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Reaction kinetics for gold dissolution in acid thiourea solutions were investigated using formamidine disulfide as an oxidant. For the conditions studied it appears that a surface reaction limits the rate of gold dissolution. The rate was found to be first order with respect to thiourea concentration and half order with respect to the concentration of formamidine disulfide; the apparent activation energy for the reaction was 10.40 kcal/mol (43.40 kJ/mol); and the reaction rate was independent of pH for the pH range 1.0 to 3.0.

Jan 1, 1999

By Peter L. Dunn

With the advent of new high-strength magnetic materials, rare-earth magnetic separators have become more common place for processing heavy mineral sands. In many instances, rare-earth magnets have replaced conventional separators such as electromagnetic cross-belt and induced-roll type machines. This paper will present the results from a detailed test program developed to evaluate the performance of rare-earth drum and roll separators for processing heavy mineral sands. The effect of machine design parameters, such as magnetic element configuration and separator diameter, will be reviewed in light of these test results. The impact of basic operating parameters (i.e. feed rate and roll speed) on separation efficiency will also be presented.

Jan 1, 1999

By Henry E. Keniston

In every business today costs come under almost microscopic scrutiny. It's hard to conceive that less than 30 years ago there was no such cost consciousness apparent in overall industry. Railroads, through their almost absolute monopoly on freight handling, were one of the industries where little thought was given to overall costs. True regulation kept rates in line, but railroads did very little in the area of supplying equipment intended to help the shipper minimize his costs and at the same time result in savings to the rail carrier. During this period, except for isolated cases, railroads placed standard cars for loading. Most railroad car fleets consisted of box cars, hopper cars, flat cars and low side gondola cars certain roads having unique movements developed special cars to accommodate the particular product, but seldom did these cars move in general interchange service. Most of you are aware that several large companies built railroads of their own as an integral part of raw materials handling from remote sources to production plants located near concentrations of usage. On these railroads special cars were built with little thought to inter-change service. Examples of such railroads are the Duluth, Missabe and Iron Range, the Elgin, Joliet and Eastern, the Union Railroad, the Bessemer and Lake Erie and the Birmingham Southern.

Jan 1, 1972

By George H. Davis

The Caribou sulfide deposit near Bathurst, New Brunswick (Figure 1) is illustrative of one variety of strata-bound sulfide deposits. It consists of numerous near-vertical sulfide lenses which are concordant to the foliation and lithologic layering of low-grade metamorphic host rocks. Pyrite is the chief mineral in these lenses, but appreciable quantities of sphalerite, chalcopyrite, and galena are also present. Rocks in the Caribou mine area belong to the Tetagouche Group of Ordovician age. They consist chiefly of (1) quartz-sericite and quartz- sericite- feldspar schists, (2) greenschists, and (3) slate and phyllite. The trends of these steeply dipping rocks define the trace of a tight, steeply plunging fold structure, the Caribou fold (Figure 2). This fold plunges approximately 750 to the north-northwest; its axial plane strikes N.20°E. and dips steeply westward. Sulfide lenses of the Caribou deposit are associated spatially with the Caribou fold. The deposit is located in the fold along the contact between quartz-sericite and quartz-sericite-feldspar schists on the hanging wall and quartz-chlorite-sericite phyllites and graphitic schist on the footwall (Figure 3). Genesis of the Caribou deposit is ambiguous because its strata-bound form suggests syngenetic sulfide deposition, whereas its location within a fold suggests structurally controlled epigenetic mineralization. Acceptability of a particular genetic model rests on establishing the time of mineralization relative to deposition, deformation, and metamorphism of the associated rocks. To establish the timing for Caribou mineralization, the deformational histories of rock and sulfide, respectively, were compared. Epigenetic and syngenetic models can be tested against this interpreted structural history of the Caribou deposit.

Jan 1, 1971

By I. Iwasaki

The effects of autogenous grinding and conventional grinding on the floatabilities of copper-nickel sulfides were investigated as a part of a pilot-plant development project on the differential flotation of Duluth gabbro. At the same mesh-of-grind copper, nickel, and cobalt recoveries were higher and residual sulfur in the flotation tailings was lower with the autogenously-ground pulps. With the ball-mill-ground pulps the residual sulfur in the tailings could not be lowered to the level attained by the autogenously-ground pulps even at increased levels of the collector addition. From mineralogical examinations of concentrate and tailings samples, an electrochemical interaction between grinding media and sulfide minerals was thought to have a greater effect on sulfide mineral flotation behavior than the breakage characteristics of the ore samples in these two types of mills.

