PL245590B1 - Set of raw materials for the production of Portland clinker and its application - Google Patents

Abstract

The subject of the application is a raw material set for the production of Portland clinker, which contains 75 - 80% by weight of natural limestone, 7 - 17% by weight of sedimentary rock, 0.4 - 0.8% by weight of scale and 4 - 15% by weight of lime ash, in which set the contents of the main oxides are 12 - 15% by weight of SiO₂, 3 - 4.5% by weight of Al₂O₃, 1.6 - 2.2% by weight of Fe₂O₃, 42 - 44% by weight of CaO, characterized in that the natural limestone is lake chalk. The subject of the application is also the use of the set according to the application for the production of Portland cement.

Description

Description of the invention

The subject of the invention is a raw material composition for the production of Portland clinker and its use in the production of Portland cement.

Cement is a binding material obtained from mineral raw materials by burning and then grinding the obtained clinker. Cement production creates wide possibilities of using waste as substitutes for non-renewable, mineral mining raw materials. Such activity is in line with one of the basic principles of sustainable development, which assumes rational management of non-renewable resources and replacing them with substitutes.

Various clinkers for the production of hydraulic binders are known in the art. European patent EP1781579 discloses a sulfoaluminum clinker with a high belite content, a method of its production and its use for the preparation of hydraulic binders. This clinker comprises a belite-sulfaluminate having the following mineralogical composition: 5 to 25%, preferably 10 to 20%, of a calcium aluminoferrate phase with a composition corresponding to the general formula C2AXF(1-X), with X comprised between 0.2 and 0.8, 15 to 30%, preferably 20 to 30% of a calcium sulphoaluminate phase "yeelimite" (C4A3$), 40 to 75%, preferably 45 to 65% of belite (C2S), from 0.01 to 10% of one of a number of mineral phases selected from calcium sulphates, alkali metal sulphates, perovskite, calcium aluminates, ghelenite, free lime and periclase, and/or a glassy phase such as blast furnace slag or hydraulic glass.

Portland clinker is a hydraulic material, which is a semi-finished product in the cement production process. As is known from industrial practice and many textbooks, e.g. W. Brylicki et al., entitled Technology of building binding materials. Cement, WSiP, Warsaw 1983, M. Gawlicki et al., entitled Building materials. Basics of technology and research methods. Ed. J. Małolepszy, AGH Publishing House, Cracow 2008, W. Kurdowski, entitled Chemistry of cement and concrete, Polish Cement Publishing House, Cracow 2010, PWN Warsaw 2010, for the production of Portland clinker, raw materials are used that ensure obtaining a raw material allowance with appropriate relations between the contents of CaO, S1O2, Al2O3, and Fe2O3.

Raw material sets for the production of Portland clinker are also known in the art. Polish patent PL233349 discloses a raw material set for the production of Portland clinker containing natural limestones, marls, clay raw materials and waste raw materials of industrial origin, including fly ash and bottom slag from the combustion of hard coal, in which set the contents of the main oxides in % by weight are: 41-50 CaO, 12-16 S1O2, 2-5 Al2O3 and 1-3 Fe2Os, characterized in that it contains 1-100% by weight of carbide lime resulting from the production of acetylene from carbide, combined with an ash-slag mixture in a weight ratio of 2:1 to 4:1, wherein the carbide lime consists in % by weight of: 60-75 CaO, 1-5 S1O2, 0.5-3 Al2O3, 0-1 Fe2Os, 0-1 SO3, 0-1 MgO, 0-0.1 Na2O, 0-0.1 K2O, 0-0.2 T1O2, 0-0.2 P2O5, and ignition losses constitute 20-34% by weight, with the average grain size of carbide lime ranging from 20 to 60 μητ, while the ash-slag mixture contains in % by weight: 1-5 CaO, 42-52 S1O2, 16-24 Al2O3, 5-12 FesOa, 0-4 SO3, 0-2 MgO, 0-2 T1O2, and the average grain size of the ash-slag mixture ranging from 0.1 to 1.5 mm.

