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By S. D. F. Rocha

The influence of surfactants on the crystallization of calcium sulfate was investigated in both hatch and continuous systems. The investigation was per formed at the following conditions. 343 °K, 28% P205 and with a sulfate level of 2.0%. At concentrations of 5 and 200 µgig, respectively, dodecylbenzene sulfonic acid (DBSH) and sodium diisooctil sulosuccinate (SSNa) promoted both an increase in the size and a reduction in the length/width (L/W) ratio of the calcium sulfate hydrates produced in the hatch and continuous crystallizers. Unique effects were observed in the batch system at higher DBSH concentrations. At 10 µg/g, the precipitation of hemihydrate crystals with a distinct morphology and texture occurred under conditions where dihydrate precipitation was expected. Above 50 µg/g, the precipitation of calcium sulfate hydrates was completely inhibited.

Jan 1, 1996

By A. A. Sadegh

A laboratory investigation was carried out on the characterization and beneficiation of sillimanite ore. Petrographic analysis indicated that the ore consisted of massive elongated sillimanite grains in a matrix of hematite, garnet, feldspar and silica. A procedure for estimating the percentage of sillimanite was developed using float-sink and magnetic-separation techniques. A liberation study was carried out to determine the level of size reduction required to achieve sufficient liberation while ensuring that gravity concentration techniques would be applicable. Laboratory testing was performed on the liberated ore to investigate the applicability of using wide-angle dense-medium cycloning to upgrade this ore. Initially, medium-only tests were carried out using various size distributions of magnetite and ferrosilicon as the dense-medium solids to evaluate the effects of operating conditions on medium segregation. Depending on the medium solids and operating conditions, either positive of negative differentials (difference between the relative densities of the underflow and overflow streams) were obtained. Based on these results, separation tests were performed to process nominal -1.2-mm sillimanite ore. The results indicated that sillimanite concentration could be obtained using a medium relative density that was much lower than would typically be used in a dense-medium cyclone separation.

Jan 1, 2007

By Liu Cheng-si

Variable airway is controllable, which is an important discovery in ventilation research in recent years. For this reason, conventional calculating methods are no longer suitable to solve this problem. I used Mayeda-Seshu and Newton methods to solve the above problem before, they have been proved feasible. However, it is troublesome and difficult to apply to operation with a large amount of calculations. In this paper combination theory and simplified formula are used in determine all control plans and its parameters. This new method with less calculation is easy to understand and master, so it is more important in research and application.

Jan 1, 1997

By Phoebe L. Hauff, Jeffrey P. Kurtz, Paul D. Chamberlin

Clay minerals can be a source of problems in heap leaching operations. The ore for many heap leach operations is commonly acid-sulfate alteration zone rocks which may be found in hot springs deposits as well as the supergene zone of other near- surface gold deposits. Clays can be important constituents of these ores. Swelling clays, such as smectite, can come loose from the agglomerated ore, migrate within the heap, concentrate in pore spaces and often plug up flow channels in the heap Cement is often added to the ore as a binder during the agglomeration process. Lime is added for pH control. Their presence, combined with the sodium cyanide commonly used to leach, can raise the pH of the leach solution to 10 or even 12. This very alkaline solution can cause dissolution of some mineral Some clays, such as kaolinite, are not very stable in high pH solutions. They can be dissolved and reprecipitated as other clay species if sufficient silica and the appropriate cations are available in solution. Silica gels and amorphous materials can also be created from the dissolved kaolinite and other minerals and act as retardants to the flow of leach solutions in the heap. Therefore, before a heap leach operation is built, the operator should evaluate the clays in the ore and test the agglomeration procedure. It is important to know not only the mineralogy and the chemistry of the leach environment but how the minerals and solutions interact and what the products of this interaction are. A hypothesis is presented in this paper that expanding smectite- bearing clays can be generated within the heap. How and why this happens will be explained.

