Magnesium molten, density

Maclaurin series, A-65 to 67 Madelung constant, 12-32 Magnesium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 molten, density, 4-139 to 141 thermal conductivity, 12-203 to 204 thermal properties, 12-201 to 202 thermodynamic properties, 5-1 to 3 vapor pressure, 6-61 to 90 vapor pressure, high temperature, 4-136 to 137... 

Electrowinning of Other Metals. Magnesium, like aluminum, is a low-density metal and is also manufactured by electrolysis. The electrolysis of molten magnesium chloride (in the presence of other metal chlorides to lower the melting point) yields mj ne-sium at the cathode. The scale of ms nesium production is not as large as that of aluminum, amounting to several hundred thousand metric tons per year. Ms -nesium is used in aircraft alloys, flares, and chemical syntheses. 

In practice calcium and magnesium need to be dissolved into the lead bullion as a first step and this encounters significant problems due to the ready oxidation of the reagents at operating temperature, and due to the low density relative to lead which causes them to float to the surface of the lead. Magnesium is also prone to bum when exposed to air at kettle temperatures. Hence the metals are handled in ingot form and are usually placed in a wire cage, immersed into the molten lead in a... 

Aluminium oxide melts at 2000 °C, and the technical difficulties in working at this temperature would be almost insuperable. The oxide dissolves in cryolite, Na3Alp6, however, and the eutectic contains about 10% AI2O3 and melts below 1000 C. Other salts can be added to reduce the m.p. still further, but they must not increase the density of the melt beyond 2.3, the density of molten aluminium, since the aluminium produced is collected as the lower layer to prevent oxidation. Magnesium fluoride and up to 5% calcium fluoride are common additions, and the working temperature is then not much above 900 °C. 

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