PDF《Processes from Fly Ash》

Research on Alumina Leaching Through Different Processes from Fly Ash Xiaorong Liu, Zhu Zhang, Yaqin Sun, Yanan Lv, Mingling Jin School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai, P.

R.China,200233 1. [email protected],

2 [email protected] 3. [email protected] 4. [email protected] [email protected] Abstract: Fly ash was roasted with Na2CO3 to strengthen aluminum leaching. Different successive proc- esses such as acid leaching and microwave acid leaching were investigated comparatively. The results showed that the highest leaching rates of aluminum with acid leaching and microwave acid leaching were 42.38% and 59.17%, respectively. It could be deduced from the XRD, SEM and EDS characterization results of roasted fly ash that roasting fly ash with Na2CO3 destroyed SiO2-Al2O3 bond of mullite and generated such high ac- tive material as NaAlSiO4. In addition, microwave heating raised the internal energy of reactant elements and decreased activation energy of reaction, which shortened the reaction time and increased leaching rate of alu- minum from fly ash. Keywords: fly ash;

aluminum;

roasting;

microwave;

strengthen leaching 不同工艺下粉煤灰中铝的浸出效率研究 刘晓荣, 张琢, 孙亚琴, 吕亚男, 金鸣林 上海应用技术学院材料科学与工程学院, 上海, 中国,

200233 [email protected], [email protected], [email protected], [email protected], [email protected] 摘要: 本文通过添加 Na2CO3 焙烧提高粉煤灰的浸出活性,对比研究了酸浸、微波浸出等不同工艺对 粉煤灰中铝浸出效率的影响.研究表明,焙烧-酸浸时,铝的最大浸出率为 42.38%;

采用焙烧-微波场 酸浸联合工艺,铝的浸出率可达 59.17%.对焙烧后粉煤灰进行 XRD、SEM 及EDS 分析结果表明,粉 煤灰和钠盐混合焙烧破坏了粉煤灰中莫来石的 SiO2-Al2O3 键,生成 NaAlSiO4 等活性高的物质;

微波加 热能提高反应物分子的内能,加快粉煤灰中铝的浸出速度,提高浸出效率. 关键词: 粉煤灰;

铝;

焙烧;

微波场;

强化浸出;

1 引言 粉煤灰是燃煤电厂排放的工业固体废弃物, 目前 我国电力工业发展格局仍以火电为主,随着经济的发 展,能源消耗日增,粉煤灰的排放量急剧增加,如不 能充分利用,不仅严重污染环境,还将占有土地,因 此粉煤灰的开发利用迫在眉睫. 粉煤灰是燃煤颗粒中所含粘土、岩盐、长石等硅 酸盐矿物和石英矿物在高温下经历一系列物理化学变 化而形成的,其化学成分主要是 SiO

2、Al2O3 和铝硅 酸盐,其中氧化铝和二氧化硅的质量分数占化学成分 的60%以上,还有少量的 Fe2O

3、CaO、MgO、未燃 尽碳和钛、镓、锗、钒、钼、锌等微量元素[1] ,因而 它是一类来源广泛的再生资源.从粉煤灰中提取铝制 备Al2O3 或聚铝类无机高分子絮凝剂是一种极具研究 价值的高效利用途径 [2-4] .但是这些研究大都面临一 个难题,即由于 Al2O3 主要存在于非晶质的莫来石 (3Al2O3・2SiO2)之中,SiO2-Al2O3 键能高, 键聚合度大, 在常温下化学性质稳定,活性较低,导致铝的浸出率 ? 资助信息:国家自然科学基金项目资助(51074107),上海市重点 学科建设基金项目资助(J51504) 比较低, 因此提高 Al 的浸出率成为从粉煤灰中回收铝 的难点和关键. 为了强化粉煤灰中铝的浸出,通常采用焙烧活化 和添加助溶剂的方法,即通过高温固体状态下的反应 使铝硅酸盐基质发生变化而使铝生成可溶性很好的铝 酸钙等产物, 使浸出变得容易[5,6] ;