Chemistry Assignment

Topics: Aluminium, Oxygen, Bauxite Pages: 8 (3083 words) Published: June 23, 2013
Metals are mined from ores, considering yield to see if it is economically viable for a business to mine at a particular site. However, due to environmental damage and global warming, recycling has increased globally to create a sustainable future. By examining the cost and energy expenditure of recycling and extracting aluminium we can understand why recycling is a better choice than extracting metal from its ore. Discuss the importance of predicting yield in the identification, mining and extraction of commercial ore deposits Yield is the amount of product obtained or in mining terms how much (amount) a particular metal can be extracted from an ore (a deposit of minerals in which a commercial metal can be extracted from). Predicting yield in the processes of identification, mining and extraction is vital to the success of a business. For a business to compete with the global markets, the investment must be profitable and in some cases sustainable to last year’s into the future. Percentage composition is used widely in the mining industries to calculate and measure the yield of particular metal from an ore. For example, haematite (Fe2O3), a compound consisting only of iron and oxygen, can theoretically produce around 70% iron while chalcopyrite (CuFeS2), consisting only of copper, iron and sulphur can produce theoretically 35% copper. However if we express yield as a percentage of the ore dug out, an iron ore would only contain about 16% iron and for a copper ore only contain 1-5% copper. This is because an ore dug out of the ground contains unwanted minerals like dirt, rocks and other waste products which add to the mass of the required mineral ;giving a low yield percentage. Since compounds like chalcopyrite and haematite have uniform composition, ores are mixtures of useful minerals and other waste products which have variable composition (different location will yield different amounts of metals). This will affect if it is economical to mine the ore at a particular location and hence demonstrate that predicting yield is important. Predicting yield in the process of mining and extraction is important, whether extracting the metal from the ore or actually mining it, because it can determine if it is profitable or not. Extraction techniques must be efficient and sustainable. Copper is extracted through roasting it with oxygen before smelting it to form liquid copper. It is then reduced by bubbling air into the liquid copper to reduce copper sulphide to copper metal. Since this sulphur dioxide doesn’t escape fast enough, it forms blister copper with is 98% copper. Electrolysis is used to refine it. Due the significant amount of energy required and the cost involved it may seem copper is unprofitable. Yet if the copper price is high, the consumption is high, location is not far from refinery plants and factories that use copper, if there is a steady sustainable source(abundance) of copper ore and the extraction technique is efficient plus cost effective then a profit can be gained from the high cost of extraction, transport and the money needed to pay for the energy consumption. For a copper ore site to be economical it must contain at least 5% of copper or more. Haematite is extracted through reducing it with carbon monoxide to form iron (metal) which falls to the bottom of the blast furnace. Limestone is also heated in the blast furnace which decomposes and reacts with silica to form a slag that floats on the liquid iron, hence stopping iron from reacting with oxygen. High heat is needed to separate iron from oxygen since iron is reactive to oxygen and sand and limestone is needed to prevent the union of these two elements. Hence for haematite to be economically viable an ore must contain at least 20% iron as the energy needed to extract the metal is large and the world’s demand for iron is great. Since iron ore price is relatively high, a profit can be obtained from deposits of iron ore that contain more than...

Bibliography: Smith. R (2004), Conquering Chemistry, 4th edition, Mc Graw Hill Education, North Ryde
This textbook is useful for the assignment as it answers the relevant dot point with examples and diagram
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