Search Documents

By L. Naude, J. Cloete, S. Engelbrecht

The results of an investigation evaluating whether an industrial plant, currently operating using sodium isobutyl xanthate (SIBX) as primary collector for sulphide minerals (mainly chalocopyrite), could adapt to operate using an alternate primary thiol collector without compromising plant and metallurgical performance. Initial laboratory scale flotation tests identified commercial dithiophosphate (DTP)-based and thionocarbamate (TC)-based collectors, that when blended, showed potential to replace the incumbent SIBX primary PGM collector. Industrial plant trail results show that there was no deterioration in recovery of 4E PGMs, even at a lower concentrate grade when operating the plant on the identified (DTP + TC)-based collector blend compared to SIBX. The effect on Cr2O3 content in the final concentrate was also found to be negligible. The (DTP + DTC)-based collector blend also showed promise in terms of plant adaptability in accommodating a new primary specialty collector blend. These observations highlighted the potential of replacing xanthate primary collectors with alternate thiol collector blends for PGM flotation. Keywords: PGM, xanthate replacement, specialty collector, sodium iso-butyl xanthate (SIBX), dithiophosphates (DTP), dithiocarbamates (DTC)

Jan 1, 2020

By D. Harrington

When the word "gas"' is mentioned in connection with mining almost invariably it is inferred that the explosive gas, methane, is in mind and that the reference is to coal mining. Although methane is likely to occur in any coal mine the metal mines of the world contain by far a greater variety of gases than do the coal mines. Often the gases in metal mines are as dangerous as the gases likely to be found in coal mines, and sometimes are even more deadly. A coal mine is more likely to contain methane than a metal mine. In rare instances it may contain high percentages of nitrogen or carbon dioxide or it may be deficient in oxygen where the air is confined in a blind end or in a sealed region. Much more rarely relatively small percentages of ethane or other hydrocarbons with an odor of ether, gasoline, or kerosene, or minute percentages of hydrogen sulphide are found in a coal mine. During a coal-mine fire or explosion carbon monoxide content is likely to be high (4 per cent or more), and if the coal contains much sulphur the high fumes may contain some sulphur dioxide.

Jan 1, 1931

By W Roy

When it comes to plan implementation and securing success in organisations in the 21st century, if there was such a thing as the secret to success it would be effective communication. Commoditisation brings financial, operational and cultural advantages to organisations that use effective communication. Effective communication tools turn æpeople problemsÆ into system control solutions, removing personality clashes that hide procedural malfunctions. By introducing communications frameworks available in the market place today, and case studies of their use, this paper provides insights into the successes available to organisations courageous enough to redefine their communications for the 21st century.

Jan 1, 2006

By S. K. R. Iyengar

This report presents the results of a study to develop optimal designs for light-weight mine roof supports for use in underground coal mines. A load capacity of 196 kN (22 tons) and a height adjustable between 1.829 m (72 inches) and 2.438 m (96 inches) were taken as the design parameters and the design goal was a unit weighing less than 22.3 kg (50 lbs). Three alternative design concepts were explored, viz. mechanical, hydraulic, and hydro-mechanical and a total of 13 designs analyzed in detail. Steel, aluminum alloy and composites were the main potential construction materials investigated for suitability from structural, life, and safety and other considerations. The designs considered most promising for development were: (i) the mechanical screw-pin type using telescopic tubes and a fine adjustment screw thread section (ii) the all-hydraulic type, of steel, aluminum alloy or aramid graphite construction (iii) the hydro-mechanical design using telescopic tubes and a short stroke hydraulic cylinder for fine adjustment It is shown that by using realistic mathematical models for stress and deflection calculations, it is possible to reduce prop weight to the design goal. The analysis presented for all-hydraulic props is applicable to hydraulic cylinders on all mining equipment and similar machinery. This report includes the computer program and user's guide for analyzing hydraulic cylinders as well as a cross-indexed bibliography on structural composites.

