Method for producing magnesium silicate-belite-calcium aluminate cement

Abstract

The present invention relates to a method for producing a binder comprising the following steps: a) providing a starting material, from raw materials, that has a molar (Ca+Mg)/(Si+Al+Fe) ratio from 1 to 3.5, a molar ratio Ca/Mg from 0.1 to 100, and a molar Al/Si ratio from 100 to 0.1, wherein constituents that are inert during the hydrothermal treatment in an autoclave are not taken into account for determination of the ratios, b) mixing the raw materials, c) hydrothermal treating of the starting material mixture produced in step b) in an autoclave at a temperature from 100 to 300 C. and a residence time from 0.1 to 24 h, wherein the water/solids ratio is 0.1 to 100, d) tempering the intermediate product obtained in step c) at 350 to 600 C., wherein the heating rate is 10-6000 C./min and the residence time is 0.01-600 min.

Claims

1. A method for producing a binder comprising the following steps: a) providing a starting material from one or more raw materials that contain CaO, MgO, SiO.sub.2, Al.sub.2O.sub.3 and Fe.sub.2O.sub.3 or other compounds of these elements, wherein the starting material has a molar (Ca+Mg)/(Si+Al+Fe) ratio from 1 to 3.5, a molar Ca/Mg ratio from 0.1 to 100, and a molar Al/Si ratio from 100 to 0.1, wherein constituents that are inert during a hydrothermal treatment in an autoclave are not taken into account for determination of the ratios, b) mixing the raw materials to form a starting material mixture, c) hydrothermal treating of the starting material mixture produced in step b) in an autoclave at a temperature from 100 to 300 C. and a residence time from 0.1 to 24 h, wherein the water/solids ratio is 0.1 to 100, to provide an intermediate product, and d) tempering the intermediate product obtained in step c) at 350 to 600 C., wherein the heating rate is 10-6000 C./min and the residence time is 0.01-600 min.

2. The method according to claim 1, wherein 0.1 to 30% by weight additional elements and/or oxides are added during the mixing b) and/or in the following steps.

3. The method according to claim 1, wherein the raw materials are selected from CaO, Ca(OH).sub.2, Ca and Mg (hydroxide)carbonate(hydrates), MgO, Mg(OH).sub.2, slags, granulated blast furnace slags, ashes, Portland cement clinkers, Portland cement, processed hardened cement pastes, calcium sulfoaluminate belite cement, calcium aluminate cement, glass powder, sodium silicate and natural stone dusts in suitable mixture.

4. The method according to claim 1, wherein an additional burning process at temperatures from 350 to 1400 is performed between the mixing of the starting materials b) and the hydrothermal treatment c).

5. The method according to claim 1, wherein a holding time of 1-120 min during heating at a temperature of 350-600 C. is performed for dewatering in step d).

6. The method according to claim 2, wherein sodium, potassium, boron, sulphur, chlorine, nitrogen, carbon or phosphorous or combinations thereof are used as additional elements.

7. The method according to claim 2, wherein alkaline and/or alkaline earth salts and/or hydroxides are used as a source for the additional elements and/or oxides.

8. The method according to claim 7, wherein the alkaline and/or alkaline earth salts and/or hydroxides are selected from the group consisting of CaSO.sub.4.2H.sub.2O, CaSO.sub.4. H.sub.2O, CaSO.sub.4, CaHPO.sub.2.2H.sub.2O, Ca.sub.3P.sub.2O.sub.8, NaOH, KOH, Na.sub.2CO.sub.3, NaHCO.sub.3, K.sub.2CO.sub.3, MgCO.sub.3, MgSO.sub.4, Na.sub.2Al.sub.2O.sub.4, Na.sub.3PO.sub.4, K.sub.3PO.sub.4, Na.sub.2[B.sub.4O.sub.5(OH).sub.4].8H.sub.2O, CaCl.sub.2, Ca(NO.sub.3).sub.2, MgCl.sub.2, Mg(NO.sub.3).sub.2, AlCl.sub.3, Al(NO.sub.3).sub.3, FeCl.sub.3, Fe(NO.sub.3).sub.3Ca(CH.sub.3COO).sub.2, Mg(CH.sub.3COO).sub.2, Al(CH.sub.3COO).sub.3, Ca(HCOO).sub.2, Mg(HCOO).sub.2, Al(HCOO).sub.3, and mixtures thereof.

