CN114472475B - Method for preparing molten glass body using complementary components of two fly ash - Google Patents

Abstract

The invention discloses a method for preparing a molten glass body by utilizing the complementarity of two fly ash components, which comprises the following steps: uniformly mixing fire grate fly ash and fluidized bed fly ash, and then placing the mixture into a crucible; placing the crucible into a muffle furnace, setting the temperature, and preserving heat for a certain time after the temperature is programmed to a certain temperature; closing an air inlet valve and opening an air outlet valve in the heat preservation process, and keeping the reducing atmosphere in the furnace; and after the heat preservation is finished, immediately taking out the crucible from the muffle furnace, and breaking the crucible after the crucible is naturally cooled, and taking out the glass body. The glass body is prepared by utilizing two dangerous wastes, the operation steps are simpler, the economic cost is low, the melting temperature is reduced (the energy consumption is reduced), the prepared glass body is high in stability and safety (such as good heavy metal fixing effect and low leaching toxicity), the application prospect is good, the cooperative treatment of the two fly ash (dangerous wastes) is realized, and in addition, the recovery of metal can be realized.

Description

Method for preparing molten glass body using complementary components of two fly ash

Technical field

The invention relates to the technical field of environmental protection and comprehensive utilization of resources, and in particular to a method for preparing a molten glass body by utilizing the complementarity of two fly ash components.

Background technique

The proportion of incineration disposal of urban domestic waste in my country is growing, currently reaching 54% (more than 50%), and the resulting incineration fly ash production is also gradually increasing, because fly ash has high chlorine and high alkali characteristics , with characteristics such as high water-soluble salt content and accumulation of heavy metals and dioxin-like substances, its treatment and disposal will also face huge challenges.

Fly ash treatment technologies include solidification/stabilization landfill, high-temperature sintering, cement kiln co-processing, plasma melting, high-temperature melting and other technologies. For landfill, cement or stabilizer is usually used to solidify and stabilize the fly ash, and then it is landfilled. At present, about 80% of fly ash in the country is treated in this way. However, due to problems such as volume expansion caused by cement solidification, large occupation of land resources, the need for further exploration of stability, and the inability to recover valuable metals, the application of landfill technology will be limited in the future. gradually decreases. For sintering technology, fly ash is mixed with clay or flux, partially melted at high temperature, and cooled to form a sintered product. The advantage of this technology is that the entire process can recover some heavy metals and soluble salts, and prepare ceramsite, sintered bricks, lightweight aggregates, etc. However, the high-temperature process causes volatile metals to enter the flue gas, making it more difficult to treat the tail gas. Cement kiln co-processing technology uses fly ash as cement raw material to fix heavy metals in fly ash to cement clinker and completely decompose dioxins. It not only saves the use of cement raw materials, but also reduces the environmental risk of dioxin. Although this technology has received increasing attention in recent years, some cement kiln co-processing fly ash projects have been carried out across the country. However, salt, sulfur, and chlorine elements can easily cause clogging of cement kilns, and the stability of heavy metals in cement products needs to be further determined. , The large-scale application of this technology still needs a lot of practice and testing. Plasma melting technology uses high-temperature plasma to melt fly ash and then cool it to form glass slag. Dioxins and furans are effectively degraded. Not only is the volume of the slag reduced to one-third of its original size, but the slag formed has obvious leaching characteristics. Improved, with high stability and security. Although this technology has remarkable processing effects and obvious advantages, high energy consumption has always been an important factor limiting its widespread use.

High-temperature melting technology is a fly ash treatment technology that combines detoxification and resource utilization. By using high-temperature heating, the fly ash crystals are rearranged, melted and crystallized, and then cooled to form a dense and stable glass body. It not only completes the detoxification of heavy metals, but also can use the stable glass body as construction and roadbed materials to achieve volume reduction, resource utilization and harmlessness of fly ash. Therefore, this technology has attracted more and more attention.

