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By S. Donges, P. L. Dunstan, B. J. Huls

The commissioning of a distributed digital control system for the grinding circuit at Cuajone was completed by mid-August 1985. Development of a successful strategy, excellent operator acceptability, and the visual aspects offered by the display of the central console improved mill through- put significantly. The inherent features of a digital system enhanced the flexibility in grinding control and allowed the milk and classifiers to be operated at maximum capacity. This paper discusses the strategy development and the production restrictions encountered, and evaluates the overall performance of the digital control system.

Jan 1, 1988

By Pedro Sanchez-Mejorada

Laguna del Rey is the name of a dry lake bed located in the State of Coahuila, Mexico in a semi-desertic terrain typical of the basin and range physiography. Química del Rey, S.A., a subsidiary of Industrias Peñoles, has been producing sodium sulphate since 20 years ago, from brines pumped from the sub-surface of the present playa. The spent brine is used as raw material for the production of magnesium oxide. An extensive, lenticular deposit is found just below the playa. It consists mostly of glauberite (sodium-calcium sulphate) and blöedite (sodium-magnesium sulphate). The glauberite occurs as thin crystals oriented at random and leave many void spaces among them. These intercrystalline spaces are partly filled with mud, but the whole mass of the evaporite is still very porous. A brine that contains in solution ions of sodium, magnesium, sulphate and chlorine occupies the voids of the sponge-like evaporite body.

Jan 1, 1984

By D. Wheeler

Similar to modern day petro-chemical processes, the flotation column is a complete break from the conventional manner of floating on a batch basis in cells. The column has a reputation of being only suited for cleaning applications, particularly that of molybdenum cleaning. The original column, invented and developed by Column Flotation Co. of Canada, Ltd., was developed as a Rougher-Scavenger. Only after proving its capability in this field was cleaning allowed. One rougher-scavenger column in closed circuit with a cleaner column produced better grade and recovery than a conventional cell plant consisting of one stage of roughing, two scavenging and four stages of cell cleaning. Three cleaner columns replaced 13 stages of conventional cell cleaning and resulted in higher grades and recoveries. The gentle countercurrent action of the column itself together with complete automatic control enable this machine to produce such results.

Jan 1, 1986

By P. T. Bissert, L. Yan, M. D. Klein

"Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Mobile RAs have a limited ability to dissipate heat, and heat buildup can lead to a life-threatening condition as the RA internal air temperature and relative humidity increase. The National Institute for Occupational Safety and Health Office of Mine Safety and Health Research performed heat testing on a 10-person tent-type training RA and contracted ThermoAnalytics, Inc. to develop a validated thermal simulation model (TSM) of the tested RA. The TSM was used to examine the effects of the constant mine strata temperature assumption, initial mine air temperature (MAT), initial mine strata surface temperature (MSST), initial mine strata temperature at depth (MSTD), and mine strata thermal behavior on RA internal air temperature using 117 W of sensible heat input per simulated miner. For the studied RA, when the mine strata temperature was treated as a constant, the final predicted RA internal air temperature was 12.8°F lower than it was when the mine strata thermal behavior was included in the model. A 10°F increase in the initial MSST resulted in a 7.1°F increase in the final RA internal air temperature, whereas a 10°F increase in the initial MSTD yielded a 2.5°F increase in the final RA internal air temperature. INTRODUCTION Since 2008, the Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines (1). MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. NIOSH recommended an apparent temperature limit of 95°F in its 2007 report to Congress (2). In 30 CFR 7.504, MSHA has specified a maximum apparent temperature of 95°F inside an occupied RA (3). The apparent temperature is calculated using both air temperature and relative humidity (4). Calculations could be used to determine if the air within an occupied RA will reach the apparent temperature limit. In these calculations, in order to simplify the problem, the mine temperature could be assumed to remain constant. With this assumption, the effects of the mine strata thermal mass and thermal conductivity on the heat buildup in an RA are ignored. OMSHR research has shown that the mine air and strata temperatures surrounding an RA increase when subjected to the heat of an occupied RA (5). Thus, calculations performed with the assumption that the mine temperature is constant would under-predict the resulting dry-bulb temperature and apparent temperature for a given RA occupancy. The mine air temperature has been used as the basis for RA temperature calculations. However, research has not been used to confirm that the mine air temperature is the appropriate basis."

