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By J. P. Schmid

Results of a comprehensive investigation of the impact of underground mine waste disposal on the health and safety of miners are presented. Information was gathered through an extensive search of American and foreign literature and personal communication with professionals in private industry and government. All conceivable health and safety hazards directly or indirectly related to underground mine waste disposal are analyzed, catagorized, and ranked on an industry-wide basis. Positive health and safety effects are analyzed and ranked in a similar way. Both potential and known hazards and positive impacts are included. Recommendations on abatement techniques for the various hazards are presented. Case histories of a fill-related accident in a metal mine and a health hazard associated wtih coal waste backfilling are included and causes and possible abatement procedures are discussed. The rule of management in the promotion of health and safety in backfilling operation is discussed.

Jan 1, 1982

By B. S. Terry, C. L. Harris

After measuring the kinetics of Ni reduction from a SiO2-saturated fayalite slag into a Cu-based metallic phase on a laboratory scale, a general model was developed that is capable of simulating mass transfer to and from metal-slag, slag-gas and metal-gas interfaces for multiple species. The model was used to simulate the reactions that occur when Cu and Ni are reduced from fayalite-based slags into a Cu-based metallic phase. Good agreement was achieved between model predictions and experimental data

Aug 1, 1995

By Allan E. Martin

As part of a comprehensive investigation of tie mechanism of desufurization of iron and steel by slags, the Blast Furnace Studies Section, Metallurgical Division, Bureau of Mines, in cooperation with the Institute of Technology-, University of Minnesota, has made a study of the forms in which sulfur occurs in blast-furnace slag. This report presents data on the three sulfides most important in iron smelting, namely, ferrous sulfide, manganous sulfide, and calcium sulfide. The tendency of these sulfides to form colloids in the molten slag was determined by an examination of quenched samples with an ultramicroscope. Vogt5/ conducted experiments on sulfide silicate melts and examined synthetic blast-furnace slags in a partly crystallized condition. His conclusions were that FeS, CaS, and bins, or isomorphous compounds, such as (FexCay)S and (MnxCy)S, were precipitated Prom the melt, depending on the composition of the slag. In all specimens sulfides were visible and were spherical.

Jan 1, 1941

By Steve Kral

Mining is a risky business. The cost of exploring for new mineral deposits is high and the success rate of finding one worthy of development is relatively low. And once a deposit is identified, there is no guarantee that it will become a mine. Mining companies have to spend a lot of time and money on due diligence, prefeasibility and feasibility studies, and sustainable development and environmental issues before deciding whether the deposit will become a profitable mine. And then there are the millions of dollars spent in developing the deposit and building a mine. No wonder the mining industry has trouble attracting investment capital. Companies take a large risk in developing reserves and investors take a similar risk in investing in them. So mining companies must be as accurate as possible in determining mineralization that makes it to reserve status. After all, reserves are a company’s most important asset and one of the critical factors analysts and funding sources look at when determining if a mine or mining company is worth the risk.

Jan 1, 2003

By B. K. Belle

The beginning of 21st century has heralded the global strategic importance, as evidenced by increase in energy prices and energy generation-emission-utilization dilemmas. In January 2008, the South African energy supplier, ESKOM had tabled the concept of power conservation and acknowledged the energy crisis until 2016. The concept is required of all energy users to reduce their electricity consumption, intensify energy efficiency and cautiously proceed with new projects. The generation of energy results in by-products called ?green house gases? (GHGs). To make a positive response to climate change and their effect on the environment, every energy user must ensure efficient energy use through technical and administrative means referred to generally as energy savings. This paper identifies mine ventilation engineering, in particular the electricity consumed by main fan units, as an area of potential energy savings. For a major mining company, electricity consumed by main ventilation fans alone can be in the order of 120 MW. Although a known fan engineering technique but scantly applied technology identified as the Hermit Crab can be seen as a ?quick win? project, due to its success in other industries such as cement and steel. The ?Hermit Crab? technique® involves upgrading or replacement of an impeller - whatever its origin - with a design impeller to suit the actual ventilation requirements, resulting in increased fan efficiencies. The cash flow benefits associated with a case study and its rollout of this technology have been calculated. For a 10% increase in main fan efficiency, would have a net present benefit of US$ 16.08m over 10 years. With the inclusion of carbon credits, this benefit rises to US$ 29.40m in total. Application of other available technologies, viz., composite materials, ventilation-on-demand and variable speed drives are discussed.

