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E. W. Stutchbury (Internationa~ Oombustion Aust. Ltd.) : Mr. Callcott made particular mention in his paper of erosion in primary air fans which are placed after the mill discharge. He adds that subsequent reduction in plant performance and resulting increased maintenance costs occur. It is generally assumed that this statement is substantially correct as the fan handles the complete output from the mill, but with modern materials, reduction in performance and subsequent .maintenance are not now a problem. This consideration of handling the pulverised coal in the fan is more than offset by the advantage of operating the mill under suction which results in cleaner operating conditions, simpler feeder arrangements and elimination of complicated seals on the mill.and feeder unit. It should be specially noted that whereas mill exhausters in the past have used chequer plate blades (sometimes with the addition of hard facing by electrode deposit) it is modern practice to provide fan blades of up to 1 in·. thick Ni-hard suitablyheat treated, with the circumferential section of the fan also in Ni-hard. By the use of this material large power...

Jan 1, 1957

By P. Gaskell

The paper examines the development of rock movement between a longwall extraction horizon and the surface for a fully caved mining situation. Physical modelling has been used to examine the mechanics of ground movement and the propagation of fractures around the longwall working. The paper discusses dimensional analysis, model construction and measurement technique and data processing of the results into effective graphical forms for further study.

Jan 1, 1988

By L McCracken

Up until 1990 CoalCorp North Island's accident record was six times that considered acceptable in those NSW operations with good accident prevention programmes. This was an obvious avoidable burden on the company in both human and cost terms.   Late in 1989 an accident prevention programme was implemented with the objective of achieving a 50 per cent reduction in the lost time accident frequency rate within 12 months. The key to achieving this objective was recognised as being an attitude change in the total workforce from General Manager downward. Management commitment and action were seen to be critical to the success of the programme.   Through very basic and simple training programmes in accident investigation, analysis and reporting, communication, on-the-job coaching and in focusing on improving supervision skills, the original objective was achieved.   During 1991 the application of methods improvement and hazard recognition techniques are seen as the logical step to achieving a further 50 per cent reduction in the accident frequency rate.

Jan 1, 1991

The rapid advance in the adaptation of scientific knowledge to the treatment of ores, resulting in improved chemical and metallurgical processes, has enormously increased the possibility of working lodes profitably, which a few years ago were passed over as unpayable. By the discovery of chlorination, and later of "Cyanidation," by the highly improved methods of concentration, and by the rapid advance in our knowledge of smelting (for which we are greatly indebted to Americanmetallurgists), and by the gradual replacement of scientifing principles and enlightened management, for rule-of-thumb methods formerly in vogue, many large low grade bodies have been opened, and are now paying dividends, which were,twenty years ago, looked upon as hopelessly unpayable. It has been more especially in these large low grade ore bodies, that modern methods have been benefical; for small lodes must be rich to pay at all, as they cannot be worked on the same gigantic scale, but even in these a percentage of metal is saved which formerly was absolutely lost.To make these large deposits remunerative it is, however necessary to try and find the point of greatest economic advantage, to handle the ore in vast quantities, to erect huge plats to treat it, to substitute automatic appliances for hand labour as far as possible, and to combine several processes supplementary to one another, so that ore which is not amenable to one process, shall be saved, by another; and by doing...

Jan 1, 1901

By George L. Gates

[When clays are mixed with water to -.,tee mud fluids for use in trilling wells for nil and --ac b ;l-,e rotary method the liquid mixtures have certain physical characteristics that vary with the quantity and size of their inherent solid particles. All naturally occurring clays contain variable quantities of particles of different sizes ranging from relatively coarse (sands) through -,.tedium (silt) to fine materials of colloidal dimensions. Tie colloid content is extremely important 2.s a desirable _.'ale constituent of mud fl-z to fit well drilling. ';'it:-out colloids the souk?;,' in a mud fluid wouldr rapidly, end ti-c-and. wall-building qualitites of the' fl,-,id would l ..o r re 1 impaired. Mud .fluid.^ with insufficient quantities of colloids also are lacking in "lubricating" g listen, and it is, to ° min casing in, -)re holes drilled with such fluids.]

