Interox Chemicals Limited

Laporte Industries Limited

David B Mobbs

Michael Robinson

Colin F McDonogh

Alastair McNeillie

David Shaw

Simon Pollard

Matthew James Jackson

Kirit Talati

Diana M Mounsey

A process for the production of a black iron oxide pigment from Fe,O,hematite iron oxide which may be an impure oxide produced by the &ldquo;Ruthner&rdquo; process or by other means, or which may be a mineral hematite. The process may be used to upgrade poor quality synthetic or natural hematite, or to improve their performance as red pigments, by conversion to black pigment with subsequent oxidation of the magnetite so produced back to hematite. The process uses a low temperature aqueous slurry reaction in which the hematite is contacted with a soluble source of Fe(II) ions in the presence of a soluble source of Fe(III) ions in an aqueous alkaline medium to convert the same to Fe,O,.

Process for the production of black iron oxide pigments

Adsorbents suitable for use to remove aromatic or polyaromatic hydrocarbons from liquids such as oils may be produced from an acid-activated siliceous clay containing adsorbed oil by treating to carbonize the oil and to activate the carbon so produced on the surface of the clay. The carbonization and activation steps may be conducted by heating in the presence of an activating agent which may be zinc chloride. Preferably zinc chloride activated material is subsequently steam-treated. The invention is particularly useful to reduce the content of hazardous polyaromatic hydrocarbons, such as benzo(a)pyrene, from edible oils.

Removal of benzopyrene from edible oils using an activated carbonized

Unless aqueous acidic hydrogen peroxide solutions are stabilized, an excessive rate of decomposition of hydrogen peroxide precludes their use for treatment of metal surfaces, such as of copper and copper alloys, during which use substantial concentrations of decomposition catalysts build-up in solution. Regular monitoring of the solutions for residual stabilizer content would demand sophisticated analytical equipment beyond the reach of many users. The invention provides a stabilizer in the form of a block of sparingly soluble material, whereby monitoring can be simply and readily effected visually or by a simple electrical or mechanical detection system. For copper/copper alloys preferred stabilizers are p-hydroxybenzoic acid and triphenyl carbinol.

Stabilization of metal-containing hydrogen peroxide solutions

Organic sulphides are extremely malodorous compounds that are found in gaseous or aqueous effluents from many industries such as paper and pulp manufacture, hydrocarbon refinering, tanneries, and in the synthesis of organic sulphur compounds. Their removal is necessary before such effluents can be discharged into the environment. In the present invention their removal is effected using hydrogen peroxide at a pH controlled to pH 8.5 to 11.5 and in the presence of a catalytic amount of a soluble tungstate. Such a process is especially applicable to the removal of dialkyl disulphides, which are regarded as being especially difficult to remove oxidatively. In especially preferred conditions, the pH is about pH 11 and about 3-4 moles H.sub.2 O.sub.2 is used per mole equivalent of sulphur, in the presence of at least 20 ppm sodium tungstate (as W).

Process for waste treatment

The invention relates to the preferential precipitation of cobalt from aqueous acidic sulphate solutions of nickel and cobalt. The separation is carried out by introducing at least a stoichiometric amount of Caro's Acid containing no more than a small amount of hydrogen peroxide into the nickel/cobalt solution progressively over a period of at least an hour, while maintaining the solution of a pH from 3.1 or 3.5 up to 4.7 by addition of an alkali metal hydroxide carbonate or bicarbonate, or at 4.3 to 4.7 with the corresponding ammonium compound, and, thereafter separating the precipitate from the aqueous cobalt depleted solution. In preferred features, the Caro's Acid solution used contains hydrogen peroxide in a mole ratio to peroxomonosulphuric acid of not more than 1:10; the Caro's Acid solution is introduced continuously or in increments of less than 1% of the total over a period of at least an hour; the Caro's Acid is produced by reaction between 93-98% sulphuric acid and 65-72% aqueous hydrogen peroxide in a mole ratio of 2.7:1 to 3.5:1; the Caro's Acid solution is diluted before use; and particular amounts of Caro's Acid are used depending upon the nature of the nickel/cobalt solution, the mode of treatment, and the nature of the neutralizing agent. Further separation can be effected by subsequent water and particularly not acid washing of the precipitate.

Separation of cobalt and nickel by oxidative precipitation with

Granular active carbon having satisfactory adsorbency and hardness characteristics and having a high proportion of its porosity in the below 2000 A range is produced from granules prepared from coal fluid energy milled until not more than 1% of the particles have diameters above 38 microns. The coal has a low ash and high carbon content and may have a British Standard Swelling number from 2 to 7 although it is preferred for the volatile matter content of the coal to be not more than 40% on a dry ash free basis. The granules may be produced by compacting milled particles having a temperature of from 50.degree. C to 250.degree. C between unheated pressure rolls.

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Handforth, United Kingdom

David B Mobbs