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By R. L. Wolfrom, R. Hogg, S. Chander

A gravimetric method for measuring rates of capillary rise in powders was explored. Methods to improve reproducibility and consistency of the results were investigated. In particular, the effects of particle size and packing uniformity were addressed. Studies of the wetting behavior of both spherical glass beads and irregularly shaped synthetic graphite particles by various organic liquids were carried out. Standardized procedures for bed preparation will be described. The applicability of the Washburn equation for surface energy evaluation in such systems will be discussed. Key words: Wettability, Powders, Capillary rise, Surface chemistry

Jan 1, 2003

By F. Dakubo

"Solvent extraction of copper pregnant solution (PLS) obtained from ammonium peroxodisulfate assisted leach was modeled using response surface methodology. Mixing speed, pH, reagent concentration and organic to aqueous (O/A) ratio were selected for testing. A pitched blade mixer was used in the experiment. Mixer speed contributed significantly to copper extraction significant, while pH had minimal effect on copper extraction. The response model developed has an R2 = 0.97 and Adeq precision of 28.3. A parallel kinetic comparing study using a straight blade Rushton turbine in a turbulent regime of mixing showed no difference (p-value =0.308) between peroxodisulfate assisted leach PLS and conventional ferric/sulfuric acid leach PLS- the power draw data support this conclusion. INTRODUCTION High arsenic chalcopyrite concentrates are a problem to the smelters all over the world due to high arsenic gas emissions during smelting. Therefore leaching is often the alternative for extracting the copper in these concentrates if dilution with low arsenic concentrate is not possible. High-pressure autoclave leaching is used. Alternatively, the use of stronger oxidants such as peroxodisulfate has been proposed [16, 18]. There is a concern brought up by the hydrometallurgy community about the faith of the organic extracting reagent coming into contact with stronger oxidant residue in the pregnant leach solution (PLS) and hence the efficiency of such extraction process. This work, therefore, looks to answer such concerns. PLS generated from leaching of chalcopyrite concentrate with the peroxodisulfate ion was used in this solvent extraction experiment. As a liquid-liquid extraction, solvent extraction involves contacting the aqueous PLS with organic extractant via mixing. Mixing is known to increase the interfacial area for mass transfer by decreasing the diffusion path length (Jussi et al.1997). EXPERIMENT Instruments and Reagents Reagent grade Acorga 5910 reagent was used in the experiment was supplied by Cytec (Current name Solvay), Ammonium peroxodisulfate and sulfuric acid were reagent grade obtained from Amazon. Apparatus The solvent extraction tests were carried in a 2000 ml plastic cylindrical reactor equipped with four 0.5” baffles. In the hypothesis test, the reactor was a 4000 ml cylindrical reactor with four 1” thick baffles arranged evening in the reactor. Comparison between peroxodisulfate and ferric leach PLS via hypothesis test"

Jan 1, 2018

By Robert C. Peddicord

Application of Quality Management philosophies and techniques commonly referred to as Managing for Continuous Improvement, Team Management , or Managing for Consistency is required in today's mining, manufacturing, and service industries in order to meet quality demands, beat competition, lower costs, optimize operations, effectively use personnel, improve morale, and enhance profitability. Most of these phiosophies and techniques are known to today's managers but either have fallen into disuse or were never allowed to surface in the corporate environment of the organization. Managers should review and adopt the philosophies and techniques of Quality Management and use them to revitalize their organizations and bring about a "paradigm" shift in the way we manage, thereby achieving the goals listed above.

Jan 1, 1991

By William P. Lorenz

The paper describes a uranium by-product recovery plant operating within a copper leach, solvent extraction, and electrowinning circuit. The operation is unique because it is integrated into the main process stream of the copper circuit The plant processes 1408 m3/h of copper solutions containing about 10 mg/L of uranium. An Eluex type process was selected due to its compatibility with the copper leach plant. The paper includes an overview of the copper circuit

Jan 1, 1983

By Fernando Concha, Arturo Barrientos

The flow in a hydrocyclone is divided into a boundary layer around the walls, an exterior inviscid flow and an air core in the center of the equipment. The boundary layer flow over the lateral walls is associated with the short circuit of particles to the underflow, while the boundary layer over the top of the hydrocyclone and the outer part of the vortex finder tube is related to the short circuit of particles to the overflow. Classification takes place in the exterior flow. The model can be validated with pilot or industrial data and simulates the performance of hydrocyclones in a wide range of design and operating variables.

