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By Duncan M. Lamb

Commercial computer "time-sharing" is a new and powerful tool for the engineer. It is a system of virtually simultaneous use of a digital computer by several individuals. Access to the computer is by means of a conventional teletypewriter which transmits over the regular telephone lines to the computer which may be located any distance from the user. Complex or repetitive computations can be programmed and the speed of computation is many times that which one can do with slide rule and desk calculator. The availability of such a commercial computer "time-sharing" system offered an opportunity to transform a tedious and time-consuming task into one that requires only a few minutes. Until the work of F. C. Bond produced widely accepted mathematical statements concerning the performance of grinding mills, the selection of the proper size equipment was done by comparison with similar operating equipment. Allis-Chalmers systematized Bond's work in a bulletin published in 1963 but the calculations are laborious and the final mill selection still required comparison of the calculated power draw with the power requirements listed in equipment catalogs. This was, however, a step forward from previous procedures. This paper discusses a rapid and simple method of determining the size and power requirement of overflow ball mills. A shared-time computer program has been developed which rapidly calculates and displays the physical dimensions, power requirements, grinding media size and quantity, as well as the important correction factors used. All of these data are calculated from input information which is usually available.

Jan 1, 1969

By John A. Folinsbee

Placer Dome Canada owns and operates the Campbell mine and mill at Balmertown, in the north western corner of Ontario. The mine operates at 1.3 kt/d (1,500 stpd). It produced more than 9.3 t/a (300,000 oz/year) of gold during the last three years. Changes to the gravity concentration circuit have resulted in a 10% to 15% increase in gravity recovery. The mill head grade at the Campbell Mill is relatively high, averaging 18.5 g/t (0.54 oz/st) over the total reserve tonnage. During the past several years, the head grade was averaging close to 20 g/t (0.6 oz/st). Before 1994, gravity concentration was achieved by using a combination of conventional mineral jigs and tables. Jig concentrates were upgraded on shaking tables to produce a concentrate, which was refined to bullion. In May 1994, management decided to buy two Knelson CD 760-mm (30-in.) concentrators. The objective was to replace the existing jigs and increase gravity gold recovery by up to 15%. Gravity recovery with jigs averaged between 30% to 35%. Gravity recovery was anticipated to increase to about 50% with the Knelsons.

Jan 1, 1997

By Lawrence Pelham

The demand or consumption of fluorspar has been somewhat taken for granted in recent years, except for the specific interest of those that produce, market, and/or consume the commodity. A tradition was established of thinking that as the steel and aluminum industry goes, so goes fluorspar. This is much less true today than in the past. The industry is becoming more dependent on chemical industries that feed primarily off hydrofluoric acid (HF) production. The Bureau of Mines recently published an assessment of world fluorspar reserves and resources that created a foundation of valuable data that can be used to monitor fluorspar availability. Celebrations were held this year commemorating the 100th anniversary of the isolation of fluorine. The United States and other countries continue to struggle with the controversy of ozone depletion and the effect of fluorocarbons on the atmosphere. The goals for the U.S. Government's strategic stockpile are being reevaluated. The market for fluorine chemicals is changing and diversifying, making it a challenge to assess and forecast fluorspar/fluorine demand. This paper reviews the recent past of fluorspar and helps set the stage for a more detailed assessment of this critical commodity.

Jan 1, 1986

By Víctor Vázquez, Guillermo Tiburcio, Martin Encinas, Jesús L. Valenzuela, Erick Montaño, Alejandro Valenzuela, José Parga

Merrill-Crowe is the primary process used for the concentration and purification of silver in a cyanide solution. The Langmuir Adsorption model for silver recovery in a cyanide solution was used for the study. The maximum adsorption capacity was 6.19 mmol/g for silver. This model properly adjusts the experimental results of the adsorption equilibrium with high correlation coefficients, which also favors the formation of a single layer of molecules adsorbed for the silver in the electrocoagulation- generated species. The thermodynamic parameters ΔG, ΔH, and ΔS were estimated, and it was found that the adsorption process is exothermic and spontaneous. For the kinetic study, the Lagergren second-order equation was used to study the adsorption speed. To characterize the solids coming from the electrocoagulation, X-ray diffraction (XRD), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) were used; the results of this study suggest that silver is present in aluminite, hydroniumjarosite, and alunogen.

