Method for synergistically preparing green Portland cement clinker by utilizing multi-element solid waste

Abstract

A method for synergistically preparing green Portland cement clinker by utilizing multi-element solid waste comprises the following steps: (1) obtaining raw materials of limestone, silica, phosphorite beneficiation powder, copper tailings, ferroalloy slag and coal-fired slag, burdening according to silicate, and mixing and grinding to obtain a raw material; (2) preheating the obtained raw material by a preheater, and then feeding the raw material into a decomposing furnace for decomposing; (3) calcining in a rotary kiln after decomposition to obtain green Portland cement clinker; the method has the beneficial effects that 1, the copper tailings are doped, so that the burnability of the raw material is improved, and the cost of the raw material is reduced; 2, the content of f-CaO in the clinker can be reduced, the compressive strength, compactness, water resistance and stability of the clinker can be improved, the quality of the clinker is improved, and the coal consumption of clinker sintering is reduced; thirdly, after the copper tailings are used for replacing a part of ferroalloy slag, the content of water-soluble hexavalent chromium in the cement is reduced; and 4, by doping the coal-fired slag, the grindability of the raw material can be improved, the quality of the clinker is improved, the coal consumption of clinker sintering is reduced, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of cement clinker technology, and more specifically to a method for preparing green silicate cement clinker using a combination of solid wastes. Background Technology

[0002] The "Limits and Determination Methods for Water-Soluble Hexavalent Chromium (VI) in Cement" (GB31893-2015) stipulates that the content of water-soluble hexavalent chromium in cement shall not exceed 10.00 mg / kg. Water-soluble hexavalent chromium (Cr(VI)) is one of the most toxic heavy metals in cement. It can cause harm to the human body through skin contact, inhalation, and environmental contact. With people paying more and more attention to environmental and health issues, the problem of hexavalent chromium in cement has also received more and more attention. The main sources of chromium in cement clinker are: (1) Raw and fuel materials, such as limestone, sandstone, clay, iron corrective materials, coal, etc., often contain a certain amount of chromium. (2) Crushing and grinding systems, such as various crushers of raw materials and grinding media of grinding systems, all contain a certain amount of chromium. (3) Kiln systems, such as castables, hangers, refractory bricks, etc., all contain a certain amount of chromium.

[0003] Existing methods for reducing the water-soluble hexavalent chromium content in cement using chemical additives mainly include: reducing agent method, chemical curing method, and water-reducing agent inhibition method. However, these methods all have drawbacks such as increased cost, poor stability, and difficulty in operation.

[0004] For many years, traditional cement production enterprises have mostly used ferroalloy slag as an iron correction material. This material has the following shortcomings in use: First, the high chromium content makes it difficult to control the water-soluble hexavalent chromium (Cr(VI)) in cement; second, the material has poor grindability, resulting in large wear on the grinding rollers (roller press) of the raw meal vertical mill, increased welding costs, and high power consumption in the raw meal grinding process; third, the high content of water-soluble hexavalent chromium (Cr(VI)) affects the stability of cement clinker.

[0005] Therefore, existing cement clinker production technologies still suffer from problems such as high power consumption in the raw material process, high raw material costs, high content of water-soluble hexavalent chromium (Cr(VI)), and poor clinker stability. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing green silicate cement clinker by using multiple solid wastes in a synergistic manner, so as to solve the problems of high power consumption, high raw material cost, high content of water-soluble hexavalent chromium (Cr(VI)) and poor clinker stability in the raw material process of cement clinker production technology.

[0007] The technical solution adopted by the present invention to solve the technical problem is to provide a method for preparing green silicate cement clinker by using multiple solid wastes, including the following steps: (1) obtaining limestone, silica, phosphate rock beneficiation powder, copper tailings, ferroalloy slag and coal-fired furnace slag as raw materials, mixing and grinding them according to silicate proportions to obtain raw meal; (2) the obtained raw meal is preheated by a preheater and then decomposed in a decomposition furnace; (3) after decomposition, it is calcined in a rotary kiln to obtain green silicate cement clinker.

[0008] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic process. In step (1), the raw meal required for preparing the cement clinker contains 79.77% limestone, 7.02% silica, 4.59% phosphate rock beneficiation powder, 2.54% copper tailings, 0.86% ferroalloy slag, and 5.22% coal-fired slag.

[0009] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing. The chemical composition and content of the copper tailings in the raw materials are as follows: LOSS content is -3.8%, SiO2 content is 27.32%, Al2O3 content is 7.97%, Fe2O3 content is 50.70%, CaO content is 8.94%, MgO content is 3.58%, SO3 content is 2.62%, K2O content is 0.66%, Na2O content is 0.27%, and moisture content is 8.78%.

