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This paper gives an overview of the difficulties associated with determining the strength of hard rock pillars. Although a number of pillar design tools are available, pillar collapses still occur. Recent examples of large scale pillar collapses in South Africa were caused by weak partings which traversed the pillars. Currently two different methods to determine the strength of pillars are used namely, empirical equations derived from the back analyses of failed and stable cases and numerical modelling tools with an appropriate failure criteria. Both techniques have their limitations and additional work is required to obtain a better understanding of pillar strength. Empirical methods are popular and easy to use, but care should be exercise that the results are not extrapolated beyond the range of the data which were used to derive them. An example is the Hedley and Grant formula (derived for the Canadian uranium mines) that has been used for many years in the South African platinum and chrome mines (albeit with some adaptation of the K-value) to design the pillar layouts. Very few collapses have nevertheless been reported and it might even be too conservative an assumption of pillar strength in these mines. As an alternative, some engineers strongly advocate the use of numerical techniques to determine pillar strength. A close examination unfortunately reveals that these techniques also rely on many flawed assumptions. An area where numerical modelling is invaluable, however, is to study specific pillar failure mechanisms, such as the influence of weak partings on pillar strength. In conclusion, it appears that neither empirical techniques nor numerical modelling currently provide a solid basis to conduct pillar design. It is therefore recommended that both these techniques be utilised when confronted with a pillar design to obtain the best possible insight into the problem.

Nov 25, 2010

By F N. Baez

This paper supplements a keynote address prepared for the MassMin 2016 conference on mass underground mining methods, including block, panel, inclined and sublevel caving. It advocates for a new cave mining paradigm that takes advantage of a number of new and disruptive technologies or innovations that have evolved over the last 15 years, some of which were initiated by major mining companies such as Codelco. The paper will address the challenges that the industry will be facing in the future as well as possible solutions. As background, the paper summarises the challenges that the industry has faced in the past and how such challenges were addressed. The author acknowledges that given his more than 30 years of experience with Codelco Chile (operations and corporate), aspects of his intelligent mining concept have no doubt been influenced and have matured during his invaluable time with Codelco also as the Head of Technology and Innovation. In the paper, he uses some of the innovations developed within Codelco and by the Chilean Government to illustrate the concept of ‘intelligent mining’.CITATION:Baez, F N, 2016. ‘Intelligent mining’ – the way of the future, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 3–8 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Ernest W. Hilton

The purpose of this investigation was to assess the environmental impact of the surface mining methods currently used in the steep-sloped areas of Central Appalachia: southern West Virginia, eastern Kentucky, southwestern Virginia and northeastern Tennessee. Comparisons are made between mountaintop/cross ridge mining, contour strip, augering and an innovative method surface shortwall mining which was attempted at Julian, West Virginia. Included in this final report are a discussion and analysis of current Appalachian production, reserves, and the extent of land affected on a county- by-county basis. Additionally, the seams within the steep sloped region have been assessed according to minimal standards of thickness, surrounding lithology, and areal extent to determine their amenability to surface shortwall mining. These seams have been tabulated with their ash, sulfur, and BTU content on a county-by county basis. Only minimal statements are made concerning quantity because of the narrow set of conditions required by the shortwall method. Other sections deal with the possible technical failings of an operational surface shortwall system based on field studies at shortwall operations, discussions with people experienced with shortwalls and research into ground control problems at sites where short- and longwall operations have been monitored. A final section details proposed additional research directions which the Bureau might take in the future.

Jan 1, 1979

By G. A. Bezuidenhout, J. P. T. Kapusta, D. K. Chibwe

"Peirce-Smith converters (PSCs) are extensively used in the copper, nickel, and platinum group metals industries. The typical converting operation involves lateral purging of air into molten matte through a bank of tuyeres. This blowing operation occurs at low pressure from the blowers, resulting in a bubbling regime that is considered inefficient from both a process and an energy utilization perspective. Inherent drawbacks also include recurrent tuyere blockage, tuyere punching, and low oxygen efficiency.Western Platinum embarked on a full-scale industrial evaluation of generating a jetting regime by using sonic injection. Prior to industrialscale tests, a numerical assessment to ascertain the feasibility of implementing sonic injection into a PSC was conducted. The work included flow characterization at high-pressure injection achieving sonic velocity at the tuyere exit. The 2D and 3D simulations of the three-phase system were carried out using the volume of fluid method together with the RKE turbulence model to account for the multiphase and turbulent nature of the flow.This paper discusses the key findings in understanding plume extension, velocity distribution, shear wall stress analysis, and phase distribution characteristics in the system. Plant trials are also discussed with reference to the commercial aspects of a full-scale implementation of sonic injection in the smelter."