9. The method according to claim 1, wherein, before the hydrothermal treatment c), from 0.01 to 30% by weight seeds containing calcium silicate hydrates, Portland clinker, granulated blast furnace slag, magnesium silicates, calcium sulphate aluminate (belite) cement, sodium silicate and/or glass powder are added to the mixture.

10. The method according to claim 4, wherein the additional burning process is performed at a temperature from 750 to 1100 C.

11. The method according to claim 2, wherein sodium, potassium, boron, sulphur, chlorine, nitrogen, carbon, or phosphorous, or combinations thereof are used as additional elements.

12. The method according to claim 2, wherein a holding time of 1-120 min during heating at a temperature of 350-600 C. is performed for dewatering in step d).

13. The method according to claim 11, wherein a holding time of 1-120 min during heating at a temperature of 350-600 C. is performed for dewatering in step d).

14. The method according to claim 1, wherein the molar ratio of Ca/Mg is from 0.1 to 5 and the molar ratio (Ca+Mg)/(Si+Al+Fe) is from 1.5 to 3.5.

15. The method according to claim 14, wherein 0.1 to 30% by weight additional elements and/or oxides are added during the mixing b) and/or in the following steps.

16. The method according to claim 15, wherein sodium, potassium, boron, sulphur, chlorine, nitrogen, carbon, or phosphorous or combinations thereof are used as additional elements.

17. The method according to claim 14, wherein a holding time of 1-120 min during heating at a temperature of 350-600 C. is performed for dewatering in step d).

18. The method according to claim 16, wherein a holding time of 1-120 min during heating at a temperature of 350-600 C. is performed for dewatering in step d).

19. A binder obtained by a method according to claim 1.

20. The binder according to claim 19, wherein the binder comprises the following components: 1-95% by weight reactive calcium aluminates, 1-80% by weight magnesium (calcium, aluminium, iron) silicates, in the form of crystalline, ill crystalline or amorphous phases, which may contain foreign ions, 1-80% by weight C.sub.2S polymorphs, in the form of crystalline, ill crystalline or amorphous phases, 1-80% by weight calcium aluminate silicates, in the form of crystalline, ill crystalline or amorphous phases, 1-80% by weight calcium magnesium aluminate silicates, in the form of crystalline, ill crystalline or amorphous phases, up to 30% by weight traces and minor components, and 0-30% by weight hydrates from the hydrothermal treatment.

21. A binder obtained by a method according to claim 14.

22. The binder according to claim 21, wherein the binder comprises at least one calcium silicate, calcium aluminate, calcium aluminium silicate, magnesium (calcium, aluminium, iron) silicate or calcium magnesium silicate and at least one X-ray amorphous phase, wherein the sum of calcium silicates, calcium aluminates, calcium aluminium silicates, magnesium (calcium, aluminium, iron) silicates and calcium magnesium silicates is at least 30% by weight.

23. The binder according to claim 22, wherein the binder comprises the following components: 1-95% by weight reactive calcium aluminates, 1-80% by weight magnesium (calcium, aluminium, iron) silicates, in the form of crystalline, ill crystalline or amorphous phases, which may contain foreign ions, 1-80% by weight C.sub.2S polymorphs, in the form of crystalline, ill crystalline or amorphous phases, 1-80% by weight calcium aluminate silicates, in the form of crystalline, ill crystalline or amorphous phases, 1-80% by weight calcium magnesium aluminate silicates, in the form of crystalline, ill crystalline or amorphous phases, up to 30% by weight traces and minor components, and 0-30% by weight hydrates from the hydrothermal treatment.

