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By Peter Dowden, Trevor Carter, Allan Moss, Bruce Downing, Richard Beddoes

Traditionally (with a few exceptions) tunnel boring machines (TBMs) have been utilized on tunnel projects where the risks associated with deep tunnels (rock burst, squeeze, etc) are low (or expected to be low). This has generally been due to the extremely adverse consequences of entrapping or damaging a TBM under such conditions; but also due to the relative difficulty of dealing with these ground conditions in the confined working area of a TBM, in comparison to a drill and blast heading. This paper review the constraints of operating a TBM in a deep tunnel and discusses related project experience, particularly recent and current experience with TBMs in the deep Alpine Base Tunnels. Potential future applications of TBMs in the development of large, deep underground mines are also discussed.

Jan 1, 2007

"Drilling twinned holes is a traditional technique used for verification of intersections of high-grade mineralization, testing of historic data, or confirmation of drillhole data during geological due diligence studies. Twinned holes can also be used for special tasks such as correcting earlier data that are recognized to be biased. Successful implementation of the twinned-holes technique requires thorough planning. Experience suggests that good practice is to drill twinned holes no more than 5 m apart. Many unsuccessful twinned-holes programs could possibly have failed because the twinned holes have been drilled too far apart.Twinned holes are best compared by mineralization intersections and, if the data and geological characteristics of the deposit permit, by samples, equal-length composites, or geological units. Variables to be verified by twinned holes should include the thicknesses of the geological units of interest (e.g., mineralized thickness) as well as the presence of significant geological features (e.g., ore/mineralization contacts, alteration, etc.).A formal, rigorous analysis of twinned-hole data is essential. Repeatability of sampling, analytical results, and bias must be analyzed and statistically quantified. The number of twinned holes required for conclusive statistical and geostatistical analysis can be as high as 20-30, in particular where the studied variables are characterized by high short-range (local) variability.The efficiency of this approach is demonstrated by several examples of successfully applied twinned-hole projects, including applications to orogenic gold, mineral sands, bauxite, and iron ore deposits."

Jan 1, 2009

By Missy Isaman

"Mixed ground tunnels come in all kinds. In rock tunnels with possible faults and high pressure water, the challenges are many. With the advent of Crossover TBMs, contractors can minimize machine wear in such conditions while maximizing efficiency. The newest generation of Crossover is exemplified by two projects in Albania and Turkey. A 5.56 m Crossover TBM destined for Turkey’s Gerede Water Transmission will be assembled using Onsite First Time Assembly (OFTA) from within an existing tunnel. The unique machine will bore through 30 fault zones requiring the TBM to be sealable to up to 20 bar so pre-consolidation grouting can be done. If boring under pressure is required, the TBM will bore sequentially using the screw conveyor fore and aft gates. Skewing further towards hard rock, a unique 6.2 m diameter Double Shield TBM with Crossover features was designed for Albania’s Moglicë Headrace Tunnel. The machine features closure doors and a sealing system to contain inrushes of water until they can be grouted off. This paper will discuss the unique aspects of the Crossover designs, including their inception as based on past projects in difficult ground, and their utilization at the two current projects. INTRODUCTION Specialized tunnel boring machines have been made for years to tackle specific types of ground conditions. Traditional types of TBMs bore within a specific set of ground conditions. If a project is located in a competent granite face, then a Main Beam machine is a good solution. In soft ground, Earth Pressure Balance (EPB) machines are the method of choice. Years of experience and engineering advancements have made both types of machines fast and economical solutions for tunneling. Unfortunately not all ground conditions are a perfect swath of one material, and the need for a more diverse machine is apparent."

Jan 1, 2016

By C Haughy, F F. Pitard

Blue Mountain Minerals is a large supplier of calcium carbonate products used by various manufacturers as a major raw material. Very small amounts of free carbon in the rock can have a huge impact in carbon-sensitive applications. The marble in the deposit at Blue Mountain Minerals contains variable amounts of free carbon in the form of trace amounts of the mineral graphite.To make quality improvements, variography was used to measure the impact of non-ideal sampling practices at the Blue Mountain Minerals operations in Columbia, California in the United States. A major investment in correct sampling systems and sampling protocols was implemented over a one-year period. Subsequent variography was used to measure the improvement on the predictability of the graphite content in marble produced by the quarry and as it is processed as an acceptable raw material for extremely carbon-sensitive applications. The improvements of the sampling protocols, control of long-range changes and better knowledge of process cycles are easily noticeable on variograms when they happen to exist. The economic impacts are discussed.CITATION:Haughy, C and Pitard, F F, 2017. Use of variography to measure improvement of sampling practices for the quality control of graphite consistency in marble used for carbon-sensitive applications, in Proceedings Eighth World Conference on Sampling and Blending , pp 255–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By M. F. Goodrich

