Search Documents

By L. Zhou, J. P. Rider, T. W. Beck, J. A. Organiscak, Y. Zheng

The National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research recently developed a series of models using computational fluid dynamics (CFD) to study the gas distribution around a continuous mining machine with various fan-powered flooded bed scrubber discharge configurations. CFD models using Species Transport Model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The following scenarios are considered in this study: 100 percent of the discharge redirected back toward the face on the off-curtain side of the continuous miner; 100 percent of the discharge redirected back toward the face, but divided equally to both sides of the machine; and 15 percent of the discharge redirected toward the face on the off-curtain side of the machine, with 85 percent directed into the return. These models were compared against a model with a conventional scrubber discharge, where air is directed away from the face into the return. The CFD models were calibrated and validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100 percent redirected, equally divided case. These models identified relatively high gassy areas around the continuous miner, which may not warrant their use in coal mines with medium to high methane liberation rates. This paper describes the methodology used to develop the CFD models, and the validation of the models based on experimental data.

Jan 1, 2015

By Amar Prakash, V. M. S. R. Murthy, VIVEK KUMAR HIMANSHU, Sufal Mehrotra, Ashish Kumar Vishwakarma

Raises are vertical or inclined openings made to connect two levels of an underground metalliferous mine. They are developed using drilling and blasting-based technique or by mechanical means. Raise boring machines (RBM) have evolved in recent years, which provide quicker and safer raise excavation. The penetration rate using RBM has influenced applied thrust. The required thrust to enhance penetration rate with optimal use of energy would be different under varying geological and geotechnical conditions. In this study, the influence of applied thrust on penetration rate using RBM has been investigated. The investigation has been made for two different rock types, amphibolite (AMP) and garnet-biotite-sillimanite-gneiss (GBSG). The numerical simulation model was developed for this purpose using Ansys-Explicit Dynamics. The induced tensile stress under different conditions of applied thrust has been analysed in the calibrated numerical model. The model output shows the power trend between the parameters. The experimental data on penetration rate was also collected along with the respective operational parameters. A statistical analysis has been carried out for the gathered data. The analysis of data also shows a power trend between thrust per cutter and penetration rate in both rock types and hence validates the numerical simulation-based output. Based on the outputs of the numerical simulation and empirical study of the experimental data, the optimum thrust per cutter for excavation in both rock types is in the range of 12–14 tons. The approach used in this study can be helpful for predicting the optimal operational parameters of raise boring machines under different geological/geotechnical conditions.

May 29, 2023

By M. S. Celik

Beneficiation of boron minerals by flotation with well defined systems has been very little investigated in the literature. The difficulty arises from the fact that boron minerals cover a spectrum of solubilities. Colemanite, a calcium containing relatively insoluble boron mineral, and borax, a highly soluble boron mineral have been used to exemplify the flotation of boron minerals. The floatability of both minerals using sodium dodecylsulfonate and dodecylamine hydrochloride exhibits considerable differences in their response to flotation. This has been ascribed to variations in the solubilities 0f boron minerals and the presence of the cations in the lattice structure. Flotation tests along with zeta potential measurements are used to elucidate the mechanisms involved in the flotation of boron minerals.

Jan 1, 1992

By R. J. Matetic

Mining operations have long been accused of causing a disruption to local, domestic and agricultural water supplies. More recently, concern for water supplies has increased with the advent of high-extraction mining techniques, namely longwall mining. Theoretically, any water bearing zone in the overburden above a high-extraction mining operation may be affected by mining. In some cases, a confining bed may be fractured causing a loss of water to a particular zone. In other cases, increased fracture permeability may enhance the ability of an aquifer to transmit and deliver water. Unfortunately, only a limited amount of studies have been conducted that characterize hydrologic changes and also quant1fythe magnitude of mining-induced subsidence. The U.S. Bureau of Mines conducted such a study at a mine site located in Greene County, PA. A total of 8 water wells were drilled and hydrologic parameters such as specific capacity, transmissivity and well yield were determined both before and after mining. Electronic water level recorders were installed on each water well to provide continuous observations of water level fluctuations.

