Bench height and berm width

 

 

The height of the bench is controlled by the selected loading equipment, required degree of selectivity, economics and overall design. For economic rea-sons the bench should be rather high to make drilling and blasting operation cheaper per ton of material. The loading equipment will finally determine the maximum height of the bench and also the minimum to some extent. Operating benches are generally 35 to 40 m minimum width to give sufficient working room for loading and hauling equipment. But the bench widths left behind, here called berm, are typically between 5 and 15 m. The width of the berm is designed to be as small as possible, consistent with access requirements and the ability of the berm to catch and retain falling rock. If the rock is not homogeneous, but contains structural discontinuities, local (bench) failures like plane or wedge failures might occur. These can be predicted as a result of the slope stability study and the width of the berm can be selected to keep falling debris. At the crest of the berm there shall be a safety wall to help catch falling rock and to di-rect rainwater to drain along the berm instead of into the pit. For this reason, there may be a slight inclination of the berm alongside the pit wall (about 1 %).

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What is the height of the bench controlled by?

 

b) How wide are operating benches?

 

c) What is called berm?

 

3. Переведите на английский язык следующие предложения:

 

а) Если порода содержит структурные нарушения, она не является од-нородной.

b) Местные обрушения могут быть предсказаны в результате изучения устойчивости склонов.

30

 

 

c) Барьер (safety wall) по краю бермы помогает удержать обломки по-роды и направляет дождевые воды в сторону от карьера.

 

TEST № 21

 

 

Прочитайте текст и письменно выполните задания к нему

 

 

Stripping ratio

 

 

The ratio between waste quantities and ore quantities is called stripping ra-tio. It is controlled by economic considerations and can be used to compare dif-ferent alternatives. There are three kinds of stripping ratios: the overall stripping ratio, stripping ratio during a year, the incremental stripping ratio.

The overall stripping ratio is defined as:

 

Overall stripping ratio = Total waste / Total ore.

 

The yearly stripping ratio in an operating mine varies from year to year and can be found in the annual mining plans.

The incremental stripping ratio is defined as:

 

Incremental stripping ratio = Additional waste / Additional ore.

 

Waste removal must often be performed many years before the correspond-ing ore production will be reached. Waste rock therefore means that the mining company must invest a lot of money in the mine, an investment which is hope-fully paid back later by high revenues.

To reduce interest cost and to maximize the profitability of expanding of mine, it is important to delay waste stripping as long as possible. Therefore, it is wrong to mine waste at the same time as ore mining is done at the same level in the mine. Instead, the waste volume should be split up into several push-backs. Waste rock within a new pushback should be started as late as possible to save interest costs. But the waste rock must of course be removed in such a time that ore mining at deeper and deeper benches is guaranteed.

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What is called stripping ratio?

31

 

 

b) Where can the yearly stripping ratio in an operating mine be found?

 

c) What is called incremental stripping ratio?

 

3. Переведите на английский язык следующие предложения:

 

a) Мы можем сократить расходы на выплату ссуды, если как можно позже начнем выемку пустой породы.

b) Инвестиции, вложенные в разработку рудника, впоследствии воз-вращаются в виде доходов.

 

c) Правильно ли начинать выемку пустой породы одновременно

 

с выемкой руды?

 

 

TEST № 22

 

 

Прочитайте текст и письменно выполните задания к нему

 

 

Planning and design of open pit mines. Slope angles

 

 

The planning process actually starts at the exploration phase. However, mine planning must be correlated with all phases of a mining operation. Mine planning includes ore reserve calculations, determination of rock properties and structural defects, concentrating characteristics of the ore, marketing considera-tions, capital expenditures and the cash flow of the venture and its present value. Elements are closely related and influence each other in such a way that they must be considered as a whole. If more than one deposit is be-ing mined in an area, their planning should be integrated. There are three factors guiding the geometric design of an open pit mine: slope angles, bench height and berm width, haul road design. Behind the final choice of these criteria lies an optimization of operational and economic considerations.

