Grinding energy requirements

The grinding energy required for ductile mode is different from that for brittle mode. Based on the concept of the critical depth-of-cut d, which has attracted considerable attention so far, a general description has been successfully introduced to express the brittle-ductile relationship. 

For fine pulverization, both dry and wet processes are utilized, but increasingly the dry process is more popular because wet grinding ultimately requires drying and is much more energy intensive. A sensitive fan swirls the dust sizes into the air separator and permits coarse particles to recycle to the grinding mill or be rejected as tailings the fines are drawn into cyclones where the dust is collected. 

As only a small proportion of the material is in contact with the roUs and friction on the rollers is low, hard materials can be processed with tittle wear. The high pressure action creates a slab of ultrafine particles which usually requires a low speed impact milting system to disagglomerate. Used in closed circuit with such a disagglomerator and an air classifier, such machines can reduce the energy requirement for fine grinding many minerals. 

Grinding Efficiency The energy efficiency of a grinding operation is defined as the energy consumed compared with some ideal energy requirement. 

Ghosh, S., Chattopadhyay, A.B., and Paul, S., 2008. Modelling of specific energy requirement during high-efficiency deep grinding, International Journal of Machine Tools and Manufacture, 48 (11), 1242-1253. 

The maj ority of these new plants are corn dry-grind ethanol plants. Approximately 2.5-2.7 gal of ethanol, 17.5 lb of dried distiller s grain (DDG), and 17 lb of carbon dioxide are produced from each bushel of corn processed through a corn dry mill (2). Since 1980, process improvements in enzymes, thermal-tolerant yeasts, molecular sieves, and cogeneration have achieved a 50% reduction in the energy required to produce ethanol from corn (2). Further improvements in efficiencies and reductions in production costs can be expected in the future. 

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