Crushing Smarter

Crushing has greatly evolved over the last century. Cone crushers in particular have become a stalwart in mining and aggregates processing plants. Despite the popularity of these processing titans in modern industry, there remains shortfalls in the selection, application, and operation of crushers at many sites.

Even with well-designed plants with effective crushing circuits and solid maintenance plans, there can be significant room for improvements in areas ranging from the initial selection of crushers or design of equipment and circuit to long-term operational philosophy.

From experience in the field, the following eight issues can be highlighted. These considerations are not exhaustive but are based on Metso’s experiences with the installation, operation, and service of thousands of crushers around the world.

1) Back to basics: not following operational & maintenance best practices

This point is fundamental, so it is a good place to start before moving on to more specific issues. The number of ways that this commonly seen error can lead to poor performance and potentially costly repairs or downtime is beyond the scope of this article.

However, operating outside of design limits and failing to keep components and oil systems in proper working order continues to be a reality at some plants. Sometimes this occurs due to lack of experience or training, other times it could even be a bottleneck from plant design or management targets. For the sake of the crushing circuit, it is important to not fall into the trap of ‘pushing production a little longer’ without taking upkeep and maintenance basics into account.

2) Design criteria not matching long-term operation

Naturally, not everything is known in the design stage of a crushing circuit. Feed characteristics such as ore hardness and process definitions, like feed top size or particle size, most often are not fully understood until the plant is in operation. In these cases, a design choice is made and frequently it is the ‘play-it-safe’ option.

This method can result in an oversized crusher with initial higher total capital cost and future reduced efficiency from operation at non-ideal load levels. There have been extreme cases where the crusher’s full capacity has been over 50% greater than the production that the operating plant was able to support. Now, it can be argued that having this extra headroom in production capacity is desirable to allow for possible future operation above nameplate capacity. While this can be prudent, it should be addressed already in the design phase to maximise capital efficiency and mitigate issues with underloaded equipment upfront.

3) Insufficient crusher monitoring

Crushers operate in isolation and have many mechanical and operating conditions that should be continually communicated and evaluated. The type of sensors, location, and reporting intervals should all be carefully selected. Oil temperature, pressure, and flow rate can be monitored with simple transmitters (or even a switch) but even these require care be taken to avoid issues from improper scaling or calibration.

When in operation, the cavity filling level inside the crusher is an important factor for both production performance and operating costs. However, it should be noted that dust in the air and the difficulty in positioning a sensor to focus a beam down into the cavity can impact this measurement.

Whether a level sensor was not included with the equipment or if it is disengaged, not having an adequate reading on cavity level will almost always restrict optimal performance. A basic ultrasonic sensor has been effective in many installations, but might have issues with airborne dust or getting a focused beam. Radar or laser/lidar sensors are often recommended and have proven to be a more successful option that should be considered.

Another measurement specific to pedestal-shaft cone crushers is adjustment ring lift (also known as ring bounce), which is indicative of an over-force event that exceeds the crusher’s design rating (or less often, a loss of hold down force in the tramp relief system). Tens of thousands of cone crushers, both old and newer models, have no direct measurement of this critical condition. Instead, plant personnel are relied on to manually ‘hear’ any ring bounce. The issue with this strategy is that cone crushing is loud by nature, and it is easy to mistakenly ‘hear’ ring bounce. Others may inadvertently dismiss actual ring bounce as ‘just how the crusher sounds’.

Accelerometers have been used for decades to monitor this critical condition. However, they require careful calibration and essentially are reading total movement of the adjustment ring, not its lift relative to the mainframe. More modern solutions use vibration frequency spectrum, magnetic positioning, and laser sensors, which have been proven effective at capturing ring lift events, with continued testing expected to reinforce confidence of these as long-term solutions.

Enjoyed what you've read so far? Read the full article and the rest of the Autumn issue of Dry Bulk by registering today for free!

Read the article online at: https://www.drybulkmagazine.com/special-reports/03102025/crushing-smarter/