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By J. D. Miller, C. L. Lin

As the techniques and resolution for three-dimensional spatial analysis have advanced in the last decade, it is now possible to map in detail the microstructure of multiphase materials in three-dimensional digital space. In this regard, three-dimensional X-ray microtomography offers a unique imaging capability. Spatial resolution on the order of 10 µm can be achieved with the use of microfocus X-ray generators. Recently, a state-of-the-art cone beam X-ray microtomography system was installed at the University of Utah for the quantitative analysis of multiphase materials in three dimensions. This facility was designed to obtain 2,048 by 2,048-pixel reconstruction over a 10-mm diameter, while also allowing for the imaging of somewhat larger (40-mm) objects. The system is capable of handling high-density materials, even materials having a density as high as 8.0 g/cm3. This unique, one-of-a-kind instrument can be used to obtain three-dimensional spatial reconstruction for many applications, such as three-dimensional liberation analysis, pore structure analysis of particle beds during filtration and the air-void system of concrete structures. The utilization of X-ray microtomography not only allows for the quantitative analysis of multiphase systems but also allows, for the textural characterization and determination of phase continuity. This paper presents information regarding the current use of this new facility and a review of potential applications for the advanced analytical system. Key words: Cone beam X-ray microtomography, Three-dimensional analysis, Material characterization

Jan 1, 2003

By Z. Jin, D. DePaoli, P. Zhang

"Phosphorite, or phosphate rock, is the most significant secondary rare-earth resource. It contains high amounts of phosphate-bearing minerals along with low contents of rare earth elements (REEs). In Florida, about 19 Mt of phosphate rock are mined annually and most are used to manufacture fertilizers using a wet process, in which sulfuric acid reacts with phosphates to produce phosphoric acid and phosphogypsum. In the wet process, REEs are also leached out into solution and eventually get lost in the leaching residue and phosphate fertilizer. Recovering REEs from Florida phosphate rock in the wet process will be beneficial to broadening rare-earth availability, improving the quality of phosphoric acid product and protecting the environment.This study focuses on the influences of wet-process operating conditions on REE leaching efficiency. The results indicate that REE leaching efficiency increases with phosphoric acid addition in the initial pulp. At a temperature of 75 °C, a stoichiometric ratio of sulfuric acid (H2 SO4 ) to calcium oxide (CaO) of 1.05 and a weight ratio of liquid to solid of 3.5, REE leaching efficiency reached a relatively high value of 52.82 percent. The trends of REE leaching efficiency were similar to those for phosphoric acid (P2O5 ). Extensive tests on the leaching residue showed that during leaching, about 90 percent of the REEs were released from the phosphate rock but only 52.82 percent ended up in the leaching solution. This phenomenon can be attributed to two factors: (1) the effect of phosphate ions (PO4 3-) in the solution, which caused REE ions to form REE phosphates and be precipitated into the leaching residue, and (2) the influence of large amounts of anions such as sulfate (SO4 2-), dihydrogen phosphate (H2 PO4 -) and hydrogen phosphate (HPO4 2-) anions as well as the polar molecule H3 PO4 , which surrounded the REE cations and formed an ion atmosphere that prevented the PO4 3- from contacting and combining with REE cations. Interaction of these two opposite effects determined the REE distribution between leaching solution and residue."

Jan 1, 2017

By Feridon Ghadimi, Saeed Mojeddifar, Massume Khavari

Separation of geochemical anomalies from background is an important and essential issue in the exploration of mineral deposits. Statistical methods are used to separation of anomaly from background. Fractal/multifractal and singularity methods are very suitable for the separation of weak anomalies. For interpolation, various methods could be used such as most distance-weighting methods, kriging, spline interpolation, interpolating polynomials, and finite difference methods. This paper addressed application of multifractal techniques together with finite difference procedure to detect the anomalous regions. Fractal models such as concentration–area, spectrum–area, and singularity index model were selected to identify Pb–Zn anomalies. In this research, 170 samples from 33 boreholes were taken in the Haft-Savaran area and analyzed for determination of Pb–Zn anomaly. Singularity method was a suitable method for separating Pb and Zn anomalies. Also, the results showed that the geochemical anomaly has occurred along NE–SW trend and is consistent with the sulfide mineralization process and the faults of the region.

