International Development of Modern Open-pit Mining Technology and Prospects of Open-pit Coal Mining in China

I. Characteristics of the development of open-pit mining technology in the world

(1) Highly centralized mining and intensive management

The world's largest open-air coal mine production reached 5060Mt / a, located in Germany, the United States, Kazakhstan and other countries; annual output of 20Mt / a opencast mine is throughout Russia, Australia, wave, the Czech Republic and other countries.

The centralized share of coal production and market sales by large enterprise groups is another important trend in the centralized development of mining. In 2000, the top ten international coal companies controlled the annual output of 850 million tons of coal.

(2) Diversification of mining technology

The technical development trends of contemporary open pit mining processes are:

1. The equipment is large and the mining is centralized. Practice has proved that the use of large-scale mining equipment can significantly improve mine output and economic benefits. For example, the iconic package specifications for single bucket shovel and trucks will be updated every 15 to 20 years. At present, the single bucket electric shovel bucket has a volume of 76.5m 3 , and its loading weight exceeds 100t; the matching truck has a weight of 363t. The production capacity of a single open pit mine has exceeded 60 Mt/a.

2. Continuation of the mining process. The most representative full-continuous process is the wheel shovel mining - belt conveyor transport - earthmoving machine dumping, which can achieve high efficiency and low cost. However, due to factors such as the nature of the ore, the application range of the continuous process is limited. In the past 40 to 50 years, the open-pit mine semi-continuous process has been more and more widely used to adapt to local burial conditions. Representative semi-continuous processes include: single bucket shovel mining - (face truck transport) - a mobile crusher (movable crusher) - a tape transport system; bucket excavator mining a truck transport system.

3. The merging of production links and the simplification of mining processes. The basic production links of open pit mining include loading, transportation and dumping. When the conditions are appropriate, some mining equipment can be used to realize the merger of two or even three production steps to simplify the mining process and greatly reduce the mining cost. The giant bucket shovel is a typical combined process; the scraper stripping process is another type of combined process.

4. Integration of mining technology. With the trend of centralized mining, the mining area of ​​a single open pit mine tends to expand, the mining depth is increasing, and the conditions for occurrence of ore in the mining boundary are often complex and variable. In response to this situation, the traditional single mining process often cannot adapt to it, which reduces the mining efficiency and increases the mining cost. In recent years, the comprehensive application of multiple mining processes has become a development model for large-scale open-pit mining.

China's Zhungeer mining area black gully open pit mine surface soil stripping using a bucket excavator one tape system, hard rock stripping will soon adopt the giant drag shovel dumping process, coal mining using a single bucket shovel a truck half fixed broken one tape transport process In addition, a part of the single bucket shovel truck is used for the stripping of the remaining hard rock. This is a typical integrated process system. Various processes are adapted to local conditions and exert their strengths. It is expected to achieve good comprehensive economic benefits.

(3) Computerization of enterprise management and construction of intelligent mines

With the rapid development of computer technology, computers have been widely used in many fields of open-pit mining. From mineral exploration and geological model establishment to mine design planning, from mining area and mine production management to equipment failure monitoring, computers have become indispensable tools for cutting tools. .

(4) Make rational use of resources, rebuild the ecological environment, and maintain sustainable development

For mine environmental protection, such as reclaiming land, three waste treatment, landslide prevention, coal spontaneous combustion prevention, etc., many new technical problems have been raised. Reasonable and full use of mineral resources to achieve sustainable development of the mining industry, involving the long-term interests of future generations, has been widely concerned by all countries.

Second, a brief review of the history of open coal mining in China

(1) The first stage

In the 1950s and 1960s, China built a number of open-pit mining backbone mines with the assistance of the former Soviet Union. The production capacity of Fushun and Haizhou mines is above 3Mt/a. The annual production capacity of the national open-pit coal mine is more than 20 million tons. Opencast mining technology in this stage, a single bucket iron-based channel technology, production of more than 90% complete. Large open pit mines use 3~4m 3 single bucket electric shovel to load to standard gauge (1435mm) trains; small open pit mines use 1m 3 electric shovel to load narrow gauge (900mm or less) mines, only individual mines use trucks. transport. The adhesion quality of the quasi-rail locomotive is 80-150t, and the self-turning vehicle weighs 50~60t.

(2) The second stage

After the reform and opening up in the 1970s, China decided to develop five open-pit coal mines, namely Antaibao, Heiqigou, Huolinhe, Yiminhe and Yuanbaoshan open pit mines. Its total designed production capacity is 52Mt/a. From the 80s to the 90s, the five open-airs have been completed and handed over.

At this stage, the open pit mining process has also undergone major changes. Truck transportation has gradually replaced rail transportation. In 1991, 58% of coal and 43% of strippings were shipped out of trucks in 14 state-owned open pit mines. As the scale of new mine production has increased year by year, this proportion continues to expand, and truck transportation has now dominated.

At this stage, the specifications of mining equipment continue to increase. The equipment for the single bucket and one truck process is roughly:

3~4m 3 electric shovel +20~30t truck

8~14m 3 electric shovel +68~108t truck

23~35m 3 electric shovel +154~172t truck

23~35m 3 electric shovel +154~172t truck

At the same time, continuous mining processes and semi-continuous mining processes have been developed. In the Xiaolongtan and Heiqigou open-pit mines, a full continuous stripping process using a wheel shovel to extract a belt to transport a row of earthmoving machines is adopted. In the Huolin River and Fushun West Open-pit Mines, a single bucket shovel is used to mine a truck, a pit crusher, and a coal mining process for tape transportation.