Jan 1, 1992

By Jianmin Qin, Raja V. Ramani

In this paper, the results of a research study on airborne dust transport in a full scale simulated longwall face are presented. The simulated longwall face was set up in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines to conduct experiments under controlled conditions. The controlled parameters in the experiments were the dust dispersion rate, dust size distribution, density of the dust, air velocity, and the rate of travel of the dust generating source. The analyses of the experimental results on mass concentrations, particle size distributions, and real-time respirable dust concentrations are discussed. There are definite spatio-temporal trends between the location of the shearer, the concentration at any location in the face, and the dust generation rates. The size-consist and density characteristics of the source dust, the air velocity in the face, and the air leakage into the gobs all affect the concentration.

Jan 1, 1995

By Bernard Lippe

The successful construction project is one in which the component construction operations are completed within the scheduled time and cost parameters. Most construction projects, however, are subject to delays and/or disruptions which adversely affect the time (start, duration, and completion) and cost aspects of the project. DELAYS Delays fall into two categories: Compensable Delays for which the contractor is entitled to contract time extensions and additional money as compensation for the extra expenses generated by the delay or obstruction to job progress, and Non Compensable Delays, for which the contractor may or may not receive an extension of time but no additional compensation. Compensable Delays Compensable delays may take the form of holds or suspensions on all or certain segments of a project by the owner, failure of the owner or his Engineers to approve shop drawings, cuts or material samples within a reasonable period of time, failure of the Owner or his Engineer to properly coordinate the job, discovery of design deficiencies in the plans and specifications which prevent the continuation of construction until

Jan 1, 1974

By H. Polat, B. Mohal, S. Chander

Several nonionic surfactants and one anionic surfactant were tested to enhance the flotation response of a low-rank coal. The nonionic surfactants included an ethoxylated octylphenol and several polypropylene-polyethylene block copolymers, and the anionic surfactant was a dioctyl sulfosuccinate. All of the surfactants improved the yield significantly, but the influence on grade was complex. To elucidate the mechanisms involved, separate studies were conducted to determine the emulsification behavior of the surfactants. For the nonionic water soluble reagents, a correlation between the emulsifying power of the surfactant and the flotation response was observed. An increase in the number of droplets produced was considered to he the main reason for increases in the yield. However, a small amount of surfactant adsorption on coal is essential to promote adhesion of oil droplets. When the surfactant was introduced into the flotation pulp prior to addition of dodecane, the benefits of the surfactant decreased significantly. The decrease was attributed to both a decrease in hydrophobicity of coal through increased surfactant adsorption and a decrease in the surfactant available for emulsification. When a surfactant dispersed in oil was used, the transfer of surfactant to the aqueous phase was minimal, and a considerable increase in yield was observed.

Jan 1, 1995

By K. Biswas, S. J. Jung

Health and safety of workers in mineral industry in the U.S. is still a vey important issue as Mining along with Agriculture, Forestry and Fishing and Construction industries have contributed most of the fatal occupational injuries ill between 1980 - 1995 (Worker Health Chartbook, 2000). Health and safety issues, especially for the mining or related excavation industries, arise either from exposures of the human workers to the contaminants liberated or generated by mining operations that have adverse effects on human health (for example coal dust etc.) or from the exposures of the human workers to hazardous working environment that constitutes mining operations (for example blasting etc.). One of the biggest challenges is to understand the combinatorial effect of numerous work-condition (e.g. exposure to dust) and human-factor (e.g. smoking habit) variables on a health or safety-condition variable (e.g. incidence rate of a disease). This paper uses an example dataset on Coal miners' cough problem to illustrate the applicability of Generalized Linear Modeling (GLM) in understanding the relation between cough and other response variables, such as, age, height, smoking habits, time of underground exposure etc.

Jan 1, 2002

By Ora H. Rostad

The sequence of events preceeding the discovery of the Mount Emmons molybdenite include some inadvertent near misses by several groups. The events are given in general chronological order to bring out the essentially contemporaneous, but different activities by several groups in two areas on opposite sides of Mount Emmons. The Mount Emmons molybdenite deposit lies in the Elk Mountain mining district. The west edge of the deposit is near the boundary between the Elk Mountain and Ruby mining districts as shown by the USGS map included (see Fig. 1). Considerable history regarding the Keystone silver-lead-zinc mine is given because of its proximity to the Mount Emmons molybdenite deposit which is on the other side of the mountain from Redwell Basin and where other significant activities took place. It should be noted that there was no documentary evidence available to me that would indicate that molybdenite was recognized to be present on, or under, any part of Mount Emmons, including Redwell Basin, before 1970. Veins containing silver-lead-zinc minerals were discovered in the Elk Mountain and Ruby mining districts about 1872. Some discoveries on the south flank of Mount Emmons about 1880 were developed into the Keystone mine. The Keystone has the largest cumulative production of metal ores of any of the mines in these districts. Most of the 413 Mt (455,473 st) of ore produced from the Keystone mine through August 1967 was produced after 1950. The ore averaged 175.4 gt (5.64 oz per ton) Ag, 2.62% Pb, 5.56% Zn, and 0.72% Cu.

