Multi-element solid waste cement clinker and preparation method thereof

Abstract

The invention relates to the technical field of industrial solid waste resource comprehensive utilization and cement manufacturing, in particular to a multi-element solid waste cement clinker and a preparation method thereof. According to the specific technical scheme, the multi-element solid waste cement clinker is prepared from the following components in parts by weight: 60 to 70 parts of carbide slag or 62 to 78 parts of papermaking white mud, 5 to 10 parts of quartz tailings or other tailings containing silicon dioxide, 10 to 25 parts of slag powder, 3 to 10 parts of fly ash, 5 to 8 parts of desulfurized gypsum and 2 to 8 parts of red mud. According to the invention, various industrial solid wastes can be digested, and the environmental pollution caused by solid waste accumulation and the economic and labor cost required by solid waste treatment are reduced. In addition, the requirements for clay, limestone and other non-renewable resources in the cement clinker production process can be reduced, the production cost is reduced, meanwhile, industrial solid waste is utilized to create economic benefits, the raw materials meet the Portland cement production standard, and a product with the components and performance extremely close to those of conventional cement clinker can be prepared by adjusting the proportion.

Description

Technical Field

[0001] The present invention relates to the technical fields of comprehensive utilization of industrial solid waste resources and cement manufacturing, and particularly relates to a multi-component solid waste cement clinker and a preparation method thereof. Background Art

[0002] In China, the annual cement output is over 2 billion tons, the annual output of commercial concrete exceeds 2 billion cubic meters, and the annual carbon dioxide emissions exceed 1.2 billion tons, facing extremely severe energy conservation and emission reduction pressures. In the process of China's modernization, the development of the three major industries has an increasing demand for non-renewable resources such as ore resources, energy, and soil resources, resulting in a decreasing amount of resources. At the same time, the cumulative stockpiling of various industrial solid wastes exceeds 6.2 billion tons, which not only occupies a large amount of land for stacking, but also brings various problems such as environment and safety. Currently, solid wastes still face severe challenges of high generation intensity, insufficient utilization, and low added value of comprehensive utilization products. It is necessary to vigorously promote the source reduction, resource utilization, and harmless disposal of bulk solid wastes, strengthen the whole-chain governance, focus on solving prominent contradictions and problems, and promote the new development of the comprehensive resource utilization industry. Therefore, the resource utilization of industrial solid wastes is extremely urgent. Due to the high demand for cement in the process of social development, the combination of industrial solid wastes and cement production can not only greatly reduce the quantity of solid wastes, but also meet the needs of social production and bring a large amount of economic value.

[0003] In the existing related patents for firing cement clinker using solid wastes (application numbers: 202310677773.2, 202010256888.0, 202210490789.8, 202210081850.3), steel slag is mostly used as the raw material. Steel slag contains a large amount of iron oxides and has poor soundness. The use of steel slag is prohibited in the latest preparation specification of Portland cement (GB 175-2023). Therefore, new technologies are urgently needed to dispose of solid wastes.

[0004] There are relatively few patents related to the complete use of solid waste to prepare cement, and many of them involve the use of steel slag. Among the patents that do not involve steel slag (application numbers: 202011583113.0, 200410016744.9), hazardous waste such as incineration fly ash is used. Incineration fly ash contains various heavy metals, organic pollutants, dioxins, etc., has certain toxicity and environmental hazards, has relatively high requirements for the firing process, and the prepared clinker used in building materials will pose potential hazards to organisms and the environment, and is not suitable for large-scale production and application. In some patents related to the preparation of cement clinker (application numbers: 202310607962.2, 202210081850.3, 202410625951.1, 202110913089.0), the types of all solid wastes are relatively few, and there is still a demand for non-solid waste substances such as limestone and bauxite. In the non-clinker cement prepared from industrial solid waste (application number: 202310920243.6), an activator is required during use to make the cement form a gel. This type of cement-based material lacks specifications so far, and its performance is greatly affected by environmental factors. Compared with common clinker cements such as portland cement and calcium sulfoaluminate cement, there are difficulties in popularization and application. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a multi-component solid waste cement clinker and a preparation method thereof.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0007] The present invention discloses a multi-component solid waste cement clinker. Calculated by weight, 60-70 parts of carbide slag or 62-78 parts of papermaking white mud, 5-10 parts of quartz tailings or other tailings containing silicon dioxide, 10-25 parts of slag powder, 3-10 parts of fly ash, 5-8 parts of desulfurized gypsum, and 2-8 parts of red mud.

