ソーダ系フラックスによる粗銅中の不純物除去

抄録

Removal of impurities, V-groupe elements (As, Sb, Bi), oxygen and sulfur in crude copper during Na, CO, -treatment nas been investigated in order to propose the new process of copper refining. The test were carried out by molten comer (15g) and tne various compositions ot Na₂CU₃-SiO₂ flux (5g) in an alumina crucible at 1150-125°C in air and Ar.
V-groupe elements, especially As, Sb, were rapidlyremoved from crude copper melts by Na₂CO₃-treatment. For example, the arsenic level in the copper dropped sharply from 1750 ppm to 150 ppm after 30 min. The elimination of V-groupe elements increases with increasing the basicity of flux and lowering the temperature of treatment. On the other hand. the atmosnhere of treatment seems to have little influence on the elimination of impurities in these tests.
It was found that the oxygen and sulfur in crude copper were rapidly removed like the arsenic during Na, CO₃-treatment. Thus, it is considered that V-groupe elements are fixed in flux by being oxidized with the oxygen in the crude copper melts and the oxygen ion in flux. The removal reaction of As and Sb seems to be shown as following equation (1).
2M+5O+O²=2MO₃^-.(1)
M: V-groupe element in crude copper. O: Oxygen in crude copper. O^2-: Oxygen ion in flux. MO₃^-: Anion of V-groupe element in flux.