The premiums, paid on top of benchmark three-month London Metal Exchange (LME) prices, fell 10.7% from Friday's levels to $62.50 a tonne, the lowest since June 2017.
Detour is under pressure from two other investors, investment company Coast Capital Management L.P.and hedge fund Livermore Partners, to overhaul its board and consider a sale.
The macro picture may have brightened just a little after the weekend meeting of the U.S. and Chinese presidents, but signs the global economy is losing momentum, do not bode well for metals demand.
The strike was the second in the past month to hit Sierra Rutile, one of Sierra Leone's largest companies, following a week-long stoppage in October that led Iluka to cut its output forecast.
Days before Tauli-Corpuz arrived in Ecuador, indigenous groups and about 2,000 protesters marched in the capital Quito and handed the national assembly a proposed law that would ban large metal-mining projects.
China's biggest state-run aluminium producer has decided to make around 470,000 tonnes of annual output at units including Shanxi Huasheng and Shandong Huayu subject to "flexible" output arrangements.
