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By W. R. Reed, D. E. Pollock, T. W. Beck, J. A. Organiscak, J. D. Potts

In underground continuous mining operations, ventilation, water sprays and machine-mounted flooded-bed scrubbers are the primary means of controlling respirable dust exposures at the working face. Changes in mining arrangements — such as face ventilation configuration, orientation of crosscuts mined in relation to the section ventilation and equipment operator positioning — can have impacts on the ability of dust controls to reduce occupational respirable dust exposures. This study reports and analyzes dust concentrations measured by the Pittsburgh Mining Research Division for remotecontrolled continuous mining machine operators as well as haulage operators at 10 U.S. underground mines. The results of these respirable dust surveys show that continuous miner exposures varied little with depth of cut but are significantly higher with exhaust ventilation. Haulage operators experienced elevated concentrations with blowing face ventilation. Elevated dust concentrations were observed for both continuous miner operators and haulage operators when working in crosscuts driven into or counter to the section airflow. Individual cuts are highlighted to demonstrate instances of minimal and excessive dust exposures attributable to particular mining configurations. These findings form the basis for recommendations for lowering face worker respirable dust exposures.

Jan 1, 2016

By Will B. Jamison

The most serious safety problems encountered in U. S. underground coal mines today are related to the roof bolting operation. Also, roof bolting is usually the operation which limits coal production of the section. The purpose of my paper is to review some of the research, developments, and new ideas related to roof bolting. Many of these ideas have originated at. coal mines or with manufacturers. Most of the research on fundamental improvements has been funded by, and is a part of, the excellent and broad plans of the Bureau of Mines.

Jan 1, 1977

By L. A. Baker

The presence of goethite in a hematite ore has been shown to strongly affect the time of heating to the firing temperature. The investigation of spalling of single pellets and of packed beds has enabled free water and goethite spalling to be identified as separate phenomena. In addition, it has been shown that even for an 18 inch deep bed of green balls the free water and goethite drying periods can be considered separately. Based on this observation, a method of predicting production rate and hood temperature profile is presented. The method required knowledge of the ore goethite content, ore grind and the green pellet bulk density. Laboratory results were found to be in good agreement with actual plant practice and have led to improved process performance.

Jan 1, 1972

By L. B. Phelps

Many coal mining companies have potential surface mine reserves which either are known or suspected to have had prior drift mining activity on them. In many cases, there is no documentation on these mines or at best, very fragmented records. These undocumented abandoned underground mines are creating engineering, financial, and environmental difficulties and concerns for both surface coal mine operators and regulatory personnel. This paper examines the use of resistivity techniques in detecting entries of abandoned drift coal mines. The detection of such a drift mine entry would confirm the presence and orientation of an abandoned underground coal mine.

Jan 1, 1985

By K. S. Radcliffe

Results are presented for the first phase of an experimental program to study the feasibility of using acoustic velocity for predicting the state of stress in a rock mass. Compressional wave velocities were determined axially in cylindrical samples during uniaxial compression for several rock types conditioned in dry and water-saturated environments. Results indicate that in rocks containing compressible voids or cracks, substantial velocity change occurs with the application of stress in the lower (below 100 MPa) stress regime. The effect norm- ally is nonlinear, however, and diminishes to asymptotic values when cracks or voids become closed or with saturation. Empirical prediction equations were derived for each rock type by linear and nonlinear regression analyses, and correlation coefficients were calculated to determine the equations that best fit the stress- velocity data. The operational range for predicting stress using compressional-wave velocity appears to be within the range of vertical stress expected in most shallow to intermediate depth mining operations (less than 1,000 m). Based on the experimental results to date and theoretical considerations, it appears that the technology can be advanced to predict in situ stress based on acoustic P-wave velocity determinations in most mining situations.

Jan 1, 1986

By Nikolaos Syrtariotis, Mark Berger, Timothy O’Brien, Vojtech Gall

The Northeast Corridor Superconducting Maglev Project (SCMAGLEV) entails construction of a high-speed train system between Washington, DC and New York City, with the first leg between Washington and Baltimore, MD. This innovative project will shorten travel times between Washington DC and Baltimore to approximately 15 minutes, and connect Washington, DC to New York City in under an hour. In 2021 the draft EIS is expected to be issued for comment with a Final EIS/ROD anticipated by early 2022. This paper provides an update on the project as presented in Gall et al. (2020) and discusses the economic and environmental benefits, preferred alignment alternative, preliminary staging and launching of the TBMs for construction, and preliminary station design.

