Mineral Formation under the Influence of Mine Waters (The Kizel Coal Basin, Russia)

The development of coal deposits is accompanied by negative environmental changes. In the territory of the Kizel coal basin (Perm Region, Russia), the problem of contamination of water sources by acid mine waters and runoff from rock dumps is particularly acute. Mine waters are acidic (pH 2–3), with high mineralization (up to 25 g/L) and significant content of sulfate ions, iron, aluminum, manganese, toxic trace elements (As, Co, Ni, Pb and Zn). They are formed as a result of the interaction of underground waters from flooded mines of the Kizel basin with coal and rocks of dumps with high sulfur content (15%). Uncontrolled inflow of mine water into rivers (about 22 million m3 annually) leads to significant amounts of iron and aluminum hydroxide precipitation. These precipitations are in active interaction with river water, polluting the rivers tens of kilometers downstream and are entering the Kama reservoir. Studies of alluvial precipitation can be considered as a method of control and predictors of technogenic water pollution. The mineral composition of river sediments was studied with the application of different methods, including studies of sand-gravel and silty-clayey sediments. The sandy-gravel grains in the bottom load are mainly composed by natural minerals and are represented by a significant number of particles of coal dumps, slags and magnetic spherules. The silty-clayey material, mixed with natural minerals, contains a significant number of amorphous phases with a predominance of iron-rich substances, which may actively concentrate toxic elements. The presence of jarosite, goethite, basaluminite, lepidorocite and copiapite in silty-clayey sediments are indicators of the influence of mine waters.

Hydrogeology of the Kizel coal basin (Western Urals, Russia) in post-mining stage: the main problems and ways of their solution

Coal mining in the Kizel coal basin was accompanied by intensive mine drainage, drainage of both coal strata and hydraulically associated rock aquifers, the formation of extensive depression craters in the areas of worked mines, the movement of large masses of rocks, the formation of sinkholes over the worked space. These processes have led to significant changes in the filtration characteristics of aquifers and groundwater supply conditions compared to natural conditions. After the dewatering was stopped, 19 outflows of acid mine waters were formed, which are a source of pollution of the hydrosphere. To select engineering measures aimed at improving the environmental situation, it was necessary to assess the balance components involved in the formation of these outflows. The necessary accuracy of the forecast in assessing the balance components of water involved in the formation of outflows both at the present time and in the implementation of engineering measures can be achieved by reproducing the methods of mathematical (geofiltration) modeling of the hydrodynamic history of mining. Groundwater in the Kizel coal basin is formed within several relatively isolated basins of underground catchments. To determine the external boundaries of the models, an approach based on the analysis of the geological, tectonic structure of the territory, filtration properties of rocks, taking into account the geomorphological position of the basin, was used to ensure the correct interface of the boundaries of local models. On the basis of the analysis of long-term data of regime observations at working out of coal mines, generalization of geological and hydrogeological information the substantiation of basic parameters of 8 geofiltration models is executed, external and internal boundary conditions are defined, stratification of each of models is carried out. The value of the infiltration feed for the territory under consideration was taken on the basis of estimates made in different years in the study of the natural regime of groundwater, in the operation of the mine drainage and the analysis of the outflow costs after flooding. The effectiveness of engineering measures was evaluated by analyzing the changes in the balance components of water involved in the formation of spills at the present time and in the implementation of measures, which were considered as plugging wells and mine shafts, the device of bridges in mine workings, injection of reagent into the underground space, removal of surface runoff, pumping groundwater upstream.

Analysis and Feasibility of Measures to Minimize the Impact of Acid Mine Waters Discharged by Abandoned Copper-Sulphide Mines on Hydrosphere of the Tagil River

Mass closure of copper-sulphide mining sites both in the Sverdlovsk Region and worldwide resulted in the emergence of environmental challenges. One of such challenges is generation and discharge of acid mine waters. Manmade and natural factors have their impact on chemical composition of mine waters due to activation of sulphides oxidation processes taking place in disturbed rock mass and mines. Concentrations of components in treated mine waters are much higher than MAC (dozens and hundreds of times for iron, copper and zinc). That results in pollution of hydrosphere which goes on for decades and spreads over large distances along rivers. Quite a few reasons cause environmental degradation of hydrosphere in old industrial districts. These are baseline amounts of metals in the hydrosphere, low rates of self-rehabilitation of dead pits, high amounts of acid waters, high amounts of contaminants in mine waters, imperfection of treatment systems. Given the demand of mine waters treatment over decades, improvement of existing treatment systems and implementation of new technologies are required.

Research of migration of technogenic bottom sediments with application of modern geoinformation systems

The study of the regularities of formation and migration of technogenic bottom sediments in river ecosystems of mining regions is an urgent area of works of domestic and foreign researchers in connection with the high need to reduce the anthropogenic impact on the natural components of the environment. This article is devoted to the problems of the migration of pollutants and the formation of technogenic bottom sediments in river ecosystems in the Kizel coal basin (Perm Region, Russia). The scale of the problem is determined by the existence of numerous sources containing extremely high concentrations of elements of the 1st, 2nd and 3rd hazard classes. The main sources of contaminants on the study area are acid mine waters discharged through former mines and springs, as well as effluents from waste dumps. These technogenic solutions are characterized by a multicomponent composition, in which high concentrations of the following elements (Fe, Al, Mn, Zn, Be, Cu, Pb, Cd et al.) are noted. Exceeding the MPC for some elements reaches hundreds and thousands of times; in all, according to various estimates, over 500 km of rivers are polluted in the territory of the former Kizel coal basin and in the zone of its influence. The article describes the characteristics of bottom sediments of the river Kos’va, one of the largest regional rivers, according to long-term observations from 1984–2018, field studies, as well as the use of GIS technologies and the created geo-ecological geoinformation system of the Kizel coal basin. Also, based on international experience, environmental measures were proposed to restore the river ecosystems of the territory.

Elaboration technology of selective processing of acid mine waters of copper-pyrites complex mining plants

The actuality of elaboration technology of processing of acid mining waters of copper-pyrite deposits is stipulated by necessity to increase nature resources utilization efficiency. Implementation of it will allow to decrease the dead-weight losses of manganese, copper, iron and other metals. The developed technology includes a complex of sequentially executed processes. At the first stage extraction of Cu2+ ions by cementation is done, at the second stage extraction of Fe2+ and Fe3+ ions in the dispersed phase is done by acid-base deposition. At the third stage extraction of Mn2+ ions is done by transferring Mn2+ ions under the action of an oxidizing agent in insoluble forms of manganese and the subsequent extraction of the dispersed phase by the electro flotation method. The developed technology was tested on the acidic underspoil waters of the mining enterprises in the Ural region. The obtained practical results of the developed technology implementation have shown that, the technology introduction will make it possible to obtain copper, iron and manganese in the form of commercial products with a simultaneous decrease in their concentrations in adjacent water bodies to the maximum residue limit (MRL) standards. The developed technological recommendations for the manganese extraction from acid mine waters allow selective extracting manganese in the form of a flotation concentrate, with a manganese content of up to 50.1%. The resulting manganese concentrate can be used as feedstock in various metallurgical operations. The technology is simple, it can be used without applying complex expensive equipment both independently and within a system of existing treatment facilities.