The concept of using water-only cyclones as a clean coal scalping device preceding a heavy media cyclone circuit shows considerable promise, as it can considerably reduce the feed to the heavy media cyclone circuit. The system will not perform as well as a heavy media cyclone circuit alone, but the resultant loss in yield is small and may be negligible under some conditions. The concept of water-only cyclone scalping has previously been suggested by others. By reducing the amount of raw coal to be processed in the more expensive circuits overall capital and operating costs may be reduced. There are a few commercial plants with circuits operating on this concept. In the Warwick and Rowland plants water-only cyclones are used to scalp the feed to a heavy media vessel and Deister tables respectively while Amherst Coal Company's McGregor plant uses them to scalp the feed to a heavy media cyclone circuit. The system was evaluated on a technical basis, both from a theoretical viewpoint and by analysis of a computer simulation, in order to gain a fuller understanding of its usefulness and limitations.

Jan 1, 1977

By J. T. Kalala

Particles for heap leaching in conventional circuits are prepared using Cone crushers. Cone crushers are used to crush the ore to the size range between 12-25 mm for heap leaching operations. Leaching from these relatively coarse particles occurs only at the surface and in subsurface regions, which are accessible from the surface by cracks and pores. Since leaching is active in accessible areas, the method of comminution that forms multiple cracks and pores would offer an advantage for heap leach. An investigation was performed in this study to assess if the HPGR forms more cracks and pores than a Cone crusher. X-ray computed tomography (CT) was used to characterize the degree of cracks and pores formed by these two comminution devices that can be used for heap leaching feed preparation. In order to compare the effect of the comminution method on crack network generation, a bulk sample of the zinc ore was crushed by the HPGR at three different pressure settings (45, 95 and 120 bar), the sample ore was also crushed with a Cone crusher for comparison purposes. Products from the Cone crusher and HPGR experiment were then screened into five size fractions ((-25 +19), (-19+16), (-16+9.5), (-9.5+5), (-5+4.75) mm), Subsamples from the ((-25 +19), (-16+9.5), (-5+4.75) mm) size fractions were analysed. The spatial distribution of the crack network of sphalerite particles was characterized using a highresolution industrial X-ray CT system. This paper describes the use of image analysis techniques including image segmentation, which uses a combination of thresholding and other methods to characterize and quantify crack and mineral dissemination in the sphalerite particles after comminution with the HPGR and Cone crusher. The results are validated with those obtained using traditional techniques such as physical gas (with N2) adsorption, mercury intrusion porosimetry, SEM and QEMSCAN.

