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By Ben W. Burdett

Since the late 19701s, the use of microcomputers in the minerals industry has grown to the point where today they can be found in virtually every plant within the industry. Their use in every aspect of instrumentation and control has increased the ease of operation and control of every phase of mineral processing. Their incorporation in sensors, transmitters, indicators, and controllers in addition to their use in distributed control and computer systems has provided operators with more timely accurate information than they have ever had before. This has led to an increase in the operator's effectiveness and an improvement in overall productivity. The ultimate aim of plant control is to maximize recovery in the mineral processing operation, and the microcomputer has spawned many tools that are now making this goal attainable. This paper discusses individual use of microcomputers in the areas previously mentioned as well as their collective use in overall control systems. The incorporation of local control systems in total plant control including the communication of information throughout all levels of plant management is also discussed. Finally the role the microcomputer is playing in today's plants is illustrated with numerous references to current examples.

Jan 1, 1985

By R. Raymond

The occurrence and distribution of organic sulfur in coals may be investigated using electron probe microanalysis, scanning electron microscopy, and optical petrography. A general relationship exists between macerals and organic sulfur contents in individual coals: sporinite, resinite = micrinite, vitrinite > pseudovitrinite = semifusinite = macrinite > fusinite. With increasing organic sulfur content of a coal, the total range in organic sulfur content between macerals containing high and low organic sulfur contents likewise increases. Furthermore, the organic sulfur content of the vitrinite in most coals equals the organic sulfur content of the coal. For any individual coal, organic sulfur contents of macerals correlate inversely with reflectance-in-oil measurements, but the amount the organic sulfur contents vary between macerals cannot be calculated based solely on the coal's rank. Formation of pyrite following peatification has no effect on organic sulfur contents of surrounding macerals.

Jan 1, 1986

By Irvine G. Reilly

Results of a preliminary study of the ammoniacal leaching of covellite (CuS) in an aqueous oxidizing system in the presence of a non-miscible organic sulfur solvent are described. Up to 60% of the sulfur can be recovered from the solvent as elemental sulfur 1 while achieving high degrees of solubilization of the mineral. The effects of temperature, particle size, oxygen pressure, ammonia concentration and ammonium ion concentration on the degree of sulfur recovery were investigated. Maximum recoveries were achieved at moderate temperatures and in well-buffered systems, with a large excess ammonia concentration. Oxygen pressure and particle size were found to have little effect on fractional recovery of sulfur. A simple empirical model based on electrochemical theory correlating the effects of some of the parameters cont-rolling the degree of sulfur recovery is presented. The results of this work also confirm that in any proposed reaction mechanism for the oxidative ammoniacal leaching of copper sulfides, the primary oxidation product of the sulfide ion in elemental sulfur.

Jan 1, 1978

By M. Gunter, M. Buzon, B. McNamee

"A Google search on talc asbestos will yield over 500,000 hits – the reason being the growing number of civil lawsuits in this area. Historically the litigation was centered on amphibole-containing industrial talc. There was no debate these talcs contained amphiboles, but the issue was the definition of asbestos. Ultramafic hosted talcs, however, are formed in such a way as to not favor the formation of amphiboles in the talc; they can occur in the surrounding black-wall, also the serpentinite host rock is in direct contact with the talc. Thus allegations can be made non-asbestiform amphiboles or non-regulated serpentine group minerals can occur in the final products. INTRODUCTION Gunter (1994) wrote the following in regard to the question “What is asbestos? “The question yields different answers depending upon the audience. To a mineralogist, asbestos is a mineral form. To an engineer, it is an industrial material with several useful properties. To a medical doctor, it is an agent that might cause certain diseases. The third answer invokes several more issues: to a lawyer, a possible lawsuit; to a news reporter, a story; to an asbestos abatement worker, a job; and to a public school administrator or a parent, a nightmare.” The main function of that article was to try and provide background information to be taught at the college level to help students understand some of the issues associated with the use of asbestos in our modern society, and especially its use as a fireproofing agent in schools and public buildings. At that point in time one of the main issues was asbestos abatement as the mining and use of asbestos was waning as its health risks became more clearly known in the occupational setting. Now over 20 years later the current issue we are dealing with herein is “asbestos” occurring naturally in talc. This is a well know concern for those in the talc industry and they have been working on methods to ascertain if their products contained “asbestos” since last century. As such our articles will focus more on issues emerging from recent litigation, and the confusion that occurs, especially in the “asbestos” nomenclature as the mineralogist, engineers, doctors, and lawyers previously mentioned try to communicate. And lastly we need to remain cognizant of the fact that people are still dying of mesothelioma in the US. As a last resort to recoup expenses as they are dying they often respond to the TV advertisements we’ve all no doubt seen."