Jan 1, 1978

By C. O. Anderson, W. M. Meyers

Since 1922, when a brief report3 on the production and utilization of garnet was issued by the Bureau of Mines, there have been a number of interest—in developments in the technology of that mineral. Greater activity has been displayed in mining, new mills have been erected, and more attention has been paid to improvements in milling so that a more efficient and economical recovery of garnet has been possible. These activities have resulted in larger production; therefore, attempts are being made to broaden the market for garnet abrasives, and to find new uses for the unusual combination of physical properties than this mineral possesses. The writers have recently completed a field study of the occurrence, methods of mining and milling of garnet, and the manufacture and utilization of abrasive garnet products. This preliminary report indicates the most important sources of garnet, the methods by which it is recovered, and the manner in which it is recovered, and the manner in which it is utilized.Chemical and Physical Properties.The term ""garnet"" is applied to a closely related group of minerals which crystallize in the caste forms and possess similar physical properties, although their chemical composition may exhibit greater variation. The chemical composition of the garnet group may be represented by the general formula 3R"" O.R""' 203.3S102, in which R represents the bivalent elements calcium, magnesium, in the manganese state and ferrous iron, R"" represents the trivalent elements, ferric iron, aluminum and chromium in the chromie state. An account of the amorphous substitution of the different bivalent and trivalent elements, specimens whose composition may be represented by a definite formula are rare, the composition of any given specimen generally exhibits treat complexity.

Jun 1, 1925

By D. K. Adjei, G. Ofori-Sarpong, R. K. Amankwah

"Mercury (Hg) is toxic and has long-term effect on the muscle tissues, the brain and the central nervous system functions due to its bioaccumulation and biotransformation effect. Hg pollution around the world is high and this has attracted much global concern such as the Minamata Convention on Mercury, held in 2013. For several years, mercury has been the chemical of choice for Artisanal and Small-Scale Mining (ASM) gold extraction, accounting for about one-third of the global mercury consumption. A greater percentage of this ends up in the environment through open burning of amalgam, spillage and indiscriminate disposal of waste. To break this wall of mercury pollution, it is very important for the mercury used to be recycled through the use of mercury retort units. This brings into the limelight, the Lantern Retort which tries to synergise the high conductivity of steel and the see-through effect of glass, thus, improving the amalgamation process. A research conducted on improving the original Lantern Retort arrived at an appropriate distillation length of 5.08 cm which was used in redesigning a more efficient retort. The improved Lantern Retort recovered about 98% of the mercury used. INTRODUCTION Artisanal and Small-scale mining (ASM) is an informal mining activities which employ quite simple tools such as pickaxes, sluice boxes, shovels, chisels, metal bars, mattocks and water pumps for mining and processing of gold ores. The artisanal and small-scale mining (ASM) sector has served as source of employment for many people in developing countries including Ghana (Aryee, 2001; Hilson and Potter, 2003; Amankwah and Anim-Sackey, 2004; Amankwah et al., 2010) and has provided a substantial amount of foreign exchange through its activities (Hilson, 2001; Styles et al., 2010). Hentschel et al. in 2003 estimated that about thirteen (13) million people are said to be engaged directly in the small-scale mining activities worldwide. However, an estimated 100 million people are said to depend on this sector for their livelihood mainly in developing countries. In China alone, a projected number between 3 and 15 million people are engaged in artisanal and small-scale mining activities (Hentschel et al., 2003), whilst in Ghana, it is estimated that more than 1,000,000 people are employed directly or indirectly in the artisanal and small-scale mining activities, with 10% being women (Amankwah and Anim-Sackey, 2004; Amankwah and Ofori-Sarpong, 2014). In Ghana, ASM gold production has grown from a low of 2.2% in 1989 to a high of 34% in 2014. This figure is estimated to increase with proper documentation. This indicates that the sector has made significant socioeconomic impact on many individuals and communities as a whole. Notwithstanding the above positive contributions, the sector has also contributed to negative impacts on human, aquatic life and the environment in general due to indiscriminate mercury emission. This ‘pollution wall’ needs to be broken, and several interventions have been put in place including the use of retort units like the lantern retort (Adjei et al., 2014; Amankwah and Ofori-Sarpong, 2014)."

