Extraction of alumina from fly ash by ammonium hydrogen sulfate roasting technology

NH4HSO4 roasting technology was used for preparing Al2O3 from fly ash. First, Al and Fe were extracted from fly ash by NH4HSO4 roasting and deionized water leaching. Then, the Al and Fe in the leached liquid were precipitated by adding NH4HCO3 solution. After the mixed precipitations of Al（OH）3 and Fe（OH）3 were leached by NaOH solution, the NaAl（OH）4 solution was decomposed by carbonation. Finally, the pure Al（OH）3 was calcined to α-Al2O3. The optimal conditions of the whole technology were determined by experiments. The quality ofa-Al2O3 product is up to the technical indicator of YS/T 274-1998 standard.

Study on extracting alumina from fly ash by compound additive activation method

According to the chemical and mineral composition characteristics of the fly ash,alumina can be extracted from fly ash through the calcining method by using sodium carbonate and calcium carbonate additives.The effects on leaching rate of alumina have been investigated. The results showed that the fly ash can be activated effectively and the leaching rate of alumina can be improved to more than 92% through this method. The best process parameters were the ratio of raw materials,i. e. the material weight ratio of fly ash,calcium carbonate and sodium carbonate was 1. 0∶1. 2∶0. 9. The activating temperature was 850℃-900℃,activating time was 3 h. This process has a potential application prospect and improves the value of comprehensive utilization of fly ash.

Effect of Temperature on Phase and Alumina Extraction Efficiency of the Product from Sintering Coal Fly Ash with Ammonium Sulfate

A new developed technology for extracting alumina from coal fly ash was studied in this paper. In this technology, coal fly ash is first sintered with ammonium sulfate, forming ammonium aluminum sulfate in the resultant product, where alumina can be easily leached without using any strong acid or alkali. The products obtained under different sintering conditions were characterized by X-ray diffractometry. Alumina extraction efficiency of these products was also investigated. The results show that the sintering temperature and time substantially influence the phase composition and alumina extraction efficiency of sintered products, while the heating rate has little influence. The optimal sintering condition is 400 °C for 3 h in air with a heating rate of 6 °C·min-1.Under the optimal sintering condition, the alumina extraction efficiency from as-sintered coal fly ash can reach 85% or more.

Synergistic extraction of rare earth elements and alumina from coal fly ash by potassium pyrosulfate

Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other drawbacks.To address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient analysis.The REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in CFA.The extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is higher.At high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in CFBFA.The Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction efficiencies.The developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.

准格尔矿区粉煤灰提铝残渣的理化性质研究

为了实现对准格尔矿区煤粉炉粉煤灰提取氧化铝后残渣的利用，以进一步提高粉煤灰的综合利用率，通过密度与细度分析、荧光光谱分析、化学分析、晶相分析、岩矿分析、形貌分析等手段，对残渣的化学成分、矿物构成、形貌特征、活性特征等理化性质进行了研究．结果表明，该类残渣的可磨性好；残渣主要成分以SiO2为主，占90％以上，Al2O3约占4％～6％，CaO和Fe2O3和量不足1％；残渣粒度集中在0．02mm以下，少量在0．02—0．2mm之间，粒度越大者含量越少．残渣中仍然以非晶质（玻璃相）成分为主，约占85％～90％，晶质相约占10％～15％，主要为石英及少量的刚玉、长石、云母；大部分颗粒表面呈多孔、疏松结构．SEM分析表明，提铝残渣颗粒形貌完全不同于粉煤灰原灰形貌，且多为不规则玻璃体颗粒，表面粗糙不平、并呈多孔、疏松结构．

粉煤灰提铝残渣改性制备橡胶填料

以酸法提铝后的粉煤灰残渣为填料,通过研磨改性等处理后用于增强丁苯橡胶,研究残渣的添加量、粒径、不同改性剂处理对丁苯橡胶补强效果的影响,并对不同改性剂改性效果和机理进行探讨。结果表明:当残渣和白炭黑质量相当时,改性产品拉伸强度为5.33 MPa,断裂伸长率较白炭黑增大30%左右,为851.26%;当残渣研磨60 min(d50=5.35μm)时其拉伸强度为5.70 MPa,断裂伸长率可以达903%;经过4种改性剂处理后,橡胶的断裂伸长率和拉伸强度有明显的变化,其中硅烷偶联剂KH550改性后,其拉伸强度高达9.12 MPa,硅油改性后断裂伸长率增大到949.86%。

粉煤灰酸溶渣合成13X分子筛及其对铜离子吸附性能

利用循环流化床粉煤灰一步酸溶法提取氧化铝后剩余的尾渣为原料,通过碱溶-水热法合成了13X分子筛。研究结果表明:溶液硅铝比、溶液p H、晶化温度等因素对分子筛的合成影响显著。对合成的分子筛进行了X射线衍射(XRD)、氮气吸附-脱附曲线、扫描电镜(SEM)表征,并详细考察了其对铜离子的吸附效果。吸附实验结果表明:铜离子饱和吸附量为41.02 mg/g,去除率达到99%以上。这为粉煤灰提铝后高硅尾渣的综合利用开发了新途径,具有较好的市场应用前景。

粉煤灰提铝渣对预脱硅液模数的调控

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.