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By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012

By Dan A. Brown

The New Mississippi River Bridge (MRB) employed conventional design-bid-build procurement, but the bidding process included the opportunity for pre-qualified bidders to develop and propose confidential Alternative Technical Concepts (ATC?s) for evaluation and approval in advance of bidding. The ATC process provides a mechanism for value-engineering prior to bid, with incentives and opportunities for both the owner and the bidding contractor. The contract described in this paper is for the river bridge composed of a cable-stayed crossing with two pylons and the anchor piers on each side of the river. The Massman-Traylor-Alberici (MTA) team developed a re-designed foundation system for the main pylon and anchor foundations which utilizes their equipment and experience along with field load test measurements to optimize the foundations. The paper describes the experience with the use of the pre-bid ATC process on the project from the perspective of the bidder, and outlines some of the benefits and limitations of this concept with respect to foundation design and construction. Some keys for success are identified and impediments to the effective implementation of the process are described.

Jan 1, 2011

Identifying Opportunities to Reduce the Consumption of Energy Across Mineral Processing Plants

Sep 13, 2010

By Heiner J. Sander

Stanford University operates the National Research Facility which is located at the Stanford Linear Accelerator Center (SLAC) in Menlo Park, California. In order to improve and allow for enhanced experiments, the current facilities required expansion. A1500 foot long tunnel (20 ft wide by 21 ft high) and a 220 foot long underground cavern (49 ft wide by 32 ft high) were excavated through the Ladera Sandstone formation which is an intermediate geo-material with week rock properties. The overburden between surface and crown of the structures varies from 10 to 80 feet. The underground structures were excavated according to the principles of the NATM (New Austrian Tunnel Method). This paper addresses the challenges that were encountered during the construction phase of the project and how construction issues were resolved mutually by the owner, engineer and contractor. The implementation of geotechnical instrumentation, recorded data and interpretations, soil conditions and behavior encountered during construction are also presented.

Jan 1, 2008

By E Breese

The Grey River dredge is the first large scale alluvial operation to be permitted under the Mining Act 1971 and the Water and Soil Conservation Act 1967. The experience of Grey River Gold MiningLimited in pursuing these statutory approvals has identified weaknesses and strengths in the present system and problems which need to be resolved. The Company has learnt lessons, which if heeded, will assist future large scale alluvial mining projects.

Jan 1, 1989

By P. J. Baguley

The model has been developed on the basis of the observation that the partitioning behaviour of a particle is related to its calculated terminal velocity. It utilises a theoretical calculation of the terminal velocity of each particle class. This is then correlated with the observed partition data for a plant separator using empirically-derived functions of operating conditions which take into account effects such as bath turbulence, holes in drum lifters and feed arrangements. The model successfully decouples the effects of medium density and viscosity and is appropriate for any bath-type separator. The correlation between calculated terminal velocity and actual partitioning behaviour was established and modelled using data obtained from two Wemco drums treating Fe and Mn ores. The model can be used to predict the prevailing size-by-size partition curves and the separation (product grades/recoveries) given the washability of the feed and operating conditions. Simulations are used to show that, for the treatment of Fe ore, there is a maximum medium density beyond which product grades fall and that this maximum decreases as the proportion of magnetite in the medium increases. This is attributed to the dominant effect of viscosity at higher medium solids concentrations

Jun 18, 1905

By A Jewbali, J Phillips, C Boyle

Normal practice in the mining industry is the creation of a single geological model. These models provide a single interpretation of the geological and mineralisation domains. These interpretations infer the exact behaviour of ore domain contacts at shorter scales when resource definition drilling is done on wider scales and are thus locally highly uncertain. The interpreted geological model provides a single number for the volume and tonnes of mineralised material enclosed by the mineralisation envelope. It is on this single number for volume and tonnage that capital intensive mine development decisions (mine design and scheduling, stockpile strategy, waste management, closure planning, dewatering strategy, product quality, etc) are based. Some of these decisions require knowledge of grade variability for small volumes of material such as quarterly production periods. It is generally recognised that this information cannot be derived from single kriged geological models, but can potentially be modelled by conditional simulation techniques. Uncertainty in the extent and continuity of the mineralised envelope and its effect on grade variability for shorter production periods is thus recognised as a major source of uncertainty in new mine development.CITATION:Jewbali, A, Boyle, C and Phillips, J, 2013. Quantifying domain uncertainty for an iron ore deposit, in Proceedings Iron Ore 2013 , pp 157-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Hugo Julien

