Capital Equipment News September 2018

Only if supplier and customer are prepared to work closely together will it be possible to determine the most economical crushing system which is able to fulfil the quality demand.

More quality considerations Sandro Scherf, CEO of Pilot Crushtec International, says one critical consideration is the end application of the aggregate produced. Some basic examples where shape and size or product size distribution (PSD) are critical to include are filter sands, road construction and asphalt topping, to mention a few. “Filter sands require very strict product curves. With too much fine material, the filter sand turns to clay, which doesn’t allow water to flow through. With too little fine material, the water passes through too easily and particles aren’t filtered out,” explains Scherf. For road base construction, Scherf says the Colto specs on G1 and G2 base and sub-base material require at least 4-12% of 0,075 mm material, all produced from clean parent rock. “The micro fines basi- cally act as a lubricant when compacting the road-base to ensure that you get the correct compaction levels and have a sturdy base on which to lay the road. This can generally only be achieved with the introduction of a vertical shaft impact (VSI) crusher as a tertiary or quaternary stage in the process,” explains Scherf. For asphalt topping (and high MPa concrete), Scherf reasons that it’s critical to have a cubicle shape to the stone rather than a flaky product. Flaky material is weak and can be broken by the pressure of large vehicles, while an exposed hole will fill with water and quickly form a pot- hole. “Cubicle material fits closer together and more compactly, ensuring that less

QUICK TAKE

Quality parameters in aggregate production are normally based on strength, size and shape of the end product

The final product requirement is the cornerstone of equipment selection and plant design

If optimum shaped product is an obligation, the VSI crusher is the optimal shape-producing crusher

Apart from costs, the main advantage the VSI has over the HSI crusher when it comes to production of a cubicle product is the consistency in the end product

CAPITAL EQUIPMENT NEWS SEPTEMBER 2018 9