Polish patent PL229385 discloses a raw material set for the production of Portland clinker containing natural limestones, marls, clayey raw materials and waste raw materials of industrial origin, in which the contents of the main oxides in % by weight are 41-48 CaO, 12-16 S1O2, 2-5 Al2O3 and 1-3 Fe2Os, characterized in that the waste raw material is carbide lime resulting from the production of acetylene from carbide, contained in the raw material set in the amount of 1-35 by weight of: 60-75 CaO, 1-5 S1O2, 0.5-3 Al2O3, 0-1 Fe2Os, 0-1 SO3, 0-1 MgO, 0-0.1 Na2O, 0-0.1 K2O, 0-2 T1O2, 0-0.2 P2O5, and ignition losses are 20-34% by weight, while the average size of the post-carbide lime is in the range of 20 to 60 μητ

In the further description of the invention the following abbreviations will be used to designate the mineral components of cement and thus the type of binder produced (all values expressed in [wt.%]):

Lime saturation module according to Kind, MN, expressed by the formula:

CaO - (CaO _w + 1.65 A/ ₂ Æ? ₃ + 0.35 Fe ₂ O ₃ + 0.7 SiO ₂ ) ^Mn= 2.8 (Si0 ₂ - SiO _2w )

The value of the lime saturation module according to Kind should be within the range (0.84- 0.98).

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The hydraulic module, expressed by the formula:

CaO M _h =—-----------S1O2 + 4/2^3 Fe?2^3

The value of the hydraulic module should be within the range (2.1 4- 3.5).

The aluminum modulus, MG, is given by:

The value of the aluminum modulus should be within the range (1.0 3- 3.0).

The silicate module MK, expressed by the formula:

5ίί?2 j4Z ₂ O3 + Fe ₂ O ₃

The value of the silicate module should be within the range (1.7 3- 3.5).

Lime Saturation Module LSF, Lime Saturation Factor - defining the chemical composition of the raw material set ensuring the highest possible (optimum) bound CaO in the burnt clinker expressed by the formula:

CaO lsf =_________________________

2.8StO ₂ + 1.18Λ/ ₂ Ο ₃ + 0.65Fe ₂ O ₃

The value of the lime saturation module, usually expressed as a percentage, should be within the range (95 3-100)%.

The conversion of chemical composition into mineralogical composition can be done using Bogue's formulas - which state that the chemical formulas of oxides and minerals are identical to their contents:

C3S = 4.07 C - 7.6 S - 1.43 F - 6.72 A

C2S = 8.6 S + 1.07 F + 5 A - 3 C

C3A = 2.65A - 1.69F

C4AF = 3.04F

Where:

F ~ Fe ₂ O ₃ ; A — Al ₂ O ₃ ; S = SiO ₂ — SiO ₂ insoluble

C = CaO - CaO _woine - 0.7 SO ₃

Mineral composition according to Bogue's method:

C ₃ S —alite (tricalcium silicate),

C ₂ S - belite (dicalcium silicate),

C ₃ A — celite (tricalcium aluminate)

C ₄ AF —brownmillerite (dicalcium aluminate)

The use of large-scale extraction of overburden minerals accompanying lignite mining, including lake chalk (whose properties correspond to raw materials with a high calcium carbonate content), in the large-scale process, is an opportunity to manage many millions of tons of mining by-products, i.e. lake chalk, sand, clay materials, which until now have mostly been mixed with earth and rock masses as overburden and deprived of the usable features of the raw material. The combination of extraction and processing of minerals accompanying coal mining means a departure from the linear economy (which absorbs a huge mass of non-renewable raw materials and produces significant amounts of waste) and is a way to meet the widely postulated principles of the Circular Economy.

Therefore, the aim of the invention was to develop raw material sets for the production of Portland clinker, which would make it possible to develop deposits of lake chalk - an overburden mineral accompanying the mining of brown coal - and to obtain clinker and Portland cement with the desired properties.

The raw material composition for producing Portland clinker according to the invention comprises 75-80 wt.% of natural limestone, 7-17 wt.% of sedimentary rock, 0.4-0.8 wt.% of scale and 4-15 wt.% of limestone ash, in which composition the contents of the main oxides are 12-15 wt.% SiO2, 3-4.5 wt.% Al2O3, 1.6-2.2 wt.% Fe2O3, 42-44 wt.% CaO, characterized in that the natural limestone is lake chalk.

Preferably the sedimentary rock is selected from the group consisting of sand and clay.