Jan 1, 1987

By Frank P. Frandina, Michael J. Loehr, Paul E. Gabryszak

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. In the Preliminary Engineering stage, 30 existing tunnels were assessed and 28 were found to need clearance improvements to allow the use of double stack trains. Alternative tunnel enlargement methods were developed to achieve the desired clearance improvements, while maintaining structural integrity and minimizing disruption to train traffic. This paper summarizes the geometric and condition investigations of the existing tunnels, as well as describes the preferred methodologies to achieve the desired clearance. The clearance improvements will be implemented beginning in the summer of 2007.

Jan 1, 2007

By Mark Springett

The problems inherent in sampling low- grade deposits have long been recognized. As economic grades become lower with increasing metals prices and improvements in recovery technology then the previously difficult sampling problem has consequently become even more demanding. The breakdown of the sample process and error is illustrated by describing in the remainder of the paper some sampling practices that have been utilized on mining and exploration properties and by describing some problems that have been encountered, providing a series of cautionary tales to those involved in any aspect of mine or exploration sampling.

Jan 1, 1983

By S. K. Mishra

The history of the Australian coal industry is almost as old as the history of Australia after new settlement. The first cargo of coal was exported from Newcastle to India in 1799. Although coal has been mined in Australia for almost two centuries, there are indications that the first coal was processed in 1877 in the New-castle area, nearly a half-century after the first coal processing in Europe. Processing on any significant scale began only in 1944 at the Newcastle Steel Works. In Queensland, however, coal processing did not begin until the second quarter of this century. The well-known dramatic growth of mining and processing of Australian coal since the mid-sixties has primarily been due to the expansion of the export market in Japan and other Asian and European countries. Black coal occurs in most of the major sedimentary basins in Australia. The better known deposits of commercial importance are in Sydney, Bowen, Oakland and Gailiee Basins (Figure 1). Apart from Collie Basin in Western Australia, other coal deposits of the Arckinga Basin in South Australia, the Bonaparte Basin in Northern Territory and Tasmania Basin, Tasmania, are basically unexploited. Sydney Basin of New South Wales and Bowen Basin of Queensland remain the major producers of black coal in Australia.

Jan 1, 1985

By F. H. Deily

The petroleum industry has developed and utilized many aspects of rock mechanics, both in its search for petroleum and in its drilling and production operations. Geological exploration activities have been improved by knowledge of earth tectonic forces. Better understanding of seismic wave motion has contributed to a more accurate interpretation of geophysical data. Drilling activities have benefited from basic knowledge of rock strength behavior under in situ conditions. Production has been significantly increased through stimulation techniques, such as hydraulic fracturing. The ability of rock mechanics work to contribute to future petroleum activities will depend upon the development of knowledge of rock properties under greater depths and at higher pressures and temperatures.

Jan 1, 1969

By Vladimir Admek, Paul W. Jeran, Michael A. Trevits

It has' been found that lithological conditions over the Pittsburgh Coal bed cause the subsidence coefficient to vary within the area of the subsidence trough. This precludes the use of European developed predictive models, which are based upon a constant subsidence coefficient. Regression analysis of the distribution of subsidence coefficients from 11 Bureau of Mines, U.S. Department of the Interior, longwall panel studies on the location relative to the edge of the panel has yielded a third degree polynomial equation. This equation has been incorporated into a BASIC computer program for use on a personal computer that allows users with no previous knowledge of the theory of subsidence to predict vertical movements over typical longwall panels in the Northern Appa1achian Coal Basin.