Jan 1, 1990

By R. T. Richins

Coeur d'Alene Mines Corporation (CDE) is a precious metals mining company. The company's three mining operations are located In Nevada and Idaho. Collectively, these mines (Rochester in Nevada, and the Galena and Coeur In Idaho) produced about 61,000 ounces of gold and more than 7.5 million ounces of silver in 1991. The company is currently planning the development of two major properties; the Fachinal gold-silver project in Chile and the Kensington gold project near Juneau, Alaska. Fachinal and Kensington hold encouraging potential to significantly expand CDE's gold production during this decade. The permitting process for these two distinctly contrasting environmental settings, project design requirements and regulatory/political circumstances provide the basis for a comparative analysis of licensing and permitting requirements, timeliness of the permitting process and costs in the U.S. and Chile.

Jan 1, 1993

By P. J. Arps

Cyanide (CN) is used to recover gold from its ores in many locations worldwide. In spite of the established history of gold mining in Alaska, modern cyanidation methods have been used at only one location, the Ryan Lode Mine at Ester Dome, near Fairbanks. Ore was processed by heap leaching between 1987 and 1989, when permitting issues caused operations to be terminated. Those issues have since been resolved, and plans to reopen the mine are currently being discussed. Plans are also proceeding to develop several other ore deposits in the state, all of which include the use of cyanide for gold recovery [6]. Since tailings and effluent water produced from these mines will require treatment, it is important to develop detoxification methods suitable for the Arctic and sub-Arctic conditions found in Alaska. Several methods exist for removing cyanide from mining wastewater. However, most industrial users prefer chemical treatment systems, and typically use sodium hypochlorite, hydrogen peroxide, or sulfur dioxide/air/copper to oxidize free and complexed cyanides [9]. Biological treatment has been used successfully at two sites in the United States [30,32] and field tested at several others [20,27,28]. In addition, one mine uses "natural processes", which include natural oxidation, photodegradation, and degradation by naturally occurring bacteria [33].

Jan 1, 1994

By A. B. Cecala

The Bureau of Mines performed a study to determine optimal locations for longwall face methane monitoring equipment. Longwall face ignitions continue to be a concern to the U.S. coal mining industry. Gains in ignition control technology have been somewhat negated by advances in longwall productivity. More reliable, heavy-duty longwall face systems generate higher production rates and increase methane liberation rates. These rates will likely continue to rise in the future as further coal production increases occur. Efforts will continue in the areas of methane drainage, methane containment, and methane dilution. In addition, more effective face methane monitoring is needed. As technology continues toward automated longwall panels, the importance of monitoring for methane at the shearer becomes even more significant. Since the primary face ignition source is the shearer mining machine, the Bureau ran tests to determine the best location to take methane readings on the shearer. This information, in conjunction with data obtained from field studies, provides a knowledge base for selecting optimum face methane monitoring locations.

Jan 1, 1993

By V. Rastogi

Acid rock drainage is the result of exposure of sulfidic materials, such as pyrites and sulfidic ores, to air and water. The oxidation of these sulfides is catalyzed by more than a million times by the bacteria Thiobacillus jerrooxidans and close families. Inhibition of these bacteria can mitigate 98% or more of the acid loading generated. This can be achieved by the use of certain surfactants that are selectively bactericidal to the lithotropic acidophilic bacteria. Bactericides are used in two ways. As periodic or continuous treatments for prevention of acidification of material actively handled and moved, and in controlled release form for reclamation where treatment sets up a change in site microbiology to replace Thiobacillus jerrooxidans with heterotrophic bacteria and creates a stable site without need for further treatments. Use of bactericides begins with laboratory testing of the site material to qualify the site for bactericide treatment and dosage determination. Site specific treatments are designed for active sites and reclamation. Once acid production is controlled, solubilization of metals is correspondingly reduced. Results and economics of use from active and reclamation sites are presented.

Jan 1, 1995

By A. Miller, M. McNinch, R. Jacksha

Each year, hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The U.S. National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s two-phase implementation of an IoT-based intelligent machine monitoring system.

By Z. T. Bieniawski

Engineering rock mass classifications have received prominent attention as design aids in rock tunneling. Support selection in civil engineering tunnels and chambers is often based on such classifications. In the field of mining, rock mass classifications have not been utilized to the same extent but some applications have been made. This paper considers the current rock mass classification schemes from the point of view of their potential in mining. Case histories are described featuring their use in assessing the cavability of ore as well as entry stability and support. Current possibilities for rock mass classifications as design aids in mining are outlined.

