Mining, Processing and Engineering

Rössing Uranium’s operations consist of two distinct activities: mining uranium-bearing rock and 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 ore 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.

 


Artisan Elieser John, doing welding work at the mine’s plate shop.

Mining operations

In 2017 we mined 25.2 million tonnes of rock (3 per cent more than in 2016) of which 9.6 million tonnes were uranium-bearing ore (20 per cent more than in 2016) and 15.1 million tonnes were waste rock removed from the pit (0.5 million tonnes were in-pit dumping). A waste-to-ore strip ratio of 1.57 was achieved which is significantly lower than 2016 at 1.97, and a ratio of ore milled to waste rock removed of 0.63.

This is a direct result of the Phase 3 pushback intersecting more ore with depth. For the first time, the contribution of ore from Phase 3 exceeded that of Phase 2.

In addition to the increased ore tonnes, came higher uranium grades, as well as a higher calc index. Overall, the grade increased by 20 per cent while the calc index increased by 30 per cent.

A high calc index in the ore has an adverse effect on the extraction of uranium in the Processing Plant, specifcally on the sulphuric acid consumption.

A key focus for the year was on trying to achieve a consistent ore blend to the primary crushers with the highest grade material, but at a calc index which the plant could handle. Operating with tight blending limits highlighted a number of areas for improvement which will continue to be a focus into 2018.

In addition, improvements were achieved in a number of other areas, including maximising haul truck loads.

In terms of safety, 2017 saw a continuation of the safety drives from 2016. The mining team (including the mine maintenance team) achieved a significant reduction in the number of injuries and severe incidents. Segregation of light vehicles and heavy mobile equipment continued and a number of projects were completed that have now almost eliminated this risk on the main access routes. The safety focus for 2018 will be on segregation on the benches in the open pit where traffc types are still mixed.

 


An aerial view of Rössing Uranium's mining operations.

Enhancing productivity and safety: finding shovel teeth
During 2017 Rössing Uranium acquired state-of-the-art technology with the installation of a Ground Engagement Tools (GET) Trakka system.

The system provides support in the operations of heavy mobile equipment used in the open pit by detecting shovel-GET breakage. GETs are tips, lips and wing shrouds of shovels. Sensor tags are placed in a special recess in the shovel bucket GET and collect real-time digging information, which is wirelessly transmitted to a receiver in the shovel. We monitor 13 GETs per shovel bucket.

Upon breakage, an alarm is sounded in the shovel cab, alerting the operator of the breakage and enabling quick identification and removal of the GET and the safe return to production.

The value for Rössing Uranium is in the quick recovery of broken-off shovel bucket GETs before a GET is loaded onto a haul truck, ending up in the crushing circuit which could cause severe damage to crushing equipment and downtime. The implementation of the GET Trakka system provides greater production information and enhances safety and productivity. (See photograph on front page on the use of a GET Trakka scanner to locate broken-off shovel bucket tips or other parts.)

On the maintenance side, haul truck availability in 2017 was a particular highlight, exceeding target and continuing to feature as one of the best in the Rio Tinto Group, despite the age of our trucks and the trolleyassist lines.

In 2018 the productivity focus will shift to cycle times and better utilisation of the trolley lines, with the aim to lower diesel consumption.

While haul truck availability increased, shovel availability on the other hand represented a huge challenge during 2017 and will be a key area improvement focus for 2018.

Processing operations
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 effcient and safe manner possible.

We drummed a total of 2,110 tonnes of uranium oxide in 2017 compared to 1,850 tonnes in the previous reporting year, representing a 14 per cent increase.

 

Engineering Projects

Maximising technology to increase efficiency and productivity

Several engineering projects were completed during 2017.

Replacement of reservoir
One project entailed replacing the heap leach reservoir at the Tailings Storage Facility (TSF) with a redundant tank from the mining area for use as a collection point for seepage water from the different trenches which is then pumped to the so-called lakes. This was necessary as the tank’s structural integrity deteriorated over the years to the point where failure was imminent, therefore the decision was taken to replace the tank.

Transporting and placing the tank in its position was challenging due to the extremely steep and narrow road sections which had to be negotiated with a low-bed trailer and truck. Lifting of the new tank into position required a 220-tonne crane and a secondary 70-tonne crane. The new tank was commissioned on time and without any safety or environmental incidents.

