Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering

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Pumping Considerations (2 replies and 1 comment)

B
Pump Guy
8 years ago
Pump Guy 8 years ago

Hi, I am pump guy from Florida. I apply pumps in mining applications. I wanted to clarify the formula for converting dry solids to a slurry flow. In the formula ,

Qm = 4  x  dry solids ( tons/hr )/Cw  =  Sm

Where is 4 derived from ? and how do I solve for Cw =  Sm . Is this to mean use either Cw or Sm ?

Thank You

David
8 years ago
David 8 years ago
Like

Hi, i think you got a typo in your formula.  Read this PDF here and I think you will find your answer.  

Arising from an analysis of the test results, the following observations can be made:

• When pumping settling slurries, the head and efficiency are reduced by the same ratio below that obtained on water. Note: It was observed that the efficiency drops at a greater rate than the head when the volumetric concentration is very large. The correction formula has been adjusted to allow for this.

• When pumping settling slurries the “best efficiency point” does not change.

• When pumping settling slurries, the head and efficiency ratios were found to be independent of flowrate.

• When pumping settling slurries, it was observed that the head and efficiency reduction ratios were virtually independent of pump size and specific speed.

• When pumping setding slurries, the head and efficiency reduction ratios remained the same regardless of rotational speed of the pump.

• For a settling slurry, the BH P of the pump will be directly proportional to the mixture specific gravity.

It is important to appreciate that there is a maximum concentration for a given slurry beyond which the pump may not “deliver,” if only for the reason that it is approaching the limit set by the “voidage” between the particles. The greatest concentration is obtained when the voids among the larger particles are partially filled with smaller particles. The maximum concentration of randomly packed particles which a pump can handle is on the order of 50 percent by volume (Cv).

To illustrate this, a centrifugal slurry pump can easily handle a magnitite/water slurry of Cw = 60 percent and Ss = 5.2, since by calculation, this would give a Cv = 22.4 percent.

The same pump, however, would have difficulties in handling a bituminous coal/water slurry of the same Cw = 60 percent, but having a much lower Ss = 1.3 since by calculation, this would give a Cv = 54 percent.

For heterogenous slurries, the power will be directly proportional to the specific gravity of the mixture and can be determined from the equation:

IN THE PDF HERE BELOW:

Slurry-and-centrifugal-pumps.pdf

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David
8 years ago

Also http://www.weirminerals.com/pdf/Slurry%20Pumping%20Handbook%20-%202009.pdf and http://www.pumpfundamentals.com/slurry/WeirSlurryPumpingHandbook.pdf

David
8 years ago
David 8 years ago
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Have you checked out http://www.pumpfundamentals.com/ and https://groups.yahoo.com/neo/groups/pumpfundamentals/info

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