Jan 1, 1986

By H. Tutu

The legacy of gold mining operations continues to affect water quality in the Witwatersrand Basin in South Africa. The acid mine drainage (AMD) emanating from the tailings dumps liberates heavy metals from the ore minerals. The objective of this study was to characterise the geochemical processes that are important in understanding chemical evolution of polluted water in the study area. Analytical results for water samples collected in the catchment of the study area generally showed elevated concentrations of heavy metals in the vicinity of tailings dumps and mining operations and a decrease in the distal. Dams and wetlands, despite their proximity to the tailings dumps, recorded low concentrations of heavy metals and other pollutants. The characterisation of AMD was summarised in a conceptual model in which plots of redox potential versus pH and electrical conductivity versus pH were identified as the most important sub-models that captured the gross physical-chemical characteristics of polluted water and its interaction with the environment.

Jan 1, 2006

By C. W. Matthews

Introduction Screening is defined as a mechanical process which separates particles on the basis of their size and their acceptance or rejection by a screening surface. The key element in this method of particle sizing is obviously the screening surface, the medium that contains the apertures for the passage of the undersize material. This surface must be strong enough to support the weight of the material being screened, flexible enough to yield to the vibrating force applied to it, yet light enough to provide a reasonable ratio of open area to attain a practical through- put. To balance all of these factors is difficult enough. The problem is compounded, however, because screening media are made in a great variety of types, shapes, sizes, and materials of

Jan 1, 1985

By William T. Ingram

Early in the 60's the author served as Chairman of the Engineering Foundation's Coordinating Committee on Air Pollution Research. One of our objectives was the development of a study on the measurement of stack emissions. Three publications of the Foundation resulted from these efforts to focus attention on the stack sampling problem.1,2,3 Two of these were annotated bibliographies covering 197 references. The third reported the results of a workshop meeting at which some 21 individuals from research institutes, industry and government discussed the possible and probable areas of research that would add to or increase the ease, precision and utility of sampling gaseous and particulate matter emitted from stacks. The American Society of Mechanical Engineers has had in its Power Test Codes a Standard Code for Determining the Dust Concentration in a Gas stream4 since 1941, The American Industrial Hygiene Association has published, in its Air Pollution Manual,5 a Section on Stack Sampling. Industry and regulatory agency requirements for stack sampling have utilized some modification of the alternatives in methodology. There has been ho single guide to stack sampling that met the needs of those who have the need to know.

Jan 1, 1970

By Felicia F. Peng, Lili Li

The dispersion model of nonideal flow was applied to describe the hydrodynamic state within the flotation column. Residence time distribution (RTD) data of a laboratory flotation column were measured to determine the parameters of the model. The effects of operating variables and column geometry on the Peclet number which reflects the extent of axial dispersion were investigated and a semi-empirical expression of Pe was formulated. The dispersion model was validated for the column flotation of ultrafines coal. Under the conditions of sufficient aeration rate and frother addition, a good agreement between the measured recoveries and predicted data was obtained. The dispersion model with first-order flotation rate process of the flotation column developed in this study is useful in predicting the collection zone recovery of fine coal, and for the flotation column scale-up.

