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By K. A. Smith, X. Cheng

Introduction The separation of minerals from complex sulfide ores by flotation requires careful control of the surface chemical behaviors of the minerals constituting the ores. When the minerals in the ore are finely disseminated, extremely fine grinding is needed to liberate the minerals. Fine grinding is not only an energy-intensive operation, but also influences the flotation behaviors of liberated minerals. Steel balls are commonly used for grinding. Galvanic interactions occur not only between sulfide minerals and grinding media but also among the different sulfide minerals themselves. The electrochemical characteristics of chalcopyrite and pyrrhotite when they are independently coupled with steel grinding media and the relevance of these characteristics to the flotation behavior of these minerals have been exten¬sively studied (Cheng and Iwasaki, 1992: Li and Iwasaki, 1992). These studies dealt with reactions in two electrode combinations, simulating mineral-grinding medium and mineral-mineral interactions. In practice, however, it is more common to involve more than one sulfide mineral. In a study of a pyrite-pyrrhotite-mild steel system, Pozzo et al. (1989) provided evidence that a mineral having an intermediate potential could behave differently, depending on the condi¬tion of galvanic contact. This investigation was undertaken to study a chalcopyrite-pyrrhotite-mild steel system to gain better in¬sight into the mechanism of multiple galvanic interactions. A three-electrode system was chosen to simulate a typical copper sulfide ore. The sulfide minerals were represented by chalcopyrite and pyrrhotite. The grinding medium was rep¬resented by mild steel. The nature of galvanic interactions involving these minerals and grinding medium in an oxygen atmosphere was investigated in a three-electrode combina¬tion, and an attempt was made to relate the laboratory flotation results of pyrrhotite-chalcopyrite ores. Possible implications to the differential flotation of complex sulfide ores are discussed. Key words: Electrochemistry, Flotation, Sulfide ores Experimental The pyrrhotite (57.74% Fe, 0.09% Cu, 4.84% Ni and 36.54% S) sample was obtained from Falconbridge Ltd.'s Strathcona mine, Ontario, Canada, and the chalcopyrite (26.00% Cu, 28.57% Fe, 0.05% Ni and 31.52% S) sample came from Transvaal, South Africa. Mild steel (AISI 1020, 0.2% C) was chosen to represent grinding media. A conventional three-electrode cell was used in the elec¬trochemical measurements. The working, counter and refer¬ence electrodes were, respectively, sulfide minerals or mild steel, graphite rod and saturated calomel electrode (SCE, 0.245 V vs. standard hydrogen electrode). The exposed areas of the sulfide minerals and grinding medium electrodes were approximately the same (0.17 to 0.19 cm2). The preparation methods of working electrodes, the reagents used, the experi¬mental procedures and the instrumentation were the same as those described previously (Cheng and Iwasaki, 1992). Rest potentials of pyrrhotite, chalcopyrite and mild steel were measured individually in 0.05-M sodium sulfate solu¬tions. Combination potentials and galvanic currents of the sulfide minerals and grinding medium were measured in short-circuited two- and three-electrode systems. All poten¬tials in this study are quoted in volts with respect to the standard hydrogen electrode (SHE). To simulate the constantly abrading conditions in a ball mill, rest potentials, combination potentials and galvanic currents were also measured by rotating a porcelain ball against chalcopyrite, pyrrhotite and mild steel electrodes in

Jan 1, 2000

By C. L. Peng, F. F. Min, S. X. Song

"Using a parameter representing the degree of hydration of particles in a liquid called hydration index I, which we derived based on Einstein’s viscosity equation, we evaluated the degree of hydration of fine montmorillonite particles in different aqueous solutions by measuring the viscosities of the montmorillonite dispersions and plotting relative viscosity against volume fraction of dry montmorillonite particles in the dispersions. We investigated the effects on the hydration of montmorillonite in aqueous solutions of (1) the type and (2) the concentration of electrolytes in the solutions and (3) pH. For the same concentration of electrolytes, the hydration index I of montmorillonite was found to increase in the order of Na+ > K+ for monovalent cations and Mg2+ > Ca2+ for divalent cations, and to decrease with increasing valence of cations in the order of Na+ > Ca2+ > Al3+. For both Na+ and Ca2+, the hydration index I first increased with increasing concentration of electrolytes and then decreased after a certain concentration. The hydration index I increased with increasing pH. IntroductionClay minerals have the distinctive ability to adsorb water molecules and hydrated cations in aqueous solutions, resulting in hydration on their outer surfaces and in their interlayer spaces. Many investigators (Jurinak, 1963; Anderson and Tice, 1971; Costanzo et al., 1982; Israelachvili, 1992) had found evidence of ice-like structures of water on clay minerals.This phenomenon of hydration plays an important role in the dispersion and sedimentation of clay minerals in aqueous solutions. To understand clay hydration, numerous experimental and simulation studies have been carried out since 1933, including the recent ones of Hawkins and Egelstaff (1980), Skipper et al. (1995), Karaborni et al. (1996), Salles et al. (2013) and Morrow et al. (2013). Among the factors that can influence a clay mineral’s hydration characteristics are chemical composition, type and degree of isomorphous replacement in its structure, and number and nature of associated exchangeable cations."

