Overview
Rössing is the third-largest uranium mine in the world. It is an open pit operation consists of two distinct phases: mining of the uranium-bearing rock or ore, and processing of this ore to produce uranium oxide.
In 2009, Rössing mined 54.5mt of rock and produced a total of 4,150t of uranium oxide
In August 2009, the Rössing Uranium Board of Directors approved the latest life-of-mine operating plan to continue the mining activities until 2023.
Location
The mine is located approximately 40 miles northeast of Swakopmund in the Namib desert of Namibia.
Geology
Rössing is the largest known uranium ore deposit of its kind and has a geological history dating back 700 million years to when the Namib Desert formed part of the sea. The ore body was found to be an enormous low-grade deposit of uranium embedded in tough, abrasive granite known as Alaskite.
Mining & Operations
In 2009, Rössing mined 54.5mt of rock – the most mined from the open pit in the past 26 years. The pit is currently 390 m deep compared to about 100 m deep in 1983, meaning it takes much longer for the haul trucks to cart the rock out of there.
The Fine Crushing Plant crushed 12.4mt of ore, slightly lower than the 12.6mt processed in 2008. However, the grade of the ore was higher overall than was the case in 2008, resulting in more uranium oxide being produced.
Rössing produced a total of 4,150t of uranium oxide in 2009. This is 41t higher than the previous year, which – for the second year running – is the highest production seen by the plant in 20 years.
Waste stripping is to increase from a current 33mt per annum, to as high as 50mt per annum. Additional mining equipment, including a hydraulic face shovel, four haul trucks and support equipment, has already been acquired for this expensive but necessary phase of our mining activities.
A key achievement in 2009 was the introduction of a mining monitoring and control system. This system not only assists operational staff in mining more efficiently, it also allows maintenance staff to monitor the state of equipment online. The information gleaned in this way enables us to take proactive decisions. In the year under review, this online maintenance monitoring system helped to prevent an estimated N$1.8 million in equipment failure.
Mining consists of three main activities: drilling and blasting to break the rock; loading the ore by shovels unto trucks; and hauling it from the pit, either to the Processing Plant if the uranium grade is high enough for efficient processing, or stockpiling the waste in dumps adjacent to the pit.
The uranium in Rössing’s lease 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 in the open pit at least once a week. One blast loosens between 150,000 and 500,000 t of rock, much of which does not contain sufficient uranium-bearing rock to justify processing it. About 3.5 t of uranium-bearing rock is needed to produce 1 kg of uranium oxide.
Electric and diesel-powered shovels load the uraniumbearing ore into haul trucks, which is then transported to the primary crusher for the first crushing stage. From there, the crushed ore goes by conveyor to the Coarse Ore Stockpile, from where it is reclaimed and put through several more crushing stages before the wet processing stage of our operations starts.
To ensure a mine life until 2023 will require an enormous increase in waste stripping in the open pit’s north-western and southern areas over the next four years. Waste stripping entails the removal of blasted rock that does not bear sufficient uranium and, therefore, is not economical to process.
Waste stripping is to increase from the current 33 million t per annum to as high as 50 million t per annum for the next two years. Additional mining equipment, including a hydraulic face shovel, four haul trucks and support equipment, has already been acquired for this expensive but necessary phase of our mining activities.
Processing
The Processing Plant is responsible for the extraction of uranium from the ore via a number of stages to produce uranium oxide, after which it is securely packed and shipped to our customers for further enrichment. The objective is to produce planned quantities of uranium oxide in the most efficient and safe manner possible.
The Fine Crushing Plant processed 12.4 million t of ore, which is slightly less than the 12.8 million t of ore crushed in 2008. However, the grade of the ore was higher in 2009, resulting in more uranium oxide being produced. The focus for 2010 is to consistently crush above 40,000 t per day, enabling us to achieve the target of 14 million t per year.
Leaching is the optimal extraction of a soluble metallic compound from an ore by dissolving it in a solvent, such as sulphuric acid and then recovering the uranium oxide by precipitation. Our leach performance was exceptional during 2009, with an average daily extraction of 88.7 per cent. Plant water consumption was significantly reduced by implementing systems where freshwater usage was substituted by recycled tailings dam solution. By utilising less fresh water, a scarce resource in our desert environment, we demonstrate our business approach of sustainable development.
Since the initial decision was made to extend the life of the mine rather than close it down, a programme was embarked upon to automate the entire Processing Plant. Under the auspices of the Technical Innovation team, the final phase of computer-controlled automation was completed in 2009. This allowed for central control of all the processing steps with much higher degrees of timely interventions, impacting positively on cost efficiencies. Although the automation required extensive capital input, it is an investment in our future that will allow us to reap benefits for many years to come.
