Financial aspects of comminution in beneficiation plant

The cost of comminution operations is typically a very significant proportion of the total cost for mineral processing. Comminution costs are conveniently divided into two parts: Capital costs (the original cost of equipment and its installation) and operating costs (the day-to-day costs associated with power, wear parts, maintenance, and labor provided by operators).

Typical capital costs are shown in Tables 1 and 2  for a copper ore and an iron ore processing operation, respectively. The total investment cost for the copper crushing and grinding plant is about $48.8 million. The total investment cost for the iron ore crushing and grinding plant is about $54.2 million.


It should be kept in mind that the hardness of these two ore types differ by 113% and that the final product size of each is different. Copper ore product size required for flotation is about 80% passing 100 mesh, whereas the iron ore size required for making iron ore pellets is approximately 80% passing 270 mesh. Note that in each case the installed cost is roughly 1.5 times the equipment cost. The installed cost includes foundations, buildings, wiring, and basic regulatory controls. In addition, the cost of equipment varies roughly as the size reduction effort; that is, it must deliver the cost of the maximum power it is capable of drawing during breaking operations.
Finally, operating costs vary with comminution device type, ore type, feed size and product size, local energy and labor costs, media and wear protection materials used, and equipment operating modes and maintenance programs. Typical copper and iron ore costs are presented in Tables 3 and 4.
A more general division of operating costs is shown by equipment type in Figure 1. Note that the relative costs for energy and wear parts, liners and grinding media are different for different ball mill types.
When taken in total, these costs (capital plus operating) seem to be huge, but an analysis of the net present value (which takes into account the comminution plant revenue minus operating costs discounted to their current value) of a comminution operation for a 10-year period for an 85,000-tpd copper ore operation and a 25,000-tpd iron ore operation in 2001 in North America, for example, predicts profitable performance. As long as the metal values of the ores are high enough and the overall finenesses of the product required for separation are not too small, the overall economics of comminution will always be quite favorable.
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Sinonine technology team



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