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By S. M. S. Azghdi, K. Barani

The effect of microwave treatment on the surface roughness and wettability of chalcopyrite (CuFeS2 ) and on the chemical composition of its surface was studied. The microwave source was a conventional multimodal oven with frequency of 2.45 GHz and maximum power of 900 W. Pure chalcopyrite specimens and purified chalcopyrite concentrate were used in this study. Analysis using atomic force microscopy showed a decrease in the surface roughness of the chalcopyrite after microwave radiation. This decrease may be due to oxidation of the surface and formation of iron oxide. Moreover, the surface wettability of the chalcopyrite mineral increased with increasing duration of microwave radiation, which was in good agreement with the micro-flotation mass recovery results. The increased wettability of the surface may be attributed to the decreased surface roughness by microwave radiation. Analysis using scanning electron microscope/energy-dispersive X-ray spectroscopy indicate that after microwave radiation, the contents of sulfur and iron increased whereas that of copper decreased on the surface of the chalcopyrite, significantly changing the average atomic number of the chalcopyrite surface.

By E. J. Owen, A. Appah, I. C. Sanchez, K. T. Stafford, N. Hurtig, R. Otoo, N. A. Iverson, S. A. Moses, V. T. McLemore

New Mexico lies at the eastern edge of one of the world’s great metal-bearing provinces hosting numerous Laramide and Paleogene mineral deposits. Southwestern New Mexico contains Laramide porphyry Cu (±Mo, Au) and Paleogene Mo-W deposits. Porphyry deposits are generally large, low-grade deposits containing Cu, Fe, Mo, Au sulfides (and other metal sulfides) associated with porphyritic intrusions and exhibit characteristic alteration styles. Porphyry deposits can also be spatially and temporally associated with skarn deposits and polymetallic veins. All of these deposits have the potential to host various critical minerals, including Cu, Zn, Bi, Co, Ni, rare earth elements (REE), Te, and W. Critical minerals may be found as substitutions within ore minerals or as separate mineral phases. These deposits are constrained using 40Ar/39Ar dating into three ore-producing magmatic pulses: 1) ~78–71 Ma Laramide pulse, 2) ~59–50 Ma, Laramide pulse, and 3) ~40–30 Ma Paleogene pulse. New and historic whole-rock geochemical data have highlighted areas with critical minerals potential that require further study.

Feb 1, 2025

By Robert G. Woolery

Union Carbide_ began looking seriously at heap leaching in 1971. At that time some 1.6 million tons of mineral averaging 0.040% U308 were stockpiled at various sites around the Gas Hills, Wyoming, uranium facility. Several alternatives for economically exploiting these reserves were considered and heap leaching seemed the most attractive. At the time, Western Nuclear Inc. was operating a heap leach project nearby in which the low-grade ore was leached with sulfuric acid, the product liquor treated in an on-site solvent extraction circuit, and the stripped product liquor re-acidified and recycled. They were most generous in allowing us to visit their site, answering our questions, and were helpful in discussing the problems associated with heap leaching. They confirmed our belief that, it was possible to operate a heap leach profitably on material too low grade for. conventional milling. Based largely on what we had learned from Western Nuclear's experience, a program was set up involving a laboratory study to determine the characteristics of the mineral stockpiles as related to heap leaching and to conduct a pilot heap leach adjoining our Gas Hills mill. Basically, the pilot heap construction and leach procedure were similar to those described in the literature(1,2) with certain modifications to permit detailed monitoring of the operation. In May, '1972, the decision was made to construct a test heap. The UCC plant at Gas Hills, Wyoming was selected as the most appropriate site for the follow¬ing reasons:

Jan 1, 1977

By F. Segobia, M. Portal, F. Ysla, L. Goicochea

It is our responsibility to promote responsible and sustainable mining with new generations, promoting a culture of equality and respect. To fulfill this commitment, we are working with the SME UNC Student Chapter team, Newmont Yanacocha, BRG Women and Allies and the Museo de Agua y Tierra (MAT) to carry out the “Building our future” project. It is our responsibility to promote responsible and sustainable mining with new generations, promoting a culture of equality and respect. To fulfill this commitment, we are working with the UNC SME Student Chapter team, Newmont Yanacocha, BRG Women and Allies and the Museo de Agua y Tierra (MAT) to carry out the “Building our future” project. This project seeks to instill in new generations the importance of mining, integrating sustainable development objectives. We have the participation of Newmont Yanacocha and external professionals, who share their life stories and inspire participants from rural and urban educational institutions to pursue their dreams and aspirations. We believe that this project is important because it will help new generations understand the importance of mining and its role in the development of the country, covering the economic, environmental and social spheres. Since its inception in 2022, the project has positively impacted more than 500 participants.

Feb 1, 2024

By Matthew T. Mowry

As the mining industry continues to hire young professionals to supplant the growing number of retirees, a well-developed engineering curriculum, coupled with practical, real-world training, can prepare mining engineering graduates to make meaningful contributions in the industry. Successful companies can be measured not only by their reserve base and annual production but also by their retention of mining engineering graduates with zero to five years of operational experience. My personal experience in the industry during the last five years has been varied and rewarding. The knowledge and experience I have gained have taught me valuable lessons that prepared me for my current role.

Nov 1, 2013

By Matthew Grzelak, Gulsah Erinc, David R. Chapman

"The third phase of the Bagram Drainage System project at Bagram Air Force Base in Afghanistan included construction of a shallow, 540-m long, 1.8-m inside diameter drainage tunnel. The tunnel penetrated mostly stiff to hard clayey and silty soils. The contractor’s Value Engineering Change Proposal (VECP) to use pipe-jacking with a microtunnel boring machine (MTBM) instead of the specified two-pass Earth Pressure Balance method was evaluated and supported using hand calculations. Contractor support was provided throughout the project by providing design reviews and instrumentation monitoring during construction. This paper compares the value-engineering proposal to the specified method and describes the construction conditions encountered. INTRODUCTION As part of a larger improvement project at the Bagram Air Force Base in Afghanistan, a shallow, 540-m long, 1.8-m inside diameter drainage tunnel was constructed to provide additional capacity for Coyote Creek to pass below several critical structures, including taxiways and the main runway, for mitigation of recurring flooding (see Figures 1 and 2). Overburden over the tunnel crown ranged from about 3 m to 5.5 m. An existing cast-in-place twin barrel concrete culvert runs approximately parallel to the new tunnel and is within about 8 m at its closest point. The contractor’s Value Engineering Change Proposal (VECP) to the specified two-pass Earth Pressure Balance (EPB) method (steel ribs and lagging or steel liner plate with a carrier pipe later grouted in-place) called for installation of the required drainage pipe by pipe-jacking (one-pass installation) using a slurry microtunnel boring machine (MTBM). The critical nature of the operations at the air base resulted in significant construction coordination challenges and a greater than usual need to avoid excessive settlements. Substantial restrictions were placed on drilling of investigative borings and installing instrumentation near runways and taxiways due to drill mast height. The prime contractor was SERKA TAAHHUT INSAAT A. S. (SERKA), the microtunneling subcontractor was Ludwig Pfeiffer Microtunnel GmbH & Co.KG (Pfeiffer), the jacking pipe designer was Gollwitzer Pipe and Shaft Technology GmbH (Gollwitzer), and the contractor’s tunnel engineer was Lachel & Associates, Inc. (Lachel). Lachel provided contractor support throughout the project including preparation of a VECP/Design Summary (including interpretation of existing and new geotechnical information), design reviews for jacking pipe, estimating settlement of an existing drainage structure above the new tunnel, and instrumentation planning, monitoring, and analysis during construction."