Jan 1, 1995

By William F. Riggs

The basic theme of this symposium and panel Is Rotation Pads: Are They Optimized? There Is a. reason for phrasing the title In the form of a question. There Is not only the technical competency which we must address; there Is the operating philosophy that must be evaluated on the part of both the customer and the supplier. Customers desire reagents which are trouble-free and capable of providing that extra amount of selectivity or recovery. When they receive ft, after the supplier has provided several years of Internal research, one of the first concerns/complaints Is the price of the product. This has a tendency to rapidly reduce a supplier's support level In the future. Suppliers are equally guilty from another perspective. When they approach a customer to Introduce a product, they often attempt to market by offering only a price Incentive. They then wonder why a customer doesn't respond Immediately to the incentive. They are often oblivious to the fact that the reagent cost is such a minor aspect of the operating budget, and the customer has many more pressing problems on a day-to-day basis In comparison to the reagent cost. We need to establish the understanding that reagent cost Is an Inconsequential cost of operation, and yet has such a disproportionately high Impact on the success of the entire operation. This understanding Is required by both the customer and the supplier. We say to each other,' why are we discussing this since this has been obvious for some time?' The reason is relatively simple in that we talk about it, acknowledge it, and yet we do not adhere to it. The supplier provides a product along with test data containing statistics, analysis, recovery, grade and cost calculations while most of the time ignoring the operating technique which must be applicable In the plant In order to optimize the product. He expects the reagent to be substituted In the plant for the existing reagent and ft works or does not work after trying several variables. The operating management Is equally guilty, In order to best explain this to both the customer and the supplier, ft becomes necessary to review the basic purpose of the major reagents utilized In flotation. A collector is basically to Impact selective, maximum water repellency on the surface of a particular mineral, The frother has the purpose of providing a chemically stabilized membrane on the surface of the bubble at the air-water interphase. This, then, provides a host environment for the attachment of the collector-coated mineral to a bubble. The depressant functions In the reverse of the collector and must demonstrate the same or greater degree of selectivity than expected of a collector. The key area which has been Ignored Is the rate by which these reactions occur and Interrelate. This has a very specific effect on the operating technique and the compatibility of the chemistry, equipment, and the operator himself. Researchers, suppliers, and customers provide reams of data to demonstrate how their products or design produce, for example, higher kinetics, more selectivity, or more recovery. The Information is often true. After all, we are all learned men and laboratory and actual plant data do not lie. However, we must remember the theme of this symposium and panel: Flotation Plants: Are They Optimized? and Optimizing of Flotation Reagents? The direct, honest comment to the two titles is very simple. OF COURSE THEY ARE NOT The plants, equipment, and reagents had better not be optimized or else we are in trouble. The Issue of this panel discussion is to approach this subject from a slightly different or perhaps mainly Ignored aspects of optimizing reagents in flotation. When we have reagents which provide higher kinetics, more selectivity, and better recovery, how do we use them? Since each reagent has a different physical characteristics of froth, rate of recovery, volume effect on the compatibility of equipment, and many more aspects too numerous to mention, the question which has been severely Ignored Is, 'What degree of study and cooperation by both the supplier and the operating management has been conducted In order to prepare the operator for maximizing the performance of a reagent In relation to the rest of the system?" Prior to testing a new reagent, how much time Is spent to bring the actual operator(s) Into the program to make them feel part of the program? How much time is spent explaining to the operator on the float floor how to possibly take advantage of a reagent with faster kinetics or one which Is Inherently more selective? What

Jan 1, 1993

By Winn B. Frank

Events of the mid-1970's have materially affected US coal production and transportation by railroad. Coal, as a replacement or substitute for petroleum fuels, has been hauled in significantly increased tonnages. Concurrent with the new demand, the railroad regulatory environment has undergone major changes, especially in "deregulation" activity. Those two events have produced considerable Litigation regarding coal rates. This paper discusses the factors involved with railroad rates and topics such as revenue adequacy, Ramsey Pricing, stand-alone cost, and differential pricing. In addition, an update on the western railroad merger situation and the implications for coal transportation are presented. The paper concludes with an evaluation of the current regulatory climate and future prospects.

