Arsenic alkali residue disposal method

Abstract

The invention belongs to the technical field of arsenic-alkali residues, and discloses an arsenic-alkali residue treatment method which comprises the following steps: step 1, leaching separation, step 2, evaporation drying, step 3, plate-frame pressure filtration, and step 4, mixing to prepare sodium silicate. According to the invention, the mixed salt containing sodium arsenate and a proper amount of silicon powder are mixed and sintered, and only the reaction conditions of the reactants and silicon dioxide need to be considered in the reaction process of the mixed and molten sodium arsenate, sodium arsenite, sodium carbonate, sodium bicarbonate, sodium sulfate and quartz stone. Sodium silicate can be produced under a certain condition by melting and mixing the compounds, and actual application and operation are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of arsenic-alkali slag, in particular to a method for disposing arsenic-alkali slag. Background Art

[0002] Arsenic alkali slag composition: Arsenic alkali slag is mainly composed of arsenic, calcium, magnesium, aluminum, iron and other elements, and also contains a certain amount of hydroxides, oxides and other inorganic salts. Among them, arsenic is the most common and most critical component, and the arsenic content varies in different arsenic alkali slags.

[0003] In the current practical application process, arsenic alkali slag is an inevitable byproduct of metal smelting. Its high concentration of arsenic and strong alkalinity pose a serious threat to soil, water sources and even ecosystems. Traditional treatment methods, such as landfill or incineration, are not only inefficient, but may also cause secondary pollution, aggravating the arsenic alkali slag problem, which is not conducive to practical application and operation. Summary of the invention

[0004] One of the objects of the present invention is to provide a method for disposing arsenic alkali slag.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a method for treating arsenic alkali slag, comprising the following steps:

[0006] Step 1: leaching and separation, using solid waste residue leaching and separation treatment technology to obtain water-soluble substances and residues;

[0007] Step 2: Evaporation and drying: a mixed salt containing sodium arsenate is obtained by evaporation and drying, and resource utilization can be achieved to reduce the emission of harmful substances;

[0008] Step three: Plate and frame filter pressing. Through the plate and frame filter pressing method, water-insoluble silicon dioxide, aluminum oxide and other substances are returned to the antimony refinery to infiltrate the antimony ore sand for calcination. After calcination, heavy metals such as antimony, copper, lead, cadmium and their compounds and dangerous substances such as chlorine in the flue gas are condensed into powdered solids for recovery and reprocessing. The solid slag can meet the quality requirements of cement production.

[0009] Step 4: Mixing to make sodium silicate: Mixing the arsenic-containing mixed salt with silicon oxide to make sodium silicate (water glass), and passing quality inspection to obtain sodium silicate water glass that meets production requirements.

[0010] Preferably, in step one, soluble substances such as sodium (sub)arsenate, sodium carbonate, sodium thioantimonite, sodium (sub)sulfate, etc. that are soluble in water are introduced into the solution; under optimized conditions, the arsenic leaching rate can reach more than 95%, providing a high-concentration arsenic-containing solution for subsequent steps, and the effect is evaluated by indicators such as arsenic leaching rate, impurity removal rate, leaching solution concentration and purity.

[0011] Preferably, in step 2, a mixed salt containing sodium arsenate is obtained by evaporating and drying the sodium arsenate, soda ash and sodium sulfate in the water-soluble substances.

[0012] Preferably, in step three, the water-insoluble silicon dioxide, aluminum oxide, antimony, arsenic and other substances are filtered through a plate and frame filter press, and then sintered to extract the antimony, arsenic and other substances therein, and the slag is sent to a cement plant as raw material.

[0013] Preferably, in step 4, at high temperature, the arsenic mixed salt reacts with quartz sand (SiO2) to generate sodium silicate to achieve material conversion. The sodium silicate solid is subjected to post-treatment processes such as elution, dehydration, and drying to obtain the final sodium silicate product, with an arsenic conversion rate of up to 97% and a sodium silicate water glass purity of 99.5%.