[0010] This invention provides a method for preparing green silicate cement clinker using a combination of solid wastes. The chemical composition and content of the coal-fired slag in the raw materials are as follows: LOSS content is 3.64%, SiO2 content is 50.06%, Al2O3 content is 29.91%, Fe2O3 content is 6.96%, CaO content is 6.43%, MgO content is 1.63%, SO3 content is 0.52%, K2O content is 1.11%, Na2O content is 0.58%, and moisture content is 14.98%.

[0011] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing. The chemical composition and content of the phosphate rock powder in the raw material are as follows: LOSS content 38.34%, SiO2 content 4.78%, Al2O3 content 1.63%, Fe2O3 content 2.00%, CaO content 29.84%, MgO content 18.28%, SO3 content 1.75%, K2O content 0.28%, Na2O content 0.22%, and moisture content 11.12%.

[0012] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing. In the raw meal required to prepare the cement clinker, in step (1): the content of limestone is 81.11%, the content of shale is 1.57%, the content of silica is 4.24%, the content of phosphate rock beneficiation powder is 4.44%, the content of copper tailings is 2.26%, the content of ferroalloy slag is 1.13%, and the content of coal-fired slag is 5.25%.

[0013] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing. The chemical composition and content of the copper tailings in the raw materials are as follows: LOSS content is -4.38%, SiO2 content is 35.1%, Al2O3 content is 5.62%, Fe2O3 content is 52.70%, CaO content is 3.23%, MgO content is 3.77%, SO3 content is 2.20%, K2O content is 0.70%, Na2O content is 0.17%, and moisture content is 9.78%.

[0014] This invention provides a method for preparing green silicate cement clinker using a combination of solid wastes. The chemical composition and content of the coal-fired slag in the raw materials are as follows: LOSS content is 3.30%, SiO2 content is 48.50%, Al2O3 content is 27.12%, Fe2O3 content is 7.61%, CaO content is 6.23%, MgO content is 1.31%, SO3 content is 0.66%, K2O content is 1.26%, Na2O content is 0.81%, and moisture content is 14.26%.

[0015] This invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing. The chemical composition and content of the phosphate rock powder in the raw material are as follows: LOSS content is 1.38%, SiO2 content is 48.50%, Al2O3 content is 9.58%, Fe2O3 content is 13.41%, CaO content is 45.26%, MgO content is 6.40%, SO3 content is 2.45%, K2O content is 0.83%, Na2O content is 0.34%, and moisture content is 5.61%.

[0016] The present invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic processing, comprising the following steps: (1) obtaining the limestone, silica, phosphate rock beneficiation powder, copper tailings, ferroalloy slag, and coal-fired slag as raw materials, mixing and grinding them according to silicate proportions to obtain raw meal; (2) preheating the obtained raw meal in a preheater and then decomposing it in a decomposition furnace; (3) calcining the decomposed raw meal in a rotary kiln to obtain green silicate cement clinker; the beneficial effects are: firstly, the addition of copper tailings improves the calcinability of the raw meal and reduces the cost of the raw meal; secondly, it can reduce the f-Ca content in the clinker. The addition of oxygen can improve the compressive strength, density, water resistance, and stability of clinker; thirdly, replacing part of the ferroalloy slag with copper tailings reduces the content of water-soluble hexavalent chromium (Cr(VI)) in cement; fourthly, adding coal slag can improve the grindability of raw materials, improve the quality of clinker, reduce coal consumption during clinker burning, and reduce costs; the addition of phosphate rock beneficiation powder can improve the resistance to sulfate attack by more than 30%, reduce the firing temperature by about 50°C-100°C, reduce heat consumption by 5%-8%, reduce costs, and at the same time improve clinker strength (3d strength increases by 0.6MPa-1.4MPa). Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a preferred embodiment of the present invention for a method of preparing green silicate cement clinker using multiple solid wastes. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0020] Please see Figure 1 The technical problem to be solved by the present invention is to provide a method for preparing green silicate cement clinker by utilizing multiple solid wastes, so as to solve the problems of high power consumption, high raw material cost, high content of water-soluble hexavalent chromium (Cr(VI)) and poor clinker stability in cement clinker production technology.

[0021] First, it should be noted that there is a clear transformation relationship between cement raw materials, raw meal, and clinker. Various different cement raw materials are blended in proportion and subjected to processes such as crushing, grinding, and homogenization to form a chemically homogeneous mixture; that is, the cement raw materials become cement raw meal. Further, the cement raw meal is calcined at high temperature in a rotary kiln, undergoing physicochemical changes, and ultimately forming cement clinker; that is, the cement raw meal generates the cement clinker. Because this application uses different proportions of cement raw materials, the final product is cement clinker with silicate as its main component.

