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By Paul Sterk

In underground mining a great deal of time, money, effort, and resources have been used in the effort to minimize blast-induced damage. This damage occurs to the back, ribs, and pillars when the energy of the explosive is released back into the rock due to over confinement or the overloading of explosives in the perimeter holes. This damage can result in roof falls, dilution of ore, excessive rock bolting, scaling, screening, shot-creteing and other safety and support issues.

Jan 1, 2003

By R Garzon

For resources projects with healthy net present value (NPV) and low cash flow volatility, conventional discounted cash flow (DCF) analysis will continue to provide the dominant investment decision-making criteria. However, DCF analysis can be biased because it often applies a single risk-adjusted discount rate (RADR) to compare the value of projects with different risk characteristics. Many of the difficulties with DCF modelling arise from analystsÆ inability to determine appropriate risk discounts and to estimate expected spot prices inputs for the commodities produced over the life of the project. Modern asset pricing (MAP) is a very valuable complement to DCF analysis in addressing some of these issues. Most papers dealing with MAP, however, while academically rigorous, tend not to be explicit in terms of practical application of this methodology in routine project evaluation. This paper has the objective of reviewing the MAP methodology and of demystifying its complexity, by providing a simple but realistic step-by-step evaluation of a mining project, comparing its DCF and MAP NPV values. The paper concludes that MAP provides a minimum, risk-adjusted æfloorÆ value, thus representing a valuable complement to any DCF valuation.

Jan 1, 2007

By Louis J. Mittoni

"It is well known that gas injection systems can exhibit a wide range of dynamical behaviours, ranging from linear periodic bubbling through to highly complex turbulent jetting. Recently, it has been observed that an important intermediate regime exists under certain system conditions, where the dynamics are complex in nature yet predictable for short time periods. This paper reviews the evidence to support the above hypothesis, and discusses the invariant quantitative measures such as density, return maps, Lyapunov exponent and dimension which may be used as pattern recognition features in a mOnitoring and control strategy.INTRODUCTIONThere has been a great deal of research on the submerged injection of gases into liquids. This interest is primarily due to the large number of applications in the pyrometallurgical and chemical engineering industries. Gases are typically injected into liquids to achieve goals such as heat and mass transfer, or physical mixing and agitation. Only recently though has the possibility of using the evolution of the gas dynamics as a probe to internal system conditions been raised [1, 2].At very low gas injection rates and small upstream chamber volumes, gas normally disperses in the form of stable bubbles of constant volume [3]. With increases in gas flow rate, the dynamics become more complex, bifurcating into double bubbling, multiple bubbling and complex coalescence behaviour. Irregularities measured in pressuretime series acquired upstream of the injection port under these complex conditions have usually been treated as bothersome noise or contamination to be filtered from the signal and ignored in the analysis. These irregularities, however, may contain physically interesting and useful information on the system from which they were produced if the system may be classified as deterministically chaotic [4]."

Jan 1, 1996

Reason Analysis of Impurity Containing and Technology Discussion of Quality Improvement for Low-Quality Iron Concentrate

Sep 13, 2010

By D. Minney

The quality of resin used in South African collieries is currently controlled according to South African Bureau of Standards, "SABS-1534:2002". It has however been found that resin which passed the SABS tests failed in underground short encapsulation pull tests. An investigation was therefore conducted to determine the characteristics of resins that are currently being used in collieries. A series of in situ short encapsulated pull tests was conducted to determine the effect of expired resin on support performance. The results showed that the longer the time after the expiry date the poorer the resin performance. A series of resin-torque tests has been performed using Anglo Coal's testing facility. The following parameters were investigated on different resins: Spinning speed, Mixing time, and Setting time. An attempt was also made to develop a new quality control procedure for resin. This procedure enables mining personnel to make sure that the quality of resin can provide the required support performance. The effect of spinning speed on resin performance was also investigated. The results showed the resin gelling times of resin decreases as the spinning speed increases. It is found that over-spinning with slow speed roofbolters may result in decreased bond strengths. It was found that a 30-second resin (10-second spin, 30-second hold) should never be spun more than 20 seconds, even with very slow roofbolters (100 rpm).

