Application of radio-wave geointoscopy method to study the nature of spreading the solutions in the process of uranium underground leaching

Purpose. Assessment of the effectiveness of using the method of radio-wave geointoscopy of the inter-well space for three-dimensional mapping of the zone of the leaching solution actual propagation in the process of uranium mining by the method of underground leaching. Methods. Experimental-industrial studies of the leaching process are conducted at technological block 68 of the Semizbay deposit (Kazakhstan). In experimental studies, special equipment is used for conducting radio-wave geointoscopy. Inter-well measurements are performed using the RVGI-06 equipment. The observations are conducted in a fan pattern within the filter section. The step between adjacent points along the wellbore is 1 m. At different stages of mining the technological block, maps of geoelectric resistivity have been compiled, with the help of which a comparative analysis is performed. Findings. A tendency to an increase in the area of acidic solutions propagation over time has been revealed by comparing the fragments of RVGI geoelectric map at different stages of mining the block. The influence of a heterogeneous geological structure on the uniformity of the leaching solutions propagation has been proved. It has been determined that the resolving power of the radio-wave geointoscopy method is sufficient to detect changes in geoelectric conditions at small monitoring cycles in time. The spatial-temporal change in the front of the leaching solutions propagation makes it possible to determine the prevailing directions of solutions propagation and to assess the filtration characteristics of rocks. Originality. The patterns have been determined of the leaching solutions propagation over time from the beginning of block acidification to active leaching. The first attempts have been made to use the geophysical well logging method in the practice of uranium mining by In-Situ Leaching (ISL) method. Practical implications. Monitoring studies by radio-wave geointoscopy method at the stage of passive acidification can be re-commended for further experimental and scientific testing at technological blocks of the Semizbay deposit for a quantitative assessment of the filtration characteristics of rocks and the dynamics of the acidification process development, as well as for the development of well-grounded recommendations on the optimal scheme for mining the blocks in specific geotechnical conditions.

Investigation of the Causes of Violations of the Radioactive Balance between Radionuclides of the Uranium Decay Chain

Throughout the literature, it is mentioned that 15 radionuclides in the uranium decay chain have a constant radioactive equilibrium. Theoretical calculations give the value of the activity of each radionuclide in the uranium decay chain.This article examines various factors that affect the coefficient of radioactive equilibrium between radionuclides in the uranium decay chainThe concept of the coefficient of violations of nuclear equilibrium between radionuclides is adopted to determine the degree of violations in the uranium decay chain.Many nuclear-physical factors influence the radioactive balance between radionuclides. The most important of them is the recoil energy that the daughter nucleus receives when splitting from the mother nucleus.Another critical factor in the violation of the radioactive balance between radionuclides is the technological factor: leaching (acid, mini-reagent, bicarbonate, etc.) when leaching uranium by underground leaching of uranium.In addition, as a theoretical result of the study, the article presents a graphical relationship between the number of nuclear masses and the recoil energy of radionuclides in the uranium decay chain.

Physical and Chemical Technologies of Metal Mining and Water Resources

The article is devoted to minimizing the negative impact of mining on the water resources of the mining regions. An assessment is made of leaching technologies with the involvement of non-conventional reserves for traditional methods of mining, reducing costs and lowering the level of environmental impact, including water resources. A reference is given on the use of leaching technologies for the development of natural and technogenic deposits in Russia. The mechanism of contamination of water resources with reagents and products of ore mining and processing is described. The typification of the processes of water migration of substances and components of underground leaching solutions is proposed. The zones of interaction between mineral deposits and water resources are differentiated. Fundamental differences of technology are formulated by the criterion of impact on water resources. An example of preventing the mixing of clean water and industrial effluents by creating a barrier in practice of a mining enterprise is given. It is concluded that the use of technologies with leaching of metals from ores at the place of their localization is promising

Modeling of filtration processes of technological solutions in block underground leaching

