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By Lamont G

The significance of blasthole stemming in determining blasting efficiency has been extensively studied for small diameter holes using gelignite explosives. Recent developments in blasting technology with the use of large diameter holes and low cost blasting agents have not included studies of the effectiveness of different types of stemming materials. A review of previous measurement techniques and the relevance of these earlier results to present stemming practice is presented in this paper. A survey of operating mines in Australia provided information for this analysis. The value of stemming in reducing blast noise and improving blasting efficiency is generally accepted but the use of bulk-loaded explosives in underground operations has resulted in the practice of eliminating the use of stemming material.In surface operations drill cuttings are used for stemming on the basis of availability rather than efficiency in providing resistance to movement. The development of laboratory testing techniques, based on noise level and borehole pressure measurements, to evaluate the relative efficiency of different types of stemming materials is described. The results of an extensive series of tests with ANFO explosive showed similar trends tothose obtained from earlier published results with gelignite type explosives. Conclusive quantitative results on the relative effectiveness of different stemming materials will require minor modifications to the existingequipment. Observations and the results of pressure measurements indicated the presence of shock wave effects which caused the ejection of the top section of the stemming column when using coarsely fragmented material.

Jan 1, 1979

By A. Jennings

[ ] In November 2005, Essroc Cement, part of the Italcementi Group, commissioned a long overland conveyor at their Nazareth plant in Pennsylvania. This conveyor, tagged CV-105, was designed to transport 1000 tph of limestone from the quarry to the kiln, and 400 tph of hot clinker (at 300°F) at back from the kiln to a handling facility about halfway back. Conveyor CV-105 is 8969 ft (2733 m) long. It gains 152 ft (46 m) of elevation in the first 1570 ft (480 m), then is mostly flat for the remaining 7400 ft (2250 m) (Figure 1). After the limestone is discharged at the head pulley, hot clinker is loaded onto the return side of the belt. This clinker can be discharged at one of two locations.

Jan 1, 2012

Energy Dissipation in Long-Distance Slurry Pipelines

Sep 13, 2010

Appropriate roof control is the most important requirement in underground coal mining and, in the case of longwall panels or second mining in room and pillar extractions, this can be simply expressed in terms of good and predictable roof caveability. Studies of roof caveability have been undertaken in many coalfields around the world. Most of their conclusions. however, are directly related to the mining and geological conditions experienced in these areas and as a result, may not be applicable to the conditions encountered in the Appalachian coalfield. Furthermore, some of these studies appear to be theoretical and conceptual, ignoring many important parameters of the geological environment, whereas others rely heavily on geological information but lack a rigorous foundations upon which quantitative design guidelines can be built. The objective of this study is to analyze caving and mass deformation characteristics above longwall panels in Appalachia and includes: - Analysis of the effects of the geological and geomechanical characteristics of the strata on the caving height and the bulking of the caved-material. - Testing of the applicability of the various theoretical and empirical models of roof caving. Formulation of a numerical around- deformation model for ion-elastic material behavior.

Jan 1, 1986

By David M. Langlais, Krystle Pelham

"Explosives used in blasting operations, natural and anthropogenic sources such as septic systems,fertilizers, and decomposing vegetation can potentially contaminate groundwater with nitrate in thevicinity of construction sites and make identification of blasting impacts difficult. Blasting operationsfor a private construction project in Windham, New Hampshire were indicated as the source of water quality impacts to private drinking water wells prompting the New Hampshire Department ofTransportation (NHDOT) to implement a proactive approach to limit the potential for impacts fromblasting for ongoing NHDOT projects. NHDOT has developed a baseline drinking water monitoringprogram designed to detect potential impacts and to ensure alternative drinking water is providedthroughout the construction phase of projects. In 2013, the U.S. Geological Survey (USGS) andNHDOT began a study to determine the source and fate of nitrogen compounds near blasting sites using a combination of isotopic, time series, geochemical, hydrologic, and geologic data. Approximately 1.75 million cubic yards (1.33 cubic meters) of rock were removed by blasting in several locations for roadway construction at a major highway construction site in southern New Hampshire."

