Rössing Uranium’s operations consist of two distinct activities: the first is mining uranium-bearing rock, while the second is processing this ore into uranium oxide for the world’s nuclear energy market, which fuels the generation of electricity.
The uranium located in our mining licence area is embedded in very hard and abrasive granitic rock, known as alaskite. To mine the necessary volume of ore and waste, the mine must conduct blasting operations regularly.
Electric and diesel-powered shovels load uranium-bearing rock onto haul trucks, which transport the ore to the primary crushers for the first stage in the crushing process. From there the crushed ore is conveyed to the coarse ore stockpile, where it is reclaimed and put through additional crushing stages in the Fine Crushing Plant before the processing stage of operations begins.
During 2021, we mined 20.7 million tonnes of material (7 per cent more than 2020) of which 10.0 million tonnes was ore (9 per cent more than 2020) with waste and low-grade material being 10.7 million tonnes, equating to a strip ratio of 1.07.
The strip ratio is expected to drop significantly going forward as the pit gets deeper. A higher-than- planned crushed production of 9.6 million tonnes (10 per cent more than 2020) and a 6 per cent improvement in plant feed grade allowed the mine to achieve 16 per cent higher uranium production for the year.
The Mining Operations department embarked on a manpower ramp-down process to align employee numbers with the lower expected mined tonnes for the remainder of life-of-mine. This resulted in 42 operations and technical employees being redeployed, with those having artisan qualifications given the chance to attain the practical experience required to achieve full qualifications, while other employees moved to the other departments on the mine.
COVID-19 continued to have some impact on operations. However, employees in the mining teams are commended for adhering to the controls and maintaining adequate turnout to achieve target production.
With regards to health and safety, there were incidents of injuries within the mining teams that dented the productive mood, which nevertheless provided learning opportunities for leaders and employees. Actions to mitigate future potential incidents included improvements to engineering controls for pit vehicles and refresher training on manual handling.
The fatigue system was installed on all haul trucks and large water carts, resulting in a few employees receiving assistance with fatigue-related issues.
On the dust control side, the implementation of the pit-bottom water-pumping system resulted in a significant decrease in overall dust and a reduction of the risk of driving the water carts for long distances down-ramp. The latter project also allows us to de-water the pit bottom ahead of operations in the next few years.
Also notable was the design and execution of waste dumping within the pit limits, resulting in a significant reduction in diesel expenditure and related emissions.
In the technical space, there was an upgrade of the pit-control system to Dispatch 6; the introduction of down-hole radiometric grade measurement; a review of the mineral deportment and extractability of ores in the current pit and a potential Phase 4 push-back; and geotechnical and resource drilling to collect relevant information for the Phase 4 push-back. There were also upgrades to the mobile diesel-electric power generator (known on site as the motivator) and additional “scanner frame style” cable bridges to ease the burden for pit employees when moving electrical equipment.
The Processing Plant is responsible for the extraction of uranium from mined ore through several stages to produce uranium oxide (U3O8 ). This product is securely packed and shipped to our customers for further conversion. The aim of the plant is to produce targeted quantities of uranium oxide in the most efficient and safe manner possible.
In 2021, we exceeded the milled production target by 5 per cent, as we milled 9.6 million tonnes of uranium bearing ore. We drummed 2,882 tonnes of uranium, which is 393 tonnes more than the 2020 production.
The Processing Operations department recorded zero ‘all injuries’ for 2021.
Our focus in 2022 will be on innovation and capability enhancement to implement cost improvement initiatives, with emphasis on reagent consumption and extraction efficiencies.
A total of 48 engineering projects were undertaken during 2021, of which four are discussed below.
Increase of water storage capacity
The project to increase water storage capacity was approved for execution in 2020. This project is aimed at minimising production outages because of the unavailability of fresh water. A total of six glass-fused-to-steel-bolted tanks were constructed. Each tank size is 41,27 m diameter and 8,4m height with a capacity of 10,000 m3. The project results in a total increase of 60,000 m3 to compliment the storage capacity that is provided by NamWater’s reservoirs.
Construction work was performed by a local contractor who was responsible for all the on-site construction activities. The construction work started in May 2021. Substantial earthwork preparation was needed, and this included both the tanks area, the pipeline route, as well as the pump station.
