The challenge: A regional aggregates producer had acquired a new mine site including an older crushing spread. The crusher had a relatively low production rate and was spread over approximately one-half mile. Customer trucks were routed too close to the crusher to maintain good safety separation. The old crusher and stockpiles were also situated on top of reserves that would need to be in production within the next two years.

The approach: RMCAC examined the mining, traffic, crushing and stockpile flow of the mine site. The crusher had never been previously moved. Additional conveyors were added as the working face went away from the crusher. RMCAC also looked at the schedule for the producer’s mobile crushing assets.

The solution: In the near term the old crusher was moved close to the mining face. Approximately one-third mile of conveyor was eliminated. Electric and MSHA inspection load decreased. The mining loaders also had a much shorter haul to the primary. Old stockpiles on reserves to be mined were aggressively sold in preparation for mining under them. In the following year the old low rate crusher was sold and a high production mobile crusher periodically rotated into the mine with setup in an optimal location each time.

The results: Crushing cost dropped by over $1 / ton by shortening up the crusher and loader haul. Fuel burn, traffic flow, stockpile location and access to reserves all improved. Crushing costs dropped another $1.50 to $2 / ton when the old spread was sold and replaced with a high rate mobile crusher producing the same volume of material in one-third the time. Overall company labor, fuel, maintenance and depreciation decreased with the optimization of the mine flow and crushing resources.