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PURE SALTS SEPARATION AND OPTIMIZATION OF SELECTIVE SALT RECOVERY FROM BRINE

IP.com Disclosure Number: IPCOM000247067D
Publication Date: 2016-Aug-01
Document File: 5 page(s) / 191K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates generally to solution mining and in particular to methods of recovering various salts from brine solutions with high levels of NaCl, KCl and MgCl2. The methods involve a complex flow sheet to recover selective salts to the desired quality while achieving very high recovery. The flow sheet involves a sequence of steps, including pretreatment using chemical dosing clarifiers, electrodialysis units, S/L separators, alternate crystallization technique or solvent extraction, brine concentrators, ultrafiltration and nanofiltration/reverse osmosis units and efficient recycling. Potassium hydroxide is recovered as overflow stream from the S/L separator, and sodium hydroxide is recovered as a wet solid product. The invention has advantages of high salt and water recovery (>95%), product quality and less solid waste production.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 49% of the total text.

Page 01 of 5

PURE SALTS SEPARATION AND OPTIMIZATION OF SELECTIVE SALT RECOVERY FROM BRINE

BACKGROUND

The invention relates generally to solution mining and in particular to methods of recovering various salts from brine solutions with high levels of NaCl, KCl and MgCl2. Solution mining is a mining process used to recover minerals/salts such as potash, rock salt, sodium sulfate and magnesium chloride through boreholes drilled into a deposit. Brine solution is pumped into the deposit where it makes contact with the ore. The salt-rich solution bearing the dissolved ore content is then pumped to the surface. Brine solutions generated from solution mining typically contains elevated levels of sodium, potassium, magnesium, chlorides and sulfates.

There are various methods of treatment of salt-rich waters from solution mining in practice: 1) thermal systems: these use a concentrator, followed by cooling/crystallization of raw brine, which in turn produces less valuable products like NaCl, KCl and MgCl2, 2) eutectic freeze crystallization: this requires high capital and operating costs and is not economical for smaller flow rates, and 3 the chlor-alkali process: the operating cost of this process is high.

The following problems have to be faced during the treatment of solution mining brine: 1) huge amounts of mixed solids are generated that need to be disposed properly or sold at discounted price. 2) The capital and operating expenses of the recovery system are very high making the treatment uneconomical. 3) D ue to high scaling tendency of salts, membrane-based treatments are not very effective. Also, conventional treatments produce effluents that do not meet discharge regulations. Methods and processes are proposed here that solve most of the above-mentioned challenges in recovering salts in an efficient and cost-effective way.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses methods to recover various salts from brine solutions formed from solution mining, in which

FIG. 1 shows a method for producing acids and caustics from brine.

FIG. 2 shows a method of crystallization/solvent extraction.

FIG. 3 shows a method to recover various salts from brine solution obtained from solution mining.


Page 02 of 5

DETAILED DESCRIPTION

The invention discloses methods and processes for recovering various salts from brine solutions, which have high levels of NaCl, KCl and MgCl2, formed from solution mining carnallite brine etc.). The methods involve a complex flow sheet to recover selective salts to the desired quality while achieving very high recovery. The methods use the principles of membrane electrolysis, ACT/solvent extraction and crystallization. The following steps are involved in the process:


1) P retreatment step: The pretreatment step involves a lime dosing clarifier, where lime quick lime, slaked lime or limestone is added to the feed water to remo ve heavy metals and some amount of sulfate. The clear stream from the clarifier is further filtered u...