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By William Gleason

"Komatsu has been on the cutting edge of autonomous mining for the past 30 years and the company remains at the forefront of the technology that is changing from concept to a full-fledged reality.In 1996, Komatsu America Corp. (KAC) purchased a controlling interest in Modular Mining Systems; a move that enabled both companies to expand their product lines. It was through this effort that Modular helped to deploy the first autonomous haulage system (AHS) — the Komatsu FrontRunner system. In January 2008, the first commercial implementation of the FrontRunner system occurred at Codelco’s copper mine in Chile. Since then, Komatsu has put more than 130 haul trucks into seven sites on three continents to haul copper, iron ore and oil sands and its equipment has moved 1.8 Gt (2 billion st) of material with zero lost time incidents attributed to Komatsu’s autonomous trucks. The 1.8 Gt (2 billion st) is the most of any commercial mining autonomous haulage system and there is more to come. In November, Komatsu announced that an additional 150 autonomous haul trucks will be deployed to the Canadian oil sands over the next seven years.Komatsu has continued to pioneer autonomous haulage development, creating a range of autonomous options that includes semiautonomous and teleremote options all the way up to a haulage vehicle that stole the show at the world’s largest mining equipment trade show.In 2016, Komatsu advanced the concept of driverless haul truck to a new level when it displayed its Innovative Autonomous Haulage Vehicle (IAHV) at MINExpo in Las Vegas, NV. The concept vehicle is the first mega class haul truck designed to be fully autonomous, without an operators’ cab included on the vehicle.Unlike other haul trucks, the vehicle was developed exclusively as an unmanned vehicle designed to maximize the advantages of unmanned operation. Among other advancements, it was designed to distribute equal load to the four wheels, both when the vehicle is loaded and unloaded, and adopt four-wheel drive, retarder and steering. Komatsu said it is aiming for high-performance shuttling of this vehicle in both forward and reverse travel directions, thereby eliminating the need for K-turns at loading and unloading sites."

Dec 1, 2018

By S. P. Vanka, B. G. Thomas, S. Sivaramakrishnan

"During the continuous casting of steel, transient 'flow events can be very important to the generation of quality problems, such as shear entrainment, surface level fluctuations and bubble entrainment. These phenomena can be better predicted using Large Eddy Simulation (LES) models than the K-E models, which have been extensively studied. In this work the turbulent transient flow in a water model of a continuous caster has been both simulated using LES models and measured using Particle Image Velocimetry (PIV). The results of PIV and LES have been compared to validate the LES model and also to enhance the understanding of the prominent transient features of the flow field. The flow near the top surface in PIV was found to contain periods of 5-1 Os when the velocities were three to four times their mean values, which is of importance to the shear entrainment of the liquid flux. In both simulation and PIV the upper roll structure is found to change chaotically from a single large recirculation structure to a set of distinct vortices. The inlet swirl in PIV is seen to persist more than halfway across the mold, causing a characteristic staircase velocity vector pattern when viewed in a plane parallel to the wide faces. The lower rolls in PIV are significantly asymmetric for very long periods of time (- I-hour) and go through a repeating sequence of features. One of these features involving a short circuit between the upward and downward flow in the lower roll is also seen in the simulation and is of significance to bubble entrapment.IntroductionThe turbulent flow through the nozzle and in the mold of the continuous caster has been studied extensively using computational Reynolds Averaged Navier Stokes (RANS) models of turbulent flow [1,2]. Defects, such as internal inclusion of liquid fl4x through surface shear, pencil pipe defects due to bubble entrapment, surface defects due to level fluctuations are caused by transient flow phenomena oc'curring in the mold. These phenomena can be better predicted using transient Large Eddy Simulation [3] or ""LES"" models."

Jan 1, 2000

By Y. Makola, M. Kilumba, S. Mwaba, P. Ilunga, F. Banze, B. Nel, P. Kyoni, N. Mautsa, R. Nkomba, G. Ilu

