Search Documents

By Michael Fellows

Epidote is a common hydrothermal alteration product in many copper deposits of the southwestern United States. In many of these deposits epidote, along with calcite and chlorite, generally characterize a distal or halo propylitic alteration assemblage, but the mineral can occur within the central potassic alteration zone as well. Epidote is also a common alteration mineral in deposits formed in calcareous host rocks -- the skarn or pyrometasomatic ore bodies. Within the past 15 years, studies of the major and trace element composition of other alteration phases, principally biotite, associated with base metal ore deposits have demonstrated that some hydrothermal alteration minerals are compositional distinct from their igneous or metamorphic counterparts: However, the use of major and minor element content to identify and zero in on mineral¬ized areas does not appear to be very promising. Little work has been published upon the geochemistry of epidote from this standpoint and the results of my work suggest that a similar conclusion can be applied to epidote. My work (Fellows, 1976) suggests that epidote minerals in hydrothermal alteration suites from porphyry copper deposits in the southwestern United States are generally iron-rich rather than aluminum-rich. As a group, these alteration minerals differ compositionally from epidotes of regional metamorphic terrains. I ascribe these differences to the variations in the oxidation character of the respective environments. However, it appears as though the use of major element compositional variations of epidotes as an exploration tool is severely limited. Epidote is a complex calcium-aluminum silicate. Replacement of aluminum by ferric iron establishes a solid solution series between

Jan 1, 1977

By Michael J. Mankosa

Carpco has recently evaluated the use of various mineral processing techniques for secondary materials recovery. These applications include recycled foundry sands, plastics and secondary metals. This paper describes different recycling applications and the associated separation solutions. Results from extensive laboratory-and pilot-scale test work in each area are discussed. Industrial installations resulting from this test work will be presented. A detailed description of an industrial installation patented by Carpco for the recovery of plastic and metallics from current waste by-products is presented.

Jan 1, 1997

By D. E. Walsh

The behaviour of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effect of particle size, particle shape, pulp density, feed rate, and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that provided suitable precautions are taken, the technique is capable of providing valuable information that cannot be obtained by conventional studies, and could be used to better optimize spiral performance.

Jan 1, 1992

By R. M. Rowe, A. K. Bhasin, D. Malhotra

Introduction Most primary molybdenite producers use a selective flotation process in which molybdenite is floated from the ore while other sulfide and nonsulfide gangue minerals are depressed in the same step. The process was developed at the Climax mill. Reagents used in the rougher flotation stage include vapor oil (collector), syntex (surfactant), pine oil (frother), and occasionally sodium cyanide and Nokes reagent (depressant). Rougher concentrate is upgraded by cleaner flotation to produce market-grade molybdenite concentrates. Reagents used in the cleaner flotation stage are Dowfroth 250, vapor oil, sodium cyanide, and Nokes reagent. The development of the flotation reagent scheme at Climax and the role of the reagents have been well described by Born et al. (1976) and Malhotra et al. (1976, 1977a, 1977b, 1977c, 1980). The hydrocarbon collector, vapor oil, accounts for approximately 50% of the total molybdenite flotation reagent cost. Because vapor oil sources are limited, and the cost of vapor oil has increased significantly over the last decade, several studies have been done to evaluate alternate oil-based collectors and/or blends of collectors that would produce similar metallurgical results at a reduced cost, or increase the overall molybdenite recovery at the same cost (Smit and Bhasin, 1983; Hahn, 1969; Smith and Bhappu, 1971). The approach taken in the present study was to evaluate alternate nonoil-based collectors and collector systems that are less expensive than vapor oil. A series of potential nonoil-based collector classes were identified and evaluated in the laboratory against the current collector system. The metallurgical performance of these collector classes was related to their chemical structures. The results of this study are discussed. Collector classes A survey of sulfide mineral collectors was performed with the objective of identifying and selecting potential collectors for molybdenite flotation. The available reagents were categorized into 10 general classes. Table 1 summarizes these collector classes, their chemical formulas, the manufacturers, and selected commercial collectors in each class that were evaluated in the present study. Experimental procedure A Climax ore sample, assaying 0.3% MoS2, 2.2% FeS2, 0.007% Cu, 0.003% Pb, and 0.03 oz per ton Ag, was used for this study. Standard laboratory rougher flotation test procedure involved grinding a 2-kg ore charge in a rod mill at 60% solids. Reagents were added to the rod mill including a collector, syntex (0.005 kg/t), pine oil (0.03 kg/t), lime (to adjust pH to 8), and sodium silicate (0.15 kg/t). The ground pulp was transferred to a 1000-g cell, and flotation was performed at 35% solids and 1800 rpm using a Denver D-1 flotation machine. Concentrate was collected for a flotation time of six minutes. The general approach used in the present study was to substitute the nonoil-based collectors at two to three different dosage levels (0.01 to 0.15 kg/t) for vapor oil in the bench-scale, open-circuit rougher flotation tests

