Midas Gold Provides Metallurgical Update on its Golden Meadows Au-Ag-Sb Project, Idaho - Seite 2

Mineralogy

Mineralogical studies, including QEMSCAN, confirmed that antimony occurs as stibnite and that, when present in economic quantities, is coarse enough for good flotation recoveries at the chosen grind, while gold primarily occurs in solid solution in pyrite and, to a much lesser extent, arsenopyrite. Except where the mineralization is oxidized, free gold is relatively rare. Overall, the sulfide content of the deposits is relative low, with West End having relatively less sulfides than Hangar Flats and Yellow Pine.

Comminution (crushing and grinding)

A wide spectrum of comminution testing was completed on the different composites to determine appropriate crushing parameters, as well as SAG and ball milling conditions. Overall results confirmed a conventional crushing-SAG-ball mill combination as the optimal comminution circuit. The Yellow Pine and Hangar Flats mineralization are broadly similar and have similar grindability characteristics, whereas the West End mineralization is somewhat more resistant to SAG milling and may require additional crushing. The PFS design parameters (excluding any additional crushing that may be required for West End) to be used in the PFS are anticipated to be single stage crushing with a 2m x 1.5m opening 373kW (79"x59", 500HP) jaw crusher, primary grinding in one 9.1m x 4.9m 7,500kW (30' x 16', 10,000HP) SAG mill, followed by a single 7.3m x 12.2m 13,500kW (24' x 40', 18,100HP) ball mill for secondary grinding to 80% minus 75 microns prior to flotation.

Flotation

Per the currently conceptualized mine plan, the substantial majority of the mineralization is sulfide and transitional material (~86%), with the balance of the mineralization being oxide ores from the West End deposit. Extensive flotation test work, including multiple locked cycle tests, was undertaken on a variety of global composites from each deposit representing the PEA established average deposit grades of gold, sulfur and antimony. Test work confirmed that the optimal recovery circuit for sulfides involves a conventional sequential flotation circuit of stibnite (antimony) flotation (where antimony grades warrant, in approximately 14% of the sulfide feed at grades generally >0.1% Sb) followed by flotation of other sulfide minerals into a gold-bearing sulfide concentrate. Where warranted, tailings from flotation will undergo agitated leaching to recover additional gold, while oxide material will bypass flotation and go straight to agitated leaching. Due to the high carbonate content of West End materials, a cleaning flotation stage will be undertaken to reject carbonates from the concentrates. While further value to the project may be attainable through the use of additional metallurgical processing, the flow sheet selected is designed to constitute the minimum technical risk and, as such, uses only technologies that are in wide use industry-wide.