Jan 1, 2012

By R. Philip Hammond

Monazite has had a Cinderella-like history. Although nearly go per cent pure rare-earth compound (rare-earth phosphate) it was sought at first not for the rare earths but for the sake of a minor constituent—thorium. The thorium, essential for the Welsbach gaslight mantle, was present in only small quantities and the principal constituents, the rare earths, were largely discarded. Gradually, however, the rare earths have developed uses of their own and today have left the thorium far behind in value. Occurrence Monazite was first produced commercially about 1886, in North Carolina, where it was collected in small sluices by farmers who found it in stream beds on their land. The deposits were later exploited on a larger scale, but were mostly abandoned in a few years, when monazite from Brazil came upon the market in far larger quantities. Domestic production ceased entirely in 1906. The Brazilian source is still active, together with Indian, Dutch East Indies, and Australian deposits. Several other localities in the United States have yielded monazite, but none of these has produced commercially as yet. Monazite occurs originally in pegmatite~ and gneisses, through which, unfortunately, it is scattered in highly dispersed form. All commercially useful deposits consist of transported monazite sands liberated by erosion and concentrated by the action of water, which has sluiced away lighter materials and concentrated the heavy (D = 5.0 to 5.2) grains of monazite, together with ilmenite, zircon, garnet, and other dense minerals. The Carolina deposits were in stream beds; most of the other deposits mentioned are on or near the seashore, where the action of the waves has served to concentrate the monazite. In most cases today, the sands are worked to obtain the ilmenite and zircon, as well as monazite. The minerals are separated by means of sluices, dry tables, and magnetic separators, and each is finally obtained nearly pure. No crushing or grinding is necessary. The concentrates are shipped in fiber bags. Composition of Monazite As Table I illustrates, monazite is the anhydrous orthophosphate of the cerium Table i.—Typical Analysis of a Monazite Sand (India). Per Cent Thorium oxide............................. 8.1 Cerium oxide.............................. 30.6 Lanthanum oxide........................... 15. 7 Neodymium oxide.......................... 10.5 Praseodymium oxide........................ 2. 9 Samarium oxide............................ 1.0 Europium. gadolinium, and terbium oxides.... 0.7 Yttrium oxide.............................. 0.4 Dysprosium, holmium, erbium. thulium, ytterbium. and lutecium oxides................. 0. 1 Silicon oxide............t................... 2.4 Calcium, aluminum, and iron oxides.......... 1.0 Uranium oxide............................. 0.3 Phosphorus pentoxide....................... 26. 2 a The values given for the rare earths following samarium are approximate. being based upon analyses of concentrated fractions derived from monazite. The composition given represents Travancore monazite carefully freed from other minerals. goup of rare-earth elements. A small amount of yttrium and terbium group phosphate is also present.* All the rare-

Jan 1, 1948

By R. Philip Hammond

Monazite has had a Cinderella-like history. Although nearly go per cent pure rare-earth compound (rare-earth phosphate) it was sought at first not for the rare earths but for the sake of a minor constituent—thorium. The thorium, essential for the Welsbach gaslight mantle, was present in only small quantities and the principal constituents, the rare earths, were largely discarded. Gradually, however, the rare earths have developed uses of their own and today have left the thorium far behind in value. Occurrence Monazite was first produced commercially about 1886, in North Carolina, where it was collected in small sluices by farmers who found it in stream beds on their land. The deposits were later exploited on a larger scale, but were mostly abandoned in a few years, when monazite from Brazil came upon the market in far larger quantities. Domestic production ceased entirely in 1906. The Brazilian source is still active, together with Indian, Dutch East Indies, and Australian deposits. Several other localities in the United States have yielded monazite, but none of these has produced commercially as yet. Monazite occurs originally in pegmatite~ and gneisses, through which, unfortunately, it is scattered in highly dispersed form. All commercially useful deposits consist of transported monazite sands liberated by erosion and concentrated by the action of water, which has sluiced away lighter materials and concentrated the heavy (D = 5.0 to 5.2) grains of monazite, together with ilmenite, zircon, garnet, and other dense minerals. The Carolina deposits were in stream beds; most of the other deposits mentioned are on or near the seashore, where the action of the waves has served to concentrate the monazite. In most cases today, the sands are worked to obtain the ilmenite and zircon, as well as monazite. The minerals are separated by means of sluices, dry tables, and magnetic separators, and each is finally obtained nearly pure. No crushing or grinding is necessary. The concentrates are shipped in fiber bags. Composition of Monazite As Table I illustrates, monazite is the anhydrous orthophosphate of the cerium Table i.—Typical Analysis of a Monazite Sand (India). Per Cent Thorium oxide............................. 8.1 Cerium oxide.............................. 30.6 Lanthanum oxide........................... 15. 7 Neodymium oxide.......................... 10.5 Praseodymium oxide........................ 2. 9 Samarium oxide............................ 1.0 Europium. gadolinium, and terbium oxides.... 0.7 Yttrium oxide.............................. 0.4 Dysprosium, holmium, erbium. thulium, ytterbium. and lutecium oxides................. 0. 1 Silicon oxide............t................... 2.4 Calcium, aluminum, and iron oxides.......... 1.0 Uranium oxide............................. 0.3 Phosphorus pentoxide....................... 26. 2 a The values given for the rare earths following samarium are approximate. being based upon analyses of concentrated fractions derived from monazite. The composition given represents Travancore monazite carefully freed from other minerals. goup of rare-earth elements. A small amount of yttrium and terbium group phosphate is also present.* All the rare-