Jun 13, 2021

By F. Brost

In 1976, a decision was made to install a conveying system to transport ore 10.3 km (6.4 miles) from the new Eisenhower Partnership Mine to Twin Buttes. The system, supplied and installed by Cable Belt Limited, of England, represents a radical departure from conventional conveyor systems. The driving tension is applied through two endless wire ropes while the belt acts only as the carrying medium. Features of the system are a single 2240 kw (3000 hp) drive and a 60° angle bend. Construction was completed in two years. Full production was attained after several months' operation.

Jan 1, 1979

By K. Darcovich

The wettabilities of agglomerates made from coals of several different ranks were measured by the adhesion technique. Oil levels from 0 to 10% by weight were used. As was expected, it was found that higher-rank coals are more easily oil-wetted and that the surface properties of the agglomerates correlate with agglomeration recovery and ash removal data.

Jan 1, 1992

By J. P. H. Steele, T. Vincent, C. Debrunner, M. Whitehorn

For a variety of reasons, the need for automation of underground mining equipment is growing dramatically, e.g., improved safety and health, availability of labor, deeper mines, and desire for more focused excavation. While there has been tremendous progress made in this direction, much needs to be done to reach the holy grail of an autonomous mining machine. This paper reviews a number of technological developments and presents research and development needs for future development. A report on our current project for the Western Mining Resource Center at CSM is included.

Jan 1, 2000

By John S. Brock

During 1964 and 1965 a mineral exploration program was carried out over an area of approximately 250 square miles, located in the Anvil-Vangorda Creek area of east central Yukon, 125 miles northwest of Whitehorse. The Vangorda deposit, a massive lead-zinc sulphide body discovered in 1953, was centred in the area proposed for exploration, a northwest trending belt located between the southwestern flank of the Anvil Range and Pelly River. Exploration for base metals in the remote Anvil area had previously been restricted by poor metal markets in the late 1950's. Regional geologic information was also limited except for publication of a scale 1 inch to 4 mile map by the Geological Survey of Canada in 1961. To effectively explore this area, a combination of geophysical and geochemical methods were essential due to extensive overburden cover varying in depth from a few feet to over 300 feet. (Figure (i) Key Map) Dynasty Explorations initiated the first comprehensive regional exploration program in the Anvil area, utilizing saturation prospecting methods employing geologic, geochemical and geophysical methods. The program involved an approach demanding continual modification of technical and physical logistics. After a total of 12 months of field work involving an expenditure of approximately $450,00, massive sulphides were discovered which subsequently proved to be an economic orebody. Thirteen properties had been acquired and explored. Ten separate geophysical anomalies had been outlined by a combination of magnetic, electric and gravimetric survey techniques of which five were tested by rotary drilling and two by diamond core drilling. The discovery of the Faro deposit was a direct result of this program.

Jan 1, 1971

By R. Wild

[When a blast furnace has a certain defined burden and is operated under fixed conditions of blast temperature, etc., the fuel efficiency is determined by the extent to which the reducing gases can remove oxygen from the burden in the furnace stack. This is determined by two distinct factors: 1) The uniformity of gas-solid contact, and 2) The ease with which oxygen can be removed from individual pieces of burden. This latter is often called burden reducibility. When burdens were poorly prepared the first factor was by far the most important and a study of the reducibility of individual lumps was of rather academic interest recent years good burden preparation with emphasis on sized material has led to greatly improved gas distribution in the stack, and thus the second factor has become much more important and there has been a marked increase in interest in methods of measuring reducibility.]

Jan 1, 1964

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi

The abstract highlights the impact of flocculants used in the middle thickener of a copper-molybdenum plant on both process water quality and molybdenite floatability. The study investigates the effect of a starch-based flocculant (wheat starch) on the efficiency of the middle thickener and molybdenite flotation. The findings indicate that the presence of starch influences the settling behavior of particles with different shapes, and the dosage of starch affects both molybdenum recovery and the presence of copper minerals in the molybdenum concentrate.