[0022] Specifically, in one embodiment, the present invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic process, comprising the following steps: (1) obtaining the limestone, silica, phosphate rock beneficiation powder, copper tailings, ferroalloy slag and coal-fired slag as raw materials, mixing and grinding them according to the silicate cement clinker composition requirements to obtain raw meal; (2) the obtained raw meal is preheated by a preheater and then decomposed in a decomposition furnace; (3) after decomposition, it is calcined in a rotary kiln to obtain green silicate cement clinker.

[0023] Specifically, in S10, the limestone, silica, phosphate ore beneficiation powder, copper tailings, ferroalloy slag, and coal-fired furnace slag raw materials are obtained, mixed and ground according to silicate proportions to obtain raw meal; Furthermore, since the valuable metals in the copper tailings promote low-temperature calcination, fluxing, and mineralization, the valuable components in the copper smelting slag can be utilized as iron-based raw materials in cement production to produce silicate cement clinker, thereby realizing the resource utilization of the copper tailings and achieving energy conservation and emission reduction. Research shows that using the copper tailings as an iron-based raw material in cement production has the following advantages: 1. It can improve the hardening speed of cement. The chemical composition of the copper tailings can react with C3S and C2S in the cement, accelerating the hardening speed of the cement and promoting the early strength development of the cement; 2. The copper tailings have a good promoting effect on the calcination and mineral formation of cement clinker, which can improve the burnability of raw materials and reduce the f-CaO content in clinker. During the sintering process, it can appropriately reduce the coal consumption for clinker calcination, creating conditions for high-quality, high-yield, and low-consumption rotary kilns. 3. The copper tailings can significantly improve the physical and mechanical properties of cement clinker. After being added to cement, the copper tailings can reduce the porosity and defects in the cement, and improve the density and water resistance of the cement. The silicates, aluminates and other substances in the copper tailings can form cement clinker containing quartz, aluminates, silicates and other substances with elements such as CaO and SiO2 in the cement, thereby enhancing the compressive strength and durability of the cement and improving the quality of the cement clinker.

[0024] When ferroalloy slag is used as a corrective material for iron content, its proportion is approximately 5.5%. The chromium content in ferroalloy slag is approximately 1460 mg / kg, while the chromium content in copper tailings is approximately 344 mg / kg. This results in excessive levels of water-soluble hexavalent chromium (Cr(VI)) in the cement, exceeding 14.00%. After replacing a portion of the ferroalloy slag with copper tailings, the ferroalloy slag content decreased from 5.5% to approximately 1.0%, and the water-soluble hexavalent chromium (Cr(VI)) in the cement decreased to an average of approximately 7.5%, with the Cr(VI) content controlled below 10.00%, meeting national standards.

[0025] Therefore, by incorporating copper tailings into the cement raw materials as an iron-based raw material for cement production, energy consumption can be saved and maintenance costs of raw material equipment can be significantly reduced. If the raw material production line has an annual output of 7.5 million tons, it is estimated that 2.25 million kilowatt-hours of electricity can be saved annually.

[0026] Furthermore, research indicates that the addition of coal slag to the cement raw materials can improve the grindability of the raw meal, reduce the clinker firing temperature by approximately 50°C, and decrease coal consumption by 5.5 kg per ton, thereby directly reducing the production cost of the raw meal while ensuring the stability of the cement clinker.

[0027] Furthermore, it should be noted that research on incorporating phosphate rock beneficiation powder into raw materials shows that an appropriate amount of phosphorus can improve the cement's resistance to sulfate attack by more than 30%. The fluorine compounds in the phosphate rock beneficiation powder can lower the firing temperature by approximately 50°C-100°C, reduce heat consumption by 5%-8%, lower costs, and simultaneously improve clinker strength (3-day strength increased by 0.6MPa-1.4MPa). If 6%-8% of phosphate rock beneficiation powder is incorporated, the clinker's 3-day strength reaches over 28MPa, and the 28-day strength stabilizes at around 55MPa. Simultaneously, a solid waste disposal subsidy of 15-20 yuan per ton is obtained, further reducing costs.

[0028] Below, Scheme 0 is used as a control, and Schemes 1 and 2 are used as raw materials for cement experimental mix design to prepare cement clinker by calcination. Schemes 1 and 2 adopt the preparation method of green silicate cement clinker described in this application, while Scheme 0 adopts other methods.

[0029] Table 1 Total Chromium Content in Raw Materials Material Name Chromium content (mg / kg) limestone 0 shale 2.22 silica 38.64 Phosphate ore beneficiation powder 78.70 Copper tailings 344.45 Ferroalloy slag 628 Coal-fired furnace slag 159.79 bauxite 114.3 First, it should be noted that the total chromium content in the above-mentioned raw materials, determined by atomic absorption spectrometry, is as follows: limestone 0 mg / kg, shale 2.22 mg / kg, silica 38.64 mg / kg, phosphate rock powder 78.70 mg / kg, copper tailings 344.45 mg / kg, ferroalloy slag 628 mg / kg, coal-fired slag 159.79 mg / kg, and bauxite 114.3 mg / kg, as shown in Table 1 above.