However, high-temperature melting usually uses high temperatures greater than 1400°C for processing, which requires long reaction times and high energy consumption. It also mixes general industrial solid waste and hazardous waste, increasing the amount of hazardous waste disposal and environmental risks. To sum up, the current method of preparing glass body by melting fly ash has the following three problems:

(1) The reaction temperature is too high and energy consumption is large

(2) The stability of the vitreous body is poor and there are environmental risks

(3) Resource-based products have low value.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art, at least to a certain extent.

To this end, the first purpose of the present invention is to propose a method for preparing a molten glass body using the complementarity of two fly ash components, including the following processes:

Mix grate furnace fly ash and fluidized bed fly ash evenly and put them into the crucible;

Put the crucible into the muffle furnace, set the temperature, program the temperature to rise to a certain temperature and then keep it warm for a certain period of time;

During the heat preservation process, close the air inlet valve and open the air outlet valve to maintain a reducing atmosphere in the furnace, which is conducive to the reduction of Fe oxides, etc. In other words, the iron-loving heavy metals enter the iron phase and form an alloy with iron, and are enriched in the form of ferroalloy products. Collect and recycle using magnets by crushing into powder using the magnetism of the product.

After the heat preservation is completed, immediately take out the crucible from the muffle furnace, wait for it to cool down naturally, then crush the crucible, take out the glass body, and then crush the glass body with a crusher into powder that can pass a 50-mesh sieve, and use a magnet to recover and weigh it. The distribution of elements is then observed with a scanning electron probe.

The present invention utilizes the complementary composition of grate furnace fly ash and fluidized bed fly ash to form a Ca-Si-Al material glass body with good stability under high-temperature melting conditions, while also lowering the melting temperature and energy consumption. Effectively realize the common detoxification and resource utilization of two hazardous wastes. Fly ash is characterized by high contents of Ca (approximately 31.26%-45.29%), Si (approximately 1.21%-1.56%), Al (approximately 0.173%-0.842%), and Cl (approximately 17%-20%). Fluidized bed fly ash is produced through the circulating fluidized bed waste incineration treatment system. The amount produced is 10-15% of the incineration amount. The relative contents of Fe, Al and Si are relatively high, Ca (about 25.94%-34.42%), Si (about 5.23%-12.67%), Al (about 3.97%-8.95%), Cl (about 3.2%-8.32%). By using two hazardous wastes to prepare a vitreous body, the operation steps are simpler, the economic cost is low, and the melting temperature is lowered (lower energy consumption). The prepared vitreous body has good stability and safety (such as good heavy metal fixation effect and low leaching toxicity). Therefore, it has good application prospects and realizes the co-processing of two kinds of fly ash (hazardous waste) at the same time, and can also realize the recycling of metals.

Preferably, the mass ratio of the grate furnace fly ash and the fluidized bed fly ash is 1:9 to 3:2. According to thermodynamic analysis, the CaO-Al ₂ O ₃ -SiO ₂ system melts, and the mass ratio of the three The more balanced it is, the lower the melting point and the easier it is to produce a glass body. The grate furnace fly ash is a high calcium, low silicon and low aluminum system, while the fluidized bed fly ash is a relatively low calcium, high silicon and high aluminum system. By regulating the mass ratio of the two fly ash, the CaO and Al in the mixed fly ash system are controlled. The content of ₂ O ₃ and SiO ₂ makes the quality of the three more balanced, thereby generating a glass body.

Preferably, the grate furnace fly ash is fly ash produced by a mechanical incinerator, and the fluidized bed fly ash is fly ash produced by a fluidized bed incinerator. By melting the fly ash containing hazardous waste in 2 Preparing glass not only enables the recycling of waste, but also the recycling of hazardous waste.

Preferably, the content ratio of Ca element in the grate furnace fly ash and the fluidized bed fly ash is 0.12-1.6.