According to OSHA 29 CFR Part 1910.119 (Process safety management of highly hazardous chemicals), Canadian Provincial Safety Standard Acts or Federal laws, the owner of stationary equipment (Boilers, stacks, piping, pressure vessel, etc.) should follow a complete inspection plan and follow an Integrity Operating Windows (IOW’s) adapted for each of them. Some important variables shall be included in the inspection plan such as specific damage mechanisms versus alloy used in the original design, process conditions, etc. Some North American’s standards exist, like the one listed in ASME PTB-2-2009, to help owner to create such inspection program. The new API RP 584, Integrity Operating Windows (IOW’s) can guide Mining & Metals owners to find out their specific IOW’s. Inspection frequencies are often described in the Jurisdiction Safety Acts such as the British Columbia B.C. Reg. 104/2004, etc. but often left in the owner representative responsibility (Bill C-21, federal Act to amend the Canadian Human Rights Act). Every deficiency should be repaired according to recognized Codes such as ASME PCC-2, etc.. If flaws not conforming to the original Code of construction are found, this article will introduce the Fitness-For- Service assessment principles to be able to accept it without any repairs.

Jan 1, 2014

By T. Johnson

Hydrometallurgical processes can be exceptionally corrosive. This is particularly true in acid leaching processes for copper, cobalt, nickel and rare earth elements. In the last five years, several large hydromet plants have been built in North America (Vale - Long Harbour, Baja Mining ? El Boleo and MolyCorp - Mountain Pass). Hundreds of storage tanks, extraction vessels and electrowinning cells along with miles of piping were designed and fabricated to withstand the aggressive environments inherent in these processes. One key element all three projects had in common was the extensive use of FRP in equipment design. As a material of construction, FRP provided equal if not improved durability relative to alternative corrosion resistant alloys at a considerably lower cost. This paper will highlight the extensive use of FRP in these three world scale projects and why it was chosen for each process.

Jan 1, 2013

By O. C. Garst

"The lightness and relatively high strength per unit weight of certain magnesium alloys have interested designing engineers for many years. Ever since the noted investigator Bunsen3/ first produced the element by electrolysis of the fused chloride in 1852, utilization of this light metal has been considered. Magnesium is widely distributed over the earth's surface in high-grade as well as low-grade deposits; it occupies eighth place in the list of elements arranged in order of their decreasing abundance, as there is 2.24 percent magnesium in the earth's lithosphere. Even though the element is distributed widely in the form of relatively insoluble: minerals and also as soluble salts in sea water and spring water, as well as being an indispensable constituent of plants and animals, the technology of magnesium was slow development. This slowness of development was first caused by confusion or the part of the early investigators who thought that magnesia, magnesite, magnetite, and the pyrolusite-type manganese ores were compounds of the same metal. At one time the metal that we now know as manganese was called magnesium, and magnesium was called either magnium or talcium. In addition to this coon, the chemical activity of the metal, especially at high temperatures, created problems that are still difficult to solve.With the advance of science in all branches, .methods for -he production of magnesium were developed. The methods first used for producing the element were: (1) reduction of magnesium salts with alkali metals,4/ (2) electrolysis of aqueous solutions of magnesium salts, and (3) electrolysis of fused magnesiun salts.The first attempts to produce magnesium by the carbothermal reduction of magnesia were failures as sufficient thermodynamic knowledge concerning the reversibility of the reaction between magnesia and carbon was not at hand. As the igneous electrolytic Method for making the element was more easily controlled than the others and. yielded more metal per unit of energy, considerable work was expended on the improvement of this process. The work in this field paralled that on the electroreduction of aluminum and the alkali metals. For several years the entire magnesium industry was dependent on this igneous electrolysis process for its supply of the metal, but as demand for the metal increased and more scientific knowledge was available, other processes were developed. Today magnesium is produced by the electrolysis of molton magnesium chloride electrolytes, the carbothermal reduction of magnesia, in arc furnaces followed by shock cooling of the furnace gases by a coin inert atmosphere, and the silicothermal reduction of calcined dolomite in stainless steel retorts."

