SUNConferences, Computers and Industrial Engineering 42

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Sweating the constraint of strip mining: A case study of Project Khulisa
Andile Dumisani Ndiweni

Last modified: 2012-06-07


 The mining industry faces a tirade of issues least of which is the increasing difficulty in extracting ore from the earth. Geological conditions in the coal mining industry are getting harder whilst customers are continuously demanding better quality at a lower cost. To survive in this ever demanding environment, we need to continuously optimise our systems with regards to resources, equipment utilisation and improving our labour productivity.  Isibonelo Colliery an operation of Anglo American Thermal Coal is not immune to these changes and demands, with a higher demand of coal in the Domestic Market Isibonelo Colliery is faced with an ever ending need for asset optimisation innovations to ensure continuous improvement in tonnage throughput, cost, productivity and NPV. 

Isibonelo Colliery supplies 5.1Mt per annum of domestic market coal to SASOL. Due to the nature of its geology, the volume of material to be moved prior to reaching coal has almost doubled in the past five years. In 2011 a pre-strip fleet was commissioned however the desired results were not being obtained.
In 2011 AATC embarked on operational diagnostic exercise to benchmark its operations assets productivity against world class standards. The objective was to identify initiatives which will enable the mine to grow to its full potential and project KHULISA was born. (KHULISA – a Nguni word simply translated as “to grow something to its full potential”).

The approach taken by Isibonelo Colliery was to use the AATC AO process inline with the TOC constraint model to ensure all parts of the business value chain are reviewed and that the key constraint is identified and  fully exploited to deliver value:

Key issues identified within open cast mining pre-strip operations:
• Operator training and availability (Bums on seats)
• Planning
• High lead time for spares
• Trucking capacity
• Carry back (material sticking to truck bowls.)

The key actions taken to deliver on the benefit were:
• Identify and understand your constraint
• Training of operators and tracking of operator licences,
• Proactive relationship management with the OEM,
• Purchase of additional trucks (optimum point and type of trucks and hauling fleet optimisation) and
• Re-design of the bowl to reduce carry back.
The results have seen improvements in both uptime and rate leading to improvement in excess of 50% year on year. This project shows the results that can be obtained when business improvement is focused on the key constraint on the operation.
Keywords: Opencast Mining, Business Improvement and Coal mining and TOC