Jan 1, 1948

By W. H. Andrews

DEFINITION OF BAUXITE The term "bauxite" (1) dates back to 1821, when it was assigned to a deposit of red earthy material outcropping near the village of Les Baux in Southern France. Chemical analysis indicated the presence of aluminium oxide, iron oxide and water. Deposits of bauxite are widespread throughout the world although the major developments occur within 30 degrees of the Equator. Essentially bauxite is the product of weathering and leaching of a variety of sediments or rocks, generally in a high-rainfall tropical or sub-tropical climate, resulting in the enrichment of the aluminium oxide content. It is characterised by the presence of one or more of the minerals, gibbsite, boehmite, and diaspore. The other constituents are usually clay, (typically kaolin), hematite and/or goethite (iron-oxides), anatase (titanium oxide), and possibly silica as quartz. A variety of minor elements may be present, such as calcium, magnesium, phosphorus, vanadium, gallium, manganese, and many others in very small quantities. Organic compounds are normally present from development in association with a soil horizon where vegetation may be encouraged by the high rainfall necessary for bauxitisition. The physical form depends upon the geological history of the deposit and correlation also exists with the mineralogy. Older deposits which have been subject to burial are invariably hard and compact with the alumina predominantly occurring as boehmite or diaspore, while the more recent, surface deposits are frequently less compacted and gibbsite is the dominant alumina mineral. In these later deposits, the physical form can vary from the fine red soil (terra rosa) of Jamaica to the Weipa pisolites to the cemented Arkansas type. The presence of concretionary structures is an important aid in identification in the field.

Jan 1, 1984

By Cam Thomas, Steve Bernard

Various types of blasting instrumentation can be used in the field to analyze conditions before, during and after a blast, and to indicate what changes need to be made. When different types of measurements are combined together, the blaster can end up with useful data that can pinpoint the source or sources of problems and what changes have to be made. This paper outlines two case examples where blasting instrumentation was used to overcome problems in separate quarry operations. Extensive measurements with different systems led to significantly improved blasting results.

Jan 1, 2012

By Frank W. Osterwald

Violent, spontaneous destruction of coal faces and ribs during, what are commonly called, bumps endangers and at times destroys life and property in mines of the Book Cliffs coalfield, Carbon County, Utah. Because these mines supply much of the coking coal for the West Coast steel industries, mining is necessary, although costs are high and operating conditions are very difficult at times. As operations continue, mining will go to greater depths, and the difficulties will increase. Whether or not mining can be continued successfully depends in part on whether or not incidence of bumps can be controlled successfully. For this reason, the U.S. Geological Survey, at the request of and in cooperation with the U.S. Bureau of Mines, undertook a study of the Sunnyside No. 1 mine to determine what geologic factors were related to the incidence of bumps. This report presents the preliminary results of that study and indicates that some observable geologic features in the mine may be related directly or indirectly to bumps, and that other features may be used to infer stress distribution around workings that will aid in design of roof support measures. Coal is mined in the Sunnyside No. 1 mine from depths as great as 2500 ft by room-and-pillar methods. The surface topography is rugged with many steep cliffs and deep canyons, hence the load on the coal varies greatly within short distances. Much of the Sunnyside coal is under high stress, and while being mined, it shatters continuously' and falls from the face. Continuous shattering (bumping) makes mining easy, but if the shattering is interrupted, greater stress is built up and violent bumps may result when the coal is mined.

Jan 4, 1962

By Patrick Cloutier

Presentation objectives ? Introduce discrete-event 3D computer simulation as a tool to design, improve and optimize construction projects: ? Describe a real typical construction project planning issue. ? Present an applied use of simulation to solve this issue. ? Detail benefits of using simulation versus traditional planning methods.

Aug 1, 2013

By L. Chunpongtong

ABSTRACT Oil sands production occurs on a massive scale, making orebody estimation a challenge. In rainy conditions, operators can have difficulty accessing ore at the mapped location. Without enough inventory as a buffer, the high-cost stockpile is depleted quickly, necessitating the removal of significant amounts of overburden and interburden to meet plant feed requirements. The inventory curve—a plot of ore inventory on a period-by-period basis—plays an important role in selecting an appropriate scheduling scenario. This paper presents a programmable method for creating an inventory definition by using a pit optimization tool.

