Cement Manufacturing FAQs

Analyzer placement depends on the plant layout and process goals, but most cement plants start by controlling raw-material quality in the pre-blending stockpile. In this setup, the analyzer is typically installed after the primary crusher and before the stockpile, monitoring the material from the quarry. It provides immediate feedback when undesirable materials—such as those high in magnesium, alkalis, or sulfur—enter the process. Using the analyzer at this point helps maintain consistent stockpile chemistry and reduces the need for costly corrective additives later.

Some plants, however, achieve the greatest benefit by installing the analyzer at the raw-mix proportioning stage, where it provides high-frequency analysis and automatically adjusts raw-material feed rates in real time.

When deciding placement, discuss your stockpile, blending, or proportioning objectives with your Thermo Fisher Scientific application specialist.

Online analyzers measure the entire material stream continuously and in real time as it moves along the conveyor belt. The system typically provides a new elemental analysis every minute—without sampling, handling errors, or lab delays. This frequency is more than sufficient for precise process control, though it can be adjusted if needed.

Real-time awareness of the raw-material chemistry allows producers to use more of the deposit efficiently. By identifying variable or lower-grade materials that can still meet target chemistry, plants reduce waste, rely less on external raw materials, and extend the usable life of the quarry.

Yes. The single biggest lever for lower energy use is kiln feed with correct chemistry and low variability. Online PGNAA helps enable high-frequency control of raw-mix proportions to keep chemistry on target.

Why online beats offline lab loops:

• Lab X-ray control relies on small, intermittent samples; typical loop time is 30–60 minutes, so high-frequency variations are often missed.
• Changes based on lab results can be out of date and occasionally push chemistry further off spec.
• Obtaining truly representative samples is difficult; online analysis measures the entire material stream continuously (about every minute) with no sampling error.

How the control works:

• At raw-mix proportioning, the analyzer provides minute-by-minute results and the software automatically adjusts feeder rates to smooth fluctuations.
• The same principle applies to pre-blending stockpiles; feedback is slower because it’s directed to mining/loaders rather than feeders, but variability still drops.

Energy impact:

• More stable kiln feed helps reduce fuel needed for complete reaction.
• Less over- or under-reacted clinker means lower finish-mill energy.
• Fewer process upsets further cuts wasteful energy spikes.

Yes. Reducing raw-material chemistry variation is one of the main goals of installing an online analyzer. Real-time PGNAA measurements, combined with automated proportioning control, allow precise adjustment of raw-material feeds to maintain consistent quality parameters such as LSF, SM, and AM—as well as individual oxides or mineral phases like C3S, C2S, C3A, and C4AF.

In a recent case study, continuous PGNAA analysis replaced the traditional 90-minute lab sampling cycle, eliminating sampling errors and enabling minute-by-minute control. The result was a 70% reduction in LSF variation, 50% in SM, and 33% in AM. More stable raw meal led to a 50% decrease in clinker free-lime variability (0.72 → 0.37), improved kiln stability, lower fuel consumption, and longer brick life.

Yes. Controlling stockpile chemistry is one of the most common applications of cross-belt online analyzers. Whether the stockpile is longitudinal or circular, continuous analysis keeps pile chemistry close to target, minimizing variation within and between piles. This helps ensure consistent kiln feed and gives producers more flexibility in quarry operations.

For example, when blending limestone and clay, a single quality parameter such as LSF or Alite (C3S) may be sufficient if each material has uniform chemistry. However, if the limestone and clay vary across the quarry—such as high- and low-grade zones, or clays rich in silica, alumina, or iron—then the analyzer can manage multiple material types simultaneously to achieve the desired blend.

Most quarries have several distinct material grades across different benches, making real-time online analysis essential for building consistent, high-quality stockpiles.

Read more: Question About Limestone and Clay Blending in Cement Production.

Yes. The same principles used for stockpile control apply to raw-mix proportioning. Online PGNAA analysis provides continuous feedback on the chemistry of each material feed, allowing automated control software—such as RAMOS Raw Mix Optimization—to adjust feeder rates in real time.

This helps ensure the raw mix consistently meets target values for key moduli (LSF, SM, AM), reduces chemistry variability, and minimizes the use of costly corrective additives—all while maintaining the lowest possible production cost.

The number of control parameters (such as moduli or oxides) that can be optimized is one less than the number of distinct raw materials available.

In simple terms, if you have four different raw materials, you can simultaneously control three quality parameters (n – 1 rule). The more independently variable materials you feed, the more control flexibility the system provides.

Prompt Gamma Neutron Activation Analysis (PGNAA) and Pulsed Fast Thermal Neutron Activation (PFTNA) are non-contact, non-destructive analytical techniques used in online analysis systems to determine the elemental composition of bulk raw materials. Both techniques are known collectively as neutron activation analysis and function by bombarding materials with neutrons.

The neutrons interact with elements in the materials, which then emit secondary, prompt gamma rays that can be measured. Similar to X-ray fluorescence (XRF), each element emits a characteristic energy signature as it returns to a stable state.  

Learn more about PGNAA and PFTNA technology here.

PFTNA (Pulsed Fast Thermal Neutron Activation) is a form of PGNAA (Prompt Gamma Neutron Activation Analysis), but PFTNA uses an electrically-operated neutron generator as its source of neutrons as opposed to sourcing them from an isotope like PGNAA does. 

Learn more about PGNAA and PFTNA technology here.

A neutron is a neutrally-charged sub-atomic particle that is a component of the nucleus of all elements (except for simple hydrogen).

Essentially two types of neutron sources exist to enable PGNAA: (1) A fissionable radioisotope (or combination of radioisotopes); or (2) electronically powered specialized compact linear accelerator called a neutron generator. 

Radioisotopes that fission neutrons which can be used for PGNAA are either ²⁵²Cf or the combination AmBe. By far, the most common radioisotope utilized is ²⁵²Cf for various reasons one of which is safety.

Yes. Although online analyzers use neutrons for measurement, they are engineered for safe operation in industrial environments. Leading manufacturers design these systems so that radiation levels remain well below regulatory limits, allowing personnel to work around the analyzer without special access restrictions or monitoring.

Thermo Scientific online cement analyzers, for example, are heavily shielded to keep radiation near background levels under normal operating conditions. If a neutron generator is used instead of a radioisotope source, it can also be switched off at any time for added safety and convenience.

Data from the analyzer are processed and displayed through an advanced interface that also monitors instrument health in real time. Results are automatically stored and can be viewed by multiple users simultaneously from any workstation connected to the plant network.

Learn more about OmniView online elemental analyzer interface software here.

Maintenance is minimal because the analyzer has no moving parts. For isotope-based systems, the source must be periodically replenished—typically by adding about half the original amount after each half-life of the isotope has passed. For neutron-generator systems, the accelerator tube inside the generator head needs periodic replacement.

To simplify upkeep and help ensure maximum uptime, Thermo Scientific analyzers are connected to the Instrument Performance Management (IPM) platform, which continuously monitors system health and alerts service teams before maintenance is required.

Yes. Automatic calibration software continuously compares analyzer results with laboratory measurements to keep your system operating at peak accuracy. The software provides both statistical and graphical analyses, identifying any drift and applying timely corrections.

Consistent calibration helps ensure stable kiln feed, leading to higher throughput, lower fuel and power consumption, and longer refractory life.

Learn more about AccuLINK software here.