 

Slope angles. On purely economic grounds, a very steep overall slope is preferable, the steeper the slope the less waste rock needs to be stripped. On the other hand, for operational and safety reasons, the slope angle will have to be limited. There is a definition of several slope angles – overall slope angle, bench face angle (between the level of berm bottom and its wall) and interrupt slope angle (between the horizontal level and wall of the ramp) . It can be seen that the overall slope angle depends not only on the bench face angle but also is affected by haul road width, bench height and berm width, which are chosen according to the selected equipment. This in turn is a function of methods used and production

32

 

 

rate. In general, the bench face angle is normally 70–90°, interrupt slope angle is 53°, and the overall slope angle (or the angle of the final wall) is normally 40–60°.

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What does mine planning include?

 

b) What are the angles of the slopes?

 

c) Why is very steep overall slope preferable?

 

3. Переведите на английский язык следующие предложения:

 

а) Чем круче склон, тем меньше пустой породы надо извлечь.

 

b) Элементы планирования рудника должны рассматриваться вместе,

 

так как связаны между собой и влияют друг на друга.

 

с) Подсчеты запасов руды и определение свойств породы очень важны при планировании рудника.

 

ВОПРОСЫ ДЛЯ ПОДГОТОВКИ К ЗАЧЕТУ

 

1. What is mine development?

 

2. What does the extent and type of development work depend on?

 

3. When does a ramp have a large cross section with passing bays, niches,

 

etc.?

 

4. How are ramps used in emergencies?

 

5. How are shafts used in many large, deep mines?

 

6. What is drift? What are the functions of drifts? What is the common size of drift?

7. What is the method for transporting ore?

 

8. What does bedrock contain of? What does mining method adapt to?

 

9. What is the task of mining?

 

10 What openings connect stops and workplaces?

 

11. Why is the circular shaft often preferеd by miners?

33

 

 

12. How is core drilling made? Where and when was the core drilling first

 

used?

 

13. Why are the rock drillability and blastability very important for drilling pattern design? What is the main aim when designing a drilling pattern?

14. Where from can water flow into the underground mine? How do ground waters move down to the water basin? What is sump?

15. Why is ventilation of mine so important? What is air in mine regularly contaminated by? What are the main components of mine ventilation system?

16. What is the main idea of rock bolting? When is the rock bolting usually done? What categories of bolts do you know?

17. Since when has mechanized bolting been available?

 

18. What does mechanized equipment now handle? What equipment pro-vided now secures fixing and grouting? What advantages does LHD technology give?

19. Why is developing of mine another 400 meters down difficult? Why can we say, that the ramp constitutes for shaft?

20. What are the disadvantages (недостатки) of carrying ore on trucks?

 

21. What variables of blasting can be altered and how? How have new equipment and blasting materials changed the quality of blasting? What may be limiting factors for blasting in remote areas?

22. What is explosive? What are the requirements to the explosives, used in underground blasting? Why is drilling pattern for surface blasting not very com-plicated?

23. What is the percentage of total production of the crushed stone by open pit mining?

24. Under which circumstances is the mining operation usually con-verted from open pit to underground mining? When is open-pit mining used?

25. What is reclamation of land? What sciences do operations of reclama-tion depend on? What is water-based recreational area?

26. What is the height of the bench controlled by? How wide are operat-ing benches?

27. What is called stripping ratio? Where can the yearly stripping ratio in an operating mine be found? What is called incremental stripping ratio?

34

 

 

РЕКОМЕНДУЕМАЯ ЛИТЕРАТУРА

 

 

1. Англо-русский словарь (любое издание).

 

2. Баракова, М.Я. Английский язык для горных инженеров

 

/ М.Я. Баракова, Р.И.Журавлева. – М. : Высшая школа, 2001.

 

3. Гузеева, К.А. Английский язык : справочные материалы / К.А. Гу-зеева, Т.Г. Трошко. – М. : Просвещение, 1992.

 

4. Поуви, Д. Здравствуй и прощай : английский речевой этикет : учеб. пособие / Д. Поуви, А. Иванов. – СПб. : отделение изд-ва “Просвещение”. 1998.

5. Славина, Г.И. Аннотирование и реферирование : учеб. пособие по английскому языку / Г.И. Славина, З.С. Харьковский, Е.А. Антонова, М.А. Рыбакина. – М. : Высшая школа, 1991.