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By J. C. Rhodes

The demand for good white minerals for many industries including paint and plastics have made it necessary to import high grade industrial minerals from various parts of the world. Some of the calcium carbonate, barite and talc minerals are from China, Mexico, Jamaica and Haiti. These materials can be processed by custom processors. The custom processor can provide a service to the Industrial Mineral owner. The imported materials can arrive in various feed sizes from lumps (3"-6") down to 325 mesh. The materials can also be in various size shipments or container loads. The economics for importing should be investigated thoroughly. The two factors just mentioned can influence the quantity of material to be processed. These two factors can also influence the total cost for each end product.

Jan 1, 1989

As noted by D.W. Fuerstenau in his Plenary Lecture at the Conference on Extractive Metallurgy of Gold and Base Metals, Kalgoorlie, Australia, "Com¬minution of solids is surely one of the oldest technologies that, even in this day and age of DNAs, chips and space exploration, continues to challenge our scientific acumen and engineering ingenuity." Thus, the fundamentals of comminution continue to receive a great deal of attention in the literature. This was particularly true in 1992 with the publication of the proceedings from the SME-sponsored symposium, Comminution Theory and Practice. Papers covering topics ranging from liberation to comminution fundamentals to novel size reduction techniques are included in this review. Liberation Liberation continued to be a prime area of research interest, not only in terms of liberation modeling, but also in understanding the basic mechanisms involved in mineral liberation. King (Comminution - Theory and Practice, pp. 3-15) described a method for determining the interphase area between mineral grains. He showed how the mea¬surement of interphase area before and after comminution could be used to determine the presence or absence of intergranular fracture. Lin, Miller and Cortes (Kona, Vol. 7) discussed the use of computed tomography (CT) as a nondestructive means of investigating three-dimensional particle composition. The use of this technique in constructing coal washability curves from CT data was presented.

Jan 1, 1993

By W. E. Adkins

Ore and waste haulage usually constitute one of the major cost items in the operation of an open pit mine. This has always been true at the Chino mine, one of Kennecott Copper Corporation's western mines, located in southwestern New Mexico. The Chino Mines Division is an integrated operation. The open pit mine, dump leaching operation, and a precipitating plant are located at Santa Rita, New Mexico, and a power plant, mill, smelter, and fire refinery are located in Hurley, New Mexico, about nine miles south of the mine. Approximately 22,000 tons of ore are mined and processed each day; in addition, approximately 42,000 tons of waste are removed from the pit. Originally the pit was located along the side of Santa Rita Creek but it has deepened and expanded so that at the present time, it could better be described as a nearly circular pit about one to 1.5 miles in diameter. The bottom is at an elevation of 5750 feet, the west rim near the ore gathering yard is at an elevation of 6230 feet, and the highest bench on the east side of the pit is at an elevation of 6750 feet, giving a vertical mining depth of 1000 feet. The train waste dumps reach a maximum elevation of 6580 feet. At the present time, Chino uses electric locomotives, off-the- highway trucks, and a skip system for mine haulage.

