Study On Comprehensive Recovery Of Valuable Resources In Arsenic Alkali Residue From Antimony Smelting

Abstract:Arsenic alkali residues originate from procedure of removing As by adding Na2CO3in antimony smelting, in which there are a large amount of toxic and soluble Na3AsO4, Na2CO3and Sb dangerous to environmental and human-being health. At present, the total amount of piling arsenic alkali residue in China was more than200thousand tons. New technologies should be developed to safely treat arsenic alkali residue and recover the valuable metals to get rid of the potential threaten to the environment from it.In this thesis, the lab-, pilot-and full-scale researches were carried out to deal with the historical piling secondary piling arsenic alkali residue. Three critical technologies of "Deep separation of As and Sb", high effective separation of As and alkali, and "effective drying of Na3AsO4" broke through to develop new technology including " two steps leaching separation of As and Sb","deep separation of As and Sb by oxidation","primary crystallization separation of As and alkali","dissolution separation of As and alkali","microwave drying of Na3As04" to recover the value resources in the arsenic alkali residue, such as As, Sb and alkali.The results indicated that two-step leaching with optimum conditions like particle size, rate of solid to liquid, leaching time, leaching temperature, can reduce the content of As in the leaching residue to0.6%. By using H2O2, the Sb content in the leachate was then decreased to0.5g/L with14%orate of solid to liquid,20min feeding time,60min reaction time,80℃reaction temperature as optimum conditions. Through "two steps leaching separation of As and Sb" and "deep separation of As and Sb by oxidation" technologies,95.27%of Sb and97.7%of As were recovered and leached out respectively, which means the separation of Sb and As.The experiments on "primary crystallization separation of As and alkali" and "dissolution separation of As and alkali" technologies were carried out to obtain optimum conditions including3times crystallization (1.36-1.40kg/L solution density for the first,1.42-1.45kg/L for the second and1.50-1.55kg/L solution density for the third),80～90℃reaction time,180mincrystallizationtime for the "primary crystallization separation of As and alkali" and80℃dissolutiontemperature,3for rate of liquid to solid,10min dissolution temperature,3times cycle of saturated solution of sodium carbonate for the "dissolution separation of As and alkali". By using above the technologies, the As and alkali were successfully separated with the result of0.6%As, up to77.86%Na2CO3in the treated solution.Microwave drying were used to desiccate the Na3AsO4with merit of high efficiency, which solve the problem of plugging and low efficiency to traditional drying technology.The full-scale experiment proved that the new technologies has the capability to recover the above95%of Sb and As from the arsenic alkali residue. The leaching residue and oxidation residue can be retreated in the Sb-smelting system. The alkali can be reutilized as ingredient during the reducing smelting in reverberatory furnace, or be sold out as products for glass-manufacture industrials. Na3AsO4was also a glass refining agent for glass-manufacture industrials. There are no waste solid, no wastewater, no gaseous pollutants produced in the new technologies.