Method for preparing cement clinker by melting and bonding granular high-magnesium steel slag with raw material

Abstract

The invention discloses a method for preparing cement clinker by melting and bonding granular high-magnesium steel slag with a raw material, which comprises the following steps: mixing a calcium source, a silicon-aluminum source and a sulfur source to form raw material powder, then uniformly mixing the steel slag with the raw material powder in an original granular form, calcining, and quenching to obtain the cement clinker. The process provided by the invention effectively overcomes the problems of poor stability and over-limit leaching of the water-soluble Cr (VI) content of the cement clinker prepared from the ground steel slag obtained by adopting the traditional process.

Description

Technical Field

[0001] The invention relates to the technical field of cement clinker preparation, and in particular to a method for preparing cement clinker by utilizing granular high-magnesium steel slag to melt and bond raw materials. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] During the steelmaking process in blast furnaces and converters, magnesium in the ore is reduced to magnesium oxide (MgO) and enters the steel slag. Magnesium in slag-forming agents such as limestone and dolomite added during the desulfurization and dephosphorization process is also introduced into the steel slag, resulting in a high MgO content in the steel slag, even reaching more than 10%. Its use in cement concrete is mainly limited by the following three aspects: (1) Steel slag with a high MgO content has low alkalinity and poor grindability. A large amount of energy is consumed during the grinding process, and the resulting steel slag powder has low hydration activity, a low dosage in cement concrete, and poor economic efficiency. (2) The content of MgO in the steel slag is high, and the content of MgO in the steel slag is high. f -MgO reacts slowly with water to form Mg(OH)2, with a volume expansion rate of up to 248%, resulting in poor volume stability of steel slag, which limits the application of steel slag aggregate in structural concrete. (3) The chromium content in high-magnesium steel slag is much higher than that of other raw materials. When using steel slag powder as a substitute raw material to produce cement clinker, it is very easy to cause the water-soluble Cr(VI) content in cement to exceed the standard. Therefore, the comprehensive utilization of medium- and low-alkalinity high-magnesium steel slag has always been a difficult problem in the field of solid waste treatment. Summary of the Invention

[0004] To address the current challenges of using steel slag powder as a raw material to produce cement clinker, resulting in poor stability and excessive leaching of water-soluble Cr(VI), the present invention provides a method for producing cement clinker using granular high-magnesium steel slag to melt-bond raw meal. Specifically, the technical solution of the present invention is as follows.

[0005] A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: mixing a calcium source, a silicon-aluminum source, and a sulfur source to form raw material powder; then uniformly mixing the steel slag in its original granular form with the raw material powder and calcining the mixture; and then rapidly cooling the mixture to obtain the cement clinker.

[0006] Furthermore, the calcium source includes at least one of carbide slag, high-magnesium limestone, etc.

[0007] Furthermore, the silicon-aluminum source includes at least one of fly ash, coal gangue, iron tailings, waste ceramics, red mud, low-grade bauxite, etc.

[0008] Furthermore, the sulfur source includes at least one of phosphogypsum, desulfurized gypsum, fluorinated gypsum, titanium gypsum, and chemically pure gypsum.

[0009] Furthermore, the steel slag includes at least one of converter steel slag, electric furnace steel slag, stewed steel slag, drum steel slag, etc. Optionally, the MgO content in the steel slag is ≥ 5 wt.%. Preferably, the particle size of the steel slag is not less than 0.3 mm.

[0010] Furthermore, the steel slag accounts for 5-15% of the mass of the raw meal. Preferably, the particle size of the steel slag does not exceed 30 mm. Optionally, the residue on an 80 μm square mesh sieve of the raw meal is no more than 10%.

[0011] Furthermore, the calcination treatment temperature is 1250-1350° C., and the calcination time is 15-30 minutes.

[0012] Optionally, the cement clinker comprises the following mineral phases: calcium sulfoaluminate (C4A3$) 9.8-22.1wt.%, β-dicalcium silicate (β-C2S) 25.5-32.8wt.%, iron phase (Ca2Fe2O5, C4AF) 21.8-27.2wt.%, magnesium spinel (MgFe2O4) 3.5-10.1wt.%, calcium aluminate (C 12 A7) 3.8-5.4 wt.%, pyroxene 3.2-6.5 wt.%, amorphous phase 12.1-19.1 wt.%, and Cr(III) solid solution in the magnesium spinel. It should be understood that cement clinker with other compositions can also be prepared by adjusting the proportion of the raw materials as needed.

