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By AJ Rorke, JD Botes

Presplit blasting in strip mines is aimed at creating a safer wall to work under during the coaling operations. Good quality presplits are also necessary for effective throw blasting and drainage of the blast block. A less obvious but important function is full coal recovery. Optimum Colliery has been experiencing rock freezing against the presplit highwalls. The rock formed in patches along the highwall and trapped coal beneath it. The material that was &ozen comprised the rock between the back row of holes and the presplit and was often up to 3 m thick (the stand off distance between the back line and the presplit). The cozen rock formed predominantly along the bottom halfor bottom two thirds of the highwall. Along the top portion of the highwall, the presplit crack was usually well formed with visible barrels. This problem, or similar variations of it, is common on many South African strip-mine operations. Investigative work was carried out at Optimum Colliery to correct the problem. This paper presents the information and measurements that were made and discusses the solutions that have been applied to solve the problem. It was found that there were two independent causes for the tiozen material, with each contributing more or less to the frozen rock along the highwall. It was found that the presplit was not forming properly in places, especially closer to the bottom of the highwalls. The reasons and the solutions are presented. The second cause was found to be associated with reduced detonation velocity in the back line holes coupled with low confinement from long delay periods. Emulsion explosive that is sensitised with air bubbles was found to be prone to this phenomenon near the back of high-energy blasts. A change in the explosive formulation in the back-line holes, together with reduced delays in the back line, has resulted in significant improvements. The details are presented in this paper.

Jan 1, 2000

By E. Wasmund

"Sandfire’s DeGrussa Copper-Gold operation in West Australia is a new high grade copper sulfide mine, which includes a 1.5 Mtpa concentrator which was completed in 2013.Early after commissioning, it was identified that the flotation capacity in the all-mechanical cleaner circuit was not sufficient. In order to improve recovery, the tail from the cleaner scavenger was sent back to feed the rougher scavengers. Test-work was done on-site to evaluate the possibility of using a flotation column as a pre-cleaner. A CavTube™ sparging system was selected, which is especially effective for fine ore particle flotation. Test-work was conducted at site using a 150 mm diameter unit, and then confirmed on a 500 mm diameter unit. A 4250 mm diameter full scale unit was installed in Q4 2014 and commissioned in Q1 2015. This unit gave some significant advantages including a reduction in re-grinding requirements, elimination of a circulating load and increase in the recovery of copper in the cleaner circuit and overall circuit.In this presentation, the benefits of columns and cavitation sparging for floating fine particles and rejecting fine entrained gangue will be explained. Also, the results from a lab unit and a pilot unit will be compared against the results of the full-scale unit. The paper will demonstrate the scalability of flotation columns, and which phenomena and scale-up criteria must be considered to be successful. Finally, some general observations will be made about the importance of columns in copper cleaning circuits.IntroductionSandfire Resources’ DeGrussa copper-gold concentrator is located approximately 900 km north-north-east of Perth in Western Australia. The project area landscape is scrubby mulga lands with few notable features. The climate is arid with high temperature and heavy summer downpours."

Jan 1, 2016

By Alfred Bellows

The objective was to develop and design a remotely operated temporary roof support system that provides a safe working environment between a freshly cut coal face and the last line of permanently supported roof in which to perform roof bolting activities. This system was to take the form of a retrofit package which could be adapted to a majority of the bolters currently in service. The result is an integrated piece of hardware which will retrofit onto virtually all single boom bolters by removing the drill boom and relocating and modifying the hydraulic controls. The system is composed of three basic components: a pair of cantilevered roof supports which reach forward to the desired line of support, a mast type drill unit for drilling holes and torquing bolts, and a transverse slide assembly to carry the drill from hole to hole across the entry without relocating either the bolter or the roof support. A converted bolter not only provides a much safer operation but is projected to increase the production speed as well as reduce the manpower required to operate a section.. This improvement in productivity is shown to make the job of retrofitting a bolter cost effective in less than two months and provide a potential profit thereafter. Based on the findings presented in this report it is recommended that a proto-type be built and tested in an underground coal mine to demonstrate its effectiveness.

