Exxaro Resources limited
Consolidated Mineral Resources and Mineral Reserves report 2021


Matla is a captive underground coal mine that extracts thermal coal that is crushed, screened and sized before it is delivered directly to the Eskom-owned Matla power station via a network of conveyor belts. There is potential to increase RoM through successfully implementing and executing the three major expansion projects that are at various stages of implementation. A major milestone was reached in 2021 for the Mine 1 relocation project through the completion of the boxcut. Through the review of the LoM and innovation from the Matla team, investigations on additional mining ground are ongoing.

Matla overview

Table 30: Matla overview

Location 15km west of the town of Kriel in Mpumalanga, South Africa


1976 to 1990

1990 to 2006

2006 to 2021

Previous ownership

Trans Natal Mines



Material notes

Construction began in 1976 with full production in 1983

Rights ceded to Exxaro in 2006

Continuous exploration drilling. Mine in operation for approximately 38 years.

Adjacent properties

The well-known Kriel coal mine neighbours Matla mine to the east and the operations of Khutala (South32) and Zondagsfontein (Anglo American) to the north.


Matla is on the P53-1 and R547 secondary roads branching off the R580 and R545. Existing infrastructure of the three shaft complexes includes three ventilation shafts, a network of conveyor belts, coal silos and stockpiles, a crushing and screening plant, four pollution-control dams, hospital, accommodation facilities, offices, workshops, and a water treatment plant. Potable water is received from Eskom and no potable water plant exists on the mine property. Electricity is sourced from Eskom (Matla power station) and transporting coal from the mine to Matla power station is via a network of conveyor belts.


Matla mine is in the Highveld coalfield, immediately south of the Witbank coalfield. The coal seams are found in the Vryheid Formation of the Karoo supergroup. The stratigraphy sequence in the Matla area includes five coal seams that can be easily correlated with seams found in the Witbank coalfield.

Main seams

The principal economic seams currently exploited are S2 and S4 with mining of S5 terminated in 1998 due to high levels of contamination and subsequent increase in abrasive index.

Seam development

Coal seams in the area are generally flat and continuous with subsequent igneous activity resulting in displacements and devolatilisation of coal seams at places.
The 5 seam is most prominent in the Mine 2 and Mine 3 areas and, to a limited extent, in the western limb of the southern part of the mining right area. The roof comprises approximately 0.5m of thick sandy micaceous shale at Mine 2 that thickens up to approximately 1.6m in Mine 3. The seam consists of mixed coal and torbanitic material with an average thickness of 1.5m. Economic S4 exists in the Mine 1, Mine 2 and Southern Reserve areas, and to a limited extent in the Mine 3 area. At Mine 3, the seam splits into two thin, poor-quality horizons towards the west, and is thus excluded from the mineable reserves. The best quality S4 may be found at Mine 1 and at the eastern edges of Mine 2. The seam is composed of dull lustrous coal interspersed with bright coal bands. In-seam partings typically consist of discontinuous lenses of shales and siltstones less than 0.1m thick but these may thicken locally to 0.3m. Carbonaceous limestone lenses are also prevalent within the central portion of the
Mine 2 area. The S2 at Matla is well developed in the north-western part of the mining area in the mines 2 and 3 Resource areas. It thins out to the south, where thickness averages at 1.2m to 2.5m. Much of the coal in this area is mined as a low seam. Much of the S2 is burnt by a prominent dolerite sill between the Mine 2 and Mine 1 as well as in the western and south-eastern portions. Coal qualities are also generally poor in this area thus S2 is not generally mined in the southern portion of the mine area.

Depositional control

The coal was deposited on glacial sediments of Dwyka tillite, which in turn was deposited over a granitic basement. The Matla mining area is characterised by two distinct dolerite types, the B8 (porphyritic) and B4 (olive-rich) types which have varying effects on seam displacements and coal burning and devolatilisation. A dolerite sill with an average thickness of 10m is generally found above S5 in mines 2 and 3. However, the sill intersects the coal seams and underlies S2 in Mine 1 and S4 on the south-western part of the Reserves. This sill has burned and devolatilised S2 on the southern part of the mining area in Mine 1. Floor rolls have been encountered in S2 workings and created some challenges in some mining sections. The floor rolls strike north-east-south-west, vary in width between 50m and 200m and have amplitudes up to 1.5m. The floor rolls are more prominent if the seam floor is close to the basement contact. Sandstone lenses encountered are generally less than 0.5m in width but can reach up to 1.5m in thickness.

