Method of quantitative determination of portland cement clinker phase composition

FIELD: machine building.

SUBSTANCE: polished section is premade from Portland cement clinker to reveal phase present in said section under microscope. Thereafter, phase compositions are compared to correct phase composition defined from X-ray diffraction spectrum of phases revealed in minor quantities. Then, relationship between two alite monoclinic modifications are defined. Said alite is contained in clinker in major amount. Said modifications are defined by analysing asymmetry of superimposed reflections in the range of angles 2θ_Cu ⁼31.5-33°. Then, Ritweld method is used to define quantitative content of all revealed phases by, first, one monoclinic modification. Then, it is defined by second monoclinic modification. Now, defined is quantitative content of all phases in the range of their mean content and that obtained from monoclinic modification present in major amount.

EFFECT: higher validity, accuracy and comprehension.

2 cl, 6 dwg

The invention relates to the field of construction, in particular for the cement industry, and can be used to control the phase composition, which determines the quality of commonly used Portland cement materials.

Known methods of determining the phase composition of the cement materials [1, 2]. Known chemical method for determining the number of one of the phases of cement clinker - silicates of calcium [1], in which the determination is made with the use of simple and cheap equipment, making it available for use in cement plants with a daily production quality control. However, the known method has limitations because it is intended only to define one phase and therefore is not sufficiently informative.

Known x-ray method for quantitative determination of the total content of clinker in cement [2], in which the definition produced by the method of internal standard and reference samples are prepared from a mixture of clinker with additives fluctuations that the samples cover the entire range of variation of the cement composition. The intensity of x-ray analytical lines of one of the clinker minerals are correlated with the clinker content in cement. Moreover, use of this mineral, which is payable only clinker, for example, is lit. Next, determine the ratio of the intensity of the analytical line of tricalcium silicate and intensity of the standard, which is taken calcium fluoride. However, the known method is time-consuming, since it requires the preparation of reference samples, and uninformative due to determine only the total content of all phases of clinker in cement.

There is a method of quantitative determination of the phase composition of Portland cement clinker [3] x-ray Rietveld method (i.e. method full-profile analysis), which is the closest to the claimed invention achieved technical result. The known method consists in determining the content of the clinker phases and their polymorphic modification by x-ray diffraction spectrum of the powder from the drug, made from the analyzed Portland cement clinker. It monoclinic modifications Alita, which is present in the studied clinker at the maximum number, choose the option with the best convergence factor by Rietveld method. The method does not require preparation of standard mixtures.

The disadvantages of the prototype are not high enough accuracy, reliability and information content of quantitative determination of the phase composition due to incomplete accounting present therein phases.

Stated from Britanie devoid of these shortcomings.

The technical result of the claimed invention is to improve the accuracy, reliability, and usefulness of quantitative determination of the phase composition of Portland cement clinker.

This technical result is achieved in that in the method for quantitative determination of the phase composition of Portland cement clinker, consisting in obtaining x-ray diffraction spectrum from a powdered drug made from the analyzed Portland cement clinker, the definition on the obtained x-ray diffraction spectrum of the phase composition of the powder preparation containing alit, polymorphous modifications of each identified phase and its quantitative content by the Rietveld method, in accordance with the claimed invention is made of the polished sections of the investigated Portland cement clinker, which visually under a microscope reveal present in polished sections of phase, then the phase compositions compare and carry out the adjustment of the phase composition, which is obtained by x-ray diffraction spectrum, in those phases, which is revealed in the smallest quantities, and then determine the ratio of two monoclinic modifications Alita, which is contained in the study clinker in the greatest quantity by analyzing the asymmetry imposed reflections in the interval of angles 2θ_Cu=31,5-33°, after which it by the Rietveld method to determine the quantitative content of all of the detected phases, consistently first one monoclinic modification Alita, then in his second monoclinic modification, and then determine the quantitative content of all phases in the studied clinker in the interval between their average content and the content obtained by the monoclinic modification Alita present in larger quantities.

