Abstract: A composition suitable for adding to water to produce a water-resistant hydraulic solid which composition comprises components (a), (b) and (c) as follows:(a) calcium sulphate hemihydrate;(b) portland cement;(c) calcined clay having a pozzolanic activity;wherein the percentages by weight of components (a), (b) and (c) in the said composition are in the respective ranges:(a) from 20% to 98%;(b) from 1% to 50%;(c) from 1% to 30%;the percentages of components (a), (b) and (c) adding to 100% in the three component composition.

Abstract: A method for producing a high solids slurry of an acid-resistant precipitated calcium carbonate for shipping purposes is disclosed. A low solids of about 18 wt. % to 20 wt. % solids slurry is treated with a chemical additive, such as sodium aluminate, in order to impart acid resistance to the calcium carbonate, and is dewatered to form an intermediate solids slurry of about 44 wt. %. This intermediate solids slurry is then diluted with a fraction of the low solids slurry which was treated with the chemical additive, in order to bring the intermediate slurry to a final high solids slurry of about 35 wt. %. Acid is added to the final product slurry in order to reduce the pH of the final slurry to within a buffering range of about 7.0 to 6.5. The final product slurry of about 35 wt. % comprises an acid-resistant calcium carbonate composition with a pH of about 7.0 which can be shipped for ultimate use when making paper under neutral pH conditions.

Abstract: A method of producing a multiple coated cellulosic sheet product having a surface which is smooth, bright and capable of being printed upon, includes the steps of coating a substrate comprising a cellulosic sheet with a first layer of an inorganic pigment-containing aqueous coating composition, and coating the first layer with a second layer of an inorganic pigment-containing aqueous coating composition to form a product in which the first layer is bonded to the cellulosic sheet and the second layer is bonded to and inseparable from the first layer, wherein there is incorporated into the first layer a sizing agent in an amount of up to 0.6% by weight based on the dry weight of the pigment present in the first layer. The sizing agent is selected from alkene ketene dimers, alkenyl succinic anhydrides, and anionic polyurethane sizes.

Abstract: An inorganic particulate material suitable for use as a pigment material in a paper coating composition has a particle size distribution which when represented as a graph of percentage of weight of particles having an equivalent spherical diameter (esd) of given size versus particle esd expressed in microns and plotted on a logarithmic base 10 scale has the following features: (a) a first peak at the coarse particle size and a second peak at a finer particle size and a dip or trough between the first and second peaks; (b) the mean particle size x.sub.1 of the particles making up the first peak being 2 to 4 microns; (c) the relationship between the first and second peaks being such that the value of the mean particle size x.sub.2 of the particles making up the second peak is separated in the particle size distribution graph from the value of x.sub.1 by at least 0.5; and (d) the minimum of the dip or trough is at a given particle esd dimension of between 0.5 and 5 microns.

Abstract: A method of producing a composition for coating fibrous sheet products includes adding a surface treatment agent in an aqueous emulsion or solution form to an aqueous suspension of a dispersed inorganic particulate material comprising kaolin to improve the coating composition, e.g., rheology, and the rotogravure printing process, e.g. runnability. The dispersing agent is polycarboxylate. The surface treatment agent is in a substantially free state, has a hydrophobic group, and is selected from the group consisting of: (i) a long chain fatty acid; (ii) a long chain fatty alcohol; or (iii) an anionic surfactant having a long chain hydrophobic group and a polar group. A hydrophilic adhesive is added to the dispersed aqueous suspension during or while the surface treatment agent is added to the dispersed aqueous suspension. This method is used to produce a coated and a printed coated cellulosic sheet member.

Abstract: A method of preparing an inorganic particulate material suitable for incorporation in a composition comprising a hydrophobic polymeric material includes the steps of (a) processing an aqueous suspension of an inorganic particulate material in the presence of a water soluble dispersing agent; (b) adding a surfactant to the particulate material; and (c) drying the particulate material. The inorganic particulate material to which the surfactant has been added may be further treated by addition thereto of a further surface treatment agent which is a hydrophobising surface treatment agent, eg. a carboxylic acid or salt thereof. The surfactant may be a non-ionic surfactant and may be added to the particulate material whilst in the form of a dispersed aqueous suspension. The further surface treatment agent may be added to the particulate material during or after the drying step (c).

