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By Neil Williams

The brecciated dolostone-hosted (Mississippi Valley-type) and associated shale-hosted stratiform Pb-Zn deposits at McArthur River occur adjacent to a major syndepositional fault, the Emu fault. Base-metal zoning, mineral parageneses, and Pb and stable isotope ratios indicate that both types of deposits formed contemporaneously from metalliferous brines that flowed into the host sediments from the Emu fault. Derivation of brines from underlying evaporitic sediments is suggested. Geochemical evidence indicates that the mechanism of ore formation was sulfate-reduction coupled with oxidation of organic matter. The textural relationships of stratiform sulfide mineralization to diagenetic dolomite concretions, chert blebs, volcanic glass shards, and inter-ore breccia beds, indicate that the reactions proceeded diagenetically within about 100 m of the sediment/water interface.

Jan 1, 1979

Large scale fluid extraction from the Latrobe Group in the Gippsland Basin is occurring as a result of offshore petroleum production and coal mine dewatering in the Latrobe Valley. Groundwater extraction in the Latrobe Valley exceeds recharge and is causing an expanding area of declining hydraulic head in the Latrobe Group, and regional land subsidence which is well documented. Recently the government water sector completed the installation of a network of Latrobe Group monitoring bores in the remainder of the onshore part of the Gippsland Basin. The bores situated along the coastal area show a steady decline in hydraulic head of about 1 m/year which can be attributed mainly to petroleum production.

Jan 1, 1992

By S. K. Kawatra, S. J. Ripke

Bentonite clay is used as a binder for iron ore concentrate pelletization. Bentonites are sensitive to cations such as calcium, magnesium, sodium, and potassium that are known to be dissolved in the moisture remaining in the iron ore concentrate. These cations affect the ability of bentonite to absorb water, as measured by the plate water absorbance (PWA) test. This paper addresses the relationships between plant water chemistry and pellet strength for a wide PWA range of bentonites. Experiments were conducted to determine the effect of concentrate moisture solute chemistry and bentonite PWA value on the wet knock and wet and dry compressive strengths of iron ore pellets. Experiments used seven different types of bentonite that had PWA values ranging from 564 to 1033. Flushing plant concentrate with distilled water to remove the dissolved cations resulted in increased pellet strengths, to a widely varying degree, for each bentonite tested; wet knock values increased an average of 92% and dry compressive strength increased an average of 46%. In addition, pellet strengths were not found to be directly related to the ability of bentonite to absorb distilled water, measured by the PWA test.

Jan 1, 2002

Rio Tinto has embarked on a journey to use automation to improve the performance of its surface mines. The driver for automation is to improve the accuracy and consistency of mining processes and less to do with cost savings through labour reduction. A key task in most surface mines is blasthole drilling. The degree to how well this is done cascades through the downstream mining process. It impacts scheduling, excavation, slope stability, material handling, beneficiation and final product blending. Improved blasthole drilling was identified as an objective that has a significant business case in most of Rio Tinto's surface mines. This paper describes Rio Tinto's drill enhancement project that has developed a robust system for automating most of the functions on a Terex SKSS16 drill rig. Automated drilling is currently being used in production at the West Angelas iron ore mine in the Pilbara region of Western Australia. A description of the essential elements of the drill automation system is given together with an overview of how automated drilling is performed remotely from the mine office. A review of some of the benefits of the enhanced drill system is given together with the future plans to extend the functionality of the automated drill and the expected benefits.