[0014] Preferably, sodium arsenate and sodium sulfate can be decomposed by the alkaline oxide in sodium carbonate, and the reaction equation is as follows: Na2CO3+Na2HAsO4→Na3AsO4+CO2↑+H2O Na2CO3+Na2SO4→2Na2SO4+CO2↑ At the same time, silicon powder will also react with the pyrolyzed sodium carbonate at high temperature to generate sodium silicate: SiO2+2Na2CO3→Na4SiO4+2CO↑.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention is to sinter a mixed salt containing sodium arsenate and an appropriate amount of silicon powder. In the reaction process of mixing the melted sodium arsenate, sodium arsenite, sodium carbonate, sodium bicarbonate, sodium sulfate and quartz stone, only the reaction of these reactants with silicon dioxide needs to be considered. By melting and mixing these compounds, sodium silicate can be produced under certain conditions. In the process of producing sodium silicate, some iron and calcium ions react with arsenic at high temperature to produce insoluble substances such as ferric arsenate and calcium arsenate. Subsequently, the generated sodium silicate solid is subjected to elution treatment to remove surface impurities, and insoluble substances such as ferric arsenate and calcium arsenate are further separated by filtration. Subsequently, dehydration and drying treatment are carried out to obtain a high-quality sodium silicate product.

[0017] (2) The specific chemical formula of the present invention is:

[0018] Na2CO3+SiO2→Na2SiO3+CO2↑, NaHCO3+SiO2→Na2SiO3+CO2↑+H2O, Na3AsO4+SiO2→Na2SiO3+As2O3↑, NaAsO2+SiO2→Na2SiO3+As2O3↑+H2ONa2SO4+SiO2→Na2SiO3+SO2↑.

[0019] (3) The compounds of the present invention all contain oxygen and sodium, which can react with silicon dioxide to form sodium silicate. Therefore, in the molten mixture, these compounds will undergo a reaction similar to the above chemical reaction formula. The overall reaction equation is: Na3AsO3+Na2CO3+Na2Sb2O3+Na2SO4+SiO2→Na4SiO4+As2O3+Sb2O3+CO2+SO2. In this process, each soluble substance is mixed with quartz and melted, and finally sodium silicate and some gas products are generated. Among them, what role does NaAsO3 play in the melting reaction and what impact does it have on the quality of the product? As a salt of Na+ and AsO3^-3, NaAsO3, after entering the solution, its main role is to provide As2O3 in the reaction, which is an important intermediate product for the formation of sodium silicate. NaAsO3 itself will also undergo certain chemical reactions, but it may not have a great impact on the amount and quality of the sodium silicate finally generated. In the melting reaction phenomenon, As2O3 reacts with SiO2 to generate Na2Si2O5As2O3. Therefore, the addition of Na3AsO3 is critical to the provision of this intermediate product during the reaction. At the same time, if Na3AsO3 contains other impurities, it may affect the quality and purity of the final sodium silicate. Therefore, when adding Na3AsO3, its purity and impurity content need to be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0022] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0024] One of the preferred embodiments of the present invention is as follows Figure 1 As shown, a method for treating arsenic alkali slag comprises the following steps:

[0025] Step 1: leaching and separation, using solid waste residue leaching and separation treatment technology to obtain water-soluble substances and residues;

[0026] Step 2: Evaporation and drying: a mixed salt containing sodium arsenate is obtained by evaporation and drying, and resource utilization can be achieved to reduce the emission of harmful substances;

[0027] Step three: Plate and frame filter pressing. Through the plate and frame filter pressing method, water-insoluble silicon dioxide, aluminum oxide and other substances are returned to the antimony refinery to infiltrate the antimony ore sand for calcination. After calcination, heavy metals such as antimony, copper, lead, cadmium and their compounds and dangerous substances such as chlorine in the flue gas are condensed into powdered solids for recovery and reprocessing. The solid slag can meet the quality requirements of cement production.

[0028] Step 4: Mixing to make sodium silicate: Mixing the arsenic-containing mixed salt with silicon oxide to make sodium silicate (water glass), and passing quality inspection to obtain sodium silicate water glass that meets production requirements.

[0029] In the step 1, soluble substances such as sodium (sub)arsenate, sodium carbonate, sodium thioantimonite, sodium (sub)sulfate, etc. that are soluble in water are introduced into the solution; under optimized conditions, the arsenic leaching rate can reach more than 95%, providing a high-concentration arsenic-containing solution for subsequent steps, and the effect is evaluated by indicators such as arsenic leaching rate, impurity removal rate, leaching solution concentration and purity.

[0030] The second step is to obtain a mixed salt containing sodium arsenate by evaporating and drying the sodium arsenate, soda ash and sodium sulfate in the water-soluble substances.

[0031] In the step three, the water-insoluble silicon dioxide, aluminum oxide, antimony, arsenic and other substances are filtered through a plate and frame filter press, and then sintered to extract the antimony, arsenic and other substances therein, and the slag is sent to the cement plant as raw materials.

