Metallurgical Risks

Some of the most flourishing mines which are now operating were commercially worthless until serious metallurgical problems could be overcome.

The ores of other mines hold metals that cannot be recovered until the ores are ground very fine or, in many cases, oxidized to liberate the valuable metals. The costs of grinding rise very sharply with the fineness of grind and oxidation of small amounts of ore can be fairly expensive.

The role of the metallurgist is to select the best and most affordable process available for optimum recovery from a given ore, normally by testing drill core, pit or underground bulk samples. Care must be taken to ensure the material tested (and thus, counted on to represent the entire orebody) is fresh enough not to have oxidized or altered in any way and that there is enough of it to make a reasonable judgement of the orebody by extrapolation.

Even if the metallurgist is given up to thousands of tonnes of material from test mining, the sample might not be representative of the deposit. It could be from a high-grade zone, or from an area with poor ground conditions under study by the mining engineer for the risk of excessive dilution. It could also be from the top of an open-pit deposit that has been weathered more than what lies further below.

To do a good job, the metallurgist must be provided with samples representing minable grades of each geologically different part of the deposit.