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Enhancement of Energy Efficiency in Fine Grinding of Copper Sulfide Minerals Using a Pilot-Scale Stirred Media Mill - IsaMill The mineral liberation size of run of mine ores has dramatically reduced over recent years. As a result, the demand for fine grinding which is the most energy-intensive form of grinding has markedly increased in the minerals industry. Furthermore, the fine grinding costs increase exponentially with decreasing product particle size. As a result of the increased energy requirement for fine grinding, it is desirable to optimise fine grinding processes such as stirred media milling (ie IsaMill) to enhance energy efficiency, throughput and the product fineness. In the present study, the influence of slurry rheology, grinding media type and grinding media-to-feed size ratio on energy efficiency in a pilot-scale IsaMill was investigated under certain industrially relevant pulp processing conditions. It was shown that a critical rheological state existed, below which the energy required to achieve an 80 per cent passing (ie P80) 20 ¦m product size was unaffected by shear rheology (ie apparent viscosity and shear yield stress) whilst above which the grinding energy required increased dramatically with increasing shear rheology. Colorado River sand (3.35 mm) showed higher energy efficiency than MT1 ceramic media (2.5 mm) for a target P80 of 20 ¦m in the solids concentration range of 38 to 55 per cent by weight, but the former experienced more than four times the wear rate of the later. The high wear rate of the Colorado River sand may be due to its much lower hardness. For feeds with an 80 per cent passing (ie F80) 70 to 110 ¦m, 2.0 or 2.5 mm MT1 media appeared to be more energy efficient than 3.5 mm MT1 media whilst a media-to-feed size ratio of 41 to 53 is applicable for ~50 ¦m (ie F80) feeds for efficient grinding.

Sep 13, 2010

By Giovanni A. Bonita

The new Embassy of the Peoples Republic of China in the United States (Chinese Embassy) is located in the Embassy Row portion of Northwest Washington DC. The 475,000 ft2 (44,125 m2) structure has five levels below ground and four above, making it the largest embassy in Washington DC. The structure approaches the property line on all sides, and is immediately adjacent to several foreign embassies and a secure U.S. Federal Building. A vertical soil nail wall was used as the primary support of excavation (SOE) system for the project. The soil nail wall was irregularly shaped, benched in areas, and reached total heights up to 98 feet (29.9 m). The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. Tight excavation requirements were defined for the project due to the location of the building relative to the property line, requiring fairly precise wall positions and shotcrete tolerances. Design challenges included soft soil conditions, inside wall corners, underground utilities, and seismic impacts from blasting. The paper will focus on the design, construction, and performance of the soil nail SOE system, as well as touch on the logistical and political factors that influenced the design. The paper also notes the Value Engineering and communication approaches that were generated during construction. These efforts resulted in a significant improvement in the quality control and quality assurance exhibited on site, expedited the schedule, and led to significant cost savings to the contractors, engineer, and owner.

Jan 1, 2006

By U. Weber

The effect of grinding media performance on milling and operational behaviour was demonstrated under different selected conditions of calcium carbonate slurry milling. A variety of grinding media materials and bead sizes, along with two different stirrer tip speeds, were used in the grinding process to generate a particle size reduction of the calcium carbonate (CaCO3). To determine the optimum milling parameters the collected test data were used to calculate and evaluate specific energy as well as stress intensity under different milling conditions. Keywords: Grinding, mill media, high energy mills, industrial minerals, precious metals.

Jan 1, 2010

By Amanda Elioff

Success of the Gold Line Eastside Extension rail tunnels in Los Angeles has prompted Metro?s planning for two new rail lines to include underground alternatives. The Westside Extension Transit Corridor alternatives include up to 17 miles of subway to be constructed in soft ground. The routes will require construction in Los Angeles? ?Potential Methane Zone,? not considered for subway construction until recently. Slurry face TBMs will likely be specified. The Regional Connector, through the downtown area, includes one underground alternative with 1.7 miles of tunnel as well as three underground stations in soft ground and rock. Challenges will include tunnel and station construction under narrow streets. This paper will describe the alternatives, planning, geologic conditions and tunneling concepts for both planning studies.

By Fan Shaogang

In this paper, the airbags' structure and technical characteristics and its applications in China are described. Based on the practice of the airbags in mining thin seams, the effects on ground control are discussed. This paper also analyzes the interaction mechanism between the airbag and surrounding rocks.

