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By D Syme

In the middle of 2000, BHP Billiton implemented a Six Sigma Plus business improvement program known as Operating Excellence. It was developed based on a business bottom line initiative to deliver 35 - 40c/share and was one of the BHP Billiton strategies to deliver $2 earnings per share and a longer term $40 share price (BHP share price). Cannington is a silver, lead and zinc mine owned and operated by BHP Billiton. Through implementing Six Sigma Plus Cannington wanted to:have in-house capabilities to change and improve; tailor for the needs of each business unit and department; have æSharing of its KnowledgeÆ as a tool for improvement and have a competitive edge across Cannington û to be better than our competitors; learn from and leverage off the successes of improved safety and prior business improvement efforts; and ensure networking and sharing of information have common measurement systems across all assets. As with most business improvement programs û Six Sigma Plus was met with some degree of skepticism, especially given the amount of resources involved. After 18 months, much of this skepticism has been replaced with enthusiasm as peopleÆs understanding and acceptance of its fundamental concepts are being realised. The idea behind Six Sigma Plus is that it combines sound technical solutions with high acceptance by those who need to work with or implement the change. The future vision for Six Sigma Plus is that it become part of what we do at Cannington û just like safety and environment û so that Six Sigma tools and methodologies are used in our every day work.

Jan 1, 2002

By Jason M. Ryan, T Michael LeBlanc, John H. Heiiig

Drill trajectory deviation is a recurring problem in the Mining Industry retreat stoping operations. As a result of this deviation, it is quite concevable that 60 kg (165 mm 0) and 103 kg (203 mm 0) explosive charges are detonated beyond the hanging wall contact. Consequently, there follows a reduction in hanging wall stability and an increase in ore dilution.

Jan 1, 1995

CENTRAL mine ore consists mainly of galena and marmatite in a siliceous and rhodonitic gangue, the average assay values being approximately 11.5 oz. per ton Ag, 14.5% Pb, 14.5% Zn, 1.3% Ox Pb, 0.3% Ox Zn.Owing to the 1923 fire in the underground workings, much of the ore now being mined has been subjected to a certain amount of oxidation, as shown by the oxidised values above.This factor is of great importance from a flotation point of view, as a sulphide surface which has been subjected to the influence of oxidation is not as amenable to flotation concentration as a fresh sulphide surface. The importance of this factor is increased when a differential flotation is to be made, and, as in the case of Central mine ore, the sulphide, which is to be floated first, has been oxidised...

Jan 1, 1931

By J. B. Fletcher

The Miami mine first started operations in 1910. For convenience, the history of the orebody can be divided into the following categories (Fig. 1): 1) 1910 to 1925: 24.4 million tons of high grade ore, mined by top slicing, sublevel caving, etc. 2) 1926 to 1954: 102 million tons of low grade ore, mined by block caving.

Jan 1, 1961

By W. J. Spat

Political risk is an integral part of the mining business in northern Andean countries. Peru, Ecuador, Colombia and Venezuela all have a higher than average political risk compared with other South American countries. Successful operations require good political-risk information, a thorough political-risk-management plan and a strategy to deal with political-risk perception on the part of the investing public. Colombia is perceived as about the riskiest place in the world to do business. A selection of recent headlines reads: “Colombia on the brink” (Economist, 1998), “Colombia’s ship of state is sinking” (Insight on the News, 1998), or simply “Bad news” (US Catholic, 1998). The World’s Most Dangerous Places rates Colombia as “currently the most dangerous place in the Western Hemisphere, and perhaps the world” (Aral and Pelton,1998). And many prospective investors and analysts say to Greystar Resources: “Yes, we love your results, but Colombia?”

