B2Gold gold mine located in Mali is powered by a Power plant with 8 16CM32 medium-speed diesel engines having a capacity of 7.1 MW each, operated on 380 cSt residual fuel. The plant was commissioned in August 2017 and experienced elevated engine vibration since the beginning.

The engine’s RPM is 720, corresponding to 12 Hz in the frequency domain. A significant 6 Hz component related to half of the engine speed was evident during all the vibration analyses conducted in the recent past.

Each engine is mounted on 10 spring-box dampers to absorb and dampen its vibration during operation so that minimum vibration will be transferred to the basement. The bottom plates of the spring-box damper arrangements are secured to the ground while the engine is supported on the top plate.

This study aimed to investigate the performance of the spring-box damper arrangements using an Emerson AMS 2140 vibration analyzer (guideline on spring-box damper vibration measurement was not available with the original equipment manufacturer). Out of eight engines, six operating at full load were selected for the study. Ten vibration points in the bottom (spring boxes) and ten from the top plate were selected for measuring vibration.

Vibration levels in the top plate of the spring-box damper did not vary significantly among the engines. However, a peak value of 9.45 mm/s was observed in B-bank location #2 of engine #03. In contrast, the vibration level of the bottom plates showed considerable variation among engines (1.302 to 4.307 mm/s). The average vibration level was calculated for each engine, with the highest observed in engine #05 (1.443 mm/s). It was an unexpected finding where it was expected to be in engine #03 assuming equal vibration transmission. Only the bottom plate of engine #02 showed the anticipated stability level, while all others showed higher vibration levels, which need further investigation.