[0030] Option 0: Furthermore, Scheme 0 provides a method for producing silicate cement clinker, comprising the following steps: (1) obtaining the limestone, silica, shale, bauxite and ferroalloy slag raw materials, mixing and grinding them according to silicate proportions to obtain raw meal; (2) preheating the obtained raw meal in a preheater and then decomposing it in a decomposition furnace; (3) calcining the decomposed raw meal in a rotary kiln to obtain green silicate cement clinker.

[0031] In step (1) of scheme 0: the content of limestone is 85%, the content of silica is 2.0%, the content of shale is 5.5%, the content of bauxite is 2.0%, and the content of ferroalloy slag is 5.5%.

[0032] Table 2 Chemical composition and content of raw materials in Scheme 0 name LOSS SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O Moisture limestone 40.13 4.21 1.54 0.54 50.87 0.70 0.57 0.27 0.16 0.86 silica 0.93 93.35 2.28 0.90 0.10 0.44 0.19 0.44 0.13 2.47 shale 4.04 69.56 13.78 4.38 1.70 1.62 0.24 3.13 0.19 5.73 bauxite 11.42 40.19 30.20 12.33 0.77 0.49 0.29 0.39 0.64 8.71 Ferroalloy slag -2.74 21.09 6.40 32.08 34.84 4.76 0.44 0.05 0.11 2.28 Further, in one embodiment, the chemical composition and content of the raw materials are specifically shown in Table 2 above. As can be seen from Table 2, in one embodiment, the chemical composition and content of the bauxite raw material are as follows: LOSS content is 11.42%, SiO2 content is 40.19%, Al2O3 content is 30.20%, Fe2O3 content is 12.33%, CaO content is 0.77%, MgO content is 0.49%, SO3 content is 0.29%, K2O content is 0.39%, Na2O content is 0.64%, and moisture content is 8.71%.

[0033] In one embodiment, the chemical composition and content of the ferroalloy slag raw material are as follows: LOSS content is -2.74%, SiO2 content is 21.09%, Al2O3 content is 6.40%, Fe2O3 content is 32.08%, CaO content is 34.84%, MgO content is 4.76%, SO3 content is 0.44%, K2O content is 0.05%, Na2O content is 0.11%, and moisture content is 2.28%.

[0034] In one embodiment, the chemical composition and content of the silica raw material are as follows: LOSS content is 0.93%, SiO2 content is 93.35%, Al2O3 content is 2.28%, Fe2O3 content is 0.90%, CaO content is 0.10%, MgO content is 0.44%, SO3 content is 0.19%, K2O content is 0.44%, Na2O content is 0.13%, and moisture content is 2.47%.

[0035] In one embodiment, the chemical composition and content of the shale raw material are as follows: LOSS content is 4.04%, SiO2 content is 69.56%, Al2O3 content is 13.78%, Fe2O3 content is 4.38%, CaO content is 1.70%, MgO content is 1.62%, SO3 content is 0.24%, K2O content is 3.13%, Na2O content is 0.19%, and moisture content is 5.73%.

[0036] In one embodiment, the chemical composition and content of the limestone raw material are as follows: LOSS content is 40.13%, SiO2 content is 4.21%, Al2O3 content is 1.54%, Fe2O3 content is 0.54%, CaO content is 50.87%, MgO content is 0.70%, SO3 content is 0.57%, K2O content is 0.27%, Na2O content is 0.16%, and moisture content is 0.86%.

[0037] Table 3 Calculation of the theoretical total chromium content of raw materials in Scheme 0

[0038] As shown in Table 3 above, the calculated chromium content of each element and its mixture in the raw materials of Scheme 0 is as follows: limestone 0 mg / kg, shale 2.22 mg / kg, bauxite 114.3 mg / kg, silica 38.64 mg / kg, ferroalloy slag 628 mg / kg, and raw materials 37.71 mg / kg.

[0039] Option 1: Specifically, in one embodiment, in step (1): the content of limestone is 79.77%, the content of silica is 7.02%, the content of phosphate rock beneficiation powder is 4.59%, the content of copper tailings is 2.54%, the content of ferroalloy slag is 0.86%, and the content of coal-fired slag is 5.22%.

