Separation And Extraction Of Selenium From High Selenium, Tellurium And Precious Metal-rich Compound, Tellurium Study

In the treatment process of copper anode slime, the material, which is rich in gold, platinum, palladium, selenium and tellurium would be produced as the method of sulfated roasting, high pressure leaching, aqueous leaching, or combined with dressing-metallurgy. It is decisive significance of extraction of precious metals to separate Se, Te with precious metals. There is more great significance of reused scarce resources to recover the Se and Te.According to the reference, the similar methods with this study as follows:sulfated roasting, alkaline leaching, oxidation-acid leaching, combined with dressing-metallurgy, aqueous leaching, high pressure leaching, these treatment processes with all of which can not make sure the recovery of Se and Te, at the same time, much precious metals are lost when it not scattered in the recovery process of Se and Te, and it is hard to recovered. In this paper, in order to make the Se & Te and the precious metals stay into the solution and solid, respectively, the method of low-temperature roasting-alkaline leaching for recovery of Se & Te are proposed.In this study, the Se & Te are separated with precious metals from the rich material though the method of roasting-alkaline leaching. Firstly, the characteristics of Se & Te in the rich material can be made sure by X-ray diffraction analysis and detection. Anglicizing the phase, some exploratory experiments are carried out, and then, the conditions and orthogonal experiments are following. In those study, various factors to assure the higher leaching rate of Se & Te, when the precious metals remain in the residue is not oxidized. The factors include baking temperature, baking time, the amount of NaClO3 and Na2CO3 added, leaching temperature, leaching time, NaOH concentration, and ratio of liquid to solid. The results shows that under the condition of baking temperature 600℃, baking time 2.5 h, rich material and NaClO3, Na2CO3 mass ratio 10:1/10:7, respectively, leaching temperature 75℃, leaching time 2.5h, NaOH concentration of 10%, liquid to solid ratio 5:1. After roasting-alkaline leaching, there is extraction rate of 95% for Se & Te, as the precious metals remain in the solid phase.At the same time, the separation techniques of Se & Te are studied in the recovery process of Se & Te. The detailed experimental study included that how the pH and amount of Na2SO3 effect the co-precipitation of Se & Te. The results show that, when the impurity being removed from leaching solution and controlling the pH from 5.5 to 6, most of the Se and Te can be precipitated. The concentrations of Se and Te in the precipitation solution were 0.15g/L and 0.1Og/L, respectively. Under the condition of m (Se):m (Na2SO3) 1:8, the Se can be leaching out and the rate reaching to more than 90%, so the Se and Te were well separated.