Jan 1, 2000

By A. H. Marquis

Since the start-up of its first Direct Reduction Module in April 1973, S1DBEC has produced over 2 million tons of prereduced iron. During this period, SIDBEC has acquired comprehensive experience in the operation of the direct reduction process and at the same time has learned to recognize the characteristics that the oxide should have to constitute an adequate feed for the process. A comparison is made as to the design and operation of the two direct reduction units now operating at Contrecoeur, Que. A description is given of a method of evaluation of a direct reduction unit, which takes into account the main process variable sand which permits comparison ofthe results on a daily basis. The paper defines the characteristics that the iron oxide and the prereduced iron pellets must have to meet the specific requirements of the direct reduction and the electric arc furnace processes. A simple model makes possible a rapid evaluation of the technical and economic effect related to the use of a given raw material. Finally, the paper outlines the advantages of prereduced iron in the steelmaking process and on the quality of the steel products.

Jan 1, 1979

By Shosei Ph. D Serata

The Stress Control Method of mine design provides enhanced engineering control over the behavior of underground structures in comparison to conventional mine design methods. The same Method can be applied to achieve design control of surface subsidence. The basic mechanism relating undergroued deformation and surface subsidence is disclosed by mine simulations, using the REM (Rheological Element Method) computer code, whose predictions have been validated by field measurements. The key components of the underlying mechanism of surface subsidence have been shown to be the stress envelopes formed in the process of underground excavation. It has also been demonstrated that significant control of surface subsidence can be achieved by designing the geometry and timing of underground excavation to regulate the formation of stress envelopes. A field example is given in this paper to illustrate this application of the Stress Control Method.

Jan 1, 1986

By Andre Zingano

The objective of this paper is to study the effect of annulus thickness on the quality of resin mixture for fully grouted resin bolt. Pullout and mixture tests were made in underground coal mines for the following arrangements: (a) borehole diameter 1.14 in. (29 mm), and roof bolt diameter 0.75 in. (19 mm) with steel wire around the roof bolt; (b) borehole diameter 1.14 in. (29 mm), and roof bolt diameter 0.75 in. (19 mm) with no wire around the roof bolt; and (c) borehole diameter 0.95 in. (24 mm) and a roof bolt diameter 0.75 in. (19 mm) with no wire around the roof bolt. The mixture test in steel pipe showed that the best resin mixture is for borehole with 0.95 in. (24 mm). The arrangement (b) produced big voids around the bolt. But for the 0.95 in. (24 mm) hole, arrangement c, the mixture was the best. It was corroborated with the pullout tests results where there is a difference in grout stiffness: the 0.95 in. (24 mm) borehole is about 10 times higher than a borehole with diameter 1.14 in. (29 mm). On the other hand, for the cohesive strength the difference is not significant. Numerical models were built to simulate the pullout tests, and also to simulate the roof support at an intersection. Convergence at two underground intersections, consisting of an immediate roof with laminated sandstone, was monitored to evaluate the performance of the roof supports, using the 1.14 and 0.95 in. (29 and 24 mm) diameter boreholes (i.e. arrangements ?a? and ?b?). The convergence readings showed that the 0.95 in. (24 mm) borehole diameter resulted in a smaller, although it was not significantly different.

Jan 1, 2008

By Ali Porbaha

In today's fast-track construction environment, owners are searching for non-conventional technologies to build their projects faster and safer while maintaining traffic flow during construction. To that end designers and contractors are providing solutions that incorporate many unique features to expedite construction processes. In addition to timely delivery of the finished highway products, there is an increasing interest in making the initial investment in applying innovative technologies and thereby minimizing costly maintenance of highway projects. Accordingly, the aim of this paper (along with the accompanying paper) is to examine innovative technologies, developed mostly in Europe, that accelerate construction of highway, runway and railway embankment foundations. For each technology, a basic concept, installation technique(s), and design considerations are discussed, along with the case history of a real-world project. The Geotextile Encased Columns (GEC), AuGeo, and Continuous Flight Auger (CFA) are presented in Part I. Deep Mixing (DM), Mass stabilization, Cut-Mix-Injection (FMI), and Combined soil Stabilization with Vertical columns (CSV) technologies are discussed in Part II.

