Grinding aid tablet with integrated standard

Abstract

The invention relates to a grinding aid. The grinding aid comprises the following components: A, 15-40% of cellulose or cellulose derivatives; b, 40%-60% of natural resin; c, 0% to 5% of an auxiliary agent and a coating substance; and D 15-25% of a crystalline inorganic material as an X-ray standard, the sum of the components A, B, C and D being 100%, all the values being weight percentages.

Description

[0001] The present invention relates to a grinding aid tablet having an integrated crystalline substance which serves as a standard for the quantitative determination of amorphous components by X-ray diffraction, for example for the production of clinker and cement.

[0002] Today, samples in, for example, the cement industry, the aluminum industry or steel production are often quantitatively analyzed by X-ray diffraction methods, which are sometimes automated for process control. For quantitative evaluation, Rietveld refinement is performed, which allows the relative amounts between the individual phases to be determined quantitatively. In particular, area detectors are used here for process control, which can significantly shorten the measurement time for quantitative analysis, with the accuracy of individual phase fractions being as low as 0.1%. Here, there are difficulties in the quantitative determination of amorphous compounds, and therefore adjustments are usually made via so-called pseudostructures.

[0003] Grinding aids, in particular grinding aid tablets, have three main functions. First, the grinding aid contributes to the grinding effect, which enables better homogenization of the sample during grinding. Second, the grinding aid is intended to make the automatic cleaning of the grinding unit easier. Especially during a purely automated sample production process, this enables the minimization of contamination between successive samples by achieving complete discharge. Then, these components of the grinding aid tablet also provide a third effect, namely stabilizing the produced pressed sample pellets to ensure that they can be easily studied and processed. Therefore, grinding aids are usually added in an amount on the order of about 10% by weight.

[0004] The use of a grinding aid in the form of a grinding aid tablet enables good, especially automated processing, very simple and reliable dosing, and avoids contamination problems.

[0005] DE 10 2013 106 998 A1 discloses a process and a device for producing pellets.

[0006] DE 10 2020 201 877 B3 discloses the composition of a grinding aid tablet.

[0007] The materials of grinding aids are usually amorphous and thus have an impact on the usually already existing amorphous matrix. This makes it difficult to quantitatively determine the amorphous components in the sample.

[0008] In addition to the three requirements that the grinding aid tablets already mentioned must meet, there are of course further requirements, namely that the grinding aid tablets themselves must be stable in order to enable reliable, especially automated processing.

[0009] The problem to be solved by the present invention is to be able to quantitatively determine all phases of a sample as much as possible.

[0010] This problem is solved by a grinding aid having the features defined in claim 1 and a method having the features defined in claim 8. Advantageous improvements will be apparent from the dependent claims and the following description.

[0011] The grinding aid according to the invention serves to make the sample more easily grindable, in particular in an automated manner, and to produce stable X-ray analysis pellets for subsequent studies by X-ray diffraction. Here, the function of the grinding aid is to assist in grinding and thus in the good homogenization of the sample, to assist in the complete removal of the sample from the equipment, and then to impart stability to the pressed X-ray analysis pellets. Furthermore, another problem to be solved by the present invention is to provide an internal X-ray standard so that quantitative analysis can be carried out reliably.

[0012] According to the invention, the grinding aid has the following composition:

[0013] A 15% to 35% of cellulose or a cellulose derivative,

[0014] B 40% to 60% of a natural resin,

[0015] C 0% to 5% of an auxiliary agent and a coating substance,

[0016] D 15% to 25% of a crystalline inorganic material as an X-ray standard.

[0017] The sum of components A, B, C and D is 100%. All values here and below are by weight percentage.

[0018] The cellulose derivative (A) is a chemical derivative of cellulose and is commonly used as a binder, for example, in pharmaceuticals and cosmetics. Cellulose derivatives can be prepared, for example, by methylation (methylcellulose), ethylation, hydroxypropylation, sulfonation, nitration (nitrocellulose), acetylation (cellulose acetate), oxidation, xanthation, crosslinking or graft copolymerization. There are many other modifications.

[0019] The natural resin (B) helps to stabilize the sample pellets, in particular through its viscosity.

