RED DUNE
Red Dune · Process Engineer Toolkit

Yield Optimiser · Ash or CV

When coarse and small coal, or two seams, are washed separately and blended, cutting each at the same quality rarely gives the best yield. Find the cut points that maximise total yield at your product ash or CV.

A RED DUNE TOOL · v0.1
You're viewing example data. Enter your own washability for each circuit or seam. Free registration unlocks your results.

Washability by source

Example data loaded
FractionRDYield% fract.Ash% fract.CVMJ/kg fract.

Enter fractional washability for each source; densities may differ between sources. Share of plant feed is each source's mass as a % of total plant feed (they need not add to 100% if some feed bypasses washing). Tip: paste four columns (RD, yield, ash, CV) from Excel into any RD cell.

Optimum

SourceFeed share%Optimum cutqualityYield% of sourceYield% of plant feedSeparationRDEqual-quality cutyield % of source
Optimised cutsEach source cut at the same quality

What the extra yield is worth

Optional: enter plant throughput and price to turn the yield gain into tonnes and revenue.

Method

Total yield at a fixed product quality is greatest when every source is cut at the same incremental (elementary) quality, not the same product quality. The tool finds that incremental value by bisection so the blended product meets the target exactly, using monotone cubic (PCHIP) curves of cumulative quality against yield for each source.

The equal-quality comparison cuts every source at the target quality itself, the simplest way to run a plant.

Reading the results

  • Yield gain is the extra product, as % of plant feed, from optimised cuts over equal-quality cuts.
  • One source is usually cut cleaner than the target and the other dirtier; the blend still meets specification.
  • The optimum is often flat: cuts slightly either side give almost the same yield, so pick ones the plant can hold.

Limitations

Results assume perfect separation at each cut. Real plants misplace material, more so for fine coal; use the DMS Efficiency Test tool to account for that. Gains are only realised if each circuit's density can be controlled independently and the products are blended.

References

  • Leonard, J.W. (ed.) (1991). Coal Preparation, 5th ed. SME.
  • Osborne, D.G. (1988). Coal Preparation Technology.
  • ISO 7936:2022, float and sink characteristics.