钢渣多孔吸声材料的制备及吸声性能研究

发布时间：2018-06-16 21:08

本文选题：钢渣 + 多孔吸声材料　；参考：《北京科技大学》2016年博士论文

【摘要】：钢渣是钢铁生产过程排放最多的固体废弃物,具有成分复杂、耐磨和安定性差等特性,致使我国钢渣资源化利用率低,环境污染严重。钢渣含有部分硅酸盐成分,具有一定的胶凝活性,可用作水泥、陶瓷、玻璃等建材生产的原料。目前噪声污染日益严重、噪声污染治理越发紧迫,而采用多孔陶瓷、泡沫玻璃等新型无机非金属材料吸声降噪越来越受到重视。因此,探索利用钢渣制备多孔吸声材料,开发钢渣资源化利用的新途径和新领域,提高钢渣利用率,对企业节约资源、保护环境、提高经济效益具有重要意义。论文选择高温烧结的方法制备钢渣吸声材料,针对关键材料参数和性能指标,逐步改进原料配方及相应的成型造孔工艺。通过对比钢渣-粉煤灰、钢渣-粘土-长石-石英体系和钢渣-粉煤灰-粘土-稻壳灰三个体系原料配方及其相应成型造孔方法的特点,确定了制备工艺方案,并探讨了制备机理,建立了烧结过程模型。论文主要得到如下结论：(1)本研究采用的转炉钢渣主要化学组成为CaO、Fe2O3、SiO2,Al2O3、 MgO等；主要矿物相为C2S、C3S、RO目、C2F和C3A等。冷态制备的钢渣胶凝材料早期强度低,28天强度为18.36MPa,而高温烧结试样抗压强度可达90.86MPa。相对于冷态制备方法,选择高温烧结的方法制备钢渣多孔吸声材料将能够具有更好的力学性能。(2)通过掺加不同硅质材料改进原料配方,不但可以获得较好的力学性能也可逐步拓宽烧成温度范围；而通过调整造孔剂种类、添加方式及成型造孔方法,可提高钢渣吸声材料的孔隙率,并保持较好的力学性能。采用三种基体材料配方及相应成型造孔方法制备的钢渣吸声材料孔隙率在50%以上,抗压性能可达3.0MPa以上,厚度在2.5-3.0mm的材料平均吸声系数可达到0.40-0.48。钢渣-粉煤灰-粘土-稻壳灰体系及颗粒堆压与造孔剂复合造孔方法废物利用率高、工艺简单、烧成温度范围较宽,以及材料力学和吸声性能较好,因此,选择该原料配方和成型方法作为钢渣多孔吸声材料的制备工艺。制备工艺条件包括：钢渣：粉煤灰：粘土：稻壳灰的配比为12：3：2：3,高温造孔剂为白云石掺加量基体材料质量的10%；圆盘造粒的颗粒粒径控制在1.2-2.8mm；颗粒堆压在1.0-1.5MPa之间；烧成温度区间在1130-1180℃,较适宜的烧结温度和时间为1150℃和4h。(3)通过钢渣多孔吸声材料烧结成孔机理研究发现,稻壳灰、白云石可作造孔剂也是良好的掺加剂,适当烧结温度下坯体孔隙率均在50%以上,而且抗折强度最大可达44.7MPa。在控制烧成温度方面,稻壳灰、白云石和长石等原料的掺加可以改变烧结反应的温度,稻壳灰和长石分别可以降低反应温度20-30℃和10℃左右,但同时也缩短了烧成温度区间；白云石可以拓宽烧成温度范围,却提高了烧结反应的温度。因此,应控制稻壳灰和白云石的掺加量,该配方不宜掺加长石。烧结温度是钢渣吸声材料制备的主要影响因素。材料造孔过程主要在低温阶段,烧结升温速率不宜过快；烧结反应主要发生在高温阶段。延长烧结时间可促进烧结反应,使晶体充分发育生长,材料获得良好的力学性能,但同时降低孔隙率而影响吸声性能,烧结时间宜控制在2.5-4.0h。提高成型压力增加坯体密实度,可促进烧结反应,也使孔隙率明显降低；成型压力较低的试样具有较高孔隙率,但致密化程度低,因而成型压力可在1.0-1.5MPa之间。(4)多孔材料烧结过程可分为初期、中期和后期三个阶段,造孔剂分解造孔和烧结反应两个过程。烧结初期大约在室温到1100℃,烧结反应缓慢,收缩率在1%左右,少量中间过渡矿相钙铁榴石产生,主要是多孔材料的造孔过程。烧结中期在1100-1150℃之间,烧结收缩加速,收缩率达5%左右,主要表现为烧结颈部扩大,气孔形状改变,孔隙率下降；矿物相逐步从过渡矿物相生成稳定的透辉石相和少量RO相。烧结后期在1150-1200℃之间,收缩率达到10%以上,是孔隙形态、大小和数量快速变化的过程,也是晶体形成、生长,生成稳定矿物相的过程；由于大量高温液相产生,传质方式发生改变。烧结中期和后期组成材料烧结的另一个过程,即烧结反应的主要过程。烧结动力学结果表明,随烧结温度提高,坯体的烧结速率常数快速增加；烧结时间关系指数n值逐步由0.221升至0.342,说明坯体内的传质从表面扩散逐步变化为品界扩散的过程,在1190℃时n值下降为0.195,坯体中已有液相产生,传质方式已经改变；在1150-1190℃的活化能为32.88 kJ/mol。(5)钢渣多孔材料孔隙率、平均孔径、厚度和体积密度对吸声性能具有明显的影响。提高材料的孔隙率、增加材料厚度、孔径增大、减小体积密度均可提高材料平均吸声系数,尤其是增加材料厚度对于提高低频吸声系数作用效果显著,当增加到5.1cm时,平均吸声系数达到0.55。与其他常用多孔吸声材料性能比较发现,厚度基本相同条件下,钢渣多孔吸声材料的吸声性能优于多数常用的吸声材料；换算成混响室法吸声系数为0.74,吸声性能为Ⅱ级,属于具有优良的吸声性能吸声产品。
[Abstract]:Steel slag is the most discharged solid waste in the process of iron and steel production. It has the characteristics of complex composition, poor wear resistance and poor stability, which causes low utilization rate of steel slag and serious environmental pollution in China. Steel slag contains some silicate components and has certain gelation activity, which can be used as raw materials for building materials such as water mud, ceramics and glass. The treatment of noise pollution is becoming more and more urgent, and the sound absorption and noise reduction of new inorganic nonmetallic materials, such as porous ceramics and foam glass, are being paid more and more attention. Therefore, the exploration and use of steel slag to prepare porous sound absorption materials, develop new ways and new domain for utilization of steel slag, improve the utilization rate of steel slag, save resources and protect enterprises. Environment, improving economic benefit is of great significance. This paper chooses high temperature sintering method to prepare steel slag sound absorption material. According to key material parameters and performance indexes, the raw material formula and corresponding molding process are gradually improved. By comparing steel slag fly ash, steel slag clay feldspar quartz system and