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Method for comprehensively recovering calcium and arsenic from calcium arsenate/calcium arsenite precipitate

A calcium arsenite and sediment technology, applied in the field of metallurgy, can solve the problems of high disposal cost, unstable chemical properties, unstable sediment, etc., and achieve the effect of small footprint

Active Publication Date: 2021-04-06
YUNNAN CHIHONG ZINC & GERMANIUM +1
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Problems solved by technology

[0004] It can be seen from the previous patents and the research status at home and abroad that most arsenic fixation technologies use lime precipitation method (atmospheric pressure method, hydrothermal method), and other methods include scorodite method and vitrification method; these technologies are all There are certain defects: (1) The lime precipitation method is a commonly used treatment method for arsenic sulfide slag and arsenic-containing wastewater. This method uses lime to precipitate arsenic in the solution, and then produces arsenic-containing intermediate products-calcium arsenate or arsenous acid Calcium; the main component of calcium arsenate is a mixture of calcium hydroxide and calcium arsenate. The calcium salt of arsenic has a high solubility and is not stable in chemical properties. Pay high environmental protection tax per ton; therefore, due to environmental protection and economic considerations, it is imminent to realize the economical, environmental protection, safe and harmless disposal of calcium arsenate slag
(2) The scorodite method is to oxidize the arsenic precipitate in the iron-containing solution through normal pressure or pressurized hydrothermal reaction to form scorodite crystals and solidify them. Since there are many types of scorodite crystal forms, a stable crystal form is formed. Scorodite has harsh conditions (usually it can be formed under pressurized hydrothermal conditions with a temperature above 160°C), so there are usually some easily soluble scorodite, which has high disposal costs, unstable sediments, and harsh conditions. (3) Although the vitrification method realizes the harmlessness of arsenic by solidifying arsenic through high-temperature transformation, because arsenic is extremely volatile, the process control needs to prevent the secondary volatilization of arsenic from polluting the environment, and usually requires heating Calcium arsenate solid is melted with other slag (Si, Fe, Na, etc.) at 1200°C and then solidified, so there are problems such as high energy consumption cost, poor economy, and secondary pollution of arsenic
[0005] Based on the above analysis, most of the current arsenic-containing wastewater treatment adopts lime precipitation method, and the scorodite method and vitrification method used essentially solidify unstable calcium arsenate or calcium arsenite, which has not been realized as a resource. Therefore, The disposal of arsenic-containing wastewater or arsenic slag is mainly how to achieve its harmless, economical and environmentally friendly goals

Method used

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  • Method for comprehensively recovering calcium and arsenic from calcium arsenate/calcium arsenite precipitate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031]The raw material employed in this embodiment was added to the lead anode mud oxine soaking solution to the theoretical amount of 1.5 times lime, and the calcium arsenate, which was 27.75% arsenic.

[0032]100.00 g of calcium arsenate is added to 800 ml of water, mechanically stirred to form a slurry, and the molar ratio of calcium carbon dioxide gas, carbon dioxide and calcium carbon dioxide and calcium carbon dioxide and calcium carbon dioxide and calcium carbon dioxide is 5: 1, carbon dioxide. After the time was 480min, after the reaction, the mixed slurry was solid separated to give calcium carbonate and arsenic solution, and the arsenic content in the calcium carbonate was 0.4%; the arsenic solution was evaporated and crystallized, at the temperature of 1200 ° C, Time 90min, the reducing agent is coke, and the carbon heat reduction is carbonized under the conditions of C / As molar ratio, and 99.1% of metal arsenic is prepared.

Embodiment 2

[0034]The raw material employed in this example is to add arsenic wastewater to a theoretical amount of 1.3 times lime, and a mixture containing calcium arsenate is 25.13% of the mixture.

