Proposed Mining Method Research Articles

Research into Impact of Leaving Waste Rocks in the Mined-Out Space on the Geomechanical State of the Rock Mass Surrounding the Longwall Face

Backfilling technology is not always used by mining enterprises, which is conditioned by technological and economic factors, such as the need for high mining rates and costs for the technological processes of transporting backfill materials from the daylight surface to the mined-out space. This concerns the underground mining of hard coal, which is a strategic energy resource, in the mines of Ukraine. This paper aims to study the effect of leaving the waste bottom rocks in the mined-out space of the longwall face without their drawing to the earth’s surface on the geomechanical state of the rocks surrounding the longwall face. The geomechanical assessment of the stress state of the rock mass surrounding the longwall face, when leaving the waste rocks from the seam bottom rocks in the mined-out space, is performed by the finite element method using the Ansys software package. A geomechanical model has been developed and substantiated, which adequately reflects the mining-geological conditions for seam mining within the extraction site, the actual structure and properties of the coal-bearing rock stratum, the parameters of the longwall face and the modified powered support for the processes of leaving the rocks in the mined-out space. The values and patterns have been determined of the decrease in the stress intensity concentrations in the coal-bearing roof mass in the frontal bearing pressure zone and destressing zone with an increase in the ratio of the rock pack thickness to the extracting seam thickness. The relative indicators of the load on the powered support section and the lowering of its roof have been determined by the ratio of the thickness of the rock pack formed in the mined-out space to the extracting seam thickness. The proposed mining method is of significant commercial and research interest for owners of coal mines developing thin coal seams because environmental costs for placing waste on the surface are reduced, and the energy potential of coal is increased due to the separation of waste rocks from coal in underground conditions. The need for a cycle of beneficiation of mined mass is eliminated and the geomechanical conditions of coal mining processes are improved.

An Association Rule-Based Multiresource Mining Method for MOOC Teaching.

The selection of MOOC teaching resources is influenced by diversified resource positioning methods, which leads to low index efficiency of resource mining. Therefore, this paper proposes a multiresource mining method based on association rules to collect the learning behavior data of MOOC users and establish the MOOC teaching resource warehouse. Aiming at the attribute set of information association positioning, the association rules of teaching resources are designed. In addition, the association rules are combined with the shortest path scheduling scheme of teaching resources to establish the location and mining of diversified MOOC teaching-associated resources. Finally, the clustering method is used to process the results of teaching resource mining and complete the clustering of diversified teaching resources. Experimental results show that the index time required by the proposed mining method is 0.1 s, which is only 1/6 of other resource mining methods.

Improvement of Continuous Lateral Surface Mining Method for Coal Extraction from Closed Mines’ Pillars

The presented paper deals with a continuous lateral method of closed mines' coal pillars surface mining and its advantages in land intensity, dust emissions, maximizing coal extraction, and overburden transporting costs. While inclined and steep coal seam strata in the pillars are widely exploited with land-and-cost intensive deepening longitudinal mining method, this article substantiates the choice of modification of block-and-layer continuous lateral mining method for different kinds of coal deposits. The aim of the study is to specify the modifications of the method proposed, define the stages of their carrying out, and emphasize the advantages over deepening longitudinal method of coal pillars surface mining. The basic principle of the proposed continuous lateral method of mining the coal pillars is limiting the final depth of quarry by the vertical height of the first floor of the underground mine workings. The continuous lateral mining method is detailed in the article in three modifications (for development coal seams strata of high and medium thickness, as well as distanced separate coal seams), which advantages are low land intensity and dust emission from the dump. Attention is also paid to the economic benefits of the block-and-layer continuous lateral method of mining coal pillars of closed mines, whereby the overburden transporting costs can be significantly reduced, while limitations of the proposed mining method concern specific sites of closed mines that make up a small part of the coal pillars extracted by surface mining today.

In situ fluidized mining and conversion solution to alleviate geological damage and greenhouse gas emissions due to coal exploitation: A numerical analysis and evaluation

AbstractCoal remains a primary energy source for the foreseeable future. However, existing approaches for coal exploitation and utilization are highly detrimental to the geological formations from which they are extracted and the atmospheric environment. Moreover, underground mining can induce earthquakes that lead to fatalities and financial losses. The demand to abandon coal mining is increasing worldwide, and the need for efficient, safe, and environmentally acceptable coal exploitation and utilization has garnered widespread attention. We propose a novel unmanned automatic machine‐based mining and in situ conversion method for the safe and clean exploitation and utilization of subsurface coal resources. Solid coal is transformed in situ into fluidized energy resources using this method. To evaluate its effectiveness, a geological model of a coal mine was generated, and a numerical simulation based on the continuum‐based discrete element method was conducted to compare the mining‐induced stress distribution, roof subsidence, coal wall failure, and microseismicity for fluidized and traditional mining methods. Our results indicate that the proposed mining method can significantly reduce damage to the geological formation and greenhouse gas emissions associated with the exploitation and utilization of coal resources. We also discuss the limitations of the current study and future research possibilities.

