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By L. H. Pye

For large mining sites in the west, the traditional method for performing an ecological risk assessment (ERA) provides little useful information for risk managers faced with selecting and designing sound remedial options. Current U.S. Environmental Protection Agency (EPA) risk assessment guidance largely supports quantitative risk characterization of individual species as surrogates for population and ecosystem-level effects. Developing a work plan for investigating and remediating ecosystem-level changes potentially caused by large-scale historic mining/smelting contaminant release requires a decision process that incorporates a more holistic ecosystem management approach. Some of the most wasteful efforts associated with mine site ecological risk assessments arise when the risk analysis and data collection programs are not specifically linked up-front to the risk manager's decision needs. The following paper discusses the importance of employing a decision-based, ecosystem management framework when conducting ecological risk assessments at large mining sites. A case study of an ecological risk assessment currently being performed at a large New Mexico copper mine site is presented.

Jan 1, 1999

By John S. Burton

Mineral policy in Canada has been in a state of transition and change over the past several years. 1976 has witnessed some settling of troubled waters and the pattern of the currents of change is becoming more clear. The provinces play a key role in this process and have provided much of the thrust for new initiatives. On the other hand, the federal government in Canada in recent years has taken a much more active interest in mineral affairs than previously and has asserted its powers on a number of key policy questions. Some of the initiatives from the two levels of government in Canada have come into conflict with each other and, thus, contributed materially to a state of affairs that includes change, uncertainty and conflict.

Jan 1, 1976

By T. A. McAfoose

As one of the major suppliers of the chestnut Ridge energy center, Rochester and Pittsburgh Coal Company continues the search for more efficient haulage systems. This search is one that is essential in providing coal to the Keystone and Homer City power plants at the most economical cost. These two electrical generating plants located in west central Pennsylvania are part of the energy center which consists of four generating stations. Prior to the time the two stations were put on line, August, 1967 for Keystone and August, 1969 for Homer City, our company made the decision to rely on belt conveyors from the section to the surface to provide for continuous main line haulage. The proximity of these generating stations to proven reserves allow for minimal truck haulage and minemouth setups. With the addition of seven new mines, in the past ten years, revisions have been made on the original setup to interconnect the haulage of several mines to deliver the product by belt to the power plants.

Jan 1, 1979

Lack of selectivity in mixed mineral flocculation can be attributed to one or more of the following factors: dissolved ion interference, heterocoagulation, mechanical entrapment in flocs and entrainment of fines between flocs. In a study of apatite- dolomite system, it was determined that dissolved ions do not have a significant effect on selectivity. Heterocoagulation was minimized by choosing proper process conditions and addition of a dispersant. Mechanical entrapment was proved to be insignificant and efforts were made to reduce entrainment by choosing an appropriate method of separation of flocs from fines. A new factor termed "polymer induced entrapment" which occurs due to limited affinity of the polymer to the mineral which is not flocculated is postulated to be the cause for the loss of selectivity.

Jan 1, 1986

By J. R. Johanson

In recent years the procedures for functionally designing bulk storage bins and hoppers have evolved from qualitative guess and try methods to a quantative method based on theory and tests of the bulk solid to be stored. This quantative method, developed and implemented by Dr.'s A. W. Jenike and J. R. Johanson as with any new design, must prove its effectiveness and validity in the actual operation of the finished equipment. How accurate are the theoretical predictions? Is it possible to extrapolate from bench size tests on a small ample of the bulk solid to the full scale bin design? Can the theoretical designs be economically translated into working hardware? In this paper the answers to these questions are discussed in light of actual bin operations.

Jan 1, 1968

By S. Peng, Yi Luo

Subsurface strata movements and deformations associated with underground longwall mining activities could cause certain influences to subsurface structures and water bodies. Methods have been developed for the prediction of final and dynamic subsurface movements and deformations induced by underground longwall mining operations in the eastern coal fields. Two new types of strata deformation, vertical and total strains, which could be useful in the field of subsidence research in assessing subsidence influences to the subsurface structures and water bodies, have been introduced. Using the subsurface subsidence prediction model, three types of subsidence influences to surface and subsurface hydrological systems have been identified. Attempts have been made to quantify the two types of subsidence influences that could cause water loss and could lower water levels in aquifers.

