Circulating Load Ratio (CLR) Calculator

Calculate grinding circuit Circulating Load Ratio (CLR %), cyclone underflow recycle tonnage, and total mill throughput from pulp density and screen assays.

Circuit Tonnage & Assays

Fresh Feed Rate F (t/h):

Mesh Sieve Reference Size (µm):

Cyclone Feed Passing Assay c (%): % cumulative passing reference sieve

Cyclone Overflow Assay o (%): Flotation feed (% passing)

Cyclone Underflow Assay u (%): Recycle to ball mill (% passing)

Circulating Load & Tonnage

Circulating Load Ratio (CLR):

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Underflow Recycle Tonnage:

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Total Ball Mill Feed Load:

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Cyclone Feed Slurry Load:

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Frequently Asked Questions

What is a typical Circulating Load Ratio in closed-circuit grinding?

Standard industrial ball mill circuits operate with circulating loads between 200% and 400% (ratio 2:1 to 4:1). High circulating load rapidly purges finished fines, preventing energy-wasting overgrinding.

What causes CLR to run too low or too high?

Low CLR (<150%) results in excessive fines and slime generation. Extremely high CLR (>500%) overloads the cyclone feed sump, causing cyclone roping and mill choking.

Can CLR be determined from pulp densities?

Yes; if size assays are unavailable, mass balance can be solved using % solids of feed, overflow, and underflow streams: CLR = (So - Sc)/(Sc - Su).