Resources and Reserves

Coal Resources and Reserves occur within the domains of mines 1, 2 and 3. The Coal Reserves are aligned with the existing LoMP.

Mining method

Matla comprises three underground production facilities: Mine 1, Mine 2 and Mine 3. All three are long-life assets, each with a specific operating capacity comprising conventional coal circuits to produce bituminous coal. Work at Mine 1 was stopped in 2015 due to pillar instability but an Eskom-approved project to relocate
Mine 1 access is currently in the implementation phase. Mine 2 and Mine 3 use bord-and-pillar and shortwall methods to mine S2 and S4 coal seams.


None of the coal mined at Matla is beneficiated but is crushed and screened (sized) before being conveyed to the power station.


Matla mine produces thermal coal exclusively for Eskom.


Captive market: Eskom

Mining right

Matla has an approved mining right that covers some 23 494ha.

Environmental approvals

All environmental appeals have been favourably addressed for the declared Reserves except for one that has expired but is under renewal.

Projects/Feasibility studies

Three major LoM projects exist at Matla, namely the Matla Mine 1 relocation project (MM1R), the Northwest Access Decline project (NWA decline) and the Northwest Access Incline project (NWA incline). The MM1R is currently in progress and includes the construction of a boxcut, portals, silos and overland conveyors which creates a new access point to Mine 1, with conveyor infrastructure transporting the coal directly to Matla Power Station. The NWA projects are two separate projects where a decline and incline will be constructed at Mine 3 and Mine 2 respectively to unlock future Coal Reserves. The NWA incline is currently in progress where the incline connects existing Seam 2 workings to the 4 Seam to allow extraction of the 4 Seam through Mine 2.

Figure 11: Matla mine

Malta mine

Figure 12: Matla cross-section

figure 12 matla cross section

Resource estimation

Table 31: Resource estimation methodology and reporting

Drilling, logging and sampling

Surface vertical, surface inclined and underground horizontal drilling methods are employed at Matla. Of these, only the vertical surface drill holes are used for resource modelling.

All drill holes are geologically logged on a detailed log sheet with the content dictated by the Exxaro logging procedure. Logging is conducted by recording of lithology down to 1cm detail on logging sheets, according to the classification of the lithology. Once all core and sample markings are in place, the core is photographed on a 1m interval basis.

Once correlated, sample intervals are defined based on lithological contacts and logical boundaries along the drill hole, across the named intervals or seams. If the entire unit is homogenous samples are then collected at 1.5m intervals.

All samples are placed into plastic sample bags, and a sample tag is placed inside the bag, with a duplicated attached to a cable tie on the bag's exterior. The sample tags are used to identify the samples according to a sampling convention, which is recorded in the log sheet and geological database as to allow the laboratory results to be assigned to the correct interval in each specific drill hole.

Laboratory and accreditation

Siza Coal laboratory, SANAS T0447

Laboratory dispatch and receiving process

All samples collected and bagged are registered in a sample sheet which is also used as a dispatch sheet. All exploration samples are weighed on site prior to dispatch and recorded at the mine. The laboratory reports the weight of each individual sample, and these results are compared to the mine weights to validate that the correct samples were conveyed correctly and safely to the laboratory. The dispatch sheet is signed by the receiving laboratory personnel after ensuring that the number and sample ID on the dispatch sheet matches that of the actual samples that should be analysed. The analyses required are also clearly explained in the sample dispatch sheet.

Laboratory quality control and quality assurance

Matla conducted QA/QC on Siza laboratory processes and equipment in 2020. Siza laboratory also does internal validations and checks as part of their QA/QC programme. Siza partakes in round robins.

Data datum

Cape datum - LO29

Drill hole database


Number of drill holes in mining right

3 321

Number of drill holes used for Resource estimation

S2 – 2 523

S4 – 2 222

Number of drill holes used for classification

S2 – 1 659
S4 – 2 116

Data compositing and weighting

Conducted in Geovia MinexTM

Data validation Conducted using queries in acQuire and Excel
Geological modelling software Geovia MinexTM
Estimation technique Growth algorithm
Previous model date 2019
Last model update 2020
Grid mesh size 25m x 25m
Scan distance 2 000m
Data boundary 200m
Model build limits Upper: limit of weathering and topography/collar
Lower: basement/Dwyka
Model outputs Roof, floor and thickness grids generated for structure
Raw quality grids
Changes to modelling process None
Thickness cut-off and extraction height considerations ≤1.8m and ≥4.8m
Quality cut-offs (adb)

