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By Michael H. Leon, John A. Organiscak

Controlling worker dust exposure on longwall mining systems is difficult because the working face area serves as an immediate return during the mining cycle and the amount of airborne dust generated is directly related to production. Since improvements in longwall mining technology have significantly boosted production levels, additional technology is needed to control the airborne respirable dust generated at present and future production levels. One concept to reduce longwall worker's dust exposure is to maintain two splits of air at the face -- a clean intake split in the workers walkway, and a return (dusty) split over the face conveyor. The U. S. Bureau of Mines has recently investigated a concept to overcome the visibility handicap of face partitions by utilizing a permeable polyester mesh. The mesh material was anticipated to provide adequate air-splitting capabilities as long as the pressure differential between the face and worker walkway was minimal. Initial testing of this concept at the Bureau's Lake Lynn Laboratory showed that notable reductions could be achieved with a 1/8 in (3.18 mm) and 1/16 in (1.59 mm) mesh opening size. Dust reductions at 100 ft (30.5 m) and 200 ft (61.0 m) downstream of source were 58 and 36 pct, respectively, for the 1/8 in mesh and 79 and 55 pct, respectively for the 1/16 in mesh. Longwall application of the 1/8 in mesh showed similar results to the Lake Lynn Laboratory tests. A flame retardant mesh was used underground with portable lighting mounted on the shearing machine for face side lighting.

Jan 1, 1993

Tailgate pillar and tailgate-face corner humps have been a major threat to longwall coal mines where hump-prone conditions exist. The yield pillar design concept, in which the longwall chain pillars are designed in such way that they can yield in a nonviolent or controlled manner during longwall retreat, has been used in many longwall mines to prevent tailgate pillar humps. However, this practice often shifts the side abutment load onto the tailgate-face corner especially when a massive and strong sandstone member is present within the caving zone or in the vicinity of the coal seam. Therefore, the abutment pillar design concept has also been used in some hump-prone coal mines to minimize the stress concentration on the tailgate panel rib for the control of tailgate-race corner humps. The disadvantage of using the abutment pillar design concept is that it is more costly and puts additional pressure on mine operations for gate entry development and significantly reduces the recovery of coal reserve. In addition to pillar size, panel layouts. such as the panel width and panel orientation also play a critical role in pillar or face humps and should he taken into account. Based Upon the Cyprus mine design and operational experiences at Willow Creek and case studies at other bump-prone longwall nines in the U.S., the authors attempt to identify the critical factors causing coal mine bumps and to introduce some guidelines and criteria for the design of both yield and abutment pillar systems and panel layouts.

Jan 1, 1999

By J Durbin

To effectively plan for closure, we must have an end-point in mind. To undertake meaningful rehabilitation, a post-mine land use (or uses) must be known. However, it is becoming more apparent that the end-point or “goal-posts” are shifting - and may continue to do so throughout the life of a mine. As well as being safe, stable and not causing environmental harm, post-mine land uses should always be sustainable, achievable within the given land capability, and they should involve stakeholders in their design and development.The majority of mines in Australia, and around the World, were historically expected to return disturbed land to either native ecosystem or agriculture/forestry practices. However, examples of highly successful final land uses suggest that today’s focus on closure includes not only minimising future liability and impact but also – and importantly – a move towards the creation of economic opportunity (Murphy and Heyes, 2016).CITATION:Durbin, J, 2018. Planning for (not so) final land use, in Proceedings Life-of-Mine 2018, pp 110–112 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By R. M. Stewart

INTRODUCTION Requirements for achieving economic slope stability in open pit mining must not only be met during the operating stages but in all preceding stages of mine development. In many operating mines little or no emphasis was ever placed on evaluating the stability of possible slopes during the exploration and planning stages. The purpose of this discussion is to emphasize the necessary considerations that should be made in all stages of development in order to achieve the safest and most economic pit slopes. The most economic slopes may not always be the safest slopes and it is incumbent upon the mine operators and engineers to achieve an optimal combination of economics and safety. The stability requirements outlined are based on the profit motive and are, therefore, practically oriented. Long-term basic research or theoretical studies are considered important only to the extent that they can be shown to have a definite payoff. Consideration will first be given to the information required for stability analysis, which can be determined during the exploration and evaluation stage, followed by further stability work necessary during the mine planning and layout stage. Particular emphasis is then placed on the operating stage in which blasting, dewatering, artificial stabilization, and slope failure are discussed. Lastly, the importance of a logical and orderly research procedure is stressed. EXPLORATION AND EVALUATION STAGE The purpose of the exploration and evaluation stage in the mining scheme is to find and delineate a potential orebody. Discovery and delineation commonly involve drilling tens and in many cases hundreds of boreholes. These boreholes, which may cost as much as $20.00 per foot of depth for a cored hole, are usually abandoned once drilling is completed. Stability evaluation for a potential open pit should begin at this stage by taking advantage of the existing boreholes. Rock and soil properties, as well as hydrologic parameters, may be obtained from both the borehole and the core. Seismic velocity and neutron probes may be used to log the borehole to obtain elastic moduli data. A borehole dilation jack may also be used to give backup information on the rock and soil elastic parameters. Use of a core orientation system can result in the determination of fault and joint frequency and distribution. Before splitting or otherwise disturbing the fresh core, qualitative evaluation

