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By R. Berton, M. Walden, S. Melberg, N. Rocco

Recent tailings dam failures around the globe have influenced many mining industry regulators to reassess their requirements for the numerical modelling of tailings dam failures. This type or forward modelling is associated with overarching uncertainties as the model cannot be calibrated against a physical result. Dam breach analyses that meet the requirements of current industry standards and guidance typically begin with identification of credible failure modes and selection of appropriate topographic data set to represent the study area. The breach parameters and the volume of tailings released are then determined using available methodologies and empirical relationships. Subsequently, when the breach hydrograph is developed and the hydrology of stream networks are complete, the runout simulation is implemented. Due to the uncertainty involved in the process, sensitivity analyses are recommended to quantify variations in model inputs on the inundation extent and the flow characteristics. This paper outlines some common methodologies utilized for development of dam breach models, summarizes associated uncertainties with these methodologies and inputs, and provides guidance on how sensitivity analyses can address a wide array of uncertainties inherent in tailings breach analyses. This paper provides an understanding of how selecting appropriate breach parameters can result in reasonably conservative inundation extents consistent with the identified credible failure modes.

Mar 2, 2022

By M. Fan, A. Hobert, W. van Dyk

Low flotation recovery and selectivity have been long-standing problems in the treatment of most ultra-fine phosphate ores. This paper investigates the improved flotation of two ultra-fine Brazilian phosphate ores from Itafos’ Arraias project. These ores are predominantly composed of quartz, muscovite, apatite and a Ca-Al phosphate. As a result of fine phosphate dissemination and associated grinding requirements, column flotation was selected for the metallurgical test program to address the inherent limitations of fine particle flotation using conventional flotation cells. Accordingly, both benchtop Denver cell and laboratory column flotation tests were conducted to optimize their respective flotation responses. Improved flotation performance was achieved using column flotation as compared to benchtop mechanical flotation. In column flotation, a P2O5 concentrate grade of 30.5-31.0% was yielded at a flotation recovery of 83.7-85.1% for the 38x0µm generated ultrafines. The benefits of Eriez’ column flotation technology realized from this study include a higher degree of selectivity, increased recovery, and reduced collector dosage as compared to bench-scale mechanical flotation.

Mar 2, 2022

By J. Kretschmann, N. M. Smith, J. F. Brune, P. Goerke-Mallet

Coal production and coal use for electric power generation are diminishing worldwide. Germany will phase out lignite mining as well as lignite and hard coal-powered electricity generation by 2038. In the United States, coal production has dropped by more than 50% since 2006, including in key coal production states like West Virginia and Wyoming (EIA 2021). Closing mines and power plants across entire mining regions has significant socio-economic impacts. Existing industries must be focused on the post-mining economy by attracting new industries, and implementing job retraining programs for displaced workers, as former mining regions transition towards agricultural, industrial and recreational use. This paper examines the German “exit from coal” under the 17 UN Sustainability Goals and illustrates the complex procedures, interrelationships, risks, and rewards of the transition towards renewable energy sources, including wind, solar, hydrogen, and bioresources.

Mar 2, 2022

By J. Bickson, C. DeGennaro, J. Homer, M. Girman

Powered haulage and haul truck-related fatal accidents are among the most frequent at surface mines. Industry organizations developed guidance on accident scenarios to address haul truck and mobile equipment collision-related accidents. However, there is a need to investigate accident data to prioritize these scenarios and identify factors relevant to developing validation methods for collision warning/avoidance technologies and determining their capabilities and limitations. Standards and effective validation methods are necessary for improving system efficacy within mining operations and promoting industry adoption. To address these needs, researchers from the National Institute for Occupational Safety and Health (NIOSH) investigated available powered-haulage and machinery-related fatal accident reports documented by the Mine Safety and Health Administration (MSHA). Their objective was to gain a perspective for informing the development of test protocols and validation methods through determining the most prevalent accident scenarios and related factors. Our findings afford insight for addressing the most prevalent haul truck scenarios and relevant factors within U.S. surface mining environments.

