A massive landslide on April 10 resulted in about 165 million tons of rock crashing down into the bottom of the Bingham Canyon Mine. No one was hurt but the slide, which company officials termed one of the largest in mining history, covered most of the bottom of the open-pit mine with rock and debris an estimated 300 feet deep. It brought ore mining to a halt.
Jones said Kennecott crews were able to begin mining copper ore over the weekend from an area in the bottom of the pit that was untouched by the landslide. Still, the volume of ore that was mined on Saturday and Sunday was only a fraction of the 150,000 tons of ore that, prior to the landslide, normally would have been processed at the crusher each day.
From the crusher, ore is sent over a 5-mile conveyor belt system that runs through 3 miles of tunnel to the company's concentrator, where large grinders further pulverized the stone into a fine powder.
The concentrator takes the pulverized ore and mixes it into a slurry that then is piped to flotation cells were it is mixed with reagents to produce a bubbly froth. Copper, gold, silver and other metals adhere to the bubbles, which float over the sides of the flotation cells. Kennecott then collects and filters that material, which is called concentrate.
The concentrate, which contains about 26 percent copper and by-products such as gold and silver, is then sent through a pipeline to the company's smelter for further processing.
Faced with a shortage of concentrate in recent weeks the result of the lack of ore mining follow the landslide Kennecott is now turning to outside suppliers to help it get the raw materials it needs to feed its smelter so it can produce refined copper for its customers.
On rare occasions in the past, Kennecott supplemented its supply of concentrate feed with small amounts purchased from outside suppliers, Jones said.
Since the slide, Kennecott's marketing team has secured two lots of concentrate, Jones said. The first portion of which is being delivered now and will continue to be delivered in the coming weeks. By comparison, the purchased concentrate represents less than 20 percent of a normal monthly supply.
Scott Mullins, president of United Steelworkers Local 392 that represents the ore-truck drivers at the mine, said the dumping of that first load of ore into the concentrator was a significant milestone for Kennecott and its workers.
"The good news is that the crusher, the tunnel and the conveyor belt system weren't damaged in the landslide. If those had been damaged we really would have been in big trouble."