[0032] In step 4, at high temperature, the arsenic mixed salt reacts with quartz sand (SiO2) to generate sodium silicate, thereby achieving material conversion. The sodium silicate solid is subjected to post-treatment processes such as elution, dehydration, and drying to obtain the final sodium silicate product, with an arsenic conversion rate of up to 97% and a sodium silicate water glass purity of 99.5%.

[0033] The sodium arsenate and sodium sulfate can be decomposed by the alkaline oxide in the sodium carbonate, and the reaction equation is as follows: Na2CO3+Na2HAsO4→Na3AsO4+CO2↑+H2O Na2CO3+Na2SO4→2Na2SO4+CO2↑ At the same time, silicon powder will also react with the pyrolyzed sodium carbonate at high temperature to generate sodium silicate: SiO2+2Na2CO3→Na4SiO4+2CO↑.

[0034] Working principle:

[0035] When used, a mixed salt containing sodium arsenate is mixed with an appropriate amount of silicon powder for sintering. In the reaction process of mixing the melted sodium arsenate, sodium arsenite, sodium carbonate, sodium bicarbonate, sodium sulfate and quartz stone, only the reaction of these reactants with silicon dioxide needs to be considered. By melting and mixing these compounds, sodium silicate can be produced under certain conditions. In the process of producing sodium silicate, some iron and calcium ions react with arsenic at high temperature to produce insoluble substances such as iron arsenate and calcium arsenate. Subsequently, the generated sodium silicate solid is eluted to remove surface impurities, and insoluble substances such as iron arsenate and calcium arsenate are further separated by filtration. Subsequently, dehydration and drying are carried out to obtain a high-quality sodium silicate product.

[0036] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for treating arsenic alkali slag, characterized in that: Includes the following steps: Step 1: leaching and separation, using solid waste residue leaching and separation treatment technology to obtain water-soluble substances and residues; Step 2: Evaporation and drying: a mixed salt containing sodium arsenate is obtained by evaporation and drying, and resource utilization can be achieved to reduce the emission of harmful substances; Step three: Plate and frame filter pressing. Through the plate and frame filter pressing method, water-insoluble silicon dioxide, aluminum oxide and other substances are returned to the antimony refinery to infiltrate the antimony ore sand for calcination. After calcination, heavy metals such as antimony, copper, lead, cadmium and their compounds and dangerous substances such as chlorine in the flue gas are condensed into powdered solids for recovery and reprocessing. The solid slag can meet the quality requirements of cement production. Step 4: Mixing to make sodium silicate: Mixing the arsenic-containing mixed salt with silicon oxide to make sodium silicate (water glass), and passing quality inspection to obtain sodium silicate water glass that meets production requirements.

2. The method for treating arsenic alkali slag according to claim 1, characterized in that: In the step 1, soluble substances such as sodium (sub)arsenate, sodium carbonate, sodium thioantimonite, sodium (sub)sulfate, etc. that are soluble in water are introduced into the solution; under optimized conditions, the arsenic leaching rate can reach more than 95%, providing a high-concentration arsenic-containing solution for subsequent steps, and the effect is evaluated by indicators such as arsenic leaching rate, impurity removal rate, leaching solution concentration and purity.

3. The method for treating arsenic alkali slag according to claim 1, characterized in that: The second step is to obtain a mixed salt containing sodium arsenate by evaporating and drying the sodium arsenate, soda ash and sodium sulfate in the water-soluble substances.

4. The method for treating arsenic alkali slag according to claim 1, characterized in that: In the step three, the water-insoluble silicon dioxide, aluminum oxide, antimony, arsenic and other substances are filtered through a plate and frame filter press, and then sintered to extract the antimony, arsenic and other substances therein, and the slag is sent to the cement plant as raw materials.

5. The method for treating arsenic alkali slag according to claim 1, characterized in that: In step 4, at high temperature, the arsenic mixed salt reacts with quartz sand (SiO2) to generate sodium silicate, thereby achieving material conversion. The sodium silicate solid is subjected to post-treatment processes such as elution, dehydration, and drying to obtain the final sodium silicate product, with an arsenic conversion rate of up to 97% and a sodium silicate water glass purity of 99.5%.

6. The method for treating arsenic alkali slag according to claim 1, characterized in that: The sodium arsenate and sodium sulfate can be decomposed by the alkaline oxide in the sodium carbonate, and the reaction equation is as follows: Na2CO3+Na2HAsO4→Na3AsO4+CO2↑+H2O Na2CO3+Na2SO4→2Na2SO4+CO2↑ At the same time, silicon powder will also react with the pyrolyzed sodium carbonate at high temperature to generate sodium silicate: SiO2+2Na2CO3→Na4SiO4+2CO↑.

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