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Underground coal mining continues to evolve in the U.S., and more reserves are being mined under deeper cover, with worse roof, or with interactions from previous workings. At the same time, the mining community is responding to higher safety standards and intense competitive pressures. The need for effective ground control design has never been greater. Ground control safety issues that have been addressed by recent the National Institute for Occupational Safety and Health (NIOSH) research include: Improving roof support performance; Maintaining safe tailgate escapeways from longwalls; Optimizing pillar design for retreat mining; Controlling multiple seam interactions; Predicting roof conditions during extended cuts, and; Preventing massive pillar collapses. As funding from both government and the private sector has diminished, the emphasis in research has focused on providing the mining community with practical techniques for improved ground control design. Many projects have successfully employed empirical methods that emphasize the statistical analysis of case histories from underground mines. Other projects have employed numerical models and large-scale laboratory testing of roof support elements. Using these data, NIOSH has developed an entire toolbox of computer programs that have been effectively transferred to the mining community.

The spatial distribution of copper grades at the Mansa Mina project is highly variable due to the presence of high grade copper/silver/arsenic breccia bodies. Copper grades within the breccia bodies tend to average about 4.5% copper while grades in the surrounding stockwork average about 1.0%. The breccia is known to occur in the vicinity of significant controlling structures, however, the outline and therefore the thickness of the bodies are far from regular. Due to the high grade of these bodies a significant proportion of the value of the project is derived from the breccia tonnages. The irregularity in the outlines/thickness translates into an uncertainty in the breccia tonnage and therefore in the value of the project. Acknowledging the economic importance of the breccia bodies and the risk associated with the breccia tonnage uncertainty, significant additional drilling has been proposed to both understand the spatial distribution of the breccias and reduce project risk. The costs associated with this additional drilling are not inconsequential; thus, a reasonable question is ‘what value is derived from this additional drilling’? To obtain an answer to this important question, a simulation approach is applied. First the deposit is simulated using the existing drilling and the uncertainty in the resource is defined. Next the proposed drilling program is simulated and the simulated data are added to the existing data. Using this expanded data set a second simulation of the deposit is created and once again the uncertainty in the resource is defined. Using this approach, the reduction in the uncertainty in the resource can be determined. To convert this reduction in uncertainty (or reduction in risk) in the stated resource into a dollar value, a method of defining the increase in the project rate of return necessary to account for risk is presented. Using the two different rates of return, the difference in project NPV and hence the value of additional drilling is determined.

Jan 1, 2003

By Edward W. Parsons

The transverse force developed by expansion-shell rock-bolt anchors on the wall of a drill hole as the bolt is tensioned was measured by the Bureau of Mines using a device specially designed and fabricated for attachment to a universal testing machine. Load cells equipped with electrical-resistance strain gages provided the data from which the transverse force, in pounds, was calculated. Seven different expansion-shell anchors were tested, and the ratio of transverse force to bolt-tension load was found to range between 0.98 and 1.94 to 1.0. The drag load appeared to be the major cause of the transverse-force variation, but the relative effects of individual factors that affected the ratio between the transverse force and the bolt tension were not determined.

Jan 1, 1968

By M. R. Geer

Information on the performance of coal-cleaning equipment is necessary to provide a basis for evaluating the performance of existing plants and projecting that of new plants. Performance data can contribute greatly to the wise selection and effective use of coal-washing equipment. The Bureau of Mines has published information on the performance of several commercial plants, as well as of some laboratory-scale equipment, 5 (2-9, 11, 12, 17-12, 21-25) from time to time for a number of years. A more intensive program to provide such information for all the principal types of cleaning equipment is underway. The present evaluation of table performance is part of this program.

Jan 1, 1962

By William D. Hissem

For those blasthole applications which require the use of holes ranging from 1” to 5.5” in diameter, the use of top hammer drills has been the equipment of choice for several generations of drillers. Pneumatic compressed air and hydraulic compressed oil systems represent the primary technologies which are available to the drilling practitioner. While both employ the same operating principals, the characteristics of performance, cost, and reliability can be markedly different between technologies and manufacturers.

Jan 1, 1998

Properties of coal which are significant in relation to preparation for carbonization and conversion are reviewed, and existing coal preparation technology which has been used for production of cleaned coal of suitable ash content and petrographic composition for carbonisation, pyrolysis, hydrogenation and similar processes is described. Possibilities for application of this technology to some Australian coal seams is examined briefly. It is concluded that further survey work is required related to the optimization of selective crushing and concentrating operations, with the aim of maximizing production of quality products for carbonisation, etc mainly from Australian seams with only moderate coking characteristics.

