RSV completed the construction of a UG2 reef storage silo at the Dishaba shaft of Anglo Platinum’s Amandelbult East mine earlier this year. Work started on this portion of the project in April 2007 with site establishment, earthworks and civils work. At peak the project employed 60 people, and over 220,000 manhours were worked without any lost time injuries being recorded.

The mine previously extracted Merensky ore and the existing silos house Merensky and waste product. This new project provides an infrastructure for UG2 mining and the new silo, which will house the UG2 ore. The project also provided a third ore pass system to hoist the UG2 at the Dishaba shaft.

“An impressive aspect of this project is the high level of survey accuracy,” Pierre Lombard, project principal at RSV, says. “The silo set out was done within 50 mm of the specified survey coordinates.”

One of the major challenges on this project was to ensure the accurate transfer of both the UG2 to the new silo and the waste to the existing silo even though the new silo is slightly offset from the centre line of the existing silos. “The reason for it being offset was to accommodate the radius of the new railway line which now runs under the UG2 silo,” Lombard says.

The use of innovative design work was applied to achieve the optimum solution. The existing waste chute was utilised and now incorporates a flopper gate and the new transfer chute. “An interesting aspect of the transfer point itself is that the chute was designed with a twisted configuration to accommodate two different angles,” Ettienne de Beer, lead mechanical engineer at RSV, says.

Another interesting element of this project was the design and installation of spilmanator chutes. “Traditionally these chutes are used to control mud rushes and were selected for this silo application to enhance safety. Attention was given to the design work to ensure easy and safe access to the chutes for maintenance and repair work and to ensure the structural integrity of the spilmanator chutes,” de Beer says. The spilmanator chutes were structurally designed by RSV for and on behalf of CAN Mining, which was responsible for the manufacture of the chutes.

Winches have been installed to facilitate the lifting of large components for repair and maintenance to the silo penthouse. In addition, the winches were used for the installation of the 90 metre long conveyor belt and, as a permanent installation, will fulfil this role in the future.

Using an unconventional design methodology, the silo is fitted with rail liners to eliminate wear on its interior surface. The 12.7 metre diameter, 31 metre high silo with a 3,500 tonne live storage capacity, was completed at the end of February 2009 on schedule and within budget.