Optimization on selenium and arsenic conversion from copper anode slime by low-temperature alkali fusion process

A process was proposed to convert and separate selenium and arsenic in copper anode slime (CAS) by low-temperature alkali fusion process. Central composite design was employed to optimize the effective parameters, in which NaOH/CAS mass ratio, fusion temperature and fusion time were selected as variables, and the conversion ratio of selenium and arsenic as responses. Second-order polynomial models of high significance and 3D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of > 90% selenium conversion ratio and > 90% arsenic conversion ratio was obtained by the overlaid contours at NaOH/CAS mass ratio of 0.65-0.75, fusion temperature of 803-823 K and fusion time of 20-30 min. The models are validated by experiments in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the fusion process.