Trolly-assist line at Haul road 16
Following the successful commissioning of Trolley 17 during 2016, equipping Haul road 16 with a trolley-assist line was another engineering project implemented in 2017. As Trolley 13 had not been used after 2016, it was decided to use the remainder of Trolley 13 equipment to complete Haul road 16. Considering the number of truckloads utilising Haul road 16, a tonnage and cash flow profle was derived reflecting a net present value of N$21.4 million for the remaining life-of-mine period. Trolley 16 was successfully commissioned, with a cost saving achieved of approximately N$1.8 million.

Speed and flow controls for pumps
The Projects department was also tasked to design and implement an alternative solution for speed and flow controls for pumps in the Processing Plant. Historically the mine has been using oldertechnology, hydraulic variable-speed couplings (VSCs) to control the speed of pumps and flow-rate in the plant. As state-of-theart, variable-speed drives (VSDs) are more widely used, the older mechanical equipment has become scarce on the market, putting immense strain on maintaining them.

The project was a multi-disciplinary engineering project with a capital plan of N$6 million which included the delivery and supply of various goods and services. It started mid-2016 and was completed mid-2017, due to long delivery times. This project has improved operational performance, maintenance tactics and reduced plant downtime. It is envisaged that the successful replacement of VSCs with VSDs will be continued during 2018, replacing the countercurrent, decantation feed pumps’ VSCs with VSDs.

Installation of in-vehicle cameras
Vehicles and driving are listed as Rössing Uranium’s top critical risks for multiple fatalities. In an effort to reduce vehicle safety incidents or accidents, the engineering team commenced with the installation of in-vehicle cameras to all vehicles that leave the mine site, as well as to the haul truck and heavy mobile equipment fleet. The aim is to promote a safer and more responsible driving environment.

To date, cameras have been installed in all manager vehicles, all buses and vehicles transporting our personnel and 60 per cent of the haul truck fleet. This project will conclude in mid-2018.

Rapid-motion scanner
Demonstrating the engineering team's commitment to working smarter, in another engineering project, the latest technology, rapid-motion scanner (RMS), which is an automated ultrasonic scanner, was used for the first time to carry out ultrasonic testing on tank shells. In line with our storage tanks inspection standards and equipment integrity maintenance process to ensure compliance with the statutory requirements, the condition of four of our onsite tanks in the Processing Plant were evaluated in terms of shell thickness.

The RMS scanner provided safer remote access and no scaffolding or other working-at-height equipment was required to access the higher areas of the tank. In addition, the RMS scanner allowed the team to work faster as the scanner crawled up and down the tank shell at high speed with real-time image display, thus enhancing productivity. The 3D view of the data, clearly showing any defect in the tank thickness, further increased accuracy.

The team has several projects planned for 2018. Among others, the team will upgrade the seepage water recovery system, returning it to a physical condition that will allow operation for a further 30 years, which is 20 years beyond the expected life-of-mine.

Groundwater control and monitoring systems will be reviewed and modernised. The project involves upgrading the monitoring network and to fully automate the system, enabling control from Central Processing Control.

 

Information technology

Two years ago a lost-opportunity reporting system (LORS) application was implemented. LORS is used to record production downtimes and the reduction of production capacity. The need to record downtime events and reduced feed is critical to help the mine’s operations focus on specifc areas and specifc equipment to ensure optimum and continuous production.

During 2017, in line with Rössing Uranium’s critical equipment reliability (CER) mandate, a renewed focus was placed on the information obtained from LORS. With the creation of two new reports, the technical team is now able to get downtime information for individual equipment, as opposed to downtime areas only as reflected in previous reports. The team is now able to view the performance statistics of each item of equipment, which they can then use for maintenance planning.

In addition a contractor-management mandate was established during the previous reporting year to focus on the full governance and administration process of contractors. During the year under review the IT team undertook a gap analysis of these systems at Rössing Uranium operations. This process determined if the current state of the site’s contractor-management system is in alignment with the Rio Tinto Contractor management excellence (CMX) programme and provides information to develop a CMX improvement plan.

Based on its findings, several projects were successfully implemented in 2017, such as the upgrading of the current accesscontrol system to provide accurate clocking data and the seamless integration of gate data with contractual terms to ensure accurate invoicing of contractor labour, equipment and material.

In addition, a new application system was developed to maintain administrative data of the contractor employees onsite which contributed to the streamlining of the engagement, extension and termination processes. This application provides key information on the contractor employees, numbers per contracting company and expiry dates, among others.

The roll-out plan of the CMX framework has been fnalised and the implementation and embedding of this framework will continue during 2018.