Method for preparing all-solid waste glass ceramic from stainless steel slag and fly ash

Abstract

The invention provides a method for preparing all-solid waste glass ceramic by using stainless steel slag and fly ash, which comprises the following steps: mixing the stainless steel slag and fly ash as raw materials in proportion, and heating in a high-temperature furnace until the raw materials are molten; carrying out casting molding on the glass melt, demolding, heating, and annealing to obtain base glass; and carrying out crystallization heat treatment on the base glass to obtain the glass ceramic. According to the method, the self-nucleation function of heavy metal elements in the solid waste is fully utilized, harmful heavy metal is solidified in a diopside phase and an akermanite crystal phase, and high-value utilization and harmless treatment of the stainless steel slag and the coal ash are achieved. The raw materials of the glass ceramic are all industrial solid wastes, so that the secondary utilization of industrial solid waste resources is fully realized, the harm of the industrial solid wastes to the environment is reduced, and the glass ceramic conforms to the national current policies of energy conservation, emission reduction and sustainable development.

Description

Technical Field

[0001] The present invention relates to the fields of glass-ceramics preparation and solid waste resource utilization, and particularly to a method for preparing all-solid-waste glass-ceramics using stainless steel slag and fly ash as raw materials. Background Art

[0005] After the toxic heavy metals and a small amount of radioactive elements in coal are cooled after high-temperature combustion above 1000 °C, there will still be a certain amount of toxic substances in fly ash. After that, fly ash is stacked in the open air for a long time, and the toxic and harmful substances will disperse into the surrounding area and pollute the environment. Therefore, in the face of the environmental pollution problem caused by fly ash, it is necessary to improve the comprehensive utilization of fly ash.

[0006] Compared with conventional glass and metal materials, glass-ceramics have excellent properties and are widely used in mechanical engineering, construction, power industry and other aspects. At present, there are many technical problems in the preparation of glass-ceramics in terms of raw material selection, formula design, melting, crystallization treatment, etc. How to make full use of solid waste and stably fix the heavy metal elements in solid waste in glass-ceramics products is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] The present invention provides a method for preparing all-solid-waste glass-ceramics, which can realize the high-value utilization of industrial solid waste, and the prepared glass-ceramics material can effectively solidify heavy metals and reduce environmental hazards.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing all-solid-waste glass-ceramics using stainless steel slag and fly ash, the method comprising the following steps:

[0010] (1) By weight percentage, the glass-ceramics raw materials are: 50-80% of stainless steel slag and 50-20% of fly ash. Weigh each raw material, mix them evenly to obtain a mixture.

[0011] (2) Place the mixture in a high-temperature resistant crucible and put it into a high-temperature furnace for heating and melting.

[0012] (3) Pour the glass melt into a mold, form it, and after demolding, put it into a muffle furnace for annealing, and then cool it naturally with the furnace to obtain a base glass.

[0013] (4) Put the base glass into a crystallization furnace for crystallization heat treatment. The crystallization temperature is 800 °C - 920 °C, and keep it at this temperature for 1 - 4 h, and then cool it to room temperature with the furnace to obtain glass-ceramics.

[0014] Preferably, the melting temperature is 1420 - 1520 °C, and it is held at this temperature for 2 - 3 h.

[0015] Preferably, the annealing temperature is 500 °C - 600 °C, and the annealing time is 1 - 4 h.

[0016] Preferably, the method of crystallization heat treatment is: heating the base glass from room temperature to 800 °C - 920 °C for crystallization at a heating rate of 2 - 5 °C / min, and holding at this temperature for 1 - 4 h.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The glass - ceramics of the present invention use stainless - steel slag and fly ash as raw materials. Fly ash mainly contains components such as Al2O3 and SiO2. The stainless - steel slag has relatively high contents of CaO and SiO2, and contains a certain amount of MgO components, heavy - metal oxides and fluorides, which are good nucleating agents for preparing glass - ceramics. Therefore, by taking advantage of the complementary advantages of the components of stainless - steel slag and fly ash, and scientifically designing the raw material ratio, excellent - performance CaO - MgO - Al2O3 - SiO2 - based all - solid - waste glass - ceramics are successfully prepared without the need to additionally add chemical reagents (including nucleating agents), showing good technological innovation.

[0019] (2) The present invention fully utilizes the self - nucleation function of heavy - metal elements in solid waste. The obtained glass - ceramics solidify harmful heavy metals in the diopside phase and gehlenite crystal phase, realizing the high - value utilization and harmless treatment of stainless - steel slag and fly ash.

[0020] (3) Performance tests show that the heavy - metal leaching rate of the glass - ceramics of the present invention is far lower than the national standard, and the solidification effect of heavy metals in solid waste is good; the product has excellent performance, with a flexural strength of 170 - 184 MPa, a micro - hardness of 7 - 9 GPa, and acid - alkali resistance above 95%, having the advantages of high strength, high hardness, and strong acid - alkali resistance.