Jan 1, 2016

By Frank Sames

Most Blasting Programs are developed focussing on the environmental impact with respect to blast vibration and airblast. Compliance with existing regulations or policies limiting the immissions are generally achieved through constrains in the blast design, or monitoring programs. Efficient monitoring programs combine compliance monitoring and blast assessment. Signals, which are obtained in the area of direct influence of the seismic source, can contain valuable information about the blast design parameters. Techniques to analyze blast vibration signals have advanced and can assist in understanding the contribution of individual blast parameters to blast vibration and airblast. Advanced signal analysis encompasses magnitude analysis, Fast Fourier Transforms (FFT) and frequency scans in the frequency domain, as well as filtering in the time domain. Through examples, the advanced signal analysis techniques and their limitations are described and discussed, showing the impact of blast timing, timing accuracy, charge configuration and the geology dependent transmission behavior. Optimization criteria and pragmatic monitoring programs can be developed on the basis of the most influential blast parameters. In addition, however, safety and the cost efficiency of the blasting program are essential to the success of an operation. That is where advanced signal analysis techniques can interface with blast planning, computer assisted modeling and information systems. A valuable process can be developed to ensure compliance with existing regulations and efficient risk management for mining operations, while tracking cost and supporting operational decisions. A conceptual blasting information system is presented.

Jan 1, 2000

By Richards S. M

The abundances and abundance relationships of lead, zinc, copper and silver in the major sulphide lenses at Broken Hill are examined, and their possible geochemical significance discussed.When expressed as atoms per cent, zinc is the most abundant base metal throughout the whole .group of orebodies, the highest average lead: zinc ratio (No. 2 lens) being about 0·45, the lowest (No. 1 lensZinc Lode group) being in the 0·12-0 ·14 range. Lead and silver are clearly higher in the lower two orebodies, but the abundance of zinc shows no apparent relationship with stratigraphical position. Among the base metals copper is conspicuously low and remarkably uniform, a feature noted in other conformable orebodies.Although, as has been recognised for many years, abundances of silver and lead, and lead and zinc, are sympathetically related, correlation within the pairs is variable and generally of low degree. Silver and lead show distinctly the better correlation, particularly in No. 3 lens. On the basis of lead: zinc ratios, No. 2' and No. 3· lenses, on the one hand, and the No. 1 lenses, Rhodonitic and Siliceous Zinc Lodes on the other, constitute two groups. However on the basis of silver : lead ratios, No. 3 lens stands alone, No. 2 lens showing clear affinities with the higher layers. Ternary relationships between copper-zinc-Iead and silver-zinc-Iead emphasize the very close constitutional relationship between the No. 1 lenses and the two "zinc lodes".The possible implications of these relationships are then discussed in the light of the' two principal theories-hydrothermal replacement or chemical sedimentation-held for the formation of the Broken Hill ores. It is pointed out that the ratios of the four metals in the ores are rather different from those found in most igneous and sedimentary rocks, and in seawater. For 'example, whereas copper and zinc are present in almost equal amounts in most terrestrial materials, copper in the ores is only about one-hundredth of the amount of zinc. Lead has increased somewhat, but the ratio of silver to lead has fallen; in spite of its recognition as a source of silver, the Broken Hill lode is impoverished in silver with respect to lead as compared with most common terrestrial materials.No solutions are offered to these prob'lems of abundance. Rather it has been the aim of the work to provide data, and to demonstrate the...

Jan 1, 1961

By S. H. Ward, R. A. Barker

THE Juniper Prospect is in Carleton County, N. B., at approximately 46" 31' north latitude, 67" 20' west longitude. During the summer of 1955 an area in west-central New Brunswick was selected for aerial electromagnetic prospecting with American Metal Co.'s helicopter-mounted equipment. Generalized, small-scale government geologic maps had suggested that this area was located along the western border of the northeast-trending granitic backbone of northwestern New Brunswick and might be underlain by the Ordovician-Silurian sediments and volcanics that are the host rocks for the recently discovered sul-fide deposits of the Bathurst-Newcastle district. The helicopter electromagnetic equipment located an anomalous conductive area, coincident with a small aeromagnetic closure, about five miles west of the town of Juniper. Subsequently 30 mining claims (total area about 6600 x 8000 ft) were staked and company personnel conducted geological, geophysical, and geochemical investigations on the property. The claims and immediately contiguous areas were mapped geologically, and an area of about 2000 x 4000 ft was soil-sampled and also surveyed by ground electromagnetic and gravity methods. Finally six diamond drillholes, totaling 3500 ft in length, were drilled to test the anomalous conditions discovered by the several exploration techniques used. The discovery of base metal sulfides during drilling was a technical success for the exploration methods, but the quantity of sulfides was too small to be profitably exploited.

