September 2014 Quarter
Production by quarter
|Langer Heinrich Mine
|U3O8 Production (lb U3O8)
The quarterly production of 1,027,033lb U3O8 was down on the preceding quarter by 23%.
|Ore mined (t)
|Grade (ppm U3O8)
|Additional low grade ore mined (t)
|Grade (ppm U3O8)
|Total Ore and Waste
Mining activities concentrated mainly on the western side of the deposit in Pit H1 and H2 and were discontinued in Pit G3 on the eastern side of the deposit early in the period. Mining volumes remained on target and consistent with budget.
ROM ore stockpiles were full at the end of the quarter at approximately six weeks’ supply and are being supplemented by medium grade ore from long term stockpiles in line with the mine plan.
Throughput, recoveries and hence production were impacted during the quarter, primarily due to planned maintenance, but also due to scale formation in the process plant that led to a further, unanticipated reduction in throughput and recovery. This impact and the reasons for it were reported in the ASX release dated 16 September.
Throughput for the quarter was down 19.2% from the past quarter as was recovery by 2.9%, resulting in the overall production being down by 23% from the June quarter compared to the 20-22.5% reported in the 16 September release.
|Ore milled (t)
|Grade (ppm U3O8)
|Overall recovery (%)
|Production (lb U3O8)
The source of the scale formation was identified and routine anti-scalant addition procedures were modified during the quarter. By the end of the quarter, scale formation had been brought under control and all major affected equipment had been cleaned. In the case of affected process water pipelines, these have either been replaced or, in the case of major pipelines, duplicated to provide future redundancy.
The resin replacement was undertaken, as planned, during the annual scrubber reline and flash/splash annual maintenance and inspection stoppage. By the end of the quarter, resin had been replaced in both NIMCIX systems and they were each operating, as anticipated, above budget efficiency and uranium transfer levels. This was the first resin replacement undertaken for either NIMCIX systems since they were commissioned in 2012 and resin replacement scheduled in the next financial year is expected to have immaterial impact on production with the optimised procedures now established for this change out.
The process optimisation strategy will continue to focus on the better utilisation of existing equipment and unit operating costs. In addition, specific focus has been directed towards operator training and supervision as well as further integration of process control.
Water supply to the project continues to be sufficient, stable and secure under the water supply agreement executed with NamWater in November 2013. An extension of the agreement is being progressed. The Namibian Government recently has taken up secure and affordable water supply as a national priority and is advancing this critical policy with renewed focus.
Future Cost Optimisation Focus
A nano-filtration circuit, similar in principle to the very successful acid recovery plant at the Kayelekera Mine, is under construction at the Langer Heinrich Mine. This plant is the first phase in a range of innovations and optimisations aimed at achieving a substantial reduction in IX and leach reagent consumptions as well as increased overall recovery. The plant in question is designed to recycle up to 30% of the sodium bicarbonate needed for the operation of the plant, and, in so doing, will also reduce total sodium hydroxide consumption by up to 30%. These two reagents alone represent a significant proportion (circa 50%) of process operating costs. Construction is now well advanced and the Bicarbonate Recovery Plant (BRP) is scheduled for commissioning in the March quarter 2015.