CN116903276A - A powdery raw meal melting accelerator and its preparation method - Google Patents

Abstract

The invention discloses a powder melting accelerant and a preparation method thereof, and relates to the technical field of cement clinker calcination, wherein the powder melting accelerant contains 40-70% of activated electrolytic aluminum solid waste, 5-20% of co-doped nano rare earth components, 10-35% of calcination fluxing components and 5-20% of auxiliary decomposition accelerating components. The powder raw material melting promoter provided by the disclosure can realize the omnibearing recycling of electrolytic aluminum overhaul slag in cement production. The composite raw material melting accelerant provided by the disclosure has the comprehensive effects of well accelerating carbonate decomposition, reducing the decomposition temperature of calcium carbonate, improving the easy burning property of clinker, reducing the calcining energy consumption of cement clinker and improving the quality of cement clinker.

Description

A powdery raw meal melting accelerator and its preparation method

Technical field

The invention belongs to the technical field of cement clinker calcination, and specifically relates to a powdery raw meal melting accelerator and a preparation method thereof.

Background technique

According to statistics, typical cement enterprises’ electricity consumption accounts for 5.90% of comprehensive energy consumption, raw coal consumption accounts for 3.61% of comprehensive energy consumption, and fuel oil consumption accounts for 0.49% of comprehensive energy consumption. For coal-fired cement energy consumption, clinker energy consumption accounts for about 70%-80%. During the clinker calcination process, the decomposition of carbonate is a strong endothermic reaction, and the heat required accounts for about 1/2 of the total production consumption of the suspension preheating kiln or precalcining kiln, and the required coal consumption accounts for 60-70%. In the process of clinker firing, the formation of liquid phase, solid-liquid reaction and other processes also consume a large amount of energy, accounting for about 40%. Therefore, promoting the decomposition of calcium carbonate and improving the formation conditions and properties of the liquid phase during the calcination process are important ways to promote clinker sintering and reduce energy consumption.

While the aluminum smelting industry is booming, the environmental risks posed by hazardous wastes such as carbon slag, overhaul slag and aluminum ash generated during the production process have become increasingly prominent. At present, the disposal methods of solid hazardous waste generated in the electrolytic aluminum process mainly include traditional methods such as landfill, roasting and comprehensive utilization of resources. The landfill method has a simple process, but it can easily cause waste of Al and F resources and cause soil and groundwater pollution. Valuable elements are recycled. Valuable metal recovery methods are still mostly in the laboratory stage, and it is not yet possible to achieve high-value utilization of aluminum electrolysis solid waste. The technology for collaborative disposal of hazardous waste in cement kilns is relatively mature, and the relevant standard system is also relatively complete. There is also cement kiln co-processing technology, but it is generally used as an alternative fuel or alternative raw material for cement production to achieve harmless disposal of solid waste.

After investigation, the alkali and fluorine contents in electrolytic aluminum solid waste are relatively high. For example, the alkali content in electrolytic aluminum overhaul slag is 14.23%, the fluorine content is 11.503%, and the fluoride content can reach 30%-40%. Fluoride in high-temperature processes It can generate new phases in the clinker to accelerate the decomposition reaction of raw meal. At the same time, it can form calcium fluoroaluminate solid solution with calcium oxide and aluminum oxide and dissolve in the clinker. It is an excellent material for improving the burnability of raw meal. , can increase clinker production and enhance cement strength.

Contents of the invention

In view of the above problems, the present invention provides a powdery raw meal melting accelerator and a preparation method thereof. The accelerator can effectively promote the decomposition of carbonate, reduce the decomposition temperature of calcium carbonate, and has multiple components that synergistically reduce the eutectic point and promote cement ripening. The burning of materials.

The powdered raw meal calcined melting accelerator is prepared by including the following weight percentages of raw materials: 40-70% of activated electrolytic aluminum solid waste, 5-20% of co-doped nano-rare earth components, and 10-35% of calcined fluxing components. %, auxiliary decomposition component 5-20%.