[0035]A mixture of 100.00 g of calcium containing mercycium arsenic acid was added to the water, mechanically stirred to form a slurry, with a carbon dioxide gas, carbon dioxide, calcium carbon dioxide and calcium carbonate and calcium carcium carbonate and calcium carbonate. When the ratio is 5: 1, the carbon dioxide is transferred for 240 minutes. After the reaction, the mixed slurry is liquidally solidified to obtain calcium carbonate and arsenic solution; the amount of arsenic in calcium carbonate is 0.2%; containing arsenic solution evaporation After crystallization, the temperature was 1100 ° C, the time was 60 min, and the reducing agent was graphite, and the reducing agent was carbonized under conditions of C / A molar ratio of 3 times, and 99.2% of metal arsenic was prepared.

Embodiment 3

[0037]The raw material employed in this example is to add the theoretical amount of 1.8-fold lime to the lead anode mud, which is obtained by a mixture of calcium arsenate, which contains 19.35%.

[0038]100.00 g of calcium arsenate is added to 800 ml of water, mechanically stirred to form a slurry, with a molar ratio of calcium carbon dioxide gas, carbon dioxide and calcium carbon dioxide and calcium carbon dioxide and calcium carbonate and calcium carbonate and calcium carbonate at 3:00 1. The carbon dioxide is 300 min. After the reaction, the mixed slurry is liquidally solidified to obtain calcium carbonate and arsenic solution; the amount of arsenic in calcium carbonate is 0.3%; the arsenic solution is evaporated by evaporation, The temperature is 900 ° C, the time is 150 min, the reducing agent is coal, and the reducing agent is carbon-heat reduction under conditions of C / A molar ratio of 2.0 times, and 99.0% metal arsenic is prepared.

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Abstract

The invention relates to a method for comprehensively recovering calcium and arsenic from calcium arsenate / calcium arsenite precipitate. The method comprises the following steps that (1) the calcium arsenate / calcium arsenite precipitate is mixed with water according to a liquid-solid ratio of (2-10):1 for size mixing, carbon dioxide gas is introduced at a leaching temperature of 25-100 DEG C, and the calcium and arsenic precipitate reacts with an aqueous solution of carbon dioxide to obtain mixed slurry; liquid-solid separation is performed on the mixed slurry to obtain a calcium carbonate solid and an arsenic-containing solution; the calcium carbonate solid is dried and dehydrated to obtain a calcium carbonate product; (2) the arsenic-containing solution is concentrated, crystallized and dried to obtain As2O5 or As2O3 solid; and (3) carbon is added into the obtained As2O5 or As2O3 solid for high-temperature carbon thermal reduction to obtain metal arsenic and carbon dioxide gas. Harmless, recycling and environment-friendly treatment of the calcium-arsenic precipitate is realized in the whole process.

Description

Technical field[0001]The present invention belongs to the field of metallurgical technology.Background technique[0002]Arsenic is a toxic element, mainly in the form of sulfide, with other metals such as: lead, zinc, copper or the like, producing a large amount of vulcanization during non-ferrous metal smelting and sulfuric acid industrial flue gas acid Arsenic and high (low) arsenic wastewater. These sulfurized arsenic and arsenic wastewater must be removed in a stable compound, so the removal of arsenic in the field of colored metal smelting and the harmless disposal technique has always been a hot spot.[0003]Patents, currently arsenic, calcium-containing, calcium arsenate or arsenate decomposition, and a method of decomposition of calcium arsenate: (1) Patent CN201010138190 provides a method of calcium calcium-converted synthesis of arsenate: referring to a car arsenic or solution The arsenic is converted and combined with oxygen pressure and is a method of insoluble in arsenate; ...

Claims

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Application Information

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IPC IPC(8): C22B30/04C22B5/10C01F11/18
CPCC22B30/04C22B5/10C01F11/18Y02P10/20
Inventor 杨大锦付维琴贾著红刘俊场马雁鸿邹维李衍林谢天鉴张候文牟兴兵代龙果翟忠标
Owner YUNNAN CHIHONG ZINC & GERMANIUM
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