Volume proportion value developments entities cost-cutting

1. Mergers and acquisitions have been made, in order to create larger, more cost-effective and financially stronger…

2. In terms of … and … of output, it is still much alive and kicking.

3. … mined underground equates with some 16% of the total volume of ores extracted.

4. Technical … resulting in more deeply penetrating exploration methods, increase the probability of finding new, richer, deeper ore deposits.

5. Intensive ... ... is now standard in all companies.

4. Give answers to the following questions:

1) What economic factor is now standard in all companies?

2) What is mining about?

3) What’s the difference between underground and open pit mining?

4) How much ore is produced globally each year?

5) What country is the most important in underground ore production?

5. Quоte the sentences in which these words and word combinations are used:

… to grow steadily, to make it possible, to have an impact, a tough fight, in terms of, on the other hand, at the other extreme, to come from, to become depleted.

6. Tell what you know about:

1) economic situation in world mining industry

2) improving productivity

3) underground mining

4) production distribution

5) future growth of world mining industry

Mining in Flat Orebodies

Nearly Horizontal Extraction

Variations on room-and-pillar and longwall mining techniques have always been attractive propositions for mechanization, because of the near horizontality of such systems. Until recently, trackless equipment was limited to a minimum working headroom of 2 m or more. However, major developments in Polish copper mines and in gold and platinum mines in South Africa have spawned a new generation of thin-seam and narrow mining equipment from Atlas Copco that can work in substantially less space than previously thought possible. The Rocket Boomer S1 L, for instance, has a tramming height of just 1.3m, yet can cover a face area of up to 29 sq m. Likewise, the Wagner ST 600LP, or Ratel, equipped with video cameras to assist the driver, has a height of only 1.56 m, but still carries a 6 t payload. Availability of such machines is already revolutionizing the design approach to mining flat orebodies.

Room and Pillar

Room and pillar is designed for mining of flat, bedded deposits, of limited thickness. Examples are sedi­mentary deposits, like copper shale, limestone or sandstone containing lead, coal seams, salt and potash Wets, limestone and dolomite.

The method recovers the mineralization in open stopes, leaving pillars of ore to support the hanging wall. To recover maximum ore. miners aim to leave the smallest possible pillars. The roof must remain intact, and rockbolts are used as rock reinforcement.

Rooms and pillars are normally arranged in regular patterns, and can be designed with circular pillars, square pillars, or elongated walls, separating the rooms.

Classic room and pillar applies to flat, bedded deposits with moderate to large thickness, also to inclined deposits with larger thickness. Mining the orebody creates large open stopes, where trackless machines can travel on the flat floor. Orebodies with large vertical height are mined in horizontal slices, starting at the top and benching down in steps.

Post room and pillar applies to inclined orebodies, of dip angle from 20 to 55 degrees, with large vertical height, where mined out space is back-filled. The fill keeps the rock mass stable, and serves as the work platform while mining the next ore slice.

Step room and pillar is an adaptation of trackless minjng to orebodies with too steep a dip for rubber-tyred vehicles. Haulage drifts and stopes are angled across the dip, to create work areas with level floors, off which trackless equipment can work. mining advances downward, along the step room angle.

Date: 2015-12-24; view: 686