Magnesium calcium carbonate

Calcium/magnesium carbonate/hydroxide and calcium phosphate can be removed by using 5 to 15% hydrochloric acid at 140 to 150 °F, by recirculating tetrasodium EDTA at 200 to 300 °F, or by 7 to 10% sulfamic acid at 140 to 150 °F. The temperature may need to be a little higher to start the dissolution process. 

Marble. The word marble is used as the common name for two types of monomineral rocks one derived from limestone and therefore composed of calcium carbonate, the other derived from dolomite and composed of calcium magnesium carbonate. Extremely high pressures and heat during past geological times modified the structure of both limestone and dolomite, compacting them into a characteristic crystal structure. Most marble is white however, minor and trace amounts of metallic impurities cause the formation of stains in a variety of colors, hues, and patterns, or of colored marble. 

Calcium magnesium acetate, 1 127 Calcium magnesium carbonate, health and safety factors related to, 15 74 Calcium monosulfoaluminate, 5 477t Calcium montmorillonite, 6 686, 696 structure and composition, 6 668-669 Calcium nitrate, in nitrogen fertilizers,... 

K. J. D. MacKenzie and R. H. Meinhold, Thermal decomposition of dolomite (calcium magnesium carbonate) studied by Mg solid-state nuclear magnetic resonance. Ther-mochim. Acta, 1993, 230,331-337. 

Dolomite is an alternative mineral that is used in some regions in place of cal-cite for certain applications. Dolomite is a calcium magnesium carbonate (CaCOj.MgCOj) and occurs widely in nature. Although generally similar to cal-cite in properties, it is shghtly harder (3.5), denser (2.85) and more acid resistant. Production is similar to that for calcite,but miUing is more costly and it tends to only be available at the coarser end of the size spectrum. 

Hydromagnesite is a basic magnesium carbonate 4MgC03.Mg(0H)2.4H20, while huntite is a mixed calcium magnesium carbonate SMgCOj.CaCOj. Both materials generally exhibit a platy crystal habit. 

Divergent plate boundary Areas where adjacent tectonic plates are separating. A spreading zone. Dolomite A calcium-magnesium carbonate mineral, CaMg(C03)2-Dolostone A sedimentary carbonate rock primarily consisting of dolomite. 

Ground dolomite (calcium magnesium carbonate) and limestone fillers are also used. 

The high calcium content in the majolica found in Mexico City— 21.4% calculated as pure calcium carbonate compared with 5.9% in sherds of Teotihuacan—suggests that a calcium compound such as calcium or calcium magnesium carbonate may have been added to the majolica either as a temper or through deposition during burial. Petrographic examination of cross sections of representative Mexico City majolica sherds show heavy deposits of birefringent material with structures... 

Calcite and whitings (RI 1.5-1.7) are naturally occurring calcium carbonate deposits. The lowest cost grades are ground limestone or the mixed calcium magnesium carbonate ore, dolomite. Synthetic calcium carbonate is also used as an extender, but it is more expensive. 

The dissolution of dolomite, calcium magnesium carbonate, in hydrochloric acid is a reataion of particular importance in the acid stimulation of dolomite oil teseivoirsd The oil is contained in pore space of the carbonate material and must flow through the small pores to reach the well bore. In matrix stimulation, HCl is injected into a well bore to dissolve the porous carbonate matrix. By dissolving the solid carbonate the pores will increase in size, and die oil and gas will be able to flow out at faster rates, thereby increasing the productivity of tbe well. The dissolution reaction is... 

Compounds of magnesium are very abundant in the earth. Dolomite, or calcium magnesium carbonate (CaMg(C03)2), is an example. Dolomite has been used as a building material for centuries. 

Figure 6.11 Stability relations among the calcium-magnesium carbonates at 25 C and 1 bar total pressure as a function of the mCa VmMg ratio and CO2 pressure. The stippled field is that of ordered, well-crystallized dolomite. The plot shows that when dolomite is kinetically inhibited from precipitating, nesquehonite, hydromagnesite, or brucite can coexist with calcite under metastable conditions. Huntite (not shown) is stable relative to crystalline dolomite for mCa VmMg < 10 . From D. Langmuir, Physical and chemical characteristics of carbonate water. In Guide to the hydrology of carbonate rocks, P. E. La-moreaux, B. M. Wilson, and B. A. Memeon, eds. 1984 by UNESCO. Used by permission.

Equilibrium reactions among all the calcium-magnesium carbonates can be written in terms of the CO2 pressure and mCa VmMg ratio in water ([H2O] = 1). A diagram in which the phase bound-... 

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