Study on purification and application of novel precipitant for ceria-based polishing powder

Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result could be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate could reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as concentration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm could be prepared when the concentration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was controlled at 25 ml/min. Compared with commercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of commercial polishing powder.     

用高岭土制备施胶沉淀剂聚合氯化铝的研究

以高岭土和质量分数为20％的废盐酸为原料，采取两段溶出酸浸法工艺制备作为松香施胶沉淀剂的聚合氯化铝(PAC)，并对其在施胶体系中的理化性能和电化学性能进行测试。结果表明，在焙烧温度为750～800℃，焙烧时间为2～3h、高岭土与盐酸的用量比为1：1．75(g／mL)、酸浸温度为85～95℃、酸浸时间为1h的最佳工艺条件下制备的PAC的盐基度为37．3％，在施胶体系中能达到很好的沉淀效果；电泳实验结果表明，当pH值为5．0～10．0时，PAC均能保持正电性。该工艺具有操作简便，生产成本低等特点，并为高岭土的利用开辟了一条新途径。     

Sm-MnOx catalysts for low-temperature selective catalytic reduction of NOx with NH3: Effect of precipitation agent

A series of Sm-Mn mixed oxide catalysts were prepared via precipitation using various precipitants,namely Na₂CO₃(NH₄)₂CO₃,and NH₃·H₂O,and evaluated for the selective catalytic reduction(SCR) of NO_x with NH₃ at low temperatures.Various characterisation techniques were used to determine the physicochemical properties of the catalysts,and it is found that their catalytic performance is greatly influen...     

丹宁分解产物对电解的影响

文章分析了丹宁分解物对锌生产工艺及其产品的危害 ,指出了还原物在电锌工艺中的行为扼制的措施     

粗硫酸镍脱除钙镁的工艺研究

研究了用化学沉淀法脱除粗硫酸镍中的Ｃａ、Ｍｇ。实验表明，络合沉淀剂是一种效果较好的沉淀剂，在６０℃、ＰＨ值在３．０－６．０之间、用量系数为１．５、反应时间１ｈ以上时，其脱除Ｃａ、Ｍｇ的效果良好，能达到电池用酸镍标准。     

溶胶共沉淀法制备ZrO2超细粉末的工艺研究

采用正交试验方法研究了溶胶共沉淀法制备ＺｒＯ２－Ｙ２Ｏ３陶瓷粉末的工艺过程，对粉体进行了粒度，ＸＲＤ，ＳＥＭ观察，结果表明，对粉体粒度影响最大的是母液浓度，而母液温度则无明显影响，母液ｐＨ值不同影响ＺｒＯ２的晶体，正交试验优化出了用ＮＨ４ＨＣＯ３作为沉淀剂制备了ＺｒＯ２粉末的最佳工艺参数，即：母液浓度１．０ｍｏｌ／Ｌ，ｐＨ＝５～６事实表明，用此法制粉成本低，周期短，效率高。     

高比表面积氧化镁粉体的制备

以MgCl2·6H2O和沉淀剂为原料,采用沉淀法制备MgO粉体。考察了制备条件对产物比表面积的影响,确定了高比表面积MgO粉体的制备条件：碳酸钠为沉淀剂、MgCl2溶液浓度1．0mol／L、反应温度30℃、反应体系pH值为9．8～10、中间产物焙烧温度500℃。     

硫酸铝与聚硅酸硫酸铝对松香胶施胶效果的影响

本文就硫酸铝与聚硅酸硫酸铝（PASS）对阴离子分散松香胶施胶效果进行比较，采用PASS能在接近中性的条件下抄纸，也可使用价格低廉的碳酸钙作填料。     

沉淀剂对胶质溶液喷雾热解Sm_(0.2)Ce_(0.8)O_(1.9)固体电解质结构的影响(英文)

分别采用碳酸铵((NH4)2CO3,AC)和碳酸氢铵(NH4HCO3,AHC)作沉淀剂制备胶质溶液,利用胶质溶液喷雾热解制备纳米晶氧化钐掺杂氧化铈(Sm0.2Ce0.8O1.9,SDC)电解质粉末。通过X射线衍射、热重分析和扫描电镜表征粉末和陶瓷的结构和形貌,探讨沉淀剂对前驱体和SDC粉末形貌、粒径和结晶相的影响及作用机理。结果表明:通过AC途径制备的喷雾热解粉末呈球状,经700℃热处理后,得到的SDC粉末聚集体粒径小于0.5μm,具有很高的烧结活性,经1250℃烧结4h获得的陶瓷密度达到理论密度的96%;通过AHC途径制备的喷雾热解粉末经热处理后仍保持片状,相应的陶瓷呈多孔结构,只有理论密度的79%。     

液相沉淀法制备HfO2纳米粉体

以HfOCl2·8H2O为原料,采用化学沉淀法在不同的pH值下制备HfO2纳米粉体,并对制备的纳米粉体采用XRD,DSC-TG,TEM,BET等方法进行表征.研究了pH值对粉体比表面积、粒径的影响.结果表明:本方法制备的纳米粉体呈简单正交晶型,平均粒径为10m,粒度分布窄,随着pH值的增加,粉体有比表面积增大,平均粒径减小的趋势,但变化幅度较小.