Jan 1, 1972

By D. J. Hutchinson, S. Nickson

Cable bolts are used as a means of rock support around underground excavations in many mines across Canada and around the world. A substantial body of research on cable bolting was conducted at a number of Canadian universities and mines from the mid-1980s through the 1990s. Since then, research into selected areas of cable bolting practice has continued in Canada. The research has focussed on cable bolt instrumentation and on the inclusion of cable bolts in empirical stope design techniques. A review of cable bolting practice is now warranted at many mines. It has been five years since the completion of the previous substantial body of Canadian academic research and the associated advancement in understanding of cable bolt design, implementation and verification practice. Attempts were made at that time to transfer the new design procedures and performance assessment technologies to mine-site personnel. In some cases, this was effective, and ground control personnel continue to improve on their cable bolting practice at each specific mine site. However, at other sites, experienced people have moved on, and the new, less experienced personnel do not have access to the training or technical resources required to improve their understanding of the subject. In other cases, the technology was not transferred effectively to practitioners, with the result that substantial improvements can be made to the cable bolting practice at those mines. Guidelines for auditing cable bolting practice are provided in this paper. The guidelines include a discussion of the objectives of the audit, suggestions for audit procedure and a summary of the possible outcomes of a cable bolt audit. The objectives of an audit might include assessing the reasons for unexpected cable bolt failures, evaluating the quality of the installation procedures, quantifying the efficiency of the cable bolt system and assessing training requirements and procedures. A cable bolt audit should include consideration of all aspects of the cable bolting cycle, including the design, implementation and verification phases of the operation. At the end of the audit, a ranking should be assigned to the components of the cycle. The ranking system can then be used to identify items that require immediate attention, others that could be improved and others that are adequate. Following completion of a cable bolt audit, increased confidence in the support system and its application is generally, found, along with the potential for cost savings in many cases.

Jan 1, 2002

By P. J. Carroll, H. Colijn

Feeders must be considered an integral part of the over-all bin and feeder system. Improper design of either one of these parts will affect the performance of the whole system. Feeder load, material properties, feed rate, physical layout, and environment as well as first cost determine the selection of feeder type. This paper provides a new method of calculating feeder loads with some experimental data as verification. General design criteria for belt and apron feeder, rotary table and plow feeders are discussed and a special section is devoted to vibratory feeders. Feeders are used to provide a means of control for the withdrawal of bulk materials from storage units such as bins, bunkers, silos and hoppers. This control function can only be performed properly as long as the bulk materials flow by gravity to the feeder in a uniform and uninterrupted fashion. During the past few years various papers have been written and presented on feeders and their application.1-9 This paper will be confined to some specific bin-feeder design criteria such as feeder load and power requirements. Special attention is given to the basic design criteria for vibratory feeders. HOPPER AND BIN DESIGN Feeders must be considered an integral part of the over-all bin and feeder system. Improper design of either one of these parts will affect the performance of the whole system. A lot of effort has been devoted in the past decade to the development of functional design criteria for hoppers and bins.1,10 The integrated concept of bin and feeder design requires quantitative analysis of the bulk material characteristics before the design and the selection of components can be attempted. The design of a feeder system must begin with the proper dimensioning of the hopper outlet to prevent arching or ratholing. The hopper opening should be large enough to allow passage of the bulk solid at the required maximum discharge rate." A feeder can only throttle the flow. FEEDER LOAD DETERMINATION Over the past ten years, there have been various attempts to determine the exact load or pressure on feeders mounted directly under hopper openings. Many designers, however, still consider this pressure equal to the hydrostatic head of material above the opening, and because such pressure would be very

Jan 1, 1969

By Mark Mammele, John Bowles

With the continuing rise in the cost of petroleum products and the focus on the increasing use of renewable resources, a readily available, economical replacement for fuel oil in ANFO is the logical next step, and has finally come to realization. This “green” fuel is plentiful, derived from renewable resources, more cost effective and reduces CO emissions. It also increases product density and bulk strength performance. As this unique fuel replaces some of the mass of ammonium nitrate prill, increased savings will be realized proportionally with the increasing cost of ammonium nitrate. Minimal changes are necessary, as this renewable fuel is designed for use and handling with current, commonly used ANFO blending and loading equipment. This proven technology is now in use by commercial operations in the Southwest, providing significant economic benefit with reduced cost per hundred weight of ANFO consumed.