[0021] (4) The present invention can realize the large - scale resource utilization of two industrial solid wastes, stainless - steel slag and fly ash, reduce the environmental pollution caused by solid waste, greatly reduce production costs, and save energy and protect the environment. The product glass - ceramics can be widely applied in fields such as construction, chemical engineering, and mechanical engineering, having good economic and social benefits. Description of the Drawings

[0022] Figure 1 It is the XRD pattern of the product glass - ceramics in Examples 1 - 4;

[0023] Figure 2 It is the SEM image of the glass - ceramics in Examples 1 - 4;

[0024] Figure 3It is the solidification positions of heavy metals Cr, Ni, and Mn in the glass-ceramics in Example 2. Detailed implementation manners

[0025] The following further elaborates on the detailed implementation manners of the present invention in conjunction with the examples.

[0026] Example 1 A method for preparing all-solid waste glass-ceramics using stainless steel slag and fly ash, the specific steps are as follows:

[0027] (1) Select stainless steel slag and fly ash, and grind the stainless steel slag and fly ash respectively so that their particle sizes both reach 100 - 200 mesh. The mass percentage compositions of the stainless steel slag and fly ash are as follows:

[0028] Stainless steel slag: CaO 40.78%, SiO₂ 28.55%, MgO 5.98%, Al₂O₃ 8.00%, Cr₂O₃ 1.82%, Fe₂O₃ 5.00%, NiO 0.09%, MnO 1.08%, K₂O + Na₂O 2.20%, CaF₂ 4.55%, others 1.95%.

[0029] Fly ash: SiO₂ 52.23%, Al₂O₃ 36.54%, CaO 5.26%, Fe₂O₃ 5.01%, others 0.96%.

[0030] (2) According to the mass ratio of stainless steel slag to fly ash in Table 1 being 5:5 for batching, weigh 200 g of stainless steel slag and 200 g of fly ash, put them into a ball mill and ball mill for 3 hours.

[0031] Table 1 Formulations of stainless steel slag and fly ash in Examples 1 - 4

[0032]

[0033] (3) Melting: Put the mixed raw materials into a high-temperature furnace, heat them to 1500 °C at a heating rate of 5 °C / min, and keep them warm for 3 hours; pour the molten glass liquid into a metal mold, after demolding, place it in an annealing furnace, anneal at 600 °C for 2 hours, and naturally cool to room temperature with the furnace to obtain the base glass.

[0034] (4) Crystallization: Put the base glass into a crystallization furnace, heat it to 820 °C at a heating rate of 5 °C / min, keep it warm for 4 hours and then naturally cool to room temperature to obtain the glass-ceramic product TF1.

[0035] Example 2 A method for preparing all-solid waste glass-ceramics using stainless steel slag and fly ash, the specific steps are as follows:

[0036] (1) The properties and requirements of the raw materials are the same as those in Example 1.

[0037] (2) Weigh 240 g of stainless steel slag and 160 g of fly ash according to Table 1, and put them into a ball mill for mixing for 3 hours.

[0038] (3) Melting: Put the mixed raw materials into a high-temperature furnace, heat them to 1520 °C at a heating rate of 5 °C / min, and keep them at this temperature for 3 hours; Pour the molten glass into a metal mold, demold it and place it in an annealing furnace, anneal it at 550 °C for 2 hours, and then naturally cool it to room temperature in the furnace to obtain the base glass.

[0039] (4) Crystallization: Put the annealed base glass into a crystallization furnace, heat it to 850 °C at a heating rate of 5 °C / min, keep it at this temperature for 3 hours, and then naturally cool it to room temperature to obtain the glass-ceramic product TF2.

[0040] Example 3 A method for preparing all-solid waste glass-ceramics using stainless steel slag and fly ash, the specific steps are as follows:

[0041] (1) The properties and requirements of the raw materials are the same as those in Example 1.

[0042] (2) Weigh 280 g of stainless steel slag and 120 g of fly ash according to Table 1, and put them into a ball mill for mixing for 3 hours.

[0043] (3) Melting: Put the mixed raw materials into a high-temperature furnace, heat them to 1450 °C at a heating rate of 5 °C / min, and keep them at this temperature for 3 hours; Pour the molten glass into a metal mold, demold it and place it in an annealing furnace, anneal it at 600 °C for 2 hours, and then naturally cool it to room temperature in the furnace to obtain the base glass.

[0044] (4) Crystallization: Put the annealed base glass into a crystallization furnace, heat it to 880 °C at a heating rate of 5 °C / min, keep it at this temperature for 4 hours, and then naturally cool it to room temperature to obtain the glass-ceramic product TF3.

