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ADS-RPT-2021-14 <br />ESS-Nederland Mine _ 60 <br />November 4, 2021 <br />200 Lake Drive, Glasgow, DE 19702 302.731.1700 Fax 302.731.1701 <br />www.gravertech.com <br />Proprietary and Confidential <br />Page 7 of 8 <br />Figure 2. The Zn kinetic test at a V/m ratio of 1000 mL/dry gram of media. The test is limited by <br />the method detection limit. A 10-minute contact time (at a very low concentration) only <br />removes about 32% of the contaminant. At 60 minutes the % removal is much higher, ~85%. <br />Note that the lines drawn are just connecting the dots to emphasize the change in efficiency. <br />The connecting line is not a fit for the data; it is just a visual cue. <br />This analysis demonstrates that the media does remove a significant amount of both Cd and Zn <br />but may have some kinetic hinderance. These tests were completed in a batch-like style which is <br />not as efficient as a column test. In a column test, media is not distributed randomly in the fluid. <br />Instead, the fluid passes through a bed, making the removal significantly more efficient. Based on <br />the data gathered, the standard recommendation of one to three minutes empty bed contact <br />time(EBCT)for HMRG is not likely to be effective. A ten-minute contact time shows some removal <br />and is more practical than a 60-minute contact time. A pilot study with a 10-minute EBCT is <br />recommended to increase confidence in the ability for the media to successfully remove the <br />contaminants with the desired engineering design. <br />5.0 Conclusions <br />Graver has investigated the ability of MetSorb® HMRG to remove Cd and Zn from the water at the <br />Nederland mine Cross site. MetSorb® HMRG has a capacity of over 15 mg/g for Zn and over 0.14 <br />mg/g for Cd. The low concentration of Cd makes the HMRG kinetically hindered; a contact time