Study On The Phase Change Of Selenium-containing Substances In Copper Anode Slime During Selenium Distillation

Selenium is mainly recovered from copper anode slime,of which the researches mainly emphasis on improving recovery technology at present,while the researches on phase change of selenium in the recycling process are paid less attention.Therefore,deep study on the phase change process of selenium compounds in evaporating selenium process of sulfating roasting of arsenic-free and antimony-free copper anode slime are conducted in this thesis,in order to provide a theoretical basis for optimizing the roasting process of copper anode slime and the selenium recovery.Thermodynamic analysis was carried out using Factsage and HSC software,the effects of different roasting atmosphere,roasting temperature,roasting time and acid to ore ratio on the phase change of selenium-containing materials during sulfating roasting and evaporating selenium of copper anode slime were analyzed by X-ray diffraction(XRD).The following conclusions are obtained:(1)Through the detection and analysis of the main elements and occurrence state in copper anode slime,the selenium containing selenium are mainly Se-Cu compounds(Cu Se₂,Cu Se and Cu₂Se)and Se-Ni compounds(Ni Se and Ni₃Se₄).(2)A series of thermodynamic theoretical calculations and analyses were carried out on evaporating selenium from copper anode sludge in sulfuric acid roasting.The results show that the removal of arsenic and antimony before evaporating selenium is beneficial to the recovery of subsequent selenium.It is necessary to decompose the selenium compounds in copper anode slime with sulfuric acid,and the oxidation and decomposition of the selenium phase can be realized by controlling the roasting temperature at 400?500°C.With the increase of temperature,the Se-containing phase Ni Se,Cu₂Se,Cu Se₂,Cu Se and Ni₃Se₄is oxidized and decomposed in turn.(3)The effects of roasting time,roasting temperature and acid-ore ratio on selenium-containing compounds were studied in air,oxygen-enriched atmosphere and vacuum respectively.The results showed that extending roasting time,increasing roasting temperature,increasing acid-ore ratio and using oxygen-enriched atmosphere were beneficial to the decomposition of selenium-containing compounds.When the evaporating selenium temperature of copper anode slime was controlled at 400?500°C,the selenium containing compounds Ni Se,Cu₂Se,Cu Se,Cu Se,and Ni₃Se₄were oxidized and decomposed in turn,and selenium volatilized in the form of Se O₂.The effect of air,oxygen enriched atmosphere and vacuum on the remover process of selenium in copper anode slime is as follows:oxygen enriched atmosphere>air atmosphere>vacuum atmosphere.