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Cost accounting information is used primarily for (1) planning, control, and performance evaluation; and (2) managerial decision-making. Incremental analysis is a tool for managerial decision-making. It is designed to estimate future financial performance, namely the benefits and costs associated with alternative courses of action. Decisions may be distinguished as pertaining to short-term or long-term activities. Long-term activities frequently focus on capacity decisions and the attendant capital budgeting processes used to quantify the financial effects of these decisions. Short-term decisions typically address short-range production quantity and pricing issues, outsourcing, selection of the optimal mix of products, inventory management, and the acceptance of special orders. This chapter addresses these short-term decisions.

Jan 1, 1999

By T. J. Crebs

The latest estimates compiled by the Society of Exploration Geophysicists again indicate a moderate increase in mining geophysical activity in 1980 over the 1979 level. While North American activity remained at above the 1979 level, a considerable increase in mining geophysics was reported in South America, Australia, and the Far East. The total worldwide expenditures for mining geophysics were reported to be $53.7 million in 1980, compared to $44.4 million in 1979, and $31.6 million in 1978. During 1980, approximately 2% of all dollars spent on geophysics were attributed to mining geophysical activities; this percentage has remained relatively constant in recent years. Airborne surveys accounted for 51% of the total worldwide mining geophysical expenditure, 43% was spent for land surveys, and 6% for borehole surveys. Within the US, the breakdown of expenditures for land surveys was 60% for elec¬trical methods, 23% for gravity and magnetic methods, and 17% for seismic techniques. Electrical techniques remain the primary exploration tool for US mining geophysicists. Electrical Methods With inductive or electromagnetic (EM) techniques, significant developments were achieved in both frequency-domain and time-domain systems. Work continued on increasing the signal level on most time-domain (TEM) methods, to increase the exploration depth. The Crone group increased the power of its Pulse ElectroMagnetic system (PEM) to a 20-amp transmitter-loop capability. The GEOEX group is modifying the SIROTEM II system to obtain larger transmitter amperage from a portable motor generator. Geonics developed a new digital recording system (data logger) for its EM-37 system. This development should increase the productivity of EM-37 crews. A new ground, frequency-domain EM system was developed by the Scintrex group. This novel Genie system does not require a wire link between the receiver and transmitter. Because an amplitude-ratio is measured, the Genie data are reported to be relatively insensitive to coil orientation and distance errors. This new technique does not need extensive line-cutting or accurate station-chaining and would appear to be a good reconnaissance instrument. Scintrex also began marketing the new IPR-11 induced polarization spectral receiver. This receiver is microprocessor controlled, and can output to a cassette tape and record 10 windows of secondary voltage decay simultaneously from up to six receiver dipoles. The Phoenix group's new 100 kW induced polarization/resistivity (IP/R) transmitter began tests using their IPV-3 multifrequency, multichannel receiver. While this unit was primarily developed for "oilfield" IP exploration research, it has obvious application to "deep" mineral exploration. The Phoenix group also developed a new remote-reference, real-time magneto-telluric (MT) device in 1981. This five-component MT sys¬tem has a frequency range from 0.0005-384 Hz. Helicopter-borne electromagnetic (HEM) developments also continued in 1981. The mining in¬dustry increased its use of the new Geonics EM-33-3 multifrequency, multicoil instrument. In 1981, the Dighem group developed software for estimating magnetite as a mapping parameter from its HEM system. Dighem's work is said to complement airborne magnetic intensity surveys, since the HEM estimate is independent of remanent magnetism and magnetic latitude effects. Gravity and Magnetic Methods Probably one of the most innovative techniques in geophysics in 1981 was the use of airborne gravity surveys for both mining and petroleum exploration. The Carson group is using a modified, shipborne LaCoste-Romberg platform in helicopters. Data accuracies to 0.5 milligal have been achieved by flying gridded surveys. Although this airborne method is expensive-up to $186/ km ($300/line-mile)-the geophysical community has been excited by initial results. On the ground, the portable proton-precession magnetometers are becoming sophisticated. Both GeoMetrics and EDA recently introduced field magnetometers having data storage and processing capabilities. This development should greatly increase the productivity of ground-magnetic surveys. Seismic Methods Development of high-resolution seismic techniques continued in 1981. These techniques have primarily been directed toward coal studies for fault detection. OYO Instruments introduced their McSEIS-1500 seismic data acquisition system in 1981. This device contains a 24-channel recording capability, with digital output to 256-kbyte floppy disks. The high-speed data transfer using the disk media is considered a desirable feature. Borehole Methods The general decrease in uranium exploration, where borehole logging is extensively used, probbly led to the overall decline of geophysical logging activity in the minerals industry. However, a number of new sondes and logging systems were introduced in 1981: • Mount Sopris recently introduced their Series III logging system. This microprocessor-controlled unit records up to four channels of data on nine-track or cassette magnetic tape. The logging package is relatively light-weight, so helicopter transport to mountainous or roadless exploration sites is possible. (Both the Edcon and Woodware-Clyde consulting groups offer "slinging" capabilities for their Mount Sopris units.) Mount Sopris is continuing work on their 500-mm-diam (2¬in-diam) spectral gamma-ray sonde. This tool is expected to be available soon. • Owl Technical "slim-downed" its successful digital deviation probe to 380-mm (1.5-in) outside diameter. This new sonde will also measure inclinations up to 80° from the vertical, as compared with its older instrument that could measure inclinations to 30°. • A magnetic susceptibility sonde was introduced in the US by the OYO Instruments group. This Kappalog sonde contains two aircored coils for measurements slightly affected by thermal changes within the borehole. The increased activity in massive-sulfide exploration and the need to "look" deeper no

