TAKRAF Wagon Loading Station

The first wagon loading (rapid load-out) station built by TAKRAF for a manganese operation was completed within a record time of 32 weeks, compared to the industry standard of up to 52 weeks. The load-out station was built to service a new mine in South Africa, loading trains with manganese ore for export via the South African port of Port Elizabeth for local and international use.

The load-out station loads 2,000 t/h of manganese ore, but has the capacity to reach 7,000 t/h. Special consideration had to be given to the abrasive nature of the product, with TAKRAF drawing upon its experience of designing and delivering load-out stations for the iron ore industry.

Due to the high tonnages stored by this station, a concrete rather than a steel silo was employed. Other challenges that were overcome during design included the fact that the station had to continuously service trains comprising five different wagon types, while still enabling accurate load distribution and a uniform profile to ensure that axle-loading requirements were met. Furthermore, the station was required to handle two different product sizes: -15 mm +6 mm manganese chips and -32 mm +15 mm lumpy ore, loading each wagon with 63 t at a rate of about two minutes each. A total of 1 04 wagons per train is handled with each wagon moving through the load-out station at 0.3 km per hour.

As a flask-loading system, the station comprises a concrete silo equipped with a flow cone. The flow cone makes use of a controlled slot through which the manganese ore is fed into the weigh flask. The weighed load is then passed through the profile chute into the wagons. The flow of manganese ore out of the storage silo and weigh flask is controlled by a single long radial gate, which is activated hydraulically by a system designed by TAKRAF and which ensures that the gates close fully without spillage. The profile chute is designed to increase the loading distribution accuracy and reduce potential dust emissions during loading.

The system has a learning capability, whereby, as the first few wagons are loaded, the system assesses the effect of the loaded material's density and flow characteristics. lt automatically accounts for the prevailing conditions, and loads the train's wagons accurately, based on the wagons that have already been loaded. The control systems are based on client-specified and Windows-based software, allowing overall supervisory control and data acquisition (Scada) control of the operation. This also enables automatic validation of wagon numbers as they are entered into the Scada system, as weil as visual monitoring of operations through closed-circuit television systems.