[0040] Table 4 Chemical composition and content of raw materials name LOSS <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[SO3]]> K2O Na2O R2O P2O5 Moisture limestone 40.32 4.33 1.40 0.57 50.39 0.58 0.36 0.40 0.04 1.00 silica 1.07 78.04 2.16 0.11 0.18 0.18 0.11 0.31 0.10 2.03 Ferroalloy slag -2.73 19.81 6.42 30.73 40.81 5.46 0.45 0.08 0.18 2.14 Coal-fired furnace slag 3.64 50.06 29.91 6.96 6.43 1.63 0.52 1.11 0.58 14.98 Copper tailings -3.8 27.32 7.97 50.7 8.94 3.58 2.62 0.66 0.27 8.78 Phosphate ore beneficiation powder 38.34 4.78 1.63 2.0 29.84 18.28 1.75 0.28 0.22 0.4 3.0 11.12 As shown in Table 4 above, in one embodiment, the chemical composition and content of the copper tailings raw material are as follows: LOSS content is -3.8%, SiO2 content is 27.32%, Al2O3 content is 7.97%, Fe2O3 content is 50.70%, CaO content is 8.94%, MgO content is 3.58%, SO3 content is 2.62%, K2O content is 0.66%, Na2O content is 0.27%, and moisture content is 8.78%.

[0041] Experimental data show that adding an appropriate amount of copper tailings to the raw meal results in cement clinker exhibiting good later-stage strength and durability. In one embodiment, the chemical composition and content of the coal-fired slag raw material are as follows: LOSS content is 3.64%, SiO2 content is 50.06%, Al2O3 content is 29.91%, Fe2O3 content is 6.96%, CaO content is 6.43%, MgO content is 1.63%, SO3 content is 0.52%, K2O content is 1.11%, Na2O content is 0.58%, and moisture content is 14.98%.

[0042] It is understandable that by replacing some raw materials with coal-fired slag, the preparation cost of the raw meal has been successfully reduced, while the stability of the cement clinker performance has also been ensured.

[0043] In one embodiment, the chemical composition and content of the phosphate rock beneficiation powder raw material are as follows: LOSS content is 38.34%, SiO2 content is 4.78%, Al2O3 content is 1.63%, Fe2O3 content is 2.00%, CaO content is 29.84%, MgO content is 18.28%, SO3 content is 1.75%, K2O content is 0.28%, Na2O content is 0.22%, and moisture content is 11.12%.

[0044] In one embodiment, the chemical composition and content of the limestone raw material are as follows: LOSS content is 40.32%, SiO2 content is 4.33%, Al2O3 content is 1.4%, Fe2O3 content is 0.57%, CaO content is 50.39%, MgO content is 0.58%, SO3 content is 0.36%, K2O content is 0.40%, Na2O content is 0.04%, and moisture content is 1%.

[0045] In one embodiment, the chemical composition and content of the silica raw material are as follows: LOSS content is 1.07%, SiO2 content is 78.04%, Al2O3 content is 2.16%, Fe2O3 content is 0.11%, CaO content is 0.18%, MgO content is 0.18%, SO3 content is 0.11%, K2O content is 0.31%, Na2O content is 0.10%, and moisture content is 2.03%.

[0046] In one embodiment, the chemical composition and content of the ferroalloy slag raw material are as follows: LOSS content is -2.73%, SiO2 content is 19.81%, Al2O3 content is 6.42%, Fe2O3 content is 30.73%, CaO content is 40.81%, MgO content is 5.46%, SO3 content is 0.45%, K2O content is 0.08%, Na2O content is 0.18%, and moisture content is 2.14%.

[0047] Table 5 Chemical composition and content of raw materials name LOSS SiO2 AL2O3 Fe2O3 CaO MgO ∑ KH N P Sample 1 34.77 14.26 3.33 2.21 43.29 1.11 98.97 0.929 2.59 1.50 Furthermore, after the cement raw materials are used to generate the cement raw meal, the chemical composition and content of the cement raw meal are shown in Table 5 above.

[0048] Furthermore, the chromium content of the raw material in Scheme 1 can be calculated.

[0049] Table 6 Calculation of the theoretical total chromium content of raw materials in Scheme 1

[0050] As shown in Table 6 above, the calculated chromium content of each element and its mixture in the raw materials of Scheme 1 is as follows: limestone 0 mg / kg, phosphate rock beneficiation powder 3.61 mg / kg, copper tailings 8.75 mg / kg, silica 2.71 mg / kg, ferroalloy slag 5.40 mg / kg, coal-fired slag 8.34 mg / kg, and raw materials 28.81 mg / kg.

[0051] Option 2: Furthermore, in another embodiment, in step (1): the content of limestone is 81.11%, the content of shale is 1.57%, the content of silica is 4.24%, the content of phosphate rock beneficiation powder is 4.44%, the content of copper tailings is 2.26%, the content of ferroalloy slag is 1.13%, and the content of coal-fired slag is 5.25%.

[0052] Specifically, in another embodiment, the chemical composition and content of the raw materials are shown in Table 7 below.

