The invention pertains to a method for preparing succinic acid comprising the steps of providing an aqueous magnesium succinate solution to an acidification step, wherein the magnesium succinate solution is acidified by the addition of hydrogen chloride, thereby obtaining an aqueous solution comprising succinic acid and magnesium chloride; subjecting an aqueous solution comprising succinic acid and magnesium chloride derived from the acidification step to a treatment step with active carbon, precipitating succinic acid from an aqueous mixture comprising succinic acid and magnesium chloride resulting from the active carbon treatment step in a precipitation step to form solid succinic acid and a magnesium chloride solution, separating the solid succinic acid from the magnesium chloride solution subjecting the magnesium chloride solution to a thermal decomposition at a temperature of at least 300 C., thereby decomposing the magnesium chloride to magnesium oxide and hydrogen chloride, and recycling the hydrogen chloride generated in the thermal decomposition step to the acidification step. It has been found the method according to the invention leads to succinic acid crystals with better properties than a comparable method wherein no active carbon treatment is used.

A process involving the steps in this order of: providing a waste plastics stream (A) comprising polyvinyl chloride (PVC); (i) supplying the waste plastics stream (A) to a reactor vessel; (ii) subjecting the waste plastics in the reactor vessel to a temperature of 250 C. and 350 C., preferably of 275 C. and 325 C., preferably for a period of 5-30 minutes, under applying a vacuum, preferably of 35 mbar, or using an inert gas sweep, and evacuating the generated hydrogen chloride (B) from the vessel, wherein the PVC is partially dechlorinated to form a waste plastics stream (C) comprising partially unsaturated PVC; (iii) removing the waste plastics stream (C) comprising partially unsaturated PVC from the reaction vessel; and (iv) separating the partially unsaturated PVC from the waste plastics stream to form a dechlorinated waste plastics stream (D).

The present invention relates to a method for chlorination and dehydrogenation of ethane, comprising: mixing and reacting a low-melting-point metal chloride with C.sub.2H.sub.6, such that the low-melting-point metal chloride is reduced to a liquid-state low-melting-point metal, and the C.sub.2H.sub.6 is chlorinated and dehydrogenized to give a mixed gas containing HCl, C.sub.2H.sub.6, C.sub.2H.sub.4, C.sub.2H.sub.2 and C.sub.2H.sub.3Cl. In the method, the low-melting-point metal chloride is used as a raw material for chlorination and dehydrogenation, and the low-melting-point metal produced after the reaction is used as an intermediate medium. The method has the characteristics of simple process, low cost and high yield. Moreover, some acetylene and vinyl chloride can be produced as by-products at the same time when the ethylene is produced, by controlling the ratio of ethane to the chloride as desired in production.

Embodiments of the present disclosure are directed to systems and methods of removing carbon dioxide from a gaseous stream using magnesium hydroxide and then regenerating the magnesium hydroxide. In some embodiments, the systems and methods can further comprise using the waste heat from one or more gas streams to provide some or all of the heat needed to drive the reactions. In some embodiments, magnesium chloride is primarily in the form of magnesium chloride dihydrate and is fed to a decomposition reactor to generate magnesium hydrochloride, which is in turn fed to a second decomposition reactor to generate magnesium hydroxide.

A method for recovering hydrochloric acid and metal oxides from a chloride liquor is described. The method uses a chloride liquor including the metal and mixing the liquor and a matrix solution to produce a reaction mixture, wherein the matrix solution assists oxidation/hydrolysis of the metal with HCl production. In a preferred embodiment the matrix solution includes zinc chloride in various stages of hydration and an oxygen containing gas is added to the mix. A method where the improvement is the mixing of a liquor and a matrix solution where the solution assists hydrolysis of the metal with HCl production is also disclosed. The reactor is a column reactor in a preferred embodiment. Further disclosed is the method of using the matrix solution and a reactor for recovering hydrochloric acid and for oxidizing/hydrolysis of a metal.

Embodiments of the present disclosure are directed to systems and methods of removing carbon dioxide from a gaseous stream using magnesium hydroxide and then regenerating the magnesium hydroxide. In some embodiments, the systems and methods can further comprise using the waste heat from one or more gas streams to provide some or all of the heat needed to drive the reactions. In some embodiments, magnesium chloride is primarily in the form of magnesium chloride dihydrate and is fed to a decomposition reactor to generate magnesium hydroxychloride, which is in turn fed to a second decomposition reactor to generate magnesium hydroxide.

A process for the production of potassium sulphate by conversion of potassium chloride and sulphuric acid using a muffle furnace, said furnace comprising a reaction chamber and a combustion chamber, wherein in the reaction chamber potassium chloride (KCI) and potassium hydrogen sulfate (KHSO.sub.4) are reacted to form potassium sulphate while supplying heat to the reaction chamber from the combustion chamber, wherein the combustion chamber has at least a pair of regenerative burners and wherein the process comprises the steps of alternatingly causing one of the regenerative burners to perform a combustion operation in the combustion chamber to heat the reaction chamber and another of the regenerative burners to perform a heat-regenerating operation in a regenerator, wherein the pressure in the combustion chamber is kept at a pressure of between 0.2 and 3 mbarg.

The present relates to a method for producing calcium sulfate solid crystals and hydrochloric acid (HCl) from a calcium chloride solution comprising the steps of feeding a continuous stirred-tank reactor with a calcium chloride solution, sulfuric acid and water; mixing the calcium chloride solution, sulfuric acid and water in the reactor; and maintaining the reactor a temperature of less than about 70 C., converting the calcium chloride solution, sulfuric acid and water into HCl and calcium sulfate solid crystals. The method described herein can be incorporated as a means for regenerating HCl from CaCl.sub.2 solutions which are generated in the metallurgical industry when processing calcium-bearing ores for recovering metals like rare earth elements.

A method for producing titanium tetrachloride is provided, in which valuable materials such as unreacted titanium-containing raw material, carbon raw material and chlorine can be recovered from solid recovered material generated in chlorinating process of titanium-containing raw material, and titanium-containing raw material can be efficiently used. The treatment method of titanium-containing raw material includes the steps: separating and removing impurities selectively from the titanium-containing raw material as chlorides so as to obtain high titanium-containing raw material, producing titanium tetrachloride using the high titanium-containing raw material, and performing separating process of impurities from solid recovered material byproduced in the production of titanium tetrachloride, together with selective chlorinating treatment of the titanium-containing raw material. Thus, the high titanium-containing raw material can be produced while recovering chlorine and impure oxides.

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 MgCl2.4H2O. 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.