CHINA MINE ENGINEERING

Abstract:Mechanical arms of mining machinery are members with flexible structures that usually have weak rigidity and light damping, so they are liable to unwanted oscillation of low frequency and small amplitude under external interference. During mining, the mechanical arm is vulnerable to forced oscillation by ambient disturbance that is difficult to eliminate through the arm’s structure, resulting in strong impact on mining accuracy and work stability. Magnetic fluid dampers not only are sensitive to oscillation without need for external excitation, but also possess properties of small size, light weight and reliable work performance. They are irreplaceable in damping against oscillation of low frequency and small amplitude for long, straight, flexible members.

Abstract:The Chinese steel industry has been contributing half the global output. However, dependence on foreign iron ore has been restricting the development of the whole industrial chain for a long time. Heavy reliance on imports makes China’s spent on iron ore second only to that for integrated circuits and crude oil in foreign exchange. The lack of self-sufficiency of resources puts a country in a weak bargaining position internationally and further poses risks to national resource security. Based on this fact, China rolled out the “Foundation Plan” and created China Mineral Resources Group to further integrate domestic resources, coordinate the development of overseas resource and enhance industry concentration, in order to increase international competitiveness of the industry and safeguard national resource security.

Abstract:For accurate scope and level analysis of the impact on existing buildings/structures in the ground surface movement zone during cut-and-fill mining, a three-dimensional numerical model was built by integrating 3D Mine, Rhinoceros and FLAC^3D Deformation was simulated by using factors of displacement, stress and plastic zone and stability analysis of surface buildings/structures was conducted combining safety indicators including horizontal strain, curvature and slope. As was indicated by analysis results, plastic failure zone, which was dominated by shear failure, was created around the stope by mining, but it did not reach the surrounding buildings/structures; After mining completion by rational sequence, all buildings/structures remained outside the mining disturbed zone, and all the safety analysis indicators were smaller than the critical deformation allowance. Therefore, it is considered that underground mining will not affect the safety of buildings/structures.

Abstract:Based on the open-pit slope monitoring programme of an iron mine in Anhui Province, open-pit slope stability was studied by combining exploration and simulation, and control measures were proposed herein. Based on SSR method, finite element models were built respectively under natural working conditions, seepage effect and working conditions reinforced with prestressed bolts by use of the COMSOL Multiphysics numerical simulation software. As indicated by study results, the slope was stable under natural working conditions. However, slope stability became poor under seepage effect, with a safety factor of only 1.12, featured by the formation of circular slip, inside to surface, bottom to top. After reinforcement with prestressed bolt, the slope became stable in spite of seepage effect. The research results can provide an empirical reference for the safety management and protection of similar open-pit slopes.

Abstract:The S pit of a copper mine is reused to accommodate acidic wastes. The backfill has reached 525m elevation and is expected to reach a final top elevation of +575m. The waste backfill in S pit produces polluting acidic water. On the eastern slope of S pit,there is a strong aquifer of Quaternary alluvium(Q^apl_h)with a length of about 1500m. Water inflows from Chindwin River and Yawma River into the pit through this layer. Under normal conditions. However, as the level of acidic backfill rises in S pit, acidic waste water will enter the strong aquifer of sand and gravel on the eastern slope by dispersion and seepage after the acidic pit water reaches above the 545m bench, which will contaminate the nearby groundwater, Yawma River and soil. Based on the experimental research of related data, composite liner barrier cutoff wall was proposed in this study for the eastern slope of S pit to stop seepage. The seepage control efficiency of the cutoff wall was simulated in Visul Modflow software and results showed that composite liner barrier cutoff wall could stop pollutants from contaminating groundwater for 100 years.

Abstract:Large-diameter deep-hole open stoping with subsequent backfilling method is often preferred for mining deep and thick deposits, but how to further reduce cutting-mining ratio and improve panel production capacity remains the main technical challenge we face. Taking as an example the large-scale mining in Sishanling Iron Ore Mine, this paper explored the techno-economic feasibility of large lift stoping. Detailed techno-economic comparison was made between 120m lift and 60m lift. As a conclusion, 60m lift was still proposed for the -1020m starter level of Sishanling.