May 18, 2020

By L. V. Wade

The use of longwall/shortwall mining systems is under increasing scrutiny by the U. S, coal industry as a means to reverse the decline in productivity. The success of these mining systems depends to a great extent upon designing the system hardware to best suit local conditions. Of particular importance in this regard is designing the various elements of the total ground support system, including face, face end, and gate road supports, to accommodate local geologic conditions. This presentation centers on the problem of selecting the face support system. The existing geologic situation can influence the selection of the face support hardware in a variety' of ways. In general terms, these influences can be grouped into the following four areas: 1. The capacities required of the support unit; 2. The roof, coverage supplied by the support units; 3. The flexibility required of the support unit to meet changing geologic conditions; and 4. The required stiffness characteristics of the individual support units both vertically and horizontally. The following will center on the first area, i.e., the required d capacities of the support unit, in particular, the maximum required load density for a particular geologic situation.

Jan 1, 1976

?Energy-related systems: wind, solar, electric are typically materials intensive. As new technologies are widely deployed, significant quantities of the elements required to manufacture them will be needed. However, many of these unfamiliar elements are not presently mined, refined or traded in large quantities, and, as a result, their availability might be constrained by many complex factors. A shortage of these ?energy-critical elements? could significantly inhibit the adoption of otherwise game-changing energy technologies. This, in turn, would limit the competitiveness of the U.S. industries and the domestic scientific enterprises and, eventually, diminish the quality of life in the US.? -Energy Critical Elements: Securing Materials for Emerging Technologies?- American Physical Society, 2011.

Jan 1, 2012

By Edita Vircíková, J. B. Hiskey, Ludovít Molnár, Peter Lech, B. J. Scheiner

This paper describes the results of a study of hydrometallurgical methods of producing sodium arsenate for the glass industry from arsenic oxide wastes occurring in carbon dioxide washing. This paper addresses the following aspects: theoretical assumptions for leaching arsenic and its oxides, experimental results of As(III) oxidation to As(V) in aqueous solutions, sodium arsenate crystallization (the system As2O5-Na2O-H2O), characteristics of the crystalline product, and pilot-plant tests using sodium arsenate in the glass industry.

Jan 1, 1993

By Patrick Ph. D. Kennedy, Osvaldo A. Ph. D. Bascur

With the revolutionary progress in information and computer technologies, applying the latest information technologies in metallurgical complexes has become a serious challenge to both a major opportunity and a serious challenge to both management and technical teams. The emerging component and object technologies are changing the way everyone can beneficially use their computer and networks to add to their corporate bottom lines. Most mining and metallurgical plants use predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis and oil and lube analysis for critical equipment. Process control strategies are installed in several metallurgical sites. All process equipment and control strategies require maintenance from local personnel at the mine. Integrated use of existing and emerging technologies is making it possible to implement an overall process effectiveness control index. This index is based on key indices such as losses due to plant availability, performance efficiency and rate of quality. The availability of real time and process history to identify the most critical part of the processing system from mechanical integrity is highlighted. An emerging plant integration paradigm is described to simplify the implementation of business enterprise resources management and distributed plant management systems.

Jan 1, 1998

By E. Ozberk, J. B. Hiskey, M. J. Collins, B. J. Scheiner, M. E. Chalkley, I. M. Masters

Conventional zinc concentrates generally contain 5 to 10% Fe, while bulk concentrates can contain up to 20% Fe. As a result, the disposal of iron bearing residues is an integral part of zinc refining operations. The quality of iron residues must comply with ever changing and increasingly stringent environmental legislation. Zinc has been recovered from sulphide concentrates by a hydrometallurgical route for almost one hundred years. The disposal of iron was a major difficulty for the industry for many decades and was directly responsible for low overall zinc recoveries. The introduction of the jarosite process in the mid 1960's allowed for the treatment of neutral leach residues and the precipitation of iron in an easily filterable form. Subsequently, three additional iron precipitation processes have found commercial application in the zinc industry: the goethite process; the paragoethite process; and the hematite process. The Sherritt Zinc Pressure Leach Process has been developed for integration with existing roast leach electrowin zinc plants, or as a stand alone facility for the treatment of a wide variety of zinc bearing feed materials. It is essential that these processes allow for the disposal of iron residues in an environmentally acceptable form. This paper describes the integration of the Sherritt Zinc Pressure Leach Process with commercially proven iron precipitation processes. The results of laboratory testwork and data from operating plants are presented.

