluxes (such as Na2O, CaO, etc.), and pore-forming agents. These are the key raw materials for calcining ceramsite. The silicon and aluminum components in the two types of solid waste can enable the pyrometallurgical preparation of ceramsite through synergistic calcination. On the other hand, in the pyrometallurgical process, antimony and oxygen components react with activated carbon, undergoing transformation and volatilization according to the following reaction equations: Sb2O4 + CO = Sb2O3 + CO2; Sb2O4 + C = Sb2O3 + CO; 2Sb2O4 + C = 2Sb2O3 + CO2; Sb2O4 + 2C = 2Sb + 2CO2; 4Sb + 3O2 = 2Sb2O3. Arsenate decomposes and reduces under high-temperature calcination to MAsO4 + C → MO + As2O3(g) + CO2(g), MAsO4 + C → MO + As2O3(g) + CO(g). In addition, under high-temperature conditions, the tungsten-containing component reacts with sodium carbonate and sodium bicarbonate components to transform into sodium tungstate. FeWO4 + Na2CO3 = Na2WO4 + FeO + CO 2； WO3 + Na2CO3 = Na2WO4 + CO2; CaWO4 + 2Na2CO3 = Na2WO4 + CaO + CO2. Throughout the pyrometallurgical process, the alkaline components of the arsenic-alkali slag leaching residue serve two main purposes: firstly, they act as fluxing agents and lower the firing temperature; secondly, during roasting, the raw materials generate a liquid phase with certain viscosity and sealing properties at high temperatures. This liquid phase can seal in the gases within the raw materials, creating air inside and promoting the formation of a honeycomb-like porous structure within the ceramsite. The externally added silica-like substances serve two purposes: firstly, they adjust the silicon-to-aluminum ratio, improving the sintering strength of the ceramsite; secondly, they provide skeletal support during roasting, facilitating the volatilization of arsenic and antimony components.

[0006] As a preferred embodiment, the arsenic-alkali leaching residue and tungsten-containing waste residue are ground to -40 mesh. Grinding to an appropriate particle size is beneficial for subsequent granulation and high-temperature solid-phase reaction.

[0007] As a preferred embodiment, the ratio of the arsenic-alkali leaching residue to the tungsten-containing waste residue is measured according to a sodium to tungsten molar ratio of 1.0 to 3.0:1. At a suitable sodium-tungsten ratio, it is beneficial to convert all the tungsten in the tungsten-containing waste residue into sodium tungstate.

[0008] As a preferred embodiment, the amount of carbonaceous reducing agent is 5% to 8% of the total mass of the arsenic-alkali leaching residue and the tungsten-containing waste residue. The appropriate amount of carbonaceous reducing agent mainly promotes the conversion and volatilization of arsenic and antimony components in the arsenic-alkali leaching residue and the tungsten-containing waste residue. Examples of carbonaceous reducing agents include activated carbon, pulverized coal, and coke powder.

[0009] As a preferred embodiment, the amount of silica-based material used is adjusted to a silicon-to-aluminum ratio of 5:1 to 8:1. The silica-based material mainly functions to regulate the silicon-to-aluminum ratio, improve the sintering strength of the ceramsite, and also provides skeletal support during the calcination process, which is beneficial for the volatilization of arsenic and antimony components. Adding too much silica-based material will affect the final strength of the ceramsite, while adding too little will reduce the volatilization effect of arsenic and antimony. Examples of silica-based materials include quartz powder.

[0010] As a preferred embodiment, the binder comprises at least one of bentonite, sodium humate, sodium lignosulfonate, and water glass. These binders are common granulation additives in the industry.

[0011] As a preferred embodiment, the amount of binder used is 3-8% of the total mass of arsenic-alkali leaching residue and tungsten-containing waste residue.

[0012] As a preferred embodiment, the particle size of the granules is controlled between 0.8 cm and 1.5 cm.

[0013] As a preferred embodiment, the roasting conditions are: roasting temperature of 800~900℃ and roasting time of 60min~90min. Increasing the roasting temperature and extending the roasting time is beneficial for improving the volatilization and recovery of arsenic and antimony components, promoting the combination and transformation of tungsten components and sodium salts, reducing the apparent density of the ceramsite, and maintaining a high standard of compressive strength. The granules made from the arsenic-alkali slag leaching residue and tungsten-containing waste residue of this invention form a large number of microporous structures on the surface of the granules during the roasting process due to the volatilization of arsenic and antimony components, while the interior has a honeycomb structure. This facilitates the outflow of sodium tungstate components from the internal structure during leaching, while also satisfying the characteristics of lightweight and low-density ceramsite.