Mar 2, 2022

By W. R. Reed, G. W. Luxbacher

As directed by the MINER act of 2006, the NIOSH Office of Mine Health & Safety Research (OMSHR) has annually awarded contracts to enhance mine safety and health. OMSHR has a history of research that focuses on both respirable coal mine dust and respirable crystalline silica (or quartz) dust, and contracts have been awarded since 2010 in support of our intramural research efforts. In 2018, a National Academies of Science consensus study report recommended expansion of respirable dust research. As a result, beginning in 2018 through 2021, eighteen contracts were awarded focusing on this area. These contracts can be grouped in three topic areas: characterization of coal/dust, development of real time monitors, and improvement of respirable dust controls. This paper summarizes the outcomes of completed contracts and the progress of current contracts.

Mar 2, 2022

By O. J. R. Baena, I. C. Sánchez, J. L. G. Guzmán

Frontino, a municipality in western Antioquia, Colombia, has more than 200 years of mining tradition. Currently, mining activities are carried out for lode gold using subway tunnels, where the grinding of the material is done in "cocos", whose energy depends on internal combustion engines and ACPM, environmentally polluting and inefficient methods. In accordance with the Sustainable Development Goals as an initiative developed by the UN, different mining methodologies that are aligned with these are constantly being analyzed. This study proposes to eliminate the use of hydrocarbons in artisanal mining, mainly promoting Sustainable Development Goals 7, 9, 11, 12, and 13. This will be achieved through an energy transition to renewable energy sources that take advantage of the topography and water resources of the area, providing advantages to the communities that live there, such as lighting, electricity for cooking, ventilation for mines, etc

Mar 2, 2022

By Adil Jamali, Taufiq Hidayat, Imam Santoso, Zulfiadi Zulhan, Indah Suryani

The study investigates the segregation of iron and titanium in iron sand concentrate pellets reduced using coal under an isothermal-temperature gradient profile. The results show that metallic iron migrates to the surface while titanium and other oxides move to the center of the pellet. The study provides insights into the reduction process and the behavior of iron and titanium during heat treatment.

Mar 2, 2022

By M. Z. Emad, Y. Majeed, G. Rehman

Massive deposits of rock salt are mined in the Salt Range area of Pakistan. The main export products of rock salt include salt lamps, blocks, and tiles, while local consumption includes the chemical industry and domestic use. The profitable production of salt for value addition depends on the quality, size, and shape of the block. Salt processing for value addition is easier when very few cracks are present in the blocks. The current salt mining practice involves drilling and blasting, which introduces undesired fractures in the material. This paper focuses on the extraction of rock salt blocks by applying conventional cuboidshaped block mining methods used in quarries. The techniques include wedges and feathers, expansion chemicals, and blasting with low-yield explosives. Experimental work involved both laboratory-scale and in-situ field testing. Laboratory experiments assisted with the determination of splitting force, loaddeformation curves, and other rock mechanics parameters. Regression analysis proposes a relationship for the estimation of radial strain from the load in the case of the wedges and feathers method. The splitting force obtained from the laboratory tests was used to confirm the accuracy of the already published empirical relationship. The results of the laboratory as well as in-situ tests showed that the wedges and feathers technique is the most suitable method for mining rock salt blocks of the desired size, shape, while minimizing cracking.

Mar 2, 2022

By H. Schunnesson, H. Fredriksson, D. Johansson, E. Söderström, S. Manzoor, A. Gustafson, M. Danielsson

Fragmentation analysis is an essential part of the optimization process in any mining operation. The costs of loading, hauling, and crushing the rock are strongly influenced by the size distribution of the blasted rock. Several direct and indirect methods are used to analyse or predict fragmentation, but none is entirely applicable to fragmentation assessment in sublevel caving mines, mainly because of the limitations imposed by the underground environment and the lack of all the required data to adequately describe the rock mass. Over the past few years, measurement while drilling (MWD) data has emerged as a potential tool to provide more information about the in-situ rock mass. This research investigated if MWD can be used to predict rock fragmentation in sublevel caving. The MWD data obtained from a sublevel caving mine in northern Sweden were used to find the relationship between rock fragmentation and the nature of the rock mass. The loading operation of the mine was filmed for more than 12 months to capture images of loaded load-haul-dump (LHD) buckets. The blasted material in those buckets was classified into four categories based on the median particle size (X50). The results showed a stronger correlation for fine and medium fragmented material with rock type (MWD data) than coarser material. The paper presents a model for prediction of fragmentation, which concludes that it is possible to use MWD data for fragmentation prediction.

