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By G. I. Mathieu

Research and development studies were carried out at the Canada Centre for Mineral and Energy Technology to produce a synthetic forsterite sand from asbestos tailings for Les Sables Olimag Inc. The National Research Council of Canada also supported and collaborated to the project. Theoretically, the technological approach consists of a heat at over 1300°C; however, the process without additive would result in the production of an enstatite-rich product (MgSiO3) having a fusion temperature less than 1600°C. The purpose was to foster the formation of forsterite (Mg2SiO4), a more refractory compound. The fabrication of the forsterite product requires pre-agglomeration of serpentine-MgO with a binder, which is stable at high temperature, to prevent the loss of the powdered magnesium oxide as dust in the kiln off gases and to maintain the mixture homogeneous during the process. Characterization of the end products with respect to mineral composition and thermal resistance are described. The synthetic forsterite in sand form was tested with success under a bath of liquid steel maintained at 1700°C for up to two hours. The advantages of the new sand and its potential applications will be reviewed.

Jan 1, 1992

By R. P. King

A new device, called the dual impact load cell, has been developed and built at the Comminution Center to measure fracture energy and damage accumulation in brittle particles that are subject to impact. The results show that damage accumulation during impact is not a significant factor in determining the fracture energy or the particle strength. However, predamage induced by thermal pretreatment of the particles has a significant effect on both fracture energy and particle strength.

Jan 1, 1995

By Larry A. Lien

Membrane technology has been available for about 30 years, but has been used very sparingly within the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and element cleaning techniques have improved the reliability and robustness of membrane based systems. These improvements have expanded the potential to use this "new" technology to enhance critical recoveries of gold and silver in heap leaching operations or in the extraction circuit. Another opportunity for the mining industry will be to use membrane technology in new processes like controlling organic acids or ammonium thiosul­fate to enhance gold and silver extraction during leaching opera­tions. Finally, the most common use for membrane technology is for the control of mining water balance and acid mine drainage issues. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold or silver. Recent applications have been developed for spi­ral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operated on feed streams from 200° C to 3000 centipoise. Most recently, membrane based systems have been pilot tested suc­cessfully to purify solvents, like LIX. Opportunities exist to apply membrane technology to concen­trate gold and silver cyanide solutions with thin-film composite Reverse Osmosis (RO) membranes at elevated pH values above 10. Incorporating membrane technology could allow one to increase production without incurring additional expansion of the gold extraction side of the process. Furthermore, free cyanide is not rejected by the Reverse Osmosis membranes, but other inorganic salts are rejected 98+%, thereby, allowing an essentially ion free, except for the free cyanide, to be recirculat­ed back to the heap leach operation for enhanced extraction.

Jan 1, 1998

By R. W. Guill

For the past five years, Small Mine Development has been involved in the development of small grade underground projects. These projects have been in tough environments where solutions have been found by placing emphasis on creative collaborations by small work forces and selected specialists. This has created an environment where constant innovation and change have become standard operating practice. The cornerstones of these efficient operations have been formed using pneumatic backfill, creative shotcreting, specialized equipment, and highly motivated people. The results realized have served to turn interesting properties into productive operations.

