矸石电厂粉煤灰制备微晶玻璃预提取铁、铝的研究

通过试验,就矸石电厂粉煤灰提取铁、铝并将二者有效分离的方法进行了探讨;结合后续制备微晶玻璃的工艺,提出了相关的技术要求,以保证整个研究的经济性和完整性。研究结果表明:二次沉淀法有效地实现了铁、铝分离,为微晶玻璃的制备创造了条件,且工艺简单,控制点少,可操作性强。

不同前处理方法对粉煤灰有效成分提取率的影响

为了充分提取粉煤灰的有效成分,研究了不同的粉煤灰前处理工艺(酸提取法、碱提取法、高温熔融/酸溶复合提取法)对其有效成分硅、铝、铁提取率的影响,并确定了最佳前处理方法。结果表明:浸出温度80~100℃、浸出时间1.5~2.0 h、15%盐酸用量为40~50 m L时,硅、铝、铁的提取率最高可以分别达到44%、61%和67%;压力0.4 MPa,温度150℃,反应时间2~3 h、碱液用量为150~200m L时,硅、铝、铁的提取率最高可以分别达到69.5%、65.7%和72.3%;温度900~920℃、灰助剂比范围10/6~10/10,经过40~60 min的熔融,随后进行酸浸,硅、铝、铁的提取率最高可以分别达到84.9%、87.9%和95.3%。试验结果表明,对粉煤灰有效成分提取率最高的方法为高温熔融/酸溶复合提取法。

Mechanism and kinetics of iron extraction from high silica boehmite−kaolinite bauxite by hydrochloric acid leaching

The chemical and mineral compositions of bauxite recovered from the Severoonezhsk Bauxite Mine(Arkhangelsk region,Russia)were studied by XRD,ICP-OES,TG/DSC,SEM,TEM,and Mössbauer spectroscopy.The iron-containing minerals of the bauxites were found to comprise alumogoethite(α-Fe_(1−x)Al_(x)OOH),alumohematite(α-(Fe_(1−x)Al_(x))_(2)O_(3)),alumoakaganeite(β-Fe_(1−x)Al_(x)O(OH,Cl)),and chromite(FeCr_(2)O_(4)).The efficiency of Fe extraction from the bauxite by HCl leaching was 82.5%at 100℃,HCl concentration of 10%,solid/liquid ratio of 1:10,and the process duration of 60 min,with aluminum loss from the bauxites below 4.5%of the total Al contents in the bauxite.Analysis of the kinetics of the iron leaching process proved diffusion to be the limiting stage of the process at 90−100℃.Bauxite residue after leaching presented traces of α-Fe_(1−x)Al_(x)OOH and β-Fe_(1−x)Al_(x)O(OH,Cl),and most of the iron content was in the FeCr_(2)O_(4).In bauxite residue after HCl leaching,in addition to iron oxide,the contents of chromium and calcium oxides significantly decreased.The iron chloride liquor after leaching contained the rare earth elements(REE)of 6.8 mg/L Sc,4.1 mg/L Ce and 2.3 mg/L Ga.