Jan 1, 2016

By Ralph S. Mattson, Frederick T. Hancock

GENERAL DESCRIPTION The Granduc mine is situated on the west side of Granduc Mountain in the Leduc River area of north¬west British Columbia about 51 km (32 miles) north¬east of the town of Stewart. Entry is by means of a 16.6-km (10.3-mile) long haulage adit from the concentrator site at Tide Lake. The principal ore mineral is chalcopyrite. Ore mineralization varies from dis¬seminated to irregular semimassive stringers generally associated with highly folded and sheared biotite-rich sections of metasediments. The ore bodies vary in width from 3.6 m (12 ft) to over 18 m (60 ft) in a zone some 800 m (2600 ft) in length dipping at an average of 75° to the west and plunging steeply to the south. Capping varies in thickness from 0 to over 300 m (1000 ft). SELECTION OF MINING METHOD In the early stages of planning the primary require¬ments to be met by the mining method were: (1) suit¬ability to high output and productivity, (2) adaptability to mechanization in order to minimize operating costs, and (3) minimization of the costs and the development period for preproduction. Considering these, the selection of a mining method was narrowed to a choice be¬tween sublevel long-hole stoping or sublevel caving. A method utilizing backfill was ruled out as uneconomical, especially since mill tailings would not be readily available. At the time, the following facts about the ore body were recognized: (1) the average width of the ore body was 12 m (40 ft), (2) 30% of the stoping blocks were in areas of 6 m (20 ft) or less in width; (3) in many cases, ore zones were located in parallel lenses or were irregular in shape; (4) major faults were present in the hanging wall close to the ore, with minor faults within the different ore zones; and (5) the ore itself was lami¬nated with fractures and jointing crossing such bedding planes. Considering these factors, the two stoping meth¬ods were compared. Sublevel Open Stoping The characteristics of sublevel open stoping are: 1) It is generally not used for widths below 6 m (20 ft) since the ratio of waste development increases as level intervals are reduced to insure good control of long-hole drilling. 2) This method is used where ground is relatively competent. Otherwise more pillar support is required, increasing ore losses or mining costs with pillar recovery. 3) The method is not easily adaptable to parallel ore zones separated by relatively narrow waste bands. 4) Close control of pillar and stope design will per¬mit some degree of dilution control. Sublevel Caving Sublevel caving is characterized by the following: 1) The method can be used for a variety of ore widths, recognizing that 3 m (10 ft) in width may be an economical minimum. 2) It is particularly favorable where wall rock is weak. 3) The method has flexibility so that irregular ore bodies or parallel lenses can be mined. 4) The need to leave pillars for support is eliminated 5) Dilution and tonnage recovery are interrelated. With concern about the stability of the hanging wall and the geometry of the ore bodies, there was a growing favor to choose the sublevel caving method. However, this method was relatively new to Canadian mining practice. Teams were sent to Sweden to tour mines using sublevel caving and to study their methods and any extraction and dilution problems. The objective was to develop cost and performance data and ore recovery grades and tonnages for feasibility comparisons. Next, detailed mine plans were developed covering a three-year period using sublevel caving and sublevel open stoping. Extensive analyses of the development and production costs for each method were made. With sublevel caving, ore losses of 10% with a 20% dilution rate were used. The same ore loss was estimated for sublevel open stoping with dilution varying from 11 to 15%. As a result of these studies, the decision was made to use sublevel caving partly because slightly lower op¬erating costs, together with higher productivity, offset the adverse effects of higher dilution; and partly be¬cause, at the start, there would be less risk in being able to handle the ground, and the method offered more flexi¬bility. Open stoping was not ruled out for testing at a later date. It was recognized that some other method of mining would be required for mining the ore extensions below the glacier, where surface subsidence must be avoided. During the operating life of the mine, open stoping was tested in narrow width ore zones and found un¬satisfactory due to wall failure. A cut-and-fill stope, utilizing run-of-mine waste from development, was also operated on a trial basis. A sequence was finally estab¬lished that permitted ground control; however, produc¬tivity needed considerable improvement in order for open stoping to be considered as a sole alternative for mining below the main haulage level. At the termination of operations in June 1978 over 13 000 000 t (14,500,000 st) had been extracted from above the main haulage level at production rates varying from 3270 to 7250 t/d (4000 to 8000 stpd). Sublevel Caving Methods Two basic methods were used, transverse and longi¬tudinal. The transverse method was used mainly in the upper C ore body in widths greater than 18 m (60 ft), and occasionally as an alternative to the longitudinal method in localized areas where strike faulting inter¬fered with normal development. The longitudinal method was used in ore bodies varying in width from 3.6 to 18 m (12 to 60 ft), with a multilongitudinal varia

