Abstract: The addition of polymeric flocculant or other chemical dewatering modifier to a suspension flowing through a service line to a dewatering plant is controlled automatically in response to automatic determination of a filtration rate parameter. This may be determined using novel apparatus which includes a filtration assembly comprising a chamber with a filter element mounted across its open end and water sprays for washing the filter element. In one embodiment it is preferred to assist back-washing with an air purge while in another embodiment there are means for disassembling the filtration assembly to permit cleaning.

Abstract: Dirt tracks and other surfaces formed of particulate material are stabilized, to suppress dust formation, by incorporating an aqueous solution of a water soluble, low molecular weight, anionic polymer.

Abstract: A slow release composition comprises particles of a cross linked polymeric matrix in which a water soluble reagent is dispersed, and the reagent is anionic, generally being a low molecular weight anionic water soluble polymer, and the matrix is a cationic, highly cross linked, polymer formed from a water soluble monomer or monomer blend.

Abstract: A homogenous blend is formed of different water soluble polymer types, for instance of particular addition and condensation polymers, by forming one of the polymers from its monomeric starting material by polymerisation in a solution of the other polyer. The resultant solution has a concentration of above 10% but is homogenous. It can be used as a bulk solution or can be dried to powder or can be present as a reverse phase dispersion.

Abstract: Measurement of the ionic value X of a solution of a polyelectrolyte after shearing, for instance by a rotating blade, and/or measurement of the ionic value Y of a solution of polyelectrolyte before shearing, and especially the difference between t he values X and Y, gives a useful indication of the degree of cross linking of the polyelectrolyte and so can be utilized to control the manufacture of the polyelectrolyte, for instance drying conditions, or the storage or use of the polyelectrolyte, for instance its suitability or dosage in a flocculation process.

Abstract: A cross linked high molecular weight polymer formed from a water soluble monomer or blend of monomers and which has IV and/or solubility and/or rheology properties indicating that it would be unsuitable for use as a flocculant can be used as a flocculant after shearing the polymeric material. The shearing may be applied to the polymeric material before addition to the suspension that is to be flocculated or can be applied to the suspensionthat is being flocculated. The shearing increases the intrinsic viscosity of the polymeric material and can improve its rheology and solubility. The polymeric material must be of high molecular weight.

Abstract: An exothermic gel polymerization process conducted in the presence of water is initiated at a low temperature, is held for most of the process at a higher temperature by including in the medium a particulate heat sink material, such as sodium sulphate decahydrate, that is substantially insoluble in the medium and which undergoes an endothermic phase change and is then allowed to rise to a higher temperature. Either as a result of the endothermic change, or as a result of a subsequent exothermic change, at the end of the process the heat sink material is again solid particulate material substantially insoluble in the medium and so the product is a dispersion of the material in a polymer gel. The polymer is water soluble.