Abstract: A new process of synthesis of optically active .alpha.-amino acids is described through nitrosation in a non-aqueous, aprotic system of the corresponding N-carbamyl derivatives followed by decomposition of the thus obtained N-nitroso derivatives in aqueous acidic medium. The process, which is of a general applicability, leads to a remarkable increase in the reaction yields, due to the suppression of the main side reaction leading to the corresponding .alpha.-hydroxy-acid. Some N-nitroso intermediates, which can be recovered from the process of the invention, are also described.

Abstract: A new process of synthesis of optically active .alpha.-amino acids is described through nitrosation in a non-aqueous, aprotic system, of the corresponding N-carbamyl derivatives followed by decomposition of the thus obtained N-nitroso derivatives in aqueous acidic medium. The process, which is of a general applicability, leads to a remarkable increase in the reaction yields, due to the suppression of the main side reaction leading to the corresponding .alpha.-hydroxy-acid. Some N-nitroso intermediates, which can be recovered from the process of the invention, are also described.

Abstract: Ferrous sulphate heptahydrate obtained as a by-product of the production of titanium dioxide by the sulphate process is converted into a non-polluting, free-flowing particulate neutralization product by contacting said sulphate with calcium hydroxide as a neutralizing agent in a molar ratio between said neutralizing agent and said ferrous sulphate of at least 1:1, and reacting the resulting mixture under agitation at a temperature not exceeding 60.degree. C. and for a contact time not exceeding five minutes.

Abstract: This invention describes the preparation of a red pigment of iron oxide from ferrous salts, by simultaneous reduction of organic nitro derivatives.

Abstract: This invention describes a process for preparing a yellow iron hydroxide pigment from inorganic ferrous salts and aromatic nitro compounds.

Abstract: Hydrolysis of a titanyl sulphate solution is carried out according to the autonucleation method of gradually adding the solution to a body of water at a substantially constant rate over 10-20 minutes, in such a way as to obtain an ionic concentration after one minute of feeding of from 75 to 105 g/l, the concentration of sulphuric acid in the final hydrolysis solution being regulated to a value of from 310 to 330 g/l by adding water from the commencement of clouding of the hydrolysis solution up to the end of hydrolysis.

Abstract: A soil modifier comprising from 80 to 95% by weight of a mixture of ferric oxide and ferric sulphate in an oxide/sulphate weight ratio of from 0.25:1 to 1:1, is prepared by calcining at 500.degree.-600.degree. C in an oxidizing atmosphere a blend of by-product obtained in the manufacture of titanium oxide by the sulphate process, with at least 20% by weight with respect to said by-product, of a material based on ferric sulphate and/or ferric oxide. Calcining is then continued under the same conditions, replacing said material in the blend continuously fed in by a recycle fraction of the product continuously discharged.

Abstract: Novel compositions for use in agriculture as soil improvers and fertilizers comprising as essential components ammonium sulfate and ferric oxide hydrate. By-products obtained in the production of titanium dioxide from ilmenite or ilmenite slag in the sulfate process and substantially consisting of ferrous sulfate heptahydrate are reacted with ammonia and that the reaction product obtained, consisting substantially of ammonium sulfate and ferrous hydrate, is subsequently oxidized until a composition is obtained which substantially consists of ammonium sulfate and ferric oxide hydrate.

Abstract: A soil modifying composition and a concentrated solution of ammonium sulphate with a high purity degree are obtained from by-products consisting essentially of ferrous sulphate heptahydrate, obtained in the production of titanium dioxide from ilmenites by the sulphate process, by contacting solid particles of said by-products with gaseous ammonia, lixiviating the resulting product with water, thereby to recover said concentrated solution of ammonium sulphate, the dried residual solid yielding said soil modifying composition.

Abstract: Soil modifiers comprising from 80 to 95% by weight of a mixture of ferric oxide and ferric sulphate in an oxide/sulphate weight ratio of from 0.2:1 to 2:1 are prepared by calcining at 500.degree.-600.degree. C in the presence of an oxidizing gas a material consisting essentially of ferrous sulphate with an average number of molecules of crystallization of from 1 to 5 obtained by partial dehydration of the waste materials, consisting essentially of ferrous sulphate heptahydrate, obtained in the manufacture of titanium dioxide from ilmenites or ilmenite slags by the sulphate process. These modifiers are particularly suitable for clay soils.

Abstract: A solution of active nuclei for the hydrolysis of titanium sulphate and for the rutilisation of titanium dioxide in the manufacture of titanium dioxide in tutile form in the method via sulphate is prepared by transforming titanium tetrachloride into a compound of the formula Ti(OH).sub.x Cl.sub.y, wherein x ranges from 1 to 3, y from 3 to 1 and x + y is equal to 4 by contact with steam in the vapor phase, and contacting the reaction products with an aqueous solution of sodium hydroxide to form an aqueous suspension of titanium hydroxide having a TiO.sub.2 content of from 10 to 30 grams/liter and a pH value of from 3 to 4.

Abstract: Titanium sulphate solutions obtained in the sulphate process from titaniferous materials are hydrolized by contacting at 88.degree.-98.degree. C water with a first titanium sulphate solution having a TiO.sub.2 titer of 230-260 g/l and an acid factor of 1.75-1.85, adding at 88.degree.-98.degree. C to the mixture a second titanium sulphate solution having a TiO.sub.2 titer of 230-260 g/l and an acid factor of 2.1-2.4 and heating the resulting mixture at boiling point. A volumetric ratio of from 3:100 to 12:100 is maintained between the first and the second solution.

Abstract: A process for the joint production of titanium dioxide and sodium tripolyphosphate from ores of titanium and phosphorus, and from sulphuric acid, in which the titanium dioxide is produced by the "sulphate process" and the impure dilute aqueous solution of sulphuric acid resulting therefrom is concentrated and used in the initial attack of phosphatic ones to provide a solution containing vanadium and chromium which can be removed without requiring any preventive conversion. The resulting sodium phosphate is then converted to sodium tripolyphosphate in a known way.

Abstract: Process for the purification of titanium tetrachloride, in which the said titanium tetrachloride is brought into contact with a purifying agent consisting of an inert support in granular form on which metallic sodium or other reducing metal has been deposited in sub-divided form, the said contact taking place either on crude liquid titanium tetrachloride with subsequent distillation to recover the purified titanium tetrachloride or on crude vaporised titanium tetrachloride with subsequent condensation to recover the purified titanium tetrachloride.

Abstract: Compositions useful in agriculture as soil modifiers and fertilizers are prepared by contacting the waste materials, obtained in the manufacture of titanium dioxide from ilmenites by the sulphate process, and which consist essentially of ferrous sulphate, with oxides, hydroxides or carbonates of alkali metals or alkaline earth metals or ammonium carbonate, and then submitting the reaction product to oxidation to convert the ferrous hydroxide into ferric hydroxide. Ferric hydroxide is further converted to ferric sulphate by treatment with sulphuric acid.