Method and system for producing low-alkalinity sulphoaluminate cement with new mineral system using steel slag

Abstract

A method and system for producing low-alkalinity sulphoaluminate cement with a new mineral system using steel slag. The method includes the following steps: evenly mixing and homogenizing ground steel slag with dry desulfurization gypsum, aluminum ash and carbide slag according to a set ratio; and conveying the homogenized raw meal to a rotary kiln for calcination to obtain cement clinker, where the calcination temperature is 1200° C.-1270° C., and the calcination time is 20-60 min; the alkalinity modulus of the homogenized cement raw meal is 0.81-0.9, and the Fe.sub.2O.sub.3 content is 8-13%. The method breaks through the requirements on contents of calcium, aluminum and iron in traditional sulphoaluminate cement production, and realizes application of a large amount of steel slag.

Claims

1. A method for producing sulphoaluminate cement from steel slag, comprising the following steps: evenly mixing and homogenizing ground steel slag with dry desulfurization gypsum, aluminum ash and carbide slag according to a set ratio to obtain a homogenized raw meal; conveying the homogenized raw meal to a rotary kiln for calcination to obtain cement clinker, wherein the calcination temperature is 1200° C.−1270° C., and the calcination time is 20-60 min, wherein an alkalinity modulus of the homogenized raw meal is 0.81-0.9, the homogenized raw meal contains 32-40 parts by weight of CaO, 6-12 parts by weight of SiO.sub.2, 20-28 parts by weight of Al.sub.2O.sub.3, 8-13 parts by weight of Fe.sub.2O.sub.3, and 10-18 parts by weight of SO.sub.3, and the homogenized raw meal has an alumina-sulfur ratio of 1.3-2.0.

2. The method of claim 1, wherein the homogenized raw meal contains 32-35 parts by weight of CaO, 6-12 parts by weight of SiO.sub.2, 20-25 parts by weight of Al.sub.2O.sub.3, 10-13 parts by weight of Fe.sub.2O.sub.3, and 10-15 parts by weight of SO.sub.3.

3. The method of claim 1, wherein the alumina-sulfur ratio of the homogenized raw meal is 1.3-1.8.

4. The method of claim 1, wherein the ground steel slag has a fineness that meets that a sieve residue of a 0.08 mm square hole sieve is less than 10%.

5. The method of claim 4, wherein the fineness of the ground steel slag meets that the sieve residue of the 0.08 mm square hole sieve is from 4% to 8%.

6. The method of claim 1, wherein the homogenizing comprises is grinding homogenization or homogenization treatment in homogenization equipment.

7. The method of claim 1, wherein main mineral phases in the cement clinker comprise calcium sulphoaluminate, gehlenite and calcium sulfoaluminate ferrite, accounting for 40-65%, 5-20% and 10-25% by mass respectively of the cement clinker.

8. The method of claim 7, wherein the main mineral phases in the cement clinker comprise calcium sulphoaluminate, gehlenite and calcium sulfoaluminate ferrite, accounting for 50-65%, 5-20% and 15-25% by mass respectively of the cement clinker.

9. The method of claim 1, further comprising a step of mixing and grinding the cement clinker and gypsum to prepare the sulphoaluminate cement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings that constitute a part of the present invention are used for providing a further understanding of the present invention. Exemplary embodiments of the present invention and the description of the embodiments are used for explaining the present invention and do not constitute any inappropriate limitation to the present invention.

(2) FIG. 1 is a process flowchart of Embodiment 1 of a production system of the present invention.

(3) FIG. 2 is a process flowchart of Embodiment 2 of the production system of the present invention.

(4) FIG. 3 is an X-ray diffraction pattern of cement clinker prepared in Embodiment 1 of the present invention.

DETAILED DESCRIPTION

(5) It should be noted that, the following detailed descriptions are all exemplary, and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those usually understood by a person of ordinary skill in the art to which the present invention belongs.

(6) It should be noted that the terms used herein are merely used for describing specific implementations, and are not intended to limit exemplary implementations of the present invention. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise. In addition, it should be further understood that terms “comprise” and/or “include” used in this specification indicate that there are features, steps, operations, equipments, assemblies, and/or combinations thereof.

