Particle size reduction and enlargement

A material is crushed in a Blake jaw crusher such that the average size of particle is reduced from 50 mm to 10 mm, with the consumption of energy of 13.0 kW/(kg/s). What will be the consumption of energy needed to crush the same material of average size 75 mm to average size of 25 mm  

Which of these results would be regarded as being more reliable and why  

A crusher was used to crush a material with a compressive strength of 22.5 MN/m2. The size of the feed was minus 50 mm, plus 40 mm and the power required was 13.0 kW/(kg/s). The screen analysis of the product was  

What power would be required to crush 1 kg/s of a material of compressive strength 45 MN/m2 from a feed of minus 45 mm, plus 40 mm to a product of 0.50 mm average size  

A dimension representing the mean size of the product is required. Using Bond s method of taking the size of opening through which 80 per cent of the material will pass, a value of just over 4.00 mm is indicated by the data. Alternatively, calculations may be made as follows  

At the other end of the spectrum, many very fine powders are frequently to difficult handle, and may also give rise to hazardous dust clouds when they are transported. It may therefore be necessary to increase the particle size. Examples of size enlargement processes include granulation for the preparation of fertilisers, and compaction using compressive forces to form the tablets required for the administration of pharmaceuticals. 

In this Chapter, the two processes of size reduction and size enlargement are considered in Sections 2.2 and 2.4, respectively. 

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Nc PARTICLE SIZE REDUCTION AND ENLARGEMENT Critical speed of rotation of ball mill (rev/time) Units in SI System s-1 145 Dimensions in M, L, T T-l... 

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