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By Werner Burger

After its first introduction in 2013, Variable Density TBMs have increased their application significantly in mechanized closed mode tunneling. Throughout a variety of successfully completed and ongoing projects since then, Variable Density TBM technology has demonstrated its advantages in a wide range of applications. This paper will present the developments and lessons learned from these projects as well as the future potential of Variable Density TBMs.

Jun 13, 2021

By J. C. Irvine

Meramec Mining Company, a joint venture by Bethlehem Steel Corporation and St. Joe Minerals Corporation, is engaged in the mining, concentrating, and pelletizing of iron ore from the Pea Ridge Mine located near Sullivan, Missouri, about 70 miles southwest of St. Louis. The orebody was delineated in the mid-1950's by St. Joe during an exploration program to discover new lead orebodies. An airborne magnetometer survey which was run by the U. S. Geological Survey, the Missouri Geological Survey, and several min¬ing companies was published in 1950 and showed an anomaly in the Pea Ridge area. Test holes drilled in 1953 and 1954 revealed the presence of a large orebody of probable commercial significance; additional drilling in 1956 and 1957 provided confirmation of this. Meramec Mining Company was incorporated in 1957 and shaft sinking began in the latter part of that year. The Pea Ridge orebody lies under about 1300 feet of sediments. It is tabular, about 2600 feet long and up to 600 feet thick, and lies in an approximate east-west delineation. The orebody dips about 800S and is of unknown depth. The ore is primarily high grade magnetite with smaller zones of specular hematite, The Pre-cambrian wall rock is rhyolite porphyry. The mine is serviced through two concrete-lined shafts, 19 feet 1 inch in diameter and 2500 feet deep. No. 1 shaft, equipped with an "A" type head-

Jan 1, 1972

By Michael A. Redfearn

The use of nitrogen in molybdenite flotation circuits is a relatively new concept utilized by only a few mines around the world. This paper briefly discusses circuit chemistry and the reason for its success. It follows the entire testing process which resulted in a sodium hydro-sulphide dosage reduction from 18.5 to 4.4 lbs/ ton (9250 to 2200 g/t) through to the final installation of an inert gas generator which will produce reagent savings in excess of one million dollars annually. A description of the various types of nitrogen generators commercially available is included.

Jan 1, 1983

By N. Ripepi

"The Langmuir model has been widely used for the coal-methane sorption process via an isothermal test. However, even though the temperature-dependent Langmuir model were recognized theoretically and experimentally, the quantitative relationship between the Langmuir’s constants (a & b) and temperature have not been clarified and confirmed by lab test data. This paper collects 158 methane-coal sorption data under different temperatures, which apply the Langmuir model to consider the relationship between Langmuir’s constants (a & b) and temperature (see APPENDIX I). Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters (a & b). The results from these published isothermal tests confirm that 1) there is no consistent relationship between Langmuir’s constant-a and temperature; 2) the Langmuir model is a temperature-dependent model, and the temperature-dependent feature is mainly shown by the relationship between Langmuir’s constant-b and temperature; 3) The relationship between Langmuir’s constant-b and temperature can be described by both the exponential and linear relationship with dried coal. This paper provides a database for temperature-dependent Langmuir’s model, which can be used for reservoir simulation of coalbed methane reservoir, coal seam degasification modeling for underground coal mines considering the heating effect induced by geotherm and heat injection (via hot water, hot steam, ultrasonic, etc.). INTRODUCTION The isothermal test for gas sorption on coal is one of the fundamental tests in Coalbed Methane (CBM) recovery fields, such as underground coal mine methane degasification, CBM gas-in-place estimation, and carbon dioxide sequestration in un-minable coal seams. Generally, two methods, volumetric and gravimetric, are employed to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012). Based on these two approaches, a series of commercial and self-assembled instruments are built and several calculation methods are used to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012, Gasparik, K., 2014; Goodman, A. L., et al, 2004; Zhang, L., et al, 2013). In the post-processing stage, many models are provided to analyze isothermal data in order to understand the storage mechanism of gas in coal. Common models include the Langmuir model (and its extended forms), the pore-filling model, multilayer adsorption model (BET), and the Gibbs’ model. Among these models, the Langmuir model is the most widely used for its simplicity and functionality. The Langmuir model is expressed as follows:"

