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By Yousef Ghorbani, Jafar Abdolahi Sharif, Fatemeh Kazemi, Ataallah Bahrami

Kinetic models are the most important tool for predicting and evaluating the performance of flotation circuits. Gilsonite is a natural fossil resource similar to an oil asphalt, high in asphaltenes. Here, in order to determine the kinetic order and flotation rate of a gilsonite sample, flotation experiments were carried out in both rougher and cleaner stages. Experiments were conducted using the combinations of oil–MIBC and gas oil–pine oil, with one test without collector and frother. Five kinetic models were applied to the data obtained from the flotation tests using MATLAB software. Statistical analysis showed that the results of the experiment with oil–MIBC were highly in compliance with all models. Kinetic constants (k) were calculated as 0.1548 (s−1 ) and 0.0450 (s−1 ) for rougher and cleaner stages, respectively. Rougher and cleaner tests without collector and frother also matched all models well (R2 > 0.98), with k values of 0.2163 (s−1 ) and 0.284 (s−1 ), respectively. The relationship between flotation rate constant, maximum combustible recovery, and particle size showed that the maximum flotation combustible recovery and flotation rate were obtained in the size range of −250 + 106 μm in the rougher and cleaner stages. The combustible recovery and flotation rate were higher in the rougher flotation process than in the cleaner stage.

By GEORGE D. RAMSAY

ABOUT three miles west of Fontana San Bernardino County, California, and fifty miles east of Los Angeles, the Kaiser Co., Inc., has built an integrated steel plant. By integrated, I mean that from its wholly owned iron ore and coal supply, the Kaiser Co. is producing in its own mills iron and steel products. Pig iron to meet the West Coast needs has been produced at Fontana since Jan. 1, 1943; steel ingots were first poured there May 14, 1943; and steel plate for ships was first rolled Aug. 15, just sixteen months after ground was broken. Briefly, the plant consists of: (I) Two batteries of by-product coke ovens, totalling ninety ovens, carbonizing about 1740 tons of coal per day at capacity; with by-product facilities for the production of tar, ammonia, and ammonium suIphate, light oil distillates, and tar distillates. (2) One blast furnace producing at

Jan 1, 1944

By A. Takala, H. Cline, D. Girard

"This article describes the project development and successful implementation of a particle sorter at the Kensington mine. The Kensington underground gold mine and associated milling facilities are located within the Berners Bay Mining District on the east side of Lynn Canal about 45 miles north-northwest of Juneau, Alaska. The paper describes the project from concept, through the development phase, including test work confirming feasibility, to a discussion of operational data and includes shared experiences from operation and maintenance. The project has proven successful in recovering gold that was previously lost to the waste dump and has already resulted in a positive return on investment. The payback was achieved in less than one year.INTRODUCTION The first paragraphs of this paper describe Coeur Mining and the Kensington Mine, its history, geology, mining operation and mill. The second part of this paper gives a quick introduction to sensor-based sorting in general and X-ray transmission sorting (XRT) in particular. This article does not cover costs or economic impacts apart from the pay-back period for the investment at Kensington. Interested readers find more in information on this in the literature (Kleine & Wotruba, 2010; Robben, 2013). Since the publication about XRT sorting at TGME in Pilgrim’s Rest (Kleine, Riedel, Ketelhodt, & Murray, 2010), this is the first time that a comprehensive data set on gold ore sorting using XRT is published. Following chapters highlight the aim of the project for Coeur Kensington, project development through testing and operation before concluding. ABOUT COEUR MINING’S KENSINGTON OPERATION Coeur Mining is the largest U.S.-based silver producer and a significant gold producer with five precious metals mines in the Americas employing approximately 2,100 people. Coeur produces from its wholly owned operations: the Palmarejo silver-gold mine in Mexico, the San Bartolomé silver mine in Bolivia, the Rochester silver-gold mine in Nevada, the Kensington gold mine in Alaska, and the Wharf gold mine in South Dakota. The Company also has a non-operating interest in the Endeavor mine in Australia in addition to royalties on the Cerro Bayo mine in Chile, the El Gallo complex in Mexico, the Zaruma mine in Ecuador, and the Correnso mine in New Zealand. In addition, the Company has two silver-gold feasibility stage projects—the La Preciosa project in Mexico and the Joaquin project in Argentina. The Company also conducts ongoing exploration activities in Alaska, Argentina, Bolivia, Mexico, and Nevada. The Company owns strategic investment positions in several silver and gold development companies with projects in North and South America."