Preferably, the content ratio of Si element in the grate furnace fly ash and the fluidized bed fly ash is 0.03-0.43.

Preferably, the content ratio of Al element in the grate furnace fly ash and the fluidized bed fly ash is 0.02-0.29.

Preferably, the specific process of mixing the grate furnace fly ash and the fluidized bed fly ash is: using the grid sampling method, put the grate furnace fly ash and the fluidized bed fly ash into a vortex oscillator and vibrate for 10 -15min, the composition of fly ash is complex, and the grid sampling method can ensure that the obtained sample composition is uniform and representative.

Preferably, the crucible is a graphite crucible. After the fly ash is added to the crucible, the crucible needs to be covered with a lid to prevent the volatilization of heavy metals and other elements during high temperature processes. The main component of the corundum crucible is Al ₂ O ₃ , which will interact with the fly ash system. Melting is not suitable for the reaction of alkaline substances such as fly ash, and will affect the formation of products. The main components of graphite crucible are graphite, silicon carbide, silica, refractory clay, etc. They will not react with the fly ash system, so they will not affect the melting reaction. However, since it contains graphite, which provides carbon elements, in order not to provide additional reduced carbon in the fly ash reduction system and interfere with the original reaction, the graphite crucible will be heated and kept at 1000°C for one hour each before the fly ash experiment, and then burned. The carbon in the graphite crucible was volatilized before using the carbon-free graphite crucible for the fly ash melting experiment.

Preferably, the programmed temperature rise process of the muffle furnace is: from 25°C to 1300°C, the temperature rise time is 1.5h, and the temperature rise rate is 12-20°C/min.

Preferably, the heat preservation temperature is 1300°C and the heat preservation time is 2.5 hours.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

Figure 1 is a flow chart of a method for preparing a molten glass body using two complementary fly ash components according to Embodiment 1 of the present invention;

Figure 2 is an XRD analysis test chart of the products prepared in Examples 1-6 and Comparative Example 1 of the present invention;

Figure 3 is an SEM image of the material in Example 1 of the present invention;

Figure 4 is an SEM image of the material in Example 1 of the present invention;

Figure 5 is an SEM image of the material in Example 4 of the present invention;

Figure 6 is an SEM image of the material in Comparative Example 1 of the present invention;

Figure 7 is an SEM image of the material in Comparative Example 1 of the present invention;

Figure 8 is the morphology of the product samples obtained in Examples 1-6 and Comparative Example 1.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and are not to be construed as limiting the present invention.

In order to realize the recovery of fly ash and the preparation of glass body, this application uses two complementary components of fly ash to prepare molten glass body, which is specifically recorded in the following examples.

Example 1:

Referring to Figure 1, a method for preparing a molten glass body using the complementarity of two fly ash components includes the following processes:

Step 1: Use the grid sampling method to take the grate furnace fly ash produced by the mechanical incinerator and the fluidized bed fly ash produced by the fluidized bed incinerator. The Ca element in the grate furnace fly ash and fluidized bed fly ash is The mass ratio is 0.12-1.6, the mass ratio of Si element in grate furnace fly ash and fluidized bed fly ash is 0.03-0.43, and the mass ratio of Al element in grate furnace fly ash and fluidized bed fly ash is 0.02-0.29 , then put the grate furnace fly ash and fluidized bed fly ash into the vortex oscillator in a mass ratio of 1:9, shake for 10 minutes, mix evenly, and then put them into the graphite crucible, and the graphite crucible needs to be covered with a crucible lid to prevent The volatilization of heavy metals and other elements during high temperature processes;

Step 2: Put the graphite crucible into the muffle furnace, set the temperature, and program the temperature to rise from 25°C to 1300°C. The heating time is 1.5h, the heating rate is 12~20°C/min, and the temperature is maintained after rising to 1300°C. 2.5h;

Step 3: During the heat preservation process, close the air inlet valve, open the air outlet valve, and block air to maintain a reducing atmosphere, which is conducive to the reduction of Fe oxides, etc.;

Step 4: Immediately after the 1300°C insulation is completed, take out the crucible, place it in a stable room temperature environment to cool naturally, then crush the crucible, take out the glass body, crush the glass body with a crusher into powder that can pass a 50-mesh sieve, use a magnet to recover and weigh , observing the distribution of elements through a scanning electron probe.

