MechChem Africa October 2017

MechChem Africa talks to SAIChE iCHEMe stalwart Philip Lloyd, whose chemical engineering career began some 65 years ago and he continues to find new directions today. Six and half decades of exciting opportunity

P hilip Lloyd was born in the UK and came to South Africa as a boy im- mediately after the Second World War. “Imatriculated inCapeTown in 1953 and then spent a year with the O’Kiep Copper Company in Namaqualand, where I developedan intensedislike for shiftwork,” he says. “While doing laboratory work, though, I became fascinatedby a newway of producing acidbyseparatingsulphidemineralsfromcop- per ore andusing it togenerate sulphuric acid. “I had always been fascinated by science, and chemistry, in particular. So following my year out, I was advised by a career counsellor to take the Applied and Industrial Chemistry degree atUCT, which I did,” he tells MechChem Africa . Half way through his degree, Applied and Industrial Chemistry became Chemical Engineering, so Philip Lloyd was among the very first batch of chemical engineers to graduate fromUCT. While still a young graduate, Lloyd “got lucky”. After completing his degree. “There

was a scholarship going begging, funded by theChamber ofMines and later by theAtomic Energy Board. So I stayed to do a PhD and that work not only set up my career, it also resulted in a significant change in theuranium industry,” he recalls. The work? “Uranium extraction at that time relied on the ion exchange process. During my PhD I developed a far more cost- effective method using solvent extraction – and within five years, this new process had completely replaced ion exchange,” he says. Describing the principles involved, he says that the leach solution from the uranium ore was mixed with a long-chain amine, which selectively extracted uranium into a solution at relatively high purity. “We then found a very cost-effective way of precipitating the uranium out of the paraffin solution – by manipulating the pH, the uranium tumbled out in a single step.” “This worked out much cheaper than the ion exchange process, which depended on highly concentrated nitric acid to get the ura- nium off the ion-exchange resins,” Lloyd explains. As a reward for this success, the

reveals, adding that the research done was very widespread. “We investigated how to fight underground fires; how to get rid of the pathogenic fungus that grew on the mine- prop timbers; and we doubled the size of the Fanagalolanguagetoimprovecommunication underground.” During this period, Lloyd supervised the work done to reprocess the mine dumps on the East Rand. “The East Rand gold and ura- nium complex (Ergo) was first formed during this time to focus on recycling the dumps. As well as getting residual metals out of the old tailings dumps for recycling, the real benefit was opening up a the land along the reef for development,” he notes. “We also did a lot of work to improve the economics of gold mining. It was clear that a huge amount of rock had to be brought to surface and processed to extract the gold, which led us to look at the possibility of get- ting the gold out of the ore underground,” Lloyd recalls. Describingeffortstomilloreunderground, he says that, on the surface, gold ore is fine milled in a 1G gravitational field. “We bolted amill onto the end of a centrifuge to expose it to 20Gs, which enabled us to process 100 t/h using a mill only 1.0 m in diameter and 1.0 m long.Thisistypicallydoneonthesurfaceusing a 5.0 mmill with 5.0 m length,” he says. “While underground processing was not taken up at the time, “the real benefit of this research turned out to be the safety advantages of backfilling. Today, about a third of underground support in goldmines is achieved by backfilling,” he notes, adding that company called Gekko has now taken up the challengeofprocessingoreathighefficiencies underground. “We alsodiscovered thatwe could recover up to 97%of the goldwithout having to crush the ore so finely. This proved unpopular with mine owners, however, who felt leaving 3.0% of the gold in the ground was a waste. The economic argument for going that route was strong, though,” Lloyd points out. Describing a success story for the gold mining industry in the Free State town of Virginia, Lloyd says that the Chamber of Mines’ Research Laboratory developed a portable X-ray technique for analysing the amount of gold present in a rock face.

Atomic Energy Board sponsored Lloyd to attend MIT in the USA for three years of research into nuclear physics – “along with a lot of other exciting stuff.” On his return he went to work for the GovernmentMetallurgical Laboratory, which was based at Wits at the time. “The Lab had an extractionmetallurgydivision that was part of the Atomic Energy Board and I continued to do work on uranium – until the division was renamed Mintek and moved off campus to its current site in Randburg. At that stage theBoard was moving into nuclear weapons related work and I did not want to be involved with this,” Lloyd informs MechChem Africa . “So I joined the Chamber of Mines Research laboratory in Melville, Johannesburg. In those days it was funded to the tune of R100-million per year, so it was a very exciting place to work,” he

A 3.0 m 3 rougher flotation cell recovering gold in up to 2.0 mm particle sizes at 97% efficiency.

6 ¦ MechChem Africa • October 2017