Explosives and ignition

 

 

An explosive is a chemical compound that can be ignited by thermal or mechanical means and, once ignited, decomposes rapidly in a detonation. On

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detonation, an explosive suddenly releases an enormous amount of heat and pressurized gases, which expand rapidly and powerfully in the rock. The explo-sive energy leads not only to rock fragmentation and to displacement, but also produces ground vibration and air blast.

Surface blasting in quarries offer sufficient free space for the blast to ex-pand freely and the drilling patterns are therefore not very complicated. Blasting typically advances in more or less straight rows. In underground drifting, only one free surface is normally available for the blasted rock to expand. This means that the blast must be strong enough to throw the rock forward, sufficiently well controlled to prevent any excessive cracking and breaking of the surrounding rocks. Special explosives are often used to ensure the smooth blasting of holes closest to the walls and roof. Shaft sinking and traditional raise driving are spe-cial and even more restricted cases of blasting.

 

The explosives used in underground excavation must be easy to store, safe and non-toxic as possible. Blasting is often performed immediately or within a couple of hours of the holes being charged, so the explosives, which are left in holes, must still be effective, water resistant and stable.

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What is explosive?

 

b) What are the requirements to the explosives, used in underground blast-

 

ing?

 

c) Why is not drilling pattern for surface blasting very complicated?

 

3. Переведите на английский язык следующие предложения:

 

a) Кроме смещения породы и раздробления ее на куски, взрывание производит вибрацию грунта и взрывную волну.

b) Подземное взрывание должно тщательно контролироваться, чтобы предотвратить чрезмерное растрескивание и разрушение окружающей по-роды.

c) При подземных взрывных работах необходима хорошая вентиляция для удаления токсичного дыма.

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Варианты контрольной работы для студентов специальности 130403 "Открытые горные работы" (№№ 18–22)

 

TEST 18

 

 

Прочитайте текст и письменно выполните задания к нему.

 

 

Open-cast (open pit) mining

 

 

Open-cast mining is the process of surface mining in which large quantities of mineral-bearing rock are scooped out to produce, in effect, a very large hole, with terraced sides. The largest, in Bingham Canyon, USA, is 1.5x1.6 miles x 0.5 mile deep.

Two basic types of open-cast mining are quarrying, in which the rock is cut unto large blocks and usually transported away from the site in this form, and metal mining, where the large quantities of rock are ground to the powder on site and the metal-bearing minerals are removed. In this way, large quantities of poor ores may be processed in order to obtain relatively small amounts of the valuable minerals. This method also leaves a very large amount of useless ground-up rock.

Open-cast mining is used for the recovery of deposits, which are situated close to the earth surface and have the gentle dipping. It is generally considered that open pit mining is more advantageous than underground mining in:

• (higher) productivity of labor;

 

• (greater) production;

 

• (lower) cost of mining;

 

• (better) recovery;

 

• (better) grade control;

 

• (better) flexibility of operation;

 

• (better) safety;

 

• (better) working environment.

 

When mineralization in an open pit mine extends to a greater depth, the rapidly increasing amount of overburden imposes economic limits beyond which mining must be abandoned. Under such circumstance, the mining op-eration is usually converted from open pit to underground mining.

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The estimated percentage of the total ore production from open pit opera-tion in Western World are: crushed stone – 96 %, iron ore – 80 % ,copper ore – 70 %, hard coal – 50 % The above figures indicate that open pit mining is very important in mining industry.

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What is the percentage of total production of the crushed stone by open pit mining?

b) Under which circumstances is the mining operation usually converted from open pit to underground mining?

c) When is open-cast mining used?

 

3. Перевести на английский язык следующие предложения:

 

a) Существуют два основных вида открытой разработки – добыча ру-ды в карьере и разработка рудоносных пород.

b) Если оруденение уходит на большую глубину, открытые горные работы трансформируются в подземную разработку.

c) Открытая разработка месторождения имеет много преимуществ по сравнению с подземной разработкой.

 

TEST № 19

 

 

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Reclamation

 

 

Open pit mining is a temporal use of the land surface. The time span of mining can be very short as in road building or very long as in some of the mas-sive open pits for copper. During the mining process there will be a time when mining ceases. Usually good mine design and good mining practice require that attention be paid to the post-mining use of the land formerly used by a mine. Reclamation is defined as those operations that prepare mined land for post-mining use. Reclamation also includes those steps that stabilize mined land in its environment. Reclamation is not a single step supplementing mining, rather it

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is a series of integrated operations that begins with initial mine planning, continues through the extraction phase, and does not end until the new, post-mining land use begins.

The operations of reclamation depend upon applied scientific disciplines that make up the environmental sciences. They include soil mechanics for ground stability, soil science for soil productivity, hydrology and hydrogeology for surface and ground water flows, agronomy for revegetation, ecology for baseline studies, and the social sciences for land-use planning. Technical re-quirements of reclamation will vary depending upon the degree of needed res-toration and the way, which the reclaimed area will be used in. For example, the pit may be filled by the waste rock then the removed and stored topsoil is re-turned back and revegetated, so the area can get recreational use as park and golf field. Otherwise, the pit may be filled with ground waters forming the small lake and the area then may be turn into water-based recreational area.

 

Задания

 

 

1. Переведите текст на русский язык.

 

2. Ответьте на вопросы к тексту:

 

a) What is reclamation of land?

 

b) What sciences do operations of reclamation depend on?

 

c) What is water-based recreational area?

 

3. Переведите на английский язык следующие предложения:

 

a)  Открытые горные разработки не постоянный  (constant),

 

а временный способ землепользования.

 

b) Технические требования рекультивации зависят от необходимой степени восстановления земли и способа ее использования.

 

c) Отработанный карьер заполняется породой, затем сохраненной почвой (soil) и засевается травой.

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TEST № 20

 

 

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