Jan 1, 2015

In a previous paper the writer dealt -with the jasper bar formations and their relationship to the structural geology of older pre-Cambrian rocks in the goldfields districts of Western Australia (24). He has pointed out in this ahd other papers that jasper bars, or banded iron formations, banded hematite or ,magnetite quartzites, jaspilites and related banded ferruginous or non-ferruginous cherts, occur in abundan'ce in the Older Greenstone Series of Western Australia (22), (24), (26). They are considered to represent special forms of banded ferruginous sediments, and are usually fpund in the field interbedded with more or less metamorphosed pasaltic 01' andesitic lavas and tuffs, now amphibolites, together with occasional thin bands of normal pelitic sediments, which go to make up a large proportion of the Older Greenstones in thfs State (26).Great thicknesses of fiat-bedded ]:landed ferruginous cherts are also found associated with cherty' carbonate rocks; quartzites, shales and thin-bedded dolomite whicIi constit'ute the Nullagine (Pl'oterozoic) system in the northwest of Western Australia. In the Hamersley Range district these banded ferruginous chert beds are the hosts of important deposits of blue amphibole asbestos.In the paper mentioned above brief reference was> made to the importance, of geological structure in relation to economic geology, particularly in the goldfields regions of Western Australia, and it was shown that jasper bars may have an important role in the study of 'the structural geology of many of these regions. Of possibly more immediate economic importance is the part that these rocks play, both directly and indirectly, as host rocks for mineral deposits-the chief of Which are gold, iron ores, blue asbestos, and manganese ores. The blue asbestos bearing banded iron formations mentioned above are confined to the younger pre-Cambrian Nullagine formations. They have been described in detail elsewhere (23). In this paper it is proposed to discuss the economic geology of the jasper bars found in the older pre-Cambrian series.The jasper 'bars have in themselves little or no intrinsic value except perhaps some of the more highly coloured and banded varieties which may be utilised for ornamental and decorative purposes. Probably the best known of such varieties is the so-called "marble bar;" a belt of, strikingly coloured banded chert occurring just south and west of the famous town of that name (see Fig. 1t). This consists of a hard, very fine, even-grained rock with alternate individual stripes varying from the thickness of a sheet of paper up to an inch or more in width, and ranging in colour from clear white to yellow, from various shades of pink to brilliant...

Jan 1, 1943

By Z. J. Hladysz

A Deep Underground Science and Engineering Laboratory (DUSEL) is being planned at the site of the former Homestake Gold Mine in Lead, South Dakota, under the sponsorship of the National Science Foundation (NSF) in cooperation with the Department of Energy (DOE). This national facility will host a variety of multi-disciplinary science and engineering experiments including physics experiments that require shielding from cosmogenic radiation. Current plans include construction of large rooms (up to 55 m in width) at depths of 1.48 km (4850 ft) and 2.25 km (7400 ft) below the surface. Preparation of the preliminary design required the development of a geotechnical characterization program including: preliminary drilling and coring, core logging, drill hole mapping with a televiewer, drift mapping of the geology and rock structure, in-situ stress measurements, and laboratory testing of the mechanical properties of the rocks and discontinuities. Overall rock quality is very good to excellent. Site investigations were followed by geotechnical assessments for the construction of caverns and laboratory modules. The results are favorable and reaffirm selection of the Homestake site for establishment of a Deep Underground Engineering and Science Laboratory.

