CN110407250B

CN110407250B - Method for stabilizing treatment and recycling sulfur by converting arsenic-containing waste residues into arsenite

Info

Publication number: CN110407250B
Application number: CN201910746898.XA
Authority: CN
Inventors: 张静; 李明洋; 刘峰
Original assignee: Research Center for Eco Environmental Sciences of CAS
Current assignee: Research Center for Eco Environmental Sciences of CAS
Priority date: 2019-08-14
Filing date: 2019-08-14
Publication date: 2021-02-05
Anticipated expiration: 2039-08-14
Also published as: CN110407250A

Abstract

The method mainly adopts a hydrothermal method, quickly converts arsenic slag into arsenite by introducing a mineralizer aluminum sulfate, optimizes conversion conditions and evaluates the long-term stability of the arsenite. The solid-liquid ratio, the pH value and the like of the arsenic-containing waste residue are adjusted, then the arsenic-containing waste residue is subjected to hydrothermal reaction, and the reaction temperature, the reaction pressure and the reaction time are controlled. Thereby realizing the solidification and stabilization of the arsenic. Experimental results show that the new method for treating arsenic waste residue through hydrothermal stable solidification has the advantages that the arsenic stabilization efficiency can reach 80%, the recycling of sulfur can be realized, the recovery rate of sulfur is higher than 90%, and the purity is higher than 90%. The toxicity leaching of the arsenic slag after treatment is less than 2mg/L and less than the toxicity leaching standard limit value (5mg/L) of the hazardous waste, and the requirement of the hazardous waste on stockpiling is met, which shows that the technology is economic and effective for stabilizing the arsenic slag.

Description

Method for stabilizing treatment and recycling sulfur by converting arsenic-containing waste residues into arsenite

Technical Field

The invention relates to the field of non-ferrous metal smelting technology and environmental protection, and relates to the fields of solidification and stabilization treatment of arsenic-containing waste residues and recycling of sulfur.

Background

A large amount of high-concentration arsenic-containing waste liquid is generated in the non-ferrous metal smelting process, and the high-concentration arsenic-containing waste acid is mainly treated by adopting a precipitation process, so that the process is simple, and the treatment effect is good, so that the method is widely used. However, the process generates a large amount of arsenic-containing waste residues which belong to highly toxic substances, including arsenic sulfide (As)₂S₃、As₂S₅) Arsenate slag (CaHAsO)₄、Ca₃(AsO₄)₂、FeAsO₄). The arsenic-containing waste residues are generally amorphous nano particles, belong to highly toxic articles, are easy to cause cancers, are easy to dissolve in alkali metal hydroxides and carbonates, and are oxidized into arsenic acid to be dissolved by the action of peroxides and concentrated nitric acid, so that the environment and the human health are easily threatened. If the arsenic waste residue can not be properly treated and disposed, the operation of the vulcanization treatment process of the acid wastewater of enterprises is limited, and the method has great potential safety hazard and is very easy to cause secondary pollution. Therefore, an economical and environment-friendly method for performing subsequent treatment on the arsenic-containing waste residue needs to be found.

Aluminum and iron salts play an important role in controlling the migration of arsenic, since these metals are ubiquitous in the natural environment and in water treatment processes. In recent decades, the solubility of iron arsenic phase has been studied more and more, and the stability of arsenate as a compound, especially the stability of crystalline aluminum arsenate phase, has been neglected, and arsenopyrite is a mineral with a structure similar to scorodite, is a good arsenic-fixing mineral, and has the advantages of high arsenic-fixing rate, large particle and stable structure.

At present, two methods are mainly used for treating arsenic-containing waste residues, and one method is to reduce the environmental risk and toxicity of the arsenic residues through stabilization and solidification; the other is to react the arsenic in the arsenic slag to generate arsenic oxide, simple substance arsenic or arsenate to realize resource recycling. The resource treatment can be divided into fire treatment and wet treatment. The pyrogenic process mainly comprises oxidizing roasting, reducing roasting, vacuum roasting and the like; the wet method mainly comprises sulfuric acid leaching, copper sulfate replacement, ferric sulfate method, alkaline leaching and the like.

For the resource utilization of arsenic-containing waste residues, the method comprises the following steps:

liuwei et al use arsenate as raw material, after arsenate material and carbonaceous reducing agent are mixed uniformly, put into inert or reducing atmosphere, under the condition of negative pressure, carry on reduction roasting, collect the roasting flue gas, get arsenic products (Liuwei, Liang super, Jofin, etc. a method for preparing arsenic by arsenic-containing material direct reduction roasting [ Z ]. CN 106636678A). Dudongyun and the like utilize an oxidation desulfurization leaching-acidification reduction process, and stannous chloride is added under an acidic condition for reduction to prepare simple substance arsenic (Dudongyun, Ruije, Guoli and the like, a method for recovering simple substance arsenic from arsenic sulfide slag [ Z ]. CN 103388076B). Malayang and the like dissolve arsenic sulfide slag in alkali, and oxidize sulfur ions into simple substances by blowing oxygen, the arsenic acid solution is reduced into an arsenic acid solution by introducing sulfur dioxide, and the arsenic acid solution is subjected to reduced pressure distillation and cooling crystallization to prepare arsenic trioxide (Malayang. method [ Z ]. CN102115166A ] for preparing arsenic trioxide by using arsenic sulfide waste slag).