Jan 1, 2015

The 29th annual American Mining Hall of Fame Awards Banquet and Fundraiser sponsored by the Mining Foundation of the Southwest (MFSW) will be held at the JW Marriott Star Pass Resort, Tucson, AZ on Saturday, Dec. 3, 2011. Each year, one living inductee, two recipients of Medals of Merit, and up to five honorees from mining history are chosen by the MFSW for their outstanding contributions to the mining industry. Chilean Minister of Public Works and former Minister of Mining, Laurence Golborne Riveros will be the guest of honor, featured speaker and inductee into the American Mining Hall of Fame. Golborne Riveros was instrumental in managing the rescue of the 33 Chilean miners in October 2010 and in the coordination/management of the ?townsite? for family members, rescue support and the media. His engineering background and executive management skills made him ideally suited to assist in both a technical and managerial role in this emergency.

Jan 1, 2011

By S. S. Huyett

The opportunity to cooperate with the Mining Department of the Pennsylvania State University in their Student-Trainee Program is accepted by The New Jersey Zinc Company who believes that the participation in this type of a program will lead to a larger supply of high calibre engineers in mining. Trainees compete with other employees to earn the cost of their education while gaining practical experience in the mining industry. The practical experience is arranged to complement the technical education through a variety of work assignments. Job opportunities for the trainee are related to the work requirements of the Company and to the performance of the trainee. Management must consider and deal with a good many problems uncommon with regular, full 'time employees. For a number of reasons this program is recommended to other companies as a means to encourage outstanding young men who are interested in a career in the mineral industry to obtain a professiona1 education.

Jan 1, 1963

By Jerry M. Riggsbee, John H. Weber

INTRODUCTION The Washington Metro is a 98 mile rapid transit system that will serve the District of Columbia, southern Maryland, and northern Virginia. The construction work herein described relates to Section B-1 of this system. The contract for this work was awarded by the Owner, The Washington Metropolitan Area Transit Authority, to a joint venture doing business under the name of Ball-Shea-Norair. The partners in this venture were Gordon H. Ball, Inc., Danville, California; J. F. Shea Company, Inc., Walnut Creek, California; and Norair Engineering Corporation, Washington, D. C. The bid price for the project was $33,741,524 with a contract duration of 910 calendar days. Notice to proceed was issued January 5, 1970. The present modified price for the work is $36,866,000 with completion anticipated in July 1974. (About 1,638 days elapsed time.) The work to be done consisted essentially of construction of 3,490 linear feet of cut-and-cover track with side platform, and 600 ft cut-and-cover arch shaped subway stations. Stations are located in Judiciary Square and Eighth & G Street, N. W., areas. Decking of excavation in street areas, maintenance of traffic and utilities, vent and fan shafts, underpinning of court buildings in Judiciary Square and the Smithsonian National Portrait Building, and an electrical substation were included in the contract. Stations were constructed of cast-in-place concrete.

Jan 1, 1974

By K. Rajamani

A mathematical model based on the pertinent fluid dynamic equations to predict the performance of the hydro cyclone has been developed which will eventually replace the empirical model. Experimental measurements of fluid velocity profiles made in a 75 mm hydrocyclone by laser Doppler velocimetry (LDV) agree well their predictions by solving the Navier-Stokes equations numerically. Particle slip velocity and particle trajectory were computed which in turn, yields separation curve of the hydrocyclone.

Jan 1, 1988

By Larry Sevenker

On the basis of favorable salt characteristics, primarily compressive strength and impermeability, solution-mined cavities can provide structurally stable isolation chambers for waste. Solution mining techniques are established for storage of hydrocarbons. The proposition of waste isolation in engineered salt cavities is similar to this practice relative to characterization, certification and safeguards. What materials are isolated and how operations are conducted are principle differences. Compatibility of wastes with other wastes must be considered, but hazards can be precluded by avoiding certain mixtures. Waste material characteristics and cavity considerations are discussed.