Jan 1, 2011

By G. M. Kintz

In safety work a study of past accidents is of value in determining means of reducing future accidents of the same character. This is particularly true with reference to coal-mine explosions. Data from publications of the United States Bureau of Mines and from published reports of the State inspector of coal mines of Colorado are presented in this circular in the belief that they will be of value to operators by indicating methods of preventing future coal-mine explosions. The tables included are complete only with regard to major disasters. The Bureau of Mines considers as a major disaster one in which five 'or more men are killed. However, this circular also includes a considerable number of minor disasters, Various explosions in the coal mines of Colorado from 1883 to 1932, inclusive, are listed with information available as to their probable cause, number of men killed and measures which, if they had been in use at that time, might have prevented them. John McNeil, first Colorado State coal-mine inspector, on page 43 of his first report for the period ended July 31, 1884, made the following recommendations for the prevention of explosions in the coal industry: True causes could be traced either to insufficient ventilation, carelessness and lack of rigid discipline in carrying on energetic ventilation and other precautions needed to be enforced in a mine giving off explosive gases. *** When any quantity of fine coal dust is observed in an entry, air course, or room it should be made damp and be removed from the mine, and thus beep every place as free from dust as possible. *** A system of bratticing close up to the face of each and every place in the mine from crosscut last made (whether gas should just then show its presence or not) which should not be more than 50 or 75 feet according to the nature of the mine.

Jan 1, 1933

By Peter Faust

The foundations for the new South Viaduct Bridge in San Francisco were extremely challenging due to the requirement for very large and deep piles installed adjacent to historic structures. Drilled shafts up to 12? foot in diameter were constructed to a maximum depth of 200? feet in alluvial soils and Franciscan Bedrock using an oscillator system for the installation of the permanent steel casing. This paper provides an overview of the construction techniques, the equipment, and the challenges associated with constructing 12? foot diameter shafts on this very complex project in one of the nation?s nicest landscape setting.

Jan 1, 2011

By Horst Peter Wölfel

The goal of biodynamic models is to simulate the vibration behaviour of the human body. In combination with experimental studies biodynamical models can be a powerful tool for the analysis of the effects of vibration exposure on health [1] and comfort. This paper gives an overview of the state of the art of biodynamic whole-body vibration models of humans, addressing both numerical models and hardware dummies. Method Two approaches are distinguished, the phenomenological and the anatomical, as illustrated in Figure 1. [ ] Phenomenological models aim to reproduce the vibration behaviour of humans with respect to particular physical quantities, chiefly the driving-point impedance at the interface to the seat, and partly with respect to other transfer functions. Discrete systems of masses, springs, and dampers with several degrees of freedom whose topology and parameters are determined by structure- and parameter identification methods are used in the sense that the functions derived from measurements are reproduced as well as possible. This paper provides an evaluation of this methodology and defines its range of application as well as its limits.

Jan 6, 2006

Bio-Oxidation of Arsenic and Stibium Bearing Gold Ores Bio-oxidation of arsenic and stibium bearing gold ores with acidithiobacillus ferrooxidans was studied. The preoxidation results show that the best bio-oxidation technical parameters are the initial pH in the range of 1.8 ~ 2.0, particle sizes under 0.074 mm, temperature in the range of 25¦C ~ 30¦C and rotating speed of the orbital incubator in 100 rpm ~ 160 rpm. The leaching results show that If the ore, of which contain 10.37 per cent arsenic and 36.81 per cent stibium, is not bio-oxidised, gold leaching is only about 41 per cent, after 8 days oxidised, the result is about 76.55 per cent, which improved about 35.62 points. The relationship between gold leaching and arsenic oxidation is direct proportion, furthermore, it needs only partly oxidise and higher gold leaching could be get, for example, gold leaching is over 90 per cent when asenic oxidation is 60 per cent. The results will provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory gold ores.