Jan 1, 2005

By R Sridhar, M Fe, W G. Bacon

The problems of magnetite build-up have plagued the non-ferrous pyrometallurgical industry for many years. To better understand these problems, a study was undertaken to determine the thermodynamic variables that affect the behaviour of magnetite under different smelting conditions. Equilibration studies were performed in the nickel smelting systems of matte-gas and matte-slag(silica saturation)-gas. The relationship of thermodynamic variables such as temperature, sulphur and oxygen partial pressure and matte grade on iron and magnetite activities were calculated and the significance on smelting parameters such as metal losses and partition coefficients were defined. The experimental data from this study were employed to develop practical methods which could be used to control the build up of magnetite, as well as to obtain additional metallurgical benefits. In general, a lower sulphur partial pressure and higher temperature operation was shown to enhance the metallurgical benefits of nickel smelting by decreasing the magnetite activity. Operating in this manner can also have added benefits such as higher metal recoveries, more efficient vessel utilisation and efficiency and lower smelter emissions at equivalent or higher primary furnace matte grades.

Jan 1, 2000

By Pierre Marcotte

Jackleg rock drills expose their operators to high hand-arm vibration levels. To address this problem, an antivibration handle has been developed. The antivibration properties of the handle were achieved through a suspension based on a hinge design, achieved with a torsion spring and o-rings. To provide some bench marking for this new handle and to follow the evolution of its performance over time, a test bench was developed to characterize the vibration emission values of jackleg drills under controlled operating conditions. Testing of four antivibration handles on the test bench have shown reductions of the overall weighted acceleration level in the order of 54 % to 60 %, with most of the attenuation occurring in the zh-axis at the rock drill percussion frequency.

Jan 1, 2008

By Z. Zhang, R. G. Reddy

Viscosities of industrial lead slags with various compositions were measured as a function of temperature using a Brookfield viscometer. Based on the experimental data from this study and other investigations reported in the literature, an expression has been developed to correlate the viscosities of lead silicate slags as functions of composition and temperature. The effect of each individual slag component on the variation of the slag viscosity is identified. The composition dependency of viscosity of lead silicate slags is discussed. The calculated results using this viscosity expression are in good agreement with the measured data.

Jan 1, 2001

By C Katongo

Ground condition at No1. Shaft varies across the mine. The different ground conditions arise as a result of the differences in the rock strength and structure, seismicity and induced stresses in abutments areas. Apart from being a major cause of Fall of Ground incidents/accidents, adverse ground conditions where encountered has affected the rate of development advance as well as production. This implies that for support to be cost effective Geotechnical section has to ensure that support is designed to prevailing ground demand to ensure the safety of personnel and minimize loss of production. We have also seen changes in mining methods as a result of change in ground conditions. To avoid incurring unnecessary costs through remedial works resulting from ground deterioration and collapses of development openings due to inadequate support, the principle in engineering design is ?Do it right the First Time?, and this can only be achieved through good understanding of Geotechnical environment. The paper discusses the different ground conditions encountered in various development ends at No.1 Shaft. It also discusses the principles of ground support, failure mechanisms, types of ground support systems employed, and the different techniques used to select support systems, and quality control techniques in underground support installation.

