International Journal of Mining and Mineral Engineering (7 papers in press)
A Stochastic Integrated Simulation and Mixed Integer Linear Programming Optimization Framework for Truck Dispatching Problem in Surface Mines
by Ali Moradi-Afrapoli, Hooman Askari-Nasab
Abstract: Making near optimal and close to reality decisions on the destination of trucks is vital for maximizing the utilization of truck and shovel fleets and subsequently minimizing the operating costs in surface mines. However, currently available truck dispatching algorithms have shortfalls that prevent them from making near optimal and close to reality decisions on the destination of trucks. In this paper, we developed an integrated simulation and optimization framework for solving truck dispatching problems in surface mines. The developed framework uses discrete event simulation modeling to imitate mining operations and capturing technical uncertainties. It also applies uncertainty-based mixed integer linear optimization modeling to dynamically solve truck dispatching problem capturing practical uncertainties. The developed optimization model simultaneously optimizes truck fleet utilization, shovel fleet utilization, and processing plant feed rate. The optimization model considers the stochastic nature of the dispatching parameters and includes travel time uncertainties in the decision-making procedure. We applied the developed framework in a surface mining case study to assess its performance. A comparison between the application of the developed optimization model with a currently in the market optimization model using the developed integrated simulation and optimization framework showed an average of 11% improvement in the production of the case study.
Keywords: Truck dispatching; Surface mining; Fleet management system; Stochastic Optimization.
Prediction of Rock Properties using Grinding Characteristics of Ball Mill
by Ram Chandar Karra, Umamahesh A, Pruthvi Kumar D, Avinash D
Abstract: Knowledge of physico-mechanical properties of rocks is essential starting from the preliminary exploration to processing in mining projects. The strength properties of rocks considered necessary for mine planning and design, method of working, selection of equipment, use of suitable processing technique etc. Sophisticated laboratory facilities are required to determine various properties of rocks using some international standards like ISRM, ASTM etc., which is time consuming and costly affair. In this study, an attempt is made to predict some of the rock properties like density, tensile strength, Protodyakanovs strength index, rebound hardness number using grinding characteristics of ball mill.rnLaboratory experiments were conducted on samples of granite, limestone, slate and BHQ varying different parameters like quantity of feed, charge ratio, size of balls, grinding time etc., at constant RPM of ball mill. Grinding characteristic curves used to obtain 25%, 50%, 80% cumulative passing sieve sizes. In addition, laboratory experiments were carried out to find physico-mechanical properties like density, tensile strength, Protodyakonavs strength index, rebound hardness number. Regression analysis carried out with the data obtained from experiments on samples of granite, limestone, slate and mathematical equations for each property obtained, combining operational factors of ball mill with a good R square value of above 0.9. Experimental data of BHQ used to validate the developed equations. Percentage of error calculated for each equation and equation with least percentage of error for each property chosen as the final predictor equation as shown in the results. rn
Keywords: Rock Properties; ball mill; Characteristic curves,.
Stress distribution and failure characteristics of deep inclined seam and overhead mining along strike longwall floor
by ZHANG Fengda, SHEN Baohong, G.U.O. Wenyan
Abstract: Based on a case study, this paper presents the stress distribution characteristics and plastic zone distribution characteristics of a deep inclined seam and overhead mining along strike longwall (ICMSL) floor by considering the results from numerical simulations, theoretical calculations, and field measurements. The stress distribution characteristics and plastic zone distribution characteristics of the ICMSL before the main roof breaks are analysed by numerical simulation. The theoretical model for analysing failure depth of the ICMSL floor is given. The maximum failure depth of the working face is measured by a water injection test and a stress-strain test. The results show that the vertical taper structure is formed by the roof, the interconnection, and the maingate. The vertical taper structure is formed by the floor, the face, and tailgate. The movement and deformation are mutually restricted by the vertical taper structure, which leads to the stress concentration of vertical stress and maximum shear stress. The maximum failure depth is 20 m, and the failure zone is mainly concentrated in the vicinity of the interconnection and face. The maximum failure depth of the coal seam floor is 21.32 m by theoretical calculation, and between 18.19 m and 20.24 m by in situ field tests, which provide references for the rationalities of theoretical analysis and numerical simulation.
Keywords: overhead mining along strike longwall; vertical taper structure; slip line field theory; failure depth of coal seam floor.
