2021-06-14_REVISION - M2012032 (3)

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Ouray Silver Mines Inc. Technical Revision 15 May 24, 2021 1 Introduction This Technical Revision 15 (TR)requests the following revisions to the Revenue-Virginius Mine (Mine)Division of Reclamation,Mining,and Safety(DRMS)Permit No. M-2012-032 (Permit). 1) Recertification of the mill at the Revenue Mine site. This TR request describes the reasoning,characteristics, construction,and operation measures associated with the mill recertification at the Mine. Supporting information is presented under the following sections,background information(Section 2),mill design discussion(Section 3), mill construction,modifications, and test operations (Section 4),water and slurry handling systems and environmental protections(Section 5),chemical handling system and containment (Section 6),and tailing chemistry and water quality at the tailings embankment(Section 7). As of the date of this TR,the mill is not in operation. The certification approval for the mill was originally granted by the DRMS on January 11,2016. In February 2017,the Mine submitted TR- 09 to DRMS,which allowed for changes in the mill process for improved recovery and bringing the mine back into full production. Within the crushing circuit, TR-09 allows for jaw crushers and a rod mill to replace the pre-existing cone crusher that would clog with fines. TR-09 also permitted two Derrick screens to replace a poorly sized cyclone circuit, addition of another conditioning tank to the zinc flotation circuit,rougher flotation tank cells(with air blowers)to the bulk lead and zinc circuits,and two additional cleaner flotation tank cells for the lead circuit. In addition to the changes in equipment,TR-09 also requested changes in the chemicals used in the milling process. The chemicals that were approved for use in TR-09 are: Xanthate(SIPX,Zn collector),AERO 242 (Pb promoter),AERO 3418A(Au Pb collector),Oreprep F-549 (aka MIBC,used as a frother),Flocculant(Tails Thickener), sodium metabisulphite(Pb depressant), CuSO4(Zn activator), and ZnSO4(Zn depressant). The mine received approval for TR-09 from the DRMS on March 10h,2017. On April 9th, 2021,the mine received notice of mill de-certification from the DRMS citing mill reconfiguration, equipment modifications,and a change to chemicals used in the metallurgic process as the reasons for decertification. Upon conditional approval of Technical Revision 15, the mill will be allowed to process ore to optimize the milling procedure through adjustments to equipment,chemicals,monitoring procedures,and tailings management so that permanent operations can take place. During mill commissioning,representative tailings samples will be subject to Synthetic Precipitation Leaching Procedure (SPLP)and acid-base accounting with sulfur forms to allow placement in permitted tailings storage facilities(TSF)and/or resale of blended waste rock and tailings(Revenue TSF or Atlas TSF). This Certification applies only to the environmental protection items of the mill;it does not apply to other environmental items of the mine permit. This Certification document is meant to satisfy the requirements of Rule 7.4 of the Hard Rock/Metal Mining Rules. Page 3 of 12