Method for processing magnesium chloride solutions

Patent metadata

Field	Value
Publication number	US-2016369302-A1
Application number	US-201414902374-A
Country	US
Kind code	A1
Filing date	Jul 2, 2014
Priority date	Jul 3, 2013
Publication date	Dec 22, 2016
Grant date	—

Abstract

A method for processing MgCl2 solutions including the steps of: providing an aqueous solution including 5-25 wt. % of MgCl2 and optionally organic contaminants to a step, wherein water and present, organic components are evaporated; withdrawing aqueous solution with a MgCl2 concentration of 25-35 wt. % from an evaporation step and providing it to a preconcentrator where it is contacted with a HCl containing gas stream at least 300° C.; providing aqueous solution with a MgCl2 concentration of 35-45 wt. % resulting from the preconcentrator to a thermohydrolysis reactor, being at at least 300° C.; withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream from the thermohydrolysis reactor, said HCl-containing gas stream at least 300° C.; providing the HCl-containing gas stream with at least 300° C. to the preconcentrator; withdrawing a HCl-containing gas stream with a temperature of at most 150° C. from the preconcentrator.

First claim

1 . Method for processing MgCl2 solutions comprising the steps of
providing an aqueous solution comprising 5-25 wt. % of MgCl2 and optionally organic contaminants to an evaporation step, wherein water and, where present, organic components are evaporated, withdrawing an aqueous solution with a MgCl2 concentration of 25-35 wt. % from an evaporation step and providing it to a preconcentrator where it is contacted with a HCl containing gas stream with a temperature of at least 300° C., providing an aqueous solution with a MgCl2 concentration of 35-45 wt. % resulting from the preconcentrator to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C., withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream from the thermohydrolysis reactor, said HCl-containing gas stream having a temperature of at least 300° C., providing the HCl-containing gas stream with a temperature of at least 300° C. to the preconcentrator, withdrawing a HCl-containing gas stream with a temperature of at most 150° C. from the preconcentrator.

2 . Method according to claim 1 , wherein the aqueous solution comprising magnesium chloride has a total content of organic components (TOC) of at least 1000 ppm.

3 . Method according to claim 1 wherein the product resulting from the evaporation step has a TOC which is at most 50% of the TOC of the aqueous solution provided to the first evaporation step.

4 . Method according to claim 1 , wherein the product resulting from the evaporation step which is provided to the preconcentrator has a TOC of at most 1000 ppm.

5 . Method according to claim 1 wherein the concentration increase effected during the evaporation step before the preconcentrator, defined as [MgCl2 prec]−[MgCl2 start], is between 30 and 5 wt. %.

6 . Method according to claim 1 wherein the evaporation step is a single-stage evaporation step.

7 . Method according to claim 1 wherein the evaporation step is a multiple-stage evaporation step.

8 . Method according to claim 7 wherein in the first stage of a multiple-stage evaporation step volatile organic components are removed, so that the concentrated product from the first evaporation stage has a VTOC which is at most 50% of the VTOC of the aqueous solution provided to the first evaporation stage.

9 . Method according to claim 7 wherein steam is withdrawn from the first evaporation step and provided as heating liquid to a further evaporation step.

10 . Method according to claim 9 wherein the multiple stage evaporation is carried out in a multiple-effect evaporator.

11 . Method according to claim 1 wherein vapor-compression evaporation is used in the evaporation step or in one or more stages thereof.

12 . Method according to cl;aim 1 , wherein the magnesium chloride solution is derived from a process comprising the steps of
subjecting a carbon source to a fermentation step to form a carboxylic acid, which fermentation step comprises the steps of fermenting a carbon source by means of a micro-organism in a fermentation broth to form carboxylic acid and neutralizing at least part of the carboxylic acid by adding a magnesium base selected from magnesium oxide and magnesium hydroxide, thereby obtaining a magnesium carboxylate, subjecting the magnesium carboxylate to an acidification step wherein the magnesium carboxylate is contacted with HCl in an aqueous environment to form an aqueous mixture comprising carboxylic acid and magnesium chloride subjecting the aqueous mixture comprising carboxylic acid and magnesium chloride to a separation step, to form an effluent comprising carboxylic acid and a magnesium chloride solution.

13 . Method according to claim 12 comprising the steps of
recycling the organic components evaporated during the evaporation step at least in part to the separation step, and/or
recycling the magnesium oxide withdrawn from the thermohydrolysis reactor at least in part to the fermentation step, and/or
recycling the HCl-containing gas stream derived from the preconcentrator at least in part to the acidification step.

14 . Method according to claim 13 , wherein the method comprises
recycling the organic components evaporated during the evaporation step at least in part to the separation step, and recycling the magnesium oxide withdrawn from the thermohydrolysis reactor at least in part to the fermentation step, and recycling the HCl-containing gas stream derived from the preconcentrator at least in part to the acidification step.

15 . Method according to claim 12 wherein the separation step encompasses an extraction step, wherein use is made of an organic extractant.

Assignees

• Purac Biochem Bv

Inventors

• De Vries Johannes Jeichienus
• Frediansyah Raymon
• De Haan André Banier

Classifications

• C12P7/40 Primary

  containing a carboxyl group {including Peroxycarboxylic acids} · CPC title

• C07C51/02

  from salts of carboxylic acids · CPC title

• C01B7/01

  Chlorine; Hydrogen chloride · CPC title

• C01F5/30

  Chlorides · CPC title

• C01F5/10 Primary

  by thermal decomposition of magnesium chloride with water vapour · CPC title