富铁粉煤灰除铁的工艺研究

Study on Leaching Process of Iron from Iron-Rich Fly Ash

研究了富铁粉煤灰酸溶除铁工艺,探索KHSO4在焙烧温度、焙烧时间、溶出温度和溶出时间等关键条件下铁氧化物的溶出率,根据铁氧化物在粉煤灰中的存在形式和特性,提出优化工艺。试验结果表明,西南粉煤灰中富含铁氧化物且具有磁性,通过XRD检测可知,铁氧化物没有明显的特征峰。用酸式盐KHSO4替代硫酸酸溶粉煤灰中的铁氧化物,其关键条件的优化结果是焙烧温度为220℃,焙烧时间为180 min,溶出温度为90℃,溶出时间为80 min,除铁率最高为86.7%。与硫酸酸溶相比,KHSO4酸溶相当于40%的硫酸,对设备腐蚀小,经济环保,生产效益好。通过对焙烧熟料的XRD分析可知,KHSO4反应不完全,特征峰明显,Fe2(SO4)3和Al2(SO4)3有特征峰,强度不大,晶型不是很好,二氧化硅和莫来石晶型未发生变化,不参与反应。

Leaching process of iron from iron-rich fly ash was studied by potassium bisulphate on the main condition of roasting temperature,roasting time,leaching temperature,leaching time.An optimized process was proposed according to leaching rate of iron oxides and properties of iron-rich fly ash.The results show that iron-rich fly ash in the southwest of China has magnetism,without obvious characteristic peaks of iron oxides through XRD,which indicates that iron oxides are amorphous,or dispersed in other substance with micro-particles.Iron oxides from fly ash can be leached by potassium bisulphate replacing sulphuric acid with the main effect factors of roasting temperature 220℃,roasting time 180 min,leaching temperature 90℃,leaching time 80 min;rate of iron removal to 86.7%.Compared with concentration of sulphuric acid,that of potassium bisulfate is equal to 40%on leaching rate of iron oxides,which latter shows the virtues of less corrosion to the equipment,lower costs,smaller pollution and higher efficiency and profits in industrial production.XRD analysis of roasted clinker displays that the X-ray diffraction pattern of ferric sulphate and aluminium sulphate is not strong with imperfect crystal form,while that of potassium bisulphate is strong and perfect indicating incomplete reaction.Crystal sillicon dioxide and mullite involved in reaction are not observed.