Some factors affecting the chlorination of kaolinic clay

Chlorination of small samples of kaolinic clay was studied by the Bureau of Mines by a continuous weighing technique. The effects of NaCl additions, prior contact with SiCl₄ vapor, and the form of the reductant were qualitatively examined. Optimal chlorination of clay samples weighing less than 0.2 g was achieved in a fast-moving stream of CO and Cl₂ such that 90 pct of the aluminum and <5 pct of the silicon were reacted in 55 min at 625°C when one part NaCl was added to ten parts clay. Similar results were obtained in about 15 min at 750°C using chlorine gas with a mixture of ten parts clay, two parts charcoal and one part NaCl.