Red mud pulp carbonization with scandium extraction during alumina production

In the existing technology for the processing of bauxites into alumina, scandium remains in red mud. The average scandium concentration in bauxites coming into processing from the Severoural’skoe and Srednetimanskoe deposits is studied. Bauxites are a rich potential source for the production of scandium. The fractional distribution of mud and the concentration of scandium in its fractions are determined. The concentration of scandium in aluminate solutions and that from mud fields is extremely low and amounts to <0.05 g/m3. The processing of mud with a soda solution results in the partial solubility of scandium with its complexing. For the precipitation of scandium, the solubilities of Al, Ga, Zn, and Sc compounds in alkalinesoda-hydrocarbonate solutions are studied under the conditions of reactive and gas carbonization. Zinc hydroxide is the best coprecipitant. The carbonization of red mud pulp provides for the partial recovery of scandium and reduces the toxicity of mud storage areas by converting the alkaline-carbonate liquid phase into a carbonate-hydrocarbonate one with a lower toxicity.     

Simulation of dense random packings of ellipsoidal bodies by mechanical analogy

The statistical properties of dense random packings of ellipsoidal bodies in cylindrical vessels created under the effect of the gravity force are investigated by the numerical method developed from the equations of mechanics of a rigid body. The body-to-body and body-to-wall interaction is described by elastic forces. It has been found that the influence of the gravity force in the presence of walls specifies the statistically meaningful anisotropy of the orientation of ellipsoids. According to the method of the formation of a packing and the spatial separation of bodies by size can be found; this causes a local narrowing of the size spectrum. The method is naturally generalized by including friction forces, arbitrary force fields, and walls of an arbitrary shape.     

Regularities of tinting ceramics based on low-melting clays

The effect of the mineral composition of low-melting red-burning clay, the gaseous medium, and the type of raw materials on the formation of light-colored (white) ceramics as a consequence of the crystallization of iron-bearing crystal phases is established. __________ Translated from Steklo i Keramika, No. 8, pp. 20–21, August, 2006.     

Discrete–continuous analysis of optimal equipment replacement

In operations research, the equipment replacement process is usually modeled in discrete time. An alternative approach is represented by continuous‐time vintage capital models that explicitly involve the equipment lifetime and are described by nonlinear integral equations. The paper introduces and analyzes a model that unites both these approaches. The structure of optimal replacement, transition, and long‐term dynamics, and clustering and splitting of replaced machines are discussed and illustrated with numeric examples. Equipment splitting is demonstrated when the optimal equipment lifetime increases.     

Thermal Oxidation of Ti and Pb Thin Films Deposited on Single-Crystal Silicon

Thin Pb–Ti–O films on single-crystal Si were prepared by magnetron sputtering followed by thermal oxidation of Pb/Ti/Si and Ti/Pb/Si structures. Oxidation of Pb/Ti bilayers was found to yield lead oxides, which then react with Ti to form lead titanate. Ti/Pb bilayers on Si could be converted into stoichiometric lead titanate, through titanium and lead oxides, by oxidation between 870 and 1070 K. Some of the films exhibited ferroelectric properties.     

Rapid Matrix‐Assisted Refolding of Histidine‐Tagged Proteins

Matrix refolded : The formation of inclusion bodies, which are amorphous aggregates of misfolded insoluble protein, during recombinant protein expression, is one of the biggest bottlenecks in protein science. We report a stepwise, rational optimization procedure for refolding of insoluble proteins (see scheme). In comparison to refolding in‐solution, this parallelized, matrix‐assisted approach allows the refolding of various proteins in a fast and efficient manner.

     

Formation mechanism and adhesive strength of white single-layer low-melting enamels on steel

The formation mechanism of white single-layer glass enamel coating on steel surface in low-temperature firing is considered. The basic laws governing strong adhesion are identified. The effect of various methods of pre-treatment of steel before single-layer low-temperature enameling on the structure and composition of the transitional adhesive contact layer determining the adhesion strength of steel — enamel composite is demonstrated.