A method and product for preparing a composite coal-saving synergist for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner.

Abstract

This application provides a method and product for preparing a composite coal-saving synergist for cement clinker using undisturbed fluorine-containing sludge and other solid wastes in a synergistic and low-energy-consumption manner. Fluorine-containing sludge, steel slag, municipal solid waste incineration fly ash, nickel-iron slag, and aluminum ash slag are used as main raw materials. Through a series of processes including raw material pretreatment, pre-homogenization, material proportioning design, extrusion granulation and activation-induced product formation, coagulation, self-hardening, self-curing, and self-drying, a composite coal-saving synergist for calcining high-quality cement clinker is prepared. This method avoids the drawbacks of high energy consumption and inefficient utilization of dried fluorine-containing sludge during the drying process. It fully utilizes the effective components in various solid wastes, including fluorine-containing sludge, to achieve synergistic effects, enabling large-scale, low-energy, and high-efficiency treatment of fluorine-containing sludge and other industrial solid wastes.

Description

Technical Field

[0001] This invention relates to the field of energy conservation in cement clinker production and resource utilization of waste, specifically a method for preparing a composite coal-saving synergist for cement clinker using fluorine-containing sludge in conjunction with industrial solid waste. Background Technology

[0002] Due to the decomposition of limestone and high coal consumption during the calcination process of cement clinker, producing 1 ton of clinker requires the emission of approximately 0.8 tons of carbon dioxide. With the emphasis on energy conservation and emission reduction in the cement industry, its transformation is urgent, necessitating the implementation of energy-saving and emission-reduction measures. Furthermore, limestone resources, the main raw material for cement clinker production, are dwindling, forcing the cement industry to rely on low-grade limestone raw materials with high magnesium, high silicon, and high sulfur content. Poor limestone quality easily leads to a series of problems, including unstable kilns, high coal consumption, and poor clinker quality, severely hindering the sustainable development of the cement industry.

[0003] The use of mineralizers in cement raw materials is an effective means to improve clinker strength and reduce energy consumption in clinker production. Fluorite is a common mineralizer; the calcium fluoride component in fluorite can reduce the viscosity of the liquid phase during clinker calcination, promoting the formation of cement clinker phases, thereby reducing standard coal consumption and increasing clinker strength. In the past, fluorite was commonly used in vertical kiln production, but its usage was generally 2% or even higher. Due to the large amount of fluorine, it easily escapes into the air, polluting it. On the other hand, fluorite resources are becoming increasingly scarce and unevenly distributed, making it difficult to meet the mineralizer needs of the cement industry.

[0004] Reports indicate that the use of traditional fluorite mineralizers in rotary kiln systems can lead to system scaling and kiln ring formation, causing equipment corrosion and affecting kiln operation. Furthermore, the high-temperature calcination of fluorite in rotary kilns may result in fluoride emissions, thus impacting the environment. Therefore, the solidification of fluorine during cement calcination is also crucial.

[0005] Fluorinated sludge is a major waste product in the photovoltaic and electronic device manufacturing industries. Currently, the vast majority of fluorinated sludge is disposed of through landfill and surface stockpiling. This not only wastes valuable land resources, but also allows fluoride and heavy metal ions in the pollutants to leach out and be absorbed by plants, leading to water and soil pollution. Given the characteristics of fluorinated sludge, its resource utilization rate is less than 20%. The main component of fluorinated sludge is calcium fluoride, which has the potential to be used as a mineralizing agent. However, due to the high moisture content of fluorinated sludge and its extremely slow moisture loss during natural stockpiling, dewatering efficiency is low, and most of the moisture is difficult to remove through natural drying. The filtration and drying dewatering processes for sludge inevitably lead to huge energy consumption, resulting in high drying costs and affecting utilization efficiency and value.