Jan 1, 1987

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 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 A J. Jonaitis

The DENVER Tube Press is a simple, high pressure (1500 PSI (100 bar» filtration unit, developed for processing difficult-to-dewater materials and to produce a handleable filter cake and clear filtrate product. Lab and pilot testwork conducted in Australia on coal fines (55-70\ -35 micron (400 mesh)) have shown that total moisture contents of less than 20\ are consistently achieved in the final cake products from the Tube Press. Currently, these coal super fines are sent to waste due to uneconomical mechanical dewatering methods, which were only able to reduce total moisture levels in excess of 30%. Calculated, throughput rates for the 500 Series Tube Press exceeded 1700 kg/hr (3750 lbs/hr). Feed solids concentration requirements are between 45 and 50\ to achieve these results.

Jan 1, 1993

By J. R. Muhm

Environmental due diligence investigations, also known as Phase I Environmental Audits, are increasingly important to major investors, venture partners, or prospective purchasers or sellers of mineral properties. Knowledge of environmental risks associated with a property will allow better appraisal of a property's overall desirability prior to completing the transaction. It is possible that the cost of environmental cleanup could exceed the value of the property. Topics appropriately investigated include permit status, water quality, past use of the property, hazardous materials management, storage tanks, public records pertaining to the environmental character of the property, and environmental costs.

Jan 1, 1991

By S. Rideout

The United States Department of the Interior's Office of Surface Mining (OSM) is responsible for regulating active coal mining and reclaiming abandoned coal mines in the United States. In working with the State government agencies that implement these programs, OSM is building a new approach that moves away from traditional "command and control" regulation and towards an approach that focuses on providing long-term environmental and economic sustainability on lands disturbed by coal mining. This initiative called "Reclaim the Future!" looks to enhance opportunities for economic development, wildlife preservation and enhancement, reforestation, and other beneficial and productive uses of lands disturbed by coal mining. The initiative is also focused on ensuring that the landowners and the local public have significant involvement in determining how best to reclaim mine sites and what post-mining land uses are most appropriate for each individual abandoned mine reclamation project or active mine reclamation. Through the use of the best scientific input in an open, participatory process, OSM hopes to further sustainable development principles for coal mining within the framework of existing United States law.

Jan 1, 2007

By W. Wan

Diesel particulate matter (DPM) emitted from diesel engines is currently considered to be a health problem in underground mines. As a result, attempts have been made to control DPM both by reducing emission rates and by managing the DPM that gets into the mine atmosphere. This paper presents a method for modeling the generation, transfer and distribution of DPM in the mining sections through the use of a convection-based computer model so that controls for emitted DPM can be evaluated. A variety of ventilation strategies and diesel deployment schemes for room-and-pillar development sections were simulated to compare their effects on average DPM concentrations at several fixed and mobile personnel locations in the section. Input data for the model was gathered from actual diesel development sections and derived from experimental study results provided by other researchers. Studied using the model were ventilation schemes using vent tubing and brattice, exhaust location strategies on the vehicles, and the direction of ventilation at the feeder-breaker location. A summary of results from this study will be presented.

