Texasgulf Inc.

Arthur Gloster

Edward H Conroy

James A King

An improved process for the production of soda ash from trona including the steps of sizing the trona, heating the trona to eliminate water and carbon dioxide therefrom, dissolving the trona in an aqueous medium to obtain a solution thereof, removing insoluble solid materials from the solution, crystallizing sodium carbonate monohydrate from the solution, and heating the crystallized sodium carbonate monohydrate to produce soda ash. The improvement of the invention comprises the step of removing insoluble solid materials from the solution of trona by classifying the insoluble solid materials in a plurality of hydroclones.

Process for the separation of insoluble materials in the production of

Sodium carbonate is crystallized in multi-stage evaporative crystallizers from a pregnant liquor process solution typically obtained by dissolving calcined crude trona in water, separating insoluble impurities, and removing the majority of organic matter with activated carbon. After separation from the sodium carbonate crystals, a portion of the mother liquor usually is recycled to the crystallizers, and the remainder is purged to prevent buildup of impurities. Product quality is improved, and the amount of purged mother liquor is reduced by feeding the pregnant liquor predominantly to the initial stage crystallizers, directing the majority of the recycled mother liquor to a final stage crystallizer, recovering sodium carbonate crystals from slurries from at least the initial stages, and withdrawing purge liquor only from the slurry from the final stage crystallizer. Automatic compensation for variations in feed rates is obtained by introducing fresh feed into one end of a common crystallizer feed pipe adjacent to the first stage and directing recycled mother liquor to the other end of the feed pipe adjacent to the final stage. Preferably the stages are arranged in order of decreasing temperature so that the purge liquor is taken from the lowest temperature stage.

Multi-stage crystallization of sodium carbonate

Described herein is a process for producing soda ash (sodium carbonate) from natural ores such as trona in which separate soda ash products are produced having differing purities. According to the invention, a substantially purified and saturated solution of sodium carbonate is divided into at least two separate process streams, one of which is subjected to crystallization in the absence of recycled mother liquor to form high purity sodium carbonate-containing crystals, while the other stream is subjected to crystallization in the presence of recycled mother liquor to form lower purity crystals. The crystals are thereafter separately processed to obtain soda ash products of differing grades.

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New York, NY, United States of America

Arthur Gloster