Jan 1, 2016

By Zygmunt Sadowski

Problems encountered in barite flotation from various waste materials such as spent drilling muds are likely to be closely connected with the effect of chemical additives and metal ions present either added or present as contaminants, on the flotation. Fuerstenau and Palmer (1976) have studied in detail the adsorption of multivalent cations onto oxide and silicate minerals. It was observed that the adsorption of a multivalent metal species exhibits a sharp pH dependence which is related to the formation of hydroxy complexes of the metal ions in solution. Investigations on the recovery of barite from tailings ponds and mining wastes (Sullivan and Lamot, 1981) have shown that such barite materials can contain large quantities of carbonate and silicate minerals (including clay minerals). Also iron oxide slimes can be present. From these substances cations such as Ca2+, Mg2+, Fe2+ and A13+ can potentially dissolve and be present in the aqueous phase accompanying the various minerals. These ions and their hydrolysis products can have a substantial effect on any subsequent flotation scheme. The present study investigates the effect of the noted ions on both the stability and electrokinetic behavior of barite suspensions.

Jan 1, 1986

By Alexander Sutulov

It is calculated that since the beginning of last century, which practically coincides with the beginning of the Industrial Revolution, our civilization has consumed around 239.5 million tons of copper (see: Table 1). According to the most pessimistic projections of today, with only a 2.5% annual growth rate in demand, we are bound until the end of this century to consume another 200 million tons of copper in remaining 17 years. A recent study made by US Bureau of Mines (1) indicates that the proven ore reserves of 150 major operating mines and about 120 deposits sufficiently explored for development and feasibility studies accumulate a total mass of 49.3 billion tons of ore, assaying an average of 0.82% Cu and containing around 324 million tons of recoverable copper. Consequently, there is a high grade of probability that the bulk of our future ore supplies, for our demand of, say, next 25 years will cane precisely from these mines. The interesting point in USBM study is that it indicates the recoverable byproduct content of these ores and which is: 118.2 million troy ounces of gold 2277.4 million troy ounces of silver 7.1 million tons of lead 24.7 million tons of zinc 1.3 million tons of nickel 3.1 million tons of molybdenum 765 thousand tons of cobalt, and 720 thousand troy ounces of platinum. This information gives us a relatively reliable profile of our future ores for next 25 years, and thus makes possible evaluation of byproduct credits in our future copper mining and producing activities.

Jan 1, 1983

By E. C. Roper

Landusky Mining, Inc. and Zortman Mining, Inc. are two registered Montana Corporations wholly owned by Pegasus Gold, Ltd. of Vancouver, B.C. The Zortman and Landusky Mines are located in the Little Rockies District of central Montana. The Zortman-Landusky mines produced 2,100 kg gold in 1982. A total of 3,250,000 t of ore per year are mined during the period March 1, to September 15, at an average grade of 1.04 gm/t (0.03 oz/t) gold and 13.4 gm/t (0.385 oz/t) silver at a cutoff grade of 0.35 grams of gold/ton (0.01 oz of Au/t) of ore. The stripping ratio during 1983 is anticipated to be 0.75/1 waste to ore. Combined average plant capacity of the two Merrill-Crowe plants is 9,840 lpm (2,600 gpm). The combined heap spray capacity of the two plants approaches 18,900 lpm (5,000 gpm). The mine employs approximately 200 people, about half of these work for the mining companies and the other half for the mining contractor, N. A. Degerstrom of Spokane, Washington. Net profit in 1982 for Zortman and Landusky Mining, Inc. approximated $4,900,000 at an average gold price of $11.40/gm.

