Permission to use the attached copyrighted document provided to the U.S. EPA by email dated 

November 3, 2009 from J. Sloesen, Weir Minerals Netherlands b.v., to Steve Souders, U.S. EPA. 
The fly ash disposal area: ready for soil 

covering. 

The problem: hardened slurry obstructing the 

bladder.

GEHO® Info for sales representatives 

Volume 12, No. 2, March 2002

Water barrier dampener 

Sloped disposal 

Elektrarna Ledvice (ELE), in the Czech 

Republic, deposits residue from coal 

combustion and flue gas desulphurisation at a distance of 4,700 metres 

against the slopes of an open pit in a 

manner, which meets Czech environmental legislation. 

GEHO® PUMPS met the challenge to 

develop a concept, design, build, commission, performance test and warrant 

the disposal system. It comprises the 

preparation, pumping, transportation, 

distribution and dry disposal of a hardening (from CaO reaction) slurry with 

entrained crushed slag in a rather humid 

and cold climate. A large section of the 

sloped disposal has been filled with a 20 

metres high stack as seen in the photograph. After it is covered with soil and 

vegetation, the landscape will be as it 

was before the mining of brown coal. 

The stack has proved to be so stable 

that soil sealing is no longer a requirement. It did not take much more than an 

extension of the pipeline to prepare the 

adjacent area for disposal. 

Solidification 

GEHO® PUMPS designs guidelines for 

equipment and systems that handle selfhardening slurries, which require the 

avoidance of stagnant areas. 

The ELE pumps were fitted with a 

dampener with nitrogen precharged 

bladder to reduce the pressure variation 

at the discharge flange for flow and acceleration induced pressure disturbances. 

We felt that the special shape of the 

housing and bladder and the resulting 

wedge action would keep the dampener 

clear of product. We were wrong, so we 

set out to resolve the problem. 

Solidified product formed scaling and 

obstructed the free movement of the 

bladder, which failed prematurely. 

Water barrier 

The operators had to remove the entire 

dampener weekly for descaling. The 

removal by chiselling of a four centimetre build up of compacted and stone-
The solution: a spool pipe between manifold and dampener. 

hard slurry was labour intensive and not 

easy. 

None of the GEHO® trials, such as a 

topdown mounting, which put the slurry 

inside the bladder, improved the situation. We considered the use of various 

dampener models available on the market and especially the through-flow 

types. Not a single one was suitable and 

without unacceptable drawbacks. 

A level controlled air vessel would have 

been the solution except that it was a 

costly retrofit. The problem was then 

resolved with the installation of a spool 

pipe between the manifold and dampener. The intermittent injection of water 

now provides a continuous water barrier 

between the bladder and the live slurry. 

Empirical proof of concept 

A commercial plunger (jet cleaning) type 

pump is used for the water flushing. Its 

flow rate is small and independent of the 

prevailing pipeline operating pressure. 

The fixed line shown served to sample 

the contamination of the water by slurry. 

With each flushing cycle, the clear water 

level is pushed down the spool. 

It creates a fresh water buffer that 

gradually becomes contaminated due to 

mixture with slurry solids. When reaching a certain level of contamination, it is 

displaced into the pump manifold during 

the next flushing operation. 

The flushing interval time for pipeline 

start-up and operation were empirically 

determined. The water consumption 

needed for keeping the water-slurry mixture below the sample point and ultimately out of the dampener did effectively decrease the slurry solids concentration a negligible 0,06%. 

The water barrier design did eliminate 

the need for descaling and resolved the 

bladder failure problem altogether. 

The dimensions of such a spool pipe will 

obviously vary with the dampener size 

and also with the pipeline pressure operating range. 

The development is one of the many 

experiences gained by GEHO® PUMPS 

from the supply of tailings disposal systems. 

Weir Minerals Netherlands b.v. 

P.O. Box 249, NL-5900 AE Venlo 

Phone: +31(0)77-3895200 

Fax: +31(0)77-3824844 

Email: weir@weirminerals.com

Website: www.weirminerals.com

Copyright © 2002, Weir Minerals Netherlands b.v. All 

rights reserved.