Jan 1, 2002

By Paul Sarnoff

The economics of precious metals -- depending upon who is involved --could be the economics of hope, of fear, indeed of profit and perhaps survival. For those investors seeking capital gains in a puzzling economy, precious metals involve the economics of hope. Those who are convinced that currency soon won't be worth the paper it's printed on turn to precious metals because of the economics of fear. Gold and silver have been a storehouse of wealth since biblical times. The economics of fear during the past 500 years on the Continent has caused almost every European family to make sure a private stockpile or hoard of gold, silver or coins is at hand in case the paper currency of their country undergoes the kind of disaster that came to the German Mark after World War I. Understandably, for mining companies involved in the production of precious metals, the elements of operations and management are directly concerned with the economics of profit -- and perhaps survival. To the American miner the price of precious metals in the marketplace is a matter of daily concern. After decades of selling silver to the US Government at 64.64 cents an ounce, producing silver mines suddenly became faced with prices breaking $5, $10 and $20 per ounce, and approaching $50 an ounce during the period 1978-1981. What should the miner expect one year in the future? Five years?

Jan 1, 1981

By M Sherman

The challenge facing the engineering provider is to calculate throughput rates when faced with disparate specific energies calculated by different testing methodologies. Typically, an ownerÆs team would expect that the throughput calculations be checked using more than one method, therefore it is inevitable that there will be differences, based on which methodology is used. This engineering challenge is exacerbated by the continuing evolution of contemporary circuit configurations such as two stage pebble crushing with or without high pressure grinding rolls (HPGRs) as the second stage, or second stage pebble crusher product reporting to the ball milling circuit, etc.This paper is a companion to the paper first presented at SAG 2011, which showed that the Bond Indices are an excellent tool for estimating the specific energy requirements for semi-autogenous grinding (SAG) mills in single-stage SAG milling (SSS) circuits, SAG and ball mill circuits (SAB) or SAG and ball mill circuits with pebble crushers (SABC). This paper presents how the Bond Indices have been used to calculate ball mill specific energies, and therefore throughput rates, for SAG mill based circuits. Once the ball milling specific energy is known, tower mill and vertimill energy requirements can also be calculated. It is noteworthy that the method presented in this paper does not require the use of any unpublished correction factors: the proposed method uses the Bond parameters and equations published by Rowland in 1982.CITATION:Sherman, M, 2013. 21st century bond, in Proceedings Iron Ore 2013 , pp 309-312 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By K. Leutwyler

The key to realistic casing stress analysis in thermal recovery installations is accurate knowledge of the temperatures involved. Much information leading to prediction of heat losses from tubing string to wellbore has been published. This .same information permits calculation of casing temperature under certain conditions. This paper reviews the basis for most of the published work, the line source solution to the diflusivity equation and examines some of its application criteria in the light of unsteady-state conditions. An alternate finite differences method is presented for correlation, and experimental data pertaining to the heat transfer mechanism in the annulus is reported. In the light of the information presented in the paper, it appears that the assumption of a line source for the tubing-wellbore system is valid even for reasonably short periods of heat flow, .such as "steam soak" operations. The empirically modified equation presented earlier matches computer derived results of the finite differences approach lor periods as short as 50 hours. Previously predicted cas ing temperatures and the associated stress levels are thus verified based on these correlative computations and the reported experimental information. Fall out from the computer output resulting in some studies of the influence of insulating cement properties on casing temperature, and experimentally studied effects of nitrogen placed in the annulus at various pressures., are described. INTRODUCTION Generally speaking, predictions of average casing temperatures have been based on an idealized model involving a centralized tubing string at uniform constant temperature radiating energy towards the casing under steady-state conditions.'. ' Heat is transferred away from the casing to the formation by unsteady-state conduction across thermal barriers consisting of cement and the mud sheath. Heat balances written on the casing permit prediction of instantaneous casing temperatures. During early periods of injection, casing temperature varies appreciably as a function of time; however, for long injection times this variation decays as heat flow from the wellbore to the formation stabilizes, and it becomes virtually negligible as conditions surrounding the wellbore become quasi-steady-state (Fig. 1). Carslaw and Jaeger -escribe a solution to the diffusivity equation for a line source (Fig. 2). A constant supply of heat is introduced into the medium from the line placed into the origin of the x-y coordinate system and parallel to the z-axis. Heat spreads outward in the infinite cylindrical solid and the temperature increase on a line going through point (x, y) parallel to the z-axis at a distance r can be predicted by: The following criterion must be considered: the Carslaw and Jaeger equation is obtained on the basis of a large

