Grade – The Crucial Factor for an Economic Uranium Mine (An Opinion Based on Considerable Experience and Common Sense)

摘要

Since the resurgence of the uranium mining and exploration industry (less than ten years ago) only three conventional uranium mines were brought into production and one of these had to close. New uranium explorers dusted off and successfully expanded numerous projects found in earlier heydays of uranium exploration. Some even found new uranium mineralisation and deposits. Why did this exploration success not lead to an equally successful start-up of new mining operations? The answer in the author’s opinion is grade. Most of these new or rejuvenated and upgraded deposits are basically too low-grade to be developed into a conventional uranium mine under the current uranium price regime. Using simple calculations like marginal cut-off grades in conjunction with achievable production and capital costs, and with current uranium prices going up to US$80/lb, it can be shown that uranium deposits with average grades below approximately 400 ppm U_3O_8 are essentially uneconomic and are unlikely to be developed under current economic circumstances. To develop a conventional uranium mine a minimum reserve base, somewhere close to 10 000 t (24 Mlb) contained U_3O_8, is also required. However, to make such a small orebody economic, average grades of 1000 ppm U_3O_8 or greater will be needed. To develop orebodies of 500 ppm U3O8 average grade, very large reserves in the vicinity of +150 000 t (330 Mlb) contained U3O8 are required. It seems very unlikely that uranium orebodies of below 400 ppm U_3O_8 average grade can be developed under current economic circumstances. For these lower grade deposits to become economic, uranium prices will need to rise over or well beyond US$80/lb.