24. The binder according to claim 21, wherein the BET surface area of the binder ranges from 1 to 30 m.sup.2/g.

25. The binder according to claim 21, wherein a chemically bonded water content is at most 20% by weight.

26. A concrete, mortar, or plaster comprising a binder according to claim 21.

27. The binder according to claim 23, wherein the traces and minor components are C.sub.5A.sub.3, CA, calcium oxide, aluminas, quartz and/or limestone, CaO, calcium sulphate, MgCO.sub.3, Mg(OH).sub.2, FeO, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, iron silicates, amorphous iron-containing phases, or mixtures thereof.

28. The binder according to claim 23, wherein the reactive calcium aluminates are in the form of crystalline C.sub.12A.sub.7, or ill crystalline or amorphous aluminate phases.

29. The binder according to claim 27, wherein a chemically bonded water content is at most 10% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the measured heat flow of the products from Example 1 reacted with a water/solids ratio of 0.5 in a calorimeter.

(2) FIG. 2 shows the cumulative heat flow of the products from Example 1.

(3) FIG. 3 shows the measured heat flow of the products from Example 2 reacted with a water/solids ratio of 0.5 in a calorimeter.

(4) FIG. 4 shows the cumulative heat flow of the products from Example 2.

EXAMPLE 1

(5) Starting material mixtures, one containing 37.8% Portlandite, 29% brucite and 32.6% silica fume and, for comparison, a second one containing 63.7% CaO and 36.3% silica fume were produced from the raw materials listed in Table 1.

(6) TABLE-US-00001 TABLE 1 Raw material Portlandite CaO Brucite Silica fume Loss on ignition at 24.33 31.04 2.73% 1050 C. SiO.sub.2 94.05% Al.sub.2O.sub.3 0.61% TiO.sub.2 0 MnO 0 Fe.sub.2O.sub.3 0.40% CaO 75.67% 100% 0.31% MgO 68.96% 0.59% K.sub.2O 1.12% Na.sub.2O 0.21% SO.sub.3 0 P.sub.2O.sub.5 0.04%

(7) The two starting material mixtures were each mixed with water at a water/solids ratio of 10, and were treated for 16 hours at 185 C. in an autoclave. The intermediate products were tempered for 1 hour at 500 C. The obtained products were reacted in a calorimeter to check the hydraulic reactivity with a water/solids ratio of 0.5. The obtained heat flows and cumulative heat flows are shown in FIGS. 1 and 2. It can be seen that the product according to the invention with the magnesium content comprises more reactive constituents.

EXAMPLE 2

(8) A starting material mixture containing 27.75% Portlandite and 72.24% granulated blast furnace slag was produced from the raw materials listed in Table 2 and was reacted in accordance with Example 1 to form a binder. The product was reacted in a calorimeter to check the hydraulic reactivity with a water/solids ratio of 0.5. For comparison, the same materials were additionally reacted in a calorimeter with a water/solids ratio of 0.5 without the hydrothermal treatment and tempering. The measured heat flows and cumulative heat flows are shown in FIGS. 3 and 4.

(9) TABLE-US-00002 TABLE 2 Granulated blast furnace Raw material Portlandite slag Loss on ignition at 24.33 1.37% 1050 C. SiO.sub.2 35.84% Al.sub.2O.sub.3 11.06% TiO.sub.2 0.99% MnO 0.34% Fe.sub.2O.sub.3 0.44% CaO 75.67% 38.99% MgO 8.19% K.sub.2O 0.49% Na.sub.2O 0.15% SO.sub.3 3.18% P.sub.2O.sub.5 0.00% Amorphous phases 92.6%

(10) It is clear from the examples that the method according to the invention leads to products with high reactivity that can be used as binders, either per se or mixed with further substances. Compared with the production of Portland cement, the energy use is reduced, in part very significantly reduced. In addition, by-products and waste products can be used to an even greater extent.