Jan 1, 1980

By S. J. Broderick

[Xuge d-mp heap co:lt:.ini9: tilcu?:na3s of tons of cad ~eP~se 2r3 a failiar sight in coal-mininc regior@:. T5ey reprecei~t considergole economic 1083, are very l.u.,si~hC,ly, ?:ld t?ke un m-lch vaL-x3le qace. Cor.sequentl;r thelr remcval i~ geatlyr dezir36, ax2 my ret-sn t?-at c,m be obtained would be er;pecic.llj .a~elconre&apos; t.7 the cod ir.S..r; kry. T?.e vaste rk.t~ri..tl conpl-ises large pieces of slr.t.e, hi~h-2s&apos;. bore c~al., luqs cf cle:., ,ad finer refuse conin,= fro3 the vrtskery, Tilt 1:zshcr:r refilsn contnins sone yood coal. Rig coal and the &apos;better p~lcs of bore ere the zat~rla2.s ~15:;~itiered in this in- vest ig:?.tion. 7% Il~avter frnctions of the w~~sherjr ref;lw aizd tts large 2ieces of slcte ?,".:I rgck contilin 1it:lei ccai-i-bcna.c~o~s caterial ad are vir- tu<dly worthiess nc, rz:. ::atcrin!. for .*=irin,= zct,iv?*teb cCvb~n. 13 the 3irniingh.m district, i13br.12, a-c.ju",P p?rcccn",f the c3sl r?.ir?ed is washed, ,md in tkis c?i.;trict nlz:~c rcfilce ecc;:?:lletcs ~t the r%tg of 1 to 2 million .! tons 2 yew.]

Jan 1, 1941

By C. Hellar

A new dual-boom remotely controlled roof bolter was designed, fabricated, and then tested in an underground coal mine. Remote-control functions allowed complete bolting cycles to be performed on two booms with both operators located within protective cabs. Capabilities included 3-to 6-foot-long bolts in 5-to 8-foot seams, limited to bolts 20 inches shorter than seam height. Machine was in compliance with all regulations including dust collection, machine lighting, and permissibility.

Jan 1, 1979

By Charles Findlay

As one of its projects for degasification of major panels of coal prior to mining within them, the Bureau of Mines conducted methane emission studies during development of a set of three headings 1,800 feet in a major coal panel (2,700 by 3,500 feet) which had been completely isolated by sets of main headings for 12 months in the Federal No. 2 mine (Pittsburgh coalbed) in northern West Virginia. Similar emission studies were conducted in the development of two sets of main headings in virgin coal areas nearby. Comparing the two sets of data indicated that the isolated coal panel had been degasified by approximately 70 percent.

Jan 1, 1973

By Vance G. Leak

Leaching of manganese from low-grade Minnesota ores was studied over the temperature range 25° to 225° C at atmospheric and elevated pressures to demonstrate that good recoveries of manganese could be achieved from unroasted ores using reagents available nearby. Various combinations of ore, pyrite, lignite derivatives, and sulfuric acid were tested on a small scale. Pyrite alone required the highest temperature to effect a good extraction, but the combination of pyrite, lignite char, and sulfuric acid solubilized 99 percent of the manganese after 30 minutes of reaction at 75° C.

Jan 1, 1971

By S. L. Crouch

An important class of mining problems involves excavations in planar seam or vein-type deposits. In many instances it can be assumed that the seam is at &apos;infinite&apos; depth in a homogeneous, isotropic or transversely isotropic, linearly elastic rock mss, and that the normal to the plane of the seam is a principal stress direction. Rational planning of excavations in such deposits requires a knowledge; of the stresses and displacements induced by complicated, irregular excavation geometries in the plane of the seam. This problem previously has been solved either numerically or by means of an electrical resistance network analog. Both of these methods effectively simulate the mined portions of the seam as a dislocation in an otherwise continuous mass, and determine the complete solution in terms of the stresses and displacements at the seam. In both cases, the plane of the seam is divided into a number - say, M x N - of squares, and the solution to the problem is determined in terms of the solution to an M x N system of equations. The numerical approach requires that these equations be solved explicitly, while the analog; solves them instantaneously with current analogous to stress and voltage to displacement. A purely numerical solution of practical problems can require a substantial amount of computer time, particularly in situations that demand some sort of sequential analysis, either due to successive mining or to nonlinear behavior of the seam material. This report describes a combined analog-digital computer system for solving problems that are impractical when either device is used separately. The digital computer and the analog are interfaced so that the digital computer can receive information from the analog via a switching matrix and an analog to digital converter, and can activate points of the analog via another switching matrix and a set of digital to analog converters. The resulting hybrid system can be used to simulate arbitrary "stress-strain" characteristics for any portion of the seam by an iterative procedure similar to the initial strain method used in nonlinear finite element analysis. Thus, the hybrid system combines the speed of analog computation with the decision-making capability of the digital computer: the analog instantaneously solves the set of equations, and the digital computer decides how the initial strains must be altered for the solution to be compatible with the prescribed "stress-strain" characteristics for the seam material. The hybrid computer system has many implications for rational planning of underground excavations, since it allows practically any type of inelastic seam behavior or artificial support characteristics to be simulated. Inelastic seam behavior, for example, might be due to either rock failure or to time-dependent deformation.