Studying the Appropriate Underground Mining Methods in Sukari Gold Mine

This paper represents an attempt to study mining methods and development in the area of underground mining in Sukari gold mine. Detailed mining and rock mechanics data had been collected from Sukari gold mine to select the appropriate mining method for underground area. Underground mining methods have been studied to show that the selected mining method in SUKARI gold mine is suitable for the geology of the ore body, and hence proposed mining method could be taken into account. A brief background about Sukari gold mine is given and the used mining method in Sukari gold mine has been approved. Some of the suitable mining methods are discussed according to selection method and the most appropriate one is listed. Mining method selection was done by UBC method and Hartman flow chart.

Data mining to effect of key alloying elements on corrosion resistance of low alloy steels in Sanya seawater environmentAlloying Elements

In this paper, the relationship model between seawater environment, chemical composition and corrosion potential of low alloy steel is established and the distribution of corrosion potential of low alloy steel with changes in key alloying elements is excavated. The research was carried out with the following steps: Firstly, the relationship model between corrosion potential of low alloy steel and its influencing factors was established by data dimension reduction and artificial neural network (ANN). Secondly, key alloying elements of experimental steels were selected out by Pearson correlation analysis, then the corrosion resistance element model was visualized to show the effect of key alloying elements on corrosion potential of low alloy steel. Finally, corrosion potential of low alloy steel with the change of key alloying elements was classified and visualized by classification method. The mining results can reflect the validity of the proposed mining methods to a certain extent and provide an intuitive data basis for the development of high-quality and low-cost low alloy steels.

Characteristics of Roof Ground Subsidence While Applying a Continuous Excavation Continuous Backfill Method in Longwall Mining

Activities of traditional longwall mining will result in ground subsidence and therefore cause issues such as damages to buildings and farmlands, water pollution and loss, and potential ecological and environmental problems in the mining region. With advantages of the longwall backfill mining method, as well as the room and pillar mining method, a continuous excavation and continuous backfill (CECB) method in longwall mining is recommended to effectively control the ground subsidence. In this method, mining roadways (MRs) are initially planned in a panel, and then they are excavated and backfilled in several stages until the whole panel is mined out and backfilled. According to the geologic conditions of an underground coal mine, and the elastic foundation beam theory, a mechanical model was built to study the subsidence of the roof while using this new mining method. In addition, methods to calculate roof subsidence in various stages in CECB were also provided. The mechanical parameters of backfilling materials, which were used in the theoretical calculation and the numerical analysis for mutual check, were defined through analyzing the stability conditions of the coal pillars and the filling bodies. The control effect for the ground subsidence of using the newly proposed mining method was analyzed based on both simulation results and site monitoring results, including the ground subsidence, horizontal displacement, tilt, curvature and horizontal strain. This research could provide suggestions to effectively control ground subsidence for a mine site with similar geologic conditions.

Rating and Comments Mining Using TF-IDF and SO-PMI for Improved Priority Ratings

Data mining technology is frequently used in identifying the intention of users over a variety of information contexts. Since relevant terms are mainly hidden in text data, it is necessary to extract them. Quantification is required in order to interpret user preference in association with other structured data. This paper proposes rating and comments mining to identify user priority and obtain improved ratings. Structured data (location and rating) and unstructured data (comments) are collected and priority is derived by analyzing statistics and employing TF-IDF. In addition, the improved ratings are generated by applying priority categories based on materialized ratings through Sentiment-Oriented Point-wise Mutual Information (SO-PMI)-based emotion analysis. In this paper, an experiment was carried out by collecting ratings and comments on “place” and by applying them. We confirmed that the proposed mining method is 1.2 times better than the conventional methods that do not reflect priorities and that the performance is improved to almost 2 times when the number to be predicted is small.

