Mining, Processing and Engineering
Our operations consist of two distinct activities: mining uranium-bearing rock, and processing this ore to produce uranium oxide for the world's nuclear energy market for the generation of electricity. All our attention is directed towards creating shareholder value and keeping the business safe and viable, as well as towards ensuring that we remain a long-term contributor to Namibia's economy.
The uranium-bearing ore at Rössing Uranium is mined through drilling, blasting, loading, and hauling from the open pit. The ore is delivered to the primary crushers. It passes through a further series of crushers and a grinding process before extraction of the uranium can be done. Checking on the production in the open pit are haul truck operator Oligen Lucas (right) and mining engineer Protasius Aluvilu.
The uranium in our mining licence area is found in very hard and abrasive granitic rock, called alaskite. To move the required amount of ore and waste, we have to conduct blasting operations at least once a week. Electric and diesel-powered shovels load the uranium-bearing ore onto haul trucks, which then 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 several more crushing stages in the Fine Crushing Plant, before the processing stage of our operations begins.
No exploration and prospecting work were performed during 2015. The Z20 deposit remains part of Rössing Uranium's resource for further development, pending improvement of market conditions. No additional exploration is planned for 2016.
Mining production was reduced to match the processing capacity of the plant in line with the mine's change-over to a three- panel shift roster and a five-day operations schedule since August 2014. This followed a Board of Directors' decision to curtail production to meet only contractual commitments, with the resulting curtailed production plan. By October 2015 the mine returned to a four-panel shift roster and a seven-day operations schedule to increase production.
Against a plan of 18.9 million tonnes, we mined a total of 19.3 million tonnes of rock from the open pit during 2015, compared with 23.3 million tonnes in the previous reporting year. Of the 19.3 million tonnes of rock mined, 6.8 million tonnes were uranium-bearing ore, while 12.5 million tonnes were waste - giving a waste-to- ore strip ratio of 1.80 and a ratio of 0.55 in respect of ore processed to waste rock removed, with 0.1 million tonnes of ore processed from stockpiles.
The north-west part of the open pit, referred to as Phase 2 of the SJ Pit, was the main source of uranium-bearing ore during 2015.
In addition, waste stripping in Phase 3 of the south-eastern part of the SJ Pit tapered off to produce more ore. While the grade of the ore was as expected, the calcium carbonate (calc) level increased to a level higher than expected.
A high calc index in the ore has an adverse effect on the extraction of uranium in the Processing Plant.
A key focus during the reporting year was to continue with opportunities to improve productivity and reduce costs across all of the main mining activities, ie in drilling, blasting, loading, hauling and ore supply.
Significant cost savings were indeed achieved and the total cost for mining operations was 10 percent under budget.
Investigating a number of the cost-saving activities will continue in 2016, namely to benefit from an improved cycle time for haul trucks, hauling waste to stockpiles closer to the open pit. In ore supply a higher proportion of direct feed from the pit, together with reclamation from run-of- mine stockpiles, is expected to provide cost savings on reduced equipment hours.
A key focus in 2015 was improving the effective utilisation of mining equipment even further through initiatives such as multiskilling and improving operator attendance at work.
Following a reduction in the use of explosives during 2015, a study on improving blast fragmentation will be carried out in 2016.
The return to a four-shift panel required the recruitment in August of 70 mining operators to fill vacancies. Following training of the mining operators, an increase in mining was notable by December 2015.
The objectives in 2016 are to improve availability of mining equipment, maintain a high effective utilisation of the equipment, and improve scheduling, together with an upgrade of the mining dispatch system.
The production target for 2016 is to mine 27.5 million tonnes, crush 10.2 million tonnes and drum 2,051 tonnes of uranium oxide.
The Phase 4 plan for expansion of the SJ Pit in the north-east area will see activity on the pre-feasibility study. The plan will become part of the life-of-mine plan in order to be ready when the uranium market price improves.
