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By Frank Rausche, Scott D. Webster, Rozbeh B. Moghaddam

"Pile foundation driveability is a function of several variables such as subsurface characteristics, hammer type, hammer efficiency, pile type, and plugging conditions. One important phenomenon occurring during pile driving, and yet not well documented and published, is the friction fatigue, where a reduction of shaft resistance is observed as the pile is driven to greater embedment. This paper introduces current soil models developed for the assessment of friction fatigue, and further presents a comparison between predicted driveability obtained from Wave Equation Analysis Program (GRLWEAP) and field driving records. From a literature survey, and review of technical articles, a widely-used soil model known as AH-01 has been selected to analyze the friction fatigue concept. Using a WEAP software, two driveability analysis were completed using the standard approach with setup factors, and adapting the AH-01 model into the WEAP input file. Driveability predictions were compared to the driving records corresponding to a 1676-mm x 44- mm open-ended pipe pile with a total and embedment lengths of 180-m and 119-m, respectively. Results from analyses and the comparison presented in this paper provide further information regarding existing methods for the incorporation of the friction fatigue concept to the driveability analyses, and contributes to a better prediction of driveability of open-ended pipe piles. IntroductionDynamic measurements during pile installation provide more dependable information as compared to results obtained from predictive models used for design. Despite uncertainties associated with a specific project site and foundation type, measured data provides a reliable understanding of the soil resistance and its distribution throughout the length of the pile. Back-calculations or back-analyses based on a series of measured data from a pile driving process could help to obtain reliable models to better predict events related to pile installation process in spite of all variability related to fitted models. One of the widely-used analysis regarding pile driving during the design phase is the “driveability analysis” where capacity, blowcounts, maximum stresses in the pile element, and transferred energy from the hammer to the pile element are predicted using mathematical models along with a software. Such analysis requires relevant information regarding soil, pile, and hammer properties combined with a deep understanding of the level of impact each one of these properties could have on the analysis."

Jan 1, 2017

By John O. Marsden

"Technology development and innovation has played a crucial role in the copper industry throughout history. The effective development and implementation of new technologies allows mankind to produce copper at progressively lower cost of production at a given feed grade and mineral type. This progress serves to counteract cost inflation/escalation over time and, depending on the magnitude of the cost benefit, allows ore cut off grades to be reduced thereby improving the availability, accessibility and utilization of resources. Two broad categories of technology development and innovation play a key role in this process: (i) incremental improvements and optimization of existing technology provide benefits in the near- to medium-term, and (ii) step change technologies provide value over the longer term. A key issue for potential developers and implementers of new step change technology is how to justify resource allocation and expenditures for such initiatives. This paper examines this issue with reference to specific case studies in the copper industry. INTRODUCTION AND BACKGROUND Technology development and innovation has played a crucial role in the commodity minerals industry throughout history, and none more important than the copper industry. As new, cost-efficient technologies are commercialized, the cost of production in real terms at a given ore feed grade and mineral type decreases. This progress enables ore cut off grades to be reduced allowing lower grade material to be processed economically, which in turn increases the availability and supply of the metal or mineral of interest. Cost inflation/escalation works in the opposite direction, squeezing margins for operations utilizing incumbent technology to process material from a given ore deposit. A prior review by the author considered the issue of technology development and sustainable competitive advantage. This review concluded that first movers and fast followers can achieve competitive advantage for periods of 10-15 years through effective deployment of new technologies (Marsden, 2004). A new, more comprehensive study and evaluation was completed in 2014. This paper presents a portion of the results from the 2014 study."

Jan 1, 2018

By V. Ramachandran

The Amarillo Copper Refinery, the newest and most modern copper refinery in the world, has been in operation for the last eleven years and has a rated capacity of 460,000 st/yr. The tankhouse - a structure that covers 500,000 ft2 under one roof - extends one-half mile in length and is a model of materials-handling efficiency. The use of recently developed and patented* reagent control technology, termed "Reatrol Process", has increased current efficiencies to an average of 98% and has considerably improved the physical and chemical quality of the cathode deposit. The present paper describes the current operations at the Amarillo Copper Plant with special emphasis on tankhouse operation.

