Abstract: A process for producing titanium dioxide which discharges no waste is disclosed. In a first step, a sulfuric acid solution containing titanium ion with one or more kinds of metal ions is contacted with a first organic solvent to extract the titanium ion as a sulfuric acid complex. The organic solvent containing the extracted titanium as a sulfuric acid complex (titanyl sulfate) is contacted with an aqueous liquid to strip the titanium into the aqueous liquid and regenerate the first organic solvent. In a second step, the aqueous liquid containing the titanium is subjected to hydrolysis to form insoluble titanium hydroxide, and the titanium hydroxide is washed with dilute sulfuric acid and/or clear water.

Abstract: A method for manufacturing titanium oxide, comprising bringing a sulfuric acid solution containing predominantly titanium ion together with one or more kinds of metal ions into contact with an organic solvent containing one or more species selected from the group of oxygen-containing organic solvents, alkyl amines, and alkyl aryl amines to extract the titanium ions in a form of a sulfuric acid complex from the sulfuric acid solution, and bringing the organic solvent containing the extracted titanium into contact with water or an aqueous dilute sulfuric acid solution to inversely extract the titanium from the organic solvent to the water or the dilute sulfuric acid solution and to regenerate the organic solvent.

Abstract: A method for neutralization of sulfuric acid containing Fe ions, comprising adding ions selected from the group consisting of Na ions, K ions, Mg ions, Ca ions and NH.sub.4 ions in the form of a compound containing chlorine to a sulfuric acid solution to be treated in an amount corresponding at least to the chemical equivalent to SO.sub.4.sup.2-, and bringing the resultant solution into contact with an organic solvent containing oxygen or comprising alkylamine for extracting Fe ions from said aqueous solution into the organic phase as chloride complex. Iron chloride can be recovered from the organic phase by distilling or evaporating the organic solvent or by extracting back it into water.

Abstract: Process for electrolytically producing metals of Ni, Co, Zn, Cu, Mn, and Cr, comprising, electrolyzing an aqueous solution containing ions of a metal as main component selected from Ni, Co, Zn, Cu, Mn, and Cr in a cathode compartment to deposit the metal electrolytically on a cathode, the cathode compartment being separated by one or more diaphragms from the remainder of the solution where iron or a metal containing iron is used for material of corrosible anode, and maintaining the concentration of iron ion in the solution circulating in the anode compartment at a low level by bringing the whole or a part of the circulating solution into contact with an organic solvent which is prepared by adding petroleum hydrocarbon for dilution of one or more extracting agents selected from the group consisting of carboxylic acids, alkylaryl phosphoric acids, hydroxyoximes, alkyl phosphoric acids, alkylamines, ketones, alkylamides, and neutral phosphoric acid esters, to extract and remove the iron or the chloro-complex ion

Abstract: Process for producing fluorides of Mo, W, Nb, Ta, V, Re, Ti, Zr, Hf, Co, Ni, Cr, Sb, Sn, Zn, Pb, Al and rare earth metals comprising heating fluorine-containing ammonium salts of corresponding metals in a stream of an inert or reducing gas to convert them into fluorides of the metals.

Abstract: A crystallizer comprising a mixing zone of an organic solvent containing ions of a metal extracted therein and an aqueous separating solution provided at the upper part of a main crystallizer body, a lower-part opened organic solvent settling zone provided outside of the mixing zone for receiving and settling the organic solvent overflowing out of the mixing zone, a crystals developing zone having a downwardly narrowing cross section provided at the lower part of the main crystallizer body, a descending pipe extending from the lower end of the mixing zone to the lower part of the crystals developing zone, a crystals fluidizing medium inlet provided at the lower end of the crystals developing zone, a separating solution discharge pipe and a crystals discharge pipe.

Abstract: A process for selectively stripping and separating iron ions from an organic solvent (A) which comprises bringing the organic solvent (A) containing iron and zinc ions, and containing one or more compounds selected from the group consisting of alkyl phosphoric acid, alkyl-aryl phosphoric acid, alkyl thio phosphoric acid and alkyl-aryl thio phosphoric acid together with a petroleum hydrocarbon as a diluent, into contact with an aqueous solution containing NH.sub.4.sup.+ and F.sup.- ions so as to selectively strip the iron ions into the aqueous solution despite the coexistence of zinc ions.

Abstract: A process for treating and recovering pickling waste liquids used for the pickling of stainless steel such as nitric-hydrofluoric acid, nitric acid, hydrochloric acid and, sulfuric acid is disclosed, which comprises recovering the nitric-hydrofluoric acid and the iron oxide or metallic ion from the waste liquids of nitric-hydrofluoric acid and nitric acid by two solvent extraction processes and recovering the Cr and Ni containing ferrite from the waste liquids of sulfuric acid or hydrochloric acid by a ferrite formation process. When the waste acid is sulfuric acid, gypsum of a high purity can be obtained.

Abstract: A process for production of metallic iron by heating ammonium iron fluoride or iron fluoride in hydrogen stream.

Abstract: A process for production of metallic iron by heating ammonium iron fluoride or iron fluoride in a hydrogen stream.

Abstract: A process for the production of aluminum oxide from aluminum compounds containing fluorine comprising:(1) extracting aluminum ions with an organic solvent containing one or more compounds selected from the groups of alkyl phosphoric acid, alkyl and aryl thio phosphoric acid, carboxylic acid and hydroxime together with a petroleum hydrocarbon as a diluent;(2) preparing aluminum compounds containing fluorine by stripping the aluminum ions in the resultant organic solvent from the step (1) in contact with an aqueous solution containing one or more compounds selected from the groups of HF, NH.sub.4 HF.sub.2, NH.sub.4 F or KHF.sub.2 and simultaneously regenerating the organic solvent; and(3) producing aluminum oxide by heating the resultant aluminum compounds containing fluorine from the step (2) in gas stream containing oxygen or H.sub.2 O.

Abstract: This invention relates to a process for recovery of waste H.sub.2 SO.sub.4 and HCl which are used for pickling metallic materials and articles and contain a large quantities of Fe ions. Furthermore, it offers a process for the recovery of H.sub.2 SO.sub.4 and HCl from waste H.sub.2 SO.sub.4 which contains large amounts of Fe ions after removal of Ti ions by a hydrolysis process in the production of TiO.sub.2 and also for the recovery of high-purity electrolytic iron or iron hydroxide.

Abstract: This invention relates to a process for recovery of waste H.sub.2 SO.sub.4 and HCl which are used for pickling metallic materials and articles and contain a large quantities of Fe ions. Furthermore, it offers a process for the recovery of H.sub.2 SO.sub.4 and HCl from waste H.sub.2 SO.sub.4 which contains large amounts of Fe ions after removal of Ti ions by a hydrolysis process in the production of TiO.sub.2 and also for the recovery of high-purity electrolytic iron or iron hydroxide.