Introduction to Mineral ProcessingMineral processing has three principle branches, to quote Taggart, "Ore Dressing, which comprises the methods of separation of solids in inorganic crude by means which do not affect substantial chemical change; Extractive Metallurgy, which utilizes chemical reactions for separations of constituents from solids in inorganic crude; and, Fuel Technology, which employs both physical and chemical methods for separating and rearrangement of liquid gaseous and solid components in crude oil and natural gas, tar sands, shale oil, or coal."
Mineral processing covers a very wide field and dates back to the early history of man which started with the production and use of native minerals such as gold, silver, copper, mercury, and meteoric iron which were washed or picked from deposits on the surface of the earth and worked because of their malleability. Later, melting was discovered and then it was possible to cast objects of these metals, excluding mercury. The discovery of a method for reducing the metallic oxide probably was developed from melting fragments of oxides or roasted sulfides with charcoal, so that the native metal could be produced in simple blast furnaces such as are used today in rural parts of Spain, China, and elsewhere. Eventually, it was learned that iron could be readily worked when hot, which resulted in its replacing bronze for tools, weapons, and cutlery.
Mineral processing is an art of treating crude ores and mineral products in order to separate the valuable minerals from the waste rock, or gangue. It is the first process that most ores undergo after mining in order to provide a more concentrated material for the procedures of extractive metallurgy.
Although more than 2,800 mineral species have been identified, only about 100 are considered ore minerals. Among these are hematite, magnetite, limonite, and siderite, which are the principal sources of iron; chalcopyrite, bornite, and chalcocite, the principal sources of copper; and sphalerite and galena, the principal sources, respectively, of zinc and lead. Copper, molybdenum, and gold are commonly found in disseminated deposits - i.e., scattered more or less uniformly through a large volume of rock. Copper, lead, and zinc are frequently found in massive sulfide deposits. Many such deposits are believed to have been formed by precipitation from volcanic exhalations on the seafloor or by metasomatic replacement (a process of simultaneous solution and deposition). The term “ore” was originally applied only to metallic minerals, but its definition has been broadened to include such nonmetallic substances as sulfur, calcium fluoride (fluorite), and barium sulfate (barite).
No ore deposit consists entirely of a single ore mineral. The ore is always mixed with unwanted or valueless rocks and minerals that are collectively known as gangue. The ore and the gangue are mined together - i.e., taken out of the host rock in a mass, by either mechanical or manual means. Then the ore is separated from the gangue by various operations known collectively as mineral processing, or ore dressing. The desired metallic element is then extracted from the ore by various smelting, roasting, or leaching processes. After this, the metal may be still further refined (purified) or alloyed with other metals, as in a copper refinery or steel mill. Mining, processing, and refining are thus successive steps in the utilization of an ore deposit to yield a metal.
Exercise 25 Match heads and tails of the sentences.
Exercise 26 Choose the right word in brackets.
1. Mineral processing is an art of treating crude ores and mineral products in order to separate the valuable minerals from the (waste/ hard) rock. 2. Copper, lead, and zinc are (frequent/frequently) found in massive sulfide deposits. 3. The discovery of a method for reducing the metallic oxide probably was developed from melting fragments of (oxides/ acids) or roasted sulfides with charcoal. 4. The ore is always mixed with unwanted or valueless rocks and minerals that are collectively known as (metal/ gangue). 5. Although more than 2,800 mineral species have been identified, only about 100 are considered ore (metals/minerals). 6. Among these are hematite, magnetite, limonite, and siderite, which are the principal sources of (iron/ copper). 7. Many such deposits are believed to have been formed by precipitation from volcanic (explosions/exhalations) on the seafloor or by metasomatic replacement 8. Copper, lead, and zinc are frequently found in (small/ massive) sulfide deposits. 9. The ore is separated from the gangue by various operations known collectively as (mining/mineral processing). 10. The desired metallic element is then (extraction/extracted) from the ore by various smelting, roasting, or leaching processes. Exercise 27 Put these steps in order and in pairs describe each step:
Exercise 28 Find the words in the text that have the following suffixes.
Exercise 29 Make questions for the answers:
1. 2,800 mineral species 2. in rural parts of Spain, China 3. ore dressing, extractive metallurgy and fuel technology. 4. gangue 5. in massive sulfide deposits. 6. the first process 7. a process of simultaneous solution and deposition 8. mineral processing 9. by mechanical or manual means 10. in disseminated deposits
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