Kamoto Copper Company is a copper cobalt mining company established in Lualaba Province of Democratic Republic of Congo under a Joint Venture between Glencore PLC and Gecamines (the state-owned mining company). Operations consist of underground and open pit mines, a concentrator producing sulfide concentrate and oxide ores milled slurry, and a hydrometallurgy plant producing copper cathode and cobalt hydroxides from concentrate and ores. The production capacity is 300 k/a of copper cathode and 35 kt/a of cobalt hydroxide. Since Q4 2020, the Luilu hydrometallurgy plant has experienced operational instabilities due to increase in proportion of dolomite in the ore mined and fed to the plant. This was diagnosed by the significant increase in calcium grade in ore and acid consumption, continuous foaming, and overflow of tanks with subsequent adverse impact on equipment availability due to corrosion caused by acidic spills, structure integrity, and safety concerns around the acidic slurry spills. Production was adversely impact due above equipment availability and often throughput restriction to mitigate the foaming and overflows. A high gangue-acid-consuming ore management programme was developed with the aim of mitigating these impacts. The programme included: (i) use of defoamer agent in leach to stop foaming and overflow, (ii) design of a mechanical solution to leach foaming and overflow, and (iii) froth flotation for copper and cobalt minerals separation from dolomite. Only option (i) is presented in this paper. Through laboratory testwork, pilot-plant testing, plant trial, and full plant implementation, Kamoto Copper successfully implemented a defoamer agent (Kemfoam X9980) dosing at leach, resulting in significant reduction in foaming and overflow of leach reactors and countercurrent decantation thickeners. The optimum defoamer dose rate obtained was 20 mg/L. Since then, the Luilu recovered its operational stability, the corrosion of critical equipment ceased, and availability improved as the acidic leach slurry spills ceased. The constraint on throughput due to leach foaming was addressed and the frequency of sliming events in the thickeners was significantly reduced as the foaming on the supernatant surface ceased, with subsequent significant reduction in interfacial crud in solvent extraction.

Jan 1, 2023

By K Sommerville, J Parkinson

"Open pit mines today have more technology and data available. The challenge is to effectively use resources to analyse and identify mine productivity improvements. AMC Consultants Pty Ltd (AMC) has completed more than 100 benchmarking studies worldwide. In the process of gathering cost and productivity data, insights have been gained on how mines are using data to drive productivity. This paper aims to share good practice on using data, what benchmarks operations should be aiming for, where mines are currently sitting, high value areas to target, and how to best prioritise improvement to meet operational goals.A key purpose of data is to assist in managing and improving operations. Key information is used to drive meetings, decisions, budget estimates and reports. Safety, equipment productivity, available stocks, grade and spatial reconciliation are examples of where data is important for management systems. The key is to keep reporting simple whilst maintaining access to source data for troubleshooting and analysis.Some operations still have paper-based reporting systems. Some operations collect data directly off machines and instruments, use cameras and have off-site control centres. The level of technology is a fit-for-purpose choice.Comparisons of productivity assumptions commonly used in feasibility studies with good practice productivity numbers sourced from AMC’s benchmarking database will be shared in this paper. A typical activity mining cost breakdown will highlight where the high value areas for productivity improvement sit.In addition to examining the productivity of each mining step it is also important to examine the impact on the mine plan. Equipment numbers, strip ratio, grade and material hardness can impact the results of bottleneck analysis. A bottleneck example case study will highlight how productivity and other factors can be used to identify and prioritise improvement opportunities.Keep it simple. Use only the critical data for meetings, decision-making, reports and plans. Knowing and communicating the key performance indicators (KPIs) you are striving for aligns the operation and prioritises improvement plans.Citation:Parkinson, J and Sommerville, K, 2016. Getting the Most Out of Technology to Drive Mine Productivity Improvements, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 84–93 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By P Mitchell, S Pushpan, G Ferres, K Bobbermien, L Hudson

"Falling commodity prices and a rising supply surplus have ushered in a period of restraint in capital project investment across the global mining and metals sector. Competition for capital project funding has seen fewer projects progress through investment gates and a stronger focus on projects that deliver gains in capital productivity and strategic outcomes.Over the course of the 2015 financial year, EY conducted a study of 108 projects in the global mining and metals sector (EY analysis; Larsson and Ericsson, 2014; SNL Financial, 2015). The projects studied were at various life cycle stages and related to the development of copper, iron ore, gold, coal, nickel and other commodities. Each individual project investment exceeded US$1 B, and the studied group represented a cumulative investment value of US$367 B.The research found that the majority of projects were delayed and/or over budget when measured against the initial estimates made during the early stages of the project life cycle. Of the surveyed projects, 69 per cent were identified as facing cost overruns with an average overrun of 62 per cent above the initial estimate and 50 per cent reported schedule delays, even after remedial acceleration initiatives.The analysis found that budget and schedule overruns could be attributed to five key causes:project management factorsstakeholder conflictsresource constraintsregulatory, and policy-related challengesunfavourable external environment.Improving project delivery performance starts with successful planning, followed by rigorous management during delivery. From global experience on large and complex capital programs, EY has observed a consistent theme of underinvestment and a lack of focus in three often-overlooked but critical areas:implementing effective governance and reporting frameworks with lead indicators that reliably flag emerging risks while they can still be mitigatedallocating adequate cost and time contingency to account for risks across the life cycleenhancing the value of contingency by aligning contingency plans with scenario plans.This paper explores the surprising findings of the study, proposes a root cause model and examines key considerations in applying these critical enabling techniques.CITATION:Hudson, L, Mitchell, P, Ferres, G, Bobbermien, K and Pushpan, S, 2016. Are your megaproject schedules and costs under – or out of – control?, in Proceedings Project Evaluation 2016, pp 75–85 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By Dirce H. Jacomo, Jaciele G. Teixeira, Anibal Y. Abreu Castillo, EsperidianaA. B. Moura, Yalquiria A. Silva, Rene R. Oliveira, Michelle G. Gomes