The Processing Plant is responsible for the extraction of uranium from the ore through a number of stages to produce uranium oxide (U 3 O 8 ). Our product is then securely packed and shipped to our customers for further conversion. The aim of the plant is to produce planned quantities of uranium oxide in the most efficient and safe manner possible.
In terms of milled production (ore that is crushed and ground to liberate the mineral particles) 2015 started off on a positive note, closing the first month of the year with 9 percent above target.
Unfortunately in February a fire broke out in the roaster area of the Final Product Recovery (FPR) Plant, derailing production plans.
We decided to continue with mill produc- tion by increasing the tank storage capacity in the FPR and to store yellow cake, whilst the Roaster rebuild project was underway.
By doing this, we could continue with production, while delaying uranium oxide shipments and sales to later in the year, once yellow cake calcining resumed.
We completed the Roaster rebuild project on time and on budget. In May we restarted roasting and calcining the stored yellow cake, as well as with drumming of uranium oxide. From the middle of the year, we started sending out our shipments and making sales again.
In total we drummed 1,245 tonnes of uranium oxide compared with 1,543 tonnes in the previous reporting year.
We also made great strides in terms of improving the useful life of the plant and reducing the maintenance debt on major pieces of equipment.
We completed a successful major maintenance shutdown in July, maintaining critical pieces of equipment and upgrading the Honeywell Mining 2 system in the Central Processing Control (CPC) room.
Throughout the year we continued working on the Tank and structural refurbishment project and completed major refurbishments on a number of leach tanks and other critical vessels around the plant.
We also experienced major challenges at the counter current decantation thickeners and at one stage experienced only 50 per cent availability of thickeners, exposing us severely. With the help of the Maintenance and Engineering departments, we finalised an approach to get these vessels back online and maintenance up to date as soon as possible. This will be a major focus area for 2016.
In October we resumed our operations on a seven-day, 24-hour basis from the five-day, 24-hour basis we operated on since the fire in the FPR Plant. This was a critical step in achieving our throughput targets.
In December mill production exceeded operating target and achieved a milestone 890,000 tonnes - the highest production since the leach tank failure in December 2013. This confirmed the steady improvement in our plant's performance.
Working at a loading zone in the open pit, shovel operator Salome Maletzky loads ore on to a haul truck.
Three important projects that we finished successfully during the reporting year were the Buttress project, Starter embankment project and the Fine Crushing Plant ducting replacement project.
An exciting project scheduled for 2016 is the High calc (calcium carbonate) project. In the following years we expect to mine higher grade ore with a high calc index, and thus it is important for the plant to be able to process it. The High calc project will improve the plant's ability to handle higher calc ore, which is critical.
Buttress project and Starter embankment project
The scale of these two projects is massive and we commissioned the contractor Fraser Alexander to help us with the construction of the buttress (or support structure) to improve the stability of the Tailings Storage Facility (TSF).
They also constructed the starter embankments for the new paddocks where tailings will be deposited in the coming years. We already started depositing tailing in our new paddocks during the year under review.
The project enlarged our TSF substantially, giving us extra tailing storage space for the rest of the life of mine.
The project was completed successfully and on time.
Fine Crushing Plant ducting replacement project
During the past few years managing dust generation and spillages within the Fine Crushing Plant was a major challenge.
The dust needs to be collected in ducts, transported to suitable storage bins, and then be removed and reintroduced into the system in a sensible manner without creating a hazard.
Although the plant is equipped with dust collectors, the abrasiveness of the dust wears out the ducting. Once the ducting loses its integrity, the dust becomes airborne. This creates both a health and a safety hazard, as visibility becomes impaired.
During 2015 all deteriorated dust ducting was repaired and replaced. Although there is still some work that needs to be done, the bulk of the project was completed successfully.
We already saw an improvement in the dust management at the Fine Crushing Plant.
During 2015 the Projects section was responsible for designing and implementing various capital and operational improvement projects.
Final Product Recovery fire
Unfortunately, on 12 February 2015, we had a fire in Final Product Recovery's roaster area. Most importantly, no one was hurt during this incident.