May 1, 2010

By R. R. Klimpel

The industrial processing of ores containing precious metals such as gold is generally very mining site specific, e. g. McQuiston and Shoemaker (1985), vanZyl et. a1. (1988), Fuerstenau and Hendrix (1990), and Hausen et. a1. (1990). The variety of various mineral processing techniques employed is extensive and includes size reduction, size classification, gravity separation, roasting, cyanidation, chemical and/or bacterial leaching, ion exchange and/or solvent extraction, and froth flotation. Gold occurs in the earth's crust on the average in very low concentration estimated by various sources to be between two and five parts per billion. For a specific ore deposit to be considered as an economic source of gold, generally a concentration of near one part-per million (one gram / Mton) or more is required. From a mineralogical viewpoint, gold often occurs in its native or free form. However, it can also occur as gold compounds of telluride, antimony, and selenium contained within either sulfide minerals such as pyrite, arsenopyrite. and pyrrhotite or, to a less extent, within silicate, oxide, and carbonate minerals. In many locations, alloying of gold with silver is found. The optimal processing method for recovering gold is determined by many factors such as the mineralogy of the gold bearing minerals as well as the associated mineralogy of the gangue minerals, the type of liberation profile of the gold bearing minerals upon' size reduction, and the particle size of the gold itself. Free or native gold particles can vary in size from the extreme of large nuggets to very finely disseminated gold associated in a complex sulfide mineral matrix. Typically free gold particles of several hundred microns or larger are efficiently recovered by one or more of a number of gravity based techniques due to the large specific gravity differential of gold (19.3 to 15) versus typical gangue minerals (5 to 2.7). When gold is associated with a sulfide (usually pyrite) matrix, historically most industrial plants involving size reduction and subsequent liberation have operated in a size range of 50 to 80 percent less than 75 microns. Grinding finer than this has been normally not economical unless the ore has a high gold content in the feed ore.

Jan 1, 1998

By N. de Koker, Y Jooste, J. Gerber

This paper presents a novel application of the boundary element method for numerical modelling of the seismic activity and hazard that is associated with the shaft pillar extraction at Bambanani mine in South Africa. In the numerical model, the tabular mining excavations are represented by displacement discontinuity elements, and to accommodate crush, shear, and fault slip seismic events, the numerical model is populated with additional displacement discontinuity elements that represent modelled crush- and shear-type failures in the rockmass. Crush-type failures are evaluated by applying the limit equilibrium method and a Hoek-Brown strength criterion, and shear-type failures are evaluated by applying a Coulomb-friction strength criteria to Ortleppshear and geological features. In this paper, the modelling results are presented as time history analyses of modelled potency from 1 January 2010 to 30 June 2022 and normalised exceedance rates for different mining periods using an upper-truncated power law. The normalised exceedance rates of seismic events that have moment magnitude Mw ≥ 1.0 are lowest for the initial mining period (26 events per year) and highest for the final mining period (218 events per year). The relative errors of the modelled potency and normalised exceedance rates are typically less than 10% or 15%, which suggests that the modelling methodology is appropriate for medium- and longer-term forecasting of seismic activity and hazard, as presented in this paper. Shorter-term forecasting is not considered in this paper.

Nov 24, 2025

By D. Harrington, W. J. Fene, H. B. Humphrey

In the fiscal years 1946 and 1947 the number of mine explosions decreased compared with the preceding years. However, the loss of life was so serious during the fiscal year 1947 the period when the Government administered bi- tuminous-coal and lignite mines that from April to June 1947 extraordinary measures were taken in mines then under Government possession to obtain com- pliance with provisions concerning rock dusting, ventilation, and blasting that had not been followed. The great loss of life in explosions during the fiscal year 1947 as compared with 1944, 1945, and 1946 is not easy to explain, but the necessity for maintaining adequate protection has been definitely demonstrated. Management, workers, and inspection agencies alike must keep the mines reasonably safe against explosions or allow them to lapse into a condition where chance is the principal protection against disaster. The at- tention given to protecting coal mines and the men employed in them against mine fires, following the disastrous fires in 1944 and 1945, has at least tem- porarily controlled this hazard loss of life from coal-mine fires was re- duced to 1 fatality in 1947. The number of fires was also less, and progress has been made in reducing the heavy losses in both life and property from un- derground coal-mine fires that occurred in the two years mentioned. Fatalities from mine explosions during the past 6 fiscal years, July 1942 to June 1947, totaled 674, and there were 149 explosions; during the preceding 6 years there were 655 fatalities in 132 explosions. The 6 fiscal years 1942- 47 cover the active period of Federal coal-mine inspection. During the fiscal year 1947, there were 154 fatalities from explosions compared with 58 during the fiscal year 1946, 64 in 1945, 94 in 1944, 152 in 1943, and 152 in 1942.