Jan 1, 2017

By L. S. Harner

This paper which describes the milling practice at the Golden Cycle mill is one of a series of similar papers being prepared by the United States Bureau of Mines. The mill of the Golden Cycle Corporation, formerly known as the Golden Cycle Mining and Reduction Co., is located at Colorado Springs, Colorado, and has been operated since 1907. It is now and has been from its inception almost exclusively a custom mill.

Jan 1, 1933

By S. Gajardo, E. Valdés Guerra

Together with Sociedad Punta del Cobre S.A. (Pucobre) and Orica, we are carrying out a study of alternatives for methodology of excavation in Slot Up Raises from actually built with Blind Hole (BH) to drilling and blasting (DB) methodology. The study is part of the permanent search for innovation, the use of technology and the reduction of mine operation costs. This application aims to optimize the Sub Level Stoping method, which has historically been exploited at Pucobre. Using a new variant of the method “Open Stoping”, through the initial development of ascending blind raises using a pilot drilling of a bore hole, with the objective of eliminating the upper level in order to excavate the free face opening. This industrial test aims to replace the mechanized BH Up Raise of 1.5m (4.9 ft.) in diameter and 30m (98.4 ft.) high, with a Up Slot Raise considering two separate blasting events, using different technological enablers, as detailed below: accuracy drilling with relief holes of 254mm (10 in.) diameter, high viscosity bulk emulsion, wireless initiation system and high-strength injectable bulk resin. Considering the importance of the success of this application, a DB diagram was defined to allow the opening of the up raise in two blasting events, separated by intermediate stemming deck located at the same level at a height of 15m (49.2 ft.) from the collar, using high-strength injectable resin. The first blasting event considers the first section from the collar to the first 15m (49.2 ft.), using wired electronic initiation that is detonated on the first day. A second event blasts the section from 16.5 to 30m (54.1 to 98.4 ft.), using a wireless initiation system, as, it has no physical connection, is blasted on the second day after the extraction of the material resulting from the first event. For greater precision, the design of the explosive charge configuration and initiation sequence is made, adjusted to the measurements of trajectory deviations of the actual ground drilling and is also considered for the control of the explosive charge configuration with high viscosity bulk emulsion. This application improves the profitability of the mining business by generating savings through the change of Blind Hole methodology, estimating a savings of more than 75% per Up Slot Raise

Jan 1, 2024

By H. A. Kramer

The Flin Flon mine is at present hoisting 5,000 tons of ore daily. In 1943, a peak production of 6,188 tons daily was maintained. Before discussing secondary blasting, it is felt that a short review of stoping procedure will be of value. A list of papers dealing with various phases of the mining operation is appended. Stoping Practice Stopes vary in width from 30 to 150 feet, in length from 200 to 450 feet, and in height from 200 to 500 feet. A typical stope would be 300 feet long, 300 feet high, and 90 feet wide. The dip of the orebodies varies from 60° to vertical, with an average of 82°. The ore is heavy, having a specific gravity of 4. Both sub-level benching and radial drilling are practised. Blast-hole diamond drills are responsible for 85 per cent of the total production. Two sizes of hole are drilled at present, 11 7 6 -inch and 1%-inch. For bench drilling, the burden on the 1 7/16-inch hole is six feet, with holes on 8-foot staggered centres; in radial drilling, the burden is six feet, with nine feet between the toes. The burden on the l 5/8-inch hole is eight feet with holes on 11-foot centres, or 13 feet on the toe of fanned holes. Holes are blasted with two No. 8 instantaneous electric caps per hole, using 403 Polar Forcite. A powder charge of 0.15 pounds per ton is used, with a tonnage factor of 5 and 6.4 per foot drilled for the two sizes. Two rows of holes are blasted together. Fragmentation is satisfactory with the above drilling pattern and powder charge. However, some overbreak and fall-off locally results in oversize material. It is estimated that, after primary breaking, 75 per cent of the ore will pass through the grizzly openings and 15 per cent will pass the draw points, leaving 10 per cent that must be broken further to pass the draw points.

Jan 1, 1946

By W. S. Sanner

This report describes the commercial application of the launder screen in anthracite-industry fine-coal cleaning operations. No new device, the launder screen has been used since the early part of the present century to size, screen, classify, and deslime the fine-anthracite sizes (Buckwheat Nos. 1 through 5) recovered by "river-coal" men dredging along streams draining the anthracite fields. The launder screen is stationary, has no moving parts, requires ample water for operation, and can be constructed economically on the job. Essentially, it consists of a wooden trough with baffles placed through its width to form a well system. The wells are covered by fine-mesh woven-wire screening. Each well is tapped with a number of orifices, and the hydraulic suction head developed in this manner removes high-gravity fines and slimes through the screening as underflow to waste. Material retained on the screen surface discharges as overflow product.