Jan 1, 2008

By Paul K. Krueger

SUMMARY Since 1970 the Federal Preparedness Agency has been using computer models to help establish the amounts of strategic and critical materials to be held in the National Stockpile. Fifty-three of these materials are metals or minerals. The following diagram shows the linkage of models used to estimate material requirements. [ ] The starting point for the models are estimates of the major components of GNP for some future period. These may be estimates purchased from a forecasting service or may be produced in-house. The projections are translated into industrial final demands using DITT (Demand Impact Transformation Tables), a system developed at FPA. Then using a version of the current Bureau of Economic Analysis input-output model, estimates are made of the gross output of each industry necessary to support the level and composition of GNP as specified by the macro-economic model.

Jan 1, 1977

By J. A. Herbst, Y. C. Lo

An attempt has been made to parameterize the population balance model for a ball mill based on measurements of the elementary breakage process obtained using an ultrafast load cell device. Detailed insight obtained concerning the fragmentation of particle assemblies with the ultrafast load cell leads to a better understanding of ball mill grinding. The ball mill breakage function and specific selection function are derived from an average single event representing the multiple breakage events which occur in ball mill grinding. Since both the breakage function and the specific selection function depend on the loading mode in the mill, predictions of breakage mechanisms in ball mills are possible by using data obtained in various elementary loading modes. The application of this model to the description of batch ball milling behavior has resulted in reasonably accurate predictions of product size distributions for various energy inputs.

Jan 1, 1992

By J. David Lowell

For the first time in several years, Chile is again opening its doors to foreign investment. In its new investment code, the Chilean government has announced its willingness to become a partner in joint Chilean-foreign projects for a number of government-controlled porphyry copper deposits at the developed, semi-developed, or prospect stage; and, that it will allow privately owned deposits or deposits discovered by new exploration to be developed with up to 100% foreign ownership. Three deposits of particular interest are: El Abra, with at least 300 million mt of +100% Cu; Los Pelambres, with at least 428 million mt of 0.78% Cu and 0.03% Mo; and Andacollo, with 350 million mt of 0.70% Cu and 0.015% Mo. (El Abra is almost entirely government- controlled; but both Los Pelambres and Andacollo are mostly under private ownership.)

Jan 11, 1974

By S. Merjan

Three papers were presented for discussion at the conference: 1) Instrumented driven steel tube piles at Canary Wharf; author: A. R. Gaba, United Kingdom. The author described the Canary Wharf development in the London Docklands, and in particular, the decision to build over the water by driving open-ended steel piles 25m in length into the sands below the soft estuarine deposits. The tubes were then filled with concrete above the sand plug (usually 17m below pile head). Three trial piles were instrumented with: a) resistance strain guages on the inside of the tubes; b) vibrating wire guages on the re­inforcement of the concrete. The trial piles showed elastic behaviour in five cycles of lateral loading, while the verticle load tests showed a definite bi-linear load-settlement behaviour. The initial stiff portion was a result of frictional staff resistance, both inside and outside the tube, with the soil at the base contributing at higher settlements. Loads were taken to three times working load, with no imminent signs of failure.

Jan 1, 1991

By Kuipers A. J

Aberfoyle has been applying computer methods to mine geology in small to medium-sized underground mines since the early 1980's. Recently, the installation of DATAMINE software at the Hellyer Mine in Tasmania has allowed development of computerised applications which assist both mine geologists and mine planning engineers on a daily basis.Comprehensive data is entered into a database prior to survey coordinating to produce a processed database which can be accessed for construction of a variety of plots. The folded and faulted nature of the orebody contacts at Hellyer has necessitated the use of the structure contour method to provide a complete 3-D spatial interpretation. Computer-generated contact intersection points are hand-contoured before digitising and wireframing as a digital terrain model. This wireframe model can be sectioned in any plane for mine planning.