Jan 1, 1959

By Warren L. J

The effectiveness of shear-flocculation as a method for upgrading simple mixtures of ultrafine (1-11 \lm) scheelite and garnet was evaluated. Statistical methods were used in the design and analysis of the main test program.The stirrer speed, stirring time, and initial weight ratio were all found to have significant effects on both the recovery and grade of the floes produced. The particle sizes also had an effect on the final grade. There were several important interactions between factors which also affected the results. Optimum conditions for shear-flocculation were established, and under these conditions about 80 per cent of the scheelite could be recovered at a grade which depended on the composition of the starting mixture. Starting with mixtures containing 10 and 50 per cent scheelite, the best final grades were between 20 and 50 per cent and between 70 and 90 per cent respectively, the actual value depending on the particular combination of particle sizes.

Jan 1, 1977

By Tapio Leskinen

"l. IntroductionA reliable sampling system is the basis for an on-stream analyzer. This was realized in Outokumpu company when the development work of the Courier 300 On-Stream X-ray analysis system was started. Because Outokumpu Oy is a mining and mineral processing company, its engineers have been able to thoroughly test sampler prototypes in actual operating situations. The sampler development has been going for several years in close co-operation between company's concentrators, the Institute of Physics and the Instrument Division of Outokumpu Oy. The most active part of the work was done between 1969- 1972. Besides the reliable operation of a sampler special attention was paid to the representatively of the samples taken by the samplers. 2. The Courier 300 Sampling SystemThe sampling system comprises up to fourteen sampling circuits in one Courier analysis system. Each circuit consists of the following components:1. Primary sampler 2. Secondary sampler 3. Cleaner screen 4. Feeding tank5. Sample cell6. Timer-controlled sampler7. Pumps, sumps and pipesSecondary samplers, cleaner screen and feeding tanks are included in the secondary sct1npling system. The sample cells are located in the spectrometer cabinet of the analyzer."

Jan 1, 1976

By R. L. Fullman, J. W. Cahn

A method is derived for obtaining the distribution of sphere diameters and plate thicknesses (or pearlite spacings) from size distribution functions obtained along randomly oriented lines. The method described offers several advantages over existing methods. IT is often of interest to measure not only the average particle size but also the distribution in sizes of particles dispersed in an opaque material, such as an alloy. Particles of a single size will exhibit a range of apparent sizes on the plane of polish. If the sample contains a distribution of particle sizes, the distribution of observed sizes on the plane of polish is related to the distribution of actual particle sizes by an integral equation, For example, a distribution of sphere sizes, N(r),

Jan 1, 1957

By John G. Payne

The Pebble deposit contains three contiguous zones. In the Pebble West zone, granodiorite stocks intrude gently warped volcanosedimentary rocks that had been intruded by diorite sills and two felsic intrusion breccias. In the Central zone, volcanosedimentary rocks are cut by diorite and granodiorite sills; the latter are genetically associated with the granodiorite stocks. In these zones, widespread potassic alteration consists of brown biotite and K-feldspar, with abundant quartz-carbonate-sulphide vein stockworks. Chalcopyrite/pyrite ratios range from 2/1 to 1/20. Diorite hosts the highest-grade mineralization, with much of it being disseminated. Patchy, later phyllic alteration is moderate and commonly depleted in copper. The Pebble East zone occupies a granodiorite stock and intruded host rocks below an eastwardly thickening wedge of barren Tertiary volcanic and sedimentary rocks up to 600 m thick. Brown biotite alteration and copper mineralization are strong, with chalcopyrite/pyrite ratios commonly over 1/1. The zone extends to a depth of at least 1200 m below surface; some drill holes bottomed in strong mineralization. Later, weak to moderate sericitic alteration removed some chalcopyrite and locally remobilized gold. The Pebble deposit has a Measured/Indicated resource of 3 billion tonnes grading 0.28% Cu, 0.32 g/t Au and 0.015% Mo (= 0.5% copper-equivalent) and an Inferred resource of 1.13 billion tonnes grading 0.30 g/t Au, 0.27% Cu and 0.015% Mo (0.55% copper-equivalent). The Pebble East zone has an Inferred resource of 2.13 billion tonnes grading 0.55% Cu, 0.34 g/t Au, and 0.037% Mo (0.97% copper-equivalent). The Pebble East zone is open to the east and to a lesser extent to the north, south, and to depth.