Jan 1, 2009

By M Rafty, A Markham, S Atkinson, M Heyting

Over recent years there has been a significant increase in the number of miners in the Pilbara region of Western Australia targeting channel iron deposits (CID) located in valleys, intersected by ephemeral creeks and below the groundwater table. The falling iron ore price has triggered a drive to reduce cost and maximise yield. Creek diversions provide an opportunity to maximise the utilisation of orebodies and extend the life-of-mine.Creek diversions that are required during mining operations to access ore and provide flood protection have historically been constructed as uniform engineered channels designed primarily for flow conveyance while minimising earthworks costs; however, the design of diversions becomes more complex when they are required to function in a similar way to the existing creek system during operations and remain stable during more extreme events than would typically occur following mine closure, in accordance with current regulatory guidance. The design specifications for closure are often more rigorous than the operational phase, and could incur significant additional cost to implement retrospectively if not planned and designed upfront.The complexity of diversion design depends on site specific factors such as: the size of the creek to be diverted; hydrology; corridor restrictions; geomorphology; hydrogeology; geology; environmental and heritage values; potential impacts and the risk to operations and environment. The complex interactions of these factors must be well understood and hydraulic modelling undertaken to characterise the existing creek system, demonstrate the diversions, provide adequate flood protection during operations, and can function in a similar way to the existing system following mine closure. This paper presents key design considerations for Pilbara creek diversions, operational and closure requirements, mine planning considerations, risks, cost saving opportunities, and the benefits of an integrated approach to design.CITATION:S Atkinson, A Markham, M Rafty and M Heyting, 2017. ‘Back to the future’ – resilience in historical context and implications for the future, in Proceedings Iron Ore 2017, pp 367–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Nicholas R. Dixon

This report summarizes all work performed under Phases I, II and III of U.S. Bureau of Mines Contract H0387006, "Development of a Prototype Retrofit Noise Control Treatment for Jumbo Drills." The noise and vibration levels of four jumbo drills were characterized and a survey of percussive rock drill usage is reported. A Gardner-Denver DH 123 drill was chosen as a demonstration drill, and extensive noise diagnostic studies were performed. Noise control treatments were designed, developed and evaluated in a reverberant drill test facility. The treatments consisted of an integral enclosure/muffler for the drifter, vibration isolation of the drifter from the enclosure and feed, and a drill steel sheath. A 19 dBA reduction in overall sound power level was achieved with no loss in drilling rate. The prototype retrofit treatments were field tested in an aboveground mine and in a production section of an underground zinc mine. Long-term durability and operator acceptance of the enclosure/muffler treatment were excellent. Preliminary evaluation of the drill steel sheath was encouraging, although additional testing is required.

Jan 1, 1982

By D. G. Krige

For the purpose of determining confidence limits for ore grade estimates, an extensive simulated database was used, which included 1728 ore blocks with ?actual? grades and the corresponding estimates based on ordinary and simple kriging. The practical results show that conditional unbiasedness is essential and that acceptable confidence limits can then be set using Normal theory for the simulated error distribution based on the logarithms of the ratios of ?actuals?/estimates with a variance related to the kriging variance. The mean of the data used to prepare the variogram and the estimated block grade are to be used properly in this approach. A practical analysis was also done of the actual point and block data from a very large mined out Carbon Leader area. The distributions of the actual grades for two levels of block sizes with different levels of variability were fitted using three models, ie. two three and compound lognormal. The trends of tonnages, grades and relative profits for a range of pay limits, as well as the usual tonnage-grade curves, show a practical insensitivity for the choice between the three lognormal models considered.

Jan 1, 2004

By H. Maleki

As mining continues toward deeper reserves in thick western US coal fields, the control of mining induced-seismicity has become a priority in many operations in Utah, Colorado, and Wyoming. Gradual floor heave, common in many coal mines, has historically not been a safety issue. However recent occurrences of sudden floor heave accompanied with seismicity in a few deep mines have fueled this investigation. The focus is to identify and study the mechanisms resulting in sudden heaving of the mine floor in western U.S. deep coal mines through analytical calculations and back analyses of an actual event in a cooperative mine. Based on review of available data in three mines, underground observations and back analyses of an actual event, the authors have identified the following contributing factors (1) presence of stiff stratigraphic units and thick seams mined at depths exceeding 1000-ft (2) presence of geological discontinuities reducing the in-situ strength of the coal with calculated factor of safety near 1 for the mine floor (3) mining approaching areas of higher than normal stress gradient associated with previous mining or structural anomalies or surface topographic highs and (4) an additional source of energy triggering sudden failure such as periodic caving or slip along geological discontinuities. Preliminary examination of seismic data for the actual event in the cooperative mine and underground observations excluded fault slip at the mining horizon as the triggering mechanism but highlighted the significance of weak, anisotropic strata conditions near the intersection of two faults.