Jan 1, 2016

By William M. Gray

[The products of mites hive historically beet a very large and important segment of total shipment transported by American Railroads. Much as the Mining transportation Executives right have wished for coal and other mineral deposits to be found along navigable rivers, where railroads have for years been competing with the very aggressive Army Corps of Engineers and the inland waterway operators, the mineable reserves are more often that not located in the arid west far from these "free" waterways. The rivers cannot go to the mines but the railroads could, did, and continue to invest it new lines to reach new mines. The mining industry and the railroad industry have good reason to rely upon each other. The former Northern Pacific Railway, the Great Northern Railway, the Chicago, Burlington and Quincy Railroad and the Spokane, Portland and Seattle Railway merged in 1970 to form the Burlington Northern Railroad, with Lou Menk as its first President. As unofficial spokesman for the industry, be had, for years, conducted a tireless effort to educate shippers, lawmakers and the general public of the single most critical problem confronting the railroad industry, the strangle bold of government regulator.]

Jan 1, 1985

By R. M. G. Machunter

The presence of ultra-fine particles affects the separation performance of wet gravity separation equipment. Several studies have been undertaken to establish the maximum level of these particulates that can be tolerated by spiral separators and it has been found that unless the ultra-fine material is effectively processed, relatively low proportions in the ROM material combined with high feed rates can result in degradation in plant performance and/or excessive water consumption. The maximum level of particulate material in the process water has been determined by examination of separation performance of spiral separators under varying slime loading. This work has been conducted utilizing various feed sources and a robust ‘rule-of-thumb’ has been derived.

Jan 1, 2005

By R. J. Roman

The results of column leaching tests on 3 different mixed oxide/sulfide ores from a Chilean deposit are presented. The 3 samples contained different ratios of oxide copper minerals to chalcocite and chalcopyrite. The results of the column leach tests are interpreted in light of the shrinking core model for coarse particle leaching. The copper recovery from the oxide minerals and the sulfide minerals each conforms to the shrinking core model with the total recovery equal to the weighted average of the individual minerals. The use of column test results to predict field heap leaching results using the multi-mineral shrinking core model is discussed.

Jan 1, 1993

By A. R. Laplante

A novel methodology to estimate gold recovery by gravity is presented. The methodology makes use of a population balance model which represents gold liberation, breakage and classification behaviour and applies pre-concentration and recovery performance curves to gravity-recoverable gold to predict overall recovery. Derivation of the necessary parameters is explained and demonstrated using data from an actual gravity circuit and one projected application. The methodology makes it possible to estimate the performance of circuits with large gold circulating loads and relatively low unit recoveries (e.g. jigs), or with high recoveries on a bleed of the circulating load (e.g. Knelson concentrators).

Jan 1, 1994

By V. Gangrade, J. Addis, S. Vanderslice

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are conducting research to improve the ventilation of large-opening underground stone mines. The mine ventilation in these mines are characterized by: (1) challenges related to keeping airflow velocities high enough to effectively remove or dilute airborne contaminants, (2) low pressure losses needed to move large air volumes of air, and (3) costly stoppings needed to direct ventilation airflows. Each of two field studies was dedicated to specific focus areas. The first focus area was the characterization of underground mine ventilation airflow. The primary means of airflow control in stone mines is through the use of freestanding booster fans. The primary goal of this study was to identify the effectiveness of various fan types and optimize their placement. Both traverse and grid-based airflow readings were taken at various distances from the fans, ranging from 70 ft to 425 ft away from the fan. The air readings were taken using a vane-anemometer and a handheld hotwire anemometer. The data was used to develop precise computational fluid dynamics models. The second focus area was to determine diesel particulate matter (DPM) concentrations in the mine. For large-opening underground stone mines, controlling DPM exposures dictates the design of the ventilation system. Therefore, researchers carried out the DPM sampling campaign to identify potential areas of concern within the mine. The samples collected during the campaign were analyzed using NIOSH Method 5040. The sampling was done using the Mine Safety and Health Administration’s (MSHA) compliance sampling methodology.

Feb 1, 2023

By D. D. Harbuck

The U.S. Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent such as 502 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage counter-current leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with 502 or sulfuric acid.