Jan 1, 1941

By D Hill

In the Ngakuru area zeolite deposits occur in late Quaternary lacustrine vitric tuffs of the Ngakuru Formation and two of the deposits are being mined. The Ngakuru Formation overlies the Ohakuri Ignimbrite dated at c. 240 ka, and is overlain by younger alluvial sands and gravels. Individual zeolite deposits contain 50 - 80 per cent zeolite over a thickness of up to 45 m in thinly stratified vitric tuffs and are localised along NE-trending normal faults. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, Kfeldspar and smectite are also present. The zeolites and other minerals are very fine grained (<10 8m), with open meshes of crystals that result in high porosities (52 - 70 per cent) in mordenite-rich tuffs. Zeolitic tuff samples typically have cation exchange capacities of 80 to 110 meq/100 g and internal surface areas of 25 - 58 m2/g, which combine to give high liquid and odour absorption capacities. The first zeolite deposit (Mangatete) was found in 1992, and this and the Twist Road deposit are worked by quarry benching into the side of hills. The zeolitic tuffs are dried and crushed to produce a variety of products including adsorbents for soaking up oil/chemical spills and animal wastes, animal feed supplements, water treatment, and sports turf and slow release fertiliser. The Ngakuru zeolite deposits formed at shallow depth (<100 m) along fault zones from reaction of glass-rich tuff beds with groundwater-diluted geothermal water during the late Quaternary, and are as young as 8500 yr BP from 14C dating of plant material in sinter associated with the Mangatete deposit.

Jan 1, 2005

By J. P. Sancho, L. F. Verdeja, J. I. Verdeja

"This paper analyzes the present state of the different processes competing to keep their market shares within the future iron and steel business sector.The continuous transformations in the steel making process are also studied here. These transformations have happened especially during the two last decades obviously favouring steel price, properties, quality and environmental compatibility in the new millennium. IntroductionIn the early 1980s, world steel production reached a historic figure; specifically in 1982, the amount was 645 Mt (Verdeja et al., 1993). This might have been one of the reasons why the United States, Japan and the European Community drew up a declaration of principles after which the leading industries and sectors in the following century’s development would be: advanced materials, also known by the very diffuse term of new materials; information technologies; and biotechnology (Eager, 1998).On the threshold of the 21st century, it can be inferred that information technologies (computers and telecommunications) have progressed spectacularly. Nevertheless, there have been downsides too; technology develops so quickly that after a few months the products are obsolete. Environmental problems may also appear in a few years due to storing so many useless devices. At the same time, the achievements of biotechnology did not meet the optimistic forecasts made in the early 1980s.On the other hand, it is also curious that some solutions for the environmental problems generated by star technologies of the new millennium, such as computers and biotechnology, are closely linked to the iron and steel industry. For example, blast furnaces in Germany and Japan are prepared for burning residua by introducing polymer materials from computers and other electronic prepared devices through their tuyeres, while cement tube furnaces can destroy any organic residua from different origins."

Jan 1, 2002

By C A. Locke

Geophysical signatures of the Taranaki and Tongariro volcanoes reflect similarities in their age, composition and hydrothermal histories, but also reflect differences in host rock settings and edifice evolution. The Taranaki volcanoes have strong positive gravity anomalies showing that their edifices largely consist of dense andesite which reflects substantial lava production or dyke injection during construction and that large sub-edifice dyke/stock complexes occur. In contrast, the Tongariro volcanoes have strong negative gravity anomalies indicating low density edifices of volcaniclastic material; no sub-edifice intrusions can be identified, probably because of the lack of density contrast with host basement rocks. Strong positive magnetic anomalies over the younger cones can mainly be attributed to near-surface andesite lavas or dykes whereas subdued magnetic effects are associated with hydrothermally altered zones within both edifices and sub-edifice intrusions.  