Jan 1, 1967

Gas well tests were performed on 17 wells in the Roma area. The procedure used in the test programme incorporates an initial isochronal test followed by what is described as the "two flow drawdown" technique. The second flow of the two flow drawdown test was conducted for sufficient time to allow transient investigation of the surrounding reservoir. This combination of tests allows the evaluation of stabilized production capacity in addition to the determination ,of several important reservoir characteristics.It also provides a qualitative indication of reserves, by reflecting the presence or absence of reservoir boundaries within the drainage area affected during the test.

Jan 1, 1968

By S. S. Rowland

Good afternoon, ladies and gentlemen. It is a pleasure, for several reasons, to be here at this 13th International Conference on Ground Control in Mining. Of course it's always a pleasure to be able to see and reacquaint myself with many long-time friends; but it's also a pleasure, or 1 should say worthwhile, because I take something back with me, some knowledge about mining that lets me do my job better and more safely. if I can do that, I've accomplished my purpose in being at a conference such as this. This conference is a little different, though. I have to earn my stay. I have to earn it by telling you a story; a story about mining through a mile of rock to get from one coal seam to the same seam on the other side of an ancient river channel; a story about mine personnel taking over the job from a contractor; a story about having to mine through two faults after the hard part was supposed to be over, but, most importantly, it's a story about how it was accomplished successfully and safely by a group of ordinary coal miners possessed with determination, belief in themselves, and a "can do" attitude. If you can take any part of my story and use it to do your job better and more safely, then I will have accomplished my purpose in being here today. Kerr-McGee Coal Corporation's Galatia Mine is located in Southern Illinois near the town of Harrisburg in Saline County, about 350 miles south of Chicago and 120 miles southeast of St. Louis. Construction of the mine began in 1982, and the first coal was shipped in 1984 from the Harrisburg No. 5 Seam, 550' below the surface. Mining began in the Herrin No. 6 Seam, 100' above the No. 5 Seam, on April 1, 1985. Mining in both seams began by using the room-and-pillar method. In 1989, the No. 6 Seam was converted to longwall mining, as was the No. 5 Seam in 1992. Today, all mining is done by the longwall method except for the required development work, which is performed by continuous miners. A heavy-media preparation plant with a 4.2 million-ton annual clean-coal capacity processes the coal. By the end of 1994, with annual production now exceeding 4 million tons, we will have shipped over 30 million tons of steam and metallurgical coal throughout the United States and the world. Most of the coal has been used as the primary source of fuel to generate electricity for the city of St. Louis. The No. 5 Seam coal can be used as a semi-soft coking coal or as a high-Btu, relatively low-sulfur steam coal. Its use allows utilities to comply with Phase I of the Clean Air Act Amendments of 1990 without installing flue gas desulfurization units or blending with other coals. The Herrin No. 6 Seam is a high-Btu, medium-sulfur steam coal that requires blending to meet Phase I requirements. Because the No, 6 Seam coal does not meet the Clean Air Act Amendments' Phase I compliance standards, we were forced to cease mining operations in the No. 6 Seam, leaving 170,000,000 tons of minable coal in the ground. Last month the Galatia Mine became a single-seam operation mining the Harrisburg No. 5 Seam only. The Clean Air Act Amendments of 1990 and the resultant S02 emission limitations on electrical power generation plants effectively eliminate, beginning in 1995, the near-term potential for profitable mining of the Galatia Mine's high sulfur Herrin No. 6 Seam coal. Because of the Clean Air Act Amendments, it is virtually impossible to market high-sulfur coals like the No. 6 coal unless the mine location and mining conditions enable greatly depressed sales prices to cover costs. We, along with the majority of

