| 초록 |
Refining is the process by which the impurity level of a particular metallic system is reduced to the required grade so as to eliminate the trace impurity effect on the property corresponding to its use. Metal of the type commonly referred to as commercial-purity is normally used as the starting material in ultra-purification operations. Depending on the metal in question, commercial purity usually means a purity between 99.0 and 99.95%. Commercial-purity metal can be prepared by a variety of processes. The two basic approaches to the refining of metals are as follows: Production of high purity metal compounds and their subsequent reduction to very pure metal(useful in case of very reactive metals). This can be achieved through various means in which some are physical(sublimation, distillation, crystallization)and some are chemical (precipitation, ion exchange, solvent extraction, etc.,) Production of bulk metal from metal ore, ensuring maximum recovery, and then purity the metal to the required extent(Eg. Selective distillation, liquation, electrolytic refining, zone refining, etc.) |
