# US 11,027,999 B2 · Enhanced process for selective salt recovery from wastewater, waste salts, and brines

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- Number: US 11,027,999 B2
- Document ID: US11027999B2
- Status: Granted
- Kind: B2
- Application number: 16/550,805
- Filed: 2019-08-26
- Published: 2019-12-19
- Granted: 2021-06-08
- Earliest claimed: 2016-07-28
- Assignees: Veolia Water Technologies, Inc.
- Applicants: Veolia Water Technologies, Inc.
- Inventors: Sebastien Bessenet; Timothy J. Rittof
- Web page: https://patentgrep.com/patent/US11027999B2

## CPC

- C02F 9/00: Multistage treatment of water, waste water or sewage
- B01D 9/0004: {cooling by heat exchange (by evaporation of components of the mixture to be separated B01D9/0013; refrigeration machines F25B)}
- B01D 9/0031: {by heating (B01D9/0022, B01D9/0027 take precedence)}
- B01D 9/0059: {General arrangements of crystallisation plant, e.g. flow sheets}
- C01D 3/06: Preparation by working up brines; seawater or spent lyes
- C01D 5/16: Purification {(C01D5/145 takes precedence)}
- C02F 1/048: {Purification of waste water by evaporation}
- C02F 1/283: {using coal, charred products, or inorganic mixtures containing them}
- C02F 1/442: {by nanofiltration}
- C02F 1/52: by flocculation or precipitation of suspended impurities {(C02F1/463 takes precedence)}
- C02F 1/04: by distillation or evaporation
- C02F 2001/5218: {Crystallization}
- C02F 2101/101: {Sulfur compounds}
- C02F 2101/12: Halogens or halogen-containing compounds
- C02F 2103/365: {from petrochemical industry (e.g. refineries)}
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01D: COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides C01B17/22; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia and cyanogen, containing nitrogen and other non-metals C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; phosphides C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20)

## Abstract

A process for treating wastewater or waste brines that include sodium and chloride ions. The waste brine is concentrated and thereafter directed to a Mirabilite crystallizer that produces hydrated sulfate salt crystals and a first solution. The hydrated crystals are melted to form an aqueous sulfate solution that is directed to a sodium sulfate crystallizer which produces sodium sulfate salt crystals. The first solution produced by the Mirabilite crystallizer is directed to a nanofiltration device which produces a permeate stream and a reject stream containing sulfate removed by the nanofiltration device. The permeate stream is directed to a sodium chloride crystallizer that produces sodium chloride salt crystals. The reject stream is recycled to the Mirabilite crystallizer.

## Claims

### Claim 1

A method of treating a waste brine that contains sodium, sulfate and chloride and producing sulfate and chloride salt crystals comprising:
directing the waste brine to a nanofiltration device and filtering the waste brine to produce a permeate stream and a reject stream;
directing the reject stream to a first concentration unit and concentrating the reject stream;
directing the concentrated reject stream to a Mirabilite crystallizer and producing via cooling crystallization hydrated sulfate salt crystals;
melting the hydrated sulfate salt crystals to form an aqueous sulfate solution or a slurry;
directing the aqueous sulfate solution or slurry to a sodium sulfate crystallizer and crystallizing anhydrous sulfate salts from the aqueous sulfate solution or slurry to form the sodium sulfate salt crystals;
directing the permeate stream from the nanofiltration device to a second concentration unit and concentrating the permeate stream; and
directing the concentrated permeate stream to a sodium chloride crystallizer and producing the sodium chloride salt crystals.

### Claim 2 (depends on 1)

The method of claim 1 wherein the sulfate crystallizer produces a mother liquor and the method includes recycling the mother liquor from the sulfate crystallizer to the Mirabilite crystallizer.

### Claim 3 (depends on 1)

The method of claim 1 including purging brine from the Mirabilite crystallizer and directing the purged brine to a waste backend crystallizer and producing a waste salt.

### Claim 4

A coal-to-chemical or coal-to-liquid process that includes recovering sulfate and chloride salt crystals, the process comprising:
converting coal-to-chemical or liquid and producing a waste brine which contains sodium, sulfate and chloride;
directing the waste brine to a nanofiltration device and filtering the waste brine to produce a permeate stream and a reject stream;
directing the reject stream to a first concentration unit and concentrating the reject stream;
directing the concentrated reject stream to a Mirabilite crystallizer and producing via cooling crystallization hydrated sulfate salt crystals;
melting the hydrated sulfate salt crystals to form an aqueous sulfate solution or a slurry;
directing the aqueous sulfate solution or slurry to a sodium sulfate crystallizer and crystallizing anhydrous sulfate salts from the aqueous sulfate solution or slurry to form the sodium sulfate salt crystals;
directing the permeate stream from the nanofiltration device to a second concentration unit and concentrating the permeate stream; and
directing the concentrated permeate stream to a sodium chloride crystallizer and producing the sodium chloride salt crystals.