Hydrothermal mineralized arsenic precipitation in H3AsO4-FeSO4-K2SO4-H2O system
Received:October 13, 2022   Revised:October 13, 2022   Accepted:October 13, 2022      Published Online:April 21, 2023
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KeyWord:hydrothermal system;mineralized arsenic precipitation;scorodite;arsenic precipitation rate;
                    
AuthorInstitution
luojingsong Kunming University of Science and Technology
licunxiong Kunming University of Science and Technology
zhangzhaoyan Kunming University of Science and Technology
dengge Southwest Copper Branch of Yunnan Copper Co., Ltd.
caoyuandong Yunnan Copper Science Technology Development Co.,Ltd.
liyudong Southwest Copper Branch of Yunnan Copper Co., Ltd.
tangxiaoming Yunnan Copper Science Technology Development Co.,Ltd.
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Abstract:
      The effects of K+ on precipitation rate of arsenic and ferric, phase and chemical composition of As-bearing precipitate, and phase transition behavior were studied during hydrothermal mineralized arsenic precipitation in H3AsO4-FeSO4-K2SO4-H2O system. The results show that the presence of K+ in the system has a significant effect on composition of As-bearing precipitate. In addition to co-precipitation with As (V) to form scorodite (FeAsO4?2H2O) and self-hydrolysis precipitation to basic ferric sulfate Fe(OH)SO4, supersaturated Fe (III) will also competitive precipitation with K+ in the form of K-jarosite(KFe3(SO4)2(OH)6). With conditions of the initial concentration of K+ 5 g/L, arsenic concentration 10 g/L, iron-arsenic molar ratio 1.5, solution pH 1, reaction temperature 160℃, agitation speed 500 r/min, reaction time 3 h, and the oxygen partial pressure 0.6 MPa, the precipitation rates of As and Fe were 96.7 % and 96.5 %, respectively, and the phase compositions of As-bearing precipitate were mainly scorodite, jarosite and basic ferric sulfate, the contents of which were 65.0 %、24.2 % and 10.8 %, respectively, the content of As, Fe, K and S in arsenic slag was 23.39 %、25.72 %、1.84 % and 4.09 % , respectively. The formation of metastable state K-jarosite phase can be effectively inhibited by controlling the initial iron-arsenic molar ratio in a reasonable range, so as to achieve efficient precipitation of arsenic, increase the arsenic content in As-bearing precipitate and reduce its yield.
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