Jan 1, 1954

By C. J. Beyke

The U.S. Bureau of Mines has developed a process for the selective recovery of Pb metal from a mixed Pb-Zn concentrate. The concentrate was leached in recycled H2SiF6 at atmospheric pressure and 95° C with a redox potential of 570 mV (Eh). Eighty-five pct of the Pb was selectively leached from the concentrate while 87 pct of the Zn remained in the residue. Pressure leaching of the concentrate was slightly less successful, with 78 pct of the Pb leaching from the concentrate and 80 pct of the Zn remaining in the residue. Pure Pb metal was successfully electrowon from a purified PbSiF6-H2SiF6 solution with 96 pct current efficiency and 0.69-kW.h/kg energy consumption.

Jan 1, 1991

By T. C. Bibb

Longwalls using shearers in seam heights of less than 1.2 m (48 inches) are relatively rare in the U.S. Westmoreland Coal Company is currently operating a shearer-equipped longwall at a cutting height of 1.17 m (46 inches) in its Bullitt Mine. This face has averaged 2795 metric tons/day of operation since its startup on April 3, 1984. Longwall productivity in thin seams is substantially impacted by equipment reliability and availability of useable working room for travel and access. This paper addresses the design criteria used in selecting this face equipment, with the goal of maximizing these two parameters. Equipment discussed includes shearers. face conveyor, shields, stageloader, and emulsion system.

Jan 1, 1985

By James J. Snodgrass

The Bureau of Mines designed and constructed a series of calibration models for geophysical borehole logging. A nominal hole diameter of 3 inches was selected as representative of typical core holes drilled for mining and engineering purposes, although additional hole diameters of 2, 5, and 8 inches are provided in one of the models for determination of empirical correction factors for variations in hole diameter. The physical properties of the models were determined by laboratory analyses of drill core samples and evaluated statistically for reliability. This report outlines the location of the models, elements of design and construction, and results of the laboratory tests. The models are available at the Denver Federal Center, Denver, Colo., for use by Government agencies and private industry to calibrate logging equipment for measurements of density, sonic velocity, magnetic susceptibility, and electrical resistivity.

Jan 1, 1976

By Xiaoqiong Wang, Daobing Wang, Fanbao Meng, Jianbo Wang, Hongkui Ge

"Shale gas has become an important unconventional oil and gas resources. Its effective development relies on comprehensive and accurate understanding of shale gas reservoirs. Rock mechanical properties is one of the important components of reservoir evaluation. Two adjacent black shale samples, which are cored from the depth of 1145 meters in Chongqing, southwest China, are subjected to acoustic emission(AE) test under uniaxial stress and compared with coarse grained granite. The results of synchronous AE, stress-strain and ultrasonic velocity experiments show that shale has weak anisotropy. Compared with granite sample, two shale samples are similar, but their strength, velocity and brittleness are quite different, indicating that shale has strong microscopic heterogeneity. TOC, XRD, SEM microstructure analysis show that total organic content, mineral composition and natural fractures are the main impacting factors for mechanical heterogeneity. INTRODUCTIONShale gas is a typical low-grade marginal resource, which is characterized by ultra-low matrix permeability and small single well control volume. In order to enable commerical development, complex hydraulic-fracture networks must be created in the shale to allow gas to escape from the micro/nano-pores and natural fractures where it is trapped in the rock (C. Clark et al.,2013; Ge et al., 2013). The development of shale gas requires accurate evaluation methodologies to evaluate shale reservoir properties and predict production. (Jarvie et al., 2007). Rock mechanical properties are an important part of the reservoir evaluation. It is significant for efficient drilling, completion and hydraulic fracturing to understand mechanical behavior of shale gas play (John, 2011; Wei, 2013).Rock mechanical properties mainly include heterogeneity, anisotropy, brittleness and acoustic emission activity (Lockner et al., 1992; Jerome et al., 2009; He et al., 2010; Liang et al., 2012). Shale mechanical properties are evaluated from laboratory tests following a complex workflow that covers tasks from sampling to testing (Md. Aminul Islam et al., 2013). It is common to include various experimental methods such as stress-strain curves, ultrasonic velocity and acoustic emission when evaluating the mechanical properties (Rao et al., 2006). Because of the presence of organic-rich matter, mineral composition orientation and natural fractures, shale tends to have strong anisotropy and heterogeneity (Deng et al., 2004; Wang et al., 2013; Hathon et al., 2013)."

