助磨剂对粉石英超细磨矿的影响

研究了三乙醇胺对粉石英超细磨矿的影响及助磨作用机理，采用粒度分析，Ｘ－射线衍射分析、红外光谱分析等测试手段，定性描述了助磨的作用效果。并解释了助磨剂有效控制粉石英粉碎平衡，降低极限，延缓“团聚”形成的原因。     

微波助磨的研究现状及进展

重点讨论了热力粉碎和微波助磨的作用机理、国内外的研究现状和今后的发展方向。     

助磨剂对粉石英超细磨矿的影响

研究了三乙醇胺对粉石英超细磨矿的影响及助磨作用机理，采用粒度分析、X-射线衍射分析、红外光谱分析等别代手段，定性描述了助磨剂的作用效果。并解释了助磨剂有效控制粉石英粉碎平衡、降低粉碎极限、延缓“团聚”形成的原因。     

粉石英尾砂超细粉碎研究

采用搅拌球磨机对粉石英尾砂进行超细粉碎实验。在最佳实验条件下 ,可使 99.9%的粉石英尾砂粒径在 2 0 μm以下     

微波助磨的研究现状及进展

重点讨论了热力粉碎和微波助磨的作用机理，国内外的研究现状和今后的发展方向。     

粉石英细磨过程中的团聚现象

以粉石英为例，揭示了超细粉碎过程中特有的团取现象。以大量实验数据和理论分析为基础，描述和论证了团聚现象的种种表现，具有普遍的意义。为在超细粉碎中合理选择工艺条件，有效控制粉碎极限和延缓粉碎平衡，推迟“逆粉碎”的出现提供了一定的参考依据，对推进粉体技术的发人有一定的理论意义和实用价值。     

粉石英细磨过程中的团聚现象

以粉石英为例，揭示了超细粉碎过程中特有的团聚现象．以大量实验数据和理论分析为基础，描述和论证了团聚现象的种种表现．具有普遍的意义。为在超细粉碎中合理选择工艺条件．有效控制粉碎极限和延缓粉碎平衡，推迟“逆粉碎”的出现提供了一定的参考依据，对推进粉体技术的发展具有一定的理论意义和实用价值。     

粉石英在行星球磨过程中的晶体结构的变化

论述了用行星球磨机对粉石英进行超细粉碎时所发生的晶体结构和物理化学方面的变化。采用粒度分析、扫描电镜、Ｘ－射线衍射、差热分析等测试手段,揭示了粉石英在球磨过程中晶体结构变化的特征,剖析了粉石英在球磨过程中呈现出的阶段性以及同步性的特点。并通过碱溶和水溶试验,验证了表面无定形层的形成     

磨矿介质形状对石英砂粉碎参数的影响

以粒径为 2～2. 36、0. 83～2 mm的石英砂为原料,钢球、短圆柱形钢锻为磨矿介质,磨矿质量为500 g,矿浆质量分数为65%,磨矿时间为0. 5、1、2、4、8 min,钢球的个数配比:D_(30)∶D_(25)∶D_(20)=43∶62∶96,短圆柱钢锻个数配比:D_(30×30):D_(25×25):D_(20×20)=28∶41∶64,介质充填率为0. 4,球磨机转速为96 r/min,进行分批次磨矿。结果表明:不同介质形状下,石英砂的粉碎速率遵循一阶动力学模型,且在短时间内短圆柱钢锻的粉碎速率明显大于钢球的,表征物料粉碎难易程度的γ值越小粉碎越容易,φ、β表征粗颗粒粒级破碎至相应细粒级的速率,短时间(1 min)粉碎过程中介质形状对初始粉碎分布参数有影响,钢锻和钢球介质相比:γ值偏小,而φ和β值偏大。建议在石英砂的粉碎过程中,可以选择钢锻介质对其进行快速破碎。     

卧式行星磨内物料的粉磨特性

利用自制卧式行星磨对钢渣及水泥熟料进行粉磨特性及粉磨动力学研究。结果表明,粉磨后物料都满足Rosin-Rammler-Bennet粒度分布规律,钢渣及水泥熟料粉磨过程都可用一级Kapur函数描述,钢渣的粉磨速率小于水泥熟料的;在实验条件下,相对于水泥熟料,钢渣破碎更多地表现为摩擦破碎方式;钢渣进料粒级对粉磨后所得到产品的概率影响较大,粉磨前可将钢渣预破碎至粒径为1.7 mm。     

Effects of grinding aids on the grinding kinetics and surface morphological characterization of quartz

The kinetic parameters of a grinding process can be used to study the variations in particle size reductions and grinding efficiencies. Appropriate grinding aids usually change the surfaces of a material and the properties of the pulp, thus improving the grinding efficiency. In this paper, pure quartz samples with mixed particle sizes and single particle sizes were selected as the raw materials. The effects of different sodium tripolyphosphate (STPP) and citric acid (CA) dosages on the dynamic parameters k, selection function S₁ and breakage function B for quartz grinding were studied. The results showed that the STPP and CA enhanced the grinding process of the quartz. In other words, the parameter k, the selection function S₁ and the breakage function B were all increased to varying degrees. The results of SEM, BET and contact angle measurements showed that the surfaces of the quartz particles became rounder, the specific surface area and average pore size increased, and the surface hydrophilicity increased. As a result, the grindability of the quartz increased, and the grinding kinetic parameters changed. Finally, the results showed that the improvements in the quartz grindability were consistent with the influence of grinding aids on the kinetic parameter k, selection function S₁ and breakage function B_i,1.     

