How Mining Works
What you need to know about underground mining
A look at the underground mining process
The Resolution Copper deposit lies more than a mile beneath the surface. The most viable way to recover this ore body is by going underground, using a process called block caving.
Block caving is a proven mining method using advanced technologies.
Here’s how it works.
- Ore, rock containing economically recoverable copper, is extracted from the bottom of the ore body.
- A void, or cave, is then created.
- Ore above the void breaks up due to gravity and falls into the cave.
- Extracted ore is hauled to crushing facilities and broken into smaller pieces.
- Then the ore is hoisted to the surface.
Underground excavations are supported and reinforced for safety by using various ground support methods, such as bolts, shotcrete, steel mesh, straps and steel arches.
By using gravity to break the rocks, block caving limits the blasting and drilling that is typical of underground mining.
This mining technique causes subsidence or sinking of the surface above. This is a gradual, predictable, monitored and controlled process.
From rock to copper
Once ore comes out of Resolution Copper’s underground mine, it’s processed to separate the copper from the rock before it is sent to be smelted and refined into 99.99% pure copper – ready to be manufactured into a variety of products.
The process works like this:
- A wet grinding process turns the crushed rock into a fine sand.
- The ground rock is then mixed with chemicals and additional water and placed into a series of tanks. Air is passed through the tank and the copper minerals attach to bubbles and float to the surface of the tank.
- These bubbles containing copper are skimmed and filtered to produce a fine damp powder called copper concentrate. This process upgrades the copper content from what was initially ore to a copper concentrate for smelting and refining.
- The rock left behind after recovery of copper is called tailings. Tailings slurry is processed through thickeners to recover water which is reused in the process plant. Thickened tailings are then transported to the tailings impoundment. Tailings are required by law to be safely stored in specifically sited, engineered, constructed and permitted facilities called impoundments to protect the land and groundwater near mining operations.
- The copper concentrate is then sent to custom smelters for further processing to convert to copper cathodes.
- Cathodes are used to make copper wire, pipes and other products that bring us energy, fuel our computers and mobile devices, and make green technologies possible.