Sarytogan Graphite Ltd (ASX:SGA) has seen its share price plunge on the release of a prefeasibility study (PFS) for its flagship project in Kazakhstan – despite claims of exceptional returns for three different product types – with investors instead eyeing downstream operational costs of more than US$1000 per tonne. At 13:33 AEST, the company’s shares were trading at 12 cents, a fall of 22.6% since the market opened. The PFS outlined three potential products for the Sarytogan Graphite Project: microcrystalline graphite (with recoveries of more than 80%) at up to US$791 per tonne, ultra-high pu…