[0053] Table 7 Chemical composition and content of raw materials name LOSS SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O Moisture limestone 41.31 3.02 1.28 0.29 52.10 0.51 0.10 0.29 0.09 0.77 silica 0.52 95.74 1.32 0.47 0.26 0.22 0.14 0.20 0.11 2.00 Ferroalloy slag -1.74 23.14 6.04 32.32 32.60 4.79 0.53 0.12 0.14 2.74 shale 3.06 73.82 11.79 4.84 0.95 1.41 0.11 2.33 0.26 4.70 Phosphate ore beneficiation powder 1.38 17.79 9.58 13.41 45.26 6.40 2.45 0.83 0.34 5.61 Coal-fired furnace slag 3.30 48.50 27.12 7.61 6.23 1.31 0.66 1.26 0.81 14.26 Copper tailings -4.38 35.1 5.62 52.7 3.23 3.77 2.2 0.7 0.17 9.78 As shown in Table 7 above, in one embodiment, the chemical composition and content of the copper tailings raw material are as follows: LOSS content is -4.38%, SiO2 content is 35.1%, Al2O3 content is 5.62%, Fe2O3 content is 52.70%, CaO content is 3.23%, MgO content is 3.77%, SO3 content is 2.20%, K2O content is 0.70%, Na2O content is 0.17%, and moisture content is 9.78%.

[0054] In one embodiment, the chemical composition and content of the coal-fired slag raw material are as follows: LOSS content is 3.30%, SiO2 content is 48.50%, Al2O3 content is 27.12%, Fe2O3 content is 7.61%, CaO content is 6.23%, MgO content is 1.31%, SO3 content is 0.66%, K2O content is 1.26%, Na2O content is 0.81%, and moisture content is 14.26%.

[0055] In one embodiment, the chemical composition and content of the phosphate rock beneficiation powder raw material are as follows: LOSS content is 1.38%, SiO2 content is 48.50%, Al2O3 content is 9.58%, Fe2O3 content is 13.41%, CaO content is 45.26%, MgO content is 6.40%, SO3 content is 2.45%, K2O content is 0.83%, Na2O content is 0.34%, and moisture content is 5.61%.

[0056] In one embodiment, the chemical composition and content of the limestone raw material are as follows: LOSS content is 41.31%, SiO2 content is 3.02%, Al2O3 content is 1.28%, Fe2O3 content is 0.29%, CaO content is 52.10%, MgO content is 0.51%, SO3 content is 0.10%, K2O content is 0.29%, Na2O content is 0.09%, and moisture content is 0.77%.

[0057] In one embodiment, the chemical composition and content of the silica raw material are as follows: LOSS content is 0.52%, SiO2 content is 95.74%, Al2O3 content is 1.32%, Fe2O3 content is 0.47%, CaO content is 0.26%, MgO content is 0.22%, SO3 content is 0.14%, K2O content is 0.20%, Na2O content is 0.11%, and moisture content is 2.00%.

[0058] In one embodiment, the chemical composition and content of the ferroalloy slag raw material are as follows: LOSS content is -1.74%, SiO2 content is 23.14%, Al2O3 content is 6.04%, Fe2O3 content is 32.32%, CaO content is 32.60%, MgO content is 4.79%, SO3 content is 0.53%, K2O content is 0.12%, Na2O content is 0.14%, and moisture content is 2.74%.

[0059] In one embodiment, the chemical composition and content of the shale raw material are as follows: LOSS content is 3.06%, SiO2 content is 73.82%, Al2O3 content is 11.79%, Fe2O3 content is 4.84%, CaO content is 0.95%, MgO content is 1.41%, SO3 content is 0.11%, K2O content is 2.33%, Na2O content is 0.26%, and moisture content is 4.70%.

[0060] Furthermore, after the cement raw materials are used to generate the cement raw meal, the chemical composition and content of the cement raw meal are shown in Table 8 below.

[0061] Table 8 Chemical composition and content of raw materials name LOSS SiO2 AL2O3 Fe2O3 CaO MgO ∑ KH N P Sample 2 34.7 14.17 3.44 2.23 43.2 1.17 98.91 0.926 2.5 1.55 Furthermore, the chromium content of the raw material in Scheme 2 can be calculated.

[0062] Table 9 Calculation of the theoretical total chromium content of raw materials in Scheme 2

[0063] As shown in Table 9 above, the calculated chromium content of each element and its mixture in the raw materials of Scheme 2 is as follows: limestone 0 mg / kg, phosphate rock beneficiation powder 3.49 mg / kg, copper tailings 7.78 mg / kg, silica 1.63 mg / kg, ferroalloy slag 7.09 mg / kg, coal-fired slag 8.39 mg / kg, and raw materials 28.41 mg / kg.

