Exxaro Resources Limited
Consolidated Mineral Resources and Mineral Reserves report 2022


Matla is a captive underground coal mine that extracts thermal coal. All coal is crushed, screened and sized before being delivered to the Eskom-owned Matla power station via a network of conveyor belts. Matla has three major LoM projects which will provide mining access to ~83% of the remaining Coal Reserves when completed. The projects are at different levels of implementation, with delays due to funding and project execution. The projects include a boxcut and associated declines to access mineable areas at Mine 1 from the surface and an incline and decline project to create underground interseam access at Mine 2 and Mine 3.

We conduct continuous optimisation and innovation initiatives to unlock value by accessing additional mining ground.

Matla overview

Table 32: Matla overview

Topic Information
Location 15km west of the town of Kriel in Mpumalanga, South Africa.
History Previous ownership Material notes
1976 to 1990 Trans Natal Mines Construction began in 1976 with full production in 1983.
1990 to 2006 Eyesizwe Mining rights ceded to Exxaro in 2006.
2006 to present Exxaro Full production until Mine 1 closure in 2016. Mine 2 and Mine 3 continue to produce ~6Mtpa with ongoing exploration drilling to support operations.
Adjacent properties Seriti's Kriel Colliery neighbours Matla to the east and Zibulo (Seriti) and Khutala (Thungela) are situated to the north.
Infrastructure Matla is situated on the P53-1 and R547 secondary roads branching off the R580 and R545. Existing infrastructure supporting 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). All coalis conveyed from the mine directly to Eskom's Matla power station.
Coalfield Matla mine is situated in the Highveld coalfield, to the south of the Witbank coalfield. The coal seams are developed in the Vryheid Formation of the Karoo supergroup. The stratigraphic 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 a subsequent increase in the 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 in localised areas. The S5 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 is located 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 Mine 2 and 3 Resource areas. It thins out to the south, where the thickness averages between 1.2m and 2.5m. Much of the coal in this area is mined as a low seam. The S2 between Mine 1 and Mine 2 has been burnt by a prominent dolerite sill and is thus unmineable. S2 in the Mine 1 area is generally poor quality and discontinuous due to sill activity thus it is not mined in this 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 hasburned and devolatilised S2 on the southern part of the mining area in Mine 1. Floor rolls have been encountered in S2 workings and created challenges in isolated mining areas. 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 encounteredare generally less than 0.5m in width but can reach up to 1.5m in thickness.
Resources and Reserves Coal Resources and Coal Reserves occur within the domains of Mines 1, 2 and 3. The Coal Reserves are aligned with the existing LoMP. The reporting of LoM is restricted to the Mineral Right lapse date although there are Coal Reserves well beyond this date.
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. Production at Mine 1 was stopped in 2015 due to pillar instability and is planned to resume in 2025. Mine 2 and Mine 3 use bord-and-pillar methods to mine S2 and S4. Shortwall mining is also utilised to conduct mining of S2 in Mine 2.
Beneficiation None of the coal mined at Matla is beneficiated but it is crushed and screened (sized) before being conveyed to the power station.
Product Matla mine produces thermal coal exclusively for Eskom.
Market Captive market: Eskom.
Mining right Matla has an approved mining right that covers some 23 494ha.
Environmental approvals With the exception of the expired WUL, which is being renewed, discussions with the DWS are ongoing.

Figure 12: Matla mine

Figure 13: Matla cross-section Exxaro

Resource estimation

Table 33: Resource estimation methodology and reporting

Process Information
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 duplicate 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 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 are allocated unique alphanumeric IDs corresponding to the associated drill hole ID, seam sampled and number of the individual sample. These samples are collected and bagged and 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. All sample results are validated following a standard procedure including visual, logical and mathematical verification before acceptance and capture into the mine's database.
Laboratory QAQC Matla conducted QAQC on Siza laboratory processes and equipment in 2022. 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 acQuire
Number of drill holes in mining right 2 618
Number of drill holes used for Resource estimation S2 – 1 845S4 – 2 403
Number of drill holes used for classification S2 – 1 845S4 – 2 403
Data compositing and weighting Data compositing is conducted per seam using a weighted value from individual samples that make up the seam, along with the relative density and length of each individual sample. This is conducted in GEOVIA Minex™.
Data validation Conducted using queries in acQuire, Minex™ and Excel.
Geological modelling software GEOVIA Minex™
Estimation technique Growth algorithm
Previous model date 2020
Last model update 2022
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 seam structure

Raw quality grids
Changes to modelling process None
Thickness cut-off and extraction height considerations ≤1.8m
Quality cut-offs (adb) DAFV ≤ 26%CV ≤15MJ/kg, Ash ≥50%
Geological loss applied 10% (may vary considering RODA)

Table 34: Resource classification criteria

Category Type of drill holes Drill hole spacing Structurally complex areas Drill holes/ha
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. 0.13
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. 0.04
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. 0.02

Table 35: RPEEE considerations

Item Criteria Criteria met Comment
Geological data Data has been validated and signed off by Competent Person Yes Seam depth ≤40m, seam thickness ≤1.8m, dry ash-free volatiles ≤26%, CV≤15MJ/kg and ash ≥50% with coal qualities reported on an adb.
Geological model Geological model has been considered and signed off Yes 2022
Structural model Structural model was considered and signed Yes 2022
Mining Mining assumptions considered and defined Yes Underground
Assurance Exxaro internal audits and external audit 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 (2022).
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. An application for stooping was submitted and there is a reasonable expectation that the approval will not be withheld. Surface 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 renewed 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 June 2023. Extension period and terms under negotiation. All considerations remain. Exxaro has reasonable expectation that the CSA will be renewed.

