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FLSmidth USA,Inc. <br /> 7158 S FLSmidth Drive • Midvale• UT 84047-5559 • USA M ' D T H <br /> 2.0 Introduction <br /> Ouray contracted FLSmidth USA Inc. (FLS) to conduct thickening, rheology and filtration <br /> testing on a zinc rougher tailings sample for their Revenue Mine project in order to confirm <br /> process design. FLS completed testing in their Separations Laboratory located in Midvale, <br /> Utah during April 2017. <br /> FLS engineers accomplished the thickening objectives by screening flocculants, determining <br /> feedwell design criteria related to effective feed conditioning for flocculation, conducting <br /> dynamic settling tests to determine sizing and design criteria, and by measuring thickened <br /> tailings rheology to determine required rake torque and predict underflow manageability. <br /> FLS engineers accomplished the filtration objectives by simulating FLSmidth's filter press <br /> technology with a filter feed solids concentration of 60-wt% solids, determined by <br /> thickening and rheology test work. <br /> 3.0 Equipment and Testing Methods <br /> The following procedures were used during test work to gather the data which was then <br /> correlated to size the thickeners and filters required for the conditions tested. The sample <br /> characterization was done for each sample tested. <br /> 3.1 Sample Characterization <br /> Any sizing from testing is based on the characteristics of the sample tested. Without this <br /> data included in the basis of design, the sizing and predicted performance cannot be <br /> validated for the specified feed stream. Characterization requires the following <br /> measurements as a minimum; particle size distribution (PSD) (+100µm, -20µm), solids S.G, <br /> liquor S.G., suspended solids concentration, and pH of the original slurry sample. <br /> The sample characterization was performed by FLSmidth. FLSmidth Dawson metallurgical <br /> lab produced the zinc rougher tailings sample. The separations lab received a 30 gallon <br /> bucket of sample. The slurry was agitated to give full suspension for sample collection. A <br /> small sample, collected from the agitated slurry provided characterization analysis. Particle <br /> size analysis was determined by laser diffraction using the Malvern particle analyzer. <br /> 3.2 Flocculent Screening and Flux Testing <br /> Flocculent type can have a significant effect on thickener performance and as ore types can <br /> change frequently it is always prudent to monitor flocculent types for improved <br /> performance. <br /> Flocculent screening was performed by FLSmidth on three flocculants, and the best <br /> flocculent selected for the test work shown in this report. Flocculent selection was based on <br /> their success in similar applications. <br /> Flocculent screening presents a qualitative and quantitative comparison for a range of <br /> flocculants typically effective in similar processes. Observations made during flocculent <br /> screening include flocculent structure, settling rate, overflow (O/F) clarity and general <br /> settling characteristics. <br /> Flocculent solution is added drop wise to 250-mL graduated cylinders that contain slurry at <br /> a solids concentration that facilitates flocculent dispersion, while providing a qualitative <br /> Page 1 4 <br />