Jan 1, 2005

By Elione Moura Carlos

O objetivo principal deste trabalho foi incorporar o resíduo de mármore no desenvolvimento de formulações de massas cerâmicas para obtenção de grês porcelanato. Foram preparadas quatro formulações da massa cerâmica variando-se as proporções de caulim, talco, feldspato, argila de queima clara e do resíduo de mármore nas misturas. Essas matérias-primas foram peneiradas na malha 200 mesh e as porcentagens para cada formulação foi misturada em moinho de bolas por 30 min. Os corpos de prova foram preparados em uma prensa uniaxial com pressão de 25 MPa e sinterizados em forno convencional nas temperaturas de 800°C, 900°C e 1.000°C, com patamar de 60 minutos e taxa de aquecimento de 10°C por minuto, verificando as propriedades das peças. Para obtenção de resultados foram realizados ensaios de absorção de água, retração linear nas peças sinterizadas, massa específica aparente e porosidade aparente, com o propósito de avaliar a variação de retração linear em determinada temperatura de acordo com a porcentagem de absorção de água. Foram realizados também os ensaios de flexão e microscopia eletrônica de varredura - (MEV). As composições estudadas apresentaram resultados satisfatórios dentro dos valores aceitáveis para o devido uso na indústria cerâmica.

Aug 7, 2018

The use of mining by-products for beneficial use may face approval, and acceptance barriers. This paper described the use of a sustainability framework to assess the safety, effectiveness and economic value of modified bauxite residue (Alkaloam«) for use on agricultural land in the Peel-Harvey region of Western Australia. The results indicate the merit associated with using this by-product from a safety and, private, community and environmental value perspective. They may be used to indicate the worth of pursuing any future community acceptance and agency approval process.   The use of Alkaloam« for beneficial use on agricultural land in Western Australia was first investigated over 25 years ago. Efforts to gain regulatory approval and community acceptance of Alkaloam« have had a complicated and enduring history. Understanding and assessing the value of a by-product using social and economic considerations, in conjunction with an environmental assessment, provided a more complete evaluation to that previously used.

Jun 1, 2010

The following is a Maintainability Design Checklist for coal mining equipment. The purpose of the checklist is to provide a summary of design review points for the maintainability assessment of new or existing underground equipment. It specifically focuses on the identification of equipment design features, tasks, or procedures that impact equipment downtime, repair costs, labor hours and maintainer skill level requirements. Some checklist points are general in nature. The checklist was designed to be used across all categories of underground equipment. The intent is to draw attention to design features and maintenance procedures that will increase maintainability requirements. You are encouraged to adapt this checklist to site specific or machine specific requirements by: Inserting specific performance criteria for various categories of maintenance tasks. For example; all hydraulic lines on a shuttle car should be replaceable in 15 minutes or 25 minutes, etc. Adding or deleting checklist items for different categories of equipment. You would include environmental control equipment, for example, on face equipment and not on shuttle cars or man trips. Adding additional checklist items based on site or equipment specific maintenance histories or experience, company maintenance standards, or other factors.

Jan 1, 2000

By R. K. Wharton

The paper reviews the development of European harmonised standards for fireworks, recent major incidents involving the bulk storage of fireworks which led to research funded by the European Commission, progress with the forthcoming European Regulation on pyrotechnics and potential issues relating to the certification of products within the scope of the new Regulation.

Jan 1, 2005

Ground falls (roof and rib) have historically been responsible for nearly 50% of all fatalities in bituminous underground coal mines. In recent years, the number of some annual ground fall fatalities has approached zero, indicating that significant progress has been made. On the other hand, the twin disasters at Crandall Canyon in 2007, in which nine miners perished in violent coal bumps, provided a stark reminder that complacency is premature. One important success has been a great reduction in the number of miners killed inby roof supports. Throughout the 1990s, these accounted for nearly half of all roof fall fatalities, but there have just been two inby incidents since 2005. Progress has also been made in pillar recovery, where there has been just one fatal incident since 2005. On the other hand, more than 300 miners continue to be injured each year by rock falling from between supports and 100 more are injured by rib falls. Together, these two categories also account for a large percentage of recent ground fall fatalities available technologies such as roof screen, rib bolting and inside control roof bolters could reduce injury and fatality rates if they were used more widely. Further advances in these areas will likely be the next big advance in ground control safety.