Jan 1, 1991

By J. A. Rusnak, K. M. Mohamed, M. A. Van Dyke, M. M. Sears, G. Rashed

"Researchers from the National Institute for Occupational Safety and Health (NIOSH) recently developed a coal-mass model to realistically simulate the deformation and loading behaviors of the ribs of coal pillars in underground coal mines. The scale-dependent properties (stiffness and strength) of coal material were considered in the coal-mass model. In this paper the orientation of face cleat with respect to driving direction was integrated in the coal-mass model. The controlling parameters (dimensionless coal-mass scale and fracture strains) of the modified coal-mass model were calibrated using a published case study of coal pillar strength. Numerical models with wide ranges of controlling parameters were conducted to simulate the test pillar. The best match between the numerical modeling results and the measured stresses and deformations was achieved by using a coal-mass scale of 30 and fracture plastic shear and tensile strains of 3.25% and 0.325 %, respectively. INTRODUCTION The failure of coal pillar ribs by itself are a major hazard in underground coal mines. Furthermore, failing ribs can indirectly contribute to roof and floor instability by increasing opening widths across intersections and entryways. Over the past decade, rib failures have resulted in 12 fatalities, representing 28% of the ground-fall fatalities in U.S. underground coal mines. Mining depth has always played a very important role in assessing rib stability. Gauna and Mark (2010) completed an analysis of rib fatalities that occurred between 1996 and 2010. One of their most prominent and influential findings was the identification of a relationship among fatalities, depth, and mining height. Therefore, Coal rib stability will continue to be a challenge for future deeper mines in U.S. coal basins. In the past several decades, research efforts have focused on roof support. The current rib control practice in U.S. coal mines is to select rib bolts through a trial-and-error approach (Mohamed et al., 2015a). Rib failure incidents can be can be substantially reduced or even eliminated by adopting an engineering-based coal rib design approach. The factors affecting rib stability in coal mines are numerous and mutually dependent. These factors include but not limited to mining height and overburden depth, interburden thickness for multiple-seam mining, coal strength, cleat density, entry direction with respect to cleat orientation, existence or absence of partings in the coal, percentage of extracted roof and/or floor rock, density of rib bolt support (Mohamed et al., 2015a). Moreover, it is difficult to isolate the particular effect of a specific factor on the overall rib stability. Therefore, a reliable empirical rib design approach is not achievable because it requires a significant number of case histories to be collected in order to have a reasonable range of all of the critical parameters. However, numerical modeling can be a practical tool to assist with rib support design if the modeling is realistic, which can only be achieved through calibration and validation of the numerical model against field data."

Jan 1, 2018

By D. D. Runnells

In order to establish meaningful remediation goals and monitoring programs in areas disturbed by mining, it is desirable to determine the natural metals concentrations that existed in the area prior to mining. At Iron Mountain, California, several natural sources exist for acid drainage and loading of metals to Slickrock and Boulder Creeks. This paper describes methods to determine the contribution of copper and zinc to groundwater and surface water from those sources, including natural gossan rock outcrops, mineralized bedrock, and colluvial materials. Methods used include evaluation of: 1) historical information, 2) literature values of unmined, mineralized areas, 3) analyses of water from monitoring wells, 4) leaching studies, 5) statistical analysis, 6) isotopic studies, and 7) identification of background by elimination of mining sources. Results from this natural background determination show that Boulder Creek and Slickrock Creek carried elevated concentrations and loads of copper and zinc prior to mining activities. With repeated rinsing of reclaimed and remediated mine materials by rainfall, there will be a diminishing contribution from residual waste rock and tailings at Iron Mountain, and natural background will become an increasingly larger proportion of the total load.

Jan 1, 1999

By I. H. Gundiler

A pilot-plant flotation concentrate containing 21.6 g/t gold and 2 kg/t silver was used for this study. Base-line cyanide and thiourea tests showed 30-40% extraction of both gold and silver. After roasting (450-750C), the maximum gold extracted was 89% with thiourea and 76% with cyanide. Pressure oxidation tests were conducted following a statistical experimental design in a 2L laboratory autoclave at 10% pulp density, and the residues were subsequently leached in acidic thiourea solutions for 2h. Leach results were presented in the form of contour maps, and optimum autoclave conditions were determined for maximum gold extraction (93%). However, silver extraction was only 7% when gold extraction was maximized.

Jan 1, 1992

By W. Norman Sims

A number of forces are at work that are now having an influence on coal handling systems. Changes are occurring and will be occurring at an increasing rate during the next few years. 1. Environmental concerns will dictate that dust pollution and spontaneous combustion and its resulting problems be rigidly controlled. 2. Slurry pipelines will be a reality despite the opposition of the railroads because they are economical and make good business sense. Artifical roadblocks can only survive for a limited time. 3. Coal is now and will remain the most economic fuel, particularly for power generation. This is true in most of the developed nations not just the United States. Increase in demand requires a close inspection of transportation systems. 4. A projected major increase in the export of U.S. coals may never occur without major port developments not the least of which will be the ability to accommodate large ships without demurrage time now affecting such shipments at U.S. Ports.