Mar 1, 1946

By M. Hooman, W. M. Marx, R. C. W. Webber-Youngman

This paper discusses a study that investigated different underground bulk air heat exchanger (>100 m3/s) design criteria. A literature review found that no single document exists covering all design criteria for different heat exchangers, and therefore the need was identified to generate a guideline with decision analyser steps to arrive at a technical specification. The study investigated the factors influencing heat exchanger designs (spray chambers, towers, and indirect-contact heat exchangers) and the technical requirements for each. The decision analysers can be used to generate optimized, user-friendly fit-for-purpose designs for bulk air heat exchangers (air cooler and heat rejection). The study was tested against a constructed air cooler and heat rejection unit at a copper mine1. It was concluded that the decision analysers were used successfully. This tool (decision analysers) can be used by engineers for the efficient and cost-effectively design of heat exchangers.

Jan 1, 2015

By Heikki Jalkanen

The mineralogical composition and morphology of solidified copper smelting and converting slags are of some interest from slag cleaning (by froth flotation), impurity elimination, and environmental points of view. Properties result from both the state of molten slag before solidification and processes taking place during solidification and cooling. In solidification and cooling, copper and sulfur dissolved in molten slag are .precipitating substantially from the silicate phase. Even in water quenching of slag, dissolved copper is pushed out of the solution in the form of finely divided precipitate. Elements present in the raw materials are distributed in a distinct manner between the solidified slag and non-silicate solidification products. Arsenic, antimony, and tin are strongly accumulated in copper precipitate, but not the other metallic constituents common in copper concentrates. Smelting and converting slags differ remarkably on their mineralogical composition and morphology although resulting principally of same chemical processes. Converter slags are more inhomogenous; they often contain solid particles and copper content is .as a rule higher than in matte smelting slags. The final copper content of converter slags was observed to be in a distinct manner dependent on iron oxide - silica ratio. Slag forming, solidification, and precipitation phenomena are discussed on the basis of mineralogical and morphology analysis of smelter slags and laboratory scale experiments.

Jan 1, 2002

Three methods of gold analysis are briefly described highlighting some of the problems and advantages of each. The variation of results between samples and splits and due to method of preparation is illustrated. The mean per cent difference of the fire assay values from the means of sample split values for three cases is 15 per cent.Finally, a comparison of the aqua regia leach atomic absorption spectroscopy (AAS) and fire assay fusion AAS techniques is made.This shows that the mean precision, the ability to obtain the same value, of the methods at 98 per cent confidence is ± 30 per cent and ± 15 per cent respectively. The fire assay fusion AAS method is relatively more accurate than the aqua regia one.

Jan 1, 1984

By L. G. Stolarczyk, Y. Luo, S. S. Peng

Detection and assessment of severe geological anomalies ahead of a longwall face greatly benefits the mining operation. Electromagnetic-based Radio Imaging Method (RIM) is one of the most promising geophysical methods for this task. Based on two decades of development, the latest RIM instrumentation (RIM-IV) has expanded its operational range up to 1,800ft.A site demonstration of the RIM-IV technology was recently conducted within a longwall panel. An extensive ground truth study was performed to evaluate the accuracy of the RIM survey results. This study compared the generated RIM tomograms of attenuation rate with the mapped geological anomalies. Three different approaches have been employed to examine the accuracy of the RIM results and to correlate the measured signal attenuation rates with physical properties of the coal seam. The study shows that the RIM-IV technology is able to identify and delineate those geological features that would severely affect the longwall mining operation.