Jan 5, 1982

By Timothy G. Shuttleworth

In the late1970s, mineral processing plants producing copper sulfide concentrates and oxide leaching feedstocks went online with operating tonnages that exceeded traditional installations. This created a need for larger capacity belt conveyors and apron feeders. Apron feeders are slow moving, heavily loaded conveyors that feed a deep bed of ore from a bulk holding location (a bunker) as a controlled stream, often into a large capacity crusher. Apron feeders use sprockets and caterpillars, while belt feeders use rubber belts with motorized head pulleys to convey the material. The damaging of belts and clogging of transfer points from tramp iron required larger magnetic separators and the removal of tramp metal cannot prevent these serious problems. Corrective action at this location is important for two reasons: Removing tramp iron early in the ore stream protects downstream equipment from potential costly damage. Installing apron feeder magnets before the primary large capacity crusher means that secondary and tertiary crushing steps (made up of multiple parallel units) operate more efficiently, since tramp metal is removed at the onset.

Jan 1, 2011

Jurist, educator and historian Neil Reynolds will be the keynote speaker at the National Mining Hall of Fame's 11th annual induction banquet on Sunday, Oct. 11,1998 at the Pointe Hilton Resort in Phoenix, AZ. Reynolds is Municipal Court Judge for the City of Leadville, CO, home of the National Mining Hall of Fame & Museum, and a fifth-generation resident of the community. His family staked mining claims on nearby Mount Massive in 1862. Judge Reynolds is a fulltime faculty member at Colorado Mountain College, Chairman of the Lake County Historic Preservation Advisory Board and practices law in Leadville. In announcing the speaker, Board Chairman Richard Moolick said seven inductees into the National Mining Hall of Fame will join 138 mining greats previously honored in the annual ceremonies. This year's inductees will be enshrined by Thomas Falkie, president and chief executive officer of Berwind Natural Resources of Philadelphia, PA. Moolick also announced that Jeffrey Clevenger will be the master of ceremonies for the induction banquet. Clevenger is executive vice president of Cyprus Amax Minerals, Englewood, CO and president of Cyprus Climax Metals, Tempe, AZ. A cocktail reception at 6:30 p.m. will precede the black-tie (optional) dinner, to begin at 7:30 p.m. For additional information, contact Esther Mellott at 719 486 1229. Here are the biographies, then, of this year's seven inductees to the National Mining Hall of Fame & Museum.

Jan 1, 1998

By R. C. Timberlake

An understanding of the Florida Phosphate Industry, the mining practices and extraction processes and the historical development of the Industry, is essential to any consideration of reclamation. In the earliest days of the Industry, phosphate rock was produced by screening the phosphate pebble from the matrix. The waste, which consisted of overburden, clay, sand and fine phosphate, and was called "debris", was disposed of onto, either the adjacent surface area, or into mined-out pits. Since the Central Florida area was sparsely settled in those early days, there was no complaint from residents about contamination of streams or the resulting spoil piles - environmental concerns were non-existent. The development of the flotation process in the 1930's and the implementation of the flotation process in the early 1940's was a significant technological breakthrough in the Industry. This technique made possible the extraction of fine phosphate particles, and doubled the recovery of phosphate values from the matrix. However, the implementation of the flotation process produced a new waste disposal problem.

