Minerals extracting metal from

Elements at the right of the p block have characteristically high electron affinities they tend to gain electrons to complete closed shells. Except for the metalloids tellurium and polonium, the members of Groups 16/VI and 17/VII are nonmetals (Fig. 1.62). They typically form molecular compounds with one another. They react with metals to form the anions in ionic compounds, and hence many of the minerals that surround us, such as limestone and granite, contain anions formed from non-metals, such as S2-, CO,2-, and S042-. Much of the metals industry is concerned with the problem of extracting metals from their combinations with nonmetals. 

We can extract metals from all the minerals. All ores are minerals but all minerals are not ores. Think about it ... 

The possibility of using brine to slurry the ore in the presence of an oxidizer such as chlorine in order to extract metals from the more common sulfide minerals has been studied by Strickland and co-workers (Jl, S12, S13). The reactions of acid chlorine solutions with galena (PbS), pyrite (FeSj), sphalerite (ZnS), chalcocite (CujS), covellite (CuS), chalcopyrite (CuFeSs), bornite (CusFeSi), pyrrhotite (FeS), and arsenopyrite (FeAsS) were examined with respect to their reaction rates and mechanisms. 

There is currently much interest in the use of microorganisms to recover toxic or valuable metals from solution and to extract metals from low-grade or refractory ores. In both cases, the availability of this new technology depends upon the exploitation of natural processes in which microorganisms cause the deposition or the solubilization of minerals. 

Locating and mining mineral ores, concentrating ores, transporting the concentrates to a smelter, extracting metals from concentrates, and waste generation all have an effect on the environment. When one metal, such as lead, is replaced with another metal, a different set of environmental issues is expanded. 

The abundance in the earth s crust of metals that are used in electronic products is shown in Table 7 [16]. Extracting metals contained in seawater is not economically feasible. The major supply of metals is extracted from mineral ore in the earth s continental crust. There is considerable variation in the cost of extracting the ore and processing it into elemental metals. As the readily available resources become depleted, the process of extracting metals from mineral ores is increasingly more difficult and expensive. For example, in 1900 in the U.S. the copper content in rich ore was more than 4% by weight. By 1950, the available ore contained less than 1 % copper and has continued to decline such that the yield is currently less than 0.5%. 

Iron [7439-89-6J, Fe, from the Latin ferrum, atomic number 26, is the fourth most abundant element in the earth s cmst, outranked only by aluminum, sihcon, and oxygen. It is the world s least expensive and most useful metal. Although gold, silver, copper, brass, and bron2e were in common use before iron, it was not until humans discovered how to extract iron from its ores that civilization developed rapidly (see Mineral processing and recovery). 

Nonferrous Metal Production. Nonferrous metal production, which includes the leaching of copper and uranium ores with sulfuric acid, accounts for about 6% of U.S. sulfur consumption and probably about the same in other developed countries. In the case of copper, sulfuric acid is used for the extraction of the metal from deposits, mine dumps, and wastes, in which the copper contents are too low to justify concentration by conventional flotation techniques or the recovery of copper from ores containing copper carbonate and siUcate minerals that caimot be readily treated by flotation (qv) processes. The sulfuric acid required for copper leaching is usually the by-product acid produced by copper smelters (see Metallurgy, extractive Minerals RECOVERY AND PROCESSING). 

An alloy of nickel was known in China over 2000 years ago, and Saxon miners were familiar with the reddish-coloured ore, NiAs, which superficially resembles CU2O. These miners attributed their inability to extract copper from this source to the work of the devil and named the ore Kupfemickel (Old Nick s copper). In 1751 A. F. Cronstedt isolated an impure metal from some Swedish ores and, identifying it with the metallic component of Kupfemickel, named the new metal nickel . In 1804 J. B. Richter produced a much purer sample and so was able to determine its physical properties more accurately. 

A single metal may be extracted from several minerals. Thus there are many minerals of copper, such as chalcocite, bornite, chalcopyrite, cuprite, native copper, and malachite one or more of these may occur in an individual deposit. Also, more than one metal may be obtained from a single mineral stannite, for example, yields both copper and tin. A mineral deposit, therefore, may yield several metals from different minerals. 

In the drying of compound intermediates of refractory and reactive metals, particular attention is given to the environment and to the materials so that the compound does not pick up impurities during the process. A good example is the drying of zirconium hydroxide. After the solvent extraction separation from hafnium, which co-occurs with zirconium in the mineral zircon, the zirconium values are precipitated as zirconium hydroxide. The hydroxide is dried first at 250 °C for 12 h in air in stainless steel trays and then at 850 °C on the silicon carbide hearth of a muffle furnace. 