[0013] Furthermore, the surface of the steel slag is also loaded with a modified powder formed by waste spinel material and quartz sand. Optionally, the dosage of the modified powder is 1 to 1.5% of the mass of the steel slag. Wherein: the waste spinel material acts as a seed to provide heterogeneous nucleation sites, which can effectively reduce the nucleation barrier of magnesium spinel in the clinker, induce the magnesium spinel to grow rapidly and uniformly and efficiently dissolve chromium elements. The quartz sand optimizes the phase composition of steel slag, promotes the formation of low-melting-point eutectics, and improves Mg 2+ 、Fe 3+ and Cr 3+ The diffusion and migration rate of plasma in the melt makes MgO and Cr2O3 more inclined to combine with Fe2O3 and Al2O3 to form magnesium spinel, which promotes the solid solution of chromium.

[0014] Furthermore, the mass ratio of the waste spinel material to the quartz sand is 1:0.9-1.2. Optionally, the fineness of the modified powder is 300-500 mesh.

[0015] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: The original granular form of steel slag significantly reduces the contact area between the raw material and O₂ during clinker sintering, enabling controlled interfacial reactions between the slag, raw meal powder, and O₂. This effectively inhibits the oxidation of Cr(III) in the slag to water-soluble chromates such as Na₂CrO₄ and K₂Cr₂Oₐ. In addition to primary oxides such as CaO, SiO₂, and Fe₂O₃, granular steel slag also contains components such as RO phase (a divalent continuous solid solution of Fe-Mg-Mn) and P₂O₅. This chemical composition makes granular steel slag a suitable precursor for flux mineralization during clinker sintering. It first melts into a liquid at relatively low temperatures, exhibiting excellent fluidity and reactivity. It then adheres to the raw meal powder through wetting and adsorption mechanisms, promoting clinker mineralization. Its low melting point significantly reduces the sintering temperature by 50–100°C during clinker calcining. The silicate minerals and multi-graded distribution of granular high-Mg steel slag further enhance its seed mineralization effect and stabilize the β-C₂S crystal structure. Mn in steel slag 2+ 、Ti 4+ Mg 2+ etc. enter the clinker mineral lattice through solid solution doping or lattice replacement, increase its lattice defect density, and thus improve hydration activity. The Fe2O3 content of steel slag is generally greater than 20%. Its high-temperature molten liquid phase has a large amount and has typical high-iron characteristics. It can capture alkali metal ions in the raw material and dissolve in the clinker mineral lattice. In the process of adhering to the raw material, it promotes the formation of a large amount of iron phase in the ferroaluminate cement clinker, enhances the clinker's resistance to sulfate corrosion, and has broad application prospects in harsh environments such as oceans and saline-alkali lands. The Mg-rich phase (RO phase, magnesia feldspar, calcium-magnesium olivine, etc.) in the granular high-magnesium steel slag is in the oxygen-deficient microenvironment inside the clinker ball, after high-temperature calcination and induction of raw material components, it directionally generates magnesium spinel phase, Cr 3+ with Fe 3+ The ionic radius of Cr(III) is similar, and it can replace the trivalent metal ions on the octahedral position, effectively inhibiting the oxidation of Cr(III) to Cr(VI), solving the problem from the source. f The cement clinker of the present invention contains early-strength minerals and highly hydration-active silicate minerals, resulting in stable mechanical properties throughout the hydration cycle. It also exhibits corrosion resistance, anti-seepage properties, high frost resistance, and micro-expansion properties, and has broad application prospects in special environmental projects such as marine engineering, emergency repair projects, and underground engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 This is a sample picture of cement clinker prepared in the following Example 1.

[0018] Figure 2 The XRD test results of the cement clinker prepared in Example 1 are shown below. Figure 3 This is the petrographic structure diagram of the cement clinker prepared in the following Example 1. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0020] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. The reagents and raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in the present invention are used in accordance with conventional methods in the art or in accordance with the product instructions.

[0021] In addition, any methods and materials similar or equivalent to those described herein can be applied to the method of the present invention. The technical solution of the present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0022] The main components (mass fraction / %) of high-magnesium limestone, low-grade bauxite, fly ash, phosphogypsum, desulfurization gypsum, carbide slag, iron tailings, and fluorsulphite in the following examples are shown in the following table.

[0023] Example 1 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0024] (2) Add the above raw materials to a ball mill and grind them until the residue on an 80μm square sieve is ≤10% to obtain raw material powder. Then, add 10% of the original granular hot-stewed steel slag particles (particle size distribution between 0.3 and 15mm, MgO content of 7.39wt.%) to the raw material powder, stir evenly, and place in a silicon carbon rod electric furnace, first heat to 1300℃ at a rate of 10℃ / min and keep warm for 30min. After completion, blow the obtained calcined product to the room temperature by fan, and then grind the obtained sintered body in a ball mill and pass it through a 200-mesh sieve to obtain cement clinker. Figure 1 shown.

