Infrared luminescent glass-ceramics prepared from rare earth-containing blast furnace slag of Baiyunebo and method thereof

Abstract

The application discloses an infrared luminescent glass-ceramics prepared from Bayin Obo rare earth-containing blast furnace slag and a method thereof, and belongs to the technical field of solid waste resource utilization and glass-ceramics. The application uses Bayin Obo rare earth-containing blast furnace slag as a main raw material, adds pure chemical reagents such as silicon dioxide, aluminum oxide and calcium oxide, and adopts a melting method to perform melting, casting forming, annealing and crystallization heat treatment, so as to obtain Nd-containing infrared luminescent silicate glass-ceramics. 3+ The application activates natural symbiotic Nd elements in the rare earth-containing blast furnace slag in situ, so that the Nd elements are uniformly solid-solved in the crystal phase. The prepared glass-ceramics presents 1065 nm near-infrared characteristic luminescence under 585 nm visible light excitation. The method does not need to additionally add high-purity rare earth reagents, greatly reduces the raw material cost, realizes high-value and green utilization of the rare earth-containing blast furnace slag, and the product can be used in the fields of laser materials, infrared detection, optical communication and the like.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and functional microcrystalline glass preparation technology, specifically to a method for preparing Nd-containing infrared luminescent silicate microcrystalline glass using Bayan Obo rare earth-containing blast furnace slag (REBFS) as the main raw material. Background Technology

[0002] Infrared luminescent silicate microcrystalline glass, as a novel functional inorganic non-metallic material, combines the formability of glass with the excellent optical properties of crystals, and has wide applications in laser devices, bioimaging, infrared sensing, photothermal therapy, and optical communication. Neodymium (Nd), as a typical lanthanide rare earth element, possesses a unique 4f electron level structure. 3+ It can generate 1065nm characteristic near-infrared emission under 585nm visible light excitation, and is one of the core activating ions of near-infrared luminescent materials. It has wide applications in functional materials such as laser glass and luminescent ceramics.

[0003] Currently, the preparation of Nd-doped infrared luminescent glass-ceramics mainly uses high-purity chemical reagents as raw materials. This not only results in high production costs and the consumption of scarce rare earth resources, but also requires precise control of Nd element dispersion during the preparation process. Ion aggregation can easily lead to luminescence quenching, causing a decrease in the material's optical performance. Meanwhile, the development and utilization of the Bayan Obo rare earth iron ore mine generates a large amount of blast furnace slag. This solid waste is rich in key components of silicate glass-ceramics such as Si, Al, Ca, and Mg, and also contains rare earth elements such as La, Ce, and Nd. The co-existing Nd₂O₃ content is approximately 0.32 wt%, making it a natural reserve of rare earth elements and possessing the advantage of raw materials for preparing rare earth luminescent glass-ceramics. However, current REBFS (Rare Earth-Doped Glass-Ceramic Fibers) are mostly stored in stockpiles, which not only occupies a large amount of land resources but also easily causes problems such as the loss of valuable rare earth elements and dust pollution.

[0004] Silicate glass-ceramics possess excellent chemical stability, thermal stability, and optical transmittance, making them ideal matrix materials for infrared luminescent materials. Their three-dimensional glass network, composed of silicate polyhedra, provides stable doping and storage sites for rare earth ions. Existing research primarily uses industrial solid waste such as tailings and slag as raw materials to prepare structural glass-ceramics, focusing on improving the material's mechanical properties. Research on preparing luminescent glass-ceramics from rare earth-containing solid waste is limited, and in-situ activation of co-occurring Nd elements in REBFS and precise control of infrared luminescence performance have not yet been achieved.