Jan 1, 1963

By Martha E. Smith

INTRODUCTION Radiation is one of the many agents occurring in our environment that is capable of causing cancers. We are all unavoidably exposed to natural background radiation. If we wish to exploit the beneficial uses of radiation in medicine, industry, and for the production of electricity, some further exposures to radiation are almost inevitable. One needs to ensure therefore, that the standards of radiation protection are safely derived and one would want to understand the mechanism by which radiation might cause cancer and genetic defects. In order to study the effects of radiation one can: (1) analyze human data, (2) perform animal experiments, and (3) do molecular level experiments. Indeed all three kinds of information are needed. This paper will concentrate on the steps required to obtain some of the necessary human data regarding health effects, where the concern is about the impact and consequences of long-term low-level exposures to an agent. Such investigations require some knowledge of work histories, dose histories, health "outcomes", and the personal identification of the individual involved. Three inter-related computer systems have been developed at Statistics Canada which have been designed to permit optimal use of a number of different records for our entire country for such health related research. The development of the Canadian Mortality Data Base, the initiation of the National Cancer Incidence Reporting System, and the development of new computer linkage techniques have helped reduce the cost and increase the scale and efficiency of automated follow-up to produce statistics of sickness or death associated with radiation and other carcinogenic agents in mines. These computer systems have already been implemented, and references will be made to studies currently being conducted using these files and facilities (e.g. a study of all Ontario miners, plus various Canadian uranium, fluorospar, salt and nickel miners). We will also look at the kinds of data that need to be collected now, to improve such studies in the future. DELAYED RISKS - THE STUDY SIZE AND COST Delayed effects on human health, as for example industrially caused cancer, can in general only be detected and measured by following-up the individuals to see what eventually becomes of them. What is not generally recognized is that the relatively low levels of individual risk, about which the public is often concerned, usually requires for their detection that very large numbers of "exposed" and "control" individuals (e.g. 10,000 to 100,000 or more) be followed over a period of two or three decades to determine when they die, what they die of, and whether they contracted cancer or some other disease of special concern. Thus, it is frequently exceedingly difficult to make such investigations cost-effective so that they will be undertaken at all, and as a result very real risks to health can remain undetected or unquantified. THE MANUAL PROCEDURES Follow-up of individuals by epidemiologists has until recently been a largely manual and clerical operation. It has used a diversity of source record files; local, regional, and national. Often the tracing of people has involved letters sent through the mails and visits to institutions, physicians, municipal offices, and former neighbours. Only thus could one find out whether the individuals were dead or alive. Such studies were necessarily small, or else very expensive. Death registrations have, by tradition, provided a valuable tool for the identification of harmful influences in the environment. However, with the increasing mobility in the population, death may often occur far away from the place of exposure to such an influence. Thus, no longer will simple manual searches in a single registry office suffice to inform the investigator concerning the deaths that may have occurred in a study population, especially when that population is large. In the past, manual follow-up to locate the relevant death registration normally required some prior knowledge of the province and year of death in question, so that the alphabetic indexes could he used to direct researchers to the appropriate bound volumes of registration forms. To search manually in this fashion for any large number of death registrations, without knowing in which year or province the deaths had taken place, or even whether they had yet occurred, would be impractical, since each year in Canada there are about 170,000 deaths. DEATH AND CANCER AS SPECIAL ENDPOINTS Much of recent effort has been focused on the organization of the "endpoint" files required to do long-term follow-up studies on a national scale, because that is a function which other institutions are unable to perform due to the confidentiality laws governing the use of such information. Outside organizations generally come to us with detailed "starting" point records which relate to some specific group requiring study. We carry out these epidemiological searches on a cost-recovery basis. The analytical interpretation of results is normally

Jan 1, 1981

By S. Vivek

An atomic force microscope (AFM) was used to measure the surface forces between silica plate and glass sphere in sodium oleate solutions. Hydrophobic forces were observed when the two surfaces were activated by CaOH+ or MgOH+ ions. The force measurements conducted in the absence of the surfactant showed that the activated silica surfaces do not exhibit the primary hydration forces that have been observed between unactivated surfaces. The activation mechanism was studied by calculating the contributions from electrostatic and chemical interactions to the total free energy change. The results suggest that the adsorption of the hydroxo-complexes is controlled mainly by the lateral interactions between the adsorbed species on the silica surface.

Jan 1, 1999

By S. K. Kawatra

It has been observed in some mineral processing plants that grinding circuit efficiency varies seasonally, such as in some plants which are located in the northern U. S. and Canada and undergo large seasonal temperature changes, with the grinding circuit efficiency different between summer and winter. This indicates that the temperature of grinding circuit slurry has a noticeable effect on grinding performance. The effect has rarely been studied. To this end, an investigation to examine the effects of changing temperature on efficiency and determination of the mechanism responsible has been carried out. Plant investigations and laboratory experiments have been conducted in order to study hydrocyclones. It was demonstrated that under otherwise constant operating conditions, the d50(c), size decreased linearly with increasing temperature, while the shape of the reduced efficiency curve remained constant. This effect was determined to be due to changes in slurry viscosity with temperature.

