What Is an Open Well?

An open-pit mine is a production and operation unit that uses open-pit mining to mine mineral resources. The main production systems of open-pit mines are development and transportation systems, perforation and blasting and loading systems, drainage systems, waterproofing and drainage systems, as well as production of crushing, ore dressing, mechanical repair, auto repair, power supply, water supply, explosive preparation, tailings storage, etc. In workshops, some mines also have systems for rebuilding land. ^[1]

According to the terrain and the burial conditions of the deposit, open-pit mines can be divided into

Open-pit mine development

The development of open-pit deposits is to establish a transportation channel between the ground and various working levels of the open-pit stop (that is, access to the trench or well lane) to ensure the normal transport connection of the open-pit stop and prepare for a new level in time.

The development of open-pit deposits is closely related to the mode of transportation. The choice of the right development method directly affects important indicators such as the amount of mining infrastructure projects, infrastructure investment, the time of production and completion, the production capacity of the mine, and the production cost.

Open pit mining and transportation methods can be divided into road transportation development, railway transportation development, road-rail combined transportation development, road (or narrow gauge railway) -slope lift combined transportation development, road (or narrow gauge railway) -flat pit slip well combined transportation Development, road-crushing station-belt conveyor combined transportation development, self-sliding-slope hoisting and lifting transportation development seven types.

Mining methods of open-pit mines

The mining method of an open-pit mine refers to the development and change of the mining and stripping sequence in time and space conditions within the reasonable large-scale (or final) range of the open-pit mine. The mining methods of China's open-pit mines (especially metal open-pit mines) have been continuously reformed with the development of mining equipment and technology. In the 1950s, the whole-boundary (non-phased) mining method was generally used, with the disadvantages of long construction cycles and large investment. In the 1960s and 1970s, staged mining was generally adopted in all mines with conditions. In this way, the mine can be from small to large, rich first, then poor, easy first, and difficult, and speed up the initial construction of the mine, and the economic benefits have improved significantly. Because the peak of the stripping flood during the transition period is often high, the mine equipment, power supply, personnel and personnel The sharp increase in costs has brought many unfavorable factors to production management. After the 1970s, the design and feasibility study proposed the use of the new technology of steep gang expansion and new expansion (multi-phase mining) in the phased transition mining, which further solved the phased transition mining, especially in the whole-boundary mining method. There are some disadvantages.

China's metal surface mining methods are broadly divided into two categories: whole-boundary (non-phased) mining methods and phased mining methods. Staged mining is divided into staged transitional mining (longer staged time), extended mining (or staged mining, which has a short staged time) and zoned mining.

Piercing work

Perforation is the primary process of open-pit mining, and the quality of its work directly affects the blasting, mining, and transportation of the mine. In the whole open-pit mining process, perforation costs account for about 10% to 15% of the total production costs. Perforation has always been a weak link in open-pit mining in China. Since the use of roller drills began in the late 1960s, new progress has been made in perforation. Roller drills are widely used in most open-pit mines abroad. In China, the perforation equipment currently used in open-pit mining mainly includes roller drills, down-the-hole drills, steel wire impact perforators, rock drilling trolleys, etc. Among them, roller drills are the most widely used, followed by down-the-hole drills, and steel ropes. Impact punchers have been phased out and rock drilling rigs have been used under certain specific conditions.

Blasting work

Blasting is another important process in open-pit mining. Its purpose is to provide ore rock for mining, transportation, and crushing. Mine blasting costs generally account for about 15% to 20% of the total cost of the mine. Therefore, the quality of the blasting work not only directly affects the efficiency of the equipment for procurement, transportation and coarse crushing, but also affects the total cost of the mine. The blasting methods used in open-pit mining mainly include shallow-eye blasting, deep-hole blasting, chamber blasting, medicine pot blasting, external blasting, multi-row hole differential blasting, and multi-row hole differential blasting. Law, etc.

Procurement work

The mining work is the central link in the entire production process of open-pit mining. Other processes, such as perforation and blasting, transportation, and waste rock disposal, are all carried out around the picking and loading work. The mining technology and its production capacity largely determine the open-pit mining method, technical outlook, mining intensity, and ultimate economic effect.

The machinery and equipment used in procurement work include single bucket excavators, front loaders, cable bucket machines, wheel bucket excavators, chain bucket excavators, etc. Due to the relatively hard ore rock of metal surface mines, single bucket excavators and front-loading machines are mainly used at home and abroad. The development trend of mining technology is large and continuous. Therefore, with the progress of blasting technology and excavator manufacturing, the application of large bucket excavators in metal mines is very promising.