Jan 1, 1981

By Jr. Gambrell

Support characteristics of in-cycle trusses are analyzed using a photo-elastic model loaded by tightening a truss in the sequence normally used in an underground mine. Stresses in the roof at its center point and at the junction of the roof and rib are examined. Effects of zero tension and unequal tension in the inclined anchor rods are presented. Effects of simulated subsidence on stress in the roof surface and on tension in the separate truss members are examined. Conclusions are drawn relating to (1) the effects of tension in the inclined anchor rods on uplift and compressive stress parallel to the roof surface, (2) the effects of subsidence on stress in the roof surface and, (3) the effects of subsidence on tension in the truss members.

Jan 1, 1989

By V. Montaruli, A. Nieto, M. Cardu

Nickel is a metal whose workability and mechanical strength at high temperatures and in corrosive environments makes it an indispensable alloying element for the realization of stainless steel, specialty steel, super-alloys, rechargeable batteries and electroplating. Because its main fields of application are key to the development of industry and, thus, to society, nickel has recently been recognized as a potentially critical mineral, despite its abundant reserves. The purpose of this paper is the creation of possible case scenarios determined by factors and events that, in the medium to long term, could change the current structure of the nickel market on the demand and/or the supply side. Four scenarios have been determined by considering a demand variation due to the occurrence of a natural disaster and an aerospace plan implementation and taking into account the resource nationalism and the skills shortage as supply varying factors. Through the creation of a georeferenced global nickel database, the paper proposes supply strategies related to the four scenarios for each top nickel consumer: China, India, European Union, United States and Japan.

Jan 1, 2013

By H. E. Grand

The purpose of this paper is to outline briefly some basic principles of ground- water hydrology that have application in mine hydrology. The development of a mine below the water table pleads for accurate values to answers of hydrology problems. Such problems involve both an inflow of water without adequate drainage facilities and a deficiency of water for the required use. Methods which give acceptable quantitative values for the solution of many ground-water problems depend on rather simple geologic structures, characterized chiefly by isotropic rocks of considerable areal extent. Unfortunately, mining operations are likely to be centered where isotropic rocks are not present. Consequently, methods that attempt to show values of the storage and transmitting capacity of rocks in mining areas must be applied with caution. In spite of complex geology and apparent uniqueness of individual mines and quarries, adherence to some concepts of ground water used by -hydrologists in the study of behavior of wells should be helpful to mine operators, The work of the Ground Water Branch of the U.S. Geological Survey through its history has been confined largely to the study of ground water as a resource, In view of the increasing number of problems relating to drainage of mines, the Branch started an investigation of mine hydrology in 1945 under the direction of W.T. Stuart, Mr. Stuart and other workers are making detailed studies of specific mine areas. In the present paper an attempt is made to synthesize some facts about ground water into usable form for the typical mine operator. Mining operations that extend below the water table disturb the natural hydrologic regimen, Prior to development, the water table slopes away from the site of a mine in at least one direction, but as soon as development begins and water is removed from the mine, the mine becomes the apex of a depressed cone in the water table, causing a convergence in the flow of water toward the mine. The behavior of the cone of depression, as it tends to deepen and increase in areal extent when the mine deepens, is related to the rate of withdrawal of water necessary to keep the mine dry. The significance and nature of the cone of depression in the vicinity of pumped wells has been studied by ground-water hydrologists for years, but the cone caused by pumping water from mines has generally been less systematically appraised.

Jan 1, 1958

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

The paper describes the process of collecting detailed accounts of near-miss incidents and turning them into impactful visual stories using graphic simulation. The aim is to create high-quality training materials to reduce haul-truck-related accidents and fatalities in mining.

Sep 1, 2023

By K. Fleck

Energy West Mining Co. (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, UT. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the in situ coal strength and load transfer mechanisms for improving two-seam designs and support systems.

Jan 1, 2012

By M. L. Harris

Coal dust produced during the mining process is a prime explosion hazard in underground coal mines. To inert the coal dust and prevent a catastrophic propagating dust explosion, rock dust is applied to the roof, ribs, and floor surfaces of mine entries. Currently, one determination of whether a mine is adequately protected from the coal dust explosion hazard is made by analyzing collected mine dust samples for percent total incombustible content (% TIC). A minimum of 80% TIC is required per 30 CFR 75.403. The as-received moisture of the dust sample is included in the % TIC. Moisture and humidity within a coal mine vary greatly with the seasons, with explosions occurring more frequently during dry winter months. This paper will discuss the fluctuations of the as-received moisture content of the mine dust samples collected by U.S. Mine Safety and Health Administration inspectors in 2010 and the observed fluctuations of the moisture content of rock dust within the U.S. National Institute for Occupational Safety and Health Office of Mining Safety and Health Research Bruceton Experimental Mine and the Safety Research Coal Mine over a one-year period.

