Abstract: A method of preparing precipitated calcium carbonate which comprises slaking quicklime in an aqueous medium, passing the suspension of calcium hydroxide through a sieve having an aperture size in the range of 40 to 70 microns, carbonating the calcium hydroxide and separating the calcium carbonate from the aqueous medium in which it is suspended. The sieved calcium hydroxide is subjected to high energy, high shear agitation which is terminated prior to carbonation. During the carbonation, the suspension of calcium hydroxide is subjected to relatively lower energy and shear agitation compared to the previous high energy, high shear agitation.

Abstract: There is disclosed a paper coating composition comprising, in aqueous suspension, an adhesive and a treated paper coating pigment prepared by the following process:(i) suspending a paper coating pigment in water to form a suspension containing at least 5% by weight of the pigment, the pH being adjusted, if necessary, to lie below 7.5;(ii) mixing with the suspension formed in step (i) a water-soluble organic compound having a plurality of primary and/or secondary amine groups and a number average molecular weight not greater than 1000; and(iii) at least partially dewatering the mixed suspension resulting from step (ii) to form a dewatered suspension of a treated paper coating pigment containing not more than about 30% by weight water;characterized in that the water soluble organic compound is added in step (ii) in an amount sufficient to decrease the 5 poise viscosity concentration of an aqueous suspension of the treated pigment relative to that obtained with the untreated pigment.

Abstract: There is disclosed an aqueous suspension of a particulate calcium-containing filler in which the particles of filler are surface treated with a dispersing agent comprising an anionic polyelectrolyte, characterized in that said dispersing agent further comprises sufficient of a cationic polyelectrolyte to render the particles cationic. The aqueous suspension is useful in the manufacture of paper.

Abstract: There is provided an elastomeric composition including a kaolinitic clay mineral filler, characterised in that said kaolinitic clay mineral (a) is a hydrous kaolinitic clay mineral which has a content of non-exchangeable alkali metal cations not exceeding 10,000 ppm (parts by weight per million parts by weight of dry clay) and a content of exchangeable alkali metal cations not exceeding 750 ppm or (b) is a calcined kaolinitic clay mineral prepared by calcining a hydrous kaolinitic clay mineral having a content of non-exchangeable alkali metal cations not exceeding 10,000 ppm and a content of exchangeable alkali metal cations not exceeding 750 ppm.

Abstract: Apparatus for grinding particulate solid material in a substantially dry state, the apparatus comprising, means for introducing particulate solid material into a grinding chamber (4), a perforated base (8) of the grinding chamber (4) through which gas is introduced to provide an upward flow of gas passing through the particulate solid material and an impeller (42) rotating in the grinding chamber (4) to agitate the particulate solid material. The perforated base (8) has a central imperforate area (10) which causes the gas to pass preferentially through the region near the walls of the grinding chamber (4). In addition, a horizontal baffle plate (17) having a central opening (18) is positioned in the grinding chamber (4) at a height above the perforated base (8) which is not greater than one half of the transverse width of the grinding chamber (4).

Abstract: The calcium carbonate is prepared by:(a) slaking quicklime in an aqueous medium;(b) carbonating and neutralizing the suspension of slaked lime formed in step (a) using a gas comprising carbon dioxide; and(c) separating the precipitated calcium carbonate formed in step (b) from the aqueous medium in which it is suspended. There is added 0.01% to 15% by weight, based on the weight of dry calcium oxide, of a reagent having one or more active hydrogen atoms (or a salt thereof), to the aqueous medium in which the quicklime is slaked in step (a).The reagent is selected from the group consisting of triethanolamine, mannitol, diethanolamine, bicine, morpholine, tri-isopropanolamine, N-ethyl diethanolamine, N,N-diethylethanolamine and sodium boroheptonate.

Abstract: There is disclosed a process for controlling the deposition of pitch in a paper-making process, wherein there is incorporated into the paper-making composition a coated inorganic particulate material which comprises a clay mineral coated with (a) a cationic polyelectrolyte which is a water-soluble substituted polyolefin containing quaternary ammonium groups or with (b) an inorganic gel or with (c) a mixture of (a) and (b).

Abstract: There is disclosed a head for use in an apparatus for coating a sheet member which comprises a first body portion, securable at a predetermined spacing from the surface to be coated, a coating blade securable to the first body portion and projecting towards said surface to be coated and a second body portion which is resiliently mounted with respect to the first body portion and which, in use, defines with the sheet material with which it is in contact and with the blade, a coating pool which is fed by a coating reservoir and from which the coating composition is applied to the sheet material. Also disclosed is an apparatus including the head and a method of coating a sheet material with the head.

Abstract: A method and apparatus are disclosed for obtaining a measurement indicative of the aspect ratio of non-spherical particles in suspension. Conductivity of the suspension is measured for two different orientations of the particles between measuring points and the difference between the conductivities measured is used as an indication of the particle aspect ratio. The particle orientation will be aligned in one measurement and in the other may be aligned and transverse to the first orientation direction or random. Alternatively, there may be a single aligned orientation but transversely directed conductivity measurements.