The activated electrolytic aluminum solid waste is obtained from electrolytic aluminum solid waste through a mechanical-chemical coupling activation method;

The electrolytic aluminum solid waste is one or more of electrolytic aluminum waste overhaul slag and electrolytic aluminum carbon slag;

The electrolytic aluminum solid waste is electrolytic aluminum waste overhaul slag;

The electrolytic aluminum waste overhaul slag contains 33.4% by weight of fluoride, 38.6% of carbonaceous materials, 8.4% of nepheline, 3.8% of alumina, 5.1% of mullite, 2.6% of albite, 0.3% of gypsum, and 5.9% of other materials. , water 1.9%;

The co-doped nano-rare earth component is a rare earth element compound prepared by a multi-element co-precipitation method;

The rare earth element compound is one or more of cerium nitrate, lanthanum nitrate, cerium chloride, lanthanum chloride, and yttrium nitrate;

The calcining fluxing component is one or more of sodium thiosulfate, sodium dihydrogen phosphate, and zinc sulfate;

One or more of the auxiliary decomposition-promoting components sodium fluorosilicate, sodium citrate, and sodium oleate;

The mechanical-chemical coupling activation method prepares activated electrolytic aluminum solid waste. The specific steps are as follows:

Take an appropriate amount of electrolytic aluminum solid waste and add it to the planetary mill. At the same time, add grinding aid components to the mill for grinding at 300r/min. The grinding time is 40min to ensure that the crystallinity of the particles after grinding is reduced to the minimum value and disordered. The degree is >40%. After the grinding is completed, add a chemical activator into the mill at a ratio of chemical coupling initiator/waste of 2%, and then continue grinding at 500r/min for 60 minutes to obtain activated electrolytic aluminum solid waste. things.

The grinding aid component includes one or more of sodium stearate, oleic acid, and ethanol;

The chemical activator is one or more of sodium sulfate, sodium silicate and sodium lignosulfonate;

The described multi-element co-precipitation method prepares co-doped nano-rare earth components, and the specific steps are as follows:

Using Ce(NO ₃ ) ₃ ·6H ₂ O and La(NO ₃ ) ₃ ·6H ₂ O as rare earth component raw materials, take appropriate amounts of Ce(NO ₃ ) ₃ ·6H2O and La(NO ₃ ) ₃ ·6H ₂ O respectively. , dissolve in deionized water at a ratio of 3:1, configure a 0.1mol/L Ce3+, La3+ rare earth solution, take an appropriate amount of coprecipitant and dissolve it in deionized water, configure a 0.3mol/L coprecipitant solution, and Under the conditions of 60° C. and a stirring speed of 400 rpm, the coexisting rare earth solution was slowly added to the coprecipitant solution. After the reaction is completed, let the solution stand at room temperature for 2 hours. After suction filtration and cleaning, dry it. Place the dried material into a planetary ball mill for ball milling at 500r/min and for 40min to obtain co-doped nano-rare earth components.

The co-precipitating agent is one or more of ammonium carbonate, ammonium bicarbonate, oxalic acid, sodium carbonate, and sodium hydroxide.

The preparation method of the powdery raw meal melting accelerator, the specific steps are as follows:

Take an appropriate amount of the activated electrolytic aluminum solid waste prepared by the mechanical-chemical coupling activation method described in claim 2 and the co-doped nano rare earth component prepared by the multi-element co-precipitation method described in claim 3 in proportion, and add them into a dry powder mixer. Stir for 10 minutes, and then add the calcined fluxing component and the raw material decomposition promoting component described in claim 1 in proportion to the mixer and stir together for 20 minutes to obtain a powder melting accelerator.

