| abstract |
Mined salt mixtures comprising sodium-carbonate, -bicarbonate, -chloride, -sulfate, and -double salts, such as trona and burkeite, are leached with a bicarbonate-saturated solution and added carbon dioxide to selectively dissolve the sodium chloride, sodium sulfate and burkeite and to precipitate additional trona, leaving a leach residue consisting essentially of trona. The trona is calcined and dissolved, and the carbonate solution is purified, crystallized and dehydrated in a non-convective solar pond yielding high purity sodium carbonate monohydrate which is converted into dense soda ash. The brine solution from the leach may be treated for the recovery of a further amount of trona. |