Jan 1, 1987

By Erwin L. Zodrow

"IntroductionThrough an extensive coal sampling project in the Sydney coalfield of Nova Scotia during 1981 - 1984 involving a majority of the mineable coals (Zodrow, 1985, Fig. 1), a sizeable inventory on trace, minor and major metals was established. In this paper, results of studying the inventory are summarized, concentrating mainly on the relationship that exists between metal variations and thickness of coal channel samples (i.e. trends) and on explaining the trends in geochemical and sedimentological terms. As an over-all conclusion the Everglades peat of Florida is proposed as a modern-day analogue to Upper Carboniferous peat swamp development that took place in the Sydney Basin.Data InventoryFor this study 17 channel samples were cut , 8 cm to 14 cm channel width and 8 cm to 10 cm depth, from 10 successive coals which in stratigraphically descending order are as follows: Point Aconi (3), overrider Lloyd Cove (2), Lloyd Cove (2), Stubbart (2), Harbour (4), Backpit (I), Phalen (,I), Shoemaker (1) and McAulay (I), where bracketed values signify the number of channel samples cut from a seam (Zodrow, 1985, Fig. I). Each channel sample was subdivided by 15 em incremental length yielding a total sample size of 137 for analysis. By appropriate modern techniques these samples were analyzed to determine concentration levels for 32 chemical elements and ash content, the average results of which are presented in Table 1.Tests were also made for Pd, Pt, Ga, Nb, Cd, Cs, Sm and W but their concentration levels in many instances hovered on the lower detection limits that were used and on this accounts are excluded from discussion. Ashing, when necessary for the determination of concentration levels, was done for 12 hours at a temperature not exceeding 450°C. Concentration levels for the elements are reported in reference to whole-coal or whole-coal equivalents and discussed on this basis. In the course of the analyses, lower detection limits received careful attention."

Jan 1, 1986

By G. L. Oldright, J. D. Sullivan, W. E. Keck

"An apparatus and procedure developed in the laboratory of the South-west Experiment Station of the Bureau of Mines are capable not only of determining the rate and volume of penetration of solutions into porous materials but also of determining the total volume of voids within particles of porous material, and the density. The method is applicable to ores, bricks, concretes, tiles, filter bottoms, or other porous materials of this nature. As will be made clear in the descriptive matter to follow, the method measures (a) the volume of voids within the porous materials and is not concerned with the interstitial space between the particles.Porous materials usually contain some large voids and also pores that are capillary in nature. To measure the total volume of voids in a sample it is necessary to replace the gas or gases within the voids with some liquid of known density. The large cavities can be filled quite readily, but under ordinary conditions a long time may be required to fill capillary pores. As many porous materials are of a decomposable nature it is necessary to evacuate the porous materials and then submerge them in a liquid of known density to bring about saturation in a short time. Then by the use of a hydrostatic balance the volume of porous material (solid itself) can be determined. To determine the volume of porous material plus voids it is necessary to coat the sample with some material, such s paraffin, which will prevent solution from entering the voids; then, by means of a hydrostatic balance, the volume of porous material plus voids is determined and by subtracting that of the porous material from this the volume of voids is ascertained. The rate of penetration of solutions can be determined either (a) by measuring the change in weight as the sample becomes saturated when immersed ni a liquid of know density, or (b) by measuring the volume of liquid penetrating with a dilatometer. In either instance, due to the fact that some penetration takes place as soon as the sample comes in contact with solution and before a reading can be taken, the sample must be paraffined to determine the total volume of penetration. Since many porous materials partly decompose and disintegrate in liquids the rate and volume of penetration can better be measured by dilatometer than by the change in weight, as saturation takes place when immersed in a liquid. The details of procedure for determining (a) total volume of voids, and (b) rate and volume of penetration are given in this paper."