[0006] CN102531429B discloses a method for co-processing fluorine-containing sludge in a cement kiln. The method involves drying fluorine-containing sludge with a moisture content of 40-80% and then adding it to raw materials at a dosage of 1-5%. The resulting cement meets various performance standards. However, this technology requires drying the sludge, consuming significant energy and resulting in high production costs. Furthermore, the mineralizer enhancement effect is not significant, impacting its utilization value. CN115849742A discloses a method for preparing clinker mineralizers using fluorine-containing sludge in conjunction with heavy metal oxides. This method involves blending dried sludge with trace heavy metal elements to prepare powdered mineralizers. However, this technology also requires initial sludge drying. Additionally, the required trace heavy metal powder is costly, has poor mixing uniformity, and is difficult to utilize on a large scale. Neither of these patents addresses the issue of fluorine escape during clinker calcination after incorporating dried fluorine-containing sludge, nor does it propose a corresponding solution. Summary of the Invention

[0007] This invention addresses the technical problems of poor kiln conditions, high energy consumption, low product strength, and the difficulty in directly applying undisturbed fluorine-containing sludge during clinker calcination caused by low-quality raw materials. It provides a method for the harmless treatment and high-value-added application of undisturbed fluorine-containing sludge during clinker calcination. Through raw material pretreatment, pre-homogenization, material proportioning design, extrusion granulation and induced product formation, and self-hardening and self-curing, composite coal-saving and efficiency-enhancing agent granules for cement clinker are prepared. The resulting product improves kiln conditions, lowers clinker calcination temperature, increases calcium carbonate decomposition efficiency, increases kiln output, improves clinker quality, solidifies fluorine, reduces coal consumption, and lowers carbon emissions. It is suitable for calcining high-strength cement clinker using low-grade limestone raw materials such as high-silicon, high-magnesium, and low-calcium materials, and low-quality coal. It is also suitable for cement rotary kilns with poor kiln conditions, unstable operation, high coal consumption, low clinker strength, and low output.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A method for preparing a composite coal-saving synergist for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner, the method comprising the following steps:

[0010] (1) Batching and pre-homogenization of raw materials: Weigh the original fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel iron slag powder, aluminum ash slag powder and temperature and humidity regulating coagulant, and mix the raw materials evenly through a mixer;

[0011] (2) Dual-mold extrusion granulation: The material uniformly mixed in step (1) is extruded and granulated by a dual-mold granulator. The granulated particles are stacked layer by layer naturally, self-hardening, self-heating and self-drying, to obtain a composite coal-saving efficiency enhancer product.

[0012] In the technical solution of the present invention, the fluorine-containing sludge mentioned in step (1) is the main industrial by-product of photovoltaic enterprises without treatment; steel slag is the by-product of converter steelmaking process; fly ash from municipal solid waste incineration is the by-product generated during municipal solid waste treatment; nickel-iron slag is the solid waste generated during nickel-iron alloy smelting process; and aluminum ash slag is the by-product of aluminum electrolysis process.

[0013] In the technical solution of this invention, the moisture content of the original fluoride-containing sludge is 30-80%, and its calcium fluoride content is 20-70%.

[0014] In the technical solution of the present invention, the weight parts of the fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel-iron slag powder, aluminum ash slag powder and temperature and humidity regulating coagulant in step (1) are 50~80 parts, 5~30 parts, 5~20 parts, 5~20 parts, 5~10 parts and 0.02~0.5 parts respectively.

[0015] In some preferred technical solutions: further preferred: the weight parts of the fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel-iron slag powder, aluminum ash powder and temperature and humidity regulating coagulant in step (1) are 50~80 parts, 5~20 parts, 5~15 parts, 5~10 parts, 5~10 parts and 0.1~0.5 parts respectively.

[0016] In the technical solution of the present invention, the temperature and humidity regulating coagulant in step (1) is composed of 30-50 parts by weight of hydroxyethyl diisopropanolamine, 10-30 parts by weight of lithium sulfate, 10-30 parts by weight of sulfonated melamine formaldehyde condensate, 10-30 parts by weight of polyacrylol, and 10-30 parts by weight of sodium dodecyl sulfate.

[0017] In the technical solution of this invention, in step (2), the fluorine content (F / (Al + Fe)) in the raw material is controlled to be 0.06~0.20, and the crystal doping control rate (crystal doping element / (Al + Fe)) is 0.20~0.65; the crystal doping element is P, S, Mg, Zn, Pb, Cu, Cr, Mn, and the crystal doping element has the function of inducing tricalcium silicate crystal transformation and crystal structure distortion.

[0018] In the technical solution of the present invention, the calcium fluoride content in the composite coal-saving efficiency enhancer in step (2) is 20-55%, and the moisture content is not higher than 10%.