Sep 13, 2010

By Linda C. M. Elliot, Liangxue Liu

"The deposition of tailings under water is considered to be one of the most environmentally promising and potentially cost effective methods to reduce or eliminate acid mine drainage from tailings. One of the concerns of subaqueous deposition has been that metals may leach into the cover waters, thereby increasing aqueous metal concentrations to higher than acceptable limits. This potential was seen to have an even greater possibility for impact when the tailings are deposited under acidic lake water.The following paper summarizes the results of subaqueous tailings pilot column test work conducted to determine the effects of subaqueously deposited tailings on lake water and tailings pore water. Two types of tailings were tested: high sulphide tailings (pyrrhotite concentrate), and low sulphide tailings (end of pipe slime tailings).Data was collected from five columns over a 13 month test period. The results indicated that a stagnant I 000 mm water cover was capable of maintaining the underlying tailings in a reducing condition. The upwards diffusion of pore water resulted in a pH increase in the waters overlying the thickened pyrrhotite tailings and the pyrrhotite tailings with a shallow cover of substrate. A conductivity gradient between the tailings and the water cover caused a diffusion of salts upwards into the overlying water column. Precipitation noted at the tailings water interface may be related to the precipitation of ferric oxyhydroxides, which resulted in a decrease in Fe concentrations noted in the water cover. Other metal concentrations did not exhibit significant increases in the water cover. A sulphate concentration gradient between the tailings and the water cover may have caused the diffusion of SQ4 from the tailings into the water cover."

Jan 1, 1997

By D Vickers, N C. Fowke

The reduction of geological risk for planning of high production longwall faces is essential. Geological and geophysical techniques applied at Huntly West Mine before 1989 were unable to reduce the geological risk to an acceptable level. The success of a trial long-hole directional drilling programme at Huntly West Mine (Fowke et al, 1989) has encouraged the Coal Corporation of New Zealand to use the technology long-term, for seam definition. Initial drilling in 1989 completed a total of 3543 metres, with the longest borehole length being 369 metres (limited by number of rods available). A major re-interpretation of seam structure resulted from the drilling, which was able to fill in seam details between surface exploration boreholes. The undulating thick seam conditions at the mine require a refinement of drilling strategies used overseas. Long-hole directional drilling also displays potential for inseam gas drainage. Gas flows of the order of 1000 L/min were initially indicated in individual boreholes. Other gas parameters of the seam have been studied by Beamish et al (1991), and highlight the significance of the natural gas resource in the Huntly Coalfield.   The continued development of drilling technology will be of major benefit sustainable development, particularly in policy.

Jan 1, 1991

By Lloyd A. Morley

This seven-chapter document is the first volume of a two-volume report that presents a comprehensive outline of coal-mine electrical power systems from theory to practice. Together, the two volumes contain the vital aspects that go into planning and designing a mine power system. After a short introductory chapter, Chapter 2 discusses the history of electrical use in mining and introduces "typical" mine- power-system arrangements. Chapter 3, 4, and 5 supply basic information on electrical theory, circuit analysis, and motors. Next, the Grounding and Distribution Chapters detail unique aspects of mine power systems. Elements of surface and underground use are included in all these chapters. An index concludes Volume I and is cross-referenced to both report volumes.

Jan 1, 1982

By D. Craig Camp

conditions. The soils included 65 m of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2, 130 meters of soft clay, silt, and sand not exceeding 30standard penetration test SPT blows per 300 mm, and 220 m of rock ranging between an UCS of 400-600 kgf/cm2. The river crossing, utilizing 1778 mm OD x 19 mm wall x600 mm steel casing pipe without intermediate jacking stations, was part of a seven kilometer liquefied natural gas (LNG) transmission line in South Korea. This 440-m, 1,442-ft, river crossing was microtunneled through three different ground conditions and completed in just over three months. The crossing was achieved with an average of 25 m of ground cover and 15 m of water cover. The Kwang Yang River Crossing was part of a 7 km liquefied natural gas pipeline project for POSCO, a Korean steel producer. The microtunneling machine was custom built for this project. The microtunneling machine selected for this project was tooled with 7 button bits and 2 roller bits. None of the cutter bits were replaced during the drive. Inside the machine, before the spoils laden slurry was pump back to the surface, it would pass through an independent cone crusher. The crusher is placed in the slurry flow to make sure that none of the spoils are so large as to stop the return flow of the slurry. An additional requirement was for the inclusion of a compressed air lock. The air lock was required in the event that the cutter tools required replacement. The cutters were back loaded so that the workers would have access to change the cutters in the event of cutter failure or wear out. No intermediate jacking stations were installed for the drive. The soils included 65 meters of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2 with production averaging between 7 and 20 mm/minute. The second zone contained 130 meters of soft clay, silt, and sand not exceeding 30 standard penetration test (SPT) blows per 300 mm with production averaging between 80 and 180 mm/minute. The third zone contained 220 m of rock ranging between an UCS of 400-600 kgf/cm2 with production averaging between 7 and20 mm/minute. The steel casing pipe was 1778 mm OD x 19 mm wall x 6000 mm long. The project profile, see Figure 1, shows the soil conditions. The hand written numbers locate just above the pipeline are the production dates. The circled numbers are the 10 pipe joint increments. The project required 74 pieces of pipe to span the440 m drive. Figure 2 and Figure 3 are the jacking information. Figure 3 is a continuation of the information from Figure 2. The top section of the graph is the jacking force. The jacking

