Abstract: A physical property of the solid component of a slurry, for example the percentage content of a selected element such as iron, is continuously measured. A sampling device (2) carrying a filter element is immersed in the slurry at a sampling station (A). Vacuum is applied to the sampling device (2) to cause the liquid content of the slurry to pass through the filter element, leaving the solid component deposited on the filter element as a filter cake. The sampling element is transferred to a heating station (B), where the filter cake is dried, and then to a measuring station (C), where the desired physical property is measured. The sampling device is then transferred to a washing station (D), where the filter cake is washed from the filter element so that the procedure can start again. The process is automatically controlled by a microprocessor, enabling continuous sampling of the slurry to be carried out.

Abstract: A filled elastomer composition comprises a natural or synthetic rubber and, as a filler, a substantially dehydroxylated clay which contains at least 60% by weight of particles smaller than 2 microns equivalent spherical diameter, has a specific gravity not greater than 2.4 and a spherical surface area of at least 10 m.sup.2 g.sup.-1 and which has been treated with a substituted silane. The substantially dehydroxylated clay can be obtained by "shock" calcining a kaolinitic clay.

Abstract: A method of comminuting a mineral involves introducing into a grinding chamber which has an internal, rotatable impeller driven by an electric motor, water, a dispersing agent and pieces of said mineral not larger than 20 mm to form a slurry. The slurry is agitated in the grinding chamber and a slurry of comminuted minerals is continuously withdrawn from the grinding chamber. The rates of introducing the water, the dispersing agent and the pieces of mineral into the grinding chamber and the rate of withdrawing the slurry of comminuted mineral from the grinding chamber are such that the slurry of comminuted mineral withdrawn from the grinding chamber contains at least 50% by weight of solids. The volume of material in the grinding chamber is maintained substantially constant, and the power consumed by the electric motor driving the impeller is maintained between upper and lower limits.

Abstract: A process for concentrating mica in a mixture of sand and mica is disclosed, which comprises introducing the feed mixture of sand and mica into an upper part of a density separating vessel in which is provided a rising current of an aqueous medium, the velocity of the current being uniform or substantially uniform over a horizontal cross-section of the vessel and being such that all but the least buoyant particles of the mixture are held in suspension as a bed which is gently displaced upwards in the vessel by incoming feed mixture; and passing a slurry which overflows from the vessel over a screen having an aperture size in the range from 210 .mu.m to 500 .mu.m (No. 72 mesh to No. 30 mesh B.S sieve), there being retained on the screen a mixture of sand and mica having a higher percentage content of mica, as calculated in the dry state, than the feed mixture.

Abstract: In a tube pressure filter which includes a pair of generally coaxial inner and outer tubular bodies arranged one within the other and adapted to be supported in a generally upright position, the inner tubular body having a cylindrical central section, and upper and lower end sections, each of which end sections includes a portion of greater diameter than the cylindrical central section and a fairing mounted on or adjacent to said portion so as to extend around an end of the cylindrical central section; and a filter element disposed around and supported by the inner tubular body, the filter element comprising a filter cloth sleeve, the improvement which comprises constructing the fairings and the ends of the filter cloth sleeve so that each end of the filter cloth sleeve is or can be secured to the outwardly facing surface of one of said fairings.

Abstract: In the method described fluid containing magnetizable particles is introduced into a separating chamber containing a fluid-permeable mass of magnetizable material and held therein for a finite length of time. During this time the magnetizable material is moved into a magnetic field where the fluid is drained from the magnetizable material leaving magnetizable particles entrained in this material. This draining may be achieved either by providing relative movement between the separating chamber and the magnetizable material or by discharging the fluid from the separating chamber. The magnetic separator described comprises a plurality of interconnected separating chambers, and associated masses of magnetizable material, which are moved continuously through a separating zone in which a magnetic field is established by a magnet. In this zone each mass of magnetizable material is drained and, outside this zone, the magnetizable particles entrained in the magnetizable material are removed by flushing.

Abstract: Paper or cardboard products are manufactured by mixing an aqueous solution or dispersion of a cationic starch with an aqueous suspension of a kaolinitic clay filler, and adding the resulting mixture to a stock of cellulosic fibres to form a furnish containing the kaolinitic clay filler, the cationic starch and the cellulosic fibres, which furnish is then formed into the desired paper or cardboard products, the amount of shear to which the mixture containing the clay filler and cationic starch is subjected being controlled to ensure that the furnish contains flocs of clay filler and cationic starch of a desired size.

Abstract: A rotary magnetic separator is disclosed which includes a ferromagnetic rotor provided with a plurality of arcuate separating chambers supported at its periphery. Each separating chamber comprises an inlet for feed suspension in its bottom coupled to a pump by way of a flexible pipe, and an outlet for feed suspension in its top, there being a fluid permeable and magnetizable packing material between the inlet and outlet. Two electromagnet poles are magnetically coupled to the rotor which serves as a further pole. The rotor can be turned by a motor so as to move certain separating chambers into the vicinity of the electromagnet poles. Feed suspension can then be supplied to these separating chambers and magnetizable particles from the feed suspension may become entrained in the packing material. Subsequently the rotor can be turned back to its original position and these separating chambers can be flushed out with clean water.

Abstract: A process for treating a clay mineral of the kandite group comprising forming a fluid aqueous suspension of the clay mineral, the suspension having a solids content in the range of from 60% to 75% by weight and a pH in the range of from 7.0 to 11.0 and the suspension containing a dispersing agent to deflocculate the clay mineral; and treating the fluid suspension of clay containing the dispersing agent with a water-soluble reducing bleaching agent under alkaline pH conditions for a time sufficient to give the desired improvement in brightness of the clay. Preferably, the clay mineral suspension is subjected to a particle size separation process at said solids content to reduce the percentage of particles larger than 10.mu.m to not more than 3% by weight. Advantageously, the viscosity of the clay mineral suspension during the particle size separation process is below 2 poise.