Jan 1, 2004

By D. Denton, L. Buckingham

The dry grinding and leaching circuits of the Barrick Gold’s new Roasting Facility at Goldstrike Mine in Nevada, USA incorporate well proven technologies in a unique combination. During the design of the plant, every effort was made to utilize the best available technologies from the perspective of capital, environment and operating costs. Crushing is a two stage process using gyratory and cone crusher. Ore is stockpiled and then reclaimed to two parallel dry grinding mills. The double rotator dry grinding mills include a drying chamber, coarse and fine compartments and utilize a gearless motor drive (GMD) or “wrap-around”. In-circuit product transfer is accomplished with air slides and bucket elevators. Finished product separation is performed by both static and dynamic classifiers with the final product captured in baghouses. Recycle of unfinished product utilizes cascade chutes. The final ground product reports to two 2000 ton roaster feed silos. The two-stage oxygen flu-solids roasters with their associated gas train are the subject of a separate paper. The cyanide leach circuit is a standard carbon in leach system with circular swept screens for interstage carbon retention. The loaded carbon is sent to the existing Goldstrike autoclave plant for stripping and regeneration. Tails, after cyanide destruction, are deposited in the existing tailings dam with tails from the autoclave facility. Throughout the circuit, Clean Plant Design criteria were used to assure environmental compliance, ambiental acceptability and ensure worker health and safety. The commissioning and operation of the double rotator grinding technology has been very successful at Barrick Goldstrike.

Jan 1, 2001

By L. M. Irwin

This Bureau of Mines investigation relates the physical properties of copper reverberatory furnace slags to changes in composition, The smelting of upper Michigan copper ore presents some problems that probably differ from those of other copper smelting areas. The study of these problems has, however, provided important data regarding slags in general and therefore will be of value to other operations as well. Conclusions reached from this study were: (1) Slag fluidity and refractive indices varied directly with the iron content and inversely with silica, lime, and alumina, and (2) there was no apparent correlation between slag fluidity and its copper content.

Jan 1, 1962

By E. Pardo-Igúzquiza, R. A. Olea

The bootstrap is a computer-intensive resampling method for estimating the uncertainty of complex statistical models. We expand on an application of the bootstrap for inferring semivariogram parameters and their uncertainty. The model fitted to the median of the bootstrap distribution of the experimental semivariogram is proposed as an estimator of the semivariogram. The proposed application is not restricted to normal data and the estimator is resistant to outliers. Improvements are more significant for data-sets with less than 100 observations, which are those for which semivariogram model inference is the most difficult. The application is illustrated by using it to characterize a synthetic random field for which the true semivariogram type and parameters are known.

Jan 1, 2015

By Braden Lusk, Paul Sainato, Josh Calnan, Hiago Vasconcelos, Luis Felipe Marinho

"Blasting and rock fragmentation is one the most important unit operations in mining. Since itsintroduction into the mine production cycle, mining has become more efficient in mineral production(Hartman, 2002). Widely used with the main objective of breaking rock mass in smaller fragments to be loaded and hauled at a minimum cost, blasting is optimized when stemming materials properly confine drillholes charged with explosives. Halim Cevizci (2013) performed a stemming application using Gypsum plaster, a kind of material that exhibits solid-like behavior when it is dry. Based on his theory, the present article reports an experiment using another type of material that shows similar behavior, non-Newtonian fluids. The primary goal of this study is to measure the confinement effectiveness provided by a non-Newtonian mixture as the stemming component. The study also analyzes the explosives’ energy propagation throughout the rock mass relating to the stemming materials applied. Currently, mining literature recommends the application of dry granular materials in stemming columns, because of its inertial and high frictional effects (Hagan, 1973). However, the test verified that the mixture added to the stemming column was able to reduce energy and gas losses to the atmosphere, because of the liquid’s property of filling voids in the material. The solid-like behavior of the non-Newtonian mixture was investigated for its capability to improve borehole confinement, since the mixture reacts like a solid when under shear stress. The results were compared to those from sand and air stemming applications, configured in different arrangements. It was concluded that the non-Newtonian mixture yielded high results due to its better confinement effectiveness, a reduction of air overpressure, and an increase of the strain propagation and ground vibration throughout the rock."

