The WEMCO® Attrition Machine (Sand Scrubber) was originally developed in conjunction with Owens-Illinois Glass Company to perform a needed scrubbing step in the treatment of glass sand. It met the requirement very well, is now used extensively by Owens-Illinois as well as other glass sand producers, and has spread to various other applications.
Principle & Design
In designing the machine, the object was to achieve the strongest possible attrition of particle surfaces without reduction of particle size. This was done by introducing the feed at high density, 70 to 80% solids in the case of sand, with a consistency approaching concrete mix. Then, in place of simple rotary motion of the pulp, the agitation was made turbulent by reversing the pitch of alternate sets of impeller blades, and folding of the pulp was induced by making the tank octagonal shaped instead of circular.
The most important function of the Attrition Machine is the scrubbing of particle surfaces to remove film or coating.
Applications
Flotation
Particle surfaces are cleaned prior to flotation to increase selectivity.
Glass Sand
Iron oxide coating on silica sand is removed by attrition and flotation to produce a low-iron glass sand.
Industrial Sand
Blasting sand and fracturing sand are scrubbed to disperse contaminating soft particles and other impurities, which are then removed by desliming.
Ores and Various Minerals (Phosphate, etc.)
Impurities are freed and they can be removed with the help of Spiral Classifier or Hydrocyclone.
Dissolving
The use of the Attrition Machine to dissolve solids reduces contact time by continuously exposing fresh surfaces to the solvent.