Jan 1, 1997

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

The importance of the Broken Hill mining field may be gauged from the fact that since the discovery of the ore-body in 1883, till the end of 1931, approximately 43,000,000 tons of ore have been raised.The lode covers a length of 31 miles, and in places is upwards of 300 ft. in width. The ore, as at present mined, consists of an intimately blended mixture of lead and zinc sulphides with silver and gangue minerals.Structurally the lode conveys the impression of a huge longitudinal arch (when viewed from the east or west), having its apex or crown near the centre of the field, in the leases of the Broken, Hill Proprietary Co. Ltd., where the lode outcropped at the surface.The minimum depth of the lode in the Proprietary mine was some 500 ft. from the surface, but huge undulations, having an average pitch of 45°, carry the extensions of the arch gradually deeper, to those places where active stoping operations are now in progress in the workings of the North mine at one extremity, and the South and Zinc Corporation mines at the other. The depth of the lode from the surface, as exposed at present, is approximately 1700 ft. at these extremities.The structure and physical character of the ore-body, and its containing walls, are so complex and varied that almost every type of mining problem is met with.

Jan 1, 1932

By Jim Dodd, Jim Paynter

"We would like to acknowledge the efforts of the following key people who helped to make this project a success.Ron Jung, instrumentation supervisor for the Golden Giant Mine, spent many hours reviewing process and instrument drawings, selecting instruments and providing hands on support during commissioning.Andy Keough, underground production supervisor for the Golden Giant Mine, was responsible for readying the underground distribution network for paste backfill.H.A. Simons Ltd. personnel who did an excellent job providing sound conceptual and detailed engineering.Fred Brackebusch, of Mine System Design who designed the paste backfill delivery systemPierre Lacombe, mill superintendent of the Louvicourt Mine, generously shared information and operating experience of their paste backfill plant.AbstractThroughout the 11 year history of the Golden Giant Mine, the primary backfilling method made use of consolidated rock fill. New backfill technologies have developed over recent years which now make it possible to use large quantities of fine mill tailings as backfill.In January of 1996, construction began on a new paste backfill plant at the Golden Giant Mine. Six months following, the plant was commissioned. This paper describes the design, commissioning and operational experience to date of the paste backfill plant."

Jan 1, 1997

By Professor of Civil and Environmental Engineering Northwestern University, Mike Wladron, Gordon Revey

A unique judicial opportunity allowed measurement of the response of three cracks in residential structure to blasting for underground aggregate mining. Instrumented cracks were located in the interior basement CMU mortar and upstairs dry wall as well as exterior brickwork. The dynamic environment was unusual. Even though the blasting occurred some 490 m (1600 ft) away, excitation frequencies were unusually high and there were no apparent surface waves. In addition there was no air overpressure wave to produce secondary crack response. As is typical, long term environmental effects produced greater crack response than did the blast induced ground motions.

Jan 1, 2007

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 Sara Jane Boles

In recent years the demand for products of greater refractoriness has placed an ever-increasing emphasis on ceramic materials, including the metallic oxides. Magnesia (MgO) is one of the most important of these oxides, exhibiting, as it does, high electrical resistivity, high slag resistance, and a melting point of 2,800° C. However, magnesia has a tendency to hydrate in the presence of water and to volatilize above 1,500° C. in certain kiln atmospheres and has a comparatively low resistance to thermal shock. Because of these disadvantages, the previously listed advantages inherent in this material have been largely overlooked, and research on magnesia has lagged behind that on oxides such as alumina and zirconia. This bibliography has been prepared in an effort to present to Government and industry a comprehensive picture of the prospects for greater utilization of magnesia as a refractory material in future research. To provide as selective and accurate a collection as possible, the references included cover magnesia in a pure state, not as an additive or in combination with other materials. However, several references discuss the effect of minor impurities (less than 5 percent of the total) on the properties of magnesia, as these papers are considered to be of special importance. A few references to articles on forming techniques are also included, as they are valuable additions to the overall treatment of the subject. The processes used in obtaining and refining the raw materials are adequately covered in earlier publications and are excluded. A number of references are omitted as being of questionable value in enhancing the cumulative study of pure magnesia as an ultra-high-temperature refractory material.

