WITHSTANDING TIME Thirty years of reliability wins Condra a repeat order
Reliable duty in a corrosive environment has won crane and hoist manufacturer Condra a repeat order from platinum miner Lonmin Platinum for an overhead tankhouse crane to replace an identical machine delivered 30 years ago.
The original crane was installed in 1990 at Lonmin’s Middelkraal Farm refinery outside Marikana, in the North West, where it lifts and positions copper plates and slabs in the acid tanks used during the electrolytic refining process.
During this final phase, anodic copper slabs, with a 99% purity, attained during three prior processes, are suspended by the crane in large tanks filled with an electrolyte solution of copper sulphate and sulphuric acid.
Small, thin sheets of pure cathodic copper are then positioned between these anodes and an electric current is applied. Copper ions leave the anodic slabs and move through the electrolyte to place themselves on the cathodic sheets, which, after a time, become thick copper plates of 99.99% purity, ready for removal by the tankhouse crane for rinsing and despatch to factories that produce copper products.
Lonmin’s double-girder electric overhead travelling crane has a span of 19.9 m, a capacity of 5 t, a lifting height of 7.7 m and two lifting speeds of 2 m/min and | 8 m/min.
Long-travel speed over the 42 m of the tankhouse is 80 m/min.
Condra has delivered – to other refineries – tankhouse cranes with long-travel speeds as high as 140 m/min, more than three times the speed of a standard crane and about as fast as an average person’s jogging speed.
“To cater for a possible customer need for higher speeds in the future, we have included in Lonmin’s new crane the provision for an easy upgrade to frequency drives,” explains Condra MD Marc Kleiner.
“Condra is currently investing in improved digital loadcells to further improve reliability across our tankhouse line in general, even though the reliability of the Marikana crane was well proven over a period of three decades,” he says.
Lonmin’s new tankhouse crane will incorporate features from Condra’s design library that move it beyond the company’s current generation of tankhouse cranes.
These include four light-emitting-diode girder downlights to illuminate the work area, remote crane control with a pendant backup, an electrical control panel fitted with acid filtration ventilation to cater for the corrosive tankhouse environment, and a special paint finish for the same reason.
Quality control will include inspection and certification at defined stages of manufacture, as well as magnetic particle inspection of the welding seams to ensure airtight girders and the avoidance of corrosion on the internal faces.
The crane was ordered in April and will be delivered before the end of next month.