RED DUNE
Red Dune · Process Engineer Toolkit

Mayer Curve Analyser · Ash

Enter float–sink washability data and read off theoretical yield, separation density and discard ash for any target product ash, single or two-product.

A RED DUNE TOOL · v0.4
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Washability data

Example data loaded
FractionRDYield% fract.Ash% fract.
Total / raw

Tip: copy three columns (RD, yield, ash) from Excel and paste into any RD cell. Rows sort by density; mark the final sinks row as S.

Separation

Mayer curve (ash / yield) Densimetric curve (RD / yield) Ash vectors & construction

Cumulative washability

FractionRDYieldfract. %Ashfract. % Ash massfract. %Floats yieldcum. %Floats ashcum. % Sinks yieldcum. %Sinks ashcum. %Ash masscum. % (Mayer)

Method

The Mayer (M) curve plots cumulative ash mass, the sum of fractional yield × fractional ash, against cumulative float yield. A straight line from the origin to a% at 100% yield is the ash vector for product ash a; where it crosses the curve gives the theoretical yield.

The curve is interpolated with a monotone cubic (PCHIP) spline, so its local slope gives the ash of the elemental particle at the cut. Separation density is read from the densimetric curve at the same yield. Discard ash is the ash mass balance of the remainder.

Reading the results

  • Cleanest particle: slope of the curve at 0% yield.
  • Dirtiest in product / cleanest in discard: slope at the cut point.
  • Dirtiest in discard: slope at 100% yield.
  • Near-gravity material: yield within ±0.10 RD of the cut, rated on Bird's scale from simple to formidable.

References

  • ISO 7936:2022, Coal: determination and presentation of float and sink characteristics.
  • Mayer, F.W. (1950). Die Mittelwertkurve. Glückauf, 86.
  • Osborne, D.G. (1988). Coal Preparation Technology. Graham & Trotman.
  • Leonard, J.W. (ed.) (1991). Coal Preparation, 5th ed. SME.
  • Wills, B.A. & Finch, J.A. (2016). Wills' Mineral Processing Technology, 8th ed. Butterworth-Heinemann.
  • Fritsch, F.N. & Carlson, R.E. (1980). Monotone piecewise cubic interpolation. SIAM J. Numer. Anal. 17(2).

Limitations

Mayer Curve Analyser is a Red Dune tool, built on standard coal preparation washability practice.

Results are theoretical (perfect separation) and assume representative float–sink data. Extrapolation below the lightest float density, set by the 0%-yield RD, is uncertain, especially when the first float is at 1.40 RD or above. Use for screening and comparison; confirm plant design with a qualified engineer.