[0005] Furthermore, it is usually difficult to achieve the controllable precipitation of the target crystalline phase when using industrial solid waste such as tailings and slag to prepare microcrystalline glass. Other crystalline phases are easily generated during the crystallization process, which is not conducive to further improving the luminescent properties of microcrystalline glass. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing Nd-containing infrared luminescent microcrystalline glass using REBFS.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] Infrared luminescent microcrystalline glass prepared using rare-earth-containing blast furnace slag from Bayan Obo has a basic composition of SiO2 50–56 wt%, Al2O3 5–11 wt%, MgO 8–14 wt%, and CaO 19–25 wt%. The preparation process uses Bayan Obo rare-earth-containing blast furnace slag as the main raw material, with the addition of chemical reagents SiO2, Al2O3, MgO, and CaO. Based on the basic composition of the microcrystalline glass and the measured content of each component in the Bayan Obo rare-earth-containing blast furnace slag, the added SiO2, Al2O3, MgO, and CaO were recalculated and corrected before batching. Through a heat treatment process, the Nd element co-occurring in the Bayan Obo rare-earth-containing blast furnace slag is converted into Nd... 3+ The form is dissolved in the crystalline phase and glass phase structure of the microcrystalline glass to obtain the near-infrared luminescent microcrystalline glass.

[0009] The raw materials for this microcrystalline glass are prepared according to the above-mentioned basic glass formulation. Based on the content of each component in the REBFS, other chemical components are added to maintain the overall stability of the basic glass system. The raw material formulation for this microcrystalline glass is as follows: 40-60 wt% rare earth blast furnace slag from Bayan Obo, 30-45 wt% silica, 0.45-3.5 wt% alumina, 4-7 wt% magnesium oxide, and 1.2-10 wt% calcium oxide.

[0010] A method for preparing infrared luminescent microcrystalline glass using rare earth-containing blast furnace slag from Bayan Obo includes the following steps:

[0011] (1) Weigh each raw material according to the formula of microcrystalline glass raw materials, mix each raw material to obtain a mixture;

[0012] (2) The mixture is placed in a high-temperature resistant crucible and then placed in a muffle furnace. It is heated to 1400-1500℃ through a gradient heating process and melted at high temperature to obtain a homogeneous rare earth Nd-containing material. 3+ molten glass;

[0013] (3) The glass melt is poured into a mold to form a shape, and after demolding, it is placed in a muffle furnace for annealing to obtain annealed glass;

[0014] (4) The annealed glass is subjected to crystallization heat treatment to regulate the precipitation of crystalline phase and obtain infrared luminescent microcrystalline glass.

[0015] The gradient heating process is as follows: first, the mixture is heated to 1000℃ at a heating rate of 3℃ / min and held for 2 hours; then, it is heated to 1400-1500℃ at a heating rate of 3℃ / min and held for 3 hours.

[0016] The annealing temperature was 600℃, the annealing time was 2 hours, and the furnace was cooled to room temperature after annealing.

[0017] The crystallization heat treatment method is as follows: the annealed glass is heated from room temperature to 1000℃ at a heating rate of 3℃ / min and held at that temperature for 2 hours to crystallize; finally, it is cooled to room temperature in the furnace and removed from the furnace to obtain infrared luminescent microcrystalline glass.

[0018] This invention fully leverages the resource value of REBFS, directly utilizing its naturally occurring Nd element as an in-situ luminescent ion. Simultaneously, it relies on its rich silicate matrix components to replace some high-purity chemical reagents. Through precise control of raw material ratios, melting process parameters, and crystallization heat treatment, Nd... 3+ By achieving uniform distribution of the microcrystalline phase within the glass-ceramic phase, silicate microcrystalline glass with excellent near-infrared luminescence properties was successfully prepared.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) This invention achieves the directional precipitation of the pyroxene main crystalline phase by controlling the basic glass formulation and heat treatment process. The pyroxene phase lattice is rich in Ca... 2+ Lattice sites, crystallization stage of Nd 3+ Capable of replacing Ca in the crystal lattice 2+ The light is dissolved and incorporated into the pyroxene crystal structure. The orderliness of the crystal field environment increases the probability of stimulated emission transitions and suppresses non-radiative transition processes such as multiphonon relaxation, thereby significantly improving the luminescence intensity and lifetime of the glass-ceramic. The fluorescence lifetime of the near-infrared luminescent glass-ceramic product of this invention can reach 318.41 μs, which is superior to that of conventional silicate luminescent glasses.