Jan 1, 1978

By A. E. Halim, J. F. Brune

Debate continues over whether barricading in refuge chambers is a good strategy to survive entrapment emergencies in underground coal mines, in particular fires and explosions. Unlike U.S. coal mines, Australian coal mines are not required to use refuge chambers and, instead, have adopted a strategy that focuses on instructing and training miners to self-escape to the surface. This paper analyzes the merits and problems of using refuge chambers or self-escape to the surface to manage emergencies in fires or explosions in an underground coal mine. We found that using refuge chambers may not be the best strategy during extensive fires or when multiple explosions occur. In these situations, mine rescuers are unlikely to be able to extract miners who are sheltered in chambers and, conversely, self-escape may save more lives than sheltering. Chances for successful self-escape are further improved by regular, externally assessed training such as the level 1 emergency exercises required in Queensland, Australia. These exercises put pressure on mine operators to ensure and maintain the effectiveness of their emergency management system.

By M. J. Oliver, A. J. Nugent

Hydrogen Peroxide and Caro's Acid (H2so5) were used to treat cyanide containjng effluents. Significant reagent savings were achieved by using Caro's Acid. Weak Acid Dissociable (W.A.D.) cyanides were removed at near stoichiometric levels of Caro's Acid. Hydrogen Peroxide showed poorer efficiency in the presence of W.A.D. cyanide complexes, resulting in higher consumption rates. By using Caro's Acid, reaction catalyst requirements ar(! el.iminatnd, react.ion I.imes significant.I y rnduced and capita] costs for an effluent lreal.ment facility are minimal. The Efflox* Process ut ilisc�s this more efficienl oxidising reagent in a treatment system exhibiting a simple non proprietary control system with minimal peroxygen consumptions.

Jan 1, 1991

By A. Spearing

According to a 2000 NIOSH report, about 100 million rock anchors are installed annually in coal mines in the USA. Most coal mines have conditions that are conducive to corrosion of the rock anchor and ancillaries (such as plates), yet the effect of this on the performance of the anchors has not been adequately researched and its effects are not understood or quantified in the USA. There is considerable research into corrosion in civil engineering applications on surface and underground but the corrosion of coal mine rock anchors is not necessarily the same because: ? In underground civil structures, water ingress is usually stopped as part of the construction process. ? Many rock bolts in mines are only partially resin grouted leaving part of the reinforcing member exposed to corrosive conditions. All cable bolts in coal mines are only partially resin grouted. ? Even when mine bolts are fully grouted, shrinkage cracks occur and the rock stresses can change due to adjacent mining that can cause the resin column around the bolt to fracture further under external shear or tensile stresses. Most coal mines therefore have ideal conditions for bolt corrosion.

Jan 1, 2010

By J. M. Scharer, Bruce E. Halbert, Lysane Bouduc, Douglas B. Chambers, Jennifer L. Kirkaldy, Carol M. Pettit

Io contrast to acid mine drainage (AMD), neutral mine drainage (NMD) has not yet received widespread attention. Metal and sulphate concentrations can be elevated and of concern in neutral drainage from waste rock and tailings. In the present paper, metal release in high ionic strength mine drainage at neutral pH is evaluated at several mine sites. Specific factors including oxidation rates, buffering capacity, and hydrology are also addressed and their effect on the production of contaminated NMD from mine wastes is evaluated. Case studies are presented involving current seepage water quality and predictive geochemical modelling to illustrate the possible time frame and magnitude of the contamination.

Jan 1, 2000

By Keith S. Liddell

he selection of mill design parameters to suit the applica­tion requirements can result in quite different operating parame­ters for each generic type of application, even though the basic mechanical layout of the mills may remain similar. The selection of the type and size of grinding media is very important to efficient and cost-effective operation, and to ensuring that the milled product achieves the required properties. Accordingly, the grinding media selection is seen as an integral part of the mill design. Consideration of the requirement for classification is important in order to achieve the optimum mill and circuit performance. This can lead to the circuit feed not being classified for a steady feed with minimal slimes and a low size reduction ratio. Feed containing on-size particles would be deslimed by open circuit classification. Closed circuit classification is performed where the feed fluctuates. The rheological characteris­tics of the circuit feed slurry can have an influence on mill performance, and needs to be allowed for. A common misconception frequently encountered is the belief that "a mill is just a mill". This is not the case with stirred types of mills, since the operating parameters selected for the mill can have a large effect on the product characteristics. For example, horizontal shaft high speed stirred mills have a com­pletely different grinding action to vertical shaft low to medium speed stirred mills, which results in large differences between the surface area produced at a given product size (Liddell, 1986). Hence, it can be misleading to apply test results or design procedures obtained from one type of mill to other types for scale-up. The Metprotech stirred mill, as applied in the mining and minerals industries, is a low to medium speed vertical shaft mill. The basic design has been discussed previously (Liddell, 1989). Currently, the largest mills that have been manufactured have an installed power of 400 kW. The largest chamber volume at this power is 6000 litres, containing IO t of grinding media. It is intended that the installed power will increase up to lMW as applications requiring larger sizes arise.

