Mechanical Properties and Microstructure Evolution of Cemented Tailings Backfill Under Seepage Pressure

Cemented tailing backfill (CTB) in underground mine inevitably experiences seepage field, which complicates its mechanical behavior. In this study, the mechanical properties and microstructure characteristics of CTB under different seepage water pressures (SWPs) were investigated. The results show that, with the increase in SWP, the mechanical properties of CTB decrease, but the decreasing trend reduces gradually. Higher SWP leads the microstructure of CTB looser and more porous, and the largest proportion of pores initiated and propagated by SWP is micropores, which means the damage in CTB under seepage is mostly caused by micropores. Besides, the mechanical properties of CTB under seepage decrease exponentially with the increase in porosity and present linearly inverse proportional relation to the pore area fractal dimension. Results above indicate that SWP has a significant deterioration effect on the mechanical properties and microstructure of CTB. The research could not only extend the knowledge of mechanical properties and microstructure characteristics of CTB under seepage but also provide a theoretical reference for mechanical index determination and stability analysis of CTB in water-rich underground mines.

About scientific and practical conference explosives of the Urals

The article reviews the results of the VIII Scientific and Practical Conference with international participation "Technology and Safety of Drilling and Blasting Operations in Surface and Underground Mines of the Urals" which was held at the Ekaterinburg-EXPO Exhibition Center and the Uralasbest Industrial Complex as part of the IX Urals Mining Industry Forum and the URAL MINING' 21 Exhibition dedicated to the Year of Science and Technology in the Russian Federation and the 30th Anniversary of the Urals Mining and Industrial Association. The article also informs about the winners of the Ural Mining Award 2021 and about the research and engineering reports and presentations made during the conference and dedicated to blasting operations. Results are summarized of the visiting seminar at the Uralasbest Industrial Complex, where the Chief Engineer of Promtekhvzvzryv Company N.A. Chistyakov and General Director of the Urals Explosives Association G.P. Bersenev conducted tours to the open-pit mine, the 'Poremit' Plant - the first emulsion explosives production facility in the Urals, a bulk explosives storage, the museum and training center of the Urals Asbestos Mining and Processing Complex. Following the tours of the training center site of the Processing Complex, the second part of the conference was held, during which a number of reports were delivered. Upon completion of the seminar, the Urals Explosives Association awarded honorary certificates and valuable gifts to specialists of the Promtekhvzvzryv Company for their contribution to improvement of drilling and blasting technology and organization of labor on blasting sites. The article is concluded by a summary of the Conference's decisions.

Optimization of the ventilation scheme for increasing production capacity of underground mines

Currently, many underground mines are revising their design solutions to increase their production capacity. This tendency is explained by the decreasing ore grades, as well as by the extensive introduction of mechanization in underground mining operations that has improved the output of mobile equipment by increasing the box capacity and engine power. Dieselpowered mobile vehicles are the most common in underground mining practice. The advantages of such engines are obvious as they generate more power than other types of engines. However, the high air demand for mine ventilation limits their application. This is associated with the need to increase the cross-sections of permanent mine workings in order to comply with the standard air flow rate with account of the increased ventilation capacity along with an increase in the inventory of mobile equipment in order to ensure the specified output of the mine. The specific features of mining operations are defined by the stage-wise character of commissioning various blocks of the deposit. Managing of production and development works provides an opportunity to ventilate the mine sections due to their consecutive commissioning, locally, with an isolated stream of air by means of mine workings that do not have the intersection of air streams. This provides a reduction of critical path of air travel up to 30% and reduction of the general mine ventilating pressure drop by at least 20% at constant air flow rate. The results of the work can be used in designing the ventilation system of underground mines both under construction and in operation.

