Five main sources of dust in open-pit mines and their prevention measures

5. Dust is generated from soil disposal

When the transport equipment discharges materials in the dump, dust is generated due to the collision and friction of rocks. In addition, due to the large drop of the dump and the large amount of discharge, the amount of secondary dust is also large, which has a serious impact on the surrounding environment.

Five measures to prevent dust in open pit mines

Dust prevention measures for drilling operations

The dust prevention measures of drilling rig operation mainly include dry dust suppression, wet dust suppression and dry and wet combined dust suppression. For the cone drill commonly used in mines, the three-stage dust removal system is the most effective, which can make the air dust content in the working area of the drill meet the health standard, and the dust removal efficiency is more than 99%. The first stage usually uses a dust settling tank to remove drilling cuttings and coarse dust in the air stream, and the efficiency is generally 50%-70%. The second stage is a group of cyclone dust collector, which removes medium and fine particle dust in the air stream, and the efficiency is generally 70%-80%. The third pole is a belt filter for capturing fine dust with an efficiency of more than 99%. For dust with high dust humidity or that may be bonded on the surface of the bag, hydraulic dust removal or bubble dust collector is used as the third level dust removal.

Dust prevention measures for blasting operations

The methods of dust control in blasting operation are mainly divided into technical dust control and hydraulic dust control. Dust prevention in blasting process refers to the improvement of blasting process and the effective use of explosive blast wave to reduce the residual dust discharged from the gun hole and blasting funnel. For example, the direction of extrusion blasting in the formation of explosive pile to achieve the purpose of reducing dust; Directional initiation of deep hole charge can reduce the discharge of residual dust from the hole. Water can not only wet the surface of ore rock and dust, but also penetrate into the ore body through cracks, and play a good dust-proof effect. Hydraulic dust removal methods include water-filled chamber blasting, water plug blasting, using glue paste to plug, spraying water in the explosion area, foam covering the explosion area, etc.

Dust prevention measures for mining operations

The mining operation sprinkles or sprays a chemical additive solution on the explosive pile before excavating the nearest work surface, while spraying water while excavating. When the moisture content of the ore is increased from 4% to 8%, the dust content in the air of the shovel face can be reduced from 200mg/m³ to 20mg/m³, that is, the dust concentration in the air of the working face can be reduced by 9 times. In addition, spray dust sprinklers can be installed on the shovel, and the distance the sprayer moves at one time is related to the water pressure, the speed of the stope wind, the wind direction, and the speed of the shovel. Generally, the distance that the sprayer moves once should be less than the maximum range of the nozzle.

Dust prevention measures for transportation operations

For open-pit mines that are transported by automobile, dust prevention measures during transportation should mainly be taken for the dust produced on the road surface. At present, the dust prevention measures on the surface of the open-pit mine transport road are mainly: laying fixed water pipelines along the route, installing sprayers every other section, spraying water on the road through the sprayer, spraying calcium or magnesium salt solution with strong moisture absorption, mixing powdered or granular calcium chloride in the road surface, treating the special paving road surface with emulsion. For open-pit mines that use tape transportation, the dust prevention measures are mainly to set up dust walls to prevent dust from floating into the stope with wind flow, or to use closed transportation to reduce the time and area of the transportation material exposed to the atmosphere.

Dust prevention measures for dumping operations

Water or sodium chloride solution can be sprayed to the secondary dust points, and trees with high value can be planted around the dump site to strengthen the reclamation and greening work of the dump site.

There are many sources of dust in open-pit mines, the prevention and control of which can not be based on single-machine protection, according to the actual situation of open-pit mines, on the basis of single-machine protection, further improve other protective measures to achieve comprehensive dust prevention in open-pit mines, reduce the dust content in open-pit mines to a minimum, and provide a good working environment for mine employees.