Waste rock filling in fully mechanized coal mining for goaf-side entry retaining in thin coal seam

A large amount of waste rock is generated during thin seam coal mining operations underground. The waste rock material stacked on surface also adds to the environmental pollution. So it is important to reduce the amount of waste rock by exploring gainful utilization methods. This paper deals with an investigation undertaken to develop an alternate gob filling material in laboratory and evaluating its efficiency numerically as well as in field. A coal–waste rock separation system and a roadway layout system were designed, and a new technique of fully-mechanized goaf-side entry retaining and goaf filling back hydraulic supports was proposed. These methods helped realize the goal of green mining, which was featured by waste rock consumption in nearby region without any need to be elevated to ground surface. This study demonstrated that the two proposed mining methods, namely, caving mining method and mining with filling method, differed in mechanical environments where roadside filling body was located, deformation, and failure scope. The maximum principal stress concentration degree near the roadside filling body for caving mining method was high with a maximum value of 42.5 MPa because of key rock blocks in overburden. As a result, the surrounding rock of roadside filling body was severely deformed with a maximum displacement of 1117 mm. The entire roadside filling body moved toward the inside roadway and experienced plastic failure. After goaf filling, filling bodies in goaf, roof and floor strata, and roadside were combined to form an entire withstanding deformation. The motion space of overburden rock was limited, the adjustment range of surrounding rock stress near the roadside filling body was narrowed, the maximum principal stress decreased to 29.5 MPa, and the main roof did not rupture. Accordingly, the deformation of surrounding rocks of the roadside filling body was small, the maximum displacement of roof and floor was 457 mm, and the roadside filling body did not experience plastic failure. The study results enrich goaf-side entry retaining theory in thin coal seam and mechanized filling technology and provide a theoretical foundation for thin coal seam mining with difficulty in waste rock treatment.

Design principles and key technologies of gob side entry retaining by roof pre-fracturing

This study investigates gob side entry retaining by means of roof pre-fracturing. Based on short cantilever beam theory, the entry roof was pre-fractured from gob roof via orientated blasting. The gob gangue was then blocked and used as one side wall of the retained entry. The blasting hole length relied on site geological conditions, and a design method was formulated. Yieldable cable bolt anchored into stable overlaying strata is one key technique to stabilise the entry roof under double dynamic pressure. For the gangue management I-steel and retractable U-steel formed frameworks were investigated with regards to varying seam thicknesses. A real-time remote monitoring system was developed and used to investigate surrounding rock mass deformation of the proposed retaining method and to provide early warning for mining safety. We present two working cases to show the applicability of the retaining method under different geological conditions. Field monitoring reveals that the periodic weighting loads decreased at the working face after roof blasting. The entry roof and gangue wall became stable after the working face passed a certain distance. Our proposed mining method provides an innovative approach for mining safety and economy.

Numerical investigation of load shedding and rockburst reduction effects of top-coal caving mining in thick coal seams

By comparing the overburden structure characteristics and the distribution of stresses around roadways and coalfaces in slice mining and top-coal caving mining in thick coal seams, this study analysed the effects of the two mining methods on rockburst prevention. Furthermore, by using FLAC3D numerical simulation, this research studied the distribution of surrounding rock stress in the first mining panels, subsequent panels, solid coal roadways, and gob-side roadways and the influence of parameters including mining height, bottom coal, and coal seam thickness on stresses in the surrounding rocks. On this basis, the effects of load shedding and rockburst reduction of top-coal caving mining of thick coal seams were summarised and verified through field investigation. The results show that compared with slice mining, overburden structures in top-coal caving mining of thick coal seams weakened the stress concentration in surrounding rocks, resulting in lower peak values but wider ranges of advanced abutment stress and side abutment stress in panels. The point of peak stress was observed deeper into the coal masses. With the increase of mining height and the decrease of bottom coal thickness, the stress concentration around roadways and coalfaces decreased rapidly and then tended to be stable. Therefore, top-coal caving mining can reduce the stress concentration around roadways and coalfaces to decrease rockburst risk. While mining thick coal seams, top-coal caving mining needs to be conducted preferentially over a reasonable range of mining heights. Field practice in Xing’an and Junde mines revealed that the top-coal caving mining induced a lower rockburst frequency, over a smaller range and with lower intensity, which validated the effects of load-shedding and rockburst reduction of the proposed mining method.

A Data Mining Approach to Analyze Occupant Behavior Motivation

Occupants’ behavior could bring significant impact on the performance of built environment. Methods of analyzing people’s behavior have not been adequately developed. The traditional methods such as survey or interview are not efficient. This study proposed a data-driven method to analyze the occupants’ behavior, supported by a specific case of analyzing people’s adjustment to ventilation system in a Dutch community. In the individual level, to analyze the motivation of a single person, a logistic regression based approach was proposed to classify occupants’ behavior of increasing/decreasing the ventilation flowrate and then reveal the motivations behind. In the community level, the behavior motivations derived from different occupants were compared. Three motivational behavior patterns, namely the environment-driven type, the time-driven type and the mixed-type were summarized. The proposed mining method is useful to discover and develop occupant behavior models.

