从硫酸铝溶液制取高纯超细氧化铝过程中杂质的行为及控制

对从硫酸铝溶液中,采用中和沉法制取高纯氧化铝过程中杂质的行为进行了分析。提出了采用添加有机试剂结合屏蔽铁离子,添加无机盐来除去重金属离子,从而制得纯度大于９９．９９％的高纯氧化铝,本文对除杂机理进行了详细的理论计算。     

混流式水轮机偏工况运行的大涡模拟方法验证

为更准确地预测混流式水轮机在偏离最优工况时的内部流动特性和外特性,采用大涡模拟方法(LES)对其进行数值研究,针对LES方法,对比单相流计算和空化模型计算的结果.结果表明:基于空化模型的LES预测混流式水轮机内部流场比单相LES更为精确,偏工况下,多相流LES计算能捕捉到更准确的叶道涡结构和尾水管涡带结构.对比模型实验结果表明,LES计算能更好地预测水轮机的外特性,包括流量曲线和效率曲线.基于非定常的水轮机内部流动的LES,使用Q方法提取转轮区的空化叶道涡和尾水管涡带,研究叶道涡的高频运动和涡带的低频演化规律,在活动导叶开度10 mm、单位转速64.9 r/min工况下,叶道涡演化频率为转频的15倍,而涡带演化频率为转频的0.4倍,和实验结果相符合,验证了在复杂三维流动中LES方法的准确性.     

Synthesis and reaction behavior of calcium silicate hydrate in basic system

1　INTRODUCTIONIt skeytoseparatealuminafromsilicainaluminaproductionbyBayerorsinteringprocess .Whethersilicachangestosodiumaluminosilicatehydrateorhydro garnet(bothtitleddesilicationproduct,DSP) ,bothcontainso daoralumina .IfDSPisdischargedoutdirectly ,alargeamountofsodaandaluminawillbewasted ,meanwhiledischargedDSPwillresultinheavyenvironmentalpollu tion .InpresentitcostsalottorecoveraluminaandsodafromDSPbysinteringprocess[1] .Soitisurgenttodevel opnewhydro processtechnologytorecove…     

铝酸钠溶液碳酸化分解的热力学

为对高浓度铝酸钠溶液碳酸化分解过程中产品杂质含量的控制提供理论依据，分析了铝酸钠溶液碳酸化分解过程的热力学，认为该过程中Al(OH)3析出的真正机理是过饱和铝酸钠溶液的自发结晶；而基于分解过程中平衡浓度的热力学计算表明，在碳酸化分解过程中SiO2的变化规律与公认的三段变化规律一致，说明该过程产品中SiO2的含量取决于它在溶液中的平衡浓度，而非吸附所致；同时还分析了丝钠铝石的形成热力学。     

水轮机压力脉动的混沌动力学特性

为有效进行水轮机的运行监测和故障诊断,采用混沌动力学方法对水轮机在偏工况运行时的压力脉动特征进行研究.利用提升小波变换对压力脉动实验数据进行去噪,给出压力脉动信号时域分布及各频率成分的能量分布情况.分析脉动信号由轻度空化发展到严重空化过程中的一系列动力学特性,包括时频特征分布、相轨迹图、李雅普诺夫(Lyapunov)指数图和庞加莱(Poincaré)映射图等.结果表明:水轮机尾水管压力脉动的主要能量分布在低频段,随着空化程度的加重,频谱脉动强度增大;对于研究工况,最大Lyapunov指数均大于零且随空化程度增加而增大,说明水轮机压力脉动信号存在混沌吸引子.利用本文方法进行多工况分析,可完成在线运行监测.     

软件工程课程案例剖析及项目实践组合教学法

为解决软件工程教学中存在的问题,案例剖析教学方法侧重提高理论分析过程的参与性．而项目实践教学方法侧重提高项目实践过程的参与性,在实际教学过程中将这两种方法有机结合．增强了课程的理论教学水平,同时也提高了学生的动手实践能力,教学实践验证了该组合教学方法的可行性。     

The Applicability of Debye-Hückel Model in NaAl(OH)4-NaOH-H2O System

Focusing on the most important NaAl(OH)4-NaOH-H2O system in the industry of alumina production, the feasibility of establishing a calculation model of activity coefficients according to Debye-Hückel theory via the equilibrium solubility data of sodium aluminate solution is discussed in this paper. Firstly, the hypotheses for applying Debye-Hückel theory into NaAl(OH)4-NaOH-H2O system are involved and the values of parameters are determined. Then the applicability of Debye-Hückel model in NaAl(OH)4-NaOH-H2O system is testified. The results indicate that Debye-Hückel model is applicable to the establishment of calculation model of activity coefficients in NaAl(OH)4-NaOH-H2O system and the value of ?NaAl(OH)4 is estimated as 0.3595 nm.     

采用烧结法处理高铁赤泥回收氧化铝

利用氧化铝热力学数据库,对高铁赤泥炉料烧成过程中的相关化学反应进行热力学计算,并在此基础上,研究烧成温度、烧成时间、炉料配比等烧成工艺条件对高铁赤泥炉料烧成效果的影响。研究结果表明：赤泥炉料的配钙量可以在较宽的范围内变化,并且在烧成过程中可能生成不溶盐类,导致熟料中氧化铝的溶出率降低：延长烧成时间和增加配料铁酸钠含量均有利于烧结：高铁赤泥炉料的最佳配料是：熟料中Na2O-Fe2O3质量分数为10％12％,钙铁摩尔比为1．0-1．2：烧成工艺条件是：温度为1000-1050℃,烧成时间为30--40min。在最佳配料和烧成工艺条件下,当熟料中氧化铝含量为15％左右时,熟料中Al2O33回收率可达85％-90％。     

Properties of Water Blown Rigid Polyurethane Foams with Different Funetionality

Water blown rigid polyurethane foams with different functionality were prepared.The physical properties of rigid foams were measured with rotational viscometer(NDJ-1),universal testing machine (Instron3365),scanning electron microscope(SEM)and differential scanning calorimeter(DSC).The results show that the viscosity of polyether polyol increases exponentially from 62 mPa s to 6 000 mPa s with the increase of functionality from 2 to 5.6,respectively.The overall density of foam increases slightly from 31.7 kg/m~3 to 37.4 kg/m~3 with increasing functionality while core density exhibited little difference.Compressive strength of foam shows the similar behavior with density except for 2-functional sample.At the same time, dimensional stability becomes better with increasing functionality except for 5.6-functional foam that has worse stability than 4.8-functional foam.From the SEM results,the functionality is not an important factor in determining distribution of cell size of foam,According to the results of thermal analysis,the glass transition temperature(T_g)shifts to a higher temperature from 128.9℃to 166.3℃for the 2 to 5.6 functional foam, respectively.     

Thermodynamics of chromite ore oxidative roasting process

To explicate the thermodynamics of the chromite ore lime-free roasting process,the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied.The thermodynamics calculation shows that all the standard Gibbs free energy changes of the reactions to form Na2CrO4,Na2O·Fe2O3,Na2O·Al2O3 and Na2O·SiO2 via chromite ore and Na2CO3 are negative,and the standard Gibbs free energy changes of the reactions between MgO,Fe2O3 and SiO2 released f...