Embodiment 1

(7) As shown in FIG. 1, a system for producing sulphoaluminate cement from steel slag includes a dryer, a primary grinder, a secondary grinding homogenizer, a batching equipment and a rotary kiln. The dryer is configured to dry steel slag, desulfurization gypsum, aluminum ash and carbide slag; the dried steel slag is quantified by the batching equipment and is then ground in the primary grinder; the desulfurization gypsum, the aluminum ash and the carbide slag are mixed in the batching equipment according to a set ratio, and are then homogenized and ground with the steel slag in the secondary grinding homogenizer; and the homogenized cement raw meal is calcined in the rotary kiln to obtain cement clinker.

(8) Firstly, all raw materials are dried, and the steel slag obtained by drying is ground. The fineness of the outlet ground steel slag meets that a sieve residue of a 0.08 mm square hole sieve is within 10%. Then the desulfurization gypsum, the aluminum ash, the carbide slag and other materials are mixed according to the set ratio and added to the grinder to be ground and homogenized with the steel slag. An alkalinity modulus of the homogenized cement raw meal is 0.81, and the homogenized raw meal contains 34 parts by weight of CaO, 6 parts by weight of SiO.sub.2, 25 parts by weight of Al.sub.2O.sub.3, 10 parts by weight of Fe.sub.2O.sub.3, and 17 parts by weight of SO.sub.3. Afterwards, the homogenized materials are conveyed to the rotary kiln for calcination to obtain the cement clinker, the calcination temperature is 1250° C., and the calcination time is 30 min. The main mineral composition of the cement clinker is shown in Table 1, and an X-ray diffraction pattern of the cement clinker is shown in FIG. 3. 3% gypsum is added to the cement clinker, and the mixture is ground in a cement grinder to obtain the sulphoaluminate cement. The mechanical properties of the obtained sulphoaluminate cement are shown in Table 8. The strength test standard is based on GB 20472-2006 Sulphoaluminate Cement.

(9) TABLE-US-00001 TABLE 1 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 56 20 17

Embodiment 2

(10) Firstly, all raw materials are dried, and steel slag obtained by drying is ground. The fineness of the outlet ground steel slag meets that a sieve residue of a 0.08 mm square hole sieve is within 10%. Then desulfurization gypsum, aluminum ash, carbide slag and other materials are mixed according to a set ratio and added to the grinder to be ground and homogenized with the steel slag. An alkalinity modulus of the homogenized cement raw meal is 0.9, and the homogenized raw meal contains 38 parts by weight of CaO, 8 parts by weight of SiO.sub.2, 22 parts by weight of Al.sub.2O.sub.3, 13 parts by weight of Fe.sub.2O.sub.3, and 15 parts by weight of SO.sub.3. Afterwards, the homogenized materials are conveyed to the rotary kiln for calcination to obtain cement clinker, the calcination temperature is 1220° C., and the calcination time is 25 min. The main mineral composition of the cement clinker is shown in Table 2. 5% gypsum is added to the cement clinker, and the mixture is ground in a cement grinder to obtain sulphoaluminate cement. The mechanical properties of the obtained sulphoaluminate cement are shown in Table 8. The strength test standard is based on GB 20472-2006 Sulphoaluminate Cement.

(11) TABLE-US-00002 TABLE 2 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 62 6 23

Embodiment 3

(12) As shown in FIG. 2, a system for producing sulphoaluminate cement from steel slag includes a dryer, a grinder, a batching equipment, a homogenization equipment and a rotary kiln. The dryer is configured to dry steel slag, desulfurization gypsum, aluminum ash and carbide slag; the dried steel slag is ground in the grinder; the steel slag, the desulfurization gypsum, the aluminum ash and the carbide slag are mixed in the batching equipment according to a set ratio, and then the mixture is homogenized in the homogenization equipment; and the homogenized cement raw meal is calcined in the rotary kiln to obtain cement clinker.