[0021] (2) This invention innovatively adopts an in-situ activation strategy, directly utilizing the naturally occurring Nd element in REBFS as the luminescent ion, without the need to add additional high-purity Nd-based rare earth chemical reagents. This breaks through the dependence of traditional infrared luminescent microcrystalline glass on high-purity rare earth resources, realizing the high-value utilization of rare elements in rare earth solid waste, which is in line with the development concept of green, low-carbon and resource recycling.

[0022] (3) This invention achieves Nd by in-situ activation of co-existing Nd elements in solid waste. 3+ The efficient solid solution and directional modulation of near-infrared luminescence properties in microcrystalline glass phases allow the resulting materials to be applied in functional materials fields such as laser materials, infrared detection, and optical communication.

[0023] Highly efficient solid solution indexing systems can accommodate Nd co-occurring in REBFS with high capacity and uniformity. 3+ No ion agglomeration, no rare earth-rich impurity crystal precipitation, Nd 3+ Stably dispersed in the crystal. This invention utilizes the inherent K-type properties of REBFS. + Na + Ca 2+ Mg 2+ Network modifiers disrupt the silicon-oxygen network structure and reduce the degree of polymerization of the silicon-oxygen network, thereby improving Nd... 3+ Upper limit of melting. The mixture is melted and homogenized for 3 hours to promote Nd2O2 melting. 3+ It diffuses fully in the melt. During the crystallization stage, the pyroxene lattice diffuses Nd through cation substitution and alkali metal charge compensation. 3+ Stable solid solution within the pyroxene lattice, avoiding rare earth element desolvation and precipitation of impurity phases, achieving Nd throughout the entire process. 3+ Efficient solid solution treatment eliminates quenching of luminescence concentration.

[0024] Directional control is divided into directional precipitation of crystal phase and directional distribution of rare earth ions. Directional precipitation of crystal phase limits the quaternary matrix composition range of SiO2–Al2O3–MgO–CaO, ​​constructing a thermodynamic phase-forming system of pyroxene, resulting in the precipitation of only a single pyroxene main crystal phase after heat treatment. The crystallinity and grain size of pyroxene are controlled by varying the amount of REBFS added, achieving directional control over the type, amount, and morphology of crystal phases. Directional distribution of rare earth ions refers to the distribution of Ca cations at the M2 position of the pyroxene lattice. 2+ With Nd 3+ Ion radius matching, Nd during crystallization 3+ Selective lattice substitution occurs, enabling the directional control of rare earth ions in the crystal phase.

[0025] (4) Based on the silicate matrix components such as SiO2, Al2O3, CaO, and MgO that REBFS is rich in, this invention can replace some high-purity chemical reagents, significantly reduce the raw material cost of infrared luminescent microcrystalline glass, and simplify the preparation process, thus having the potential for large-scale industrial application.

[0026] (5) This invention achieves Nd by using a two-stage gradient heating melting and a controllable segmented crystallization heat treatment in synergy. 3+ Uniform dispersion and efficient solid solution, and suppression of Nd from multiple dimensions 3+ Concentration quenching. First, heat to 1000℃ and hold for 2 hours to achieve complete dissociation of the rare earth symbiotic mineral phases in the blast furnace slag, releasing the lattice-bound Nd. 3+ Subsequently, the temperature was raised to 1400–1500℃ for high-temperature isothermal homogenization. The native alkali metal and alkaline earth metal oxides in the system played a network modification role, breaking silicon-oxygen bridged oxygen bonds, reducing the degree of silicon-oxygen network polymerization, and significantly improving Nd... 3+ The limiting solid solution concentration in the melt, eliminating Nd3+ Localized agglomeration and segregation phenomena are observed, achieving a uniform atomic-scale dispersion of rare earth ions in the glass melt. Subsequent annealing at 600℃ eliminates forming thermal stress, followed by a 1000℃ crystallization heat treatment to directionally precipitate the pyroxene main crystalline phase, allowing Nd... 3+ It is stabilized in the pyroxene lattice through cation exchange.