Jan 1, 1990

By Peter C. Ashbrook

The Regional Copper-Nickel Study was initiated in large part because of fears that copper-nickel development might cause adverse effects on the environment from air pollutants such as sulfur dioxide (SOZ) emissions from a smelter, and water pollutants such as acid mine drainage. The Study comprehensively examined the potential for ad- verse effects on the environment and possible mitigation measures on both a local and regional scale by first characterizing existing air and water quality, and existing sources of pollution, and then developing hypothetical development scenarios to model potential adverse effects. This paper gives a brief overview of the Study's findings concerning air and water resources.

Jan 1, 1980

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By Michael Karmis, Syed Muhammad Tariq, Zeshan Hyder

Secondary or boulders blasting is a regular feature of quarrying operations in Pakistan, especially in cement and stone crushing industries. The main reason for secondary blasting is the production of a large number of boulders during the production blast. These boulders are larger than the feed hopper of crushers and require further breaking. The complex geometry of boulders, relative lack of restraining burdens, and the availability of number of free faces make this kind of blasting more hazardous than production blasting. Secondary blasts have generally unpredictable results and may cause flyrock, airblast, and over-crushing of rock material. Thus, it is essential to have an appropriate amount of explosive charge/powder factor, and for it to be properly distributed in the blast hole. The greater the amount of explosive over the required amount, the more violent is the blast, which will result in more flyrock, airblast, and excessive crushing of boulders.

Jan 1, 2012

A diverse selection of rockbolt designs and resin anchors are available for use in underground mines. Research in recent years at the UNSW Mining Research Centre led to the construction of a rockbolt pull-testing facility. This facility has subsequently been upgraded, commissioned and initial test work has been completed to verify the pull-test process. A test program has been completed with the objective to understand the load transfer mechanism and improve the general performance of rockbolts. This paper describes the results of this research. Une sélection diverse de dessins du rockbolt et ancres de la résine est disponible pour usage dans les mines de métro. Faites des recherches ces dernières années à l'UNSW que le Centre de la Recherche Minier a mené à la construction d'une facilité de l'essai de la traction du rockbolt. Cette facilité a été améliorée par la suite, le travail de l'épreuve en commission et initial a été complété pour vérifier le processus de la traction-épreuve. Un programme de l'épreuve a été complété avec l'objectif comprendre le mécanisme du transfert de la charge et améliorer la performance générale de rockbolts. Ce papier décrit les résultats de cette recherche. Eine verschiedenartige Auswahl an rockbolt-Designs und Harzankern ist dafür verfügbar, benutzen Sie in unterirdischen Bergwerken. Forschung in letzten Jahren beim UNSW-Bergbau Forschung Zentrum führte Ruckerprobung-Einrichtung zur Konstruktion eines rockbolt. Diese Einrichtung ist anschließend befördert worden, ist beauftragt worden und wird abgezeichnet, prüfen Sie, die Arbeit ist vervollständigt worden, um den Ruckprüfung-Prozeß zu verifizieren. Ein Prüfungsprogramm ist mit dem Objektiv vervollständigt worden, den Lastübertragungsmechanismus zu verstehen und die allgemeine Aufführung von rockbolts zu verbessern. Dieses Papier beschreibt die Ergebnisse dieser Forschung.

Jan 1, 2003

Chlorine as a lixiviant for gold possesses a number of significant chemical and Idnetic advantages over cyanide but because of its corrosive and vaporous nature the method of implementation needs to be significantly modified. At comparable reagent concentrations the dissolution rate for gold in the C12/Cl- systems is some 10 - 100 times that achieved in the 02/CN system. The dissolution rate in the chlorine system is largely a function of the concentration of C12, Cl- and pH. Under conditions of low Cl', (less than 50 g/1), the dissolution rate begins to drop off dramatically over the pH range from 3 - 4. Increasing the level of dissolved chloride ions shifts the pH of this rate reduction to around pH 5 at 100 g/l NaCl, and to around pH 6 at 300 g/l NaCl.

Jan 1, 1991

By R. Browner, J. Collard, D. Ibana

The extraction of cobalt from synthetic pressure acid leach solutions of nickel laterite ores by the direct solvent extraction route using ESPLIM is reported. It first explored the use of gaseous ammonia as pH modifier and then the variables that affect the dispersion of the aqueous phase in the organic phase such as ionic strength, viscosity of the phases, initial droplet size, etc. were explored so that phase hold-up and thus extraction can be effectively controlled. The results show that the technique allows better control of phase dispersion circumventing one of the main weaknesses of conventional solvent extraction.