Jan 1, 2010

By James M. Williams, Michael E. Zellars, Arthur J. Roth

INTRODUCTION Our present estimates of world P205 consumption for all uses show an average annual growth rate of approximately 1.9% per year. The estimated 1985 consumption of 41.5 million tonnes of P205 is predicted to increase to 57.1 million tonnes of P205 by the year 2005, which represents a growth from 157.7 million tonnes in 1985 to 217 million tonnes of phosphate rock in 2005. The present situation of oversupply and extremely weak phosphate product prices is, however, expected to continue in the short term and a normal supply/demand balance may not be achieved until after 1990. The growth in P205 demand, in conjunction with the higher cost of replacing low cost mines as they are depleted, will place economic pressure on world farm economies through the increased cost of phosphate fertilizers. The availability of rock supply is not the challenge; rather, it is the economics of new rock supply. This economic challenge of providing new rock supply is by no means limited to the United States. Even in centrally controlled economies, the cost of rock from domestic mines of marginal quality and economic viability, coupled with burdensome infra¬structure requirements, may result in tonnage additions at very high cost. Although government subsidies to offset higher production cost is a factor in some countries, world production in the next 20 years will be directed, if not governed, by economic factors. Established infrastructure, good quality reserves, and existing operations will provide a competitive advantage for new prod¬uction. It is our opinion that the current world supply structure will remain relatively stable through 2005, in that most of the traditional suppliers will retain supply roles. U.S. rock production, although it is not expected to grow beyond the present level, will still be a major contributor to world supply. Although dramatic changes within mining, fertilizer production and farm economics may appear disruptive, the current supply scenario will, in general, continue with the major issue being production economics. WORLD DEMAND Demand for P205 by region in the world has been estimated using projections of population, crops and yield, arable land, economic and other data as a basis for future demand projec¬tions by Blue-Johnson and Associates, our col¬laborators on a recent multi-client study. Non-fertilizer P205 demands were estimated in the same general manner. These estimates of future demand are based on an assumption of reasonable world political and economic stabil¬ity, debt repayment requirements maintained at workable levels, and resolution of problems in the agricultural economy to a point where normal supply/demand forces can interact freely to provide a basis for continued P205 supply. The results of these studies indicated an average growth rate of 1.9% per year through the year 2005. This growth could be as low as 1.5% per year, or as high as 2.5% per year. It is our opinion that the estimated rate of 1.9% per year is most probable. This moderate growth rate considers both the major economic constraints facing the world agricultural industry today and the general problem of affordability of fertilizers and other crop inputs. WORLD SUPPLY There are adequately defined world reserves of phosphate rock today to provide supply well into the future, even at much higher levels of demand than presently projected. Using the U.S. Bureau of Mines estimates, which are based on stringent criteria for definition of reserves, the present world reserves base is approximately 35 billion tonnes. Identified resources raise the potential for production by orders of magnitude. Potential resources based on geological trends, and including offshore deposits, would again result in orders of magnitude increases in rock resources. Morocco leads the world in reserves base with approxi¬mately 21 billion tonnes. The U.S. is second, followed by the Republic of South Africa and Russia. These four countries control about 87%

Jan 1, 1986

By T. Weimer

Gasification of carbonaceous energy carriers with simultaneousCO2 removal is a new and interesting alternative e.g. ZECA [1],HyPr-Ring [2], AER [3]. In the ZECA process lime supported Hydrogen generation from Methane is a basic process unit and the Hypr-RING process investigates Hydrogen generation from hard coal with addition of lime. Here the main objective is a further development of the AER process. High energetic efficiencies for gasification in the range of 90 % can be achieved if the humidity of the energy carrier is already sufficient for steam reforming reaction. The aim of the overall process is upgrading coals and biomass yielding into three valuable products: • A fuel gas ready for power generation • A CO2gas stream containing >95%, ready for transportation to disposal or chemical fixation • A pre-calcined feed for cement clinkering consisting ofCaO and coal ash Thus power generation and gasification are independent. A promising industrial application is the combination of gasification and cement production. Then only one additional reactor is required and the precalcination mass flows have to be increased.