steel slag - fly ash - clay - rice husk ash three On the basis of the characteristics of the system material formula and its corresponding molding method, the preparation process is determined, the mechanism of preparation and the sintering process model are discussed. The main conclusions are as follows: (1) the main chemical composition of converter steel slag used in this study is CaO, Fe2O3, SiO2, Al2O3, MgO and so on. The main mineral phases are C2S, C3S, RO, C2F and C. 3A et al. The early strength of steel slag cementitious material prepared by cold state is low, the strength of 28 days is 18.36MPa, and the compressive strength of the high temperature sintered sample can reach 90.86MPa. relative to the cold state preparation method. The choice of high temperature sintering method to prepare the porous sound absorbing material of steel slag will have better mechanical properties. (2) improving the raw material formula by adding different siliceous materials. It can not only obtain better mechanical properties but also gradually broaden the range of sintering temperature, and by adjusting the types of pore making agents, adding methods and forming hole making methods, the porosity of the steel slag absorbing materials can be improved and the mechanical properties are maintained. Three kinds of matrix material formula and the corresponding molding hole making method are used to make steel slag absorbing materials. The porosity is above 50% and the compression performance is above 3.0MPa. The average sound absorption coefficient of material with thickness of 2.5-3.0mm can reach 0.40-0.48. steel slag - fly ash - clay - rice husk ash system and the compound hole making method of pore pressure and pore making agent, which has high utilization rate, simple process, wide firing temperature range, and good mechanical and sound absorption properties of materials. Therefore, the preparation process of the raw material formula and molding method is selected as the preparation process of the porous sound absorption material of steel slag. The preparation conditions include: steel slag: Fly Ash: Clay: the ratio of clay: the ratio of the rice husk ash is 12:3:2:3, the high temperature pore making agent is 10% of the mass of the dolomite, and the particle size of the disc granulation is controlled in 1.2-2.8mm; The pile pressure is between 1.0-1.5MPa, and the sintering temperature range is 1130-1180, and the suitable sintering temperature and time is 1150 and 4h. (3) through the porous sound absorption material of steel slag. It is found that the rice husk ash, dolomite can be a good additive, and the porosity of the body is above 50% under proper sintering temperature, and the bending resistance is more than 50%. With the maximum strength of 44.7MPa., the addition of rice husk ash, dolomite and feldspar can change the temperature of the sintering reaction. The rice husk ash and feldspar can reduce the reaction temperature of 20-30 and 10, but also shorten the firing temperature range, but the dolomite can broaden the firing temperature range, but increase the temperature range. The sintering temperature is not suitable for adding feldspar. The sintering temperature is the main factor affecting the preparation of the sound-absorbing material of steel slag. The process of making holes in the material is mainly at the low temperature stage, and the heating rate should not be too fast; the sintering reaction is mainly in the high temperature