Ball mill failure: how mining company mitigated costs

Identifying a fault in a ball mill allowed an Australian mining company to save millions of dollars. Check it out!

At the end of 2023, the monitoring team of a large Australian mining company identified a significant increase in vibration on the input shaft of the ball mill gearbox in one of their plants. This is an extremely important asset and could impact all production if it were to become inoperable.

The mining company uses the Dynamox Technology to monitor their assets. These Predictive Maintenance tools consist of wireless triaxial vibration and temperature sensors, as well as an online platform with up-to-date graphs of the data collected.

Ball mill fault identification

Initially, the platform sent out an A1 (attention) alert, which prompted the Condition Monitoring Team to investigate the machine. The analyst noted that the spectral data on the DynaPredict platform pointed to a bearing failure on the inner race of the ball mill gearbox input shaft. The site maintenance director was informed of the progress of the fault and ordered spare parts.

It’s important to note that this happened during Christmas time and, in Australia, the possibility of obtaining parts and service labor during this period is particularly difficult.

During monitoring, an increase in vibration levels was noticed, to the point where the online platform issued an A2 (intervention) alert. Subsequently, the engineering team was informed of the progress of the problem and the gearbox OEM support team remained on the alert to take action.

Faced with this critical situation, maintenance was carried out on the gearbox, as there was no other spare part to replace it.

Mill maintenance

The ordered spare parts arrived on site and the OEM mobilized to help complete the repair with the support of the plant’s maintenance team.

During the repair, the input shaft was removed, the bearings replaced and the oil changed. At the same time, the team carried out a complete overhaul of the gearbox and shaft alignment to ensure that all specifications were within the manufacturer’s standards.​

In addition, the investigation revealed that a fault had appeared in the inner race bearing on the gearbox input shaft at the bearing end. The gearbox had large amounts of metal filings, indicating that a catastrophic failure was imminent. Wear was also noted on the intermediate shaft housing, suggesting that the bearing was rotating inside the housing.

Results – Ball mill failure

Thus, thanks to Dynamox’s real-time monitoring system, the team identified the breakdown in good time to plan and carry out a preventive repair. The maintenance was completed successfully, avoiding a catastrophic failure that could have resulted in significant downtime.

The plant was inoperative for 105 hours. That is, a much shorter period than would have been predicted if the failure had occurred without proper monitoring. As such, the cost of the repair was only $81,500 AUD.