Jan 1, 2005

By R. C. Fox

The geophysical aspect of reconnaissance marks the beginning of extensive computer applications supporting development of a mine. Although there are some storage and retrieval applications in geology, and some statistical analysis in geochemistry, large-scale compilation, reduction, and interpretation of mineral resource data are initiated in reconnaissance geophysics. The reasons for this fact are quite simple. Geophysics is oriented toward quantitative evaluation of areas of interest, and methods of data collection are automated to the extent that large amounts of analog and digital information are recorded. The large volume of data must be interpreted in a reasonable time. Furthermore, some modeling problems involving complex numerical solutions could not be attempted without the computer. Therefore, the computer is essential to the success of an exploration project using geophysics. For example, aeromagnetics is a common technique for reconnaissance examination of areas associated with sulfide systems and porphyry deposits. An area covering 161 X 161 km (100 X 100 miles) may be flown with a 1.6-km (1-mile) line spacing yielding 10,000 line miles (16,093 km) of data. If only 10 measurements are recorded per mile, 100,000 data points, including location and magnetic field intensity, must be reduced and stored for quantitative interpretation. Computer applications often represent a significant investment in manpower and hardware. It is desirable, therefore, to initiate an engineering approach to the application of computers to geophysics. By this it is meant that computer programs and systems should be formulated, developed, and implemented in a disciplined manner such that their usage is dependent only on the application and not on the individual doing the programming. In other words, computer application, development, and usage should evolve beyond the personal gadget phase to an important applied technology. Geophysics has evolved over the past two decades in a course parallel to computer hardware development. During the sixties, the computer became large enough and fast enough that complex models required by geophysics could be solved. Automation also relieved the geophysicist from routine manual calculations. During the seventies, computing power in¬creased and applications expanded from two-dimensional problems to three-dimensional modeling. Moving into the eighties, as computer hardware costs will significantly decrease, the major expense of computing will be the manpower required to develop, implement, and use an application; therefore, improved programming techniques and applications software engineering methods will be used to optimize and preserve this investment. This chapter presents a general overview of computer methods in geophysical reconnaissance; it is divided into two parts: geophysical methodology and software engineering.

Jan 1, 1979

By N. Moemise, M. B. Shongwe, P. A. Olubambi, M. M. Ramakokovhu

"Near-infrared (NIR) spectroscopy sorting technology is incorporated in an automated optical mineral sorter that can discriminate between materials using the differences in characteristics when exposed to near-infrared radiation. During September 2014 to April 2015, a pilot plant that utilized NIR technology to discriminate between kimberlite and waste materials was commissioned to determine the viability of including this technology in the diamond winning process flow sheet at Cullinan Diamond Mine. The plant was used to minimize the waste content in the size fraction -70+35 mm that reports to the crushing section and then to the dense media separation process. This paper describes the initial test work, conducted at Mintek, that led to the decision to conduct a pilot-scale study. The mineralogical characterization of the feed and product streams to establish the sorting criteria and the operational data obtained during the pilot plant campaign are described. The results indicated a good possibility of discriminating between the kimberlite and waste material using NIR technology. However, the consistency of discrimination was not good enough to avoid the risk of potential diamond loss. Furthermore, a lower than expected availability of the machine reduced the throughput capabilities. IntroductionUsing near-infrared spectroscopy (NIRS) technology for ore sorting is a new concept for the mineral processing and mining industry. NIRS has been used for decades in the laboratory for the identification of pure minerals, and has its roots in the recycling, food, and pharmaceutical industries (Salter and Wyatt, 1991; Robben et al., 2009). Ore sorting in itself is not a new concept; it was introduced during the Stone Age with handsorting being the first method to separate valuable materials from gangue (Wills and Napier-Munn, 2006; Sassos, 1985). However, over the years the scale of mining has increased and hand-sorting has become challenging to implement (Joensson, 2014).Sensor-based sorting is an advanced technology that can help overcome problems such as ore dilution experienced in mineral processing operations. The benefits are lower energy and water costs, reduced ore dilution, lower environmental impact, and improved profit margin (Mathew, 1974; Jonsson, 2014; Salter and Wyatt, 2009; Death et al., 2009). In sensor-based sorting, materials are mechanically sorted based on certain physical properties that are detected by a sensor (Dalm, 2013). Research has found that with NIR scanners it is possible to obtain a ‘fingerprint’ of a sample that is directly related to its mineralogical composition. According to Woutruba et al. (2009), molecules absorb NIR radiation by means of electronic and vibrational transitions. Nowadays, there are many sensors available in the market that utilize different material properties; the choice of a sensor is dependent on the mineralogy of the ore."

Jan 1, 2016