Jan 1, 2015

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By R. S. C. Smart

Surface chemical factors, including the balance of hydrophobic (e.g. collectors) and hydrophilic (e.g. oxidation products, precipitates) species, are major control determinants in flotation rates of specific minerals and therefore grade and recovery. There are a number of challenges involved with the surface analysis of different mineral phases from process streams in a flotation facility. The first is to collect samples that are representative of the process and retain their surface chemistry prior to introduction into the instrument. The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles, confident mineral selection can be difficult with many multi-metal minerals and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers. The third challenge is to provide a statistical surface analysis of multiple grains of the same mineral. Methods to achieve these aims are described. Principal component analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. Specific examples from both lab and plant operations, demonstrate that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation. A study of copper ion transfer (inadvertent activation) from chalcopyrite to pyrite and sphalerite clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases corresponding to their flotation response. The PCA analysis applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between chalcocite and heazlewoodite minerals. The statistical analysis has been able to identify mechanisms controlling recovery and selectivity. High intensity conditioning (HIC) tests in which sphalerite was separated from a complex sulfide ore gave a 5% increase in the overall Zn recovery. The PCA/ToF-SIMS statistical analysis revealed the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. HIC conditioning resulted in the removal of these gangue fines improving surface collector attachment efficiency.

Jan 1, 2014

By J. P. Capp

This experiment, one of a series on underground gasification of coal, was an investigation by the Federal Bureau of Mines of hydraulic fracturing as a means of increasing the air acceptance of a coalbed to permit introducing combustion air and removing product gases. Specific objectives of the investigation included: (1) Fracturing a coalbed; (2) determining the distance the coal was physically affected; (3) ascertaining the effect of the fracture on air acceptance of the coalbed; and (4) gasifying the coal. The coal was fractured with a fluid consisting of 15,000 lb. of sand mixed with 10,000 gal. of fuel oil and 5,000 gal. of kerosine, injected at pressures up to 900 p.s.i.g. and rates up to 425 g.p.m. The oil served as the fracturing medium, and the sand as a propping agent to hold the fracture open. From the fracture point, (the place in the bed where the fluid was injected), the fracture extended 200 ft. or more along the face cleats, somewhat less along the butt. cleats, and was confined to the coalbed. At the fracture point, the bed accepted about 500 std. c.f.m. of air, which was an etghtyfold increase. Fracture effects were extensive, as airflow was noted from old mine workings and outcrops 600 to 800 ft. from the fracture point. It is probable the actual fracture was much less than 600 ft. and that normal coalbed permeability beyond the fracture limits was responsible for this flow. This indicated that effects of the fracture extended beyond the area of coal physically affected. Although no attempt was made to gasify coal more than 200 ft. away, these effects plus the natural permeability of the bed likely would permit combustion beyond the outer limit of the fracture. As these experiments continued for more than 2 years, and greater air acceptance due to the fracture was observed at the beginning of each test, it is apparent that the effects of the fracturing persist for a considerable time.

Jan 1, 1960

By Richard L. Gordon

At almost no time since the end of World War I has the coal industry been free from serious threats to its competitive position. At present, the critical question is whether the industry can maintain its position in the electric power market and this paper reviews the prospects in this area. Our report is part of a study, supported by Resources for the Future Inc., dealing with coal demand in general. Like most elements of coal economics, it has received much less analysis than problems in other energy sectors--a defect we felt worth correcting. We have concentrated on electric power elements of the market. The nature of the coal market makes this the natural choice. Three markets absorb over 80 per cent of coal production and are considered in our overall work. The completely excluded sectors are largely catchall categories in which coal use is declining anyway. Comparing the three markets included in the overall study, we see: modest growth is the most optimistic forecast for metallurgical coke; export growth depends to a large extent on policies of foreign governments. Electric power use, however, has rapidly grown to absorb over half of coal output and coal's prospects depend almost entirely on continued expansion of this market. Throughout the 1960's the demand for coal used to generate electrical power in the United States grew at an average rate of 6.5 per cent annually. This growth rate will be sustained until at least 1976.

