Equivalent Grades

With polymetallic deposits, it can be difficult to appreciate the contribution each metal makes to the value of an orebody. Each has their own grade, price and metallurgical recovery, which complicates things. Worse still, the grades and prices have variable units of measure that might be an inelegant mix of the imperial and metric systems. Common practice is to collapse that complexity to a single value known as an equivalent grade. Here we select a single metal (usually the primary commodity in the deposit) and ask, "if this were the only payable metal in the deposit, how high would the grade need to be to acheive an equal value to this mix of metals I'm dealing with now?"

When doing such a calculation, keeping the arithmetic straight can be painful. This tool eases that pain by doing the math for you. Populate the fields with the proper grade values, metal prices, metallurgical recoveries, and units, and it will provide not only a calculated equivalent grade, but also the formula for doing so.

Please note, I have not gone to the effort to accomadate "Net-Smelter Return" terms. If the idea is to sell a concentrate to a smelter, keep an eye out for different payabilities on the various metals and how that might impact equivalent grade calculations.

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