In addition, this technical result is achieved by measuring x-ray diffraction spectrum are produced in automated powder x-ray diffractometer using copper radiation, in the range of angles 2θ ~5-80°, at a voltage of 45 kV and current of 35 mA.

The essence of the claimed invention is illustrated Figure 1-6.

In figure 1 as a reference presents a color photograph of minerals of Portland clinker in polished sections under an optical microscope [4].

Figure 2 as a reference presents fragments of powder x-ray monoclinic modifications Alita.

3 shows the powder x-ray analyzed clinker factory "Sukholozhskcement".

Figure 4 presents a photograph of the minerals studied clinker factory "Sukholozhskcement" in polished sections under an optical microscope.

Figure 5 shows a photograph of the minerals studied clinker factory "Sukholozhskcement" in polished sections under scanning electron mi is ROKOPOL.

Figure 6 shows the asymmetry imposed reflections of monoclinic modifications Alita on powder x-ray analyzed clinker factory "Sukholozhskcement".

In addition, the essence of the claimed method is illustrated in the shown tables 1-3.

Table 1 presents the results of different stages of obtaining quantitative phase composition of clinker factory "Sukholozhskcement".

Table 2 presents the results of different stages of obtaining quantitative phase composition of clinker factory " LIPETSKCOMBANK"

Table 3 presents the results of different stages of obtaining quantitative phase composition of clinker plant "CEMENT PIKALEVO".

The essence of the claimed method is implemented in the following sequence.

Determination of the phase composition of Portland cement materials begins with the preparation of investigational clinker powder preparation for x-ray studies. When preparing a powder of the drug granules of cement clinker (about 1 g) is ground in a ceramic mortar. The degree of readiness of the drug is determined with the aid of tactile sensations: the prepared sample should not contain visible grains. Next, the sample is evenly distributed in the cell, which is then installed in the automatic x-ray powder diffractometer and they hold to change the possible x-ray diffraction spectrum using copper radiation, in a wide range of angles 2θ~5-80°, at a voltage of 45 kV and current of 35 mA.

On spectrum obtained using well-known specialized databases powder x-ray diffraction data [5, 6] determine the phase composition of the powder of the drug, including alit, bleaches, almaterra, spinel and periclase, polymorphous modifications of each identified phase. Next, make the adjustment of the phase composition and the rst phase, present in small quantities, and then Alito present in the studied clinker in the maximum number.

The first adjustment of the phase composition of the clinker is as follows. First, from the study of clinker produced the polished sections. When the polishing of the polished sections to avoid hydration of the clinker phases, use the minimum amount of water, gradually reducing its number to the end of polishing to zero.

Then visually on the basis of differences in morphological characteristics of clinker minerals and their distribution in the clinker determine the phase composition of clinker in polished sections under an optical or electron microscope. After microscopic examination of the phase composition of obtained x-ray and microscopic methods, compare, and thus eliminate the uncertainty of the phase composition, which is was b obtained by x-ray diffraction spectrum, in those phases, which were presented on the x-ray one peak: choose between triclinic modification of Alita and Belita between cubic and tetragonal modification of aluminate, specify the presence of magnesia.

To illustrate the first adjustment figure 1 shows known [4] a photograph of the clinker minerals in polished sections under an optical microscope, on which grain Alita shaded brown, Belita blue, almateria blue, spinel black; areas of filled epoxy resin grey. It is seen that for Alita typical isometric large crystals with high relief; for Belita - rounded grains with the hatch, which usually form clusters, rarely are between crystals Alita. The field of almateria with small dark inclusions of spinel, are located in the intergranular space Alita and Belita. In addition, the size and shape of the discharge aluminate allow you to make a preliminary conclusion about its polymorphic modifications, as the cubic aluminate is characterized by small isometric crystals, and rhombic - Board and elongated crystals of a larger size.

