摘要:
Waste tyres (76) are disposed of in a cement-manufacturing or other mineral-burning process by introducing the tyres into the hot gas stream (82) at at least one point between the mineral-inlet end of a rotary kiln (2) and the lowermost cyclone (36) of an associated preheater system, e.g. into the gas stream (82) within a precalciner vessel (24) or riser duct (32), the tyres being maintained in contact with the hot gas for a sufficient period to effect at least partial combustion of the tyres. As an alternative, the tyres may be introduced into a Lepol grate preheater (84).
摘要:
Filler particles are coated with an adduct of an unsaturated polymer, e.g. polybutadiene, and phosphinic acid groups. The coated filler may be prepared by reacting an unsaturated organic polymer with a phosphorus trihalide and applying the product in the form of a solution or dispersion in an organic solvent to mineral, e.g. calcium carbonate, particles. If liquid, the product may alternatively be applied as such to the mineral particles. In either case, the product so applied is then hydrolysed in situ in order to form the phosphinic acid groups. The coated filler particles are useful in the reinforcement of elastomers.
摘要:
Particles having different properties (e.g. particulate fly ash and carbon) are separated by driving the particles by means of a vibratory feeder (12) forwards along a horizontal electrode plate (1) above which is mounted a second electrode (2) having at least one plate (4) mounted at an acute angle (a) to the horizontal. Preferably, two plates (4) each extend sideways from a central block (3) of dielectric material. An alternating electric field is generated between the electrodes (1, 2) by a high voltage AC power source (14). The potential across each plate (4) varies (in particular, decreases) in the lateral direction, the variation being continuous or stepwise. The field lines (16) from each plate (4) curve to the side and impart centrifugal forces to particles charged by friction or conductive induction, which forces separate lighter, more heavily charged particles from the others. The separated particles are collected in bins (13) arranged around the lower electrode (1).
摘要:
An aqueous slurry of mineral particles, for example calcium carbonate and/or calcium hydroxide, has a mineral solids concentration of at least 40% m/m and contains an agent that maintains the slurry at a pumpable viscosity but that acts as a flocculant upon dilution of the slurry. Suitable agents include cationic and amphoteric polyelectrolytes having nitrogen-containing groups, for example polyamines and dimethyl diallyl ammonium chloride polymers. The slurries may contain, other components, for example a synthetic hectorite or a dispersing agent such as a polyacrylate, polymethacrylate or polyphosphate. The slurries are useful in papermaking and in the treatment of sewage.
摘要:
An aqueous composition for conditioning an aqueous system, for example a sewage slurry, comprises an alkaline earth metal hydroxide, e.g. lime, and an anionic oligomeric polyelectrolyte, e.g. a salt of polyacrylic acid. Other components may include a weighting agent, e.g. calcium carbonate, a cationic flocculant, e.g. a polyacrylamide, and a base such as sodium hydroxide.
摘要:
Waste tyres (76) are disposed of in a cement-manufacturing or other mineral-burning process by introducing the tyres into the hot gas stream (82) at at least one point between the mineral-inlet end of a rotary kiln (2) and the lowermost cyclone (36) of an associated preheater system, e.g. into the gas stream (82) within a precalciner vessel (24) or riser duct (32), the tyres being maintained in contact with the hot gas for a sufficient period to effect at least partial combustion of the tyres. As an alternative, the tyres may be introduced into a Lepol grate preheater (84).
摘要:
A cementitious composition comprises a ground sulfoaluminous clinker, a ground Portland cement clinker (preferably rapid hardening Portland cement clinker), calcium sulfate, aggregate (especially sand and a coarse aggregate such as granite) and metal (e.g. stainless steel) fibres. The composition may also comprise a plasticiser and agents for controlling setting and hardening. The reinforced concrete produced from the compositions is useful in offshore applications, e.g. as a coating for the weld areas between lengths of steel pipe to be laid under water.
摘要:
A settable cementitious composition is prepared by mixing a ground mineral clinker that contains the phase 4CaO.3Al₂O₃.SO₃ with a source of SO₃ (eg. calcium sulfate), a source of CaO (eg. lime and/or ordinary Portland cement) and a fibrous material, in the presence of water. The fibrous material, which is preferably selected from synthetic organic fibres, wollastonite fibres and mixtures thereof, gives rise to improvements in the strength characteristics of the hardened masses formed by the setting of the compositions. The compositions find use in the production of monolithic packs to be used as supports in underground mining operations and also in the production of ceiling tiles and similar constructional articles.
摘要:
A cementitious composition comprises (a) an hydraulic cement comprising at least 65% by weight of hydraulic calcium silicate, e.g. tricalciuin silicate, and (b) a water-soluble or water-dispersible organic polymer. The hydraulic cement preferably comprises not more than 7% by weight of Al 2 O 3 , not more than 6% by weight of Fe 2 0 3 and not more than 4% by weight of S0 3 , and may be partially replaced by a mineral aggregate or extender. The polymer is present in an amount of up to 15% by weight of the cement and other mineral components and is preferably a partially hydrolysed poly(vinyl acetate). The compositions are rendered settable by the inclusion of water, the set products having excellent wet dimensional stability.
摘要翻译:水泥质组合物包含(a)包含至少65重量%的水硬性硅酸钙的水硬性水泥, 硅酸三钙,和(b)水溶性或水分散性有机聚合物。 水硬性水泥优选包含不超过7重量%的Al 2 O 3,不超过6重量%的Fe 2 O 3和不超过4重量%的SO 3,并且可以部分地由矿物骨料或增量剂代替。 聚合物的存在量高达水泥和其他矿物组分的15重量%,优选部分水解的聚(乙酸乙烯酯)。 通过包含水使组合物变得可凝固,凝固产品具有优异的湿尺寸稳定性。