Comparing revenues generated from copper sulphide ore – Flotation vs. Leaching

There is more and more news appearing on the internet about advances toward copper sulphide leaching, as this technique is deemed to be the next breakthrough for copper mining.  Related patents and technical papers propose many approaches to solve the problem, none of them currently capable of solving all operational constraints.

Given the variety of solutions, I can’t nail down the operating costs of such process.  However, I can compare the expected revenues between floating and smelting a copper concentrate versus leaching the ore and producing cathodes on-site.

General assumptions:

  • Copper price: $2.65 per pound
  • ore: chalcopyrite, no impurities, no secondary payable metals

Assumptions for flotation and smelting

  • Mill recovery: 88%.  I assume that the recovery is independant of the grade, a simplistic assumption, but one that can be revisited later.
  • Copper concentrate grade: 25%
  • Transport cost: $34 per wet tonne
  • Loading and representation: $5 per dry tonne
  • Metal deduction: 1.1 units
  • T/C, R/C: $70 per tonne, $0.07 per pound of copper

Assumptions for leaching

  • Process plant recovery: 75%, similar to oxide leaching
  • Cathode grade: 99.99%
  • Transport cost: $31 per tonne
  • Loading and representation: $5 per dry tonne
  • R/C: $0.07 per pound of copper.  I am not sure that this cost is applicable here.

The results are plotted below for copper feed grades from 0.3% to 1.3%.  I was surprised to see that the ore value is almost the same for both cases.

Cu value float leach vs grade

My observations are the following:

  • This revenue analysis is sensitive to copper recovery; any points up or down for either process can have a significant impact
  • Copper leaching can be economically advantageous if its operating cost is lower than that of flotation. It seems reasonable that it should be the case given that the grinding, flotation, concentrate thickening, and tailings disposal stages are eliminated.
  • Those two aspects are currently impeding the adoption of this technology in the industry.  Any company with the solution to improve either or both variables will certainly gain market value.

Author: George McIsaac

Mining Engineer and Mineral Economist specializing in underground mining.