"Composites consisting of poly(vinyl alcohol), starch and sugarcane bagasse ashes, using glycerol as plasticizer agent, were prepared by solution casting method. Composites prepared were subjected to electron-beam radiation treatments, at radiation dose of 50 and 80 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The composite samples obtained were evaluated for their water absorption, mechanical and morphological properties.1. IntroductionThe potential of biodegradable polymers and more specifically of biocomposites obtained from agro-resources have long been well established [1-3]. Starch, derivate from variety of botanical sources (cereals, legumes, and tubers) is widely available raw material and one of the most studied and promising agro-resources for the production of biodegradable polymers as matrices for biocomposite applications. However, starch itself is very brittle, hydrophilic and its mechanical properties are very poor for many applications [3 - 5]. The blending of starch with conventional polymers is a promising approach to improve its drawbacks. Recently, many efforts have been made to blend starch with biodegradable synthetic polymers [5, 6]. Polyvinyl alcohol (PYA) is a particularly well-suited synthetic polymer for the formulation of blends with natural polymers, as it is highly polar and can also be manipulated in water solutions, and depending upon its grade, in functional organic solvents as well [3, 7]. PY A has been reported to be an option to blend with starch. Most of the starch/PY A composites have been prepared by casting. However, it is well known that starch/PY A composites has poor in water resistance and mechanical properties after absorbing water [3,8]. Attempts to improve the mechanical properties and to decrease the water absorption property of the starch/PY A composites are made by adding the cross-linkers and plasticizers. Park et al. prepared starch/PY A/citric acid films by the casting method. They also studied the effect of (spell out) citric acid on the mechanical properties and water resistance of composites [9]. Zhai et al. prepared the starch/PY A hydrogels using electron-beam radiation [10]. Different kinds of lignocellulosic fibers have been investigated in blends for formulation of biocomposites."

Jan 1, 2013

By Keith S. Liddell

he selection of mill design parameters to suit the applica­tion requirements can result in quite different operating parame­ters for each generic type of application, even though the basic mechanical layout of the mills may remain similar. The selection of the type and size of grinding media is very important to efficient and cost-effective operation, and to ensuring that the milled product achieves the required properties. Accordingly, the grinding media selection is seen as an integral part of the mill design. Consideration of the requirement for classification is important in order to achieve the optimum mill and circuit performance. This can lead to the circuit feed not being classified for a steady feed with minimal slimes and a low size reduction ratio. Feed containing on-size particles would be deslimed by open circuit classification. Closed circuit classification is performed where the feed fluctuates. The rheological characteris­tics of the circuit feed slurry can have an influence on mill performance, and needs to be allowed for. A common misconception frequently encountered is the belief that "a mill is just a mill". This is not the case with stirred types of mills, since the operating parameters selected for the mill can have a large effect on the product characteristics. For example, horizontal shaft high speed stirred mills have a com­pletely different grinding action to vertical shaft low to medium speed stirred mills, which results in large differences between the surface area produced at a given product size (Liddell, 1986). Hence, it can be misleading to apply test results or design procedures obtained from one type of mill to other types for scale-up. The Metprotech stirred mill, as applied in the mining and minerals industries, is a low to medium speed vertical shaft mill. The basic design has been discussed previously (Liddell, 1989). Currently, the largest mills that have been manufactured have an installed power of 400 kW. The largest chamber volume at this power is 6000 litres, containing IO t of grinding media. It is intended that the installed power will increase up to lMW as applications requiring larger sizes arise.

