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_ ..:. <br />' ....:. <br />1 <br /> <br /> <br /> <br /> <br />1 <br />C <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />Page 12 <br />TABLE 8 <br />RESULTS OF THE CONTINUOUS FLOW PILOT PLANT STUDY U51NG COMPLETE MIX REACTORS <br />Inftuertt Air Flux Complete Mlx Aeration Period Effluent <br />•~N ` /rtfi min Reactor Steae (mini _~ <br />t98 ~4.5 ~ 1 63 33 <br /> 2 125 31' <br /> 3 167 27 <br /> 4 250 25 <br /> 5 312 24 <br />179 6.2 1 63 21 <br /> 2 125 20 <br /> 3 187 17 <br /> 4 249 1 Bi <br /> 5 312 14 <br />171 8.8 1 63 16 <br /> 2 125 15 <br /> 3 187 16 <br />In the second phase of the study, the recovery of cyanlde from slurries was Investigated usi g a packed <br />tower. A schematic of the tower is presented in Figure 5. The tower was packed with about~m of either <br />50 or 75mm plastic media. The Influent distribution system consisted of a ceramic multiple weir trough <br />assembly and a demister. The media was supported by a multiple beam ceramic gas Injection plate. The <br />stripping column was about O.Sm In diameter and 6m In height. The parameters Investigated ingluded mass <br />transfer efficiency, media size, air to liquk) ratios, flooding characteristics, cyanide removal efficiencies, and <br />required packing height. A summary of the tower performance Is presented In Table 9. <br /> <br />TABLE 9 <br />PILOT PLANT STRIPPER TOWER TEST RESULTS <br />Test Run No. <br />- 1 2 3 ~ 5 6 7 6 <br />Slurry Fb <br />w;~hr) 2.37 2.37 1.94 2.17 2.54 2.1 2.21 2.33 239 <br />Air Fbw (m /hr) B45 B45 639 B39 B38 2126 2126 1484 1400 <br />No. of Tower Passes 1 1 1 1 1 1 1 1 2 <br />Air/Uquld Retb 337 357 432 367 330 1012 662 ~~ W7 586 <br />Influent WAD CN" 182 162 156 166.4 766.4 1924 192.4 197.6 19.1 <br />Effluent WAD CN- 36.8 24.5 45.1 23.5 22.7 13 13.7 18.3 5.6 <br />Test Run No. <br />- ~ _ 10 11 12 13 <br />Slurry Fb <br />w;mTlhr) 236 245 4.1 4.0 4.17 4.0 3.9 3.7 S.0 4.8 <br />Air Fbw (m /hr) 1815 1615 2137 2137 2561 2561 1369 1364 1662 1682 <br />No. of Tower Passes 1 2 1 2 1 2 1 2 1 2 <br />Alr/Uquld Ratio 884 &59 671 534 81B 645 349 369 336 365 <br />In6ueni WAD CN- 223.8 22.0 174 25 197 22 178 35 164 35 <br />Et6uent WAD CN- Z1.Y 6.0 29 7.0 28 7.0 43 13 40 14 <br />At air to liquid ratios of about 500-700, Influent WAD cyanlde concentrations ranging from 17a-224 mg/I were <br />ettectNely reduced to <10.0 mg/I In two passes of the tower packed wfth the 75mm media. With the 50mm <br />