Balancing Issues Rectified for UK Mineral Mine

  • Company: LKAB Minerals
  • Industry: Mining
  • Services: Asset Investigation, Emerson Data Collector, Cloud-based Reporting
  • Location: United Kingdom
  • Cost-Saving: £4,800

The Overview

A site visit revealed imbalance on a main attritor rotor, with the main three tonne rotor confirmed as been out of balance. It was recommended that all wear plates be replaced equally across the plate circumference and that the five free-spinning hammers be inspected for signs of wear and free movement. This resolved the balancing issue, saving the client £4,800 in lost production costs.

The Situation

We were requested to attend a mineral mine based in the UK, to offer investigative assistance on a primary limestone attritor.

The Challenges

Excessive vibration had been reported causing multiple structural failures, repeated production downtime and concerns regarding achieving production targets.

The Solution

An initial site visit, utilising an Emerson data collector, revealed imbalance in the main attritor rotor. It was evident that the main three tonne rotor was out of balance. No sub synchronous activity was detected, ruling out a structural looseness. A further visit was required utilising alternative equipment to confirm shaft integrity and to assess resonance.

A verbal recommendation was given at the time to replace all wear plates equally across the plate circumference and inspect the five free-spinning hammers for signs of wear and free movement.

The Results

Our engineer confirmed that the balance issue had been resolved using Emerson’s multichannel CSI 2140 to check the shaft phase angle, confirming the shaft integrity.

A sample of data was obtained from initial start up to full speed over the duration of 10 minutes, to highlight any resonant frequencies. The machine passed as well as confirming the rotor balance issue had been resolved.

Three speeds were visible to cause additional vibration. Recommendations were provided alongside confirmation that the shaft had not been distorted.

Due to the issues previously experienced on an annual basis with the reliability of this asset due to a similar vibration issues, it is estimated the cost avoidance, through bringing the unit back to an acceptable standard of vibration and thus extending asset life, was £4,800.