Jan 1, 1995

By M. Albrecht

I have been following the discussions on coal degradation started by the article "Degradation process in coal slurry pipe-lines," by M.G. Ayat and B.C. Scott. I agree with Mr. Dasher's comments in January that the title of the article was perhaps misleading as the information appeared to pertain more to processing the coal than to transportation. Specifically, the authors' conclude that the cyclone had an important impact on the degradation. Dr. Ferri's comments on degradation in other physical processes was very correct, handling of coal in a turbulent manner has an impact on the size distribution of the coal. This is one reason that when I design a coal system (mine to rail car) I try to minimize the total number of transfer and processing steps consistent with achieving the desired product specifications. Another area, mentioned in passing in the article, the impact of natural causes and the mining step, is of particular interest to me. A mine in West Virginia had a variation of 50% in the -6.35 mm (-0.25 in.) raw coal depending upon the direction of mining. Since it was a single unit mine, this significantly impacted the final product. Two articles on mining's impact on size distribution are: • Stefanko, R., Chopra, 1K., and Ramani, R.V., 1974, "Mining influence on size consistency and washability characteristics of coal," SME Fall Meeting, September; and • Albrecht, M., and Olsen, D., 1980, "Mining methods impact on coal preparation plant design," 1st International Mine Planning and Development Symposium, September. Both articles presented information on variation of size distribution and cleaning plant performance on a coal depending on the mining method used. Both articles considered a single coal seam at one mining operation. Stefanko's article considered continuous and conventional mining of coal in Pennsylvania. Albrecht's article considered surface, underground continuous, and underground hydraulic mining of a coal in British Columbia. Both concluded that mining methods do impact coal characteristics. I agree with Mr. Ayat's comments in reply to Dr. Ferri's discussion, "... degradation is a multi-faceted phenomenon involving many natural and man-made factors." As efforts are being made to produce a higher quality (lower sulfur) coal, this topic becomes even more important

Jan 1, 1989

By N. Cabrera

IN a recent paper Kuczynski' studied the rate at which the crack between a metallic plane and a spherical particle of the same material is filled up gradually when heated at temperatures near the melting point. If x is the radius of contact between plane and sphere (fig. I), Kuczynski shows experimentally that x5 = At [1] where t is the time. Assuming that the mechanism of transport of matter is the volume diffusion of vacant lattice sites, he is also able to prove Eq 1 theoretically. The constant A contains as a factor the self-diffusion coefficient of the metal and he shows that the values for this coefficient deduced from his experiments yield the same activation energy as that calculated by other methods, which is a confirmation of this point of view. Kuczynski has also considered theoretically the law of growth of x which would be expected if surface diffusion were the important mechanism. He suggests that x should then obey a law of the form x7 = At, and claims to be able to decide the mechanism involved from the observed law of growth., The purpose of this note is to prove this incorrect. On the contrary, when the mechanism is surface diffusion Eq 1 is also obeyed, but with a different constant A. Following Kuczynski, we suppose the bottom of the crack (surface A A) to have an average radius of curvature p. As a result of this curvature the concentration of adsorbed atoms in this surface, n(p) per cm2, will be smaller, and the concentration of vacant lattice sites in the neighborhood, N(p) per cm3, will be larger than the corresponding concentrations, n(w) and N(w), for a flat surface. For all practical cases we can write Thomson's formula in the form n(co)— n(P) N(P)—N(cc) _ 2a-a" n(oo) JV(co) kTp [2] where u is the surface energy of the metal and a the interatomic distance. 1. Let us now consider the mechanism of surface diffusion. We suppose the concentration of ad-

Jan 1, 1951

The serious shortage of eastern gas coal and of coke for gas-making in Illinois and adjoining states during the winter of 1917-1918 was emphasized at the meeting of the Illinois Gas Association, March, 1918. The seriousness of the situation was of concern not merely to private interests but to the general public, which consumes gas for heating, lighting, and for important industrial uses. Some relief was thought possible if central district coals from Illinois, Indiana, and western Kentucky could be used generally as a substitute for eastern coal and coke in the manufacture of retort gas and water-gas. Already a little Illinois and Indiana coal was being used under special circumstances in Illinois retort plants and successful experiments with mixtures of Illinois coal and eastern coal had been conducted at the Decatur retort-gas plant by F. K. Ovitz of the U. S. Bureau of Mines and the Illinois Mining Investigations, with the advice and cooperation of a committee of the Illinois Gas Association. Consequently, it seemed desirable to continue experiments with central district coal in gas retorts, and with coal as a substitute for coke in water-gas generators, and to give publicity to the results and technical assistance to companies desiring to use central district coal. Other matters, of national importance were the prospective shortage of toluol and of ammonia for the manufacture of explosives, and the possibility of encouraging recovery of additional amounts from some of the plants in central states that were not contributing these substances. Results of work done by the Gas Section, Illinois Mining Investigations, under the advice of the Technical Committee, were pushed to early publication until the signing of the armistice lessened the importance of speed as a war measure. The first two publications listed below were distributed by the Regional Director of the U. S. Fuel Administration, through the Bureau of Gas. By-products and Public Utilities. The others were distributed by the Geological Survey. Bulletin 21. The Manufacture of Retort Coal-gas in the Central States Using Low-sulphur Coal, from Illinois, Indiana, and, Western Kentucky. Bulletin 22. Water-gas Manufacture with Central District Bituminous Coals as Generator Fuel