Jan 1, 1993

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By Yi Yang, CHENGLONG XU, HAORAN LI, YALI FENG, JINRONG JU

Steel slag is an industrial byproduct of steelmaking that is mainly composed of calcium, iron, silicon and magnesium. In addition, depending on the different raw materials entering the furnace, steel slag contains a certain amount of vanadium that is the main source of vanadium production, accounting for 69 percent of the species of the total vanadium raw material [1]. From experience, the production of one ton of steel will generate 1.0 to 1.5 tons of steel slag [2]. However, the utilization efficiency of steel slag is less than 30 percent, and a large amount of steel slag is identified as waste and stacked in tailings. The random stacking of steel slag not only wastes large amounts of limited steel and land resources but also exerts pressure on the environment [3], making it imperative to research the effective utilization of steel slag and recycling of metal resources.

By Adrian E. Scheidegger

Recently, a new theory of the subsidence of rock masses has been advanced by Litwiniszyn and coworkers, which is based on the notion that the individual rock particles perform random walks. It is shown in the present paper that the final equations of the random walk theory can be justified from general principles of statistical mechanics in which no specific theoretical model of particle behavior has to be made. The theory appears to account appropriately for subsidence phenomena.

Jan 1, 1966

By David J. Dyet

Computer applications in the past five to seven years have become a typical and necessary practice in most modern geological offices. Manual calculations, interpretations and plotting of data can be, at times, quite tedious, inefficient and lacking in ac- curacy. The introduction of geostatistical and geological software can eliminate these problems. Computer applications in the uranium industry are not new; however, they are constantly being developed. A variety of soft- ware programs are available. Generally, these programs support most geological and geostatiscal applications in uranium mines. The Rabbit Lake Operation - Eagle Point mine in Northern Saskatchewan is a high grade mine, as one such case. Computer applications at the Eagle Point mine have been a mainstay in the geology department, since the mine's collaring in 1991. This paper presents a discussion on descriptions of programs, operations and applications of computers. It also explains and de- scribes the radiometric equipment used at Eagle Point. This pa- per will demonstrate how, by using computer systems, mine site information flows reliably with the involvement of computers.

Jan 1, 1996

By Ke Yang

In Chinese coal mines, extraction of deep, highly gassy soft coal seams sandwiched between soft floor and soft roof in complicated geology is commonly encountered. How to safely and efficiently excavate such seams is a very significant and important problem. It has been a focused research area in recent years. By combining the characteristics of fully mechanized longwall mining methods such as large cutting height and mining along the dip, an integrated method and technologies for the Zhangji Coal Mine were developed. This technology includes the design of a complicated geological exploration system, optimization of mining method and working face parameters, control of rock pressure and high levels of gas, reliability model of the production system, and selection and compatibility of equipment. Engineering practice shows that the integrated technology was successful in mining these complicated seams. This study not only enriches the mining method, but also improves the coal mining practice, especially ensuring both safety and productivity under complicated geological conditions.

Jan 1, 2009

By Richard R. Klimpel, Basil F. Fee

This paper summarizes the status of a series of new chemical reagents developed with the explicit goal of expanding the capabilities of existing froth flotation processes as well as allowing for new solid/solid separations to be undertaken that are not now feasible with flotation. The first portion of the paper briefly outlines the theory and motivation behind the development of each new reagent family. 'The second portion of the paper deals with specific laboratory examples of some separation systems studied to date.

