A Kiln Patent Is Granted

Up to this point almost no attention has been paid to the heart of the plant, the kiln. It has several unique features that are unknowns. It is large and must rotate at a high temperature. It is gas-heated internally, but feed to the kiln is a liquid that is sprayed onto a bed of hot crystals through water-cooled feed tubes that reciprocate over the feed to insure that feed is fed uniformly to the hot charge. Perhaps the best way to describe the kiln is to furnish the description given in the U.S. Patent No. 4,717,487.  

The approach taken to grind samples in a pilot plant was surely not low technology, but perhaps too sophisticated for the job it was required to do. The mill was an air classification mill. Although this mill functioned reasonably well, it had wear surfaces that were certain to be a source of excessive maintenance when placed in a full production mode. This issue was never faced, but was recognized as a problem that had not been adequately solved. A two-step crushing and milling process should work well. 

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