Abstract: A method of producing dicalcium phosphate from calcium phosphate includes reacting the calcium phosphate with a mineral acid such as sulphuric acid to produce a calcium salt and phosphoric acid. The calcium salt may then be hydrolyzed to form a calcium alkali which may then be reacted with the phosphoric acid to produce dicalcium phosphate. Also, a method of producing monocalcium phosphate from calcium phosphate includes reacting the calcium phosphate with sulphuric acid to produce monocalcium phosphate. The monocalcium phosphate may be further processed to remove fluorine contamination and to produce fluorine-free dicalcium phosphate or dicalcium phosphate dihydrate.

Abstract: A method and apparatus for reducing a metal compound particularly iron oxide, by means of a reducing agent comprising CO or H.sub.2 or a mixture of these two gases, of which the average temperature is between 850.degree. C. and 1000.degree. C. and which has been obtained at this temperature by means of a plasma arc heater. The CO and H.sub.2 mixture is preferably obtained by heating a mixture comprising a selection of various reducing agents, including so called Sasol gas, and CO.sub.2 and steam in a plasma arc heater and converting the mixture to CO and H.sub.2.