Jan 1, 1995

By W. C. Wheeler, G. Suranyi, J. F. Gentleman, J. Muller, R. Kusiak

INTRODUCTION In 1974 two of the present authors reported the results of a pilot study indicating an increase of lung cancer risk in Ontario uranium miners. (Muller, Wheeler, 1973, 1974) The study was based on data contained in a computerized Mining Master File maintained by the Ontario Workmen's Compensation Board that contained information on miners examined in Ontario who had either 60 months of dust exposure in mines or had signs of pneumoconiosis or tuberculosis. Including the above conditions the definition of uranium miners added the condition of one month or more of uranium mining experience in Ontario. This list of Ontario uranium miners contained 8,649 names. Following the results of this first pilot study, we embarked on creating a file of uranium miners containing information on men with one month or more of uranium mining experience in Ontario without any further conditions. This file was used by the Royal Commission on the Health and Safety of Workers in Mines in their study of risk in Ontario uranium miners. (Hewitt 1976) This file contained 15,094 names. In this report we give an outline and progress report on a study of Ontario miners that we are conducting at present. It was felt that the male population of Ontario is not necessarily an adequate control population for uranium miners. A preliminary examination of the work history of uranium miners indicated that the majority of them (about 90 percent) had other mining experience in addition to their exposure in uranium mines. We therefore considered it useful to evaluate the possible effects of non-uranium mining on risk, and for this reason decided to make the Uranium Miners Study part of a study dealing with the mortality of Ontario miners in general. Aims of the Study The aims of the Study include the evaluation of: 1) the risk of dying by cause in non-uranium miners as compared to the male population of Ontario and Northern Ontario. 2) any differences that might exist in the death experience of non-uranium miners by cause according to ore mined. 3) the effect of length of exposure in non-uranium mines on age-specific risk by cause. 4) the dose-response function for primary cancer of the trachea, bronchus and lung from exposure to radon and its short-lived daughters. 5) the possible effect of the mining environment on deaths from causes other than cancer of the trachea, bronchus and lung. The study will address itself to a number of other factors that might well affect the dose-response function. These include: a) factors in the mine environment - other than radon daughters - that might affect lung cancer mortality. b) the effect of non-uranium mining on lung cancer risk in uranium miners. c) the effect of age as well as age at time of exposure on lung cancer risk. d) questions of latency and the possible dependence of latency on age at time of exposure. e) smoking as an important factor in lung cancer risk. f) Histological type of cancer in relation to the various parameters of exposure and age. MATERIALS AND METHODS The Study is making use of existing computerized data files and has set up certain new files. These include the Mining Master File and the Model Development File. The Mining Master File This file is a computerized record of data on individual miners obtained at yearly miners' examinations that have been carried out since the mid 1920's. The conditions for inclusion in the Mining Master File have been indicated above. Information contained in the file includes: (1) Identifying information: a) Surname and given names b) Date and place of birth c) Miners Certificate Number d) Social Insurance Number if available. (2) Updated Employment data obtained at each miner's examination: a) Year of first dust exposure in Ontario b) Year of first dust exposure outside Ontario c) Number of months worked in mining d) Ores mined e) Mining areas and mines f) Occupations

Jan 1, 1981

By Allan E. Hall

The use of full face boring machines in underground mining has increased considerably in recent years and over 200 raise-boring machines are now in use in the Western World. Several tunnel-boring machines have been tested notably in America, West Germany, Britain and South Africa. A relatively new concept is the blindhole borer, where the machine stands on the lower level and bores a full diameter raise upwards without the use of a pilot hole. Four of these machines have been tested to date in South African quartzites with varying degrees of success. The development of boring technology has created new problems for ventilation engineers and exacerbated several existing ones. This challenge has been met in many varying ways and this paper attempts to provide a review of the current state of the art. Technology and methods are developing at great speed in this field and therefore no final and absolute solutions can be proposed, since each machine and site pose individual problems which are best handled by local knowledge and experience.

Jan 1, 1980

By J. Duran

Mining at Newmont Mining?s Phoenix?s Mine is currently done by surface operation in the Fortitude and Bonanza pits at a combined rate of approximately 100 kt/d (110,000 stpd). A portion of the orebodies targeted by these pits was mined previously by underground mining methods, dating back to the mid-to late-1800s. Most of the underground workings (voids) are located in the west central area of the Bonanza pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This article presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.

