铝酸钠溶液耦合分解制备一水软铝石
文献类型：学位论文
| 作者 | 杨柳 |
| 学位类别 | 硕士 |
| 答辩日期 | 2009-05-25 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 郭占成 |
| 关键词 | 铝酸钠溶液 三水铝石 一水软铝石 诱导调控结晶 |
| 其他题名 | Preparation of Boehmite from Supersaturated Sodium Aluminate Solutions by Coupling Precipitation |
| 学位专业 | 化学工艺 |
| 中文摘要 | 铝酸钠溶液的分解是氧化铝生产工艺中最重要的工序之一，该工序决定着产物的晶型、形貌及粒径等特征。由于我国铝土矿98%为高硅、低铝/硅比的一水硬铝石矿，只能采用工艺复杂、耗能高的烧结法和联合法生产氧化铝，生产能耗是国外拜尔法的3倍左右，且三水铝石依然作为主要分解产物提供给后续的焙烧环节。以生产1 mol氧化铝计，焙烧三水铝石所需热量为170 kJ，而焙烧一水软铝石只需72 kJ，因此转变现有分解产物三水铝石为一水软铝石就可以降低焙烧能耗60%。 本文提出了铝酸钠溶液耦合分解制备一水软铝石的新工艺，通过工艺调控、晶种诱导、添加剂诱导等方式来促进共分解过程一水软铝石的析出、提高铝氧水合物的分解率。主要研究内容和结果如下： (1) 系统的研究了晶种系数、晶种粒径、分解温度和晶种活化等因素对铝酸钠溶液分解过程的影响。结果表明，一水软铝石晶种可以有效的促进一水铝石的结晶。当T=90 ℃、 =104 g/L、MR＝1.48、二氧化碳浓度为38%，采用100目机械活化晶种、SR=0.4的情况下，分解率可达85%，产物中一水软铝石质量分数为77%。晶种的粒径越小，铝酸钠溶液分解率越高，但产物中一水软铝石的质量分数越低；机械活化的方法可以一定程度的提高分解率，但碳酸化分解过程中晶种并不是分解率的决定因素。 (2) 对铝酸钠溶液耦合分解制备铝氧水合物的过程进行了宏观动力学分析。铝酸钠溶液耦合分解制备一水软铝石的过程与传统的晶种分解机理相似，符合二级分解动力学方程，其表观活化能为98 kJ/mol。晶种系数的反应级数为-0.5，与实验结果相一致。 (3) 考察了乙醇等有机添加剂对铝酸钠溶液分解制备一水软铝石的影响。有机添加剂的加入可以降低溶液游离碱的含量，促进铝酸钠溶液的分解，提高分解率，分解速率最大可达传统晶种分解的200倍；乙醇改变了铝氧水合物的径向和轴向生长速率，产物由不规则的片状晶体转变为由长柱状晶体组成的附聚体。 |
| 英文摘要 | The precipitation of sodium aluminates solution which determined the diameter, crystal form and morphology of product was one of the most improtant sections in the process of alumina production. Because 98% of alumyte in our country was diaspore, the method adopted to produce alumina can only be sintering process and combinational process. Thus, the energy consuming in produce alumina was three times as abroad. Moreover, gibbsite has also been used as the only kind of material supplied to subsequent section in more than one hundred years. If gibsite was replaced with boehmite, the bake energy could decrease 60% for the roast energy of gibbist was 170 kJ compared 70 kJ of boehmite. A new coupling precipitation technology was proposed to prepare boehmite from sodium aluminates solution. In the new technology, techniques of process parameters controlling, seed inducement and additive inducement were adopted to promote the crystallizing of boehmite and increase precipitation rate of sodiumte solutions at the same time. The main research results were shown as below: (1) The effect of seed ratio, seed diameter, precipitation temperature and active method on the precipitation process of sodium aluminate solutions was investigated respectively. The results showed that boehmite seed can induce the crystallizing of boehmite. The precipitaion ratio was 85% and mass ratio of boehmite was 77% under the conditions of T=90 ℃, =104 g/L, MR＝1.48, SR=0.4, =38%. Moreover, with the decrease of diameter of seed, the ratio of boehmite in the production was decreased, whereas precipitation rate of sodium aluminate solutions increased. Finally, mechanical activation can improved the precipitation rate, but seed active is not the decesive factor for precipitation rate. (2) The kinetics of coupling precipitation of sodium aluminate solutions was investigated. The mechanism of preparation boehmite from sodium aluminate solutions by coupling precipitation was similar with traditional seed precipitation. The kinetic reaction equation follows second grade and activation energy was 98 kJ/mol. Moreover, the order of initial seed ratio was -0.5, consistent with experimental results. (3) Influence of organic additives such as ethanol on the precipitation of sodium aluminats solution was investigated. Ethanol could decrease free cautic and increase the supersaturation, as a result, precipitation of sodium aluminates solution was improved which was 200 times of traditional seed precipitation. Furthermore, the addition of ethanol changed growth speeds of product in longitudinal and radial direction, as a result, the product changed from plate like crystal to long column agglomeration. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 96 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1284]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 杨柳. 铝酸钠溶液耦合分解制备一水软铝石[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009. |
入库方式： OAI收割
来源：过程工程研究所
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