Abstract:The application of 3D visual laser scanning technology in deep softrock roadway is mainly to identify the deformation and failure of wallrock during stoping and eliminate defects of conventional monitoring, including limited amount of measured data, low level of visualization and low utilization rate of data. 3D laser scanning technology was applied to obtain 3D point cloud data of the roadway surface in order to build a 3D visual model of roadway with high precision and high-resolution. Tunnelkey 3D Point Clouds Processing & Analyzing System(TK-PCAS), a 3D point cloud processing software, was adopted to process the point cloud profile data of actual roadway section and roadway design profile data and analyze intrusion beyond clearance limit of roadway; In order to fully master the deformation of steel support in the deformed section, a 3D cloud model of roadway was constructed. Point cloud data of the steel support section were extracted directly for comparison with the steel support section analysis in preliminary survey, so as to quantify the subsidence of steel support and deformation of sidewalls. In order to prove the accuracy of monitoring data, comparative demonstration was made in terms of value and development trend between the monitoring data collected by total station and that by the scanner. The results show that 3D laser scanning technology can accurately and scientifically evaluate the over intrusion of the initial support structure to roadway clearance limit, which offers guidance to the rectification of under-excavated therein; Regarding deformation monitoring, data obtained by 3D scanning technology were generally consistent with conventional monitoring in terms of value and development trend. What’s more, 3D laser scanning technology broke through limitations of conventional single-point monitoring, which made the monitoring information of the roadway more complete in both longitudinal and annular directions with higher visualization. It provides data support for determining the deformation magnitude of wallrock and optimizing roadway support system.

Abstract:In order to solve the problem of concentration drop and low concentration of gas drainage in the bottom drainage roadway through crossing hole, Jiulishan coal mine was investigated for its variation rule of gas drainage by such practice and theoretical analysis was carried out on the reasons for the drop in gas concentration; And based on the floating accumulation theory of CH4 molecule under gravity field and negative pressure drainage theory, a method of secondary sealing to crossing hole was proposed to raise drainage gas concentration. Technological feasibility was analyzed on the concentration increase of secondary sealing to crossing hole that had low gas concentration. Field test was conducted in the 16101 bottom drainage roadway of Jiulishan mine. As was proved by test, the concentration increase technology for holes with low concentration could greatly improve hole drainage concentration. The gas drainage concentration of test drill hole was increased by more than 2 times, with much less mixed volume and higher drainage efficiency, which realized efficient utilization of the drainage capacity.

Abstract:To solve the roof caving of rectangular roadway caused by concentrated stress, a research was carried out based on the haulage roadway at C2316 working face of Anju Coal Mine. By adopting theoretical calculation, numerical simulation and other methods, the reasons for the roadway instability have been found and support measures have been proposed for improvement. The results of the theoretical calculation show that the height of the relaxation zone over the roadway roof is Ls=3m, the width of the relaxation zone on the two sides of the roadway is Le=2.5m, the rock bolts in the original support scheme are not long enough to reach the relaxation zone. Thus, it’s proposed to change the support scheme of the roof from bolt support to anchor cable support, and change the bolt length on the two sides from 1800mm to 3000mm. Site practice shows that the roof-to-floor and side-to-side convergences are 30mm and 28mm respectively, proving the deformation of the roadway surrounding rocks has been effectively controlled and safety production requirement can be met.

Abstract:Kekegai Coal Mine, located in northern Yuheng mining area and on the southern fringe of the Mu Us Desert, introduced drilling method in vertical shaft construction for the first time in the north of the Yellow River. The pilot hole of the shaft reveals that the Quaternary drift-sand formation is up to 61m thick. To ensure safe and smooth construction of the shaft and avoid borehole collapse, freezing method or deep-hole pre-grouting method is generally used, while in this project, the MJS jet grouting method was creatively adopted in the shaft construction, achieving the goal of fast reinforcement of the unconsolidated formation, guaranteeing the construction safety and obtaining good safety and technical effects. The innovative practice has also provided reference for eliminating the hidden danger of collapse in shaft construction using drilling method in Mu Us Desert area. Meanwhile, coal mine construction is an integration of multiple technologies, thus, the latest scientific and technological achievements at home and abroad shall be combined or learned to drive the technological progress of the industry. This practice is a model of cross-industry technical cooperation, it has provided ideas to those safety and technical management personnel committed to coal mine construction for solving the technical difficulties they encountered.