Jan 1, 1988

By Andrew Cushing, Joe Carvalho, Jon Hurt

"INTRODUCTIONThe shales of the Greater Toronto Area (GTA) have been known to experience time-dependent deformations (TDD); those initiated by excavation-induced stress relief which progress with time as a function of rock porewater salinity, access to freshwater (or air) of lower salinity, clay and calcite content, and the buildup of swelling pressures within the rock mass. These deformations can induce long-term pressures on shaft walls and tunnel linings, especially if the permanent works are constructed soon after excavation, with very little time delay. This paper presents measurements of time dependent deformation of recent shaft and tunnel projects constructed in the GTA, and draws conclusions regarding the main influences on the TDD. The key input parameters for the numerical predictive model are critically assessed. Projects which are discussed include the Billy Bishop Airport Pedestrian Tunnel, Hydro One Midtown Tunnel and Hanlan Feedermain (Contract 3).MECHANISM OF TIME DEPENDENT DEFORMATIONExplanation of MechanismThe Georgian Bay Shale unit consists of typically moderately weathered to fresh, grey to dark grey, fine to very fine grained fissile shale interbedded with slightly weathered to fresh grey, fine grained calcareous siltstone and limestone interbeds. There are two distinctive features of the shale in the Greater Toronto Area (GTA). One is a high horizontal stress regime, and the second is long-term time dependent swelling behavior which develops when the following factors occur (Lo and Micic, 2010):• Stress relief of the rock mass• Outward salt concentration gradient from pore fluid of the rock to the ambient fluid• Availability of fresh waterThe swelling is a consequence of the reduction in confined stress in the rock which occurs upon excavation in combination with a differential gradient in salinity between the saline rock porewater and freshwater or even humid air. Osmotic and diffusive processes result in a decrease in the salinity of the rock porewater achieved by an overall increase in the water content, resulting in volumetric expansion of the shale rock over time. The development of this time dependent deformation (TDD) relative to the time"

Jan 1, 2016

By Arthur R. MacPherson

Primary autogenous grinding has been in general use for somewhat over 20 years. During this period there have been many highly successful plants built on this principle, while some others have had problems such as: 1. Not performing as predicted from test work. 2. Highly fluctuating tonnage rates. 3. Mechanical problems. 4. High liner wear. Many of the problems with commercial autogenous mills have resulted from improper sampling and testing of the ore during the development period. It is recognized that the fully autogenous mill is very sensitive to any changes in grindability which may occur in the feed to such a mill. The semi-autogenous mill is somewhat less sensitive, but large swings in grindability of the feed require adjustment of ball charge and this cannot be easily accomplished in a short period of time.

Jan 1, 1976

By Eric R. Braun

Ore reserves in the Republic mining district were nearly exhausted in 1984 when hole D-54 intersected a vein twenty- eight feet in drill width averaging 1.57 opt gold and 11.95 opt silver below post-mineral lake beds. The discovery area, termed "Golden Promise", has announced proven and probable ore reserves of approximately 372,000 tons averaging 1.0 opt gold and 4.5 opt silver, and drilling indicates another 756,000 tons of mineralized material containing 0.37 opt gold and 1.4 opt silver (Hecla fourth quarter 1986 report). This paper describes new geological interpretations made as part of a district research study sponsored by Hecla Mining Co., which led to the D-54 discovery. Important new geological concepts include: 1) re-interpretation of the volcanic stratigraphy of the district and recognition of a suite of pyroclastic rocks that are unique to the Republic graben, 2) identification of disseminated subaerial mineralization at a paleosurface that corresponds to the newly described upper contact of the Sanpoil Volcanics, 3) recognition that epithermal veins have a maximum productive vertical range of 0-500 meters, measured from the paleosurface, and 4) veins exhibit visual and geochemical vertical zoning within the productive zone with highest gold occurring at an optimal depth, which is interpreted as the average depth of hydrothermal boiling.

Jan 1, 1987

By R. Latifovic

Assessment of the possible impact of existing and future mining projects located in remote areas may be difficult and costly. This may have an adverse effect on the process of issuing mine permits and development of new mines. A remote sensing based land cover change assessment methodology presented in this paper is a promising avenue to render this process more meaningful, precise and affordable. It has been applied to a case study of the Oil Sands Mining Development in the north-east of the Canadian province of Alberta. Recently, the Athabasca Oil Sands Region (AOSR) is a place of unprecedented growth of open-pit mining operations. This study was focused on the primary impact onto the landscape and vegetation resulting from exploration and, mining development. This impact was assessed using an information extraction method applied to two LANDSAT scenes. The analysis based on derived land cover maps shows a 8.64% decrease of natural vegetation in the study area (715,094 ha) in 2001 relative to 1992. It is demonstrated that the methodology presented here provides reliable results and is fully applicable for the assessment of the environmental impact of large scale mining operations.