The second adjustment of the phase composition of the clinker is carried out, analyzing on powder x-ray asymmetry of the two superimposed broad reflections of monoclinic modifications of the lita (M1, M3) in the interval of angles 2θ_Cu=31,5-33°. In this way reveal the ratio of these modifications in the clinker. If the asymmetry is manifested by small angles, 2θ, prevails M3 modifications, if large - M1. This approach to determining monoclinic modifications Alita is optimal, because of the proximity of their unit cells (a= 12.33, 33.08; b = 7.06, 7.03, = 25.05, 18.49, Å; β = 90.06°, β = 94.12°, respectively [3]) is not imposed reflect these phases on the x-ray is missing.

To illustrate the second adjustment figure 2 presents fragments of powder x-ray monoclinic modifications Alita in the range of angles 2θ_Cu=31,5-33°, calculated from structural data [3, 7, respectively]. Specify the diffraction indices reflections. Structural parameters for these calculations (relative coordinates of the atoms, the occupancies of the positions and offsets) were taken from the database structural data Findit [8]. It is seen that in the presence of clinker two monoclinic modifications Alita their reflections will overlap, forming two superimposed maximumunilateral asymmetry which reflects the proportion present monoclinic modifications.

After making adjustments of the phase composition of the clinker is the quantitative definition is of the content of all phases by the Rietveld method first one monoclinic modification Alita, then in his second monoclinic modification. Quantitative determination of the phase composition of clinker by the Rietveld method on two modifications Alita at the same time is not possible (the program fails because of the proximity of their structural characteristics).

In the last step, determine the content of each of the phases in the studied clinker Q (wt.%) and the maximum error of its determination Δ (wt.%) from the formula:

Δ=|Q-Qi|,

where QM1, QM3 - the content of the phases obtained for each of the monoclinic modifications Alita (M1, M3), QMi - content phase, obtained by the monoclinic modification Alita present in larger quantities.

The claimed invention was tested on a laboratory basis of the St. Petersburg state University (SPBU) in real time numerous studies conducted with samples of Portland cement clinker with four cement plants in Russia: JSC "Sukholozhskcement" (Sverdlovsk region), JSC "LIPETSKCOMBANK" (the city of Lipetsk), CJSC "PIKALEVSKII CEMENT" (Leningrad region).

Specific examples of the tests are given below in examples 1, 2.

Example 1

Determination of the phase composition portlandcementnogo clinker obtained at the plant "Sukholozhskcement".

From the sample of clinker, which consisted of granules the size of the om from 0.5 to 3 cm, preparing a powder preparation, designed for x-ray studies, and at the same time it is the polished sections for microscopic examination. When preparing a powder of the drug granules of cement clinker (about 1 g) was ground in a ceramic mortar. When the polishing of the polished sections to avoid hydration of the clinker phases, used the minimum amount of water, gradually reducing its number to the end of polishing to zero.

X-ray examination is made of clinker powder preparation was carried out in interdepartmental x-ray laboratory of the geological faculty of St. Petersburg state University, automatic powder diffractometer STOE STADI P using copper radiation, in the range of angles 2θ~5-80°, when the voltage of 45kV and current 35mA. Measurement of the x-ray spectrum can be carried out either by passing, in which the monochromator (Ge) is installed on the primary beam, either by reflection, in which the monochromator is installed on diregiovani (i.e. reflected) beam; in both cases, a step-by-step mode: point spacing of 0.2° 2θ, time measurement at the point ~100 sec. In this example we used the method of passing.

Determination of the phase composition, polymorphic modifications of phases was performed using the database of powder x-ray diffraction data [5, 6]. Aspect] is the solution of the two monoclinic modifications Alita found, analyzing the asymmetry of the two superimposed reflections Alita in the range of angles 2θ_Cu=31,5-33°: Quantitative content of all present phases produced by the method of Rietveld program FullProf [9]. The content of the phases was determined sequentially first one monoclinic modification Alita, then in his second monoclinic modification.