[0025] 1. The mineral components of the cement clinker prepared in this embodiment were tested, and the results were as follows: Figure 2 As shown. Among them: calcium sulfoaluminate (C4A3$) is 12.2wt.%, β-dicalcium silicate (β-C2S) is 25.5wt.%, iron phase is 26.0wt.%, magnesium spinel (MgFe2O4) is 9.2wt.%, calcium aluminate (C 12 A7) is 4.3wt.%, pyroxene is 4.4wt.%, and amorphous phase (ferroaluminate glass produced during rapid cooling without crystallization, mainly composed of Fe2O3, Al2O3 and CaO) is 18.4wt.%. In addition, the petrographic structure of the cement clinker is as follows Figure 3 As shown, the square or pyramid-shaped crystals with the highest reflectivity are magnesium spinel phases, the round or irregular crystals with the largest size are β-C2S minerals, the fine grains are C4A3$ minerals, and the iron phase and the poorly crystallized amorphous phase are filled as interstitial phases between the minerals.

[0026] 2. The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 1 below.

[0027] Table 1 Example 2 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0028] (2) The above raw materials are added to a ball mill and ground until the residue on an 80 μm square sieve is ≤10% to obtain raw meal powder. Then, 15% by weight of the original granular hot-stewed steel slag particles (particle size distribution between 1 and 15 mm, MgO content of 7.39 wt.%) are added to the raw meal powder. After stirring evenly, the raw meal powder is placed in a silicon carbon rod electric furnace and heated to 1300°C at a rate of 10°C / min and kept at this temperature for 30 min. After completion, the calcined product is purged with a fan and rapidly cooled to room temperature. The sintered body is then ground in a ball mill and passed through a 200 mesh sieve to obtain cement clinker.

[0029] 1. The mineral components of the cement clinker prepared in this example were tested. Among them: C4A3$ is 9.8wt.%, β-C2S is 28.5wt.%, iron phase is 27.2wt.%, spinel is 10.1wt.%, C 12 A7 is 5.4wt.%, pyroxene is 6.5wt.%, and the amorphous phase is 12.5wt.%.

[0030] 2. The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 2 below.

[0031] Table 2 Example 3 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 59.8 parts by weight of high-magnesium limestone, 22.2 parts by weight of fly ash, and 15.3 parts by weight of desulfurized gypsum.

[0032] (2) The above raw materials were added to a ball mill and ground until the residue on an 80 μm square sieve was ≤10% to obtain raw meal powder. Then, 5% by weight of original granular converter steel slag particles (particle size distribution between 2 and 15 mm, MgO content of 5.06 wt.%) were added to the raw meal powder. After stirring evenly, the raw meal powder was placed in a silicon carbon rod electric furnace and heated to 1250°C at a rate of 10°C / min and kept at this temperature for 30 min. After completion, the calcined product was purged with a fan and rapidly cooled to room temperature. The sintered body was then ground in a ball mill and passed through a 200 mesh sieve to obtain cement clinker.

[0033] 1. The mineral components of the cement clinker prepared in this example were tested. Among them: C4A3$ is 14.5wt.%, β-C2S is 26.3wt.%, iron phase is 24.8wt.%, spinel is 6.0wt.%, C 12 A7 is 3.8wt.%, pyroxene is 5.5wt.%, and the amorphous phase is 19.1wt.%.

[0034] 2. The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 3 below.

[0035] Table 3 Example 4 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 49.5 parts by weight of carbide slag, 27.5 parts by weight of fly ash, 10.4 parts by weight of iron ore tailings, and 12.6 parts by weight of fluorgypsum.

[0036] (2) The above raw materials were added to a ball mill and ground until the residue on an 80 μm square sieve was ≤10% to obtain raw meal powder. Then, 5% by weight of the original granular drum steel slag particles (particle size distribution between 5 and 15 mm, MgO content of 11.24 wt.%) was added to the raw meal powder. After stirring evenly, the raw meal powder was placed in a silicon carbon rod electric furnace and heated to 1350°C at a rate of 10°C / min and kept warm for 15 minutes. After completion, the calcined product was purged with a fan and rapidly cooled to room temperature. The sintered body was then ground in a ball mill and passed through a 200 mesh sieve to obtain cement clinker.

