A processing unit for a liquid washing medium contaminated with sulphur oxides and/or nitrogen oxides, has an evaporation stage for concentrating the active components of the washing medium by an evaporator and/or by a heat exchanger, and has a collecting tank connected to the evaporator and/or to the heat exchanger. The collecting tank is configured as a crystallizer for removing sulfur oxides from the washing medium by crystallization of a sulphate, in particular of potassium sulphate. A separating device for carbon dioxide has a corresponding processing unit, and a method for processing a washing medium contaminated with sulphur oxides and/or nitrogen oxides uses a corresponding processing unit.

A process for preparing solid sodium carbonate monohydrate from a solution of sodium carbonate is described.

A method of forming lithium carbonate from a lithium-bearing solution including: evaporating the lithium-bearing solution to precipitate a first group of impurities; removing the first group of impurities to form a first purified solution; and performing a flash crystallisation step within a predetermined temperature range to crystallise a second group of impurities from the first purified solution; removing the second group of impurities from the first solution to form a second purified solution, wherein at least 90 wt % of lithium is recovered from the first purified solution; and reacting the second purified solution with a metal carbonate to form lithium carbonate of at least 90 wt % purity.

A method (10) for the processing of lithium containing brines, the method comprising the method steps of: (i) Passing a lithium containing brine (12) to a filtration step (14) to remove sulphates; (ii) Passing a product (16) of step (i) to a first ion exchange step (18) to remove divalent impurities; (iii) Passing a product (20) of step (ii) to a second ion exchange step (22) to remove boron impurities; (iv) Passing a product (24) of step (iii) to an electrolysis step (26) to produce lithium hydroxide (28); and (v) Passing a product (30) of step (iv) to a crystallisation step (32) that in turn provides a lithium hydroxide monohydrate product (34).

A process for removing lactic acid from an aqueous lactic acid-containing magnesium chloride solution, the weight ratio of magnesium chloride to lactic acid in the aqueous lactic acid-containing magnesium chloride solution being at least 1:1, the process including the steps of subjecting the aqueous lactic acid-containing magnesium chloride solution to an evaporation step, resulting in the formation of a slurry of MgCl2.Math.MgL2.Math.4H2O in an aqueous magnesium chloride solution, then subjecting the slurry to a solid-liquid separation step, to separate the solid MgCl2.Math.MgL2.Math.4H2O from the aqueous magnesium chloride solution, resulting in the removal of lactic acid from the aqueous lactic acid-containing magnesium chloride solution in the form of MgCl2.Math.MgL2.Math.4H2O. The process makes it possible to efficiently remove lactic acid from aqueous lactic acid-containing magnesium chloride solutions, resulting in magnesium chloride solutions with a low lactic acid content which can be further processed as desired.

Techniques according to the present disclosure include capturing carbon dioxide from a dilute gas source with a CO.sub.2 capture solution to form a carbonate-rich capture solution; separating at least a portion of carbonate from the carbonate-rich capture solution; forming an electrodialysis (ED) feed solution; flowing a water stream and the ED feed solution to a bipolar membrane electrodialysis (BPMED) unit; applying an electric potential to the BPMED unit to form at least two ED product streams including a first ED product stream including a hydroxide; and flowing the first ED product stream to use in the capturing the carbon dioxide from the dilute gas source with the CO.sub.2 capture solution.