The new 4,800 MW Medupi power station being built in South Africa’s Waterberg coal field is in even closer physical proximity to Exxaro’s Grootegeluk open pit mine than the existing Matimba power station. Medupi, South Africa’s first new base load power station in over two decades and its associated coal supply project, is looking to replicate the success of its predecessor.

Exxaro’s Medupi Grootegluk expansion project in Limpopo province, situated some 40 kilometres from the Botswana border, will see the mine supply 14.6 million tonnes of coal a year to the new power station. This will be the core driver that sees Grootegeluk expand from its current production of about 19 million tonnes per annum (mtpa) to become a 36 mtpa coal producer by 2014/2015. Grootegeluk currently mines 58 mtpa in total and this will grow to 110 mtpa. It is also one of the projects that will see Exxaro Resources, currently South Africa’s fourth largest coal producer by tonnage, challenge to become the country’s largest coal producer. The project will expand the use of the coal reserves in the Waterberg, which accommodates 45% of the country’s remaining coal reserves (75 billion tonnes in situ), a coal field that will play an increasingly significant role in the country’s future, especially in energy provision.

The Waterberg coal field extends for 88 km east to west and also extends westward into Botswana. It extends 40 km north to south, is bounded in the north by the Zoetfontein fault and in the south by the Eenzaanheid fault. Another fault, Daarby, divides the coal field into open pit mineable and underground mineable reserves, with the latter located some 260 metres below the surface.

Grootegeluk’s mineral rights cover six farms in the shallow portion of the coal field, while Exxaro also has the exploration rights to an additional five adjacent farms on which it has another project in mind, Grootegeluk West, currently in pre-feasibility stage. Part of the Ecca group of coal deposits, the mineable seam of the Waterberg, which contains 11 coal bearing zones with a thickness of 115 metres, is much thicker than that of Mpumalanga’s Witbank coal fields.

At Grootegeluk there is an overburden of only 16.5 metres, which eliminates dragline mining as a viable option, since the dragline would not be utilised efficiently and would stand idle for too much of the time. The first four benches of the Grootegeluk mine range from 15 to 17 metres in height, and contribute power station and coking coal, while benches six to 13, which range in height from four to eight metres, supply metallurgical and power station coal.

The coal for the Medupi project is not expected to differ greatly from that produced already. The present mine will continue to be mined in the westerly direction for another eight kilometres. Then it will turn back on both flanks. This will enable Grootegeluk to supply the Medupi and Matimba power stations with enough coal over the next 45 to 50 years.

The conveyor from the mine to Medupi, which will be the biggest power station in South Africa to date, will extend some three kilometres and supply 50,000 to 55,000 tonnes a of coal a day. The current Grootegeluk pit is 3.3 km by 3.2 km and has a depth of 115 metres. Mining at Grootegeluk is by means of a three Demag 285 hydraulic shovels (used on the lower benches), one Demag 455 shovel (used on the upper benches), two cat 994s, 24 trucks (Euclid 180 tonne and 260 tonne trucks and haulpack 200 tonne trucks), and six P&H 2300 rope shovels (also used on the top benches), in addition to all the ancillary equipment. The mine uses an electrical pantograph trolley assist system to reduce fuel costs, with this done from flat surface in the pit to flat surface outside the pit.

Grootegeluk also boasts the world’s largest coal beneficiation operation, with six different plants. The first, GG1, which produces semi-soft and power station coal, was established in 1980. The GG2 and GG3 plants were established in 1990 and 1992 respectively to supply additional power station coal, with the GG4 and GG5 plants established between 1996 and 1998. The most recent plant, GG6, established in 2006, beneficiates 700,000 tonnes of semi-soft coking coal a year as well as power station coal.

Grootegeluk supplies 15 mtpa of power station coal for Matimba. “The dry cooled 3,900 MW power station has proven to be South Africa’s cheapest and most reliable base load station and is very well managed,” Joe Meyer, general manager of the Medupi Grootegeluk expansion project says.

GROOT

Grootegeluk coal mine in
the Waterberg coal field.

“Matimba, which burns 20.5 calorific value 35% ash coal, started off as a six unit 3,600 MW power station, but it has upgraded to produce more and is the best performer on the grid. Together we have earned the right to grow in the Waterberg coal field, and the Medupi environmental impact assessments, both for the mine and the power station, showed no significant impacts. If Medupi achieves the same level of performance as Matimba, the 14.6 mtpa of coal we supply to Medupi could also increase in the future.”

In addition to power station coal, Grootegeluk produces 1.5 mtpa of metallurgical steam coal in the form of small nuts, peas and duff. It also produces 2.5 mtpa of semi-soft coal with 10.5% ash content and this is supplied to the steel industry as coking coal, with Mital being the biggest customer. “Further, we export about one mtpa through the Richards Bay Coal Terminal (RBCT) using some of Exxaro’s RBCT allocation.

The Medupi mine project will feature the latest technology; the tipping bins and crushers will be mobile units that will be used in-pit close to the benches and will move as the mine move forward. The plant is planned to ensure no slimes need to be pumped to tailings dams and to that end dry screening will be introduced on the Run of Mine (ROM) stockpiles. The stockpiles between the mine and the plant and between the plant and the discard stackers on the discard dumps will ensure more support for continuous production.

