THEORY OF CONSTRAINTS

The Theory of Constraints (TOC) applies to the mining cycle and its activities for stoping and development. Research was directed towards a study using TOC to identify typical mining cycle constraints within current mining operations while developing a model (or manual) that can be used by mining companies to utilise the theory of constraints, in a consistent and meaningful way to optimise current mining operations.

The TOC improvement methodology implementation manual was validated in respect of a successful TOC ore flow implementation at the Lonmin, Rowland Shaft – a narrow reef platinum mine. The research team identified the process constraint(s) and determined the most effective method to exploit the process constraint(s). The next step involved mitigating the constraint and re-evaluating the process. Once this was completed, start-up training was made available to the Mandela Mining Precinct team and steering committee representatives. At the end of the process, the Rowland shaft project was validated, and the team produced a high-level case study.

The implementation criteria, such as the exploitation and subordination rules for each constraint in an ore flow line from different areas (e.g. half levels or levels or raise line blocks) can differ slightly to extensively due to geological, mining, logistical and beneficiation differences. Thus, sub-ordination criteria, buffers, measurements and tracking rules will differ from mine to mine and can even differ from one raise line block to the next; or from one half level to the next in the same mine. Sustaining the buffer and constraint measurements and management rules on a continuous basis are crucial for a sustained TOC improvement initiative.

For all practical reasons, a TOC improvement exercise is one of the very few methodologies that will guarantee a successful, sustainable and significant improvement. This is if the TOC programme implementation rules are applied and maintained correctly and strictly.

This research was commissioned to the CSIR and Exxpleo. The researchers involved in this project are Sibusiso Ngobese and PG Laurens.

The Theory of Constraints project has been completed. Final reports have been submitted and training manuals were compiled to prepare users to adapt the TOC system.