Jan 1, 2009

The safety analysis of shaft-sinking operations included a review of accident reports from coal and metal-nonmetallic mine shaft-sinking projects in the United States, a review of foreign and domestic shaft laws, and discussions with shaft contractors and Federal mine inspectors. Accident data were studied to identify the most common and the most severe types of shaft accidents and to determine their immediate and contributing causes. Additional factors such as worker training and experience, equipment and sinking procedures, regulations and enforcement practices were also investigated to determine their impact on shaft safety. The results of the study are summarized in recommendations for improved training of shaft miners and clarification of Federal shaft-sinking regulations. A guide to assist mine inspectors in examining shaft-sinking projects is also included.

Jan 1, 1977

By Randy Clarkson

"Free gold particles occur in many base metal and precious metal mines throughout the world. Occasionally mine operators are unaware of the presence of free gold particles in their ores because they have not seen free gold hand specimens or at the working face of the mine.Due to the high density and malleability of gold, large circulating loads of free gold particles can build up over time in grinding circuits. This gold is often deposited in unintended traps throughout the mineral processing system.These unidentified free gold deposits represent a serious security risk as well as inaccessible inventory of gold. Deposits of free gold particles often remain undetected by mine management until they are accidentally discovered while repairing mill equipment. The trapping and subsequent release of gold particles can frustrate attempts to calculate accurate metallurgical balances.Nuclear tracers have been used to determine the free gold recovery efficiency of gravity recovery equipment, drills, and sampling equipment (Clarkson, 1994, 1997, 1998, 1999 and Walsh, 1986, 1992). In 1995, the author used radiotracers to locate and eliminate gold traps at La Mine Doyon (Clarkson, 1997). In 1998 and 2001, the author also salted mineral processing circuits at Royal Oak's Pamour Mine in Timmins (Clarkson, 1999) and at Gold Corp’s Red Lake Mine in Ontario with radioactive gold particles.The gamma and X-ray radiation from gold's nuclear isotope (Au198) were detected through steel, in pipes, and in moving equipment with scintillometers. The radiotracers proved to be a safe, rapid and accurate method of identifying gold traps, improving security, determining the recovery efficiency of Knelson gold concentrators and estimating retention times of gold particles in various processes."

Jan 1, 2003

By M. Dattilo

The U.S. Bureau of Mines has been conducting research on the use of waste-derived zinc as a partial replacement for pure zinc in the electrogalvanizing process. The end product of this process is automotive sheet, which has enhanced cosmetic protection over previously used cold-rolled (CR) steel. In this study, primer-coated specimens of CR and electrogalvanized (EG) steel were subjected to the on-vehicle environment and monitored periodically by electrochemical impedance spectroscopy (EIS) during immersion in 1M NaCI solution. The results of these tests were compared with immersion-only conditions. Scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) techniques were also used to evaluate the corrosion processes and compare them with atmospheric exposure specimens. EIS was found to measure the corrosion associated with on-vehicle exposure, thus providing an excellent screening technique for evaluation of the performance of EG automotive sheet steel.

Jan 1, 1990

By X. Pan

Slag-metal equilibrium experiments were conducted at 1500ºC and 1580ºC under 0.03 atm, 0.05atm and 0.83 atm CO partial pressures using silica and Cr-oxide crucibles. The complex slags belonged to SiO2-CaO-Al2O3-MgO-FeOx-CrOxand the metal phase to the Cr-Fe-C-Si-(S)systems. The carbon saturation of the metal phase was avoided using oxide crucibles and thus the results are pertinent to ferrochromium refining slags and processes. From equilibrium data and thermodynamic calculations the CrO /(CrO+Cr2O3) ratio in the slag was determined as 0.75, 0.80and 0.86 under 0.83 atm and 0.05 atm of CO pressure at 1500ºC and 0.03 atm and CO pressure at1580ºC respectively. The results clearly demonstrated that a higher chromium content of the metal results in higher Cr in the slag, and chromium in slag decreases with increasing SiO2. The results were also sensitive to the crucibles used as these oxide crucibles saturated the slag either with respect to SiO2or Cr-oxides. It was also demonstrated that the relative amount of CrO in the slag was higher when SiO2crucibles were used in accord with thermodynamic calculations. Iso-concentration curves for carbon and chromium of the metal phase in equilibrium with the slag were drawn on pseudo ternary SiO2–(AI2O3+CaO+MgO)–(Cr2O3+Fe2O3) diagram. The activity coefficients and activities of carbon and chromium of the metal phase were also calculated from the experimental data and available thermodynamics information and were plotted as iso-activity curves in the same pseudo ternary diagram. Keywords: Chromium, slag, equilibrium

