Optimising Grinding Performance with Advanced Mill Linings

Rubber & composite lining solutions for all scrubber and mill applications across Australia

At a Glance: Maximising Solutions

In Western Australia’s high-cost mining environment, your mill liner is a strategic asset, not a consumable commodity of parts.

This guide explores how selecting the right metallurgy inserts for shell plates or lifter bars along with the polymer/rubber profiles specifically for Pilbara and Goldfields ore bodies, can slash shutdown downtime, reduce energy draw, and deliver the lowest total cost per tonne. Whether you're running SAG mills with high impact zones (as seen in the photo using Thejo products), high-slurry abrasion Grate Discharge or Overflow Ball & Lime mills, learning how data-driven wear monitoring and engineered solutions offered by Thejo Australia can drive efficiencies on site.

Driving Throughput: Why Liner Selection is a Strategic Priority

In Western Australia’s fast moving mining sector, grinding performance is far more than a technical variable - it is a critical strategic lever that changes constantly rather than a “set and forget”. For the Processing/Maintenance teams overseeing the plant performance, selecting the right mill lining solutions is the heart of the process than can affect higher throughput, improved recovery, and lower total cost of ownership (TCO).

In a landscape defined by volatile commodity prices and rising operational costs, the difference between a "standard" mill lining supplier and a market leader often lies in Thejo mill designs for comminution efficiency through the consultancy period.

The Reality of the Australian Mill Lining Market

Thejo is a boutique customised designer and manufacturer for rubber and composite liners, we have the capability to redesign or convert certain steel mill linings to composites through our design team. We find specialising in the rubber/composites mills is over 80% of all mills in Australia.

Whether you are digging through abrasive hard rock in the Goldfields or high-grade iron ore in the Pilbara, your mill liners face a brutal physical reality that either impactions, abrasion or impingement will wear the components differently. The geological diversity of Western Australia and beyond means that a "one-size-fits-all" approach to liner selection isn't just inefficient, it’s a fair dinkum financial liability.

1. SAG Mills: Semi-Autogenous Grinding (SAG) mills are the workhorses of the mining industry which can be either entirely steel lined or composite depending on the site processing conditions primary stage. Consideration to the grinding media volume/charge height can see a SAG mill with 12-20% grinding media being operated as a Ball Mill, this consideration is critical for different lining designs that can be used. Driven by high-impact kinetic energy and severe abrasion, these environments demand materials that can handle the relentless battering of large-diameter grinding media and coarse ore. Failure here doesn't just mean a liner change; it often means serious damage to the mill shell itself.

2. Grate Discharge Ball Mills: Can be operated on sites as a Primary/Secondary or Tertiary grinding dominated by constant sliding or impact abrasion whether upset crushing is using a HPGR (High Pressure Grinding Rollers) or gyro/cone jaw crushers. Here, the goal shifts from impact resistance to surface endurance and grinding media trajectory control through Thejo selection criteria. If the shell liner profile wears unevenly on the leading edge, the grinding media’s impaction zone may be over/under throwing ("toe" and "shoulder" positions shift), this can lead to inefficient power draw and reduced mineral liberation.

In WA's high-cost environment maximising throughput, Thejo strategic selection must be developed application-specific, by aligning the liner’s metallurgy (inserts) or polymer (rubber) profile with the specific characteristics of your ore body.

3. Overflow Ball Mills, Scrubbers Lime/Slaker Mills: In today’s environment of longer service life required for the Northwest Iron ore industry, Thejo are customising each site requirements using inserts in high wear areas inside these types of mills which are extending the service life, reducing down time and removing multiple relines which is part of the TOC(Total Ownership Cost) model. The photo on the right indicates the feed head outer lifter bar and partially the shell linings in this 5m diameter by 12m long was able to balance the entire wear rates from having 2 partial mill linings into one complete lining replacement.

Thejo’s design pricinples are always applied to overflow mills with similar wear characteristics, why throw away or dispose of components that are only 50% worn. Finally the lime mills are using Thejo premium grade rubber for maximum service life usually expecting a minimum of 10 years full time operation between changes

Quick-Reference: Strategic Liner Selection

Moving Beyond "Price per Set" to "Cost per Tonne"

For procurement teams and financial controllers, the initial capital outlay of a liner set is only the tip of the iceberg. To truly optimise a maintenance budget, you must look at the Whole-Life Cost. In addition to this, Thejo by customising the lining design can also help reduces costs with third party reline teams, grinding media, power usage for diesel operated power plants running the mills.

In real time, Thejo Western Australian context, three pillars define this calculation which are:

1. Slashing Shutdown Downtime: In the WA mining industry, every hour of a scheduled or unscheduled shutdown represents a massive hit to potential revenue. Traditional steel liners are heavy, awkward, and potentially dangerous to handle requiring third party trained personnel and suitable liner handling equipment that needs annual service and certification.

