Generals

Metal mining methods are more varied than those for coal, due to the greater diversity in form and occurrence of metalliferous deposits. As coal seams are "beds", i. e. stratified deposits, they are generally mined like bedded deposits. A distinction is sometimes made between the methods of mining anthracite and bituminous coals, but for a given case the proper method depends much less on the kind of coal than on the physical characteristics of the seam, roof and floor. Standard underground methods with their modifications fall into two groups: pillar methods known as room-and-pillar (nearly all coal in the USA is mined by room-and-pillar systems) and long-wall methods, divided into advancing and retreating long-wall.

In coal mining development openings corres­ponding to the levels and drifts in metal mines are locally called entries, headings and roads (bituminous mines of the USA) or gangways (anthracite mines). Openings for ventilation are termed airways or air courses, also monkeys or monkey ways in anthracite mines.

The mode of entry, drifts, or vertical or inclined shafts (slopes) depends primary on the conditions governing the development of any deposit, viz.: topography, together with the pitch and physical characteristics of the seam.

Purposes of systematic development are: a) to provide openings for stopping and transporting the excavated material; b) to obtain further and more detailed information as to character and size of deposit. Relative importance of these functions depends on type and size of deposit; the second is more important during early stages of development and in ere-bodies of irregular shape.

Modes of entry for pitching seams are: a vertical shaft, started in hanging wall; a footwall vertical shaft; a footwall inclined shaft or an inclined shaft in the seam. Except in the last case, crosscuts are necessary at intervals to reach the seam. A vertical shaft is the correct mode of entry for flat or vertical deposits lying under flat topography. In moun­tainous regions, entry to some deposits may sometimes be made by crosscut tunnels or drift tunnels. It is common to find two or more openings of the same or different kinds on a single seam.

Inclined shafts for large tonnages must be straight. Gradual changes in dip are allowable, but they increase hoisting cost and decrease shaft ' capacity by limiting hoisting speed. A straight incline cannot be sunk in a deposit of irregular dip; at some point it must extend into rock. In such deposits the footwall location is generally preferable for large shaft capacity. In fairly regular deposits large outputs can be handled through shafts in either location.

A typical example requiring a decision between the two kinds of shaft arises in case of a pitching seam. Either location of a vertical shaft requires more crosscutting than the inclined shaft and from this standpoint the inclined shaft has an advantage which varies with dip of seam and with depth, Vertical shafts cost more or less per foot than inclined shaft, according to local conditions and the way in which ground breaks. To reach a given level, a vertical shaft requires less hoisting rope, piping, wiring and support material than an incline. Hoisting in vertical shaft is generally cheaper than in inclined shafts-because hoisting distance from a given level is less.

Task 1. Which of these translations of the sentences are correct.

1. The mode of entry, drifts, or vertical or inclined shafts (slopes) depends primary on the conditions governing the development of any deposit.

1. Спосіб входу, нахиленої виробки, чи вертикального чи нахилено шахтного стволу (нахилена виробка), залежить, в основному від керування розробкою яких би то не було покладів.

2. Спосіб розробки, нахиленої виробки, чи вертикального чи нахилено шахтного стволу (нахилена виробка), залежить, в основному від керування розробкою яких би то не було покладів.

3. Спосіб входу, нахиленої виробки, чи вертикального чи нахилено штреку (нахилена виробка), залежить, в основному від керування розробкою яких би то не було покладів.

2. Except in the last case, crosscuts are necessary at intervals to reach the seam.

1. Не зважаючи на останній випадок, квершлаги необхідні на певному інтервалі до пласта.

2. Не зважаючи на останній випадок, квершлаги необхідно застосовувати на певній відстані щоб досягти пласта.

3. Не зважаючи на останній випадок, квершлаги застосовують на певній відстані щоб досягти пласта.

3. It is common to find two or more openings of the same or different kinds on a single seam.

1. Загально вживано знайти два або більше однакових отворів чи різних на одному пласті.

b) Загально вживано знайти два або більше однакових отворів чи різних на одному пласті.

c) Звичайно роблять два або більше однакових отворів чи різних на одному пласті.

4. A straight incline cannot be sunk in a deposit of irregular dip; at some point it must extend into rock.

1. Прямий уклін не можна пройти у покладах нестандартного уклону; у деяких точках він має розширюватися.

2. Рівний уклін не можна пройти у покладах неправильного уклону; у деяких точках він має розширюватися.

3. Прямий уклін не можна пройти у покладах нестандартного уклону; у деяких точках він має розширюватися в породу.

Task 2. Put different kinds of questions to the sentence.

Standard underground methods with their modifications fall into two groups.

Task 3. Finish the sentences.

1) A distinction is sometimes made between the methods of mining anthracite and bituminous coals, but for a given case the proper method depends much less on …

2) To reach a given level, a vertical shaft requires less hoisting rope, piping,…

3) Openings for ventilation are termed airways or air courses, also monkeys or …

4) Relative importance of these functions depends on type and size of deposit; the second is more important during …

Task 4. Put the verbs in the brackets in the right form.

1. Vertical shafts (cost ) more or less per foot than inclined shaft. 2. Either location of a vertical shaft (require) more crosscutting than the inclined shaft. 3. In moun­tainous regions, entry to some deposits may sometimes (to be make) by crosscut tunnels or drift tunnels. 4. Inclined shafts for large tonnages (must to be) straight.

LESSON 4