Jan 1, 1982

By C. Wayne Burnham

Much has been written about hydrothermal alteration and the compositional changes induced by it in the wallrocks of mineral deposits, especially in alummino-silicate wallrocks. So much has been written and the descriptions so varied, in fact, that the casual reader frequently is bewildered by the extreme complexities and lack of uniformity, real or apparent. Certainly the mineralogy and chemistry of altered rocks are not as simple as most of us would like, but neither are they as complex in their principal aspects as pa of what has been written would lead us to believe. The trend until recently seems to have been toward greater complexity and hence greater confusion, but the straightforward presentation of Creasey (1959), it is hoped, marks a reversal in this trend.

Jan 1, 1962

By R. V. Ramani, C. J. Bise

INTRODUCTION Classification of coal seams as thin, medium, and thick is both subjective and relative and is more a reflection of the statistical mode of the thicknesses en- countered in a mining region. A geological factor more precisely understood as defined than thickness is the inclination of the seams to the horizontal, commonly referred to as the pitch or the dip of the seam. Thick and steeply pitching seams present far more challenges to the ingenuity of the mining men to devise methods for their extraction than the thick and less steeply inclined ones. In a marginal case, where a thick coal seam may be minable by surface or underground methods, the decision bears a close relationship to the technological developments in the mining scene. Near surface thick coal seams are a special gift of nature and are not as wide- spread as the ones that call for the application of under- ground methods. Recent advancements in surface mining equipment have made it possible to surface mine to great depths. Stripping ratios of 30: 1 (cu yd of over- burden removed per ton of coal) have been achieved. The extraction of thick seams which preclude the use of surface methods is the concern of this chapter. Specifically, the objective here is to outline the special technological factors in underground mining of thick coal seams and to illustrate through several case histories the methods that are practiced in the North American continent. For the purposes of this chapter, a thick seam is defined as one which is not readily minable with currently available equipment without modifications to the extraction method or the equipment. At the present time, a thickness of 4.8 m (16 ft) can be considered as the lower limit, although developments in equipment and methods can be expected to push this limit upwards. The data for the case histories were collected from two extended mine visits in 1975 and 1978, and from other published accounts of the mines visited. Reference is drawn particularly to reports by Bise, Ramani, and Stefanko (1976) and Rarnani and Kenzy (1979). THICK SEAM MINING METHODS The various methods of mining thick seams can generally be grouped into three major categories: full face methods, where the entire thickness of the seam is re- covered in a single pass; slicing methods, where the seam is extracted to its full thickness by horizontal or inclined slices either in an ascending or descending order; and caving methods, where the seam is undercut and the en- tire coal seam is recovered by caving the top coal into the excavated cut, or some variations of the basic sub- level caving method. As shown in Table 1, in each of these methods, the coal is removed by either room-and-pillar or longwall methods. Hydraulic mining and transport of the coal in open flumes or in pipelines are also practiced. Addition- ally, the void created by the removal of coal may be filled with a packing material (stowing) except in the caving methods. The pitch (dip) of the seam, particularly when it is greater than 0.26 rad (150), imposes severe operational limitations on mobile equipment. A more detailed general discussion of the methods can be found in Bise et al. (1976) and Vorobjev and Deshmukh (1964). Specific discussion on the many variations of the three basic methods can be found in the papers presented at the international symposia that were held in

