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By Kenneth J. Reid, Marian S. Stachowicz

A preliminary evaluation of a new in-stream particle size analyzer has been carried out using materials obtained from a taconite plant in Northern Minnesota. Results are reported for bench scale, pilot scale and full scale tests, the latter being carried out in a taconite plant concentrator. The unit employs a novel scanning laser microscopy principle and details of the equipment configuration and operating principles are presented and discussed. Data acquisition is via an eight channel digital electronic system and particle counts are collected on the basis of reflected light pulse time intervals which are a direct measure of particle size. Output is available as an eight point individual or cumulative size distribution or as computed averages. The practical aspects of sample point location and flow requirements for reproducible results are outlined and discussed.

Jan 1, 1990

By Aydin Shaterpour Mamaghani, Bilgin. Nuh, Engin Dogan, Tayfun Erdogan

"Improved safety and more environmentally friendly operation are basic advantages of mechanical excavation over the drill and blast method. Raise Boring Machines (RBMs) are one of the types of these machines which have recently been increased use in Turkey. The excavated hole with RBM is more stable than other methods and has better air flow, making it ideal for ventilation shafts. This paper is a summary of the performance of a RBM in the Balya PB-Zn Mine in Turkey. Length and diameter of the ventilation shaft are 200 m and 2.4 m, respectively. The geological and geotechnical characteristics of the strata excavated in the mine are first given and later the validity of a model developed to predict the machine performance is discussed. It is believed that the results of this study and the model given to estimate the performance of the RBM will be useful guide for future applications. INTRODUCTION Raise boring technology was developed to meet the demands of the mining industry, but has also found numerous applications in tunneling or infrastructure projects for ventilation purposes. Raise boring machine uses a small diameter drill rod, around 230-350 mm to drill a pilot hole down to the required depth up to around 2000 m. Once the pilot hole has been drilled to the desired depth, a reamer of up to 9 m diameter is attached to the drill rod. The reamer is then pulled back up to the upper level, creating a round shape. Continues operation provides a faster advance rate than other methods. RBMs are suitable both in hard and soft rock. The flexibility in different angles and diameters is a great advantage compared to drill and blast excavation method. RBM creates a shaft with smooth walls which usually does not require lining. The hole is more stable than a drilled and blasted method and has better air flow, making it ideal for ventilation shafts. Raise boring is convenient method in competent rock; however several problems are faced in geological formations where geological discontinuities are dominant. Moreover, assembly and disassembly time may be long in some cases. The performance and operational parameters of the excavating machine should be predicted prior to starting the excavation operations in order to fulfill the economic requirements of the project. In the light of this fact, the main objective of this investigation is to summarize a case study on raise boring machine performance and suggest a new model based on laboratory test results. First, general description of the mine and project are provided. Then, the physical and mechanical characteristics of the samples taken from project area are discussed. In the third section, performance and operational parameters of RBM are investigated to understand the machine behavior in different rock characteristics and also to collect a useful database for further investigation. In the fourth section, a new model for performance estimation of RBM are recommended."

Jan 1, 2016

By L. M. Petrie, D. C. Marozas, S. E. Paulson

The US Bureau of Mines (Bureau) is conducting research to evaluate the potential for developing an in situ leach mining process that will selectively extract manganese from oxide ores, leaving gangue relatively undisturbed. To accomplish this, a geochemical approach based on deposit-specific information, such as mineralogy and geology, is used to constrain the operating parameters of the system. Among the studies being conducted are: • leaching experiments to define reaction mechanisms and kinetics, • detailed petrologic characterization at the microscopic scale to assess manganese distribution and leaching efficiencies, • deposit characterization and evaluation, and • development of potential manganese recovery schemes. Data from these studies are being used to develop engineering design information for an in situ mining process. Specific details of the Bureau's research project are discussed, including results obtained to date.

Jan 1, 1993

By J. Paraszczak

Water-powered jackleg rock drills, introduced recently in South African mines, are reported to be more efficient, faster and more comfortable to operate than conventional pneumatic drills. Comparative testing of these drill types was performed in Quebec. Based on the test results and on time studies performed in the mines, water-powered drilling was reviewed. The review considered the drilling rates achieved, the infrastructure needed, side effects and health and safety considerations. This study shows that the application of water-powered drills may, under specific conditions, help increase the footage drilled and may improve the working environment. Examples of such applications are presented in the conclusions.