Jan 8, 1919

By M. E. Fine

IN the apparatus for measuring internal friction shown in fig. 1, a modification of that described by Kê,1,2 the parasitic energy loss or background is equivalent to a Q-1 of approximately 4x10-5. This low value of background was obtained by using a jeweler's collet of appropriate size for the upper support, eliminating lateral motion without immersing the bob in oil, and designing the bob to reduce air resistance. The pendulum is supported on the frame through a snug fitting, sliding rotary joint (fig. I-B). A slight twist of the top imparts essentially pure torsional motion to the pendulum. No evidence of energy loss in the sliding joint has been observed. In the bob (E) steel balls are used in the torsion arm, and the bottom is filled with lead giving a total weight of 94 g. A lighter bob may be used for small diameter specimens. Another bob was a solid disc with provision for adding discs to change the frequency. The oscillating image of the filament is recorded on a revolving drum camera (fig. 1-3) driven by a synchronous motor. This allows use of frequencies higher than can be measured visually on a glass scale. Samples varying in diameter from 0.020 to 0.075 in. have been measured, the frequencies have ranged from 1 to 12 cps, and the maximum strain varied from 0.5 to 10x10-5. With appropriate modification the sample may be placed in a thermostat. The apparatus may also be used to measure the shear modulus. In the examples of measurement given in table I the internal friction of Permendur and the 46.8 Ni-Fe alloy are due, for the most part, to magneto-mechanical hysteresis8 (elastic hysteresis accompanying stress-induced magnetostriction) which depends on strain amplitude and increases with annealing. The internal friction of most materials decreases with annealing. References IT. S. K6: Physics Review (1947) 71, 533. 2 T. S. Kê: Transactions AIME (1948) 176, 448; Metals Technology (June 1948) TP 23703. 3 R. Becker and W. Döring: Ferromagnetismus. 365 (1939). J. Springer.

Jan 1, 1951

By Nicola Baldo, Marco Pasetto

"The paper discusses the results of a laboratory study, aimed to evaluate the suitability of the bottom ash from Municipal Solid Waste Incineration (MSWI), obtained from different Italian plants, to be recycled in the lithic skeleton of bituminous mixtures, for base layers of road and airport pavements. The research involved a preliminary study of the physical and geotechnical properties of the bottom ash by itself; it was followed by a mechanical characterization of the bituminous concretes. The traditional Marshall methodology was used to identify the optimum bitumen content; the mixtures were also mechanically checked by means of the stiffness modulus test, repeated load axial test and fatigue test. Because the requisites for acceptance in the Italian Specifications and Standards have been satisfied and given the positive mechanical performances, it has been verified that the MSWI bottom ash can be used as substitution of the lithic materials in the road bases, also with very high contents (up to 81% on the weight of the aggregate). Introduction The incineration of Municipal Solid Wastes (MSWs) provides for by-products which can be mainly classified as bottom ash and fly ash. The first one, corresponding to the 25% on the weight of the wastes to be incinerated, so resulting the principal product of the process, is mainly composed by Silica (Si), Iron (Fe), Calcium (Ca), Aluminium (Al), Sodium (Na) and Potassium (K) oxides, so presenting a composition similar to that of different natural materials. Its metallic fraction can be recovered; the remaining part is usually stocked in dumping or, less frequently, recycled. Bottom ash can be re-utilised in the construction of new infrastructures, especially in bitumen bounded mixtures, because of the inert properties of the binder which covers the grains with a subtle film, that prevents the release of heavy metals. The paper describes a study aimed to design new bituminous mixes for flexible road and airport pavements, realised with the highest content of 4 types of bottom ashes, deriving from different MSWI plants of the Northern Italy. The ashes will be named as BA1, BA2, BA3, BA4 respectively (the origin cannot be specified)."