Effects of mechanical grinding on pozzolanic activity and hydration properties of quartz

To provide basic research into the utilization of mine tailings as supplementary cementitious materials in cement, the pozzolanic activity and hydration properties of quartz-a common mineral phase in mine tailings-after undergoing mechanical grinding were investigated. In this study, a supplementary cementitious material was obtained using the mechanical grinding of quartz. Prolonged grinding resulted in a gradual increase in the pozzolanic activity index and percentage of dissolution in an alkaline solution, as well as a reduction of the relative crystallinity. The particle size appeared to have reached a limit after 80 min of grinding; however, the specific surface area reached its limit after 120 min of grinding, which was mainly due to the continual increase in pore volume of the micropores and mesopores from the grinding process. As an active supplementary cementitious material, the hydration product of ground quartz was an amorphous C-S-H gel in the presence of calcium hydroxide. This study provides a research basis for investigating the pozzolanic activity and hydration properties of ground quartz, which is beneficial to an evaluation of the pozzolanic activity of siliceous mine tailings after mechanical activation.     

Effect of thermal oxidation on titanium oxides' characteristics

Nanocrystalline TiO₂, in the form of anatase or rutile, is one of the most important and used photocatalysts because of its excellent conversion efficiencies and its chemical stability. TiO₂ layers can be grown on titanium by means of anodising processes: the so-obtained oxides present either amorphous or semicrystalline structure, depending on process parameters. When a homogeneous oxide with maximum thickness of the order of hundreds of nanometres is formed, a wide range of interference colours appear on the oxide surface, showing different hues and saturations. Similar effects are obtained when the oxidation process consists of a thermal treatment. This work is aimed at the exploration of the parameters involved in thermal oxidation and of their influence on the growing oxide characteristics, with particular reference to its thickness and the contingent generation of crystal phases (anatase and rutile) responsible for photoinduced properties. Oxide characteristics are investigated by means of reflectometry and X-ray diffraction. Thermal treatments proved to be an efficient way to tune oxide thickness and structure, in order to achieve the formation of oxides showing photoactivated properties both in the UV and in the visible light range, as well as to tune their chromatic properties.     

Effect of grinding conditions on mechanochemical grafting of poly(1-vinyl-2-pyrrolidone) onto quartz particles

Grinding of quartz in an aqueous solution of 1-vinyl-2-pyrrolidone (VP) in a stirred media mill results in grafting of poly(1-vinyl-2-pyrrolidone) (PVP) onto the quartz particles as proven by FTIR-spectroscopy. The grinding kinetics, the particle size of the final product and the amount of PVP grafted onto the silica particles depend on grinding conditions like VP and quartz concentration, pH and size of grinding media. The grinding kinetics becomes slower in the presence of VP due to the damping effect of the forming PVP chains. The final particle size, however, is almost independent on VP concentration. The amount of PVP grafted onto the silica particles ground for 12 h increases with growing VP concentration because the amount of adsorbed VP and the polymerization rate increase with growing VP concentration.The primary particle size and the kinetics of particle breakage do not depend on the pH-value of the dispersing medium, whereas the degree of agglomeration of the particles decreases with increasing pH-value of the medium. Under alkaline conditions, however, less PVP is grafted onto the quartz particles than under neutral or strong acidic conditions. The reasons for these effects are pH-dependent interactions between the grafted PVP chains and the surface hydroxyl groups on the quartz particles. If the quartz concentration in the suspension decreases the grinding kinetics becomes much faster because the specific energy input increases with decreasing particle concentration if the other process parameters are kept constant. For a very low quartz concentration (1 wt.%), however, after 7 h of grinding the particle size measured by dynamic light scattering starts to increase with grinding time. SEM investigations reveal that grinding of 1 wt.% quartz in aqueous VP solution for longer than 7 h results in the formation of plate-like particles.     

Computer thermal model for hardening grinding

A mathematical model of heat transfer in steel parts under force grinding is considered that allows one to determine the grinding parameters at which a steel layer of prescribed thickness is heated up to hardening temperatures. Results of numerical simulation of the process of hardening grinding are compared with experimental data. The internal structure of the material after hardening grinding is analyzed. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 430–438, March–April, 2000.     

Effect of fibre pre-treatment on thermal characteristics of asbestos-nylon-epoxy composites

The objective of this study has been the enhancement of understanding the role of fibre pre-treatment in determining the thermal expansion behaviour and glass transition temperature of fibre-reinforced thermosetting polymers. Asbestos fibres were pre-treated with poly(hexamethylene adipamide) and used afterwards as filler reinforcement in a bisphenol-A-based epoxy matrix. Two alternative processes of fibre pre-treatment were used. Thermal expansion coefficients and glass transition temperatures for the asbestos-nylon-epoxy composites were experimentally determined. Results are qualitatively explained by theoretical models in which the concept of the is considered. The effects of asbestos and nylon content as well as of type of pre-treatment and adhesion between the phases are investigated.     

Introduction of color centers in fluorinated sol gel quartz glasses by radiation thermal treatment

Data are presented to show how fluorination influences the optical quality and radiation resistance of quartz glasses fabricated by the sol gel method. It is found that under the action of gamma radiation, mainly E′ centers form in the glasses. The incorporation of fluorine in the xerogel lattice promotes the removal of hydroxyl groups and enhances the radiation optical resistance of the synthesized samples in the red. It is observed that the radiation resistance of the glass is enhanced in the ultraviolet by using irradiation-annealing cycles and this is attributed to a decrease in the concentration of radiation-induced E′ centers. Pis’ma Zh. Tekh. Fiz. 23, 74–79 (December 26, 1997)     

Effect of optimum thermal treatment on BiSrCaCu2Oy

BiSrCaCu₂O _y compositions have been subjected to different atmosphere treatments and cooling schedules after initial calcination and firing in air. The large variation in properties has been explained on the basis of oxygen disorder effects and possible insertion of oxygen in different planes.