Jan 1, 1983

By M. R. Yalamanchili, C. A. Young, J. J. Kellar, W. M. Cross, J. D. Miller

Introduction Researchers have long speculated regarding the adsorption state of collectors on mineral surfaces. Only recently have analytical techniques become available that allow direct in situ analysis of adsorbed layers. With reactive internal reflection elements (IREs), Fourier transform infrared spectroscopy coupled with internal reflection spectroscopy (FT-IR/IRS) allows for unobtrusive investigation of the adsorbed layer (Harrick, 1979). This technique has been used both for the in situ identification of adsorbed species and for the direct calculation of collector adsorption density in real time from infrared spectral data (Miller and Kellar. 1988). The reactive mineral IRE serves both to internally reflect the infrared light and to act as a substrate at which collector adsorption can be monitored. Shown in Fig. I is a schematic of light being internally reflected in an IRE. As the light is totally reflected at the interface, an evanescent wave propagates a short distance (typically a few microns) away from the IRE, and sampling of the interfacial region occurs. Because of multiple internal reflections, great sensitivity can be obtained. Flotation systems for which this method has been demonstrated include CaF2/oleate, Al2O3/dodecylsulfate, CaCO3/oleate, ZnS/xanthate and KCI/octylamine (Miller and Kellar, 1988; Kellar et al., 1989, 1990; Miller et al., 1990). Of particular interest to flotation chemists is the conformational behavior of the alkyl chain of adsorbed collector molecules. In the simplest sense, conformation can bethought of as the relative flexibility of the hydrocarbon chain caused by rotations about carbon-carbon single bonds. The flexibility is described by the amount of gauche/trans conformations in the alkyl chain. Figure 2 shows examples of gauche and trans conformations (rotational isomers or rotamers) in a hydrocarbon chain. These two conformations are observed when the terminal methylene groups in any four-carbon subchain are on the same side (gauche) or opposites sides (trans) of the plane of the middle carbon-carbon bond. A gauche conformer (rotamer) is thus a state of maximum potential energy, whereas a trans conformer is a state with minimum potential energy. The difference between these states has been found to be approximately 0.5 to 0.8 kcal/mole (Mead et al., 1986). The relative number of butane molecules present as gauche conformers with respect to trans conformers can be calculated from the Boltzmann equation (Mead et al., 1986). At 25° C approximately 66% of the butane molecules are trans rotamers. [ ] However at 100° C, only 33% of butane molecules are trans rotamers. Exposing the hydrocarbon chain to a polar, rather than an a polar, medium should also cause an increase in the number of gauche butylene groups in a hydrocarbon chain, although this effect has been difficult to observe experimentally (Mead et al., 1986). Forming a crystalline hydrocarbon is equivalent to decreasing the temperature, which greatly increases the amount of trans butylene groups present in the chain. From the preceding discussion, a picture of the solution species of concern can be developed. The collector monomer should exhibit the greatest number of gauche rotamers and most likely will look crumpled or balled-up to reduce the surface area in contact with water. The micellar form is expected to be aggregated, with the hydrocarbon chain existing in a less polar environment. These characteristic conformational features have been examined by FT-IR spectroscopy for various liquid phases of alkanoic acids (Umemura et al., 1981; Cameron et al., 1982a; Yang et al., 1986; Wong, 1987; Wong and Mantsch, 1983; Cross et al., 1992), phospholipid membranes (Fringe Ii, 1980; Casal and Mantsch, 1985: Wong et al.. 1988;