Jan 1, 2016

By J. Andrew Cornier, Mike Cooper

"Upon successful completion of the AG/SAG Mill project (Cooper et al., 2001) the Brunswick Mine concentrator was configured with single line processing through the AG/SAG mill, followed by two parallel ball mill and flotation circuits. The Stage Grinding project was undertaken to utilize a pre-flotation stage on the AG/SAG mill primary cyclone overflow and simplify the flowsheet by consolidating the two ball mill and flotation circuits, resulting in single line processing fi-om AG/SAG mill to final concentrate. Concurrently, the reclaim water supply capacity was increased to enable flotation cleaning at lower percent solids.Benefits from the Stage Grinding project include revenue enhancement from increased zinc grade and recovery combined with additional lead recovery. Further benefits included a reduction in the number of process pumps, reduction in loss associated with spillage to sumps and process simplification through efficient use of equipment layout.The Stage Grinding project was implemented in six phases over a period of seven months in 2000. Each phase was commissioned during scheduled concentrator shopdays with minimal additional downtime required. One year after project approval the Stage Grinding project was completed at a total cost of $1 1.8 million.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is one of the world’s largest leadzinc mines. Milling of ore began in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore fkom the No. 6 open pit located several kilometers away. In 1980 the pit was exhausted and the concentrator rationalized to accept a design feed rate of 10,500 tomes per day from the No. 12 mine. In excess of 100 million tomes have been milled to date, representing over three-quarters of the known reserve. The concentrator employs differential froth flotation to produce lead, zinc, copper and leauzinc bulk concentrates. The ore is massive sulphide, with approximately 20% valuable minerals, 60% pyrite and 20% silicates."

Jan 1, 2002

By L. Flett, S. Woods, C. Deredin

"Following a significant reduction in world Imperial Smelting Furnace (ISF) capacity from 2003 to 2008, a major optimization initiative was successfully carried out on the lead upgrading and bulk (zinclead) flotation circuits in the Brunswick Concentrator.This paper describes the process improvements that have taken place in order to reduce the quantity of bulk concentrate:•,Increase in lead upgrading rougher flotation circuit capacity•,Installation of a closed-circuit bulk regrind utilizing MillPebs and 150 mm Cavex hydrocyclones•,Installation of two additional cleaner flotation stages on the bulk circuit•,Optimization of the manipulated variables in the lead upgrading and bulk circuitsINTRODUCTIONThe Brunswick Mine (Xstrata Zinc Canada) is located near Bathurst, New Brunswick and is one of the world’s largest lead/zinc mines. Milling of ore commenced in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore from the No. 6 open pit mine. The planned closure of the mine will take place at the end of the first quarter in 2013. The ore is a complex massive sulphide, consisting of approximately 20% valuable minerals, 60% pyrite and 20% silicates.A simplified flowsheet for the concentrator is given in Figure 1. The overall flowsheet involves SAG milling, secondary ball milling, selective flotation, and dewatering by thickening, filtering and drying. The complexity of the flowsheet evolves from the requirements for fine grinding and the production of four concentrates: zinc (sphalerite), lead (galena), copper (chalcopyrite) and bulk (sphalerite plus galena).Primary hydrocyclone overflow feeds the copper-lead aerator-roughers for flotation at pH 9.0 with soda ash. Plant xanthate (80-20 sodium isopropyl and potassium amyl) and AP407 are used as collectors in the copper-lead circuit. The rougher concentrate is directed to the copper-lead regrind circuit and the tailings are fed to the secondary grinding circuit. The secondary hydrocyclone overflow from the secondary grinding circuit feeds the copper-lead rougher-scavenger banks. Rougher concentrates are reground to a P80 of 28 µm prior to three stages of copper-lead cleaning. The first stage of cleaning is done in an open circuit with the tail reporting to the cleaner scavenger. The cleaner scavenger concentrate reports to the regrind circuit and the cleaner scavenger tail combines with the rougher/scavenger tail to feed the zinc circuit. The second and third stages of cleaning are performed in closed circuit with the cleaner tail being recycled to the copper-lead regrind circuit. The average final concentrate grades 23% Pb, 3% Cu and 704 g/t Ag, and is fed to the copper separation circuit."

Jan 1, 2013