Mar 2, 2022

By M. SIDDARAJU, Rameshwar Sah, Satendra Kumar, Arvind Jaiswal

The study explores a novel process to sinter porous iron ore with improved productivity and quality. The iron ore is pre-processed with calcined lime to temporarily close pores, preventing water absorption during granulation. This enhances reaction kinetics and early slag formation during sintering, resulting in significant improvements in sinter productivity, product yield, and cold strength property.

Feb 28, 2022

By Dongjie Zhang, Fengyu Ren, Xudong Li, Yanjun Zhou, Yang Liu, Rongxing He, Jianli Cao

Based on the limiting-equilibrium analysis of roof processive caving in hanging wall caving method and the critical medium column theory, a new model of subsidence prediction caused by sublevel caving mining method was proposed in this study, considering the drawing influence and the dynamic process of filling granular media. Meanwhile, the distribution rules for lateral pressure with different orebody dip were studied under drawing ore, and subsequently complemented the model. This model indicated that the surface subsidence scope decreased as the unit weight of crack rock and the orebody dip increased. In addition, the height of critical medium column showed a decreasing trend as cohesion of rock mass, the internal friction angle and the unit weight of rock mass. Also, the method of predicting the scope of surface subsidence in the Dabeishan Iron Mine was applied. The results showed that the relative errors are less than 9% and the prediction method could be used in practical application.

Feb 24, 2022

By Setareh Afrouz, Emily Sarver, Cigdem Keles

The resurgence of severe lung disease among US coal miners since the mid-1990s has led to efforts to better characterize and monitor respirable dust exposures, particularly focusing on mineral constituents from rock strata surrounding the coal. A rapid analysis method for silica (quartz) mass using direct-on-filter Fourier transform infrared (FTIR) spectroscopy has been developed, which can also estimate kaolinite, a primary silicate mineral in many coal mines.

Feb 24, 2022

By Jonisha P. Pollard, F. Nasarwanji, Lydia M. Kocher

This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011 to 2017. Hand and finger injuries occur at a rate of 6.53 per 1000 full-time employees, which is nearly double the rate of the next highest affected body part, the back.

Feb 24, 2022

By Fan Yang, Zhiping Wen, Tiancheng Nie, Jinhe Pan, Ruibo Jia, Changchun Zhou

Rare earth elements have important strategic significance and economic value, and the rare earth elements in coal resources have considerable development potential. This study took coal refuse in the Jungar area of Inner Mongolia, China, as the research object, and investigated the occurrence modes of rare earth elements. A special sequential chemical extraction experiment was designed, and the results showed that the rare earth elements in coal refuse mainly occur in silicate and aluminosilicate form, accounting for approximately 65% of the total rare earth elements. According to the results of SEM-EDS, micro morphology of the sample belonged to the lamellar structure of clay minerals, and Al, Si, Fe, S, Y, and La were all present in the sample. Through SPSS software analysis, rare earth elements have an obvious linear positive correlation with Al, Si, and Fe elements, and a negative correlation with S elements. The rare-earth element occurrence mode in coal refuse can provide a definite theoretical basis for the later extraction and enrichment work.

Feb 18, 2022

By Kaixi Jiang, Chaozhen Zheng, Shuchen Qin, Hao Ma, Yufang Wang

The study investigates the behaviors of zinc and iron in neutralized residue during pressure and hot acid leaching. It examines the effects of temperature, acidity, leaching time, and oxygen partial pressure on zinc extraction. The results indicate that the acid to zinc mole ratio is crucial for the extraction process, with a zinc extraction rate reaching 98.0% under optimal conditions.