The arsenic waste residue solidification and stabilization technology is currently applied as follows:

min wavelet is used for realizing the hydrothermally stable curing of the arsenic sulfide slag by adjusting the liquid-solid ratio, pH and oxidation-reduction potential of the arsenic sulfide slag and then entering a high-temperature high-pressure hydrothermal reaction kettle for curing reaction (Min wavelet, firewood yuan, Yajing et al. Old xiaofeng and the like react arsenic sulfide slag with sodium sulfide, then an oxidant is added for oxidation, and then ferric salt or aluminum salt is added, finally cement is adopted for solidification, so that the arsenic leaching toxicity is reduced (a method for harmless treatment of arsenic sulfide slag [ Z ]. CN 105963902A). However, the curing methods have the problems of large compatibilization ratio before and after curing, large land piling and filling requirements in the later period, and the like. Zhang hong et al, which is a method for leaching and synchronously stabilizing arsenic sulfide slag [ Z ]. CN105967232A, add ferrous sulfate solution into arsenic sulfide slag, and introduce air to heat and oxidize the arsenic sulfide slag to generate scorodite, thereby reducing the leaching toxicity of the arsenic sulfide slag and facilitating safe stockpiling. Based on the previous research, the invention converts arsenic slag into large-particle arsenolite crystals similar to scorodite so as to achieve the aim of stabilizing and solidifying the arsenic slag, but the operation of the method is too complex.

The invention provides a novel method for treating arsenic-containing waste residue through hydrothermal stable solidification. The hydrothermal stable solidification treatment method can be used for stabilizing and solidifying arsenic-containing waste residues generated in the industries of smelting, electroplating, chemical engineering and the like, and specifically comprises the following steps: the solid-liquid ratio, the pH value, the oxidation-reduction potential and the like of the arsenic-containing waste residue are adjusted, then the arsenic-containing waste residue is subjected to hydrothermal reaction, and the aim of solidification and stabilization of arsenic is fulfilled by controlling the reaction temperature, the reaction pressure, the reaction time, the cooling rate and the cooling mode. Experimental results show that the new method for treating arsenic sulfide slag through hydrothermal stable solidification has arsenic stabilization efficiency as high as 80%, leaching toxicity after treatment is lower than 2mg/L, and volume reduction of waste slag is 60%. In addition, the novel method for treating arsenic-containing waste residue through hydrothermal stable solidification can realize the recycling of elemental sulfur, wherein the recovery rate of sulfur is higher than 90%, and the purity exceeds 90%.

Disclosure of Invention

In order to solve the problem that the existing arsenic-containing material is difficult to treat, the invention aims to provide a high-efficiency solidification and stabilization method and a method for recovering sulfur. The method realizes the reduction and harmlessness of arsenic-containing waste residues and the resource utilization of sulfur. In order to realize the technical purpose, the invention provides a method for solid-phase conversion, solidification and stabilization of arsenic-containing waste residue and simultaneous recovery of sulfur, which is characterized in that in the hydrothermal process, sulfide ions dissolved out of arsenic residue and trivalent arsenic are respectively oxidized into sulfur and pentavalent arsenic, and then As⁵⁺With Al³⁺The arsenic and the aluminum oxide are combined to form arsenic solidification and stabilization. The method is simple to operate, the generated arsenopyrite crystals are large in particles (about 30 microns), easy to precipitate, small in size and high in stability, the arsenic leaching method is disclosed in HJT 299-2007, and the result shows that the toxicity leaching of arsenic is 1-2 mg/L, and is smaller than 5mg/L of a solid waste identification standard, namely leaching toxicity identification (GB5085.3-2007) and a hazardous waste landfill pollution control standard (GB 18589-2001). The technology is shown to be economical and effective for stabilizing treatment of arsenic slag. Meanwhile, the generated elemental sulfur is easy to recover and can be reused as sulfur.

The reaction equation involved in the invention is as follows:

As₂S₃+4H₂O₂＝2AsO₄ ^3-+3S↓+8H⁺

AsO₄ ^3-+Al³⁺+2H₂O＝AlAsO₄·2H₂O

the technical scheme of the invention is as follows:

a process for stabilizing waste dregs to become arsenopyrite and recovering sulfur includes such steps as adding the waste dregs to the mixture of hydrogen peroxide and aluminium sulfate, high-pressure reaction at a certain temp. Finally, the arsenopyrite and the elemental sulfur are generated, and the purposes of fixing arsenic and recovering sulfur are achieved. The method comprises the following specific steps:

preparing a mixed solution containing 10-15% of hydrogen peroxide and 0.015-0.04 mol/L of aluminum sulfate dodecahydrate, adjusting the pH value to be 1-3 by using sulfuric acid, and then adding arsenic waste residues into the mixed solution to be uniformly stirred (the solid-liquid ratio is 1: 150-1: 80 g/ml);

and (3) transferring the obtained mixed solution into a hydrothermal reaction kettle, and placing the hydrothermal reaction kettle in an oven at the temperature of 180-200 ℃ for reaction for 2-4 hours. After the reaction, it was cooled to room temperature. After hydrothermal treatment, white arsenolite and recyclable yellow solid sulfur simple substance are obtained by centrifugal separation, washing and drying.

