Reagent dosing: kg/t, consumption and cost

Reagent dosing is where the chemistry meets the operating budget. A circuit meters its bulk reagents against the ore it treats, in kilograms per tonne of dry solids, and that single unit ties a chemical decision to a cost line that often dominates the plant’s operating spend. An engineer who is fluent in dosing can read the economics of a flowsheet straight off the reagent schedule.

The base arithmetic is direct. A dosage in kg/t multiplied by a dry-solids throughput in t/h gives a reagent rate in kg/h; that rate times the operating hours gives a daily consumption; the daily consumption times a unit price gives a daily cost. There is nothing subtle in the multiplication — the subtlety is in the dosage figure itself and in what it means.

Addition versus consumption

The distinction that matters most is addition versus consumption. Addition is what you dose into the circuit; consumption is what the process actually uses up. They are not the same number. Some reagent is consumed by the reaction you wanted, some by side reactions with gangue minerals, some reports unreacted to the next stage or to tailings, and some is recovered and recycled. Acid consumption on a leach, for example, is driven as much by the acid-consuming gangue in the ore as by the metal you are dissolving — a mineralogy question, not a stoichiometry one.

So a dosing figure can mean "what we add" or "what the ore demands", and a reagent balance has to be clear which. The dosage that drives the cost is the net consumption, and it comes from testwork and plant data on the specific ore, not from a reaction written on paper.

Why this line dominates

Why this line dominates is a matter of scale. A plant treating a thousand tonnes a day at a few kilograms per tonne is consuming several tonnes of reagent daily, every day, for the life of the operation. A change of one or two kilograms per tonne — well within the spread that mineralogy and operating practice produce — moves the annual reagent bill by an amount that can outweigh a capital choice. This is why operators watch consumption continuously and why testwork spends real effort pinning down reagent demand: it is a number the economics are genuinely sensitive to.

The calculator below turns a dosage and a throughput into a consumption rate, a daily tonnage and an optional daily cost, with the dosage as an input you supply from testwork or plant data. It estimates how much reagent a given dose costs; it does not predict recovery, optimise the dose, or model the chemistry — those come from the ore, not the arithmetic.