Taguchi Optimization of Solvent-Antisolvent Crystallization to Prepare Ammonium Perchlorate Particles

The sphericity and size of ammonium perchlorate (AP) particles significantly influence the properties of composite propellants. As the AP particles become more spherical, the accumulation coefficient increases, the viscosity during casting decreases, and the particle loading and burning rate increase. Hence, the production of micronized AP particles with an average size between 1 and 20 μm is important to increase the loading percentage of AP in the composite propellant. Here, the Taguchi experimental design was used to optimize the solvent-antisolvent crystallization (SAC) process for the preparation of micronized AP particles with higher sphericity. SAC parameters such as the type of antisolvent, the solvent-to-antisolvent ratio, the antisolvent temperature, the stirring speed, and the retention time were investigated at four levels. The type of antisolvent and the solvent-to-antisolvent ratio were found to mainly contribute to improving the sphericity and size of the AP particles, respectively.     

硫酸体系中锰钽铌矿加压浸出研究

针对单一硫酸体系锰钽铌矿加压浸出下钽铌浸出率均不到10%的问题,在硫酸体系引入助浸剂,考察氟化铵、双氧水、反应压强、硫酸浓度、反应温度、氟化铵矿比对锰钽铌矿加压浸出的影响,采用XRD对浸渣进行物相表征。实验结果表明,在锰钽铌矿加压浸出中,引入助浸剂氟化铵,温度200℃、硫酸浓度50%及氟化铵/矿比为0.8∶1的条件下钽浸出率超过93%,铌浸出率超过96%。引入氟化铵对硫酸体系下锰钽铌矿的加压浸出效果的提升十分显著。     

An intelligent control of NH3 injection for optimizing the NOx/NH3 ratio in SCR system

The distribution of nitrogen oxides (NO_x) flux within the cross-section area in front of ammonia injection grid (AIG) under different operating conditions was obtained by computational fluid dynamics (CFD) method. Weight of NO_x flux in the sub-zone corresponding to each of the ammonia (NH₃) injection branch-pipes of AIG system was analyzed and the sensitivity of which against the plant power load was figured out. A number of “critical” ammonia injection branch-pipes were determined with regard to the weight sensitivity analysis. The selected “critical” branch-pipes were changed to be controlled by the automatic valves, and an intelligent tuning strategy was proposed. The NO_x/NH₃ mixing stoichiometry over the cross-section area in front of AIG system was significantly modified for the high utilization ratio of ammonia. A case work was launched on the selective catalytic reduction (SCR) system of a 660 MW plant. As a result, the ammonia consumption rate (ACR) was found to be reduced by 6.44% compared to that under previous control system, and was 9.31% lower than that of the unapplied system. The methodology for determining the “critical” branch-pipes and intelligent tuning strategy of ammonia injection notably saved the ammonia consumption of SCR system, and the formation of ammonium bisulfate (ABS) were greatly confined.     

Reduction of cresolase and catecholase activities in tubers of some Indian potato varieties by the application of potash fertilisers

Cresolase and catecholase activities were determined in tubers of four potato (Solanum tuberosum L) varieties (Kufri Chamatkar, Kufri Chandramukhi, Kufri Sindhuri and C-2703) fertilised with three levels (0, 120, 240 kg K₂O ha^?1) of either muriate or sulphate of potash. The enzyme activities were also determined separately in the peel and flesh tissues of the tubers of Kufri Chamatkar and C-2703. Differences were observed in the activities between varieties, with highest specific activities in the tubers of Kufri Chamatkar. Peels of both the varieties showed higher cresolase and catecholase activities than the flesh tissue. Application of potassic fertilisers caused a reduction in both the activities in the tuber, peel and flesh tissue. Greater reduction in activities was caused by application of muriate of potash than with the sulphate form.     

