Transport phenomena in electric smelting of nickel matte: Part I. Electric potential distribution

An electric potential probe was constructed so that simultaneous, multiple measurements of electric potential could be made in a six-in-line electric furnace for smelting nickel calcine having a maximum transformer capacity of 36 MVA. When the electric potential distributions were compared with those calculated from the solution of the Laplace equation, it was evident that there was significant electric potential drop at the electrode surface, 100 to 120 V for an applied potential of 180 to 230 V and currents of 20 to 30 kA. The Soderberg electrodes were continuously oxidized in the slag, likely creating carbon monoxide. The electric potential drop at the surface was attributed to arcing through the carbon monoxide. Thus, heat was released in the immediate vicinity of the electrode due to arcing, as well as in the bulk of the slag by Joule heating. The proper distribution of heat dissipation is required for the transport model, developed in Part II of this series.     

Social influence phenomena in a task-oriented group situation.

"The three variables tested were the size of the group, the duration of group participation, and the identifiability of the source of the response standard… . The three experimental hypotheses tested and the results reported for 182 subjects in test groups of 2, 4 and 6 members… . For the particular situation studied, neither group size nor duration of group participation had significant effects on social influence." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contact phenomena in a sphere-plane single - Crystal system

Conclusions Theoretical considerations, experimentally established facts, and elementary estimates lead to the conclusion that the initial stage of the sintering process may be accompanied by plastic deformation, while a later stage is controlled by diffusion-dislocation flow, in which mass transport responsible for growth of the contact neck takes place under conditions of self-consistency of the dislocation loop generation and dissolution processes. This article is concerned only with monocrystalline objects, but the conclusions arrived at in it can be extended also to real polycrystalline systems. This will necessitate regarding the structural elements of a polycrystal as obstacles to dislocation motion characterized by different degrees of penetrability. An opportunity will thus arise in particular to obtain fuller information on the initial stage of sintering of powder compacts, which are characterized by high sintering activity.Published to stimulate discussion.Translated from Poroshkovaya Metallurgiya, No. 10(214), pp. 14–24, October, 1980.     

Fluid flow phenomena in a single phase coreless induction furnace

New measurement techniques for local velocity, magnetic field, and current density have been applied to the study of electromagnetic and hydrodynamic phenomena in a coreless induction furnace containing an aluminum alloy. The action of electromagnetic shields on the intensity and the structure of the liquid metal flow is reported. It is shown that the direction of the fluid flow and the number and sizes of the recirculating cells may be significantly modified; the electromagnetic stirring may also be practically canceled. The influence of the dimensions of the screens on the structure of the liquid metal flow is examined. Finally, the modification of the fluid flow phenomena is explained by the evolution of the electromagnetic force patterns.     

Recrystallization and grain growth phenomena in a particle-reinforced aluminum composite

Recrystallization and grain growth in a 2219/TiC/15p composite were investigated as functions of the amount of deformation and deformation temperature. Both cold and hot deformed samples were annealed at the normal solution treatment temperature of 535 °C. It was shown that large recrystallized grain diameters, relative to the interparticle spacing, could be produced in a narrow range of deformation for samples cold-worked and those hot-worked below 450 °C. For cold-worked samples, between 4 to 6 pct deformation, the recrystallized grain diameters varied from 530 to 66 μm as the amount of deformation increased. Subsequent grain growth was not observed in these recrystallized materials and noncompact grain shapes were observed. For deformations greater than 15 pct, recrystallized grain diameters less than the interparticle spacing were observed and subsequent grain growth produced a pinned grain diameter of 27 μm. The pinned grain diameter agreed well with an empirical model based on three dimensional (3-D) Monte Carlo simulations of grain growth and particle pinning in a two-phase material. Tensile properties were determined as a function of grain size, and it was shown that grain size had a weak influence on yield strength. A maximum in the yield strength was observed at a grain size larger than the normal grain growth and particle-pinned diameter.     

Fluctuation Behaviors of Air Pressure in a High-Rise Building Drainage System

Air pressure fluctuation behaviors in a high-rise building drainage system (HBDS) are presented by probability density functions and statistical analysis of measured data in the drainage stack in a real-life eighteen-floor building, the Li Ka-Shing (LKS), at PolyU of Hong Kong. Three observation points, at the mezzanine (M), 6th, and 12th floors, are arranged to record the air pressure in the primary building stack. The measured data are stored in a personal computer with a sampling period of 1?s. Statistical analysis revealed that there is an evident floor dependence of the air pressure in the real-life HBDS. The flatness factor of the pressure fluctuation increases with floor number, whereas the skewness factor has a reversed variation tendency; it decreases from a positive value in the M floor to negative values at higher floors. Probability density functions show the pressure fluctuation behaviors are far from normal distributions.     

Photochemical phenomena in nystatin solutions

A case of unilateral ureteral obstruction owing to extensive pelvic endometriosis is presented. There was complete resolution of ureteral obstruction following treatment with synthetic progestin. Sequential assessment of renal function was provided by renal imaging and renograms. It would appear that selected patients with obstructive uropathy may respond favorably to medical management, which would allow for preservation of reproductive capabilities and restoration of renal excretory function.     

Injection phenomena in nonferrous processes

Injection phenomena in a Peirce-Smith copper converter and a slag fuming furnace have been investigated during blowing. A tuyerescope attached to the back of a given tuyere has been employed to observe the build-up, and to obtain samples, of accretions while a piezoelectric transducer has been used to measure pressure fluctuations in the tuyere. It has been found that in both processes the accretions grow upward by a freezing mechanism from the bottom of the horizontal tuyere. Probing the shape of an accretion in the fuming furnace, without coal injection, showed that the accretion grew into the bath 30 to 40 mm from the tuyere tip. A study of the shape and frequency of the pressure pulses as well as the duration of intervals of low pressure in the tuyere has revealed that the closely spaced tuyeres may operate independently or may interact. Tuyeres in a full slag fuming furnace act independently of one another, and the air discharges in the classical bubbling regime at 5 to 6 bubbles per second. In the copper converter there is more tuyere interaction as bubbles growing at adjacent tuyeres coalesce to form a horizontal unstable gas envelope. In both processes if the tuyeres are shallowly submerged the gas may channel directly to the surface without forming bubbles. The influence of bath viscosity, the extent of wall erosion at the tuyere line, and tuyere submergence on these injection phenomena have been elucidated qualitatively. G.G. RICHARDS, formerly Graduate Student