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31. П ереведите предложения, обращ ая вним ание на разны е значения и функции глаголовto be и to have:

1.The various methods of mining involve production faces which are either long (longwall) or short (shortwall) or room- and-pillar.

2.Until mining machines were developed, short faces predomi

nated.

3.The aim was to reduce the volume of development work by using the longwall method.

4.Some disadvantages of shortwall work are a considerable loss of mineral which may reach and exceed 40 per cent, and the dif ficulty of ventilation.

5.In gassy mines each face with its development workings has to be ventilated with its own air current.

6.Cutter-loaders are being widely applied underground now because these machines are the most progressive means for mecha nising coal winning.

7.It is necessary to study all the factors which influence the choice of the mining method.

8.There are special methods of extracting seams which are close together (сближенные).

9.The shield method of mining has to be introduced in thick seams, dipping at an angle of not less than 55-60", with regular occurrence and hard coal.

10.They have to introduce new mining equipment as soon as possible.

32. Переведите предложения, обращ ая внимание на разны е способы вы ражения отрицания:

1.As the longwall method permits an almost 100 per cent re covery of coal, all the seam is extracted and there is no coal left in the form of pillars, except the shaft pillar.

2.No fissures were found.

3.We do not use the room-and-pillar method on a wide scale because it is characterized by high losses of coal.

4.Nothing was said about special ways of extracting thick

seams.

5.In manless faces no men operate the machines, you can see nobody in such faces as all the processes are fully automated.

A level is a horizontal road with no direct access to the sur6.

face.

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33. Выразвте несогласие • подтвердите свою точку зрения фактами из текста Б, используя следующие разговорные формулы:

OD the contrary; to my mind; In my opinion; as far as I know; as Is known; I'd like to stress that; I'd like to say that; let us consider

1.We say that the method of mining is rational if it guarantees only safety of the men and maximum output of mineral.

2.It is rather difficult to define which method of m ining (longwall or shortwall) is more often used in Russia.

3.The shield method of mining is used where short faces are worked. It is used in all the coal-fields of Russia.

4.The problem of extracting thick seams is not difficult.aAs rule, such seams are not extracted to full thickness.

5.In applying hydraulic mining powerful cutter-loaders win coal and transport it to the surface.

34. Суммируйте содержание текста Б. При этом ответьте на следующие вопросы:

1.W hat does the method of mining mineral deposits under ground involve?

2.What main requirements should mining methods satisfy?

3.What types of production faces do the methods of mining in clude?

4.What can you say about their application in different coalproducing countries?

5.What methods of mining are practised in the Kuznetsk coal

field?

35. Расскажите вашим друзьям о посещении шахты по следующему плану, используя слова в скобках:

1.The Location of the Mine, Its Geological Conditions(folds, faults, disturbances, depth, seams, thick, sloping, steep, inclined)Try to . explain why underground mining is used there.

2.The Type of the Deposit(tabular, bedded, vein).

3.The Method of Mining(longwall, room-and-pillar).

4.Mine W orkings, Their Functions(vertical, horizontal, in clined).

5.Average Output(annual, daily).

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UnltS

36.Прочитайте заголовок и аннотацию к тексту В и скажите, о чем гово рится в тексте В.

37.Прочитайте текст и скажите, как ведется борьба с метаном на шах тах Карагандинского угольного бассейна.

Слова для понимания текста:

goaf — завал; обрушенное пространство

double-ended drum bearer — комбайн с двойным барабаном

ТЕКСТ В

M ining Thick Seam s

Longwall retreating is one of the primary methods of mining in many coal mining areas. There is a high degree of mechanization, and mine safety is receiving an increasing amount of emphasis.