Jan 1, 2016

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By Alan G. Fricker

Cyprus Gold NZ Ltd will be recovering residual free cyanide in barren gold pulp by air stripping. Laboratory investigations by DSIR have indicated additional advantages by recovering the cyanide from pregnant pulp. These are a lower leach pH, a greater cyanide recovery and less carbon consumption. They have a net economic advantage of $1.20/tonne over recovery from barren pulp. The realisation of these advantages is dependent on three crucial technical aspects -optimum pH for dissolution, the absolute loss of cyanide and the stability of the aurocyanide ion. The laboratory investigations described herein address these aspects. Earlier work had indicated that the rate of dissolution of freely revolving gold discs at constant cyanide ion concentration increased with decreasing pH from 11 to 8. Attempts to repeat the work in a more controlled manner by measuring the corrosion potential and current density have, to date, not been reproducible, but do not contradict the earlier observations. Cyanide recoveries and balances were obtained on leaches at pH 10.5 and 9 at the same cyanide ion concentration -the lower pH requiring three times as much total cyanide. Unaccounted-for losses, unfortunately, exceed the accounted-for losses, making interpretation of the balances difficult. Nevertheless, it appears that the additional amount of cyanide at the lower pH of 9 may not be fully recoverable. It may not, however, prove necessary in practice to use more cyanide at a lower pH. Both the gold and silver cyanide complexes remain available for carbon adsorption, as do mercury, copper and iron. Zinc, and probably cadmium, nickel and lead, may precipitate during stripping, which is an environmental advantage.

Jan 1, 1991

By Stanley Dempsey

Since its passage, the Mining Law of 1872 has been modified several times to meet the changing needs of America's society and economy. Despite the fact that it continues to provide an effective framework for a robust US exploration and mining industry, the mining law continues to be criticized in some quarters as outdated. Pressure to reform the Mining Law of 1872 has reached new levels in recent years. Many proposals for reform of the law have been introduced during the 1990s. None, though, have been enacted. The issue will not likely disappear and is certain to be raised during the 105th Congress. To provide a better understanding of the status of current congressional reform proposals, this article presents an overview of the major moments in the history of mining laws in the western United States - from the days before the 1872 mining law and the days following its promulgation, to the current dilemma over mining law reform. The future of the mining law is assessed as are the interests at stake for the modern mining industry. Mining before 1872 No discussion of the Mining Law of 1872 is complete without some historical background to provide an understanding of the origins of this unique law. There was plenty of mining activity on the public lands before the mining law was enacted. At first, the federal government's policy was to allow all miners to work freely on the public lands and to resolve disputes among themselves. In this "hands off" environment, miners operated according to laws they promulgated. These were based on previous experiences in Europe and Mexico. These "frontier codes" of groups of individual miners took the form

Jan 1, 1997

By Jamal Rostami, Tala Tahernia

TBM utilization rate is a component of machine performance prediction and critical for developing a reliable estimate of the construction completion time and cost of the tunnel. Estimation of the utilization rate involves identifying and quantifying the time dedicated to each activity in a tunneling jobsite. Ring building is a common activity in TBM tunneling and takes a large amount of tunnel excavation time when using shielded TBMs. This paper concentrates on the effect of tunnel diameter on the duration of downtimes related to ring building and examines the impact of machine diameter on downtimes. For this purpose, the dependency of segment installation time to segment configuration, and also the diameter of the tunnel was investigated. Furthermore, the ring building time for four tunnels with different sizes of diameters and a variety of ring arrangement were analyzed and the relationship between TBM diameter and segment installation time and consequently TBM utilization was evaluated.

Jun 13, 2021

By Frank J. Foster

This Paper will deal with Bucketwheel Suction Dredging and its particular relationship to mining applications. There will be comparisons with other methods of suction dredging and descriptions of two recent bucketwheel installations in the mining area. The Directory of World Dredging Fleets published in the `larch 1984 edition of World Dredging magazine shows that there are about 1.000 conventional Cutterhead Dredges listed throughout the world with 289 in the United States. There are 242 Bucketline Dredges listed throughout the world of which only 6 are in the United States. These figures are not completely accurate because several units are known to the author that are not on the list and, of course, there may be others.

Jan 1, 1984

By J. T. Graves

Bauxite, dolomite, and magnesite are natural occurring minerals that are used extensively in the manufacture of refractory products. In addition, magnesia produced from seawater or brine finds its way into the production of refractories. All of these materials must be processed at high temperatures, 1500°C to 2200°C, to produce an intermediate raw material (refractory grain) , which can then be used in the final manufacture of refractory bricks and shapes. During the last 20 years, the major supply of refractory bauxite has been from Guyana, and at times the annual production has ranged up to 1,000,000 tons per year. More recently, China has become a major source of refractory grade bauxite by supplying over 300,000 TPY. Other sources of bauxite in lesser quantities have been Surinam, Brazil, and the U.S.A. During 1980, the estimated available world tonnage amounted to slightly more than 1,300,000 tons. The bulk of this material has been calcined in rotary kilns except for some of the Chinese production, which was treated in shaft kilns. Recent work has indicated that an excellent product can be produced in the Nichols Shaft Kiln using much less fuel than the conventional rotary kiln. Details of the Nichols Shaft Kiln will be provided later in this paper.