Jan 1, 2008

By Ming-Kao Yen

S. E. MADDIGAN*—I think Mr. Yen should be complimented on doing a very excellent and a very comprehensive piece of work. I was particularly pleased to note the use of X rays in a somewhat less tedious technique than pole figures. In the past I think many workers have been diverted away from the use of X rays in such investigations because of the large amount of work involved in pole figures if one is dealing with a great number of specimens. The same thing, I think, applies to the determination of orientations by counting of twins which is also a very tedious procedure; as a result several papers which have otherwise been of excellent quality have depended upon etching techniques for determination of orientation. The present paper indicates that the results reported in those previous papers were correct, but I think the use of etching techniques alone is a rather shaky basis for setting up theories in the literature. W. M. BALDWIN, JR.*—This discussion will be a short note of correction and apology. In my discussion of Brick, Martin and Angier's paper I incorrectly reported the orientation of phosphorus deoxidized copper annealed at temperatures. When I learned that Mr. Yen was preparing the present paper I asked that he correct this previous error, which he most graciously consented to do. However, through my ambiguity the correction noted on p. 59 of Mr. Yen's paper is still not the proper one. For this I take full responsibility. The orientation which I observed in phosphorus deoxidized copper at high temperatures is the (112) [111] which agrees with the pole figure given in Fig 8a, on p. 65 of Mr. Yen's paper. Our observations were made on the basis of twin counts rather than X ray determinations and therefore serve as an independent confirmation of Mr. Yen's data. M. K. YEN (author's reply)—The author wishes to thank Dr. Maddigan for his comments in regard to the application of glancing technique to textures. As a matter of fact, considerable work has been done recently in connection with

Jan 1, 1950

By P. Amelunxen, E. Herrera, L. Hill, J. Vanderbeek

It is well-known that the particle breakage mode that occurs in a semi-autogenous mill is significantly different from that which occurs in a ball mill, enough so to warrant very different lab scale breakage tests and scale-up models. This phenomenon, at the plant scale, leads to changing process constraints depending on the particular properties of the ore. For example, hard or coarse ores might bottleneck the SAG/AG mill throughput, while the ball mills might constrain throughput when milling soft or fine ores. Because the power draw of a ball mill is fairly constant compared to that of a SAG/AG mill, periods of SAG/AG mill bottlenecks lead to increased ball mill circuit specific energy consumption and a finer grinding circuit product size, which together constitute a loss of efficiency of the overall process. Because HPGR circuit throughput is less sensitive to changes in ore hardness, this situation is less common or severe in those circuits. Furthermore, the ball mills are somewhat decoupled from the upstream crushing circuits through the use of surge bins, which also helps to mitigate this effect. As a result, ore hardness variability constitutes a significant cost penalty that should be applied to SAG mill/ball mill/pebble crusher SABC circuits when evaluating the relative economics of different grinding circuit configurations. Nevertheless, the issue is by-and-large ignored, because most current HPGR trade-off studies are based on averaged ore hardness parameters. This paper provides an estimate of the magnitude of this penalty for a typical operation by using Monte Carlo simulation methods and plant data from Freeport-McMoRan’s autogenous, semi-autogenous, and HPGR-based comminution circuits. A case study from an in-house 96K t/d sulphide project is presented to illustrate the concept. It was found that by including variability effects, the trade-off NPV of the HPGR circuit over that of the SAG mill circuit increases to $84 million from negative $33 million, effectively reversing the original decision of selecting a SAG mill circuit for the fixed hardness case.

Jan 1, 2012

By Persifor Frazer

The rocks which cover the east flank of the South Mountain are chloritic schists typical in character. A specimen of this rock from near the Bechtel shaft, Hamilton Ban Township, Adams County, Pa., was selected and analyzed in my laboratory by Mr. C. Hanford Henderson, with the following results: Ignition,........2.740 CaO,..........7.040 SiO,,..........41.280 MgO,.......... 7.486 AI,O,,.........18.480 K,O,..........2.208 Fe,Os,.........9.440 Na,O,.........3.523 FeO,......... 8.200 100. As one penetrates the range by moving westvard, these schists are replaced either by epidotie quartz or by orthofelsite. In the former case, a belt of copper-bearing rock is traversed, but not in the latter case. Inasmuch as this junction of the chloritic schists on the southeast and orthofelsite on the northwest, separated by the epidotic quartz, is several times repeated, we find two or three copper belts arranged in general parallelism to the axis of the chain, because the copper horizon is generally at this junction. Thus, in going west from Fairfield, after entering the low spurs on the South Mountain, one is fairly within the chlorite measures. At the " Virginia Mills " a chlorite schist comes in with a dip of S. 1.5 E.-74 Half a mile up Middle Creek, large numbers of fragments of chlorite schist, decoruposed epidotic matter, and quartz are encountered. The former rock, where in place, dips E. 40" S.-57o. About 4000 feet west of the intersection of this road with the so-called Tape-Worm Railroad, near the house of one Singly, large masses of chloritie schist are found loose on the road. A hundred yards farther west, near a triangle in the road, the latter is less in quantity and much epidotic quartz appears, after which a very large display of orthofelsite succeeds on the left bank of Middle Creek. All these last-mentioned rocks, however, are in fragments. Crossing the stream again a few hundred yards farther On, the chlorite fragments at first preponderate, and then large numbers of both rocks