The powdered raw meal melting accelerator is added to the cement production process in at least one of the following ways:

(1) Mix the powdery composite raw meal melting accelerator with the cement raw meal on the belt before the raw meal mill;

(2) Mix the powdery composite raw meal melting accelerator with the cement raw meal before entering the preheater;

Beneficial effects obtained by the present invention:

(1) Activated electrolytic aluminum solid waste: After mechanical activation, the particle size of electrolytic aluminum solid waste becomes significantly smaller. At this time, adding a small amount of chemical activators can change the physical and chemical properties of the material surface, making the powder The destruction of chemical bonds on the particle surface is accelerated, the chemical strength is changed, the activity of the powder is increased, and it has a better surface effect. During the application process, first, it can generate new phases under high temperature conditions, destroy the crystal structure, make the crystal structure tend to be amorphous, and promote the occurrence of carbonate decomposition reactions; second, it can generate intermediate phases, promoting the early appearance of C3S, Increase the firing speed and reduce the energy consumption of cement clinker firing; third, it contains trace amounts of various metal elements, which have the effect of multiple elements synergistically lowering the eutectic point; fourth, the waste contains some carbon-based components, which at high temperatures Part of the heat can be released at this time, which helps to reduce coal consumption in clinker preparation.

(2) Co-doped nano-rare earth components: During use, further decomposition will occur to generate smaller multi-element nano-rare earth components. At the same time, gas will be generated, disturbing the raw material, and helping to disperse evenly; at the same time, the nanoparticle ratio The surface area is further increased, the proportion of atoms with insufficient surface coordination is higher, the surface energy is further improved, showing high activity characteristics, and is easier to react with raw materials, embedded inside the raw material lattice, increasing structural vacancies in the raw materials, and promoting particle diffusion process, reducing the reaction potential energy and accelerating the occurrence of the reaction.

(3) Calcination fluxing components: The introduction of alkali metals, transition metals and other components further enhances the synergy of multi-elements and lowers the minimum eutectic temperature of the system, so that the liquid phase can be generated at a lower reaction temperature and the liquid phase appears in advance , helps to increase the amount of liquid phase, cause uneven local electricity prices, change the properties of the liquid phase, reduce the viscosity of the liquid phase, promote the generation of C3S, and accelerate the firing of clinker; at the same time, solid solution reaction can occur, prompting the crystallization of clinker minerals. Lattice distortion, transformation to a crystal form with better strength, and improved hydration activity.

(4) Auxiliary decomposition-promoting components: Some components can react with raw materials to generate new phases on the surface. The new phases can pyrolyze during the heating process and release heat, causing the local temperature to increase, which is beneficial to carbonate of decomposition. Or it reacts with the raw material, changes the structural state of the raw material, and forms a large number of defects on the surface of the material, which contributes to mass and heat transfer during the carbonate decomposition process and accelerates the carbonate decomposition process.

The additive dosage of the present invention is 0.06-0.2%, which can significantly promote the decomposition of carbonates in raw materials, reduce the decomposition temperature of carbonates, promote the burning of cement clinker, improve the quality of cement clinker, and save coal consumption in clinker production. , has broad economic and social benefits.

Detailed ways

The specific implementation modes of the present invention will be further described in detail through the description of the examples below to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concepts and technical solutions of the present invention.

Example 1

The invention discloses a method for preparing a powdery raw meal melting accelerator, which includes the following specific steps:

(1) Take an appropriate amount of electrolytic aluminum solid waste and add it to the planetary mill. At the same time, add 0.5% sodium stearate and 0.1% oleic acid into the mill and grind at 300r/min. The grinding time is 40min to ensure that the The crystallinity of the final particles drops to the lowest value, and the degree of disorder is >40%. After completion, a chemical activator is added into the mill at a ratio of chemical coupling activator/waste of 2%. The chemical activator is sodium silicate: Sodium lignosulfonate 5:1, and then continue grinding at 500r/min for 60min to obtain activated electrolytic aluminum solid waste;

(2) Take appropriate amounts of Ce(NO ₃ ) ₃ ·6H ₂ O and La(NO ₃ ) ₃ ·6H ₂ O respectively, dissolve them in deionized water at a ratio of 3:1, and configure it to 0.1mol/L Ce ³⁺ , La ³⁺ coexisting rare earth solution, dissolve an appropriate amount of ammonium carbonate in deionized water, prepare a 0.3mol/L ammonium carbonate solution, and slowly add the coexisting rare earth solution to the ammonium carbonate solution at 60°C and a stirring speed of 400rpm. . After the reaction is completed, let the solution stand at room temperature for 2 hours. After suction filtration and cleaning, dry it. Place the dried material into a planetary ball mill for ball milling at 500r/min and a milling time of 40min to obtain co-doped nano-rare earth components;