Bench mining utilizing manual labour and mechanized equipment - a proposed mining method for artisanal small-scale mining in Central Africa

Bench mining utilizing manual labour and mechanized equipment - a proposed mining method for artisanal small-scale mining in Central Africa

Efficient frequent pattern mining based on Linear Prefix tree

Outstanding frequent pattern mining guarantees both fast runtime and low memory usage with respect to various data with different types and sizes. However, it is hard to improve the two elements since runtime is inversely proportional to memory usage in general. Researchers have made efforts to overcome the problem and have proposed mining methods which can improve both through various approaches. Many of state-of-the-art mining algorithms use tree structures, and they create nodes independently and connect them as pointers when constructing their own trees. Accordingly, the methods have pointers for each node in the trees, which is an inefficient way since they should manage and maintain numerous pointers. In this paper, we propose a novel tree structure to solve the limitation. Our new structure, LP-tree (Linear Prefix – Tree) is composed of array forms and minimizes pointers between nodes. In addition, LP-tree uses minimum information required in mining process and linearly accesses corresponding nodes. We also suggest an algorithm applying LP-tree to the mining process. The algorithm is evaluated through various experiments, and the experimental results show that our approach outperforms previous algorithms in term of the runtime, memory, and scalability.

Mining Web navigation patterns with a path traversal graph

Understanding the navigational behaviour of website visitors is a significant factor of success in the emerging business models of electronic commerce and even mobile commerce. However, Web traversal patterns obtained by traditional Web usage mining approaches are ineffective for the content management of websites. They do not provide the big picture of the intentions of the visitors. The Web navigation patterns, termed throughout-surfing patterns (TSPs) as defined in this paper, are a superset of Web traversal patterns that effectively display the trends toward the next visited Web pages in a browsing session. TSPs are more expressive for understanding the purposes of website visitors. In this paper, we first introduce the concept of throughout-surfing patterns and then present an efficient method for mining the patterns. We propose a compact graph structure, termed a path traversal graph, to record information about the navigation paths of website visitors. The graph contains the frequent surfing paths that are required for mining TSPs. In addition, we devised a graph traverse algorithm based on the proposed graph structure to discover the TSPs. The experimental results show the proposed mining method is highly efficient to discover TSPs.

Exploration drilling optimisation using geostatistics: a case in Jharia Coalfield, India

Drill hole optimisation using geostatistics has been used in many parts of the world in respect of various mineral deposits including coal. The present paper is an attempt to provide a means to maximise the information to cost ratio for optimisation of exploration drilling in the Jharia coalfield, which is the only source of prime coking coal in India. Exploration in Jharia Coalfield that has led to the generation of a huge exploration database has been carried out by various governmental and non-governmental agencies. But because of lack of importance and an obvious application towards exploration modelling, the database had not been utilised to its fullest extent. In the present study, an attempt has been made to derive geostatistical models of various proximate coal constituents of selected seams in respect of nine opencast mine blocks of the coalfield. This experimental study, employing geostatistical volume–variance relationships, revealed that an exploration grid density of 16 drill holes per square kilometre with a grid spacing of 300 × 300 m within an exploration area of 1 × 1 km is adequate for maximisation of information in respect of the Jharia Coalfield. Until now, the density of exploration drilling in the coalfield has been considered as per Indian Standard Procedure (ISP) norms solely based on past experience and proposed mining methods. The present study of exploration drill hole optimisation using the concept of kriging variance is associated with an objectively defined mathematical basis and therefore may be applied for exploration optimisation in other coalfields in India and other countries, which occur in similar geological settings.

Automatic discovery of rules for predicting network management events

In order to discover behavior patterns, current algorithms only analyze historical data in terms of performance data or fault events, ignoring the temporal correlation among different types of information, including the configuration changes. A method is presented that can discover recurrent patterns from multiple flows of events, such as alarms and configuration events, as well as discrete information, such as traffic and usage, taking into account static and dynamic information concerning observed objects and their environments. This method can filter out theoretically useless patterns, using a novel technique for detecting chaos in sequences of events. The prediction accuracy of the discovered patterns has been measured using objects with dynamic behavior controlled by known and complex differential equations. The proposed mining method has been used for discovering and predicting alarms in a computer network composed of several Internet servers taking into account the alarm and configuration events history, as well as static information about these servers.