Jan 1, 1980

By A. Vien

A major thrust in Industrial automation over the past few years has been the exploration and incorporation of higher level (supervisory and optimizing) control strategies aimed at more fully exploiting the existing control system infrastructure. There is little doubt that this is worthwhile pursuit, however, one must not lose sight of the maintenance and development requirements of the basic control system. Statistics on loop performance indicate that this too is an area of considerable potential. In this paper the authors look at some of the less elegant, but arguably equally important issues in mineral processing plant control. The focus is on controller structures, loop tuning, sampling, filtering, and some of the other principal components of the regulatory control foundations. In many cases significant improvements In control performance can be achieved by getting back to the basics.

Jan 1, 1998

By Fengyu Ren, Kunpeng Yu, Gideon Chitomb, Qiangqiang Gao, Liqiang Ma, Jiangtao Zhai, Ichhuy Ngo

The penetration of rock fragments of overlying strata causes advanced ore dilution during drawing. The results of numerical and physical experiments showed that the proposed numerical simulation was applicable and the microscopic parameters of the model were reliable. The penetration under the variables of particle diameter ratio, density ratio, overlying strata thickness, and particle morphology was clarified. The penetration was quantitatively characterized by the discharge amount and the dilution rate. The experimental results showed that the diameter ratio and density ratio had a significant influence on the penetration. On the irregular shape of particles, the penetration is weakened. The overlying strata thickness had little effect on the penetration. This study could provide a theoretical basis for the full section uniform drawing, avoiding advanced ore dilution and further optimization of recovery rate.

Nov 13, 2023

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By A. Vilinska

The adhesion of Leptospirillum ferrooxidans bacterial cells onto the sulfide minerals pyrite and chalcopyrite was evaluated using two different physical-chemical approaches; thermodynamic and extended DLVO theory. For the parameters incorporated into calculations, the zeta potentials and contact angles of powdered solids and bacterial cells were acquired experimentally. The Hamaker constants essential for Lifshitz-van der Waals inter-action calculations were calculated following two different methods: macroscopic and microscopic. Adsorption tests were carried out at physiologic conditions to estimate the amount of cells adsorbed onto a mineral surface and the extent of alteration of that mineral surface in biobeneficiation. The free energy of adhesion was found to be negative for both minerals, indicating that the adhesion is energetically favored and preferred. The interaction energy diagrams of the total interacting force was also negative for the cases where the particles were charged oppositely; in the remaining cases, the total force was attractive after overcoming an energetic barrier caused by the repulsive electrostatic forces. Under the conditions of the adsorption test, the experimental results are in agreement with the theoretical; this suggests that the physical-chemical forces are crucial for bacterial adhesion.

Jan 1, 2011

By Linda J. Dahl

The U.S. Department of the Interior, Bureau of Mines is developing a process to selectively extract manganese from oxide ores as part of its in situ leach mining research program. The Bureau is conducting site characterization studies of two manganiferous iron-formation deposits which include: drill core, regional stratigraphic relationships from the existing geologic database, ore body geometry, geologic structure, hydrologic conditions, proximity of ore minerals to the leach fluid paths, surface subsidence potential, and data collected from laboratory leaching experiments. This information is being used to evaluate the technical, environmental, and economic feasibility of in situ leach mining of manganese for these two deposits. This paper will focus on the stratigraphy, mineralogy, ore textures, fractures, permeability, and porosity as they relate to in situ leach mining.

Jan 1, 1992

By Madan M. Singh

Increasingly, geotechnical data are being collected for various types of coal development projects. In many cases, a specific design concern is addressed. However, many data collection programs are not intended to immediately support mine design activities or to resolve a specific concern. The following discussion describes some current geotechnical approaches in mine planning, development of reserves, and peripheral activities. Types of Data Collection Programs Geotechnical data collection is increasingly becoming a part of standard coal exploration programs, performed along with stratigraphic evaluations and coal quality tests. The aims of such programs vary. The purpose of the exploration may be to fill out the portfolio on a block of reserves that is to be sold, leased, or held for potential future development. In such a case, a generic suite of geotechnical data are collected. The resulting engineering reports may touch on the more well known mining problems of the area, but detail may be lacking. The geotechnical data are mostly intended to enhance the saleability of the package. Mine design alternatives are generally not addressed.

