高铝粉煤灰拜耳法溶出渣碱回收
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摘要
针对高铝粉煤灰拜耳法溶出渣进行了脱碱工艺研究,考察了[n(C)/n(S)](Ca O与Si O2物质的量比)、反应温度、反应时间、液固比及体系碱浓度等对脱碱的影响,同时考察了脱碱过程对氧化铝溶出率的影响.结果表明:添加石灰的方式可以实现高铝粉煤灰拜耳法溶出渣中氧化钠的脱除,并回收部分氧化铝;反应温度对氧化钠和氧化铝回收率均造成显著影响,而[n(C)/n(S)]仅对氧化钠的溶出率影响较大;在温度260℃、氧化钠质量浓度小于80 g/L、液固比4、[n(C)/n(S)]为1. 8、反应时间2 h条件下,脱碱率为91. 2%,氧化铝回收率为28. 0%;拜耳渣脱碱过程物相由水合铝硅酸钠向水化石榴石及铁水化石榴石转变.
The dealkalization process of the Bayer leaching slag of high alumina fly ash was studied. The influences of [n( C)/n( S) ]( the molar ratio of CaO to SiO2), reaction temperature,reaction time,liquid-solid ratio and alkaline concentration on dealkalization rate,and the effect of dealkalization process on the alumina leaching efficiency were investigated. The results indicated that the lime-adding method can realize the removal of sodium oxide from the Bayer leaching slag of high alumina fly ash and recover part of alumina. The recovery of sodium oxide and alumina is significantly affected by reaction temperature,but [n( C)/n( S) ] only affects the dissolution of sodium oxide. The alkali removal ratio and alumina recovery ratio are91. 2% and 28. 0% respectively under the conditions of 260 ℃,NaO concentration less than 80 g/L,liquid-solid ratio 4,[n( C)/n( S) ]1. 8 and reaction time 2 h. The phase of Bayer leaching slag transforms from sodium aluminosilicate hydrate to hydrogarnet in the dealkalization process.
The dealkalization process of the Bayer leaching slag of high alumina fly ash was studied. The influences of [n( C)/n( S) ]( the molar ratio of CaO to SiO2), reaction temperature,reaction time,liquid-solid ratio and alkaline concentration on dealkalization rate,and the effect of dealkalization process on the alumina leaching efficiency were investigated. The results indicated that the lime-adding method can realize the removal of sodium oxide from the Bayer leaching slag of high alumina fly ash and recover part of alumina. The recovery of sodium oxide and alumina is significantly affected by reaction temperature,but [n( C)/n( S) ] only affects the dissolution of sodium oxide. The alkali removal ratio and alumina recovery ratio are91. 2% and 28. 0% respectively under the conditions of 260 ℃,NaO concentration less than 80 g/L,liquid-solid ratio 4,[n( C)/n( S) ]1. 8 and reaction time 2 h. The phase of Bayer leaching slag transforms from sodium aluminosilicate hydrate to hydrogarnet in the dealkalization process.
引文
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[3] Stanislav V V,Christina G V. Methods for characterization ofcomposition of fly ashes from coal-fired pow er stations:acritical overview[J]. Energy and Fuels,2005,19(3):1084-1098.
[4] Ahmaruzzaman M. A review on the utilization of fly ash[J].Progress in Energy and Combustion Science,2010,36(3):327-363.
[5] Yao Z T,Xia M S,Sarker P,et al. A review of the aluminarecovery from coal fly ash,w ith a focus in China[J]. Fuel,2014,120(15):74-85.
[6]张战军.从高铝粉煤灰中提取氧化铝等有用资源的研究[D].西安:西北大学,2007.(Zhang Zhan-jun. Research on extraction of alumina andother useful resources from high aluminium fly ash[D].Xi'an:Northw est University,2007.)
[7]郭强.粉煤灰酸法提取氧化铝的工艺研究进展[J].洁净煤技术,2015,21(5):115-122.(Guo Qiang. Development on leach of alumina from fly ashby acid method[J]. Clean Coal Technology,2015,21(5):115-122.)
[8] Wu C Y,Yu H F,Zhang H F. Extraction of aluminum bypressure acid-leaching method from coal fly ash[J].Transactions of Nonferrous Metals Society of China,2012,22(9):2282-2288.
[9] Seidel A,Slusznv A,Shelef G,et al. Variation in fly ashproperties with milling and acid leaching[J]. Fuel,2005,84(1):89-96.
[10] Wu Y S,Xu P,Chen J,et al. Effect of temperature on phaseand alumina extraction efficiency of the product from sinteringcoal fly ash with ammonium sulfate[J]. Chinese Journal ofChemical Engineering,2014,22(11/12):1363-1367.
[11] Matjie R H,Bunt J R,Heerden J H P. Extraction of aluminafrom coal fly ash generated from a selected low rank bituminoussouth african coal[J]. Mineral Engineering,2005,18(3):299-310.
[12]张廷安,郑朝阵,吕国志,等.高铝粉煤灰制备氢氧化铝的比表面积及孔隙特性[J].东北大学学报(自然科学版),2014,35(10):1456-1459.(Zhang Ting-an,Zheng Chao-zhen,Lyu Guo-zhi,et al. Specificsurface aera and pore characteristics of aluminum hydroxideprepared from high-alumina fly ash[J]. Journal of NortheasternUniversity(Natural Science),2014,35(10):1456-1459.)
[13] Zhang R,Zheng S L,Ma S H,et al. Recovery of alumina andalkali in Bayer red mud by the formation of andradite-grossularhydrogarnet in hydrothermal process[J]. Journal of HazardousMaterials,2011,189(3):827-835.
[14] Liu W C,Sun S Y,Zhang L,et al. Experimental and simulativestudy on phase transformation in Bayer red mud soda-limeroasting system and recovery of Al,Na and Fe[J]. MineralsEngineering,2012,39:213-218.
[15] Li X B,Xiao W,Liu W,et al. Recovery of alumina and ferricoxide from Bayer red mud rich in iron by reduction sintering[J]. Transaction of Nonferrous Metals Society of China,2009,19(5):1342-1347.
[16]柯家骏,张帆.拜耳法赤泥水热处理的渣物相的热力学分析[J].化工冶金,1994,15(4):341-347.(Ke Jia-jun,Zhang Fan. Thermodynamical analysis on residuephases resulted from hydrothermal treatment of the Bayer redmud[J]. Engineering Chemistry&Metallurgy,1994,15(4):341-347.)