DAFV ≤26%

CV ≤15MJ/kg, Ash ≥50%

Geological loss applied

10% (may vary considering RODA)

Table 32: Resource classification criteria

Measured Cored drill holes with applicable coal qualities 0m to 350m Infill drilling is conducted where basement highs and or seam structure creates uncertainty around continuity. S4 – 0.1
S2 – 0.1
Indicated Cored drill holes with applicable coal qualities 350m to 500m Infill drilling is conducted where basement highs and or seam structure creates uncertainty around continuity. S4 – 0.1
S2 – 0.1
Inferred Cored drill holes with applicable coal qualities 500m to 1 000m Infill drilling is conducted where basement highs and or seam structure creates uncertainty around continuity. S4 – 0.1
S2 – 0.4

Table 33: RPEEE considerations

Geological data Cored drill holes with applicable coal qualities Yes Seam depth ≤40m, seam thickness ≤1.8m and ≥4.8m, dry ash-free volatiles ≤26%, air-dried CV≤19.5MJ/kg and ash ≥50% with coal qualities reported on an air-dried basis.
Geological model Geological model has been considered and signed off Yes 2020
Structural model Structural model was considered and signed off Yes 2020
Mining Mining assumptions considered and defined Yes underground
Assurance Exxaro internal audits and external audit conducted Yes 2019 (model and chain of custody)
Economic evaluation Exploitation study with economic and mining assumptions, including geotechnical and geohydrological assumptions Yes LoM exploitation study
Environmental Reasonable demonstration that environmental approvals can be obtained within the context of local, regional and national governmental legislation Yes Current required approvals in place or there is reasonable expectation that outstanding approvals will be granted. Additional requirements can be demonstrated in the context of local, regional and national legislation. Land acquisitions for future stooping can be achieved based on the current acquisition strategy.
Tenure Formal tenure must be demonstrated with reasonable demonstration that a mining right approval can be obtained within the context of local, regional and national governmental legislation Yes The mining right expires in 2025. Application to renew is in process and there is reasonable expectation that it will be extended with no impediments noted.
Infrastructure Assumptions used should be reasonable and within known/assumed tolerances or have examples of precedence Yes Current infrastructure
Market A potential market for the product with a reasonable assumption that this market is sustainable Yes Current coal supply agreement (CSA) in place until 2023. Negotiations to renew are in process. Exxaro has reasonable that the CSA will be renewed.

Reserve estimation

Table 34: Reserve estimation

Software XPAC
Reserving process

Scheduling of the Coal Reserve is determined using mine scheduling applications from XPAC and ProgCad. The geological 3D model used for the Coal Reserve estimation is referred to as the Reserve 3D model. The Coal Resource model uses the full coal seam while the Reserve model only defines a select mining height. The process ensures the model represents reality regarding the technical capability of current production equipment.

Resources are converted to Reserves where the Resource confidence, continuity and other factors (including economic, environmental, safety and social aspects) allow for the reasonable expectation of successful extraction. Reserves are converted using modifying factors which account for layout design and associated losses. The Reserves stated are subject to verification according to an approved fact pack, which sets out the standards and considerations for all reserving and scheduling processes. This document is reviewed annually and vetted by all relevant stakeholders.

Conversion classification At Matla, Indicated Resources are generally converted to Probable Reserves and Measured Resources to the Proved Reserve category, except if any modifying factors have not been (partly) fulfilled, where the Resource is either not converted or downgraded to the Probable Reserve category, clearly stating the outstanding requirement and risk.
Inferred Resources inside LoM Some 7.6Mt of Inferred Resources are included in the LoMP, representing 4.7% of the LoMP, and are not considered material.

Modifying factors

Average thickness cut-off ≤1.8m and ≥4.8m
Quality cut-offs DAFV ≤26% and CV ≤19.5MJ/kg
Mining loss Already included in model, based on specific geological conditions and mining restrictions
Depth to roof 40m unless rock strength allows otherwise
Safety factor Tertiary panels 1.6 and main development 2.0
Bord width 7.2m
Barrier pillar At least equal to pillar width
Boundary pillar 15m
Mining height ≤1.8m and ≥4.8m
Extraction factor Already included in model
Dilution Already included in model
Contamination Use select seam
Practical plant yield N/A
Strip ratio cut-off N/A
Environmentally sensitive areas Areas underlying wetlands and other eco-sensitive areas are excluded from Reserves. A higher safety factor is used underneath rivers and surface structures.
Legal Applicable mining right considered
Social Applicable mining right considered
Geohydrological Applicable surface and groundwater models considered.