Jan 1, 2004

By Anthony G. Fonseca, W. W. Wen

About 45-50% of the coal mined in the U.S. passes through coal preparation plants; east of the Mississippi River this number increases to about 75-80%. Although the cost for coal preparation is worthwhile to some, the coal industry faces the challenges of continuing downward pressure on the price of coal and the impact of new environmental regulations. Coal preparation, as commercially practiced today, is an effective process achieving 75-803 ash reduction, 15-8m trace element reduction, and 85-90% Btu recovery; it is less effective for pyrite reduction (35-70%), and on-line operating time (40-60%), and suffers from obsolete control systems. Methods will be discussed for reducing costs of coal preparation and improving the performance of coal preparation plants. Comments are included on equipment selection, especially for -28 mesh coal, and prep plant operation and control practices. Btu recovery, ash and pyrite reduction, fines processing including dewatering and slurry fuel use options are emphasized. Trace element removal and expert control systems for maximization of prep plant operation also will be highlighted.

Jan 1, 1995

By J. Partyka

Adequate ventilation is a main concern if Lockerby Mine near Sudbury is to be expended. This study investigate a two-fold problem: (1) the new pressure and volume requirements of the main fans due to the theoretical. deepening of the mine, and (2) the effect of the natural ventilation pressure on the main fans. Field data was analyzed with the aid of a newly developed network simulation program, VNETPC Version 3. 0. The density change throughout the mine is accounted for by performing all computations at reference density. Results of the investigation indicate that the existing fan system must be supported by three to five additional underground fans as well, the density effect is significant. If neglected, it will greatly alter the simulation results

Jan 1, 1991

By S. B. Gaidhani, V. A. Mandlekar, R. L. Sonolikar

Column flotation technique is applied for the depression of the magnetic material by the application of an axial magnetic field from chalcopyrite ore. It is observed that an increase in the intensity of magnetic field from 0 to 316.8 oersteds decreased the magnetic content in the froth from 25 to 2 %. . This might be due to retention of magnetic material in the magnetizable zone and the diffusion of nonmagnetics through it. The effect of air velocity increased the magnetic content in the froth and total froth content also. At low gas velocity the tiny bubbles are formed whereas at high gas velocity these coalesce into big bubbles and slugs formed breaks the magnetizable zone. This study opens a new field called 'Magneto-flotation'.

Jan 1, 1988

By M. Z. Dogan, M. S. Celik, G. Onal, O. Ozcan, I. Yildirim

A fluorite ore (51.85 % CaF2) containing high contents of calcite, quartz and iron oxides was upgraded by flotation using a new reagent, oleoyl sarcosine (OS). In addition, quebracho and sodium silicate were used as depressants for calcite and quartz, respectively. The effect of pH, collector and depressants concentrations on grade and recovery was determined with the aim of optimizing the flotation conditions. Application of the two-stage cleaning achieved a concentrate assaying 92.17 % CaF2 with 80.1 % recovery. The Si02 content (0.76 %) was below the required level of 1 % SiO2. The mechanism of interaction between OS and fluorite, as compared to oleic acid, is also elucidated based on the zeta potential measurements.

Jan 1, 1993

By R. Corriveaau

This paper is about a horizontally curved conveyor, which carries 6,050 stph of limestone over land from a new quarry to the owner's plant. The conveyor is 5,012 ft long with a horizontal curve radius of5,OOOft Site conditions made a curved conveyor design the most optimal and economic solution. Using our unique custom conveyor calculation program, TKRI was able to accurately model and design the conveyor to properly track the belt and prevent any spillage through the horizontal curve radius. A data monitoring system was installed that allows monitoring of the conveyor both locally and remotely. The remote monitoring allows TKRI to contact the owner for preventive maintenance. Preventive maintenance can reduce the conveyor downtime during normal operating hours.

Jan 1, 2004

By B. D. Shah, H. S. Soto

Lack of selectivity in mixed mineral flocculation can be attributed to one or more of the following factors: dissolved ion interference, hetero- coagulation, mechanical entrapment in flocs, and entrainment of fines between flocs. In a study of the apatite-dolomite system, it was determined that dissolved ions do not have a significant effect on selectivity. Heterocoagulation was minimized by choosing proper process conditions and addition of a dispersant. Mechanical entrapment was proved to be insignificant and efforts were made to reduce entrainment by choosing an appropriate method of separation of flocs from fines. A new factor termed "polymer induced entrapment," which occurs due to limited affinity of the polymer to the mineral that is not flocculated, is postulated to be the cause for the loss of selectivity.

