"The mining sector isn't close-minded to new revisions of the taxation system, if done with prudence," said Pedro Francke, Castillo's economic adviser.
China is releasing metal from state stockpiles as part of its campaign to restrain prices after factory inflation in May hit its highest level in 13 years.
Ivanhoe says DRC mine's first 3.8mtpa concentrator is now fully operational and pre-production ore stockpiles reach 3.4m tonnes grading average 4.78% copper.
A jump in demand for traditional lead-acid car batteries and lingering freight problems have created shortages that have been felt most acutely in the huge US automotive sector.
Company approved the final construction and development of its cobalt operations in the US state of Idaho, with the first production expected in mid-2022.