:: Namdeb’s No. 3 Plant Diamond-treatment Facility Upgraded

Bateman Engineering has implemented a ZAR65 million (US$9 million) upgrade of the diamond-treatment facillity at Namdeb Diamond Corporation Pty Ltd’s No. 3 Plant in Oranjemund on the south-west coast of Namibia. The upgraded facility has met Namdeb’s expectations and was completed within budget.

This upgrade project involved the detail design of some new plant and modifications to existing circuits. The additional plant comprised a new-generation Sandvik cone crusher with fully automated on-line gap settings which, while smaller than those on the out-going crusher, would liberate the diamonds more effectively. An additional 200 t/h Bateman Mega DMS Modular Plant was installed that is more efficient and has a smaller footprint than the existing plants.

The upgrade also comprised the provision of underflow feeding for the DMS (dense-media separation) stockpile, modification of the existing scrubbing section and the provision of a three-way splitter-chute system to the three DMS modules. In the existing DMS building, the old mixing boxes were replaced by more efficient standard units. The old cyclone feed system comprising two Multotec 610 cyclones per stream was replaced with new distributors and feed hoses and four Multotec 420 cyclones per stream, to accommodate the change in the feed-size profile. The new silo system now controls the collection of concentrate from all of the DMS plants. The tailings conveyor was extended to accommodate the new DMS module and the water-reticulation system was modified using new equipment. The existing SCADA (supervisory control and data acquisition) system was also upgraded.

The whole plant was designed to use seawater with no additives as process water. As a result an environmentally friendly tailings stream is being pumped back into the sea.

The final scope of the project was agreed in May 2006, with the plant’s construction completed in February 2007, commissioning and first production starting in March and the whole project signed off in May 2007.

The start of the project dates back to 2004, when Namdeb involved Bateman Engineering in a pre-feasibility study and then a feasibility study on the use of the plants for dump reclamation in the area to increase the life of the mine. It is known that the diamond-recovery processes used previously were not as efficient as they are today and that these dumps contain meaningful amounts of small diamonds and possibly also some larger stones.

Initially a minimal upgrade was contemplated, but this was subsequently expanded to cover an increased throughput and other possibly more viable business options. After additional run-of-mine (ROM) resources were discovered in the area, the concept evolved into one in which the upgraded plant would first have to process ROM and then convert to handling dump material in the future.

The initial scope of the project was agreed in September 2005 and design work commenced with the goal of ensuring the major components could be delivered onsite by mid 2006. Some downscaling firmed up the final scope, permitting the reduction of the installation time and contract price.