Why The IsaMill™ Outperforms a Traditional Ball Mill

In the mining industry, making your mineral processing more efficient is not just a goal, it’s a necessity. With global demand for metals and rare minerals increasing and ore grades declining, operations must innovate new ways to maximise their collection whilst reducing energy consumption.

One of the most pressing questions among mineral processing organisations today is:

"What is the best mill for fine and ultra-fine grinding?"

At Glencore Technology, we understand this challenge first hand. That’s why we developed the IsaMill™, a piece of mining technology that offers game-changing advantages over traditional ball mills (including planetary ball mills). In this article, we’ll help clarify the differences, explain why the IsaMill™ leads in performance, and guide you toward making the best decision to optimise your wet grinding process and deliver consistent sample material to downstream circuits.

What is an IsaMill™?

The IsaMill™ is a horizontal, high-speed stirred media mill designed for product size in the 1–10 µm range; far beyond what a ball mill or other lab-scale grinding machine can achieve at scale. Unlike semi-autogenous grinding mills (SAG) and ball mills, how the IsaMill™ works is through grinding discs that enhance the grinding efficiency of raw materials whilst eliminating the contamination risks associated with steel grinding balls.

It operates with a series of rotating discs inside a horizontal chamber, agitating the grinding media and slurry in a plug-flow pattern.

The result? Consistent particle size, high energy efficiency, and a simple, compact design that works without the need for large mill discharge pumps.

Legacy SAG mills rely on steel balls and large ore fragments tumbling in a horizontal rotating cylinder to grind ore. While effective at coarse grinding, they often suffer from reduced grinding efficiency when processing softer ores, and high maintenance costs from mill liners and grinding balls.

Ball mills improve on size reduction but still require large amounts of energy and typically offer less grind control. They are also limited when it comes to reaching sub-10-micron particle sizes economically.

By contrast, IsaMill™ uses media arranged eccentrically on a shaft; every pass releases high dynamic energies that grind hard pebbles and other large particles down to very small sizes in a single pass. The IsaMill's high intensity grinding technology has nearly 1.5-2 times the kW/m3 of its closest competitor, the HIG mill. With a tip speed of 22 m/s it has at least two times the kinetic energy in impacts.

It changes the equation entirely with its more uniform grinding process, high power intensity, and proven scalability.

The IsaMill™ delivers unmatched efficiency and reliability in fine grinding. Here’s how:

• Horizontal Layout
  A compact design that fits easily into existing mineral processing plants, no tall steel structures required.

• Low Installation Cost
  Fewer civils and simpler infrastructure than traditional ball mills.

• High Energy Efficiency
  Up to 350 kW/m³ for lower power use and higher grinding efficiency.

• Accurate Scale-Up
  What you test is what you get. 1:1 scale-up guarantees real-world results.

• High-Intensity Grinding
  Stirred media design achieves finer grind sizes faster than tumbling mills.

• Open Circuit Configuration
  No large recirculating loads.

• Simplicity in Maintenance
  No grinding balls or high-pressure oil systems means reduced downtime.

• Large Scale
  Proves its value from test rigs to full-scale mineral processing operations.

• Better Recovery Rates
  Ultra-fine grinding and inert media improve liberation and downstream performance.

“IsaMill’s horizontal configuration means it’s completely different from other mills. IsaMill™ gives me an increased recovery that outweighs the cost. I never have to worry about the mill.”
- Amandelbult Operation, Anglo American

Beyond technical advantages, the IsaMill™ delivers measurable business returns compared to ball mills. When evaluating equipment for a mineral processing plant, understanding ROI (both direct and indirect) is crucial to make an informed decision.

1. Reduced Energy Costs

Traditional ball-mill-based milling processes lose power to media tumbling, often consuming vast amounts of energy with lower grinding efficiency. The IsaMill™, operating at energy intensities up to 350 kW/m³, can reduce energy use by 20–40% for equivalent grind sizes.

Example:
A plant processing 2 million tonnes of ore annually could save up to 1.5 GWh of energy per year with IsaMill™, translating into energy cost savings of $150,000–$250,000 AUD annually, depending on local power rates.

2. Lower Maintenance Expenditure

With no need for large grinding balls, liners, or high-pressure oil systems, the IsaMill™ uses modular, easily accessible components that simplify upkeep.

Impact:

• Lower spare parts inventory
• Fewer shutdown hours
• Improved safety during maintenance

3. Improved Mineral Recovery

The IsaMill's sharp particle size distribution relative to other stirred mills reduces surface contamination, leading to better flotation and leaching outcomes. In many circuits, this means 2–5% higher recovery rates, especially for precious metals and complex ores.

Scenario:
A gold mine increasing recovery by just 2% on a 100,000 oz/year operation adds 2,000 oz of extra production. This translates to a potential $5M+ AUD in additional annual revenue at current gold prices.

4. Smaller Plant Footprint

The IsaMill™ requires less structural steel and fewer pumps. That leads to faster construction timelines and reduced upfront costs.

5. Predictable Performance = Predictable Profit

With 1:1 scale-up, the IsaMill™ eliminates the uncertainty often encountered with new mill technologies. It gives operations clear performance expectations and a faster return on capital.

If you're wondering which mill is right for you, here's a quick guide on when to choose IsaMill™:

• You want to process fine or ultra-fine particles below typical ball mill limits
• You're working with refractory or complex ores where high liberation is needed
• You're looking to reduce energy consumption in your grinding circuit
• You need to cut back on maintenance costs and downtime
• You want a system that scales predictably and integrates with modern advanced process control systems

While tumbling mills such as SAG Mills are still the go-to for coarse primary grinding, IsaMill™ overtakes conventional ball mills once the target grind drops below ~100 µm, delivering finer liberation at a lower specific energy.

Trusted By Leading Mines Around the World

With thousands of cumulative operating hours logged, the IsaMill™ has a proven track record of success.

Since its first installation in the 1990s, the IsaMill™ has transformed mineral processing operations across more than 150 sites in 23 countries. It’s trusted by major players in the mining industry to deliver consistent, reliable, and scalable fine grinding performance.