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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 K. F. Unrug

Martin County Coal Corporation is located in Martin County, Kentucky in the Appalachian coal fields, near the West Virginia border. The total leasehold covers more than 33 000 acres. Total annual production at Martin County Coal Corporation is currently 2,500,000 tons, but in certain years exceeded 3,000,000 tons. Approximately 45 percent of the annual production comes from two surface mines. The balance is produced from five underground mines. Martin County Coal Corporation's work schedule consists of 240 days/year, two nine-hours shifts/day.

Jan 1, 1991

By M. A. Boucher

The purpose of my presentation is threefold: a) to make you aware of what is available in Canada in terms of refractory minerals. b) indicate the mineral deposits that have potential for development. c) show the advantages of Canada as a supplier of electrical energy necessary for the production of electrofused minerals. Canada is a producer of natural refractory minerals, electrofused minerals, and synthetic refractory minerals. Several deposits also have good potential for development. The natural refractory minerals produced in Canada are shown in Table 1. The major minerals by decreasing order of importance in terms of tonnage and values are: dolomite, graphite and magnesite.

Jan 1, 1992

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 K. Ueda

Lead concentrates from Kuroko (black ore) mines, which contain Cu 4 ? 7%, Pb 55%, Zn 3 - 7%, As 0.5 - 0.9% are treated by hydrometallurgical process in order to smelt the product by electric furnace smelting together with other lead resouces from Kuroko. The hydrometallurgical pretreatment involves sulfuric acid leaching at first stage, ferric leaching at second stage. This paper describes the short history of lead recovery from Kuroko and the performance of laboratory test, pilot plant and commercial operation.

Jan 1, 1982

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 S. Corrent, F. A. V. Guimarães, M. G. Barbosa

"INTRODUCTION Moisture can be a villain, so new technologies have been explored to make more viable the production of high moisture iron ores. The current work presents the attempt of the utilization of a superabsorbent polymer (SAP) to aid in the screening process and in the ore handling process, such as stockpiles reclaiming and vessels/trains discharge in sub-zero temperature conditions. The results have shown that the polymer can be used in certain cases to improve productivity and increase safety in the process of handling the material (by increasing the TML). However, for size separation no advantages were found upon the use of the polymers. WATER ADSORPTION MECHANISMS The use of water in mineral processing is constant as its utilization brings an increase in the efficiency of separation. Although we have better results in the processing with water, materials with a high content of “natural” moisture can be very difficult to be treated by the conventional methods of separation. Nowadays many studies have been conducted in order to understand the effect of adsorption of water in the particles of complex minerals. Those studies have being divided in many different lines of research such as contact angle of a drop of water and the surface of the mineral to determine hydrophobicity, the particle size distribution and the porosity of particles. Mainly two forms of adsorption of water by the particles are possible: one the water is retained inside porosity of the particles. Laboratory tests developed in China have showed that capillary adsorption is faster in coarser particles that achieve the saturation degree earlier than finer particles (Xuewei Lv et al., 2011). The so called non-porous model considers the effect of water in the bulk sample of iron ores, in a physical connection when all the water works as a binder between particles as shown in the figure 1.If we take into account the compressibility of the system and compaction due to the weight of the bed over the particles, the thickness of the water film between particles is the same but the volume inside different particle size systems is much higher than in a system with particles of same size."

Jan 1, 2018

By Pierre J. Goossens

Since Guild 1 and Snelgrove 2 attracted our attention to the relationships between certain endogenic ore deposits and plate boundaries, an abundant flow of papers appeared in the metallogenic literature concerned with this problem and its application to mineral exploration. Some of the papers only speculate with the formation of specific type of ore deposit 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 Other papers are more concerned with genetic and structural relationships between plate tectonics and mineralization 13, 14, 15, 16, 17, 18, 19, 20 They are philosophical, in that they are generalized and refer to no specific area. Yet it is true that a large part of the world mineral potential is concentrated at the convergence of oceanic and continental plates, for example, around the Pacific. Therefore, the interaction of two plates by either subduction, obduction or slippage likely has an important role for the genesis and/or the (structural) control of these "orogenic" ore deposits. If subduction is the driving mechanism for the generation of igneous rocks 21, 22 and endogenic ore deposits 18, volcanic activity and the nature of volcanic products certainly are the major geologic processes and events to be tested. Fonteilles 23 and Alsac 24 have already emphasized the important relationship between mineralization and the talc-alkaline affinity of the volcanics. The Andean orogen is one of the best areas for testing such genetic relationships. Rich and varied endogenic and volcanogenic ore deposits occur there and plate interaction is still active.