Jan 1, 2006

By Fathi Habashi

ION FLOTATION was introduced by F. Sebba in 1959. This technique permits the recovery of metal ions from solution through the introduction of an appropriate cationic or anionic surface-active agent into the solution. The surface-active agent, called a collector, is added in stoichiometric amounts in relation to the metal content of the solution. It reacts with the metal ion to form an insoluble soap, and is levitated to the surface by gentle bubbling of air to form a foam which collapses into an insoluble scum. The optimum conditions for the ion flotation with soaps of C10-16, fatty acids are shown in Table 15-1. Baarson and Ray (1965) found that once the metal was completely precipitated as the hydroxide, as little as one hundredth the stoichiometric amount of the collector was required to cause complete flotation of the [ ]

Jan 1, 1970

By Dale J. Sadowski, Richard J. Switalski, Kyle R. Ott

This paper discusses design and construction aspects of shaft construction through rock saturated with petroleum hydrocarbons (crude oil). During the subsurface exploration phase for design of the Hilltop Interceptor project in Cleveland, Ohio natural crude oil was encountered at depths between 6.1 and 61 m below ground surface. The oil-saturated Euclid sandstone contained up to 12,000 mg/kg total petroleum hydrocarbons (TPH), various volatile organics, and had flash points as low as 18.9°C. Interceptor hydraulic design required that construction of access and/or drop shafts penetrate the layer of petroleum hydrocarbon saturated rock. This led to the design of a special lining and some special handling procedures for the excavated material.

Jan 1, 1995

By M. Tokoglu

Accurate estimation of resources is one of the major challenges in mineral project evaluation. Contemporary mineral resource estimation practice calls for contribution from several disciplines and execution of several interdependent tasks. 3D estimation domain modelling is obviously one of the most essential components of such a substantial process which forms the basis of this research. The study constitutes a comparative analysis of four major domain modelling techniques; (i) explicit modelling, (ii) implicit modelling, (iii) indicator kriging, and (iv) conditional simulation. It involves comparison of outcomes for alternative scenarios to assess the implications of the modelling decision on resource estimates of a polymetallic massive sulfide deposit located in western Turkey. Thus, identical grade estimation method and parameters are considered to identify the discrepancies arising only from the choice of the domain modelling approach and underlying assumptions. Economic implications are demonstrated in the form of range of outcomes for the extends of the ultimate pit, ore tonnages (min:37.0 Mt, max: 46.7Mt), waste tonnages (min:201.2 Mt, max: 251.2 Mt), stripping ratios (min:5.18, max: 5.71), and total pit values (min: $1.05B, max: $1.45B). Examination of solid models as well as cross-sections revealed that major discrepancies are observed beyond outlying drillholes. Therefore, it has been proposed that assumptions regarding extrapolation distance is the main source of mentioned dissimilarities. Key words: Domain modelling, explicit modelling, implicit modelling, indicator kriging, conditional simulation INTRODUCTION Resource estimation is apparently a challenging process calling for extensive expertise and input from several sources, each of which introducing its related uncertainties. In the last decades, substantial role of quantitative analysis of several forms of risk and uncertainty in evaluating projects’ upside potential and downside risks has been realized. Studies indicated that mining companies have been severely impacted because of not meeting project expectations. As noted by Vallee (2000) “… in the first year of operation after start-up, 60% of mines surveyed had an average rate of production less than 70% of designed capacity”. Several other studies on mining projects also revealed that uncertainties related with the resource model are one of the major contributors of mentioned shortfalls. In this perspective, quantification of uncertainties associated with each component of estimation process is critical. 3D estimation domain models capturing major mineralization controls are the fundamental components of contemporary mineral resource estimation. Domain models are key guiding tools for estimation and are products of a complex process involving many unknowns and assumptions. There exists a number of 3D modelling alternatives which are distinct with respect to complexity, time and effort involved. Acknowledging potential influences on downstream mining practices and relavent economic implications, risks and uncertainties associated with 3D domain modelling are critical yet poorly studied aspects.