[0008] Preferably, in the fly ash, the SiO2 content is 20-62%, the Al2O3 content is 10-40%, and the CaO content is 1-45%; in the carbide slag, the CaO content is 60-80%; in the quartz tailings, the SiO2 content is greater than 70%; in the red mud, the SiO2 content is 15-20%, the Al2O3 content is 10-20%, the CaO content is 5-10%, and the Fe2O3 content is 20-60%; in the slag powder, the SiO2 content is 30-40%, the Al2O3 content is 15-25%, and the CaO content is 35-45%; in the desulfurized gypsum, the CaSO4·2H2O content is greater than 90%.

[0009] Preferably, in the papermaking white mud, the calcium carbonate content is 80-90%, the SiO2 content is 7-8%, and the alumina content is 3-4%; in the other silica-containing tailings, the SiO2 content is greater than 90%. When the SiO2 content is lower than 90%, the addition amount of the other silica-containing tailings is 5-15 parts.

[0010] Correspondingly, a method for preparing the above-mentioned multi-solid waste cement clinker includes the following steps:

[0011] (1) After drying raw materials such as carbide slag or papermaking white mud, quartz tailings or other silica-containing tailings, slag powder, fly ash, desulfurized gypsum and red mud, mix and grind them, and pass through a 200-300 mesh sieve to obtain raw meal.

[0012] (2) After pressing the raw meal into cakes, conduct high-temperature calcination. After the calcination is completed, conduct rapid cooling.

[0013] (3) After cooling, grind and pass through a 200-300 mesh sieve to obtain the clinker powder.

[0014] Preferably, in step (1), dry at 75-85 °C for 3-5 h.

[0015] Preferably, in step (1), first grind the quartz tailings or other silica-containing tailings. After grinding for about 1 h, then add red mud and continue to grind for about 30 min. Add carbide slag or papermaking white mud, slag powder, fly ash and desulfurized gypsum for mixing and grinding. After the grinding is completed, stir and mix the ground raw meal. The grinding order of the whole raw material is determined according to the particle size of each raw material. The one with the largest particle size is ground first, and then, the particle sizes are added one by one in order.

[0016] Preferably, in step (2), spray water on the raw meal, stir evenly, press into cakes, and dry; or directly press the raw meal powder into cakes.

[0017] Preferably, in step (2), the calcination process is: heat up at 8±2 °C / min to 1000±50 °C, and then heat up at 5±2 °C / min to 1450±50 °C, and calcine for 30-45 min.

[0018] The present invention has the following beneficial effects:

[0019] 1. Based on the chemical compositions of six types of industrial solid wastes, namely fly ash, carbide slag or papermaking white mud, quartz tailings, red mud, slag powder, and desulfurized gypsum, and the composition of common silicate cement on the market, the present invention proposes a raw material proportioning design method and the dosage ranges of various industrial solid wastes. According to the mixing ratios of various solid wastes, grinding is carried out according to the set grinding sequence. After uniformly mixing the raw materials, they are pressed into round cakes using a mold, fired at high temperature, and then rapidly cooled. The clinker obtained after firing is ground and sieved to obtain clinker powder. The present invention can not only dispose of multiple types of industrial solid wastes, reduce the environmental pollution caused by the accumulation of solid wastes and the economic and labor costs required for treating solid wastes, but also reduce the demand for non-renewable resources such as clay and limestone in the production process of cement clinker, reduce production costs, create economic benefits by using industrial solid wastes, and the raw materials meet the production specifications of silicate cement. By adjusting the proportioning, products with compositions and properties very close to those of conventional cement clinker can be prepared.