Jan 1, 2014

By H. R. Maggard, C. M. Bollinger

Solving the problem of detecting underwater explosions from "dynamite fishing" can be done by using a system of sonobuoys programmed to detect the acoustic waves from underwater explosions. The system includes three anchored sonobuoys, which have radio communication to a central station. Each sonobuoy will detect the direction the blast occurred, and then send the magnitude of the acoustic waves and the blast direction to the central station where the blast distance will be calculated. The central station can the send the coordinates to the authorities who can find the location using GPS systems onboard their boats.

Jan 1, 2004

By G. H. Glos

There was a time when an occasional failure of a tailings embankment was considered an acceptable risk associated with mining activities. This is not the case anymore. A major tailings failure today could result in the indictment of mine officials, huge fines and a possible site closure due to the loss of operating permits. As a result of this changed operational environment, tailings disposal facilities must be operated with these potential consequences in mind. Physical controls for tailings embankments are prohibitively expensive. However, the nuclear industry has developed a system of administrative controls as an alternative to physical controls. Administrative controls may be defined as control of actions, through organizations and management, using written procedures, record keeping, review and audit to assure operation of a facility in a safe manner (10 CFR 50). Administrative controls can reduce the cost of operating tailings impoundments, as well as increase the level of confidence in these facilities.

Jan 1, 1999

By J Bresnahan, D Kepert, R Murray, R Neroni

Stratigraphy of the Hamersley Province in Western Australia, featuring alternating units of banded iron formations and shales with contrasting electrical properties in a mostly gently undulating shallow-dipping layered geometry, is particularly favourable to airborne time-domain electromagnetic mapping techniques. Manipulated vertical cross-sections of modelled conductivity obtained from laterally constrained one-dimensional inversion of SkyTEM304 data enable the exploration geologist to interpret weathering profiles, shallow-dipping stratigraphy and steep structures, all of which are crucial aspects of bedded iron ore deposits genesis models.The Cobra Project is located 14 km east of the NNW-trending Menindee Fault Zone, which defines the western margin of the Hamersley Province, Western Australia. The region comprises an extensive plateau of Brockman Iron Formation cut by a series of horst and grabens with a regional dextral strike-slip component. The 150° striking horst and grabens and associated 060° striking conjugate faults have approximate frequencies of 400 and 2000 m, respectively, and control the bulk of the iron mineralisation. Syn to late 150° trending dykes in part intrude the faults.In the Cobra region, elucidating the structurally dislocated stratigraphy without closely spaced drilling is very challenging. Geological mapping is hindered by the paucity of mappable stratigraphic markers within the banded iron formations and kinematic indicators. Airborne magnetic and remote sensing data sets highlight the dense lineament network, but provide limited assistance in quantifying relatively small apparent displacements, or distinguishing faults from dykes with reasonable confidence.Interpretation of modelled conductivity cross-sections generated from laterally constrained one-dimensional inversion of airborne electromagnetic method (AEM) data offers invaluable insight where the quality of mapping or drilling is wanting. Subsequent targeted field checking and infill drilling validated the geological model interpreted from the integration of these data sets.The AEM technique alone cannot decipher the complex geological environments often present in the Hamersley Province but can facilitate effective iron ore exploration by focusing precious field time and assisting structural and stratigraphic interpretations in areas with sporadic and shallow geological data.CITATION:Murray, R, Neroni, R, Kepert, D and Bresnahan, J, 2017. Using airborne electromagnetics to solve a structurally complex geological puzzle in the Hamersley Province, Western Australia, in Proceedings Iron Ore 2017, pp 269–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By J. Shang, P. Howarth, B. Morris

