1992-04-02_REVISION - M1988112 - Laserfiche WebLink

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Before further discussion please review Fig. 2 (and forgive the sketch). Currently we generate 1200 gpm of tailings containing approximately tOQ ppm CN-. In addition there is a tailings pond of approximately 30 x 108 gallons containing approximately 85 ppm CN and a collector pond of 2 x 10 gallons containing 40 ppm CN . During this initial phase of two weeks we shall be required to add 5 lbs. Cy7ox per minute to remove CN- from the ponds and an additional 5 lbs. CyTox per minute to ensure that very minimal amounts (1-tOppm) CN' are present in the tailings. Thus, for two weeks, we shall apply 10 lb./min. CyTox to our system at two points (places). These application points are illustnated in Fig. 3 (again forgive the sketch). Application Point 1. Immediately all of the ore has been processed, and within the mill system, CyTox shall be added as a granuldr powder at the rate of 5 lbs./min. It shall be delivered by a variable speed screw. -Said powder, which dissolves instantaneously, shall be very turbulently mixed with the slurry for five minutes as it is transported at 1250 gpm through a pipe to the AVR. Within the AVR a further 20 minutes of turbulent mixing shall occur before being piped to the tailings-pond. The total reaction time shall thus be approximately 30 minutes by which time we anticipate a reduction from 100 ppm to 10 ppm CN-. Within the tailings pond we anticipate the comlexing of a further 5 ppm CN'. Application Point 2. Leaching through the tailings pond to the collection pond occurs at 1200 gpm. A11 leach is collected and transferred to a feed-pipe which itself feeds the collection pond. Into this pipe we shall again "screw" 5 lb./min, CyTox. This action shall neutralize the collection pond and, since this pond feeds back to the settling pond, naturalize it also. B. Stage 2. Once both ponds are neutralized the only problem remainiing will be the continual neutralization of the tailings. At that time, addition point 2 shall be eliminated and addition point 1 shall continue in perpetuity. We estimate that the time required to reach "steady-state" shall be two weeks. Two further general points need to be made: 1. When Ca(CN)Z is used instead of NaCN then obviously CaSO~ is produced in the reaction rather than Na SOS. But in both cases considerable amounts of Ca or Na are tied into the zincferro cyanide compound which, as said earlier, is stable over a wide pH range. 2. The CyTox treatment causes the generation of 1.3 lbs. of precipitate for every ton of ore processed. So the tailings pond which now receives 5000 tons of fine silt per day will have a further 3.25 tons per day of precipitate added (0.065%) continuously with the "silt". 3