Print page

Print page

Achieve good top to bottom slurry suspension

Q: A general question regarding suspension of fine ore slurries, of the following properties: solids spg=2.9, mean dp=60 microns; liquid is 50wt% sulfuric acid at 100oC. slurry is 45wt% solids. Vessel is 90% full The vessel is brick lined, approx 16ft diam x 17ft T-T. Bottom head is ASME F&D, OD=204 inches,1/2" thick. There are 3 baffles made into "V" shape using bricks fastened to the vessel walls (ie, no spacing between baffle and vessel wall) The agitator is 40 HP, and there are 2 hydrofoil type impellers, approx 68 inch diam. I believe that they are A310'S. The impellers are spaced approx 68" apart. I do not know the distance from the bottom to the lower impeller, but I suspect it is about 35 -40". In your expert opinion, is this system adequate to achieve good top to bottom slurry suspension? The desired objective is to achieve as close as possible a uniform suspension within the vessel. Please give me your assessment and recommendations on how to improve this system?

A: As extensive as this description is, it is missing an important piece of information.  The rotational speed of the mixer is missing.  If the speed is 68 rpm, the mixer would effectively load the 40 hp motor and provide good solids suspension.  While "uniformity" is difficult to achieve, especially with an overflow for discharge, the mixer described should give good uniformity of the average particles.
 
    If the speed is less than 68 rpm, then increasing the mixer speed would improve the uniformity of the suspension.
 
    If the particles are larger than 60 microns or more dense than 2.9, then some particles may not may not be sufficiently suspended.
 
    The design as described should provide good suspension and reasonable uniformity.  Greater uniformity would require a larger mixer, but not much improvement would be expected.

Back to Ask the Experts