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Zululand Anthacite Colliery |
History
Most exploration activity in the vicinity of ZAC took place in 1976 and the early 1980's by Southern Sphere and Trans Natal Coal Corporation (later renamed Ingwe Collieries Limited) respectively. ZAC was opened in 1985, and has been a continuously profitable operation supplying domestic and international markets. In 2005, the operation was purchased as a going concern by Riversdale Mining Ltd and its Black Economic Empowerment partner (BEE), the Maweni Mining Consortium which comprises an Employee Trust and a number of community groupings.
Based upon JORC-compliant calculation of reserves and resources, ZAC has up to a 16 year mine life at current mining rates, with the possibility of further extensions based upon exploration success.
Geological Setting
ZAC is located within the Zululand coalfield of northern Kwa-Zulu Natal. The Zululand coalfield can be described as structurally complex, due in part to coal deposition within a graben structure where active rifting and down-warping took place. The active rifting and subsidence resulted in thick sedimentation and high geothermal gradients, which, in turn, produced an anthracite deposit where regional heat and pressure played a major role in the anthracitation process.
This contrasts with many other anthracite deposits located in Kwa-Zulu Natal where the anthracitation process is directly related to proximity to post depositional dolerite sills. Coal quality and yield distributions at ZAC are in general more uniform as opposed to anthracite developed in other Kwa-Zulu Natal coalfields due to the anthracitation process being influenced by regional heat and stress conditions and not dependant on proximity to dolerite sills.
This structural feature has rendered ZAC anthracite as the only true anthracite in South Africa (as distinct from semi anthracites) with a low volatile content of typically 5% on an air dry basis, with high vitrinite content which allows this coal to be used in high value niche markets.
The unstable tectonic conditions in the vicinity of ZAC produced a number of recognisable coarsening up sequences that have been separated into distinct zones by mine geologists from observation of the borehole record. Numerous small coal seams are developed within these coarsening upward cycles, but only the Main Seam attains a thickness of more than 0.8 m.
The ZAC Main Seam coal deposit has been broken up into the Kwa-Sheleza, Ngwabe, Mgeni and Maye mining blocks by north-south trending faults with displacements in excess of 100m. The Kwa-Sheleza mining block is, in turn, divided into the Sheleza North, Sheleza Deep and Sheleza Shallow blocks by a northwest-southeast trending graben with displacements of approximately 140 m on the bounding faults. Many of the fault displacements have dolerite dykes that have exploited the weakened country rock fabric. Within the fault bounded resources areas, the Main Seam can be found at both subcrop and to more than 200m depth with increasing surface elevations from south to north.
Operations
ZAC's underground mining operations use the bord-and pillar method, to be followed by stooping on retreat. A fleet of mining equipment that allows flexibility for operating in different seam thicknesses is utilized, with a combination of road-headers and continuous miners supported by scoops and shuttle cars as appropriate.
ROM (Run of Mine) Coal is transported by road truck to the coal treatment facilities which are capable of treating up to 90,000mt per month - the significant unutilised capacity allows ZAC great scope for economic expansions of throughput. Coal is trucked to a tipping site, and fed into a MacNally crusher to segregate stone from the raw coal, before being fed into a circuit of cyclone and drum washing facilities. A spiral plant assists the recovery of fine coal into the middlings stream as a saleable product.
Information in this report that relates to geology, drilling, mineralisation and Mineral Resources and Ore Reserves estimates is based on information compiled by J Liebenberg, who is a member of South African Council for Natural Scientific Professions. Mr Liebenberg has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking as a Competent Person under the meaning of the JORC Code. Mr Liebenberg, an employee of Zululand Anthracite Colliery (Pty) Limited has given his consent to the Public Reporting of these statements concerning geology, drilling and mineralisation in this format.
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