### 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.GEHO® piston diaphragm pump for fly ash transportation at Bayswater Power Plant. GEHO® Info for sales representatives Volume 7, No. 2, April 1997



# Dry disposal of fly ashes

Dense ash slurry benefits

Fly and bottom ash generated by coalfired power plants is generally transported hydraulically, pneumatically or by mechanical means (trucks, conveyors), to ash dumps, natural ash dams or artificial ash dams. The hydraulic transport of fly ash has been largely in the form of dilute slurries ie. 10-30% solids by weight. However, continued use of dilute slurry pumping has been questioned and environmental constraints on ash disposal have limited the options available and increased costs. The problems are substantially eliminated by preparing ash slurry at high density ie. low water content for discharge onto a sloped disposal site where the deposit stabilises.

GEHO® piston diaphragm pumps are well suited for transporting high concentrated slurries, making a "dry" disposal method possible. The highly concentrated, thick slurry runs out slowly over the disposal site after leaving the pipeline. Normally there is no water leakage, depending on the characteristics of the ash. The high density disposal method offers several major advantages, such as:

• Dense fly ash slurries use significantly less water than dilute slurries.

• The need for an ash dam water reclaim system and return water lines

can often be avoided with the natural retention of slurry water by the dense ash slurry.

• When used as mine backfill, it does not add to the mine dewatering capacity and solids loading of the

mine water.

• Dense fly ash slurries do not flow outGEHO® hydraulically driven pist on pumps for fly ash pumping at MUJA Power Station (decommissioned). to form a horizontal surface, but create a

shallow cone from the point of discharge.

• A typical slope of 2-6% will be generated in the ash dam; the ash will dry out to form a fairly solid surface, unaffected by rainfall (erosion) and not prone to dusting in windy conditions.

• The energy savings to run pumps can amount to 50% or

more.



### Score against conveyors

GEHO® PUMPS has won a major contract to design, supply and install three GEHO® ZPM 800 ash transport pumps at Ledvice power station in the Czech Republic. The positive displacement piston diaphragm pumps will transport

154 m 3 /h of ash slurry 4,300 m from the power station to a 1,000 m long, 100-200 m wide and 29 m heigh ash disposal site located against a 15E slope. The dense phase slurry will be transported through 150 mm diameter pipes at a maximum

solids concentration of 72% and an operating discharge pressure of 9.3 mpa.

The pumps, 3 x 50% capacity, form part of the ash slurry preparation and transport system, with detailed engineering and construction being carried out by Chepos Engineering, Brno. The project involves the construction of two thermally insulated surface pipelines, the pumping station, the agitated slurry mix tank and power distribution and control systems.



### Rough with the smooth

The ash disposal system is unique in that it is designed to handle various mixtures and ratios of fly ash, bed ash, bottom ash and desulphurisation products. These slurried mixtures have either settling or hardening characteristics.Complex control loops working interactively ensure that the various slurries are delivered to the pipeline in a condition which satisfies the stringent specification for pipeline operation and for slurry disposal. Controls and operation procedures are designed to prevent pipeline blockage, to clear slurry from the pipeline by using water and for pipeline drainage with the help of compressed air. The plant and component design is based on sample testing by GEHO®. During the plant proving phase, the slurry properties will be modified with a view to optimize the performance of the overall ash disposal system. This project follows the commissioning of the Bayswater fly ash disposal plant in New South Wales and of the MUJA fly ash pumping plant in Western Australia.

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 © 1997, Weir Minerals Netherlands b.v. All rights reserved.