The equations of caustic curve and its initial curve for a crack illuminated by an oblique incident light beam in reflection arrangement were deduced using the space analytic geometry method.

The experiments demonstrate that this is a new method of production, It will in a certain sense improve the process of manufacturing pure sodium and caustic soda.

For sulfur content more than 1.5%, hydrotreating of FCC feedstock or regenerative wet caustic washing method of the BELCO Company is adoptable.