Mar 7, 2022

By S. Castro, L. Gutierrez

A classification of flotation processes carried out in concentrated electrolyte solutions, e.g., seawater, is proposed using the most obvious features of these processes: low or high content of Mg2+ and Ca2+ ions, pulp ionic strength, and pH. The first distinguishable group is the processes carried out in NaCl/KCl solutions, about 0.5 M in the case of salt flotation of inherently hydrophobic minerals, and at concentrations about 10 times higher in the flotation of potash ores. In the flotation of sulfide ores, such as nickel or copper ores, with xanthate-like collectors, the xanthate collector is apparently not affected by pulp ionic strength and only adjustment of frother may be required. Content of Mg2+ and Ca2+ ions in seawater is the main difference between such systems and fresh water. The presence of these metallic ions can adversely affect flotation in the pH ranges over which these ions hydrolyse. The successful flotation of Cu-Mo ores typically requires depression of pyrite at high pH values achieved with the use of lime. However, in seawater, flotation of Cu-Mo ores requires removal of the hydrolysis products of the Mg2+ and Ca2+ ions or the use of a pyrite depressant that can be effective over the pH ranges that are much below the pH of hydrolysis. Mg2+ and Ca2+ ions also affect flotation of phosphate ores with fatty acids. In this case, the depression mechanism is not caused by precipitating magnesium hydroxides on the mineral surface but by precipitation of collector insoluble salts, and the same ions are responsible for depression in both cases. In the seawater flotation of Cu-Mo sulfide ores and phosphate ores, the practical solution involves either removal of Mg2+ and Ca2+ ions prior to the flotation or complexation with other reagents.

By J. E. Dreier, R. E. Scheffel, A. Guzman

"This paper outlines a comprehensive, cost-effective testing program for the acid-ferric sulfate heap leaching of oxide, supergene and primary copper ores. It is based on extensive experience in copper heap leaching and uses the many technological advances in the field developed over the past several decades. The approach described requires firstly a detailed resource evaluation, then a hydrodynamic characterization of representative samples and, finally, a focused metallurgical testing program. The principles communicated here can be applied to other acid leachable minerals. The program varies considerably from conventional testing in its disciplined, orderly, step-by-step approach, its application of hydrological and chemical principles to leaching, and its reliance on fewer, more tightly controlled column tests. The purpose of the test program is to optimize the financial, time and other resources devoted to the program, while minimizing the financial risks to the development company or companies and the project funding providers. IntroductionThe major goal of any process development testing program should be the successful implementation of the project. With respect to heap leaching, the metallurgical testing program plays a critical role in the larger objective, as described in Scheffel (2013, 2014). McNulty’s series of papers (1998, 2004, 2014) confirm that the success of any project is directly proportional to the extent and quality of the testing program on which the process is designed.Therefore, a key development objective is to conduct a well-focused metallurgical test program. While the primary focus of this paper is copper, the acid leaching of any substance would benefit from a similar approach.This paper addresses primarily the sulfate system, which is compatible with the bioleaching of sulfide minerals. Nicol et al. (2011) described the advantages of the chloride leaching of copper sulfide minerals. United States patents Nos. US 2009/0173188 A1, US 8,597,933 B2 and US2015/0232963 A1, assigned to BHP Chile Inc. and BHP Billiton S.A. Ltd, describe methods for both the oxidative and nonoxidative leaching of primary and secondary copper sulfides. Reyes (2013) and Ipinza and Flaquer (2014) described commercial applications of chloride-based heap leaching. The testing disciplines discussed in this paper will also apply to the development of an acidic chloride leaching system."

Jan 1, 2016

By VÍCTOR VÁZQUEZ-VÁZQUEZ, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, JESÚS L. VALENZUELA-GARCÍA, OFELIA HERNÁNDEZ-NEGRETE

This study examines a process for the recovery of precious metals from difficult minerals that exhibit refractory characteristics to cyanidation: low extraction of metals and high consumption of leaching reagent. A mineral sample from Monte del Favor Mine, located in Hostotipaquillo, Jalisco, Mexico, was physically and chemically characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fire assay and atomic absorption spectroscopy (AAS). Two stages of leaching were carried out, first to eliminate manganese from the sample using sodium sulfite (Na2SO3) as a reductive reagent along with sulfuric acid (H2SO4), and second to dissolve gold and silver with hydrochloric acid (HCl) and sodium hypochlorite (NaClO). The results show extractions of around 96 percent for manganese (Mn), 98.73 percent for silver (Ag) and 83 percent for gold (Au). The usefulness of high acidity and Na2SO3 to obtain better results in Mn and Ag leaching are discussed along with the roles that HCl and NaClO play in Ag and Au dissolution values.