Jan 1, 2019

By A. W. Scaroni, C. Y. Tsai

The effect of particle size and composition on the pyrolysis and combustion of a pulverized bituminous coal in an entrained-flow reactor has been investigated. Predicted time-temperature histories of the coal particles and experimental weight loss data indicate a strong coupling of heat and mass transfer to the pyrolysis and combustion rates. A higher combustion rate following ignition was observed as particle size was increased to 112 µm (about 140 mesh). This is related to a higher particle temperature after ignition for the larger particles. Although the heating rate before ignition decreases with increasing particle size, higher slip velocities and surrounding gas temperatures for the larger particles promote early ignition. The presence of liptinite in the coal increases the weight loss rate before and immediately after ignition. Similar behavior was observed for pyrolysis. Fractions of an HVA bituminous coal that were rich in mineral matter or semi-fusinite were found to have a higher heterogeneous char combustion rate than vitrinite-rich samples.

Jan 1, 1987

By David M. Abbott

"The picture of the baby surrounded by the number of (usually) pounds of a variety of mineral products a newborn will use in a lifetime has been widely distributed over the years, both on the web and as business cards that could be distributed to anyone. Figure 1 shows a typical example. I have included a slide of the mineral baby in various lectures over the years, particularly in my lecture “Industrial minerals: much used, little recognized.” The mineral baby with associated estimated lifetime mineral quantities is updated every year. I collected a set of past mineral baby pictures to examine the changes in the quantities of the various mineral products over the years.The mineral baby was introduced by the Minerals Information Institute (MII) in 1999 and became known as the “MII Baby.” SME took over MII in 2008 and continued publication as the “MII Baby” until the merger of MII with SME’s GEM program in 2011 to form SME’s Minerals Education Coalition (MEC). MEC is now the publisher. Figure 2 is the 2016 version of the mineral baby. The repositioning of the picture of the baby from lying on its back to crawling reflects a major design change to help emphasize that SME’s MEC is now the mineral baby’s publisher.Data sourcesThe data used to prepare each year’s mineral baby comes from the National Mining Association, which collects the preliminary annual mineral commodity data from the U.S. Geological Survey (USGS) and other sources. This preliminary data becomes available late in the first half of each year. The life expectancy data for each year comes from the Center for Disease Control’s “Data and Statistics by Topic” and the population data comes from the U.S. Census Bureau’s “Quick Facts” tab.The source mineral data is compiled using metric tonnes as the basic unit. The quantity of of each mineral is the apparent U.S. consumption each year."

Jan 6, 2017

By T. Veneroso

Comminution is the process by which rock or ore is reduced to a size where the liberation of the minerals is maximized without changing the chemical or physical properties of the rock. Comminution accounts for about 50% of all energy that mines use (Klein et al., 2018). Growing demands from stakeholders and shareholders for sustainable development and CO2 reduction will increase the need for energy-efficient comminution. Ores with different mineralogical characteristics, textures, strengths, apparent stiffness, and mass-specific fracture energies need to be processed with a specific, new, and efficient comminution technology to increase the production and profitability of mining companies. The adoption of crusher wear parts built with new materials, such as non-Hadfield manganese steel or synthetic materials or traditional manganese with wear-resistant components, could improve the efficiency of the crushers, reduce downtime, increase production, improve the desired P80 (the aperture through which 80% of the product will pass) product size distribution, and enhance mine safety.

Feb 1, 2023

By Andrew S. Lain

Before you begin mining aggregates in Oklahoma, you must first look at the market and ask these questions: (1) Is there a need for additional aggregate production? (2) Can we produce the aggregate efficiently enough to compete? (3) Is the deposit close enough to the market? If you can answer "yes" to each of these three questions, then you are ready to start the process for mining aggregates in Oklahoma. The first consideration to be made is whether the aggregates produced will need to meet state specifications. If you do not want to meet state durability standards, there are numerous formations you can mine and produce aggregates. We will deal only with the formations that will meet state durability standards. These formations are located in the southern half of Oklahoma and in the Tulsa area. Some of the formations that contain limestone, dolomite, and sandstone that will meet state durability tests are West Springs Creek, Kindblade, McKenzie Hill, Butterly-Royer, and Rush Springs Formations. Granite and rhyolite also are found in Oklahoma and can be used as construction aggregates. Once an area has been identified as having durable material, and drilling has verified its properties, a permit must be secured from the Oklahoma Department of Mines, Oklahoma Department of Environmental Quality, and any other applicable agency before construction of a plant occurs. There are many different brands of crushers available, but all work on one of two crushing principles-either compression breakage or impact breakage. Each type has its application in different industrial-mineral types and the desired end product. A typical small crushing plant would start with a jaw crusher for primary reduction, and then employ one standard cone and one shorthead cone for secondary reduction. One grizzly would be in the circuit with one finished-product screen and three to four finished-product stackers. Natural sands and gravels are found in rivers and old river channels. These too need to be tested to see if spec product can be produced. All of our sand operations have very little gravel; thus, we do not process the gravel. The sand is processed through classifying tanks for gradation.