[0019] In the technical solution of the present invention, the granulator mentioned in step (2) is a dual-mold granulator with a granulation pressure of 5~10 MPa and a scraper cutting particle size of 3~8 mm.

[0020] In the technical solution of this invention, in step (3), when the composite coal-saving synergist is used in the production of clinker in a cement kiln, the amount of the composite coal-saving synergist added to the raw meal is 0.05~1.5% by mass percentage;

[0021] A composite coal-saving synergist for cement clinker is prepared by synergistic low-energy consumption preparation of multiple solid wastes using undisturbed fluoride-containing sludge. The composite coal-saving synergist is prepared by the above-mentioned method of synergistic low-energy consumption preparation of composite coal-saving synergist using undisturbed fluoride-containing sludge and multiple solid wastes.

[0022] In the technical solution of this invention, steel slag, municipal solid waste incineration fly ash, nickel-iron slag, and aluminum ash slag are ground to a residue of less than 5% on a 75 μm sieve to obtain powder.

[0023] In the technical solution of this invention: the obtained composite coal-saving efficiency enhancer product is naturally stacked for 1 to 3 days, which has good strength and avoids damage during loading and transportation by forklift.

[0024] In step (1), the steel slag contains 1-5% P, 0.2-1.5% F, 3-6% Al, and 20-30% Fe; the municipal solid waste incineration fly ash contains 3-7% S, 0.1-0.5% Pb, 0.1-0.3% Zn, 0.1-0.2% Cu, 0.5-3% Al, and 0.5-2% Fe; the nickel-iron slag contains 0.1-1.5% S, 1.5-2.5% Cr, 0.5-0.8% Mn, 18-33% Mg, 2-7% Al, and 10-15% Fe; and the aluminum ash slag contains 1-5% F, 40-80% Al, and 0.3-1% Fe.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) This invention is a granular coal-saving synergist composed of multiple components, including clinker liquid phase regulator, clinker mineral phase seed crystals, and thermal decomposition aid, and is suitable for cement clinker calcination. First, calcium fluoride in fluorine-containing sludge plays a role in clinker mineralization, improving the calcinability of raw materials. Second, tricalcium silicate and dicalcium silicate in steel slag act as mineralization seed crystals, reducing the nucleation barrier of clinker minerals and promoting the formation of clinker minerals. In addition, the doping of crystal-inducing elements such as S, Mg, Zn, Pb, Cu, Cr, and Mn in powder materials (steel slag, municipal solid waste incineration fly ash, nickel-iron slag, and aluminum ash slag) can directionally regulate the crystal form and crystal structure of calcium silicate mineral phases in clinker, improve the activity of dicalcium silicate and tricalcium silicate, and thus improve clinker strength.

[0027] (2) This invention relates to the synergistic effect of multiple solid wastes. By controlling the fluorine content (F / (Al + Fe)) in the synergist, the solidification of F ions in fluorine-containing sludge is promoted, so that they are stabilized in the clinker components, preventing the escape of F ions during the clinker calcination process and avoiding negative effects such as ring formation in the rotary kiln and equipment corrosion caused by F ions.

[0028] (3) The composite coal-saving enhancer prepared by the present invention can significantly improve the viscosity of the liquid phase and reduce the formation temperature of tricalcium silicate, reduce the amount of free calcium oxide in clinker, increase the amount of tricalcium silicate, thereby improving the activity of silicate mineral phase and promoting the clinker to increase 3d strength by 3~5 MPa and 28d strength by 5~7 MPa.

[0029] (4) The composite coal-saving synergist prepared by the present invention has the effect of significantly improving the kiln mine, reducing flying sand in the kiln, and reducing free calcium oxide, and can improve the decomposition efficiency of calcium carbonate.

[0030] (5) The composite coal-saving synergist prepared by the present invention can improve the utilization efficiency of low-grade limestone (high magnesium and high silica limestone), and can be used to prepare high-strength cement clinker, or increase the proportion of low-grade limestone to prepare high-strength cement clinker.

[0031] (6) The composite coal-saving enhancer prepared by the present invention has outstanding coal-saving effect and can save 5-10 kg of actual coal per ton of clinker.