The approximation of the profiles of reflections produced by an asymmetric function of the Pseudo-Voigt. The coordinates of the atoms and the values of populations of positions secured, thermal factors equated to unity. First in the queue was specified coefficients of a polynomial background and place of zero. Then refined parameters was established and began the gradual refinement of the parameters characterizing each phase (starting with Alita, then Belita, almateria, aluminate and at the end of magnesia): scale factor (concentration of all phases), unit cell parameters and coefficients are functions of the Pseudo-Voigt. At the final stage of re-specify the coefficients of the polynomial background and place of zero. For each parameter was performed 8 cycles of refinement. The control results of the refinement was carried out on the basis of the standard factors of convergence that characterizes the closeness of the experimental and calculated intensities of x-ray diffraction spectra.

After that determined the content of each of the phases in the studied clinker Q (wt.%) and m is similou error of its determination Δ (wt.%) from the formula:

Δ=|Q-Qi|,

where QM1, QM3 - content phase obtained for each of the monoclinic modifications Alita (M1, M3), QMi - content phase, obtained by the monoclinic modification Alita present in larger quantities.

Microscopic examination is made of clinker was carried out on polished sections of an optical microscope Leica Microsystem CMS CmBh in reflected light at 10× and 20× magnification and scanning electron microscope Quanta 200 3D with energy dispersive microprobe EDAX in reflected electrons at a voltage of 15-20 kV in high vacuum. Determination of the phase composition of clinker under the microscope were made visually on the basis of differences in morphological characteristics of clinker minerals and their distribution.

The results obtained are presented in table 1 and detailed in figures (3-6).

Determination of the phase composition of the powder of the drug on the x-ray spectrum (Figure 3) revealed a significant amount of tricalcium silicate alit in the form of a mixture of two monoclinic modifications M1+M3 (figure 3 marked A), and almaterra (figure 3 marked AF) and a very small amount of aluminate (figure 3 labeled AL). In addition, x-ray powder spectrum is weak reflection (2θ_Cu=32°, in the figure denoted by X), which may indicate the presence of β-is odificatio Belita (reflection 103, the relative intensity 100) or triclinic modification Alita (reflectionthe relative intensity of 100).

The study of polished sections of the investigated clinker under an optical microscope (Figure 4) revealed numerous light yellow large isometric grains Alita, between which are clearly visible, light-gray, rounded with the hatch grain companies. Intergranular space filled with bright, fairly large chunks of almateria with small dark inclusions aluminate.

The study of polished sections of the investigated clinker under the scanning electron microscope (Figure 5) allowed to thoroughly review clusters of rounded grains, the companies with a pronounced hatching (Figure 5,a) and find a single grain of magnesium oxide (Figure 5,b).

Comparison of the results of phase analysis x-ray and microscopic methods have shown that the reflection of X in the powder x-ray diffraction spectrum belongs to the companies and found magnesium oxide (probably periclase), reflection is on the radiograph are not visible (the strongest reflection is superimposed on the peak Alita).

Analysis of the profiles of two superimposed reflections of monoclinic modifications Alita (M1, M3) in the interval of angles 2θ_Cu=31,5-33° (6) revealed asymmetry by small angles 29, which suggests that in the study the intensity of clinker is Yunosti reflections M3 modifications more than M1, i.e. modification M3 prevails.

Thus, the phase composition of the clinker presents tricalcium silicate by alicom (main phase), which is present in two monoclinic modifications (content M3 more than M1), and β-modification, Belita, almateria, cubic spinel and periclase (single grain).

The results of all stages of determining the quantitative phase composition of the clinker given in table 1. Given the results of determination by the Rietveld method on each of the two monoclinic modifications Alita (QM1, QM3) and proposed method (Q). For options QM1, QM3 in parentheses are standard errors in the determination of δ, for the case Q is the maximum error in the determination of Δ and the corresponding relative error Δ/Q. in Addition, for options determine the quantitative phase composition by the Rietveld method (QM1, QM3) shows the values of the parameters (R_f, GoF), characterizing achieved by the Rietveld method convergence, and values |Q1-Q3|/δ_maxdescribing the significance of the differences obtained results.

Parameter values (R_f, GoF), characterizing achieved by the Rietveld method in each case, convergence, for option definitions with modification Alita M3 is slightly lower than for the case of modification Alita M1, indicating that n is a slight predominance of modifications M3. The results of the determination of phases in two modifications Alita (QM3, QM1) differ significantly (difference in the content of all phases more than 4 standard errors δ), which indicates a lack of reliability and informative quantitative determination of the phase composition.

