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由于含有大量的重金属,不锈钢渣与铜渣中被许多国家归属为危险废物[1-4]。这些危险废物在雨水的淋滤过程中容易进入地下水系统和土壤中,从而对生态环境造成威胁。一般可通过二次回收和固化2种方式解决不锈钢渣与铜渣中的重金属污染问题[5-7]。仪桂兰[8]以粉煤灰和不锈钢渣为原料成功地制备了微晶玻璃为不锈钢渣资源化利用提供了新途径。卜金彪等[9]综合利用不锈钢渣、尾矿及废玻璃制备了主晶相为镁黄长石相微晶玻璃。SOHN等[10]通过改变不锈钢熔渣中Al2O3/SiO2比例,提高富铬尖晶石在熔渣中浸出率,减少熔渣中游离的Cr离子含量,提高了Cr离子的稳定性。MA等[11]以铜渣为原料添加ZnO制备微晶玻璃,研究发现Zn能够有效包裹在晶体结构中,降低了酸碱环境中重金属被浸出的风险。LIU等[12]利用钢渣与粉煤灰制备全固废基微晶玻璃,使Zn、Fe、Mn进入微晶相中对重金属离子进行固化。此外,DENG等[13]、DENG等[14]和DENG等[15]利用铬铁渣制备微晶玻璃使不锈钢渣中的多种重金属结晶为尖晶石,实现多种重金属协同固化。因此,以粉煤灰、不锈钢渣和铜渣制备微晶玻璃可以高值化利用固体废弃物,减少毒性物质的浸出。
微晶玻璃具有较高的机械强度、耐腐蚀性和耐磨性,可替代铸石和耐酸陶瓷板在煤炭、采矿、水泥、机械等工业部门应用。大部分微晶玻璃是通过非均匀形核制备获得,晶核剂是促进玻璃析晶和优化性能的重要物质[16]。DENG等[13]提出了在CaO-MgO-SiO2-Al2O3体系微晶玻璃中Cr2O3容易优先结晶形成尖晶石纳米晶粒作为晶核剂诱导辉石结晶。ZHANG等[17]研究发现Cr2O3能够诱导玻璃分相,降低析晶温度。魏海燕等[18]尝试以微波热处理技术制备微晶玻璃,探究Cr2O3和Fe2O3为晶核剂对微晶玻璃析晶行为的影响。Fe2O3是一种促进微晶玻璃析晶的重要晶核剂,铁离子能够弱化玻璃网络结构,增加非桥氧数量,降低玻璃析晶活化能,促进玻璃析晶[19-20]。因此,金属离子作为形核剂诱导硅酸盐玻璃析晶是制备微晶玻璃的一种优势选择。
目前,主要采用电阻加热方式对微晶玻璃进行热处理,该方法制备微晶玻璃能耗高、热能利用率低,不利于可持续发展。基于废弃物成分以SiO2、CaO、MgO、Al2O3以及Fe2O3为主,适合制备 CaO-MgO-SiO2-Al2O3-Fe2O3(CMASF)体系微晶玻璃。本研究以粉煤灰、不锈钢渣和铜渣为原料采用微波热处理制备矿渣微晶玻璃,拟探究微波热处理过程重金属迁移与固化机制,并分析Fe2O3对辉石微晶玻璃形成过程中的玻璃网络结构变化与结晶规律。
微波处理多种固废制备微晶玻璃
Microwave treatment of various solid wastes to prepare glass-ceramics
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摘要: 以不锈钢渣、铜渣和粉煤灰为原料,通过熔铸法与微波晶化法相结合制备矿渣微晶玻璃,研究铜渣添加量 (Fe2O3) 对矿渣微晶玻璃结晶特性与重金属迁移规律。结果表明,铜渣中的Fe2O3对微晶玻璃结晶具有调控作用,5%的铜渣添加量会促进辉石结晶;当铜渣超过15%导致了磁铁矿的结晶,抑制辉石析晶。不锈钢渣与铜渣中的重金属Zn、Mn、Cr离子在玻璃结晶过程迁移进入尖晶石,尖晶石为辉石提供形核质点,诱导辉石外延尖晶石析晶。在矿渣微晶玻璃中辉石包裹尖晶石形成“核-壳”结构,对重金属离子有效固化。本研究结果可为高值化利用多种固废制备矿渣微晶玻璃及重金属固化研究提供参考。Abstract: Taking the fly ash and the slag of the stainless steel, the copper slag as raw materials, slag glass-ceramics was prepared through the combination of the method of casting and microwave heating, and the purpose of the paper was to study on the crystallization characteristics and the migration law for heavy metal existed in glass-ceramics made of slag by the addition of copper slag(Fe2O3). The results showed that Fe2O3 in copper slag had a regulatory effect on glass-ceramics crystallization while the addition of 5% copper slag would forward augite crystallization. However, over 15% that would lead to the crystallization of magnetite, and augite crystallization would be inhibited. The heavy metals Zn, Mn and Cr ions in the slag of the stainless steel and the copper slag would be transferred by migration into spinel during the glass crystallization process, while the spinel provides nucleation points for augite, which would induce the crystallization on epitaxial spinel for augite. Thru augite wrapping of the spinel to form a core-shell structure in slag glass-ceramics, it would lead to an effective curing of the heavy metal cation. The results of this study can provide a reference for highly preparing of the slag glass-ceramics and the curing for heavy metal from a variety of solid wastes.
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Key words:
- Slag glass-ceramics /
- Microwave treatment /
- Augite /
- Spinel /
- Heavy metal curing
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表 1 固体废弃物成分
Table 1. Composition of waste residues
% (质量分数) 成分 粉煤灰 铜渣 不锈钢渣 SiO2 53.34 22.59 37.76 Al2O3 18.18 3.91 13.16 CaO 11.53 2.41 3.68 MgO 3.33 0.68 23.10 Fe2O3 10.83 66.36 6.37 K2O 1.23 0.67 0.20 Na2O 0.56 0.69 0.35 ZnO — 1.00 0.05 Cr2O3 — — 2.90 其他 1.00 1.69 2.41 表 2 基础玻璃的主要化学成分
Table 2. The main chemical composition of glasses
样品编号 粉煤灰添加质量/g 铜渣添加质量/g 不锈钢渣添加质量/g SiO2添加质量/g CaO添加质量/g MgO添加质量/g B2O5添加质量/g C0 126.72 0 31.68 8.25 9.9 1.65 9.90 C5 120.37 10.00 30.10 7.84 9.41 1.57 9.41 C15 107.69 30.00 26.93 7.01 8.41 1.40 8.41 C25 94.98 50.00 23.76 6.19 7.43 1.23 7.43 表 3 玻璃的稳定性特征
Table 3. Stability characteristics of glass
温度/ ℃ C0 C5 C15 C25 Tg 680 661 668 698 Tp 863 837 858 896 △T 183 176 190 198 表 4 Qn的含量与DOP计算结果
Table 4. Qncontent and DOP calculation results
样品编号 Q0/% Q1/% Q2/% Q3/% Q4/% DOP R2 C0 11.25 13.67 17.16 44.43 13.49 1.65 0.996 C5 14.93 13.91 22.91 42.63 5.62 1.89 0.994 C15 6.92 9.62 17.12 44.92 19.37 1.40 0.994 C25 7.70 8.66 19.16 48.06 18.46 1.39 0.996 -
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