Jan 1, 1981

By R. J. Sweigard

Estimated costs and revenues can be used in the evaluation of post- mining land use alternatives. However, post-mining land use decisions have to be made in an environment complicated by several additional factors. These factors, including cultural, natural, and managerial issues, are not as easily quantified as costs and revenues but may be more important determinants. There- fore, some approach is needed to attach relative weight to the various factors. The concept of fuzzy sets assembled into a structured hierarchy facilitates analysis of the relative value of individual factors and their impact upon each alternative under consideration. In this paper, a method is presented which employs fuzzy set analysis to evaluate postmining land use plans on the basis of these nonquantitative factors.

Jan 1, 1986

By Thomas H. Koenning

The number of spontaneous combustion incidents in the U.S. is expected to increase as the consumption of lower rank coals and the use of longwall mining becomes more prevalent. A spontaneous combustion incident holds the potential for substantial loss of life from a mine fire or explosion if not prevented or controlled at an early stage. Laboratory tests have been developed which are useful in ranking the susceptibility of various coals to spontaneous combustion. Ventilation circuits and mining methods can be designed to minimize the risk of spontaneous combustion. Early detection of spontaneous combustion is possible with the combined use of continuous monitoring, periodic gas sampling, and inspection.

Jan 1, 1989

By Warren G. Burres

or more than 50 years the Portland Cement Association has represented the United States cement industry in matters relating to the technology and use of cement and concrete. Interestingly enough, PCA?s emphasis has been on concrete and its uses rather than on Portland cement. The cement industry realized long ago that cement is basic and serves its fundamental purpose as an ingredient in concrete. Cement could never be successful if concrete were not. Work with the users and specifiers of concrete had to be done at its end point of application--in a building, bridge, dam, highway or home. PCA, over its half century of existence, has been dedicated to this job. I should like to talk to you today on the less technical side of concrete--what it has been--what it is today--and what it can offer in future construction. Concrete, in many forms, has a long background extending from such notable historic times as the Roman Empire. Here, concrete made from pozzolanic cement from the slopes of Mt. Vesuvius was used to construct the Coliseum, home of the Roman circus; for the Appian Way, the ancient forerunner of the Interstate system; and the miles of aqueducts throughout Europe, many of which still carry water. In 1811 Joseph Asppin, an English bricklayer, made the first modern cement by the artificial mixing of pulverized limestone and clay materials. Ht,

Jan 1, 1971

By V. H. Forsythe

Mr. Chairman, members of SME, and guests It is indeed a pleasure to have the opportunity to appear before this group. The topic of this paper is, "Current Trends in Related Industries and Their Influence on Electric Shovel Design and Size". Before getting into the major items, it is well to point out that this text will deal with loading shovels primarily, since their application is almost universal in major open pit mining operations throughout the world. Related industries influence our design in many ways. For the sake of simplicity, these industries will be broken down into two major categories. The first category to be discussed will include industries that will indirectly influence design and size, while the second category will include industries whose products can directly be incorporated by the engineer in the design of shovels.

Jan 1, 1964

By Kirk Carlton

The Athabasca tar sands of Alberta are an increasingly important source of crude oil for the North American continent. Published figures indicate estimates of recoverable resources in the tar sands at some 300 billion barrels of synthetic crude of which some 86 billion barrels can be recovered by surface mining techniques. At the present time, two commercial plants are in operation, Great Canadian Oil Sands Limited and Syncrude Canada Ltd. Their present combined capacity is approximately 150,000 barrels per day. Some of the factors which will make this oil expensive will be noted here. The location of the present producing plants is 500 kilometres north of Edmonton at an elevation of approximately 320 metres. Recorded temperatures range from +38 to -55 degrees Celsius. Wind velocities are not high but the chill factor with even a slight breeze and minus 40 degrees is very uncomfortable.

