Rhenium Mining
Rhenium Mining
Rhenium accounts for 77th most abundant element in the earth. It doesn't occur in a major ore or chemical compounds in nature and so the direct mining of it seems impossible. However it occurs with many minerals ranging from 0.0001% to 0.3%. Molybdenite is the major commercial ore to extract rhenium as it comprises of rhenium with an average of 0.2%. Chile is the largest producer of rhenium having half of the global production by their copper deposits.
Mining of Rhenium:
Molybdenite , the chief ore for rhenium extraction is mined from both open pit method and underground cave method. The open pit methods are mostly handled in the regions where the availability of ore is on the surface and also in some minimal molybdenite regions such as copper mines. The open pit technique is bit less expensive than the underground cave method.
The underground caving technique is confidently used in the areas of rich molybdenite ore which are buried deep down the soil. In this technique the rocks were made to collapse with their own weight and taken up to the surface for processing. This method to extract is only executed in well financial mines as cost of this technique remains quite high.The extraction of rhenium is mostly done in the byproduct mines of molybdenite and copper.
Extraction of Rhenium:
The extraction of the rhenium can be done from smelting of molybdenite ore or the electrolytic-refining of copper.
By smelting molybdenite:
The smelting process of the molybdenite metallic ore initially starts with the roasting of ore in the presence of oxygen. By the process, the rhenium in the ore gains oxygen to its composition and converts into an inorganic anhydrous Rhenium (VII) oxide (Re_2 O_7).
The anhydrous Re_2 O_7 which are yellow in color are collected out of flue dusts and gases by leaching of the anhydrous rhenium are dissolved with water which in turn produces perrhenic acid. The resulted perrhenic acid is precipitated with ammonium chloride to produce perrhenate salts (NH_4 ReO_4). Finally the perrhenate salts are reduced by hydrogen to rhenium metal.
By electrolytic refining of copper:
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The copper sulphate (CuSO4) is induced to the electrolytic refining process with concentrated sulphuric acid as an electrolyte. As the refining starts, the impurities and other compounds are settled as the anode sludge. From the anode sludge the rhenium is roasted into Rhenium (VII) oxide (Re_2 O_7). Then Re_2 O_7is mixed with water and produces perrhenate acid. The resulted acid is converted to perrhenate salt (NH4 ReO4). At last, the salt is reduced to metallic rhenium by hydrogen.
The above two are major extraction techniques handled by industries for the commercial production of rhenium Rhenium is discovered in the form of rheniite (ReS2) in Iturup Island in Kurile Islands of Russia and Pagoni Rachi deposits in north eastern Greece.The producers of rhenium across the world are Chile, Poland, United States of America, Uzbekistan and Kazakhstan. The global production of rhenium accounts about 50,000 metric tons.
Rhenium:
Rhenium accounts for 77th most abundant element in the earth. It doesn't occur in a major ore or compounds in nature and so the direct mining of it seems impossible. However it occurs with many minerals ranging from 0.0001% to 0.3%. Molybdenite is the major commercial ore to extract rhenium as it comprises of rhenium with an average of 0.2%. Chile is the largest producer of rhenium with half of the global production with their copper deposits.
Extraction of Rhenium:
The extraction of the rhenium can be done from the smelting molybdenite ore or the electrolytic-refining of copper.
By Smelting Molybdenite:
The smelting process of the molybdenite metallic ore initially starts with the roasting of ore by oxidizing it. The rhenium in the ore is gains oxygen to its composition and converts into an inorganic anhydrous Rhenium (VII) oxide (Re_2 O_7). The anhydrous Re_2 O_7 which are yellow in color are collected out of flue dusts and gases by leaching are dissolved with water which in turn produces perrhenic acid. The resulted perrhenic acid is precipitated with ammonium chloride to produce perrhenate salts (NH_4 ReO_4). Finally the perrhenate salts are reduced by hydrogen to rhenium metal.
By Electrolytic Refining Of Copper:
The copper sulphate (CuSO4) is induced to the electrolytic refining process with concentrated sulphuric acid as an electrolyte. As the refining starts the impurities and other compounds are settled as the anode sludge. From the anode sludge the rhenium is roasted into Rhenium (VII) oxide (Re_2 O_7). Then Re_2 O_7is mixed with water and produces perrhenate acid. The resulted acid is converted to perrhenate salt (NH4 ReO4). At the last the salt is reduced to metallic rhenium by hydrogen.
The above two are the most extraction techniques handled by the industries for the commercial production of rhenium.
Rhenium is discovered in the form of rheniite (ReS2) in Iturup Island in Kurile Islands of Russia and Pagoni Rachi deposits in north eastern Greece.
The producers of rhenium across the world are Chile, Poland, United States of America, Uzbekistan and Kazakhstan. The global production of rhenium accounts about 50,000 metric tons.
Applications:
Rhenium is one of the rarest elements in Earth's crust with a average concentration of 1 ppb; other sources quote the number of 0.5 ppb making it the 77th most abundant element in Earth's crust. Rhenium is most likely not found free in nature, but occurs in amounts up to 0.2% in the mineral molybdenite, the major marketable source, although single molybdenite samples with up to 1.88% have been found. Chile has the world's major rhenium reserves, part of the copper ore deposits, and was the leading producer as of 2005.
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