Jan 1, 1982

By Kenneth Deaton

"A packaged cooling system is being developed for refuge alternatives (RAs) that will meet U.S. Mine Safety and Health Administration (MSHA) qualification guidelines for deployment in coal mines. This system will allow full occupancy ratings of deployed refuge alternatives to be maintained by keeping the apparent temperature inside the RA from exceeding 35° C (95° F).Research investigations sponsored by the National Institute for Occupational Safety and Health (NIOSH) have shown that heat buildup caused by occupants in mobile RAs will result in apparent temperatures that exceed the 35° C (95°F) limit established in 30 CFR 7.504.Figure 1 shows the temperature rise in an inflatable RA having an occupancy rating of 23 people at an 27° C (81°F) mine air temperature. This plot shows the need for either heat mitigation or occupancy derating in warmer mines.The Refuge Alternative Environmental Control System (RAECS) will be designed to provide enough heat mitigation to eliminate occupancy derating due to heat buildup over the 96-hour refuge period.This article describes testing of a prototype cooling system that uses proven vapor compression technology powered by batteries to keep the RA interior below the 35° C (95° F) limit for a minimum of 96 hours. Testing of this prototype cooling system was conducted in December of 2015 and January of 2016 at the NIOSH test mine in Bruceton, PA. December testing was conducted at the prevailing mine ambient temperature — approximately 15.5° C (60° F). The January testing was done with the mine ambient temperature in the immediate vicinity of the RA artificially elevated to 29° C (85° F). Realistic heat gain from RA occupants was provided by human simulators developed by NIOSH. These simulators add sensible heat corresponding to human metabolic processes and latent heat generated by respiration and perspiration. Heat generated by CO2 scrubbers was also added. Results of cooling system performance using these simulated loads at the two ambient conditions are described. A comparison of the apparent temperature in the RA using two different control techniques is also presented. This work documents the ability of the cooling system to meet the established apparent temperature limit at the full occupancy rating of a six person RA. A new cooling system intended for use with existing RA deployments and having greater cooling capacity is currently in development and will be described.Expendable desiccant modules were also used to provide supplemental water vapor removal and their role in mitigating cooling load is addressed."

Dec 1, 2016

By David Kwietnewski

Roadheaders are gaining widespread acceptance in North America as a means for mechanical tunnel excavation. Until recently, almost all of the large-scale North American tunnel projects were excavated one of two ways ? the tried and true drill-and-blast method or with the use of tunnel boring machines (TBM), the hi-tech super-excavators. TBMs enjoyed fast-growing popularity worldwide as TBM manufacturers offered greater technology to meet the demand of the civil tunnel industry in the late 20th century. Recently, though, more tunnel projects, large and small, can thank the brute force of a roadheader for getting the job done.

Jan 1, 2011

By Philani Larrance Ngwenyama, Ronald CW Webber-Youngman

The survival chances of trapped miners in underground mines depend on how quickly they can be located and rescued post-accident. During entrapments, emergency rescue is highly desired but can be hindered by the lack of positioning information when a fit-for-purpose missing-person locator system is not available. Various types of missing-person locator systems are available to aid search-and-rescue operations. From the wide range of the available systems, selecting the most suitable one becomes the next challenge. The available systems have not been measured if they are fit-for-purpose or not, and to what situation. This study proposes user requirements that can be used as a guideline to facilitate the system selection process. These user requirements provide a framework for the design and development of a fit-for-purpose missing-person locator system. The user requirements can also be used for evaluating the performances of a particular system, predict its success, and also drive future research toward developing new technology to enhance the capabilities of the current systems.

Apr 1, 2024

By J. P. Sieverson

The Comprehensive Environmental Response, compensation, and Liability Act (CERCLA -commonly referred to as Superfund) was passed into law in December 1980 in the wake of such incidents as Love Canal and the Valley of the Drums. Superfund was originally perceived as a way of cleaning up spills of hazardous substances and/or cleaning up abandoned hazardous waste dumpsites. In February 1981, Michael Cook, EPA deputy assistant administrator for hazardous emergency response, called Superfund "a tremendously powerful law. It could revolutionize the way the environment is protected, but we certainly don't intend to realize the full potential of the law for some time." These words have proven prophetic for Asarco's East Helena Smelter.

