Calculate Froth Factor

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Sealing, drives and hoppers Any of the normal seal types such as gland and expeller can be utilised for froth pumping. A typical hopper for froth pumping is shown in FIGURE 3. Belt or direct drives are both suitable, but it is preferable to use a variable speed drive to cater for changes in the froth characteristics that occur due to the normal and variable output of the �otation cells and to also allow for duty changes, different throughput of ore, grinding size and duty changes etc.

Other froth pump applications Pumping froth highlights some of the problems that occur at the inlet of centrifugal pumps and the need for proper system design and pump selection. Generally, if the �uid is able to enter the impeller it typically can be pumped successfully. Other types of pumping applications that can present problems at the inlet and related operability problems are high yield stress, non-Newtonian, paste slurries, such as thickened tailings and viscous froths, such as oil sands bitumen froth. While these particularly difficult to pump slurries may have more severe corrections than those provided

Weir Minerals Technical Bulletin - #28

for mineral froths, the large inlet, �ow inducing vanes and larger passageways of the Warman �ow inducer impeller have shown the ability to handle these diffi cult slurries better than conventional slurry pumps.

FIGURE 5 - Froth pump selection

Do’s and Don’ts of froth pumping •

Do select the correct pump size

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Do minimise the head

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Do speed the pump correctly

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Do provide a proper enlarged pump inlet

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Do allow adequate space for pump maintenance

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Do allow a large Over�ow in the hopper in case of spillage’s

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Don’t utilise Froth Volume Factors over 1.8

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Don’t over-speed the pump

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Don’t impede froth �ow into or out of the pump

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Don’t allow the �ow into the pump hopper to entrain further air in the hopper

FIGURE 6 - HRf and ERf selection chart

FIGURE 4 - Froth characteristics and NPSH

Note: 1. HRf & ERf are constant over �owrange 2. HRf & ERf also include effects effects of fine solids 3. STD = Standard open froth impeller 4. QU1 = Flow Flow inducer open froth impeller

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