Abstract: A method of treating a kaolinitic clay which is intended for use as an ingredient in a ceramic composition which method comprises the steps of: (a) mixing with the kaolinitic clay from 0.1% to 15.0% by weight, based on the dry weight of the kaolinitic clay, of a smectite clay; and (b) subjecting a mass in a moist plastic state of the clay mixture formed in step (a) to mechanical working under conditions such that there is dissipated in the moist plastic mass at least 5 kJ of energy per kilogram of clay mixture on a dry weight basis.

Abstract: A new composite material which is useful as a pigment in paper making or paper coating is produced by precipitating a white insoluble pigment compound, eg calcium carbonate, in an aqueous suspension containing a mixture of fine particulate material eg titanium dioxide particles and fibers, eg cellulosic fibers. These suspended solids in the mixture are derived from separate stocks and added together to produce the composite pigment material. The new material is a bonded matrix of the fibers and the white pigment compound having particles of the fine particulate material, eg TiO2, dispersed and bonded within the matrix. The new material may exist in the form of particles in dry or wet form which may be further treated in a known way prior to use in paper making or paper coating.

Abstract: A method of producing a breathable film which comprises the steps of: (a) producing an inorganic filler by treating particles of an inorganic particulate material comprising an alkaline earth metal carbonate compound by reaction with a hydrophobising surface treatment agent comprising one or more aliphatic carboxylic acids having at least 10 chain carbon atoms to produce a hydrophobic coating on the particles under conditions such that the inorganic filler produced has a total surface moisture level comprising moisture adsorbed on the particles and trapped within the hydrophobic coating thereon of not greater than 0.1% by weight based on the dry weight of the inorganic particulate material; (b) producing a filled thermoplastic composition by mixing the inorganic filler produced in step (a) with a heated thermoplastic polymer; and (c) shaping the composition produced in step (b) by heat processing to form a film product.

Abstract: A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: A process for treating a nitride-containing ceramic material which includes the following steps: (1) comminuting the material to produce a particulate ceramic material having a particle size distribution such that at least 40% by weight of the particles have an equivalent spherical diameter (esd) smaller than 2 &mgr;m; and (2) a ferrosilicon separation step comprising one or both of the following steps: a) subjecting the particulate ceramic material produced in step 1 to differential sedimentation in a liquid medium to produce substantial separation of a light fraction from a heavy fraction, ferrosilicon required to be separated being included in the heavy fraction and refined particulate ceramic material being included in the light fraction; b) subjecting a suspension of the particulate ceramic material to magnetic separation to produce substantial separation of magnetic particulate material from non-magnetic particulate material, refined particulate ceramic material being included in the non-magnetic ma

Abstract: A method of heat treating kaolin particles which includes the steps of establishing in a furnace a heating zone suitable to calcine the particles and passing the particles rapidly through the heating zone whereby the particles are flash calcined in the heating zone, wherein the furnace is of the kind in which a toroidal fluid flow heating zone is established and the particles are heated in the said heating zone to a temperature of at least 800° C. but not greater than 1100° C. by application to the particles of a temperature increase rate greater than 103 Celsius degrees per second to give a rapid blistering of the particles caused by rapid dehydroxylation of the kaolin and wherein the particles have a residence time of less than 1 second in the said toroidal fluid flow heating zones.

Abstract: A method of dispersing a solid particulate material in an aqueous medium by addition to the aqueous medium of a dispersing agent wherein the solid particulate material is to be used as a filler or pigment in a sheet material which is required to come into contact with foodstuffs, wherein the dispersing agent is a composition comprising: (1) up to 0.25% by weight, based on the dry weight of the particulate solid material, of a water-soluble salt of a poly(acrylic acid) having a weight average molecular weight not greater than 20,000, and (2) from 0.02% to 1.5% by weight, based on the dry weight of the particulate solid material, of either (a) an anionic polyelectrolyte which comprises a water-soluble salt of a copolymer of acrylic acid with acrylamide; or (b) a water-soluble condensed phosphate salt.

Abstract: A pigment material for use in a coating composition suitable for coating a sheet material to be printed by an electrophotographic printer which pigment material comprises a blend of Components A and B as follows: Component A: a fine pigment material suitable for gloss coating of a sheet material the pigment material comprising particles at least 80% by weight of which have an equivalent spherical diameter (“esd”) of less than 2 &mgr;m and having a particle size distribution (“psd”) such that its d50 value, namely the particle esd value less than which 50% of the particles have an esd, is less than 1 &mgr;m; and Component B: a coarse pigment material having a psd such that its d50 value is from 2 &mgr;m to 10 &mgr;m, desirably 2 &mgr;m to 5 &mgr;m and such that not more than 2% by weight of the particles of the coarse pigment material have an esd greater than 15 &mgr;m, desirably not more than 2% have an esd greater than 10 &mgr;m; wherein the weight ratio of Component A to Component

Abstract: There is disclosed a process for preparing a concentrated aqueous suspension of a finely ground particular material, which process comprises (a) preparing an aqueous suspension comprising at least 20% by weight of the particulate material comprising calcium carbonate in coarse particular form; (b) grinding the suspension formed in step (a) in the presence of a polycarboxylate dispersing agent for the particular material in a grinding process where the pH is not less than 10 to produce an aqueous suspension wherein at least 90% by weight of the particles or the particulate material have an e.s.d. less than 2 .mu.m and 60% by weight have an e.s.d. less than 1 .mu.m; (c) adding an additive comprising an anionic polycarboxylate dispersing agent to the suspension of ground material formed in step (b). The process is characterized in that the aqueous suspension formed in step (c) has a pH which lies within the inclusive range 8.5 to 9.

Abstract: A method of treating water containing silicon-containing impurities in a concentration of up to 10,000 parts per million by weight of the water, by contacting the water over a period of time with a particulate solid which entrains silicon-containing impurities in the water and subsequently separating the water from the particulate solid, wherein the particulate solid is a high alumina cement which is anhydrous when first contacted by the water.