[0014] As a preferred embodiment, the water immersion conditions are: water temperature of 60~100℃, immersion time of 60~90min, liquid-solid ratio of 5:1~10:1, and stirring rate of 300r / min~500r / min. As the leaching temperature and leaching time increase, the leaching rate of tungsten gradually increases.

[0015] Compared with existing technologies, the technical effects of the present invention are as follows: This invention utilizes the co-processing of arsenic-alkali leaching residue and tungsten-containing waste residue to prepare ceramsite. It fully leverages the advantageous components of both materials. By co-processing the two types of waste residue, it not only achieves the harmless removal of arsenic and the resource recovery of antimony from the arsenic-alkali leaching residue, but also realizes the resource utilization of tungsten from the tungsten-containing waste residue, while obtaining value-added ceramsite products. This is a new approach of "treating waste with waste" and provides a novel strategy for the resource utilization of arsenic-alkali leaching residue and the resource disposal of tungsten slag. Attached Figure Description

[0016] Figure 1 This is a diagram showing the surface morphology of calcined ceramsite.

[0017] Figure 2 This is a diagram of the internal structure of calcined ceramsite. Detailed Implementation

[0018] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims. Example 1

[0019] Using arsenic-alkali leaching residue from Lengshuijiang Tin Mine and tungsten-containing waste residue from Chenzhou Tungsten Smelter as experimental research objects, Table 1 below shows the elemental composition of the arsenic-alkali leaching residue. Table 1 shows that the elemental composition of the arsenic-alkali leaching residue is complex, mainly composed of sodium, aluminum, silicon, and antimony. Specifically, silicon content is 12.12%, sodium content is 21.61%, antimony content is 3.406%, and arsenic content is 2.65%. According to the experimental arrangement, the arsenic-alkali leaching residue and tungsten-containing waste were crushed and ground to a particle size of -40 mesh. 500g of the crushed and ground arsenic-alkali leaching residue was weighed out. The tungsten-containing waste, arsenic-alkali leaching residue, reducing carbon, SiO2, and binder were mixed in a certain proportion. The amount of reducing carbon was 5% of the total residue. The added quartz powder was intended to serve as the matrix framework during the raw material roasting process. The amount of added quartz powder should be controlled at a silicon-to-aluminum ratio of 5:1, 6:1, 7:1, or 8:1. The binder used in the raw materials is bentonite, with a mass percentage of 5% of the total mass. After thoroughly mixing the leaching residue and tungsten-containing waste, add an appropriate amount of water and mix evenly using a stirrer or mixer to ensure the material reaches suitable moisture content and that the mixture has sufficient adhesion and plasticity. Shape the mixture into 15mm spheres, ensuring that each sphere is uniform in size and shape. After shaping, place these spheres in an oven for thorough drying to ensure the spheres maintain their shape stability during drying and that internal moisture is effectively evaporated and removed. After proper drying, the sphere surface exhibits a certain degree of hardness and dryness, while internal moisture is effectively removed. This gives the spheres sufficient mechanical strength and stability. During the pyrometallurgical process, the mixture is fed into a calcining furnace for heating treatment. The tube furnace calcination temperature is set at 800℃, 900℃, and 1000℃. The calcination time was controlled at 60 minutes. After appropriate calcination, the arsenic and antimony components were effectively volatilized. At the same time, various elements in the mixture were fully solidified and sintered, forming a ceramic particle product with certain strength and durability. The ceramic particles after arsenic and antimony volatilization were placed in hot water systems at 60℃, 80℃, and 100℃, respectively, with stirring times set at 30 minutes, 60 minutes, and 90 minutes, a liquid-to-solid ratio of 8:1, and a stirring rate of 400 r / min. The resulting solutions contained dissolved tungsten elements. The tungsten component content in the solutions was measured, and the overall tungsten leaching efficiency of the ceramic particles was calculated. After solid-liquid separation, the leached ceramic particles were dried, realizing resource recycling and environmental protection. Specific data are shown in Tables 2, 3, and 4 below.

[0020] The calcined ceramsite is as follows: Figure 1 As shown, the surface is smooth and uniform with a porous structure and a honeycomb structure inside, which is conducive to gas exchange and liquid permeation on the surface of the ceramsite. This provides a good airtight transport for the volatilization of arsenic and antimony in the leaching residue and a better leaching environment for the resource utilization of tungsten in tungsten-containing waste.