[0032] (7) The temperature and humidity regulating coagulant used in this invention promotes the chemical reaction between fluorine-containing sludge, steel slag and other raw materials to produce gelling properties, while releasing heat to promote the drying of water-dissipated particles, thus achieving the effect of self-hardening, self-heating and self-drying of particles.

[0033] (8) This invention uses extrusion granulation technology to prepare a composite coal-saving and efficiency-enhancing agent to achieve harmless treatment and high-value-added application of undisturbed fluorine-containing sludge. On the one hand, this method can directly utilize undisturbed fluorine-containing sludge with a high water content, avoiding the energy consumption caused by the drying process in conventional fluorine-containing sludge utilization, thus enabling large-scale, low-energy, and stable utilization of fluorine-containing sludge. On the other hand, the obtained product effectively utilizes the fluorine element in the fluorine-containing sludge and the effective elements in other raw materials, synergistically improving clinker quality and reducing energy consumption in cement clinker production through liquid phase regulation effect, ion doping effect, crystal doping induction effect, and mineral phase seed effect, while avoiding the escape of fluorine in the traditional cement kiln system. Attached Figure Description

[0034] Figure 1 This is a picture of the clinker composite coal-saving synergist granules in Example 1;

[0035] Figure 2 This is a flowchart illustrating the entire production and utilization process of Examples 1-6;

[0036] Figure 3 Thermogravimetric analysis diagrams of Example 1 and Comparative Example 1 are shown.

[0037] Figure 4 QXRD results for clinker produced by adding Examples 1-6 and Comparative Examples 1-2 to raw materials;

[0038] Figure 5 Backscattered electron images and energy dispersive spectroscopy analysis of the clinker produced by adding Example 5 to the raw material. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0040] The fluorinated sludge mentioned in the examples and comparative examples is a major untreated industrial byproduct of photovoltaic enterprises; steel slag is a byproduct of converter steelmaking; fly ash from municipal solid waste incineration is a byproduct generated during municipal solid waste treatment; nickel-iron slag is a solid waste generated during nickel-iron alloy smelting; and aluminum ash slag is a byproduct of aluminum electrolysis.

[0041] In the following embodiments and comparative examples of the present invention, the main constituent elements of steel slag, municipal solid waste incineration fly ash, nickel-iron slag, and aluminum ash slag are as follows:

[0042] The steel slag contains 4.8% phosphorus, 1.2% sulfur, 3.9% aluminum, and 25.6% iron.

[0043] The fly ash from municipal solid waste incineration contains 6.9% sulfur (S), 0.5% phosphorus (Pb), 0.3% zinc (Zn), 0.2% copper (Cu), 2.8% aluminum (Al), and 1.1% iron (Fe).

[0044] The nickel-iron slag contains 1.5% sulfur, 2.3% chromium, 0.8% manganese, 29.1% magnesium, 6.5% aluminum, and 12.3% iron.

[0045] The aluminum ash slag contains 1.8% F, 65.8% Al, and 0.5% Fe.

[0046] Example 1

[0047] A method for preparing clinker composite coal-saving synergist using fluorine-containing sludge, the method comprising the following steps:

[0048] (1) Select undisturbed fluorine-containing sludge with a moisture content of 40% and a calcium fluoride content of 55%, and grind the block steel slag, municipal solid waste incineration fly ash, nickel iron slag and aluminum ash slag into powders with a residue of less than 5% on a 75 μm sieve.

[0049] (2) Weigh 80 parts by mass of fluorine-containing sludge, 5 parts by mass of steel slag powder, 5 parts by mass of municipal solid waste incineration fly ash powder, 5 parts by mass of nickel-iron slag powder, 5 parts by mass of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine content is 0.20. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping control rate is 0.22), and 0.1 parts by mass of temperature and humidity regulating coagulant (composed of 50 parts by mass of hydroxyethyl diisopropanolamine, 10 parts by mass of lithium sulfate, 20 parts by mass of sulfonated melamine-formaldehyde condensate, 10 parts by mass of polyacrylol, and 10 parts by mass of sodium dodecyl sulfate). Pour the raw materials into a mixer and stir evenly.

[0050] (3) Pour the well-stirred material into the double-die granulator, adjust the granulation pressure to 10 MPa, cut the particle size with a scraper to 5 mm, and extrude to obtain composite coal-saving and efficiency-enhancing agent particles.

