The role of iron and its compounds in processes of enrichment of sulfide ores of non-ferrous and noble metals

On the basis of the analysis of the literature data and the data of our investigations, the role of iron and products of its oxidation in sulfide pulps is shown. The technological factors are noted, such as the pH value of the medium, concentration of modifiers, mineral composition, and points and the order of batching flotation reagents; which affect the redox processes with the participation of iron and the characteristics of separation of sulfide minerals during flotation.     

Wear of magnesia spinel refractories in portion vacuum-processing steel plant

Conclusions The processes of wear in the lining of vacuum chambers of outdoor-furnace vacuum-treatment plants (UPVS) are due to the simultaneous action of high temperatures, deep vacuum, gaseous medium, molten metal, and slag. The corrosion and erosion of aggressive melts of slag and metal are the decisive forms of wear.Laboratory investigations established the relationship between slag resistance in vacuum and the ratio of corrosive and erosive constituents in the wear of different magnesia-spinel refractories and their phase composition, structure, and properties.Refractories obtained from fused periclase-chromite material with a low content of fusible silicates showed that in laboratory vacuum equipment and during service in the linings of the vaccum chamber of industrial plant they have higher slag resistance and lower wear than refractories based on sintered magnesite, spinel, and chromite ores.Translated from Ogneupory, No. 3, pp. 14–21, March, 1980.     

Influence of mechanical activation of basic refractories and mixtures on sintering

Conclusions Mechanical activation leads to partial breakdown of the crystalline structures of refractory materials, conferring a higher reaction state on them. This is manifest as a reduction in the temperature range in which the magnesite and dolomite undergo conversions during heating, and also in the greater degree of exposure of the periclase and chrome concentrate.The porosity of the clinker obtained from activated sintered periclase with (CaO + SiO₂) >3.5%, fused periclase obtained from magnesite calcined in a shaft furnace, raw magnesite and periclase-skin, is reduced by more than an order compared with the original. It is considerably less for periclase-chromite skin, is reduced by more than an order compared with the original. It is considerably less for periclase-chromite skin, sintered periclase with (CaO + SiO₂) <3.5%, fused periclase-chromite, and periclase obtained from Kul'dursk brucite.To determine the possibility of applying these results in production conditions, research is now being conducted to select effective production activators, e.g., equipment with an elastic deformable working component.The authors would like to thank N. B. Kusin'sh, G. I. Vikulina, G. N. Bondarenko, and A. P. Kima for assistance in completing this work.Translated from Ogneupory, No. 3, pp. 14–17, March, 1993.     

Effect of radiation heating on the creep of polymeric materials

Strength of Materials -     

A method and integrated circuit for processing random data streams in multichannel experimental physical equipment

An asynchronous data stream processing method in multichannel experimental physical equipment is described. The conversion of an input data stream irregular in time into data synchronized with the fundamental clock frequency of the system is considered. The realization of the proposed method as part of the specialized integrated circuit manufactured by the CMOS process of the UMC Co. (Taiwan) with 0.18-μm design rules is presented. The structure, principle of operation of the microcircuit, and experimental results of its tests are described. The work is performed as a part of the CBM experiment of the new FAIR accelerating facility (GSI, Darmstadt, Germany).     

Exponential Queuing Network with Dependent Servicing, Negative Customers, and Modification of the Customer Type

The open exponential queuing network with negative customers (G-network) was considered.For each arriving customer, given was a set of its random parameters such as the route defining the sequence of network nodes passed by the customer, route length, size, and servicing duration at each stage of the route. It was assumed that the negative customer arriving to the sth node with the probabilities _s and _s ⁺ either kills the positive customer in a randomly chosen server or does not affect it at all and with the probability _s ^– =1 – _s – _s ⁺ transforms it into a negative customer which after an exponentially distributed time arrives to the sth node with the given probability. The multidimensional stationary probability distribution of the network states was proved to be representable in the multiplicative form.     

On a Retrial Single-Server Queueing System with Finite Buffer and Multivariate Poisson Flow

We consider a single-server queueing system with a finite buffer, K input Poisson flows of intensities _i , and distribution functions B _i (x) of service times for calls of the ith type, . If the buffer is overflowed, an arriving call is sent to the orbit and becomes a repeat call. In a random time, which has exponential distribution, the call makes an attempt to reenter the buffer or server, if the latter is free. The maximum number of calls in the orbit is limited; if the orbit is overflowed, an arriving call is lost. We find the relation between steady-state distributions of this system and a system with one Poisson flow of intensity where type i of a call is chosen with probability _i / at the beginning of its service. A numerical example is given.