Oct 30, 2021

By R. H. King

Underground coal mining machinery utilizes portable electric sables, "trailing cables." to obtain power from load centers or distribution boxes. Cables are frequently damaged since mobile equipment, poor lighting, and restricted space are inherent to coal mining operations. Normally, the damage is repaired by splicing--the joining of one or more severed conductors and replacing insulation and jacket. Figure 1 illustrates a typical single conductor splice. Although the repair seems simple, difficulty of the splicing process is exemplified by the many safety hazards and frequent production delays that result from defective splices. Forty-two cable splice related injuries were reported to the U.S. Bureau of Mines in 1972 and 1973. Additionally, 17 splices related fires were reported in the three year period prior to December 1972. Assuming the damaged area is quickly located, an average splice time for a two conductor cable is twenty minutes. Some operators estimate this delay is incurred once per day per operating section. If one ton per minute is averaged throughout the shift, each unit could loose 4800 tons per year from splice delays. An estimated cost for materials and labor to make a splice is $20. The expenditure could result in a $4800 annual cost per section. The estimated expense does not include wages of other personnel waiting for the repair to be completed. Nevertheless, labor and materials cost is minor compared to the income lost from decreased production.

Jan 1, 1975

By J. C. Stankus, K. J. Ma, D. Faulkner

To protect mine personnel and moving equipment at underground roof fall areas, mine operators typically install steel sets, which are covered with wooden blocks and backfilled with an expanding-type cement material. In large roof falls, the cost of void backfilling becomes prohibitively high, causing some mines to leave the voids open. However, the durability of wood over time and the capability of the steel set and wood lagging to resist falling rock are unknown. This has caused concern for the U.S. Mine Safety and Health Administration (MSHA) and ground control engineers. During the last few years, Keystone Mining Services, LLC developed various impact-resistant steel set designs that were approved by MSHA and installed in various underground fall rehabilitations. This paper presents an impact-resistant steel set design methodology, including (1) steel set design per AISC national standard, (2) design, development and laboratory testing of a waterproof coated impact-resistant lagging panel and (3) impactresistant steel set design based on the law of conservation of energy. Two underground cases will be included detailing the application of the system.

Jan 1, 2011

By M. A. Reyes, L. Yan

Heat and humidity buildup withn refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. The Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a lifesustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 h while maintaining an apparent temperature (AT) below 95 °F (35 °C). The National Institute for Occupational Safety and Health (NIOSH) tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in its underground coal mine facilities to investigate the thermal environment over a 96-h period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners (SMs) increased over the 96-h test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating the interior heat and humidity temperature profiles for occupied RAs not tested in situ.

By Floyd M. Thorman

Gypsum is the crystalline chemical compound CaS04?2H20. A close chemical relation - and frequently occurring with Gypsum ? is Anhydrite which is Cask. Gypsun has wide commercial use because relatively simple heat processing reduces it to Plaster of Paris. While Anhydrite can be converted to Gypsum and thence to Plaster of Paris, the procedure is not simple and is quite costly. Anhydrite, however does have use in the agricultural field and in the Portland Cement industry. Occurrence of Gypsum in the earth structure is usually near or at the surface. Most underground mining is at 60 to 100 feet although one mine in southwest Virginia reaches a depth of 1300 feet. Gypsum is one of our softest minerals, rating only 2.0 on the Mohs scale of hardness. Specific gravity is 2.3 to 2.4. It is soluble in water but only slightly so. Interestingly, it is more soluble in cold water than in hot. For example, one part Gypsum dissolves in 370 parts water at 106° Fahrenheit while at 212°F. the water requirement is 452 parts. Compressive strength of massive Gypsum runs about 3000 lbs. per square inch. Color ranges from grey and brownish-grey to white.