[0020] The auxiliary agent and the coating substance (C) are used, for example, to protect the surface of the grinding aid tablets, to improve the flow properties, etc. Those skilled in the art are familiar with such coatings and coating processes. Since they are present in small proportions, these substances have little, ideally no, influence on the grinding process and the subsequent study of the ground material.

[0021] Therefore, this composition differs from conventional grinding aids known, for example, from DE 10 2020 201 877 B3 in terms of the addition of component D. However, generally speaking, the addition of crystalline inorganic materials necessarily requires a larger amount of grinding aid. The changed composition in turn leads to a change in the ratio, in particular, between component A and component B. If cellulose with a higher proportion disclosed in the prior art is used, the stability of the subsequently produced X-ray analysis pellets will be poorer, with a tendency to flake and break. Therefore, it is impossible to simply add crystalline inorganic materials without adjusting other formulations.

[0022] Therefore, it is also advantageous that crystalline inorganic materials have been added to the grinding aid. First, during subsequent use, the second batching step for separately adding an internal standard in the form of crystalline inorganic materials becomes redundant. Second, the ratio between other components of the grinding aid and the crystalline inorganic materials is thus also constant and is, for example, independent of batching or weighing errors. Therefore, the composition of other components of the grinding aid can be precisely adjusted according to a preset ratio between other components of the grinding aid and the crystalline inorganic materials.

[0023] In addition to X-ray diffraction, other studies can be carried out on the X-ray analysis pellets simultaneously or separately. For example, the composition can be studied by X-ray fluorescence. Infrared spectroscopy studies can also be optionally performed. This is another advantage of the X-ray analysis pellets: multiple non-destructive studies can be carried out on the same X-ray analysis pellet.

[0024] In another embodiment of the present invention, the ratio between component A and component B is from 25:75 to 35:65. This achieves the best strength while minimizing the fragility of the X-ray analysis pellets. At the same time, good self-cleaning of the mill is also achieved. This ratio is significantly different from that of the grinding aid without crystalline inorganic materials disclosed in, for example, DE 10 2020 201877B3. It has been proven that this ratio is optimal for the required high proportion of crystalline inorganic materials.

[0025] In another embodiment of the present invention, component D includes one or more substances from the following list: titanium dioxide (especially rutile), aluminum oxide (especially corundum), silicon dioxide (especially quartz), silicon carbide, silicon, hematite, and magnetite. Preferably, the selected substances are not components of the sample. Nowadays, typical application fields of automated X-ray diffraction for process control exist, for example, in the cement industry, steel production (especially in the slag field), aluminum production, or titanium dioxide production. Those skilled in the art will select suitable crystalline inorganic materials that have the least overlap with the peaks of the crystalline materials of the sample in the diffraction pattern.

[0026] In another embodiment of the present invention, the proportion of component A is between 28% and 32%, preferably 30%.

[0027] In another embodiment of the present invention, the natural resin of component B comprises the following components:

[0028] a 3% to 20% of 2,4-bis(1-phenylethyl)phenol,

[0029] b 1% to 12% of dehydroabietic acid,

[0030] c 1% to 8% of 1,2-bis(4-methoxyphenyl)-1-propene,

[0031] d 1% to 7% of ((1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthren-1-yl)-methanol,

[0032] e 1% to 7% of (1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthrene-1-carbaldehyde.

[0033] The sum of all components of the natural resin is 100%.

[0034] Of course, a complete analysis of all components is impossible, especially for substances with very low proportions, where significant fluctuations may occur. In addition, natural resins vary in different regions and different years, so an exact composition cannot be determined. For example, the fluctuations are caused by differences in the time, region, or climate of plant growth.

[0035] First, the natural resin is studied by 1D NMR and 2D NMR. Second, pyrolysis is carried out at 450 °C for 10 seconds, and then the product is passed through an HP-5ms gas chromatography column under the conditions that the temperature program is from 45 to 240 °C (heating rate 4 K / min), then from 240 to 300 °C (heating rate 40 K / min) and held for 15 minutes, with helium as the carrier gas at a flow rate of 1 ml / min and a split ratio of 50:1. The separated substances are identified by mass spectrometry, with a scanning range of 10 to 600 g / mol.