May 1, 1948

By S. K. Sharma, ANKUSH GALAV, G. S. P. Singh

Providing a suitable protective water barrier pillar (PWBP) is common to reduce inundation hazards in underground coal mines. The imperative factors influencing its performance include the water head acting on the pillar, cover depth, pillar width, strength properties, and permeability characteristics. The mechanical failure of such pillar is a stress-controlled phenomenon, whereas the hydraulic failure is a strain-based phenomenon. A finite-difference numerical modeling approach was developed to study the hydro-mechanical coupled behavior of protective water barrier pillars. The mechanical stability was evaluated in terms of the percentage of failed (ZoF) and intact zones. The influence of the strain-controlled weakening on the permeability of the flow medium was studied through the coupling of the mechanical and hydraulic effects. The coupled steady-state model was used to estimate the outflow rate and its hydraulic stability. The adequacy of the protective pillar was also investigated by assessing mechanical stability and capability to resist hydraulic pressure against the maximum expected water head. A seepage rate-based classification system has also been proposed to evaluate the seepage potential and assess the hydraulic stability. The model has been validated for two case studies at the cover depth of 136–189.5 m and the existing pillar width of 16–42 m against the water head of 25–141 m.

Aug 18, 2022

By T. Bhambhani, D. R. Nagaraj

"Ultramafic Ni ores present significant challenges in processing in that both recoveries and grades are not satisfactory, due to the presence of Mg silicates in large amounts. Significant quantities of xanthates and CMCs are generally used for their recovery by flotation. Additionally, given that some of these ores are processed under acidic conditions, CS2 generation due to xanthate decomposition presents some safety hazards. Technology to replace xanthate has been developed for which the safety and health issues are absent. Collector S-10294 shows significant improvements in Ni and overall S recovery at a dosing rate of one half that of xanthate. New polymeric modifiers have also been developed that help reduce the Mg content of the concentrates at very low dosages. The reagents are custom designed for use in normal or hypersaline water, and acid or alkaline conditions.INTRODUCTION The use of xanthates in sulfide mineral flotation is reported to have started as early as 1925 (Nagaraj 2005). The reagent is now ubiquitous in the mining industry, accounting for 40-50% of total collector consumption. In recent years, the development of more selective reagents has rendered xanthates largely obsolete in Cu flotation. However, xanthates continue to be sold in large amounts in the Au, PGM and Ni flotation industry, where bulk sulfide flotation is required. The low cost and easy availability is the largest driver for the use of xanthates in the minerals industry. Of particular interest to this study is the use of xanthates in the flotation of Ni sulfide ores. About 60% of the world’s annual nickel output is obtained from sulfide Ni ores (Hoatson, 2006). A strategically important category of these ores is the ultramafic hosted sulfides, such as those of Western Australia and Canada. These ores are characterized by low Ni grades (<1%), with the Ni minerals being pentlandite, violarite, millerite and mackinawite, and gangue minerals comprising an array of altered Mg silicates, mostly serpentines. The challenges associated with treating these ores are well documented (Eltham et al. 1973; Claridge et al. 1975). One challenge is that Ni recoveries from these ores are lower. This has been attributed to the increased pulp viscosity, as discussed in detail by Vasudevan et al., 2010. Additionally, Mg silicates tend to report to the concentrate in large quantities, which is problematic for two reasons: a) concentrate dilution, and b) the high melting point of Mg silicates tends accelerate wear on the refractory lining of smelters. This has been attributed to network transport to the froth phase via bubble flux and entrainment (Patra et al, 2010)."

Jan 1, 2012

By G. W. Jones

As part of its program for the promotion of safety, the Bureau of Mines has investigated various means of mitigating or eliminating the explosion hazards of combustible gases and vapors found in the mining and other industries. Knowledge as to the explosive characteristics of cyclopropane in air, oxygen, and other gaseous mixtures is of both theoretical and practical importance because cyclopropane is now used extensively in anesthesia. As such an agent it has many desirable characteristics, and increased consumption of this gas may be expected if the explosion hazards now attending its use can be minimized or eliminated. The present practice of using mixtures of approximately 20 percent cyclopropane and SO percent oxygen should be discouraged because such mixtures are violently explosive and have led to fatal accidents.

