Manufacture of Silicon Carbide Retorts

A METALLURGICAL process to be economically successful must be carried on under proper conditions of control and equipment. The question of equipment is always of primary importance. In the dis-tillation process for the recovery of zinc by retorting, the retort is the all-important piece of equipment. Each retort in a working block must function as a separate unit. Over-all block efficiency is the result of the ability of the individual retort -to withstand the severe conditions of operation for a maximum period of time. Therefore retort manufacture has been an ever present problem with the operator of a zinc-retort-ing plant. During recent years the zinc-plant operator has been faced with rapid changes in the character of the ores and concentrates. Operating costs have increased as a result of the- introduction of the flotation process and the amount of flotation concentrates to be handled. To counteract increasing costs, the operator has found it necessary continually to attempt heavier loading of retorts, until a 45 to 50-lb. charge per cubic foot of retort space has become common practice. Heavy loading has brought about severe firing conditions, which, in turn, have emphasized the necessity for further improving the quality of the retort. Increasing percentages of detrimental impurities in the retort charges have also added to the operator's difficulties.