(3) Take the activated electrolytic aluminum solid waste prepared in step (1) and the co-doped nano-rare earth component prepared in step (2) in proportion, add them into a dry powder mixer, stir for 10 minutes, and then add the mass ratio into the mixer in proportion Zinc sulfate and sodium dihydrogen phosphate of 1:1, stir for 10 minutes. After stirring, continue to add sodium fluorosilicate and sodium citrate with a mass ratio of 3:1 in proportion and stir together. The stirring time is 30 minutes, and the powder is melted. accelerator.

Among them, 50% of activated electrolytic aluminum solid waste, 15% of co-doped nano-rare earth components, 20% of calcined fluxing components, 15% of auxiliary decomposition-promoting components, and the additive content is 0.12%.

Example 2

The invention discloses a method for preparing a powdery raw meal melting accelerator, which includes the following specific steps:

(1) Take an appropriate amount of electrolytic aluminum solid waste, add it to the planetary mill, grind it for 40 minutes, then grind for 60 minutes after an interval of 30 minutes, to obtain the electrolytic aluminum solid waste;

(2) Add an appropriate amount of mamiCe ₂ (CO ₃ ) ₃ and La ₂ (CO ₃ ) ₃ powder in a ratio of 3:1, stir and mix in a mixer to obtain nano-rare earth components;

(3) Take the activated electrolytic aluminum solid waste prepared in step (1) and the nano-rare earth component prepared in step (2) in proportion, add them to a dry powder mixer, stir for 10 minutes, and then add proportionally to the mixer with a mass ratio of 1: 1 zinc sulfate and sodium dihydrogen phosphate, stir for 10 minutes. After the stirring is completed, continue to add sodium fluorosilicate and sodium citrate with a mass ratio of 3:1 and stir together. The stirring time is 30 minutes to obtain a powder melting accelerator.

Among them, 50% of activated electrolytic aluminum solid waste, 15% of co-doped nano-rare earth components, 20% of calcined fluxing components, 15% of auxiliary decomposition-promoting components, and the additive content is 0.12%.

Example 3

The invention discloses a method for preparing a powdery raw meal melting accelerator, which includes the following specific steps:

(1) Take an appropriate amount of electrolytic aluminum solid waste, add it to the planetary mill, grind it for 40 minutes, then grind for 60 minutes after an interval of 30 minutes, to obtain the electrolytic aluminum solid waste;

(2) Take appropriate amounts of Ce(NO ₃ ) ₃ ·6H ₂ O and La(NO ₃ ) ₃ ·6H ₂ O respectively, dissolve them in deionized water at a ratio of 3:1, and configure it to 0.1mol/L Ce ³⁺ , La ³⁺ coexisting rare earth solution, dissolve an appropriate amount of ammonium carbonate in deionized water, prepare a 0.3mol/L ammonium carbonate solution, and slowly add the coexisting rare earth solution to the ammonium carbonate solution at 60°C and a stirring speed of 400rpm. . After the reaction is completed, let the solution stand at room temperature for 2 hours. After suction filtration and cleaning, dry it. Place the dried material into a planetary ball mill for ball milling at 500r/min and a milling time of 40min to obtain co-doped nano-rare earth components;

(3) Take the activated electrolytic aluminum solid waste prepared in step (1) and the co-doped nano-rare earth component prepared in step (2) in proportion, add them into a dry powder mixer, stir for 10 minutes, and then add the mass ratio into the mixer in proportion Zinc sulfate and sodium dihydrogen phosphate of 1:1, stir for 10 minutes. After stirring, continue to add sodium fluorosilicate and sodium citrate with a mass ratio of 3:1 in proportion and stir together. The stirring time is 30 minutes, and the powder is melted. accelerator.

Among them, 50% of activated electrolytic aluminum solid waste, 15% of co-doped nano-rare earth components, 20% of calcined fluxing components, 15% of auxiliary decomposition-promoting components, and the additive content is 0.12%.