The Roaster rebuild project, with support from the Maintenance Improvement section, was completed on time and within budget, getting us back to full production by May.
Major maintenance shutdown
In July we had a successful, major maintenance shutdown, doing maintenance on critical pieces of equipment. We used this opportunity to do upgrades of our Honeywell system in the Central Processing Control room. We also completed major refurbishments on a number of our leach tanks and other critical tanks around the plant.
Tailings Storage Facility
Two important projects that we finished successfully during the year were the Starter embankment project and the Buttress project for an amount of N$100 million. This enlarged our Tailings Storage Facility and provided us with extra space for the rest of the life of mine.
Fine Crushing Plant ducting replacement project
The Fine Crushing Plant ducting replacement project was successfully completed and although there is still some additional work to do, we already saw improvement in dust management in the area.
Leach and other tank refurbishments
Following the failure of one of the leach tanks at the end of 2013, we initiated an overall programme for the refurbishment of metal structures and tanks across the mine site.
In total 84 process tanks containing various types of materials and chemicals were assessed and repair work prioritised accordingly. From this assessment we identified 30 tanks that need repairs over the next three years. To execute this refurbishment programme we established a separate project management team to be assisted by two contracting companies.
Reagent Plant upgrade
The construction work on this project was interrupted three times with the civil, mechanical and electrical contracts that had to be cancelled as a result of non- performance. The project commenced in 2013 and will now continue into 2016.
The plant is being constructed next to the Reagent Store that was completed end of 2014. Once the plant is completed it will eliminate the need for a permanent mobile crane to batch the reagents and will reduce the dust pollution caused by handling megabags.
Walvis Bay acid offloading to facilitate decanting of rail tankers into storage tanks
The take-or-pay agreement for sulphuric acid supply from Dundee Precious Metals from Tsumeb brought forward the risk of oversupply in the event of the Processing Plant not being able to consume as planned. In order to manage the risk it was decided to create the opportunity to offload rail tankers iinto stroage tanks n Walvis Bay. The project commenced during the third quarter of 2015 and is scheduled to be completed during the second quarter of 2016.
Looking at 2016
Unfortunately we experienced some major challenges with our counter current decantation thickeners during 2015 and at one stage had half the number of thickeners offline. With the assistance of the Maintenance and Engineering departments we finalised an approach to get these vessels back online and maintenance up to date as soon as possible. This will be a major focus area in the new year.
Another important project scheduled for 2016 is the High calc project. This will improve the plant's ability to handle ore with a higher calcium carbonate concentration. This is critical, as the higher uranium grade expected for the foreseeable future also comes with high calc concentrations and thus it is important for the plant to be able to process it.
We collected operational data since the inception of Rössing Uranium nearly 40 years ago. The data and reports generated over the years contain all the laboratory test work and trials, plant test work and trials, investigation reports, fault finding reports, changes and new implementations. In addition, the library in the Processing Plant contains information on our original plant design, operating procedures and reports from consultants.
During the reporting year we launched a pilot project in the Processing Plant to restructure the shared hard drives and library according to Rio Tinto's file plan structure.
We aim to implement an integrated web- based solution for electronic information or document management that will enable us to access documents through a secure environment for data validation and audits, thereby reducing redundancy and complexity.
This will ensure that data is not lost and can easily be retrieved when needed. The lessons learned from this pilot project will be considered when this solution is rolled-out throughout the mine during the coming years.
Efficient control of printing
During the previous financial year we initiated a system to control and manage the office printing needs throughout the company.
During the reporting year we replaced all the office printers with 103 new printers and installed printing management software. This centralised printer monitoring software enables us to track and monitor devices and printer consumables in a cost-effective manner.
We also introduced Follow-You printing functionality, which can help reduce waste, while improving security.
The company's heavy mining equipment maintenance teams take great care to follow maintenance schedules which involve inspecting and testing the equipment, among others. Berno Peterson (Electrician), Angelo Nel (Fitter) and Romano Shaduka (Fitter) are busy with the fitment of a haul truck wheel motor in the Heavy Mobile Equipment Workshop.