2021-06-14_REVISION - M2012032 (3)

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Ouray Silver Mines Inc. Technical Revision 15 May 24, 2021 will be added to the circuit in 2022. A list of tanks described in this section can be found in Table 1. All processes from the rod mill downstream are fully wet. From the ball mill discharge tank or slurry storage tanks slurry is pumped to the 2 Derrick stack sizer screens,which size to p80 of- 130 micron. These screens replaced the previously used hydro cyclone. Undersized material is sent to the Pb conditioning tank(1064 gallons).Oversize material is circulated to the ball mill where it is ground and returned to the screens for sizing. The ball mill reduction takes place in a wet enclosed ball mill. Sodium metabisulfite(pH control&Zn suppressant),Zinc Sulfate(Zn suppressant),and Lime(pH adjustment) are introduced into the process in the ball mill. 3.2 Lead Concentrate In the Pb conditioning tank,process water,Aerofloat 242,Aerophine 3418A, and MIBC are added to promote the flotation of Pb and Ag while depressing the Zn to prepare for the concentrate separation in the lead rougher flotation cell(1320 gallons). The rougher flotation cell mixes air into the slurry with a rotor so that Pb can adhere to the bubbles and float to the surface. The rougher flotation cell feeds tailings from the bottom of the cell into Pb rougher scavenger flotation cells which consist of two sets of tanks(1320 gallons each)with three rotors in each tank(these tanks will also have two products -a concentrate and a tails). The concentrate goes to the Pb cleaner flotation cell. The tails from rougher scavenger cells report to the Zn rougher feed. The concentrate comes off the top of the rougher flotation cell and is fed to the Pb cleaner flotation cell or Pb cleaner column determined by recovery/concentrate grade. The slurry then enters Pb cleaner floatation cells(unless bypassed to the Pb cleaner column) which consist of two banks that both have two tank cells(I"cell 449 gallons,2°d cell 290 gallons). This step also creates two products—concentrate and tails. The concentrate reports to the Pb cleaner flotation columns. The tails from bank#1 tank#1 report to the bank#2 tank#1. Tails from bank#1 tank#2 goes to bank#2 tank#2. Tails from bank#2 tank#1 goes to bank#1 tank#2. Bank#2 tank#2 tails report to the Zn rougher conditioning tank(which is mislabeled on drawing 300-PI-004). Concentrate from the Pb cleaner flotation cells reports to the Pb cleaner column(214 gallons). Like all other tanks in the circuit,the Pb cleaner column creates both a concentrate and a tail. The tail from the Pb cleaner column are pumped back into the Pb cleaner flotation tank cell#1. The concentrate from the Pb cleaner column reports to the Pb concentrate thickener. Process water and flocculant are added to the slurry at the Pb concentrate thickener. After the Pb concentrate thickener, material reports to the Pb concentrate filter feed tank(933 gallons). From the Pb concentrate filter feed tank,the concentrate is pumped to the Pb concentrate filter. Water removed from this step is sent to the filtrate water tank. The Pb concentrate is sent to a screw conveyor that feeds the bagging system.Once bagged the Pb concentrate is trucked off site to be sold. An SDS will accompany the bagged product to final delivery. Offtake is sold to a third party FOB mine warehouse and OSMI does not own the product once the bags are loaded for shipment. 3.3 Zinc Concentrate Page 6 of 12