Jan 1, 1994

By Wayne J. Nordstrom, Dennis L. Murr, James E. Wennen

National Steel Pellet Company (NSPC) conducted pilot scale testing and computer simulation studies which indicates that the capacity of the secondary grinding mill could be increased and that concentrate grade improvement could be expected with improved classification in the grinding circuit. Based on these studies, a decision was made to modify one secondary ball mill line at NSPC to include both cyclone and screen classification with magnetic separation applied to the circulating load. This paper will briefly discuss the studies leading to the decision to modify the circuit, the design of the modified circuit and the initial start-up and operating experience.

Jan 1, 1997

"Foreword by Lisa SchlinkSuperintendent, operations, Freeport-McMoRan Inc.,Green Valley, AZ, USAThe sixth annual Student Poster Contest hosted by the Mineral & Metallurgical Processing Division of the Society for Mining, Metallurgy & Exploration was held during the 2015 SME Annual Conference and Expo in Denver, CO. The contest had another record-breaking attendance of 31 entries: 27 graduate and four undergraduate. The universities represented were: Colorado School of Mines, South Dakota School of Mines and Technology, University of Kentucky, University of Utah, Southern Illinois University Carbondale, University of Wyoming and West Virginia University.The competition began with an extended abstract review by a panel of judges selected from MPD members. At the SME Annual Conference, all students displayed their posters, highlighting their research. The students with the top abstracts from the graduate and undergraduate divisions presented their research at the MPD Student Poster Session Wednesday morning. The panel of judges then provided tallied scores for the abstract, poster and presentation to determine the winners of the 2015 Student Poster Contest. The first- and second-place winners of both the graduate and undergraduate divisions received $1,000 and $500 scholarships, respectively. The third through seventh places received $200 each, and all other entrants received $100 each and were invited to join the MPD Luncheon.In the undergraduate division, Annette Hein of the University of Wyoming received first place for her research on “Solvent Extraction of Europium from a Nitric Acid Solution.” Second place went to Jennifer Galvin of South Dakota School of Mines and Technology for her research titled “Solvent Extraction of Neodymium Using PC88A.”In the graduate division, Caelen Anderson of the Colorado School of Mines received first place for his research titled “Fundamentals of Rare-earth Flotation Surface Chemistry: Hydroxamate Adsorption on Bastnasite”. This is Caelen’s fourth year placing in the top finisher. Second place in the graduate division went to Seyed Hassan Amini of West Virginia University for his research on “Ultra Clean Coal Production for the Solar-cell Industry.”The 2015 Student Poster Contest was chaired by Lisa Schlink (Freeport- McMoRan Inc.) and Emily Sarver (Virginia Polytechnic Institute and State University). The panel of judges included Aaron Noble (West Virginia University), Nick Gow (FLSmidth), Ren Bryce (Freeport-McMoRan Inc.), David Perkins (Derrick Corp.), Jim Metsa (Weir Minerals) and Scott Shuey (Newmont).A special thank you is extended to the sponsors of the MPD Student Poster Contest, to all the students who participated and to the panel of judges. Watch for more information on the 2016 MPD Student Poster Contest to be published later this year on http://www.smenet.org/mpd/ and in the November issue of Minerals & Metallurgical Processing."