Example 2:

A method of preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 1:4.

Example 3:

A method of preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 3:7.

Example 4:

A method of preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 2:3.

Example 5:

A method of preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 1:1.

Example 6:

A method of preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 3:2.

Comparative example 1:

A method for preparing molten glass body by utilizing the complementarity of two fly ash components. The specific preparation process is the same as Example 1, but the mass ratio of grate furnace fly ash and fluidized bed fly ash is 7:3.

The products prepared in the above-mentioned Examples 1-6 and Comparative Example 1 were subjected to XRD analysis and testing. The specific test results are shown in Table 1 and Figure 2.

Table 1 XRD analysis test results of the products prepared in Examples 1-6 and Comparative Example 1

It can be seen from Table 1 and Figure 2 that when the mass ratio of grate furnace fly ash and fluidized bed fly ash reaches 7:3, no glass body is produced. From this, it can be seen that the mass ratio of grate furnace fly ash and fluidized bed fly ash is glass body. has a great influence on the production of CaO-Al ₂ O ₃ -SiO ₂ system. The more balanced the mass ratio of the three is, the lower the melting point is and the easier it is to produce glass body. The grate furnace fly ash is a high-calcium, low-silicon and low-aluminum system, while the fluidized bed fly ash is a relatively low-calcium, high-silicon and high-aluminum system. By adjusting the amounts of the two fly ash, the CaO and Al ₂ in the mixed fly ash system are controlled. The content of O ₃ and SiO ₂ makes the quality of the three more balanced, thereby generating a glass body.

As can be seen from Figures 3-7, SEM analysis of the products prepared in Example 1, Example 4 and Comparative Example 1 shows that when the mass ratios of grate furnace fly ash and fluidized bed fly ash are 1:9 and 2:3 , can generate glass body, and metal Fe is generated, but when the mass ratio of grate furnace fly ash and fluidized bed fly ash reaches 7:3, glass body cannot be generated at this time, the metal generated is FeS, and no metal element is generated. .

In addition, if the grate furnace fly ash is directly used for melting experiments, the temperature required to generate glass body is generally above 1600 degrees.

The leaching toxicity of the glass materials prepared in the above examples and comparative examples was measured. The specific measurement results are shown in Table 2.

Table 2 Toxicity leaching results of glass materials (mg/L)

As can be seen from Table 2, the obtained vitreous material was subjected to toxic leaching according to the "Technical Requirements for Solid Waste Vitrification Treatment Products" (GB/T 41015-2021). It can be seen from the table that if the vitreous body is treated as general solid waste, the leaching toxicity of the HJ/T300-2007 acetate buffer method meets the entry landfill toxicity limit requirements specified in the Domestic Waste Landfill Pollution Control Standard (GB 16889-2007) . At the same time, if used as building materials or sandblasting raw materials, the glass body still meets the requirements for heavy metals such as Cu, Ni, Cr, Pb, Zn, Cd, and As in the Class III groundwater index limits (GB/T 14848). The leaching toxicity of the vitreous body formed by fluidized bed fly ash and the non-vitreous product (mass ratio of 7:3) is basically slightly higher than that of the vitreous product (mass ratio of 1:4, 3:7, 3:2). The leaching toxicity shows that the molten glass body produced by the two types of fly ash with complementary characteristics has good heavy metal fixation and environmental stability, which is conducive to further exploration of its application in the environment and materials.

