Statistical modeling of Chevreul's salt recovery from leach solutions containing copper

摘要

In this study,oxidized copper ore was dissolved under optimum conditions [temperature 14 deg C,average particle size 2.8 mm,stirring speed 500 rpm,ammonia concentration 2.824 molL~(-1) ammonium sulphate concentration 0.236 molL~(-1),solid-to-liquid ratio 0.167 gmL~(-1),leaching time 2 h] in an aqueous NH_3-(NH_4)_2SO_4 solution [T.Calban,S.Colak,M.Yesilyurt,Optimization of leaching of copper from oxidized copper ore in NH_3-(NH_4)_2SO_4 medium,Chem.Eng.Commun.,in press].Chevreul's salt was precipitated by passing SO_2 from these leach solutions.Chevreul's salt,a mixed valence copper sulfite Cu_2SO_3 centre dot CuSO_3 centre dto 2H_2O,was characterized by XRD and SEM.The effects of parameters,such as temperature,pH,stirring speed and reaction time,were investigated on precipitation of Chevreul's salt.2~n factorial experimental design and orthogonal central composite design methods in the precipitation experiments were used.It was observed that the most effective parameters on the precipitation of Chevreul's salt were temperature,stirring speed and reaction time.The optimum conditions established for maximum copper precipitation were:temperature 62 deg C,pH 3,stirring speed 600 rpm,reaction time 12 min.Fixed parameters chosen at the initial stage of the reaction were:SO_2 flow rate 358 Lh~(-1),concentration of CuSO_4 solution 7.383 g Cu L~(-1).Under these optimum conditions,the percentage of copper precipitated from leach solution was 99.92.