Construction World December 2021

CONSULTING ENGINEERS

MOVING KENMARE WET CONCENTRATOR PLANT B TO PILIVILI

T he Moma Ti tanium Minerals mine in Northern Mozambique i s owned and operated by Kenmare Resources . I t i s one of the largest t i tanium minerals depos i t in the world. Mining i s principal ly undertaken us ing dredges that float in art i ficial mining ponds . The dredges mine the mineral rich dunes f rom the ponds and pump the mineral sands to the float ing Wet Concentrator Plant (WCP) . Wi th the object ive of increas ing i lmeni te product ion at the mine f rom 1 mi l l ion to 1,2 mi l l ion tonnes per year on a sustainable bas i s f rom 2021, the last of three development projects was undertaken in 2020: the Wet Concentrator Plant B (WCP B) was moved 23 ki lometres f rom i ts previous s i te at Namalope to a new high grade ore zone cal led Pi l ivi l i . In addi t ion to moving the WCP and dredge the inf rastructure for the new operat ion at Pi l ivi l i (water and HMC product pipel ines , 110 kV overhead powerl ine, a Statcom, sub stat ions and s i te electrical ret iculat ion, a product stacker and reclaim system and a pos i t ive di splacement pumping system) had to be des igned, procured, and constructed. Mining at Namalope was completed in late August 2020. The relocat ion of the WCP and i ts associated dredge was undertaken by Mammoet , a global special i st heavy l i f t ing and transport contractor, us ing plat form vehicles cal led sel f-propel led modular transporters (SPMTs) . The dredge and WCP were moved in two stages . Once they had been placed on concrete pl inths in a relocat ion pond and the pond had been dewatered, the fi rst stage involved the movement of the dredge to Pi l ivi l i . On complet ion of thi s relocat ion, the SPMTs returned to Namalope to transport the WCP along the same route. The relocat ion of the dredge took place between 14 and 16 September 2020. The WCP, only able to travel at

one ki lometre an hour fol lowed on 21 September. On 25 September, a major mi lestone was achieved wi th the WCP arriving safely at the staging pond in Pi l ivi l i . Thi s project had a unique scope due to the nature of the material upon which the WCP and dredge had to be transported. The project included the civi l inf rastructure requi red for the moves ; roads , earthworks , relocat ion pond, staging and float-of f ponds , river cross ing mining starter pond and a terrace for the inf rastructure at Pi l ivi l i . Construction innovation technology The 1 700 tonne dredge and the 7 000 tonne concentrator were transported along a new purpose- bui l t road us ing plat form vehicles cal led sel f-propel led modular transporters . Haul Road and Float-over Channel The completed road travel way needed to be 42 metres wide, to accommodate the 60 m-wide WCP wi th some clearance on ei ther s ide. The excavated land contained untreated, col laps ible sands wi thout any cohes ion, placing enormous pressure on avai lable resources . Several material tests were undertaken to determine the best poss ible opt ion for road layer works . Impact compact ion of the ins i tu material , was implemented in the form of impact rol l ing wi th a vibrator y polygon rol ler, to depths of 2,5 m, to ass i st in the dens i ficat ion of the ins i tu material and increase the st i f fness . The subbase layer compri sed of 2 x 150 mm thick layers of cohes ionless , compacted red sand. The wearing course was a blend of granular material and red sand f rom local borrow pi ts and was compacted to a 200 mm thick layer. In addi t ion, a float-over channel (600-metres long by 70-metres wide and 2-metres deep) across the Mualadi River was constructed, for the dredge and plant to float

52 20 th Best Project Awards 2021