By Mustafa Fener, Masoud Rostami, Sair Kahraman, Behnaz Dibavar

The paper introduces a new rock mass cuttability classification (RMCC) system for roadheaders used in coal mines. It includes performance prediction models for both axial and transverse roadheaders, based on six parameters: uniaxial compressive strength, Cerchar abrasivity index, volumetric joint count, strike and dip of joints, joint aperture, and groundwater condition. The study validates the RMCC system through field and laboratory measurements, showing high correlation coefficients between net cutting rates and RMCC indices.

Nov 1, 2023

By MAURICE SUNKPAL, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

In this study, various rib bolting scenarios were investigated to better understand the effectiveness of the support systems. A coal mass constitutive model is implemented to a distinct element method (DEM) code, and rib factor-of-safety (RibFOS) analyses were performed by applying strength reduction for the coal matrix and explicitly modeled face cleats. Ribs with various overburden depths and mining heights composed of solid banded bright coal were considered. Different scenarios such as rib bolt length and number of bolts were studied to quantify the effect of primary rib support density on rib stability. As a result of the unsupported coal rib analyses, a decaying exponential relationship is proposed between the mining height-overburden depth and the RibFOS. The developed coal rib models clearly show the coal-rib bolt interaction and illustrate how the addition of rib bolts restricts the movement of the coal rib. The results reveal that the strength-reduction method in DEM code with the coal-mass model can aid in the development of practical primary sup- port charts, which can help in the rib support design process.

Feb 1, 2024

By K. Rushdi, B. E. Abulnaga

The conventional Froude number is blind to the presence of solids, their density and their concentration in a stream of slurry mixture such as tailings flowing in an open channel. This often leads to rough approximations of subcritical, critical and supercritical regimes, based on one phase flow Froude number, limiting subcritical to a value smaller than 0.8 and supercritical to values above 1.4, as proposed in the past by Green, Abulnaga and other authors. While acceptable for small flows, such approximations can be uneconomical for the larger flows encountered in some modern plants that treat up to half a million t/day. A review of concepts of a densimetric Froude number sheds some light on the effect of solids on stratification prior and subsequent to a hydraulic jump. While the approach is heavily borrowed from modern sedimentology, it provides a useful tool to designers of large launders or open channel tailings systems. These concepts are reviewed with some practical examples.

Jan 1, 2013

By H. Y. Sohn, M. Pérez-Tello, J. Löttiger

An investigation of the oxidation reactions of two industrial copper mattes was performed using dflerential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) at heating rates of 20°C and 8°C/min, respectively. The temperature of incipient reaction, the total exothermic and endothermic heats of reaction and the weight change during the oxidation process were measured as functions of the oxygen concentration in the oxidizing gas, matte grade and matte particle size. The temperatures of incipient reaction measured from the DSC experiments were found to increase monotonically with all three input variables. TGA experiments showed that Cu2O and CuO CuSO4 are formed before the complete oxidation of Cu2S to CuO.

Jan 1, 2000

By G. J. Hartman

A presentation of this project was given previously at the SHE Annual Meeting, Denver Colorado February 23-27, 1987. The project concerns the development of in situ recovery of borate products from a deep-seated colemanite deposit in California. The deposit contains some 147 million tons of borate ore containing 6.4% boron oxide (B2O3). This paper involves the numerous changes in the process that has taken place since that first presentation. This paper further explains the reasons for these changes which are primarily environmentally based and secondarily capital requirements related.

Jan 1, 1994

It is widely accepted that particles stabilize flotation froths and that stable froths result in improved flotation performance. Predicting the effect of particle addition on froth stability is, however, challenging. Furthermore, there is currently no technique that allows the prediction of the effect of different flotation reagents on froth stability, without carrying out froth stability experiments.

By T. Doshi, S. Ennis

The interactions of mineralogy, chemistry and mechanics in an ore concentrator are highly complex, so it can be particularly hard to measure the impact of a specific plant change. This paper describes a method for modeling a baseline metal recovery so that the value of a major process improvement can be measured. This method only considers variables that cannot be optimized, such as mineralogy or equipment availability. Linear regression, random forests, extreme gradient boosting (XGB), and simple two-layer neural network models of process value were tested as candidate baseline model types to assess the impact on throughput and recovery in a copper concentrator. XGB performed the best in terms of accuracy for both throughput and recovery models. Using an XGB model of nonoptimizable process variables provides an accurate, dynamic baseline that can be compared with continuous production data to determine the value added by major concentrator improvements in real time.

Mar 2, 2022