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Showing 1 to 14 of 14 for “"Calcium sulphate"”.
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Time as a factor in the dissociation of calcium sulphate
Calcium sulphate was found to have a dissociation temperature some 60°-90°C. lower than the values reported by other workers.
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Crystallization of calcium sulphate during phosphoric acid production : improving filtration through improvement in particle shape and size distribution
… process produces a side product of calcium sulfate hydrates, which become the filter media in the subsequent acid separation process. For most industrial processes, the dihydrate form of calcium sulfate crystals (gypsum) precipitates and its shape and size distribution are key …
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Evaluating the Potential of Scaling due to Calcium Compounds in Hydrometallurgical Processes
… theoretical and experimental study on calcium sulphate scale formation in hydrometallurgical solutions containing various minerals was conducted. A new database for the Mixed Solvent Electrolyte (MSE) model of the OLI Systems® software was developed through fitting of existing …
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Gypsum seeding to prevent scale formation and improve separation efficiency
… of different inorganic solutes. The treatment of calcium sulphate-rich brines using EFC often results in gypsum crystallization before any other species. This results in gypsum scaling on the cooled surfaces of the crystallizer, which is undesirable as it retards heat transfer rates and hence …
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Control of the desupersaturation reactor used in the SPARRO process
… process. The process was designed to treat calcium sulphate (gypsum) scaling mine waters by encouraging preferentlal crystal growth onto introduced seeds, rather than on the reverse osmosis membranes. The major problem faced by the SPARRO process was the short membrane life span, possibly …
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Factors influencing the strength development in pfa-lime systems
… on the pfa particle surfaces as anhydrous calcium sulphate, and it was found possible to remove this surface layer by acid treatment. The presence of this gypsum has been shown to be a critical factor in controlling the reaction rate, influencing the reaction mechanism and hence affecting …
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Development and characterisation of a Portland cement-based dental root filling material
… canals. This study investigated the effect of calcium sulphate additions for improving the undesirably-long setting time of MTA-like dental materials, whilst maintaining the mechanical, biological and sealing properties. 10wt%PoP accelerated initial setting times of grey and white model cements …
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Composition and microstructure of concrete mixtures subjected to biogenic acid corrosion and their role in corrosion prediction of concrete outfall sewers
… entails simultaneous destruction of the calcium hydroxide (CH) in the hydrated cement paste (HCP) and substituting a larger molecule of calcium sulphate into the concrete matrix thus causing pressure and spalling of the adjacent concrete and aggregate particles. In addition, the calcium …
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Yield, chemical composition, digestibility and palatibility of orchardgrass (Dactylis glomerata L.) fertilized with different levels of nitrogen and sulphur
… ammonium nitrate and S (0, 34, and 67 kg/ha) as calcium sulphate on yield, chemical composition, digestibility and palatability of orchardgrass (Dactylis glomerata L.) , were studied in a field experiment. Treatments were applied in a randomized block design with a 3x3 factorial arrangement of …
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APPLICATION OF TAGUCHI'S ORTHOGONAL ARRAY IN AN EXPERIMENT FOR FORMULATION OF CEMENTITIOUS REPAIR MATERIAL
… constituents. They are as follows: HAC, OPC, calcium sulphate, calcium carbonate, silica sand, resin, superplasticizer, low cellulose, defoamer, retarder and accelerator. This self-leveling mortar is characterized by the following properties: compressive strength, flow value, tensile bond …
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Fracture of the distal radius - outcome, primary surgery and treatment of malunion
… was used with a faster resorbing mixture of calcium phosphate and calcium sulphate. 15 consecutive patients with a radiographic and clinically manifesting malunion after a DRF underwent an osteotomy. The same technique was used for fixation of the osteotomy as in Paper III but this time with …
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The study of pretreatment options for composite fouling of reverse osmosis membranes used in water treatment and production
… in RO processes operating on brackish water are calcium carbonate, calcium sulphate and silica. However, silica fouling is the recovery limiting factor in RO system. Silica chemistry is complex and its degree of fouling strongly depends on the silica solubility and its polymerization under …
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Acid resistance of sewer pipe concrete
… commonly encountered in South African sewers. Calcium sulphate, which precipitates in a sulphuric acid solution and masks further attack, is eliminated simulating the constant dissolution of the precipitate at the average daily sewage level region and loosely attached precipitate in the …
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Sedimentation on the continental margin off the Orange River and the Namib Desert
… released by anaerobic reduction of sea-water sulphate. The dissolution of planktonic foraminiferal tests provides calcium ions which combine with sulphate to form gypsum, once the calcium/sulphate solubility product is exceeded. On the Walvis shelf off LUderitz residual glauconite was reworked …