Abstract: An improved method for dry milling calcined kaolin clays involves use of an effective amount of an ammonium polyacrylate dry grinding aid which is applied to a calcined kaolin clay product prior to dry milling. This improves flowability of the product through the mill, resulting in an increase in the grinding efficiency and, therefore, an increase in the production rate of the mill. The final product displays an increase in Hercules high shear viscosity, and therefore, an increase in the rheology in very high solids aqueous slurries, which is particularly useful in the coating of paper and paperboard products.

Abstract: A method of treating a dilute aqueous suspension of solid particulate material comprising waste material from a process for recovering petroleum from oil sand includes diluting the suspension with at least 75% of its own volume of water thereby to increase the settling rate of the particulate material and allowing the particulate material to settle to form a concentrated solid sediment. The treated suspension may have been obtained from a process in which an alkaline solution is used to treat the oil sand. The water from which the concentrated solid sediment is separated may be returned to the process for recovering petroleum from oil sand. The solid sediment may be transferred to a separation vessel in which it is fractionated into a coarse particle fraction and a fine particle fraction. The fine particle fraction may comprise essentially particles having an equivalent spherical diameter not greater than 3 .mu.m. The concentrated solid material recovered may be calcined to form a pozzolanic material.

Abstract: A method is described for the treatment of a solid containing material obtained from effluent from an industrial plant or process, eg. a plant for the de-inking of waste paper. Such effluent comprises an aqueous suspension of solids comprising organic material and inorganic particulate material. The inorganic particulate material contains a substantial amount of calcium carbonate and is likely also to contain kaolin or metakaolin. The solids may also contain carbon particles. The method includes subjecting the solid containing material to a heat treatment process such that the temperature is controlled to be maintained in the range 600.degree. C. to 800.degree. C. preferably 600.degree. C. to 750.degree. C., to cause burning of the organic material without decomposition of more than about 50% by weight, preferably not more than about 10% by weight, of the calcium carbonate present to produce a particulate calcium carbonate-containing inorganic material substantially free of organic material.

Abstract: There is disclosed a method for the preparation of a precipitated calcium carbonate (PCC) for use as a pigment in paper coating compositions, the method comprising the steps of (a) carbonating an aqueous lime-containing medium to produce an aqueous suspension of a PCC predominantly in a selected crystal form, (b) at least partially dewatering the PCC-containing suspension; and (c) subjecting the PCC-containing suspension to comminution by high shear attrition grinding with an attrition grinding medium. Steps (b) and (c) may be applied in either order, ie. (b) followed by (c) or alternatively (c) followed by (b). The dewatering step (b) is preferably carried out using a pressure filter device operating at a pressure of at least 5 MPa, preferably at least 10 MPa. A pH reduction step may be applied after steps (b) and (c). Also disclosed are pigments produced by the method and pigment and paper coating compositions including such pigments.

Abstract: A process is described for preparing .beta.'-sialon comprising heating a mixture of particles comprising from 70% to 90% by weight of particles of an aluminosilicate material and from 30% to 10% by weight of particles of a carbonaceous material at a temperature in the range of from 1300.degree. C. to 1600.degree. C. in nitrogen in a vessel in a manner such that the particles are in substantially continuous motion relative to each other and relative to the nitrogen. The residence time of the particles in the vessel does not exceed 3 hours.

Abstract: A decanter centrifuge for separating a feed suspension of a particular solid material in a liquid into two fractions, i.e. a heavy fraction containing heavy particles and a light fraction containing light particles, or no particles at all, is described. The centrifuge has a rotatably mounted elongated bowl having closed ends with a side wall extending therebetween. A helical scroll is rotatably mounted coaxially within the bowl, and the bowl and the scroll may be rotated at different rotational speeds. A pipe coaxially mounted in a tubular shaft and rotatably supporting the scroll, feeds the suspension into the bowl. Several outlets in the wall of the bowl discharge the heavy fraction from the bowl. The light fraction travels through the length of the bowl by the helical scroll and is discharged from outlets located downstream from those that discharge the heavy fraction. The delivery region is also nearer to the outlets for the heavy fraction than to the outlets for the light fraction.