Jan 1, 1994

By P. J. D. Lloyd

The widely employed IPCC models for the release of methane from underground coalmining operations are reviewed, and put in the context of the South African National Communication on greenhouse gas emissions. Then attempts to calibrate the model via measurements on South African coalmines are described. These attempts failed because it rapidly became clear that the IPCC model, involving methane adsorbed by the coal and released (a) by the depressurization of the strata caused by mining, (b) from the broken coal and (c) from coal remaining in roof, floor, pillars or goaf after mining, was not valid. Instead, measurements showed that the methane release was very variable, sporadically falling to zero. Carbon dioxide concentrations were monitored at the same time as methane, and followed methane concentrations. An alternative model was developed, in which methane was largely displaced from the coal and held in fissures, cleats and pores, which, when intersected by mining, released methane into the ventilation stream. In a key test of this hypothesis, methane concentrations around a continuous miner were monitored both during operation and after shutdown. Even during operation, methane became undetectable. It is hypothesized that heating of the South African coal-seams during the emplacement of the igneous dykes that cut so many of the seams caused displacement of the methane from the coal into the pores. This fissure-held methane, or free methane, is released rapidly once a pathway through the coal into the mine atmosphere is established. In contrast, methane adsorbed in the coal, and measured as the seam gas, desorbs relatively slowly. Measurements suggest that on average about 50%of the adsorbed methane is lost one day after mining. By that time, the coal will have left the mine, so that the remaining seam gas will be released to the atmosphere outside the mine. Attempts to measure methane emissions from surface coal-mining operations showed very little detectable methane. Coal from surface operations, which was milled and exposed to atmosphere, adsorbed gas from the air. It is concluded that methane release from surface operations is probably less than 3Gg/a. It is estimated that the total methane release from the coalmining industry amounts to about 72 Gg/a, as opposed to the National Communication estimates of 323 Gg/a in 1990 and 317 Gg/a in 1994. However, there are large errors associated with these estimates, and it is recommended that the methodology outlined in this report be extended to as many mines as possible to reduce the errors that are inherent in the physical processes underlying the release of methane from South African coalmines.

Jan 1, 2005

By R. M. Waterstrat

X-ray diffraction and metallographic examination of binary Mn-rich alloys with Ti revealed the presence of intermediate phases in this system. A binary R phase has been identified and also a phase having an a-Mn type structure. The X-ray pattern of the phase TiMn3 is presented and a tentative phase diagram for the Mn-rich portion of this binary system has been constndcted. MANGANESE-rich alloys with titanium have been subjected to thermal analysis at temperatures down to 1100°C by Hellawell and Hume-Rothery.1 Their results indicate the existence of an intermediate phase TiMn3 in this binary system. This phase appears to coexist with the Laves phase TiMn2, and with terminal solid solutions based on the allotropes of manganese, at least down to 1100°C. The above investigators did not attempt to determine the crystal structure of this phase, however. Since, by analogy to the binary systems Mn-V and Mn-Cr3 one might expect to find a phase in this region of the diagram, it seemed desirable to obtain X-ray diffraction patterns of alloys in the concentration range in question, in order to ascertain whether the sigma phase or related structures occur. EXPERIMENTAL PROCEDURES Alloys were prepared by arc-melting electrolytic manganese and iodide titanium in a water-cooled copper crucible under a helium atmosphere. Excess manganese was added to each melt in order to allow for losses incurred during melting. The alloys were then wrapped in molybdenum foil and sealed in evacuated quartz tubes for annealing at various temperatures, as shown in Table I, followed by quenching in cold water. Although the inside of the tubes showed evidence for some loss of manganese from the specimen during annealing, there was no evidence of any reaction between the specimen and either the molybdenum foil or the quartz tube at these temperatures. It was later found that the manganese loss was considerably reduced by annealing these alloys in sealed quartz tubes containing one atmosphere of purified argon. As an added precaution the surface of each specimen was ground off before crushing the alloys to -270 mesh powder, using a hardened steel mortar and pestle. X-ray powder patterns were obtained using either FeKa or CrKa radiation in an asymmetrical focusing camera, which gave excellent dispersion of the closely spaced lines. Pictures were also obtained using a Debye camera of 5-cm radius which provided data in the angular region not covered by the focusing camera. The alloy specimens were polished and examined metallographically, using an etchant consisting of 60 pct glycerine, 20 pct nitric acid, and 20 pct hydrofluoric acid. The 10-g buttons were in each case broken in half and found to be well-melted and free of any gross segregation. One half of certain alloy buttons was submitted to chemical analysis in the "as-cast" condition. No appreciable change in composition seemed to occur during annealing . RESULTS The X-ray pattern of alloy Ti1.17Mn0.83 was found to agree well with that of the ternary R phase which was first found in the Mo-Cr-Co system,' and re-

