煅烧和消化工艺对白云石活性的影响

以白云石为原料,采用柠檬酸测定法,通过控制煅烧温度、保温时间、消化温度和消化时间等因素,研究了煅烧和消化工艺对白云石活性的影响及最佳的煅烧和消化条件.结果表明:煅烧温度为950℃,保温时间为1.5 h时,煅烧产物中的氧化镁活性最好;以最佳煅烧条件下得到的白云灰粉进行消化反应,消化温度为80 ℃、消化时间为30 min时,得到的消化产物活性最高.工艺简单、操作方便,对进一步利用白云石制备氢氧化镁和氧化镁产品具有重要的参考价值.     

煅烧工艺制度对轻烧白云石活性度的影响

通过煅烧实验和显微结构观察,研究了煅烧工艺对三种自云石轻烧后活性度的影响,得出如下结论：（1）保温时间为90min,随煅烧温度提高轻烧白云石的活性呈现先升高、后降低的趋势,在1050℃活性度达到最高点。（2）对应某煅烧温度存在一个煅烧时间使轻烧白云石活性最高。（3）白云石的煅烧颗粒尺寸影响煅烧产物活性度。（4）白云石原矿的显微结构对煅烧产物活性度有很大影响,一般晶粒粗大的原矿易得到活性较高的煅烧产物。     

熔盐法制备氧化镁粉体的研究

以氯化镁、碳酸钙、氯化锂为原料,采用熔盐法制备了氧化镁粉体。通过热重-差示扫描量热仪(TG-DSC)、X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)等手段对反应过程及产物进行了分析和表征,同时采用水解动力学分析法研究了煅烧温度和煅烧时间对氧化镁粉体活性的影响。TG-DSC分析表明:在650℃时碳酸钙可完全反应。XRD分析表明:在430℃保温3 h条件下进行热处理,产物中有氧化镁生成;在650℃保温3 h条件下进行热处理,产物经无水乙醇洗涤后,全部为氧化镁晶体,经SEM分析表明,所制备的氧化镁形貌为颗粒状,形状不规整,大小介于50~250 nm。水解动力学分析表明:当温度大于500℃、保温时间超过3 h后,随着热处理温度的升高和时间的延长,氧化镁粉体的活性下降。     

白云石制备高纯氧化镁的工艺研究

以白云石为原料,通过煅烧、消化、硫酸酸浸、过滤得硫酸镁溶液,采用氨水沉淀法制备氢氧化镁中间体,经煅烧得高纯氧化镁。研究了加入硫酸后白云石灰乳终点pH、反应温度、硫酸镁浓度和煅烧温度对镁的浸出率、沉淀率以及产品氧化镁纯度的影响,最终确定最佳工艺条件为：灰乳终点pH为6,反应温度为40 ℃,硫酸镁浓度为0.8 mol/L,煅烧温度为900 ℃。在此条件下制备的氧化镁纯度达到99.0%以上,满足高纯氧化镁的要求。     

利用菱镁矿制备高活性氧化镁

以菱镁矿为原料,先在850℃下煅烧2h获得轻烧氧化镁,然后水化成氢氧化镁,干燥后在不同温度(分别为450℃、500℃、550℃、600℃)和保温时间(分别为1h、1.5h、2h)下轻烧,通过分解氢氧化镁制备了高活性氧化镁。结果表明:氢氧化镁在500℃时完全分解成氧化镁;轻烧温度和保温时间对氧化镁活性(用吸碘值表征)有较大的影响,随着温度的升高,氧化镁活性逐渐降低,而在相同温度下,随着保温时间的延长,氧化镁的活性降低;在加热温度为500℃,保温时间为1h的条件下轻烧分解氢氧化镁,能得到吸碘值达191.42mg·g-1的活性氧化镁。     

白云石的热分解对氧化镁活性的影响

采用碘吸附法研究了白云石热分解温度对氧化镁活性的影响,测定了不同分解温度下制备氯氧镁水泥的固化时间,得出白云石制备氯氧镁水泥的最佳分解温度为680℃,此时产物中氯化镁活性最高.制备氯氧镁水泥制品后固化时间最短;当分解温度超过720℃时,产物中氧化镁的活性度低,不具备生产氯氧镁水泥的条件.该研究为利用白云石生产氯氧铁水泥提供了一条合理的途径.     

