Analysis of the raw meal, cement and clinker

An exemplary composition of the raw material prior to its extraction may be determined in three dimensions using the test drilling. This allows you to plan for the future mine plan. Immediately after its production raw material composition is determined by neutron activation, when the material passes through the conveyor belt. The method is based on the interaction between neutrons and the nuclei of the substance to be examined. The chemical composition can then be calculated from the obtained spectrum. The method allows to determine the composition of even inhomogeneous natural materials, provides uniformity of composition of the charge, high quality clinker and cement [35, 36, 37]. To assess the quality of the raw meal and clinker cement can be used various methods are generally used multiple methods. Chemical analysis by x-ray fluorescence analysis (XRF) provides information on the total composition. standard lime (CN) and the modules can be calculated from these data. They provide information about the quality of the clinker.

In addition the analysis of the potential phase content determined Bogue [5, 53, 54]. This calculation assumes that the clinker melt crystallizes in equilibrium with the solid phases (in practice this is not so), and that the phases of the clinker chemically pure, have the stoichiometric phase composition (pure C3S, C2S, C3A, S4AF) are not considered foreign ions and incorporating a phases of the clinker. Therefore, the calculation for Bogue phase content provides only approximate composition, but in practice these values ​​are slightly different. Typically, the actual content of alite and belite above. The actual content of aluminate and ferrite phase varies by only a few percent of the calculated values, the potential of the content. An important criterion is also the free lime content (content of free, unbound CaO). Currently it is mainly determined by X-ray diffraction, and only sporadically by the traditional "wet" chemistry [38, 39]. Due to the lime standard, it provides an indication of the production conditions, gives information about the extent of clinker burning. The content of free, unbound CaO can not exceed the limit value, which is about 2-3% by weight (depending on the production conditions), as this can lead to fractures in the hardened lime mortar or concrete.

While X-ray fluorescence analysis to determine the elements in the raw meal in cement and widely used X-ray diffraction method in the normal mode is usually used only for determining CaOsvob free lime. Recent developments in the use of X-rays to study powders, especially Rietveld refinement allows to apply quantitative phase analysis with X-ray diffraction. In the case of the Rietveld method "least squares refinement" calculations were made long before the best match results. However, based on structural data, and global parameters of the diffraction pattern is not obtained accurate data between the measured and calculated. Structural data relating to the current-phase mixture of the compounds can vary due to differences in chemical composition. The calculation is performed in the iterative process by changing the crystal structure parameters and profile. Using the Rietveld method was made possible by the simultaneous analysis of the separate phases, even with strongly overlapping reflections, as is often the case with cement. This method provides for automatic adjustment in industrial processes. It is expected to include the standard in the future analysis of the materials and products of a cement plant.

Microscopic examination of clinker allows you to set information about the nature, form and distribution of clinker phases. The weight content of the clinker phases depends on the chemical composition of the clinker. In contrast, the formation and distribution of the clinker phases depends on production conditions (composition of the raw meal, fineness, homogeneity, rate of heating of the charge, sintering time and clinker cooling rate. Experienced technicians can determine by microscopic image clinker nature of the effect of bad production conditions and provide guidance. corrective For this usually conducted research etched and polished thin sections in the reflected light with increasing x 50 - 1000. For phase identification and determining their quality using shape, color, reflectivity minerals etching is performed, hardness, etc. is determined. indicators

Petrographic analysis shows the actual mineral composition of clinker. Rational chemical analysis of clinker to determine its chemical composition, based on which with the help of the formulas can be determined settlement mineralogical composition of clinker. Estimated and actual structure is slightly different. Reasons for discrepancies include: 1) during firing and cooling, the clinker is not achieved complete phase equilibrium, remain free of CaO and SiO2; 2) the actual composition of the minerals is different from the calculated composition of the compounds, as part of alite and belite different from the composition of trёhkaltsievogo and dicalcium silicates, minerals, and similarly - flooded; 3) minerals form solid solutions; 4) significant changes in the theoretical composition of the clinker making lye.

As a rule, the actual content of alite in the clinker is always greater than the estimated, the actual content of C3A less than its rated amount.