Alumina, lime and

It is, therefore, only necessary to make on analysis of each of the crude materials that are to Jbo mixed together, to ascertain the quantity of silica, alumina, lime, and potassa each contains, in order to obtain the data for calculating how much of each by weight, and consequently by measure in their semifluid state, will be roqulred to obtein the proper mean quantity as nearly as possible in the mass. 

English red consists essentially of anhydrous ferric oxide in very fine powder, more or less deep red in colour. It usually contains small quantities of silica and silicates, alumina, lime and magnesia, and often sulphates, chlorides and free sulphuric acid it may also contain manganese and copper. It is often sold mixed with considerable proportions of gypsum (Venetian red), barium sulphate and chalk sometimes its colour is heightened or modified by addition of artificial organic colours. 

The pigment is treated with hydrochloric acid effervescence indicates copper or calcium carbonate any insoluble residue may contain barium sulphate, gypsum (in large quantity), lead sulphate or clay, which may be identified by the usual methods. The solution is treated with excess of ammonium carbonate if a precipitate forms, it is tested especially for alumina, lime and magnesia. 

In the Kraft recovery process the green liquor, which is an aqueous solution of sodium carbonate, is heated with lime to produce white liquor or caustic soda, which is then returned to the pulp digestion operations. In the production of alumina, lime and soda are fed to bauxite digesters. The CaCO 3 produced during the course of the reaction is rebumed to lime and is recycled. The main difficulties associated with these processes include the extensive mechanical handling through the use of causticizers, settlers, and repulpers in order to produce caustic that is low in carbonate and the high fuel consumption needed to reconvert CaCO to lime. 

This alkali can only be obtained from either of the above minerals, which are silicates. One part of the mineral in fine powder is mixed with two of fluor-spar, and the mixture heated with sulphuric acid, until the whole of the silica is dissipated. There then remains a mixture of sulphates of alumina, lime, and lithia, and, in the case of lepidolite or spodumene, potash. By boiling with carbonate of ammonia in excess, the alumina and lime are precipitated, and the filtered liquid is evaporated to dryness, and ignited to expel the sulphate of ammonia. The residue is sulphate of lithra, or sulphates of lithia and potash. In the latter case, by the cautious addition of chloride of barium, the sulphuric acid is separated as sulphate of baryta, and the lithia and potash converted into chlorides. These being dried, are digested in absolute alcohol, which dissolves the chloride of lithium. The lithia is now free from other bases to obtain it in the separate state, the chloride is converted into sulphate, by being boiled with oil of vitriol, and the solution of the sulphate decomposed by the exact equivalent of barytic water, by which the sulphuric acid is precipitated, while the free lithia is dissolved, and the solution, if evaporated, leaves hydrate of lithia, LO, HO. 

Disposal. Fluorine can be disposed of by conversion to gaseous perfluorocarbons or fluoride salts. Because of the long atmospheric lifetimes of gaseous perfluorocarbons (see Atmospheric models), disposal by conversion to fluoride salts is preferred. The following methods are recommended scmbbing with caustic solutions (115,116) reaction with soHd disposal agents such as alumina, limestone, lime, and soda lime (117,118) and reaction with superheated steam (119). Scmbbing with caustic solution and, for dilute streams, reaction with limestone, are practiced on an industrial scale. 

Silica and Alumina. The manufacture of Pordand cement is predicated on the reaction of lime with siUca and alumina to form tricalcium sihcate [12168-85-3] and aluminate. However, under certain ambient conditions of compaction with sustained optimum moisture content, lime reacts very slowly to form complex mono- and dicalcium siUcates, ie, cementitious compounds (9,10). If such a moist, compact mixture of lime and siUca is subjected to steam and pressure in an autoclave, the lime—silica reaction is greatiy accelerated, and when sand and aggregate is added, materials of concrete-like hardness are produced. Limestone does not react with siUca and alumina under any circumstances, unless it is first calcined to lime, as in the case of hydrauhc lime or cement manufacture. 

Fine powder containing compounds of lime, alumina, silica and iron oxide. Used as a construction material. 

Silica bricks are manufactured from crushed ganister rock containing about 97 to 98 percent silica. A bond consisting of 2 percent lime is used, and the bricks are fired in periodic kilns at temperatures of 1,500 to 1,540°C (2,700 to 2,800°F) for several days until a stable volume is obtained. They are especially valuable when good strength is required at high temperatures. Superduty silica bricks are finding some use in the steel industry. They have a lowered alumina content and often a lowered porosity. 

The preparation of ferrovanadium by this route is carried out batchwise in refractory-lined open reactors, with vanadium pentoxide, aluminum powder, iron scrap and lime or fluorspar constituting the charge. The reactions once initiated, proceed briskly to completion. The reaction heat is sufficient to melt the ferrovanadium and the alumina-lime/fluor-spar slag, which readily separate due to density difference. The aluminothermic ferroalloy product contains practically no carbon. 

Portland cement Major three-dimensional inorganic construction polymer containing calcium silicates, lime, and alumina. 

Nickel is removed from electroplating wastes by treatment with hydroxide, lime, and/or sulfide to precipitate the metal (HSDB 1996). Adsorption with activated carbon, activated alumina, and iron filings is also used for treating nickel-containing waste water. Ion exchange is also used for nickel removal and recovery. 

Subsequent reaction of the monosulfate with gypsum produces acicular crystals of ettringite. Monosulfate apparently does not contribute to expansion, whereas the formation of ettringite involves expansion. A recently issued patent [75] covers the use of prehydrated high-alumina cement (H-HAC), lime and gypsum mixtures. Particle type, size, thickness of protective coating, and presence of moisture determine the rate and extent of expansion [Fig. 6.11]. 

Vauquelin believed that Torbern Bergman s incorrect conclusions as to the chemical nature of the beryl had been caused by the unwillingness of his active mind to submit to the details of experiment. Thus Bergman, and Bindheim as well, had entrusted their analyses to young pupils who were incapable of distinguishing a new substance when they saw it. According to Bindheim s analysis, the beryl consisted of 64 per cent of silica, 27 per cent of alumina, 8 per cent of lime, and 2 per cent of iron (total 101 per cent) (23). 

Plate-Glass, composed of silica, soda, or potassa, lime, and a little alumina. This variety only differs from the preceding by the greater purity and freedom from color of the materials. 

The impurities most frequently met with in solution of and solid hydrate of potassa are carbonate of lime oxide of iron, silica, alumina, carbonate and sulphate of potassa, and chloride of potassium. > Carbonic acid is indicated by effervescence on the addition of an acid. Carbonate of lime and oxide of iron remain insoluble when the salt is treated with water. Silicic acid and... 

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