[0051] (4) The composite coal-saving synergist granules were naturally piled up for 1 day to obtain the synergist product suitable for the production of high-strength cement clinker. The composite coal-saving synergist contained 40.8% calcium fluoride and had a moisture content of 5.2%.

[0052] Example 2

[0053] A method for preparing clinker composite coal-saving synergist using fluorine-containing sludge, the method comprising the following steps:

[0054] (1) Select undisturbed fluoride-containing sludge with a moisture content of 50% and a calcium fluoride content of 60%, and grind the block steel slag, municipal solid waste incineration fly ash, nickel iron slag and aluminum ash slag into powders with a residue of less than 5% on a 75 μm sieve.

[0055] (2) Weigh 70 parts by weight of fluorine-containing sludge, 15 parts by weight of steel slag powder, 5 parts by weight of municipal solid waste incineration fly ash powder, 5 parts by weight of nickel-iron slag powder, 5 parts by weight of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine content is 0.11. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping control rate is 0.48), and 0.15 parts by weight of temperature and humidity regulating coagulant (composed of 30 parts by weight of hydroxyethyl diisopropanolamine, 20 parts by weight of lithium sulfate, 20 parts by weight of sulfonated melamine-formaldehyde condensate, 20 parts by weight of polyacrylol, and 10 parts by weight of sodium dodecyl sulfate). Pour the raw materials into a mixer and stir evenly.

[0056] (3) Pour the well-stirred material into the double-die granulator, adjust the granulation pressure to 10 MPa, cut the particle size with a scraper to 5 mm, and extrude to obtain composite synergist particles.

[0057] (4) The composite coal-saving synergist granules were naturally piled up for 1 day to obtain the synergist product suitable for the production of high-strength cement clinker. The composite coal-saving synergist contained 32.3% calcium fluoride and had a moisture content of 6.9%.

[0058] Example 3

[0059] The experimental method used in this embodiment is the same as that in Embodiment 2.

[0060] The steps for preparing the clinker composite coal-saving synergist in this embodiment differ from those in Example 2 in that step (2) involves weighing 70 parts by mass of fluorinated sludge, 5 parts by mass of steel slag powder, 5 parts by mass of municipal solid waste incineration fly ash powder, 10 parts by mass of nickel-iron slag powder, 10 parts by mass of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine rate is 0.09. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping control rate is 0.61), and 0.2 parts by mass of temperature and humidity regulating coagulant (composed of 30 parts by mass of hydroxyethyl diisopropanolamine, 20 parts by mass of lithium sulfate, 20 parts by mass of sulfonated melamine-formaldehyde condensate, 20 parts by mass of polyacrylol, and 10 parts by mass of sodium dodecyl sulfate).

[0061] Example 4

[0062] A method for preparing clinker composite coal-saving synergist using fluorine-containing sludge, the method comprising the following steps:

[0063] (1) Select undisturbed fluorine-containing sludge with a moisture content of 60% and a calcium fluoride content of 70%, and grind block steel slag, municipal solid waste incineration fly ash, nickel iron slag and aluminum ash slag into powders with a residue of less than 5% on a 75 μm sieve.

[0064] (2) Weigh 60 parts by mass of fluorine-containing sludge, 10 parts by mass of steel slag powder, 15 parts by mass of municipal solid waste incineration fly ash powder, 10 parts by mass of nickel-iron slag powder, 5 parts by mass of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine content is 0.12. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping control rate is 0.66), and 0.25 parts by mass of temperature and humidity regulating coagulant (composed of 30 parts by mass of hydroxyethyl diisopropanolamine, 30 parts by mass of lithium sulfate, 10 parts by mass of sulfonated melamine-formaldehyde condensate, 10 parts by mass of polyacrylol, and 20 parts by mass of sodium dodecyl sulfate). Pour the raw materials into a mixer and stir evenly.

[0065] (3) Pour the well-stirred material into the double-die granulator, adjust the granulation pressure to 8 MPa, cut the particle size with a scraper to 6 mm, and extrude to obtain composite synergist particles.

[0066] (4) The composite coal-saving synergist granules were naturally piled up for 1 day to obtain the synergist product suitable for the production of high-strength cement clinker. The composite coal-saving synergist contained 27.8% calcium fluoride and had a moisture content of 6.6%.

