US 8,282,690 B2 · Process for the preparation of solar salt having high purity and whiteness

Abstract

The process of the invention deals with significant improvements in salt purity and whiteness brought about through treatment of brine with alum prior to charging into crystallizers for solar salt production. The improvements realized are partly on account of elimination of suspended impurities like gypsum and clayey matter in the brine, which may otherwise be carried along with the brine in the crystallizer and finally end up in the salt, and partly due to the improved crystal size and morphology that minimizes embedded impurities in the salt. Rain washing of the heaped salt has resulted in a salt with greatly reduced calcium and sulphate impurity levels hitherto not achieved in solar salt production. Alum treatment by the process of the invention requires no additional time or infrastructure and the cost of the treatment works out to <3 U.S. cents per ton of salt. The process can be implemented in any solar salt works.

Claims32

Dependent claims

A process for obtaining salt from brine, the said process comprising the steps of:

(i) subjecting brine to solar evaporation to crystallize out carbonate salts and gypsum to obtain concentrated brine,
(ii) mixing an alum solution with the above said concentrated brine,
(iii) settling of suspended particles under gravity and subsequent clarification of brine in a pre-crystallizer,
(iv) feeding the above said clarified brine into a crystallizer and while inhibiting flocs from entering into the crystallizer by maintaining adequate dead volume in the pre-crystallizer and also minimizing re-contamination of the clarified brine with clay/soil, and continuing solar evaporation to crystallize out salt,
(v) repeating the steps of (ii) to (iv) to build up a salt layer in the crystallizer,
(vi) draining out bittern from the crystallizer followed by charging fresh brine into the crystallizer,
(vii) harvesting and washing of salt to obtain salt.

4 more elements

Dependencies are inferred from the claim text.

Process for the preparation of solar salt having high purity and whiteness

Life of this patent

Process for the preparation of solar salt having high purity and whiteness

Life of this patent

Abstract

Claims32