Abstract: A method of comminuting a solid material comprising calcium carbonate to obtain a product containing at least 60% by weight of particles smaller than 2 microns equivalent spherical diameter comprises forming an aqueous suspension of the solid material which has a solids content in the range of from 5% to 50% by weight of dry solids and contains a dispersing agent, comminuting the solid material in the suspension by agitating the suspension in admixture with a particulate grinding medium, separating from the suspension thereby obtained an aqueous suspension containing comminuted solid material at least 60% by weight of which is smaller than 2 microns equivalent spherical diameter, flocculating the comminuted solid material by means of an electrolyte having a multivalent cation, and dewatering the aqueous suspension containing the comminuted and flocculated solid material.

Abstract: A tube pressure filter comprising inner and outer compartments separated by an impermeable elastic sleeve includes an inlet to the inner compartment which is located in an upper end section of the tube pressure filter and includes a feed distribution system which comprises a substantially annular aperture extending around said upper end section debouching into the inner compartment of said tube pressure filter, said substantially annular aperture being (a) constructed and disposed so that, in use, feed material debouching therefrom has a downward component of velocity and (b) in communication with an antechamber formed in said upper end section into which antechamber a mixture to be pressure filtered can be introduced under pressure through a feed conduit.

Abstract: An apparatus and a method are described for separating magnetizable particles from a fluid in which they are suspended. The apparatus comprises a separating chamber having an inlet and an outlet for permitting fluid to enter and leave the separating chamber, a matrix of a plurality of ferromagnetic filaments arranged substantially parallel to one another and to the general direction of flow of fluid through the matrix and disposed in the separating chamber, magnet means for establishing a high intensity magnetic field in the separating chamber perpendicular to the general direction of flow of the fluid through the matrix, and removal means for removing magnetizable particles attracted to the matrix within the separating chamber.

Abstract: A method of reducing the liquid content of a mixture of a liquid and a particulate solid by subjecting said mixture to pressure filtration in a tube pressure filter in which, after the formation of the filter cake on the filter element of the tube pressure filter, a gas is forced through the filter cake at a pressure which is at least one third of the maximum pressure employed to form the filter cake on the filter element.

Abstract: The apparatus comprises a magnet for establishing a magnetic field in a first zone, and a separating chamber. The separating chamber is provided with an inlet and an outlet for fluid and contains a fluid-permeable packing of magnetizable material between the inlet and the outlet. One or more parts of the separating chamber consist of magnetic field concentrating means constituted by ferromagnetic material. This part (or each of these parts) would otherwise occupy a region of relatively low magnetic field intensity when the separating chamber is within the first zone and a magnetic field was established in the first zone by means of the magnet. The remainder of the separating chamber consists of substantially non-magnetizable material. Means are provided for moving the separating chamber into, and out of, the first zone and for passing fluid containing magnetizable particles through the separating chamber when within that zone so that magnetizable particles are magnetized and captured in the packing.

Abstract: The invention provides a process for improving the rheological properties of an aqueous suspension of a clay mineral in which the aqueous suspension is mixed with a water-soluble organic compound having a plurality of basic groups and a number average molecular weight not greater than 1,000. The treated clay minerals may be used, for example, as the pigment in a paper coating composition.

Abstract: There is disclosed an apparatus suitable for shifting the plates of a plate filter press. The apparatus comprises supporting means for supporting the apparatus so that it can be moved longitudinally of the plate filter press, and a manually-operable, power-drivable device including first and second members capable of engaging plates of the plate filter press and movable relative to one another by a source of power along a line of action which, when the apparatus is in use is parallel to, or substantially parallel to, the plate filter press. The arrangement is such that, in use, the device can be rotated or swung in order to bring the first and second members into and out of engagement with plates of the plate filter press and, when in engagement with plates of the plate filter press, the device can be operated to cause movement of the first and second members relative to one another and hence movement of one or more plates of the plate filter press.

Abstract: The invention relates to a process for preparing paper or cardboard in which starch and a mineral filler are incorporated into cellulosic fibres. The process uses a blend, which is prepared under specified conditions, of raw starch and starch phosphate. The procedure for incorporating the starch blend and the mineral filler into the cellulosic fibres is also specified.

Abstract: A method of improving the properties of ball clay is disclosed which comprises forming a deflocculated aqueous suspension of the ball clay at a specified solids content; passing the suspension through one or more vibrated sieves, at least one of which has a nominal aperture in the range of from 50 to 100 microns; and thermally drying the material after it has been flocculated.

Abstract: In the method and apparatus described a high intensity magnetic field is established in a first zone. A quantity of fluid having magnetizable particles suspended therein is passed through a first separating chamber containing magnetizable packing material and disposed within the first zone, so that the magnetizable particles are magnetized by the magnetic field and attracted to the packing material. The first separating chamber is then moved out of the first zone and into a second zone and a second separating chamber containing magnetizable packing material is moved into the first zone.

Abstract: A continuous process for lining pipes with thermosettable polymer made from prepolymer and curing agent, comprising the steps of: heating and degassing the prepolymer and storing it in a first storage tank; providing the curing agent in liquid form at a curing temperature in a second storage tank; recycling the prepolymer and the curing agent between the storage tanks and a mixing head which is selectively operable to mix and discharge the reagents; arranging each pipe with its longitudinal axis inclined at an angle to the horizontal; introducing a selected amount of the polymer mixture into the pipe at a predetermined rate so that the liquid material flows down along the pipe; and shifting the pipe to a horizontal position and spinning the pipe about its axis to distribute the material, spinning continuing until the material has set.