Abstract:As shock wave is formed due to the roof caving in goaf, a research was carried out based on a mine to analyze the two types of roof caving, namely, “inflator” and “surrounding flow”. By analysis, the goaf roof caving was determined to be “surrounding flow” type, the maximum airspeeds caused by block caving and overall roof caving were calculated to be 0.47m/s and 37.77m/s respectively in theory. It was found that the airflow 4m from the edge of collapsed blocks did no harm to human body. The above analysis has provided guidance for addressing goaf roof caving.

Abstract:Horizontal jet grouting technique was used for pre-reinforcement in the geological engineering of a mine. A construction method based on the horizontal jet grouting technique was designed according to the engineering conditions, construction conditions and actual situations. Horizontal jet grouting piles were designed to calculate the main technical parameters of horizontal jet grouting machine, determine the layout of the piles and study the construction process of the machine. The pre-reinforcement effects of the piles were verified based on construction conditions. The monitoring results show that the displacement variation of the engineering is in compliance with associated rules, proving the horizontal jet grouting technique has good effects in reinforcing stratum and supporting surrounding rock structure, and can create a safe and stable construction environment for ming geological engineering.

Abstract:Subject to topography, land acquisition costs and other actual construction conditions, the ventilation shaft of an iron ore mine in China has to be positioned in waste rock accumulations. This unstable and complex stratum poses great challenge to the design and construction of the ventilation shaft collar. Based on engineering geological and hydrogeological conditions at the shaft collar, analysis was made on the difficulties in the design and construction of the shaft collar. Research on the structural type of the shaft collar was carried out by combining the proposed new construction technology. After the shaft wall thickness was confirmed according to the loose body theory, the foundation bearing capacity theory was applied to calculate the number of shaft cribs and determine the structural type of the shaft collar. Considering the complex geological conditions at the shaft collar, some construction suggestions were proposed to provide reference for the preparation of construction organization. The application indicates that the structural design of the ventilation shaft collar is reasonable, reliable and in close combination with site conditions and construction technical scheme, which has provided guarantee for the smooth construction of the shaft collar section, and has certain referential significance for the design and construction of shaft collar under similar wall rock conditions.

Abstract:3D design has been widely used in the architecture and water conservancy industries, but not commonly in TSF design. In this paper, the application of Bentley GEOPAK module in the calculation of TSF storage capacity and damming workload is introduced, and the advantages of 3D design in TSF design are illustrated. BIM concepts has been applied in the field of TSF design. With the development of technology, the concepts of BIM will be implemented in the design, construction, ore drawing, monitoring and other aspects of TSF, forming a simulation management system for the whole life cycle of TSF.

Abstract:A polymetallic ore occurring in Qinghai grades 0.061% Cu, 1.04% Pb, 3.03% Zn and 32.76% Fe, and contains multiple minerals, including galena, sphalerite, magnetite, pyrrhotite, etc. The comprehensive utilization of these minerals is of high difficult. Considering the properties of the ore, the process flow of Cu-Pb bulk flotation-magnetic separation-magnetic concentrate desulfurization-Zn separation from magnetic tailings was adopted, achieving the comprehensive utilization of each composition of the ore. Under laboratory conditions, the Cu-Pb bulk concentrate grading 2.19% Cu and 60.72% Pb, with Cu and Pb recovery respectively as 46.16% and 90.98%, the Zn concentrate grading 45.16% Zn with Zn recovery of 88.94%, and the Fe concentrate grading 66.35% Fe and 0.10% S can be obtained.

Abstract:The copper orebody in Yinshan Mine is mainly composed of finely veined and disseminated ores. The shape, occurrence, thickness, grade and other geological characteristics of the orebody varies along its strike and dip direction. To verify the applicability and reliability of the method, technology and grid used in the recent exploration work, a production exploration was carried out based on the recent exploration by densifying the exploration grid, and the geological characteristic parameters obtained were compared with the geological exploration outcomes. The comparison results show that the exploration method is applicable, the quality is reliable, and the characteristics of the orebody has certain change after the exploration grid is densified; exploration management and comprehensive research should be further strengthened in actual mining process.