Blackstone Minerals details 'compelling' downstream PFS for Ta Khoa Refinery Blackstone Minerals Ltd (ASX:BSX, OTCQX:BLSTF, FRA:B9S)'s Scott Williamson talks Proactive through the outcomes of a pre-feasibility study (PFS) for the proposed downstream Ta Khoa Refinery in Northern Vietnam that confirms a technically and economically robust hydrometallurgical refining process. The PFS considers a refinery that can process up to 400,000 tonnes of nickel concentrate per annum over a 10-year life of operation and will require just under US$500 million in upfront project capital to construct. Quick facts: Blackstone Minerals Ltd Follow