Jan 1, 2017

By S. L. Crouch

The general term "coal mine burp" refers to the sudden and violent failure of in situ coal. Coal bumps occur in most countries where coal is worked by underground methods, and are related to both geological factors and mining tech¬niques. Although no single set of circumstances is solely responsible for causing coal bumps, it is generally agreed that at least one of five conditions is necessary in order for then to occur: 1,2,3,4 (1) the depth of cover exceeds 500-ft., (2) the overlying strata are relatively strong and stiff, (3) the coal is structurally strong, (4) the floor does not heave readily, and (5) the mining method produces high stresses over a large area of the seam. Except for the last, these conditions relate to geological factors that are impractical to control. Consequently, methods of controlling or minimizing the occurrence of coal bumps usually are concerned with mining techniques. Coal bumps have been successfully controlled by both longwall and 'yielding pillar' mining systems 4. The longwall system is particularly effective in controlling bumps, but does not eliminate them completely, especially in strong coal seams being worked at comparatively great depths, say in excess of 2000-ft.5. Under such conditions, auger drilling or water infusion often prove helpful 5,6. These techniques are used to destress or otherwise alter the mechanical properties of the coal in an attempt to shift the peak "abutment pressure" away from the immediate vicinity of the face. Under 'normal' conditions, however, it can be expected that the coal near the face will be crushed under the prevailing high stress conditions and that the peak abutment pressure will automatically be shifted into the solid coal. In this context, coal mine bumps can be characterized as unstable releases of energy associated with successive yielding of portions of the coal seam with progressive mining. Longwall and yielding pillar mining systems are effective in controlling coal bumps because they ordinarily do not allow the zone of peak abutment pressure to become 'surrounded' by destressed coal.

Jan 1, 1973

By A. C. Stevenson

THE hoisting equipment selected for use at the Hecla mine in 1907 was one of the first Ilgner type Ward-Leonard controlled hoists put into ser- vice. Development of the Hecla below the 2000-ft. level, which is the ultimate depth of the old equipment, and the additional service required by the "Star," necessitated additional hoisting capacity. It will be our endeavor to give j70u a brief summary of the engineering which determined the selection of the new equipment. The engineer in making his decision as to size, speed, etc., must .make a duty study approximating as closely &s possible the actual opePating conditions which will eventually result. Primarily, it is necessary to know what work must be done. The amount of material which must be hoisted under the maximum condition, as well as its distribution from the various levels of the mine was carefully studied by the mining engineering department, as the ore reserves, their relative-position and the probable method of working them had to be considered. The final figures reached, taking into consideration four different operating conditions, were, in tons per day, as follows:

Jan 1, 1930

By B. M. Eiter

The impact of fatigue is seen not only in its effect on the job performance of haul truck operators but also on the health of the operator and the productivity at the mine site. Its impact can even extend outside of the mine site to the health and well-being of the surrounding community (Fourie et al., 2010). In this paper, a case study of a small, surface mining organization is presented. The goal is to highlight the fatigue risk management system implemented at the studied mine site. Mine safety personnel who were interviewed discuss the changes made to the infrastructure of the mine, to administrative areas such as the number of shifts and the use of vacation time, as well as the implementation of new technology into haulage vehicles. This paper reviews how these changes are supported in the research literature.

By Jim Huerta

Diesel fuel usage in the mining industry continues to escalate. This is because approximately 60 percent of all mined materials are surface extracted by large equipment using diesel fuel, which continues to increase in cost per gallon. For example, coal mining uses large equipment such as wheel loaders, wheel dozers, draglines and [ ] dredgers. In one year, three of the largest U.S. coal mining operations consumed approximately 567 million to 852 million L (150 million to 225 million gal) of diesel. At an approximate cost average of $3.25/gal the expenditure on diesel is $487 million to $731 million per year. So, are there any solutions that could reduce this cost burden? Yes, there are. Coal mining companies can extract less ore; use more efficient extracting equipment that consumes less fuel; wait for a significant reduction in the cost of fuel; or find and use technology that would create efficiencies that would lower the cost. Nanotechnology is one such technology that might provide the means to create the efficiencies that will significantly lower diesel fuel costs.

