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 MgC12.MgL2.4H2O in an aqueous magnesium chloride solution, then subjecting the slurry to a solid-liquid separation step, to separate the solid MgC12.MgL2.4H2O 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 MgC12.MgL2.4H2O. 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.

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 MgC12.MgL2.4H2O in an aqueous magnesium chloride solution, then subjecting the slurry to a solid-liquid separation step, to separate the solid MgC12.MgL2.4H2O 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 MgC12.MgL2.4H2O. 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.

A method for producing an iron pigment and hydrochloric acid with reduced or substantially eliminated waste streams includes: providing an iron chloride solution, wherein the iron chloride solution includes one or both of iron (II) chloride and iron (III) chloride; neutralizing the iron chloride solution with one or both of ammonia and ammonium hydroxide to form a slurry of an iron oxide solid component and an ammonium chloride solution; separating the iron oxide solid component from the ammonium chloride solution; drying the iron oxide solid component to form an iron pigment or pigment intermediate; reacting the ammonium chloride solution with an alkaline-earth metal solid to form an alkaline-earth metal chloride solution and to evolve ammonia as a vapor, wherein at least a portion of the evolved ammonia reacts with water to form ammonium hydroxide; recycling one or both of the evolved ammonia and the formed ammonium chloride for use in connection with the neutralization step; and pyrohydrolyzing the alkaline-earth metal chloride solution to form hydrochloric acid and to regenerate the alkaline-earth metal solid. Iron pigment or pigment intermediate produced in accordance with the method may have a yellow, red, or black color.

A process for converting magnesium chloride into magnesium oxide having the steps of: subjecting a magnesium chloride solution to a spray drying step in a spray-drying apparatus at a temperature of 300-475° C., resulting in the formation of a spray-dried product having 10-80 wt. % magnesium oxide and 20-90 wt. % of the total of magnesium hydroxychloride and magnesium chloride, subjecting the product of the spray drying step to a roasting step in a roaster at a temperature of 600-900° C. in the presence of water, resulting in the formation of a product having at least 98 wt. % of MgO, and less than 2 wt. % of the total of magnesium hydroxychloride and magnesium chloride, wherein the percentages of MgO, magnesium hydroxychloride and magnesium chloride, are calculated on the total of MgO, magnesium hydroxychloride and magnesium chloride.

A process for converting magnesium chloride into magnesium oxide having the steps of: subjecting a magnesium chloride solution to a spray drying step in a spray-drying apparatus at a temperature of 300-475° C., resulting in the formation of a spray-dried product having 10-80 wt. % magnesium oxide and 20-90 wt. % of the total of magnesium hydroxychloride and magnesium chloride, subjecting the product of the spray drying step to a roasting step in a roaster at a temperature of 600-900° C. in the presence of water, resulting in the formation of a product having at least 98 wt. % of MgO, and less than 2 wt. % of the total of magnesium hydroxychloride and magnesium chloride, wherein the percentages of MgO, magnesium hydroxychloride and magnesium chloride, are calculated on the total of MgO, magnesium hydroxychloride and magnesium chloride.

A method for conversion of magnesium chloride into magnesium oxide and HCl, comprising the steps of providing a magnesium chloride compound 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, wherein the magnesium chloride compound provided to the thermohydrolysis reactor is a solid magnesium chloride compound which comprises at least 50 wt. % of MgCl.sub.2.4H.sub.2O. The process accordingly is fast and can be operated in a manner which is efficient both as regards apparatus and energy. It can also be integrated in a process for converting a magnesium chloride solution.

A method for conversion of magnesium chloride into magnesium oxide and HCl, comprising the steps of providing a magnesium chloride compound 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, wherein the magnesium chloride compound provided to the thermohydrolysis reactor is a solid magnesium chloride compound which comprises at least 50 wt. % of MgCl.sub.2.4H.sub.2O. The process accordingly is fast and can be operated in a manner which is efficient both as regards apparatus and energy. It can also be integrated in a process for converting a magnesium chloride solution.

A method for conversion of magnesium chloride into magnesium oxide and HCl includes the steps of providing a magnesium chloride compound 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 an HCl containing gas stream from the thermohydrolysis reactor. The magnesium chloride compound provided to the thermohydrolysis reactor may be a solid magnesium chloride compound which comprises at least 60 wt. % of MgCl.sub.2.4H.sub.2O.

A method for conversion of magnesium chloride into magnesium oxide and HCl includes the steps of providing a magnesium chloride compound 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 an HCl containing gas stream from the thermohydrolysis reactor. The magnesium chloride compound provided to the thermohydrolysis reactor may be a solid magnesium chloride compound which comprises at least 60 wt. % of MgCl.sub.2.4H.sub.2O.

A method for conversion of magnesium chloride into magnesium oxide and HCl includes the steps of providing a magnesium chloride compound 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 an HCl containing gas stream from the thermohydrolysis reactor. The magnesium chloride compound provided to the thermohydrolysis reactor may be a solid magnesium chloride compound which comprises at least 60 wt. % of MgCl.sub.2.4H.sub.2O.