[0037] 1. The mineral components of the cement clinker prepared in this example were tested. Among them: C4A3$ is 22.1wt.%, β-C2S is 32.8wt.%, iron phase is 21.8wt.%, spinel is 3.5wt.%, C 12 A7 is 4.5wt.%, pyroxene is 3.2wt.%, and the amorphous phase is 12.1wt.%.

[0038] 2. The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching amount of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 4 below.

[0039] Table 4 Example 5 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0040] (2) Add the above raw materials to a ball mill and grind them until the residue on an 80μm square sieve is ≤10% to obtain raw material powder. Then, add 10% of the raw material powder by weight of hot-stewed steel slag powder (fineness of 309.3m 2 / kg, MgO content is 7.39wt.%), first heated to 1300℃ at a rate of 10℃ / min and kept warm for 30min. After completion, the calcined product was purged with a fan and rapidly cooled to room temperature. Then, the sintered body was ground in a ball mill and passed through a 200-mesh sieve to obtain cement clinker.

[0041] The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 5 below.

[0042] Table 5 Example 6 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0043] (2) Add the above raw materials to a ball mill and grind them until the residue on an 80μm square sieve is ≤10% to obtain raw material powder. Then, add 15% of the raw material powder by weight of hot-stewed steel slag powder (fineness 411.7m 2 / kg, MgO content of 7.39wt.%), stirred evenly and placed in a silicon carbon rod electric furnace, first heated to 1300℃ at a rate of 10℃ / min and kept warm for 30min. After completion, the calcined product was purged with a fan and rapidly cooled to room temperature. The solid material was then ground in a ball mill and passed through a 200-mesh sieve to obtain cement clinker.

[0044] The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 6 below.

[0045] Table 6 Example 7 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Weigh the raw materials according to the following proportions: 59.8 parts by weight of high-magnesium limestone, 22.2 parts by weight of fly ash, and 15.3 parts by weight of desulfurized gypsum.

[0046] (2) Add the above raw materials to a ball mill and grind them until the residue on an 80μm square sieve is ≤10% to obtain raw material powder. Then, add 5% by weight of ground converter steel slag coarse powder (fineness 147.8m 2 / kg, MgO content of 5.06wt.%), stirred evenly and placed in a silicon carbon rod electric furnace, first heated to 1250℃ at a rate of 10℃ / min and kept warm for 30min. After completion, the calcined product was purged with a fan and rapidly cooled to room temperature. The solid material was then ground in a ball mill and passed through a 200-mesh sieve to obtain cement clinker.

[0047] The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 7 below.

[0048] Table 7 Example 8 A method for preparing cement clinker using granulated high-magnesium steel slag to melt-bond raw meal is similar to Example 1 above, except that the hot-stewed steel slag particles in this embodiment are ground and screened to obtain a fine powder with a particle size distribution between 0.1 and 0.2 mm. The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination Methods of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015) and the result was 12.25 mg / kg.

[0049] Example 9 A method for preparing cement clinker using granulated high-magnesium steel slag to melt-bond raw meal is similar to Example 1 above, except that the hot-stewed steel slag particles in this embodiment are ground and sieved to obtain a fine powder with a particle size distribution between 0.05 and 0.1 mm. The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination Methods of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015), and the result was 14.46 mg / kg.

[0050] Example 10 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Original granular hot-stewed steel slag particles (particle size distribution between 0.3 and 15 mm, MgO content of 7.39 wt.%) and 500-mesh modified powder (made by grinding discarded spinel refractory bricks and quartz sand in a mass ratio of 1:1) were placed in a V-type rotary mixer. The modified powder content was 1% of the slag mass. After mixing for 10 minutes, 0.5% of the mixture mass of atomized water was added and stirred for another 5 minutes to obtain the modified steel slag.

[0051] (2) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0052] (3) The raw materials are added to a ball mill and ground until the residue on an 80 μm square sieve is ≤10% to obtain raw meal powder. The raw meal powder is then mixed with 10% by weight of the modified steel slag, mixed thoroughly, and placed in a silicon carbon rod electric furnace. The raw meal powder is first heated to 1300°C at a rate of 10°C / min and kept warm for 30 min. After completion, the calcined product is purged with a fan and rapidly cooled to room temperature. The sintered body is then ground in a ball mill and passed through a 200-mesh sieve to obtain cement clinker.

[0053] The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 10 below.