Jan 1, 2011

By H. Do

In flotation, hydrophobic particles are selectively collected by air bubbles, and the bubble-particle aggregates enter the froth phase. However, less hydrophobic particles drop off from the froth phase, while more hydrophobic particles are recovered. Thus, the froth phase provides an important cleaning mechanism. In the present communication, the froth-phase recovery process has been modeled by considering particle retention times and the carrying capacities of bubbles. The model predictions are compared with the experimental data reported by Seaman et al. (2006). The results show that the froth-phase recovery varies with particle size, particle hydrophobicity, and bubble coarsening.

Jan 1, 2008

By A. R. Byers

"This paper describes the distribution, occurrence, and paragenesis of known sulphide deposits within an area bounded by longitudes 102°00' to 106°00' west and latitudes 54 ° 301 to 57 °00 1 north. The Precambrian bed-rock which outcrops over all but the southern fringe of the area con- . sists of regional metamorphic assemblages ranging from low grade or green schist facies to high grade or amphibolite-granulite facies. The areas . of low-grade metamorphism correspond to 'islands' of volcanic rocks which are surrounded by highgrade paragneisses and migmatites. Intrusive rocks range in composition from ultrabasic to granitic and may be divided into syntectonic and posttectonic sequences. The average composition of the former is granodiorite and of the latter quartz diorite.The massive sulphide deposits fall naturally on basis of mineral content into the following divisions: ( 1) pyrrhotite and / or pyrite, (2) sphalerite and/ or chalcopyrite plus iron sulphides, (3) sphalerite and galena, ( 4) sulphide-bearing pegmatite, and (5) nickeliferous pyrrhotite and / or chalcopyrite. The deposits of iron sulphides are ubiquitous. Ratio of pyrrhotite to pyrite is fairly constant for individual deposits, but their areal distribution appears to be independent of the nature of the enclosing rock and grade of regional metamorphism. All deposits containing ore-grade quantities of base metals have been concentrated at favourable structural locations. Copper-zinc and lead-zinc deposits appear to be associated with syntectonic granodiorite with the lead-zinc concentrations confined to calc-silicate gneisses. Copper-nickel deposits show a close relationship to post-tectonic gabbros and pyroxenites. The paragenesis is more or less the same for the majority of deposits, with iron sulphides and sphalerite being introduced early and followed by chalcopyrite and galena. Some vertical and / or horizontal zoning is apparent in a few deposits. Temperatures of formation and origin of the deposits are briefly discussed."

Jan 1, 1960

By Vernon C. Davis

"SUMMARY AND CONCLUSIONSIn initial attempts to mine taconite by conventional open-pit methods, the material tended to break into tabular blocks that were too large to be handled by conventional shovel dippers and were unsatisfactory in an ordinary crusher feed. A great amount of secondary blasting was necessary, which added considerably to the cost of mining.The Bureau of Mines and others are engaged in studies designed to contribute to the solution of taconite-mining problems. These studies concern problems related to drilling techniques and patterns, types and methods of use of explosives, and other factors relative to effecting maximum fragmentation at minimum cost.This report is concerned with study of the application of shaped charges in drill holes, the effectiveness of shaped charges as compared to capped charges in secondary blasting, and the merits of different drilling patterns and methods of detonation of conventional-explosive charges.Fragmentation of taconite at or near the surface is controlled or strongly influenced by joint and bedding planes. Since all tests in this study were made in a jointed and bedded area, a definite conclusion as to the relative effect of a shaped charge in a drill hole, as compared to a conventional charge at greater depths and tighter ground, is precluded. However, application of shaped charges in primary blasting of taconite appears to be of no advantage.In secondary blasting of taconite, conventional, capped charges produced better breakage than shaped charges of the designs tested.Based on the results of conventional blasting practice in horizontal-, inclined-, and vertical-hole tests, no better fragmentation is obtained from blasting either horizontal or inclined holes, compared to vertical holes.Holes drilled in staggered parallel rows that intersect both series of joint planes at the greatest possible angle, give maximum breakage compared to rows parallel to one of the series of joint planes.Methods of detonation made little difference in breakage; but the millidelay caps produced the best conditions for moving the broken rocks."

