Atochem

Produits Chimiques Ugine Kuhlmann

Elf Atochem S.a.

Uranium Pechiney Ugine Kuhlmann

Jean-Pierre Cuer

Antoine Floreancig

Christian Colombier

Jean-Pierre Disson

Jacques Dugua

Jean Wojcik

Claudine Biver

Claudine Bonnel

Nicole Texier

Claude Aubineau

Francois Garcia

Francois Delmas

Process for reducing the concentration of multivalent cations in aqueous

Metal and/or metalloid nitride and/or carbide powders, e.g., amorphous or crystalline spherical particulates having a mean diameter greater than 0.2 .mu.m 90% of which being less than 0.4 .mu.m in size, well suited for the production of ceramic shaped articles exhibiting good thermomechanical properties and useful, for example, in the automotive and aeronautic fields, are prepared by flash pyrolyzing coarse drops of a precursor compound convertible into such nitride and/or carbide, at an elevated temperature and for such period of time as to convert the precursor compound into said amorphous or crystalline powder.

Metal/metalloid nitride/carbide ceramic powders prepared by flash

Novel basic aluminum chlorosulfate solutions, having a basicity ranging from 45% to 70% and wherein more than 80% of the SO.sub.4.sup.2- values are complexed, prepared, e.g., by reacting calcium carbonate with a chlorosulfuric solution of aluminum, are useful coagulating and flocculating agents for the removal of impurities from aqueous media, notably to prepare potable water therefrom; the water thus treated contains but trace amounts of residual aluminum values.

Basic aluminum chlorosulfate flocculating agents

A process for the preparation of novel polysiloxazane compositions which comprises reacting at least one halosilane having the formula (R.sub.1).sub.a (R.sub.2).sub.b Si(Y).sub.4-(a+b) with at least one hydrazine having the formula NHR.sub.3 -NHR.sub.4 and water, wherein R.sub.1 and R.sub.2 are a hydrogen atom or a methyl, ethyl, vinyl or phenyl radical; R.sub.3 and R.sub.4 are hydrogen atoms, Y is a halogen atom and (a+b) is an integer between 0 and 3 and preferably 2. Polysiloxazane polymer compositions formed with polysiloxazanes prepared by the process described above comprise units of formula: ##STR1## combined with units of formula: ##STR2## and, if desired, units of formula: ##STR3## and, if desired, with units of formula: ##STR4## wherein radicals R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be identical or different, may denote a hydrogen atom, a saturated or unsaturated aliphatic hydrocarbon radical or a mono- or polycyclic aryl, alkylaryl or arylalkyl radical, and wherein these radicals have a total molecular mass greater than 350.

Process for preparing polysiloxazane compositions and the products

A process for the manufacture of perborate monohydrate by the dehydration of perborate tetrahydrate at an absolute pressure maintained between 0.03 and 0.13 bar and a temperature of the perborate to be dehydrated not exceeding about 70.degree. C.

Process for the manufacture of sodium perborate monohydrate from sodium

A process for separating by means of an organic agent the uranium and the molybdenum contained in an aqueous liquor originating from a sulphuric attack of an urano-molybdeniferous ore which involves placing the said attacking liquor in contact with an organic extraction solution containing at least one tertiary or secondary amine in an (amine)/(Mo) molar ratio of up to 0.8, separating the molybdenum-charged organic phase from the uranium-rich aqueous phase, treating the organic phase with an aqueous liquor containing at least one mineral agent in the form of alkaline and ammonium hydroxide and/or carbonates to form an aqueous solution which is concentrated in molybdate.

Separation of uranium and molybdenum using a solvent

Processes for treating nitric effluents from plants so that a non-polluting stream is obtained and nitric values are recovered, which processes comprise acidifying nitric effluent, liquid-liquid extraction of the acidified effluent with an extraction agent comprising a neutral phosphoric ester and at least one long-chain alkylamine, and re-extraction of the loaded extraction agent with ammonia, thereby regenerating the extraction agent and providing ammonium nitrate, while at the same time providing a substantially nitric-free effluent.

Method of treating nitric effluents

Wet-process phosphoric acid is purified sufficiently to take the place of purified thermal-process acid by a method which comprises (1) contacting an initial aqueous phase of a crude wet-process phosphoric acid with a water-immiscible solvent for phosphoric acid and allowing phosphoric acid and anionic impurities to be extracted or charged into said solvent leaving the cationic impurities in the first aqueous phase; (2) mechanically separating the charged solvent from the initial aqueous phase and contacting the charged solvent with water to allow the phosphoric acid and anionic impurities to be re-extracted into a second aqueous phase; (3) contacting the second aqueous phase with a water-immiscible alkaline liquid medium and allowing the anionic impurities to be transferred to said alkaline medium; and (4) mechanically separating the second aqueous phase containing pure phosphoric acid.

Process for purifying phosphoric acid

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.

Growing community of inventors

Francheville le Haut, France

Jean-Pierre Cuer