Transportation work

Open pit transportation is one of the main processes of open pit mining. The investment in the transportation system accounts for about 40% to 60% of the total investment in the mine. Transportation costs and labor account for half of the total mine cost and labor, respectively. It can be seen that open-pit mining plays a very important role in open-pit mining.

The basic task of open-air transportation is to send the ore from the quarry to the ore dressing plant, crushing station or storage site, and at the same time to transport the stripped rock and soil to the dump site, and the personnel, equipment and materials required in the production process Transport to work place.

Open pit mining transportation methods can be divided into human transportation and mechanical transportation, rail transportation and railless transportation. The transportation methods used in large and medium-sized open-pit mines include dump truck transportation, railway transportation, belt conveyor transportation, slope bucket lifting transportation, slope hoisting transportation, aerial ropeway transportation, and combined transportation (automobile-railway combined transportation, Dump truck-slope bucket combined transport). ^[2]

(I) Water pollution

Open-pit mining directly destroys a large amount of land, and the accumulation of various types of waste rock, waste residue, and tailings also encroaches on a large amount of land. According to incomplete statistics, the accumulated land occupied by mines nationwide reached 5.86 million hm ² , forest destruction was about 1.06 million hm ² , and grassland was 263,000 hm ² . There are more than 100 large coal mines in Shanxi Province, occupying an area of more than 2 000 hm ² , and there are more than 15,000 construction materials mines (points). The stripping of topsoil in mines usually neglects the preservation of arable soil, which leads to serious soil erosion. After the destruction of surface vegetation, the erosion by wind and hydraulic forces intensifies, and large areas of sand appear desertified.

(II) Geological disasters

Excavation of the ground and slope affects the stability of mountains and slopes, causes deformation of rock (soil), and induces geological disasters such as collapse and landslide. Waste rock (slag) discharged from mines often accumulates on mountain slopes or gullies, and mudslides are prone to occur when induced by heavy rain. There were more than 60 landslides in the Fushun West Open-pit Mine; a large landslide of 1 million m ³ occurred in the Baiyin open-pit mining pit; 11 people died in the landslide at the Wanshan quarry in Xiangfan; ³ large landslides occurred in the limestone mine in Pangang, causing serious facilities Damage; In 2003, due to continuous rainfall-induced heavy rainfall in Tongchuan Mining Area, there were 94 geological disasters such as landslides, landslides and mudslides, with direct economic losses of more than 20 million yuan; landslides at the south dump of the Antaibao open-pit mine caused many deaths.

(Three) solid waste pollution

In the open-pit mine near the scenic area, the tourism and sightseeing environment is extremely uncoordinated due to the damage to the landscape by mining. Many mines dump solid wastes at will, causing gully and river siltation, poor flood discharge and constant flooding.

(IV) Damage to the water environment system

Mining slag and tailings are exposed to the atmosphere. The oxidation of sulfides in them causes acid rain and the unqualified discharge of wastewater from smelting and smelting often causes the surface water bodies near the mining area to be contaminated and even unable to drink or irrigate. In addition, the dredging and drainage in the stope changed the natural flow field and supplementary and drainage conditions of the groundwater, and broke the balanced transformation of atmospheric precipitation, surface water, and groundwater. A large and cumulative falling funnel centered on the mining area is often formed, causing spring eyes to dry up. Water is depleted.

(5) Air pollution

Due to the large-scale use of large-scale mobile machinery and large-scale blasting in open-pit production, a series of dust and poison pollution has occurred in the air in the mine, such as blasting and diesel-powered equipment. Common pollutants are mainly dust, harmful and toxic gases [H ₂ S, SO ₂ , CO, NO ₂ etc.] and radioactive aerosols. Due to different production processes, the amount of dust produced is related to many factors such as the type of machinery and equipment used, production capacity, rock properties, operating methods and natural conditions. The strength of open-pit mining is high, and the degree of mechanization is high. Affected by the ground meteorological conditions, the gas produced is often sudden, such as blasting, adverse meteorological conditions and poor natural ventilation methods. It can even spread local pollution to the entire mine and cause atmospheric pollution. . The large amount of dust and toxic substances generated during the beneficiation and production process are also important factors for atmospheric pollution in the mining area. Under the action of the wind generated by nature and transportation vehicles, the tailings powder will be directly raised, which will cause the dust concentration in the atmosphere to be very high. Polluting the air in mines. In addition, the heavy metal-rich exhaust gas generated by the busy transportation in the mining area, the heavy smoke generated by the smelting plant, sintering plant, and power plant in the mining area and the harmful substances produced by coal burning in the mining area all constitute the atmospheric pollution of the mining area. ^[3]

