Synthetic method for preparing arsenic trioxide through using arsenic-containing wastewater

A technology for the synthesis of arsenic trioxide and arsenic trioxide, which is applied in the field of synthesis of arsenic trioxide from arsenic-containing wastewater, achieving the effects of reducing pollutant discharge, low cost, and simple process

Active Publication Date: 2013-07-17
ZHEJIANG RONGYAO CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, the lime neutralization and iron salt coagulation sedimentation method cannot recover valuable metals, and a large amount of arsenic-containing waste residue needs to be safely landfilled, which is a hidden danger of secondary pollution.

Method used

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  • Synthetic method for preparing arsenic trioxide through using arsenic-containing wastewater

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Take 5000L of arsenic-containing wastewater intercepted by membrane separation technology, the arsenic content of 15000mg / L, pH = 7 wastewater, adjust the pH to 12.0 with alkali, stir for 30 minutes, slowly add 100kg of reducing agent hydrazine hydrate under stirring, and control the temperature At 60°C, react for 6 hours, the tail gas produced during the reaction is absorbed by the reaction absorption tower, and the content of pentavalent arsenic is reduced from the original 1.5% to 0.2% by sampling. It is concentrated, the concentrated solution is concentrated to 1 / 4 of the total volume, the pH is adjusted to 2.5 with acid, stirred, slowly cooled to 40°C to crystallize, filtered, and the filtrate is recycled. The filter cake is 90kg of arsenic trioxide, with a detection content of 94.5%.

Embodiment 2

[0025] Take 5000L of arsenic-containing wastewater intercepted by membrane separation technology, the wastewater with arsenic content of 45000mg / L and pH=8, adjust the pH to 10.0 with alkali, stir for 30 minutes, slowly add 200kg of reducing agent hydrazine hydrate under stirring, and control the temperature At 80°C, react for 10 hours, the tail gas generated during the reaction is absorbed by the reaction absorption tower, and the content of pentavalent arsenic is reduced from the original 4.5% to 0.3% by sampling. It is concentrated. Concentrate the concentrated solution to 1 / 4 of the total volume, adjust the pH to 3.0 with acid, stir, slowly cool to 40°C to crystallize, filter, and recycle the filtrate. The filter cake is 282kg of arsenic trioxide, with a detection content of 98.2%.

Embodiment 3

[0027] Take 5000L of arsenic-containing wastewater intercepted by membrane separation technology. The arsenic content is 15000mg / L and the pH=7 wastewater. Adjust the pH to 12.0 with alkali and stir for 30 minutes. Slowly add 100kg of formic acid as a reducing agent while stirring, and control the temperature at 60°C, reacted for 6 hours, the tail gas generated during the reaction passed through the reaction absorption tower to absorb the tail gas, and the content of pentavalent arsenic was reduced from 1.5% to 0.2% by sampling. Concentrate. Concentrate the concentrated solution to 1 / 4 of the total volume, adjust the pH to 2.5 with acid, stir, slowly cool to 40°C to crystallize, filter, and recycle the filtrate. The filter cake is 87kg of arsenic trioxide, with a detection content of 98.6%.

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Abstract

The invention discloses a synthetic method for preparing arsenic trioxide through using 3-nitro-4-hydroxyphenylarsonic acid wastewater as a raw material. The method comprises the following steps: carrying out pretreatments comprising pH value adjustment, cartridge filtration and the like of arsenic-containing wastewater, allowing the obtained pretreated wastewater to enter the feed liquid cycle tank of a membrane experiment apparatus, and intercepting high-content arsenic-containing wastewater; adjusting the pH value of the obtained high-content arsenic-containing wastewater to 10-12 by using an alkali, adding a reducing agent A to reduce pentavalent arsenic to trivalent arsenic, and carrying out a reaction at 40-80DEG C for 6-10h; allowing a tail gas generated in the reaction to go through a reaction absorption tower for absorbing the tail gas; and concentrating a reaction liquid obtained after the reaction by adopting a triple effect concentrator to a volume being 1 / 4 of an original volume, adjusting the pH of the obtained concentrate by using an acid, stirring for slowly cooling to 40DEG C for crystallization, and filtering to obtain arsenic trioxide powder. The synthetic method for preparing arsenic trioxide through using wastewater as a raw material has the advantages of simple flow, low raw material investment, low cost, no generation of wastes, and environmental protection.

Description

technical field [0001] The invention belongs to the field of chemical industry, in particular to a synthesis method for preparing arsenic trioxide from arsenic-containing wastewater. Background technique [0002] Arsenic and its compounds seriously damage human health, and have been identified as the first class of carcinogens by the Centers for Disease Control and Prevention of the United States and the International Research Institute, mainly endangering human health through drinking water. Therefore, China, the United States, Western Europe, Japan and many other countries have listed arsenic as one of the priority water pollutants. In recent years, with the rapid development of industries such as mining, metallurgy, ceramics, crystal glass, leather, and pesticides, the amount of arsenic-containing wastewater is increasing, and the emission and pollution of arsenic to the environment are increasing. [0003] The main methods for treating arsenic-containing wastewater incl...

Claims

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Application Information

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IPC IPC(8): C01G28/00
Inventor 陈建华吴凤洁詹峰董鑫黄云奇陈仁尔
Owner ZHEJIANG RONGYAO CHEM
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