Mining at Tati Nickel Mining Company (TNMC) takes the form of applying an integrated spectrum of functions and disciplines within one umbrella of the Mining Department. The department comprises Mining Engineering and Mineral Resource Management functions to deliver the achievement of an often challenging Production Plan.
While best practice, as evidenced in most successful mining houses, tends to detach Mining Engineering from Mineral Resource Management – or vice-versa – TNMC has decided to stick with a combined structure that has adopted the use of outsourced mining or earthmoving services.
The current mix of disciplines is a work in progress as part of an effort to represent the Mining Value Chain Workflow Process through alignment of roles and responsibilities, defining structure and span of control, optimising available competencies and accountability to internal and external stakeholders. The functions forming the Mining Value Chain process can be summarised into Exploration, Mineral Resource Evaluation, Mine Planning Process and Ongoing Technical Services.
Exploration work at Tati Nickel has up to today been near-mine or “Brownfield” (within mine lease), in which case reasonable amount of knowledge exists of the deposit. TNMC has recently adopted a new strategy as new prospecting licenses were acquired in 2010 and early 2011 to take the work towards a more “Greenfield” stage to discover more orebodies beyond the horizons of the mining leases.
The current Exploration programme has more or less continued the good work documented from historical prospecting. Exploration continued to form part of the routine operations at the mine, and the recent acquisition of prospecting licenses form part of an aggressive commitment to extend the mine life and ensure longevity and sustainability for the company as well as harness the reach mineral resource wealth in Botswana.
A substantial amount of geochemical soil sampling work was carried out within the Thekwane East and West license areas from end of 2011 and stopped temporarily during the first quarter of 2012. Preliminary results warrant consideration for further activity, ie tight grid sampling and possible drilling to test viability of the mineral occurrence for eventual extraction potential.
The other prospecting license set for near-future Exploration activity is the Pinagare area. In total six license areas awarded by government were composited into three to form larger, and fewer, areas for internal programme management purposes.
Mineral Resource Evaluation
The Exploration Diamond Drilling programmes and, lately, the Reverse Circulation (RC) Drilling campaigns have over the years provided the necessary primary data input for the mineral resource estimation process at Tati Nickel. The company has benefitted from the employment of mineral resource consultancy over the years to augment the level of technical expertise in all aspects of the estimation process.
Several consulting firms have worked with the deposit before but up to 2010 Anglo American’s MinRED have become the more experienced technical partner with the Phoenix deposit resource estimation work. The evolution of the Phoenix Life of Mine Mineral Resource Model has seen changes in both parameters and technical approach through the years. The inclusion of a 0.10% Ni Volume of Interest (VOI) over and above an existing 0.15 VOI from 2006 through 2009 was a strategic anticipation to exploit the upside potential that exists in the use of the Dense Media Separation (DMS) technology to upgrade previously uneconomic ore.
The latest change in the estimation block size involved switching from a 30X30X30 m size to a 60X30X10 m to address previous challenges associated with the hugely contrasting Smallest Mining Unit (SMU) of 15X15X10 m. A new resource model has, however, now been developed based on the original 30X30X30 m block.
The Mineral Resources reporting following routine resource updates and mining depletions is done in accordance with the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (The JORC Code), which is in accordance with the Canadian Standards of Disclosure for Mineral Projects (National Instrument 43-101) and in accordance with the South African Code for Reporting Mineral Resources and Ore Reserves (The SAMREC Code).
Mine Planning Process
The Planning team employs the use of an optimisation process to generate mineral reserves from updated mineral resources and define the optimal path of extraction of the orebody. This undertaking, which involves the application of modifying factors, has optimal pit designs as well as a final long term business/production plan as delivery outputs.
Tati Nickel’s Planning team has also benefited from engagement of technical consultancy in the optimisation part of the process. The production plan takes the form of a long term plan – up to 10 years – which is further broken down to medium to short term plans of down to a month.
At the moment recent optimisation has left Tati Nickel with an estimated mine life of up to about 2023 taking into account the mining of both Phoenix and Selkirk deposits in a well integrated schedule. This, however, is a dynamic output which is expected to change for the better with current exploration efforts.
The actual mining activity is a contracted service provided by Moolman Mining. Commitment to long to medium term contracts delivers a 22.5 million tonnes per annum mining output in 2012. The same contractor is responsible for providing the equipment and human resources to feed the plant with about 12 million tonnes of ore to meet the 2012 output delivery requirements for the Mining department.
Ongoing Technical Services
Survey, Geotechnical functions, Grade Control and Mining Dispatch Control form the core of the technical services that support the mining process at Tati Nickel. The success of the Grade Control system has been an integral part of the sustainability efforts at the mine since the inception of the mining. This function is the custodian of the Reconciliation and Mine Call Factor (MCF) calculation processes.
A Vehicle Monitoring System (VMS) is in place to manage material destinations and mining statistics. The on-mine Survey function has provided the much needed material volume measurements, stockpile designs and monthly pit face depletion outputs.
The Geotechnical Slope Monitoring programme has evolved to be a key component of the slope stability safety assurance in the pit, whereas other geotechnical data form part of the input into pit optimisation and design.