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<br />1 <br /> <br />t <br /> <br />1 <br /> <br />1 <br />1 <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br />1..~ <br /> <br /> <br />concentrate aze dependent upon the chemistry of the dissolved constituents in the water to be <br />treated, and the specific characteristics of the membrane (see Section 4.2.1.1 of TR-26). For this <br />project, a membrane capable of rejecting up to 85 percent of the NaCI equivalent will be used. <br />The ratio of permeate solution to concentrate for this project should reach a value as high as <br />65:35. The nanofiltration equipment for the interim treatment system will consist of a mobile <br />stand-alone operation. <br />Post Filtration Stage -This component of the operation will consist of a lima hopper, lime <br />slurry tank, and a lime feeder in combination with a continuously mixed reaction tank. Lime in <br />the form of ftne grained pebble quick lime will be fed from the lime hopper into the lime slurry <br />tank where the reagent will be mixed with water to form a slurry. The alkaline slurry will then <br />be fed at a controlled rate into the reaction tank. Due to the required process water flow rate and <br />consumption of alkaline reagent, the lime hopper will be required to hold a minimum of 5 tons of <br />quicklime. The lime slurry tank will be required to hold a minimum of 1,000 gallons of slurry. <br />The reaction tank will require approximately aten-minute residence time and as such will have a <br />volume requirement of 2,000 gallons. The pH of the process water will be rai:+ed to a value <br />between 9.5 and 10.0 while in the reaction tank. This rise in pH will facilitate the Hydrolysis and <br />production of insoluble hydroxide products from the vast majority of the remaining manganese, <br />and other constituents contained in the process water. As the process water doi:s not contain <br />large quantities of alumintun, the pH may be raised in one step rather than two. Simultaneous to <br />the occurrence of these hydrolysis reactions, a portion of the calcium in the lime will combine <br />with the sulfate and the fluoride in the process water to form insoluble precipitates. Furthermore, <br />this stage of the process will include asolid-liquid separation process. This porticn of the stage <br />will consist of one or more quiescent tanks where the previously formed precipita~:ed solids will <br />be allowed to settle out of the process water and form a sludge layer. As was pre~~iously stated, <br />this sludge material will contain the vast majority of the dissolved constituents from the process <br />water. This sludge layer will be removed from the tanks in a separate stage of the process. The <br />treated concentrate exiting the separation stage will have less than 5 parts per million of total <br />suspended solids. The addition of a polymer to the quiescent tanks could aid in the settling of the <br />fine-grained solid particles. The quiescent tanks will require a residence time of ~i minimum of <br />Baffle Mountain Resources, /nc. shepherd Miller, lnc. <br />i~.m,;;.b,o-;reiioa:a;yep.Own..a~..,iupn~re~...rP~.m~.~+ie~,sx 6 September l7, /999 <br />