The results of the determination by the proposed method (Q) and option QM3 (with best convergence factor most strongly diverge in the case of Alita and almateria. Any difference in content (Δ) equal to 1.8; 1.0 wt.% respectively, which exceeds 9 standard errors of determination of phases in the variant QM3. The relative error in the determination of the phases of the proposed method for the main phase Alita is 3%and for the remaining phases varies from 1 to 9%.

Example 2

Comparative analysis of the achievement of the technical result of the claimed method.

For assessment of the achievement of the technical result of the claimed method will compare the results of the quantitative phase analysis of Portland clinker with various factories in Russia: JSC "Sukholozhskcement", JSC "LIPETSKCOMBANK", CJSC "LOCAL CEMENT (table 1-3).

Conducted previously described (example 1) the study showed that all the clinkers main phase is alit, which is present in two monoclinic modifications (M1, M3)and bleaches (β-modification), almaterra, aluminate (probably in the form of cubic modification) and periclase (single grain). In the clinker plants "Sukholozhskcement" and "LIPETSKCOMBANK" prevails M3 modification Alita, and clinker from the factory at the TOWN CEMENT - M1 modification.

As can be seen from the presented results of extensive testing of the claimed method:

Content Alita varies from 60 to 70 wt.%, the maximum error in the determination of this phase is from 1 to 2 wt.%, the relative error ranges from 1 to 3%.

- The content of almateria varies from 10 to 17 wt.%, the maximum error in the determination of this phase is about 1 wt.%, the relative error ranges from 4 to 7%.

- The content of the companies varies from 12 to 18 wt.%. the maximum error in the determination of the phase is from 0.2 to 1 wt.%, the relative error ranges from 1 to 8%.

- The content of aluminate varies from 3 to 6 wt.%, the maximum error in the determination of the phase is from 0.02 to 0.4 wt.%, the relative error ranges from 0.3 to 9%.

The magnesia content varies from 2 to 3 wt.%, the maximum error in the determination of the phase is from 0.2 to 1 wt.%, the relative error can reach from 7 to 4%.

The accuracy of quantitative determination of the total content of clinker is 2-3 wt.%, and the relative error is only 2-3%.

The results obtained confirm that the claimed method is significantly better than the known analogues accurate and informative.

Technical and economic efficiency of the claimed method is accurate and informative it is used in the national economy in the daily quality control in cement plants, as well as for quality control of Portland cement, widely used in civil construction, as well as strategically important facilities, oil and other industries.

Sources of information

1. The method of quantitative determination of the phase composition of Portland cement clinker, consisting in obtaining x-ray diffraction spectrum from a powdered drug made from the analyzed Portland cement clinker, obtained by x-ray diffraction spectrum determine the phase composition of the powder of the drug, including alit, polymorphous modifications of each identified phase and its quantitative content by the Rietveld method, wherein the pre-made polished sections examined the Portland cement clinker, potatoria visually under a microscope reveal present in polished sections of phase, then the phase compositions compare and carry out the adjustment of the phase composition, which is obtained by x-ray diffraction spectrum, in those phases that are identified in the smallest quantities, and then determine the ratio of two monoclinic modifications Alita, which is contained in the study clinker in the greatest quantity by analyzing the asymmetry imposed reflections in the interval of angles 2θ_Cu=1.5 to 33°, then by the Rietveld method to determine the quantitative content of all of the detected phases, sequentially first one monoclinic modification Alita, then in his second monoclinic modification, and then determine the quantitative content of all phases in the studied clinker in the interval between their average content and the content obtained by the monoclinic modification Alita present in larger quantities.

2. The method according to claim 1, characterized in that the measurement x-ray diffraction spectrum are produced in automated powder x-ray diffractometer using copper radiation in the range of angles 2θ~5-80°, at a voltage of 45 kV and current of 35 mA.