Jan 1, 1982

By C. Anderson, B. Schug, C. Cristoffanini, S. Nazari

The Haile Gold Mine in South Carolina is increasing the automation level of their processing plant in order to improve operational stability. One step towards this goal is the application of a Digital Twin concept to provide Virtual Instruments. Haile has engaged ANDRITZ to implement Virtual Instruments at their grinding area hydrocyclones and at their tailing thickener underflow pump. These virtual instruments provide density values in a traditionally difficult location for reliable slurry density measurement. The Digital Twin is a first principles IDEAS1 ™ simulation model, connected in real time to the control system. Results have been promising, with the virtual instrument values matching the physical instrument under normal operating conditions, and showing better prediction under upset conditions. Haile plans to use the virtual instruments as optional process control parameters. INTRODUCTION OceanaGold’s Haile Gold Mine is located near Kershaw, South Carolina, about 50 miles southeast of Charlotte, North Carolina. This location was first mined in 1827, and has produced gold through several operating periods since then, including a heap leaching operation from 1985 through 1992. In October, 2015, OceanaGold acquired Romarco Minerals, the previous owner of the Haile Operation. The current operation began in 2017 as an open pit mine with additional underground resources. The nameplate throughput is 6,350 tpd ore, and 2017 production was 118k oz gold, with 140 to 155k oz gold expected in 2018. Proven and Probable reserves exceed 3 Moz. The process, as shown in Figure 1, includes a primary jaw crusher, comminution with a Semi-Autonomous Grinding (SAG) mill and ball mill circuit, flash flotation, rougher flotation, regrinding, pre-aeration, carbon in leach (CIL) leaching, carbon elution and regeneration, cyanide recovery, electrowinning and refining. The Haile Operation’s inaugural gold pour took place January 20, 2017. Mine life is expected through at least the year 2030. Based partially on prior experience of some key OceanaGold personnel with automation services from ANDRITZ on other projects, OceanaGold decided to include ANDRITZ on the Haile project. The scope of these services for Haile included design and supply of the process control application software, an ANDRITZ dynamic process simulator for operator training, and ANDRITZ Advanced Control Expert (ACE) ®2 systems for the SAG mill, ball mill, and rougher flotation areas. Since startup, ANDRITZ has continued to provide services for the site, particularly related to PLC and HMI equipment, programming and support, ACE system expansion, and the implementation of Virtual Instrumentation. The implementation of this new Virtual Instrumentation technology at Haile is consistent with Haile goals: increased automation, a change in the role of the operator from interactor to monitor, and improved stability by removing human error.

Jan 1, 2019

By Herschel H. Potter

Back injuries arising from such activities as lifting and handling objects have been and continue to be constant and undiminishing hazards of the occupational environment. Back pain in one form or another is experienced by almost a1 1 individuals. During the past 30 years, a great deal of accident prevention education has been directed toward the reduction of back injuries. However, it has not produced any great change in the incidence of the injury. The human spine remains the most vulnerable area of the muscul o-skeleta1 system. Back injuries account for about 400,000, or 18 percent, of all disabling work related injuries each year according to the National Safety Council estimates. These serious back injuries are estimated to have cost more than 1.9 billion dollars in 1976 in medical and lost time pay. 1

Jan 1, 1981

By A. J. Sinclair

One hundred and eleven pyrite samples from 3 porphyry-type deposits in the Canadian cordillera were analyzed (many in duplicate) by AA spectrophotometry for Co, Ni, Cu, Pb, Zn and Mn. All elements have density distributions that are lognormal or combinations of lognormal populations. Co and Ni in pyrites show zonal patterns that relate generally to mineralogical zones in the porphyry systems, particularly if contoured as the Co/Ni ratio. High Cu values in pyrites also correlate with Cu-rich mineralogical zones. Other elements studied appear less regular in their distribution patterns, although Zn highs in pyrite seem to occur sporadically near the margins of porphyry systems. In particular cases, pyrite geochemistry shows potential as an exploration tool to aid in target definition for detailed exploration.