Jan 1, 1991

By Dennis N. Poffenroth

One concern of the Mine Safety and Health Administration is the structural integrity of steel wire ropes used on mine personnel hoists and elevators. Failure of such ropes has resulted in loss of life and property. Although thorough and regular visual examinations are performed, hoist ropes may still fail from undetected internal wear, corrosion, and broken wires. To complement visual examinations, nondestructive rope inspection techniques have been developed to determine deterioration and removal criteria. The techniques use electromagnetic and permanent-magnet test instruments designed by a Canadian firm. This paper describes the operating principles, field and laboratory testing of these nondestructive testing instruments, and discusses the feasibility of using this type of testing as a supplement to visual examination and destructive tests.

Jan 1, 1982

By K. V. Raj

"Air inversion is a meteorological phenomenon generally occurs during winter times. Release of pollutants below the inversion height in an open-pit mine during periods of weak winds and consequently weak vertical mixing may result in very high concentrations of primary and secondary pollutants, causing serious consequences for health and safety of miners. Mine operations cease if the concentration of NOx or CO exceeds the threshold limit value (TLV) of the pollutants. Artificial ventilation is required to dilute the pollutants to an extent that mine workers can safely resume work. Studies of the turbulence parameters suggest that effective ventilation of the pit and removal of pollutants can be accomplished if a large enough mixing length in the open pit can be created. Turbulent mixing by eddies of different length scales under an inversion layer is product of wind shear, thermal gradient and buoyancy. The main result of turbulence is mixing of the atmospheric profile and transport of momentum. Computational fluid dynamics (CFD) Simulation results of a novel mitigation approach using cloud cover will be presented in this paper. INTRODUCTION In extreme climatic conditions, deep open-pit mines tend to trap pollutants at the pit bottom due to air inversions. Keeping open pits adequately ventilated is a considerable challenge for the mining community. Mine operators in cold regions are very familiar with this problem, the severity of which can be judged from Figures 1 and 2. The top portion of the figures show clear sky and snow covered benches. The brown haze, containing various contaminants accumulated over time in the pit under the air inversion, can be seen in the bottom portion of the figures. Several Arctic or subarctic mines have reported air inversions. Even Rio Tinto’s Bingham Canyon pit in Utah has reported local air inversions from time to time [1].Mitigation of pollutants in deep open-pit mines in the Arctic is a challenging task. Release of pollutants below the inversion height in an open-pit mine during periods of weak winds and consequently weak vertical mixing may result in very high concentrations of primary and secondary pollutants, causing serious consequences for human health. Mine operations cease if the concentration of any one of the pollutants (NOx or CO) exceeds the TLV. Sustained cessation of a mine operation has serious economic consequences. For continued mining operation, the levels of pollutants must be below the TLVs. If no significant synoptic meteorological situation changes during an inversion, a warm air mass sits over the cold air mass within the open pit. Artificial ventilation is required to dilute the pollutants to an extent that mine workers can safely resume work. Some of the early approaches in artificially ventilating open pits were attempted in the USSR. Most of the studies by Soviet researchers suggested the use of turbojets and turbo-propeller engines, airscrews, axial pit fans, and meteotrons [2, 3]. However, the majority of these studies were only theoretical in nature, with no evidence of an approach that really worked in practice."

Jan 1, 2017

By R. D. Hansen, R. R. Klimpel

Previous papers by these authors on slurry rheology control grinding aids have emphasized the end-use results and application methodology involved. This paper emphasizes the chemical principles and the influence of various chemical structures behind slurry rheology control chemicals. Particular examples are shown which correlate chemical structure modifications to environmental factors involved in grinding such as pH, shear, ore type, water chemistry, and particle size.

Jan 1, 1990

By William J. Attwooll

The development of gold heap leach projects in the Cripple Creek, Colorado, mining district has required utilization of heap leach pad sites other than relatively level natural ground. This paper describes the construction of a heap leach pad adequate to accommodate 907,000 tonnes (1,000,000 st) of ore over the surface of a tailings pond constructed during previous milling activities at the site. Based on the design parameters and the observed behavior to date, it has been found feasible to construct a major heap leach pile on the surface of a conventional tailings pond.

