The use of XRF analysis (X-ray fluorescence) has long been an accepted and recommended technique in the cement manufacturing industry as an analytical tool that provides elemental chemistry. Various types of XRF instruments are used in the cement industry in all stages of cement production from quarry to final product QA/QC. Having the right tools is essential in QA/QC as well as other stages of cement-making, making the cost-effective, easy-to-use, highly accurate elemental analysis method of XRF an essential tool in all cement production facilities. Currently, you will typically find various types of XRF instruments in a cement manufacturing facility, including but not limited to handheld XRF. Contact Bruker to find out how handheld XRF can benefit your cement operations.
Standard method ASTM C114 outlines the working requirements for cement analysis instruments.
Typical current uses and advances include:
- Analysis of samples in the field or “at line”
- Heavy reliance on XRF for production control
- Innovation in EDXRF (energy-dispersive x-ray fluorescence) hardware has resulted in smaller, more compact instruments with an increasing ability to measure light elements such as magnesium in MgO and Na2O, complementing—and in some stages replacing—already widely used WDXRF instrumentation.
How Can Handheld XRF Instruments Be Used at a Cement Plant?
- At-line for better control of raw mix blending and clinkerization
- Spot checks on finished product or clinker shipments in conjunction with a centralized WDXRF analyzer
- Analysis of raw materials from quarry- such as limestone and clay
- Analysis of feed stream materials: gypsum, limestone, quartz sand, clay, fuel, pozzolana and fly ash
- Raw mix control Laboratory-based analysis
- Checking of adulteration of finished cement
How Are Handheld XRF Analyzers used in the Quarry/Mill?
- For traditional geochemical applications, such as quarry drill campaigns to establish new source
- In the field to save time in raw materials extraction
- Elemental analysis of samples from exploration or blast hole drilling
- Deposit mapping
- Grade control
- Gypsum shipping and incoming inspection
- Finished mill dosage of Gypsum check
Handheld XRF Calibration Considerations for the Cement Industry
A particular challenge of using handheld XRF in the cement industry is the issue of calibration. Most handheld XRF analyzers come equipped with factory calibrations that carry names like “mining” and “soil.” Often the specifications on these calibrations lead users to believe that they will yield highly accurate results for cement industry samples, but this is often not the case. These One Standard geochemical calibrations can be used for a variety of matrices, but perform best on silicate and aluminosilicate type matrices.
- Many mining (ore) applications are focused on either oxide or sulfide ore with high metal content
- As matrices or chemical bonding diverge from the assumed configurations, the measurements will have more error and will eventually become semi-quantitative
- For raw material cement applications, the major component is carbonate (instead of oxide), so a separate application needs to be developed to get good results on limestone matrices
These calibrations tend to be too generalized and/or calibrated to a matrix that is not similar to the matrices found in cement manufacturing. Since these calibrations rely on mathematic approximations, their accuracy is easily thrown off by changes in matrix or other unexpected changes in values, density, attenuation, etc. One of the mathematical attributes of most generalized factory calibrations (but not Bruker’s) is normalization:
- Takes the sum of all measured elements and uses multipliers to normalize the concentrations to 100%
- All elements present in a sample must be either measured or associated by stoichiometry with a measured element
- Biggest effect is on the largest concentrations
Because normalization is not able to account for the matrix and other changes described above, while maintaining the same level of accuracy, it is best for cement analysis applications to create specific empirical calibrations that take into account the specific matrices and elements typical of cement samples.