[0027] (6) This invention provides a technical solution for the large-scale resource utilization and functional utilization of rare earth solid waste in Bayan Obo. It not only solves the problems of land occupation and environmental pollution caused by rare earth tailings and slag stockpiles, but also expands the ways to utilize rare earth solid waste at high value. It has important practical significance for promoting the green upgrading of the rare earth solid waste industry. Attached Figure Description

[0028] Figure 1 The images show the spectra of glass-ceramics with different REBFS addition amounts in Examples 1-3.

[0029] Figure 2 Nd2O3 in microcrystalline glass with different REBFS addition amounts in Examples 1-3 3+ Fluorescence lifetime and fluorescence lifetime bar chart.

[0030] Figure 3 The images show the XRD patterns of glass-ceramics with different REBFS addition amounts in Examples 1-3.

[0031] Figure 4 SEM images of glass-ceramics with different REBFS addition amounts in Example 1.

[0032] Figure 5 SEM images of glass-ceramics with different REBFS addition amounts in Example 2.

[0033] Figure 6 SEM images of glass-ceramics with different REBFS addition amounts in Example 3.

[0034] Figure 7 EDS spot scan images of microcrystalline glass with different REBFS addition amounts in Examples 1-3. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described in detail below with reference to examples.

[0036] The rare earth-containing blast furnace slag (REBFS) used in the example has the following composition (wt%):

[0037] The composition is as follows: silicon dioxide (SiO2) 33.55%, calcium oxide (CaO) 33.51%, magnesium oxide (MgO) 10.94%, aluminum oxide (Al2O3) 12.39%, potassium oxide (K2O) 0.61%, sodium oxide (Na2O) 1.06%, ferric oxide (Fe2O3) 0.51%, titanium dioxide (TiO2) 2.34%, manganese dioxide (MnO2) 0.79%, sulfur trioxide (SO3) 2.48%, barium oxide (BaO) 0.44%, lanthanum oxide (La2O3) 0.14%, cerium dioxide (CeO2) 0.71%, neodymium oxide (Nd2O3) 0.32%, and the remaining components 0.21%.

[0038] Microcrystalline glass formulation design:

[0039] The microcrystalline glass of the present invention is based on the quaternary system of SiO2-Al2O3-MgO-CaO, with a basic composition of 50-56 wt% SiO2, 5-11 wt% Al2O3, 8-14 wt% MgO, and 19-25 wt% CaO.

[0040] When designing the microcrystalline glass formulation, rare earth-containing blast furnace slag (REBFS) from Bayan Obo is used as the core raw material, relying on its symbiotic Nd element as in-situ luminescent ions; the ingredients are formulated according to the basic composition of microcrystalline glass, and the chemical reagents added are calculated and corrected based on the measured content of each component of REBFS, so as to maintain the overall stability of the basic composition of the microcrystalline glass system.

[0041] The raw material formulations for each embodiment are shown in Table 1.

[0042] Table 1. Microcrystalline glass raw material formulations (wt%) for each embodiment

[0043]

[0044] Example 1: A method for preparing infrared luminescent glass-ceramics using REBFS

[0045] (1) Weigh each raw material according to the formula of Example 1 in Table 1, put all raw materials into a ball mill, mix them thoroughly and evenly to obtain a homogeneous mixture.

[0046] (2) The homogeneous mixture is loaded into a corundum crucible and placed in a box-type muffle furnace for gradient heating and melting. The heating regime is as follows: heat to 1000℃ at a rate of 3℃ / min and hold for 2 hours; continue heating to 1450℃ at a rate of 3℃ / min and hold at this temperature for 3 hours. After melting, the crucible is quickly removed and the high-temperature glass melt is rapidly poured into a metal mold preheated to 600℃ to form the shape.

[0047] (3) Transfer the formed glass blank to a muffle furnace and anneal at 600°C for 2 hours to eliminate the internal thermal stress generated by casting; after annealing, turn off the muffle furnace and slowly cool it to room temperature to obtain annealed glass.