Oct 1, 1930

By Yi Zheng

Under normal circumstances, methane released along a longwall face represents only 10%-20% of the total me- thane emitted from the entire longwall panel. However, there might be a sudden surge of methane at the face which may cause a potential problem because the friction from shearer cutting, support movement, and scraper conveyor dragging can be ready ignition sources. Therefore, to predict the distribution of methane will be critical to prevent possible explosions. In this paper, methane dispersion patterns along a lognwall face are simulated under normal and abnormal conditions. With the simulation of methane released from the face, around shearer drum, and from the broken coal on the conveyor, places with possible high methane content can be identified by different phases of working process and shearer positions. Local ventilation measures are evaluated so precautionary measures can be planned ahead.

Jan 1, 2012

By Harry K. James

Experimental studies of the physical and explosion characteristics of pure hydrazine nitrate and multicomponent systems containing hydrazine nitrate, supplemented with an extensive Literature survey, are presented. Such proper- ties as melting point, heat of fusion, density, viscosity, surface tension, thermal stability, decomposition process, detonation velocity, impact sensitivity, and TNT equivalence are included.

Jan 1, 1970

By Peter L. Comanor

At Getchell, Nevada a thousand tons per day mill for extracting gold from an ore containing orpiment and realgar was operated several years until early 1967. A cyanide process with a roaster was used in the processing of the ore. Mill wastes were contained in tailings ponds, in which the concentration of arsenic, currently, is one per cent or higher, Studies were conducted determining the effect of the tailing wastes on the Upper Sonoran vegetation of the area. Grid and line-intercept techniques were employed to obtain botanical informatics of the area surrounding the tailings ponds. Data of the per cent ground cover, species frequency, and plant vitality as a function of distance from the tailings ponds was collected. The data was compared to other botanical data collected from a control site outside the influence of the tailings ponds. In an attempt to isolate naturally occurring factors for varying plant communities from hose induced by factors derived from the close proximity of the tailings, soil cores were taken along the line-intercepts at intervals of 30 meters. The cores were analyzed for several compounds and elements needed for growth, or known to inhibit growth. Specific physical parameters of the soil samples were also taken. The paper describes the impact made by mill wastes containing large amounts of arsenic on the Upper Sonoran vegetation of the Getchell region. Described in detail are the techniques used to make the correlations between the plant communities and the influences of mill wastes.

Jan 1, 1974

By R. B. Prater

The Bureau of Mines conducted research to separate the F from byproduct Zn concentrates obtained from fluorspar (CaF2) production, as part of the Bureau's effort to devise efficient, environmentally acceptable technology for recovering Zn from resources considered undesirable by Zn producers. Sulfuric acid (H2SO4) was found to be effective in F removal, while ammonium carbonate [(NH4)2C031 was not. The most important variables for reducing the necessary residence time were found to be temperature and agitation. Optimum leaching conditions were 75° C and 500 r/min for 2 h at 40 pct solids with 0.2 g acid per gram of concentrate, which resulted in a 98.3-pct F extraction. Zinc losses during F removal were in the range of 2 to 3.3 pct. Other elements such as Fe, Cd, Ca, and Cu were also partially dissolved. About 93 pct of the F was removed from the leach solution by neutralization and precipitation with calcium hydroxide [Ca(OH)2]. Additional treatment might be necessary to limit the buildup of soluble elements in the recycled leach solution.

Jan 1, 1985

"The effect of operational conditions, such as air flow rate, impeller speed and solid concentration, as well as the effect of solids concentration and frother dosage, on the bubble size distribution produced in a lab scale flotation cell, were investigated. The cell was operated under batch conditions. The measurement of bubble size was accomplished using an automated photographic technique. The technique enabled fine and coarse bubble distributions to be measured in two-phase (liquid-gas) and three-phase systems (solid-liquid-gas). In each experiment, around ten thousand bubbles were characterized.This paper discusses the main results obtained using the new photographic technique and compares these with previous findings available in the literature. The results indicate that photographic techniques combined with digital imaging processing might become a standard technique for measuring bubble size distribution in flotation machines.HUT BUBBLE SIZE ANALYSERThe importance of having precise and reliable equipment for measuring bubble size distribution in industrial flotation machines has been widely recognized. The measurement of bubble size, particularly in three-phase systems, is rather complex due to the opaque nature of the pulp. However photographic techniques combined with ingenious sampling techniques are utilized for overcoming this difficulty. The technique named HUT, combines previously developed visualization methods with digital image processing procedures. In this technique bubbles and aggregates are exposed to a monochrome progressive scan camera. The acquired images are directly stored in a computer connected to the camera for post-processing. The sampling apparatus consists essentially of a vertical tube for collecting bubbles, a viewing chamber and a collection chamber, where particles carried by the bubbles are released. The function of the collection chamber is to maintain the viewing chamber clear for imaging purposes. Each image is automatically processed off-line, using digital image tools. In this paper the advantages and limitations of this new technique are described."