Jan 1, 1988

By Luis Dr. Sobral

In this study, the removal of zinc, cadmium and copper from an aqueous sulphate solution, derived from the biomass desorption process, was examined by using a reaction system with a three-dimensional high surface area electrode (RNiF). This reaction system was found to be extremely effective in reducing metal concentrations to the ppb range. The effect of cathode potential and flow rate were studied for three different nickel foam porosities. In addition, current- potential curves were recorded, at a rotating vitreous carbon electrode, to deter- mine the possibility of depositing the aforementioned metals separately.

Jan 1, 1998

By M. K. Boateng, K. Awuah-Offei

"Mining companies have started using quantitative tools, including computer models of community interaction, to gain intelligence on social risks surrounding their projects. Models of changes in community preferences regarding mining projects over time are useful for evaluating changes in project risk due to changes in the social license to operate. For example, agent-based models that use information diffusion models and social networks are useful for studying those changes due to information diffusion. However, such agent-based models are sensitive to many input parameters including the parameters of the diffusion model and the average degree of the social network. This work evaluates the sensitivity of such a model to diffusion and network model parameters (probability of imitation, probability of innovation, and average degree) using the first order and total sensitivity indices. The results show that the model is much more sensitive to the probability of imitation than the other two parameters. Thus, to reduce uncertainty surrounding the model’s predictions of community acceptance of mining, mines need to obtain accurate estimates of the probability of imitation. INTRODUCTION Mining companies have started using quantitative tools, including computer models of community interaction, to gain intelligence on social risks surrounding their projects. Models of changes in community preferences regarding mining projects over time are useful for evaluating changes in project risk due to changes in the social license to operate. For example, agent-based models that use information diffusion models and social networks are useful for studying those changes due to information diffusion. However, such agent-based models are sensitive to many input parameters including the parameters of the diffusion model and the average degree of the social network. This work evaluates the sensitivity of such a model to diffusion and network model parameters (probability of imitation, probability of innovation, and average degree) using the first order and total sensitivity indices. AGENT-BASED MODEL OF COMMUNITY ACCEPTANCE A few researchers have started using agent-based models to study mining systems (Fujiono 2011; Nakagawa et al. 2013; Bahr 2015; Boateng and Awuah-Offei 2017a, b). Nakagawa and co-workers used ABM to evaluate dynamics of a mining project’s stakeholder networks whereas Fujiono used ABM to study innovation diffusion in the mining industry. Our previous work has presented models and a framework for modeling information diffusion in a mining community and its impact on level of acceptance (a measure of SLO) of the mining project (Boateng and Awuah-Offei 2017a, b)."

Jan 1, 2018

By Kendall Y. Keuhey

The Mercur Mine, developed and operated by Getty Mining Company, is designed to process 3,000 tons/day of gold ore from the historical Mercur Hill mining district. The mill process involves crushing, grinding, and cyanide carbon in leach for recovery of gold ores ranging from 0.08 to 0.10 oz/ton. During the mining of normal grade ore, a substantial tonnage of material containing 0.02 to 0.05 oz/ton is mined and would be available for heap leaching. Also, Getty Mining is developing methods to test and prepare lower grade material for heap leaching by rejecting a course rock fraction from the grinding circuit SAG mill. This lower grade fraction is suitable for heap leaching, and its removal will upgrade the regular mill feed. Other test methods are directed toward leaching techniques on some 4.0 million tons of tailings that resulted from roasting and/or cyanide leaching Mercur ores in the early 1900s. The natural carbons associated with the Mercur deposits require special treatment to reduce their gold adsorption effects when leached with cyanide.

Jan 1, 1983

By William F. Lawrence

Research performed by the West Virginia University Coal Research Bureau under the sponsorship of the U. S. Bureau of Mines has demonstrated that coal-ash can be converted into mineral wool insulation of a quality equal to commercial grade mineral wool. An unexpected benefit has been gained due to the discovery that the usual and costly fluxing agents employed when using conventional raw materials are not required when producing mineral wool from coal-ash. Because coal-ash sources are commonly located close to mineral wool marketing areas and because mineral wool is seldom shipped far as a result of its low weight and high volume, the use of coal-ash may offer the mineral wool producing industry profitable opportunities. Moreover, coal-ash produced from experimental limestone based air pollution control processes also yields high quality mineral wool which may aid in retarding corrosion of metals contacted by the wool. In addition, internal fluxing effects and possible sulfur oxide utilization could provide economic advantages to the use of these "modified" ashes.

