Главная страница | Контакты | Случайная страница Автомобили Астрономия Биология География Дом и сад Другие языки Другое Информатика История Культура Литература Логика Математика Медицина Металлургия Механика Образование Охрана труда Педагогика Политика Право Психология Религия Риторика Социология Спорт Строительство Технология Туризм Физика Философия Финансы Химия Черчение Экология Экономика Электроника

Activities

Activity 1. Make a list of threats to people health caused by mining industry.

Discuss suggestions for solving environmental problems

Activity 2. Define whether the statements are true or false

1. Mining ventilation is an important safety concern for many miners.

2. The concentration of methane and other airborne contaminants underground can generally be controlled by ventilation.

3. Gases in mines can also poison the workers or displace the oxygen in the mine, causing heat stroke.

4. Dusts can cause heart problems, including silicosis, asbestosis and pneumoconiosis

5. Air flows in several directions, making circuits through the mine such that each main work area constantly receives a supply of fresh air.

6. A ventilation system is set up to force a stream of air through the working areas of the mine.

7. The minerals are concentrated using sluices or jigs.

8. The presence of heavy equipment in confined spaces doesn’t pose any risk to miners

9. Modern mining sector of the industry is dominated by individual entrepreneurs or small business

10. Environmental issues can include erosion, formation of sinkholes, loss of biodiversity, and contamination of soil.

Activity 3. Match the equipment to its function

Activity 4. Unscramble these words and find their synonyms

Activity 5. Cross the odd word out

Activity 6. In pairs discuss the following questions

1. Why doesmining remain dangerous throughout the world?

2. What is the most important safety issue in mining?

3. What problems do dust and temperature cause?

4. What are the two sectors of mining industry?

5. What do environmental issues include?

5 MINERAL PROCESSING

Text 5

Mineral 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.