Clay phosphates

The description that we have given of most of the anionic clays corresponds to PLS. The intercalates of other lamellar compounds (graphites, clays, phosphates, phosphonates, oxides, oxy-halides, and chalcogenides) have been intensively studied for their pillaring properties. The primary reason for this interest is the possibility of engineering the pore sizes and distribution during the pillaring process. 

Engineering as a science must balance sophisticated mathematical models with practical field experience. In this chapter, some specific cases of slurry pipelines will be examined for coal, iron sand, clay, phosphate, limestone, and other materials. The practical experience with these minerals in different forms, particles sizes, and volumetric concentrations is very useful for the design of new pipelines or the modification of existing systems. 

Plasticity, and hence granulation efficiency, varies considerably with the nature and proportion of feed materials. Pure salts, such as potassium chloride and ammonium sulfate, lend Httle or no plasticity and thus are difficult to granulate. Superphosphates provide good plasticity. The plasticity of ammonium phosphates depends chiefly on the impurity content of iron and aluminum. The higher the impurity the greater the plasticity. In some cases, binders such as clay are added to provide plasticity. 

Resorcinol Derivatives. Aminophenols (qv) are important intermediates for the syntheses of dyes or active molecules for agrochemistry and pharmacy. Syntheses have been described involving resorcinol reacting with amines (91). For these reactions, a number of catalysts have been used / -toluene sulfonic acid (92), zinc chloride (93), zeoHtes and clays (94), and oxides supported on siUca (95). In particular, catalysts performing the condensation of ammonia with resorcinol have been described gadolinium oxide on siUca (96), nickel, or zinc phosphates (97), and iron phosphate (98). 

Size reduction (qv) or comminution is the first and very important step in the processing of most minerals (2,6,10,20—24). It also involves large expenditures for heavy equipment, energy, operation, and maintenance. Size reduction is necessary because the value minerals are intimately associated with gangue and need to be Hberated, and/or because most minerals processing/separation methods require the ore mass to be of certain size and/or shape. Size reduction is also required in the case of quarry products to produce material of controlled particle size (see Size measurement of particles). In some instances, hberation of valuables or impurities from the ore matrix is achieved without any apparent size reduction. Scmbbers and attritors used in the industrial minerals plants, eg, phosphate, mtile, glass sands, or clay, ate examples. 

Some producers beneficiate the phosphate ore prior to agglomeration to increase the phosphate content and remove undesirable contaminants. One approach uses a water wash to remove fines which are lower in assay and higher in contamination. If too much clay is removed from the ore by the beneficiation, a binder such as bentonite clay must be added back to the ore to faciUtate agglomeration. 

Aluminum [7429-90-5] Al, atomic number 13, atomic weight 26.981, is, at 8.8 wt %, the third most abundant element in the earth s cmst. It is usually found in siUcate minerals such as feldspar [68476-25-5] clays, and mica [12001 -26-2]. Aluminum also occurs in hydroxide, oxide—hydroxide, fluoride, sulfate, or phosphate compounds in a large variety of minerals and ores. 

Method 1 siHca—alumina, siHca, alumina, titania, tungstic oxides, phosphates, 2eoHtes, and clays. 

High Alumina Refractories. The desired alumina content, from 100% to just above 45%, is obtained by adding bauxites, synthetic aluminosihcates, and synthetic aluminas to clay and other bonding agents. These refractories are used in kilns, ladles, and furnaces that operate at temperatures or under conditions for which fireclay refractories are not suited. Phosphate-bonded alumina bricks have exceptionally high strength at low to intermediate temperatures and are employed in aluminum furnaces. High alumina and mullite are used in furnace roofs and petrochemical apphcations. 

B. J. Schemer and A. G. SmeUey, Dewatering of Thickened Phosphate Clay Wastefrom Disposal Ponds, Paper A81-6, The Metallurgical Society of AIME, Warrendale, Pa., 1981 J. R. Pederson, ed., U.S. Bureau of Mines Research 81, U.S. Government Printing Office, Washington, D.C., 1981, p. 83. 

Polyphosphoric acid supported on diatomaceous earth (p. 342) is a petrochemicals catalyst for the polymerization, alkylation, dehydrogenation, and low-temperature isomerization of hydrocarbons. Phosphoric acid is also used in the production of activated carbon (p. 274). In addition to its massive use in the fertilizer industry (p. 524) free phosphoric acid can be used as a stabilizer for clay soils small additions of H3PO4 under moist conditions gradually leach out A1 and Fe from the clay and these form polymeric phosphates which bind the clay particles together. An allied though more refined use is in the setting of dental cements. 

Dispersed Non-inhibited 1. Fresh water clay based fluids. Sodium chloride less than 1%, calcium ions less than 120 ppm a. Phosphate low pH (pH to 8.5) b. Tannin—high pH (pH 8.5-11+) c. Lignite d. Chrome lignosulphonate (pH 8.5-10)... 

Ceramics and minerals present many common problems, but ceramics warrant special treatment because elements of low atomic number predominate in them and they consequently offer x-ray emission spectrog-raphy of the light elements an excellent opportunity to prove its usefulness. Scott,8 in making this clear, emphasized the absorption and enhancement effects to be expected, and pointed out the need for careful sample preparation. By use of a General Electric XRD-5 spectrograph and associated equipment, he set up working curves for alumina, silica, potash, lime, phosphate, titania, and iron oxide in clays, refractories, and other ceramic materials. 

Flocculation or clarification processes are solids-liquid separation techniques used to remove suspended solids and colloidal particles such as clays and organic debris from water, leaving it clear and bright. Certain chemicals used (such as alums) also exhibit partial dealkaliz-ing properties, which can be important given that the principal alkaline impurity removed is calcium bicarbonate—the major contributory cause of boiler and heat exchanger scales (present in scales as carbonate), although closely followed by phosphate. 

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