It is important to mention that the regrinding capacity required is partly dependent on the fineness of the primary grind and cannot be established until the primary grind is fixed and the total grinding cost is a combination of both. The regrind product size is independent of the primary grind and must be determined according to the recovery process. The most common situation is related to the cyanidation of the flotation concentrate prior to the leaching process.
Basically, the regrinding cost is a small fraction of the primary grinding cost and the total cost of regrinding, for each point on the primary grind curve, may be adequately approximated by using the cost for a suitable base case and an appropriate scale exponent. Similarly to primary grind, the total regrinding cost should include both capital and operating cost factors as well as indirect and overhead items and must represent the actual cost of regrinding as closely as possible. The cost of regrinding is different because of the greater tonnage of rougher concentrate derived from the high gold grade ore. In order to analyze several options is common to consider a similar gold content in the concentrate. In order words, the cost of the grinding cost is influenced by the gold grade that treats the rougher flotation. It means that a low grade must produce lower weight than a high grade material.
Relation of total grinding cost to primary grind cost