Jan 1, 1975

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 Thomas Konstantis, Spyridon Konstantis, Panagiotis Spyridis

"Tunneling and Underground works are unequivocally subject to a diversity of inherent uncertainties associated with the geotechnical, hydro-geological and environmental regime that surrounds them. On many occasions, these uncertainties can provoke loss events of considerable consequences. The present contribution elaborates on losses that the insurance market has suffered in the recent years, following a construction failure event. These losses are being considered and analysed on a quantitative basis through evaluation of cost related data, with explicit discretization of the applied construction methodology and of the subsequent developed failure type since both of which are considered of major importance. Given the identified persistence and regularity of some loss-contributing factors, recommendations are provided on the basis of a proactive risk engineering management approach that are envisaged to reinforce the understanding of project risks and alleviate the incurred insurance cost. 1 INTRODUCTION The underground construction sector has always been a very challenging area for all involved parties, including the insurance market. Main reason for that remains the uniqueness of the uncertainties sources and the subsequent inherent risks that the tunneling and underground projects are exposed to. In many instances, these risks materialize, leading to loss events with substantially high impact on reinstatement cost and incurred delays, which depending among others on the insurance coverage will have to be bared by the Insurance market. In the recent decades and as the tunneling industry boomed and expanded with many major and significant projects undertaken around the world, the insurance market was faced with additional challenges. Increased competition during tender coupled with the scale and complexity of the projects and politically driven decision making exerted pressure on the project timelines, completion dates and budget. The pressure for on-time or even early project completion- to avoid liquidated damages or achieve bonus payments, respectively- along with cost reduction efforts and the incentive for innovative failure events. That, in turn, put additional pressure on the Insurance market which had experienced a significant amount of losses with substantial cost. One of the triggered mitigation actions was the introduction of the Code of Practice for Risk Management of Tunnel Works (ITIG, 2006 & 2012; MunichRe 2006, Wannick, 2007, Spencer, 2008, Adeyemo, 2011)."

Jan 1, 2016

By J. B. Platt

Many utility fuel choices 1990-95 defied expectations, with utility decisions and coal market developments ever more closely linked. The Central Appalachian coal boom never occurred; clean-enough coal was developed in the hard-hit Midwest; Colorado-Utah coal surged; Pittsburgh seam production strengthened; utilities embraced Powder River Basin coal; and emission allowance prices collapsed. Competition drove productivity gains, but the future is not a simple repeat. Phase 2 brings fewer viable compliance options. Mega-railroad pricing has become a key risk factor --will this be countermanded by merging utilities and power market competition? Revenue losses from vintage contracts are problematic. Uncertainty also plagues natural gas, in spite of unanimity across major forecasts, since recent experience has been so heavily influenced by the gas bubble.

Jan 1, 1997

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. 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

Careful financial analysis of capital investments has always been a vital task in mining which is one of the most capital intensive sectors of the economy. Furthermore, mining costs have leapt ahead at an astonishing rate in recent years not just due to accelerated inflation, which affects everyone, but also due to the imposition of enormous costs of enviromental regulation and the continuing decline in ore tenor. Not only have unit costs risen, but the amount of effort expended to recover a pound of metal has increased due to the inexorable decrease in ore grades. New low-margin, high-volume mining investments place increasing importance on sound financial planning. Owing to the enormous investments involved, a greater share of individual corporate resources is committed to these projects than is normally the case in other industries. Thus, the consequences of failure are extremely grave, and a close examination of all inputs to the evaluation equation is clearly indicated.

Jan 1, 1979

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 W. H. Langer

Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix, Arizona, is mined and processed to provide aggregate to the greater Phoenix area. The alluvium occurs as three distinct, stratigraphic layers. Samples from each of the three layers were examined for gravel clast lithology, grain size distribution, and engineering tests, which revealed noteworthy differences in properties. The engineering properties of the gravels are dependent on a combination of factors including gravel clast lithology, the distance the gravel clasts have been transported from their source areas, the age of the deposits, and the degree of weathering. Knowledge of these characteristics may affect the methods that aggregate operators employ to extract and process gravel from the Agua Fria River.

Jan 1, 2010

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 R. Mensah-Biney

The loading characteristics of gold-tetrabromide species onto activated carbon have been evaluated using a completely mixed batch reactor system. The overall loading of gold onto carbon was rapid for the first hour but continued slowly without cessation as a result of reduction of gold. Conventional equilibrium considerations were therefore not applicable. Although loading continued slowly after several days, abnormally high loading capacity values of 10-12 meq/g carbon (650-800 kgAu/tonne) could be attained within 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of [AuBr4l-onto the carbon surface where reduction to metallic gold took place. Elution of gold from the loaded carbon was feasible provided the carbon had not been loaded to too high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon is discussed.

Jan 1, 1992

By J. A. Domenico

A safe and precise mineral separation alternative to heavy liquids is being used for mineral sands exploration on large scale orebodies. The separation process, Magstream®, uses ferro-fluids and magnetic and centrifugal forces to produce precise split points over a range of specific gravities from 1.5 to 18.0 g/cc. This paper describes a commercial scale exploration program treating, roughly, 90 samples per day in Senegal (West Africa). Separation results comparing Magstream® and conventional heavy-liquid separation are presented.

Jan 1, 1994

By C. C. Jobes, J. J. Sammarco, D. L. Anderson

Computer-aided control of a mining machine places its operator in a safe, remote location, thus reducing health and safety risks. Sensing systems that provide machine position (xy coordinates) and heading (yaw) are extremely useful in aiding remote positioning of mining machines. The US Bureau of Mines (Bureau) developed two sensing systems for position and heading information: a scanning laser system based on the Lasernet sensor and a mechanical position and heading system based on linear-position transducers. The Bureau is also investigating a system from Honeywell, the modular azimuth and positioning system (MAPS), that employs ring-laser gyroscopes (RLGs). This paper presents a brief background and status of these sensing systems as applied to a continuous mining machine (CM). Included are field test results off each system operating in a room-and-pillar research section at a cooperating West Virginia mine.

Jan 1, 1993