摘要
针对当前砷碱渣处理过程砷碱分离效果差、分离的砷酸钠或钙砷渣安全处置难等问题,提出“水浸-水热沉砷-碳热还原”回收金属砷新工艺。以湖南某冶炼厂砷碱渣为对象,开展砷碱渣水浸砷锑分离、氧化钙水热沉砷砷碱分离、沉砷渣碳热还原回收金属砷等环节的工艺研究。研究结果表明:在浸出时间30 min、液固比3:1、浸出温度45℃、搅拌速度600 r/min的水浸条件下,砷、锑浸出率分别为95.3%和1.6%。在初始pH=11、水热温度180℃、反应时间6 h、Ca/As物质的量比为24:1的水热沉砷条件下,沉砷率达95.3%,沉砷渣主要为碳酸钙、氢氧化钙和砷酸钙。在碳粉添加量10%、温度1 000℃、还原时间3 h条件下,砷挥发率为93.1%,挥发产物砷质量分数达92.0%。砷碱渣“水浸-水热沉砷-碳热还原”新工艺,具有可实现砷锑碱梯级分离、砷以无毒的单质砷回收、沉砷剂氧化钙可循环使用、全流程未引入难处理的阴阳离子等优点。
In view of the problems in the current arsenic-alkali residue treatment process such as poor separation efficiency of arsenic and alkali and the difficulty in safe disposal of the separated sodium arsenate or calcium arsenic slag, a new process of "water leaching-hydrothermal precipitation of arsenic-carbon thermal reduction" was proposed for the recovery of metallic arsenic from arsenic-alkali residue. The arsenic-alkali residue from a smelter of Hunan Province was used as experimental object to study the process of separation of arsenic and antimony by water leaching, the separation of arsenic-alkali by hydrothermal precipitation of calcium oxide and the recovery of metallic arsenic by carbon thermal reduction. The results show that the arsenic and antimony leaching efficiencies reach 95.3% and 1.6%, respectively, under the water leaching conditions with leaching time of 30 min, liquid-solid ratio of 3 : 1, leaching temperature of 45 ℃ and stirring speed of 600 r/min. Under the conditions of hydrothermal arsenic precipitation with an initial pH of 11, hydrothermal temperature of 180 ℃,reaction time of 6 h and Ca/As molar ratio of 24:1, the arsenic precipitation efficiency reaches 95.3%. Moreover,the precipitation residue is mainly composed of calcium carbonate, calcium hydroxide and calcium arsenate. In the carbon thermal reduction of arsenic-containing precipitation residue, the arsenic volatilization efficiency is 93.1%and the arsenic content in the volatilization product reaches 92.0% under the conditions with carbon powder addition of 10%, temperature of 1 000 ℃ and time of 3 h. The new process of "water leaching-hydrothermal arsenic precipitation-carbon thermal reduction" has the advantages of achieving a stepwise separation of arsenic,antimony and alkali, the recovery of arsenic as non-toxic metallic arsenic, the recycling of the calcium oxide,without introducing anions and cations in the whole process.
作者
柯勇
曹俊杰
李童冰
李燕春
邓承宇
余林
闵小波
KE Yong;CAO Junjie;LI Tongbing;LI Yanchun;DENG Chengyu;YU Lin;MIN Xiaobo(School of Metallurgy and Environment,Central South University,Changsha 410083,China;Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution,Changsha 410083,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2023年第2期495-505,共11页
Journal of Central South University:Science and Technology
基金
湖南省重点研发计划项目(2019SK2291)
国家重点研发计划项目(2019YFC1907405,2020YFC1909204)
湖南省科技创新计划项目(2021RC3013)。
关键词
砷碱渣
砷锑碱分离
水热沉砷
金属砷
回收
arsenic-alkali residue
separation of arsenic
antimony and alkali
hydrothermal precipitation of arsenic
metallic arsenic
recovery
