Soda Ash Production (Brine)
General process information (limestone and brine)
To make soda ash (a versatile basic chemical) limestone and coke are mixed in proper proportions and charged into large kilns to produce carbon dioxide gas and lime.
Brine, a mixing of rock salt and water in a controlled manner, is purified, saturated with ammonia gas, and then carbonated in towers with the gas recovered from the lime kilns. A slurry leaving the bottom of the carbonating towers contains ammonium chloride in solution and sodium bicarbonate as a solid. The solid crude "bicarb" is then separated from the ammonium chloride solution on rotary vacuum filters.
The ammonium chloride solution is pumped to distillation columns, or lime stills, where the lime, as a calcium hydroxide slurry, reacts with the ammonium chloride solution to form ammonia gas and a solution of calcium chloride, a waste material. The recovered ammonia from the stills is re-cycled to the absorbers to saturate more of the purified brine.
Washed and filtered crude "bicarb" is decomposed in rotary dryers to produce light soda ash, much of which is sold as a basic raw material to many industries.
Part of the light soda ash is processed into dense ash, primarily for the glass industry. Soda ash constitutes one of this industry's most important raw materials; it combines chemically with sand to become molten glass, from which a host of products are made. It is also used in processing pulp and paper, iron and steel, textiles, soap, and hundreds of other products.