The multidisciplinary detail process and engineering design for Exxaro’s coal-washing plant with respect to the Grootegeluk Medupi expansion project has been successfully completed by South African construction major Aveng Engineering & Projects Company.

The coal, which will be processed through two new processing circuits, namely Grootegeluk 7 and 8, will be crushed by semimobile crushing stations in the pit, with 100 mm of run-of-mine (RoM) material being fed into the screening plant, where it will be screened into large, medium and fine fractions.
The fine fractions will bypass the washing circuit, while the medium and large fractions will be beneficiated in the cyclone and larcodem plants.

Meanwhile, Aveng says the design of the coal-washing plant ensures zero effluent, which eliminates the need for slimes dams known to have a negative impact on the environment.

The company says the design also focused on energy efficiency to provide an ecofriendly facility with minimal interference in the natural environment.

Transfer chutes were designed to comply with stringent but optimised capacity and geometrical specifications, while subjected to material flow simulations to verify calcula- tions using the discrete element method, says Aveng.

Optimising the electrical distribution and control network for the greater Grootegeluk Medupi expansion project was achieved by focusing on system load flows and fault levels, using an Electrical Transient Analyser Program (a power systems analysis solution) simulation under various switching and fault conditions, which includes the in-pit expansion, RoM and discard bunkers, and product load-out and sizing facilities.

Aveng says it used three-dimensional techniques for the layout and detail design of the process, including programmes such as AutoCAD and AutoCAD Mechanical, in ensuring an innovative approach to the design.