Six largest open-pit mines in the world

1.Mir mine in Russia

The Mir mine, also known as the "Mirne mine", is an open-pit diamond mine located in Mirny, eastern Siberia, Russia. This diamond mine is 525 meters deep and 1200 meters wide. It is the second largest man-made pit in the world, second only to the Bingham Canyon copper mine in the United States. The Mill mine is the first and largest diamond mine in the former Soviet Union. It was mined for 44 years and closed in June 2001. After the disintegration of the former Soviet Union, the diamond mine was run by Saha Diamond Company, with annual profit from diamond sales exceeding $ 600 million.

2.Davik Diamond Mine in Canada

The Davik Diamond Mine is located in the Canadian Slavic region. It has a total of 700 workers and produces approximately 7.5 million carats of diamonds each year. Its sales revenue reaches 100 million Canadian dollars. The Davik diamond mine is an important pillar of the local economy. The Davik Diamond Mine was explored in 1992, started construction in 2001, and started production in 2003. It is connected to Davik Airport via an ice road. The airport can take off and land Boeing 737 passenger aircraft. The Davik Diamond Mine is a joint project between the Harry Winston Diamond Company and the Davik Diamond Mining Company. It is approximately 220 kilometers from the Arctic Circle and can be mined for 16 to 22 years.

3.Grasberg mine in Indonesia

The Grassberg Mine, located near the Jaya Peak in Papua Province, Indonesia, is the world's largest gold mine and the third largest copper mine, with a total of 19,500 workers. Jaya Peak is the highest peak in Papua Province. The operator of the Grasberg mine, Freeport Indonesia, is 90.64% controlled by Freeport McMullen Copper & Gold, including a 9.36% shareholding through a wholly-owned subsidiary, Indonesian Mining Investment Corporation. The Indonesian government holds the remaining 9.36% stake in Freeport Indonesia. In 2006, the Glasberg mine produced 610,800 tons of copper, 58.47 tons of gold, and 174.45 tons of silver.

4. Icardi diamond mine in Canada Icardi diamond mine in Canada is the first open-air and underground double-pipe diamond mine in Canada. It is located about 310 kilometers northeast of Yellowknife and about 200 kilometers from the Arctic Circle. Close to Lake Grasse. The Icardi Diamond Mine is a joint project of Dominion Diamonds and two geologists, Chuck Phipke and Stuart Bluson, with the former holding 80% of the shares and the latter 20%. Fipke and Bluson found tubular kimberlite veins in northern Lake Grasse. From 1998 to 2009, the six open-pit mines at the Icardi diamond mine produced a total of 40 million carats of diamonds. After the high-quality ore close to the surface has been mined, the Icardi diamond mine begins underground mining

5.Bingham Canyon copper mine in the United States

The Bingham Canyon Copper Mine, also known as the "Kennecott Copper Mine", is an open-pit mine located in the southwestern part of Salt Lake City, Utah. The porphyry copper mine is owned by Rio Tinto International Mining Corporation. The Bingham Canyon Copper Mine is managed by Kennecott Copper. The company also operates concentrators, smelters and refineries. The Bingham Canyon Copper Mine was put into production in 1906, and the giant pits formed were more than 970 meters deep and 4,000 meters in diameter. In 1966, it was designated as a National Historic Landmark. On April 10, 2013, a landslide occurred in the Bingham Canyon copper mine. As the accident was predicted in advance, mining operations were suspended the day before. The landslide led to a reduction of 113 thousand tons in the Bingham Canyon copper mine.

6.Super pits in Australia

Australia's Fermiston Open Pit, also known as the "Super Pit", is Australia's largest open-pit gold pit. The pit is located on the highway in the gold mining area southeast of Kalgoorlie. The super pit is rectangular, 3500 meters long, 1500 meters wide and 900 meters deep. We can see it even in space. The super pit is owned by Kalgoorlie United Gold Mine, which produces 28 metric tons of gold per year and employs about 550 people on the site.