Jan 1, 1997

By J. Paraszczak

Water-powered jackleg rock drills, introduced recently in South African mines are reported to be more efficient, faster and more comfortable to operate than conventional pneumatic drills. A comparative testing of both drill types was performed in Quebec. Based on its results and time studies done in the mines, water-powered drilling has been reviewed with regards to drilling rates achieved, infrastructure needed, side effects, health and safety considerations. This study shows that the application of water-powered drills may help increase footage drilled and improve working environment, but under specific conditions. The examples of such applications are given in the conclusions.

Jan 1, 1995

By Yongheng Jiang, Wentong Wang, Haoming Luo, Chuanju Liu, Qianjun Zhang, Sha Guo

Rock burst has always been a major problem in deep underground engineering with high stress, and rock burst strength evaluation has become an important research topic. To effectively predict the rock burst hazard in underground rock mass engineering, a cloud model (CM) rock burst intensity evaluation method based on the CRITIC method and order relation analysis method (G1) was proposed in this paper. First, a rock’s uniaxial compressive strength σc, tangential stress σθ, uniaxial tensile strength σt, ratio of uniaxial compressive strength to tensile strength σc/σt (brittleness coefficient), ratio of tangential stress to uniaxial compressive strength σθ/σc (stress coefficient), elastic deformation energy index Wet, and depth of cover H were selected as evaluation indices of rock burst intensity. Ninety-five groups of rock burst measured data at home and abroad were selected, and the objective weight and subjective weight of each index were calculated by using the CRITIC method and G1 method, respectively. The comprehensive weight was determined according to the combined weighting method of game theory, and the sensitivity of each evaluation index was analyzed. By utilizing a forward cloud generator, the membership degrees of different rock burst grades were calculated, and then the rock burst intensity grades of the samples were evaluated and compared with the evaluation results of the CRITIC-CM method and G1-CM method and the actual grades. Finally, the rock burst classification ability of the model was analyzed. To better verify the accuracy and reliability of this model, the rock burst case of the W39 line in the Chengchao Iron Mine was analyzed by using this model. The research results show that the rock burst evaluation results based on CRITIC-G1-CM are basically consistent with the actual rock burst grade, and the rock burst intensity grade evaluation model has good practicability and reliability.

Sep 1, 2023

By Y. T. M. Ocsa, V. O. Tenorio

This research is the result of a geotechnical study carried out in a natural slope in an Open Pit mine in Southern Peru, highlighting earthquakes as an important cause of instability within the case study presented. This leads to analyze the stability of a slope, according to the safety factor and thus consider a future construction in its environment according to the identified requirements. There are known disasters at national and international level that involve human lives because of the lack of analysis of slope stability conditions, which based on the results will allow to control and to take adequate corrective measures. These mass movements are classified whether they are soils or rocks, considering the mechanism and type of rupture, as well as the presence of water, the speed and magnitude of the movement. The movement problems are due to factors of inherent nature and constitute a reason to perform a calculation study to analyze and estimate the safety factor of each of the evaluated cases

Mar 2, 2022

By Rong Guo, Qi He, Jinsuo Zhang

"Coal mine ranks No.1 among the 6 major high-risk industries, so it is no doubt that the senior managers in the coal mine bear more stress than other industry executives. The massive working stress results in serious influences on the physical and mental health of the senior managers of coal mine, which might also induce the safety risk in the coal mine. Therefore, to evaluate the senior managers’ working stress and put forward strategies of mitigating the stress is of great theoretical and practical significance in improving the physical and mental health of the senior managers and reducing the safety risk in the coal mine. The research on the working stress has been made in the western countries for almost 50 years, China began the research in the mid and late 1990s, the research is spread across multiple industries including education, medical treatment, computer and aviation. However, there is little research on the senior managers’ working stress of the coal mine, so the available literatures are few. In the paper, we, based on the working stress model of Robbins and through questionnaire survey, analyze the element composition of the senior managers’ working stress of the coal mine; then, we construct the evaluation indicator system of the senior managers’ working stress of the coal mine based on the individual factor, organization factor and environment factor; after that, we determine weights of each evaluation indicators by using the improved triangular fuzzy number weight method, and set up the evaluation model of the senior managers’ working stress of the coal mine on the basis of the fuzzy comprehensive assessment method. At last, in accordance with the model, we evaluate and analyze the working stress for the senior managers of some typical coal mines, and diagnoses the major sources and intensities of the senior managers’ working stress, and then propose corresponding strategies of mitigating the stress."