By contrast, Thor-M® Composite and Thor-R® Rubber linings are significantly lighter than their full metallic counterparts. This weight reduction does more than just improve safety; it removes the logistical bottleneck of heavy handling equipment. This allows for faster, safer changeovers, reducing the "re-line" window and getting the mill back into production hours or even days sooner.

2. Engineering for Asset Longevity: Mill Lining components should never be viewed as just a sacrificial shield; it is a precision-engineered component of the machine's efficiency. Consideration of purposely designed and built componentry crafted by amassing process conditions on site, understand lining wear patterns and suitably developing a product fit for task or better.

• Head Linings: Specifically designed for balanced wear patterns to prevent "high wearing zones either on the outer edge of the mill or trunnion zone” that lead to unscheduled stops.
• Shell Linings: Engineered to control media trajectory, allowing longer fine grind periods throughout the mill. This ensures the kinetic energy is directed into the ore for breakage, rather than into the liner, which causes premature wear and energy waste.
• Discharge Systems: Using advanced pulp lifter segments and grates designed to prevent "slurry pooling" inside the mill, reduced backflow, controlling scat ejection rates whilst maximising the grinding media consumption based on balls consumed vs process tonnes (kg/t processed) which are the silent killers of mill throughput and wear rates.

3. The Rubber Proprietary Compounds: Not all rubber is created equally with many compounds of polymers using excessive fillers to bulk the rubber up such as chalk, sand and other inert fillers which may even be by-products of other processes. Thejo having established itself in 1974 originally were using a distribution model globally through distribution to OEM/Maintenance teams in the mining industry under their product name. Thejo Australia in 2012 was formed to go direct to the mine sites to allow for better customer service experience and reducing additional costs for the end users. The T800 series compounds used in Thor-R® Rubber linings are formulated with high natural rubber/carbon black content, specifically engineered for the high-temperature and chemically diverse environments of WA processing plants.

In many secondary and tertiary mill applications, these advanced polymers can outlast traditional composite liners once the balance has been achieved using the Thejo approach. Thor-R® rubber is particularly effective in wet grinding circuits; its superior designed sealing properties prevent slurry leakage, protecting the mill shell from corrosion due to fitment and wears consistently from new through to “End of Life” as determined by the service technician.

For the Australian “Goldfields/ Kalgoorlie” operations, this material also resists 'mineral lock-up/hang up’ due to its high-density polymers, ensuring that fine particles of precious metal aren't trapped in the liner surface, which directly improves your final recovery rates. This provides a dual benefit with respect to the tear propagation resistance of the surface with a lower initial acquisition cost and a significantly extended service life, effectively decoupling your production targets from your maintenance schedule.

Data-Driven Decisions: The Role of Wear Monitoring

On remote Australian sites, waiting on a 3D scanned mill for 6 weeks to be processed or "guessing" is not a reliability strategy. You cannot manage what you do not measure therefore the current service on offer is not performing. Operational excellence depends on rigorous wear monitoring and transparent reporting whilst on site.

By plotting wear data graphically over time, Thejo provides a predictive roadmap for maintenance. Our engineers from the Kalgoorlie and Port Hedland hubs provide the on-site measurement services required to move from 'preventative' to 'predictive' schedules. This data-driven approach allows site leaders to:

• Plan Inventory Effectively: Eliminate the need for expensive "emergency" air freight or expedited shipping by knowing exactly when a set will reach its wear limit.
• Protect the Asset: Avoid "shell thinning" and catastrophic structural failure by replacing liners at the optimal point of their lifecycle.
• Iterative Design: Use real-world wear patterns to tweak liner profiles, gradually evolving the design to perfectly suit the specific nuances of your site's throughput and ore hardness.

The Bottom Line: Safety, Energy, and Efficiency

From our headquarters in Bibra Lake to our dedicated service hubs in Port Hedland and Kalgoorlie, we understand that WA sites need more than just parts, they need strategic partners.

Modern mining is under increasing pressure to meet ESG (Environmental, Social, and Governance) targets. Choosing a lining system that reduces "dead load" (the weight of the liners themselves) can directly reduces the torque and power requirements of the mill through controlling ore hangup or blockage in the shell & discharge grates. This leads to:

• Direct Energy Savings: Lower kilowatt-hours per tonne of processed ore.
• Mechanical Reliability: Reduced strain on motors, gearboxes, and drive components, extending the life of the entire grinding circuit.
• Personnel Safety: Lighter components and fewer "hot work" requirements during shutdowns significantly lower the Total Recordable Injury Frequency Rate (TRIFR).

In a high-cost, high-performance environment, your mill lining is not a commodity - it is a strategic asset. By focusing on engineering, material science, and predictive data, WA decision-makers can turn their grinding circuits into a competitive advantage.

Ready to Benchmark Your Performance?

Is your current lining solution delivering the lowest cost per tonne, or is it merely the cheapest price per set?

Contact Thejo Australia today to arrange a comprehensive audit of your mill’s performance. Our team of engineers can provide a site-specific solution designed to maximise your throughput and minimise your downtime. Thejo is a certified company to ISO 9001, 14001 & 45001.