stage. The prolonging of the sintering time can be promoted. The sintering reaction makes the crystal fully develop and grow, and the material obtains good mechanical properties, but it reduces the porosity at the same time and affects the sound absorption performance. The sintering time should be controlled in 2.5-4.0h. to increase the forming pressure to increase the density of the body, to promote the sintering reaction, and to reduce the porosity obviously, and the specimen with lower molding pressure has a higher porosity. But the densification degree is low, thus the forming pressure can be between 1.0-1.5MPa. (4) the sintering process of porous materials can be divided into three stages, in the early stage, in the middle and later stages. The pore forming agent is divided into two processes. The initial sintering process is about at room temperature to 1100 C, the sintering reaction is slow, the shrinkage rate is about 1%, and a small amount of intermediate transition ore phase calcite In the middle period of sintering, the sintering shrinkage accelerated and the shrinkage rate was about 5%. The main performance was the enlargement of the sintered neck, the shape of the pores, the decrease of porosity, and the gradual formation of a stable diopter phase and a small amount of RO phase from the mineral phase. The later period of sintering was between 1150-1200 and 1150-1200. The shrinkage rate is over 10%, which is the process of rapid change in pore shape, size and quantity. It is also the process of crystal formation, growth, and formation of stable mineral phase; the mass transfer mode changes due to the production of a large number of high temperature liquid phases. The other process of sintering at the middle and later stages of sintering, the main process of sintering reaction, is the sintering kinetics. The results show that the sintering rate constant increases rapidly with the increase of sintering temperature, and the n value of the sintering time relationship exponentially increases from 0.221 to 0.342, indicating that the mass transfer in the body is gradually changed from the surface diffusion to the process of the boundary diffusion, and the n value decreases to 0.195 at 1190. The mass transfer mode has been changed, and the mass transfer mode has been changed at 11. The activation energy of 50-1190 C is 32.88 kJ/mol. (5) porous material, the average pore size, thickness and volume density have obvious influence on the sound absorption properties. Increasing the porosity, increasing the material thickness, increasing the pore size and reducing the volume density can increase the average sound absorption coefficient of the material, especially increasing the thickness of the material to improve the low frequency. The effect of sound absorption coefficient is remarkable. When increasing to 5.1cm, the average sound absorption coefficient reaches 0.55. and compared with other commonly used porous sound absorbing materials. Under the same thickness, the sound absorption properties of the porous material for steel slag are better than that of most commonly used sound absorption materials, and the sound absorption coefficient of the reverberation chamber method is 0.74 and the sound absorption performance is class II. It is a sound absorption product with excellent sound absorption properties.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X757;TB535

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