[0020] 2. The present invention realizes the complete utilization of industrial solid wastes to prepare cement clinker, avoiding the use of non-waste non-renewable resources and steel slag in the cement firing process. As many types of solid wastes as possible are utilized to achieve the goal of large-scale disposal of multiple types of solid wastes. It reduces the environmental hazards and economic pressure brought by treating solid wastes, prepares solid wastes into cement, meets social needs, and brings economic benefits at the same time.

[0021] 3. The present invention utilizes more types of solid wastes, including six types of solid wastes: carbide slag, quartz tailings, slag powder, fly ash, desulfurized gypsum, and red mud. Producing cement can reduce the environmental pollution caused by solid wastes, reduce the costs required for treating solid wastes, and achieve the goal of large-scale disposal of solid wastes. Moreover, the raw materials used do not contain steel slag, the raw materials meet the production specifications of silicate cement, the contents of iron oxide and magnesium oxide are extremely low, and the soundness is strong. Hazardous wastes such as incineration fly ash are not used either, so it is safer in production and application. According to the preparation method disclosed in the present invention and the defined raw material ratios, clinker with compositions and properties very similar to those of conventional silicate cement clinker on the market can be fired, thereby reducing the production cost of cement and avoiding the demand for non-renewable resources such as bauxite, clay, and limestone.

[0022] At the same time, according to the mixing ratio design method of the cement raw materials disclosed in the present invention, when the composition of the raw materials changes, appropriate cement raw materials can still be prepared according to the mixing ratio design method for firing. Detailed implementation mode

[0023] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0025] The invention discloses a multi-solid waste cement clinker, which comprises, by weight, 60-70 parts of carbide slag or 62-78 parts of papermaking white mud, 5-10 parts of quartz tailings or other tailings containing silicon dioxide, 10-25 parts of slag powder, 3-10 parts of fly ash, 5-8 parts of desulfurized gypsum and 2-8 parts of red mud.

[0026] Among them, the fly ash has a SiO2 content of 20-62%, an Al2O3 content of 10-40%, and a CaO content of 1-45%; the carbide slag has a CaO content of 60-80%; the quartz tailings has a SiO2 content greater than 70%; the red mud has a SiO2 content of 15-20%, an Al2O3 content of 10-20%, a CaO content of 5-10%, and a Fe2O3 content of 20-60%; the slag powder has a SiO2 content of 30-40%, an Al2O3 content of 15-25%, and a CaO content of 35-45%; and the desulfurized gypsum has a CaSO4·2H2O content greater than 90%.

[0027] Furthermore, in the papermaking white mud, the calcium carbonate content is 80-90%, the SiO2 content is 7-8%, and the aluminum oxide content is 3-4%; in the other tailings containing silicon dioxide, the SiO2 content is greater than 90%. When the SiO2 content is lower than 90%, the addition amount of the other tailings containing silicon dioxide is 5-15 parts.

[0028] The present invention discloses a method for preparing multi-component solid waste cement clinker, comprising the following steps:

[0029] (1) Dry the raw materials of carbide slag or papermaking white mud, quartz tailings or other tailings containing silica, slag powder, fly ash, desulfurized gypsum and red mud at 75-85°C for 3-5 hours, mix and grind them after drying, and pass them through a 200-300 mesh sieve to obtain raw materials.

