Extraction methods elements from ores

The electrolysis of a mixture of ZnCl2 with alkaline chlorides and the effect of different elements were investigated as a method to extract zinc from ores and industrial wastes. The studies on electrolysis of ZnCl2 in molten ZnCl2-KCl-NaCl... 

Sources of transition metals Copper, silver, gold, platinum, and palladium are the only transition metals that are unreactive enough to be found in nature uncombined with other elements. All other transition metals are found in nature combined with nonmetals in minerals such as oxides and sulfides. Recall that minerals are mixed with other materials in ores. Metallurgy is the branch of applied science that studies and designs methods for extracting metals and their compounds from ores. The methods are divided into those that rely on high temperatures to extract the metal, those that use solutions, and those that rely on electricity. Electricity also is used to purify a metal extracted by high temperatures or solutions. 

The main point is that man had learned how to extract these various elements from their natural environment, from their ores. The method was basically a crude one and involved only the use of heat and, in some cases, carbon. It is a method quite possible in a campfire and, of course, rather easy to demonstrate in a laboratory. 

Although the alchemists failed to find a method for the transmntation of base metals into precious metals, a number of important chemical processes resulted from their efforts. For example, they extracted metals from ores produced a number of inorganic acids and bases that later became commercially important and developed the techniques of fusion, calcination, solution, filtration, crystallization, sublimation, and, most importantly, distillation. During the Middle Ages, they began to try to systematize the results of their primitive experiments and their fragments of information in order to explain or predict chemical reactions between substances. Thns the idea of chemical elements and the first primitive forms of the chemical Periodic Table appeared. 

Apart from the metal rich zones in the neighborhood of ore deposits and other rocks especially rich in particular trace elements such as peridotites and serpentinites, from central Europe, little data exist yet on the dependence of trace element behavior in common rocks. For several elements, such as Ni and As, upper limits of the trace uptake of plants seem to exist. As soil and plant concentrations are concerned, the uptake is normally dependant on the available concentrations determined with extraction methods such as 0.1 N NaN03. Whereas data on higher plants are relatively abundant, more data on naturally Influenced trace elements in mosses and lichens would certainly be useful. 

The camotite ore of the Colorado Plateau area contains a workable proportion of vanadium in addition to uranium, and processes have been devised for the simultaneous recovery of both elements by solvent extraction methods. The Shiprock plant in New Mexico, for example, extracts first the uranium from a sulphate leach liquor, by means of a solvent containing 10 per cent D2EHPA with 2-5 per cent TBP, in kerosene. A second solvent cycle, with different proportions of the two phosphates, then extracts vanadium from the first cycle raffinate. Sodium carbonate is then used for backwashing the uranium and 10 per cent sulphuric acid for the vanadium. 

In the present time our organosilicon adsorbents found the practice application in such as fields such as, for example 1) the method of spectral-chemical determination of gold Clarke quantities in poor ores and rocks has been applied in analytic practice of geological establishments and research institutes 2) at the first time soi ption process was used in hydro-chemical analyze of fresh water. This method has been allowed to analyze of Baikal water 3) for purification metallurgical waters and waste solutions of chemical-metallurgical plants due to toxic elements 4) for creation the filters for extraction of rare elements, for example, uranium 5) for silver utilization from wasted of cinema-photo manufactory. This method has been applied to obtain the silver of high purity. 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS, and sphalerite, ZnS (Fig. 15.11). Because these ores are so common, sulfur is a by-product of the extraction of a number of metals, especially copper. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H,S. The low melting point of sulfur (115°C) is utilized in the Frasch process, in which superheated water is used to melt solid sulfur underground and compressed air pushes the resulting slurry to the surface. Sulfur is also commonly found in petroleum, and extracting it chemically has been made inexpensive and safe by the use of heterogeneous catalysts, particularly zeolites (see Section 13.14). One method used to remove sulfur in the form of H2S from petroleum and natural gas is the Claus process, in which some of the H2S is first oxidized to sulfur dioxide ... 

The basis for the claim of discovery of an element has varied over the centuries. The method of discovery of the chemical elements in the late eightenth and the early nineteenth centuries used the properties of the new sustances, their separability, the colors of their compounds, the shapes of their crystals and their reactivity to determine the existence of new elements. In those early days, atomic weight values were not available, and there was no spectral analysis that would later be supplied by arc, spark, absorption, phosphorescent or x-ray spectra. Also in those days, there were many claims, e.g., the discovery of certain rare earth elements of the lanthanide series, which involved the discovery of a mineral ore, from which an element was later extracted. The honor of discovery has often been accorded not to the person who first isolated the element but to the person who discovered the original mineral itself, even when the ore was impure and that ore actually contained many elements. The reason for this is that in the case of these rare earth elements, the earth now refers to oxides of a metal not to the metal itself This fact was not realized at the time of their discovery, until the English chemist Humphry Davy showed that earths were compounds of oxygen and metals in 1808. 

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