Abstract: In a fluidized-bed combustor the evolving sulfur oxides are reacted with CaO to form calcium sulfate which is then decomposed in the presence of carbonaceous material, such as the fly ash recovered from the combustion, at temperatures of about 900.degree. to 1000.degree. C., to regenerate lime. The regenerated lime is then recycled to the fluidized bed combustor to further react with the evolving sulfur oxides. The lime regenerated in this manner is quite effective in removing the sulfur oxides.

Abstract: Calcium sulfate is decomposed to CaO and SO.sub.2 by high temperature treatment in a fluidized bed wherein reductive and oxidative conditions are simultaneously maintained. A highly reducing gas is formed in the lower portion of the bed from partial combustion of the fuel in admixture with the primary fluidizing air. The quantity of the primary fluidizing air is limited so that the reducing conditions in the lower zone converts the CaSO.sub.4 to a mixture of CaO and CaS. Secondary air is introduced at a higher level in the bed to create an oxidizing zone in the upper portion of the bed above the reducing zone capable of converting CaS to CaO. The concurrent use of such reducing and oxidizing zones permits reducing conditions to be maintained which favor a high rate of decomposition even though these conditions favor the formation of CaS as well as CaO.

Abstract: This invention relates to a process of producing magnesia from magnesium-containing carbonate ores, which comprises leaching with sulfuric acid, subsequently neutralizing the solution with magnesia, separating the undissolved impurities, crystallizing magnesium sulfate under pressure and above 150.degree. C so the crystals have from 1.5 to 4 moles of water per magnesium sulfate molecule and thermally decomposing the latter to form magnesia and SO.sub.2, recovering sulfuric acid from the sulfur dioxide produced in the decomposing steps and recycling the sulfuric acid to the leaching stage.

Abstract: Alkali metal or alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate found in dolomite or limestone are employed for removal of sulfur dioxide from combustion exhaust gases. The sulfated carbonates are regenerated to oxides through use of a solid-solid reaction, particularly calcium sulfide with calcium sulfate to form calcium oxide and sulfur dioxide gas. The regeneration is performed by contacting the sulfated material with a reductant gas such as hydrogen within an inert diluent to produce calcium sulfide in mixture with the sulfate under process conditions selected to permit the sulfide-sulfate, solid-state reaction to occur.

Abstract: There is disclosed a process for converting an alkaline earth metal sulfite or bisulfite selected from the group consisting of the sulfites or bisulfites of calcium and magnesium into an oxide form by reaction with hydrogen and water vapor at elevated temperatures particularly in connection with processes for the treatment of flue gases to reduce the amount of sulfur dioxide therein.

Abstract: Barium hydroxide is continuously produced from barite by:1. reducing barite with carbon at elevated temperatures and hot-leaching the reaction mixture to extract raw barium sulfide;2. partially oxidizing the barium sulfide from step (1) by treatment with oxygen-containing gases and precipitating the resulting barium hydroxide in crystalline form and removing same;3. oxidizing the barium polysulfide contained in the mother liquor from step (2) to difficultly soluble barium thiosulfate by treatment with oxygen-containing gases and removing same; and4. recycling the barium thiosulfate from step (3) to reduction step (1).

Abstract: A water-insoluble exchange agent is used to remove barium from aqueous barium sulfide and then to release the barium to aqueous alkali, forming an aqueous solution from which there is crystallized substantially pure Ba(OH).sub.2, 8H.sub.2 O, particularly useful as an ingredient of "barium greases". The preferred exchange agent is di(2-ethylhexyl)phosphoric acid, which can be regenerated and recycled.

Abstract: A process for recovering the calcium values and sulfide values from a calcium sulfide-containing material is disclosed. The calcium sulfide-containing material dispersed in an aqueous medium is digested in the presence of hydrogen sulfide under conditions to provide a mole ratio of S.sup.-.sup.-/Ca.sup.+.sup.+ of between 1.5 and 2.0. After filtration to remove undissolved solids, the mother liquor is stripped with an inert gaseous medium, e.g. nitrogen, steam, etc., whereby hydrogen sulfide is stripped therefrom with the concomitant formation of calcium hydroxide which is subsequently separated by filtration. The gaseous overhead from the stripping operations may be fractionated to form a recycleable hydrogen sulfide-containing stream.