Jan 1, 2015

By Thomas Schwind, Benedikt Grau, Angelos Gakis

"In Crossrail’s Farringdon station, compensation grouting was successfully utilized to mitigate the surface settlements induced by the tunneling works. The main focus of this study was the platform tunnels, which were approximately 300m long each and were enlarged to platform size using sequential excavation method (SEM) from the existing TBM running tunnels, initially supported using sprayed concrete linings. The rear grouting injections were carried out at a typical distance of minimum 5m above the completed, fully strengthened shotcrete lining hence inducing some additional stresses. In-tunnel monitoring using surveying targets was performed systematically to ensure that no excessive distortion of the initial shotcrete lining occurred. 3D finite element analyses were utilized to back calculate the actual “effective” pressure that was imposed on the completed shotcrete rings against the additional measured in-tunnel displacements due to the compensation grouting episodes. Additionally an assessment of the theoretical, “maximum” allowable grouting pressures that would lead to overstressing of the lining is presented. INTRODUCTION As part of the back analysis performed for the SEM tunnels in Farringdon station, an investigation of the effect of compensation grouting on the two constructed platform tunnels was undertaken. The platform tunnels were 10.6m high by 11.4m wide and approximately 300m long each. They were enlarged to their final shape from the existing TBM tunnels using SCL methods. This study utilized 2D and 3D finite element (FE) analyses in order to back calculate the observed tunnel crown displacement, assessing the equivalent grouting pressures during the rear injection episodes of the concurrent grouting operations. The results provide a useful reference for the order of magnitude of the grouting pressure load cases that can be applied in the numerical simulation of similar cases. Part of the results presented in this paper, were derived by the second author as part of his Master of Science thesis in Technical University of Graz."

Jan 1, 2016

By V. B. Achanti, A. W. Khair

Developing a laboratory procedure for the determination of coal-seam compressive strength has been a subject of discussion for many decades, and the reliability of laboratory determinations is often the subject of debate. A coal seam’s characteristics, the method of sample collection, the specimen preparation method and the testing procedure can often result in drastic variations in the test results. In this paper, the development of a laboratory testing procedure for the determination of coal-seam compressive strength is presented. Two samples that were collected from different coal seams were tested in this study. First, the inherent characteristics, i.e., coal structure. Hardgrove grindability index (HGI), Slake durability index, proximate analysis and mechanical properties (Young's modules and Poisson's ratio), of each coal were determined. The results were used to categorize the coal scams in terms of the characteristics liable to produce variable strength data in typical laboratory tests. Second, two commonly used laboratory specimen shapes, cylindrical and cubical, were tested to determine which shape produced the most reproducible strength values. Third, four loading rates within the static testing range, i.e., 0.007, 0.07, 0.34 and 0.7 MPa/s (1.0, 10, 50 and 100 psi/sec), were used to determine the ideal loading rate. Finally, the number of test samples required to produce strength data within the acceptable standard deviation, considering coal seam characteristics, were established. Background Laboratory testing of coal specimens for the determination of seam compressive strength has been a subject of discussion since the early 1900s. Many researchers have tested coal specimens to estimate coal-seam compressive strength for use in pillar design to insure the safe operation of [ ] mines (Unrug et al., 1986; and Hirt et al.. 1992). Yet, there is a lack of a universal procedure, and, no matter which approach is used, it becomes the subject of intensive debate. A great deal of work has been performed on the subject, and there is much information available in the literature. Some of this work concerns quantifying the influence of specimen shape and size on compressive strength (Bieniawski. 1968: Barron et al.. 1992: Khair and Xu 1994; and Khair 1994). As indicted in the literature, coal is a heterogeneous material, consisting of discontinuities such as cleats and bedding planes, which are likely to produce variable strength results (Holland, 1964; Unrug et al., 1986). Some of the prominent issues that influence the determination of coal-seam compressive strength in the laboratory are: •the collection of a representative sample from a coal seam; •the geometry, i.e., shape and size of the specimens to be prepared and tested: •the loading rate at which the specimens are to be tested:

Jan 1, 1997

By S. K. Singh

"Feather edging"-a major source of injury and fatal accidents in Australia, South Africa and USA, refers to a phenomenon where the roof, at the goaf edge, falls as a thin wafer of rock often suddenly, over-riding conventional timber breakerlines. It may run down and affect adversely a working bord at distances of 15 metres or more from the goaf edge. Feather edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a mine trial where a concentrated row of fully grouted bolts were able to resist the feather edging in the first comprehensive, monitored trial in an Australian pillar ('total') extraction coal mine.