Abstract: A process for improving the rheological properties of an aqueous suspension of a particulate inorganic material which comprises the steps of: (a) forming an aqueous suspension of the particulate inorganic material and an effective amount of an anionic polyelectrolyte dispersing agent; (b) diluting the suspension formed in step (a) with water while maintaining the particulate in the dispersed state of step (a) to give a solids concentration of not less than 20% by weight of the particulate inorganic material; and (c) reconcentrating the diluted suspension formed in step (b) to give a solids concentration of at least 50% by weight of the particulate inorganic material.

Abstract: A thermoplastic granule containing a high proportion of a particulate carbonate filler in a thermoplastic binder, for blending with an end product thermoplastic in which the carbonate filler is to be dispersed. The granule comprises at least 85% by weight of a particulate carbonate which is coated with one or more fatty acids having a carbon chain length of from 12 to 20 carbon atoms. The balance of the granule by weight comprises a thermoplastic polymeric binder which is solid at ambient temperature and is compatible with the end product thermoplastic in which the carbonate filler is to be dispersed. The polymeric binder is an amorphous polyolefins and/or a highly branched polyethylene wax. The PSD of the carbonate is selected to maximize packing.

Abstract: An improvement is disclosed applicable to the method for producing a calcined kaolin by the steps of wet beneficiating a crude kaolin to form a slurry of the beneficiated kaolin; dewatering the slurry to form a substantially dry calciner feed; and calcining the feed at a temperature of at least 1450.degree. F. by passing a stream of hot gases through a calciner in which the kaolin feed is resident, whereby an exhaust stream of hot gases is generated which entrains quantities of partially calcined and hydrous kaolin pigment fines. The improvement, enabling useful application of the kaolin pigment fines, comprises recovering the kaolin pigment fines from the exhaust stream for use in papermaking. The fines can be recovered at a wet scrubber, and after being partially dewatered, shipped directly as a product slurry to the paper maker.

Abstract: An improved form of calcium carbonate which is acid tolerant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid tolerant calcium carbonate are provided. This acid tolerant calcium carbonate comprises a mixture of calcium carbonate with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of sodium aluminate together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of one or more weak acids.

Abstract: A method for beneficiating a low brightness fine particle size discolored kaolin crude to produce a high brightness coating clay. By combining the two beneficiating techniques of selective flocculation and ozonation, a synergistic phenomena occurs and a clay product of superior brightness and whiteness can be obtained from fine discolored clays that cannot be achieved by beneficiation with either process singularly. By passing the flocced clay through ozonation, the flocculant polymer left in the clay can be completely destroyed.

Abstract: A process for recovering inorganic material from an effluent suspension produced in the treatment of waste paper. The effluent suspension, in the form of an aqueous suspension containing at least 2% by weight of dry solids, is contacted with an oxygen-containing gas at an elevated temperature, and at an elevated pressure sufficient to keep the water component of the sludge in the liquid phase, for a time sufficient to effect substantially complete oxidation of the organic material in the suspension. The resulting product is dewatered and then resuspended in water, whereafter there is separated from the suspension water containing fine carbon particles in suspension to leave the desired inorganic material.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate are provided. This acid resistant calcium carbonate comprises a mixture of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of sodium carbonate, together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of weak acids in admixture with the calcium carbonate.

Abstract: A pedal for a vehicle has an integrally formed clevis, a central portion, and an integrally formed relatively flat foot engaging section. A lightweight, one-piece, extruded aluminum tubing with a thin wall and a round cross section is bent at an acute angle to form a clevis at its upper end and is bent at about a right angle at its lower end to form a foot engaging portion. A hydroforming process forms the walls of the clevis end and the central portion into a rectangular cross section and forces the walls of the lower end together to form a relatively flat, smooth, upper foot engaging surface and an undersurface with longitudinal ribs. Hexagonally configured apertures in opposing walls of the clevis receive a bushing having the same hexagonal configuration. A cut-out section communicates with the aperture in the two opposing walls, and the bushing is secured in the apertures by forcing together the walls adjacent to those with the apertures to close the gap in the cut-out sections.