2021-06-14_REVISION - M2012032 ‎(3)‎

• Permit No: M2012032
• IBM Index Class Name: REVISION
• Doc Date: 6/14/2021
• Doc Name: Decision Date Extension Request
• From: Ouray Silver Mines, Inc.
• To: DRMS
• Type & Sequence: TR12
• Email Name: LJW
• Email Name: ACY
• Media Type: D
• Archive: No

Ouray Silver Mines Inc.
Technical Revision 15 May 24,2021
Contents
IIntroduction...................................................................................................................................3
2 Background Information...............................................................................................................4
3 Mill Design Discussion.................................................................................................................4
3.1 Crushing..............................................................................................................................................5
3.2 Lead Concentrate................................................................................................................................6
3.3 Zinc Concentrate.................................................................................................................................6
3.4 Tailings................................................................................................................................................7
4 Mill Construction,Modifications, and Test Operation.................................................................8
5 Water/Slurry Handling Systems and Environmental Protection..................................................9
5.1 Coarse Ore Tunnel, Crusher Gallery,Decline and Mill Tunnel.............................................................9
5.2 Filter Building......................................................................................................................................9
5.3 Thickener...........................................................................................................................................10
5.3 Reagent Room...................................................................................................................................10
6 Chemical Handling Systems and Containment..........................................................................10
7 Tailing Chemistry and Water Quality at the Tailings Storage Facilities....................................I I
Fi ures
Figure 1 —Mill Process Flow Diagram
Tables
Table 1 - List of major tanks in mill.
Table 2 - Volume of reagent tanks compared to the volume of secondary containment.
Table 3 -Reagent dosing rates in the flotation circuit.
Table 4 - Sizes of day tanks and mixing/storage tanks in gallons.
Table 5 - 2017 Multi-element analyses of concentrate and tailings.
Table 6- 2017 ABA of tailings.
Appendices
Appendix 1 —For Construction Drawings
Appendix 2—Reagent SDS
Appendix 3—2015 Tailing Geotechnical Testing
Appendix 4—Groundwater Quality Data
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