Jan 1, 2011

By X Hu, Z Pokrajcic, R Embry, P C. Stewart, J Carpenter, E Jones

Whilst the value of Pit to Plant and Mine to Mill optimisation has been proven since the 1990s, sustaining the productivity and efficiency gains typically requires ongoing test work, blast trials, plant surveys, and model calibration services. In contrast, the input to digital twin Pit to Plant or Mine to Mill optimisation is tens to hundreds of millions of tonnes of standard mine operating data. This paper presents a series of digital twin case studies from across the mine value chain, including machine learning testing methodology, model accuracy statistics and the application of Shapley Additive Explanations (SHAP) for model interpretation. These case studies demonstrate how machine learning and data fusion ore tracking connects hundreds of millions of tonnes of downstream performance data to produce digital twin models (operating models that are continuously updated and integrated into the wider Mine to Mill/Pit to Plant ore tracking system). Digital twin modelling software has been used to add block model variables for dig-rate, crusher and mill throughput, recovery (tailings grade), lump yield, product grade and product quality, fines yield and fines in lump. Block-by-block predictions are added to the geological resource and grade control block models as new block model variables. These new block model variables are used across all mine planning time horizons from life-of-mine planning to daily schedules. In addition to the materials handling and geometallurgical prediction case studies, the paper also presents digital twin case studies for drill and blast simulation and plant set point optimisation. The case studies show how digital twin simulation enables drill and blast engineers to simulate the effect of different blast designs in different blast domains using the mines operating data. Plant set point optimisation applies mathematical optimisation algorithms to the machine learning model to provide live operational decision support to metallurgists and plant operators. The digital twin machine learning case studies demonstrate a digital and sustainable paradigm for Mine to Mill and Pit to Plant optimisation.

Jun 22, 2022

By Gerald T. Homce

A system capable of monitoring a mine electrical power system to detect incipient electrical component failure could significantly improve power system safety and availability. The U.S. Bureau of Mines funded a contract with The Pennsylvania State University (Penn State) to establish the theoretical and technical framework for such a system. This report briefly outlines the contract, reviewing related Bureau and Penn State work prior to its award, and describes support work carried out by the Bureau. The main focus of the report is on research efforts by Penn State and subsequent results. An existing algorithm for incipient-failure detection and classification was studied, and recommendations are made to improve its performance. In addition, mathematical models of cable-connected motor systems and deteriorating motors were developed and implemented on computers. These models and laboratory tests were used to study and document relationships between component deterioration and electrical terminal effects. The project was supported by the U.S. Navy and the nature of its interest in the application of failure prediction techniques is also included.

Jan 1, 1989

By C. BARING HORIVOOD

(Chattanooga Meeting, October, 1908.) THIS paper is intended, in the light of recent investigations, to call attention to some of the essential features of good practice in sampling and mine-valuation. Mine-sampling may be divided broadly into two classes : (1) development-sampling and computation of ore-reserves; and, (2) stope-sampling and estimation of stope-values. DEVELOPMENT-SAMPLING. It is with development-sampling only that this paper deals-the term development being taken to mean the opening-up of a mine by cross-cuts, drives, connections, etc., preparatory to actual extraction of the ore for milling. In development-sampling the work of the sampler and the consequent estimation of the probable value of the mine or portions of the mine, as the case may be, cannot be verified until a later period, when the ground thus sampled has been exploited; hence, extreme care and accuracy are essential. Moreover, the development-sampler has to foresee and allow for contingencies which may arise when stoping is started. It follows that the sampling, in development-work, demands familiarity with the conditions likely to be encountered later in actual mining. In stopes, on the other hand, sampling is clone under actual working-conditions, and the sampler's valuations are immediately checked by the gold-output, or in some cases by a second sampling of the broken ore. A stope-sampler therefore need not be an experienced miner, though he should possess sound technical training and work accurately. Should he be somewhat inexperienced, be soon has his errors discovered for him, and learns to avoid them. Taking these facts into account, it is obvious that a mining company employing two or more samplers should