Example 4

The invention discloses a method for preparing a powdery raw meal melting accelerator, which includes the following specific steps:

(1) Take an appropriate amount of electrolytic aluminum solid waste and add it to the planetary mill. At the same time, add 0.5% sodium stearate and 0.1% oleic acid into the mill and grind at 300r/min. The grinding time is 40min to ensure that the The crystallinity of the final particles drops to the lowest value, and the degree of disorder is >40%. After completion, a chemical activator is added into the mill at a ratio of chemical coupling activator/waste of 2%. The chemical activator is sodium silicate: Sodium lignosulfonate 5:1, and then continue grinding at 500r/min for 60min to obtain activated electrolytic aluminum solid waste;

(2) Add an appropriate amount of mamiCe ₂ (CO ₃ ) ₃ and La ₂ (CO ₃ ) ₃ powder in a ratio of 3:1, stir and mix in a mixer to obtain nano-rare earth components;

(3) Take the activated electrolytic aluminum solid waste prepared in step (1) and the nano-rare earth component prepared in step (2) in proportion, add them to a dry powder mixer, stir for 10 minutes, and then add proportionally to the mixer with a mass ratio of 1: 1 zinc sulfate and sodium dihydrogen phosphate, stir for 10 minutes. After the stirring is completed, continue to add sodium fluorosilicate and sodium citrate with a mass ratio of 3:1 and stir together. The stirring time is 30 minutes to obtain a powder melting accelerator.

Among them, 50% of activated electrolytic aluminum solid waste, 15% of co-doped nano-rare earth components, 20% of calcined fluxing components, 15% of auxiliary decomposition-promoting components, and the additive content is 0.12%.

Example 5

The rest are the same as Example 1, except that the auxiliary decomposition-promoting component is 5%.

Example 6

The rest are the same as in Example 1, except that the calcined fluxing component is 10%.

Example 7

The rest are the same as in Example 1, except that 5% of nano-rare earth components are co-doped.

Example 8

The rest are the same as in Example 1, except that 60% of the electrolytic aluminum solid waste is activated.

Example 9

The rest are the same as Example 1, except that the additive content is 0.06%.

Raw meal performance test: Take raw meal raw materials from Wuhu Conch Cement Co., Ltd. as experimental samples, and add 0%, 0.06% and 0.12% melting accelerators. The difference is that the preparation method of the melting accelerator and the proportion of each component are different. , as shown in Examples 1-8 respectively. The specific tests are as follows:

Take the raw meal powder from Wuhu Conch Cement Co., Ltd. and put it into the kiln, melt the cement raw meal and calcine the accelerator and mix it evenly with the raw meal powder in different amounts, and dry it at 105°C for 2 hours; take the prepared mixed raw meal 1g, spread evenly in the crucible, place them in a crosswise manner, calcine at 820°C for 30 minutes, measure the loss on ignition, and the decomposition rate test results are shown in Table 1:

Table 1 Decomposition rate test results

Calcining performance of cement clinker: Take the raw meal powder from Wuhu Conch Cement Co., Ltd. and melt it into the kiln. The cement raw meal is melted and calcined. The accelerator agent is evenly mixed with the raw meal powder according to the dosage, and the test is made according to the cement raw meal easiness test method. After drying the sample at 105°C for 3 hours, move it to 950°C for calcination for 30 minutes, then quickly move it into a high-temperature furnace and calcine for 30 minutes at 1350/1400°C. After rapid cooling, grind it into powder, and measure its free oxidation within 3 days. calcium. The f-CaO test results are shown in Table 2

Table 2 1350℃/1400℃ f-CaO test results

The above results show that the melting accelerator can effectively promote the decomposition of carbonates in the raw meal and improve the burnability of the cement raw meal. The specific performance is as follows: (1) After adding the melting accelerator, the loss on ignition and decomposition rate of cement raw materials are significantly increased; (2) After adding the melting accelerator, the free calcium oxide content in the prepared clinker is significantly reduced; (3) Activation The performance of the final melt-promoting component is significantly better than that of the unactivated melt-promoting component; (4) The performance of the co-doped nano-rare earth component is significantly better than that of the ordinary mixed rare earth component.