Jan 1, 2003

By N. Mangadoddy, M. Padhi

The simulation of multi-component classification with modified viscosity model is the key focus in the current study. The classification of the ores using hydrocyclone is a renowned process and has a convoluted flow separation phenomenon. The highly turbulent flow inside hydrocyclone depends on the operating and design parameters apart from the feed mixture. Slurry viscosity also plays a dominant role in the classification of solid particles under the centrifugal settling action. A heterogeneous mixture with different components would result in different settling and rheological behaviour of particles’ suspension in the water medium. The newly proposed multi-component viscosity model (Mandakini et al. 2020) is implemented as a user-defined function to define the material property during the CFD study of the mixture rheology inside hydrocyclone classifier. The multiphase and turbulence model is solved using the modified Algebraic Slip Model and Large Eddy Simulation model. A comparison of the predicted component performance curves is evaluated with and without the corrected viscosity model. The density and size effect on the particle phase distribution inside the classifier are compared, where the misplacements of the finer particles are carefully assessed. Validation of the component classification in hydrocyclone with the laboratory experiments found a close agreement with the rheology based CFD data. Keywords: Dual-component, multi-component viscosity model, double-gap rheometer, computational fluid dynamics, high solids concentration

Jan 1, 2020

By K. F. Anderson

The increasing number of oil-productive reservoirs in the Ellenburger formation has emphasized the need for information pertaining to the hydrocarbon recoveries that may be obtained from such reservoirs. Most of the space available for accumulating hydrocarbons in the Ellenburger formation is derived from fractures, which makes it difficult to estimate reserves or probable recoveries. The Ellenburger reservoir in the Big Lake field was selected for study because it is one of the few near-depleted reservoirs in the area. The experience gained in operating and developing this reservoir has been and should continue to be a helpful guide to operators both in predicting recovery and establishing methods of development and operation In similar reservoirs. Development and production data were gathered from different sources. The writers have compiled and interpreted these data to estimate the ultimate recovery of hydrocarbons. In addition to the estimates of ultimate recovery, the report contains sample calculations and estimates of theoretical recovery based on different methods of operation. The calculations presented in this report indicate that the Ellenburger reservoir is 95 percent depleted and that the ultimate recovery of hydrocarbon liquid from the oil reservoir and gas cap combined will he 4-0 barrels per gross acre-foot of reservoir rock. An estimated 32 barrels of condensate per gross acre-foot of reservoir rock in the gas cap has been recovered, and the estimated ultimate recovery of crude oil will be 47 barrels per gross acre-.foot of rock in the crude-oil reservoir.

Jan 1, 1954

By D. L. Crouse

The worldwide talc industry has experienced significant changes since the 1980's. Consolidation of companies and operations in Europe, Australia, and North America has altered the face of supply and distribution. Imports of Chinese and Australian crude have increased competition and product options. The number of processing operations without local mines has moved competition closer to the market area. Quality controls related to ISO certification and tighter specifications demanded by the customers have altered the way our mines and mills operate. Ceramics, coatings, and paper applications continue to consume the majority of processed talc.

Jan 1, 1997

By F. N. Kissell, C. D. Litton

This study predicts the level of smoke that miners might meet while trying to escape a coal mine fire and describes how smoke would impede their safe escape. For this study, the authors assumed that miners exit through an escapeway adjacent to the burning entry, that some air would leak from the burning entry to the escapeway. The following conclusions were made: • A very low amount of air leakage to the escapeway can produce a critical level of visual obscurity from smoke. This shows that intake airways may be as susceptible to smoke visibility problems as return airways. • This critical level of smoke obscurity is reached much before a critical level of carbon monoxide is reached. • Small fires can cause a severe sensory irritation that further limits vision. Thus, reliable eye protection is very important. These results show that methods to guide miners through dense smoke will contribute greatly to saving lives during mine fires.