May 1, 2006

By Corby G. Anderson

"Laboratory testing, plant optimization, and the interpretation and application of metallurgical technologies can be tedious, time consuming and costly. This paper outlines the use of proven statistical design of experimentation software for rapid laboratory testing and optimization of operating plants with limited representative sample utilization. This results in less costly required testing, a more thorough understanding of results and the ability to simultaneously optimize several variables and outcomes at once. At the Center for Advanced Mineral and Metallurgical Processing (CAMP), this testing methodology has been used successfully in many metallurgical development and plant optimization projects thereby confirming its real world utility and application. Accordingly, several applied examples in flotation and hydrometallurgy will be outlined in this paper. This will include flotation testing of a copper gold ore, flotation testing of a copper, cobalt and gold ore, optimization of an industrial hydrometallurgical jarosite circuit and optimization of industrial nitrogen species catalyzed pressure leaching of a copper enargite concentrate.INTRODUCTIONWhile flotation technology is now 100 years old, the testing, interpretation and application of lab results can be tedious, costly and time consuming requiring extensive sample collection and preparation. In addition, recent applications like hydrometallurgical pressure leaching and associated unit operations, such as precipitation, still remain more of an art than a quantifiable science. This paper will elucidate the application of STAT-EASE Design-Expert software to minimize required laboratory testing while rapidly optimizing multiple results and outcomes in a statistically valid manner. The STAT-EASE program is based on proven design of experiment fundamentals. In this paper, the real world application of this methodology for lab testing, plant optimization and process development will be elucidated."

Jan 1, 2006

By S. E. Pérez-Fontes

An experimental study on the oxidation of chalcopyrite (CuFeS2), pyrite (FeS2), covellite (CuS) and chalcocite (Cu2S) particles was conducted by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The oxygen concentration in the process gas was set to 40% and 70% (by volume) and a heating rate of 40°C/min was used. Response variables included the temperature of incipient reaction, the total exothermic heat of reaction, particle mass, morphology and mineralogy of the reacted particles. Based on the experimental data and phase stability calculations, reaction mechanisms were proposed to represent the behavior of the particles during oxidation. The reaction mechanisms were verified by X-ray diffraction (XRD) analyses of the oxidized particles and by thermochemical and mass balance calculations to reproduce the DSC and TGA data. Overall kinetic models were developed to represent the evolution of the exothermic heat of reaction as a function of time.

Jan 1, 2007

By M. W. Hildyard

A blast was engineered close to a tunnel in a deep-level mine with the purpose of studying the wave interaction with the tunnel. Numerical modelling of seismic wave propagation was used in both the forward planning and the back-analysis of this experiment. This paper presents the forward analysis. A likely model for a propagating blast was investigated and developed. This model predicts the influence of the velocity of detonation of the blast and the rise-time of the blast on the radiation pattern, and hence on the expected positions of maximum velocity at the tunnel surface. An attempt was made to quantify the parameters of the blast model, using waveform data from two other blast experiments. The blast model caused particle velocities which were an order of magnitude lower than these measured velocities. Large values for blast pressure were required to match the amplitudes of the recorded velocities. An alternative ?effective? source with a similar mechanism but increased diameter was proposed to account for the higher velocities. It was established that distant velocities scale with the square of the borehole diameter. A calibration blast at the experimental site was also modelled. Agreement in the waveforms was not sufficient for conclusive statements to be made about the validity of the source model. However, the modelled waveforms show an encouraging correspondence with some measured waveforms. This gave confidence that the model could be used to examine wave propagation around the tunnel, and allowed a scaled source to be developed for forward analysis of the main experiment.