The concrete foundation for the first tank was completed in early July 2021, which was an important milestone for the project, as it paved a way for tank-shell construction to start. The assembly of the tanks started in early August 2021 and continued for six months to complete all the tanks. Some interesting facts about the project:
- Total number of contractor employees for the duration of the project: 100
- Total amount of concrete used: 4,423 m3
- Reinforcement: 508 tonnes of steel
- Tanks (Glass-Fused-to-Steel Sheets): 903 tonnes of steel
- First water into Tank 1 & 2 – 29th October 2021
- New tanks supplied the mine with fresh water during a planned plant shutdown at the desalination plant when NamWater water supply to the mine was interrupted.
Replacement of Roaster 2
The Rössing Processing Plant makes use of roasters in the final processing of uranium. There are two roasters (multiple-hearth furnaces) that are used to roast the yellow cake uranium product. These units have been operational for over 45 years, and because of wear and tear, they have reached their end-of-life and therefore need to be replaced.
A structural integrity assessment was done on both roasters, the result of which guided the short- and long-term asset management strategy on the roasters. The replacement of Roaster 2 was prioritised, after which Roaster 1 will be the next one to be replaced. Mitigation measures were also put in place to ensure that the business is not at risk while the replacement strategy is being executed.
The Roaster 2 replacement project was approved for execution. The replacement includes the installation of a new roaster, which includes a roaster structure with refractory, burners, and a control system.
The new roaster has been procured and was delivered to site in November 2021. The project is in execution phase and the following has been done so far:
- Procurement and supply of Multiple Hearth Furnace, burners, refractory and control system,
- Civil works for the new roaster structure and Motor Control Centre in progress,
- Steel works for the roaster structure in progress for the placement of the new roaster, and
- Control system design and hardware supply nearing completion.
Wire-meshing of Haul Road 21
Rock-fall hazards were identified on a section of the high-wall above Haul Road 21 in the open pit. The area is affected by geological structures and blast back-break on the structures, resulting in the presence of fractured blocks and loose rocks on the high wall. Attempts were made to remove the fractured blocks during scaling of the high wall, which at times included secondary cleaning by creating access on the blasted muck pile; however, not all the blocks could be removed.
To mitigate the risk, a capital project was approved for execution. The project involved the installation of drape wire meshing on the identified area. The design concept used for the Haul Road 21 high wall is an unsecured system with anchoring only along the top. This allows rock-fall to occur between the rock face and the mesh and controls the trajectory into a containment area at the base of the high wall. This project was completed in November 2021.
Replacement of Rodmill 2 Shell
The mine’s plant operates four rodmills during the ore-grinding process at the milling plant — two mills on each production line are operated concurrently. Thickness tests conducted on the Rodmill 2 shell showed increased wear on the shell-plate discharge end. The shell thickness was found to be below the expected healthy thickness, and a replacement project was approved for execution.
The shell with its auxiliary critical components were replaced, and the mill was commissioned back into operations in August 2021.
Process safety management
Process safety management (PSM) is a systematic approach of controlling the unwanted release of hazardous substances, process solutions, or fires and explosions that have the potential to significantly impact the health and safety of employees, the environment, or the business.
The four process safety hazards managed at Rössing are:
- anhydrous ammonia gas,
- concentrated sulphuric acid,
- fire in the solvent extraction and final product recovery plant, and
- engulfment due to large processing tank failures.
In 2020, Rössing rolled out an improvement project in the PSM section, which was completed in 2021. A process safety specialist consultancy team assisted the company in identifying shortcomings in the current control strategies of the two main process safety hazards: anhydrous ammonia and concentrated sulphuric acid. A total of 115 improvement actions were logged, of which 93 have been completed. The remaining actions will be completed in the first part of 2022.
The process safety improvement project was not just a success in the PSM section, but also in the other departments in Rössing. In the training department, e-learning courses were developed in process safety management and in pressure vessel statutory testing.
The engineering department benefited through the in-house approved inspection authorities that have been identified to be trained on-site and were signed off by the Chief Inspector of the Ministry of Mines and Energy.
During the reporting year, the PSM standard has been reviewed and amended and an audit protocol developed. A third-party audit is planned for the third quarter of 2022.