[0048] (4) The annealed glass is placed in a crystallization furnace and heated from room temperature to 1000℃ at a rate of 3℃ / min. The temperature is kept constant for 2 hours to induce the precipitation of pyroxene crystal phase. After crystallization, the glass is cooled to room temperature in the furnace to obtain REBFS infrared luminescent microcrystalline glass.

[0049] The performance of the prepared glass-ceramic samples was tested by fluorescence spectroscopy, fluorescence lifetime, XRD, SEM, and EDS. The results are shown in the figure. Figures 1-4 , Figure 7 :

[0050] Figure 1 The image shows the near-infrared emission spectrum of the glass-ceramic. It can be seen that under 585 nm visible light excitation, Nd2+ appears at 1065 nm. 3+ Characteristic near-infrared emission peak.

[0051] Figure 2 In the middle 'a', Nd is present in the glass-ceramic. 3+ Fluorescence lifetime, b is Nd 3+ The fluorescence lifetime bar chart shows that the fluorescence lifetime of the glass-ceramic sample is 225.99 μs.

[0052] Figure 3 The image shows the XRD pattern of the glass-ceramic. It can be seen that the XRD pattern of the glass-ceramic sample only shows the characteristic diffraction peaks of the pyroxene phase, with no other crystal diffraction signals.

[0053] Figure 4 The image shows the SEM image of the glass-ceramic of Example 1. Microscopic morphology analysis shows that the glass-ceramic is composed of a glass phase and short columnar pyroxene. The pyroxene phase has a high degree of crystallinity and no other crystalline phases are precipitated.

[0054] Figure 7 This is an EDS spot scan image of glass-ceramic. Figure 7 Image a shows the EDS spot scan of the glass phase of the glass-ceramic, and image b shows the EDS spot scan of the pyroxene phase of the glass-ceramic. It can be seen that the Nd signal in the glass phase is weak, while the Nd content in the pyroxene phase is relatively high, indicating that Nd... 3+ Preferential replacement of Ca in pyroxene 2+ It selectively accumulates within the crystalline phase.

[0055] Example 2: A method for preparing infrared luminescent glass-ceramics using REBFS

[0056] The process is basically the same as in Example 1, except for the raw material formula: the raw materials are weighed according to the formula in Table 1 for Example 2, and the preparation steps and parameters are the same as in Example 1, which will not be described in detail here.

[0057] The microcrystalline glass prepared in Example 2 was subjected to fluorescence spectroscopy, fluorescence lifetime, XRD, SEM, and EDS tests, and the test results are shown in the figure. Figures 1-3 , Figure 5 , Figure 7 :

[0058] Near-infrared emission spectroscopy display ( Figure 1 Under 585nm visible light excitation, Nd2+ appears at 1065nm in the sample. 3+ Characteristic near-infrared emission peak.

[0059] Fluorescence lifetime plot shows ( Figure 2 Example 2: The fluorescence lifetime of the microcrystalline glass is 264.27 μs.

[0060] XRD phase analysis showed that ( Figure 3 The XRD pattern of the sample only showed characteristic diffraction peaks of the pyroxene phase, with no diffraction signals from other crystals.

[0061] SEM microstructure analysis showed that ( Figure 5 ): Microcrystalline glass is composed of a glass phase and short columnar pyroxene. The pyroxene phase is highly crystalline and no other crystalline phases precipitate.

[0062] EDS element distribution display ( Figure 7 The Nd signal is weak in the glass phase, while the Nd content is relatively high in pyroxene, indicating that Nd... 3+ Preferential replacement of Ca in pyroxene 2+ It selectively accumulates within the crystalline phase.

[0063] Example 3: A method for preparing infrared luminescent glass-ceramics using REBFS

[0064] The process is basically the same as in Example 1, except for the raw material formulation: each raw material is weighed according to the formulation in Table 1 for Example 3, and the preparation steps and parameters are the same as in Example 1, which will not be described in detail here.