Jan 1, 1973

By Tina Živec, Žibertm Marko

"Civil design has changed in many ways using BIM (Building Information Modelling) technology in its most recent form. Such a technological breakthrough has not been successful so far in traditional oriented Engineering Geology, except in the Mining and oil exploration markets with budgets on much different scales. The fact is that paper, pencil and hand drawn sketches are still state of the art and a perfectly acceptable way of producing subjective geological interpretations.Using the technology available, we have developed a set of procedures and techniques to combine the latest surveying and remote sensing technology, GIS based tools to manage large data sets and BIM modelling techniques in a 3D geological environment.To demonstrate the concept, the forthcoming Karavanke tunnel project (Slovenia) has been chosen for testing techniques. The project, with its rich documentation from previous phases and new data available, represented a good basis for testing the possibility of digitizing geological data while communicating with Leapfrog Geo 3D modelling algorithms. This type of procedure would then allow engineers at the construction site to use the 3D model for prognosis and evaluation, while upgrading it daily with new information.INTRODUCTIONThe Karavanke tunnel crosses the mountain range on the border between Slovenia and Austria. As the geology is very complex due to its imbricate fan structure, a series of geological – geotechnical and hydrogeological investigations have been performed since the 1970s, resulting in extensive project documentation. The construction of the 7864 m long single-tube two-lane tunnel took place in the late 1980s. Currently, the tunnel represents a critical point on Pan-European Transport Corridor X (Salzburg, Austria – Thessaloniki, Greece), with insufficient safety measures. The need for improved traffic flow and enhanced road safety led the Slovenian government in 2013 to a decision to continue with activities regarding the construction of the second tunnel tube 70 m east of the existing tunnel.The extensive project documentation from previous investigation phases and construction of a new tunnel tube presented a good base for a pilot project, in order to test the emerging new technologies for data acquisition, processing and analysis in a 3D environment. Several products are available on the market for data acquisition and 3D geological modelling, but only a few can be applied in the civil design, as well. Developing a standard format and procedure for implementing the 3D geological model using new remote sensing techniques, 3D geological modelling tools, such as Leapfrog Geo and BIM (Building Information Modelling) modelling techniques would move the Engineering Geology, Geotechnics and Tunneling to a more advanced level. 3D modelling tools would therefore not only be used as a visualization tool, but would also contribute to in a more efficient communication and workflow between the professionals involved in the project."

Jan 1, 2016

By I. H. Douglas

All grade control methods in use currently by the mining industry are imprecise. The methods suffer from being locally inaccurate, leading to are loss and contact dilution. An ore/waste indicator variable can be used to predict the probability of ore occurrence at a given location, Po. Then, an ore grade Zo for an ore location and a waste grade Zw for a waste location are obtained. The expected revenue is calculated at each location, based on its probability of being are or waste, the corresponding grade, and on the cost of mining and processing the ore or the waste. Finally, the decision of whether to recover the block is based on the expected revenue value for that block. The method is illustrated with an example taken from the Jerritt Canyon district in northeastern Nevada.

Jan 1, 1994

By W. Hu

Gravity concentration has been the main method for tin ore beneficiation, based on the significant difference of density between cassiterite and gangue in the tin ore. However, with the exhaustion of rich and coarse reserves, the proportion of tin distribution in slime be-comes as high as 50 to 70% and has a size range of -19 urn. In some sulfide tin ore, most of the tin is of the minus 10-urn size fraction, and thus slime processing has gained importance in tin ore processing. Some innovations are being developed, such as the centrifugal cone separator, belt concentrator, slime table, B-M separator, and slime flotation. Direct flotation with tolyl arsonic acid has been practiced with success.

Jan 1, 1989

By John L. Shafer

A process for the conversion of stibnite (Sb2Sj) concentrates, crude antimony oxide, or metal to a pure cubic antimonous oxide (senarmontite) has been developed on a laboratory scale. The conversion of stibnite to senarmontite has been piloted. The high purity of the final product is the result of forming antimony trichloride as a low temperature distillable intermediate. To obtain the antimony trichloride the stibnite, or crude oxide is slurried in molten antimony trichloride and reacted with gaseous hydrogen chloride. Antimony metal is oxidized to the trichloride with chlorine. The hydrogen sulfide produced from the hydro- chlorination of stibnite can be upgraded to a strength of 95% or greater for further treatment. The crude antimony trichloride is separated from the gangue by a preliminary evaporation and then is fractionally distilled and the trichloride distillate has less than 50ppm of arsenic and lead combined (the most troublesome impurities in antimony processing). The purified antimony trichloride is then hydrolyzed with sodium or ammonium hydroxide to produce the cubic form of antimonous oxide (senarmontite) to the exclusion of the rhombic form (valentinite) which is photosensitive. The advantage of this process is the ability to treat a wide range of antimony ores, concentrates, and metal to yield a high purity oxide in a controllable range of particle sizes.

