Heavy minerals

The heavy mineral sand concentrates are scmbbed to remove any surface coatings, dried, and separated into magnetic and nonmagnetic fractions (see Separation, magnetic). Each of these fractions is further spHt into conducting and nonconducting fractions in an electrostatic separator to yield individual concentrates of ilmenite, leucoxene, monazite, mtile, xenotime, and zircon. Commercially pure zircon sand typically contains 64% zirconium oxide, 34% siUcon oxide, 1.2% hafnium oxide, and 0.8% other oxides including aluminum, iron, titanium, yttrium, lanthanides, uranium, thorium, phosphoms, scandium, and calcium. 

Barfles-Mo2ley 1.2 X 1.5 2.5 rougher concentrator for very fine heavy minerals... 

Humphrey s spiral 0.6 dia, 2.9 1-5 beach sands, iron ore, and other heavy minerals... 

Reichert cone 60-90 ubeach sands, coal, iron ore, trace heavy minerals... 

Continental Shelf. A variety of terms may be appHed to deposits in the continental shelf (conshelf) including beach, bank, alluvial, strand-line, heavy mineral, or placet. These contain mostly industrial materials, mineral sands, or precious metals (Table 1). 

Induced-roU separators have also been used in the concentration and cleaning of heavy minerals found in beach sands. Examples are the mtUe and ilmenite beach sands of Florida and New Jersey. Induced-roU separators are frequently used in combination with high tension or electrostatic separators. 

Diamonds were first discovered in ancient times in India and Borneo and later in Brazil in 1670 in alluvial deposits where water had sorted minerals on the basis of density and toughness. This type of tumbling often concentrates the better quality crystals such as those found in the ocean off the west coast of Africa. Exploration can be done by stream panning or drilling in conjunction with a search for the heavy mineral assemblages that accompany diamond. Alluvial deposits account for about 40% of the diamond found in primary sources. 

Methylfuran [534-22-5] M 82.1, b 62.7-62.8 /731mm, d 0.917, n 1.436. Washed with acidified satd ferrous sulfate soln (to remove peroxides), separated, dried with CaS04 or CaCl2, and fractionally distd from KOH immediately before use. To reduce the possibility of spontaneous polymeri.sation, addition of about one-third of its volume of heavy mineral oil to 2-methylfuran prior to distn has been recommended. 

The conveyor belt is one of the most efficient devices available for moving goods over short distances. Billions of tons of minerals, foodstuffs and consumer goods are handled in this way every year. Figure 28.1 shows the essentials of a typical conveyor system. The following data are typical of the largest conveyors, which are used for handling coal, iron ore and other heavy minerals. 

A suspension of 25.2 g of crude (52) in 250 ml of heavy mineral oil is covered with an atmosphere of nitrogen, stirred, and heated at 330-335° for 5 hr. The solution is then cooled to room temperature, diluted with 500 ml of petroleum ether (bp 35-60°) and filtered. The crude 3-[4-oxo-2-phenyl-3, (4H)-quinazolinyl]estra-l,3,5(10)-trien-17-one (53), which weighs 25 g and exhibits 279 mju (g 14,100), is used directly for the next step. 

In 1751 the Swedish mineralogist, A. F. Cronstedt, discovered a heavy mineral from which in 1803 M. H. Klaproth in Germany and, independently, i. i. Berzelius and W. Hisinger in Sweden, isolated what was thought to be a new oxide (or earth ) which was named ceria after the recently discovered asteroid, Ceres. Between 1839 and 1843 this earth, and the previously isolated yttria (p. 944), were shown by the Swedish surgeon C. G. Mosander to be mixtures from which, by 1907, the oxides of Sc, Y, La and the thirteen lanthanides other than Pm were to be isolated. The small village of Ytterby near Stockholm is celebrated in the names of no less than four of these elements (Table 30.1). 

B. l-Bromo-2-fluorobenzene. Cautionl This step should be carried outm a hood because the PFS evolved on thermal decomposition of the diazonium salt is poisonous. The apparatus consists of a 1-1., three-necked, round-bottomed flask equipped with a thermometer, a condenser, a magnetic stirrer (optional), and a 250-ml. Erlenmeyer flask that is attached by means of a short rubber Gooch connecting tube. The dry powdered hexafluorophosphate salt is placed in the Erlenmeyer flask, and 300 ml. of heavy mineral oil is placed in the round-bottomed flask. The mineral oil is heated to 165-170° by means of an oil bath or electric heating mantle and maintained at this temperature while the salt is added rapidly in portions over a period of 30 minutes. The flask is cooled rapidly to room temperature, the side flask is removed, and 400 ml. of 10% aqueous sodium carbonate is added slowly through the condenser. The mixture is steam-distilled until no more oil is visible in the distillate. 

An estimate of the applicability of gravity concentration to the separation of a mineral pair of differing specific gravity can be obtained by making use of what is called the concentration criterion, which makes use of the ratio (p, - p2)/(p3 - p2), where pj is the specific gravity of the heavy mineral, p3 is the specific gravity of the light mineral, and p2 is the... 

Figure 2.35 (A) Flowsheet for heavy mineral processing in Thailand. (B) Flowsheet for processing bastnasite from mountain pass, California.

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