Jan 1, 1969

By Daniel McNamee, Wern-ping N. Chen

The Amtrak East River Tunnels include four tunnels, Line 1 to Line 4, which extend from New York Penn Station in Manhattan, under the East River to Sunnyside Yard in Long Island City. Since fall 2015, Amtrak has initiated a program to repair and reconstruct the century-old tunnels, including structural repairs of all the tunnels and reconstruction of the Line 1 and Line 2 tunnels. The reconstruction includes bench wall demolition and replacing and installing the following elements in the tunnels: direct fixation track, traction power, signal, communication, and tunnel fire/life/safety components. This paper provides design and site investigation challenges and knowledge gained from this program.

Dec 1, 2022

By Pramod C. Thakur

During the past ten years, the US coal industry has experimented with various ways to extract methane from coal seams. Drilling long horizontal boreholes in solid coal from mine workings and vertical gob degas boreholes are becoming standard techniques for methane recovery from coal seams. Prime motivations for such work have always been safety and productivity in mines, but the commercial value of gas so produced is encouraging utilization. The paper reviews various ways to produce methane from coal seams and discusses some utilization projects extant in the industry.

Jan 1, 1984

By Louis A. Panek

INTRODUCTION Block caving is distinguished from other types of mining in its requirements that the mineral body to be extracted must cave after a relatively large tabular open¬ing is created underneath it, and that the caving must be predictable and controllable for both operating and safety reasons. A mineral body that caves readily may present special problems with respect to ground support in the mining access openings, where stability, rather than failure, is the desired objective. The complete ex¬traction of a caving block, which may measure 50 to 100 m on a side and 100 to 300 m in height, tends to create a large void, resulting in significant changes in the ground stress system and a migration of rock from all directions toward the void; these events begin very early in the life of the mine and lead to additional spe¬cial problems with respect to control of ground move¬ments in the mine working areas, in the rock adjacent to the caving stope, and on the subsiding surface above the mine. Thus, the mechanics of an undercut-cave operation involve a broad range of geotechnical subject matter, including the determination of the lithostatic earth stresses, the structural properties of a large jointed rock mass, the flow properties of the fragments after caving, the stability of tunnel-like openings, and the stability and displacements of the rock structure (1 to 2 km in size) that surrounds the ore body. The objectives are achieved by in-place measurement of rock properties, laboratory tests, theoretical structural analyses of the related prob¬lems, measurements of structural behavior in and above the mine, and comparison of theoretical predictions with actual performance in order to interpret and refine the predictive capability. Undercut-cave mining (Julin, et al., 1973) differs from most other methods in that the caving is an essen¬tial and inherent part of the excavation process and in¬volves the movements of millions of cubic meters of rock over distances of hundreds of meters, as compared to the gradual 2-m settling of the overburden typical of full¬caving longwall coal mining. Undercut-cave mining may involve a rock mass on the scale of a 1-km diam open¬pit mine, but mining is several times deeper than that in the open-pit mine; furthermore, a large portion of the rock mass is in a failed, rather than a stable, state. Ground-control problems are inevitable in a situa¬tion where ground movements are occurring on such a large scale, and where the rock mass is expected con¬veniently to cave at one location but to be stable at an¬other. To devise effective responses to these ground¬control problems, one needs to know first of all what is happening, not merely at the point where the symptoms are observed, but more broadly with respect to the be¬havior of the entire mine rock-mass structure over the total area of extraction, including the effects on the sur¬face as well as those underground. Monitoring structural behavior on this scale would require a sizable group of people, if they attempted to measure all the significant mining-induced changes of ground displacement and pressure, even on a 100-m grid of points. The practical approach is to conduct the mea¬surements activity by a judicious sampling, making in¬termittent, concentrated efforts in selected areas of lim¬ited extent to study problems of immediate importance; simultaneously a minimum level of surveillance is main¬tained over the total structure to delineate long-term be¬havior trends in the major structure, which provide the baseline reference data that are so essential for interpre¬tive purposes. Mine-structure behavior depends not only on the mine extraction configuration and sequence, but on the rock structural properties and how they change from one location to another in the mine. Increasing attention is being given to determinations of rock strength and de¬formation by performing mechanical properties tests in place and in the laboratory, and by drawing inferences from the mapping of geologic structure in mine openings as they are driven and from the logging of cores ob¬tained from exploration drilling that may be performed primarily for delineating ore reserves. Monitoring of mine-structure behavior and inter¬preting it in terms of the growing excavations and the structural properties of the rocks have significant im¬pacts on designing the major undercut-cave operations of undercutting and drawing the ore, supporting the ac¬cess openings, and controlling surface subsidence. The purpose of this chapter is to call attention to the com¬mon ground-control problems encountered in undercut¬cave mining, to relate them to the mining process, and to explain the geomechanical approaches to analyzing these problems with emphasis on methods that are most readily available to the mine staff. UNDERCUTTING, CAVING, AND DRAWING A distinguishing characteristic of an undercut-caving method of extraction is the objective that the rock mass fails of its own weight in a predictable and controllable manner, after it is undercut by excavating a tabular¬shaped void, horizontal or inclined. Induced or forced caving refers to procedures that may be resorted to when the ore will not self-cave over the desired span. Block caving, panel caving, and mass caving are terms used to denote the particular sequence of undercutting and ex¬tracting the total area of the ore body on a single min¬ing level. The discussion herein is not specialized to any of these variations; the word block as used does not imply anything as to sequence. CREATING THE UNDERCUT A common undercutting method is to drive a series of drifts and blast the intervening pillars. Theoretical structural analysis and practical experience show that ground-support problems in the undercutting drifts and in underlying access openings as well (the same princi¬ple applies even if undercutting is done by belling out drawpoints from the slusher drifts) are minimized by retreat-mining across the undercut slot according to a sequence such that the growing undercut area retains a