Jun 1, 1953

By V. Yahorava

Ion exchange is considered to be an effective technology for the removal of various impurities from cobalt advance electrolytes. With the correct choice of resin, ion exchange can consistently remove the required impurities to the levels for the production of high-grade cobalt metal. Although ion exchange was in the past used primarily for nickel removal, more recently it has been also considered for the removal of copper, zinc, and cadmium. Generally, granular ion exchange products are used, but Mintek is currently evaluating ion exchange fibres for a number of applications, including the removal of copper from cobalt advance electrolytes. Fibrous ion exchangers have major advantages compared to granular resins in that they have significantly higher reaction rates, and wash water volumes could be limited. Granular and fibrous ion exchangers were evaluated and compared for the removal of copper from cobalt advance electrolyte. A synthetic electrolyte containing 50 g/L cobalt and 50 mg/L copper was used for the test work. Equilibrium isotherms, mini-column tests, and split elution tests were done. The results were used to size a full-scale operation to treat 100 m3/h of electrolyte. The potential cobalt losses or recycle requirements were estimated, and data to calculate indicative operating costs for each adsorbent was generated. This information was used for a techno-economic comparison of granular and fibrous ion exchange systems for the removal of copper from cobalt advance electrolyte.

Jan 1, 2014

By F Rashidinejad

Iran has had an active mining sector for some 7000 years. Exceptional in terms of its mineral diversity, Iran produces 62 minerals, and is ranked among the world’s 15 most mineral-rich countries. Many people around the world know Iran as one of the major petroleum exporters. Oil and natural gas dominate Iran’s economy, and oil exports provide the principal source of income, contributing more than 80 per cent of foreign exchange earnings. Transformation of Iran from an oil exporter to an independent country to oil has been on the table for many years, even before the Islamic Revolution of 1979. Development of the Iran’s mineral industry is one of the major replacements for petroleum exports. In the last decade, Iran invested billion dollars in the mining and mineral industry sectors and to increase the added value, tried to export processed minerals instead of the raw materials. In accordance with the ‘20-year Perspective 2025’ that targeted by the Supreme Leader, Iran will be a country with the first rank in economy, science and technology in its region. The objectives over this perspective include briefly increasing annual production to 55 Mt of crude steel, 800 000 tonne of copper cathode, 1.5 Mt of aluminium, 200 Mt mineral products, 300 000 tonne of zinc and 5 000 kg of gold. These goals are achievable in normal circumstances, but concurrency of the 20-year Perspective 2025 with commencement of the UN Security Council sanctions against Iran, frustrated objectives of the perspective, at least the ones related to the mining and mineral industry sectors. This paper tries to elaborate the development programs and following challenges for the mining activities of Iran by 2025.

Nov 22, 2011

By F. G. Schwartz

This circular presents the results of a survey of research on jet fuel thermal stability jointly sponsored by the National Petroleum Refiners Association (NPRA), Tulsa, Okla., and the Bureau of Mines. The development of supersonic planes has led to many problems that did not exist in the operation of subsonic aircraft. One of the most important of these is rapid deterioration of the fuel at the high temperatures to which it is subjected. At higher speeds, aerodynamic heating of the airframe imposes severe thermal problems, and conventional techniques of rejecting the heat to the atmosphere become impractical. The fuel is the only material present in sufficient bulk to be used as a heat sink. Thus, the fuel is subjected to aerodynamic heating and also is used to dissipate heat from lubricating oil, hydraulic fluid, electronic equipment, wheel wells, and cabin air. Consequently, the fuels may have to withstand both moderate temperatures for sustained periods in the fuel tanks and higher temperatures for brief periods during transfer from the tanks to the combustion chamber. Because of high temperatures, insoluble residue or gum may form in the fuel and contribute to heat exchanger fouling and to clogging of the fuel manifolds, nozzles, control systems, and other components of the fuel system.

Jan 1, 1962