[0036] In another embodiment of the present invention, the natural resin of component B further comprises the following components:

[0037] f 0.5% to 6% of longifolene,

[0038] g 0.5% to 6% of abietic acid,

[0039] h 0.5% to 5% of caryophyllene oxide.

[0040] In another embodiment of the present invention, the natural resin of component B further comprises the following components:

[0041] i 2% to 25% of 9-ethyl-1,2,3,4,5,6,7,8-octahydroanthracene,

[0042] j 2% to 25% of N-(2-ethylphenyl)-benzeneacetamide.

[0043] In another embodiment of the present invention, the natural resin of component B comprises the following components:

[0044] b 3% to 8% of dehydroabietic acid.

[0045] In another embodiment of the present invention, the natural resin of component B comprises the following components:

[0046] d 2% to 5.5% of ((1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthren-1-yl)-methanol,

[0047] e 2% to 5.5% of (1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthrene-1-carbaldehyde.

[0048] In another embodiment of the present invention, the grinding aid has a PMMA coating. This makes the processing easier while reducing material losses during processing, such as losses caused by abrasion or breakage.

[0049] In another embodiment of the present invention, the grinding aid is a grinding aid tablet with a mass of 0.2 to 0.4 grams. It has been found that a conventional sample amount of about 10 grams (usually 5 to 20 grams) is suitable for precise dosing, while the number of required grinding aid tablets and accordingly the dosing workload are not too high.

[0050] On the other hand, the present invention relates to a method for quantitatively determining the phase fraction of a sample by X-ray diffraction. The method comprises the following steps:

[0051] a) Weigh the sample,

[0052] b) Add the grinding aid according to any one of the above claims,

[0053] c) Grind,

[0054] d) Press X-ray analysis pellets,

[0055] e) Record the X-ray diffraction pattern,

[0056] f) Perform Rietveld refinement on the X-ray diffraction pattern.

[0057] According to the present invention, the method has the following characteristics:

[0058] g) Determine the quantitative proportion of the amorphous phase in the sample by the ratio of the crystalline phase of the sample to the crystalline inorganic material of the grinding aid.

[0059] The sample weight in step a) can be exact or approximate. In the case of an exact sample weight, for example, it is specified as 10.00 g, and then a sample of this mass is accurately weighed. Alternatively, in the case of an approximate sample weight, an amount between about 10 g, for example, 8 g to 12 g, can be specified, and then the exact mass is measured when the sample is accurately provided, for example, 11.11 g. Both operations have their advantages and disadvantages.

[0060] When the grinding aid is in the form of grinding aid tablets, for example, the mass of each grinding aid tablet is 250 mg, the batching in step b) is particularly simple. For example, if 10 g of sample is specified, then, as an example, 4 tablets of the grinding aid with a total mass of 1 g will be added. The number 4 is relatively easy to count and batch, so the measurement error will be kept to a minimum.

[0061] Subsequently, grinding is carried out in step c), and X-ray analysis pellets are pressed in step d).

[0062] In step e), the X-ray analysis pellets produced in step d) are studied by X-ray diffraction, for example, using a CuK α source and a 2D area detector. Importantly, the X-ray diffraction pattern recorded in step e) has sufficient quality for the subsequent Rietveld refinement in step f).

[0063] The basis of the Rietveld refinement method is to specify the known phases and their known reflections (position and intensity ratio). Then, the parameters crucial for the study are changed, especially the ratio of the phases to each other, but also including, for example, the particle size (which may cause broadening of the reflections). For example, the latter can be particularly applicable to calculating the amorphous or pseudo-amorphous part. Then, a comparison is made between the simulated diffraction pattern and the diffraction pattern recorded in step e), and the optimal value is determined by the least squares method. This enables the ratio of different crystalline phases to be well determined, so that a quantitative study of the phases can be carried out. For example, in clinker, the ratio of alite (C 3 S) to belite (C 2 S) can be determined in this way.

