Harmony Gold Unisel mine
Feature image credit: Harmony Gold

Harmony Gold Mining Company has introduced cutting edge maintenance procedures to reduce its operational costs.

With the advent of the fourth industrial revolution, innovative processes and procedures have been developed that enable mines to modernise and increase efficiency in exiting new ways.

Some of these procedures, developed by ETA Operations and implemented as a joint venture between Harmony Gold and ETA, include the implementation of condition monitoring across its mines and centralising the condition monitoring data from these mines for easier access and simplified reporting.

The condition monitoring system was first implemented on the four mine support systems (MSSs) of a single Harmony mine as a pilot study. The process was then optimised from experience gained on the pilot study gold mine and deployed on the MSS machines of four additional gold mines within the Harmony mining group.

The implemented condition monitoring system had three main benefits. First, the equipment that runs on the mines is often dependent on maintenance schedules provided by the Original Equipment Manufacturer (OEM). However, no two pieces of equipment are identical and thus the maintenance schedules sometimes differ from those suggested by the OEM and this difference only increases with age.

The implemented condition monitoring system however allows the maintenance intervals to be based on historic data thus allowing the mine to better carry out predictive maintenance.

Second, the condition monitoring system generally uses information from sensors already installed on the pieces of equipment (vibration, temperature, etc.) as standard. This means that the implemented system avoids the need for the large capital expenditure that would have been incurred if specialised condition monitoring equipment was used.

Third, many of the pieces of equipment installed on the mines use proprietary software and data types to record their maintenance parameters.

The implemented condition monitoring system however reads these different data types and combines them in order to create a combined dataset comprised of specified parameter values for each piece of equipment.

This common dataset allows the mine to gain an overview of all the equipment present on the mine without having to go through multiple different sets of proprietary software.

Using this innovative cutting-edge technology, the Harmony mining group has significantly improved its maintenance procedures and gained significant benefits to its maintenance budget.

However, this technology is not only applicable in maintenance monitoring, it can also be applied to any field in which equipment must be monitored. As such there are plans to expand the technology rollout to other fields in order to gain even greater operational efficiency and savings.

Understanding maintenance

Condition monitoring is the process of monitoring a parameter in machinery (vibration, temperature, etc.), in order to identify a significant change which indicates the development of a fault.

The most expensive maintenance strategy is a run-to-failure or corrective maintenance strategy and it should therefore be avoided as far as possible. Preventative maintenance on the other hand can either be time based or condition based and is done at specific intervals or when certain condition-based criteria are met.

Maintenance resources on South African gold mines are also limited, which would make condition based maintenance more suitable desirable since it is less resource intensive. Condition monitoring can therefore be considered as a supportive component of preventative maintenance.

South African gold mines rely on mine support systems (MSSs) to keep underground working environments safe and enable sustainable mining operations. Since these systems are of such importance and mainly powered by machines, the failures of these machines must either be avoided, or attended to immediately when they occur.

Condition based maintenance ideally requires a condition monitoring system to support it and improve its efficiency. Condition monitoring equipment are however very expensive to maintain and requires specialist knowledge to operate.

The MSS machines, that need to be monitored, on the other hand are exposed to very harsh operating environments. This often makes the use of specialised condition monitoring equipment to continuously monitor machine conditions in gold mines impractical.