Magnesium aluminate silicate

Several different possible zeolite structures may result, and if the sodium content is too high, calcium and magnesium are excluded and a hard zeolite scale of sodium-aluminum silicate preferentially forms. If only calcium is present, calcium-aluminum silicate zeolite forms, also as a hard scale. If only magnesium is present in solution, it forms the flocculant magnesium aluminate, MgAl204. 

This is by far the most frequently encountered interference in AAS. Basically, a chemical interference can be defined as anything that prevents or suppresses the formation of ground state atoms in the flame. A common example is the interference produced by aluminium, silicon and phosphorus in the determination of magnesium, calcium, strontium, barium and many other metals. This is due to the formation of aluminates, silicates and phosphates which, in many instances, are refractory in the analytical flame being used. 

The range of materials used as refractories is very wide and includes such substances as the fireclays and kaolins, quartzites, bauxites, schist, magnesite, dolomite, graphite, carborundum, fused alumina, chromite, magnesium aluminate, magnesium silicate, zirconium oxide, zirconium silicate, boron nitride, and others. 

TAY/SCH] Taylor, R. W., Schmalzried, H., The free energy of formation of some titanates, silicates, and magnesium aluminate from measurements made with galvanic cells involving solid electrolytes, J. Phys. Chem., 68, (1964), 2444-2449. Cited on pages 243, 244, 315. 

A large number of electrolytic treatments of magnesium, anodic or a.c., have been developed, in which adherent white or grey films consisting of fluoride, oxide, hydroxide, aluminate or basic carbonate are deposited from alkaline solutions containing caustic alkali, alkali carbonates, phosphates, pyrophosphates, cyanides, aluminates, oxalates, silicates, borates, etc. Some films are thin, and some are relatively thick. All are more or less absorbent and act as good bases for paint, though none contributes appreciable inhibition. All can, however, absorb chromates with consequent improvement of protective efficiency. 

Aluminium borohydride Aluminium chloride Aluminium chlorate Ammonium tetrachloroaluminate Aluminium fluoride Aluminium trihydroxide Aluminium ammonium sulphate Aluminium potassium sulphate Aluminium nitride Aluminium nitrate Sodium aluminate Aluminium sodium aluminate Aluminium phosphate Aluminium phosphide Aluminium borate Aluminium oxychloride Aluminium fluorosilicate Aluminium magnesium silicate Aluminium sulphate... 

Dicalcium silicate Tricalcium silicate Tetracalcium aluminate Tetracalcium aluminoferrite Magnesium oxide... 

Calcium oxide is the main ingredient in conventional portland cements. Since limestone is the most abundant mineral in nature, it has been easy to produce portland cement at a low cost. The high solubility of calcium oxide makes it difficult to produce phosphate-based cements. However, calcium oxide can be converted to compounds such as silicates, aluminates, or even hydrophosphates, which then can be used in an acid-base reaction with phosphate, forming CBPCs. The cost of phosphates and conversion to the correct mineral forms add to the manufacturing cost, and hence calcium phosphate cements are more expensive than conventional cements. For this reason, their use has been largely limited to dental and other biomedical applications. Calcium phosphate cements have found application as structural materials, but only when wollastonite is used as an admixture in magnesium phosphate cements. Because calcium phosphates are also bone minerals, they are indispensable in biomaterial applications and hence form a class of useful CBPCs that cannot be substituted by any other. 

The hydrated lime then reacts with the reactive silica and alumina to produce hydrated calcium and magnesium silicates and aluminates. The cement also hydrates completely. 

Inorganic colorants listed in 21CFR 178.3297 include aluminum, aluminum hydrate, potassium silicate, aluminum silicate, barium sulfate, bentonite, calcium carbonate, calcium silicate, calcium sulfate, carbon black (channel process, prepared by the impingement process from stripped natural gas), chromium oxide green Cr203, cobalt aluminate (with restrictions), diatomaceous earth, iron oxides, kaolin (modified for use in olefin polymers in amounts up to 40%), magnesium oxides, magnesium silicate (talc), sienna, silica, titanium dioxide, titanium dioxide-barium sulfate, ultramarines, zinc carbonate (limited use), zinc chromate (less than 10%), zinc oxide (limited use), and zinc sulfide (less than 10%). 

Aluminum calcium silicate Ammonium polyphosphate Calcium aluminate Calcium hydroxide Calcium sulfite Candelilla synthetic Collodion Copal resin Elemi gum Epoxy resin Feldspar Gelatin Magnesium chloride Potassium carbonate Shellac Zirconium silicate cement additive... 

Many substances are known to act as accelerators for concrete. These include soluble inorganic chlorides, bromides, fluorides, carbonates, thiocyanates, nitrites, nitrates, thiosulfates, silicates, aliuninates, alkali hydroxides, and soluble organic compounds such as triethanolamine, calcium formate, calcium acetate, calcium propionate, and calcium butyrate. Some of them are used in combination with water reducers. Quick setting admixture s used in shotcrete applications and which promote setting in a few minutes may contain sodium silicate, sodium aluminate, aluminum chloride, sodium fluoride, strong alkalis, and calcium chloride. Others are solid admixtures such as calcium aluminate, seeds of finely divided Portland cement, silicate minerals, finely divided magnesium carbonate, and calcium carbonate. Of these, calcium chloride has been the most widely used because of its ready availability, low cost, predictable performance characteristics, and successful application over several decades.In some countries the use of calcium chloride is prohibited, in some others, such as Canada and the USA, the use of calcium chloride is permitted provided certain precautions are taken. Attempts have continued to find an effective alternative to calcium chloride because of some of the problems associated with its use. 

Zinc oxide increases tack and cohesive strength in these polymers (and also plays an important chemical role in the vulcanization of butyl). Aluminum hydrate, lithopone, whiting, and the coarser carbon blacks such as thermal blacks also increase tack with moderate increase in cohesivity. Clays, hydrated silicas, calcium silicates, silico-aluminates, and the fine furnace and thermal blacks increase cohesive strength and stiffness. Stiffness can also be increased by use of very fine silica pigment and magnesium oxide or carbonate. 

Carbonate, bicarbonate and silicate ions form moderately strong complexes with most metal ions. For instance, the association constants of alkaline earth cations for carbonate and bicarbonate are in the range of 10-1000 [107,108]. Similarly, silicate ions complex readily with many metal ions, e.g. with calcium (fci = 1230) and magnesium ki = 1.5 x 10 ) [108]. There seems to be no data on metal ion association with aluminate ions but it is likely that ion association is moderately strong here also. 

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