Extraction of metals from sulphides using sulphur trioxide in fluidised bed

The kinetics of the reaction of chalcopyrite, iron sulphide, copper sulphide, and nickel sulphide with sulphur trioxide gas were studied using a fluidised bed technique. O₂, N₂, or air was used as a carrier gas for the sulphur trioxide in fluidisation. Binary mixtures of finely ground (0.37–75 μm) samples were reacted with the sulphur trioxide in a Pyrex column at 373–673 K. The reaction products were leached with water and the soluble metals in the solution were determined by atomic absorption spectrometry. The total soluble reaction products were determined gravimetrically. The results obtained showed that a higher yield of soluble salts was obtained when O₂ or air was used as a carrier gas for sulphur trioxide than when an inert gas was used. Higher yields of soluble salts were obtained when the samples were most finely ground. Increase of copper sulphide content in binary mixtures with iron or nickel sulphide led to an increase in the yield of soluble salts. For iron sulphide/nickel sulphide mixtures, the yield of soluble salts increased with the nickel sulphide content. There were maximum values for the soluble metal ratios Ni/Fe and Cu/Ni in the corresponding sulphide binary mixtures and this maximum was at about 50% weight. The soluble Cu/Fe ratio increased with copper sulphide content in mixtures with iron sulphide.     

Calendering of non-newtonian fluids

The calendering of non-Newtonian fluids by two rotating cylinders to produce thin films of fluids finds wide application in polymer sheet-making and food-drying industries. Theoretical work has previouly been devoted to the symmetrical case where the cylinders are of equal diameters rotating at the same speed. The present work proposes a new one-film theory of calendering of power law fluids for unequal radii and surface velocities of the calendering cylinders. The relationship between the dimensionless thickness of the calendered fluid, Δ_e^* and that of the incoming fluid, Δ_i^* is shown to be a function of the ratio of the surface velocities of the cylinders and the power law index. The result further shows that Δ_e^* tends to asymptote after the second decade of Δ_i^*     

Surface morphology and nodule formation mechanism of cellulose acetate membranes by atomic force microscopy

By the use of atomic force microscopy (AFM), formation mechanism of nodular structure in cellulose acetate membranes was systematically investigated. Elementary factors affecting the nodule formation were delineated on the basis of both kinetic and thermodynamic considerations. It was shown that (1) the exact nature of nodular structure is thermodynamic equilibrium glassy state; nodular structure will vanish in the rubbery state; (2) the thermodynamic factor affecting nodule formation is the membrane formation temperature; with the membrane formation temperature decreasing, more chain segments are able to form nodular structures; (3) nodule formation is dependent on the segment rearrangement; variation of the solvent environment is the major kinetic factor affecting the segment rearrangement and nodule formation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1328–1335, 2003     

Photochemical degradation of glassy polyesters of low softening point

The photodegradation of polyesters prepared by the reaction of o-phthalic, adipic, and “dimer” acids with ethylene glycol has been studied. The polyesters softened at temperatures in the range of 25–50°C. Polymer films were irradiated in air by means of a medium pressure mercury lamp and the extent of formation of COOH groups determined by infrared spectroscopy. The films were also irradiated in vacuo and in air by means of a high-pressure mercury lamp, and the volatile products, consisting mainly of carbon monoxide and carbon dioxide, were determined by gas chromatography. The results are interpreted in terms of simultaneous Norrish type I and type II decompositions of the polyesters. The type I process accounts for the formation of carbon monoxide and carbon dioxide in the absence of air. The enhanced yield of carbon dioxide in irradiations performed in air is ascribed to the formation of hydroperoxide which undergoes further photolysis. The type II process accounts for the formation of COOH groups. The photodegradation of these glassy polyesters parallels that of crystalline poly(ethylene terephthalate) and is relatively unaffected by changes in composition of the aromatic polyester.     

Metal recovery in a pilot-scale rotating cylindrical wiper-blade electrode system

The performance of an experimental pilot-scale electrochemical reactor using a rotating cylindrical electrode equipped with wiper blades is described. Data obtained from monopolar depositing and bipolar stripping—depositing of copper from dilute aqueous electrolytes are presented and certain economic aspects of metal recovery are discussed.     

Impacts of new technologies on media usage and social behaviour in domestic environments

Technological infrastructure at home is changing continuously and is becoming increasingly interconnected. Media devices, including the TV set, provide access to the Internet and offer manifold opportunities to consume media on demand. Additionally, personal devices, such as smartphones, also enable flexible consumption and sharing of media. Questions about how these technologies change the user's media usage and how these changes affect the social structure of a household, however, remain largely unanswered. In order to gain insight into the adoption of new technologies into daily routines, we explored these changes in respect of people's media usage in a qualitative long-term Living Lab study. We will present findings regarding personal routines, flexible integration of new devices into existing practices, influences on households as social systems and related issues in device access and collective use. We will highlight potentials and conflicts regarding device shifts and roles; restrictions in device access; social influences in the living room; and individual changes in media consumption.     

抗日战争时期的青年心理探析

抗日战争是中华民族历史上的一次大浩劫,中国人民为此承受了太多的痛苦与磨难,特别是对于肩负着国家与民族振兴使命的青年更是如此.分析战时青年的心理变化及原因,指出政府和社会对青年人的心理没有采取恰当的方法进行有效的疏导,提出要总结和吸取历史的经验教训,为我们今天应对大灾难提供借鉴.     

Effects of Copper Coating on the Crystalline Structure of Fine Barium Titanate Particles

We have investigated the effect of a metal coating—copper—on the tetragonal structure of fine barium titanate (BaTiO₃) particles. The BaTiO₃ particles were synthesized by a sol-gel method and heat treated at temperatures >900°C for various amounts of time before coating. The copper coating was achieved by an electroless coating technique. The transmission electron microscopy micrographs revealed that the coated powder contained fine BaTiO₃ particles that were embedded in copper patches. The X-ray diffractometry patterns showed that the copper coating increased the c/a ratio of the fine BaTiO₃ particles. For powders that were heat treated at 900°C for 10 h and were initially cubic, the copper coating changed the c/a ratio, from 1 to 1.0034. For powders that were calcined at 900°C for 20 h and were initially tetragonal, the copper coating further enhanced the c/a ratio, from 1.0028 to 1.0043. When the copper-coated BaTiO₃ particles were oxidized, the c/a ratio was reduced to a value that was approximately equal to or below that of the uncoated powders. A conductive coating can eliminate the depolarization energy of an insulating polar particle. The fact that the copper coating promoted the polar tetragonal phase but the nonconductive copper-oxide coating did not was consistent with the interpretation that the presence of the cubic phase (nonpolar) in small BaTiO₃ particles was caused by the depolarization effect.     

论焊接结构生产的技术改造

本文讨论了焊接结构生产技术改造的有关问题，包括总思路及总目标、自动化的基本框架、按低成本自动化的原则设计生产线和关键技术问题的论述。