[0045] Example 4 A method for preparing all-solid waste glass-ceramics using stainless steel slag and fly ash, the specific steps are as follows:

[0046] (1) The properties and requirements of the raw materials are the same as those in Example 1.

[0047] (2) Weigh 320 g of stainless steel slag and 80 g of fly ash according to Table 1, and put them into a ball mill for mixing for 3 hours.

[0048] (3) Melting: Put the mixed raw materials into a high-temperature furnace, heat them to 1500 °C at a heating rate of 5 °C / min, and keep them at this temperature for 3 hours; Pour the molten glass into a metal mold, demold it and place it in an annealing furnace, anneal it at 600 °C for 2 hours, and then naturally cool it to room temperature in the furnace to obtain the base glass.

[0049] (4) Crystallization: The annealed base glass was placed in a crystallization furnace and heated to 910 °C at a heating rate of 5 °C / min. After holding for 3 hours, it was naturally cooled to room temperature to obtain the glass-ceramic product TF4.

[0050] Product Structure and Performance Detection of Example 5

[0051] The products in the examples were subjected to structural and performance analysis.

[0052] 1. Product Microstructure

[0053] Figure 1 XRD patterns of the glass-ceramics TF1 - TF4 of the products in the examples. It can be seen from the figure that the main crystal phase of the glass-ceramics is diopside, and the secondary crystal phase akermanite appears in TF3 and TF4.

[0054] Figure 2 SEM images of the products in the examples. It can be seen that the crystals of glass-ceramics TF1, TF2, and TF3 are regular granular, and the crystals of TF4 are mainly strip-shaped crystals.

[0055] Figure 3 The solidification positions of heavy metals in the glass-ceramic TF1 of the product in the example, combined with Figure 1 It can be known that heavy metals Cr and Mn in the solid waste are mainly solidified in the crystals, while heavy metal Ni is distributed in both the crystals and the glass phase.

[0056] 2. Product Performance

[0057] (1) To test the solidification effect of the glass-ceramics of the present invention on harmful heavy metals, the heavy metal leaching rates of the raw materials stainless steel slag, fly ash, base glass, and glass-ceramics of the examples were respectively tested. The test method refers to HJ / T 300 - 2007 "Solid Waste - Leaching Toxicity Leaching Method - Acetic Acid Buffer Solution Method".

[0058] The results show that the heavy metal leaching concentrations of the product glass-ceramics are lower than those of the solid waste raw materials and the base glass, and are far lower than the upper limit requirements of Cr: 5.0 mg / L, Ni: 10.0 mg / L, and Mn: 5.0 mg / L specified in the national standard "Identification Standard for Hazardous Wastes - Identification of Leaching Toxicity" (GB 5085.3 - 2007). This indicates that the glass-ceramics of the present invention have a good solidification effect on heavy metals in solid waste.

[0059] The heavy metal leaching rates of the raw materials, base glass, and products in the examples are shown in Table 2 below, where TF1 - TF4 correspond to the products of Examples 1 - 4 respectively.

[0060] Table 2 Heavy Metal Leaching Rates of Raw Materials, Base Glass, and Products in Examples

[0061]

[0062] (2) Performance testing shows that the flexural strength of the glass-ceramics of the present invention is 170 - 184 MPa, the microhardness is 7 - 9 GPa, and the acid and alkali resistance is over 95% (reference standard JC / T 2283 - 2014 - Slag Microcrystalline Glass Pipes); it has the advantages of high strength, high hardness, and strong acid and alkali resistance.

Claims

1. A method for preparing all-solid waste glass ceramics using stainless steel slag and fly ash, characterized in that, The method comprises the following steps: (1) In terms of weight percentage, the glass-ceramic raw materials are: 50-80% of stainless steel slag and 50-20% of fly ash. Weigh each raw material and mix them evenly to obtain a mixture; (2) Place the mixture in a high-temperature resistant crucible and heat it to melt in a high-temperature furnace; (3) Pour the glass melt into a mold, form it, demold it and then put it into a muffle furnace for annealing, and then cool it naturally in the furnace to obtain the base glass; (4) Put the base glass into a crystallization furnace for crystallization heat treatment. The crystallization temperature is 800°C - 920°C, and keep it at this temperature for 1-4h, and then cool it to room temperature in the furnace to obtain the glass-ceramic.

2. The method according to claim 1, characterized in that, The melting temperature is 1420 - 1520°C, and keep it at this temperature for 2-3h.

3. The method according to claim 1, wherein The annealing temperature is 500°C - 600°C, and the annealing time is 1-4h.

4. The method according to claim 1, wherein The method of crystallization heat treatment is: heat the base glass from room temperature to 800°C - 920°C for crystallization at a heating rate of 2-5°C / min, and keep it at this temperature for 1-4h.

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