Calcium sulfate Davies

Calcium sulfate may be decomposed to cement clinker and sulfur dioxide gas in a coke-fired rotary kiln at 900-1400°C (Miiller-Kiihne).28 However, the unfavorable economics of this process relegate it to countries that do not have other sources of sulfur. Phospho-gypsum (gypsum produced by the acidulation of phosphate rock) may be decomposed in this way as a means of recycling the sulfur values in the large waste phosphogypsum piles at fertilizer plants (OSW-Krupp and FIPR/Davy... 

J.L. Ricci, H.Alexander, P. Nadkarni, M. Hawkins, J. Turner, S. Rosenblum, L. Brezenoff, D. Deleonardis, G. Pecora, Biological mechanisms of calcium sulfate replacement by bone, in J.E. Davies (Ed.), Bone Engineering, Em Squared Inc., Toronto, Ontario, Canada, 2000. 

The program calculates total dissolved solids (TDS), conductivity, and the Langelier and Stiff-Davis Saturation Indexes (see Chapter 3.9). The screen allows the designer to use sodium, calcium, magnesium, chloride, sulfate, or bicarbonate to balance the water analysis. Water quality for up to five feed streams can be entered and blended together to make the total, combined feed water to the system. 

There are four stable isotopes of strontium that are found naturally. In addition there are about twenty radioactive isotopes, including strontium-90, a deadly by-product of nuclear-bomb detonations. The natural forms of strontium are relatively nontoxic. Similar to calcium both physically and chemically, elemental strontium is a soft, shiny metal. Like calcium and other alkaline earth metals, it is easily oxidized and thus not found naturally in its free elemental state. Instead, it almost always is found in the + 2 oxidation state, forming such compounds as strontium oxide (SrO), strontium sulfate (SrS04, from the mineral celestite), strontium carbonate (SrCOj, from the mineral strontianite), and strontium chloride (SrC. Strontium nitrate, Sr(N03)2, is used to produce the brilliant red color seen in some fireworks and signal flares and is also used in making tracer bullets that can be seen when fired at night. Other strontium compounds are sometimes used in the manufacture of special glasses. Yet overall, strontium is not a very important element industrially or commercially, see ALSO Davy, Humphry... 

Although calcium (Ca) metal was discovered in 1808 independently by Sir Humphry Davy and Berzelius and Pontin, the pure metal was first produced by Moissan in 1898. The name of calcium is derived from the Latin calx , meaning lime. Calcium constitutes 3.63% of the Earth s crust, and is the fifth most abundant element in the environment as well as in the human body. Due to its reactivity, it only occurs naturally in the form of its compounds for example, various magmatic rocks, carbonate (limestone), and sulfate. Calcium is indispensable for life, namely for the maintenance of structure and metabolism. Its structural roles include that of coral, the secreted shells of mollusks and, in particular, the internal skeleton of vertebrates (Hluchan and Pomerantz 2002). 

Calos, N. J., C. FI. L. Kennard, A. K. Whittaker and R. L. Davis (1995). Structure of Calcium Aluminate Sulfate Ca4AlgOjgS . Journal of Solid State Chemistry 119 1-7. 

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