Jan 1, 1976

By Norm Greenwald

The Environmental Protection Agency ("EPA") has been attempting to develop a federal regulatory program for mine waste under Subtitle D of the Resource Conservation and Recovery Act since 1986. Recent regulatory and legislative events are now bringing this goal closer to reality. This paper discusses the mining industry's perspective on a number of the issues currently being addressed at EPA's Policy Dialogue Committee and in Congressionally-sponsored negotiating sessions.

Jan 1, 1992

By G. K. Derby

Paper presents project results investigating current techniques for dragline wire rope removal and the development of less hazardous means of performing the task. The cannon is the most prevalent method used in American surface mines. A cannon test program was conducted that used 40-and 50-grain primer cord to establish force produced using a 56-pound projectile. Socketlwedges were separated to establish separation force data. Two alternative removal methods, pendulum ram and portable hydraulic pusher, were developed and tested. Both provide sufficient force to effect separations under normal conditions on draglines with up to 78- cubic yard buckets.

Jan 1, 1984

By E. J. Wasp

An upsurge of interest in slurry pipelines to move coal from Wyoming, Montana, and Colorado to markets in the southwest, west, midwest and northwest has recently developed. Specific pipelines have been proposed to serve these markets; the routes of these lines are depicted in Exhibit I. It is, therefore, timely to discuss some technical aspects of the terminal facilities for these western coal pipelines. The discussion will be based on experience with the Ohio and Black Mesa pipelines as well as detailed planning and testing for a proposed 1,000-mile system from Wyoming to the middle south area. The economics of the pipeline terminal processes are heavily depend¬ent on site, type of process used, and other specifics of the situation. However, the following approximate breakdown of costs for a 1,000 mile, large capacity pipeline will be useful for orientation purposes. [Water supply 4 Coal cleaning 5 Feed preparation 10 Slurry transportation 72 Dewatering terminal 9 100%]

Jan 1, 1976

By Frederik P. Agterberg

During the past 20 years, methods of multivariate statistical analysis have been developed on mainframe computers for the integration of geological, geophysical, geochemical and LANDSAT data in mineral resource appraisal. At present, it is becoming increasingly feasible to perform mathematical image analysis of digitized patterns on microcomputers. This has led us to develop a new method of statistical pattern integration for mineral exploration. In this paper, the new method is used to outline, by means of posterior probabilities, exploration targets within small areas of which the prior probabilities for occurrence of new mineral deposits had been estimated by multivariate analysis.

Jan 1, 1989

By Michael J. Friedel

The permeability and flow capacity in unsaturated media is investigated by the Bureau of Mines for application to in situ copper leach mining at the Cyprus Casa Grande mine site. Moisture retention properties are derived and combined with scanning electron microprobe data to characterize the mineralogy, texture, pore size, distribution, and permeability of the host rock. Finite element modeling is used to derive a saturated permeability, ambient degree of saturation, and assess various injection-recovery schemes. Recommended design modifications for optimization of solution distribution and maximum recovery from the rock matrix requires either (1) the injection pressures on the order of 1500 psi and recovery wells operating in a suction mode, or (2) performing permeability enhancement, through rubblization. By producing a maximum block diameter of 4 m, injection pressures can be reduced to 500 psi with improved recovery and containment of solutions.

Jan 1, 1991

By K. N. Santini

Natural zeolites are gaining recognition as an important commodity with an increasing number of industrial and consumer applications. This potential has prompted the Anaconda Minerals Company and other firms to investigate occurrences and markets for zeolites. The deposits of mordenite-rich tuff at Rome are of interest for their economic potential and for the excellent opportunity they provide to study a zeolite deposit formed in a hydrologically closed basin. Location The Rome property is located approximately 9 km west of Rome, Oregon, in Townships 31S. and 32S., Range 41E., Malheur County. It lies within the Owyhee Uplands of the northern Basin and Range physiographic province (Figure 1). The area discussed here includes a major portion of the depositional basin in which the zeolitic tuffs occur.

Jan 1, 1982

By C. Patrick, T. Combs

The purpose of this paper is to provide a method for analyzing the sequencing of mining production processes and predicting the effects of any planned changes. Included is a description of the development and utilization of a project-scheduling simulation that combines analytical scheduling with stochastic-activity durations. The simulation is demonstrated in two realistic examples: a longwall face-to-face transfer sequence and the effect of varying advance rates on longwall development sections. Statistical data that can provide a basis for more informed production decisions are generated in the form of project activity/path criticality and project-duration distributions. In both examples, a quantitative risk assessment, regarding subjective decisions in underground production sequencing, is presented.

Jan 1, 1996