Jan 1, 1962

By W. G. Payne, A. C. Richardson, B. L. Gandrud

"INTRODUCTION The Connellsville mine of the Yolande Coal & Coke Co. is in the southwestern part of Jefferson County, Ala., about 30 miles southwest of Birmingham. The mine is on the Blue Creek bed, which is about 6 feet thick and dips at a angle of 18º. The bed is worked by the room-and-pillar method and is mined by both machine and hand methods. The Blue Creek bed at this point yields a high ash, low-volatile coal with excellent coking properties. Because of its exceptionally low volatile content and high coking strength, this coal is excellent for blending with Alabama coals of higher volatile content and weaker coking properties to form blends suitable for production of metallurgical coke.A sample of washed coal taken during this investigation gave the following analysis on an as received"" basis: Moisture, 8.3 per cent; volatile matter-, 20.2 per cent; ash, 8.0 per cent; fixed carbon, 63.5 per cent. The high ash content of this coal limits the quantity which can be utilized when low-ash coke is required. In the Birmingham district it is usually difficult to sell as coking coal a product that contains more than 8.0 per cent ash. To produce a. coal with this ash content at Connellsville presents a somewhat difficult washing problem. This paper gives the results of an investigation that was conducted by the Southern Experiment Station of the U. S. Bureau of Mines in cooperation with the University of Alabama and the Yolane Coal & Coke Co. for the purpose of determining the washing characteristics of the coal and the possibility of reducing its ash content on coal-washing tables.The practice at the Connellsville washery at the time of beginning this investigation was to crush the run-of-mine coal to pass a 1 1/2-inch round-hole screen and to treat the satire output on two primary, 3-compartment jigs. A. middling product was recovered from the primary jigs which was re-treated on a single-compartment rougher jig. This system yields a product of acceptable ash content, but the yield is low and the loss of good coal in the refuse is high."

Feb 1, 1933

By G. P. Holmes

"IntroductionThe copper-molybdenum property of Brenda Mines Ltd. is located 18 miles north west of Peachland in the Okanagan Valley of the Southern Central interior of British Columbia. The actual site is 50 miles north of the international boundary and 150 air miles east of Vancouver at an elevation of 5000 feet above sea level. The earliest written mention of the prospect is found in the Geological Survey of Canada, Memoir No. 243, issued in 1947 by Dr. H.M.A. Rice. In 1954 the area was staked by a prospector, Bob Bechtel, who interested Bern Brynelsen of Noranda Exploration in examining the claims. A joint Noranda - Kennecott program resulted but since the grades were so low the property was not taken up until in 1964 a re-examination by Chapman, Wood and Griswold produced recommendations leading to the construction of the Brenda Mine as it is today.The rounded, timber covered mountains of the area are composed of the tuffs, argillites and limestones of the Upper Triassic Nicola Group, which is intruded by a Jurassic quartz diorite, called the Brenda stock0 The actual orebody occurs in a strongly fractured zone within the Brenda stock, approximately 1500 feet from the contact with the Nicola group0 The ore minerals, .chalcopyrite and molybdenite, associated with pyrite and magnetite of lesser importance, occur as fillings within the fractures 0 The grade of the ore decreases outwards from a central higher grade core and in January 1971 total reserves were estimated at 165 million tons assaying 0,182% Copper and 0,049% Mo."

Jan 1, 1972

By K. Whysner

The recycling of metal resources in mining influenced water (MIW) requires a paradigm shift from within the mine water treatment industry. The potential to recover zinc for beneficial use in the micronutrient fertilizer industry was investigated through a survey of zinc micronutrient fertilizer representatives. An application of the findings to a case study of the Argo Tunnel influent MIW was then implemented. It was concluded that the potential to beneficially reuse MIW residuals in fertilizers exists; the current process sequences of treatment will need to be modified if metal recycling is to be prioritized.

Feb 27, 2013

By A. D. Thomas

Some years ago, the authors developed an analysis of non-Newtonian pipe flow based on enhanced turbulent microscale and associated sublayer thickening. This analysis, which can be used for various rheologic modelling equations, has in the past been applied to smooth-walled pipes. The present paper extends the analysis to rough walls, using the popular Bingham plastic equation as a representative rheological behaviour in order to prepare friction-factor plots for comparison with measured results. The conditions for laminar-turbulent transition for both smooth and rough walls are also considered, and comparisons are made with earlier correlations and with experimental data.

Jan 1, 2007

By V. I. Zhuchkov, L. A. Smirnov, E. I. Arzamastsev, A. A. Babenko

A brief analysis is given for state-of-the-art of manganese and chromium ferroalloy production in Russia and their consumption by metallurgy plants. The main causes of low output of manganese and chromium ferroalloys, and ways to resolve the issue of ferroalloy production development are considered.