In addition, Figure 8 records the morphology of the product samples obtained in Examples 1-6 and Comparative Example 1. It can be seen from the figure that at a high temperature of 1300°C, the mass ratio of grate furnace fly ash to fluidized bed fly ash is Vitreous body was produced when the mass ratio was 1:9-3:2, but no vitreous body was produced when the mass ratio was 7:3-9:1. The resulting glass body has a smooth and shiny surface, a dense structure and a hard texture, which can effectively fix heavy metals and serve as an alternative building material. However, samples without vitreous body are fluffy, porous, and brittle, making it difficult to utilize resources.

In the description of this specification, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

In the present invention, unless otherwise expressly stated and limited, a first feature being "on" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. touch. Furthermore, the terms "above", "above" and "above" the first feature is above the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "below" and "beneath" the first feature to the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature has a smaller horizontal height than the second feature.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "an example," "specific examples," or "some examples" or the like means that specific features are described in connection with the embodiment or example. , structures, materials or features are included in at least one embodiment or example of the invention. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification unless they are inconsistent with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are illustrative and should not be construed as limitations of the present invention. Those of ordinary skill in the art can make modifications to the above-mentioned embodiments within the scope of the present invention. The embodiments are subject to changes, modifications, substitutions and variations.

Claims (5)

1. A method for preparing a molten glass body by utilizing the complementarity of two fly ash components, which is characterized by comprising the following steps:

uniformly mixing fire grate fly ash and fluidized bed fly ash according to the mass ratio of 1:9-3:2, and then placing the mixture into a crucible, wherein the fire grate fly ash is a high-calcium low-silicon low-aluminum system, the fluidized bed fly ash is a relatively low-calcium high-silicon high-aluminum system, and CaO and Al in the mixed fly ash system are regulated and controlled by regulating and controlling the mass ratio of the two fly ash ₂ O ₃ 、SiO ₂ The quality of the three materials is more balanced, so that a glass body is generated, the fly ash of the grate furnace is the fly ash generated by the mechanical incinerator, and the fly ash of the fluidized bed is the fly ash generated by the fluidized bed incinerator;

placing the crucible into a muffle furnace, setting the temperature, and preserving heat for 2.5 hours after the temperature is raised to 1300 ℃, wherein the temperature programming process of the muffle furnace is as follows: heating from 25 ℃ to 1300 ℃, wherein the heating time is 1.5h, and the heating rate is 12-20 ℃/min;

closing an air inlet valve and opening an air outlet valve in the heat preservation process, and keeping a reducing atmosphere in the furnace to enable the iron-philic heavy metal to enter an iron phase to form an alloy with iron, so that the iron alloy is enriched in the form of an iron alloy product;

and after the heat preservation is finished, immediately taking out the crucible from the muffle furnace, cooling, breaking the crucible, taking out the vitreous body, crushing the vitreous body into powder capable of passing through a 50-mesh sieve by using a crusher, and recycling and weighing by using a magnet, wherein the cooling mode is natural cooling.

2. The method for producing a molten glass body using complementarity of two kinds of fly ash components according to claim 1, wherein the ratio of the content of Ca element in the furnace fly ash to the content of Ca element in the fluidized bed fly ash is 1.6.

3. The method for producing a molten glass body using complementarity of two fly ash components according to claim 1, wherein the ratio of the content of Si element in the furnace fly ash to the content of Si element in the fluidized bed fly ash is 0.03 to 0.43.

4. The method for producing a molten glass body using complementarity of two fly ash components according to claim 1, wherein the ratio of the content of Al element in the furnace fly ash to the content of Al element in the fluidized bed fly ash is 0.02 to 0.29.

5. The method for preparing a molten glass body using complementarity of two components of fly ash according to claim 1, wherein the specific process of mixing the furnace fly ash and the fluidized bed fly ash is: and (3) placing the fire grate fly ash and the fluidized bed fly ash into a vortex oscillator to oscillate for 10-15min by using a lattice sampling method.