When Standard Mn13 Is Not Enough: Liner Optimisation for Hard-Rock Primary Crushing

Primary crushing wear part selection and chamber geometry modification for a gold ore concentrator with hard, abrasive feed and an established secondary and tertiary crushing circuit.

The Operating Context

The concentrator processes gold ore from a hard-rock deposit in China. The primary crushing stage uses jaw crushers feeding into a well-developed secondary and tertiary circuit — cone crushers and classification equipment already in place and operating reliably. The challenge was not the overall process flow but a specific, persistent problem at the primary jaw crushing stage: liner wear life that was shorter than comparable operations, throughput limited by recurring material bridging at the discharge, and a crusher that was effectively the bottleneck in an otherwise capable circuit.

The ore hardness is in the upper range for the region — granite and quartz-dominant host rock with compressive strength typically 150–200 MPa, abrasive index reflecting the high quartz content. The existing jaw plates were a standard Mn13 grade, correctly specified for many primary crushing applications but not optimised for this combination of hardness and abrasivity.

What Was Changed and Why

Liner material upgrade to Mn18Cr2. For feed material in the 150–200 MPa UCS range with sustained high quartz content, Mn13 work-hardens adequately at initial contact surfaces but tends to soften in zones of intermittent contact — particularly at the upper chamber where feed material momentarily releases rather than sustaining the compressive load needed for full work-hardening. Mn18Cr2 has a higher work-hardening potential and maintains its hardness development more reliably across varying contact intensity. The material change alone is not dramatic — approximately 15% improvement in wear life on equivalent geometry — but it addressed a specific failure mode rather than being a generic upgrade.

Crushing chamber deepening and profile optimisation. The existing chamber geometry had a relatively short effective crushing zone, which contributed to material bridging at the discharge. Material that had not been fully reduced to the target CSS was stacking at the outlet rather than progressing through the chamber. Deepening the chamber — extending the effective crushing length — reduced the proportion of oversized material reaching the discharge and distributed the crushing work more evenly across the liner surface. The result was more uniform liner wear across the plate face, which extends service life beyond what the material upgrade alone achieves: a liner that wears evenly outlasts one that wears in localised zones, because the worn-out zone determines replacement timing regardless of how much useful wear surface remains elsewhere.

Discharge arrangement modification. A discharge-assisting device was added at the outlet to prevent the bridging that had caused recurring blockages. The modification is mechanical rather than material — it addresses the flow geometry at the discharge rather than the crushing geometry within the chamber.

Results in Service

Against the concentrator’s own baseline data from the previous jaw crusher installation: crushing efficiency improved by approximately 10% on equivalent feed rate; liner service life extended by eight months against the previous replacement interval; discharge blockage rate dropped to near zero compared with a previously recurring problem that required manual intervention several times per shift during peak feed periods.

The efficiency improvement is a combination of the chamber geometry change and the material upgrade — neither change alone would have produced the same result. The eight-month life extension reflects primarily the liner material change and the more even wear distribution from the improved chamber profile.

What This Case Illustrates

Primary jaw crusher liner selection for hard, high-quartz feed is not a default specification problem. Mn13 is correct for a large range of primary crushing applications; for feed in the 150–200 MPa range with sustained abrasive loading, it is not the optimal choice, and the performance gap is measurable in wear life and operating efficiency rather than just in metallurgical theory. The chamber geometry contribution to liner life is equally important and is often overlooked when wear life is below expectation — uniform wear distribution is as significant a determinant of service life as the material hardness itself.

For enquiries about jaw crusher liner specifications for specific ore types and operating conditions, contact our engineering team with feed material hardness data, current liner grade and replacement interval, and crusher model.