(13) Firstly, all raw materials are dried, and the steel slag obtained by drying is ground. The fineness of the outlet ground steel slag meets that a sieve residue of a 0.08 mm square hole sieve is within 10%. Then the desulfurization gypsum, the aluminum ash, the carbide slag and other materials are mixed according to the set ratio and the mixture is homogenized. An alkalinity modulus of the homogenized cement raw meal is 0.85, and the homogenized raw meal contains 36 parts by weight of CaO, 10 parts by weight of SiO.sub.2, 24 parts by weight of Al.sub.2O.sub.3, 10 parts by weight of Fe.sub.2O.sub.3, and 15 parts by weight SO.sub.3. Afterwards, the homogenized material is conveyed to the rotary kiln for calcination to obtain the cement clinker, the calcination temperature is 1230° C., and the calcination time is 50 min. The main mineral composition of the cement clinker is shown in Table 3. 4% gypsum is added to the cement clinker, and the mixture is ground in a cement grinder to obtain the sulphoaluminate cement. The mechanical properties of the obtained sulphoaluminate cement are shown in Table 8. The strength test standard is based on GB 20472-2006 Sulphoaluminate Cement.

(14) TABLE-US-00003 TABLE 3 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 65 13 19

Comparative Example 1

(15) The difference from Embodiment 1 is that the homogenized raw meal contains 37 parts by weight of CaO, 6 parts by weight of SiO.sub.2, 20 parts by weight of Al.sub.2O.sub.3, 10 parts by weight of Fe.sub.2O.sub.3, and 19 parts by weight of SO.sub.3. Others are the same as those in Embodiment 1. The main mineral composition of the prepared cement clinker is shown in Table 4, and the properties of the prepared sulphoaluminate cement are shown in Table 8.

(16) TABLE-US-00004 TABLE 4 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Anhydrous Component sulphoaluminate Gehlenite ferrite calcium sulfate Cement clinker 49 5 15 9

Comparative Example 2

(17) The difference from Embodiment 1 is that the homogenized raw meal contains 32 parts by weight of CaO, 7 parts by weight of SiO.sub.2, 30 parts by weight of Al.sub.2O.sub.3, 10 parts by weight of Fe.sub.2O.sub.3, and 15 parts by weight of SO.sub.3. Others are the same as those in Embodiment 1. The main mineral composition of the prepared cement clinker is shown in Table 5, and the properties of the prepared sulphoaluminate cement are shown in Table 8.

(18) TABLE-US-00005 TABLE 5 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 28 53 7

Comparative Example 3

(19) The difference from Embodiment 1 is that the calcination temperature is 1300° C., and others are the same as those in Embodiment 1. The main mineral composition of the prepared cement clinker is shown in Table 6, and the properties of the prepared sulphoaluminate cement are shown in Table 8.

(20) TABLE-US-00006 TABLE 6 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 56 21 15

Comparative Example 4

(21) The difference from Embodiment 1 is that the calcination temperature is 1180° C., and others are the same as those in Embodiment 1. The main mineral composition of the prepared cement clinker is shown in Table 7, and the properties of the prepared sulphoaluminate cement are shown in Table 8.

(22) TABLE-US-00007 TABLE 7 Main mineral composition of cement clinker (wt %) Calcium Calcium sulfoaluminate Component sulphoaluminate Gehlenite ferrite Cement clinker 49 29 6

(23) TABLE-US-00008 TABLE 8 Compressive/flexural strength (unit: MPa) No./Age d 1 d 3 d 28 d Embodiment 1 41.2/6.5 52.3/6.9 67.9/7.5 Embodiment 2 44.8/6.7 57.2/7.1 75.1/7.8 Embodiment 3 42.1/6.5 53.6/6.8 70.2/7.6 Comparative Example 1 27.1/4.8 32.7/5.2 42.3/5.9 Comparative Example 2 17.4/2.9 22.5/3.9 28.7/4.5 Comparative Example 3 39.7/6.4 51.3/7.0 65.8/7.3 Comparative Example 4 27.9/5.0 35.3/5.3 42.8/5.9

(24) The foregoing descriptions are merely preferred embodiments of the present invention, but are not intended to limit the present invention. A person skilled in the art may make various modifications and changes to the present invention. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention is to be fall within the protection scope of the present invention.