Relationship of Coefficient of Restitution and Damping Coefficient of Rock
by Olaniyi Arowojolu, S.J. Jung, Ahmad M. Abu Abdo
Abstract: When rock travels through an ore pass, it falls, hits other rock materials, and ore passes walls. It is essential to understand the material flow and rock particle interactions in an ore pass to avoid hang-ups and accidents involving rock flow. Part of that understanding is to comprehend how rock reacts when it collides with other particles and other materials. It is difficult to determine the coefficient of restitution and the damping coefficient experimentally simultaneously. The objective of this study was to investigate the relation between the two parameters and determine their correlation mathematically. While it is difficult to measure the damping coefficient of rocks in a laboratory directly, results showed that it could be determined mathematically using the coefficient of restitution. Thus, it facilitates the use of rock flow dynamics simulation programs. Furthermore, the analysis showed that the coefficient of restitution exponentially decayed as the damping coefficient increased.
Keywords: Rock Flow; Ore Pass; Coefficient of Restitution; Damping Coefficient.
Evaluation of blast fragmentation and its benefits: a review of the paradigm and ambiguity
by Shaib Abdulazeez Shehu, Mohd Hazizan Mohd Hashim
Abstract: Wrong blasting can lead to various degrees of inefficiencies in the subsequent mining processes. It is therefore necessary to constantly evaluate blast results and optimize the process. Good blasting provides cheaper benefits when compared to crushing and grinding. Good blast may be expensive but its technical and economic benefits override such an intensive cost. Blast benefits are based on the size distribution of muckpile and the degree of induced microcracks. The size distribution can be visually accessed qualitatively as either good or poor; and quantitatively by screening or different image analysis techniques. However, screening is the only direct and most accurate method of evaluating fragmentation but not suitable for large projects. Though the microcracks can be seen with a specialized microscope but can only be assessed systematically through the study of production output and energy consumption. This paper reviews the benefits, paradigm and the ambiguity of evaluating blast fragmentation.
Keywords: Comminution; Blast geometry; Screening; Muckpile; Fragmentation; Microcracks.
Short-term Underground Mine Planning: A review
by Shahrokh Paravarzar, Yashar Pourrahimian, Hooman Askari-Nasab, Xavier Emery
Abstract: This paper reviews the state-of-the-art in short-term underground mine planning, which is critical for future mining activities. According to the literature, the research is conducted in the categories of mathematical programming optimization and discrete event simulation. Mathematical programming aims at minimizing an objective with the functionality of cost, makespan, deviation from a specific target such as tonnage and fleet management and scheduling. Mining simulation is widely applied in case of short-term mine planning, mostly based on modelling the internal mining process and parameters and on implementing a model for different case studies. A comprehensive review is provided for the aforementioned issues, commercial software packages and programming languages. Finally, research limitations and future area investigation are discussed. The studies reveal a deficiency of research based on the type of mining methods and incorporation of uncertainties.
Keywords: Short-term mine planning; Mathematical modelling; Discrete-event simulation; Optimization; underground mining.
Statistical and Exponential Triple Smoothing Approach to Estimate the Current and Future Deaths of Pakistani Coal Miners from 2010 to 2050
by Niaz Muhammad Shahani, Muhammad Jawad Sajid, Manzoor Ali Brohi
Abstract: Coal mining is considered to be the most dangerous occupation because it includes a large number of accidents and deaths of miners around the globe. Safety actions are essential, specifically in Pakistani underground coal mines considering this problem. This study is carried out an empirical analysis of coal mine fatal accidents in Pakistan from 2010 to 2018. The research focused on the different mathematical aspects of accident categories, events, and fatality rates. The results show that 53 accidents are causing 312 deaths, of which 36% are mine collapse accidents and 51% are fatalities. Likewise, the gas explosion recorded 19% accidents and 17% of deaths, and mine blast recorded 13% accidents and 16% of deaths. The Exponential Triple Smoothing (ETS) test showed steady rise in coal production while steady decline in the deaths of coal miners in Pakistan. The Pakistani coal miner's fatalities per million tons of coal production are expected to fall below zero after 2038.This paper also discusses the appropriate recommendations to solve Pakistani coal mines safety problems.
Keywords: coal mine fatal accidents; coal miner’s fatality rate; coal mine safety management; underground coal mining in Pakistan; Exponential Triple Smoothing.