Jan 1, 1999

By R. D. Schmidt

An in situ leaching geochemical simulator consisting of flow, mass transport, and graphics support programs has been developed. Two dimensional flow in heterogeneous porous media is modeled using a semi-analytic boundary integral technique. This method involves mapping streamlines to straight line segments in the complex potential plane. Leachant concentration and mineral values are modeled in this plane using the (one dimensional) potential coordinates. A fully implicit finite difference scheme is used to solve the resulting coupled system of four concentration equations. Graphical representations of streamline patterns, concentration histories, profiles and recovery curves are generated. An application of the model to uranium leaching in a heterogeneous aquifer and ore zone setting is presented.

Jan 1, 1985

By D. M. Larsen

Since start-up in 1985 the Cannon Mine has produced and shipped a 170 g Au/tonne (5 oz Au/ton) flotation concentrate to various smelters for gold and silver recovery. Several processed have been investigated to economically produce dore' at the mine site from the refractory concentrate. This paper describes recent laboratory and pilot scale test work utilized in the process design and engineering feasibility study of a 73 tonne/day (80 ton/day) pressure oxidation and CIL facility. The designed pressure oxidation circuit utilizes a series of vertical autoclave units operating at 170°C (338"F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1993

By V. B. Achanti

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the: fragmentation process were found to be: bit spacing, bit geometry, depth of cut, and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Three bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 90°. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Respirable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Jan 1, 1997

By James B. Loftis

The importance of increasing the world's mineral production to help solve our food and energy problems has been widely discussed. Improved surface mining methods will be needed to meet these needs. This paper reviews the modern horizontal drilling and blasting methods which can increase the productivity and lower the costs of I surface mining. A substantial decrease in the number of blast holes required, total footage of blast hole required and amount of explosive used has been realized by many mining companies using this method. Applications of this method are presently in large coal surface mines. However, similar gains are possible and probable in open pit mining of copper and iron.

Jan 1, 1975

By K. V. Raj, T. Bhowmick

"Computational fluid dynamics (CFD) modeling of an open-pit mine has several challenges. A good quality mesh of the model domain is a pre-requisite for convergence in solution. Good quality tetrahedral meshing and insertion of prism layers in faceted open-pit mine geometry is complicated due to presence of numerous vertices and ridges. Presence of vertices and ridges result in poor quality tetra elements and holes in prism layers, which cause instability in the model. Good quality pit bottom prism mesh elements significantly improve the formation of velocity boundary layer and thermal boundary layer at the pit bottom. This results in an expected temperature dependent micrometeorological buoyancy flow in the pit. Whereas, model geometry without a prism layer, results in abrupt temperature gradient near pit bottom. Buoyancy flow and recirculation have significant effect in lifting mechanism of fugitive dust particles generated near pit bottom. Representative initial and boundary conditions and selection of appropriate turbulence model have significant influences on the simulation results. In this paper, three-dimensional models of open-pit mines are developed using commercial CFD software (CRADLE-CFD). Important constraints and various consequences in modeling complex open-pit geometries are presented. INTRODUCTION Application of Computational fluid dynamics (CFD) to model an open-pit mine to predict fugitive dust and pollutant concentrations in and around a mine is relatively new. In former Soviet republic (USSR), Baklanov [1] and Belousov [2, 3] presented numerical models of pollutant transport in open-pit mines in Arctic regions. In recent years, advances in mathematical and computational fields have enabled better modeling of pollutant dispersion phenomenon around mines using computational fluid dynamics (CFD). Several CFD software packages have been used by various researchers to model the pollutant transport in open-pit mines. Works by Alvarez et al. [4]; Lowndes et al. [5]; Silvester et al. [6]; Torno et al. [7]; Choudhury and Bandopadhyay [8]; Collingwood et al. [9]; Raj et al. [10] and Flores et al. [11]; are examples of application of various commercial and open source CFD packages (COMSOL, ANSYS, OpenFOAM) to model pollutant transport in open-pit mines. These researches provided a strong background for additional research involving CFD modeling of open-pit mines. Due to the limitations of computational times and capacity, 3D modeling and various aspects of fugitive dust dispersion in open-pit mines remained unexplored."

Jan 1, 2015