[0067] Example 5

[0068] The experimental method used in this embodiment is the same as that in Embodiment 4.

[0069] The steps for preparing the composite coal-saving efficiency enhancer in this embodiment differ from those in Example 4 in that step (2) involves weighing 60 parts by mass of fluorinated sludge, 15 parts by mass of steel slag powder, 10 parts by mass of municipal solid waste incineration fly ash powder, 5 parts by mass of nickel-iron slag powder, 10 parts by mass of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine rate is 0.08. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping regulation rate is 0.52), and 0.3 parts by mass of temperature and humidity regulating coagulant (composed of 30 parts by mass of hydroxyethyl diisopropanolamine, 30 parts by mass of lithium sulfate, 10 parts by mass of sulfonated melamine-formaldehyde condensate, 10 parts by mass of polyacrylol, and 20 parts by mass of sodium dodecyl sulfate).

[0070] Example 6

[0071] A method for preparing clinker composite coal-saving synergist using fluorine-containing sludge, the method comprising the following steps:

[0072] (1) Select undisturbed fluorine-containing sludge with a water content of 50% and a calcium fluoride content of 70%, and grind the block steel slag, municipal solid waste incineration fly ash, nickel iron slag and aluminum ash slag into powders with a residue of less than 5% on a 75 μm sieve.

[0073] (2) Weigh 50 parts by weight of fluorine-containing sludge, 20 parts by weight of steel slag powder, 10 parts by weight of municipal solid waste incineration fly ash powder, 10 parts by weight of nickel-iron slag powder, 10 parts by weight of aluminum ash powder (by calculating F / (Al + Fe) in the raw materials, the fluorine content is 0.06. By calculating P + S + Mg + Zn + Pb + Cu + Cr + Mn / (Al + Fe) in the raw materials, the crystal doping control rate is 0.55), and 0.5 parts by weight of temperature and humidity regulating coagulant (composed of 40 parts by weight of hydroxyethyl diisopropanolamine, 10 parts by weight of lithium sulfate, 10 parts by weight of sulfonated melamine-formaldehyde condensate, 10 parts by weight of polyacrylol, and 30 parts by weight of sodium dodecyl sulfate). Pour the raw materials into a mixer and stir evenly.

[0074] (3) Pour the well-stirred material into the double-die granulator, adjust the granulation pressure to 8 MPa, cut the particle size with a scraper to 3 mm, and extrude to obtain composite synergist particles.

[0075] (4) The composite coal-saving synergist granules were naturally stacked for 2 days to obtain the synergist product suitable for the production of high-strength cement clinker. The composite coal-saving synergist contained 24.2% calcium fluoride and had a moisture content of 6.2%.

[0076] The composite coal-saving and efficiency-enhancing agents obtained in Examples 1 to 6 were added to the raw meal at 0.5% of the raw meal mass (Table 2), and the performance of the clinker obtained after calcination was tested.

[0077] Comparative Example 1

[0078] In this comparative example, undisturbed raw meal powder (Table 2) was used to prepare the cooked meal.

[0079] Comparative Example 2

[0080] This comparative example includes the following steps:

[0081] (1) Select undisturbed fluoride-containing sludge with a water content of 40% and a calcium fluoride content of 55%.

[0082] (2) Pour the fluorinated sludge into the dual-mold granulator, adjust the granulation pressure to 10 MPa, cut the particle size with a scraper to 5 mm, and extrude to obtain composite synergist particles.

[0083] (3) The composite coal-saving efficiency enhancer was naturally piled up for 3 days and then mixed into the raw material (Table 2) at 0.5% of the raw material mass.

[0084] Thermogravimetric analysis was performed on the raw material of Example 1 and the sample of Comparative Example 1. Figure 2 It can be seen that, after adding the composite coal-saving synergist described in Example 1 to the raw meal, compared with Comparative Example 1, the decomposition temperature of calcium carbonate is advanced and the amount of calcium carbonate decomposed is increased, proving that the composite coal-saving synergist can significantly improve the utilization efficiency of low-grade limestone raw materials. In addition, the dicalcium silicate and liquid phase formation temperatures are advanced during clinker calcination, proving that the composite coal-saving synergist can promote the formation of calcium silicate mineral phase and improve the viscosity of liquid phase.

