Metalloid elements such as As, Sb, Bi, Se and Te in the molten metal, alloy, matte, slag and speiss phases are of great concern in the metallurgy of copper, lead, tin and nickel and the recycling of these metals. The activity data of these elements are very important for thermodynamically considering or evaluating the processes to recover or remove these valuable or detrimental elements. Based on the knowledge and experiences made by the authors in the past decades, the methods and techniques for determining the activity of these metalloid elements in the molten metallurgical systems, such as non-isothermal isopiestic, isothermal isopiestic, tranportation, Knudsen-effusion and electro-motive force measurement methods are briefly surveyed. Some applications of the activity data to derive the activity coefficients in the molten slags and to thermodynamically evaluate the behavior of As, Sb and Bi in the matte smelting of copper are also described in the present paper.
Japan Atomic Energy Agency has been conducting in situ stress measurements using overcoring method, within the context of establishing a firm scientific basis for safe geological disposal of high-level radioactive waste. Core disking has been observed during rock stress measurements performed using the Compact Conical-ended Borehole Overcoring Technique in borehole with inflow excavated at 200m depth at the Mizunami Underground Research Laboratory. In this report, applicability of measurement tool against inflow and failure initiation of core disking is discussed.
The extraction of metals from printed circuit board waste (PCBW) in an autoclave at a high temperature and high oxygen pressure was studied for the purpose of metal recycling. Metals were extracted from the crushed PCBW sample in 1.0mol/L H2SO4 solution under the optimum extraction conditions at a pressure of 2MPa, temperature of approximately 120°C, retention time of 0.5h respectively and in the case of 100g/L pulp density. The extraction rates of Cu, Ni, Mn and Co were over 95%, those of Zn and Al were up to 94%, and over 80% of Cr was dissolved into the solution. Several methods of selective metal recovery from extracted solution involving neutralization, sulfidation, and solvent extraction were investigated in this study. Over 99% of Cu in the solution was precipitated as CuS by sulfidation using NaHS. Zn and Co were recovered by solvent extraction at pH values of 2.4 and 4.2 respectively, using extractant PC88A. Cr and Al were precipitated as hydroxides by neutralization at pH6 using powdered CaCO3. Ni was recovered by solvent extraction at pH 6.0 using extractant LIX84I. Mn was recovered as its hydroxide by neutralization at pH10.3.
The surface smoothness, S and Ag content of electrodeposited copper were investigated to clarify the influence of chloride ions on electrorefining using hydrochloric acid and SbCl3. The surface smoothness of electrodeposited copper was improved with increasing amounts of hydrochloric acid and SbCl3 as well as lower S and Ag content. The tensile strength and elongation of the electrodeposited copper were also studied to determine if they could be used as criteria for evaluating the cathode strippability in the permanent cathode process. The tensile strength and elongation increased when the total concentration of chloride ions released from hydrochloric acid and SbCl3 was 20 mg/L. Metallographic observations indicated that lower rate of twin crystal formation resulted in higher tensile strength and elongation at approximately 20 mg/L of chloride ion concentration.