Jan 1, 2004

By S. Prasad

The effectiveness of ultrasonic velocity measurements and attenuation of the propagating pulse was evaluated as a means of Non-Destructive characterization of cold worked and annealed copper. Commercial copper is subjected to mechanical working such as forging, rolling and thermal treatment to induce re-crystallization. The microstructural changes that occur in copper and a variation in its mechanical properties are subjected to analysis using the ultrasonic technique. The signal processing is carried out using the wavelet analysis technique. The features of wavelet analysis namely, localization in space and the presence of an infinite set of basis functions allows removing noise from the time series and components of a non-stationary signal to be analyzed. This is seen to improve the accuracy of the results obtained from the ultrasonic technique in the case of copper, which has distinct coarse grains that are difficult to inspect due to backscattering from the grain boundaries.

Jan 1, 2010

By A Bagchi, Nabiullah, Jagdieh

"A number of coal mines in India are affected by fire. Most of coking coal reserves in the country are located in Jharia coalfield where more than 18 sq. km is in the grip of fire. Generally such fires are confined in areas near to our crops. About 37 million tonnes of coking coal are lost in recent yearsdue to fire and another 48 million tonnes are blocked in fire areas. Preventive measures adopted to control fires were only partially successful and the cost of such measures was exorbitant I Temperature of blast holes in fire area varies between 60 and 300° C or even more. Even after thorough quenching of holes with water, it become difficult to bring down the temperature below SO"" C. For blasting hot holes primary need is to select safe and suitable commercial explosives and detonating fuse and to measure hot hole temperatures. VWiOUs types of commercially available explosives including Nitro Glycerine bare, slurries, site mixed slurries (SMS), emulsion5 ,detonating fuses and detonators were tested to determine their thermal behaviour at elevated temperatures under field simulated conditions in the Copyright © 2000 International Society of Explosives Engineers 1993g - Studies on Safe Blasting Technique in Fire Area of Coal Mines laboratory and in hot blast holes in field . More than 50 round of blast were conducted in fire areas. NG base compositions and detonators were found unsafe at temperature above SO0 C andtherefore, they are not permitted to be used in hot holes. Slurries and emulsion are stable upto 1200 c. For blasting at temperature exceeding SO0 C a heat resistant gel/ solution was developed by the authors and is being used in number of fire areas."

Jan 1, 1993

By L. du Plessis

The name FISH (Fully Integrated Sort House) refers to a class of technology deployed at Jwaneng Mine final diamond recovery. The FISH concept is based on three pillars, namely: ?Improved sorting efficiency FISH is based on laser technology, which is more efficient than hand sorting for certain product categories. Laser sorting is based on measuring in-elastically scattered light from molecules and this is referred to as Raman spectroscopy. The Raman scattered light occurs at wavelengths that are shifted from the incident light by the energies of molecular vibrations ?Availability of production information Roller gap diamond size distribution information is generated on line for upstream process optimization ?Improved product security A ?hands-off? philosophy reduces security risk during operation and maintenance of the plant. In addition, a number of lessons were learnt about the application of new technologies in the industry: ?The required human competency profile demanded by new technology should match the available competencies of the operational staff ?An integrated information management system should be fully functional for both production management and diamond control purposes ?Operational feedback must be correctly evaluated to identify design, maintenance, training and operational issues so as to accelerate the maturity of the new technology within the time span of the sustainable operations project ?Project execution and technology maturity risks have to be evaluated and married to ensure risk mitigation by means of suitable project resource and contracting model selection.

Jan 1, 2003

By D J. Black

The process of longwall coal extraction coal causes fractures in the overlying and underlying strata and these fractures become pathways for gas released from adjacent coal seams to flow into the mine workings and contaminate the ventilation air. If the rate of gas emission exceeds the diluting capacity of the ventilation air, the gas concentration will increase and exceed the statutory limit resulting in production delays.All potential gas sources within the planned mining area, including coal seams located above and below the working seam, should be identified and sufficient gas data collected and used to determine the specific gas emission from each gas source. Gas reservoir and emission modelling is recommended to determine specific gas emission and changes in gas emission from individual sources over the planned mining area. Accurate gas reservoir and emission modelling provides the information required to accurately design gas drainage programs to effectively manage gas emissions and minimise the risk of ‘gas-outs’.Given the increasing occurrence of incidents of gas concentration in ventilation air exceeding the 2.0 per cent statutory limit and changes to mine plans to avoid ‘difficult-to-drain’ areas, it is apparent that many operations are not effectively utilising gas reservoir and emission modelling to identify high gas emission areas and are not completing sufficient gas drainage in advance of planned mining.The process of gas reservoir and emission modelling to support gas drainage design to control tailgate gas concentration and fugitive emissions is presented and discussed.CITATION:Black, D J, 2017. Gas reservoir and emission modelling to evaluate gas drainage to control tailgate gas concentration and fugitive emissions, in Proceedings Australian Mine Vent Conference 2017, pp 65–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017