Gypsum CAS

Added coagulant (powderd gypsum, Ca, Mg-salts, hydrate, 0.02-U.04M)... 

CaSOi ZHjO (gypsum) = Ca + SO " + 2H2O follows first-order kinetics as expressed by the equation... 

Portland cement is fabricated by heating limestone with small quantities of materials carrying silica and alumina (such as clay) to about 1500°C in a rotary kiln this process is known as calcination. The resultant hard, sintered clinker is then ground together with a small amount of gypsum (ca. 3%) into a fine powder to produce so-called Ordinary Portland Cement (OPC), the most commonly used type of cement. 

Calcium sulfate hemihydrate []0034-76-1 j M 145.2. Sol in H2O (0.2 parts/100 at 18.75°). Completely dehydrated >650°. Dry below 300° to give a solid with estimated pore size ca 38% of vol. Anhydrous CaS04 has high affinity for H2O and will absorb 6.6% of its weight of H2O to form the hemihydrate (gypsum). It sets to a hard mass with H2O, hence should be kept in a tightly sealed container. 

Finally, sulfur occurs in many localities as the sulfates of electropositive elements (see Chapters 4 and 5) and to a lesser extent as sulfates of Al, Fe, Cu and Pb, etc. Gypsum (CaS04.2H20) and anhydrite (CaSO ) are particularly notable but are little used as a source of sulfur because of high capital and operating costs. Similarly, by far the largest untapped source of sulfur is in the oceans as the dissolved sulfates of Mg, Ca and K. It has been estimated that there are some 1.5 x 10 cubic km of water in the oceans of the world and that 1 cubic km of sea-water contains approximately 1 million tonnes of sulfur combined as sulfate. 

A great many phosphates are used in commercial fertilizers. Perhaps the most important of these is calcium dihydrogen phosphate, Ca(H2P04)2. In relatively pure form, this compound is known as triple superphosphate of lime. A 1 -2 mol mixture of Ca(H2PC>4)2 and gypsum, CaS04 2HzO, is commonly referred to as superphosphate of lime. ... 

Calcium (sixth most abundant element) is found in limestone, CaC03, and gypsum, CaS04-2H20. Bones are made up of calcium phosphate, Ca PO. ... 

A major consequence of the activities associated with the exploitation of mineral deposits (i.e., exploration, the development of mines and processing facilities, the extraction and concentration, which is also called beneficiation, of ores containing the desired minerals, and the decommissioning or abandonment of mine facilities) is the production of extremely large volumes of unwanted materials. Waste volumes vary from ca. 30% of the mass of the ore in the case of gypsum and other non-metals, to about 50% for base metals to more than 80% for strip-mined... 

Of the principal minerals of Ca listed in Table 1, the most important ores are the various deposits of CaCOj, especially limestones, which occur as immense sedimentary beds over extensive parts of the earth s surface. Extraction of Ca from CaCOj is a simple and relatively inexpensive process. Although the other Ca-bearing minerals are rarely considered as potential Ca sources, they are widely distributed and extensively mined fluorite and apatite for their fluoride and phosphate content, gypsum and anhydrite for their use in construction. 

Gypsum is a relatively soft rock made of calcium sulfate. Rainwater percolates through g q)sum, dissolves some of the rock, and eventually becomes saturated with Ca ions and SOq ions. A geochemist takes a sample of groundwater from a cave and finds that it contains 8.4 X 10 M SO4 and 5.8 X 10 M Ca. (The ratio is not 1 1 because other sulfate rock contributes some of the SOq ions to the solution.) Use these data to determine the solubility product of calcium sulfate. 

Dispersed Inhibited Saline fluids Na" ", Ca + (seawater salt, saturated salt, gypsum, lime)... 

Silver white, relatively soft metal that is only applied in alloys. Oxygen and water attack pure Ca. The most prominent compound is the oxide (CaO) = burnt calcium, which hardens to calcium carbonate in mortar. Annual production of about 120 million tons. Burnt gypsum (CaS04 0.5 H20) hardens with water. A great step in evolution was the replacement of hard shells of brittle calcium carbonate by an internal skeleton of tough calcium phosphate (hydroxylapatite)-protein composite. Calcium is essential for all life forms. The daily requirement is 0.7-1.0 g. Humans (70 kg) contain 1 kg of calcium. Calcium silicate is the main component of cement. Marble is calcium carbonate in polycrystalline form and the favorite material of sculptors. 

Sulphate CaS04-2H20 Gypsum Coelenterate statocysts Gravity S store, Ca store... 

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