There will be pre-screening using high frequency screening technology with the – 4 mm material going directly to the product stockpile. The rest will be screened again to a fine and large fraction. The finer fraction will be beneficiated in cyclone plant and the larger fraction in large Larcodem plant. The processing plant will use press filters, in the form of bag filters to dry the fines from the thickeners, and the coal delivered to Medupi will have low moisture levels. The plant will feature a 400,000 tonne blending bed, with two stackers and two reclaimers so as to ensure proper blending and additional drying time for the coal.

A key feature of the Medupi project is that Exxaro has elected to undertake the project management role in-house with the support of the best consultants and contractors. This goes counter to the trend where there has been a hollowing out of project expertise inside mining companies. However, Meyer says that Exxaro has a pipeline of projects planned on an ongoing basis over the next 15 to 20 years. This justifies having project expertise in-house. “We would like to establish a strong alliance with consultants, suppliers and contractors for future projects."

Meyer says, “The scope of the project entails mining equipment similar to what we are using at present, mobile tipping and crushing units, ROM and discard stockpiles, screening, beneficiation plants, thickeners and filter presses, a stockyard for stockpiling coal ready to send to the power station and conveyors to supply the power station, as well as all the civil and electrical services to support all the processes.

MEDUPI CONSTRUCTION

Medupi construction site with
Matimba power station in
background.

“We are aiming at a high confidence level of our front end loading before we do the detailed design in 2009. We are working hard to ensure the front-end work is done well, since that is the most important aspect to get right. One cannot recover from poor front-end work.”

The project management system being used is based on the Project Management Body of Knowledge (PMBOK). “This is supported by other best practices and lessons learned from recent large projects. We will use Full Work Breakdown Structure methodology to ensure all gaps are covered right down to activity and equipment level.

“We envisage that our team will be in control of the preparation, design, construction and hand over phases. Consultants will be contracted to ensure a full detail design so as to ensure the best possible procurement strategy and processes. At the same time, a very competent team of project managers, senior engineers, project specialists, procurement specialists, project control manager, project schedule experts, quality assurance experts and cost engineers have been employed and are all involved with the preparation to execute a successful project. People alignment and team dynamics have been implemented and will be a prime focus throughout the project and will include all the consultants, contractors and stakeholders.

“We will have a mix of both large, medium and small contractors, depending on the capacity and capability available.” The project (R9 billion) has been split into five sub-sections with the project manager of each section being responsible for some R1.5 billion. The project is also split into disciplines including metallurgical, mechanical, chemical, electrical, structural and civil. All contracts will be on open tender.

The feasibility study for Medupi’s Grootegeluk expansion was completed in August 2008, and the detailed design phase will take place from February 2009 through to early 2010. The resource and reserve calculation is being done to the highest level with confirmation drilling on a 250 metre grid.

The first construction work on the expanded mine will begin early in 2010, and will build up accordingly to supply each of the six new units at Medupi, which are expected to come on stream from the end of 2011 to completion by 2014 at six to nine month intervals.

“We will start ordering the long lead time items at the beginning of 2009,” Meyer says. The project team is weighing up the option of manufacturing some of the required plant in China, where it is cheaper ex-works and much quicker to complete. The question in comparing this with local manufacture is whether the cost of transport logistics outweighs this benefit.”

Meyer believes that the power station and mine project will make the nearby population centre of Lephalale, which currently has a population of 80,000 people into the fast growing part of the country. During the construction, up to 7,000 jobs will be created on site at the Medupi power station. The construction at the mine will create up to 2,000 jobs. At least half these jobs could be accessible to people from Lephalale, with further growth in jobs in the Lephalale private and public sectors as the town is expected to grow by 60%.

One of the challenges in a region with low levels of water is the supply of water. The Mokolo dam will supply the mine and the first three units of Medupi, after which additional water will be required. The Department of Water Affairs is planning for this, with water to be supplied from the Crocodile River.

Meyer identifies among key risks to the project the possibility of capital cost escalation due to very high construction escalation, and very high demand for design and construction services for the next 10 years with concomitant high prices. He also sees very high demand for manufacturing and supply of equipment, material and services and the resulting delays this can cause, as a risk, not to mention shortage of skills during this high demand phase the mining sector is experiencing. Another risk is a shortage of local government infrastructure to support the growth.

GROOT ELEC

Grootegeluk uses an electrical
pantograph trolley assist
system.

However the project should be aided by the fact that it must be a national priority project. South Africa has 12 base load stations accounting for 34,000 MW, and between 2025 and 2035 many of these will begin to reach the end of their planned lives. Coupled with average annual economic growth expectations of 4% to 6% the country will need a number of additional Medupis, as part of the anticipated 20,000 MW to 25,000 MW coal fired power station replacement and growth programme. Nuclear energy and renewables will have a role in South Africa’s energy mix, but the capacity of the Waterberg coal field to produce some four or five more new power stations on the scale of Medupi will see further developments along those lines.

There are also downstream beneficiation plans, with a char plant due to be commissioned this year. Exxaro is also busy with a feasibility study to produce another 500,000 tonnes of market coke in the near future, and the prospects of off-gas electricity generation to supply the mine with its own power is being investigated.