There are provided methods for the production of potassium sulphate. The methods comprise contacting an aqueous potassium- and sulphate-containing composition with magnesium chloride (MgCl.sub.2), thereby obtaining a composition comprising kainite; optionally concentrating the kainite from the composition; reacting the kainite with magnesium sulphate (MgSO.sub.4) and potassium sulphate (K.sub.2SO.sub.4) so as to convert the kainite into leonite (K.sub.2SO.sub.4.MgSO.sub.4.4H.sub.2O); optionally contacting the leonite with water to remove excess MgSO.sub.4; and contacting the leonite with water so as to leach the MgSO.sub.4, contained in the leonite, and to at least substantially selectively precipitate potassium sulphate (K.sub.2SO.sub.4). The method according to the invention can be operated at higher temperatures, in particular at temperatures above 35 C. and does not require a cooling step at 20 to 25 C. The method produces potassium sulphate with a low amount of chloride.

There are provided methods for the production of potassium sulphate. The methods comprise contacting an aqueous potassium- and sulphate-containing composition with magnesium chloride (MgCl.sub.2), thereby obtaining a composition comprising kainite; optionally concentrating the kainite from the composition; reacting the kainite with magnesium sulphate (MgSO.sub.4) and potassium sulphate (K.sub.2SO.sub.4) so as to convert the kainite into leonite (K.sub.2SO.sub.4.MgSO.sub.4.4H.sub.2O); optionally contacting the leonite with water to remove excess MgSO.sub.4; and contacting the leonite with water so as to leach the MgSO.sub.4, contained in the leonite, and to at least substantially selectively precipitate potassium sulphate (K.sub.2SO.sub.4). The method according to the invention can be operated at higher temperatures, in particular at temperatures above 35 C. and does not require a cooling step at 20 to 25 C. The method produces potassium sulphate with a low amount of chloride.

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.

A method of recovering wood pulping chemicals from black liquor produced in a wood pulping process where the process entails burning the black liquor in a recovery boiler to form ash containing high levels of carbonate as well as sodium, potassium and chloride. The ash is dissolved to form a dissolved ash solution that is directed to a first stage crystallization unit that concentrates the dissolved ash solution and which results in the precipitation of sodium sulfate and sodium carbonate. Thereafter the concentrated dissolved ash solution is directed to a second stage crystallization unit which adiabatically cools the concentrated dissolved ash solution to form a glaserite slurry and a purge stream that is rich in chloride. In order to reduce the tendency of sodium carbonate and burkeite to crystallize in the second stage crystallization unit and to encourage pure glaserite to crystalize in the crystallizer, the method entails mixing a sulfate source, such as sodium sulfate or sulfuric acid, to the concentrated dissolved ash solution upstream of the crystallizer.

A method of recovering wood pulping chemicals from black liquor produced in a wood pulping process where the process entails burning the black liquor in a recovery boiler to form ash containing high levels of carbonate as well as sodium, potassium and chloride. The ash is dissolved to form a dissolved ash solution that is directed to a first stage crystallization unit that concentrates the dissolved ash solution and which results in the precipitation of sodium sulfate and sodium carbonate. Thereafter the concentrated dissolved ash solution is directed to a second stage crystallization unit which adiabatically cools the concentrated dissolved ash solution to form a glaserite slurry and a purge stream that is rich in chloride. In order to reduce the tendency of sodium carbonate and burkeite to crystallize in the second stage crystallization unit and to encourage pure glaserite to crystalize in the crystallizer, the method entails mixing a sulfate source, such as sodium sulfate or sulfuric acid, to the concentrated dissolved ash solution upstream of the crystallizer.

Process of materials recovery from energy storage devices, wherein the process comprises cleaning, washing, deep discharging and then crushing the devices to recover floating non-magnetic materials and magnetic materials. Further the black mass is treated with baking process, water soaking process, gravity filtration process, leaching process, Cobalt salt recovery process, Manganese salt recovery process, Nickel salt recovery process, Sodium salt recovery process, Lithium salt recovery process and then selective absorption of respective ions using Ion-exchange resin and liquid-liquid extraction using organic solvent for beneficiation to recover pure Cobalt ions, Manganese ions, Nickel ions and Lithium ions. Further the process of the present invention facilitates in recovering all possible battery grade materials from used energy storage devices. The process of the present invention uses less water, energy, economical, safe, environment friendly without generating any hazardous gases while the process has very low carbon foot prints.

Process of materials recovery from energy storage devices, wherein the process comprises cleaning, washing, deep discharging and then crushing the devices to recover floating non-magnetic materials and magnetic materials. Further the black mass is treated with baking process, water soaking process, gravity filtration process, leaching process, Cobalt salt recovery process, Manganese salt recovery process, Nickel salt recovery process, Sodium salt recovery process, Lithium salt recovery process and then selective absorption of respective ions using Ion-exchange resin and liquid-liquid extraction using organic solvent for beneficiation to recover pure Cobalt ions, Manganese ions, Nickel ions and Lithium ions. Further the process of the present invention facilitates in recovering all possible battery grade materials from used energy storage devices. The process of the present invention uses less water, energy, economical, safe, environment friendly without generating any hazardous gases while the process has very low carbon foot prints.

Described herein is a process for making crystalline sodium sulfate, the process including the steps of (a) combining an aqueous solution containing sulfates of nickel and at least one metal selected from cobalt and manganese with an aqueous solution of sodium hydroxide or sodium carbonate, respectively, in a stoichiometric ratio of about 1:2, optionally in the presence of ammonia or a salt of ammonia, (b) removing the precipitated hydroxide or carbonate of nickel and the at least one metal selected from cobalt and manganese by filtration, (c) removing the ammonia from the filtrate from step (b) by stripping in a distillation column, (d) passing the remaining liquid phase through a membrane, thereby obtaining a permeate, and (e) removing water from the permeate from step (d) by an evaporation method.

Described herein is a process for making crystalline sodium sulfate, the process including the steps of (a) combining an aqueous solution containing sulfates of nickel and at least one metal selected from cobalt and manganese with an aqueous solution of sodium hydroxide or sodium carbonate, respectively, in a stoichiometric ratio of about 1:2, optionally in the presence of ammonia or a salt of ammonia, (b) removing the precipitated hydroxide or carbonate of nickel and the at least one metal selected from cobalt and manganese by filtration, (c) removing the ammonia from the filtrate from step (b) by stripping in a distillation column, (d) passing the remaining liquid phase through a membrane, thereby obtaining a permeate, and (e) removing water from the permeate from step (d) by an evaporation method.

A method of collecting anhydrous sodium sulfate from fly ash includes heating a purified sodium sulfate solution to 60 C. to 80 C., and adding a precipitation promoter to the purified sodium sulfate solution to precipitate anhydrous sodium sulfate crystal. The method further includes cooling the purified sodium sulfate solution and the anhydrous sodium sulfate crystal to 35 C. to 55 C. for precipitating more anhydrous sodium sulfate crystal, and collecting and drying the anhydrous sodium sulfate crystal.