THE EFFECT OF PRECIPITATION PARAMETERS ON PREPARATION OF LITHIUM FLUORIDE (LIF) NANO-POWDER

Lithium fluoride powder (LiF) is a white powder with a density of 2.64 gr/cm³ and a melting point of 848°C. This powder has several applications such as flux, glaze, soldering, and aluminum melting process, but one of the most important uses of this powder is its application in dosimetry. The commercial powders currently used for this purpose have average sizes of 5 to 10 micrometers; the objective of this research is to produce LiF powder with nano-metric particle size. In this study, the reaction of LiOH + HF → LiF + H₂O has been selected from among several reactions that were able to produce LiF powder, and some precipitation parameters such as temperature, time, agitation type, and supersaturation degree have been controlled. The morphology, phase analysis, and particle size distribution of the resulting powders were analyzed by SEM, XRD, and LPSA. Finally, lithium fluoride nano-powder was synthesized at a temperature of 25°C, pH about 2-3, reaction time less than 1 s, and agitation by ultrasonic bath.     

Effect of agitation in the hydrogenation of castor oil

Castor oil was hydrogenated to evaluate the effect of agitation during hydrogenation. The turbine and propeller impellers were evaluated during hydrogenation of castor oil at various temperatures, pressures, and catalyst concentrations. The effect of impeller position in the agitator at definite oil depth was also evaluated. Hydrogenation of castor oil at 130°C, 2.0 kg/cm² hydrogen gas pressure with 0.5% Ni catalyst for 6 h while using two turbine impellers fitted in an agitator, one close to the reactor bottom and another at a height just below the top oil layer, revolving at 350 rpm, resulted in a product of a iodine value of 4.1, hydroxyl value of 156.4, and slip point of 84°C.     

A new method for recovering valuable metals from low-grade nickeliferous oxide ores

A new method, the concentrated sulfuric acid acidolysis and water leaching (SAWL) of nickeliferous oxide ores, is proposed and the optimal conditions for recovery of nickel, cobalt and copper from a low-grade Chinese nickeliferous oxide ore are presented. A series of experiments were conducted which examined the effect of acid charge, acid curing temperature and acid curing time. Recoveries of up to 95%, 83% and 95% for Ni, Cu and Co, respectively were obtained with only the sulfuric acid at ambient temperature and atmospheric pressure. Comparing the percolation leaching with agitation leaching showed that percolation leaching was capable of extracting the valuable metals with water. The SAWL method was scaled to three-stages counter-current leaching tests using 1 kg of ore. The results indicate greater than 90% extraction for nickel and cobalt.     

新疆某铀矿石浸出试验

为了给新疆某铀矿采用地面堆浸和井下原地爆破堆浸的采矿新方法恢复生产提供依据，对该矿矿石进行了试验室搅拌浸出和柱浸试验。试验结果表明，该矿矿石氧化剂耗量少、浸出时间短、酸耗较低，属易浸矿石。矿石粒度对浸出率影响较大，当粒度从-5mm增加到-20mm时，矿石的柱浸渣计浸出率从88.7％下降到75．2％。氧化剂可提高浸出液铀浓度，但提高幅度不大。     

反应器结构对黄原胶发酵的影响

本文通过对黄原胶在不同结构的发酵罐上生产结果的研究，分析讨论了发酵罐的搅拌器、罐体高径比、桨叶直径与挡板、加热系统及通气量控制等因素对发酵的影响。认为加大高径比值，增加桨叶层数，减小桨叶直径，消除挡板的剪切影响，增大调温系统的传热面积并降低热源温度，控制合理的通气量等方式都是提高发酵产品产量与质量的有效途径。     

产毒藻培养用光生物反应器结构研究

设计研制了一种新型光生物反应器。该光生物反应器具备光照、温度、pH、二氧化碳、溶氧、营养源等培育条件在线自动化控制功能。采用低剪力搅捧、高效气液交换混合、低功耗高效LED光源设计,解决了海洋产毒微藻工程化培育中的关键技术问题。该反应器结构简单、易于工程化放大,系统可广泛适用于海洋微藻类及其它相关代谢产物的培养生产。并且详细阐述了新型光生物反应器的设计思路和工作原理。     

Effect of agitation pretreatment on anaerobic digestion of swine manure

This study evaluated the effect of mechanical agitation pretreatment on anaerobic digestion (AD) of swine manure (SM). The results showed a remarkable increase in soluble polysaccharides, soluble proteins, and soluble chemical oxygen demand (SCOD) by 82.42%, 121.17%, and 114.89%, respectively, after the SM being agitated for 22 h. No improvement in the volatile fatty acids (VFAs) yield was observed during the agitation pretreatment. Apparently, agitation significantly accelerated the hydrolysis of SM, while it did not seem to enhance the acidification step. Batch AD experiments showed an improved accumulative methane yield by 77.89% with the pretreated SM compared to raw SM.     

轴流式生化搅拌器的研制进展

讨论并研究了轴流式搅拌器的结构特点,工作原理,通过比较,指出轴流浆比径向流圆盘涡轮浆在发酵搅拌过程中具有传质效率高,搅拌功率低,混合效果好等优点。     

Development of testing procedure for ceramic disc filters

Small-scale laboratory tests for sizing and designing disc filters are typically performed by using leaf test equipment. Although the basic tests are fairly simple and quick, the accuracy and repeatability of the results may be poor due to various reasons. In addition to errors caused by variations in the structure of the equipment, also the skills and experience of the person performing the tests is of great importance. This paper introduces an experimental study carried out for defining the most important sources of errors in these kinds of laboratory tests and for estimating their influence on the final test results. The results obtained in this study were utilized for designing an improved version of the test equipment and also for creating a standard procedure for performing the tests. The results acquired with the small-scale laboratory tests were in good agreement with the performance results obtained from full-scale ceramic disc filters operating in industrial processes.     

内外单螺带—锚搅拌槽中粘弹性流体的流速分布和混合时间

本文用照相法测定了内外单螺带锚搅拌槽中高粘牛顿流体和粘弹性流体的流速分布,用示踪粒子法和脱色法分别测定了循环时间和混合时间,结果发现: (1)在低Re~*数下,对于同一转速,粘弹性流体的切向速度大于牛顿流体,而轴向速度则小于牛顿流体。 (2)在槽中的低剪切区,两种流体的剪切率分布相差不大,而高剪切区的剪切率和全槽平均剪切率都是粘弹性流体的大。 (3)粘弹性流体的混合时间NT_M和循环流量N_q与牛顿流体和假塑性流体相比分别增加一倍和降低70％右左。