Jan 1, 1988

By Steven W. Hunt, Gregory C. Baker, Glen J. Rorison

Microtunneling methods were utilized beneath pile-supported clarifier basins to replace settlement damaged sludge drain lines at the Jones Island Wastewater Treatment Plant in Milwaukee, Wisconsin. To minimize the risk of blockage and expensive recovery of a microtunnel boring machine against pipe piles or construction debris, a Soltau RVS 80 was utilized. This machine allowed the alignment to be initially bored with guided 114-mm diameter rods to ensure proper alignment and lack of obstructions. Casing pipe was then installed by jacking 1-m long, 305-mm diameterclay pipe along the rods and behind an auger head. This case history also discusses how 2.4-m diameter precast concrete pipe was used as a one-pass sinking caisson for workshafts and new cleanout manholes.

Jan 1, 2001

By A. K. Ghose

The increasing application of roadheading machines in the coal industry has prompted the development of an appropriate selection methodology for such machine applications in specific locales. Accurate geological sections and comprehensive rock testing are required for all machine tunneling. Using suitable geotechnical parameters and index tests, sensitive both to excavability and standability of the strata, a classification scheme has evolved to help evaluate the rock mass vis-a-vis application of a given weight-class of roadheading machine. The classification parameters include point load index, brittleness, abrasiveness, average crack density, and ground water, which with assigned numerical ratings, lead to a quantitative global rating of the rock mass. For each rock mass class, the selection of an appropriate roadheading machine is recommended. The paper illustrates the application of the rock mass rating system and also describes simple index tests for evaluating the classification parameters for brittleness and abrasiveness. Manuscript not received in time for publication.

Jan 1, 1983

By S. P. Liebenberg

During the past fifteen years significant progress has been made on carbon-in-pulp (CIP) technology for the extraction of gold. While most research on the mechanisms and kinetics of CIP sub-processes has focused on the adsorption step only, auxiliary unit operations such as elution have received less attention. The mathematical models which have been developed for elution at the University of Stellenbosch can be used for design as well as process optimisation by incorporation into an overall CIP simulation program. Except for these models, no other comprehensive models for the complex elution process are available. It is the aim of this paper to review recent modelling work on competitive elution from activated carbon.

Jan 1, 1995

By C. H. Bucknam

An interlaboratory testing program was undertaken in support of an ASTM standardization program for simultaneous combustion-infrared analysis for carbon and sulfur in ores and related materials. Statistical analysis results from the study are used to generate the within-laboratory and between-laboratory precision data needed for standardization of the methods. The interlaboratory precision statistics are also interpreted to estimate the uncertainty in calculation of net carbonate value classifications using a simplified quantitative risk analysis technique.

Jan 1, 1998

By Homer S. Anderson

To clarify what r mean about this long title, I would like to define the term technology. A standard definition of the word "technology" is "a technical method of achieving a practical purpose". Incidently, another definition of the term is merely "technical language". The same dictionary defines the word "technology" as "having a special, usually practical, knowledge of mechanical or scientific subject." Naturally, the practical purpose of the subject with which we are concerned is solving of problems we encounter in the mining industry. I might further describe the subject of this discourse by defining the term "manager". An old definition, "one who dispenses the duties of his position with care and economy." In line with the above definition most of the technology with which we in the mining industry are confronted with deals with some form of cost reduction. This may be related to the speed of doing an operation or to saving of labor or supply costs. These can be improvements of an existing method or the result of new processes or inventions, such as new machinery.

Jan 1, 1974

By Richard Hogg, Erol Kaya, Jan M. Mutmansky

Characterization of the size, shape, chemical composition, and mineralogical content of mine airborne dusts generally requires a larger mass of dust particles than is typically collected using traditional sampling devices. In this paper, the general design of a passive dust collector is described and the field results are presented. The collector was constructed of galvanized sheet metal duct with a resin-coated honeycomb to provide an elutriation-type system for particle collection. Several versions of the collector were used in the field portions of the research. The dust samples collected from underground coal mines were found to possess angular particle shapes, relatively consistent size distributions, and elemental compositions that showed relatively little variation, at least for the more prevalent elements. In addition, the distributions of particles sizes obtained from the passive dust collector appear to be similar to those of samples collected at the same time in a conventional personal sampler except that the passive device seems to collect a larger quantity of coarse, non- respirable particles. Conclusions on the suitability of this dust collector for collecting characterization samples are presented. In addition, the potential for using such a dust collection system for supplying dusts for biomedical research is discussed.

Jan 1, 1993