[0085] According to GB / T 21372-2008 "Silicate Cement Clinker", the specific surface area, setting time, soundness, and mechanical properties of the calcined clinker were tested. As shown in Table 4, after adding the composite coal-saving synergist described in Examples 1-6 to the raw meal, compared with Comparative Example 1, the f-CaO content in the clinker was significantly reduced, the setting time was shortened, and the compressive strength was improved. This is the result of the synergistic effect of multiple effects, including mineralization, liquid phase regulation, ion doping, crystal form induction, and mineral phase seeding. First, the calcium fluoride contained in the fluorinated sludge acts as a mineralizer, promoting the decomposition of carbonate minerals, destroying the SiO2 crystal lattice structure, and improving the burnability of the raw meal. On the other hand, it promotes the formation of the liquid phase, reduces the viscosity of the liquid phase, and is beneficial to the crystal growth of clinker minerals. Secondly, elements such as P, S, Mg, Zn, Pb, Cu, Cr, and Mn in steel slag, municipal solid waste incineration fly ash, nickel-iron slag, and aluminum ash exert an ion doping effect, promoting the transformation of tricalcium silicate in clinker from M3 to M1 type, reducing the particle size of dicalcium silicate, and improving the early and later strength of clinker. Furthermore, the tricalcium silicate and dicalcium silicate mineral phases contained in steel slag act as a "seed effect" during clinker firing, lowering the activation energy for the formation of tricalcium silicate and dicalcium silicate, and promoting the formation of highly active tricalcium silicate and dicalcium silicate with more internal defects.

[0086] Table 4 shows the operating status of cement kilns after using the composite coal-saving synergist from Examples 1-6. After incorporating the composite coal-saving synergist, the f-CaO content decreased significantly, and the actual coal content per ton of clinker decreased by 5-10 kg. This demonstrates that the composite coal-saving synergist improves the burnability of raw materials, increases coal combustion efficiency, and achieves coal saving and production increase.

[0087] according to Figure 4The results show that F element is mainly distributed in the liquid phase of clinker, similar to the distribution of Al and Fe elements. Table 5 shows the F ion content in raw meal and clinker. The F ion content in the clinker produced by adding Comparative Example 2 was significantly reduced compared to the raw meal, with a large amount of fluoride volatilized and lost after calcination. Examples 1-6 can significantly improve the fluoride fixation rate of clinker and reduce fluoride loss, meeting the requirements for fluoride emissions in GB 4915-2013 "Emission Standard of Air Pollutants for Cement Industry" and avoiding the negative impacts caused by F ion doping. This is because controlling the Al / Fe ratio in the raw materials enhances the solidification effect of F ions in the clinker.

[0088] The composite coal-saving synergist described in Examples 1-6 has a moisture content of 3-7% and a strength of 3.6-5.8 MPa after 1 day. This meets the requirements for long-term large-scale stockpiling, long-distance transportation, and loading by forklifts. This is because the temperature and humidity regulating coagulant added during the granulation process promotes hydration and plasticizes while reducing water content. On the one hand, the continuous hydration of the powder under the action of the activator allows a large amount of water from the fluoride-containing sludge to participate in the powder cementation process. On the other hand, the rapid coagulation and hardening of the granules generates a large amount of chemical exothermics, resulting in a self-heating and self-drying effect, which accelerates the evaporation and loss of moisture in the composite coal-saving synergist granules. In addition, the granular product has more voids during the stacking process, which is more conducive to moisture loss compared to the sludge stockpiling process.

[0089] Table 1 Chemical composition of main raw materials in raw meal (wt.%)

[0090]

[0091] Table 2 Chemical composition and yield values ​​of raw materials

[0092]

[0093] Table 3 Basic Properties of Clinker

[0094]

[0095] Table 4. Condition of 5000t / d Cement Kiln

[0096]

[0097] Table 5. Fluorine content test of raw meal and clinker at different stages

[0098]

