Kiln Material Residence Time Calculator

Estimate mean material residence time with the Sullivan empirical model; convert kiln slope correctly between percent and degrees.

Kiln Geometry & Operating Data

Kiln Diameter (inside lining) mInternal diameter after refractory lining

Kiln Length (m)Total kiln length

Kiln Speed (rpm)Typical: 2-5 rpm for large kilns

Feed Rate (tph)Kiln feed material rate

Slope ValueTypical kiln slope: 3-5% (approximately 1.72-2.86 degrees). The selector converts both to the same inclination angle.

Angle of Repose (°)Typical: 35-40° for raw meal/clinker

Bulk Density (t/m³)Raw meal: 0.9-1.4; clinker: 1.3-1.5

Method	Formula
Sullivan et al. (1927)	t (minutes) = 1.77 · L · √θ / (D · rpm · β) L and D in the same units; θ = material angle of repose in degrees; β = kiln slope angle in degrees (NOT slope %).
Material Velocity	v = L / t (m/min)
Kiln Load	M_load = Feed Rate · t / 60 (tonnes)

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