2 results about "Iron(II) hydroxide" patented technology

This disclosure provides at least one embodiment of a method for preparing sponge titanium, comprising: pretreating bauxite tailings to obtain a first mixture; acid-treating the first mixture and filtering it to obtain a second mixture; placing the second mixture in a reaction vessel containing an alkaline substance to react, thereby converting ferrous titanate into titanate and ferric oxide or ferrous hydroxide to obtain a third mixture; filtration of the third mixture to obtain a first solid phase and a first liquid phase, and drying and grinding the first solid phase; calcining the dried and ground first solid phase to form elemental iron, and performing magnetic separation to remove the elemental iron; adding an acidic substance to the first liquid phase to react and obtain metatitanic acid colloid, and washing the metatitanic acid colloid; and sequentially subjecting the metatitanic acid colloid to calcination, chlorination, and displacement reactions to obtain sponge titanium. The sponge titanium obtained by this preparation method has high purity.

The present invention provides a method and apparatus (2a) for producing at least one of calcium oxide, magnesium oxide and an iron oxide from an ore comprising a carbonate mineral of at least one of calcium, magnesium and iron, such as limestone and siderite ores. The method comprises producing liquid sodium and chlorine gas by electrolysis. The liquid sodium is oxidised to sodium oxide and the chlorine is used to make hydrochloric acid. The sodium oxide may be produced in a redox reaction with an oxide of another metal to produce the other metal in elemental form as well. The ore is added to the hydrochloric acid to dissolve the carbonate mineral therein, which produces gaseous carbon dioxide and an aqueous solution respectively comprising at least one of calcium chloride, magnesium chloride and ferrous chloride. The carbonate mineral is dissolved in the hydrochloric acid closed off from their surrounding environment and the carbon dioxide is captured. The aqueous solution is reacted with at least some of the sodium oxide, or sodium hydroxide derived therefrom, to produce an aqueous solution of sodium chloride and a precipitate respectively comprising at least one of calcium hydroxide, magnesium hydroxide and ferrous hydroxide. The precipitate is then phase separated from the aqueous solution of sodium chloride and the hydroxide(s) in the separated precipitate are thermally decomposed to produce water vapour and a solid end-product comprising the desired oxide(s). Sufficient heat for this thermal decomposition is transferred to the separated precipitate from at least one of the electrolysis products, the exothermic processes by which the precipitate is produced, their respective products and the products of the thermal decomposition itself. Thus the invention consumes no carbonaceous fuel, including any fossil fuel, and has electricity as its only energy requirement. If the electricity is produced from a source of renewable energy, it produces no greenhouse gas emissions. The apparatus (2a) comprises an electrolytic subassembly (10), a sodium oxide or hydroxide-producing subassembly (13), a hydrochloric acid-producing subassembly (12), a reaction subassembly (14), a solid-aqueous phase separator (16), a kiln (20), and a heat transfer pathway (23) for transferring enough heat to the precipitate in the kiln (20) to cause the thermal decomposition from at least one of: a product of the electrolytic subassembly (10), the other subassemblies (12, 13, 14) and their respective products, and a product of the thermal decomposition. The invention is intended to replace the traditional calcination process, including for the production of cement clinker, and can also be used to convert siderite ores into one or more iron oxides suitable for ironmaking. The captured carbon dioxide may be reacted with a second portion of the sodium oxide, or with sodium hydroxide derived therefrom, to produce sodium carbonate, thereby also providing a replacement for the Solvay process. In some embodiments, the method can even have a negative carbon footprint overall.