Aining a Kimberlite Pipe

Mining of a diamond-bearing pipe starts with the excavation of a pit into the pipe. In this process, called "open-pit" or "open-cast" mining, the initially loose and eventually hard ore material is removed with large hydraulic shovels and ore trucks. Hard rock is drilled and blasted with explosives so the broken material can be removed. When deep, rich ore warrants it, the mining goes underground with vertical shafts descending to horizontal drifts, or passageways that enter the pipe.

In bedrock adjacent to the pipe, shafts are sunk and drifts are tunneled into the pipe. The highly mechanized and efficient method known as block caving is shown in the adjacent model. Concrete-lined tunnels are excavated under a large vertical section, perhaps 140 to 180 meters (400 to 600 feet) of kimberlite. Along the tunnels are draw points, or openings in the concrete casing where kimberlite is The open pit at the Udachnaya (Lucky) pipe in Sakha Republic, Russia, has produced many millions of carats of diamond. The bench steps are about 20 m high.drilled and blasted to cave in a section above the tunnel. Broken kimberlite falls through the draw points and is scraped out of the tunnel with a drag or scraper bucket attached to a cable and winch, working much like a clothes line on a pulley. The kimberlite above the tunnels falls under its own weight and leads to a slow, continuous caving of ground that is removed through the draw points. The scraped kimberlite rubble is loaded into cars on a lower level and moved to a crusher underground. The crushed ore is then conveyed to skips that carry the ore up the vertical shaft for processing.