用碱从富铁粉煤灰中溶解硅的试验研究

Dissolution of Silicon From Iron-rich Fly Ash Using Sodium Hydroxide

研究了用碱从富铁粉煤灰中溶解硅。富铁粉煤灰先经过磁选分离,再酸化处理,然后用NaOH溶解其中的硅,考察粉煤灰与氢氧化钠质量比(灰碱质量比)、反应时间、反应温度等条件对硅溶解的影响,以及磁性粉煤灰对碱溶硅的影响。结果表明:磁选分离后,磁性粉煤灰铁含量显著提高,占铁总量的90%;非磁性粉煤灰中铁含量大幅下降;磁性粉煤灰用硫酸酸化处理,硫酸用量为30 mL/50 g粉煤灰时质量不发生变化;酸化处理后,磁性粉煤灰用碱溶解150 min、非磁性粉煤灰用碱溶解90 min,反应温度90℃,灰碱质量比3/1,硅溶解率均较高。磁性铁化合物的XRD特征峰不明显,为包括赤铁矿在内的较为复杂的混合物。

Dissolution of silicon using sodium hydroxide from iron-rich fly ash was researched.After magnetic separating and acid treating,fly ash is desilicated using sodium hydroxide.The effects of time,temperature,ash-alkali mass ratio and magnetic fly ash on dissolution of silicon were examined.The results show that iron content in magnetic fly ash increases significantly with over 90%after magnetic separation,while iron content in non-magnetic fly ash reduces obviously.The sulfuric acid dosage for 50 g fly ash is 30 mL,the fly ash quality does not change any more.The results indicate that optimizing factors of dissolution of silicon oxide are reacting time of 150 min for magnetic fly ash,90 min for non-magnetic fly ash,reacting temperature of 90℃,ash-alkali ratio of 3/1.Dissolution efficiency of silicon oxide in magnetic fly ash is good.XRD analysis shows that the characteristic peaks of magnetic iron compounds are not obvious,and it is complex mixture containing hematite.