Jan 1, 2001

By W. R. K. Wu

This bulletin traces the development of high-pressure, coal and tar hydrogenation technology, based on an intensive review of the pertinent literature. The bulletin was written as a part of the Bureau of Mines research program on synthetic liquid fuels. It covers the history and economics of the process; the chemical aspect of hydrogenation of coal, tar, and middle oil; the engineering aspect of converting coal and tar to liquid fuels, principally gasoline; and the equipment for the process. The literature covered includes documents of the United States and British Governments, journals, and other publications. Bureau results in the hydrogenation field are also incorporated.

Jan 1, 1968

By Peter Makuvise, Alain M. Bantshi

"The Mazowe Gold Mine is managed by Metallon Gold (Zimbabwe) and is situated in the west-central part of the Harare greenstone belt. Orebodies here generally comprise shear zones which are in-filled with gold-bearing sulphides and quartz. The mineralised zones are up to 1 m in width, have average grades of 4 to 5 g/t, and mostly dip between 10º and 60º to the north.Mazowe Mine is one of the oldest mines in Zimbabwe, and exploration and development in this region dates back to 1890, with over 1.4 million ounces of gold produced to date. Mazowe mine comprises two underground operations, Mazowe and the BSV sections. Ore is processed in a single plant which consists of conventional crushing and milling and carbon-in-leach facility.Baldmin Projects was awarded the contract for the design, construction and commissioning of the 60,000 tonnes per month plant at Mazowe mine in 2014 for the processing of sand and slimes tailings from previous operations at Mazowe mine. The average grade of the tailings is 1.1 g/t. The plant consists of feed preparation, grinding, flotation, thickening of flotation concentrate, and carbon in leach (CIL). A pump station for hydraulic mining of the slimes tailings dam also part of the plant.Key features of the Mazowe sands Plant are described and include:• Hydraulic mining of gold tailings dump.• Feed preparation section that includes a (W x L) 2.4 m wide x 4.8 m trash screen, 250 m3 surge tank, a cluster cyclones with 2 x 500 mm diam. Cyclone.• Comminution circuit designed for a bond work index range of 10-12 kwh/tonne. comminution circuit is constituted with 3 ball mills, 1.83 m diam. X 6.71 m Long, 280 kW.• Flotation circuit comprising rougher bank, scavenger bank and cleaner bank. Rougher Scavenger bank is constituted of 6 x 6m3 flotation cells and 3 x 30 m3 flotation cells and the cleaner is constituted of 3 x 6 m3 flotation cells.• Concentrate Thickening with 6 m diam. Thickener.• Concentrate CIL (carbon in leaching): CIL circuit is comprised of 7 tanks with 2 leach tanks and 5 Carbon in leach."

