Heavy minerals estimation

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... 

Rutile is formed primarily by the crystallization of magma with high titanium and low iron contents, or by the metamorphosis of titanium-bearing sediments or mag-matites. The rutile concentrations in primary rocks are not workable. Therefore, only sands in which rutile is accompanied by zircon and/or ilmenite and other heavy minerals can be regarded as reserves. The world reserves of rutile are estimated to... 

Estimation. — A fairly accurate measure of the amount of tungsten in an ore may be made by a simple specific gravity determination, the per cent WO3 being read from tables. This method gives satisfactory results on any one ore, provided the gangue is quite uniform and other heavy minerals are absent. It is not reliable, however, since it permits the salting of an ore with barite, cassiterrte, etc. 

The most important barium mineral is heavy spar (BaS04, barite), whose deposits are distributed over the whole world. Worldwide extraction in over 30 countries was 4.4 10 t/a in 1995, of which 1.5 (O t/a was produced in China, 0.58 10 t/a in India and 0.54 lO t in the USA. In the Federal Republic of Germany the production of marketable raw heavy spar and the quantity of processed heavy spar were together 0.15 I O t/a in 1995. The worldwide production peaked in 1981 at 8.3 10 t/a, which is about double the 1995 production of 4.4 10 t/a. This decline was mainly due to less exploration and drilling. The worldwide reserves of heavy spar have been estimated to be ca. 1.8- 10 t, of which 0.17 10 t are certain. 

The development of the process has been closely associated with the dairy industry. The use of spray drying in the dairy industry dates back to around 1800, but it was not until 1850 that it became possible to dry milk on industrial scale. Since then, this technology has been developed and expanded to cover a large food group which is now successfully spray dried. Over 20,000 spray dryers are estimated to be in use commercially, at present, to agro-chemical products, biotechnology products, fine and heavy chemicals, dairy products, foods, dyestuffs, mineral concentrates, and pharmaceuticals in evaporation capacities ranging from a few kg per hour to 50 tons/h (Mujumdar 2000). 

Of the 7 million chemical compounds known today, about 60000 to 70000 are actually in current use. The quantity of compounds and their metabolites which reach the environment yearly (predominantly via the atmosphere as exhaust gases and wastewater) is estimated to be about 65000 of these 65000 (under the best circumstances) only a fraction of the especially harmful 4000 to 6000 are actually detected. Heavy metals, pesticides, mineral oils and organic pollutants (solvents) all belong to this group. 

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