There were several smaller focus areas in 2021 to improve business controls. Visibility of information to assist with better decision-making was one of the focus areas of 2021. These initiatives will assist in the more efficient use of resources, post implementation.
An achievement was the empowering of leaders to understand their teams/employees’ attendances and productivity. Following the successful implementation of the SAP Time and Attendance system, critical findings from the benefits tracking analysis identified various key performance indicators (KPIs) to improve on. Plans were developed to address each of these areas. Several leadership dashboards have been developed to assist leaders with monitoring these KPIs.
The second achievement was the Business Intelligence (BI) analytical dashboard that was developed with regards to light vehicle KPIs, which includes elements such as tyre cost and tracking, battery cost and tracking, service cost and fuel consumption. This project was done as a proof of concept. The BI tool and process will be expanded in future years to include other business reporting areas such as contractor spend, and a time and attendance dashboard, among others.
Further improved controls have been implemented in the SAP Enterprise Resource Planning system on the following business processes:
- Service invoice acceptance: new controls will restrict acceptance to the specific cost centre owner or the manager.
- Stock reservations: release strategy has been implemented on stock reservations to improve control on maintenance cost of stores items. The delegation-of-authority values apply. This will assist to stop the unnecessary reordering of maintenance parts.
- Non-stock and service purchase requisitions: a new release strategy has been implemented. The approval of a purchase requisition will be on the total order value, no longer on each individual line item, which will enable approvers to see the total cost impact. The total order value cannot differ from the total requisition value. A few smaller controls have also been added to give the cost accountants more visibility before the requisition is approved. All consultancy requisitions have to be approved by the Managing Director.
Increased cyber security risks have prompted Rössing to commence a focused project to improve its cyber security framework and strategy.
An important focus area for 2022 is the improvement of the control of information on contracts (especially service contracts) and contractor management. This will aim to improve the control and visibility over contract spend and non-contract spend.
A business case will be developed for the implementation of a time-and-attendance system on contractors. The same KPIs which were defined for the employees will apply to contractors, improving the visibility and control over contractor-related abour cost, including areas such as double charging for the same person, overtime charges, the number of contractors on site, absenteeism management, and mitigating compliance risks from fatigue management.
The CCTV improvements planned for 2021 did not materialise. The sourcing process has brought new interested parties into the mix and they will be presented to the tender board for selection during 2022. An aggressive implementation plan should be developed with the preferred supplier.
Better document management policies will be defined to ensure the secure and controlled storage, retrieval and archiving of vital business electronic and paper base documents. The ‘Sharepoint’ document management system is already in use, but the guidelines presented from the policy need to be applied.
Life-of-Mine Extension (LoME) project
In 2021, the Rössing Board of Directors approved funds to complete a bankable feasibility study for extending the life-of-mine beyond 2026. This is underpinned by a north-eastern extension of the open pit, referred to as the Phase 4 push-back, which can provide sufficient ore to continue production for another ten years.
A major milestone for the LoME project was realised in July 2021, with the Ministry of Mines and Energy (MME) extension of the Rössing Mining Licence (ML28) by 15 years to July 2036.
The feasibility study will inform an investment decision by the end of 2022 that must consider several aspects, in addition to the pit expansion. These include an extension of the Tailings Storage Facility (TSF), as well as Processing Plant and infrastructure upgrades required to sustain production beyond 2030. To pull everything together for an optimal solution, a dedicated project team, covering seven disciplines, was assembled to focus exclusively on LoME project activities until the end of 2022.
One the mining side, a key activity is diamond drilling to improve confidence in the resource model and confirm metallurgical characteristics of the Phase 4 ore.
The drilling will also test ground conditions to firm up the push-back design, notably the pit slope angle. A study is also required to confirm the impact of blasting closer to existing mine workshops that will be affected by blast vibration and fly-rock.
On the Processing side, LoME will investigate the refurbishment or replacement of the existing plant, as well as considering new technology that has the potential to improve productivity and reduce costs.
Two such projects are the Horizontal Belt Filter (HBF) and Heap Leach (HL) technologies, which have previously been considered for Rössing.
Linked to all of this is a design for accommodating an additional ten years of leached ore (tailings) in a way that mitigates the additional impacts of a larger footprint.