PAO “Priargunsky Production Mining and Chemical Association” has been working on reserves of uranium deposits of the Streltsovsky ore field for more than 50 years. During this period, most of the rich ores have been worked out by traditional mining and physical technology. The share of poor and ordinary ores remains significant, but traditional technology does not provide the necessary level of profitability. Therefore, the widespread introduction of physicochemical technology: underground block (BPV) and heap leaching (KV) can be a decisive moment in the continuation of the operation of these deposits. The applied technology of underground block leaching has one significant drawback – a low rate of uranium recovery into a productive solution, which significantly reduces the effectiveness of this technology in the development of poor uranium deposits. To increase the yield of uranium into the productive solution, it is necessary to analyze the entire preparation and leaching process and establish the main reasons for the low rates of transition of uranium to a mobile state. For this purpose, it is proposed to simulate the underground leaching process by building visual models of halos spreading of solutions along shrinked ore mining mass accumulated in an underground chamber. During the simulation, it was found that the distribution of the size classes of the broken ore pieces in the chamber can be predicted at the stage of drilling and blasting operations, and when determining the line of least resistance W and the distance between the ends of the wells, take into account the diameter of the controlled crushing zone R_p. At the same time, 3 zones of granulometric compositions are formed: a re-grinding zone, an optimum zone and a non-carbarite exit zone. The flow of solutions through these zones will differ the more significantly, the higher the height of the chamber. In a zone with larger crushing, an almost steep distribution of the solution spreading front is expected. Accordingly, the smaller the fraction, the lower the front to the horizontal is. The following functions are offered to simulate filtering processes: – it is possible to control the flow of working solutions to the fan of irrigation wells in order to achieve optimal leaching parameters, i.e. to quickly control the process; – knowledge of the law of distribution of irrigation flares makes it possible to select the optimal grid of location of single sprinklers

ENVIRONMENTAL CONSEQUENCES OF URANIUM MINING BY UNDERGROUND LEACHING AND ASSESSMENT OF THE ENVIRONMENTAL INFLUENCE

The article considers the study of the radiation safety of uranium mining enterprises, since in the process of mining and processing of uranium ores a significant amount of radionuclides enter the environment, as well as methods for the absorption of radionuclides using sorbents (bentonites).

Salinization origin of Souf Terminal Complex: Application of statistical modelling and WQI for groundwater management

The natural salinization of Souf sandy Terminal Complex groundwater notably Pontian and Mio-Pliocene has increased four times for the last 30 years, because of over pumping for drinking and irrigation. Application of the multivariate statistical modelling and the Water Quality Index (WOI) to evaluate the groundwater variables have been done, by the investigation of water samples collected from 25 boreholes, in May 2018. Cluster analysis identified three main water types based on the major ionic contents. Factor Analysis and Principal Component Analysis methods confirmed the cluster analysis results. The water groups have sodi-potassic facies which dominate in the western part of Souf, compared to the eastern part and they have generally poor quality. An osmosis phenomenon allowed the homogenization of Pontian and Mio-Pliocene groundwater. The contact of Terminal Complex with the Eocene dolomite and Senonian evaporitic allows introducing a new preferential dissolution corridors concept in which an underground leaching front occurs with the increased pumping. Overlying sandy rocks subsidence can be produced gradually with a rise in the static groundwater level because of the leached underground Senonian evaporitic rocks. Closure of wells intersecting the evaporitic layers and minimizing of pumping from Terminal Complex groundwater in the Southwest part of Souf is strongly recommended, and the groundwater is requiring treatment before supply.

Methodology for Calculating the Stability of the Polymer Operating String in Permafrost

The goal of this paper is to develop a methodology for calculating the stability of an annular cross-section string casing made of polymer material used for the development of mineral deposits by underground leaching in permafrost formations. The aim was to determine the geometric parameters of the casing and to ensure its operational reliability.The relevance of the research is associated with the peculiarities of external influences on the string, for example, a geotechnological well operating in permafrost formation under conditions of additional exposure to ice pressure during freezing of water in the borehole annulus. This effect is usually accompanied by deformation of the casing due to ice pressure, which can lead to string collapse, abnormal operation and the risk of contamination of the geological environment.The proposed calculation method for a polymer casing is based on simulation of objects using the finite element method. We used the spatial finite elements to model the interaction of key elements of the geotechnological natural-technogenic complex: a polymer casing, ice in the annulus space and homogeneous or heterogeneous rock masses adjacent to the well.The results of the study are presented in the form of tables and patterns of displacements, which reflect stresses and strains in the elements of the calculation scheme. The analysis of the obtained results confirms the possibility of using polymer casings of different technological purposes in various conditions of permafrost formation, including extreme ones. The results of the redistribution of pressure created by ice during the freezing of water in the borehole annulus to the rock mass and the string are evaluated. Interdependent deformations of the rock mass and operating string during freezing of water in the borehole annulus are determined. The necessity of considering the properties of the rock mass in determining the pressure on the string is established. The conditions for the collapse of the string with a different combination of its parameters are revealed.