The above embodiments are only for illustrating the technical ideas of the present invention and cannot limit the protection scope of the present invention. Any changes made based on the technical solutions based on the technical ideas proposed by the present invention will fall within the protection scope of the present invention. Within; technologies not involved in the present invention can be implemented through existing technologies.

Claims (4)

1. A powder raw material melting accelerator, characterized in that it is prepared from the following raw materials in weight percentages: 40-70% of activated electrolytic aluminum solid waste, 5-20% of co-doped nano-rare earth components, and calcined Fluxing component 10-35%, auxiliary decomposition component 5-20%; The activated electrolytic aluminum solid waste is electrolytic aluminum solid waste produced by a mechanical-chemical coupling activation method, and the electrolytic aluminum solid waste is electrolytic aluminum waste overhaul slag and electrolytic aluminum carbon slag; The electrolytic aluminum solid waste contains fluoride and fluoroaluminate; The rare earth element compound is one or more of cerium nitrate, lanthanum nitrate, cerium chloride, lanthanum chloride, and yttrium nitrate; The calcining fluxing component is one or more of sodium dihydrogen phosphate, zinc sulfate, and sodium thiosulfate; The auxiliary decomposition-promoting component is one or more of sodium fluorosilicate, sodium citrate, and sodium oleate. 2. The powder raw meal melting accelerator according to claim 1, characterized in that the specific preparation method of the activated electrolytic aluminum solid waste includes the following steps: Take an appropriate amount of electrolytic aluminum solid waste and add it to the planetary mill. At the same time, add grinding aid components to the mill for grinding at 300r/min. The grinding time is 40min to ensure that the crystallinity of the particles after grinding is reduced to the minimum value and disordered. The degree is >40%. After the grinding is completed, add a chemical activator into the mill at a ratio of chemical coupling initiator/waste of 2%, and then continue grinding at 500r/min for 60 minutes to obtain activated electrolytic aluminum solid waste. thing; The grinding aid component includes one or more of sodium stearate, oleic acid, and ethanol; The chemical activator is one or more of sodium sulfate, sodium silicate and sodium lignosulfonate. 3. The powder raw meal melting accelerator according to claim 1, characterized in that the co-doped nano-rare earth component is a rare earth element compound prepared by a multi-element co-precipitation method. The specific preparation method includes the following steps: Using Ce(NO ₃ ) ₃ ·6H ₂ O and La(NO ₃ ) ₃ ·6H ₂ O as rare earth component raw materials, take appropriate amounts of Ce(NO ₃ ) ₃ ·6H2O and La(NO ₃ ) ₃ ·6H ₂ O respectively. , dissolve in deionized water at a ratio of 3:1, configure a 0.1mol/L Ce ³⁺ , La ³⁺ co-existence rare earth solution, take an appropriate amount of coprecipitant and dissolve it in deionized water, configure a 0.3mol/L coprecipitate co-precipitating agent solution, slowly add the co-precipitating agent solution to the co-precipitating agent solution at 60°C and a stirring speed of 400 rpm; after the reaction is completed, let the solution stand at room temperature for 2 hours; after filtering and cleaning, dry it; The dried material is placed in a planetary ball mill for ball milling at 500r/min and the milling time is 40min to obtain co-doped nano-rare earth components; The co-precipitating agent is one or more of ammonium carbonate, ammonium bicarbonate, oxalic acid, sodium carbonate, and sodium hydroxide. 4. The preparation method of powder raw meal melting accelerator according to claim 1, characterized in that it specifically includes the following steps: Take an appropriate amount of activated electrolytic aluminum solid waste and co-doped nano-rare earth components in proportion, add them into a dry powder mixer, stir for 10 minutes, and then add the calcined fluxing component and raw meal as claimed in claim 1 in proportion to the mixer to promote decomposition. Components, continue stirring, stir for 20 minutes, and obtain the powder melting accelerator.