The protocol involving NaOAc-HOAc at pH 5 was first proposed and used by Jackson (1958) to remove carbonates from calcareous soils to analyze soil cation exchange characteristics (Grossman and Millet, 1961). Other researchers used HOAc for the extraction of metals from sediments and soils (Nissenbaum, 1972 Mclaren and Crawford, 1973). Tessier et al. (1979) first used the NaOAc-HOAc solution at pH 5 to dissolve the carbonate fraction from sediments. Since then, the NaOAc-HOAc buffer has been widely used as a specific extractant for the carbonate phase in various media (Tessier et al., 1979 Hickey and Kittrick, 1984 Rapin et al., 1986 Mahan et al., 1987 Han et al., 1992 Clevenger, 1990 Banin et al., 1990). Despite its widespread use, this step is not free from difficulties, and further optimization is required in its application. Questions arise with regard to this step in the elemental extraction from noncalcareous soils, the dissolution capacity and dissolution rates imposed by the buffer at various pHs, and the possibility that different carbonate minerals may require different extraction protocols (Grossman and Millet, 1961 Tessier et al., 1979). 

The silicates are the most widespread minerals. However, extraction of metals from silicates is very difficult. 

As the heats of formation of minerals become more exothermic, i.e., more negative, their thermodynamic stability increases. And so the difficulty by which free metals can be extracted from the minerals also increases. In other words, the more active is the metal, the easier it is to form compounds and the more difficult it is to retrieve the metal from its compounds. This relationship is obvious in the methods by which the metals are removed from their mineral matrix as shown in the third column of the above table heating is a less severe metallurgic process, whereas electrolysis is a more severe method. 

Approximately 75% of all elements found on and in the Earth are metals. They are crystalline solids that at room temperature range from hard to butter-like soft to liquid (mercury). They are generally good conductors of heat and electricity as a result of the swarm of relatively free electrons in their outer shell that move without much resistance to other elements, particularly those with a dearth of electrons in their outer shells. In pure states, most metals have a shiny luster when cut. Those located at the far left of the table have only one electron in their outer shell. Therefore, they are very reactive and are not usually found in pure form. Instead, they are found in compounds, minerals, or ores that must be processed to extract the pure metal from the other elements in the compounds. 

This picture changed in the 1886 when an American chemist, Charles Martin Hall (1863— 1914), and a French chemist, Paul Louis-Toussaint Heroult (1863—1914), both discovered, at about the same time, a new process for extracting aluminum from molten aluminum oxide by electrolysis. (It might be noted that both discoverers have the same birth and death dates as well as the same date of discovery.) Hall was inspired by his teacher to find a way to inexpensively produce aluminum metal. He wired together numerous wet cells to form a battery that produced enough electricity to separate the aluminum from the melted aluminum oxide (mixed with the minerals cryolyte or fluorite), by the process known as electrolysis. Hall formed the Pittsburgh Reduction Co., which is now known as the Aluminum Company of America, or Alcoa. His company produced so much aluminum that the price dropped to about sixty cents per kilogram. 

Lanthanum is most commonly obtained from the two naturally occurring rate-earth minerals, monazite and bastnasite. Monazite is a rare earth-thorium phosphate that typically contains lanthanum between 15 to 25%. Bastnasite is a rare earth-fluocarbonate-type mineral in which lanthanum content may vary, usually between 8 to 38%. The recovery of the metal from either of its ores involves three major steps (i) extraction of all rare-earths combined together from the non-rare-earth components of the mineral, (ii) separation or isolation of lanthanum from other lanthanide elements present... 

The initial steps are similar to any other mineral extraction process. This involves crushing mineral, froth flotation, gravity concentration and other steps to obtain platinum metal concentrates that may contain about 30 to 40 wt% of platinum group metals. The concentrate is treated with aqua regia to separate soluble metals, gold, platinum, and palladium from other noble metals such as ruthenium, rhodium, iridium, osmium, and silver that remain in... 

Tantalum pentoxide is obtained as an intermediate in extracting tantalum from the columbite-tantalite series of minerals. Also, the oxide can be made by heating Ta metal in oxygen or air at elevated temperatures. 

Think most diligently about this often bear in mind, observe and comprehend, that all minerals and metals together, in the same time, and after the same fashion, and of one and the same principal matter, are produced and generated. That matter is no other than a mere vapour, which is extracted from the elementary earth by the superior stars, or by a sidereal distillation of the macrocosm which sidereal hot infusion, with an airy sulphurous property, descending upon inferiors, so acts and operates as that there is implanted, spiritually and invisibly, a certain power and virtue in those metals and minerals which fume, moreover, resolves in the earth into a certain water, wherefrom all metals are thenceforth generated... 

Brookhaven National Laboratory s (BNL s) biochemical recovery of radionuclides and heavy metals is a patented biochemical recovery process for the removal of metals and radionuclides from contaminated minerals, soil, and waste sites. In this process, citric acid, a naturally occurring organic complexing agent, is used to extract metals and radionuclides from solid wastes by the formation of water-soluble, metal-citrate complexes. The complex-rich extract is then subjected to microbiological biodegradation that removes most of the extracted heavy metals. 

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