Jan 1, 1993

By R. G. Swanton

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4-1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4-1/2H2O morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1991

By R. R. Klimpel

The efficiencies of plant-scale comminution processes are often evaluated by various indices calculated and/or measured somewhat independently of the performance of any associated downstream froth flotation processes. To compare specific comminution factors, such as energy utilization, media consumption and equipment utilization time, comparisons of comminution efficiency independent of flotation behavior are appropriate. However, as increasingly detailed plant-level information is gathered on the joint and highly interactive nature of comminution and froth flotation, it is becoming even more obvious that knowing and using simple efficiency indices are not enough. What is needed are more performance-related measures of the efficiencies of the combined size reduction froth flotation system for effective plant-level economic optimization to occur. The purpose of this paper is to present examples of some of the important interactions that influence the joint efficiencies of size reduction and froth flotation processes.

Jan 1, 1999

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 John A. Herbst, Per-Olaf Samskog, Jan Bjorkman, Yi Chang Lo

The study described here is concerned with the development of a model for the simulation and optimization of a rod milllpebble mill circuit. A series of laboratory tests was conducted to investigate the effect of critical operating variables. The pebble mill model structure used was a population balance type which accounta for impact breakage and fines production from pebble wear. Model parameterization and verification were performed using data obtained in batch tests and in a plant test campaign. The model developed was found to provide accurate predictions of plant-scale grinding. The prediction errors are less than 21 for the product size and 31 for the mill power required to achieve that product with a mill volume scale-up of 14,000 to 1. These results indicate that accurate extrapolations from laboratory batch data to plant scale performance are poaaible using the population balance model and scale-up prediction procedures for pebble mill circuits as well as ball mills. Preliminary indications are that the new model developed here will provide vital input for pebble mill optimization and process control as well as pebble mill design.

Jan 1, 1990

Crushing and grinding activity in 1989 followed the rapid pace of the mineral industry. Use of existing installations, demand for expanded capacity, and implementation of entirely new operations contributed to a high level of activity. At the 1989 SME-AIME Annual Meeting in Las Vegas, NV, the crushing and grinding session focused on wear materials in crushers and mills. Another session joined the process control group in its simulation-modeling and control of crushing and grinding circuits. Both sessions addressed the optimization in operating effectiveness. Specific subjects covered grinding media wear of forged and cast grinding balls and rubber lined mill liner wear. Also, the Semi Autogenous Grinding (SAG) Mill Conference in Vancouver in September 1989 provided a valuable update on the progress of SAG operations in recent years. Operationally, gold grinding and roasting circuits were implemented in 1989. Freeport McMoRan Gold started up two operations in Nevada. Two other circuits, both using SAG mills, are scheduled to start in 1990. These will be in Nevada and British Columbia. Elsewhere in gold, additional capacity continues to be brought onstream, both domestically and worldwide. In copper, expansions continue to call on additional crushing and grinding units. The unrest at Bougainville in Papua New Guinea has fueled a continued, strong demand for comminution in the copper sector. Specific equipment installed or started in 1989 included the ac variable frequency drive SAG mills in Australia, Alaska, and Papua New Guinea. Also, the gearless drive SAG mill in Chile provides tremendous flexibility in terms of mill speed. The trend toward moveable in-pit crushers continues -even at established operations.

Jan 1, 1990

By L. W. Stanger, Erich U. Petersen, William J. Tafuri, Donald M. Hausen, Douglas N. Halbe

Gold mineralization at the Mercur Mine was controlled primarily by structure and secondarily by lithology in Mississippian-age sedimentary rocks. Gold was localized where Sevier-age high angle northeast-striking faults are intersected by younger northwest-striking fault zones. The Lulu Graben is a northeast- striking fault zone composed of a south-dipping master fault coupled with subsidiary or antithetic faults. The Twist Fault zone, a sinuous, low-displacement , north-striking zone of fracturing, bisects the graben. Large- tonnage disseminated ore bodies formed east of the Twist Fault zone within silty, thin-bedded, bioclastic carbonates. West of the Twist Fault zone, gold was restricted to rock near peripheral faults surrounding a subvertical collapsed pipe developed within the graben. An overlying thick carbonaceous shale capped the ore zone. Presence of abundant limited- displacement faulting and of hydrothermal jasperoid is associated with cartonate-hosted disseminated gold. Conversely, increased fault displacement and widespread brecciation are associated with reduced dissemination of gold into normally receptive carbonates.

Jan 1, 1990