X-ray Fluorescence Multi Element Analyzer For Cement
X-ray Fluorescence Multi Element Analyzer For Cement
The chemical composition of cement plays a crucial role in the determination of its properties as a binder substance. The chemical analysis of cement components is widely used in the cement industry for production optimization and stable high-quality assurance of the final product.
High requirements for cement quality are formed by its usage in the fabrication of concrete – the most consumed material in the building industry.
The Constituents of Cement
Cement materials are classified into two classes depending on the type of hardening.
The first class: hydraulic cement,requires the addition of water for hardening. Hydraulic cement is most widespread in the industry nowadays.
Generally, hydraulic cement is made of a mixture of silicates and oxides. The fabrication process of the cement involves several stages. In the first stage, the raw components are crushed into the powder and mixed. In the second stage, the mixture is fired in special furnaces at high temperatures. During the firing of the ascending mixture, calcium carbonate decomposes into calcium oxide and carbon dioxide as well as clay. Calcium oxide interacts with clay components at high temperatures and forms silicates, aluminosilicates, calcium aluminates, and other components. The final product of the firing process is called clinker. In the third stage, the clinker is ground with gypsum in mills with steel balls. The gray-green powder obtained in grinding processes is hydraulic cement.
The second less common class of cement is non-hydraulic. The typical representative of the non-hydraulic cement is slaked lime (the mixture of calcium oxide with water) which hardens by carbonation with carbon dioxide from the air.
In the cement production low temperature melting clays are used, argillites and shales, which are part of the cement mixture. The second main component is carbonate rocks. Limestone and clay are the raw material for cement production. They are mixed in a certain ratio (75-80% limestone and 20-25% clay).
The chemical composition of cement determines its properties and area of application. The main task of
a cement tester is through analysis of elements (determination of 13 oxides and their ratio: CaO, SiO2,
AlO, FeO, SO, MgO, NaO, KO, PO, TiO, MnO, ZnO, SrO) and which allows precise control of the 2 3 2 3 3 2 2 2 5 2 2 3
quality of cement production.
The composition of mineral substances in cement provides extensive information about the quality and properties of cement, but to provide accurate enough measurements is quite difficult. It is much easier to provide elemental analysis than mineral composition analysis. And also it is possible in an easy way to convert the elemental ratios acquired into weight fractions of each oxide in the sample. The ratios of oxides present in the sample give an estimation of the precise enough cement mineral composition.
There are a lot of spectroscopy methods for the determination of elemental analysis of cement: atomic, Raman, gravimetry, X-ray photoelectron, and inductively coupled plasma mass. Most of them require additional methods or could be destructive for the sample and expensive equipment.
Many cement plants use quantitative X-ray diffraction analysis to determine the phase clinker composition. But the X-ray analysis of the cement has one major drawback: neglection of the structural decay of some weak or cleavable mineral phases like gypsum, anhydrite, or calcite in the sample during the measurement.
X-ray fluorescence (XRF) analysis is the universal method for elemental analysis. It combines simple enough procedures and correspondingly cheap equipment. Also, it provides fast and accurate results. Thus, x-ray fluorescence (XRF analysis) in cement analysis is the most convenient, easier, and suitable elemental analysis method in thecement industry.
In cement plants, XRF for cement analysis is used routinely and it is the primary way to control the composition of the raw material, the raw feed, as well as clinker and actually cement. This method provides rapid compositional data for controlling almost all stages of production and is also used for assessing and quality control of the final product.