[0030] Specifically: First, grind the quartz tailings or other silica-containing tailings. After grinding for about 1 hour, then add red mud and continue grinding for about 30 minutes. Add carbide slag or papermaking white mud, slag powder, fly ash, and desulfurized gypsum and mix them for grinding. After the grinding is completed, stir and mix the ground raw materials. The grinding order of the entire raw materials is determined according to the particle sizes of the respective raw materials. The raw material with the largest particle size is ground first, and then the raw materials are added successively according to the particle size.

[0031] (2) After pressing the raw materials into cakes, conduct high-temperature calcination. After the calcination is completed, conduct rapid cooling; Specifically: Spray water on the raw materials, stir evenly, press them into cakes, and then dry them. Spraying water is to shape the raw materials; or directly press the raw material powder into cakes.

[0032] The process of calcination is as follows: Heat up at 8 ± 2 °C / min to 1000 ± 50 °C, and then heat up at 5 ± 2 °C / min to 1450 ± 50 °C, and calcine for 30 - 45 minutes.

[0033] (3) After cooling, conduct grinding and pass through a 200 - 300 mesh sieve to obtain the clinker powder.

[0034] The following further elaborates on the present invention in combination with specific embodiments.

[0035] I. The raw material composition and the design process of the mixing ratio of the cement clinker in the present invention are as follows:

[0036] 1. Raw materials: Fly ash, carbide slag, quartz tailings, red mud, slag powder, desulfurized gypsum

[0037] The main substance content ranges of the raw materials:

[0038] Fly ash: The content of SiO2 is 20 - 62%, the content of Al2O3 is 10 - 40%, and the content of CaO is 1 - 45%.

[0039] Carbide slag: The content of CaO is about 70%.

[0040] Quartz tailings: The content of SiO2 is above 70%.

[0041] Red mud: The content of SiO2 is 15 - 20%, the content of Al2O3 is 10 - 20%, the content of CaO is 5 - 10%, and the content of Fe2O3 is 20 - 60%.

[0042] Slag powder: The content of SiO2 is 30 - 40%, the content of Al2O3 is 15 - 25%, and the content of CaO is 35 - 45%

[0043] Desulfurized gypsum: The content of CaSO4·2H2O is usually above 90%.

[0044] 2. Raw material mix proportion design method: First, determine the dosage ranges of red mud and desulfurized gypsum based on the contents of Fe2O3 and CaSO4 in 425 and 525 Portland cements. Second, conduct a comparative analysis of the SiO2 and Al2O3 content ratios in fly ash and slag powder, and add a slightly larger amount of the one with a larger SiO2 / Al2O3 ratio. Add quartz tailings to adjust the SiO2 and Al2O3 ratios in the mixture. Finally, use carbide slag to adjust the calcium-silicon ratio in the mixture to complete the mix proportion of cement raw meal.

[0045] Among them, the dosage of red mud and desulfurized gypsum is not recommended to exceed 8%, the dosage of slag powder is not recommended to exceed 25%, the dosage of fly ash is not recommended to exceed 10%, the dosage of carbide slag is not recommended to be lower than 60%, and the dosage of quartz tailings is not recommended to exceed 10%.

[0046] Mix proportion: By weight, 60 - 70 parts of carbide slag, 5 - 10 parts of quartz tailings, 10 - 25 parts of slag powder, 3 - 10 parts of fly ash, 5 - 8 parts of desulfurized gypsum, and 2 - 8 parts of red mud.

[0047] Furthermore, in the present invention, the carbide slag powder can be replaced by papermaking white mud. In papermaking white mud, the calcium carbonate content is 80 - 90%, the silicon dioxide content is 7 - 8%, the alumina content is 3 - 4%, and there is a small amount of calcium hydroxide. After replacing the carbide slag powder with papermaking white mud powder, the dosage of carbide slag powder can be appropriately increased as the dosage of papermaking white mud, such as increased to 62 - 78 parts.

[0048] The quartz tailings can be replaced by other tailings rich in silicon dioxide, with a SiO2 content greater than 90%. When the SiO2 content is lower than 90%, the dosage needs to be appropriately increased, such as increased to 5 - 15 parts.

