I need to pump a thick slurry from a tank. The slurry can be pumped, but won't flow well enough that I can use a suction pump from outside the tank. Normally, I'd use a centrifugal immersion pump that can be drawn from the tank for service. But with the thick slurry I need to use a PD pump.

One option that I'm looking at is a monopump housed in a long pipe, so the rotor/stator packet is submerged and operated by a long shaft in the pipe. But this will probably get expensive and I'm open for other options. Another consideration is ease of service, the immersion pump linked above would have to be lifted with a crane out of the tank for service.

The application is agricultural / bio-energy; tank depth is 4m.

So I'm looking for a PD pump that is ...

  • capable of pumping thick slurries
  • can be put into my sump pump and retrieved for service with low effort (which probably rules out long driveshafts)

I'm mostly hunting for ideas, no need for a concrete product recommendation.

  • $\begingroup$ No opportunity to make a gravity feed from the bottom/lower side of the tank into your centrifugal pump? $\endgroup$ Jan 23 '15 at 14:29
  • $\begingroup$ In prinvipal yes, (plant's not yet built) but I'd like to keepo the civils simple $\endgroup$
    – mart
    Jan 23 '15 at 18:15

I've worked quite a bit with vacuum pumps in the past and they certainly could get your slurry out of the tank however a complete rig can run in the $10,000 range.

Another less expensive option is an airlift pump. This is nothing more than a tube that has compressed air blowing through it which in turn 'pushes' the slurry to the top of the pipe. It does so because the volume in the pipe is substantially less dense than the slurry surrounding the pipe.

It will not carry the fluid vertically very high so would require multiple steps to make it 4m. Certainly a disadvantage, however these things are cheap and don't break.

Option 3 would be to use a basic trash pump. They are inexpensive and can handle a 4m lift, however getting them primed can be difficult. Options on this include a check vale system (but they 'leak' and lose prime over time), a valve system (also 'leaky'), or a backflow from the sump tank so the system can be filled with liquid before firing the trash pump. The backflow is probably the easiest to perform, and would allow for easy priming of the pump with only the most basic of training.

Then there is a diaphragm pump, they work extremely well and can lift your slurry without issue if you purchase one with the correct rating. The only drawback is they consume vast quantities of compressed air and are not terribly efficient.

Finally you could consider a diaphragm pump as a primer for a standard centrifugal pump. This would allow for intermittent use of the diaphragm pump for priming purposes and the use of an efficient trash pump for primary fluid transfer.

Putting it all together, a trash/centrifugal pump would seem ideal with some type of priming system. Backflow from the slurry container would be the easiest but a diaphragm pump would do nicely as well. These units are inexpensive, easy to work on, pump a great deal of liquid quickly, and can safely handle 'dirty' slurries if need be.

Hope this helps!


I'm not a pump expert but I would have thought that an Archimedes screw pump would be ideal in such a situation.

  • $\begingroup$ nah. Nice for lifting stations but doesnt create enough head to pump an appreciable distance after that. though you are right in that screws are well suited for conveying slurries. $\endgroup$
    – mart
    Jan 21 '15 at 21:54
  • $\begingroup$ I see. Once outside the tank, couldn't the slurry be easily pumped onwards with a different pump that doesn't need to sit in the tank? Would this open up more options and make it easier to access/maintain? $\endgroup$
    – jhabbott
    Jan 21 '15 at 22:04
  • $\begingroup$ in principal yes, I'd just like to have few different devices. Keep it simple if possible. $\endgroup$
    – mart
    Jan 21 '15 at 22:37

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