Jan 1, 1982

By Y. C. Kim

This paper reviews the past 18 months of geostatistical work in a coal deposit performed jointly by the University of Arizona and the Homer City Owners. The objective of the study was to better predict the in-seam sulfur values of the deposit for the purpose of future emission control. Based on initially available 112 DDH information, variogram models were developed for Sulfur, Ash and Thickness for the entire deposit. The deposit was then kriged using 333 m x 333 m (1000 ft x 1000 ft) panel size. The estimation variance information obtainable from geostatistics was next utilized to improve the development drilling activities that were underway. The results of this effort are presented in this paper. In addition, this paper describes (1) the reasons for preferring kriging over the conventional isopachs, (2) the results of empirical validation of the kriged estimates using 19 additional DDH information, and (3) up-to-date experience on the use of conditional simulation of the same deposit for the future emission control strategy development.

Jan 1, 1980

By John Newby, Ulf Gwildis, Fred Marquis

From the Brightwater Conveyance System in Seattle to the Second Narrows Water Supply Tunnel in Vancouver, BC, the design and construction of deep-lying tunnels in the Pacific Northwest often require the incorporation of deep portal shafts. Alluvium overlying marine and glacial deposits combined with the high regional seismicity is the common geologic setting. The latest example illustrating the development of shaft design for this scenario is the 40-m-deep shafts of the Annacis Island Wastewater Treatment Plant New Outfall System. The main components of the shafts include the initial lining, providing the excavation support system to be used for launching and receiving a 5-m-diameter TBM; and the final lining, designed to withstand all static and seismic loads and to remain viable for the intended design life. This paper presents design and construction considerations for these shafts against the background of and lessons learned from past project experiences.