Jan 1, 1976

By R. A. Gee, G. B. Ashton, S. T. Warren, P. N. Groves

Northside Storage Tunnel provides 500 megalitres (Ml) (130 million gallons) of storage capacity to capture stormwater/sewage overflows into Sydney Harbour. The6.6 m diameter TBM driven tunnel traverses Middle Harbour 85 m (280 ft) below sea level and through a sandstone/shale rock mass, highly disturbed by stress relief, 20 m(65 ft) beneath the base of the sediment filled palaeochannel. Target limits for inflow, groundwater drawdown and settlement of the valley beaches were achieved by systematic forward grouting from the TBM. Support included rockbolts, sets and shotcrete to carry rock loads, control block instability and spalling and to provide durability and serviceability. This paper describes the tunnelling and grouting works and their effectiveness.

Jan 1, 2001

By S. Hunt, D. de Vries

Kansanshi Copper Smelter began operation in March 2015. The smelter features a single Isasmelt furnace for smelting, one 6-in-line electric furnace for matte-settling and slag-cleaning duties, four Peirce- Smith converters and two rotary anode furnaces. A 1,450 t/day oxygen plant and a 4,085 t/day sulphuric acid plant are included in the smelter operations. This paper gives an overview of the operational performance to date with summary data for each smelter section. Challenges such as an unforeseen refractory failure in the Isasmelt furnace in 2016 are discussed. Design improvements around the electric furnace are mentioned. Plans for potential future improvements are put into context. A consistent focus on operations, maintenance and continuous improvement has seen the smelter easily achieve its nameplate capacity of 1.2 million tonnes per annum of copper concentrate throughput. The smelter now operates consistently at a concentrate throughput rate of 1.38 million tonnes per annum of copper concentrate. INTRODUCTION The smelter was commissioned in March 2015. Design and commissioning of the smelter have been discussed by de Vries, Hunt, Hanschar and Louie (2016). The smelter rapidly ramped up to achieve nameplate production (1.2 million tonnes per year concentrate) and in 2018 operated consistently at the rate of 1.38 million tonnes per year concentrate. This paper presents major operational data for each section of the plant and describes significant events and improvements during the first four years of operation. The smelter flowsheet is shown in Figure 1.

Jan 1, 2019

Carbon anode cells were studied by two-dimensional computer simulation to evaluate their suitability for alumina electrolysis at high superficial current densities. The most efficient anode arrangement was needed to overcome the electrochemical disadvantages of alumina's low solubility in chlorides. Cells with packed-bed anodes might provide practical superficial current densities greater than 0.67 A/cm2 when the granule size was less than 1 cm, but in the process of electrolysis the granules within the active zone would be consumed and become smaller, affecting alumina concentration transport. For zones of very small granules a concentration-dependent model should be considered; for more complete consideration a time-dependent model can be introduced to describe the variation of granule size and its influence on mass transfer and polarisation

Jun 19, 1905

By T. A. Grammatikopoulos, B. Vasily, A. H. Clark

"The St. Lawrence deposit is a large wollastonite skarn (ca. 9 Mt @ 41.3% wollastonite) adjoining the gabbroic-to-syenitic Leo Lake pluton in the granulite facies Frontenac Terrane of the Grenvillian Central Metasedimentary Belt. It occurs within a horseshoeshaped horizon of quartzite, open to the east. The skarn extends over 1.2 km2, and comprises wollastonite-dominant, wollastonite-clinopyroxene, and diverse quartz-feldspar-sulphide (-titanite) layers, interbanded with, and strongly folded within, the quartzite. As in the world-class wollastonite deposits of the Willsboro district, New York, no carbonate protolith is preserved, and calcite is a negligible constituent of the mineralized zones. Wollastonite development is nonetheless ascribed to metasomatism of a metacarbonate unit by magmatogene, silica-rich, CO2-poor (XCO2 < 0.05) fluids, at P = 350 MPa and ca. 560°C, or, alternatively, 550 MPa and ca. 630°C.Several high-grade zones, averaging >40% but locally exceeding 80%, of translucent, white, tabular wollastonite grains, with lengths of 0.2 cm to 5 cm, have been delimited by drilling. Preliminary beneficiation studies yield high aspect-ratio and high-purity (low Fe and Mn) concentrates.St. Lawrence compares favourably to other known prospects and operating wollastonite deposits: having good chemical and physical properties, low iron content, and high aspect ratios (>20:1). In addition, the deposit has a favourable size and location, and will benefit from a low Canadian dollar. Canada currently has no wollastonite production."