[0064] Table 10 Comparison of water-soluble hexavalent chromium (VI) content in raw meal and cement under different batching schemes sample Total chromium content in raw materials (mg / kg) Content of water-soluble hexavalent chromium (VI) in cement (mg / kg) Sample 0 37.71 14.2 Sample 1 28.81 7.8 Sample 2 28.41 7.2 As can be seen from the comparison of the chromium content in raw meal and the water-soluble hexavalent chromium (VI) content in cement in different batching schemes in Table 10 above, the content of both total chromium (mg / kg) in raw meal and water-soluble hexavalent chromium (VI) in cement is sample 2 < sample 1 < sample 0.

[0065] Therefore, the green silicate cement raw meal prepared by the method of this application has a significantly reduced total chromium content, and the water-soluble hexavalent chromium (Cr(VI)) content in the cement is controlled within 10.00%, which meets the national standard requirements.

[0066] S20, the obtained raw material is preheated in a preheater and then decomposed in a decomposition furnace; S30, after decomposition, enters a rotary kiln for calcination to produce green silicate cement clinker.

[0067] Furthermore, in one embodiment, after the cement raw meal is transformed into the cement clinker, the chemical composition and content of the cement raw meal are shown in Table 11 below.

[0068] Table 11 Chemical composition, mineral composition and content of clinker name LOSS SiO2 AI2O3 Fe2O3 CaO MgO SO3 ∑ fc KH KH- N P C3S C2S C3A C4AF CLˉ K2O Na2O alkali Sample 1 0.19 22.07 5.22 3.64 65.40 1.90 0.53 98.95 1.16 0.893 0.874 2.50 1.44 52.08 24.00 7.65 11.07 0.020 0.56 0.14 0.69 Furthermore, after the cement clinker is produced, the various physical performance indicators of the cement clinker are tested as shown in Table 12 below.

[0069] Table 12 Physical property testing of clinker

[0070] Furthermore, in another embodiment, after the cement raw meal is transformed into the cement clinker, the chemical composition and content of the cement raw meal are shown in Table 13 below.

[0071] Table 13 Chemical composition, mineral composition and content of clinker name LOSS SiO2 AI2O3 Fe2O3 CaO MgO SO3 ∑ fc KH KH- N P C3S C2S C3A C4AF CLˉ K2O Na2O alkali Sample 2 0.24 22.08 5.53 3.64 65.43 1.80 0.42 99.14 0.88 0.890 0.876 2.46 1.47 52.70 23.56 8.01 11.05 0.019 0.55 0.15 0.510 Furthermore, after the cement clinker is produced, the various physical performance indicators of the cement clinker are tested as shown in Table 14 below.

[0072] Table 14 Physical property testing of clinker

[0073] Furthermore, the various economic indicators of the three ingredient schemes were compared.

[0074] Table 15 Comparison of economic and technical indicators of raw meals with different ingredient formulations sample Vertical mill production in Taiwan (t / h) Vertical mill power consumption (kWh / t) 28-day compressive strength of clinker (MPa) Standard coal consumption for clinker (kg / t) Sample 0 446 14.6 54.6 99.48 Sample 1 502 13.4 57.5 98.8 Sample 2 490 13.7 57 97.7 As shown in Table 15 above, Sample 0 prepared using Scheme 0 has a vertical mill output of 446 t / h, a vertical mill power consumption of 14.6 kWh / t, a 28-day compressive strength of cement clinker of 54.6 MPa, and a standard coal consumption of clinker of 99.48 kg / t; Sample 1 prepared using Scheme 1 has a vertical mill output of 502 t / h, a vertical mill power consumption of 13.4 kWh / t, a 28-day compressive strength of cement clinker of 57.5 MPa, and a standard coal consumption of clinker of 98.8 kg / t; Sample 2 prepared using Scheme 2 has a vertical mill output of 490 t / h, a vertical mill power consumption of 13.7 kWh / t, a 28-day compressive strength of cement clinker of 57 MPa, and a standard coal consumption of clinker of 97.7 kg / t. Therefore, the power consumption of the raw material vertical mill in Sample 1 and Sample 2 is less than that in Sample 0, and the standard coal consumption of cement clinker in Sample 1 and Sample 2 is less than that in Sample 0. In other words, the method for preparing green silicate cement clinker described in this application can reduce the power consumption of the raw material process and the coal consumption of clinker, thereby saving production costs.