Tailings from the nickel refinery in Copper Cliff, Ontario, consist of fine silicates mixed with a variable amount of conductive and magnetic minerals mainly associated with sulphides and iron oxides. Subsequent oxidation of sulphide- rich phases within the tailings results in the formation of an acidic leachate that may contain significant concentrations of trace metals. Mapping the spatial distribution of regions of higher sulphide concentration therefore provides insight into the distribution of the acidgenerating potential within the tailings. Electrical conductivity is constrained by two parameters — the concentration of metallic sulphides and the ionic concentration of acid in groundwater. Magnetic susceptibility is directly related to the pyrrhotite and magnetite content. It is proposed that combining information derived from airborne electromagnetic and magnetic surveys can provide an indication of metallic sulphide distribution. Preliminary investigations of airborne electromagnetic and magnetic data acquired concurrently over the sulphide-rich Copper Cliff tailings site reveal that these parameters can provide information on mine tailing extent and permit separation of tailings with varying compositional and alteration levels. Airborne geophysical data provide information about the subsurface while a digital elevation model (DEM) and hyperspectral imagery record surface conditions. Integration of the two data sets can reduce ambiguity when interpreting mine tailing distributions and their subsequent alterations.

Jan 1, 2001

Provide the mining industry with a simple, accurate and readily available means of measuring the gas flow from pipe outlets such as gob holes Approach The Bureau of Mines conducted laboratory studies to establish correction or method factors for anemometers when used to measure gas flow from pipe outlets. Using the Anemometer Anemometers are used by the mining industry to make air velocity measurements in mine entries. Although the instrument has no appreciable influence on the airstream in mine entries, especially since the cross-sectional area of an entry is much larger than the cross-section of the anemometer, correction or method factors are used to correct the center line anemometer velocity to average velocity. This adjustment is made because the air velocity in a mine entry is highest in the center and lower at the sides. Anemometers can be used to measure gas flow from small diameter pipe outlets; however, since the instrument diameter is much larger than one-sixth of the pipe diameter, it will influence the air-stream from these small outlets. Resulting velocity measurements are erroneously high by as much as 30 percent. Method factors must be applied to such anemometer measurements taken at pipe outlets. Through a research investigation the Bureau of Mines established a set of method factors for center-line anemometer readings taken at the discharge end of 4-to 8-inch diameter pipes. These method factors were combined with method factors which were developed by the National Coal Board of Great Britain for 12-to 30-inch diameter pipes. The anemometer was mounted on the end of a short rod and held against the pipe for support except on the 4-inch pipe where the instrument was started and stopped remotely to prevent hand interference with the air-stream during measurements. Method factors were determined by comparing the anemometer measurements at the pipe outlet to the true average airflow which was simultaneously determined upstream by venturi measurements. Consequently, a method factor is nothing more than the ratio of the true velocity to an anemometer measurement.

Jan 1, 1987

By Joseph Haid, om, Rio Yang, Kelly Fleetwood

Some coal mining operations in the Powder River Basin are currently observing a number of blast holes detonating sympathetically within their cast blasts. Sympathetic detonation can cause poor cast results, high blast vibration levels, excessive back break and fly rock, along with a number of other undesirable blast results. The reduction or the total elimination of blast hole sympathetic detonation is of paramount importance to the coal mining companies operating in the Powder River Basin. This paper describes a systematic approach to prevent cast blast holes from detonating sympathetically through the use of the electronic initiation and expanded blast patterns. In-situ measurements outlined in this paper were recorded from pressure probes, velocity of detonation probes and near field accelerometers, along with digital images generated from a high speed CCD camera. Large diameter angled drill holes were also checked for any measurable amount of deviation by a cable type borehole measurement tool. The field measurements provided the scientific evidence, statistical data, and documentation necessary to develop a sound method or a “road map” that would minimize and in some situations prevent the occurrence of blast hole sympathetic detonation.

Jan 1, 2005

By A. Yazadni-Chamzini

Maintenance strategy selection plays a significant role in mining design. The nature of maintenance strategy selection is a complex multi-criteria decision making (MCDM) problem including both tangible and intangible parameters which are often in conflicting with each other. Moreover, when decision makers are uncertain in determining and defining the ratings and the weights of alternatives and criteria respectively, fuzzy theory provides an appropriate tool to handle the existing uncertainties. In this paper, a new fuzzy MCDM method based on the concepts of TOPSIS and AHP was proposed to evaluate the feasible maintenance strategy. The linguistic terms are employed to assess the ratings and weights. Fuzzy AHP is utilized to calculate the weights of the evaluation criteria; then, the rankings of alternatives are computed based on fuzzy sets theory and TOPSIS. A real world case study is presented to illustrate a potential application of the proposed model.

Jan 1, 2012