Jan 1, 2004

By Descour Jozef, Suguru Shirasagi, Takuji Yamamoto, Koji Murakami

For TBM tunneling no visual inspection of excavated ground is possible. This may hinder the high-speed excavation, particularly in complex ground conditions. The TBM Excavation Control System was developed for better prediction of geological conditions ahead of the tunnel face during excavation. The seismic reflector tracing produces volumetric images of anomalies in the ground in “near-real time.” These images are verified using logging data from pilot boring and TBM driving data, to improve reliability and precision of ground mapping. Also good correlation was obtained between the rock strength index computed from TBM data, and one derived from volumetric seismic images.

Jan 1, 2007

By J. A. Botín

Identifying, quantifying and minimizing technical risks associated to investment decisions is a key challenge for the minerals industry decision takers and investors. However, risk analysis in most bankable mine feasibility studies are based on stochastic modelling of project NPV which, in most cases, fail to provide decision makers with a truly comprehensive analysis of risks associated to technical and management uncertainty and, as the result, are of little use for risk management and project optimization. This paper presents a value-chain risk management approach where project risk is evaluated for each step of the project lifecycle, from exploration to mine closure, and risk management is performed as part of a stepwise value added optimization process.

Jan 1, 2011

By T. B. Armstrong

"The developing world energy crisis and spiraling fuel costs have created a new public awareness and general acceptance of the need for energy conservation.Plants will have different objectives for an energy conservation program but there appears to be a common approach on how to save electrical energy.Data for a 180tph Rod Mill powered by a 750 hp motor will be used to demonstrate the relationship of energy input and production levels and to seek an optimum operating condition.Energy Conservation:Plants that have examined ways of dealing with the energy situations have concluded that energy conservation has important benefits for industry, including reduced costs, fewer production slowdowns inthe event of fuel shortages and a continued competitive position.There have been some ""startling"" conservation achievements attained through such simple plant maintenance and operating practices as reducing unnecessary lighting in buildings and yards, turning off' equipment not needed at night or over week-ends, through planning maintenance and production schedules to minimize energy use and through improving quality control to eliminate waste.Significant reducti.ons in energy use have been achieved by some rather simple but vigorous maintenance and plant engineering efforts directed at finding and fixing energy ""leaks"" rather than technological advances or major rework or redesign of facilities and equipment.An Energy Conservation Program often must overcome such obstacles as historic operating practices and emp1-oyee indifference, i.e. the ris.ing costs of fuel should result in re-examination of so1ne basic attitudes to energy conservation. Some measures, rejected in the past largely on the grounds of capj.tal. expenditure, now make economic sense in the light of future escalating energy costs."

Jan 1, 1978

By Thomas C. Wilder

Jan 1, 1965

A genesis based on new developments in the physical chemistry and flow properties of colloidal substances is proposed for the pipe-like Peko orebody. The rheological behaviour of sediments is governed by the contained colloids. Remobilization of thick pasty sediment during diagenesis is regarded as an essential step in the concentration of metal dispersed in sediments. At a high concentration the sediment pore fluid is a dense gelloid such that van der Waals attractive forces between the colloidal particles exceeds the coulombic repulsion. This permits accretion of the colloids into globular clots and their fracture fragments. These have a uniform size distribution dependent upon the rate of shear, and the sediment lithifies to clotted, porphyry-like, "gritty", dolomitic or igneous-looking intrusions and flows. The physical chemical properties of natural sediment colloids appear adequate to account for ore formation.Adsorption accounts for the dispersion and retention of metal in sediments. Accretion accounts for the segregation of the colloidal materials to give the various types of clotted igneous-looking intrusive source rocks. Syneresis enables the colloids to spontaneously draw together and to dehydrate. Formation of an ordered lattice achieves a lower energy state and desorbs metals and insoluble metal compounds "particle by particle" into the escaping water of hydration and pore water. Peptization enables migration of the metal hydrosols as stable dispersions until they merge for outflow through seepage zones or water extrusion channels. Nucleation and concretion precipitate the metal dispersoids from pore waters seeping through hydrous parts of the source rock, porous beds, faults, and zones of weakness by which the connate waters leave the lithifying sediments. Gelatinous precipitated mineral matter in the ore channels is capable of thixotropic reliquefaction when disturbed by shock or movement. Local reintrusion, flowage, interveinings,brecciation, and intermixing of the materials is the result.The principles of the suggested genesis are applicable to both syngenetic and epigenetic mineral accumulations.