Jan 1, 1988

"History - How did you get into mining and involved with SME?Unlike many past presidents, I do not come from a mining lineage. I liked math in high school and believed I wanted to be an engineer. I told my math teacher that, and he laughed in my face. I believe that humiliation is what carried me through engineering school. At the time my ability to go to college relied on how inexpensive I could make it. My brother told me that there were a lot of scholarships in mining engineering, and I should apply to mining schools. As usual, he was right and I was off to the University of Idaho to study. My first summer break I got a job with Hecla at a mine in Arizona. I was a laborer on a shotcrete crew. I knew after the first summer that I loved underground mining, and I never considered changing disciplines. Looking back, I was working in miserable conditions (hot, humid), on a miserable job (shotcrete), where I got injured, and two summer student roommates died in a car accident on the commute home after work. I had every reason to hate the industry, as I had seen virtually everything bad about what we do. But I didn’t, I loved it. I said I was good at math, I never said I was smart.I joined SME in college because I was told to by the head of the mining school, Dr. Jack Hoskins. You did what Jack told you to do. I got involved because I went to an annual meeting and the papers in the underground sessions were terrible. I refer to bad papers as the “Tensile strength on cable bolts in sub-arctic regions on Tuesday” papers. Real snoring fodder. I don’t remember who I was complaining to, but they told me to quit my grumbling and fix it. So I chaired a session, and tried to get only good quality papers, something that has been my mantra for years with the Mining & Exploration Division. I also volunteered to help the local sections too. Then one day I woke up as president.What is your opinion of the health of the mining industry?The mining industry is in bad shape. Coal is under attack and will likely never recover to its former greatness. Our President has banned new coal leases, and the state of California is forcing people it does business with to divest their interests in coal companies. And that all happened in just in a few short weeks this January. Usually in America you get a trial before you are given a death sentence, but not with coal."

Jan 1, 2015

By Andre Vien, SANDRO DAVID DI, Frank Laroche

In 1994, Claude Bazin presented a novel method for linking size data from milling models to the feed input of flotation models. It was achieved with the simple addition of a metal/mineral distribution–size distribution relationship. This allows grade and recovery predictions from a varying mine plan through product size distribution predictions. 

By Milka Madahana, John Ekoru

For efficient management of operations, mining companies are required to be able to predict potential scenarios for main market factors. Competitive advantage and value creation are established through managing the value chain well. The mining value chain is usually faced with challenges from various shifts in commodity markets as well as ongoing uncertainties. Therefore, there is a need for accurate analysis of data from the markets, for the prediction of commodities, for instance, Precious Group Metals (PGM). The main objective of this research work is to apply machine learning methodologies with the aim to identify patterns and trends in the Precious Group Metals, and thereafter analyze and predict the future trends of these markets. Numerous machine learning models are applied to a dataset consisting of 15 years of daily price for eight precious metals namely Platinum, Palladium, Rhodium, Ruthenium, Osmium, Indium, Silver, and Gold. The results reveal the patterns and trends within the data sets and that different machine learning methods could be suited for the prediction of market prices for each of the PGMs. The application of an amalgamation of various machine learning methods may result in more accurate predictions of the PGM markets. Accurate prediction of market prices for PGMs will possibly result in unlocking untapped sources of value in the mining industry.

Jun 25, 2023

By D. A. Lee

The selection of control system equipment for a mineral plant is based on several criteria, including opera tor interface, supervisory capabilities, ease of maintenance, ease of programming and configuration, compatibility with auxiliary control equipment, and total cost. The paper discusses the technical evaluation procedure with respect to control system equipment available today.