Table 35: Matla Coal Resource and Coal Reserve statement

Category  2021 
Difference in  tonnes 
Reason for change 
Measured  639  694  (55) (8) Reduction of 8Mt through depletion and 47Mt reduction due to the removal of isolated remnant coal blocks that did not meet the RPEEE criteria.
Indicated  114  123  (9) (7) Reduction of 1Mt through depletion and 9Mt reduction due to the removal of isolated remnant coal blocks that did not meet the RPEEE criteria.
Inferred  93  151  (58) (38) Reduction of 2Mt through depletion and 55Mt reduction due to the removal of isolated remnant coal blocks that did not meet the RPEEE criteria.
Total Coal Resources  847 968 (122)  (13)  
Proved  124   148   (24)   (16)   Mining depletion 5Mt, 4Mt reduction due to LoMP changes relating to areas of burnt coal and 15Mt downgraded to Probable Reserve due to surface land ownership required for stooping.
Probable  38   22  16   74   Mining depletion 1Mt and 2Mt increase due to LoMP changes related to new information and the remainder is due to reclassification from Proved Reserves.
Total Coal Reserves  162  169  (7)   (4)     
  • Rounding of figures may cause computational discrepancies.
  • Tonnages quoted in metric tonnes and million tonnes (Mt). Coal Resources quoted as MTIS.

Exploration summary

Summary of the exploration for the reporting year is outlined in Table 20. For detailed expenditure, refer to Table 54.

Table 36: Matla exploration sum

Increase geological confidence in S2L Mine 3 area

Surface directional drilling was conducted in the main development access of the planned low seam LoM to ascertain dyke behaviour and coal continuity.

Areas with dykes and fractured coal zones, which were identified through directional drilling, will be targeted in the 2022 vertical exploration campaign.

Infill drilling in planned future mining areas of Mine 2 and Mine 3 (S2 western resource) Infill drilling was conducted at Mine 2 Eastern Reserves to confirm coal continuity and quality. Further drilling is planned for the Mine 2 Eastern Reserves as well as the Mine 3 S4 medium-term mine plan.
Mine 2 S4 project area dolerite definition and displacement delineation Surface directional drilling was conducted in 2020, which was used to redefine the mine design for the 2021 reporting year. No drilling is planned in this area for 2022.


Table 37: Matla risks

Eskom purchasing of surface farms to commence with stooping Require ownership of farms where stooping is planned. Eskom to purchase surface ownership of a list of farms as per CSA.
Environmental authorisation for stooping The environmental management plan for total extraction on stooping can only start if the surface land belongs to Eskom. Eskom needs to purchase ownership of a list of farms as per CSA.
Geological structures Geological faulting as well as the impact of sill and dykes are very pertinent challenges in all three of the Matla mine expansion projects. Unforeseen geological structural complexity (faulting and intrusives) poses risk for specifically the low seam Reserves at mines 2 and 3. Geological faults with a significant offset have been encountered and they have production tempo impacts in the mining sections. The challenges are addressed through a suite of exploration activities. Challenges are proactively accommodated in mine planning. Continuous surface exploration drilling aims to improve sill characterisation in Mine 2 while underground horizontal drilling is used to pinpoint dykes in operating sections at mines 2 and 3.
Limited pit room due to project execution delays Approximately 83% of the current Reserves are within the expansion projects. Delays in funding or execution may delay access to Reserves.  Continuous investigations on accessing new mining areas that were previously excluded from the LoM either due to quality, structural complexity or geological confidence.

Operational excellence

Due to the structural complexity at Matla, surface to seam directional drilling was implemented as an investigative tool to detect structures that affect mining operations. The success of detecting structures, using this tool, has assisted in redefining LoM in the affected areas. It has also enabled targeted vertical exploration drilling thus restricting drilling to areas of interest.

Mining ground availability has become a key focus area at Matla due to delays in three major LoM projects. Over the past three to four years, additional Reserves have been unlocked at Mine 3 Seam 4, Mine 2 Seam 2 and Mine 3 Seam 2 mining areas to ensure continued production while project implementation is ongoing. These additional Reserves have included the delineation of low seam coal at Mine 3, as well as shortwall mining at Mine 2 with the aim of increasing production tonnes from the mine, in conditions never attempted anywhere in the world. 

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