Jun 13, 2021

By William F. Riggs

Inspiration Consolidated Copper Company, located in a semi-arid climate in Arizona, continually struggles with a water problem. This applies to quality as well as quantity. When the EPA considered installing a new centralized sewage plant to handle the combined waste from the municipalities of Globe and Miami, Arizona, they automatically assumed that He could use the sewage effluent for process water in flotation. The treatment plant was to be a tertiary system producing 1600 gpm of sewage effluent. Inspiration decided that this could possibly be a source of additional process water. It was decided to test sewage effluent from Miami Treatment Plant at the rate of 400 gpm since it was only a primary treatment plant. The 400 gpm was combined with the 5000 gpm of process water going to the Concentrator. After one week the results were disastrous. The recovery and final grade had each dropped approximately 5%. With the results from this brief run, it was concluded that sewage effluent from a primary treatment plant could not be used. Research was then brought into the problem to begin an evaluation of sewage effluent in flotation.

Jan 1, 1977

By Kent E. McElhattan

The selection of efficiency machinery for an underground mining system is a highly skilled art. Modern techniques of mining, based on sound engineering principles, increase the probability of success. These techniques alone, however, will not guarantee maximum productivity. Human judgement, based on experience with mineral seams and geological conditions, remains the single most important input of the decision-making techniques in selecting high production equipment. The myth of a "Scientific Selection Factor" is absurd. The belief that such a factor exists can waste the time and resources of mining management. Until now, mineral extraction from the original desposit has defied all attempts to systematize the knowledge. Computerized programs are excellent for solving underground transportation and ventilation problems. The variables can be defined by mathe¬matical techniques in this type of problem. By the same, token, "Trial and Error" is not an acceptable method in today's technology-minded world. The candid truth of the matter is that practically nothing is known of the phenomenon of extracting a mineral from the solid. Likewise, local conditions make it nearly impossible to predict accurately the reaction of surrounding strata after the mineral has been removed. The unpredictability of the environment resulting from extracting minerals underground will remain a challenge to mining engineers for many years. In fact, we are barely beyond the trial and error stage at this point in time.

Jan 1, 1969

By Y. C. Lo

This paper presents the development of ultrasonic grinding technology for material and mineral processing. The principles underlying this new technology, as well as their implementation in two laboratory scale devices are described in detail. Ultrasonic grinding experiment results are discussed with respect to operating variables and the achieved product sizes. Special attention has been given to the electrical energy consumption of the grinder, and an attempt to compare its efficiency with tumbling mills has been made. A mechanical system capable of measuring the specific grinding energy is also described.

Jan 1, 1991

By N. C. Miller

In situ stope leaching is an innovative mining system that reduces the surface impacts of conventional underground mining. As in any leaching operation, stope leaching requires hydrologic site characterization and control of leaching solutions. Several tracer tests, using sodium chloride (NaCl) in various concentrations, were conducted by the U. S. Bureau of Mines (USBM) in an underground experimental stope to simulate a leaching environment. The tests were conducted in fractured crystalline rock that was partially saturated. As tests progressed, the surrounding fractures became more saturated. A predominant flow direction away from the stope was found during testing. Testing procedures, preliminary results, and remediation ideas based on field observations are presented in this paper.

Jan 1, 1995

Rendering a solid hydrophobic and solid-fluid particle* attachment in flotation are recognized as not necessarily related (1,2). The attachment is governed by forces of attraction and repulsion which need to be considered. The induction time required for attachment after solid and fluid particle are brought into proximity (3-8) illustrates the point. Laskowski(8) showed that a reduced induction time favoured flotation but detected no change in contact angle, a standard indication of solid surface hydrophobicity. Induction .time is observed in fluid-fluid particle coalescence, there being called a rest time (9-11) The induction time phenomenon is related to the presence of a metastable liquid film (disjoining film (2)) of the continuous phase (water in flotation) which must thin and rupture to permit attachment. The lifetime of this film, which is governed by the rate of thinning and the probability of rupture with thicknesss, depends on a complex interaction of forces. Investigating these forces should help clarify the attachment process. Practical benefits would be improved understanding of slimes flotation (12,13) This paper is concerned with the role of the mobile fluid particle-water interface on the film lifetime, in particular, the role of time-dependent or dynamic interfacial properties resulting from deformation of this interface.

Jan 1, 1975