硫酸钙晶须的研究现状及进展

根据制备原料的不同,对目前硫酸钙晶须的制备方法进行阐述,并介绍了硫酸钙晶须在复合材料、水处理等领域的应用,从而提出了硫酸钙晶须在制备、应用等方面的未来发展方向。     

D_2EHDTPA萃取铟的热力学研究

报道了用二 (2 乙基己基 )二硫代磷酸为萃取剂 ,以正庚烷为稀释剂萃取铟的热力学研究。在In2 (SO4 ) 3+Na2 SO4 +D2 EHDTPA +n C7H1 6 +H2 O体系中 ,在温度 2 78.15～ 3 0 3 .15K和离子强度 0 .1～ 2 .0mol·kg- 1 范围内 ,以Na2 SO4 为支持电解质 ,测定了萃取平衡水相中In3+浓度和pH值。计算了萃取反应的标准平衡常数K0 ,并得到经验公式logK0 =43 .93 -5 3 68.5 4 T -0 .0 699T ,同时计算了萃取反应的其他热力学量 ,并指出了焓和熵都是此萃取过程的推动力     

废铁屑还原软锰矿制备高纯硫酸锰工艺研究

研究了采用废铁屑作为还原剂,在稀硫酸介质中湿法还原软锰矿制备硫酸锰的工艺过程。通过单因素实验确定最佳工艺参数,结果表明：当Fe/MnO2的摩尔比为0.78∶1,H2SO4/MnO2的摩尔比为2.1∶1,反应温度50℃,反应时间80 min时,锰的浸出率在95%以上。加入碳酸钙中和调节溶液pH值至5~6,使溶液中的铁、铝等杂质离子水解为氢氧化铁、氢氧化铝等沉淀除去,加入硫化钡使浸出溶液中的重金属离子以硫化物沉淀除去,减压过滤得到硫酸锰粗滤液,向粗滤液中加入二氟化锰使溶液中的Ca2＋、Mg2＋等离子生成氟化物沉淀,然后溶液经过静置过滤得到硫酸锰净化液,滤液经浓缩、结晶制备硫酸锰产品。经检测产品纯度在99%以上,杂质含量低于国家标准。     

硫酸铝钾（铵）造成部分食品铝污染的研究

目的:调查食品在加工过程申使用硫酸铝钾(铵),造成部分食品铝污染的现状,为确定污染水平提供基础数据.方法:样品经干燥、灰化、定容后,用铬天青S分光光度法检测,铝的残留量以干样品中铝计.结果:共检测194份样品,铝含量在≤5.00-10522 mg/kg之间,其中45.4%样品超标.结论:油条油饼、粉条粉皮、海蛰存在铝污染问题.     

HKUST-1@APP环氧树脂阻燃复合材料的合成与性能

使用溶剂热法将HKUST-1〔Cu3(BTC)2, BTC为1,3,5-苯三甲酸〕负载到聚磷酸铵（APP）的表面制得HKUST-1@APP,然后将不同量的HKUST-1@APP与环氧树脂（EP）混合后固化制备HKUST-1@APP / EP阻燃复合材料。通过水平垂直燃烧测定仪、氧指数测定仪、电子拉力机等对EP复合材料进行了阻燃和力学性能分析。结果表明,当HKUST-1@APP的添加量为总体系的5%时,复合材料EAC-5的极限氧指数为27.5 %,垂直燃烧测试（UL-94）通过V-1级。添加HKUST-1@APP后,样品残炭的AD/AG(拉曼光谱中无定形碳的碳原子与晶体碳中SP2杂化的碳原子振动分别形成的D峰与G峰的峰面积比)降低到0.043,而添加总质量5%APP的EA-5的AD/AG为0.3161,说明HKUST-1@APP还可以改善环氧树脂燃烧过程中产生的炭层,使炭层更连续、石墨化程度更高。     

含能催化复合纳米材料的制备研究

亚铬酸铜是促进复合固体推进剂中高氯酸铵分解的一种很好的催化剂 ,以往制备的亚铬酸铜及高氯酸铵超细微粒易发生团聚 ,因而不能最有效地对高氯酸铵的分解起催化作用。本文采用溶剂 -非溶剂法 ,使溶液变为过饱和而析出晶体 ,高氯酸铵晶体包覆纳米级亚铬酸铜形成复合粒子 ,较好地解决了这一问题。在复合粒子中 ,纳米级的亚铬酸铜微粒均匀分散于高氯酸铵中 ,由于亚铬酸铜纳米粒子具有很大的比表面积和很高的化学活性 ,因而大大提高了对高氯酸铵的催化效果 ,使高氯酸铵的热分解反应温度区间明显前移 ,热分解反应的激烈程度大大提高