Designing a Monitoring System to Observe the Innovative Single-Wire and Wireless Energy Transmitting Systems in Explosive Areas of Underground Mines

Suspended monorails are a common mode of transportation for materials and personnel in underground mines. The goal of the EU-funded project “Innovative High Efficiency Power System for Machines and Devices, Increasing the Level of Work Safety in Underground Mining Excavations (HEETII)” is to introduce a single-wire energy transmission system combined with a capacitive-coupling-based wireless transmission system to power the suspended tractor, along with a monitoring system that will monitor the energy network and additional environmental parameters of the mine. Additionally, the monitoring system acts as the wireless communication backbone, allowing for data transmission to surface headquarters, where the data are processed and logged in a central database. This enables operators to detect and take preemptive measures to prevent potential hazards in the mine, improving the overall efficiency of the energy transmission system. This paper describes the additional considerations required for electrical systems in underground mines with potentially explosive atmospheres, as well as the design of the energy transmission system and the monitoring system.

Fuzzy Risk-Based Maintenance Strategy with Safety Considerations for the Mining Industry

Enterprises today are increasingly seeking maintenance management strategies to ensure that their machines run faultlessly. This problem is particularly relevant in the mining sector, due to the demanding working conditions of underground mines and machines and equipment-operating regimes. Therefore, in this article, the authors proposed a new approach to mining machinery maintenance management, based on the concept of risk-based maintenance (RBM) and taking into account safety issues. The proposed method includes five levels of analysis, of which the first level focuses on hazard analysis, while the next three are connected with a risk evaluation. The final level relates to determining the RBM recommendations. The recommendations are defined in relation to the three main improvement areas: maintenance, safety, and resource availability/allocation. The proposed approach is based on the use of fuzzy logic. To present the possibilities of implementing our method, a case study covering the operation of selected mining machinery in a selected Polish underground mine is presented. In the case of mining machinery, fourteen adverse-event scenarios were identified and investigated; general recommendations were also given. The authors have also indicated further directions of research work to optimize system maintenance strategies, based on the concept of risk-based maintenance. Additionally, the discussion about the implementation possibilities of the approach developed herein is provided.

A Mobile Robot-Based System for Automatic Inspection of Belt Conveyors in Mining Industry

Mechanical systems (as belt conveyors) used in the mining industry, especially in deep underground mines, must be supervised on a regular basis. Unfortunately, they require high power and are spatially distributed over a large area. Till now, some elements of the conveyor (drive units) have been monitored 24 h/day using SCADA systems. The rest of the conveyor is inspected by maintenance staff. To minimize the presence of humans in harsh environments, we propose a mobile inspection platform based on autonomous UGV. It is equipped with various sensors, and in practice it is capable of collecting almost the same information as maintenance inspectors (RGB image, sound, gas sensor, etc.). Till now such experiments have been performed in the lab or in the mine, but the robot was controlled by the operator. In such a scenario the robot is able to record data, process them and detect, for example, an overheated idler. In this paper we will introduce the general concept of an automatic robot-based inspection for underground mining applications. A framework of how to deploy the inspection robot for automatic inspection (3D model of the tunnel, path planing, etc.) are defined and some first results from automatic inspection tested in lab conditions are presented. Differences between the planned and actual path are evaluated. We also point out some challenges for further research.

Coordinate Transformation Using the Author’s Software in GIS Class System – Case Study

In order to implement the provisions of the INSPIRE Directive, it is necessary for the Member States of the European Union to take appropriate measures to enable combining in a uniform manner spatial data deriving from different sources and sharing use of them by many users and many applications. Spatial data regarding underground hard coal mining in Poland should also be available in the national spatial reference system. Mining enterprises run a cartographic resource in the different rectangular flat coordinate systems. The standard transformation procedure does not provide the required accuracy because these are areas affected by mining activity, and the stability of points is limited, hence, studies were undertaken. The result is the development of software that can be used in Geographic Information Systems to transform spatial data from a system used in mine to the national system. The article described shortly a chosen coordinates systems used in Polish underground mines, elaborated procedure for selection of the degree and the type of a transformation polynomial in the transformation task. It presents its practical application of procedure for the area of one of hard coal mines using the author’s software elaborated in the results of above-mentioned research.