Jan 1, 1985

By Brent A. Elliott, J. Richard Kyle

Texas is a major producer of industrial mineral resources required by the state’s ever-growing population that now exceeds 28 million. Texas typically ranks in the top three states for the value of non-fuel mineral production with a total value of $5.2 billion in 2017, accounting for 6.9% of the total US mineral value. Almost 90% of current Texas industrial mineral value comes from the production of cement, crushed stone, industrial sand, and construction sand and gravel. Construction material consumption is focused in the 25 metropolitan areas of the state with populations of > 100,000 residents. Industrial mineral consumption is dominated by the four most populous regions of the state—Houston, Dallas-Fort Worth, San Antonio-New Braunfels, and Austin-Round Rock—with an aggregate population of more than 18 million. More than 11,000 employees work in Texas mining and processing operations. Texas produces more crushed stone than any other state from more than 200 quarries; a similar number of operations produce sand and gravel. Specialty industrial sand production for use as proppants in hydraulic fracturing for enhanced petroleum production serves as an excellent example of how developments in one industry sector can markedly affect another industry; the production of industrial sand in Texas has markedly increased over the past decade, reaching $1.3 billion in 2014. With Texas’ population projected to reach 50 million by 2050, continuing in-state development and production of industrial minerals will be required to supply its residential, commercial, and industrial users. Favorable geology and economic factors provide opportunities for identification and development of new industrial mineral production sites.

Solvent extraction-electro- winning appears to be one of the most important processes for the future in the North American copper industry and for this reason both the SX and EW steps are furtive areas for development. This paper has the objective of reviewing the present state of the electrowinning technology. It discusses some recent equipment developments and concludes by discussing the direction the technology will likely go fn the next decade.

Jan 1, 1985

By James Charles McHardy

During 1980-2000, the Florida Phosphate industry will deplete its Central Florida Polk County reserves. As a result, new mines will be built in the ?so-called? Southern Florida Reserve areas. These new mines will require new mining, beneficiation and tailings disposal technologies in that the southern reserves have different characteristics than have been encountered in the Central Florida deposits furthermore, government regulations will necessitate the development of new tailings and clay disposal methods. This paper reviews these challenges for the phosphate industry and how these opportunities can be expected to effect plant design and plant operating practices.

Jan 1, 1981

By William Gleason

"There are signs that the commodity downturn that has battered the mining industry for the past five years is beginning to ease up. As the dust begins to settle and mining companies begin to take stock of the battle, Newmont Mining Corp. will be one that is standing strong with just a few scrapes and bruises thanks in large part to the leadership of president and chief executive officer Gary Goldberg and his right hand man and chief operating officer, Chris Robison.As he closes in on retirement (for a second time) Robison, a third-generation miner from Nevada, took time to speak with Mining Engineering about a 33-year career in which, among other things, he is credited with not just helping Newmont survive the turbulent times but with steering the company to a safer, more productive and more profitable heading.“I think we did it better than anyone else,” Robison said when asked how the company fared during the past five years. “We didn’t talk about it a lot, we just put together a strategy and we delivered.”What Newmont, the world’s second-largest gold mining company by production, delivered since Robison took the position of chief operating officer in 2013 are improvements in costs, porduction, projects and safety.Operating under the mantra of “live within your means,” Robison was pulled out of retirement from Rio Tinto and into a challenging situation at Newmont. The price of gold was in a nose dive from a high of nearly $58/g ($1,800/oz) and heading to levels closer to $38.60/g ($1,200 oz).“Newmont is a big ship that can’t be turned, but has to be steered,” said Robison. “We recognized that we had to set a new course. The direction the ship was going was great for $1,600 to $1,800/oz gold but we were chasing ounces.”Like the rest of the gold mining sector before the falling gold prices, Newmont was focused on volume and was looking for gold wherever it could be found. The slogan at Newmont in 2011 was “7 million ounces a year by 2017.”When Robison came on board it was a different reality.“We had to begin focusing on value over volume as the cornerstone of Newmont going forward,” he said."

Aug 1, 2016