Phenomenological model of mechanoelectric transformations in rocks

A phenomenological model is proposed on the example of the rock destruction development in underground mines. The characteristics of the electromagnetic signal generated due to the appearance and change of the dipole moment of cracks, whose beads are charged when the discontinuity is disturbed, are analytically investigated. The model is constructed using the theory of reliability and percolation theory, which allows to take into account the non-synchronism of the mechanical converters

First records of lyre crab <i>Hyas lyratus </i>Dana, 1851 (Decapoda: Majidae) in the Russian waters (northwestern Bering Sea) and some features of its biology

Males and females of lyre crab Hyas lyratus were found in the northwestern Bering Sea in 2010 (late July - early August), for the first time in the Russian waters. The crabs were caught during the trawl survey by bottom trawl at the depth of 111-169 m, on mixed grounds. Crabs of this species were caught again in the same area in August 2012. Thus, new western limit of the species distribution area is established as the western vicinity of Cape Navarin (61о52′ N 177о51′ E). Size of males was 35-43 mm, size of females varied within the range 19-49 mm. All males were at the 3rd molting stage in 2010 and at the 3rd terminal stage in 2012. All females, except one juvenile, had eggs of orange color. Traumatism (autotomy) of crabs was insignificant. Biological parameters of the crabs from the northwestern Bering Sea are compared with those from the Salish Sea (North-East Pacific)

Study of the effective filtration method applicability for the control of composite materials stress-strain state

The paper presents the results of experimental studies on the possibility of applying the effective filtration principle in the developing non-destructive testing methods. The presented results make it possible to conclude that the optimal filtration principle can be applied in the further development of methods for determining the absolute values of the stress-strain state of similar objects. It is necessary for its implementation to have impulse responses of similar objects for given stress-strain state values

Study of the effective filtration method applicability for the control of composite materials stress-strain state

The paper presents the results of experimental studies on the possibility of applying the effective filtration principle in the developing non-destructive testing methods. The presented results make it possible to conclude that the optimal filtration principle can be applied in the further development of methods for determining the absolute values of the stress-strain state of similar objects. It is necessary for its implementation to have impulse responses of similar objects for given stress-strain state values

Experimental research of the influence of the strength of ore samples on the parameters of an electromagnetic signal during acoustic excitation in the process of uniaxial compression

Parameters of electromagnetic responses (EMRe) generated during uniaxial compression of rock samples under excitation by deterministic acoustic pulses are presented and discussed. Such physical modeling in the laboratory allows to reveal the main regularities of electromagnetic signals (EMS) generation in rock massive. The influence of the samples mechanical properties on the parameters of the EMRe excited by an acoustic signal in the process of uniaxial compression is considered. It has been established that sulfides and quartz in the rocks of the Tashtagol iron ore deposit (Western Siberia, Russia) contribute to the conversion of mechanical energy into the energy of the electromagnetic field, which is expressed in an increase in the EMS amplitude. The decrease in the EMS amplitude when the stress-strain state of the sample changes during the uniaxial compression is observed when the amount of conductive magnetite contained in the rock is increased. The obtained results are important for the physical substantiation of testing methods and monitoring of changes in the stress-strain state of the rock massive by the parameters of electromagnetic signals and the characteristics of electromagnetic emission

Electromagnetic Radiation Generated by Acoustic Excitation of Rock Samples

The paper presents an experiment on acoustic excitation of electromagnetic radiation (EMR) signals in skarn, sandstone, and magnetite ore samples. For the skarn and sandstone samples, the EMR signal amplitude was observed to decrease with increasing ultimate strength. Supposedly, this effect can be explained by assuming that EMR is generated when an acoustic wave propagates through an electrical double layer. The presence of piezoelectric inclusions (e.g., quartz) in the magnetite ore enhances the analog EMR signal and its spectral components

Interconnection between parameters of rock samples electromagnetic signals and content of magnetite in the samples

The paper describes the results of studies of electromagnetic response parameters of samples of bearing strata and ore rocks from the Tashtagol mine on acoustic effects. Patterns of changes in amplitude-frequency parameters of electromagnetic signals for rock samples with different content of magnetite are experimentally found. The conducted research shows that the maximum amplitudes of electromagnetic signal spectral components increases in samples of the same mineral composition with the reduction of their ultimate strength. This is caused by heterogeneities, and defective areas which contribute to active transformation of mechanical energy into electromagnetic energy. For rocks, which contain magnetite, the emissivity depends not only on heterogeneities and defective areas, but on the quantity of high-conductivity minerals in their composition

Study of interrelation between electromagnetic radiation and rock strength

The paper presents the study of the electromagnetic radiation of real rock samples under acoustic impact. The test samples are made of kerns from the iron ore mine with different petrophysical features and strength. The study has shown that the electromagnetic radiation parameters are related to the sample strength. However, this dependence is not observed for samples with magnetite that can be due to individual structural-textural features and quartz inclusions

Studies of enrichment of sulfide and oxidized ores of gold deposits of the Aldan shield

The paper presents the analysis of studies of the enrichment of sulfide and oxidized ores in Yakutia deposits. The ore of the deposit is a mixture of primary, mixed and oxidized ores. The main useful component of the studied ore samples is gold with a content of 1.5 to 2.8 g/t, the silver content is low – 5-17 g/t. Ore minerals are represented by sulfides, among which pyrite predominates. The total sulfide content does not exceed 3-5 %. The presence in the ore of free and associated gold with a grain size from fractions of a micron to 1.5 mm. Gold is represented by nuggets in intergrowth with sulfides and also forms independent inclusions. Ores are classified as easily cyanidable. It was found that the content of amalgamable gold is 10-49, the share of cyanidable gold ranges from 66.67-91, the share of refractory gold is 9.0-33.33 %, which in absolute amount equals to 0.24-0.8 g/t. The extraction of gold in gravitation concentrate varies depending on the gold content in the ore and the yield of concentrate and for ores with a gold content of 1.5-2.8 g/t from 40 to 60 %. The direct cyanidation of all studied ore samples established the possibility of extracting gold into solution up to 86.7-92.9 %, the gold content in cyanidation cakes is 0.2-0.3 g/t. Investigations of the gravitation concentrate by the method of intensive cyanidation showed that with an initial gold content of ~ 500 g/t, up to 98.9 % is extracted into the solution. The gold content in intensive cyanide cakes will be 6-15 g/t. A set of studies carried out by the authors of the article at various institutes showed that it is advisable to process ore from the deposit using cyanidation technology with preliminary gravitational extraction of gold

Studying electromagnetic signal of rock effected by acoustic impact under uniaxial compression

Physical modeling in vitro is a way to carry out basic laws of mechanoelectric transformations in a rock massive. In this paper we examined how rock mechanical properties influenced on parameters of electromagnetic signals (EMS) excited by the determined acoustic impulse under uniaxial compression. It has been determined that sulphides and quartz in rock samples from the Tashtagolsky iron-ore deposit (Western Siberia, Russia) promote transformation of a mechanical energy to an electromagnetic field energy which is expressed in an augmentation of an EMS voltage. An EMS voltage reduction at the change of the stress-strained state of the sample in the course of an uniaxial compression is observed with quantity augmentation of containing of high-conducting magnetite in rocks. The obtained results are important for a physical substantiation of the method of monitoring of the stress-strained state of rock massive by mechanoelectric transformation characteristics