An Alternative Technique for the Extraction of Valuable Elements from Fly Ash: the Carbochlorination Method

Russian Journal of Non-Ferrous Metals - The extraction of valuable elements from high-alumina fly ash was carried out using two methods, the carbochlorination method and the carbothermic method....     

Extraction Separation of Sc(III) and Fe(III) from a Strongly Acidic and Highly Concentrated Ferric Solution by D2EHPA/TBP

The solvent extraction and separation process of Sc(III) and Fe(III) from a strongly acidic and highly concentrated ferric solution using mixtures of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) in sulfonated kerosene was studied. The effects of various parameters, including D2EHPA concentration, dosage of TBP, and phase ratio, were investigated for the extraction process. The results indicated that the extraction rate of Sc(III) was 99.72% with 1.09% Fe(III) co-extracted after two stages of counter-current extraction under optimal conditions. Moreover, saturation capacity and slope analysis were used to determine the reaction mechanism. Sc(III) is extracted in the form of HSc(SO₄)₂·4HL. Further separation of Sc(III) and Fe(III) was realized in a scrubbing and stripping process. First, 98.67% of the co-extracted iron in the loaded organic phase was scrubbed with a dilute HCl solution by a three-stage counter-current scrubbing. Then, 85.00% of Sc(III) can be stripped efficiently with a 2-mol/L NaOH solution saturated in 1-mol/L NaCl by three-stage cross-current stripping.     

Computational Fluid Dynamics (CFD) Simulations on Multiphase Flow in Mechanically Agitated Seed Precipitation Tank

The large-scale mechanically agitated tank has been widely used in the decomposition process of sodium aluminate solution in the alumina industry. The mixing process in three types of seed precipitation tanks (Robin, Ekato, and improved Ekato) stirred with multiple impellers was compared by using computational fluid dynamics, respectively. The flow field, solid distribution, mixing time, and power consumption were numerically simulated by adopting a Eulerian granular multiphase model and a standard k-ε turbulence model. A steady multiple reference frame approach was used to represent impeller rotation. Compared with the Robin tank, the Ekato tank can generate an axial circulation loop, which is better for fluid mixing and solid suspension; meanwhile about half of the power can be saved. With future improvements in the Ekato tank, the fluid mixing and exchanging can be enhanced under the interaction of a lengthened Intermig impeller coupled with sloped baffles. With a little increase in power consumption, the maximum of the relative solid concentration difference in the whole tank can be maintained within 3%, which meets the design requirement.     

燃烧合成法制备CaB6的研究

以CaO、B2O3、Mg粉为原料燃烧合成制备了CaB6粉末.考察了不同反应体系的差热曲线,采用XRD、SEM以及粒度分析技术对燃烧产物、浸出产物进行了表征.结果表明:Mg-B2O3-CaO反应体系872℃附近放热峰的表观活化能E=15.71kJ·mol-1,反应级数n=1.1,反应的表观活化能很小,说明合成CaB6的反应容易发生.燃烧产物由MgO、CaB6以及少量的Mg3B2O6和Ca3B2O6等组成,在空气中进行燃烧合成反应并不生成氮化物;燃烧产物经硫酸浸出处理后CaB6纯度达92.5%;随着制样压力的增大,CaB6粒度逐渐变小.     

燃烧合成法制备NdB6超细粉体及反应机理

以B₂O₃、Nd₂O₃和Mg为原料, 采用燃烧合成法制备出NdB₆超细粉体。考察了反应气氛、制样压力和物料配比对反应产物微观形貌和物相的影响。采用XRD、SEM对产物进行了表征, 结果表明: 燃烧产物由NdB₆、MgO以及少量Mg₃B₂O₆和Nd₂B₂O₆组成, 稀硫酸处理去除可溶性成分后, 产物为单一的NdB₆相, 纯度为99.1%。随着制样压力的增大, NdB₆颗粒尺寸逐渐变小。制样压力为20 MPa时, 制备的NdB₆粉末平均粒度小于500 nm。Mg-B₂O₃-Nd₂O₃三相反应历程: 首先Mg还原Nd₂O₃生成单质Nd和MgO, 然后引发Mg还原B₂O₃生成单质B和MgO, 同时生成的Nd和B反应得到NdB₆, 反应的表观活化能为691.59 kJ/mol, 反应级数为3.2。     

管式搅拌反应器功率特性研究

以新型管式搅拌反应器为研究对象,在冷态物理模拟的基础上,研究了管式搅拌反应器内的功率特性,以水作为介质,在流量0～3.6 m3/h,搅拌转速100～400 r/min范围内考察了搅拌转速对功率的影响,并对功率准数与雷诺数的关系进行了分析.研究结果表明,在实验范围内,T型桨管式搅拌反应器的搅拌功率P与N1.3～1.4近似成正比;搅拌功率准数与雷诺数满足下列关系式Np=109.79Re1.69.     

Effects of Diffusion with Electrode Spacing and Concentration Difference on Al2O3 Preparation from AlCl3 Solution by Electrotransformation

Russian Journal of Non-Ferrous Metals - With China’s bauxite resources depleting year by year, high-alumina fly ash has been regarded as a potential secondary aluminum resource, with alumina...     

Research on Alumina Preparation by Electrolytic AlCl3 Solution under NH4Cl Catalysis

Russian Journal of Non-Ferrous Metals - With rapid economic development, a bauxite shortage has seriously restricted China’s aluminum industrial development. As a potential alumina secondary...     

液体胍胶非水悬浮液的制备与水合性能

采用羟丙基胍胶、聚乙二醇及悬浮剂等制备了液体胍胶非水悬浮液,分别考察了液体胍胶非水悬浮液的表观黏度、悬浮率及水合速率,进一步探讨了该液体胍胶体系快速水合起黏的影响因素。流变及静置沉降实验结果表明,季铵盐改性的有机黏土适合作为液体胍胶的悬浮剂,液体胍胶的黏度随悬浮剂加量的增加而轻微增加,且其悬浮率随该悬浮剂加量的增加而急剧增大。悬浮剂加量为5%的液体胍胶在340 s-1下的表观黏度为650m Pa·s左右,在1 d内基本不沉降,在2 d内的悬浮率能够保持在98%以上。粉液比(胍胶与聚乙二醇的质量比)在1∶5~1∶2之间时,其对应的液体胍胶于340 s-1下的表观黏度值在200~700 m Pa·s之间,具备较好的流动性,便于连续混配设备泵送。水合起黏实验结果表明,与在中性环境下相比,弱酸性环境下采用该液体胍胶配制的压裂液基液具有更快的水合起黏速率,而碱性环境下该压裂液基液基本不起黏。配液用水pH值为5时,基液黏度在3~5 min内即达到最佳基液黏度的85%~90%。配液时采用高剪切循环速率会加快液体胍胶的起黏速率。