Jan 1, 2003

In order to ensure safe mining and reduce surface damage in shallow multiple-seam mining, the failure characteristics of interburden strata with different coal pillar offset distances between pillars in the upper and lower seams, the distribution characteristics of stress concentration in coal pillars, and the development characteristics of stratum cracks and subsidence were physically investigated and also using UDEC2D software. Meanwhile, the effect of different coal pillar offset distances on the stress concentration of coal pillars and development of stratum cracks were studied. Based on those results, a formula for safe mining and reducing surface damage was established, which provided a theoretical basis for safe and environmentally friendly mining in shallow multi-seams. According to the results of the study, the optimal coal pillar offset distance (the side-to-side horizontal distance of the upper and lower coal pillars) between the upper and lower coal seams was developed to reduce the stress concentration of coal pillars and surface damage. The results of this study have been applied in Ningtiaota coal mine and have achieved good results in safe and environmentally friendly mining.

Jul 28, 2020

By J. E. Sepulveda, R. Morrow

"The Linear Wear Theory provides a reliable framework for the assessment of grinding media performance at full scale. This theory can be applied for analyzing grinding media consumption rates in any given grinding operation as well as the evaluation of alternative grinding media products, based on actual operational data, correcting for conditions like ore hardness, feed and product sizes, mill power and circuit throughput; all of them unrelated to the grinding media intrinsic quality attributes. A series of Moly-Cop Tools 3.0 applications have been developed to facilitate the calculations involved. Moly-Cop Tools 3.0 is available, free of charge, to all interested parties through the corresponding author.INTRODUCTION Mineral grinding circuit operators recognize the significance of grinding media (balls) consumption on the cost structure of any full scale grinding facility. The effective cost associated with this essential consumable depends on two factors: delivered price and durability (quality) of the grinding media. When evaluating alternative grinding media varieties, there is a well accepted evaluation criterion by which a given media type is considered to be “cost-effective” when its unit application cost – normally expressed in $/ton of ore ground – is shown to be lower than that of a nominal reference condition: Grinding Media Cost = Ball Price x Ball Consumption (1) ($ /ton ground) ($/ton balls) (ton balls/ton ground) Under this criterion, an alternative, higher-price grinding media product could be “cost-effective” if its associated consumption rate is sufficiently lower than the reference media, enough to yield a lower grinding cost, as dictated by Equation 1. For the proper application of the above criterion, evaluators must rely on representative indicators of grinding media quality, ideally independent of most mill operating conditions. In each particular case, ball price is always a known component; however, it is not so evident how media performance (quality) differences amongst alternative product types could be assessed with a reasonable degree of accuracy and precision."

Jan 1, 2014

By David A. Bacca

Hydraulically powered submersible borehole dewatering pumps and emulsion/ANFO blends evolved at about the same time and for the same reasons. Mining operators needed safe, efficient dewatering systems and water resistant products.

Jan 1, 1994

By Louis A. Panek, John A. Stock

A flat slot is created in rock to cause stress relief effects in a pair of hydraulic borehole pressure cells (previously installed in drill holes above and below the slot ) , which act as sensing devices . This relief is annulled by repressuring the slot by means of a flat hydraulic cell . The slot pressure at annulment is taken to be the existing ground stress at right angles to the plane of the slot . A number of trial installations in the rib of a mine drift showed that for a valid determination of ground stress the sensing devices that respond to relief and repressuring must be within a specified zone close to the pressure transmitter ; otherwise the indicated ground stress may be excessive . By using an additional pair of borehole pressure cells , installed a few feet away , the existing rock stress can be redetermined at intervals , irrespective of a change of stress intensity subsequent to the initial installation . Based on these findings , equipment and procedures have been developed that make possible the installation and operation of a permanent rock stress monitoring station for observing mining - induced stress changes . The station consists of a 12 - in - wide hydraulic pressure cell cemented in a flat slot and four 2- by 8 - in flat hydraulic pressure cells in nearby drill holes . All drilling for the installation can be done with an air leg drill and conventional bits . Once the installation is completed , all required information is obtained by Bourdon pressure gage readings . The apparatus is simple , relatively inexpensive , and reliable under operating conditions in a wet mine . Unlike most methods of rock stress determination , this scheme permits periodic remeasurement of absolute rock pressure over several years , without additional drilling or instrumentation . Similar to other flat slot procedures , stress measurements are obtained without making auxiliary tests to determine elastic