Preferably, the set according to the invention contains 78.47 wt.% of lake chalk, 10.06 wt.% of sand, 0.49 wt.% of scale and 10.98 wt.% of lime ash, in which set the contents of the main oxides are 14.07 wt.% SiO2, 3.29 wt.% Al2O3, 1.73 wt.% Fe2O3, 43.45 wt.% CaO.

Alternatively, preferably, the set according to the invention contains 77.15 wt.% of lake chalk, 8.43 wt.% of sand, 0.54 wt.% of scale and 13.88 wt.% of lime ash, in which set the contents of the main oxides are 13.39 wt.% of SO2, 4.06 wt.% of Al2O3, 2.03 wt.% of Fe2O3, 43.39 wt.% of CaO.

Alternatively, preferably, the set according to the invention contains 78.60 wt.% of lake chalk, 15.57 wt.% of clay, 0.70 wt.% of scale and 5.14 wt.% of lime ash, in which set the contents of the main oxides are 13.12 wt.% of SO2, 3.97 wt.% of Al2O3, 1.99 wt.% of Fe2O3, 42.51 wt.% of CaO.

The subject of the invention is also the use of the kit according to the invention for the production of Portland cement.

Portland clinker is a manufactured semi-finished product to which a setting time regulator is added and then ground to obtain Portland cement.

Depending on the assumed requirements, Portland cement should comply with the standard values described in PN-EN 197-1:2012 "Cement - Part 1: Composition, requirements and conformity criteria for common cements".

The main advantage of the invention is that the Portland cement produced using the raw material sets according to the invention is characterized by the features of a typical CEM I with a rapidly increasing early strength, high hydration heat and short setting time. The minimum standard compressive strength of the obtained mortars, after 28 days of hardening, is 42.5 MPa. The obtained Portland cement meets the assumed effect, obtained entirely from overlay and waste materials, in accordance with the circular economy model, meeting the standard requirements and corresponding to the cement class CEM I 42.5R.

Description of drawings

Fig. 1 shows diffractometers of chemical composition of clinker raw materials. Fig. 1A shows diffractogram of lake chalk. The main phases identified in the sample are calcite and quartz. Fig. 1B shows diffractogram of sand. The main phase identified in the sample is quartz. The other phases were identified in small amounts (very low line reflection intensities). Fig. 1C shows diffractogram of clay. The main phases identified in the sample are quartz, kaolinite and illite minerals. Calcite was identified in small amounts. Fig. 1D shows diffractogram of scale. The main phases identified in the sample are magnetite, wustite and hematite. Fig. 1E shows diffractogram of limestone ash. The main phases identified in the tested sample are quartz, ghelenite, anhydrite, albite and hematite. The other phases were identified in small amounts (very low line reflection intensities). Fig. 1F shows the diffraction pattern of gypsum. The main phase identified in the tested sample is gypsum. Calcite and quartz occur in very small amounts (very low intensities of line reflections).

Fig. 2 shows exemplary diffraction patterns for each fired set I-III obtained during the firing process. Fig. 2A shows the diffraction pattern of Set I. The main phases identified in the tested sample are alite (Calcium silicate-red), belite (dicalcium silicate-blue), tricalcium aluminate (tricalcium aluminate-green) and brownmillerite (brownmillerite-grey). In a smaller amount (very low line reflection intensities) there is free lime CaOw, the amount of which determined by the glycol method is 1.5%. Fig. 2B shows the diffraction pattern of Set II. The main phases identified in the tested sample are alite, belite, tricalcium aluminate and brownmillerite. In a smaller amount there is free lime CaOw, the amount of which determined by the glycol method is 1.4%. Fig. 2C shows the diffraction pattern of Set III. The main phases identified in the tested sample are alite, belite, aluminate.

PL 245590 Β1 tricalcium and brownmillerite. Free calcium CaOw occurs in smaller amounts, the amount of which determined by the glycol method is 1.7%.

Fig. 3 shows diffraction patterns from measurements of the phase composition during firing of raw material sets for each fired set I-III. Fig. 3A shows the diffraction pattern of Set I. The main phases identified in the tested sample are alite, belite, tricalcium aluminate and brownmillerite. In a smaller amount (very low line reflection intensities) there is free lime CaOw (1.6%). Fig. 3B shows the diffraction pattern of Set II. The main phases identified in the tested sample are alite, belite, tricalcium aluminate and brownmillerite. In a smaller amount (very low line reflection intensities) there is free lime CaOw (1.3%). Fig. 3C shows the diffraction pattern of Set III. The main phases identified in the tested sample are alite, belite, tricalcium aluminate and brownmillerite. Free calcium CaOw is present in smaller amounts (very low intensities of line reflections), the amount of which determined by the glycol method is 1.8%.