Jan 1, 1962

By James Weaver

During the past 16 years, the authors have successfully used high-capacity rock anchors installed inside open-ended pipe piles, driven to bedrock, to provide uplift and overturning resistance for various structures including piers, bridges, power plant components and commercial buildings. These systems were ultimately used on the projects due to a combination of high uplift forces or overturning moments on the structures and the relatively poor subsurface conditions present at the sites. Other, foundation systems such as rock-socketed drilled shafts and spin fin piles were considered but were found to be economically prohibitive or not technically feasible.

Jan 1, 2011

By D. Janicijevic

This paper describes the process of scraper winch pull force measurement and shows the results of the actual winch pull force in extreme stall situations as well as during the face and gulley cleaning. It was found that by slowing down the motor and causing it to slip, torque up to 3.5 times higher than the nominal can be developed, resulting in the same increase of winch pull force. On the other hand, measurements of the actual force needed for cleaning of the face and the gully have shown that the currently used winches are too powerful. The extra torque that can be developed by the already too powerful winch motor poses a significant danger and necessitates the implementation of measures that will eliminate this risk.

Jan 1, 2008

Ore sorting is a high capacity, low cost method of pre concentrating ores and in some cases of producing a marketable concentrate. In most cases it is applied to run of mine material, immediately after primary crushing and screening in sizes ranging from 10 mm to 150 mm. Recent developments in bulk sorting of friable uranium deposits have resulted in machines capable of handling fine materials with sensing and separation being achieved on a zone by zone basis. Modern ore sorting machines rely on the synchronous operation of four internal subsystems, feed presentation, sensing, data processing and separation. A variety of different sub systems is available which can be combined in various forms to produce sorters capable of handling a wide variety of mineral types. The benefits in using ore sorting cover a wide range of situations and are applicable to both established mines as well as new mining ventures. Reduced operating costs, increased productivity, capital savings, energy and resource conservation and environmental issues are all part of the reason why ore sorting is finding rapid acceptance in today's mining industry. The suitability of different ore types for pre-concentration using anyone of the variety of ore sorting systems can be quickly established using computer based techniques which require only small samples of the materials under investigation.

Jan 1, 1980

By D Craw, L Cox, R J. Norris

The Rise and Shine Shear Zone is a mineralised low-angle deformation zone traceable for at least 7 km through biotite zone schist of the Dunstan Range, central Otago. The zone is commonly believed to be similar to the actively mined Macraes deposit. The Rise and Shine Shear Zone occurs in the immediate footwall of the Thomsons Gorge Fault, a regional scale Cretaceous normal fault that juxtaposes chlorite zone schist against biotite zone schist. Most mineralised rocks are deformed and record a progression from early stages of semiductile deformation to more brittle cataclasis. Folds in mineralised rocks trend northwards. The mineralised schist is hydrothermally altered with variable silicification, sericitisation, chloritisation, replacement of titanite by rutile and carbonate alteration. Gold is associated with pyrite and arsenopyrite and occurs in both ductile and brittle microstructures. Sheared and mineralised schist is cut by north-striking fault zones which host mineralised quartz veins. Veins in the shear zone contain hydrothermal albite. Trace element analyses show enrichment in As, U, Th and rare earth elements. Many of the above features are similar to Macraes deposit, but there are important differences. In particular, the Macraes deposit is hosted in lower grade rocks and truncated beneath by a normal fault, Macraes has no U or Th enrichment, Macraes veins have no albite and folds at Macraes trend NW-W. Rise and Shine mineralised rocks have no Cr enrichment and no hydrothermal graphite.

Jan 1, 2005