Jan 1, 1909

By D. R. Mathews

The Bureau of Mines investigated the effects of tungsten and chromium, separately and combined, on improving the mechanical properties and oxidation resistance of vanadium. Binary and ternary vanadium-base alloys were prepared and tested for oxidation resistance and tensile strength. Softening occurred with less than 1 weight-percent of either tungsten or chromium, followed by strengthening with higher alloying contents. Vanadium alloys containing up to 9.8 weight-percent chromium or 14.1 weight-percent tungsten were more resistant to oxidation in air at 600° C than unalloyed vanadium. For the alloys with 12.20 weight-percent chromium or 14.56 weight-percent: tungsten, the maximum concentrations used, the lower yield strengths were about twice that of 38,600 psi for the unalloyed vanadium. Recrystallization temperatures for these alloys were 100 and 150° C higher, respectively. Alloys containing both chromium and tungsten had properties similar to those of the vanadium-tungsten alloys.

Jan 1, 1967

By R. K. H. Falconer, Wood R. A., C. D. Castle

"A deposit of phosphate nodules is on the Chatham Rise approximately 450 kilometres to the east of Christchurch in the South Island of New Zealand. The deposit contains sufficient rock phosphate to supply New Zealand’s phosphate fertilizer needs for at least 20 years. It was first investigated commercially 50 years ago by Global Marine, followed by JBL Minerals in the early 1970’s. NZ and German government research and industry groups then took it up again, with major field programs in 1978 and in the early 1980s.Due to difficult global and local economic conditions the project ground to a halt in 2004.The project was resurrected in 2007 when Chatham Rock Phosphate applied for a prospecting licence. This was granted in 2010 and a successful subsequent mining permit approval followed in 2013. The initial application for the separately required environmental permit was declined in February 2015.A lot has changed then and the significance of this will be the subject of the presentation. Chatham Rock Phosphate is confident that an environmental permit will be successfully granted next time."

Jan 1, 2017

By Edward E. Johnson

The principal purpose of this study was the development of an engineering and economic model of a hypothetical large-scale open pit gold mining operation. The guiding concept in developing the model was the idea that, through study of a number of such models, it would be possible to evaluate a mineral property and to make reasonable estimates of the benefits to be derived from research in mining and metallurgy. The model by use of a computer is able to produce results easily and quickly when cost factors are varied. Cost factors may be varied as a result of assumptions of improved technology or of assumptions of assuming different approaches or methods to accomplish a particular segment of the mining or processing operation. The discounted cash flow rate of return was used to measure the effect of changes in costs or expected revenue. In this study, assumptions based on past processing practices were made in an effort to reduce costs of processing the ore These assumptions were: (1) Eliminating the low-grade cyanide circuit; (2) reducing the quantity of material to be processed by screening after crushing; and (3) using a combination of assumptions (1) and (2). All three assumptions resulted in reduced capital investment and operating cost that caused substantial increases in the rate of return.