Jan 1, 1884

The following is an incomplete list of members and guests who called at Institute headquarters during the period Apr. 10, 1919, to May 10, 1919. Arthur K. Adams, Spencer, Mass. Ensign Floyd D. James, U. S. S. Fulton. W. T. Bates, New York City, N. Y. J. Harry Johns, Thorsden, Woking, A. D. Brokaw, Washington, D. C. England. E. H. Clausen, San Francisco, Calif. W. F. Jones, Rock Springs, Wyo. W. M. Corse, Mansfield, Ohio. E. L. Lasier, Washington, D. C. E. O. Daue, Philadelphia, Pa. John M. Lovejoy, New Rochelle, N. Y. G. D. Dub, Washington,, D. C. 2d Lieut. James F. Magee, Lancaster, S. B. Eaton, Dover, N. J. Pa., Sherman Eaton, Smethport, N. C. Ernest Marquardt, Casper, Wyo. J. A. Endweiss, La Jolla, Calif. Geo. B. Marshall, Abangarez, Costa Edgar W. Engle, North Chicago, Ill. Rica. 2d Lieut. Maxwell E. Erdofy, New York Benj. L. Miller, So. Bethlehem, Pa. City, N. Y. Major Desaix B. Myers, Camp Mills. Chas. A. Fellencer, Allentown, Pa. Edmund Newton, New York City, N. Y. Arthur Feust, Joplin, Mo. Seely B. Patterson, Jr., Allentown, Pa. Ensign Harold P. Ford, U. S. S. Radnor. Wm. R. Pearson, New York City, N. Y. A. D. R. Galloway, Accra, West Africa. Harold C. Price, Langeloth, Pa. R. C. Gosrow, Milwaukee, Wis. T. C. Roberts, East. Orange, N. J. C. A. Grabill, El Paso, Tex. P. H. Royster, Washington, D. C. Hobart A. Hanks, San Francisco, Calif. W. H. Staver, New York City, N. Y. John L. Henning, Lake Charles, La. N. L. Wimmler, Bangkok, Siam. 1st Lieut. J. Parke Hook, Philadelphia, Capt. Jay P. Wood, New York City, Pa. N. Y. An item in the May Bulletin made it appear that Frank W. DeWolf had just become connected with the State Geological Survey of Illinois. This was one of the inadvertences of war. Mr. De Wolf has been Director, or Chief, of the State Geological Survey for approximately ten years. Through the courtesy of the Governor of Illinois, lie was loaned to the Bureau of Mines for about seven months, after which period he resumed his former position.

Jan 6, 1919

By D. E. Healy

In 1989, an autogenous grinding task force was formed to study potential autogenous grinding circuits to replace the existing semi-autogenous grinding (SAG) at the National Steel Pellet Plant in Keewatin, MN. Pilot plant test work, performed by the Hanna Research Center (HRC), indicated that fully autogenous grinding with pebble extraction and crushing could be incorporated into the existing circuits. In 1990, one of the existing 10 grinding mills was converted for an in-plant test incorporating pebble crushing. Full-scale test work were conducted in 1990 and 1991. They verified the pilot plant projections with primary mill throughputs from the fully autogenous circuit using pebble crushing being greater than throughput of the existing SAG mill circuits. The plant produces 5 Mt/a (4.9 million ltpy) of iron ore pellets from 17.6 Mt (17.3 million It) of crude taconite. Crude ore is single-stage crushed by gyratory crushers. Primary grinding is performed by 10 semi-autogenous wet grinding mills. Secondary grinding is performed by five ball mills. Induration is with an Allis Chalmers grate-kiln pelletizing system. The primary grinding circuit consists of 108.2-m-diam x 5.5-m long (27 ft-diam x 18-ft) SAG mills. The mills are charged with 127 mm-diam (5 in.diam) steel grinding balls at from 3% to 5% by volume. Ball consumption rate is about 0.55 kg/t (1.25 lbs/lt) of crude ore feed to the mill. Each SAG mill is powered by two 2.6 MW (3500 hp) motors drawing 5450 kW (7300 hp) at 76% of critical speed. The mills are grate discharge with 16 mm (0.6 in.) slotted grate openings when new. The mill discharge is sized on a trommel screen having 4.5 mm (0.2 in.) openings. The plus 4.5 mm (+0.2 in.) oversize material is returned to the discharge end of the mill by a reverse screw auger located in the center of the trommel. The -4.5 mm (-0.2 in.) trommel screen undersize is pumped to magnetic cobbers.

