Mitsuhisa Hino

Arsenic activities in molten copper and copper sulfide melts

In recent years, the concentration of the group Va elements such as arsenic, antimony, and bismuth has been increasing in copper concentrates. The elimination and recovery of these elements during the copper smelting process have presented serious problems. While the distribution of minor elements has been studied extensively, very little knowledge exists on the activities of these minor elements in copper mattes. Consequently, in this study the activities of arsenic were measured to determine activity coefficients of arsenic in the dilute solution region of molten copper, in Cu2S saturated copper, and in copper mattes equilibrated with copper at 1423 K by a mass spectrometric Knudsen effusion technique.

Antimony activities in copper mattes

A mass spectrometric technique combined with a double Knudsen cell was used to determine the antimony and copper activities in the Cu-Sb binary system at 1373 K and in the two-melt composition range of the Cu−S−Sb ternary system at 1423 K. The antimony and copper activities were calculated based on the intensity ration of the gaseous Sb and Cu species, over the unknown and known activity samples, respectively. γSbo were found to be 1.1×10−2 in molten copper at 1373 K, and 1.8×10−2 and 0.44 in a copper-rich phase and in a matter phase, of the Cu−S−Sb ternary system at 1423 K, respectively. These values indicate, that antimony can be removed during the matte smelting and slagging stage of the copper smelting process. Interaction parameters of antimony in molten copper slagging stage of the copper smelting process. Interaction parameters of antimony in molten copper at 1423 K were calculated and found to be 10.7, −5.4, and 6.3 for εSbSb · ρSbSb, and εSbS, respectively.

Recycling. Fundamental Study on Extraction and Separation of Nickel and Cobalt from Stainless Steel by Using Tin as Solvent.

Construction materials in a shutdown nuclear power plant contain radio activated nickel and cobalt in iron alloys such as stainless steel. The separation of nickel and cobalt from the alloy is required to reduce storage volume of the activated materials. In order to obtain fundamental information on the separation of nickel and cobalt from the stainless steel, the extraction method by using metallic tin as a solvent was studied at 1, 673 K. The following results have been obtained.By addition of tin and silicon to the stainless steel, phase separation to the metallic tin phase and the stainless steel phase dissolving silicon occurs, and the minimum mutual solubility between the two phases was obtained at 23 mass% Si in the stainless steel phase at 1, 673 K. The distribution ratio of nickel in the tin to stainless steel phases decreases extremely from 0.5 to 0.05 with increasing silicon content from 10 to 23 mass% in the stainless steel phase while the distribution ratios of cobalt and iron represent almost 1/10 of the nickel value. The separation coefficient of nickel shows the minimum value of 8 at 23 mass% Si in the Fe-Si phase while cobalt exhibits almost 2 in the experimental composition region. Based on the experimental results, the extraction and separation process for nickel and cobalt by using metallic tin as a solvent is evaluated at 1, 673 K.