Mining and Mineral Processing PE

Remember that negative NNP values indicate acid-forming potential. The NNP:AP ratio is also important - values less than 1:1 suggest high ARD risk regardless of absolute NNP. Pay attention to units and classification thresholds.

Atkinson's equation is fundamental for mine ventilation calculations. Remember that friction factor k varies significantly with airway surface conditions - always check the given k value or select from typical ranges. The equation shows pressure loss is proportional to Q² and inversely proportional to A³, making larger airways much more efficient.

The Bond Work Index is fundamental to grinding circuit design. Remember that F and P are the 80% passing sizes, not average sizes. The test sieve size P₁ is typically 106, 150, or 212 microns. Always check that P < F (product is finer than feed) or the equation will give negative results.

Cut-off grade determines what ore gets processed vs. sent to waste. Lower cut-off grades mean more ore processed but at lower average grade. Watch for units - ensure costs, recovery, and price are compatible. Recovery is typically given as decimal (0.85) not percentage.

This fundamental equation appears in mining engineering problems. Remember that ore density varies significantly by mineral type. Always check if density is given as in-situ or bulk density, as void spaces and fractures affect the calculation.