Jan 1, 1999

By Harold Gibson

The mechanisms leading to the impact of airborne dust particles onto bluff flow obstacles have been extensively reported [1] and widely applied in dust measuring instruments (e.g., impactors) and in dust collecting devices (e.g., filters and scrubbers). If the human head is regarded as a bluff body, particles from dusty flowing air can impact onto the face by virtue of those mechanisms. While a great deal has been researched and written on the nuisance caused to human beings by the entry of dust particles into the body by inhalation through the nose and mouth, there appears to be nothing reported in the scientific literature about the irritation which can be caused by the impact of dust onto the face. And yet there is sufficient evidence to suggest that in certain working environments and under certain conditions, the problem is indeed a real (albeit subjective) one. In the coal mining industry, underground workers are exposed to conditions, involving dust-creating production and handling processes on the one hand and high ventilation rates demanded by the gassy nature of the environment on the other, in which the problem can exist. At the coal face, for example, the movement of powered roof supports ("chocks") can release bursts of dust formed by the crushing action of the supports, which in turn is entrained into the moving air and impacts onto the faces of miners working just downstream. The dust in question contains a large proportion of coarse particles which, while still fine enough to remain airborne for appreciable distances downstream of the point of release, are coarse enough to produce sen¬sation on impact with the skin. Adverse subjective response of workers to such irritation could damage morale and productivity. We have performed laboratory and field experiments to investigate the psychophysical and physiological responses of human subjects to dust impacting onto the face and into the eyes. Since this appears to be the first systematic investigation into these questions, the aim has been to construct a useful scientific framework from which to allow characterisation of the problem of such "fly-dust", and, ultimately, the development of methods for monitoring and controlling it. The main results of our research are given here; the theoretical and experimental details will be presented at greater length elsewhere.

Jan 1, 1980

By M. Stuart

The copper-silver-mercury orebody of Gortdrum Mines (Ireland) Limited is located 3 miles north of the town of Tipperary in the Republic of Ireland. A drilling programme from 1964 to 1966 delineated an ore¬body of 4.19 million tons of copper ore assaying 1.19% Cu and 0.75 ozs per ton Ag, which could be mined from an open pit. Testwork having shown that the ore was amenable to conventional flotation techniques, it was decided to build a concentrator of 500,000 tons ore per year capacity. Stripping of the open pit commenced in 1966 and in the autumn of 1967 the concentrator started up. The first shipments of concentrates were made to the smelter in Europe in late 1967. In the spring of the following year, word was received from the smelter that these early shipments contained between 1% and 2% Hg, and that the smelter could not accept further shipments of this quality.

Jan 1, 1973

By P. Gelfi, G. Hill, A. Showell, V. Martins, R. Dunne, R. Jenkins

Carbon attrition losses are not usually a prime consideration for CIP equipment selection and CIP plant design. However, the costs as a result of carbon attrition and associated gold lost with carbon can be high. Recorded carbon losses for Newcrest operating gold plants were shown to vary widely from plant to plant. The Tuckabiana plant recorded an overall loss of only 0.3g carbon /t ore which is very low by industry standards. A comparative carbon management study was undertaken by Newcrest to highlight the reasons for the excellent record of Tuckabiana operation compared to other Newcrest plants. This paper discusses the results of the comparative study and high­lights areas of concern with respect to carbon attrition.