[0049] II. The preparation process of cement clinker in the present invention is as follows:

[0050] (1) Weigh a certain amount of various solid wastes according to the above raw material mix proportion and place them in an electrothermal blast drying oven for drying until the mass of various solid wastes no longer changes.

[0051] (2) Place the quartz tailings in a horizontal ball mill for grinding. After grinding to a lower fineness, add red mud and continue grinding. Finally, add carbide slag, slag powder, fly ash, and desulfurized gypsum for mixed grinding.

[0052] (3) Take out the ground raw meal and further stir it with a mixer to prevent some substances from sticking to the inner wall during the grinding process and making the mixture uneven. After stirring, use a sieve machine for sieving, and select a 200 - mesh sieve.

[0053] (4) The raw material is placed in a round bottom container, sprayed with an appropriate amount of water using a spray bottle and stirred evenly, pressed into a round cake with a diameter of 40 mm and a thickness of 10 mm in a stainless steel cake pressing mold, and the round cake is placed in an electric heated air drier for drying. In this step, the raw material dry powder can also be directly used or a small amount of water can be added to directly press it into a round cake under a press to omit the drying step.

[0054] (5) Place the round raw material in a muffle furnace for firing. First, heat it to 1000°C at a rate of 8°C / min. After reaching 1000°C, gradually heat it to 1450°C at a rate of 5°C / min. Calcine at 1450°C for 30-45 minutes.

[0055] (6) After the clinker is calcined, take out the round cake and place it in an air-cooled box for rapid cooling to ensure the quality of the clinker.

[0056] (7) The cooled round cake is placed in a ball mill for grinding. After grinding, it is sieved through a 200-mesh sieve using a sieving machine to obtain a clinker powder.

[0057] The present invention will be further described below in conjunction with specific embodiments.

[0058] Embodiment 1

[0059] Preparation of cement clinker:

[0060] The raw material ratio is (mass ratio): carbide slag: quartz tailings: slag powder: fly ash: desulfurization gypsum: red mud = 68.42: 5.26: 15.79: 3.16: 5.26: 2.1.

[0061] According to the above method 2 disclosed in the present invention, after firing and grinding, the results are shown in Table 1. The calcium-silicon ratio of the clinker powder is 3.35, which is close to the calcium-silicon ratio of conventional 525 cement (3.22), and the aluminum salt content is slightly lower than that of 525 cement. Under standard conditions, the performance of the prepared specimen after 28 days is similar to that of the 525 cement specimen, and a certain amount of slag and fly ash can be mixed to prepare composite cement.

[0062] Embodiment 2

[0063] Preparation of cement clinker:

[0064] The raw material ratio is (mass ratio): carbide slag: quartz tailings: slag powder: fly ash: desulfurized gypsum: red mud = 62:8:15:5:5:5.

[0065] According to the above-mentioned Method 2 disclosed in the present invention, after firing and grinding, the results are shown in Table 1. The calcium-silicon ratio of the clinker powder is 3.11, which is between that of conventional 425 and 525 cements, and the aluminum salt content is slightly higher than that of 425 and 525 cements. Under standard conditions, the 28-day performance of the prepared specimens is similar to that of 425-cement specimens, and a certain amount of slag can be added for mixing to prepare composite cement.

[0066] Example 3

[0067] Preparation of cement clinker:

[0068] The raw material ratio (by mass) is: carbide slag∶quartz tailings∶slag powder∶fly ash∶desulfurized gypsum∶red mud = 65∶10∶15∶3∶5∶2.

[0069] According to the above-mentioned Method 2 disclosed in the present invention, after firing and grinding, the results are shown in Table 1. The calcium-silicon ratio of the clinker powder is 2.62, which is lower than that of conventional 425, and the aluminum salt content is between that of 425 and 525 cements. Under standard conditions, the 28-day performance of the prepared specimens is lower than that of 425-cement specimens and higher than that of 325-cement specimens, and it is not recommended to be mixed with slag, fly ash, etc.

