ТЕКСТА General Information on Mining

As has been said, mining refers to actual ore extraction. Broadly speaking, mining is the industrial process of removing a mineral-bearing substance from the place of its natural occurrence in the Earth's crust. The term "mining" includes the recovery of oil and gas from wells; metal, non-metallic minerals, coal, peat, oil shale and other hydrocarbons from the earth. In other words, the wo± done to extract mineral, or to prepare for its extraction is called mining.

The tendency in mining has been towards the increased use of mining machinery so that modern mines are characterized by tremen­dous capacities. This has contributed to: 1) improving working conditions and raising labour productivity; 2) the exploitation of lower-grade metal-bearing substances and 3) the building of mines of great dimensions.

Mining can be done either as a surface operation (quarries, opencasts or open pits) or by an underground method. The mode of occurrence of the sought-for metallic substance governs to a large degree the type of mining that is practised. The problem of depth also affects the mining method. If the rock containing the metallic substance is at a shallow site and is massive, it may be economically excavated by a pit or quarry-like opening on the surface. If the metal-bearing mass is tabular, as a bed or vein, and goes to a great distance beneath the surface, then it will be worked by some method of underground mining.

Working or exploiting the deposit means the extraction of mineral. With this point in view a number of underground workings is driven in barren (waste) rock and in mineral. Mine workings vary in shape, dimensions, location and function.

Depending on their function mine workings are described as explo­ratory, if they are driven with a view to finding or proving mineral, and as productive if they are used for the immediate extraction of useful mi­neral. Productive mining can be divided into capital investment work, development work, and face or production work. Investment work aims at ensuring access to the deposit from the surface. Development work pre­pares for the face work, and mineral is extracted (or produced) in bulk.

The rock surfaces at the sides of workings are called the sides, or hi coal, the ribs. The surface above the workings is the roof in coal mining while in metal mining it is called the back. The surface below is called the floor.

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The factors such as function, direct access to the surface, driv­ing in mineral or in barren rock can be used for classifying mine workings:

I. Underground workings:

a) Long or deep by comparison with their cross-section may
be: 1) vertical (shaft, blind pit); 2) sloping (slopes, sloping drifts,
inclines); 3) horizontal (drifts, levels, drives, gate roads, adits,
crosscuts).

b) Large openings having cross dimensions comparable with
their length.

c) Production faces, whose dimensions depend on the thick­
ness of the deposit being worked, and on the method of mining it.

II. Opencasts.

УПРАЖНЕНИЯ

8. Укажите, какие предложения соответствуют содержанию текста. Под­твердите свои ответы фактами из текста.

1. As a rule, the term "mining" includes the recovery of oil and
gas from wells as well as coal, iron ores and other useful minerals
from the earth.

2. The increased use of mining machinery has greatly contributed
to raising labour productivity and improving working conditions.

3. It is quite obvious that the problem of depth is not always
taken into consideration in choosing the mining method.

4. Productive workings are usually used for the immediate ex­
traction of useful mineral.

5. Underground workings are driven in barren rock or in mineral.

6. A shaft is a vertical underground working which is long and
deep in comparison with its cross-section.

7. The surface above the mine working is usually called the floor.

8. The rock surfaces at the sides of mine workings arc called the ribs.

9. Ответьте на следующие вопросы:

1. What is mining?

2. What has contributed to the better working conditions of the
miners?

3. What factors influence the choice of the mining method?

4. In what case is useful mineral worked by open pits?

5. Are exploratory workings driven with a view to finding and proving
mineral or are they driven for immediate extraction of mineral?

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