Jan 1, 1940

By Kim B. Shedd

The U.S. Bureau of Mines Particulate Mineralogy Unit examined the habits of six zeolite minerals commonly occurring in domestic zeolite deposits. Mineral habit is of interest because current theory on the potential for sarcoma production in test animals emphasizes the size and shape of mineral particles, without regard to composition or structure. A scanning electron microscopic study revealed that, of these six minerals, only mordenite and erionite crystallized in acicular to fibrous habits, The fibrous varieties of these two minerals were characterized by size and shape on the transmission electron microscope, and their dimensions were compared with those of asbestos and amphibole cleavage fragments. When comminuted, these two minerals possess "fibrosity indices" similar to those of amphibole cleavage fragments. One sample, a rare woolly erionite, has uniform widths, large aspect ratios, and a "fibrosity index" similar to those of asbestos.

Jan 1, 1982

By G. W. Jones

As part of its program for the promotion of safety, the Bureau of Mines has investigated various means of mitigating or eliminating the explosion hazards of combustible gases and vapors found in the mining and other industries. Knowledge as to the explosive characteristics of cyclopropane in air, oxygen, and other gaseous mixtures is of both theoretical and practical importance because cyclopropane is now used extensively in anesthesia. As such an agent it has many desirable characteristics, and increased consumption of this gas may be expected if the explosion hazards now attending its use can be minimized or eliminated. The present practice of using mixtures of approximately 20 percent cyclopropane and 80 percent oxygen should be discouraged because such mixtures are violently explosive and have led ,to fatal accidents.

Jan 1, 1940

By John V. Simmons, Peter J. Simpson

Excavated slopes in open pit coal mines are designed to be as steep as possible consistent with stability and safety requirements. Slope failures occur for many reasons, including oversteepening. This paper is concerned with slope design and excavation experience in the Bowen Basin coalfields of central Queensland (Figure 1), [ ]

Jan 1, 2006

By A. E. Seaton

In this paper it will be my endeavor to trace the development of the marine engine and its appurtenances, and the general progress that has taken place in marine engineering generally during the past fifteen years, rather with the object of attributing much of it to the successful efforts of the makers of iron and steel, thereby rendering my thanks to them for the valuable service they have contributed to my profession, than to recount what has been achieved by the skill, ability and perseverance of my colleagues in shipbuilding and engineering. The engineer has been at all times dependent on the ironmaster, and on more than one occasion his progress has been barred by the inability of the latter to overcome some obstacle to success in his manufacture. But on the other hand, it is equally true that the ironmaster has often been ahead of the engineer, and has been prepared, long beforehand, to supply that which would make a success for the marine engineer if he would avail himself of it.

Jan 1, 1891

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least-radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By K. G. Wheeland, J. E. Dutrizac, M. Wasserlauf, A. A. Condy

Numerous processes for the treatment of thiosalts in base metal milling effluents have been examined in the past decade. Flowsheets for thirteen processes are outlined, and cost estimates are presented for a base case of a 720 mi/h effluent flow containing 1400 mg/L thiosalts. The processes are ranked on the basis of Numerous processes for the treatment of thiosalts in base metal milling effluents have been examined in the past decade. Flowsheets for thirteen processes are outlined, and cost estimates are presented for a base case of a 720 mi/h effluent flow containing 1400 mg/L thiosalts. The processes are ranked on the basis of