Jan 1, 1975

By Jessica M. Wempen

"Differential Interferometric Synthetic Aperture Radar (DInSAR), a satellite-based remote sensing technique, has application for monitoring subsidence with high resolution over short periods. DInSAR uses radar images to measure centimeter-level surface displacements. In the images, ground resolution can be relatively high, with each data point (pixel) representing the average displacement over an area of several square meters. The image data are acquired regularly which allows subsidence to be monitored sequentially over short periods; imaging periods typically range from weeks to months.Monitoring subsidence over short periods with high spatial resolution has potential to provide insight into the dynamics of subsidence and into relationships between mine advance and subsidence. In this study, for three longwall mines in the western United States, initial subsidence occurring at the start of longwall advance is quantified over short periods (12 to 72 days). C-band interferometric wide swath Synthetic Aperture Radar (SAR) images from the Sentinel satellites are used to quantify the subsidence. Overall, the data show initial development of subsidence, expansion of the subsidence trough, and the advance of subsidence in the direction of mining.INTRODUCTIONApplied Differential Interferometric Synthetic Aperture Radar (DInSAR)Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique that can be used to quantify small displacements of the Earth’s surface. Using data from the Seasat satellite, which was launched in 1978 (Jet Propulsion Laboratory, 2018), studies by Goldstein, Zebker, and Werner (1988) and by Gabriel, Goldstein, and Zebker (1989) applied Synthetic Aperture Radar (SAR) interferometry to topographic mapping and displacement monitoring. These studies established the potential for broader applications of radar interferometry. Studies by Foxall, Sweeney, and Walter (1998), Wright and Stow (1999), and Carnec and Delacourt (2000) represent some of the earliest evaluations of DInSAR for mine subsidence monitoring. All three of the studies demonstrated the application of DInSAR for quantifying mine subsidence. They also demonstrated difficulty accurately measuring subsidence over long periods due to data decorrelation. DInSAR continues to be evaluated as a tool to quantify surface deformation related to active and historic mining. For example, see Vervoort and Declercq (2018), Wempen and McCarter (2017a), Chen et al. (2013), and Liu et al. (2013). Technologies associated with SAR interferometry continue to develop. Recently launched satellites have relatively high spatial and temporal resolutions, and data processing methods and data accessibility are improving."

Jan 1, 2019

By A. C. Lordi

Present industrial plant design is influenced by motivators beyond the usual powerful one, creativity, on which Consultants thrive. The respected, although annoying, ever-present Return on Invested Capital becomes even more significant with anticipated escalation. Government regulations are having an increasing influence as air and water protection, sound and electrical safety requirements must be met And more recently, the increasing cost and uncertain availability of energy sources are having a revolutionary affect on plant design. More than ever before, the Consulting Engineer is faced with requirements and restrictions which tax even the most original thinkers -- and the result is good. This paper includes a brief review of recent trends in Cement Plant Engineering Design.

Jan 1, 1975

By F. J. Bruey

Refdist is a simple but valid approach to planning or analyzing a test-vs-control plant trial that uses accumulated plant performance data to calculate objective criteria for judging the trial outcome. Refdist calculations and results are explained and illustrated with data typical of the mining industry. Findings from a simulation study of Refdist statistical properties are reported. Suggestions for dealing with messy data situations are offered.

Jan 1, 1999

By Frank McKinley

This paper discusses the basic requirements covering the area between the initial discovery of a deposit and a decision as to whether or not the deposit will support an economically sound mining venture. The procedure for gaining the necessary information and the sequence of steps is in .some respects parallel to gaining like information on deposits other than the sand type. For the sake of simplicity the stages and sequence are presented as follow: first, the initial reconnaissance drilling; second, the exploration drilling to permit initial ore body estimates; third, metallurgical testing; fourth, the estimate of plant and operating costs; and last, the economic balance. The objective of the reconnaissance drilling is to collect sufficient information to reach a decision as to the advisability of further exploration or the abandonment of the area. This initial phase will comprise, in addition to some drilling, a thorough reconnaissance of the area, a study of the best geological and topographic maps of the region, and a study of any literature available, all under the guidance of a geologist.