Jan 1, 1974

By Tuncel M. Yegulalp

This final report contains the results of all work performed under BOM Grant J0333905. A preliminary systems analysis of coarse-particle coal slurry pipelines as a haulage method for longwall mining systems was performed. Two exhaustive literature surveys on state-of-the-art longwall mining and slurry transport technologies were prepared. Two representative longwall systems were designed, one with conventional haulage and one with slurry haulage. These two systems were then compared on the bases of cost, safety, and reliability. The conclusions were that for the case of a two-face longwall mine, a coarse slurry transport system does not have a clear-cut cost advantage over a conventional (conveyor-hoist) system. However, indications were that a cost advantage could occur under different analytical conditions such as: (1) a larger scale mine, (2) if intangible benefits were quantified, and (3) if new generation technology rather than currently available technology were applied to the study. Budget and time constraints prevented exploration of these conditions.

Jan 1, 1982

By John J. S. Sebastian

A laboratory-scale investigation was made of the basic problems involved in developing a ceramic heat exchanger to operate at high temperatures for using nuclear heat from gas-cooled process-heat reactors. Technical data were obtained on transferring heat by forced-convection from helium to air in a single-tube vitreous-alumina heat exchanger. Coolant air was passed through the annulus parallel with, and either concurrently or counter to, the flow of helium inside the tube. The data obtained pertain to removing heat from the helium. Average inside film coefficients were determined at mean surface temperatures of 200° to 1,570° F., inlet-gas temperatures of 1,450° to 2,665° F., and Reynolds numbers up to 560. The gas-to-surface temperature ratios were varied from 1.05 to 7.6. The tabulated results are shown in the appendix at the end of this report. The film coefficients of heat transfer were correlated by taking into account the physical properties of the helium at the average fluid temperature. With experimental conditions pointing to a laminar flow, the Nusselt number was found to decrease as the ratio of gas-to-wall temperature was increased to a value of 3. However, within the range tested, gas-to-wall temperature ratios above 3 did not affect the Nusselt number, regardless of the value of the Graetz number. Thus, beyond this point any increase in this ratio ceased to influence the heat-transfer relationship.

Jan 1, 1962

By A. J. Monhemius

"The paper reviews the history of modern iron control processes in hydrometallurgy. Particular attention is paid to the processes developed in the 1960s by the electrolytic zinc industry for the removal of iron from zinc sulphate leach liquors - namely the Jarosite, Goethite and Hematite processes. Problems faced by the industry in the safe disposal of the iron residues produced by these processes are discussed. The lessons learnt over the past half century by the zinc industry are projected on to the current efforts to develop hydrometallurgical processes for the treatment of copper sulphide concentrates. It is argued that any attempt to create a “hydrometallurgical copper smelter” is doomed to ultimate failure, unless and until methods are developed that can recover iron from solution in a form that can be directly utilised by the steel or pigment industries.INTRODUCTIONYou suddenly realise that age is catching up with you and that technology is moving on apace when you are asked to talk about the history of a process or a technology that you’ve grown up with. Such was my reaction when, out of the blue, I received an email last year from the chairman of the CIM’s Historical Metallurgy Committee, asking me if I would give a talk on the early developments of iron control in hydrometallurgy. Once I’d got over the initial shock of realising that I had now become living history, I was of course flattered that the invitation was to give a talk at the prestigious IMPC, a conference series that has been going for as long as I have been in the business. That this particular IMPC was to include the 4th Symposium on Iron Control in Hydrometallurgy, made the invitation even more appealing and appropriate, because I was the co-chairman of the First Symposium on Iron Control, together with my old friend, John Dutrizac (known by many as Dr Jarosite), which was held 30 years ago in Toronto.first became involved with iron at the very start of my career in hydrometallurgy – the research topic for my Masters degree thesis at UBC, back in the mid 1960s, was “Reductive leaching of Goethite with SO2”. My thesis supervisor was the late Professor Ian Warren, who himself was a protégé of Professor Frank Forward, one of the founding fathers of modern hydrometallurgy. Little did I realise at that time, now 50 years ago, that the problem of iron and how to deal with it in hydrometallurgical processes would be a theme that followed me throughout much of my 40-year career in academia."

