PTC:02-2

Methods for Design and Optimisation of Ball Mill and Other Grinding Circuits, Classifiers and Cyclones

This is a comprehensive report especially useful for all such industries which employ dry or wet ball mills, other grinding mills like roller mills, roll presses, hammer mills, crushers, classifiers, cyclones, hydrocyclones etc., equipment manufacturers, consultants, designers, researchers and students.  The report is useful:

• To increase throughput of the grinding circuit 

• To obtain the most energy efficient operation

• To predict psds of mill outlet, coarse recycle and fine product

• To design optimum grinding mills and circuits

The report consists of the following chapters

1. General definitions.
2. Design of ball mills covering mill sizing, throughput, power, particle size distribution and mill rpm.
3. Batch, open-circuit and closed-circuit grinding modeling covering determination of rate of breakage function and distribution function from experimental data, mill matrix, classifier modeling etc. 
4. Effects of ball loading, ball size distribution, ball density and  material filling on mill performance.
5. Effects of air ventilation and water injection on performance of dry milling circuits including heat balance.
6. Wear of balls, liners and lifters in dry and wet mills, and design of liners.
7. Design and analysis of classifier performance covering correction of psd data of streams around the classifier, Tromp curve and estimation of direct bypass fraction, cut-particle diameter, sharpness index of cut and overall collection efficiency.
8. Design and analysis of cyclone performance using a simplified mathematical model programmed in a spreadsheet (which will also be supplied).
9. Conclusion.

The mathematical models outlined in the above chapters form the basis for our technology softwares BMSIMUL and CLASANAL.  A companion software SIZEANAL for particle size analysis of powders and the corresponding report No. PTC:02-1 should also be extremely useful in this context.

The various mathematical models are illustrated with the help of 50 worked-out examples and 11 industrial case studies covering bauxite, copper ore, cement, raw material grinding in a cement plant, chalcopyrite, iron ore, rock phosphate, PPC mills' optimisation by heat balance optimisation etc.  These should be extremely useful to operating plants for understanding mill circuits' operation leading to optimisation, to designers for designing optimum equipments, and to engineers and plant operators as an effective learning/training aid.