RE: Pumping Bingham Plastics

From: <Steve>
Date: Fri Oct 08 2004 - 06:53:00 EDT


Thanks Jacques

as the slurry is typical metallurgical slurry (solids around 2.65), the pipe will be a bit smaller (I hope). Can do the same with thin (28 w/w) slurry through an 18" pipe, so hopefully baby poo will allow me to reduce a size or two, or so.
This is a new world to me, and I am curious to know if there are any typical transport velocities for semi-solids, other than those produced by optimisation. My gut feel is around 1 m/s. The concept of poo-hammer widens my eyes as the celerity will be high, but the viscous damping will also be high however. Not to mention vacuum relief/breaking, which with subsequent recompression could result in poo cannonballs.
I am led to understand pumping is a viable alternative to belt conveying, and the material is tailings, so the end condition is one of disposal/storage. With thin slurry, the traditional method is to build a dam, pump in the slurry, let the solids settle in the dam and return the supernatant liquid to the process plant. With baby poo I am told the procedure is to find some flat land, run the pipe to the centre and then aim it upwards. Make a volcano. As the heap builds, extend the pipe upwards. Presumably some form of skirt is required around the perimeter to contain and return runoff.
All very interesting.

Cheers

Steve

-----Original Message-----
From: Jacques Chaurette [mailto:jchaurette@fluidedesign.com] Sent: Friday, October 08, 2004 1:40 AM
To: <a href="/group/PipingDesign/post?postID=VDvKMnpIDSU_EyYVUTru_OD8Q9zaC3y-yYitV0CYfSnUshO5I17_MXtCKQCYBqnFFvwUkZGOkCsucSksOeJVbFfN_Q">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] Pumping Bingham Plastics

Steve, that's a whole lot of poo. Based on 700 tons per hour and assuming a consistency of 40% by volume and a specific gravity close to water, this corresponds to a flow rate of 7000 USgpm. You will need a 20" pipe at this flow rate.

You are going to need several positive displacement pumps, maybe some large progressive cavity pumps. As you know with positive displacement pumps the main sizing criteria are flow throughput (gpm) and viscosity, the pressure produced by the pump is normally higher than required and must be relieved. I suspect the pressure level required will be quite high in order to overcome friction for 12 km, the pipe will have to be very robust especially at the beginning of the system. To calculate the friction and th
ereforethepressurerequirementIsuggestyoudosomeresearchinbooksthatdealwit hfluidhandlinginthefoodsector.Iwonderifaconveyormighthaveacomparablecost toapumpsystem.

Cheers,

Jacques

Gents + 2

I have been requested to prepare some tails disposal pumping options
using thickened tails from a paste thickener.
The process consultant has told me to expect a process fluid with
Bingham plastic properties, a yield stress of around 100Pa and a
consistency of baby poo. Quantities will be around 700TPH solids and
transport distance around 12km.
All to be sorted by monday - no sweat - who wants a life anyway?
Before I bury my head in books (e.g. Wilson, Addie, Sellgren and
Clift, has anyone seen any good design references for estimating pipe
friction loss with this sort of stuff?
Will probably go to a recip type pump in order to be sure I dont wind
up with a frozen pipe because the thickener had an "episode".

Thanks

Steve



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