The flowchart is developed for gold ore flotation at the reduced impurity of the rougher flotation product with difficult middlings. The rougher flotation concentrate is subjected to scavenging by ...aerated air and hot steam mixture. In cold pulp slurry, the steam condensation heat is removed from bubbles to wetting films. With increasing temperature, the hydrophilic repulsive forces, that stabilize the films, can be reduced to excess osmotic pressure between the hydrophilic surfaces, and the instability of the films between the hydrophobic surfaces can be reduced to excess osmotic pressure of surrounding water, i.e. to the hydrophobic attraction forces. The test machine is designed to measure heat-transfer coefficients during aeration of water by air–steam mixture. The revealed heat loss patterns enable determining the efficient steam flow to ensure water heating in the interfacial layers of bubbles at the minimized loss of the heat source. Using an ore sample, it is demonstrated that it is possible to enhance gold recovery using the designed circuit of rougher flotation and the method of rougher concentrate scavenging.
This paper is dedicated to a study of conductivity and current-voltage characteristics (IV curve) of lithium niobate (LN, LiNbO3) single crystals. The studied crystals have been turned to a single ...domain state. We have researched nominally pure congruent (CLN) and strongly doped LiNbO3:Mg and LiNbO3:Zn crystals at Т = 300–450 K. Magnitude, activation energy and type of conductivity have been established in CLN, LiNbO3:Mg and LiNbO3:Zn in the temperature range Т = 300–450 K. Coercive field in LiNbO3:Mg and LiNbO3:Zn crystals is much lower than in CLN. However, we have determined that nonlinearity of IV curve exists in CLN crystals and is absent from LiNbO3:Mg and LiNbO3:Zn crystals at temperatures up to 450 K and external electric field strength up to 12 kV/mm. The paper suggests possible explanation for the observed effects.
•Lithium niobate (LN) crystals conductivity and I-V curves are studied at 300–450 K.•Electrical properties of CLN pure, Mg and Zn doped LN single crystals are compared.•Conductivity types were determined in CLN, Mg and Zn doped LN at 300–450 K.•CLN has nonlinear I-V curve, LN:Mg and LN:Zn crystals have linear I-V curves at 400 and 450 K.
Water wetting films on a quartz surface were found to become unstable with increasing temperature. This is believed to be associated with the temperature dependence of the structure of the water in ...the layer at the wall. Aparameter characterizing the strength of the structural forces is calculated from measurements of the contact angle. The sign inversion of the parameter is associated with the forces of hydrophobic attraction predominating over the forces of hydrophilic repulsion in a definite temperature interval. The results of deferrization of glass quartz sands by flotation during thermal action on water wetting films are presented.
The study presents the main directions and modern methods of multiparameter optimization of flow paths, aimed at improving the technical level and efficiency of steam turbines when creating new and ...modernizing existing steam turbine equipment. This approach can be used for creating highly efficient, competitive, and globally recognized steam turbines for thermal power plants, nuclear power plants, and combined-cycle plants.
The authors present the gravity concentration-and-flotation technology for joint processing of gold ore and placer gold mining waste ensuring high gold recovery. The research is carried out using ...samples of ore from a primary gold deposit under mining and from waste of gold placer mining in the Yano- Kolyma gold province in the Russian Federation. The feature of the technology is the use of bullion gold in the gold flotation circuit. Bullion gold is recovered from gold placer mining waste by gravity concentration. The ore and waste processing by gravity concentration and flotation is based on the jet flow of feed material and rough concentrate. The second flotation stream circuit uses the technology of aerosol column flotation. The efficiency of investment to joint processing of gold ore and placer gold mine waste is evaluated.
The article is dedicated to the development and investigation of conditions for obtaining the aggregate stable colloid solutions of magnetite - magnetic fluids. The developed method differs from the ...known ones and involves new ways of producing and stabilizing magnetic nanoparticles with a narrow particle size distribution.
In investigation of the aggregative stability of disperse systems by sediment volumetry, a violation of the structure of water in the contact area causes formation of nanobubbles, whose coalescence ...leads to appearance of hydrophobic attraction forces. A change in the aggregative stability of aqueous dispersions of particles can be interpreted in such a way that ingress of water molecules having a high potential of interaction with molecules of the medium in the interfacial gap between particle surfaces and outflow of water molecules exhibiting high intensity of interaction with a solid surface from the interfacial gap between particle surfaces is difficult. Excess osmotic pressure between hydrophilic surfaces leads to their hydrophilic repulsion, and excess osmotic pressure of the surrounding water (reduced osmotic pressure between surfaces) leads to hydrophobic attraction of the surfaces. To change the result of flotation, it is sufficient to bring a heat flow to a nanoscale-thick liquid layer, within which action of forces of structural origin is localized, determining the stability of wetting films. To increase the temperature in the interfacial gap between the particle and the bubble using the heat of water vapor condensation, as a gas for flotation, a mixture of air and hot water vapor is proposed. The developed flotation method has been tested in flotation of gold ores. The efficient steam flow rate determined from the results of a factorial experiment is 10.7 × 10
–3
kg/(s m
2
), with the xanthate flow rate being 1.74 g/t. In the rough flotation operation, the jet method of constructing a flowsheet is used, which provides for combination of the initial feed and rough concentrate. In comparison with flotation of ores according to a factory scheme, the yield of a concentrate sent to hydrometallurgical processing is smaller by 23.4 rel. %, with the achieved level of gold recovery remaining the same.
A family of Haar multiresolution analyses is constructed in the Hilbert space
L
2
(
), where
is the ring of adeles over the field ℚ of rationals. The corresponding discrete group of translations and ...the scaling function are, respectively, the group of additive translations by elements of ℚ embedded diagonally in
and the characteristic function of the standard fundamental domain of this group. As a consequence, a family of orthonormal wavelet bases in
L
2
(
) is obtained. Note that both the number of generating wavelet functions and the number of elementary dilations are infinite. Bibliography: 7 titles.
The prerequisites for the formation of a modern model of relations between regional authorities and print media in the Rostov region, as well as the process of evolution of these relations from 1985 ...to 1991 is discussed in the article. The author singled out two characteristic stages, carried out their study, revealed characteristics and features. The results of a comparative analysis are presented on a number of fundamental parameters, such as the degree of independence of editorial teams in choosing an information agenda, administrative and legislative control by the party leadership. Particular attention is paid to the historical context, as well as the peculiarities of the development of the media institution itself. The novelty of the study is seen in the fact that a comprehensive study of the relationship between regional authorities and the print media on the materials of the Rostov region has not been previously carried out, a number of previously unpublished archival documents have been introduced into scientific circulation. It has been established that by 1991, horizontal ties had arisen and strengthened in the Don media, new approaches to interaction with state authorities began to take shape. A new generation of professional journalists who were actively involved in politics (they were elected to representative bodies of power at various levels), the development of commercial advertising began.
The electrical conductivity of a series of LiNbO
3
crystals grown from the charge of the congruent composition with relatively low iron concentration (up to 0.15 wt % Fe
2
O
3
) has been studied ...experimentally. It is found that, at temperatures close to 300 K, the main contribution to the electrical conductivity of these crystals is from two types of the centers with close activation energies. The first type of centers are Fe
2+
ions, which determines the impurity electron conductivity with the activation energy (0.34 ± 0.01) eV. The second type of centers are
polarons of small radius with the activation energy (0.29 ± 0.02) eV. The polaron conductivity is shown to be dominate for nominally impurity-free and low-doped “as-grown” LiNbO
3
crystals at
T
= 300 K.
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