Sodium, calcium metal preparation from a solution

Silver(II) oxide, 4 12 Silver oxynitrate, Ag70sN03, formation of, by silver(II) oxide, 4 13 Silver subfluoride, Ag2F, 6 18,19 Sodium, calcium metal preparation from a solution in, 6 18, 24... 

In the preparation of handsheets, the NBS NBH furnish was soaked for 2 h in 0.0005% Ca(OH)2 solution prior to the beating step. The pulp was then beaten in deionized water containing sodium borohydride (0.1% pulp weight) and 0.02% calcium hydroxide or 2.5% calcium carbonate (22). A Craftool Hollander laboratory beater was employed. Handsheets were prepared with a Noble and Wood brass sheet-making machine, which had been painted to prevent the contact of pulp with brass. The metal wire was overlaid with polyester fiber screening (75 mesh). Handsheets were also prepared from the same pulp furnish with the Noble and Wood brass sheet-forming machine before it had been painted. These papers had a copper content of 150 ppm as a result of contamination from the brass. 

Calcium was first isolated by Sir Humphry Davy in 1808. Davy produced calcium amalgam by electrolyzing an aqueous solution of the chloride, CaCl, using a liquid-mercury cathode such as in the chlor-alkali process employing a mercury cathode. After distilling mercury from the amalgam formed, he obtained the pure calcium metal. His discovery showed lime to be an oxide of calcium. Later, Moissan reduced the calcium diiodide with sodium. The first industrial production of calcium metal was reported in 1904 and attributed to Brochers and Stockem, who prepared it by electrolysis of the molten chloride. This process was discontinued in 1940 and replaced by aluminothermic reduction of the oxide. 

Electrowinning of Aluminum. Aluminum, the most abundant metal in the Earth s crust, did not become readily available commercially until the development of the Hall-Heroult process. This process involves electrolysis of dry aluminum oxide (alumina) dissolved in cryolite (sodium aluminum hexafluoride). Additional calcium fluoride is used to lower the melting point of the cryolite. The process runs at about 960 degrees Celsius and uses carbon electrodes. The alumina for the Hall-Heroult process is obtained from an ore called bauxite, an impure aluminum oxide with varying amounts of compounds such as iron oxide and silica. The preparation of pure alumina follows the Bayer process The alumina is extracted from the bauxite as a solution in sodium hydroxide (caustic soda), reprecipitated by acidification, filtered, and dried. The electrolysis cell has a carbon coating at the bottom that forms a cathode. 

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