[0021] Under the conditions of calcination temperature of 900℃ and calcination time of 60 min, the volatilization rate of arsenic and antimony in the system gradually increased with the increase of silicon-aluminum ratio. Simultaneously, the apparent density and compressive strength of the calcined ceramsite gradually decreased. This is because the addition of SiO2 to the system promoted the decomposition of arsenates to a certain extent, while the excessive addition of silica caused excessive liquid-phase melting on the surface of the ceramsite, which significantly reduced the apparent density and compressive strength of the ceramsite. With the increase of calcination temperature and calcination time, the arsenic and antimony content in the system gradually increased. When the calcination temperature was 1000℃ and the calcination time was 60 min, the arsenic and antimony in the system almost completely volatilized. This indicates that the efficient removal of arsenic and antimony components from the leaching residue can be achieved by co-processing leaching residue and tungsten-containing waste.

[0022] The properties of ceramsite calcined under different temperatures and times are shown in Table 2. With increasing calcination time, the arsenic and antimony volatilization rate in the system gradually increases, and the apparent density of the calcined ceramsite gradually decreases. When the calcination time is relatively short, the external morphology of the ceramsite does not show significant expansion. At this time, the strength of the ceramsite is mainly affected by its internal phases. However, due to the relatively small amount of strength-providing phases formed in a short time, the compressive strength of the ceramsite does not reach a high level. Conversely, when the calcination time is extended to an excessively long period, the surface of the ceramsite exhibits severe expansion. Although this expansion is accompanied by an increase in the amount of high-strength phases, the strength improvement brought by these increased phases is insufficient to offset the negative effects of expansion, such as the loosening or destruction of the internal structure. Therefore, even with an increase in high-strength phases, the compressive strength of the ceramsite still shows a decreasing trend. The effect of calcination temperature on the compressive strength of the ceramsite shows a similar pattern, but with increasing calcination temperature, the arsenic and antimony volatilization rate in the system gradually increases, and the apparent density of the calcined ceramsite gradually increases. This indicates that properly controlling the calcination time and temperature is of great significance for improving the performance of ceramsite.

[0023] The calcined ceramsite was leached under different temperature and time conditions. The results showed that the leaching rate of tungsten gradually increased with increasing leaching temperature and time. This indicates that the sodium component in the leaching residue and the tungsten component in the tungsten-containing waste reacted fully to form sodium tungstate, which entered the solution system during the leaching process. Therefore, this scheme achieves the harmless removal of arsenic and the resource recovery of antimony during the pyrometallurgical roasting process. The roasting residue becomes ceramsite, and the tungsten in the tungsten-containing waste is fully recovered, thereby further improving the comprehensive utilization efficiency of the waste residue.

[0024] Table 1. Main elemental composition of arsenic-alkali leaching residue

[0025] Table 2 Effect of Si / Al ratio on the properties of ceramsite

[0026] Table 3. Effects of calcination temperature and calcination time on the properties of ceramsite

[0027] Table 4. Effects of leaching temperature and leaching time on the volatilization of arsenic and antimony. .

Claims

1. A method for co-smelting arsenic-alkali leaching residue and tungsten-containing waste residue, characterized in that: Arsenic-alkali slag leaching residue and tungsten-containing waste residue are crushed and ground, then mixed with carbonaceous reducing agent, silica-like substances and binder to form granules. The resulting granules are roasted, and arsenic and antimony components are recovered from the roasting flue gas during the roasting process. The roasting product is then leached with water to recover sodium tungstate product, and the remaining solid is used as ceramsite product. The ratio of the arsenic alkali leaching residue to the tungsten-containing waste residue is measured according to a molar ratio of sodium to tungsten of 1.0~3.0:1; The amount of the carbonaceous reducing agent is 5% to 8% of the total mass of the arsenic-alkali leaching residue and the tungsten-containing waste residue; The amount of the silica-based material is adjusted to a silicon-to-aluminum ratio of 5:1 to 8:1 in the system. The calcination conditions are as follows: calcination temperature is 800~900℃, and calcination time is 60min~90min.

2. The method for co-smelting arsenic-alkali slag leaching residue and tungsten-containing waste residue according to claim 1, characterized in that: The arsenic-alkali leaching residue and tungsten-containing waste residue are ground to -40 mesh.

3. The method for co-smelting arsenic-alkali slag leaching residue and tungsten-containing waste residue according to claim 1, characterized in that: The binder includes at least one of bentonite, sodium humate, sodium lignosulfonate, and water glass. The amount of binder used is 3-8% of the total mass of arsenic alkali leaching residue and tungsten-containing waste residue.

4. The method for co-smelting arsenic-alkali slag leaching residue and tungsten-containing waste residue according to claim 1, characterized in that: The particle size of the granules is controlled between 0.8cm and 1.5cm.

5. The method for co-smelting arsenic-alkali slag leaching residue and tungsten-containing waste residue according to claim 1, characterized in that: The conditions for water immersion are: water temperature of 60~100℃, duration of 60~90min, liquid-solid ratio of 5:1~10:1, and stirring rate of 300r / min~500r / min.

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