Jan 1, 2016

By A Parbhakar-Fox, B G. Lottermoser

Management of solid mine wastes, particularly waste rock, requires careful planning to reduce the likelihood of sulfide oxidation, and generation of acid rock drainage (ARD). Waste management strategies must focus on obtaining a thorough understanding of the environmental characteristics of future waste rock materials. In this study, a waste management strategy for characterising underground waste rock was developed at a polymetallic underground mine in western Tasmania to determine which materials were appropriate for surficial placement. The criteria for surficial placement set by the regulator were that materials had to be non-acid forming and non-metalliferous. A range of cost-effective field-based tools, mineralogical assessments and mineral chemistry techniques were used on a suite of representative drill core material to determine an appropriate waste management strategy. Ultimately, a modified geochemistry–mineralogy–texture–geometallurgy (GMTG) approach was designed, whereby geoenvironmental focused logging and simple prescreening tools such as paste pH and sulfur analyses were used at stage-one; routine acid base accounting and leachate tests at stage-two; and validation tools including X-ray diffractometry and laser ablation inductively coupled plasma-mass spectrometry (ICPMS) at stage-three. This approach should be considered for other mine sites at early and operational life-of-mine stages with similar deposit characteristics, to ensure correct screening and placement of potentially hazardous waste materials in suitable above-ground waste repositories or mined-out mine sections.CITATION:Parbhakar-Fox, A and Lottermoser, B G, 2017. Effectively linking mining geology with waste management – a case study from western Tasmania, in Proceedings Tenth International Mining Geology Conference 2017, pp 117–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By John Chipman, Wayne L. Worrell

Using recent thermodynamic data for the carbides and oxides of tantalum, columbium, and vanadium, the stable solid phases aboue 1300°K and at 1 atm CO(g) pressure in each M-C-O system have been determined. Pourbaix-Ellingham diagrams have been constructed and are used to estimate the minimum temperatures necessary to obtain these metals by carbothermic reduction under reduced pressures. TANTALUM, columbium, and vanadium react with carbon to form the M,C and MC carbide phases. The M,C carbides have narrow homogeneity ranges, but the MC phases possess considerable ranges of homogeneity.&apos; The free energies of formation of the MC carbides were recently measured, and those of MC and M2Ccarbides have been estimated., (The notations MC and MC denote, respectively, the carbide compositions at the carbon-rich and at the metal-rich boundaries of the homogeneous MC phase.) In this paper, these carbide data are combined with thermodynamic data for the oxides to predict the stable phases in the Ta-C-O, Cb-C-O, and V-C-O systems at specified temperatures and oxygen pressures. M-C-O PHASE DIAGRAMS The solid phases in equilibrium above 1300°K for each M-C-0 system are shown in Figs. 1, 2, and 3. Above 1300°K, the vapor would consist entirely of carbon monoxide; and these phase diagrams were obtained by specifying the vapor pressure of CO(g) to be 1 atm. The temperature at which any two solid phases become unstable is specified along the two-phase equilibrium lines in each diagram. To simplify the diagrams, all solid phases in the Ta-C-O and Cb-C-O systems are represented as stoichiometric compounds. However, the homogeneity ranges of VO and VC are indicated, because they form a complete series of solid solutions.3 It also should be noted that the homogeneity range of

Jan 1, 1964

By James P. Stewart

This case history describes the engineering design and construction for the Contractor of a 35-ft-deep excavation for an 800-square-foot addition to an existing sewage pump station. The site posed unexpected geotechnical complications that included deep gravelly soil, a history of local construction difficulties, groundwater consisting of heavy salt brine, and the need to underpin the existing pump station. The project took an interesting twist when the Owner issued a change order limiting the dewatering discharge to a fraction of that required to lower the water table. This documents the interesting circumstances of this job and documents the unusual subsurface conditions in the Syracuse, NY Lakefront area.