Jan 1, 1979

By Dr. Richard F. Coon, James D. Mavis

Risks and abatements associated with preliminary reconnaissance, plugging and filling, and maintenance of perched mine water pool are examined. This case history showed that the initial appeal of portal plugging was replaced by concern over potential environmental hazards when details of implementation were investigated.

Jan 1, 1992

By D. B. Gentzler, J. L. Kohler

A method of monitoring production information (raw tonnage and machine state) from each working section has been developed. The method is based on the sensing of electrical parameters in each section load center, and the reporting of this information through the existing mine-wide monitoring system. A decision-theoretic type of pattern classification technique has been used to define the machine states. The basis of the method is presented in this paper, along with a proposed hardware and software implementation scheme. Information issues central to the development and use of the proposed production monitoring system are also discussed.

Jan 1, 1990

By William P. Blacutt

This paper examines Bolivia's General Environmental Bill recently passed by Congress: a multi-purpose law with two primary objectives: a) the protection and conservation of the environment, and b) the promotion of sustainable development. In this law, environmental benefits are emphasized by stating general principles, not by attempting to define the means. Regulations are left to the writing of subsequent complementary codes. This paper shows that much of the controversy surrounding the legislation disappears when it is seen as guide rather than an operational part of Bolivia's industrial policy. In essence, the law addresses recent environmental awareness in a region more anxious than ever to speed economic growth.

Jan 1, 1992

A knowledge of airway friction factor (K-factor) is necessary to designing mine ventilation systems for least cost and optimum effectiveness. The friction factor used must be accurate and reliable to estimate correctly roadway resistances and pressure sources for required flows. Though the resistance to flow offered by mine airways has been an object of study over the last half century, no accurate relation has yet been established from which the prediction of the resistance of a projected airway can be made. In Kentucky, only limited and incomplete data on local K-factors are available. Therefore, there is a need for field investigations to determine these values in-situ for existing mining conditions. The author describes a study concerning K-factor that was carried out in ten coal mines, located in eastern and western Kentucky. The results of these investigations are presented in both tabular and graphical form.

Jan 1, 1991

By Kevin Lofftus

The rest potentials of molybdenite electrodes are measured as a function of pH in absence and presence of flotation reagents. The chemicals used include sodium ethyl xanthate, kerosene, dextrin,sodium hydrosulfide, hydrated sodium molybdate, sodium sulfate, and hydrated sodium thiosulfate. The effect of dissolved oxygen is also noted. The obtained data are correlated with the results of micro-flotation tests obtained under similar chemical conditions.

Jan 1, 1984

By Steve Kral

"The mining industry is a tough business. The obstacles faced in attempting to run a mine - much less build a new one - go beyond an orebody’s geology. There was a time when commodity prices dictated whether or not to build or expand a mine. Today, though, the challenges faced by miners include social responsibility, environmental regulations and a myriad of needed permits on several governmental levels that every miner knows will be challenged by opponents every step of the way. With all of those challenges, and others not mentioned here, it’s a wonder anyone would stay in the industry. But they do. In fact, more than 2,100 mining professionals from around the world gathered in Reno, NV last December for the American Exploration and Mining Association’s (AEMA) annual conference. That is an impressive number, considering that commodity prices remain in the doldrums, preventing companies from building many new mines and limiting expansions at existing ones. Even so, attending such a conference allows these mining industry pros to learn new and more efficient ways to operate their mines and plants through the dozens of technical presentations the conference offered. And mingling with their peers provided another avenue for learning. The AEMA conference also attracted many of the industry’s leading equipment and service providers (228 exhibitors in 246 booths). Technical presentationsThe AMEA meeting is known for its variety of high quality technical presentations and the 2014 conference was no exception. Some of the topics include new technologies in surface and underground mining, explorers and emerging producers, mine closure and remediation, regulations and reserves reporting, hydrology and new innovations in mining. Here is a sample of some of the presentations."