Jan 1, 1988

By P. N. Anyalebechi

Keywords: Aluminum alloy 3004, Solidification rate, Homogenization, Second phase particles The effects of the fineness of as-solidified cast microstructure and temperature on the response of aluminum alloy 3004 to homogenization heat treatment (a.k.a. preheat) have been investigated. The study was conducted at 538oC and 595oC on directionally solidified laboratory-size ingots with a range of solidification rate of 0.10oC/s to 29.4oC/s. Optical and electron microscopy, quantitative image analysis, electrical conductivity, and electron probe microanalysis were used to quantify the effects of the homogenization heat treatment on the microstructure of aluminum alloy 3004. In general, increase in fineness of as-cast microstructure and homogenization temperature enhances the a-transformation reaction, dissolution of Mg2Si, elimination of dendritic microsegregation, and dispersoid formation. The homogenization heat treatment reduces the average size of second phase particles in castings solidified at <1oC/s. However, in castings solidified at above 1oC /s, homogenization causes the coarsening of the second phase particles. Mn in solid solution is independent of homogenization heat treatment temperature.

Jan 1, 2005

By M. Feely, W. G. O'Keefe, C. O'Reilly, M. P. Holdstock

A petrographic and microthermometric study of fluid inclusions in the Kentstown Granite, crosscutting quartz (VI) and calcite+quartz (V 2) veins in the granite and calcite+quartz (V 2) veins in the overlying sediments was performed on samples taken from the borehole. Comparisons of the type 1, type 2 and type 3 fluid inclusion populations recorded in the present study with those from other Irish Caledonian granites strongly suggest a similar fluid evolutionary history. Furthermore, the low-temperature CaC12-rich brines (type 5) of this study, which must be syn- to post-Lower Carboniferous in age, have correlatives both in Irish Caledonian granites and in the Lower Carboniferous base-metal deposits of the Irish midlands

Jun 19, 1905

By Francis Foley

INTRODUCTION DURING the summer of 1919, the late Dr. Henry M. Howe, then Chairman of the Division of Engineering of the National Research Council, organized a committee to obtain a better insight into the behavior of carbon steels under the influence of various treatments by a proper control of the time and temperature factors. During part of 1919 and 1920, work in connection with this investigation was carried on at Dr: Howe&apos;s laboratory at Bedford Hills, N. Y. During 1921 there was an enforced hiatus in the work, occasioned by the illness which resulted in Dr. Howe&apos;s death in 1922. At that time one of the present authors compiled the results of the work which had been done and this was published in 1923.1 Following the publication of this work, it seemed desirable to carry on in the same manner an investigation of steel of C 0.75 per cent., which steel had not been as fully treated as had the other steels of C 0.34 and 0.52 per cent., used in the published work. Furthermore, certain unusual results have been obtained in the treatment of C 0.52 per cent. steel by quenching and drawing, and repetition of this part of the work seemed advisable. This has been done during the past year at the School of Mines and Metallurgy of the University of Missouri at Rolla, Mo., by a cooperative undertaking of the School and the Bureau of Mines, working in conjunction with the Committee on Heat Treatment of Carbon Steels of the National Research Council. The present paper is a report of the results obtained in this work.

Jan 2, 1926

By I. D. Nock, R. M. Parkin

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993 (original title: Knowledge-based condition monitoring of cone crushers). A large proportion of the electricity used by the quarrying industry is consumed in the comminution and sizing process. In most cases aggregate processing plants operate with minimum control features resulting in limited operational efficiency. Improved control is required to increase operational efficiency with concomitant savings associated with reduction in re-circulating load and improved resource utilisation. Development work has suggested that a combination of adaptive control and process condition monitoring could improve control of comminution plants. Many commercial process control and condition monitoring systems are available, but none were deemed suitable due to the domain specific characteristics of the application. An assessment of the particular characteristics of cone crushing concluded that the application was best suited to the use of small domain specific process control combined with bespoke condition monitoring. The processing power of the control system for the project is a function not of the academic requirement, but rather the economic and practical constraints imposed by the application. As a result of the constraints a high-end PC system has been designed in preference to a workstation. Within the research project work packages are sub-divided into novel wear sensor development, knowledge based control/condition monitoring and the investigation and mathematical modelling of the wear mechanisms inherent in cone crushing. Numerous strategies were considered to implement the control system outlined. The system currently under development is a modular design which utilises intelligent novel sensors to provide a variety of data inputs

Apr 1, 1994