粉煤灰提铝渣对预脱硅液模数的调控

Modulus Control of Pre-Desilication Solution by Alumina-Extracted Residues of Coal Fly Ash

以"粉煤灰预脱硅-碳酸钠活化-盐酸酸浸"工艺产生的粉煤灰提铝废渣为硅源,提高预脱硅过程产生的硅酸钠溶液的模数,利用X射线衍射仪和电感耦合等离子体发射光谱等手段对比研究了石英砂、市售超细二氧化硅以及粉煤灰提铝渣等不同硅源对硅酸钠溶液模数提高的影响,探讨了粉煤灰提铝渣作为硅源用于硅酸钠溶液提模的机理及杂质的影响,并将提模后的硅酸钠溶液用于制备高值化二氧化硅产品.结果表明,提铝渣因含有非晶态二氧化硅可用于低模数硅酸钠溶液提高模数的硅源,提铝渣与脱硅液在100℃下反应30min可得到模数大于3的硅酸钠溶液,用此硅酸钠溶液生产的高附加值二氧化硅产品能够达到HG/T 3061-2009标准.

The extraction of alumina from coal fly ash via a ＂pre-desilication--Na2 CO3 activation--hydro- chloric acid leaching＂ is hope to be one of the important value-added utilization ways of coal fly ash. The low modulus sodium silicate solution produced from the pre-desilication process and the residues from a- lumina extraction process are hard to utilize, which restricts the industrialization of this technology. The alumina-extracted residues were used to improve the modulus of sodium silicate solution. The effects of the various silicon sources such as quartz sand, commercially available ultrafine silica and the alumina- extracted residues of coal fly ash on the modulus of sodium silicate solution were investigated. The mechanism of the alumina-extracted residues as silicon source to improve the modulus of sodium silicate solution and the effects of the impurities were discussed. The treated sodium silicate solution was used to prepare value-added silicon dioxide products. The X-ray diffraction （XRD） and inductively coupled plasma atomic emission spectroscopy （ICP-OES） were used to characterize the phase and chemical com- positions. The results show that the alumina-extracted residues can be used to improve the modulus of sodium silicate solution owing to the residues containing amorphous silica. The sodium silicate solution with modulus more than 3.0 can be obtained when the alumina-extracted residues reacted with sodium silicate solution at 100 ℃ for 30 min. The value-added silica product produced from this high modulussodium silicate solution can afford the HG/T 3061-2009 standard.