I. Basic knowledge of open pit mines
1. Closed circle and open pit mining classification
Closed circle: The plane closed curve of the surface of the open pit mining site.
According to the topographical conditions buried in the deposit, according to the surface closed circle of open-pit mining, it can be divided into hillside open pit mine and hollow open pit mine. Located in the open slope of the hillside above the surface closed circle, it is called the deep open pit mine below the surface closed circle, also called the open pit mine.
2. Three elements of open pit mine
Step: The rock is divided into horizontal stratification of a certain thickness, and the working level in the mining process forms a stepped shape in space. Each step is called a step and its height becomes the step height.
Step slope: The slope faces the side of the gob. The angle between the inclined surface and the horizontal plane is called the step slope angle.
Platform (flat): The space on the horizontal plane between the bottom line of the step and the top line of the slope. The width between the bottom line and the top line is called the platform width. The platform in the blasting, shovel loading and transportation operations is called the working platform; the width between the blasting edge and the top line is called the working platform height; The platform that blocks the falling rocks is called a safe (cleaning) platform.
3. Mining technology and development methods of open pit mines
The open pit mining process is relatively simple, mainly including perforation, blasting, shovel loading, and rock discharge.
(1) Perforation
The perforation work is the preparation process of the blasting, and the purpose is to create a space for the blasting to fill the explosives.
Perforation methods: thermal fracture perforation and mechanical fracture perforation.
Main application equipment: roller rig , down-the-hole rig and heavy rock drilling rig.
(2) Blasting
Blasting is the second process of open pit mining. Through the blasting operation, the whole ore is crushed and loosened to form a burst of a certain shape, which provides working conditions for subsequent mining operations.
Commonly used blasting methods are as follows:
According to the blasting delay time classification: uniform blasting, second blasting, and millisecond blasting.
Classified by blasting method: shallow hole blasting, medium deep hole blasting, chamber blasting, multi-row hole differential blasting, multi-row hole differential blasting blasting, medicine pot blasting, external blasting, hole-by-hole blasting technology.
(3) Shovel loading and transportation
The loading operation is to use the loading machinery to excavate the ore directly from the underground or the explosion, and load it into the compartment of the transportation machinery or directly to the designated place. It is the central link of the open-pit mining process, and other production processes such as wearing and blasting, transportation, etc. are all for the purpose of loading and unloading.
Main shovel equipment: excavators, bucket shovel, hydraulic shovel and tire front loading machine.
In the open-pit mining process, the capital construction investment of mine transportation accounts for about 60% of the total investment in mine infrastructure. The transportation cost and labor volume account for more than half of the total ore cost and total labor, respectively. An important position in mining.
Open pit mode of transport: motor transport, railway transport, transport belt, the slope skip hoisting and transport combined transport ways, the most common dump trucks.
The installation and transportation are inseparable, and the two influence each other and restrict each other. At present, the development trend of the loading and transportation process is mainly reflected in the large-scale production and transportation equipment, the integration and continuity of the loading and transportation links, and computer automation.
(4) lava
The bouldering is the operation of the transportation terminal, and the topsoil and waste rock under the stripping are transported to the waste rock yard for disposal.
Drilling technology: railway transportation, rock discharge, road transport, rock transport, belt transport, rock discharge
4. Dumping ground
Dumping site (waste yard): The place where the stripping material is piled up refers to the place where the mining waste is concentrated and discharged.
According to the stacking sequence, the dumping site can be divided into a single-step dumping site, a covered multi-step dumping site, and a multi-step dumping site with a pressure-slope foot.
According to the dumping process, the dumping site is mainly divided into: road transport dumping site, railway transport dumping site, tape transport dumping site and hydraulic transport dumping site.
Second, open pit mine safety training
1. Layered mining from top to bottom
Open-pit mining should follow the top-down mining sequence, sub-step mining, and adhere to the principle of "extraction and stripping, stripping first."
2. Blasting
The blasting work of open pit mines must strictly implement the safety management regulations for blasting operations, ensure that blasting operators have the corresponding qualifications, strictly manage the safety of blasting equipment , and standardize blasting operations. Medium-deep hole blasting must be used without approval.
3, stop inspection
Establish and improve the safety inspection mechanism of the stope. The inspection of the stope should be checked once every quarter. The high-steep side should be inspected once a month. The unstable section should be inspected in time after the storm, and the abnormality should be dealt with immediately. Common hazards and failure modes include large landslides, partial slumps or rolling stones.
4. Slope monitoring management
Slope detection: The system design of the slope monitoring system should determine the monitoring level of each area according to the stability type and zoning characteristics of the final slope. The slope should be regularly observed at fixed points, including the surface and internal displacement observation of the slope, dynamic observation of groundwater level, For blasting vibration observation, etc., the technical management department shall timely collate the slope observation data and guide the safe production of the stope.
Slope management: Slope management is an important and complicated task. The mine should improve the slope management and inspection system according to its own reality, large and medium-sized mines or mines with potentially dangerous slopes, except for sound slope management and The inspection knows that effective control measures should be taken for the key parts of the slope and the areas with potential landslide hazard, and the inspection and stability analysis should be carried out regularly by qualified intermediaries.
Common measures: cleaning and maintenance, slope reduction and load shedding, water interception and drainage, controlled blasting, artificial reinforcement, etc.
5. Dumping ground
The safety of the dump is divided into three levels according to height, stability, topography and thickness of the weak layer of the foundation: danger, disease level and safety.
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