Examples of execution

Example 1 - Chemical and phase composition of raw materials

The results of the chemical composition of the raw materials are presented in Table 1. The chemical composition of the raw materials was tested using wavelength dispersive X-ray fluorescence spectrometry (XRF). The results of the phase composition of the raw materials were tested using X-ray diffraction (XRD) and are presented in Figures 1A-1F. All raw materials were dried to a constant mass, crushed and homogenized before XRF and XRD analyses. Flomogenization and grinding of the raw materials was carried out to a residue of maximum 5% on a 0.090 mm sieve.

Table 1. Chemical composition of raw materials

Ingredient Raw material description Lake chalk Sand Il Zendra Lime ash Plaster % of mass Loss on ignition 45.15 0.50 7.71 + 4.31 4.79 21.43 SiOj 1.48 94.72 66,62 0.42 30.71 1.13 AliOa 0.08 1.98 16.02 0.07 27.58 0.15 Fe;Oh 0.16 1.30 4.56 98.01 9,11 0.17 CaO 52.29 0.19 1.85 0.25 21.82 33.61 MgO 0.14 0.06 1.33 0.04 1.07 0.04 Sat ₃ 0.57 0.00 0.06 0.02 3.44 43,42 K ₂ O 0.02 0.88 0.80 0.00 0.16 0.01 On _with O 0.00 0.27 0.03 0.04 0.06 0.00 P2O5 0.05 0.03 0.04 0.02 0.43 0.04 TiO _with 0.01 0.05 0.90 0.01 0.70 0.00 Mn ₂ O ₃ 0.04 0.01 0.06 0.90 0.07 0.00 Wed 0.01 0.00 0.01 0.00 0.06 0.01 ZnO 0.00 0.00 0.01 0.00 0.03 0.00

Example 2 - Development of raw material mixture compositions

Based on the chemical composition of the raw materials from Example 1, the compositions of three sets of raw materials for the production of Portland clinker were developed and calculated, namely:

Set I consisting of lake chalk, sand, scale and limestone ash with the percentage of components of 78.47 wt.%, 10.06 wt.%, 0.49 wt.% and 10.98 wt.%, respectively.

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Set II consisting of lake chalk, sand, scale and limestone ash with the percentage of components of 77.15 wt.%, 8.43 wt.%, 0.54 wt.% and 13.88 wt.%, respectively.

Set III consisting of lake chalk, clay, scale and limestone ash with the percentage of components of 78.60 wt.%, 15.57 wt.%, 0.70 wt.% and 5.14 wt.%, respectively.

For Sets I to III, constant parameters for Portland clinker (MN, MK, MG) were calculated, i.e. typical parameters for industrial clinkers. The results of calculations of the composition of raw material sets are presented in Tables 2-4. These tables present the shares of raw materials for individual raw material sets and the theoretical chemical and phase compositions of Portland clinkers. The phase composition of the clinkers assumed a share of 1.5% of free lime CaOw, which for industrial Portland clinkers most often ranges from 1 to 2, sometimes reaching even 3%.

Table 2. Set I. Clinker with a C3A content of 9%

Assumptions and calculations MN 0.95 MK 2.80 MG 1.90 Chemical composition of raw material, % by weight = Raw material: Lake chalk Sand Zendra Lime ash Loss on ignition 45.15 0.50 4.79 SiO ₂ 1.48 94.72 0.42 30.71 and _{with about 3} 0.08 1.98 0.07 27.58 _{Fe2O3 ​} 0.16 1.30 98.01 9,11 CaO 52.29 0.19 0.25 21.82 MgO 0.14 0.06 0.04 1.07 Sat ₃ 0.57 0.02 3.44 Na,0 0.27 0.04 0.06 K ₂ O 0.02 0.88 0.16 Rest 0.11 0.10 1.15 1.26 Calculated proportions Lake chalk 78.47 Sand 10.06 % of mass Zendra 0.49 Lime ash 10.98 100¾ mixture Practical clinker Loss on ignition 36.01 - SiO ₂ 14.07 21.98 AIA 3.29 5.14 _{Fe2O3 ​} 1.73 2.71 CaO 43.45 67.90 MgO 0.23 0.37 SOj 0.83 1.29 On ₂ O 0.03 0.05 K ₂ O 0.12 0.19 Rest 0.24 0.38 CaO“ 1.50 j MODULES CHARACTERIZING CLINKER MN MK MG LSF 0.91 2.80 1.90 98 POTENTIAL PHASE COMPOSITION OF CLINKER ACCORDING TO BOGUE %CjS %C ₂ S %CjA %c ₄ af %CŚ 61.1 16.9 9.0 8.2 2,2

