Capital Equipment News August 2018

CRUSHING – PART 1

A jaw crusher is universally applicable in primary crushing applications and is used to reduce large material to a more manageable size.

on a very hard granite or basalt can result in the hammers breaking at worst, or very high operating costs at best. “Knowing the silica content or abrasion index of the feed material is critical in selecting not only the correct crusher, but also the correct wearing materials to ensure a profitable operation,” says Scherf. He adds that rock properties, even

on the same rock types, vary considerably as they are produced in a natural and varying environment, not a controlled lab. “Not all granites are the same, a fine grain granite is significantly harder than a coarse grain granite; some will have a higher silica (SiO2) content than others. In order to manage customer expectations and operating costs, we

generally send rock samples to the Metso Lab for abrasion and crushability tests, we can then simulate the plant and provide accurate estimates of the operating cost and ensure we have the correct configuration,” adds Scherf. Scherf also reasons that harder material will have an impact on the number of crushing stages. “The harder the rock the more energy required to break it down. Similar to a racing car, using different gear ratios depending on the race track, efficient and economical operation of a plant requires fine tuning to take the material properties into account,” he says. Van Rensburg says a good host rock is vital for production of a quality product,

“The hardness of the material will also affect the primary crusher selection and may well impact the throughput that can be achieved through the crushing circuit.”

CAPITAL EQUIPMENT NEWS AUGUST 2018 12