Abstract: An improved process is disclosed for the treatment of molybdenite concentrate to remove impurities, such as copper and lead therefrom. According to this process, ferrous chloride liquor is introduced into a reactor which is made of a material that can withstand leaching with the use of ferric chloride at elevated temperatures and pressures. Sodium or calcium chloride may also be added to the reactor which is then sealed and subjected to chlorination until the rise in temperature, due to the exothermicity of the reaction, produces the desired concentration of the ferric ion to leach the impurities present in the concentrate to a desired level. Upon completion of the chlorination, the molybdenite concentrate is introduced into the reactor and is leached therein. Finally, the resulting pulp is filtered and washed to obtain the desired purified product.

Abstract: A method and a system are disclosed for maintaining optimum throughput in a grinding circuit of the type in which fresh ore is fed to a rod mill and the ground ore from the rod mill, together with the ground ore from a ball mill operated in a reversed circuit, are combined in a pump box and pumped to a cluster of hydrocyclone classifiers. The rod mill is operated in open circuit but the ball mill is operated in closed circuit with the cyclone classifiers which serve to classify the mill discharge material, returning the oversize to the ball mill. The system comprises monitoring devices for sensing the cyclone classifier feed density and any one or combinations of the following conditions of the grinding circuit: (1) rod mill sound, (2) ball mill sound, (3) pump box level, and (4) cyclone overflow particle size and density.