Jan 1, 1993

The results of studies to ameliorate acid mine drainage by retarding the rate of oxidation of pyrite at source are discussed. In the transpassive region, pyrite oxidizes by reactive dissolution, mass transfer through the product layer and diffusion in the bulk solution. One can decrease the rate of pyrite oxidation by inhibiting either oxidation reactions or cathodic reactions. It is demonstrated in this study that some surface active reagents extend the passive region by affecting both the anodic and cathodic processes. The extension to higher potentials occurs by inhibition of the anodic dissolution process whereas to lower cathodic potentials through decrease in the rate of reduction of molecular oxygen and/or ferric ions. To retard the oxidation of pyrite by ferric ions, which is considered to be the dominant oxidant under conditions of acid mine drainage, it would be necessary to restrict mass transfer or promote complexation of ferric ions at the surface. Imidazoline based reagents were found to be most effective in meeting this goal.

Jan 1, 1994

By C. Musingwini, A. S. Nhleko

"Since the Global Financial Crisis (GFC) in mid-2008, capital has been more difficult to access. Mining projects must contend with projects from other industries for scarce capital. A decision to invest available capital in mineral projects requires that valuation be conducted to assess the expected return on the projects. The discounted cash flow (DCF) analysis is generally applied for the valuation of mining projects, whereby future cash flows are discounted to present value using an appropriate discount rate. The discount rate significantly affects the outcome of a valuation. Economic and finance theory provides tools to calculate discount rates. The discount rate must account for factors such as the risk and stage of development of the mineral project; hence the appropriate discount rate to utilize in a project is often a subject of debate.The discount rate is the weighted sum of the cost of debt and equity. There are several methods for determining the cost of equity. This study considers the commonly applied Capital Asset Pricing Model (CAPM) and Gordon’s Wealth Growth Model because of their simplicity and availability of parameters required to estimate the cost of equity. This study explores how differences in the cost of equity obtained by these two methods can be explained for a mining environment. Data for empirical analysis were collected from the I-Net Bridge, McGregor BFA, and Bloomberg databases. It was found that Gordon’s Wealth Growth Model provides better estimates of the cost of equity compared to the CAPM under depressed market conditions. Therefore, this research recommends that Gordon’s Wealth Growth Model be used to estimate the discount rates for mining projects during periods of depressed market conditions."

Jan 1, 2016

By Walter Knox, J. D. Doherty

IN 1939, at the request of The Koppers Coal Co., the Koppers Company Research Department established a Stoker Coal Research Laboratory for the purpose of investigating the performance characteristics of stoker coals in typical domestic stoker installations. Fig. I is a photograph of part of the laboratory. The material in this paper deals with the performance of one coal in a single installation. Presented are details of this installation, mechanical characteristics of the stoker, and the results of a series of burning tests in which adjustments were systematically varied. SUMMARY OF RESULTS Mechanical Features I. A large percentage of the total power consumed by a domestic stoker is used to operate the gear case and motor (Fig. 3). 2. The power consumption per ton goes down with an increase in rate of coal feed (Fig. 4). 3. The automatic air control in this stoker showed advantages over manual control (Fig. 5). 4. The air velocities through the retort tuyeres were uniform around the retort, but varied between the rows of tuyere rings (Fig. 6). 5. The crushing of coal with this stoker increased the minus 1/8-in. from 1 1.6 per cent to 19.2 per cent. There was a noticeable segregation of coal as it came from the retort and distribution was not uniform (Fig. 7). 6. Measurement of air entering over the fire showed that with some not uncommon adjustments this air may he a high percentage of the total air supply (Fig. 8 and Table I). Operating Performance I. The removal of clinker was shown to give a period of poor performance characterized by a high fuel-bed resistance and a high percentage of carbon monoxide in the flue gases (Fig. 10). 2. The fuel-bed resistance was found to decrease as the fuel bed built up in a normal response to heat demand after a prolonged hold-fire (Fig. II). 3. With intermittent operation the burning rate was almost always less than the feeding rate. The wide variations were found to be greatly dependent upon the length of the On period and the length of the intervals between On periods (Fig. 12). 4. The maintenance of a low furnace draft led to less fly ash, better clinker formation, and higher efficiencies (Fig. I3). 5. The maintenance of a minimum of excess air also resulted in less fly ash, better clinker formation, and higher efficiencies (Fig. 14). GUIDING PRINCIPLES In planning the investigations, the following principles were adopted: Selection of Healing Equipment.-Use only standard models of stokers and furnaces representative of those widely used.

