Abstract: A precipitated alkaline earth metal carbonate is produced by calcining raw alkaline earth metal carbonate, for example a calcium carbonate, under conditions such that substantially all the chemically combined carbon dioxide is driven off to form an oxide, slaking the oxide in water to form a suspension of the corresponding alkaline earth metal hydroxide, allowing the suspension to cool to 45.degree. C. or below, and then carbonating the hydroxide in suspension in water with substantially pure carbon dioxide in the presence of a dithionite bleaching reagent to form a precipitate of an alkaline earth metal carbonate of increased brightness and purity. The precipitate may then be separated from the aqueous medium by, for example, filtration.

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 granule comprises an inner core, which is formed from a material which does not expand appreciably in the presence of organic compounds, and an outer shell formed from an organo-clay which is preferably held on the inner core with the aid of a binder.The granule can be prepared by tumbling a particle of the inner core material in admixture with a powdered organo-clay and a binder therefor. A particulate bed of the granules can be used for separating organic compounds from a mixture thereof with an aqueous medium.

Abstract: A method of monitoring the deflocculation of particles in a suspension, which particles, when deflocculated, are such that they can become aligned in an applied field, by applying a beam of radiation to a region of the suspension, applying a field to the region and detecting a change, if any, in forward radiation scattering properties of the region due to the aligning of deflocculated particles, if any, of the suspension in the field.

Abstract: An organo-clay is prepared by mixing a quaternary ammonium compound with an aqueous suspension of a smectite clay; thereafter subjecting the smectite clay/quaternary ammonium compound/water mixture to high shear mixing for a time sufficient to dissipate in the mixture at least 100 KJ of energy per kg. of dry solids in the mixture; and then dewatering the product thus obtained.

Abstract: The outer tubular assembly (4) of the tube pressure filter comprises a cylindrical member (36) and, at each end, an end assembly comprising two annular members (38 and 40) which are releasably secured to the cylindrical member (36) by a split retaining ring (42). The two annular members define a cavity (62) for receiving the lip of a diaphragm (18, FIG. 1). The axially inner annular member (38) defines, with the cylindrical member (36) an annular chamber (56) for receiving fluid under pressure and an annular slot (58) for allowing the fluid to flow between the chamber (56) and the interior of the pressure filter. The split retaining ring (42) engages a groove (52) in the cylindrical member (36), so securing the end assembly to the cylindrical member (36) without the need for welding.

Abstract: The inner assembly (2) of a tube pressure filter comprises a core (6) provided with a facing (36) made up of a plurality of laths. At the end of the core (6) there is an annular member (42, 44) which is retained in position between the facing (36) and a split retaining ring (60, 62). The retaining ring (60, 62) fits in a groove (58) in the core and is locked in position by locking elements (64) which fit into aligned recesses in the retaining ring (60, 62) and the annular member (42, 44) and are secured by screws (68).

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 tube pressure filter comprises (a) a pair of generally coaxial inner and outer tubular assemblies, which define between them a chamber of annular cross-section, (b) an impermeable elastic sleeve which divides said chamber into non-intercommunicating inner and outer compartments, (c) a filter element, (d) a slurry inlet extending annularly around one of the tubular assemblies for feeding a slurry to said inner compartment, (e) a hydraulic fluid inlet/outlet for feeding hydraulic fluid to and withdrawing hydraulic fluid from the outer compartment, (f) filtrate discharge means for the discharge of filtrate which has passed through the filter element and through apertures in the inner tubular assembly into the chamber, and (g) means for effecting relative movement of said tubular assemblies from one to another of three operating positions of said tubular assemblies.

Abstract: There is described a process for separating from a mixture of mineral components at least one of the components. The process comprises the steps of (a) dispersing the mixture of mineral components in water so as to form an aqueous suspension containing said mixture of mineral components, (b) mixing together said aqueous suspension and a non-polar organic liquid in which there has been dissolved or suspended an anionic collector for at least one of the components of the mixture of mineral components, the volume ratio of said aqueous suspension to non-polar organic liquid being controlled and the conditions under which said aqueous suspension and non-polar organic liquid are mixed together being such that only a small amount of energy is dissipated therein in a short time in order to effect the mixing together thereof and one liquid is uniformly dispersed in the other but a stable emulsion is not formed and (c) thereafter separating, or allowing to separate, the two liquid phases.

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 separating chamber for a magnetic separator is disclosed, which separating chamber includes a canister having at least one inlet and at least one outlet and a fluid-permeable magnetisable packing material within the canister. When feed material from which magnetisable particles are to be separated is supplied to the inlet(s), it passes into the packing material by way of a fluid-permeable partition which serves to distribute the feed material over a large area within the packing material. By virtue of an externally applied magnetic field, magnetisable particles within the feed material are magnetically attracted to collecting sites within the packing material. So as to mitigate the effect of fluid passing through apertures in the partition which tends to produce high velocity jets, thereby prejudicing the separation efficiency, the partition is double-walled, the two walls being spaced slightly apart and being apertured.

Abstract: A system for pumping an abrasive or corrosive fluid at high pressure and with a variable delivery rate. The system comprises raising the pressure in a non-corrosive and non-abrasive liquid in a pressure raising means comprising pump means and at least two intermediate cylinders containing floating pistons. The pressure is transferred to the abrasive or corrosive fluid in pressure transfer vessels. A valve arrangement controls the flow of non-abrasive and non-corrosive liquid to the intermediate cylinders and return means are provided for returning the floating pistons after each stroke. The valve arrangement is controlled in dependence on the positions of the floating pistons in their intermediate cylinders.The system is particularly useful for supplying clay slurry to a high pressure plate filter press.

Abstract: A bag suitable for containing material in bulk comprises a side wall, a bottom panel and a cover, all of woven material. The upper part of the side wall is provided with at least three lifting loops attached to the side wall at locations where the material of the side wall is folded to provide at least two overlapping layers. Each lifting loop comprises an opening and two legs. The two legs are secured together contiguously to form a double thickness which is secured to the overlapping layers, and at least one leg of each of at least two of the lifting loops extends substantially to the bottom of the side wall.

Abstract: A tube pressure filter is provided with a filter element comprising a filter cloth sleeve which is tailored from a woven material so that the warp and/or weft filaments extend helically around the inner tubular body on which the filter element is supported whereby the filter cloth sleeve can be stretched transversely of the length thereof.

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 order to determine the proportion of particles of less than a predetermined size in a fluid suspension, the fluid suspension is placed in a vessel (1) and is thoroughly mixed therein by mixing means (36,37). A sample of suspension is then withdrawn from a predetermined level within the vessel (1) by means of a sampling tube (9) and is transferred by way of a flexible tube (22) to a container (15). The particle concentration of this sample is then monitored by passing x-rays from a source (17) through the container (15) and detecting the emerging x-rays with a detector (18). The sample is then drained from the container (15). After allowing the suspension in the vessel (1) to settle for a time sufficient to enable particles of said predetermined size to sink from the surface of the suspension to said predetermined level within the vessel (1) according to Stokes' law, a further sample of suspension is withdrawn from said predetermined level and transferred to the container (15).

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.