Jan 1, 1995

By T. Faulkner, S. A. Richards

"The Scale-Distance formula is one of the primary means of determining the maximum amount of explosives that can be safely detonated at one time by a single delay. This paper describes a method of applying the Scale-Distance formula to the entire mining area using gridded surfaces. Using this technique, the operator can better determine the economic impact of nearby structures on the mine plan. INTRODUCTION As the surface mining of coal and stone encroaches near populated areas, precautions must be taken to minimize blast vibration damage to protected structures. The common method employed to minimize vibration damage is not to reduce the total amount of explosive in the hole (which would negatively affect fragmentation), but rather to introduce delays to reduce the amount of explosive detonated at any point in time. The Scale-Distance formula, an industry-accepted standard, may be used to calculate the maximum weight of explosive that can be detonated at one time without damaging the structure. This information may then be used to determine the number of delays required for each hole. Detonators make up a large part of the cost of blasting. At roughly $15 per detonator an additional detonator in the hole can be significant. It is normal to set off hundreds of holes at in one shot. An additional detonator in each hole can cost additional thousands of dollars per shot. The number of detonators is also a function of the depth of the holes and the hole spacing. Being able to accurately forecast the economic impact of blasting near structures improves a company’s ability to make informed decisions on how to approach property owners. Operators basically have three options when dealing with property owners: 1. Buy the property and blast without restriction 2. Negotiate with property owner for a waiver to allow unrestricted blasting 3. Comply with the legal blasting restrictions This paper proposes a method for the engineer to forecast for all points in the proposed mining area the impact of nearby structures upon the blast design. Being able to create a contour map and ultimately estimate the number of delays required for the entire forecasted mining area, the engineer can create accurate economic forecasts of the cost of blasting. The objective is to reduce the level of uncertainty in the forecast of the blast component portion of the forecast."

Jan 1, 2016

By David R. Quigley, Patrick R. Dugan

First reports of microbial coal solubilization appeared in the early 1980's (Fakoussa, 1981; Fakoussa and Truper, 1983; Cohen and Gabriele, 1982). These degradations, which occurred at ambient temperature and pressure, resulted in a dark brown to black viscous liquid and required days to weeks to occur. Rates and degrees of coal biodegradation varied from coal to coal. Hard coals were not extensively degraded (5-7%) while low-rank coals such as Leonardite, a sublignite, were completely solubilized. A correlation between degree of weathering or oxidation of coal and the coals susceptibility to biological attack was observed. This led to oxidative pretreatments as a method to enhance microbial degradation of coal (Strandberg and Lewis, 1986). Products of microbial degradation of coal are water soluble solids that do not have significant solubilities in organic solvents (Wilson, et. al., 1987; Quigley, et. al., 1987; Quigley, et. al., 1988a). Solutions of solubilized coal did not separate or form precipitates which suggested that they were true solutions and not colloidal suspensions. Biosolubilized coal contained more oxygen than starting material suggesting that microbial attack of coals involved oxidative cleavage of carbon-carbon bonds. This small change in oxygen content was the only change observed in coal structure during the biosolubilization process. Many coal solubilizing microorganisms have been isolated. Some are lignin degrading organisms such as Phanerochaete chrysosporium and various Streptomyces species (Gupta, et. al., 1988; Wilson, et. al., 1987). This was not unexpected since the structures of lignin and low-rank coals are similar. These organisms produce an enzyme complex, ligninase, that utilizes hydrogen peroxide to oxidatively cleave the bond between a and ß carbons of an aliphatic chain bound to an aromatic nucleus. Another important organism is Trametes versacolor (syn. Coriolus versacolor, Polyporus versacolor). Even though this organism produces a ligninase (Dodson, et.al., 1987), coal solubilization has been attributed to the enzyme laccase (Pyne, et. al., 1987). Laccase utilizes molecular oxygen to oxidatively cleave a - ß bonds using a mechanism similar to that observed for ligninases (Kawai, et. al., 1988). Other coal solubilizing microorganisms have been isolated from coal outcrops (Ward, 1985; Ward, 1988), but enzyme activities responsible for coal solubilization have not been identified. Research at the Idaho National Engineering Laboratory has focused on those mechanisms involved in coal biosolubilization. An

Jan 1, 1989