Thick seam coal mining is important in Russia. Many high-qual- ity coal seams exceed 35 metres (12 feet) in thickness — the normally accepted classification for a thick seam (although this varies in different countries). Some of these thick seams are of key importance in major mining basins. Seam thickness is the most significant factor which is taken into account in mining practice. The increasing strata movement with increasing seam thickness requires not only specialized extraction techniques, but also highly specialized ground control and support methods. This is certainly true of the coal basins where coal seams are gassy and the majority of coal is liable to spontaneous combustion. Coal seams occur at a depth of between 350 and 710 metres (1,150 and 2,330 feet).

Longwall retreating is the primary method of mining at the collieries with more than 98 per cent of the total output. Application of a mining method with the coal face being advanced down the dip is steadily expanding; shortwall pillar extraction with power loaders is being successfully employed.

Coal faces and development headings are equipped with instruments for automatic gas protection and centralized telemonitoring of methane content. Data on gas conditions in development headings which are particularly dangerous from the viewpoint of methane content, and in all coal faces are transmitted to the mine dispatcher's control panel. In order to reduce gas content in mine workings, extensive use is made of preliminary gas drainage of the coal seams, gas drainage of roofs to be caved and also of the goaf.

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The main trend in mine transport is towards high-capacity automatic conveyer systems. In underground workings transport of men and materials is by high-capacity electric locomotives; in incline roadways, by ropeways, floor-mounted haulage and up-to- date hoisting installations.

The mining district is usually developed by mine shafts. The mining method is longwall retreating along the strike and down the dip. The mining area is divided into two blocks east and west. In the eastern block, the panels are mined down the dip, in the western block, mining takes place along the strike. The faces are 200 metres long and operate along the strike of the seam. Sandstone forms the immediate roof and floor of the seam. Each face is mining a 3.5-metre thick section of coal, and a 0.5 to 0.8 metre thick pillar (band) of coal is left between two panels to form the roof of the lower face.

Each face is equipped with a double-ended dram shearer. The drams are 1.8 metres in diameter and a 0.6-metre web of coal. The leading dram cuts the top section of the face, and the trailing dram cuts the bottom section. Water jets are fitted to the drams for dust suppression. Coal passes along the face on the armoured face conveyer to the crasher installed at the main gate end of the conveyer, which reduces the size of the coal before it is delivered to a beam stage loader in the main gate.

The faces are operated on two production shifts and one maintenance shift per day.

Each face is supported by shield supports.

It should be stressed that special attention is paid to underground methane drainage. The methane is pumped through pipes first to the tail gate and then through the mine gate to the upcast shafts and then to the surface, where it is used for heating. Two sensors for continuously monitoring the emission of CH4 are situated in the top panel, one in the main gate, and the other in the tail gate. These are placed 20 metres in front of the face. The control room at the mine's surface automatically monitors and records CH4 emissions throughout the mine.

In coal face and development operations, use is made of current forecasting of the liability to sudden outbursts, that is establishing dangerous and non-dangerous zones.

All coal faces are equipped with mechanized complexes, comprising power loaders. In underground haulage roadways, use is made of high-capacity belt and apron conveyers. Coal is hoisted to the surface through two skip shafts. Monorails are widely used on levels for transport of materials and equipment to coal faces and

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energy. This broad definition includes the energy minerals such as coal, petroleum and natural gas; refined or processed metals such as copper, steel and the ferroalloys; and nonminerals such as diamonds, phosphate and potash. A much narrower definition of mining includes only crude or nonprocessed mine products, such as mineral ores and coal, and excludes petroleum and natural gas. We deal mainly with the major metals from the exploration and mining stages to the processing stage from which they are normally marketed for use in manufacturing.

The production of useful minerals involves several stages that are generally carried on by large mining firms, although small mining operations may engage in the initial stage. The first stage is exploration of areas identified by geological reports as possessing potential mineral resources. Modern exploration methods are quite sophisticated and include geological, geochemical and geophysical investigation; three-dimensional sampling by core drilling or other methods; laboratory analyses, including ore treatment, concentration, and recovery tests; and economic appraisal. The objective is to discover and evaluate an orebody that can be economically exploited.