Reserve estimation

Table 36: Reserve estimation

Topic Information
Software UGCS
Reserving process Scheduling of the Coal Reserve is determined using mine scheduling applications from UGCS. 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 5.6Mt of Inferred Resources are included in the LoMP, representing 3.4% of the LoMP, and are not considered material.
Modifying factors
Average thickness cut-off ≤1.8m, low seam ≤2.1m, high seam ≤3.6 and ≥4.8m
Quality cut-offs DAFV ≤26% and CV ≤18.5MJ/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 Main development >2.1, secondary panels >1.8 and tertiary panels >1.6
Bord width 7m
Barrier pillar Main development 19m, secondary and tertiary panels 17m
Pillar centres Main development 24m, secondary panels 20m and tertiary panels 19m
Boundary pillar Main development 24m, secondary and tertiary panels 17m
Mining height Low seam ≤2.1m, high seam =3.6 and ≥4.8m
Extraction factor Low seam 58%, S2 48% and S4 50%
Dilution Already included in model
Contamination Moved from % to cm (new UGCS software). Low seam 2.1m plus 10cm roof cut. Other seams 10cm roof cut.
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 Reserves are downgraded from Proved to Probable where surface ownership is pending for stooping.
Social Applicable communities considered.
Geohydrological Applicable surface and groundwater models considered.

Table 37: Matla Coal Resources and Coal Reserves statement

Category  2022 (Mt) 2021 (Mt) Difference in tonnes (Mt) Difference (%) Reason for change 
Measured  657  639  18  Mining (9Mt) was offset by new information (27Mt). 
Indicated  91  114  (23) (21) Decrease (23Mt) is the result of new information. 
Inferred  87  93  (6) (6) Decrease is due to new information indicating thinning seams against basement outcrop areas as well as burnt coal zones (2Mt). Additional drilling upgraded 4Mt to the Measured category. 
Total Coal Resources  835  847  (11) (1)  
Proved  130  124  Mining (6Mt) and the removal of stooping areas (4Mt) was offset by new information (16Mt). 
Probable  38  38   
Total Coal Reserves  167  162 
Rounding of figures may cause computational discrepancies.
Tonnages quoted in metric tonnes and million tonnes (Mt). Coal Resources quoted as MTIS.

Exploration summary

Table 38 outlines the exploration for the reporting year. For detailed expenditure, please refer to Table 64.

Table 38: Matla exploration summary

Objectives Progress in reporting year Plans for next reporting year
Increase geological confidence in S2L Mine 3 medium-term mine plan Drilling within the five-year mine plan at Mine 3 S2 low seam has better defined areas of thicker coal development. These areas have been confirmed and subsequently targeted for fast tracking during 2023 to improve seam heights and resultant mining conditions at the low seam. Drilling at the low seam will continue in 2023 to better define key access areas within the mine plan.
Identify additional mineable ground on the eastern extent of Mine 2 Additional drilling was conducted to identify additional ground required to supplement current production requirements as a result of LoM project delays.
Increased confidence in floor undulation positions at the Mine 2 shortwall Extensive drilling and surface seismic surveys were conducted to understand small-scale variability and undulations ahead of shortwall mining. This information has been used for risk domaining and detailed for the shortwall.


Table 39: Matla risks

Risk Description Mitigation
Limited pit room due to project execution delays Approximately 78% of the current Reserves are within the delayed expansion projects. The delayed LoM expansion projects have resulted in limited pit room availability with the risk of having to mine in structurally complex and/or low-quality coal areas. Continuous investigations on accessing new mining areas that were previously excluded from the LoM either due to quality, structural complexity or geological confidence. Layouts optimised to achieve RoM blend of required product quality.
Geological structures High risk geological structures impact mining due to ground stability and the need to develop through these structures to access mineable reserves. Structures include dolerite sills and dykes, faults and jointed ground within known shear zones. Structure delineation is conducted through surface directional and underground horizontal drilling, targeting structures defined using geophysical interpretation. The resultant structural data informs the mine plan layout, orientation, roof and sidewall support during excavation.
Eskom purchasing of surface farms to commence with stooping Stooping is a total extraction mining method that will have an impact on the surface farmland. Require ownership of farms where stooping is planned. Eskom to purchase surface ownership of a list of farms as per CSA. Stooping ground below private land is reported as Probable Reserves.
Environmental authorisation for stooping The environmental management plan for total extraction during stooping can commence when land ownership has been secured. Eskom to purchase surface ownership of a list of farms as per CSA.

Operational excellence

A focus on creating additional ground availability and production improvement following life of mine project delays has resulted in multiple initiatives to unlock additional value at Matla.

These initiatives include additional drilling, geophysical surveys, short-term modelling and consolidated technical studies for the evaluation of new mining areas. These initiatives include:

  • Successful mining of previously challenging areas at Mine 3 S4 using additional drilling information and geological and rock engineering studies. This resulted in successful mining of the previously inaccessible S4 since 2020.
  • Exploration targets focused on thicker coal seam development at the Mine 3 S2 low seam have identified areas that can be accessed in the near term to reduce contamination and improve the overall product quality from the mine.
  • A ground seismic survey at the Mine 2 shortwall area has been conducted to create a high-resolution data set of the small-scale variability and seam floor behaviour ahead of shortwall mining. This information is critical to understand prevailing conditions and assist in the detailed planning at the shortwall.
  • Successful mining of the eastern Reserves following additional drilling to delineate mineable coal in the previously excluded area. This Reserve has been exploited since 2021, and continues to add additional value to the mine.
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