Jan 1, 2014

By C. Sampaio, C. Petter, M. Veras

"INTRODUCTION Use of sensor technology applied to the gravimetric beneficiation is intended for the selective preconcentration or separation of various minerals. Sensor Based Sorting (SBS) uses sensors to identify the particles and separate them by a mechanical process (flap) or pneumatic ejection valves (Wotruba et al. 2014). The principle of the SBS technology to separate mineral particles consists of three phases which cover feed,detection and separation. (killmann, 2009 Apud nienhaus et al. 2014). The applicability of the technique in an early stage of beneficiation enables free particles and poor grade to be a part of the process. The mass of tailings to be processed can be removed at the initial stage to save energy, water and equipment maintenance (Wotruba et al. 2014). Lindner (2010) suggested that the use of SBS technology would only will be possible if there exsists an electromagnetic interaction in all the wave spectra interacting with the solid ore. The interaction of electromagnetic waves depends directly on the characteristics of the material. The material receives a spectrum of electromagnetic waves by irradiation and this results in a reduced wavelength with differing types radiation such as fluorescence, reflection, remission, absorption, transmission and transmission. The frequency of the wave spectrum varies between 1000 and 1020Hz, illustrated by the data in Figure 1, which shows that each type of sensor emits a wavelength inversely proportional to the frequency ranging from 10-11pm to 104km, and the frequency that varies between EHz 103 and 1020kHz. The difference between the electromagnetic spectrum variations can only be visible to the human eye at wavelengths with intervals between 380nm and 780nm (Wotruba et al. 2014). One of the main advantages of operating with imaging sensors is the versatility of the images which can take on zero, one, two or three dimensions shown below as a point, a line, an area or a spatial image, as illustrated in Figure 2. According to Schubert (1988), to separate a mineral particle it is necessary to follow the characteristics of mineralogy, physics and chemistry with or without use of water. The use of new technologies can help reduce operating costs and improve utilization of mineral resources."

Jan 1, 2016

By W. D. Hausel

The Wyoming Province is an Archean craton which underlies portions of Idaho, Montana, Nevada, Utah, and much of Wyoming. The cratonic block consists of Archean age granite-gneiss with interspersed greenstone belts and related supracrustal terranes exposed in the cores of several Laramide uplifts. Resources found in the Province and in the adjacent accreted Proterozoic terrane include banded iron formation, Au, Pt, Pd, W, Sn, Cr, Ni, Zn, Cu, and diamonds. The Province shows many similarities to the mineral-rich cratons of the Canadian shield, the Rhodesian and Transvaal cratons of southern Africa, and the Pilbara and Yilgarn blocks of Western Australia, where much of the world's precious and strategic metal and gemstone resources are located.

Jan 1, 1991

By Toshio Fujiwara, Sumikichi Ito, Masao Kitamura

The Tennohji-Benten Giant Trunk Sewer Project has been under construction since 1974 in the eastern part of Osaka, the second largest city in Japan. The entire project is divided into 7 blocks, some of which have already been completed. This 8.8-km sewer tunnel, being driven through a densely populated area, was planned to be constructed by the shield tunneling method. This paper described shield tunneling performances and ground behaviors during the construction of Blocks 2 and 3. An earth pressure shield (dia., 6,750 mm) was employed in Block 3 tunneling. The ground was generally soft and the cover over the tunnel varied from 13 m to only 4.5 m, so that a considerable amount of chemicals was injected to stabilize the ground. A hand-digging type shield (dia., 7,250 mm) was used in Block 2 tunneling under compressed air. For 85 m of the total length of 1.6 km, the soil at the face was extremely soft, and therefore, the ground freezing method was additionally employed.

Jan 1, 1981

By Ashish Ranjan Kumar, Barbara Arnold, Luis Sanchez Gonzalez

The health and safety of miners is critical in the industry. Prolonged exposure to dust-laden air results in irreversible ailments like pneumoconiosis that have a severe impact on their lives. Operations use various personal protective devices (PPEs) to alleviate their exposure to respirable dust. Powered Air Purifying Respirator (PAPR) is one such device that uses high- efficiency filters and positive pressure masks to shield miners from airborne contaminants. Used in the medical and other industries, these respirators efficiently protected healthcare workers during the COVID-19 pandemic. Recently, the mining industry has shown a growing interest in adopting this PPE to ensure safe working conditions for the miners. We present an introduction to the PAPRs and discuss their dust capture efficacy in this manuscript.

Feb 1, 2025