A process is provided for producing potassium sulfate from potassium chloride and sulfuric acid. The process entails mixing potassium chloride with the water to form a potassium chloride slurry which is mixed with recycled sulfuric acid to form a K.sup.+, Ct, SO.sub.4.sup.2 acid mixture. This mixture is subjected to a crystallization process that produces potassium sulfate crystals and a hydrochloric acid-water vapor. The hydrochloric acid is separated from the hydrochloric acid-water vapor to form a hydrochloric acid solution.

A process is provided for producing potassium sulfate from potassium chloride and sulfuric acid. The process entails mixing potassium chloride with the water to form a potassium chloride slurry which is mixed with recycled sulfuric acid to form a K.sup.+, Ct, SO.sub.4.sup.2 acid mixture. This mixture is subjected to a crystallization process that produces potassium sulfate crystals and a hydrochloric acid-water vapor. The hydrochloric acid is separated from the hydrochloric acid-water vapor to form a hydrochloric acid solution.

A process is provided for producing potassium sulfate from potassium chloride and sulfuric acid. The process entails mixing potassium chloride with the water to form a potassium chloride slurry which is mixed with recycled sulfuric acid to form a K.sup., Ct, SO.sub.4.sup.2 acid mixture. This mixture is subjected to a crystallization process that produces potassium sulfate crystals and a hydrochloric acid-water vapor. The hydrochloric acid is separated from the hydrochloric acid-water vapor to form a hydrochloric acid solution.

A process is provided for producing potassium sulfate from potassium chloride and sulfuric acid. The process entails mixing potassium chloride with the water to form a potassium chloride slurry which is mixed with recycled sulfuric acid to form a K.sup., Ct, SO.sub.4.sup.2 acid mixture. This mixture is subjected to a crystallization process that produces potassium sulfate crystals and a hydrochloric acid-water vapor. The hydrochloric acid is separated from the hydrochloric acid-water vapor to form a hydrochloric acid solution.

Provided herein is a process for producing one or more products from a lignocellulosic feedstock. The process comprises treating the lignocellulosic feedstock by contacting the feedstock at least sulfur dioxide, sulfurous acid, or a combination thereof to produce a pretreated feedstock comprising one or more sulfonic acids. A process stream comprising one or more sulfonic acids is subsequently treated in a wet oxidation step to produce a stream comprising at least soluble oxidized phenolic compounds. The soluble oxidized phenolic compounds are then fed to an anaerobic digestion to produce methane. Optionally, hydrogen sulfide is produced during the anaerobic digestion. The hydrogen sulfide may then be converted to an acid selected from sulfur dioxide, sulfurous acid or a combination thereof in one or more steps. The acid may then be re-used in treatment as desired.

Provided herein is a process for producing one or more products from a lignocellulosic feedstock. The process comprises treating the lignocellulosic feedstock by contacting the feedstock at least sulfur dioxide, sulfurous acid, or a combination thereof to produce a pretreated feedstock comprising one or more sulfonic acids. A process stream comprising one or more sulfonic acids is subsequently treated in a wet oxidation step to produce a stream comprising at least soluble oxidized phenolic compounds. The soluble oxidized phenolic compounds are then fed to an anaerobic digestion to produce methane. Optionally, hydrogen sulfide is produced during the anaerobic digestion. The hydrogen sulfide may then be converted to an acid selected from sulfur dioxide, sulfurous acid or a combination thereof in one or more steps. The acid may then be re-used in treatment as desired.

A process for producing one or more products from a lignocellulosic feedstock comprising treating the lignocellulosic feedstock to produce sugar in one or more stages comprising addition of acid, base or a combination thereof and introduction of heat. The addition of the acid, base, or a combination thereof produces a salt. The sugar is fermented to produce a fermentation product and the fermentation product is recovered. A stream comprising the salt is treated by wet oxidation with the introduction of heat. A stream comprising salt resulting from the wet oxidation is provided for use as a salt product or a process chemical for introduction within the process. Heat from the wet oxidation may be supplied to any stage of the process in which heat is introduced.

A process for producing one or more products from a lignocellulosic feedstock comprising treating the lignocellulosic feedstock to produce sugar in one or more stages comprising addition of acid, base or a combination thereof and introduction of heat. The addition of the acid, base, or a combination thereof produces a salt. The sugar is fermented to produce a fermentation product and the fermentation product is recovered. A stream comprising the salt is treated by wet oxidation with the introduction of heat. A stream comprising salt resulting from the wet oxidation is provided for use as a salt product or a process chemical for introduction within the process. Heat from the wet oxidation may be supplied to any stage of the process in which heat is introduced.

Disclosed is a method of producing high-purity lithium carbonate and barium sulfate from discarded lithium secondary batteries, including: a first process for producing high-purity lithium phosphate from a discarded battery; and a second process for producing lithium sulfate from the lithium phosphate and producing lithium carbonate and barium sulfate from the lithium sulfate. The second process has steps of (a) producing a liquid mixture of lithium phosphate and sulfuric acid, (b) obtaining lithium sulfate by condensing the liquid mixture, (c) dissolving the lithium sulfate in water or a sodium hydroxide aqueous solution, depositing phosphoric acid as lithium phosphate, and performing solid-liquid separation (d) depositing lithium carbonate and performing solid-liquid separation to obtain lithium carbonate, (e) finely grinding the lithium carbonate and classifying the particles, (f) controlling a particle size and shape by dissolving edges of particles or minute particles, (g) performing solid-liquid separation, and (h) depositing barium sulfate.

Disclosed is a method of producing high-purity lithium carbonate and barium sulfate from discarded lithium secondary batteries, including: a first process for producing high-purity lithium phosphate from a discarded battery; and a second process for producing lithium sulfate from the lithium phosphate and producing lithium carbonate and barium sulfate from the lithium sulfate. The second process has steps of (a) producing a liquid mixture of lithium phosphate and sulfuric acid, (b) obtaining lithium sulfate by condensing the liquid mixture, (c) dissolving the lithium sulfate in water or a sodium hydroxide aqueous solution, depositing phosphoric acid as lithium phosphate, and performing solid-liquid separation (d) depositing lithium carbonate and performing solid-liquid separation to obtain lithium carbonate, (e) finely grinding the lithium carbonate and classifying the particles, (f) controlling a particle size and shape by dissolving edges of particles or minute particles, (g) performing solid-liquid separation, and (h) depositing barium sulfate.