Jan 1, 1994

By Aladar B. Dory

INTRODUCTION Practical experience in mines with known presence of radon daughters in the mine atmosphere in Canada and elsewhere shows that a very high concentration builds up in an unventilated dead end heading. As Holaday et al1 observed, even a minimal air movement results in a drastic reduction in radon daughter concentration. It is therefore obvious that the main objective of radon daughter control in the working environment is to design the ventilation system providing an optimized flow of fresh air into the workplace, resulting in acceptable climatic conditions and achieving radon daughter concentrations resulting in exposures as low as reasonably achievable. BASIC OBJECTIVES Large mining companies, having extensive material resources and professional expertise, have utilized elaborate electrical modelling in the design of mine ventilation systems as early as 1950 (coal mining industry in Europe) and with the advance of computer modelling techniques, their utilization in ventilation systems design is on the increase. Unfortunately, these methods are usually not available to small mining companies and even the large companies might not achieve the fullest benefit from utilizing them, if proper limiting factors are not considered in the modelling. When an evaluation of a ventilation system of a mine is undertaken in literature, a measure of the amount of air supplied underground per one ton of ore mined is used as an indicator of the efficiency of the ventilation system. Yet, even the greatest amount of air forced into the mine might not result in an acceptable working environment if a proper distribution of this air into individual working places is not achieved. The volume and the age of the air are probably the two most important factors in achieving acceptable radon daughter concentrations in the workplace, but other factors also have to be considered. DIRECTOR MINE - ALCAN, NEWFOUNDLAND FLUORSPAR WORKS ST. LAWRENCE, NEWFOUNDLAND, CANADA Ventilation To illustrate the effects of the design of the ventilation system on the control of radon daughter concentration, let us review the gradual development of the ventilation system of this mine from the earlier years of its development up until its final years of operation. This mine, located near the community of St. Lawrence on the south coast of Burin Peninsula was developed in the late thirties and reached full production by 1942. Unfortunately as was customary at that time, the only source of ventilation was a natural draft. The mine was extremely wet, and no significant attention was initially given to possible health effects of dust. It was not until the mid-fifties, when a number of cases of silicosis had surfaced, that de Villiers and Windish2 observed a significant increase of lung cancer incidence among the miners in comparison to its incidence among the general population of Newfoundland. Suspicions regarding radiation as a cause of the lung cancer were expressed, but it was only in surveys taken in late 1959 and early 1960 that Windish3 and Little4 established the presence of radon daughters in the mine atmosphere in very high concentrations. Windish, de Villiers and Hurley suggested that the most likely source of the radon in the mine was the mine water which dissolved radon during its passage through the granitic country rock in the surrounding geological area. This conclusion was confirmed by analyses of water from various areas of the mine by the Atomic Energy Canada Limited laboratories. The radon values in the samples varied from 4,240 to 12,850 pCi/L5. Following the discovery of the presence of radon daughters in the mine, the company took speedy action to install mechanical ventilation for the mine. The system was not designed as a total unit, but fans were installed rather on a trial and error basis. The basic system installation began in March 1960 and was completed by 1962. It remained basically unchanged with only minor modifications until August 1973 when a wholly new, redesigned ventilation system was implemented. A schematic section of the mine and its ventilation system for the period prior to March 1960 is given in Figure "A", for the period 1960-1973 in Figure "B", and for the period after August 1973 in Figure "C". The ventilation system prior to 1960 is not known. All workings of the mine were ventilated only by natural ventilation. If any measurements of airflows at different or any times of the year ever existed, no records have been preserved. The very minimal natural ventilation was augmented by "blowing" air from compressed air supply lines and exhaust air from drills. It is known that the compressor capacities of the mine were limited and therefore no significant air movement was probably created by the "blowing".

Jan 1, 1981

By Raymond W. Henn, Kent A. Pease, Glen J. Rorison

The paper focuses on construction of a 2.55-km (8,365-ft) long, 2.4-m (8-ft)diameter storm drain tunnel in Evansville, Indiana. The tunnel was driven through saturated soft ground varying from clay to fine sand. The paper presents: an overview of design and design rational including specific EPB machine requirements; the contractor’s proposed and accepted alternative construction methods and TBM design; and construction issues and performance. Some of the key points discussed are the use of the TBM in different operational modes for alternative ground conditions, the effectiveness of dewatering systems, production rates, and issues such as surface settlements and gas.

Jan 1, 2001

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By K. N. Santini

Natural zeolites are gaining recognition as an important commodity with an increasing number of industrial and consumer applications. This potential has prompted the Anaconda Minerals Company and other firms to investigate occurrences and markets for zeolites. The deposits of mordenite-rich tuff at Rome are of interest for their economic potential and for the excellent opportunity they provide to study a zeolite deposit formed in a hydrologically closed basin. Location The Rome property is located approximately 9 km west of Rome, Oregon, in Townships 31S. and 32S., Range 41E., Malheur County. It lies within the Owyhee Uplands of the northern Basin and Range physiographic province (Figure 1). The area discussed here includes a major portion of the depositional basin in which the zeolitic tuffs occur.

Jan 1, 1982