Jan 1, 1992

By J. R. Eckel

It has long been known that mud properties affect drilling rate and that drilling with water is as much as six to .seven times faster than with mud. However, it is not known why drilling rates with mud are lower. Recent studies show what fluid properties govern microbit drilling rate and also provide a quantitative correlation of these fluid properties and hydraulics with microbit drilling rate. All the microbit tests reported in this paper were made with a low permeability (about 10 md) limestone. They were conducted at constant bit weight and rotary speed with varying fluid properties, flow rate Q and nozzle dinnteter d. The tests showed that (1) drilling rate in a given system with constant circulating rate and nozzle velocity is a function of the kinematic viscosity [viscosity /density, (cp)/ p (density)] of the drilling fluid measured at near bit nozzle shear rates; (2) the combined effect of fluid properties and hydraulics on microbit drilling rate is defined by a Reynolds number function (kQp/dp); (3) for the same kinematic viscosity, drilling rate is independent of solids content; and (4) for the same kinematic viscosity, drilling rate is independent of fluid loss. INTRODUCTION The fact that mudding up reduces rate of penetration is well known, but the reduction varies from well to well. The rate with mud may be 80 percent of the water rate or it may be as low as 15 percent. Since this reduction of up to seven-fold takes place under conditions of constant bit weight, rotary speed and mud circulating rate in a uniform formation, it can only be a result of the change in fluid properties. Previous work1-" both in field tests and in laboratory microbit tests) showed that drilling rate with mud is lower than with water (Figs. 1 and 2). Microbit tests also confirm, at least qualitatively, the field observation that drilling rate slows with increased pressure differential from borehole to formation (Fig. 3). The qualitative effect of drilling rate of bit weight, rotary speed and rate of mud circulation are also the same for the field and microbit rig. For these reasons, the industry generally accepts microbit results as being qualitatively meaningful in terms of field application.

The South Junction deposit of St Barbara Mines Limited was discovered in 1989 by the geologists of Ross Atkins Mining.The deposit occurs in the lower part of the Gabanintha Formation of the Lukes Creek Group in the Mt Magnet -Meekatharra greenstone belt. Country rock is predominantly talc-chlorite schist. Gold mineralisation is associated with north-south shear zones, quartz-carbonate-fuchsite alteration of the ultramafic rocks and in particular close to deeply weathered quartz-albite porphyry. For a detailed description of the geology of the South Junction Deposit see Fiala (1992).

Jan 1, 1993

By K Cochrane

Time and time again history shows us that mine closures are sustainability failures. Mine operators do not know how to turn the mine closure into an asset and communities around the mine do not know how to plan or what to implement to be sustainable when the mine needs to close. If we want to achieve sustainability when we close a mine, we generally need to consider what economic activity we will have to create leading up to the mine closure to ensure that the communities remaining in the area are not worse off after mining than before. There is not one silver bullet solution to mine closure, as all mines are affected by different environmental and socio-economic conditions. That is one of the reasons why mine closure is so difficult.Effective stakeholder engagement is the nucleus around which sustainability is built. Achieving sustainability as part of mine closure means not only a self-sufficient community, but also could lead to transformation of that asset.A key issue is that neighbouring communities become completely reliant on the mine. The mine has influenced the economic, environmental and social aspects of the community and with no alternative economic sources. The community and municipality will struggle with capacity to maintain infrastructure, services and jobs. This not only impacts the mine workers and their families but also other businesses and people in the town that make a living by servicing the needs of the workers and their families. Social problems associated with a mining operations and closures need to be considered. The misuse of alcohol, domestic violence, breakdown in law and order, economic and health issues all have a severe influence. Families often need to relocate from the mining town to find work. This further perpetuates the impact of the mine closure to the economic viability of the town. CITATION:Cochrane, K, 2018. Is your mine closure a sustainability failure? Transform your asset and create a self supporting neighbouring community. It’s as easy as ABCD!, in Proceedings Life-of-Mine 2018, pp 38–42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018