Jan 1, 2003

The Torington Lodes.This paper describes investigations into mineralogical, petrological and structural associations of cassiterite in occurrences of economic value. The work was carried out in three mines, during a number of years, in the hope that the, data collected might be helpfulin the search for occurrences of cassiterite in stanniferous zones and reduce unproductive exploratory work. Tin-bearing lodes at Torington, in the New England district, New South Wales, have been worked since 1880, and the locality is the most important centre of lode tin occurrence in the, State. The township of Torington is 18 miles westerly from Deepwater, a station on the Great Northern Railway, 446 miles from Sydney.The tinfield forms part of the Mole Tableland, which has an altitude between 3,000 ft. and 4,000 ft. above sea level. The country rock, in which the stanniferous lodes occur, is granite of Permian age, which has been intruded into Carboniferous claystone. An inlierof claystone is exposed to the west of the stanniferous area, &apos;and in it, close to&apos; its contact with the enclosing granite, are occurrences of wolfram and bismuth. These minerals, together with chalcopyrite, pyrite, arsenopyrite, zinc blende, galena and molybdenite, in very small quantity, are associated with cassiterite in lodes traversing the granite, particularly near the claystone, but decrease in amount with distance from the contact. Their occurrence is sporadic and usually causes no trouble in dressing the cassiterite concentrate, the final product containing less than 1% of total penalisable impurity. In Curnow&apos;s mine, pyrite, galena and molybdenite have been observed at 700 ft. from surface.The granite is of the biotite type and its structure may be divided into four groups, or classifications, arising from segregation processes during cooling and consolidation. The four classes, in order of extent of distribution, are:1. Granite of normal type, in which the constituent quartz felspar and mica, have a particle size approximately 14, in.2. Porphyritic granite, in which the felspar particles are from % in. to lin. in size, that of the quartz and mica approximately % in.3. A fine-grained granite, in which the particles of all constituent minerals are % in. or less in size;4. A rock of highly siliceous ground mass containing very small particles of felspar and almost negligible biotite.Type 1 is the general type of granite in all mines of the field; types 2 and 3 may occur as large masses, or all three classes may merge rapidly one into the other, and all be disclosed in 20 ft. of driving. Usually, however, the segregations are massive, but are not associated with any special horizon. For instance, a mass of porphyiiticgranite extends from surface to a depth of 440 ft., for a distance of 350 ft. south from the New England main shaft. The upper levels of Curnow&apos;s mine, 14&quot; mile south-east, are in normal granite, but a restricted mass &apos;of porphyritic granite occurred between Nos. 5 and 6 levels, or 400-500 ft. below the collar of the shaft...

Jan 1, 1950

By Timothy D. Stark

Jet grouting has increasingly become one of the ground improvement technologies used to address seepage concerns and to provide strength improvement of soils. The technique of jet grouting uses high pressure/velocity jet fluids to erode the existing soil and then to mix the cuttings with cement slurry to form soilcrete. Excess slurry or spoil is ejected to the surface. If the native soil is not completely mixed with slurry, the resulting columns will have soil inclusions which can reduce the strength of the column and/or increase the permeability of the column. A jet grout test program at Tuttle Creek Dam shows that the completed large diameter columns contain perhaps 40 to 50% or more of native soil that was not broken up and mixed during the jet grout process. The test program included excavation of full-scale columns to a depth of 35 ft (10.7 m) for visual inspection and testing. Additionally, six of the columns were cut or sectioned to investigate the interior of the columns. The observed inclusions include significant amounts of both fine grained (silts and clays) and coarse grained (fine sands and sands) soils. Evidence suggests at least two explanations: (1) fine grained soils can be difficult to erode and break up into small enough particles that can be ejected to the surface, especially if at low natural water content, and (2) when large diameter columns are being excavated, the excavated roof of the cylindrical cavity may be unstable and may collapse. With this roof instability large slabs of material can break off, fall into the slurry and escape the cutting and mixing action of the rotating jets. This paper describes the Tuttle Creek Dam test program, inclusions observed in the completed columns, and suggests potential causes of the inclusions.

Jan 1, 2009

Several of the larger copper projects recently built have included a molybdenum byproduct circuit as part of the overall project due to the favorable molybdenum market conditions and overall economic contribution to the project. This paper provides a summary of moly plant flotation practices across a number of both recent projects and historical ones. Modern Molybdenum flotation flowsheets predominantly incorporate self-aspirated cells and forced air cells with nitrogen addition. The paper provides insight into the process considerations, capital and operating costs associated with both of the cell types. It also reviews metallurgical aspects and important safety aspects. Other aspects including instrumentation and degree of automation are also discussed along with overall plant design.

Feb 27, 2013