Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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IN-PIT CRUSHING 56 E&MJ; • JULY 2017 www.e-mj.com Mobile Sizer Station is greater than the cy- cle time of the shovel so the shovel operator is unable to overwhelm the system. If the rock fits in the dipper, the sizer will crush it. The system can load trucks with one operator accurately. The truck can sense the load and signal the feeder to stop at full payload. The shovel never waits. The dump area for the Mobile Sizer Station is the same shape as a 350-ton truck. The shovel swing passes remain in the 90° to 120° range and it can run 24/7. Productivity Increases To prove his thesis, Pitchford used a production modeling system to compare the loading process with conventional techniques. "We talked to miners to get as much input as we could and develop software to determine actual production run rates," Pitchford said. "The software [Arena] told us exactly what would hap- pen. Using all of the information, it gen- erated animation of trucks loaded in a tra- ditional fashion and compared it to trucks being loaded using IPS and we saw that the IPS arrangement immediately outpac- es the tradition loading methods." "Using our models, we are seeing approx- imately a 12- to 14-load-per-hour improve- ment in the shovel's capability," Pitchford said. "That's the shovel loading at maximum capacity compared to the normal cycle of 3.5 loads per truck. Every fourth bucket in that loading arrangement is a half load." This form of mining should also be a much safer scenario as far as the truck driv- ers not getting anywhere near the shovel. A large open-pit mine could employ several surge feeders and a two sizer sta- tions. The operation could mine from mul- tiple benches using the sizer-surge loader arrangement for ore and then use the surge loader for moving waste rock. "We see the main market as moving material with a shovel and a surge loader," Pitchford said. "With every shovel, the mine would want to have a surge loader and then in the ore they would want to have a sizing station." As for the economics, if a mine has seven shovels, Pitchford said they can produce the same amount with five using this system. They can also use less trucks to move the same amount of dirt. Using this technique, MMD believes that a mine could get 12 to 14 more loads per hour from its shovels.