【作者】 吉娜；

【导师】 丁浩；

【作者基本信息】 中国地质大学（北京） ， 材料学， 2009， 硕士

【摘要】 锆硅渣是工业上利用锆英石生产锆系列化合物(如氧氯化锆等)后产生的固体废弃物,回收锆硅渣中的二氧化硅制备白炭黑产品以实现其资源化利用,对固体废弃物减量和降低环境污染具有积极意义。在现有评判体系基础上,研究和建立对实际应用具有指导作用的沉淀法白炭黑品级的评判方法十分必要。本论文以河南锆硅渣为原料,研究了分别采用化学沉淀法和直接中和法制备白炭黑的技术和工艺。对白炭黑产物进行了性能测试和表征,讨论了化学沉淀法制备白炭黑的机理,并研究了沉淀法白炭黑品级模糊综合评判问题。研究了化学沉淀法制备白炭黑的技术和工艺,表明通过锆硅渣除色、碱溶和碱溶滤液酸析步骤可制得白炭黑产物。试验得出最佳工艺条件:碱溶时间40min,液固比3:1,NaOH加入量0.67g/10g除色锆硅渣,酸析温度为80℃,陈化时间为60min,SiO2浓度为0.580mg/mL。研究了采用直接中和法,通过硅渣研磨制浆→含PEG分散剂洗水洗涤→水浴加热→诱导剂诱导→陈化→离心洗涤等工序制备白炭黑的工艺。试验确定的最佳工艺条件:分散剂用量2.5%,反应温度70℃,研磨时间45min。对制备的白炭黑产物进行了理化性能测试和性能表征。化学沉淀法和直接中和法制备的白炭黑产物均由非晶态物质组成,比表面积分别为302.8m~2/g和427.3m~2/g,原级颗粒呈球形,粒径约100nm,孔径均在中孔范围内。直接中和法产物分散性更好,孔道分布更发达。两种白炭黑产物的各项理化指标均符合国家标准。对化学沉淀法制备白炭黑的机理进行了讨论。化学沉淀法制备白炭黑属液相化学反应,应力求在亚稳过饱和状态下进行;白炭黑生长过程由颗粒生成和颗粒长大两部分组成,控制体系组分浓度直接影响白炭黑的颗粒分散性;白炭黑产品形态可通过对液相化学反应过程中各项参数的控制来进行有效调控。根据白炭黑产品的现有标准(HG/T 3061和ISO 5794-1),并结合相关生产企业产品标准和信息,通过综合分析沉淀法白炭黑各方面性能的作用影响方式,采用模糊数学综合评判方法,建立了沉淀法白炭黑品级模糊评判模型。实例验证表明,通过模型预测的产品品级和计算价格与实际状况基本相符。更多还原

【Abstract】 Zr-containing silica residue is solid waste discharged during the industrial process of Zr serial compounds (such as ZrOCl2) from zirconite. Preparing amorphous silica by recovering silica from Zr-containing silica residue is very meaningful for reducing the solid waste and environmental pollution. It is necessary to establish grade evaluation for precipitated silica based on existing evaluation system, which is of guiding significance in applications.In this paper, preparation processes of amorphous silica using Henan Zr-containing silica residue as raw materials with chemical precipitation and direct neutralization methods were researched. Properties and structures of amorphous silica products were characterized. The mechanism of preparation of amorphous silica by chemical precipitation was discussed. The grade fuzzy comprehensive evaluation on precipitated silica was studied.Amorphous silica was prepared by chemical precipitation through procedures including alkali dissolving, color removal and acid eduction of alkali leachate. Optimum process conditions were obtained: alkali dissolving time 40min, liquid-solid ratio 3:1, dosage of NaOH 0.67g per 10g silica residue after color removal, acid eduction temperature 80℃, aging time 60min, and concentration of SiO2 0.580mg/mL.The preparation process of amorphous silica by direct neutralization was studied, which were composed of pulping by grinding, washing with PEG (dispersant) solution, water-bathing, inducing by Na2SiO3, aging, centrifugal washing and so on. Optimum process conditions were obtained: dosage of dispersant 2.5%, reaction temperature 70℃, and grinding time 45min.The properties and structures of amorphous silica products by chemical precipitation and direct neutralization were measured and characterized. Their specific surface areas reached to 302.8m2/g and 427.3m2/g, respectively. They were both composed of amorphous phase, and the original particle was spherical and of average size of 100nm in diameter, the pore diameter is at the range of mesopores. Compared with amorphous silica products prepared by chemical precipitation, the dispersibility of amorphous silica by direct neutralization was better, and the pore distribution was broader. The physicochemical characteristics of amorphous silica can accord with the national standards.The mechanism of preparation of amorphous by chemical precipitation was discussed. The process of preparation of amorphous precipitated silica was liquid phase chemical reaction, which was in metastable supersaturation region as possible. The growing processes of amorphous silica were composed of crystal nucleation and growth. Controlling the concentration of the system affected the dispersibilities of silica, and the morphologies of amorphous silica can be adjusted by controlling indexes of liquid phase chemical reactions.Grade fuzzy comprehensive evaluation model was established, which was based on present standards (HG/T 3061 and ISO 5794-1), combining with standards and information from manufacturers of amorphous silica and analysis of the influences on interactions between properties and performances. The grade and calculated price of amorphous silica sample coincided with the real situations.更多还原