Jan 1, 2017

By Branagan D. F

The geology of the area studied is briefly described, together with the prospecting methods used in the search for copper, lead, zinc and uranium ore bodies.Four prospects, Mt. Corella, Yanasinga, Lawlor's and Greenmount, which were diamond-drilled, are described in detail and geochemical results are discussed in relation to the mineralization found. Copper anomalies were found wherever intrusive rocks were mapped, and showed a much closer relation to geology and mineralization than did the predominantly lead and zinc anomalies.Geochemical prospecting aids in the overall mineral search programme because of its speed and economy, as it helps to pinpoint areas worthy of detailed geological examination. Geochemical anomalies are a guide to favourable zones but may not indicate the presence of ore.INTRODUCTIONDuring 1953-55 the National Lead Company of New York carried out a search for minerals in an area south and west of Cloncurry (Fig. 1) in rocks of Precambrian age. After reconnaissance mapping, a number of prospects were chosen for closer examination by detailed geological mapping and geochemical sampling, and from these prospects, five sites were selected for drilling.This paper records the salient features of the exploration programme and discusses the geology and geochemistry of four of the prospects-Mt. Corella, Yanasinga, Lawlor's and Greenmount. Practically all the prospects examined showed high zinc "anomalies" or "dispersion" trains. Greta, Mt. Corella and Lawlor's prospects showed some copper anomalies and, to a lesser extent, lead anomalies. In particular, Greenmount exhibited striking copper anomalies.

Jan 1, 1960

By J. W. Paul, J. N. Geyer

"GENERAL STATEMENTThe purpose of this report, which is the first of a series of three covering mines in the Fairmont district of West Virginia, is to give the result of a' study conducted in seal mines to ascertain the nature of the safeguards employed to prevent injury to the workmen from falls of roof and coal. In presenting the subject matter, consideration must necessarily be given to factors, features, and conditions such as method of mining, timber regulations and practices, supervision and natural conditions; and, for comparative purposes, a certain amount of statistical matter bearing upon the relation of fatalities and injuries to their causes, tonnage produced, men employed, days worked, and time lost.Those features and practices found to promote safe protection are summarized and suggestions made for such additional safeguards and practices as appear to give greater protection against injury from falls of roof or coal.ACKNOWLEDGMENTSThis study of falls of roof and coal in mines in Harrison County has been conducted by the U. S. Bureau of Mines in cooperation with R. M. Lambie, chief of the Mining Department of the State of West Virginia who assigned L. W. Brown, a district mine inspector, to assist in the field work and in the preparation of individual reports on each mine visited in this study. The writers acknowledge the helpful suggestions and cooperation given by these officials, the latter of whom assisted in the field work and prop red most of these sketches for the individual reports which wore submitted to the operator by the chief of the department. Thin report is a summary of the contents of the individual reports heretofore furnished the individual operator."

Aug 1, 1931

IN the construction of a set of ordinary mine plans, two axes or coordinates are used; also, two different projections are essential viz., a plan (horizontal projection) and longitudinal section (vertical projection). In isometric projection three axes are employed-one axis vertical and the remaining two inclined to it at angles of 120°, also making an angle of 120° with one another, as shown in Fig. 1. The two inclined axes are used to plot the horizontal projection, while altitudes are plotted on the vertical axis. As an illustration, consider the ease of a simple object, such as a box. To show all the dimensions in the usual manner requires two drawings-a plan and elevation, as in Fig 2.

Jan 1, 1919

By J. H. D. Hargrove, A. F. Snowball

Atmospheric pollution control has become increasingly important in re-cent years with laws and public opinion having required the reduction of contaminants from industrial gas effluents. Treatment methods have advanced to make possible, with proper plant design and operation, a satisfactory removal of these contaminants. Gases from Cominco's metallurgical operations at Trail, approximating 900,000 c.f.m., are treated by baghouses, electrostatic precipitators, cyclones, or wet scrubbers. The tabulated data include gas and dust conditions, plant performance, and some details of plant equipment. Discussion emphasizes the special features, scope of application, and basic design principles of the treatment methods, all based on Cominco experience. Recovery of over 99 per cent of the fume and dust is achieved by the major installations from which effluent gases go to atmosphere. Cooling of gases for baghouse recovery and conditioning for electrostatic precipitation are mentioned. Co3ts are tabulated for some of the installations on the basis of a unit of 1,000 cubic feet of gas. Suggestions are made on the procedure for assessing a smoke treatment problem and for selection of suitable equipment.

Jan 1, 1959