Jan 1, 1968

By Michael Arriagada, Ivan Arriagada

"As mines return to shafts to economically exploit deeper reserves, two methods mine owners use to minimize short term costs are: sinking shafts in phases and refurbishing old, existing shafts. While there may appear to be benefits to utilizing existing infrastructure, often this is not the case, resulting in missed deadlines and added costs. Similarly, if proper long term planning is not executed when sinking a shaft in phases, additional costs and downtime will be accrued. This paper will take an in depth look at both of these options with an eye towards optimizing costs, minimizing downtime, and facilitating construction. INTRODUCTION With the onset of mechanized mining and large capacity trucks, many mines turned away from shafts and began to use ramps to haul ore to surface. However, continual exploitation of mineral reserves located closer to surface, combined with the subsequent unearthing of additional resources at greater depths, forced mines to go deeper and deeper to extend the life and keep the operation running. In shallow mines, hauling ore by truck was an economical option. However, as mines get deeper, driving ramps takes additional time, and hauling over longer and longer distances becomes less economic, both in terms of cost and time. For this reason Mexico, in particular, has seen a jump in the number of shafts which have been put into production, as well as having a number of shafts in different stages of development and still more in the conceptual stages. Many of the shaft projects in Mexico are being designed in phases, with the hoist and equipment purchased capable of reaching the ultimate planned depth of the shaft, but with sinking operations stopping short at an intermediate depth. A loading pocket is then installed to start exploiting mineral at this depth sooner, with subsequent phases planned for a later date using either a rock pentice or bulkhead to separate the sinking operations from the active shaft above. Currently, we are directly involved in two such projects which are actively being deepened, as well as having seen various others already reach completion. If done properly with the long-term plan in mind, sinking in phases can be a very viable option, allowing for faster production while fully utilizing the equipment at various depths. However, there are many issues which can arise when sinking a shaft in phases that if not properly examined and planned for from the outset, have the potential to eliminate the gains hoped for when it was decided to sink in this manner."

Jan 1, 2019

By W. D. Sinclair

"Between 1934 and 1956, nearly 31 million grams of gold were produced in the Matachewan area from deposits on properties belonging to Young-Davidson Mines Limited and Matachewan Consolidated Mines Limited. In 1979, production from these properties was renewed by Pamour Porcupine Mines Limited.Most of the gold produced has come from relatively lowgrade deposits (3.4 gl t or less) that occur in an east-trending belt of dykes and irregular bodies of trachytic syenite. Although small by comparison, these deposits have some of the characteristics of porphyry copper-molybdenum deposits. The mineralized syenite contains up to 5 per cent disseminated pyrite and is highly fractured and cut by quartz and quartzcarbonate veinlets. Gold occurs as native gold along fractures, in quartz veinlets and as minute inclusions in pyrite. Minor chalcopyrite and trace amounts of scheelite, molybdenite and galena are also present. Mineralization was accompanied by potassic alteration, consisting mainly of potassium feldspar.Some gold was also produced from small, but higher-grade, deposits in volcanic rocks. These deposits occur near the syenite-hosted deposits and consist of quartz veins and stringers mineralized .with pyrite and gold. Minor gold is present in some low-grade, porphyry-type copper-molybdenum occurrences and, locally, in large, isolated quartz veins.Lead isotope analyses suggest that the gold deposits were formed at about 2700 Ma and were locally remobilized at approximately 2400 Ma, following the Kenoran orogeny. The deposits appear to be genetically related to felsic magmas emplaced in an epizonal environment and deposited from hydrothermal solutions relatively concentrated in S and K20."

Jan 1, 1982

By Grant A. Brackebusch

Paste tailings disposal was successfully implemented at the New Jersey mill in Kellogg, ID with two different types of ore feed, a gold ore and a silver ore. The purpose of this paper is to describe the production of paste tailings, including operational problems during commissioning, and also highlight the environmental and economic benefits that were realized versus conventional tailings disposal such as the recycling of process water, increased shear strength and reduced permeability of the tailings mass, and reduced environmental permitting.

By M. A. Power

The diamondiferous Drybones Bay kimberlite pipe is the largest pipe (900 m by 400 m) discovered to date in the Northwest Territories. The pipe intrudes granodiorite of the Archean age Defeat Pluton and contains crater, reworked crater (epiclastic) and diatreme facies kimberlite. In-situ measurements of seismic p-wave velocity were recorded with in-line refraction arrays over representative areas. Refractions from fresh kimberlite were recorded over epiclastic facies kimberlite in the eastern portion of the pipe and returned an average velocity of 4300 m/s. Refractions from weathered kimberlite were recorded on all lines and returned velocities ranging from 1900 m/s to 2200 m/s. Granite surrounding the pipe returned an average velocity of 5400 m/s. The results indicate that there is a definite contrast in seismic velocities between kimberlite and country rocks at Drybones Bay and suggest that seismic refraction surveys may be an effective means of screening kimberlite targets in glaciated areas underlain by igneous or metamorphic rocks.

Jan 1, 1998