Drawings

FIG. 1 is a comparison of XRD of solid slag of arsenic sulfide slag before treatment in example 1 with a standard card

FIG. 2 is an SEM photograph of solid arsenic sulfide slag obtained before treatment in example 1

FIG. 3 is a comparison of XRD of the treated arsonite of example 1 with a standard card

FIG. 4 is an SEM photograph of the arsenopyrite after being treated in example 1

FIG. 5 is a comparison of XRD of elemental sulfur after treatment in example 1 with a standard card

FIG. 6 is an SEM photograph of elemental sulfur after treatment in example 1

Detailed Description

Example 1

Adding 0.1g of slag containing simulated arsenic sulfide into a reaction kettle, adding an aluminum sulfate solution containing 10% of hydrogen peroxide and 0.03mol/L to ensure that the solid-to-liquid ratio is 1:150g/ml, adjusting the pH value to be 2, uniformly stirring, placing the reaction kettle at 200 ℃ for reaction for 2 hours, and naturally cooling to room temperature. Through cleaning and flotation, yellow caking sulfur and arsenopyrite solids are finally obtained through separation, the recovery rate of sulfur reaches 90%, and the purity of sulfur exceeds 95%; wherein the arsenic fixing efficiency is greater than 80%; the toxic leaching of arsenic is 1.8 mg/L.

Example 2

Arsenic sulfide sludge which is an acid wastewater treatment product of a certain smelting plant in Fujian province is taken as a research object. The total element mass analysis shows that the main elements in the arsenic slag comprise 53.4 percent of As 42 percent, 1.5 percent of Na, 1.3 percent of Ni and 0.98 percent of Cu, 0.1g of arsenic sulfide waste slag is taken to be put into a reaction kettle, an aluminum sulfate solution containing 10 percent of hydrogen peroxide and 0.03mol/L is added to ensure that the solid-to-liquid ratio is 1:150g/ml, sulfuric acid is used for adjusting the pH value to be 2, the reaction kettle is placed at 200 ℃ for reaction for 4 hours after being uniformly stirred, and the reaction kettle is naturally cooled to the room temperature. Through cleaning and flotation, yellow caking sulfur and arsenopyrite solids are finally obtained through separation, the recovery rate of sulfur reaches 90%, and the purity of sulfur exceeds 90%; wherein the arsenic fixing efficiency is greater than 80%; the toxic leaching of arsenic is 1.6 mg/L.

Embodiment 3

Arsenic sulfide slag generated after the sulfide precipitation of waste acid wastewater of certain nonferrous metal smelting plant in Henan province is taken as a research object. The total element mass analysis shows that the main elements in the arsenic slag comprise 11.35 percent of As, 37.96 percent of S, 26.09 percent of O, 23.53 percent of Cu and 1.07 percent of Al, 0.2g of arsenic-containing waste slag is taken to be put into a reaction kettle, 10 percent of hydrogen peroxide and 0.04mol/L of aluminum sulfate solution are added to ensure that the solid-to-liquid ratio is 1:80g/ml, the pH value is adjusted to be 2, the reaction kettle is placed at 200 ℃ for reaction for 3 hours after being uniformly stirred, and the reaction kettle is naturally cooled to the room temperature. Through cleaning and flotation, yellow caking sulfur and arsenopyrite solids are finally obtained through separation, the recovery rate of sulfur reaches 90%, and the purity of sulfur exceeds 96%; wherein the arsenic fixation rate reaches 80 percent; the toxic leaching of arsenic is 1.8 mg/L.

Similarly, a plurality of embodiments can be provided according to the protection scope defined by the claims and the technical solution provided by the present specification. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles and spirit of the invention, and these are intended to be within the scope of the invention.

Claims

1. A method for stabilizing treatment and recycling sulfur by converting arsenic-containing waste residues into arsenolite comprises the following steps:

(1) preparing 0.015-0.04 mol/L of mixed solution of aluminum sulfate dodecahydrate and 10% -15% of hydrogen peroxide, adjusting the pH value to 1-3 by using sulfuric acid, and uniformly stirring;

(2) the solid-liquid ratio is 1: 150-1: 80g/ml, adding arsenic sulfide slag into the mixed solution in the step (1), and stirring and mixing uniformly;

(3) transferring the mixed solution in the step (2) into a high-pressure reaction kettle, reacting at the temperature of 180-200 ℃ for 2-4 hours, and naturally cooling to room temperature;

(4) and (3) obtaining arsenic-containing filter residue, supernatant and yellow solid floating on the supernatant after reaction, respectively collecting, washing and drying the two solids, wherein the solid sample after hydrothermal treatment is yellow solid elemental sulfur and white filter residue crystal arsenopyrite.