[0054] Table 10 Example 11 A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag comprises the following steps: (1) Original granular hot-stewed steel slag particles (particle size distribution between 1 and 15 mm, MgO content of 7.39 wt.%) and 300-mesh modified powder (ground from discarded spinel refractory bricks and quartz sand at a mass ratio of 1:1.2) were placed in a V-shaped rotary mixer. The modified powder content was 1.5% of the slag mass. After mixing for 10 minutes, 0.6% of the mixture mass of atomized water was added and stirred for another 5 minutes to obtain the modified steel slag.

[0055] (2) Weigh the raw materials according to the following proportions: 65.1 parts by weight of high-magnesium limestone, 20.5 parts by weight of low-grade bauxite, and 12.2 parts by weight of phosphogypsum.

[0056] (3) The above raw materials are added to a ball mill and ground until the residue on an 80 μm square sieve is ≤10% to obtain raw material powder. Then, 15% by weight of the modified steel slag is added to the raw material powder, mixed thoroughly, and placed in a silicon carbon rod electric furnace. The mixture is first heated to 1300°C at a rate of 10°C / min and kept at this temperature for 30 min. After completion, the calcined product is purged with a fan and rapidly cooled to room temperature. The sintered body is then ground in a ball mill and passed through a 200-mesh sieve to obtain cement clinker.

[0057] The compressive strength of the cement clinker prepared in this example was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GB / T 17671-1999). The Cr(VI) leaching rate of the cement clinker was tested according to the "Limits and Determination of Water-Soluble Chromium (VI) in Cement" (GB 31893-2015). The results are shown in Table 11 below.

[0058] Table 11 The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag, characterized in that: The method comprises the following steps: mixing a calcium source, a silicon-aluminum source and a sulfur source to form raw material powder, then uniformly mixing steel slag in its original granular form with the raw material powder and calcining the mixture, and then rapidly cooling the mixture to obtain the cement clinker.

2. The method for preparing cement clinker by melting and bonding raw materials with granular high-magnesium steel slag according to claim 1, characterized in that: The calcium source includes at least one of carbide slag and high-magnesium limestone.

3. The method for preparing cement clinker by melting and bonding raw meal with granular high-magnesium steel slag according to claim 1, characterized in that: The silicon-aluminum source includes at least one of fly ash, coal gangue, iron tailings, waste ceramics, red mud, and low-grade bauxite.

4. The method for preparing cement clinker by melting and bonding raw meal with granular high-magnesium steel slag according to claim 1, characterized in that: The sulfur source includes at least one of phosphogypsum, desulfurized gypsum, fluorinated gypsum, titanium gypsum, and chemically pure gypsum.

5. The method for preparing cement clinker by melting and bonding raw meal with granular high-magnesium steel slag according to claim 1, characterized in that: The steel slag includes at least one of converter steel slag, electric furnace steel slag, hot-stewed steel slag, and drum steel slag; preferably, the particle size of the steel slag is not less than 0.3 mm.

6. The method for preparing cement clinker by melting and bonding raw meal with granular high-magnesium steel slag according to claim 5, characterized in that: The MgO content in the steel slag is ≥5wt.%.

7. The method for preparing cement clinker by melting and bonding raw meal with granular high-magnesium steel slag according to claim 1, characterized in that: The steel slag is 5-15% of the mass of the raw meal; Preferably, the particle size of the steel slag does not exceed 30 mm; Optionally, the residue on the 80 μm square hole sieve of the raw meal powder is no more than 10%.

8. The method for preparing cement clinker by melting and bonding raw meal with granulated high-magnesium steel slag according to any one of claims 1 to 7, characterized in that: The surface of the steel slag is also loaded with modified powder formed by waste spinel material and quartz sand; Optionally, the modified powder is added in an amount of 1-1.5% of the mass of the steel slag; Optionally, the mass ratio of the waste spinel material to the quartz sand is 1:0.9-1.2; Optionally, the fineness of the modified powder is 300-500 mesh.

9. The method for preparing cement clinker by melting and bonding raw meal with granulated high-magnesium steel slag according to any one of claims 1 to 7, characterized in that: The calcination temperature is 1250-1350° C., and the calcination time is 15-30 minutes.

10. The method for preparing cement clinker by melting and bonding raw meal with granulated high-magnesium steel slag according to any one of claims 1 to 7, characterized in that: The cement clinker comprises the following mineral phases: C4A3$ 9.8~22.1wt.%, β-C2S 25.5~32.8wt.%, iron phase 21.8~27.2wt.%, MgFe2O4 3.5~10.1wt.%, C 12 A7 3.8~5.4wt.%, pyroxene 3.2~6.5wt.%, amorphous phase 12.1~19.1wt.%, and Cr(III) is solid-dissolved in the MgFe2O4.

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