Jan 1, 2017

By S. Bassignani, D. Ippolito

In Italy at the moment there is a program which involves for the future the exploitation of two uranium mines which are now in the research stage. About one hundred and fifty workers are at present employed in those facilities. An health physics surveillance program is under way and has been designed to fulfill the requirements due to the future exploitation of the two mines. A complete evaluation of the total dose (external + internal) received by the workers will be given together with a detailed analyses of the technical methods employed for such evaluations. The external doses are evaluated on the basis of individual TLD dosimeters, while the evaluation of the internal doses is mainly due to an enviromental survillance program of the radon and radon daughter air concentration inside the mines. The criteria established for the assessment of the sampling procedures, sampling intervals and dose evaluation related to the radon doughter exposure are reported. The external dose received by the workers are lower than 0.2 m Sv~month and the internal exposure less than 6.4 IO-3 J.h.m-3 /year or using the old units 2 WLM/year.

Jan 1, 1981

The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner's cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutter head, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head's effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner improved air quality at both locations to varying degrees in some cases and not in others when compared to a continuous miner with a standard spray system.

Jan 1, 2010

By Marvin A. Ph. D. Friedman

The following paper describes an overview of evaluations for assessing the potential hazards associated with handling newly developed reagents used in the mining industry. Important factors in determining the risk and hazard associated with handling a particular chemical include hazard identification, dose-response assessment, exposure assessment, and risk characterization. The hazard evaluation step involves collecting and evaluating appropriate toxicology information on a chemical. This can include a comparison of the structure of a developmental chemical with that of a material with known toxicology information. Acute toxicology data, including oral, inhalation, and dermal LD50 values, eye and skin irritation data and sensitization or allergic potential information are typically generated for new chemicals. Environmental and in-vitro genetic toxicology data (e.g. Ames test) are also used to evaluate new mining reagents.

Jan 1, 1994

By C. P. Mangelsdorf, Richard A. Allwes

At the request of the U.S. Department of Labor, Mine Safety and Health Administration (MSHA), the U.S. Bureau of Mines evaluated the suitability of using tri-sets for protecting mine personnel in roof-fall prone areas. A steel-set arch provided by MSHA served as a basis for evaluating the performance of the tri- set. All tests and analyses were conducted according to the arch canopy test and design procedures developed by the Bureau. Theoretical resistance functions were established for the steel-set arch and tri-set and were representative of their experimental behavior. The resistance functions were used to determine the energy absorption capacity of the structures and to predict their dynamic response to impact loading. The dynamic tests demonstrated that the arch canopy design procedure is appropriate for tri -sets and yields conservative designs for both steel-set arches and tri-sets. As a result of this work, it is recommended that tri-sets may be considered for protection against roof falls, provided that the arch canopy design procedure is utilized for each application and that the principles underlying the design procedure are understood.

Jan 1, 1992

The declining grades of surface deposits have re-confirmed the need for greater production rates. Large scale production requires increased investments in expensive and sophisticated equipment. The key to successful operations can depend entirely on proper equipment utilisation and in this program of research at the Department of Mining and Metallurgical Engineering, University of Queensland, much emphasis has been placed on the analysis and improvement of this aspect of a load-haul-dump operation. For a model to be successfully integrated into a mine engineering function and readily accepted by mine operating personnel, it has to offer more than just results. The concepts used in its design and construction must include sufficient detail to enable engineers to apply it usefully and with confidence.

Jan 1, 1979

By Paul S. Parobeck, Robert A. Haney, Andrew J. Gero, Thomas F. Tomb

As a result of recommendations made in the 1988 Report of the Mine Safety and Health Administration Advisory Committee on Standards and Regulations for Diesel-Powered Equipment in Underground Coal Mines, the Mine Safety and Health Administration (MSHA) initiated a program to develop and test a diesel particulate sampling device. The sampling device employed the principles of inertial impaction to separate respirable dust into two fractions; one fraction containing particulate material having an aerodynamic equivalent diameter equal to, or greater than, 1.0 micrometer, and the other fraction containing particulate material having an aerodynamic equivalent diameter less than 1.0 micrometer. The design criteria were based on data which showed that virtually all of the diesel particulate material and very little of the mine generated dust was less than 1.0 micrometer in size. The instrument was tested in underground dieselized coal mines and in the laboratory. Comparative measurements were obtained with the MSHA designed impactor sampler, a University of Minnesota (UM) designed impactor sampler and MSHA's standard respirable coal mine dust sampler. Simultaneous measurements were also obtained with five of the MSHA and five of the UM designed impactor samplers to investigate between sampler precision. The paper discusses the design differences between the MSHA and UM impactor samplers, the precision of replicate measurement obtained with both instruments and compares measurements obtained with the respective samplers of the sub- and supermicron fractions of the respirable material.