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Table 3. Set II. Clinker with 11% CsA content. Recipe for the maximum amount of lime ash in the raw material set (for sand in the set).

Assumptions and calculations MN 0.96 MK 2.20 MG 2.00 Chemical composition of raw material, % by weight Raw material: Lake chalk Sand Zendra Lime ash Loss on ignition 45.15 0.50 4.79 SiO ₂ 1.48 94.72 0.42 30.71 AI ₃ O ₃ 0.08 1.98 0.07 27.58 Pe ₂ O ₃ 0.16 1.30 98.01 9,11 CaO 52.29 0.19 0.25 21.82 MgO 0.14 0.06 0.04 1.07 SO, 0.57 0.02 3.44 On ₂ O 0.27 0.04 0.06 K ₂ O 0.02 0.88 0.16 Rest 0.11 0.10 1.15 1.26 Calculated proportions Lake chalk 77.15 Sand 8.43 % of mass Zendra 0.54 Lime ash 13.88 100% mixture Practical clinker Loss on ignition 35.54 SiO ₂ 13.39 20.77 AI ₂ Oh 4.06 6.29 Pe ₂ O ₃ 2.03 3.15 CaO 43.39 67.31 MgO 0.26 0.41 Sat ₃ 0.92 1.42 On ₂ O 0.03 0.05 K ₂ O 0.11 0.17 Rest 0.27 0.43 1.50 MODULES CHARACTERIZING CLINKER MN MK MG LSF 0.92 2.20 2.00 100 POTENTIAL PHASE COMPOSITION OF CLINKER ACCORDING TO BOGUF %C ₃ S %C ₂ S %C ₃ A %C,AF %CŚ 59.2 14.9 11.3 9.6 2.4

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Table 4. Set III. Clinker with 11% CsA content. Recipe for the maximum amount of lime ash in the raw material set (for clay in the set).

Assumptions Obliżeriia.................. MN 0.96 MK 2.20 MG 2.00 The chemical composition of the raw material, {<> mass Raw material: Lake chalk I Zendra Lime ash Loss on ignition 45.15 7.71 4.79 SiO ₂ 1.48 66,62 0.42 30.71 ΑΙΛ 0.08 16.02 0.07 27.58 Fe ₂ 0 ₃ 0.16 4.56 98.01 9,11 CaO 52.29 1.85 0.25 21.82 MgO 0.14 1.33 0.04 1.07 SOj 0.57 0.06 0.02 3.44 Na,0 0.03 0.04 0.05 K ₂ O 0.02 0.80 0.15 Rest 0.11 1.02 1.15 1.26 Calculated proportions Lake chalk 78.60 % of mass I 15.57 Zendra 0.70 Lime ash 5.14 100% mixture Practical clinker Loss on ignition 36.93 SiOj 13,12 20.80 ai ₂ o ₃ 3.97 6.30 _{Fe2O3 ​} 1.99 3.15 CaO 42.51 67.40 MgO 0.37 0.59 SOj 0.63 1.01 On ₂ O 0.01 0.01 K ₂ O 0.15 0.24 Rest 0.32 0.50 CaO“ 1.50 MODULES CHARACTERIZING CLINKER MN MK MG LSF 0.92 2.20 2.00 100 POTENTIAL PHASE COMPOSITION OF CLINKER ACCORDING TO GOD E'A ’ %c,s %C ₂ S %C,A %C,AF %CŚ 60.5 14.0 11.4 9.6 1.7

Example 3 - Making sets of raw materials

Each kit was prepared by accurately weighing the ingredients and homogenizing them according to the calculated proportions.

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In order to prepare sets for firing, individual raw materials were granulated, dried and homogenized, preparing about 500 kg of raw material sample. Homogenization and grinding of raw materials was carried out to a residue of maximum 5% on a 0.090 mm sieve.

