Mixers tank design

In continuous flow, the only point in the tank that must be equal to the feed composition for steady-state operation is the drawoff point. Thus, if the drawoff point is at the bottom, middle, or top of the tank, different average tank compositions can result, even though the composition of the entrance and exit streams are the same. If the mixer is large enough to provide complete uniformity of all the solids, including the coarse particles as well as the fine particles, then the drawoff point does not make any difference in the composition of the tank. However, if the mixer is designed only to just suspend the solids to the drawoff point, then tank compositions vary widely, depending upon the drawoff conditions. 

By calcnlating the residence times of the various solids in the tank and relating them to their corresponding extraction curves, the total uranium extraction for the entire train of mixers was estimated. The cost of the various mixer options, the prodnction efficiency net resnlt, and the cost of the installation and tank design conld be combined to yield the economic optimum for the plant. 

Because emulsion polymers are not true solutions, they separate if allowed to stand for a prolonged period of time. Therefore, emulsion polymers must be mixed with a drum mixer, tank mixer, or tank recirculation package prior to use. A bulk tank or bin recirculation package should be designed to circulate the tank s contents at least once per day to prevent separation. Emulsion polymers contained in drums should also be mixed daily. 

SEP mixers are hori2ontaHy installed on the side of the tank and near the bottom. By rotating the propeller, a spiralling jet is produced (Pig. 27) near the tank floor which provides the desired thmst to dislodge and entrain the sediments. SEP mixers should be designed to provide the suspension velocity at the farthest distance on the tank floor. 

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