Jan 1, 1982

By W. L. Freyberger

In many papers concerned with fundamentals of the froth flotation process, authors have considered the contents of a flotation cell to be comprised of two immiscible phases, the froth and the pulp. I (Of course, each of these phases is in turn made up of several solid phases plus air and water.) This generalized concept of the flotation system can be extended by considering the cell contents to include two phases: an extracting phase, the air bubbles plus the collector, which removes a selected mineral component from the second phase, the ore pulp. Thus, there is an analogy between a flotation system on the one hand, and chemical extracting systems, such a solvent extraction system or a leaching system, on the other hand. Such extracting systems may be operated in cocurrent or countercurrent fashion. This paper includes first a brief discussion on the general nature of cocurrent and countercurrent operation as applied to froth flotation, and then presents the experimental results of flotation of a specular hematite ore by each method, using a tall oil fatty acid as collector. Cocurrent Flotation A conventional flotation circuit involving roughing, scavenging, and cleaning flotation is illustrated schematically in Figure 1. In such a circuit the col¬lector, or extractant, and new feed ore enter together at the head of the rougher circuit, and flow cocurrently to the scavenger circuit where more collector is added. According to this practice, sufficient collector is added to the head of the rougher (and scavenger) so that the final tailings are of low enough grade to be discarded. Since the flow of collector and ore is cocurrent, the process consists of single stage contact between the extracting phase and the ore pulp. If the scavenger concentrate is recycled to the head of rougher, the overall circuit has some of the characteristics of countercurrent flow. In such a case part of the extractant (collector) is added at the discharge end of the circuit, and may

Jan 1, 1971

By J. Marsden

Lift height, overall heap height and climate all play an important role in determining precious metals leaching rates, recoveries, operating costs and capital cost requirements for heap leaching operations. The effects of these factors are not easy to predict from testwork, and this can result in unexpected delays in metal production, lower recoveries than expected and higher capital and operating costs than necessary. This paper investigates the economic impact of lift height, overall heap height and climate on heap leaching and provides criteria to assist in the design and operation of leaching facilities. Descriptions of three heap leach operations in the western USA are provided to support the discussions and conclusions.

Jan 1, 1995

By Chester O. Ensign

The White Pine Mine is situated in the southwestern portion of the Keweenaw Peninsula of Upper Michigan approximately 6 miles south of Lake Superior (Fig. 1). It is east of the Porcupine Mountains in Ontonagon County. The ore deposit is about 70 miles southwest of the famous native copper deposits of the "Copper Country" lying northeast of Houghton. Geological conditions are different at every mine and create a special set of problems in dilution control. This paper is largely intended to describe the techniques applied in mine dilution control (grade control) at White Pine, and present results of the program. For necessary background information major geologic characteristics of the deposit, particularly those that exert control over the distribution of ore, are briefly discussed. Mining methods are described in considerable detail since applied grade control techniques are adapted to these.

Jan 1, 1964

By T. A. Gray

The environmental liabilities of coal waste disposal sites can have a major impact on a mining project's economic viability. Developing a waste disposal site is no longer simply an exercise in completing paperwork to obtain a permit, with the proliferation of environmental regulations in recent years, managing disposal sites now requires design creativity, short term and long term planning and detailed monitoring to maximize the benefits to the mining company. Operating costs and future capital costs for expansion of existing sites, new site development and regulatory compliance should be reviewed periodically and considered in the overall management plan. This paper discusses various management methods that are being employed in the industry to improve waste disposal operations both environmentally and profitably.

Jan 1, 1994

By R. R. Klimpel

Over the last six years, several new commercial families of sulfide mineral collectors have been developed. This paper summarizes some plant data and use experiences gained with each of these product families. The first is a series of products (F-series) based on a chelation mechanism of attachment. The second of these families is a series of products (S-series) based on an electrochemically controlled mechanism of attachment. The major advantage of the F-series collectors is the very high metal recovery capability in complex ores involving Au, Pt, Zn, Ni, and mixed Cu minerals. The major advantages of the S-series collectors are the very high pyrite rejection capability along with reduced lime requirements in Cu/Mo plants.

