Ball Charge Design and Check

Type in the ball sizes you have and the tonnes of each, and this works out how many balls that is, how much grinding surface you own, how full the mill becomes, and where the charge should stand when you next open the door. It then compares that against your last tape reading, so your ball records and your mill are checked against each other. Press YOUR CHARGE on the board to type it in.

Why this matters now

Clinker reduction, high electricity prices and tighter cement specifications put the grinding circuit under pressure. The fastest gains usually come from finding the real constraint before changing equipment or operation.

What this tool helps decide

Know which ball sizes and tonnes each chamber needs before the next top-up, so the charge supports the feed and target product instead of drifting by habit.

What subscription adds

Build a connected grinding audit: save every mill separately, reload previous measurements, compare changes over time and issue an editable report for the plant team.

Connected to the industry conversation around clinker-factor reduction, grinding energy, blended cement and quality control reported in World Cement, CemNet and Global Cement.See process-tool plans

Your charge, as recorded

The mill

Inside the lining, in metres. Not the shell outside.
Kilogrammes in one cubic metre of solid steel. Cast grinding balls are about 7700.

First chamber

Metres, inside the lining.
Tonnes in one cubic metre of charge, gaps included. Around 4.5 for big balls.
Millimetres, lining down to the top of the balls. Used only to cross-check your records. Leave 0 if you have not measured.
Ball size, mmTonnes of it
First chamber total:

Second chamber

Metres, inside the lining. Leave 0 for a one-chamber mill.
Tonnes per cubic metre. Around 4.65 for small balls, they pack tighter.
Millimetres, same way as the first chamber.
Ball size, mmTonnes of it
Second chamber total:
FIRST CHAMBER SECOND CHAMBER
FIRST CHAMBER
SECOND CHAMBER
WHOLE MILL
How full it gets
Steel in this chamber
Balls should stand at
How many balls
Average ball weight
Average ball size
Grinding surface
Surface per tonne
How full it gets
Steel in this chamber
Balls should stand at
How many balls
Average ball weight
Average ball size
Grinding surface
Surface per tonne
Steel in the mill
Total grinding surface
Records minus tape

Every size class, and what it actually does

green bar = share of the tonnes    blue bar = share of the grinding surface. Big balls carry the weight, small balls carry the surface. If a size class is a fat green bar and a thin blue one, you are paying to carry steel that is doing very little grinding.

What this charge will do

How the numbers are worked out

One ball. A ball is a sphere, so its weight is its volume times the density of steel, and its surface is the surface of a sphere. Nothing is assumed. Divide your tonnes by the weight of one ball and you know how many balls you own.

Surface. Add up the surface of every ball. That total is the only thing in the mill that actually touches material. Two charges of the same weight can differ by a factor of three in surface, and that is the difference between a mill that finishes cement and one that does not.

How full it gets. Tonnes divided by the bulk weight gives the space the charge occupies. Divided by the chamber volume, that is the filling. Run back through the circular-segment formula it gives the distance from the lining down to the balls — the same number the volume loading tool reads off your tape. That is the cross-check.

The two bands. A finish mill first chamber normally averages 1.35 to 1.65 kg per ball, and a second chamber normally gives 28 to 33 m² of surface per tonne of steel. Raw mills run lighter, around 0.30 to 0.45 kg per ball. These are the bands from your own ball charge file, not something invented here.

All of it comes from your own ball-charge-design.js. There is no fitted coefficient anywhere in this tool.