Abstract: There is disclosed a process for purifying a calcium carbonate-containing mineral which process comprises the following steps:a) mixing the calcium carbonate-containing mineral with water and a dispersing agent to form a suspension containing from 60% to 80% by weight of the dry mineral;b) comminuting the suspension of calcium carbonate-containing mineral prepared in step a) to give a product containing not more than 5% by weight of particles which are retained on a sieve having a nominal aperture of 53 microns and not more than 50% by weight of particles which are smaller than 2 microns e.s.d.

Abstract: There is disclosed an apparatus for coating sheet material. The apparatus includes a rotatable backing roll (4) upon which a sample of sheet material may be mounted to form a cylinder, a coating head (9) including a blade (22), an outlet (21b) for dispensing a coating composition and a supply means (18) for supplying a coating composition to the outlet (21b) in the region of the coating edge of the blade (22), and means for enabling the coating head (9) to be moved in operation parallel to the axis of rotation of the backing roll (4) and in contact with the sheet material mounted thereon whilst the backing roll (4) is rotated, whereby a strip of sheet material may be coated of resultant helical form, wherein the supply means (18) includes an element which comprises a matrix of tubular passageways (19) longitudinally disposed with respect to the flow of coating composition through the coating head (9).

Abstract: There is disclosed a particulate inorganic material, suitable for use in a detergent composition, comprising base granules of a smectite clay coated with a white inorganic material. Also disclosed is a detergent composition comprising a particulate inorganic material and a process for making the particulate inorganic material.

Abstract: There is disclosed a porous inorganic material, suitable for use as a support material for biological macromolecules, comprising substantially spherical particles of an aluminosilicate ceramic material, any internal cavities present in a particle occupying no more than 10% of the volume of the particle, each particle having a diameter in the range of from 5 micrometers to 5 millimeters and consisting predominantly of an open three-dimensional matrix of needles of the ceramic material each of which needles has a length in the range of from 2 to 20 micrometers and a width in the range of from about 0.2 to 2 micrometers, the ceramic needles defining between them interconnecting pores of width of from 0.1 to 5 micrometers. Also disclosed is a method of preparing such a porous inorganic material.

Abstract: There is disclosed a process for preparing an organic polymer composition which includes an inorganic filler, which comprises: (i) treating an inorganic filler by adding to a particulate white inorganic material a natural or synthetic latex composition which comprises a suspension of polymer particles in water wherein the latex solids are selected from the group consisting of acrylic copolymers and vinyl acetate copolymers, and dewatering and drying the resultant mixture, the amount of the natural or synthetic latex composition added being such as to provide from 1% to 10% by weight of latex solids based on the weight of dry inorganic material; and (ii) combining the treated inorganic filler with an organic polymer. Also disclosed is an organic polymeric composition comprising an organic polymer and an inorganic filler.

Abstract: A process for preparing an inorganic filler comprises admixing a particulate inorganic material with a natural or synthetic latex composition and an aqueous suspension of fine carbon black, and dewatering and drying the resultant mixture, the amount of the natural or synthetic latex composition added being such as to provide a coating on the inorganic mineral of from 1% to 10% by weight of latex solids based on the weight of dry inorganic material.

Abstract: There is disclosed a porous inorganic material suitable for use as a support for immobilizing biological macromolecules and which comprises a 3-dimensional network of defect aluminium-silicon spinel, said network defining an interconnecting array of pores predominantly in the size range of from 100 to 1000 .ANG..A process for preparing the porous inorganic material is also disclosed.

Abstract: There is disclosed a granular detergent composition comprising granules of a chemical reagent the surfaces of which are provided with a coating comprising an organophilic clay mineral.

Abstract: A particulate porous material suitable for use as a high surface area column packing material comprises particles substantially all of which are not smaller than 5 micrometers and not larger than 1 millimeter in diameter, and each particle is in the form of a substantially cellular body and consists predominantly of an open, three-dimensional matrix of crystal of mullite which define between them interconnecting pores having a width in the range of from 5 nanometers to about 2 micrometers. The particles can be coated with a reactive layer. There is also disclosed a process for producing the particulate porous material wherein a particulate product comprising particles substantially all of which are between 5 micrometers and 1 millimeter in diameter and consisting predominantly of a mixture of mullite crystals and silica is treated with a concentrated aqueous solution of an alkali metal hydroxide at a temperature of at least 50.degree. C.

Abstract: There is disclosed a method for preparing a thickened cleaning composition containing sulphamic acid, according to which an aqueous suspension of a particulate smectite clay suspension is formed, which is mixed with the sulphamic acid to form a thickened aqueous solution of the acid.

Abstract: There is provided a porous cellular material comprising a plurality of cavities each defined by a substantially spherical wall formed of a rigid intermeshing matrix of ceramic needles said wall being pierced by at least one aperture to provide access to the cavity, and the or each aperture having a diameter such that the ratio of the diameter of the aperture to the diameter of the cavity into which the aperture opens is in the range of from 0.1:1 to 1:1.