Jan 1, 1942

By Erwin L. Zodrow

THE AUTHORS welcome this timely opportunity to comment o n a paper by MacLean and Merner (" Room-and- Pillar Mining at the Prince Mine of the Cape Breton Development Corporation " , ClM Bulletin , June 1978, pp. 59-62) concerning the rock falls and their relation to "a change in the strata". First, however, it is proper to express our gratitude to the Cape Breton Development Corporation, and in particular to A. R. MacLean, for making it possible for us at the College of Cape Breton to start two new collections. The first of these is a fossil plant reference collection from the Sydney Coalfield, Cape Breton (Upper Carboniferous period) , and the second is a documentation of the role o f pyrite in the formation of hydrated sulphates (samples from No. 26 Colliery, 1-B Mine, and the Prince Mine at Point Aconi). Conditions of sedimentation in the deltaic-type basin of the Upper Carboniferous time in the Point Aconi area were such that on the (coal) swamp, now represented by the Stubbart (or Hub) seam , (a) clays of varying thickness and extent were deposited , (b) biogenetic sulphur was introduced and (c) flora were buried. These are essentially the culprit s that make rock falls possible and at the same time predictable over large areas (in the present mine). The clays lithified to become shale, and biogenetic sulphur combined with iron to become pyrite (marcasite?), which exists as nodules and in fine-grained layers.

Jan 1, 1978

By J. M. Tannenbaum

A depth-sensing micro-indentation technique is developed for evaluating mechanical properties of materials at elevated temperatures (to 1200°C). System description and design considerations of the test apparatus are described. Based on Hertzian spherical indentation approach, the micro-indentation test apparatus is capable of determining Young?s modulus and creep strength of test materials with flat, tubular, or curved architectures from room to 1200°C under either air or controlled gaseous environments. Calibration tests were conducted on a H13 Tool Steel coupon from 22°C to 500°C and single crystal Haynes 230 alloy at 1000°C with excellent agreement to the literature values. Indentation creep tests of Haynes 230 alloy were carried out at 1200°C with preliminary results showing good correlation to creep exponents. Further system refinements will be investigated, and additional testing will be conducted.

Jan 1, 2010

By C. Zuniga, S. Combrinck, C. Peters

Agnico Eagle Gold have partnered with Enaex Australia at their Fosterville gold mine to leverage a combination of drill and blast technologies to optimise underground development mining. The mine is the first site globally to collaboratively develop and trial Enaex SWIFT electronic development detonators, which utilise a novel approach to the user interface, simplifying implementation and enabling the benefits of electronic initiation without the complexity of a conventional system. This has been combined with the use of a Sandvik 422i smart jumbo, and the Enaex underground emulsion charging unit with the capability to tailor the delivery of explosives as required and report on a hole-by-hole basis. The combination of these technologies enables full engineering oversight of the development cycle, in turn enabling optimisation of this process in a historically conservative application. The methodology for leveraging these technologies is to bore a controlled and defined blast pattern through using a smart jumbo, load the blast holes utilising lace loading to deliver a desired quantity of ammonium nitrate emulsion per hole, with the ability to reduce chargeweight for perimeter control, and utilising Enaex SWIFT electronic detonators with flexible template type pre-defined delays to initiate the blast holes. Subsequent to firing and excavation the performance of the blast in fragmentation, advance efficiency, and overbreak and underbreak is measured and reviewed. This is then used to optimise the development cycle and apply to other parts of the mine.

Feb 6, 2023