By L. Zhou, D. Bahrami

Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance

Mar 2, 2022

By Omid Asghari, Seyed Reza Ghavami-Riabi, Sajjad Talesh Hosseini

Separation of geochemical anomalies from the background using various methods for identifying areas of higher mineral potential is a critical first step in Greenfield and Brownfield programs. There are several methods for differentiating anomalous regions from the background. The U-spatial statistics is an effective technique that provides the opportunity of reaching this goal by considering the geochemical sample locations in the separation of geochemical anomalies. In this study, a developed form of the U-spatial statistics method is introduced, which not only considers the existence of anisotropic spatial variations in input data but also reduces the computational (CPU) time. While the previous method is based on the isotropic assumption in the study area and a set of search windows at different times, here, the geochemical anomaly is determined by pasting only one ellipsoid window, effectively combining the flexibility of the U-spatial statistics method with the advantages of geostatistical approaches. This paper compares various approaches (the previous and developed version of the U-spatial statistics method, concentrationarea (C–A) fractal model, and probability diagram modeling) for the separation of anomalous areas in the presence of heterogeneous spatial variations. This is done with an application to a Baghqloom porphyry copper deposit located in southeastern Iran. The high potential areas identified via different approaches show an anomalous region in central parts of the Baghqloom area, which partially coincides with an intense potassic alteration area. Compared to other methods, our algorithm separated the high potential areas at a greater spatial resolution.

May 3, 2021

By J. O. Marsden

This paper presents an overview of the innovative methods for gold and silver extraction that have been put into actual practice in North America since 1987. It is an update of a paper of the same title which was presented by Sass and Mansanti at the AMC conference in San Francisco in 1987. New practices, new equipment and variations of older practices that have been introduced in the last five years are discussed in each of the following categories: process selection trends, comminution, gravity concentration, flotation, oxidation, agitated and vat leaching, heap leaching, solution concentration and purification, zinc precipitation, electrowinning, tailings disposal detoxification, and reclamation.

Jan 1, 1993

By Sunil Vytla, Agus Sasmito, Akash Adhikari, Srivatsan Jayaraman Sridharan, Purushotham Tukkaraja

Previous studies on blast fumes (carbon monoxide and nitrogen dioxide) clearance and workplace reentry time have overlooked the effects of toxic gases trapped in the muck pile. The currently available models for calculating the mine reentry times assume that all post-blast fumes are emitted upon detonation. However, recent studies reported that as much as 60 to 70% [1–5] of the fumes or gases produced during an underground development blasting could remain trapped in the adjacent rock mass or in the muck pile. Trapped fumes are slowly released [1–5], and when disturbed, high concentrations are released, representing a possible risk during the loading and transportation of the muck pile. In this study, mathematical models were developed using computational fluid dynamics to understand the behavior of the trapped fumes and their effect on mine reentry time. The three scenarios considered for this study include (i) gas emission source with no muck pile volume, (ii) gas emission source with non-porous muck pile volume, and (iii) gas emission source with porous muck pile volume. The estimated reentry times in all three scenarios were compared to see how porous media affects dilution time. It was observed that scenario 3, with fumes trapped in the muck pile, took a significantly longer clearance time (more than double) as compared to scenarios 1 and 2.

May 17, 2022

By Moussa Wone, Jeff Peterson, Filippo Azzarà, Daniele Nebbia

The DC Water and Sewer Authority's Long Term Control Plan includes tunnels, sewer separation, pumping station rehabilitation and green infrastructure to reduce combined sewer overflow (CSO) discharges to the District waterways. The Northeast Boundary Tunnel is a deep, large sewer tunnel that will reduce CSO discharges; signifi- cantly mitigate known chronic flooding in the Northeast Boundary drainage area and improve the water quality of the Anacostia River. This paper presents the unique combination of Owner and Contractor perspectives of the entire Project from conception through procurement, execution, and contract management, providing lesson learned, chal- lenges encountered, and solutions implemented to deliver the Project successfully.

Jun 23, 2024