Feb 14, 2022

By Muhammad Kamran, NIAZ MUHAMMAD SHAHANI

This study elucidates a new idea to predict mine fire levels by employing several machine learning techniques. A total of 120 patterns of various mine fire influencing parameters, such as oxygen, nitrogen, carbon monoxide, and temperature, were compiled from the Adularya coal mine in Turkey. Techniques like t-distributed stochastic neighbor embedding (t-SNE) and k-means clustering were used to process the data, and support vector classification (SVC) was executed to predict various levels of the mine fire. The results revealed that the proposed model has higher credibility to predict the various levels of underground mine fires.

Feb 14, 2022

By H. Jiang, Y. Luo

The study develops an automated, high-efficiency drilling control system to reduce respirable dust and increase energy efficiency in underground coal mines. It uses specific energy to evaluate efficiency and proposes a comprehensive drilling control algorithm based on laboratory tests. The algorithm optimizes drilling parameters to maintain high efficiency, reduce dust generation, and improve safety.

Feb 12, 2022

By QUANWEN PU, Yonggang Wei, Bo Li

The spent catalyst is one of solid waste resources, which contains precious metals with considerable recovery value. However, due to the different compositions of catalyst, the recovery process is difficult. Most of the catalysts are supported by alumina which has good alkali-soluble properties, while platinum is insoluble in alkali. Platinum is enriched by pressurized alkaline solution which is a kind of hydrometallurgical process. The novelty of this study is the separation of alumina and platinum from the spent catalyst and the enrichment of platinum in the solid phase. In this study, a leaching process using NaOH as leaching agent under high temperature and pressure was employed. The effects of alkali concentration, leaching temperature, leaching time, and liquid–solid ratio on leaching efficiency were investigated. The optimum process conditions were determined as follows: alkali concentration of 240 g/L, temperature of 200℃, pressure of 1.20 MPa, time of 1 h, liquid–solid ratio of 5:1. It was concluded that the leaching rate of alumina can reach 99.69%. The content of platinum increased from 0.1749 to 21.12%, the loss of platinum was 3.39%, and the enrichment ratio of platinum increased by 120.82 times. The leaching kinetics of alumina was studied based on the shrinkage core model. The activation energy of alumina leaching is 19.53 kJ/mol, and the leaching process is controlled by chemical reaction. Pressurized alkali solution can not only efficiently leachate alumina from the spent catalyst and enrich platinum, but also reduce the reaction time and increase reaction rate.

Feb 11, 2022

By Emily Sarver, Cigdem Keles, Jonathan Gonzalez

The study re-examines respirable coal mine dust samples using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It finds that SEM tends to overpredict the abundance of dust from rock strata and underpredict coal content, possibly due to coal-mineral microagglomerates (MAGs). The findings suggest that MAGs could be valuable in improving dust controls in mines.

Feb 10, 2022

By RICKARD HANSEN

With vehicles frequently found in underground mines and tyres being a major fuel item, the risk of tyre fires will be severe underground. This study presents an in-depth analysis of tyre fires on mining vehicles to increase the knowledge of the risk, applying data from full-scale fire experiments and CFD simulations. It was found that the wheelhouse of the loader caused an increase in the flame tilt angle of approximately 10%, decreasing the flame impingement and heat flux downstream. The flame temperature of the drilling rig tyre was found to be approximately 7% higher than the loader tyre, increasing the risk of igniting adjacent fuel items. The construction of the wheelhouse/mudguard will contribute to a longer flame length by creating a fuel-rich environment. The CFD simulations predicted higher flame tilt angles for the drilling rig case for higher flow velocities, indicating the influence of a varying wheelhouse/mudguard construction and tyre geometry on the flame tilt angle. The construction of the loader resulted in a flow behaviour, where the short distance to the front mudguard/tyre and the separation of flow directly downstream of the protruding construction led to fire gases being steered past the front mudguard/tyre. In the drilling rig case, the longer distance to the front mudguard/tyre led to fire gases being directed towards the body of the vehicle after passing the area with flow separation. An increased knowledge of the tyre fire risk on mining vehicles and mitigating measures would improve the fire safety in underground mines.

Feb 10, 2022