The structure of China's open pit coal mine at the end of 1989 is shown in Table 1.

(III) The third stage: the new upsurge of open-pit mining in China is on the rise

1, the background

(1) The international oil supply is tight, oil prices have risen sharply. China's energy is facing tension, and the coal-based energy structure will continue for many years.

(2) Among the existing reserves of coal available in China, the reserves of the mine are quite tight. According to the recent annual output, due to the low recovery rate of the mine, the reserves reserve factor is high and can only be maintained for 20 to 3 years; the exposed reserves can be Maintained for more than 100 years.

(3) The introduction of modern mining new technologies and new technologies has greatly reduced the cost of open-pit mining in areas with suitable conditions, and greatly improved labor productivity and achieved significant economic benefits. For example: dragging shovel dumping, throwing blasting technology, the use of high-strength semi-continuous mining equipment, and so on.

(4) Coordinated development and diversified operation of coal, electricity and transportation, opening up a vast market for coal with huge demand for electricity.

(5) The adjustment of the coal industry structure, the closure of a large number of township coal mines, in order to achieve the centralized mining of advantageous resources, large-scale operation and the full and effective use of limited resources to clear the artificial obstacles.

2. Since the beginning of the 21st century, several important changes have taken place in China's open pit mines.

In recent years, under the stimulation of the seller's market, production mines have increased their production, turning losses into profits, and mines that have not reached the designed output for many years have quickly achieved production. The development of Heipougou, Anjialing and Huolinhenan open pit mines is particularly gratifying.

The production mines will be rebuilt and expanded on the basis of high production and high efficiency, and advanced technologies and technologies will be introduced to further improve economic efficiency. For example, the black shovel introduced a giant dragline shovel, supplemented by throwing blasting, and carried out the reverse stacking, and increased the original production capacity of 12Mt/a to 20Mt/a; the Xiaolongtan open-pit mine was technically modified, and the annual output was 4.8Mt/ a increase to 13Mt / a in one fell swoop; Yimin River open pit mine expansion capacity will reach 21Mt / a.

A number of new mines have been established or have been started. The Anjialing open pit mine started construction in 1997 has been completed; the design output of Shengli No. 1 open pit mine is 20Mt/a, and the stripping project is carried out by dragging and dumping and moving crushing semi-continuous process; the design output of Harwusu open pit mine is 20Mt/ a, using the bucket shovel to reverse the pile, 56m' grade electric shovel + 300t and above trucks for stripping; Baiyinhua open pit mine design output 15MVa, using the mobile crushing semi-continuous process for stripping and so on.

Third, China's open pit mining development prospects and recommendations

(1) Development prospects

The new high tide of open coal mining in China is coming. The new high-altitude indicator of open-pit mining is: using modern advanced mining technology and technology, carrying out highly centralized mining, making full use of the engineering contracting system to quickly build open-pit mines.

It is expected that China's open pit mine is expected to reach the annual production capacity of 100 million tons of coal in the year. In 2010, it will break through the total production scale of 200 million tons of raw coal per year. The total production capacity of the national open pit mine will reach 500-700 million tons. The development prospects are quite optimistic.

(2) Suggestions on development ideas

1. Adhere to the centralized mining of superior coal resources and realize the economic benefits of large-scale production; implement the large group business strategy and achieve highly intensive operations.

2. Depending on local conditions, boldly adopt various effective mining techniques that are effective in order to achieve highly centralized mining in superior coal fields and achieve high economic benefits.

(1) Expand the application range of the bucket shovel and the stripping shovel, and strengthen the use of the bucket shovel, supplemented by the powerful cooperation of the throwing blasting and the large bulldozer.

(2) Large-scale mining equipment is an inevitable requirement for centralized mining of advantageous resources, and an important way to simplify stripping and mining projects and reduce mining costs and improve economic benefits.

At present, the mainstream equipment series of international large-scale mines are:

Single bucket electric shovel: bucket capacity 40 ~ 60m 3

Dump truck: load capacity 280 ~ 360t

(3) The use of semi-continuous mining technology for open pit mining and mining projects is an international development trend. The emergence of large-scale mobile crushers has created conditions for the advanced semi-continuous process of transporting a row of earthmoving machines by a mobile-crushing belt conveyor. Its promotion and application is expected to greatly reduce the stripping cost, simplify the stripping process and save fuel consumption.

(4) The choice of stripping process is expensive. For large-scale mines with a wide range of capabilities and large capacity, different mining techniques, different mining methods, and integrated processes to achieve optimized mining results have become the development trend of modern mines.

3. Relevant systems, norms and systems should be adapted to the requirements of the new situation, revised and improved, in order to continuously promote the rapid development of open pit mining.

4. Accelerating the construction of open pit mines through project contracting is an important experience in the construction of open pit mines in China in recent years. This measure needs to be further developed to make it more flexible to use, to get faster and better mine construction results.

5. The mine design work should be advanced and forward-looking. The design results should fully reflect the progress of modern mining science and technology and management; the design thinking should be forward-looking, anticipate the possible technological development direction, and avoid falling behind the times when the mine is built.

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