Magnesium beryl

The alkali metals of Group I are found chiefly as the chlorides (in the earth s crust and in sea water), and also as sulphates and carbonates. Lithium occurs as the aluminatesilicate minerals, spodimene and lepidolite. Of the Group II metals (beryllium to barium) beryllium, the rarest, occurs as the aluminatesilicate, beryl-magnesium is found as the carbonate and (with calcium) as the double carbonate dolomite-, calcium, strontium and barium all occur as carbonates, calcium carbonate being very plentiful as limestone. 

Beryllium is found in some 30 mineral species, the most important of which are bertrandite, beryl, chrysoberyl, and phenacite. Aquamarine and emerald are precious forms of beryl. Beryl and bertrandite are the most important commercial sources of the element and its compounds. Most of the metal is now prepared by reducing beryllium fluoride with magnesium metal. Beryllium metal did not become readily available to industry until 1957. 

Beryllium is extracted from the main source mineral, the alumino-silicate beryl, by conversion to the hydroxide and then through either the fluoride or the chloride to the final metal. If the fluoride is used, it is reduced to beryllium by magnesium by a Kroll-type reaction. The raw metal takes the form of pebble and contains much residual halides and magnesium. With the chloride on the other hand, the pure metal is extracted by electrolysis of a mixture of fused beryllium chloride and sodium chloride. The raw beryllium is now dendritic in character, but still contains residual chloride. 

In Table XVIII are given values of the radius ratio for the salts of beryllium, magnesium and calcium (those of barium and strontium, with the sodium chloride structure, also obviously satisfy the radius ratio criterion). It is seen that all of the sodium chloride type crystals containing eight-shell cations have radius ratios greater than the limit 0.33, and the beryl-... 

Metallic beryllium is produced by reduction of beryllium halide with sodium, potassium or magnesium. Commercially, it is obtained primarily from its ore, beryl. Beryllium oxide is separated from silica and alumina in ore by melting the ore, quenching the solid solution, and solubilizing in sulfuric acid at high temperatures and pressure. Silica and alumina are removed by pH adjustment. Beryllium is converted to its hydroxide. Alternatively, beryl is roasted with complex fluoride. The products are dissolved in water and then pH is adjusted to produce beryllium hydroxide. 

Many chemical properties of beryllium resemble aluminum, and to a lesser extent, magnesium. Notable exceptions include solubility of alkali metal fluoride-beryllium fluoride complexes and the thermal stability of solutions of alkali metal beryllates. 

A Note on the Alkaline-earth Family. The early chemists gave the name earth to many non-metallic substances. Magnesium oxide and calcium oxide were found to have an alkaline Reaction, and hence were called the alkaline earths. The metals themselves (magnesium, calcium, strondum, and barium) were isolated in 1808 by Sir Humphry Davy. Beryllium was discovered in the mineral beryl (BegAl2S QOjg) in 1798 and was isolated in 1828. 

Alkoxyl group exists in the non-polar position of some xanthates and dithiophosphates, which have properties similar to those of alkyl group and produce more froth. For example, etheralkyl carboxylate (ECA), R ,-(OC2H4) 2-OCH2COOH, has been reported as a collector where ni is Cg ig chain and W2 is the number of alkoxyl groups (0-16). Since its Ca or Mg salts with ni = 10, 12, 14, 17 and h2 = 10, 20 30 are soluble in water, ECA is suitable under hard water and low pH (<6) conditions for the flotation of calcium or magnesium minerals, chalcopyrite and beryl with better selectivity. FloatabiUty of Ca minerals is found to linearly decrease with n values and increase with h2 values. 

CHLORODIFLUOROMETHANE (75-45-6) Mixtures with 50% air are combustible difficult to ignite. Incompatible with aluminum, barium, beryl-lium, decaborane, difluo-romethylene dihypofluorite, fluorine, lithium, magnesium, potassium, potassium acetylene-... 

Beryllium Beryl (BesALSieOig) Electrolysis of fused BeClg or reduction of BeFg with magnesium Alloy with copper Highly X-ray permeable Nuclear reflector/moderator... 

CaS04 2 H2O) in plasters to decorate their tombs. These two alkaline earths are among the most abundant elements in the Earth s crust (calcium is fifth and magnesium sixth, by mass), and they occur in a wide variety of minerals. Strontium and barium are less abundant but like magnesium and calcium, they commonly occur as sulfates and carbonates in their mineral deposits. Beryllium is fifth in abundance of the alkaline earths and is obtained primarily from the mineral beryl, 863 2(8103)6. All radium isotopes are radioactive (the longest lived isotope is Ra, with a half-life of 1600 years). Pierre and Marie Curie first isolated radium from the uranium ore pitchblende in 1898. Physical properties of the alkaline earths are given in Table 8.4. 

Beryllium occurs principally as the silicate mineral beryl, Be3Al2[Si60i8] (silicates, see Section 14.9). It is also found in many natural minerals, and precious forms include emerald and aquamarine. Magnesium and calcium are the eighth and fifth most abundant elements, respectively, in the Earth s crust, and Mg is the third most abundant in the... 

The reactivities of alkaline earth metals with water vary quite markedly. Beryl-limn does not react with water magnesium reacts slowly with steam calcium, strontium, and barimn are reactive enough to attack cold water ... 

Cordierite with ideal formula Al3(Fe )2(AlSi5)Oig is structurally similar to beryl. The principal octahedral cations are Fe " and some Mg instead of Al. The spectra of both magnesium and iron cordeirites exhibit spectra consisting of a predominant ferrous doublet with pe = 115 mm/s and A — 2.3 mm/s. A second, much weaker, ferrous component is observed which was attributed to channel iron [200]. However, this second has also been interpreted as being due to Fe " replacing Al, whereas Na enters the center of the rings [201]. 

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