Know More About Open-Pit Mining Process

The mining process in open-pit mines is relatively straightforward and primarily involves drilling, blasting, excavation and loading, and waste rock handling.

Drilling Equipment

Down The Hole Drill Rigs(also called blasthole drills), with their wide range of drilling angles and high mechanization, reduce auxiliary operation time, enhancing drill performance. These drills are maneuverable, lightweight, and cost-effective. They facilitate various inclined hole drilling, controlling ore grades, eliminating footwall, reducing oversize material, and improving blasting quality. As a result, DTH drill rigs are widely used in small to medium-sized mines domestically and internationally, suitable for drilling in medium-hard rock formations.

• Rock Drills Carriage

Rock drills carriages, a novel rock drilling equipment, emerged with the advancement of mining industry. They integrate one or several rock drills with an automatic propulsion system mounted on specialized drill arms or frames, enabling mechanized rock drilling operations.

Blasting Operations

Blasting aims to break solid ore rocks, preparing suitable fragments for excavation. Blasting costs typically constitute about 15%-20% of the total expenses in open-pit mining. The quality of blasting directly affects the efficiency of excavation, transportation, and coarse crushing equipment, thereby impacting overall mining costs.

• Shallow Hole Blasting

Shallow hole blasting involves smaller blasthole diameters, typically around 30-75 millimeters, and depths generally not exceeding 5 meters, sometimes reaching around 8 meters if drilled using rock drill carriages. Shallow hole blasting is primarily used in small-scale open-pit mines, quarries, tunneling, secondary breaking, establishing new open-pit mining layouts, forming transportation routes in single-wall slope open-pits, and other specific blasting applications.

• Chamber Blasting

Chamber blasting involves using a considerable amount of explosives placed within blasting chambers or tunnels. Open-pit mines utilize this method during initial construction phases or specific conditions, while quarries adopt it when demand for mining is substantial.

Excavation and Transportation

Excavation involves using loading machinery to directly extract ore from underground or blast piles, loading it onto transportation machinery or directly unloading it at designated areas. It constitutes the central phase of open-pit mining, with other processes such as drilling, blasting, and transportation serving the excavation process.

Primary loading equipment includes excavators, clamshell buckets, hydraulic shovels, and tire-mounted front loaders.

In open-pit mining, basic infrastructure investments in transportation account for around 60% of total mine construction investment. Transportation costs and labor represent over half of the total ore costs and labor respectively, highlighting the pivotal role of transportation in open-pit mining. Common transportation methods include trucking, railway, conveyor belts, inclined bucket hoisting, and integrated transport systems, with self-dumping truck transport being the most prevalent. Excavation and transportation are interdependent, mutually influencing and constraining each other. Current trends in excavation and transportation processes focus on equipment upsizing, integration, and continuity, alongside computer automation.

Waste Rock Handling

Waste rock handling involves transporting stripped surface soil and waste rock to waste dumps. Methods include railway transport, road transport, and conveyor belt transport.