[0064] Since the amorphous part is difficult to determine and is also superimposed by the amorphous components of the grinding aid, the amorphous part is quantitatively determined based on the ratio between the proportion of the crystalline sample and the proportion of the crystalline inorganic material used as the X-ray standard. This will be explained by the following examples.

[0065] For example, 10 g of a sample is treated with 1 g of a grinding aid, where the grinding aid contains 20% rutile, i.e., 0.2 g of rutile. Based on the pure and simplified assumption that the sample contains equal amounts of alite and belite, a completely crystalline sample would have a ratio of alite:belite:rutile of 25:25:1. If a ratio of 12.5:12.5:1 is obtained in the Rietveld analysis, then only half of the sample is likely to be crystalline. In this very simple hypothetical case, this means that the quantitative proportion of the amorphous phase in the sample would be 50%.

[0066] This is so simple because by using a grinding aid with an internal standard, it is possible to establish a clear relationship in a simple way even when considering the amorphous components of the grinding aid.

[0067] In another embodiment of the present invention, in step b), the batching is carried out in such a way that 0.07 to 0.12 g of the grinding aid is added per 1 g of the sample. Due to the additional crystalline inorganic material, this has a tendency towards higher batching, but this amount should not be too high to ensure that the X-ray analysis pellets still have good properties and that the superimposition in the X-ray diffraction pattern of the sample is not too severe.

[0068] In another embodiment of the present invention, rutile is used as the crystalline inorganic material for a cement sample or a cement clinker sample.

[0069] In another embodiment of the present invention, for a titanium dioxide sample, corundum, silicon, or silicon carbide is used as the crystalline inorganic material.

Claims

1. A grinding aid, which has the following composition: A 15% to 35% of cellulose or cellulose derivatives, B 40% to 60% of natural resin, C 0% to 5% of additives and coating substances, D 15% to 25% of crystalline inorganic materials as X-ray standards, wherein the sum of components A, B, C and D is 100%, and all values are in weight percentages.

2. The grinding aid according to claim 1, characterized in that the ratio between component A and component B is 25:75 to 35:

65.

3. The grinding aid according to any one of the preceding claims, characterized in that component D contains one or more substances from the following list: titanium dioxide especially rutile, alumina especially corundum, silica especially quartz, silicon carbide, silicon, hematite and magnetite.

4. The grinding aid according to any one of the preceding claims, characterized in that the proportion of component A is between 28% and 32%.

5. The grinding aid according to any one of the preceding claims, characterized in that the natural resin of component B contains the following components: a 3% to 20% of 2,4-bis(1-phenylethyl)phenol, b 1% to 12% of dehydroabietic acid, c 1% to 8% of 1,2-bis(4-methoxyphenyl)-1-propene, d 1% to 7% of ((1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthren-1-yl)-methanol, e 1% to 7% of (1R,4aR,bR,7R,10aR)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,6,7,8,9,10,10a-dodecahydrophenanthrene-1-carbaldehyde, wherein the sum of all components of the natural resin is 100%.

6. The grinding aid according to any one of the preceding claims, characterized in that the grinding aid has a PMMA coating.

7. The grinding aid according to any one of the preceding claims, characterized in that the grinding aid is a grinding aid tablet with a mass of 0.2 to 0.4 g.

8. A method for quantitatively determining the phase fraction of a sample by X-ray diffraction, the method comprising the following steps: a) Weigh the sample, b) Add the grinding aid according to any one of the preceding claims, c) Grind, d) Press X-ray analysis pellets, e) Record the X-ray diffraction pattern, f) Perform Rietveld refinement on the X-ray diffraction pattern, characterized in that g) Determine the quantitative proportion of the amorphous phase in the sample by the ratio of the crystalline phase of the sample to the crystalline inorganic material of the grinding aid.

9. The method according to claim 8, characterized in that in step b), the ingredients are prepared in such a way that 0.07 to 0.12 g of the grinding aid is added per 1 g of the sample.

10. The method according to claim 8 or 9, characterized in that for cement samples or cement clinker samples, rutile is used as the crystalline inorganic material.

11. The method according to any one of claims 8 to 10, characterized in that for the titanium dioxide sample, corundum, silicon or silicon carbide is used as the crystalline inorganic material.