Jan 1, 1971

By O C. Aitken

Mining project developers are committed to taking on all the challenges and obligations of financial risk management. It is interesting that our current models of project finance have not changed markedly in principle for some 700 years, yet the rules which prepare the way for effective project assessment and subsequent loan management still do not seem to be well understood by project or corporate developers. Probability and gravity fill the opposing trays of the golden balance of financial risk. Understanding the relationship between these opposing, but intimately related elements is critically important for successful risk management. It is important to move beyond the qualitative approach and use quantitative methodologies to measure the financial impact of the occurrence of each major risk. We live in a world where the only constant is change and thus it is not surprising that a bankerÆs life is still governed by assessing, measuring and pricing risk. Banks are attracted to funding well managed companies with strong cash flow projects. But we are more risk averse compared with the credit appetites of late last century. This attitudinal shift has resulted in tougher term sheets for the early 21st century, encompassing more conditions, warranties, undertakings and stronger cash sweep provisions. Banks require well balanced portfolios to achieve an acceptable spread of risk, thus there is a more restricted market for small company lending than that available to large multi-project corporate entities with less concentrated risk profiles. Because of this focus, junior company debt finance remains comparatively expensive and especially so for more challenging geographical and political environments.

Jan 1, 2004

By R J. Hardy

The aim of this study is to examine the volumetric and mass movement characteristics of load and haul operations using statistical modelling of relatively large samples of bucket loads that are transported as small samples in the form of truck payloads. Generally, the factors influencing bucket load variability are random, difficult to predict and to control. In the process of loading trucks the underlying variability of individual bucket loads will determine the variability of truck payloads. Bucket loads of material prepared by drilling and blasting for loading into trucks are fundamental quantities in open pit mine production. A study of payload data from a large surface mining operation indicates that bucket loads and truck payloads that are a small sample of bucket loads are normally distributed. Truck payloads have a reduced dispersion compared with bucket loads that is an inverse 0.5 power function of the number of passes per truck payload. Comparison of statistical modelling results with the æ10/10/20Æ policy promoted by Caterpillar Global Mining Inc, indicate that compliance with the æ10/10Æ part of the policy, applying to truck overloading is facilitated, as the coefficient of variation of truck payloads decreases, as a result of the increasing number of loading passes. Compliance with the more stringent æ20Æ part of the policy, relating to safe steering and braking is also facilitated, albeit at lower coefficient of variation for similar reasons.

Sep 26, 2011

By Q. G. Reynolds, R. T. Jones

The choice of furnace design parameters has a marked effect on the integrity of the furnace that is constructed. The design methodology for DC arc furnaces typically begins with the chemical reactions and feed materials that define the process. The specific energy requirement of the process, and the feedrates of the raw materials largely determine the power requirement for the furnace. A chosen value for the 'power intensity' sets the diameter of the furnace. Justification is provided for why this is a good choice of scale-up parameter. Equations are presented to quantify the resulting trade-off between thermal efficiency and the degree of error that can be tolerated in the balance between power and feedrate. This improved understanding should provide a better rationale for selecting an appropriate power intensity (or furnace diameter) for future furnaces.

Jan 1, 2015

By Paul T. Allsman

This paper gives the cost and describes the mining of 55 tons of nickel-bearing rock by hand methods from a prospect in southern Nevada, June 15, 1937, by the Mining Division of the Bureau of Mines. The geology, mineralogy, and problems related to future development also are discussed briefly. The main object was to obtain a 55-ton sample within the limited period during which funds were available; little time was available to make a first-hand detailed study of the possibility of commercial ore deposits being found. The sample was desired by the Metallurgical Division of the Bureau for experimental purposes at the Electro-Metallurgical Station at Boulder City, Nev. The term "ore" is used loosely in the following discussion to designate dike material containing nickel and copper, without consideration of its commercial value. ACKNOLEDGMENTS Material concerning the geology and mineralogy of the prospect and district as obtained from Geological Survey publications by Bancroft3/and Longwell4/.

Jan 1, 1938

By David M. Kjos

Large diameter autogenous and semi-autogenous grinding mills represent the primary thrust of the expanding grinding technology. In spite of initial difficulties, large autogenous and semi-autogenous mills have reached an acceptable level of technology which provides the mineral engineer with a reliable, low cost means of ore comminution. A successful milling installation begins during the design stage of the grinding mill and the plant it is to be installed in. This is particularly true in autogenous and semi-autogenous mills. Critical mill and plant design factors should be considered while the mill and installation are still only ?paper.? Various current liner designs will be discussed ranging from lifter bar/plate to integral types. Modes of operation such as "high-low" will be considered. Liner maintenance procedures ranging from laydown area in plant design, proper mill shutdown methods, to installation and bolt tightening complete the equation to yield optimum performance possible for any particular grinding application. The objective of this paper is to discuss trends in wear materials, designs and operating practices, and provide some guidelines for good practice as we move through the 1980's. We will put together concepts that relate to the designs, materials and applications so that higher performance can be obtained by the operator for his specific application. The concepts are shown as being in series because they are dependent on each other to achieve the desired performance.

Jan 1, 1985