Claims

1. A method for preparing a cement clinker composite coal-saving synergist with raw fluorine-containing sludge and multiple solid wastes at low energy consumption, characterized in that, The method includes the following steps: (1) Batching and pre-homogenization of raw materials: Weigh the original fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel iron slag powder, aluminum ash slag powder and temperature and humidity regulating coagulant, and mix the raw materials evenly through a mixer; The moisture content of the original fluorine-containing sludge is 40-80%; the weight parts of the fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel-iron slag powder, aluminum ash slag powder and temperature and humidity regulating coagulant in step (1) are 50-80 parts, 5-30 parts, 5-20 parts, 5-20 parts, 5-10 parts and 0.02-0.5 parts respectively. The temperature and humidity regulating coagulant mentioned in step (1) is composed of 30-50 parts by weight of hydroxyethyl diisopropanolamine, 10-30 parts by weight of lithium sulfate, 10-30 parts by weight of sulfonated melamine formaldehyde condensate, 10-30 parts by weight of polyacryl alcohol, and 10-30 parts by weight of sodium dodecyl sulfate. In step (1), the fluorine content in the raw material is controlled to be F / (Al + Fe), and the fluorine content range is 0.06~0.20; the crystal doping control rate is crystal doping induction element / (Al + Fe), and the crystal doping control rate ranges from 0.20 to 0.

65. The crystal form inducing elements are P, S, Mg, Zn, Pb, Cu, Cr, and Mn. (2) Dual-mold extrusion granulation: The material uniformly mixed in step (1) is extruded and granulated by a dual-mold granulator. The granulated particles are stacked layer by layer naturally, and the particles are self-hardened, self-heated and cured, and self-dried to obtain a composite coal-saving efficiency enhancer product.

2. The method for preparing cement clinker composite coal-saving synergist with raw-state fluorine-containing sludge multi-solid waste and low energy consumption according to claim 1, characterized in that, The fluorine-containing sludge mentioned in step (1) is a byproduct of the treatment of fluorine-containing wastewater in photovoltaic enterprises; steel slag is a byproduct of the converter steelmaking process; fly ash from municipal solid waste incineration is a byproduct generated during the treatment of municipal solid waste; nickel-iron slag is a solid waste generated during the smelting of nickel-iron alloys; and aluminum ash slag is a byproduct of the electrolytic aluminum process.

3. The method for preparing cement clinker composite coal-saving synergist with raw-state fluorine-containing sludge multi-solid waste and low energy consumption according to claim 1, characterized in that, The original fluoride-containing sludge contains 20-70% calcium fluoride.

4. The method for preparing cement clinker composite coal-saving synergist with raw-state fluorine-containing sludge multi-solid waste and low energy consumption according to claim 1, characterized in that, The weight parts of the fluorine-containing sludge, steel slag powder, municipal solid waste incineration fly ash powder, nickel-iron slag powder, aluminum ash powder and temperature and humidity regulating coagulant in step (1) are 50~80 parts, 5~20 parts, 5~15 parts, 5~10 parts, 5~10 parts and 0.1~0.5 parts respectively.

5. The method for preparing a composite coal-saving and efficiency-enhancing agent for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner according to claim 1, characterized in that, The crystal form inducing element has the effect of inducing tricalcium silicate crystal form transformation and improving the activity of dicalcium silicate and tricalcium silicate.

6. The method for preparing a composite coal-saving synergist for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner according to claim 1, characterized in that, The composite coal-saving enhancer described in step (2) contains 20-55% calcium fluoride and has a moisture content of no more than 10%.

7. The method for preparing a composite coal-saving synergist for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner according to claim 1, characterized in that, The granulator mentioned in step (2) is a dual-mold granulator with a granulation pressure of 5~10MPa and a scraper cutting particle size of 3~8 mm.

8. The method for preparing a composite coal-saving synergist for cement clinker using undisturbed fluoride-containing sludge and multiple solid wastes in a low-energy-consumption manner according to claim 1, characterized in that, It also includes step (3), in which the composite coal-saving synergist is used in the production of clinker in cement kilns, and the amount of the composite coal-saving synergist added to the raw meal is 0.05~1.5% by mass percentage.

9. A low-energy-consumption composite coal-saving and efficiency-enhancing agent for cement clinker prepared by synergistic use of multiple solid wastes, including undisturbed fluoride-containing sludge, is characterized in that... The composite coal-saving enhancer is prepared by the method described in any one of claims 1-7, which utilizes undisturbed fluorine-containing sludge and multiple solid wastes in a synergistic, low-energy-consumption manner to prepare a composite coal-saving enhancer for cement clinker.

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