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. Our attention is directed towards creating shareholder value and maintaining a secure and viable business, as well as ensuring that we remain a long-term contributor to Namibia’s economy.
The uranium located in our mining licence area is embedded in very hard and abrasive granitic rock, known as alaskite. To move 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.
The refurbishment of the leach tanks is part of a ten-yearly refurbishment programme to ensure that the structure of the leach tanks is in good condition.
Risk assessments are carried out by the workers to check that the work is carried out safely. Employees of the Namibian Engineering Corporation (NEC), Sam Nujoma, Stephanus Mouton and Teopolina Fanuel are conducting a safety check while working on the refurbishment of one of the leach tanks.
In 2018, we mined 19.8 million tonnes of rock (21 per cent less than in 2017) of which 8.0 million tonnes uranium-bearing rock (17 per cent less than in 2017) were removed from the open pit and 11.5 million tonnes were waste rock (0.3 million tonnes were from in-pit dumping). This equates to a waste-to-ore strip ratio of 1.48, which is lower than 2017 at 1.57 and will continue to reduce as the open pit gets deeper.
Despite the lower tonnes mined, the ore processed remained consistent with 2017 at around 9 million tonnes with around 1 million tonnes coming from stockpiled ore. By the end of the first quarter, the run-of-mine (RoM) stockpiles had grown to the extent that a decision was taken to stop mining from the open pit for a month during the second quarter while continuing to feed the plant from stockpiles. This decongested the RoM stockpiles while saving a large amount of operating cost, an approach that continued to a lesser extent for the remainder of the year.
Both the uranium grade and calcium carbonate (calc) index continued to increase (15 and 11 per cent higher than 2017 respectively) with the better grade the main contributor to the 17 per cent increase in drummed product relative to 2017. While the high calc index of 16.7 kilogramme per tonne in 2018 had a negative impact on sulphuric acid consumption, a more consistent blend and better plant controls actually saw an increase in overall recovery by 3 per cent.
Grade and calc index will remain a key focus in 2019 with work ongoing to implement an online calc analyser to reduce the number of calc spikes to the plant.
Improvements were achieved in a number of other areas, especially in the area of safety and 2018 saw the benefit of continued safety focus with a milestone of 450 All-injury free days achieved for the mining department.
On the maintenance side, equipment availability and reliability continued to improve following the successful implementation of the Rio Tinto Asset Management tactics. A decision was taken to park one diesel shovel and two haul trucks during 2018 in line with reduced mining rates and better equipment reliability.
Focus areas in 2019
Vehicle collision and roll-over with heavy mine equipment (HME) remains the highest safety risk in the open pit with incidents caused by fatigue and over-speed prevailing during 2018. The segregation of HME from light vehicle traffic on the permanent ramps has significantly mitigated the consequence of such incidents, but the fatality risk remains with the operators of HME, predominantly operators of haul trucks. Fatigue management and speed controls will remain a key focus for 2019.
Productivity remains a key challenge in the mining department with haul truck effective utilisation (EU) as the key performance indicator. Haul trucks are the ‘conveyor belt’ of the open pit and we did not achieve the target of 60 per cent EU in any month during 2018. This is due to a combination of factors, including a shortage of operators and poor shift change turnaround, both of which will be focus areas for 2019 to improve the haul truck EU by 5 per cent, which is the equivalent of one extra truck in operation.
The Processing Plant is responsible for the extraction of uranium from mined ore through a number of 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.
We produced a total of 2,479 tonnes of uranium oxide in 2018 , which is 17 per cent higher compared to 2017's production of 2,110 tonnes.
A CRM success story: crest chicane for downhill hauling
In our critical risk management (CRM) process, heavy mine equipment collision and rollover have been identified as critical risks in the mine's open pit. It was also noted that haul truck operators not always reduce their speed as they approach the crest of down ramps.
In order to prevent accidents and fatalities, crest chicanes have been constructed on some mine roads in the open pit.
A chicane is a serpentine curve or extra turns added in a road to slow traffic for safety. The word chicane is derived from the French verb chicaner, which means 'to create difficulties'.
Since the chicanes were constructed, the average top speed of the haul trucks has dropped to 30 kilometre per hour, which is within the speed limit. An additional benefit of the chicane is that it can be used as ‘whopper stopper’ to bring a haul truck to a stop in case of a ‘run-away’.
Several engineering projects were undertaken during 2018.
Seepage recovery upgrade project
Tailings seepage at Rössing Uranium is defined as process water which filters through the Tailings Storage Facility and drains through the underlying geology into the surrounding environment.
A network of seepage recovery systems, consisting of pumps installed in boreholes, sumps, cut-off trenches and the surface seepage collection dam, prevent the seepage from entering the wider environment, specifically the Khan River.