Geochemical exploration is used to measure the chemical properties of the area surrounding the deposit in order to delineate abnormal chemical patterns that may be related to potentially economic mineral deposits. Geophysical investigations employ electronic equipment that can detect contrasts in such physical properties as specific gravity, electrical conductivity, heat conductivity, seismic velocity and magnetic susceptibility. Where much of the bedrock is concealed, telegeologic or remote sensing techniques measure various geologic properties from aircraft or satellites. Exploration is commonly carried on by teams of specialists that include geologists, geochemists and geophysicists. There are different levels of exploration beginning with regional geologic mapping of areas up to 50,000 square km (20,000 square miles) and ending with intensive investigations of orebodies by means of numerous drillings to obtain bulk samples which are then metallurgically tested to determine the dimensions and character of the orebody.

If the results of exploration activities suggest that an economical deposit has been found, the second stage involves engineering and economic evaluations of the mining project. It is on the basis of this study that companies decide whether to go ahead with a mining project; the study may also be reviewed by prospective

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lenders. The feasibility study for a large mining project may be quite costly, running to $25 million or more in some cases. The total cost of exploration and the feasibility study for a large mine may run to $50 million or more. It is uncertain whether a profitable mine will be constructed until all the stages have been completed. In the initial exploration stage, several million dollars may be spent with less than a 10 per cent chance of a successful outcome.

The third stage is the construction of the mine, the metallurgical plant, and infrastructure. There are two basic types of operations to extract mineral ores: open-pit or surface mining, and underground mining. An open-pit mine is largely a quarrying operation that handles a large volume of material. Such mining involves drilling and blasting the ore and hauling it out of the pit in large trucks with capacities ranging up to 200 tons, or in ore trains. The ore is hauled to crushers and then to the metallurgical plant. In underground mining, shafts are dug into ore deposits below the surface, from which ore is drilled, blasted and removed through underground passages to the surface. Iron, bauxite and copper ores are extracted by means of open-pit mining, while lead, zinc, silver and gold are largely extracted by underground mining. There are also some underground copper mines. Economies of scale in open-pit mining permit the mining of relatively low-grade ores. As much as 100,000 tons of ore per day containing less than 1 per cent metal are extracted in the larger open-pit operations. Higher ore grades are necessary for underground mining to be profitable.

One recent advance in mining and processing of lower-grade ores is in situ mining. In situ mining may be defined as the extraction of metals from ores located within a mine (broken or fractured ore, caved material, slag heaps, etc.). These materials represent an enormous potential source of all types of metals.

Large mines involve huge capital outlays running to a billion dollars or more. The mining complexes usually include concentration of ores for production of concentrates with 25 per cent or higher metal content. In the case of copper, large mine complexes include plants for smelting copper or for producing copper metal by hydrometallurgical methods, but in the case of other metals such as gold, lead, zinc, tin and iron, metal is produced in separate plants which may or may not be owned by the mining company. The degree of processing that usually takes place at the mine differs widely among metals, but refining the product for market-

ing to fabricators nearly always takes place in separate plants that refine the products of several mines.

As is known, modern methods of processing are dense medium separation, jigging and froth floatation. Operations prior to coal preparation include: blending, screening, crushing, dewatering and others. The aim is to get clean coal for metallurgical plants, etc.

Since mines tend to be located far away from developed areas, infrastructure is often a substantial proportion of capital cost. It is frequently necessary to provide sources of power and water, as well as highways, railroads and port facilities. In addition the mining company may be responsible for constructing living quarters for workers and their families and for providing education and other public services required by the mining community.

SCOPE OF MINING ACTIVITIES

На обсуждение вы носятся следую щ ие вопросы :

1.Using the scheme above speak about the main divisions of mining activities. What are they?

2.What definition can you give to mining in general?

3.You are a geologist. What can you say about the main objec tives of 1) exploration; 2) evaluation?