By Terry A. Rightnour

Multiple seam mining is predominant throughout the central Pennsylvania Appalachian coal fields. Wide ranges in individual seam thickness, coal quality, and overburden characteristics are common throughout the region. On typical mining permits, ranging from 404 x 103 to 2023 x 103 m2 (100 to 500 acres), often as many as eight seams are concurrently mined, with each interburden requiring unique economic and environmental consideration in the mine plan. Specifically, this paper presents several planning tools and operational guidelines developed in response to current regulations for the special handling of potentially acid-forming materials as they are related to development and operation of multiple seam mines.

Jan 1, 1984

By E. Manev

Thin aqueous equilibrium film studies and surface tension measurements on a mixed surfactant system consisting of polyethylene oxide (a model frother) and potassium ethyl xanthate (a model collector) enable the interaction between the two surfactants at the air/solution interface to be elucidated. For the film containing the non-ionic frother, the interface was charged and addition of low concentrations of xanthate acted as a common electrolyte and reduced the thickness of the film inducing rupture. However, at high xanthate collector concentrations, the negative charge xanthate was found to interact with the non-ionic and caused a build-up of negative charge at the air/solution. Higher frother concentrations were necessary to produce non-rupturing thin films upon increasing the xanthate concentration.

Jan 1, 1992

By Kailash Narayan

Atlantic Richfield Company began operating a commercial uranium solution mining project in April, 1975 in Live Oak County, 10 miles southwest of the town of George West (Figure 1). The operation is designed to produce 250,000 pounds of U303 per year and is jointly owned by Atlantic Richfield Company, Dalco and U. S. Steel. The proprietary process employed in this operation consists of injecting an alkaline leaching solution into the ore-bearing formation through a pattern of injection wells. The uranium-bearing solution is then removed through producing wells using submersible pumps in central production wells. The produced solution is pumped through a pipeline to the plant area where the uranium is extracted. The barren solution is refurbished and returned to the pattern area for reinjection. The injection field and plant site are located in the drainage of Spring Creek, a small intermittent stream tributary to the Nueces River. Land use in the area is primarily agricultural -- cattle ranching and farming -- but several producing gas fields are present in the areas as well.

Jan 1, 1976

By George F. Weaton

During the past eight years there has been a dramatic change in the iron ore industry of Minnesota, in that its status has changed from that of a seller's market to a higly competitive buyer's market. Minnesota's natural ores must now be beneficiated and up-graded considerably to be marketed in order to compete with the higher grade foreign ores as well as with the locally produced and highly desirable taconite pellets. With the passage of the "Taconite Amendment' in the November, 1964 election, the taconite industry commenced to expand in Minnesota, which, although initiated in that state, was benefiting many other states and some foreign countries to a much greater extent than Minnesota. These other areas were actually appropriating markets that had been established and retained by Minnesota for many years. Since the approval by the state voters of this amendment, there has been a great increase in the development of taconite properties on the Mesabi Range.

Jan 1, 1966

By John A. Herbst, K. Rajamani

Process improvement is probably the most widespread objective of mineral process plant operators in the late 1980's. An important part of such improvements is dynamic optimization which involves reacting to inevitable plant disturbances in such a way that productivity is maximized at every instant of time. This paper describes the way in which mathematical models can be and have been used in dynamic optimization. Both off-line and on-line model applications are described.

Jan 1, 1989

By F. Alsobrook

Industrial minerals are receiving increased attention by metals, coal and other companies seeking to diversify and stabilize earnings. Each industrial mineral has a unique set (and sub-sets) of business dynamics, however, and the diversity can present a bewildering maze to the corporate planner. Shrugging off this complexity and relying on serendipity for entry opportunities often results in unsuitable acquisitions. An effective alternative used in exploration can also be applied to strategic planning. By providing focus and direction, this flexible methodology can prevent wasting corporate resources on random pursuits and result in a quicker, more satisfactory achievement of diversification goals.

Jan 1, 1990

By P. L. Webster, S. D. Thompson

The Coal Mine Belt Capacity Simulator (CMBCS) was originally developed to provide an improved belt capacity simulation through more detailed, flexible and realistic modeling of belt loading. While this model offered improved capacity design for conveyor belts and surge bins, it lacked the capability to simulate some key protection and segregation applications for bunkers. Recently, CMBCS was extended so that these latter bunker applications could be considered. In addition, a fear minor extensions were made to improve the model's flexibility and of efficiency. These various extensions and the steps taken to verify and validate them are described. The associated modifications in the model's input and output as well as the model's current requirements and availability are also discussed.

Jan 1, 1992