In 2018, the upgrade for the cut-off trenches, the most critical component of the seepage recovery systems, was completed. The recovery systems have been operational for over 30 years and the installations at the cut-off trenches needed a complete overhaul.
The cost to upgrade the now-completely automated system was over N$30 million. These cut-off trenches are the critical groundwater controls between our Tailings Storage Facility and the Khan River, and are of utmost importance for the continuous protection of the water environment well into the future.
Construction of spur lines along haul road 20 and trolley 11 in the open pit area
In 2018, the engineering team implemented the construction of spur lines – very short branch or secondary lines – along haul road 20 and trolley 11 in the open pit area. The aim of the project was to offer a long-term solution to power supply requirement by field equipment such as drills and shovels in the mining process of phase two of the SJ Pit and phase three. In the past, this was accomplished by means of trailing cables as a temporary solution.
The project was successfully completed and resulted in improved supply reliability, an increase in feeder capacity whilst maintaining steady voltage, improved cable availability, reduced pressure on maintenance crew working on cable repairs, as well as reduced maintenance cost.
Rodmill static exciter installation
Rodmills are critical assets for the mine, forming part of the reduction process. The electric motors running these mills have an analogue excitation system. With improvement in technology over the years, a digital excitation system has been developed.
The electrical engineering team harnessed this technology to improve the rod mill operation and availability. The new system offers Our operations far more motor control and therefore, improved rodmill reliability. The successful installation and commissioning of the first excitation system was done on Rodmill 2 in 2018; the remaining three will be installed during 2019.
Concentrated eluate tank
The concentrated eluate tank is one of the processing tanks in SX plant. The tank failed in early 2016, causing the leakage of the concentrated eluate solution. Assessments revealed the severity of the tank’s condition, while a cost analysis indicated it would be best to construct a new tank rather than repairing the existing one. In addition, onsite repair of the tank would have involved extensive welding works in the SX plant, which is undesirable due to the associated fire risks in that specific area.
Demolition of the old tank commenced in July 2016. To reduce the amount of hot work in the area for safety reasons and to be able to lift the tank from its position, the old tank was demolished by cutting into three sections, namely its roof, top shell section and bottom shell section, including the floor. Each section was cut and lifted out of its position by means of a 500-tonne mobile crane, the biggest mobile crane available in Namibia.
The new tank was constructed onsite in the mobile equipment workshop, following the same sequence of demolition. This was to allow lifting of the tank into its position during installation. Construction and installation of the various sections of the new tank was completed.
Arandis roofing project
During 2018, the Arandis Town Council, in collaboration with Rössing Uranium and the Rössing Foundation, started a project to remove the hazardous asbestos roofing sheets from 823 houses and two primary and secondary schools, replacing these with zinc-aluminium roofing sheets that are environmentally friendly.
This followed engagement with the residents during the past two years through public meetings and awareness campaigns about possible health risks of using asbestos roof sheets. The replacement or refurbishment of roofs of the houses will be completed within the next three years. The project is expected to cost N$28 million, which will be paid by Rössing Uranium.
All removed asbestos is disposed of at the Walvis Bay hazardous waste site.
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.
Rössing Uranium’s PSM team forms part of the Rio Tinto process safety working group sub-committee, which is tasked with the development of training packages for the Rio Tinto Group.
In 2018, the focus was on the accelerated deployment of the controlled-focused approach as being mandated by the Rio Tinto Energy and Minerals product group. The baseline assessment for both sulphuric acid and anhydrous ammonia was completed.
The main focus in 2019 will be to critically assess current plant process control philosophies on major hazards in collaboration with the processing operations team. The control activities in the controlled-focused approach will be updated with the asset management team, and the quality of the maintenance sheets assessed and amended.
Process safety control activities and the verification of these controls will be incorporated into the existing Critical Risk Management platform. CRM is a report and monitoring tool used by Rössing to manage tasks which could potentially lead to workplace fatalities by verifying that critical controls are in place and indeed effective.
In order to separate Rössing Uranium’s IT system from that of Rio Tinto, the implementation of a stand-alone SAP ERP system commenced during 2018. This project will continue during 2019 with an expected go-live date of April 2019.
The contractor-management system that was established in 2017 to manage and administer contractors was embedded during 2018. A forum, consisting of the executive management team, will ensure that the principles of the system are implemented and adhered to.
Several IT improvement projects were also executed during 2018, such as improving the network coverage in the open pit and at Hill Jim observation point.
In addition, we extended the closed circuit television surveillance system to include nine areas in the processing plant. Benefits derived from this project include, among others, improved safety and security, improved response time to operational failures, improved visibility in obscured areas and reduced health and safety incidents.