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TECHNICAL INFORMATION

SHAFT HOISTING AND ROPE-HANDLING TECHNOLOGY(IMPALA PLATINUM LIMITED, ILLOVO, SOUTH AFRICA)

TECHNICAL INFORMATION

SHAFT HOISTING AND ROPE-HANDLING TECHNOLOGYAs mining in the platinum belt at Rustenburg in South Africa progresses, the workings have to push forward to ever-increasing depths. Impala Platinum Limited is no exception and in 2007 the company decided to construct shaft number 17 to extract ore from a depth of around 2,000 metres.

The sinking of the main shaft had to be started as quickly as possible, but there was no winder of the required capacity available at the time. The construction and delivery of a new winder would have taken too long and wrecked the customers tight schedule.

At this time, the customer was discussing with SIEMAG TECBERG the possibility of finding a suitable winder for the new shaft among the machinery decommissioned following the phasing-out of coal mining in Germany. The Koepe winder installed at the Goettelborn mine seemed to meet the requirements for mining ore at Shaft 17. Since a second hoisting system with a second Koepe winder was planned for transporting material and personnel, the solution was adopted of using the two winders for the final mine in order to sink the main shaft.

SKIP TRANSPORT DURING SINKING OPERATIONSThe twin-drum machines normally used for shaft sinking have a resetting (clutch) device to allow two skips to be hoisted and lowered alternately and to load and unload them at the same time as the distance to the foot of the shaft steadily increases. Koepe winders are unsuitable for operations of this kind, but when suitably converted, can work with one skip. It was therefore decided to dismantle the machine at the Goettelborn shaft and transport it to South Africa. It was also decided to replace the electrical control system at the same time and construct a new drum locally to cope with both the shaft-sinking operations and the subsequent mining operations. The high constricting pressures from the five-layer coiling of the loaded rope made drums with extra-thick sheet casing necessary for both machines.

In the case of Impala 17, single-kibble operation was sufficient in the initial shaft-sinking phase and the converted Goettelborn winder proved suitable for the purpose. This allowed work on the shaft to be started early and the second kibble went into operation when the service winder was completed to allow enough material to be hoisted as the travel distance increased. As opposed to conventional shaft-sinking winders, this solution allows kibbles to be hoisted

6-Rope Koepe production winder (formerly at Goettelborn shaft, Germany), currently modified as sinking winder

singly and independently of one another. On conclusion of the sinking operations, the two machines will be cleaned, the ropes removed, and then converted for Koepe-type hoisting by bolting metal blocks in a ring around the drum to create trapezoid grooves, and to fit the usual two-part friction-pulley liner blocks for six-rope hoisting. This conversion work has already been rehearsed in our workshop so that the actual work on-site can be completed as quickly as possible.

SIEMAG TECBERG was able to offer this solution as tried and tested technology because several conversions of this type have already been carried out in similar cases and the concept approved as sound and effective. In addition to the two winding machines, SIEMAG TECBERG will also be supplying the rope sheaves for the mining operations. The great depth makes the stress on the ropes very high, which means that the machines and the rope sheaves had to be specially dimensioned.

These two factors the depth and the high rope weights are also the reason why Impala has purchased a large SIEMAG TECBERG friction winch. This pulley makes it possible to raise or lower all six ropes, each measuring 2000 metres, at the same time in less than three hours. The tractive forces occurring can be as high as 180 tonnes. Like most others, the friction winch is mounted on a chassis and can therefore be moved to different positions. For this reason, it is suitable not only for installing and changing the ropes in the two hoisting systems at Shaft 17, but also for those two at Shaft 16. (For more details on friction winches, see our separate technical information).

Clamping and lifting devices are also being installed at both shafts. These are a fast and reliable means of relieving the weight in order to carry out frequently recurring work on the ropes. The two clamping and lifting devices for shaft 16 were designed for an operating load of 170 tonnes and are therefore suitable for hoisting a full conveyance from the very deepest position. A third clamping and lifting device is intended for handling one tail rope in each case. Together with the necessary rope reelers, messenger winches, deflection sheaves and other aids, SIEMAG TECBERG has developed and supplied complete solutions for rope-handling and changing specifically for the customers needs. (For more details on clamping and lifting devices, see our separate technical information).

The rope-handling systems selected have made it possible to avoid processes which are normally time-consuming and dangerous, as well as the over-dimensioning of the drive engines for the hoisting machinery which would otherwise have been necessary to hold the above-mentioned loads.

With its machinery and rope sheaves as well as its handling devices and other equipment, SIEMAG TECBERG has again proven its outstanding expertise in the field of shaft hoisting by again extending the limitations of previously realised plant and machinery.

6-Rope Koepe service winder, currently modified as sinking winder

2 x 4-Rope clamping and lifting device, double-sided, max. rope load 1,700 kN

1 to 6-Rope friction winch, max. traction force 1,800 kN

TECHNICAL DATA

KOEPE ROCK HOISTING DUTYWinding dataType of winding productionType of conveyance skip/skipType of shaft verticalMonthly winding capacity 260,000mt/mWinding capacity 700mt/hWinding distance 1,922mPayload 33mt Maximum unbalanced load 330kNMaximum suspended load (T1+T2)

3,525kN

Number of ropes & Diameter 6 x 50mmWinding speed 18m/s

Friction pulley & driveNominal Diameter 7m Pulley / Motor speed 49.1rpm Type of motors overhung AC Motor power RMS, approx. 1 x 7,500kW

KOEPE MAN HOISTING DUTY Winding dataType of winding serviceType of conveyance cage/counterweightType of shaft verticalWinding distance 1 872 mPayload 27 t Weight of cage, with rope attachments

28.8 t

Maximum unbalanced load 135 kNMaximum suspended load 3,560kNNumber of ropes 6Diameter 50 mmWinding speed 15 m/s

Friction pulley & driveNominal Diameter 6 m Pulley / Motor speed 47.8 rpm Type of motors overhung AC Motor power RMS, approx. 1 x 4,000 kW

SINGLE DRUM SINKING DUTY (BOTH MACHINES)Winding dataType of winding sinkingType of conveyance single kibble Winding distance 1,900mPayload 16mt Weight of kibble 7.8mt Maximum unbalanced load 463kNMaximum suspended load 463kNNumber of ropes 1Diameter 51mm Winding speed 15m/s

Drum & driveDiameter, centreline of rope, approx.

6.7 / 5.85m

Coiling width, approx. 1.85 / 2mDrum / Motor speed 40.9 / 47.8rpmType of motors overhung AC

Installed motor power RMS 7,500 / 4,000kW

Rope reelers, drum diameter max. 3.0 m