[0075] The present invention provides a method for preparing green silicate cement clinker using multiple solid wastes in synergistic process, comprising the following steps: (1) obtaining limestone, silica, phosphate rock beneficiation powder, copper tailings, ferroalloy slag and coal-fired furnace slag as raw materials, mixing and grinding them according to silicate proportions to obtain raw meal; (2) the obtained raw meal is preheated in a preheater and then decomposed in a decomposition furnace; (3) after decomposition, it is calcined in a rotary kiln to obtain green silicate cement clinker; the beneficial effects are: firstly, the addition of copper tailings improves the calcinability of the raw meal and reduces the cost of the raw meal; secondly, it can reduce the content of f-CaO in the clinker, which can improve the compressive strength of the clinker. The addition of copper tailings to replace part of the ferroalloy slag reduces the content of water-soluble hexavalent chromium (Cr(VI)) in cement. Furthermore, the addition of coal-fired slag improves the grindability of raw materials, enhances clinker quality, reduces clinker coal consumption, and lowers costs. Finally, the addition of phosphate rock powder increases resistance to sulfate attack by more than 30%, lowers the firing temperature by approximately 50°C-100°C, reduces heat consumption by 5%-8%, lowers costs, and simultaneously increases clinker strength (28-day compressive strength increases by 2.4MPa-2.9MPa).

[0076] Other parts of this invention that are not detailed herein are all prior art and will not be described further here.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synergistically preparing green silicate cement clinker using multiple solid wastes, characterized in that, Includes the following steps: (1) Obtain raw materials such as limestone, silica, phosphate rock beneficiation powder, copper tailings, ferroalloy slag and coal-fired furnace slag, mix and grind them according to silicate batching to obtain raw meal; (2) The obtained raw meal is preheated by a preheater and then decomposed in a decomposition furnace; (3) After decomposition, it is calcined in a rotary kiln to obtain green silicate cement clinker.

2. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 1, characterized in that, In step (1): the content of limestone is 79.77%, the content of silica is 7.02%, the content of phosphate rock beneficiation powder is 4.59%, the content of copper tailings is 2.54%, the content of ferroalloy slag is 0.86%, and the content of coal-fired slag is 5.22%.

3. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 2, characterized in that, The chemical composition and content of the copper tailings in the raw materials are as follows: LOSS content is -3.8%, SiO2 content is 27.32%, Al2O3 content is 7.97%, Fe2O3 content is 50.70%, CaO content is 8.94%, MgO content is 3.58%, SO3 content is 2.62%, K2O content is 0.66%, Na2O content is 0.27%, and moisture content is 8.78%.

4. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 2, characterized in that, The chemical composition and content of the coal-fired slag in the raw materials are as follows: LOSS content is 3.64%, SiO2 content is 50.06%, Al2O3 content is 29.91%, Fe2O3 content is 6.96%, CaO content is 6.43%, MgO content is 1.63%, SO3 content is 0.52%, K2O content is 1.11%, Na2O content is 0.58%, and moisture content is 14.98%.

5. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 2, characterized in that, The chemical composition and content of the phosphate rock beneficiation powder in the raw materials are as follows: LOSS content is 38.34%, SiO2 content is 4.78%, Al2O3 content is 1.63%, Fe2O3 content is 2.00%, CaO content is 29.84%, MgO content is 18.28%, SO3 content is 1.75%, K2O content is 0.28%, Na2O content is 0.22%, and moisture content is 11.12%.

6. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 1, characterized in that, In step (1): the content of limestone is 81.11%, the content of shale is 1.57%, the content of silica is 4.24%, the content of phosphate rock beneficiation powder is 4.44%, the content of copper tailings is 2.26%, the content of ferroalloy slag is 1.13%, and the content of coal-fired slag is 5.25%.

7. The method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 6, characterized in that, The chemical composition and content of the copper tailings in the raw materials are as follows: LOSS content is -4.38%, SiO2 content is 35.1%, Al2O3 content is 5.62%, Fe2O3 content is 52.70%, CaO content is 3.23%, MgO content is 3.77%, SO3 content is 2.20%, K2O content is 0.70%, Na2O content is 0.17%, and moisture content is 9.78%.

8. A method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 6, characterized in that, The chemical composition and content of the coal-fired slag in the raw materials are as follows: LOSS content is 3.30%, SiO2 content is 48.50%, Al2O3 content is 27.12%, Fe2O3 content is 7.61%, CaO content is 6.23%, MgO content is 1.31%, SO3 content is 0.66%, K2O content is 1.26%, Na2O content is 0.81%, and moisture content is 14.26%.

9. A method for synergistically preparing green silicate cement clinker using multiple solid wastes according to claim 6, characterized in that, The chemical composition and content of the phosphate rock beneficiation powder in the raw materials are as follows: LOSS content is 1.38%, SiO2 content is 48.50%, Al2O3 content is 9.58%, Fe2O3 content is 13.41%, CaO content is 45.26%, MgO content is 6.40%, SO3 content is 2.45%, K2O content is 0.83%, Na2O content is 0.34%, and moisture content is 5.61%.

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