含Cr危固的Cr、Ni固化与解毒机理及微晶玻璃应用研究

The output of containing Cr crisis solids, such as stainless steel slag and acid leaching sludge, were about 5.8 million tons in China in 2012. Because the concentrations of Cr and Ni ion in the containing Cr crisis solids are GB5085.3-2007 specified value 3-10 times, it brings serious heavy metal pollution. The melting method invented by the applicant will be applied for preparing non-toxic , high added value diopside-type glass ceramics using containing Cr crisis solids. CaO and MgO will be used as outside the body a glass network. SiO2 and Al2O3 will be used as the glass network. Fe2O3, Cr2O3 and NiO will be used as a nucleating agent.The laws of Cr valence Variation will be intensively investigated. The reduction reaction conditions between reducing substances, such as FeO, elemental Cr and Ni, and Cr6+ will be studied. Coupling mechanism of multi reduction reaction and detoxification mechanism of Cr6+ reduction will be set forth. We will clarify the boundary conditions of each component of CaO -MgO -Al2O3 -SiO2 quaternary phase diagram and diopside-type glass ceramics composition adjustment mechanism. We will reveal variation the laws of phase composition, grain growth and microstructure in nucleation and crystallization process of the glass-ceramic, then establish the kinetic and thermodynamic models of nucleation and crystal growth. We will also calculate the binding energies of Cr and Ni atoms in different crystal sites, then show the scientific explanations of the heavy metal stable curing. The results of this study not only can put an end to the pollution of containing Cr crisis solids, but also non-toxic high value of reuse will generate significant social and economic benefits.

2012年我国不锈钢渣和酸洗污泥等超过580万吨，其中的Cr6+、Ni2+等离子浓度是GB5085.3-2007的3-10倍，重金属污染严重。采用申请人的微晶玻璃专利技术，利用含Cr危固的SiO2和Al2O3作玻璃网络、CaO和MgO作网络外体、Fe2O3、Cr2O3和NiO作形核剂，制备出无毒、高值的透辉石型微晶玻璃。研究Cr价态变化规律，Cr6+与还原物质(FeO、单质Cr和Ni)还原反应的条件，探究Cr6+解毒和多种反应的耦合机理；阐明CaO-MgO-Al2O3-SiO2相图各组分边界条件和微晶玻璃成分调整机制；揭示微晶玻璃形核-晶化过程的相组成、晶粒和显微组织变化规律，建立形核-晶体生长的动力学和热力学模型；计算Cr和Ni的晶位结合能，解释重金属稳定固化机理。本研究思路未见报道。研究成果不仅可杜绝含Cr危固的重金属污染，而且将其制备成无毒、高值微晶玻璃，社会和经济效益显著。

2017年，我国不锈钢渣、酸洗污泥等含Cr危固产量超600万吨，现有再利用于水泥等处置方式存在重金属浸出风险高、产品附加值低等问题。本项目利用含Cr危固中的SiO2和Al2O3作玻璃网络、CaO和MgO作网络外体、Fe2O3、Cr2O3和NiO作形核剂，制备出无毒、高值的透辉石型微晶玻璃，揭示了Cr6+高温还原解毒机理，阐明了微晶玻璃形成机理，形成了微晶玻璃固化重金属理论。. （1）Cr6+解毒机理：研究了含Cr危固中Cr6+还原过程，危固中Fe、FeO、Ni等还原性物质在高温（800℃以上）时，可将Cr6+还原为无毒Cr3+；Cr6+解毒机理为氧化还原反应。. （2）沉淀固化：研究了Cr、Ni及其离子的电极电位和pH值相图，确定了不同形态Cr、Ni及其化合物稳定存在的相区。Cr3+、Cr6+和Ni2+可稳定存在低pH值区域；随着pH值升高，Cr3+、Cr6+和Ni2+可以氢氧化物形式。pH值为9.5时，可将Cr3+、Ni2+沉淀固化。. （3）微晶玻璃固化机理：研究了Cr、Pb和Cd在微晶玻璃中的存在形式，发现Cr形成了富铬相，Pb、Cd则替代了价态相同、半径接近的Ca。. （4）含Cr危固成分调整机制：根据CaO-MgO-Al2O3-SiO2四元相图，研究了碱度对透辉石微晶玻璃的影响，确定了二元碱度为1的成分调配原则。. （5）微晶玻璃形成机制：①非晶形核机制，以非晶玻璃相中Cr3+和Ni2+为形核剂，形成辉石相晶核、长大；②固态相变机制，非晶态SiO2体系，因Fe含量高驱动优先形核的石英相晶核转变为透辉石晶核。. （6）重金属赋存状态及稳定性：确定了Cr、Ni赋存于透辉石主晶相，Pd、Cd替代Ca的晶位。Cr、Ni的浸出浓度分别为0.13mg/L和0.04mg/L，远低于美国TCLP浸出标准的上限值5.00mg/L。