Jan 1, 1964

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 Campbell Brown GA

IN 1904-5 diamond drilling operations in the Mount Morgan mine proved the presence of some inillioils of tons of rich, copper-gold ore, averaging about 45% to 50% silica and 22%Fe as sulphide. To smelt this ore in blast furnaces, without previous concentration, large quantities of basic flux.were required. Unlimited quantities of cheap, limestone, were available at Marmor, on the GladstoneRockhampton railway, 50 miles from Mount Morgan, but the supply of iron flux was a more difficult problem. Smelting operations started, with one&apos; furnace in January, 1906, using as flux low-grade sulphide ore fro:m. the mine, containing very little silica. When the second, furnace was blown in this was supplemented by ironstone from, small aeposits in the immediate district. It was recognized that these sources of supply would be insufficient to keep the full plant going after the third furnace had been blown in. Accordingly, the deposits at Eabra and Mount Etna were opened, neither of which proved capable of supplying the quantity required viz, 1000 tons per week. Negotiations were meanwhile being conducted with the Marble Island Iron and Limestone Co. to obtain the right to mine at Iron Island, where a sufficiently large deposit was known to exist. Shipments from this source commenced in January, 1907, and ceased at the end of July of this year, when the metallic flux from...

Jan 1, 1912

By A. R. Miller

A fuel cell locomotive incorporates the advantages of its competitors, namely catenary-electric and diesel-electric units, while avoiding their disadvantages. It possesses the environmental benefits, at the vehicle, of an electric locomotive but the higher overall energy efficiency and lower infrastructure costs of a diesel locomotive. The natural fuel for a fuel cell is hydrogen, which can be produced from many renewable sources or via nuclear energy, and thus a hydrogen-fuel cell locomotive will not depend on imported oil. Hydrogen produced from renewable primary energies or nuclear energy would provide a totally zero-emissions vehicle, that is, with zero carbon in the energy cycle. A project partnership among Vehicle Projects Inc of the USA, and South African partners Anglo American Platinum, Ltd, Trident South Africa, and Battery Electric, has designed and is launching a series of five prototype fuel cell-powered mine locomotives.

Jan 1, 2012

By J. J. Bouillon

"Located in the northwestern portion of the Abitibi greenstone belt, Les Mines Selbaie is a copper-zinc (silver and gold) producer. Felsic tuffs host three are zones. Composed of sulphide veins and breccias, they are not exhalative massive sulphide deposits, except, probably, for the massive pyrite (fragments and lenses) localized close to the top of the volcanic sequence.The total of all (mineable and mined) ore in the three zones presently outlined on the property, is of the order of 29.9 x 106 tonnes with average grade of 0.63 g/t Au, 37.02 g/t Ag, 1.21% Cu, 1.91% Zn.The ore reserve calculations and the daily production procedures are computerized to various degrees. The data handling process is highly computerized.Various geophysical methods are, and have in the past, been successfully used on the property. The ""mise-à-la-masse"" surveys were used to perform the geological interpretation of an underground deposit (A-2 zone). Presently the PULSE-EM surveys are performed in all surface and underground exploration drill holes."