Jan 1, 2001

By Bruno Gemmi

The objective of the ? 200 million ($280 million) project Parma Railways Station-Urban Transformation was the reconnection of the North and South parts of the town by constructing an 80 m (250 ft) wide sunken artery passing under the four double railway tracks of the station without any impact on train traffic. The site of the project, adjacent to the Parma River, presented water seepage problems at any excavation depth. The use of conventional large diameter bored pile machinery was not allowed by the Railway Authority because equipment dimension and construction phases do not comply with train traffic safety regulations. Foundations for the bypass were thus constructed by minipiles nested into jet-grouted soil using machinery operating within the existing head room and at a safe distance from the tracks. Jet-grouting treatment reached depths of 25 to 28 m (80 to 90 ft) from tracks? grade and embedded minipile-heads were terminated at 2 to 3 m (6.6 to 10 ft) below grade. Load tests on minipiles were pushed to failure. Failure occurred at a 240 t (265 t) load without breakage of the bond between the jet grouted soil and the minipiles. A 0.93 MPa (135 psi) shear resistance ??? between minipile steel casing and the jet grouted soil was measured prior to the failure of the steel casings. Overall measured foundation settlements were well within expected values and were considered insignificant.

Jan 1, 2011

[COUNCIL FOR 1991/92 President R.D. Beck President Elect JP. Hoffman Vice Presidents Senior Junior Dr H. Scott-Russell J.A. Cruise Immediate Past President Honorary Treasurer H.G. Mosenthal J.A. Cruise Members of Council Dr N.A. Barcza G.A. Brown B.R. Broekman Prof. RJ. Dippenaar B.R. Fleetwood* J.S. Freer P.R. Janisch P.J. Knottenbelt Dr J. Lurie R.P. Mohring *Co-opted K.C. Owen P.D.K. Robinson D.A.J. Ross-Watt P. Smith K.A. van Gessel DJ. van Niekerk P. van Schaardenburgh* CJ.C.J. van Vuuren* P.M.T. White]

Jan 1, 1992

By Garry Keizer

The Cortez gold mine is located in Lander County, NR, about 130 km (80 miles) southwest of Elko. Cortez Gold Mines (CGM) is a joint venture between Placer Dome US Inc. (60% operator) and Kennecott Corp. (40%). The claims that supply oxide and refractory ore feed to the Cortez milling facility are located in both Lander and Eureka counties. These include the Cortez and Horse Canyon deposits, all operated by the joint venture. Other deposits outside the CGM claim area include Fire Creek, Buckhorn, Gold Bar and Tonkin Springs. These deposits all occur along the Battle Mountain-Eureka Trend. History Mining in the Cortez district began in 1862 with the discovery of high-grade silver ores. Grades in the hundreds of ounces per ton occurred in an area 7 km (4.5 miles) southeast of the current CGM mill site. Underground mining through the Garrison and Arctic tunnels provided the bulk of the ore production between 1864 and 1895. To a lesser extent, the Mill Canyon area also supplied ore until 1930.

Jan 1, 1993

By M. Kuchta, A. Newman

LKAB’s Kiruna Mine, located in northern Sweden, produces about 24 Mton of iron ore yearly using sublevel caving. For efficiency, the mine must deliver planned quantities of three ore products. We use mixed integer programming to schedule Kiruna’s operations, specifically, which production blocks should be mined, and when they should be mined to minimize deviations from planned production quantities while adhering to mining restrictions (e.g., sequencing). A new production block database and a well-formulated mixed integer programming model dramatically reduce the size of the original problem; in less than ten minutes we generate five-year schedules with time fidelity of months.

Jan 1, 2002

A Study of Extracting Vanadium from Stone Coal Using Cyclic Oxidation

Sep 13, 2010