For Set I consisting of lake chalk, sand, scale and limestone ash with the percentage of components of 78.47% by weight, 10.06% by weight, 0.49% by weight and 10.98% by weight, respectively, approximately 400 kg of lake chalk, approximately 50 kg of sand, approximately 2 kg of scale and approximately 50 kg of limestone ash were weighed.

For Set II consisting of lake chalk, sand, scale and limestone ash with the percentage of components of 77.15% by weight, 8.43% by weight, 0.54% by weight and 13.88% by weight, respectively, approximately 400 kg of lake chalk, approximately 30 kg of sand, approximately 2 kg of scale and approximately 70 kg of limestone ash were weighed.

For Set III consisting of lake chalk, clay, scale and limestone ash with the percentage of components of 78.60% by weight, 15.57% by weight, 0.70% by weight and 5.14% by weight, respectively, approximately 400 kg of lake chalk, approximately 80 kg of clay, approximately 3 kg of scale and approximately 20 kg of limestone ash were weighed.

After homogenization, the chemical composition of the sets was tested to confirm the correctness of the weighed share of components in the sets, and thus, in the event of any error, to correct the composition of the set at this stage, without its expensive firing in the kiln. The chemical compositions of the sets are presented in Table 5. Comparing the results of the chemical composition of the sets given in Table 5 with the results given in Tables 2-4, it was found that the sets were correctly prepared and could be fired in the rotary kiln.

Table 5 - Chemical compositions of raw material sets

Ingredient Set designation Set I Set II Set III % of mass Loss on ignition 35.86 35.47 36.85 SiO ₂ 14,11 13.58 13.45 AI;O ₃ 3.28 4.02 3.64 _{Fe2O3 ​} 1.82 2.06 1.88 Ca O 43.02 43.10 42.55 MgO 0.51 0.55 0.45 Sat ₃ 0.72 0.73 0.55 K ₂ O 0.12 0.12 0.14 On ₂ O 0.03 0.02 0.02 PzO ₅ 0.11 0.11 0.07 TiO ₂ 0.07 0.09 0.10 Mn ₂ O ₃ 0.05 0.05 0.05 Wed 0.01 0.01 0.01 ZnO 0.00 0.00 0.00

Example 4 - Burning of raw material sets

The sets were granulated on a plate granulometer with a small amount of water as a so-called bonding medium. After granulation, the sets were dried in a dryer at 120°C. 500-550 kg of granulated raw material sets were prepared for firing/production of Portland clinkers.

The granulated sets were fired in a semi-industrial rotary kiln with the following parameters:

• Furnace type: rotary furnace, without external heat exchanger with rotary cooler.

• Furnace dimensions: 1.25 x 16 m, • Capacity: 400-600 kg/h of material (400 kg dosed per hour), • Furnace speed: 1.5 rpm,

PL 245590 Β1 • Material residence time in the kiln 140 min, • Material residence time in the sintering zone 40 min, • Fuel: heating oil, • Firing temperature: 1450-1480°C in the sintering zone, i.e. approx. 2 m from the clinker outlet from the kiln.

The control of the firing process was carried out based on the analysis of the results of the phase composition tests of samples taken during the firing of a given set and the determination of the free lime content in them using the glycol method. Due to the content of the main component (chalk), the sets were fired in the following order: Set I, Set II, Set III.

Example diffraction patterns for each fired set, obtained during the firing process, are shown in Figs. 2A-2C.

The results of the diffraction analysis from the measurements of the phase composition during the firing of raw material batches and the results of the tests of the free lime content confirm and prove the correct course of clinker synthesis in the rotary kiln at the Glass and Building Materials Department in Kraków (Łukasiewicz Research Network - Institute of Ceramics and Building Materials.

From the fired raw material batches of 500-550 kg, approximately 200 kg of "clean" clinker was obtained. Such amounts of clinkers result from the fact that during a 30-minute break in the dosing of the next batch to the kiln (e.g. batch II after batch I), part of the first batch remained in the kiln and mixed with the next batch. Therefore, this mixed clinker was rejected and then the good clinker was separated/taken. The clinkers obtained after approximately 200 kg were accurately averaged before the next tests. The results of the chemical analyses of the clinkers are presented in Table 6. The diffractograms of the clinkers are presented in Figures 3A-3C.

