Ponnusamy Sampathkumar, Consultant – Process Optimisation and Training, discusses the role of skilled operators as the decisive link between advanced additives, digital control and world-class mill performance.

The industry always tries to reduce the number of operators in the Centre Control Room. (CCR) Though the concept was succeeded to certain extent, still we need a skilled person in the CCR.
In an era where artificial intelligence (AI) grinding aids, performance enhancers, and digital optimisation tools are becoming increasingly sophisticated, it’s tempting to believe that chemistry alone can solve the challenges of mill efficiency. Yet plants that consistently outperform their peers share one common trait: highly skilled operators who understand the mill as a living system, not just a machine.
Additives can improve flowability, reduce agglomeration, and enhance separator efficiency, but they cannot replace the nuanced judgement that comes from experience. Grinding is a dynamic process influenced by raw material variability, moisture, liner wear, ball charge distribution, ventilation, and separator loading. No additive can fully compensate for poor control of these fundamentals.

Operators see what additives cannot
When I joined the cement industry in 1981, not much modernisation was available then. Mostly the equipment was run from the local panel. Once I was visiting the cement mills section. The cement mills were water sprayed over the shell to reduce the temperature to avoid the gypsum disintegration.
The operator stopped the feeding for one of the mills. When I asked the reason, he replied that mill was getting jammed, and he added that he could understand the mill condition by its sound. I also learned that and it was useful throughout my career. In another plant I saw the ‘Electronic Ear,’ which checked the sound of the mill and the signal was looped with feed control!
Whatever modernisation we achieve, it is from the human factor that the development starts.
Additives respond to conditions; operators interpret them.
A skilled operator can detect subtle shifts, like a change in mill sound, a slight variation in circulating load, or a drift in separator cut point. It’s long before instrumentation flags a problem. These micro-observations often prevent major efficiency losses.
Additives work best when the process is stable
I would like to share one real time incident. The mill was running on auto mode looped with the mill outlet bucket elevator kilowatt. (KW)There was a decrease in the KW, and the mill feed was increased by the auto control (PID). After a while, the operator stopped both the feed and the mill. He asked the local operator to check the airslide between mill outlet and the elevator. They found the airslide was jammed and no material flow to the elevator!
The operator deduced the abnormality by his experience by seeing the conditions and the rate of increase of the feed by the auto control.
It’s always the human factor that adds value to the optimisation.

Grinding aids are multipliers,
not magicians.
They deliver maximum benefit only when:
• Mill ventilation is correct
• Ball charge is balanced
• Feed moisture is controlled
• Separator speed and loading are improved
• Blaine targets are realistic
Without these fundamentals, even advanced additives may become costly investments. The operator is responsible for ensuring process stability, whether using a ball mill or a vertical mill. After ensuring the system is stable, the operator observes it briefly before transitioning to automatic control. If there is any anomaly in the system the operator at once takes control of the system, stabilises and bring back to auto control.

Skilled operators adapt in real time
It will be interesting to note that the operators who operate from local panel start to operate from DCS also. They have the experience and the ability to adapt the changes. Operator checks each parameter deeply. Any meagre change in the parameters is also visible to him.
Raw materials change. Weather changes. Wear patterns change.
A skilled operator adjusts:
• Feed rate
• Water injection
• Separator speed
• Grinding pressure (in VRMs)
• Mill load distribution.
These adjustments require intuition built from years of experience, something no additive can replicate.

Human insight prevents over reliance on additives
Plants sometimes increase additive dosage to mask deeper issues like:
• Poor clinker quality
• Inadequate drying capacity
• Incorrect ball gradation
• High residue due to worn separator internals.

A knowledgeable operator finds root causes instead of chasing temporary chemical fixes.
The real optimisation sweet spot is reached when:
• Operators understand how additives interact with their specific mill.
• Additive suppliers collaborate with plant teams.
• Process data is interpreted by humans who know the mill’s behaviour.
This constructive collaboration consistently delivers:
• Lower kWh/t
• Higher throughput
• Better product consistency
• Optimum standard deviation.

Advanced additives are powerful tools, but they are not substitutes for human ability. Grinding optimisation is ultimately a human driven discipline, where skilled operators make the difference between average performance and world class efficiency. Additives enhance the process but operators
control it.

About the author:
Ponnusamy Sampathkumar, Consultant – Process Optimisation and Training, is a seasoned cement process consultant with 43+ years of global experience in plant operations, process optimisation, refractory management, safety systems and training multicultural teams across international cement plants.