How can I improve my size reduction equipment’s throughput?

When considering optimization of one’s size reduction equipment, it is important to consider not only the mill itself but the ancillary equipment as well.

·  For some types of mills, process airflow is directly related to throughput.  Increasing the airflow and operating the coupled classifier drive at a higher speed (if available) may increase throughput.

·  Worn internal parts often reduce capacity.  Even for slightly abrasive powders, internal parts like grinding element (hammers) and liners wear out, increasing critical clearances in the mill and causing less efficient grinding.  Replacing these components will improve grinding efficiency and capacity.

·  Consider alternate mill internal parts.  Most mills can be equipped with various types of rotors and/or classifiers.  Fibrous materials tend to reduce in size more efficiently with shear forces.  Granular, round or crystal shaped materials grind better with direct, normalized impact forces.  Finding the best type of grinding rotor is vital to optimizing a mill’s throughput.

·  More uniform, consistent delivery of feed material to the mill.  The goal is to operate the mill at or as close to the mill’s full load (typically determined by its rotor’s motor and/or classifier’s power size in HP or kW) without overloading the motor(s).  Minimizing the surges to the mill, i.e. fluctuations in the feed rate reduces the variation amplitude and yields a higher average feed rate, thus optimizing the mill’s throughput.

·  For most powders, it takes less grinding energy to reduce a smaller feed particle.  In other words, in many cases pre-sizing the material prior to milling by way of pre-crusher or other form of coarse milling yields higher throughput.  Consider testing smaller feed sizes to determine the impact of grinding energy and throughput.

·  In certain cases, a milling circuit, i.e. a mill coupled with an inline air classifier or screener, may yield higher throughput.  Scalping the oversize particles and recycling this fraction into the milling system in most cases results in a higher capacity.  Grinding energy increases exponentially for smaller product particle sizes and downstream separation with recycle often improves product efficiency.

As seen in Powder Bulk Engineering – June 2017