Jan 1, 1990

By Alexander N. Winchell

"Location. The copper mines of Michigan are all in the northern part of that state on the Keweenaw Peninsula, which extends from the (Michigan) mainland for about seventy miles northeasterly toward the middle of Lake Superior. The mines occur in a belt or zone occupying the central portion of the peninsula from end to end.. The most productive mines for many years past have been those located not far from the city of Houghton in&apos; the central part of the zone, in a section extending about ten miles southwest of Houghton and fifteen miles northeast. The most important mines in order of location, from the northeast to south¬west, are the following: Mohawk, Ahmeek, Allouez, North Kearsarge, Wolverine, South Kearsarge, Centennial, Calumet. and Hecla, Osceola, Franklin, Quincy, Hancock, Isle Royale, Superior, Baltic, Trimountain, and Champion. The first three named are in Keweenaw county and all of the others are in Houghton county. Still farther to the southwest are the Lake, Mass, Adventure, Michigan, Victoria, and White Pine mines. These are in Ontonagon county.History. The exploitation of these copper mines extends back into prehistoric times. There is little evidence that the American Indians carried on mining operations in this region in the period shortly before the advent of white men, but there is abundant evidence that the ancestors of the Indians, •or some earlier inhabitants of the region, carried on primitive mining operations. For example, Mr. S. O. Knapp, Agent of the Minne¬sota Mining Company, in the winter of 1847-48, made the first discovery of prehistoric mining. This event is described as follows by Foster and Whitney :"

Jan 1, 1920

Mine Evaluation Engineering , Operational and Social evaluation. Focus is on what opportunities are available. Social ??History ??Past Management Practices ??Community / Available labor force Mining Method / Equipment ??Competent rock ?little support required, no backfill ??Shallow mining ?ramp mining, no shafts or hoisting ??Large scale mining potential ??Simple rock breaking and crushing on surfaceMill Process ??Straightforward gold liberation process Create a Plan / Create a Team Following the feasibility 44-101. Key people were hired and a full operational Business Plan was developed. Focus is on how to get the job done. ??Scoping Study / Pre-Feasibility / Feasibility ??Operational Business Plan ??Hire key people ??Purchase key equipment

May 1, 2006

The proper selection of a coal for a particular use depends on knowledge of fundamental data concerning the coals that offer, particularly their type and rank. Type of coal depends on the nature of the original plants and the environment in which they accumulated.Rank reflects the subsequent metamorphism of the coal, and is of two kinds-physical rank and chemical rank.INTRODUCTIONIn the different coalfields of the Commonwealth of Australia there occur many different kinds of coal which provide the coal-research worker with a wide range of material, but to the fuel technologist they represent complex problems in utilization.In the past it has been common practice to instal coal-using equipment of a design based on plant used in large industrial centres of other countries and then search for supplies of suitable coal. This has led to the transportation of coal mainly from New South Wales to other States, which have inadequate supplies of coal suitable for use in the equipment they have installed. However, modern economy and industrial practice demand local resources of coal for the development of industry, transport and domestic services, and a change in the old order is rapidly taking place. Technologists and engineers are now faced with the problem of designing and installing equipment to use whatever kind of coal is available in local coalfields.Much has been accomplished in this direction and important investigations are at present being carried out, but there still remains a wide field of problems for research.In planning and carrying out investigations into coal utilization it is essential that fundamental data and knowledge should be available and that its significance should be appreciated.

Jan 1, 1955

By L. Watters, R. Terry, D. Placha

Dense medium cyclones are the preferred means for cleaning 1/2 in. x 14Mesh to 28Mesh (12.7 mm x 1.0 mm to 0.6 mm) raw coal and are becoming a common choice for cleaning raw coal from a nominal top size of 2-1/2 in. to 3 in. (63.5 mm to 76.2mm) down to 14 Mesh to 28Mesh (1.0 mm to 0.6 mm). During the last ten years, dense medium cyclone circuitry design has undergone changes which have combined to improve process efficiency. This paper describes these improvements and compares present day design with the design used prior to the mid 1980&apos;s. Improvements in the following areas are described: Raw coal desliming, cyclone configuration, drain and rinse applications, dilute medium circuitry, and instrumentation and control.

Feb 24, 1997

By Paul R. Smith

The Colorado School of Mines Research Institute (CSMRI) was founded in 1949 to fill mining industry and government needs for minerals research and development. The operations of scores of mines, mills, and plants around the world are based on the results of work done by the Research Institute. Among other things, the Research Institute conducts studies in geology, mine planning, mineralogy, size reduction, minerals processing, and hydrometallurgical techniques in extractive metallurgy. Many CSMRI projects also involve energy and environmental considerations. What follows is a summary of some of the studies in which the Research Institute has been and is currently involved, as well as some comments on trends and developments in the industry.

Jan 2, 1982