Jan 1, 1966

By Deon van Tonder, Bert Van Hege

Comparison of various technologies for uranium recovery from sulphuric acid leach solutions shows that Resin-in-Pulp (RIP) and/or Solvent extraction (SX) based processing routes are usually cost effective (11). A combined RIP-SX recovery-purification route and a CCD-SX recovery-purification route were investigated and optimised. The design basis used for the investigation was a production rate of 200 kg/h U3O8 over a solution concentration range of 40 to 1500 mg/L U3O8. The OPEX for the RIP-SX processing route was found to be sensitive to the variation in uranium concentration in the leach liquor. One of the main drivers for this trend is the leach acid concentration. Conversely, the CAPEX of the CCD-SX processing route was sensitive to the uranium concentration in the leach liquor. The leach acid concentration only affected the OPEX of the CCD-SX processing route modestly, as the bulk of the acid is recovered in a pre-leach circuit. Contrary to expectation, the effect of extractant loss assumptions on the overall processing route economics was found to be modest to insignificant. It should be noted that the CCD-SX processing route OPEX was more sensitive to extractant loss assumptions than the RIP-SX processing route OPEX. Economic optimum wash ratios were determined for the CCD-SX processing route and increased with leach concentration ? the increase in wash ratio was less than proportional. A 5-stage CCD configuration was found optimal over the concentration range investigated.

Jan 1, 2007

The method of investigation was to study the distribution of ore in great detail, to make a thorough structural study of the lode and the mine area, and then to compare the results of the two studies. Such a comparison usually reveals a very close relationship between geological structure and ore distribution, and can often lead to important conclusions which would not be reached in the ordinary working of a mine.The Triton mine lies 30 miles E.N.E. of Cue, or 380 miles N.W. of Kalgoorlie, in typical pre-Cambrian rocks, consisting of gTeenstone lavas and tuft's, interbedded with slates and some sediments, and intruded by granite and porphyry. Fig. 1 (at end of paper) is a longitudinal section of the mine and shows that the workings consist of the main North Emu and the smaller South Emu, separated by a distance of about 1 of a mile. Both orebodies occur on the same lode, which strikes north and south and dips practically vertically. On the same line, and of 1/2 a mile and a mile respectively to the north of the North Emu, are the small Rand and North Rand workings, where a big width of lode material has proved to be very low grade. In the North Emu the lode width averages 12 to 15 feet; it is seldom less than 5 feet and in places reaches 30 feet. In the South Emu the lode is wide, but only portion of it is payable.The lode is a mineralised bed occurring between massive lava flows on the east and a mixed series of tuft's and thin lava flows on the west. The lode material is hard, fine grained, and dark coloured, and generally has a faint banding which is believed to indicate a tuft'aceous origin of the original lode rock. Microscopic examination shows that the original lode rock has undergone considerable albitisation;' there has also been considerable formation of biotite which gives the lode material a characteristic sheen. The mineralisation consists of abundant fine pyrite, which is auriferous, and a lesser development of pyrrhotite which is, however, barren of gold.THE OREBODIES AND THEIR CHARACTERISTICSThe distribution of ore is best studied from gold contours, as these reveal features that cannot be detected in an ordinary assay section. Gold contours (see Fig. 3) are developed' by plotting the width and grade of all development and stoping assays throughout the mine on a longitudinal projection, representing each sample by a coloured dot according to a suitably chosen range of assay values, and then outlining areas of similarly coloured dots (see H. J. C. Conolly, Econ. Geol., April, 1936). Both width and grade must be taken into account and the simplest method of gold contouring is to use dwt.lft. values, but difficulties arise here with big widths of low grade and small widths of high grade ore. To choose an extreme case, 30 ft. of 2 dwts. and 2 ft. of 30 dwts. both equal 60 dwts.lft., and would therefore be given the same value in dwt.lft. contouring...

Jan 1, 1943