Jan 1, 1987

The implementation of NAFTA in January 1994 was expected to have small but beneficial effects on the Mexican economy, mostly through increased investments. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results during the past two years have shown that it is government and macroeconomic factors that influence investment flows, rather than the fine tuning of trade flows through so called 'free-trade" agreements.

Jan 1, 1997

By T. M. Storer

Much has been written and many discussions held on the virtues (and evils?) of a Company-owned motor fleet. Almost invariably these dialogues take a generalized form and thereby lose something since the individual circumstances, geography and philosophy - particularly in diverse industries, is never quite the same. In considering the nature of my remarks today, I felt a departure from the general approach might be in order, and in lieu of that, will attempt to present a concise picture of how we in the Lehigh Portland Cement Company view this problem and the steps we have taken in our efforts to solve it. At the outset a word may be in order about the Lehigh Company itself, what we do, and the problems that confront us specifically as well as the cement industry at large. We are primarily a manufacturer of portland cement operating 10 plants with a total annual capacity of about 23,000,000 barrels. We market this material in 30 states, shipping both from the plants directly as well as through a system of 18 distribution terminals. About 150,000 truckloads of cement are shipped to customers each year.

Jan 1, 1969

Caterpillar and Fortescue Metals Group have moved forward with the delivery, installation and support of a complete Cat MineStar System at Fortescue?s Solomon iron ore mine in the Pilbara region of Western Australia. The complete technology suite was implemented for the first phase of Solomon, the 20 Mt/a (22 million stpy) Firetail manned mine, in October 2012. As part of an autonomous mining solution for phase two, the 40-Mt/a (44-million stpy) Kings Mine, eight Command for hauling Cat 793F CMD trucks were commissioned and commenced operations in the second quarter of 2013. The mine plan calls for a progressive ramp up to 45 autonomous trucks during the next several years. In addition, other Cat MineStar System capability sets, Fleet, Terrain, Detect and Health, are being used across the mobile equipment fleet, including support equipment and light vehicles. Working closely with Fortescue and its mining contractor, Leighton Contractors, Caterpillar and the Cat dealer in Western Australia, WesTrac, are providing a full solution for managing, operating and supporting Cat MineStar System and Command for hauling. The greenfield Solomon Mine has brought together the skilled team from Caterpillar, Fortescue, Leighton Contractors and WesTrac to deliver an efficient, cost effective autonomous mining solution.

Nov 1, 2013

By T. M. Jones

This paper outlines the development of the theory of controlled district recirculation and indicates the advances in understanding and technology which have enabled a major change in established ventilation practice. An insight is presented into the possible future use of controlled district recirculation as acceptable practice in mine ventilation planning.

Jan 1, 1987

By Y. C. Kim, M Nataraja, J. T. Buckley, D. H. Tiktinsk

The Nuclear Waste Policy Act of 1982 (NWPA) assigns the U.S. Department of Energy (DOE) the responsibi1it.y of locating, constructing. operating, closing and decommissioning a nuclear waste repository. Prior to submittal of a licensee application to the U. S. Nuclear Regulatory Commission, the DOE is required by 10 CFR part 60 to conduct a program of site characterization for the site to be described in such application. Site characterization includes an exploration and research program in the field and laboratory to determine the geologic conditions and ranges of those parameters which are necessary for determining the suitabi1it.y of the site as a geologic repository. The information thus collected should be able to establish with reasonable assurance that the public and environment will be adequately protected from the hazards associated with a repository at the site. This paper demonstrates by example a geostatistical approach which, on the basis of the existing limited data base, can be used to evaluate (1) whether existing information on a certain parameter is adequate to be considered representative. (2) if additional information is required, where should the additional sampling or testing be performed, and (3) whether the new1.y acquired data along with the existing information constitute representative data.

Jan 1, 1986

By Chris D. Breeds

Northwest Boring, Inc. (NWB) deployed a skinned up AVN 2000AB Microtunnel Boring Machine (MTBM) to install 7.5-foot long, 118-inch outer diameter reinforced concrete pipe (RCP) sections along an alignment between the Fremont (FRS) jacking shaft and the 3rd Avenue (3RS) receiving shaft for the Ship Canal Water Quality SCWQ Project. The alignment includes: a 67-foot long straight section, a 367-foot long curved section excavated along a 650-foot radius curve, followed by a 182-foot long straight section. This paper describes the project including planning and design, manufacturing, equipment installation in the 90-foot-deep FRS jacking shaft, egress through the secants and microtunnel operations required to complete the shaft and install the required casing pipes.

Dec 1, 2022