Jan 1, 1983

By John Duff Erickson

Determination of the final pit limits of an open pit copper mine is a problem that has far reaching effects on the life, profitability and operation of a mine. The solution to this problem requires that all of the significant variables affecting the final pit limits be considered together with corporate objectives as the guiding principle. This paper discusses the use of these variables and how they should be applied to plan the future of a mine. The objectives of a final pit plan; are determination of the extent and location of ore reserves, the allowable stripping to be accomplished to uncover the ore, the final pit surface intercept, final pit topography and the contained metal values in both ore and waste. The objectives of the plan must be consistent with corporate objectives as they pertain to profit, future investment in the mine, return on investment, alternative investments, conservation and perpetuation of the corporate entity. The subject will be treated in three parts: economic considerations, effect of leaching and pit design technique. At the outset, it is assumed; that the extent of and metal values in the mineralized area to be considered have been reasonably defined by development drilling and sampling.

Jan 1, 1968

By Michael Schultz, Gregory Sanders

The City of New Haven is planning to construct the Downtown Storm Sewer Infrastructure Improvement project to mitigate on-going stormwater flooding in the Long Wharf District. The proposed project includes a 685 cubic feet per second (cfs) stormwater pump station and a 3,200 linear feet (975 meter) long tunnel segment with an internal diameter of 120-inches (3.05 meters). This paper presents the aspects of the final design and the use of the cloud-based data management software to make better data-informed decisions. The software was used to create a spatially aware database of the subsurface conditions, as well as improve visualization and analysis of the soil properties.

Dec 1, 2022

By William F. Hahn

It is a pleasure to speak to this group about special crusher installations which are in the bauxite and phosphate rock processing industries. The installations to be discussed demonstrate the variety of conditions, materials, and results desired which must be evaluated before a selection is made from the specialized crusher technology available today. Those of you who are closely involved with phosphate rock and phosphate products processing will find some of this information a bit interesting and perhaps alien to your own descriptions or every day references. It is given from a "crusher" manufacturer's viewpoint and therefore is infused With our flair and language. General features of six (6) different crushers will be shown in cross-section With slides and will be discussed in the same order.

Jan 1, 1978

By L. M. Turner

Perlite is a unique mineral that upon heating expands to about twenty times its original volume. Mining is by open pit method. The processing cycle involves crushing, screening and sizing the ore. An on-site quality control facility at the Manville Products No Agua mine exerts a high degree of control over every phase of the operation from blasting to finished product.

Jan 1, 1985

By R. E. Greuer

The design of mine fire emergency plans requires that the contamination of mines by fumes, and the mutual interaction of fires and ventilation systems be pre-calculated. Several computer models were developed by the Bureau of Mines for this purpose during the last decade. The models advanced in sophistication from the transient-state simulation of fume concentrations for the early stages of a fire to the steady-state simulation of airflow rates, concentrations, and temperatures for fully developed fires, and finally to the complete transient-state simulation of fires and ventilation systems. The principal features of these models are described.

Jan 1, 1989

By D. D. Young

During the 1970's a number of covered storage facilities were constructed in North America to store and handle large quantities of bulk, solid materials. This trend, away from outdoor storage piles, will probably continue at a stronger pace in the 1980's. This paper attempts to answer some of the questions often raised about the economics of large covered storage facilities. The paper is in four parts: 1. Why Build a Storage Facility? 2. 2. Common Components of Storage Systems With Details of Six Storage Facilities 3. Results of a Study for 50,000 Mg Clinker Storage 4. Guidelines for Conducting a Study to Select a Storage System.

Jan 1, 1980

By M. Rossi

The use of service variables in geostatistics (grade-thickness) is common in industry when developing block grade models and geologic resource estimates. This is particularly true in the case of sedimentary and strata-bound-type deposits. The approach has proven merits when assessing ore reserves. However, there are cases where its application for preliminary data analysis produces biased estimates. One such case is encountered in uranium disequilibrium studies. This paper demonstrates the inadequacy of service variables when performing uranium disequilibrium studies. Disequilibrium analysis is a necessary pre-processing step when radiation counts are used as raw data to calculate uranium reserves. Typically, a probe is used to obtain the gamma counts from open drill holes. These counts are then regressed (and corrected) against chemical assays obtained from core samples. During this process, the grade-thickness variable produces an optimistic image of the relationship between probe grades and chemical (true) grades, causing overestimation of the final geologic resource. The problem is analyzed through a case study.