Jan 1, 1995

By T. J. Crebs

The latest estimates compiled by the Society of Exploration Geophysicists again indicate a moderate increase in mining geophysical activity in 1980 over the 1979 level. While North American activity remained at above the 1979 level, a considerable increase in mining geophysics was reported in South America, Australia, and the Far East. The total worldwide expenditures for mining geophysics were reported to be $53.7 million in 1980, compared to $44.4 million in 1979, and $31.6 million in 1978. During 1980, approximately 2% of all dollars spent on geophysics were attributed to mining geophysical activities; this percentage has remained relatively constant in recent years. Airborne surveys accounted for 51% of the total worldwide mining geophysical expenditure, 43% was spent for land surveys, and 6% for borehole surveys. Within the US, the breakdown of expenditures for land surveys was 60% for elec¬trical methods, 23% for gravity and magnetic methods, and 17% for seismic techniques. Electrical techniques remain the primary exploration tool for US mining geophysicists. Electrical Methods With inductive or electromagnetic (EM) techniques, significant developments were achieved in both frequency-domain and time-domain systems. Work continued on increasing the signal level on most time-domain (TEM) methods, to increase the exploration depth. The Crone group increased the power of its Pulse ElectroMagnetic system (PEM) to a 20-amp transmitter-loop capability. The GEOEX group is modifying the SIROTEM II system to obtain larger transmitter amperage from a portable motor generator. Geonics developed a new digital recording system (data logger) for its EM-37 system. This development should increase the productivity of EM-37 crews. A new ground, frequency-domain EM system was developed by the Scintrex group. This novel Genie system does not require a wire link between the receiver and transmitter. Because an amplitude-ratio is measured, the Genie data are reported to be relatively insensitive to coil orientation and distance errors. This new technique does not need extensive line-cutting or accurate station-chaining and would appear to be a good reconnaissance instrument. Scintrex also began marketing the new IPR-11 induced polarization spectral receiver. This receiver is microprocessor controlled, and can output to a cassette tape and record 10 windows of secondary voltage decay simultaneously from up to six receiver dipoles. The Phoenix group's new 100 kW induced polarization/resistivity (IP/R) transmitter began tests using their IPV-3 multifrequency, multichannel receiver. While this unit was primarily developed for "oilfield" IP exploration research, it has obvious application to "deep" mineral exploration. The Phoenix group also developed a new remote-reference, real-time magneto-telluric (MT) device in 1981. This five-component MT sys¬tem has a frequency range from 0.0005-384 Hz. Helicopter-borne electromagnetic (HEM) developments also continued in 1981. The mining in¬dustry increased its use of the new Geonics EM-33-3 multifrequency, multicoil instrument. In 1981, the Dighem group developed software for estimating magnetite as a mapping parameter from its HEM system. Dighem's work is said to complement airborne magnetic intensity surveys, since the HEM estimate is independent of remanent magnetism and magnetic latitude effects. Gravity and Magnetic Methods Probably one of the most innovative techniques in geophysics in 1981 was the use of airborne gravity surveys for both mining and petroleum exploration. The Carson group is using a modified, shipborne LaCoste-Romberg platform in helicopters. Data accuracies to 0.5 milligal have been achieved by flying gridded surveys. Although this airborne method is expensive-up to $186/ km ($300/line-mile)-the geophysical community has been excited by initial results. On the ground, the portable proton-precession magnetometers are becoming sophisticated. Both GeoMetrics and EDA recently introduced field magnetometers having data storage and processing capabilities. This development should greatly increase the productivity of ground-magnetic surveys. Seismic Methods Development of high-resolution seismic techniques continued in 1981. These techniques have primarily been directed toward coal studies for fault detection. OYO Instruments introduced their McSEIS-1500 seismic data acquisition system in 1981. This device contains a 24-channel recording capability, with digital output to 256-kbyte floppy disks. The high-speed data transfer using the disk media is considered a desirable feature. Borehole Methods The general decrease in uranium exploration, where borehole logging is extensively used, probbly led to the overall decline of geophysical logging activity in the minerals industry. However, a number of new sondes and logging systems were introduced in 1981: • Mount Sopris recently introduced their Series III logging system. This microprocessor-controlled unit records up to four channels of data on nine-track or cassette magnetic tape. The logging package is relatively light-weight, so helicopter transport to mountainous or roadless exploration sites is possible. (Both the Edcon and Woodware-Clyde consulting groups offer "slinging" capabilities for their Mount Sopris units.) Mount Sopris is continuing work on their 500-mm-diam (2¬in-diam) spectral gamma-ray sonde. This tool is expected to be available soon. • Owl Technical "slim-downed" its successful digital deviation probe to 380-mm (1.5-in) outside diameter. This new sonde will also measure inclinations up to 80° from the vertical, as compared with its older instrument that could measure inclinations to 30°. • A magnetic susceptibility sonde was introduced in the US by the OYO Instruments group. This Kappalog sonde contains two aircored coils for measurements slightly affected by thermal changes within the borehole. The increased activity in massive-sulfide exploration and the need to "look" deeper no

Jan 5, 1982