Table 6. Chemical compositions of Portland clinkers after firing in a rotary kiln

Ingredient Clinker marking Set 1 Set II Set III % of mass Loss on ignition 0.08 0.07 0.09 SiO ₂ 22.29 21.25 21.80 Al2O3 6.01 6.64 5.90 _{Fe2O3 ​} 3.01 3.26 3.05 Ca O 67.10 67.41 67.94 MgO 0.91 0.72 0.73 SO ₃ 0.18 0.20 0.07 K ₂ O 0.03 0.03 0.02 On ₂ O 0.00 0.00 0.00 P2O5 0.16 0.16 0.12 TiO ₂ 0.15 0.17 0.20 Mn ₂ O ₃ 0.08 0.08 0.07 Wed 0.03 0.03 0.03 ZnO 0.00 0.00 0.00

Comparing the results of the chemical composition of the sets presented in Table 6 with the results presented in Tables 2-4 and analysing the results of the phase composition tests (Fig. 3A-3B) it should be stated that the clinkers were correctly fired in the OSiMB semi-industrial kiln in Kraków.

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Example 5 - Production and testing of cements from burnt clinkers

The obtained clinkers were shot-blasted (preliminary process before grinding) and then ground in a ball mill to a surface of 3800-3900 cm ² /g, with the addition of 6% gypsum (with characteristics/composition given in Table 1). The Portland cements CEM I obtained in this way were subjected to tests of basic standard properties according to PN-EN 197-1. The results of tests of basic standard properties of cements are given in Tables 7 and 8.

Table 7. Physical properties of cements made from Portland clinkers fired in a rotary kiln.

Sample description Specific surface area [cm7g] Density [g/cm ³ ] Water demand [%] Setting time [min] Flow [cm] beginning end Set I 3900 3.16 264 150 195 19.5 Set II 3900 3.15 26.0 145 185 19.0 Set III 3800 3.15 26.0 160 200 20.5

Table 8. Physical (mechanical) properties of cements made from Portland clinkers fired in a rotary kiln

Sample description Specific surface area [cm ² /g] Bending strength after days, [MPa] Compressive strength after days, [MPa] Zdni 7days Z8days Days 7days Z8days Set 1 3900 3.9 6.2 7.1 22.1 38.6 53.2 Set II 3900 4.1 6.3 7.2 23.3 39.3 54.6 Set III 3800 4.3 6,7 7.6 27.6 41.9 56.1

Claims (6)

1. A raw material set for the production of Portland clinker, containing 75-80 wt.% of natural limestone, 7-17 wt.% of sedimentary rock, 0.4-0.8 wt.% of scale and 4-15 wt.% of limestone ash, in which the contents of the main oxides are 12-15 wt.% S1O2, 3-4.5 wt.% Al2O3, 1.6-2.2 wt.% FezOs, 42-44 wt.% CaO, characterized in that the natural limestone is lake chalk. 2. The set according to claim 1, characterized in that the sedimentary rock is selected from the group consisting of sand and clay. 3. A set according to claim 1 or 2, characterized in that it contains 78.47 wt.% of lake chalk, 10.06 wt.% of sand, 0.49 wt.% of scale and 10.98 wt.% of lime ash, in which the contents of the main oxides are 14.07 wt.% S1O2, 3.29 wt.% Al2O3, 1.73 wt.% Fe2O3, 43.45 wt.% CaO. 4. A set according to claim 1 or 2, characterized in that it contains 77.15 wt.% of lake chalk, 8.43 wt.% of sand, 0.54 wt.% of scale and 13.88 wt.% of lime ash, in which the contents of the main oxides are 13.39 wt.% of S1O2, 4.06 wt.% of Al2O3, 2.03 wt.% of Fe2Os, 43.39 wt.% of CaO. PL 245590 Β1 5. A set according to claim 1 or 2, characterized in that it contains 78.60 wt.% of lake chalk, 15.57 wt.% of clay, 0.70 wt.% of scale and 5.14 wt.% of lime ash, in which the contents of the main oxides are 13.12 wt.% of S1O2, 3.97 wt.% of Al2O3, 1.99 wt.% of Fe2O3, 42.51 wt.% of CaO. 6. Use of a kit according to any one of claims 1 to 5 for the production of Portland cement.