Jan 1, 1958

By Harry Sutcliffe, Francis M. Keville

The paper describes the, impact of the geotechnical exploration program on the line and grade of the tunnels and the shaft configuration on the Red Line Extension N.W. in Cambridge and Somerville, Massachusetts, and comments on several aspects of the implementation of the project.

Jan 1, 1983

By Judson C. Higgins

The paper addresses changes in surface transportation methods in the Industrial Minerals business starting with history, the changes to present time including such areas as energy costs, improved highways, changes in regulations and deregulation, and attempts to project future transportation trends. Transportation methods such as rail, piggyback, truck and barge are compared, and their impact on Industrial Minerals producer's costs and profits examined. The customer impact on our businesses due to deregulation is also discussed.

Jan 1, 1983

By A. F. Peterson

There is no single mining problem at Benson that does not exist at some other mine. There are four, however, that require special attention primarily because they occur together and have an influence on each other. These are the nature of the mineral occurrence, the shape of the ore body, the operating schedule, and the climate. It is the purpose of this paper to describe mining practices in relation to these four factors. Iron ore was first noticed in the Star Lake area early in the nineteenth century. Prior to Jones and Laughlin leasing the facilities built by the Defence Plant Corporation, several companies tried to mine the ore body but gave it up as uneconomical. While there is a little high grade (40%) magnetite, most of the ore contains 20 to 25% iron and not enough was known prior to World War II to design a profitable operation. By 1943, and certainly in the years that followed, technological developments in ore dressing and mining not only put the magnetite into the category of a commercial ore, but made possible the concentration of the non-magnetic iron mineral, martite. This last development nearly doubled the ore reserve. Jones and Laughlin bought the DPC holdings in 1946 and has since expanded the plant to its present capacity of 4,400 gross tons of concentrates daily or 1,600,000 gross tons per year. Magnetite makes up 62% of this production at the present time, but it will be necessary before long to bring martite production up to about 45% of the total because of the ratio of the two ores in the reserves. To keep the plant supplied, 14,000 to 15,000 tons must be mined and crushed daily, with a ratio of concentration that varies from 2.8 to 3.4. The ore body is 12,000 feet long and varies in width from 600 to 1,500 feet. The waste rock is, for the most part, a granite gneiss, and the overburden, of which little is left, is a glacial drift sand. For the entire reserve, there is a half ton of rock for every ton of concentrate, but the stripping ratio is more than one to one at present because of the existence of more rock in the upper mining levels in relation to the ore. The dirt stripping or development work that cannot be handled by company facilities is contracted to an outside firm. The need for this diminishes every year and will soon disappear. The deposit looks like a "J" in plan, with the long leg running approximately north and south and the short leg to the west. The primary crushing plant, consisting of a 54" gyratory followed by two 18" gyratories and a 1,500 foot conveyor belt to the fine crushers, is located on the third level where the long and short leg of the mine meet. The widest part of the pit lies just the north of the crusher. The mine is operated on a lease that expires in 199l0 There are two fee owners, the Benson Iron Company, which owns slightly overhlf of the reserves, and the Newton Falls Paper Company, which owns the balance. There is no appreciable difference in the mining on the two fees, so the ore is removed in strict proportion to calculated reserves during each year. Basic mining equipment consists of eight 45 yard electric shovels, a fleet of twenty-five 22 ton end dump trucks, eleven churn drills for nine inch blast holes, and two small percussion drills for four to five inch holes, There are the normal auxiliary items, such as dozers, graders, wagon drills, and two drop-ball cranes. Power is purchased and, where practical, is used at 4100 volts. Pit drainage pumps can handle a maximum of 11,500 GPM from the several sumps, but water is a problem only during the spring or when a sudden thaw follows a heavy snowfall.

Jan 1, 1958

By Daniel Maine

Swelling clay soils have been problematic to many types of infrastructure in the United States. However, their impact on underground construction is often misunderstood. The use of swell pressures in design of initial tunnel and shaft support lacks proper guidance and is often mis-interpreted. This paper provides insight and guidance on how to implement a geotechnical investigation program to determine if swelling soil exists at a site and how it impacts the design of temporary support systems for underground projects. An example is provided for how swell pressures were incorporated into the design of an initial support system for a rib and lagging tunnel system and problems that occurred.

Jun 23, 2024