[0065] The microcrystalline glass prepared in Example 3 was subjected to fluorescence spectroscopy, fluorescence lifetime, XRD, SEM, and EDS tests. The test results are shown in [Figure number missing]. Figures 1-3 , Figure 6 , Figure 7 :

[0066] Near-infrared emission spectroscopy display ( Figure 1 Under 585nm visible light excitation, Nd2+ appears at 1065nm in the sample. 3+ Characteristic near-infrared emission peak.

[0067] Fluorescence lifetime display ( Figure 2 Example 3: The fluorescence lifetime of the microcrystalline glass is 318.41 μs, which is better than that of conventional silicate luminescent glass.

[0068] XRD phase analysis showed that ( Figure 3 The XRD pattern of the sample showed only characteristic diffraction peaks of the pyroxene phase, with no other diffraction signals.

[0069] SEM microstructure analysis showed that ( Figure 6 ): Microcrystalline glass is composed of a glass phase and short columnar pyroxene. The pyroxene phase is highly crystalline and no other crystalline phases precipitate.

[0070] EDS element distribution display ( Figure 7 The Nd signal is weak in the glass phase, while the Nd content is relatively high in pyroxene, indicating that Nd... 3+ Preferentially replacing Ca in pyroxene 2+ It selectively accumulates within the crystalline phase.

Claims

1. An infrared luminescent microcrystalline glass prepared using rare-earth-containing blast furnace slag from Bayan Obo, characterized in that, The basic composition of the infrared luminescent microcrystalline glass is 50-56 wt% SiO2, 5-11 wt% Al2O3, 8-14 wt% MgO, and 19-25 wt% CaO. It is prepared using rare-earth-containing blast furnace slag from Bayan Obo as the main raw material, with the addition of chemical reagents SiO2, Al2O3, MgO, and CaO. Based on the basic composition of the microcrystalline glass and the measured content of each component in the rare-earth-containing blast furnace slag from Bayan Obo, the added SiO2, Al2O3, MgO, and CaO are calculated and corrected before being proportioned. Through a heat treatment process, the Nd element co-occurring in the rare-earth-containing blast furnace slag from Bayan Obo is converted into Nd... 3+ The form is dissolved in the crystalline phase and glass phase structure of the microcrystalline glass to obtain the near-infrared luminescent microcrystalline glass.

2. A method for preparing infrared luminescent microcrystalline glass using rare earth-containing blast furnace slag from Bayan Obo, characterized in that, Includes the following steps: (1) Weigh each raw material according to the raw material formula of microcrystalline glass, wherein Bayan Obo contains 40-60 wt% rare earth blast furnace slag, 30-45 wt% silicon dioxide, 0.45-3.5 wt% aluminum oxide, 4-7 wt% magnesium oxide, and 1.2-10 wt% calcium oxide. Mix the raw materials to obtain a mixture. (2) The mixture is placed in a high-temperature resistant crucible and then placed in a muffle furnace. It is heated to 1400-1500℃ through a gradient heating process and melted at high temperature to obtain a homogeneous rare earth Nd-containing material. 3+ molten glass; (3) The glass melt from step (2) is poured into a mold preheated to 600°C and molded. After demolding, it is placed in a muffle furnace for annealing to obtain annealed glass. (4) The annealed glass is subjected to crystallization heat treatment to regulate the precipitation of crystalline phase and obtain infrared luminescent microcrystalline glass.

3. The method according to claim 2, characterized in that, Step (2) The heating regime of gradient heating is as follows: first, heat the mixture to 1000℃ at a heating rate of 3℃ / min and keep it at that temperature for 2 hours; then continue heating to 1400~1500℃ at a heating rate of 3℃ / min and keep it at that temperature for 3 hours.

4. The method according to claim 2, characterized in that, The annealing temperature in step (3) is 600℃ and the annealing time is 2 hours. After annealing, the furnace is cooled to room temperature.

5. The method according to claim 2, characterized in that, The specific method of crystallization heat treatment in step (4) is as follows: the annealed glass in step (3) is heated from room temperature to 1000°C at a heating rate of 3°C / min and kept at that temperature for 2 hours for crystallization; finally, it is cooled to room temperature in the furnace and removed from the furnace to obtain the infrared luminescent microcrystalline glass.

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