Jan 1, 1991

By John C. LaScola, Gerald L. Finfinger, Michael A. Trevits

Methane gas is an ever-present problem facing the underground coal mining industry. Mine operators are mandated by law to maintain safe concentrations of methane gas within the mine environment. Ventilation is the method of choice used by all mine operators to reduce gas concentrations. When gas emissions are such that ventilation alone cannot control the gas, methane drainage methods must be applied. In the 1970’s, there was a concern that unprecedented gas emissions would be experienced as mine operators began new developments in the deep and gassy Blue Creek and Pocahontas No. 3 Coalbeds. Such concern was well founded as significant gas volumes are being emitted as these mining operations mature. In 1971, the U.S. Bureau of Mines began to tabulate and track the change in mine emissions. These data were extracted from the underground coal mine quarterly air quality-quantity inspections performed by the Mine Safety and Health Administration. At that time, approximately 6560 Mm3/d (231.7 MMcfd) of gas were emitted from 430 underground coal mines. It was determined however, that the mines emitting less than 2832 m3/d (100 Mcfd) contributed only 2.1 percent of the total daily gas flow. In 1988, underground coal mines emitted 8350 Mm3/d (294.9 MMcfd) from 487 mines. This report evaluates the changing nature of U.S. mine gas emissions over the last 18 years.

Jan 1, 1991

By M. A. Trevits

Methane gas is an ever-present problem facing the underground coal mining industry. Mine operators are mandated by law to maintain safe concentrations of methane gas within the mine environment. Ventilation is used by all mine operators to reduce gas concentrations. When gas emissions are such that ventilation alone cannot control the gas, methane drainage methods must be applied. In the 1970's, there was a concern that unprecedented gas emissions would be experienced as mine operators began new developments in the deep and gassy Blue Creek and Pocahontas No. 3 Coalbeds. Such concern was well founded as significant gas volumes are being emitted as these mining operations mature. In 1971, the O.S. Bureau of Mines began to tabulate and track the change in mine emissions. These data were extracted from the underground coal mine quarterly air quality-quantity inspections performed by the Mine Safety and Health Administration. At that time, approximately 6,560 Mm Id (231.7 MMcfd) of gas were emitted from 430 underground coal mines. It was determined however, that the mines emitting less than 2,832 m Id (100 Mcfd) contributed only 2.1 percent of the total daily gas flow. In 1988, underground coal mines emitted 8350 Mm Id (294.9 MMcfd) from 487 mines. This report evaluates the changing nature of U.S. mine gas emissions over the last 18 years.

Jan 1, 1993

By H. Sevim

In this paper, the research effort in simulating the operation of underground coarse-coal hydrotransport systems (UCCHS) is summarized. The equipment of the system to be simulated is already optimally selected by using an analytical optimization model. The purpose of the simulation model is to test the performance of the system and to obtain the distribution of the operating parameters such as water and power consumption, amount of slurry delivered to the preparation plant, etc. Knowledge of the distribution of these parameters is essential for the efficiency of the design and the operation of the system.

Jan 1, 1985

By H. Sevim

This paper summarizes the research effort in simulating the operation of "Underground Coarse-Coal Hydrotransport Systems" (UCCHS). The equipment of the system to be simulated is already optimally selected by using an analytical optimization model. The purpose of the simulation model is to test the performance of the system and to obtain the distributions of operating parameters such as water and power consumption and amount of slurry delivered to the preparation plant. Knowledge of the distributions of these parameters is essential for the efficient operation of the system.

Jan 1, 1987

By J. T. Kline

This paper will present a review of the underground leaching of remnant copper mineralization left as a result of the block cave mining operation at the Lakeshore Mine in Casa Grande, Arizona.

Jan 1, 1985

By Taghi Sherizadeh, KUTAY E. KARADENIZ, Dogukan Guner, Samuel Nowak

Underground mining environments bring with them occupational health and safety issues with some severe dangers, such as mine explosions. During such events, miners may escape using main access openings or find a safe haven like a refuge alternative (RA) to wait and be rescued and evacuated to the surface. In this paper, RAs are explained with their early and current applications. A classification as permanent and portable is detailed, depending on conditions and abilities. This classification is followed by the utilization and survivability of RAs with the requirements and recommendations of the main mining countries. Based on the utilization and survivability constraints, basic human requirements, waiting for a rescue team, and the required physical specifications of RAs during the events are analyzed in detail for various countries with their regulations. Among these, the specification of resistance to explosion is discussed in particular, and studies in the literature are examined in terms of structural deformation.

Mar 1, 2023