Jan 1, 1991

By J. W. Rold

In 1973 housing and construction conflicts threatened Front Range gravel resources. The legislature addressed the problem by passing HB 1529, which required the Colorado Geological Survey to map the deposits and forbid local governments to change lands over commercial mineral deposits from zones allowing mineral development to zoning which conflicted with development. It charged counties to develop Master Plans for Extraction. Plans must consider resource quality, multiple-sequential-use potential, surrounding area compatibility, neighbors, quality of Life, extraction maximization and reclamation potential. Imprecisely worded statutes, budgetary constraints, lack of enforcement and political pressures have limited benefits from the law.

Jan 1, 1987

The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted a study to determine the effectiveness of a filtered air delivery system to reduce respirable dust exposure of roof bolter operators in underground coal mines. When performing roof bolting operations, roof bolter operators may experience exposure to high levels of respirable dust during a working shift, especially when working downwind of the continuous mining machine. While drilling and installing roof bolts, this filtered air system supplies a clean curtain of air over the roof bolter operator by means of a plenum mounted beneath the canopy. This experimentally designed air curtain, adapted for roof bolting machines used in this study, is based upon previous design prototypes, computational fluid dynamics (CFD) simulations and trial-and-error testing. Both the prototype and final designs were tested in the full-scale mining galleries at the Office of Mine Safety and Health Research (OMSHR) in Pittsburgh, PA before being taken underground for field testing. Test results of the system in both laboratory and field studies show reductions in operator exposure to respirable dust when the operator is positioned directly under the protected zone of the canopy.

Jan 1, 2012

By Robert G. Beverly

The presence of radioactivity in uranium mill wastes has resulted in somewhat unique waste disposal methods. In addition to the common problems of disposing of large quantities of solid wastes, neutralizing acids, minimizing dissolved heavy metals, and clarifying all liquid effluents, the uranium mill operator must sample and analyze liquid effluents for micro-micro quantities of radionuclides such as, radium-226, thorium-230 and lead-210. Special disposal methods or decontamination procedures are required to meet the stringent limitations established by the U. S. Atomic Energy Commission on the concentration of radionuclides in liquid effluents. Routine monitoring of the receiving stream is also normally required. In recent years there has been a growing concern about the radioactivity remaining in the uranium mill tailings, particularly at the sites of shut-down or dismantled mills. The State of Colorado, in cooperation with the industry, has adopted regulations for stabilization of inactive uranium mill tailings. The Mining and Metals Division of Union Carbide operates mills for the recovery of uranium and vanadium at Uravan and Rifle in Colorado and a mill in the Gas Hills of Wyoming for uranium production. The company also owns former mill sites on which mill tailings are located at Maybell, Rifle, and Slick Rock in Colorado and at Green River, Utah. The purpose of this paper is to describe the methods used by a few uranium mills, largely those operated by Union Carbide Corporation, to dispose of radioactive wastes, to discuss briefly the regulations under which the mills operate, and to present reference information on the subject.

Jan 1, 1968

By James R. Yancik

Economical and environmental pressures necessitates the recovery of the minus 0.6 mm x 0 coal generated by todays mining machines. This size fraction, dependent on the type of production unit, maintenance of the production unit, and the Hardgrove Grindability Index, can be a substantial portion of the Preparation Plant feed. Historically, dewatering of the collected 0.6 mm x 0 product has often been rather expensive and marginal with respect to surface moisture reduction. The Freeman United Crown II Preparation Plant more than adequately demonstrates that the continuous scroll type centrifuge can dewater 0.6 mm x 0 coal to acceptable surface moisture levels.

Jan 1, 1981