Jan 1, 1988

By Hans von Michaelis

Welcome to RANDOL GOLD FORUM 88. It is clear from the list of delegates and speakers that this conference will lead to excellent discussions of the latest developments in this fast-moving industry. Less than a year ago Randol International Ltd. published an eleven-volume report titled "Innovations in Gold and Silver Recovery - Phase 111". In the short space of time since then, many new developments have been noted, many of which will be described in this Forum. I believe that some of the more significant innovations currently under development are those that address the following:

Jan 1, 1998

By Robert E. Thurmond

With modern exploration techniques, it seems likely that an increasing number of the orebodies to be found in the future will be under alluvial fans or valley fill. As a result, a larger proportion of open pit mines will be confronted with the necessity for removal of substantial quantities of alluvial overburden; whereas in the past, for the most part, the open pit mine operator has dealt mainly with hard rock. If this proves to be the case, methods, equipment, and costs for alluvium stripping will become an increasingly important factor in open pit mine planning. Several operations are now faced with this situation, and various methods and equipment are used. At Pima Mining Company's operation the stripping ratio is in the range of 6/1 Well over half of the stripping volume is alluvium. The alluvium is removed almost entirely by carryalls hauling direct to a waste dump. Some removal has been accomplished by shovel and truck operation; more will be done by this means in the future. At American Smelting and Refining Company's neighboring .Mission Mine, nearly all alluvium removal is by large shovels and, trucks. U. S. Borax's Boron operation is accomplishing alluvium removal with carryalls but has been investigating other methods and equipment. The various operations in the Gas Hills Uranium District in Wyoming are stripping mainly with carryalls, although some small draglines are employed. The M. A. Hanna Company in the Mesabi Range employs large draglines and conveyor systems for removal of glacial fill. Nchanga Consolidated Copper Mines in Northern Rhodesia strips overburden with a large excavating wheel and conveyor system. There are no doubt other open pit operations with which the writer is not familiar, that are handling large quantities of alluvial overburden.

Jan 1, 1963

By Donald R. East

For many years there has been increasing pressure on mining companies, not without some justification, to design tailings storage facilities which guarantee some degree of protection against process solutions entering local groundwater and surface water flows. A fairly straightforward approach to achieving this has been to design conventional water-retaining type structures, and this has often been reinforced by the need to store large volumes of process water and seasonal run-off within the tailings facility. The conventional design uses naturally occurring geological barriers and a conventional embankment with possibly a grout curtain, or artificial barriers around the entire facility, using either imported low permeability soils, admixtures, or synthetic liners. While these approaches may achieve the primary objective of minimizing seepage, various other factors should be considered. Firstly, by depositing the tailings slurry in a sub-aqueous manner, the tailings, especially if relatively fine grained, will settle to very low densities and little or no on-going consolidation may occur over the operating life of the mine, There have been many cases where measured pore pressures within the tailings mass equal the total overburden stress, i.e., no consolidation and no strength, many years after decommissioning.

Jan 1, 1998

By P. O. Ripley

Into this tumultuous twentieth century, every second, two new babies are born. This is 5,412 per hour, and 130,000 per day. Relentlessly, consistently, alarmingly, they add to the more than three billion human beings who already inhabit the earth. Every tick of tier clock brings with it a problem child, the problem of another mouth to feed, another body to clothe, another human being for whom to provide. On the other hand, medical science has achieved a postponement of death, considerably past the period of a few years ago. Thus, life expectancy has been increased and world population has increased accordingly. Darwin (4) writing in 1962, suggests "It is curious how long the world is taking to perceive that we are living in what is a fantastically abnormal period of history, and one which must inevitably end soon, The first warning note of a possible population explosion was given by Malthus in 1799". He suggested that population increases geometrical while production increases only arithmetically and that soon we would not be able to feed the rapidly increasing population.

Jan 1, 1966

By H. Rush Spedden

A process has been developed and piloted to reject copper, lead, iron, phosphorus, bismuth, antimony, elemental sulfur, and insol from molybdenite concentrate without decomposing the contained molybdenite and rhenium. The impure concentrate is first heated with concentrated sulfuric acid at 260 to 290°C for 1 hour. This bake not only oxidizes the contaminating sulfides, but also activates the concentrate for later rejection of insol by flotation. Two stages of leaching follow the sulfation step. The first is an acidified water leach which extracts the oxidized copper, iron, and phosphorous; the second leach rejects the lead, bismuth, and antimony into a warm concentrated solution of sodium chloride. Final upgrading is achieved by conventional froth flotation. The chemistry of the process as well as results obtained from its implementation in a 5,000 lb/day pilot plant are presented.

Jan 1, 1971