[0070] The composition and content of the cement clinker prepared in each of the above examples are shown in Table 1 below.

[0071] Table 1 Composition and content of the cement clinker prepared in each example

[0072] Material <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO Ca / Si 28-day strength 425 cement 21.87％ 3.02％ 59.07％ 2.89 44.3 MPa 525 cement 21.50％ 6.30％ 64.80％ 3.22 56.1 MPa Example 1 21.49％ 5.60％ 67.32％ 3.35 55.7 MPa Example 2 20.88％ 6.90％ 60.62％ 3.11 43.6 MPa Example 3 25.96％ 5.28％ 63.25％ 2.62 38.2 MPa

[0073] The above-described examples are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-component solid waste cement clinker, characterized in that: By weight parts, it includes: 60 - 70 parts of carbide slag or 62 - 78 parts of papermaking white mud, 5 - 10 parts of quartz tailings or other silica-containing tailings, 10 - 25 parts of slag powder, 3 - 10 parts of fly ash, 5 - 8 parts of desulfurized gypsum, and 2 - 8 parts of red mud.

2. The multi-component solid waste cement clinker according to claim 1, characterized in that: In the fly ash, the SiO2 content is 20 - 62%, the Al2O3 content is 10 - 40%, and the CaO content is 1 - 45%; in the carbide slag, the CaO content is 60 - 80%; in the quartz tailings, the SiO2 content is greater than 70%; in the red mud, the SiO2 content is 15 - 20%, the Al2O3 content is 10 - 20%, the CaO content is 5 - 10%, and the Fe2O3 content is 20 - 60%; in the slag powder, the SiO2 content is 30 - 40%, the Al2O3 content is 15 - 25%, and the CaO content is 35 - 45%; in the desulfurized gypsum, the CaSO4·2H2O content is greater than 90%.

3. A multi-component solid waste cement clinker according to claim 1, characterized in that: In the papermaking white mud, the calcium carbonate content is 80 - 90%, the SiO2 content is 7 - 8%, and the alumina content is 3 - 4%; in the other silica-containing tailings, the SiO2 content is greater than 90%, and when the SiO2 content is lower than 90%, the addition amount of the other silica-containing tailings is 5 - 15 parts.

4. The preparation method of the multi-component solid waste cement clinker according to any one of claims 1 to 3, characterized in that: It includes the following steps: (1) After drying the raw materials of carbide slag or papermaking white mud, quartz tailings or other silica-containing tailings, slag powder, fly ash, desulfurized gypsum and red mud, carry out mixed grinding and pass through a 200 - 300 mesh sieve to obtain raw meal. (2) After pressing the raw meal into cakes, carry out high-temperature calcination, and after the calcination is completed, carry out rapid cooling. (3) After cooling, carry out grinding and pass through a 200 - 300 mesh sieve to obtain the clinker powder.

5. The preparation method according to claim 4, characterized in that: In step (1), dry at 75 - 85°C for 3 - 5 h.

6. The preparation method according to claim 4, characterized in that: In step (1), first grind the quartz tailings or other silica-containing tailings, then add red mud and continue grinding, add carbide slag or papermaking white mud, slag powder, fly ash and desulfurized gypsum for mixed grinding, and after the grinding is completed, stir and mix the ground raw meal.

7. The preparation method according to claim 5 or 6, characterized in that: In step (2), spray water on the raw meal, stir evenly, press into cakes and dry; or directly press the raw meal powder into cakes.

8. The preparation method according to claim 7, characterized in that: In step (2), the calcination process is: heat up to 1000 ± 5°C at a rate of 8 ± 2°C / min, then heat up to 1450 ± 5°C at a rate of 5 ± 2°C / min and calcine for 30 - 45 min.