工艺因素对轻烧白云石活性度的影响

为考察白云石轻烧工艺对轻烧白云石活性的影响,为实际白云石轻烧生产提供最佳轻烧条件,以河南卫辉白云石为主要原料,研究了其粒度(分别为5±2、10±2、20±2、50±5和(100±5)mm)、轻烧温度(分别为1 100、1 200、1 250℃)和保温时间(分别为1、2、3 h)对白云石轻烧料活性度的影响。研究结果表明,白云石的粒度、轻烧温度和保温时间对轻烧白云石的活性度有较大影响,其最佳工艺条件为:粒度(20±2)mm,轻烧温度1 200℃,保温时间2 h。     

由碱式碳酸镁制备过氧化镁

以碱式碳酸镁为原料,首先经过煅烧制备出活性较高的氧化镁,活性氧化镁再与过氧化氢溶液经反应、过滤及干燥制备出过氧化镁产品.研究结果表明,碱式碳酸镁的煅烧时间和煅烧温度对合成过氧化镁的活性氧含量有较大影响,最佳煅烧时间为2 h,煅烧温度为650℃;通过对反应液固比、反应温度及反应时间进行考察,确定了适宜的工艺条件:在室温下...     

白云石制备高纯氧化镁工艺研究

以白云石为原料,经煅烧、消化、碳化、热解、烘干制备出CaO质量分数小于0.1％的碱式碳酸镁,煅烧后制备出MgO质量分数高于99％的高纯氧化镁.研究了白云石煅烧温度、消化条件、碳化终点pH、碳化时(NH4)2C2O4的加入及加入时的pH对消化效率、碳化效率以及产品纯度的影响.确定了最佳工艺条件:白云石最佳煅烧温度为910...     

氧化镁活性及用于烟气脱硫的实验研究

用柠檬酸法和XRD法测定氧化镁的活性,得到氧化镁活性与煅烧温度和煅烧时间的关系。用菱镁矿煅烧制备的氧化镁进行湿法烟气脱硫试验,结果表明,当煅烧温度为650℃、煅烧45min时,氧化镁活性最好,在650℃下煅烧45min和700℃下煅烧30min时的氧化镁的脱硫活性好。     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

几种乙炔加压设备性能的比较

阐述并比较了几种加压设备在乙炔加压清净过程中的性能和特点。     

三种煤样燃烧热的测定

本文通过三个厂家提供的三种煤样燃烧热的测定,由测定结果综合得出3号煤样燃烧最完全、燃烧热也最大,是三个煤样中最好的一种。     

Semi-empirical equation of state of metals. Equation of state of aluminum

A semi-empirical equation of state for metals is described. Its capabilities are demonstrated by the example of the equation of state for aluminum. New experimental data are presented on the location of the isentrope of aluminum for unloading from the state at p = 229.71 GPa on the shock adiabat to an aerogel (SiO₂) of density 0.08 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 61–75, March–April, 2008.     

水泥水化热测定方法综述

水泥水化热是中、低热水泥和核电工程用水泥的一项关键的技术指标。全球范围内测定水泥水化热的方法有溶解法、直接法/半绝热法、等温传导量热法三种。本文总结了中、美、欧相关方法标准,对其测试原理、仪器设备、试验过程等方面进行了比对,并对其在领域的应用做了简单的概括。     

Calorimetric and Computational Study of Enthalpy of Formation of Diperoxide of Cyclohexanone

A thermochemical rather simple experimental technique is applied to determine the enthalpy of formation of Diperoxide of ciclohexanone. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6–311G basis This set level. Some possible extensions of the present procedure are pointed out.     

我国聚碳酸酯工业发展概况

介绍我国聚碳酸酯生产能力和消费需求,对聚碳酸酯在信息工业中的应用作了简短介绍     

小议汽车涂装工艺设计对涂装成本的影响

论述了涂装工艺设计对涂装设备投资、涂装生产成本的影响。     

Effect of degree of deacetylation of chitosan on the kinetics of ultrasonic degradation of chitosan

The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003     

Measurement of the gradient of viscosity with composition of mixtures of non-ideal gases

A perturbation viscometer is a differential capillary viscometer that measures the logarithmic viscosity gradient of the viscosity-composition curve for gas mixtures. Measurements are made at different gas mixture compositions. Integration of the logarithmic viscosity gradients measured over the full composition range gives the mixture viscosity relative to the viscosity of one of the pure components of the gas mixture. This method is attractive because, for measurements of equal precision, integration of the gradients is potentially an order of magnitude more precise than measurement of the viscosities directly. It can also work at high and low temperatures and perhaps high pressures.The perturbation viscometer has been used to make measurements on ideal gas mixtures at ambient and elevated temperatures. The situation is more complicated when the gas mixtures are non-ideal. Extra effects due to density differences, molar volume change on mixing and differential thermal expansion may be measured in addition to the desired viscosity change producing systematic errors in the results. Thus, a more sophisticated apparatus is required. The standard perturbation viscometer has been modified to separate out the extra effects to permit measurement of the true change in viscosity. In addition, the theoretical operation of the modified apparatus has been revised to account for the design changes to permit calculation of the viscosity-composition profiles from the results.The apparatus has been tested using helium-HFC-125 mixtures and two new viscosity-composition profiles are presented for these mixtures at 23 and . Internal consistency tests have been used to confirm that the data produced are of high quality with an estimated uncertainty in the viscosity ratio data at of 0.9% and at of 1.5%.