Jan 1, 1995

By J. L. Holman

The Bureau of Mines is conducting research to improve technology for the recovery of strategic and critical metals, such as cobalt, nickel, and chromium, that are lost in bulk and particulate superalloy-type scrap because it has not been possible to process mixed contaminated scrap efficiently. The research approach involves melting and casting mixed superalloy scrap into soluble anodes for electrodeposition of Ni-Co alloys by controlled-potential electrolysis. The initial experimental results described in this report are from electrolytic tests us-ing alloy anodes cast from elemental nickel, cobalt, and chromium, the main constituent metals of superalloys. Baseline data and operating parameters are necessary for Ni-Co and Ni-Co-Cr alloys before detailed experiments can be conducted on the more complex superalloy scrap. This basic research assessed the effects of cathode potential, S04:CI electrolyte ratio, electrolyte pH, stirring rate, deposition time, cathode current density, and chromium concentration on cathode current efficiency, alloy deposit composition, and deposition potential at a cell temperature of 55° C.

Jan 1, 1985

By Wang Xuguang, Zhang Xiaozhi, Li Guozhong, Xiong Daiyu

The emulsion explosive is a new kind of water-based industrial explosives that was developed at the end of 1960s. In the 1970s, BGRIMM invented EL-series emulsion explosive that created a new era of water-based industrial explosives technology and products in China. From single type to varieties, the perfect BGRIMM emulsion explosives technology has been formed, which consists of 9 series, over 30 types explosives and related production equipments and processes such as cap-sensitive rock emulsion explosive, opencast emulsion explosive, coal permitted emulsion explosives, low-temperature-resistant emulsion explosive, high-temperature-resistant emulsion explosive, high power emulsion explosive, bulk emulsion explosive for loading truck and powder emulsion explosive. From the early 1990s, BGRIMM successfully developed opencast emulsion explosives and the computer controlled continuous production line of small-diameter cap-sensitive emulsion explosive which raised emulsion explosive production technology of our country to a new lever. With the successful development of powder emulsion explosive and related computer controlled continuous production line, on-site mixed emulsion explosive and loading truck as well, the category of industrial explosives is getting more complete and reasonable. This paper pres ents the history, achievement and development of BGRIMM emulsion explosive technology, also forecasts the future of linked technology.

Jan 1, 2003

THE old mill erected by the .Irvinebank Company consisted of 10 heads of stamps (850 lb.), rock-breaker, Hartz jig, two Krupp tables, two Luhrig vanners, three sand-pumps, one mixer; six flotation vessels, and the necessary settlers. Power was supplied by a small colonial-type boiler, and 10-in. x 15-in Tangye engines. The ore was darted from the mines to the mill and hand-fed, into the rock-breaker, and the broken product elevated into the batter bins and fed into the stamps, the pulp from the stamps passing to a classifier, the spigot to jig, tables, and vanners, the overflow from the classifier passing to settlers. After the removal of bismuth-wolfram concentrates, the pulp was pumped to the molybdenite flotation plant and the olybdenite recovered by flotation.A commencement was made with the erection of the first unit (20 heads) of the new mill in August, 1917, and milling and concentrating commenced in February, 1919.

Jan 1, 1920

By Simon Strong, Tim Brown, Luis Ignacio Sanz Vivanco

"One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the pre-stressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels. An essential part of the tunnel ventilation system, the smoke duct, extends the full length of the 4.6km long twin, two lane tunnels. The vast majority of the tunnels (approx. 4.3km) were constructed using two 12.4m diameter double shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit out challenges. A key component of the civil fit out of the tunnels was constructing the smoke duct in the TBM tunnels which was designed as a precast solution. The slabs which each measure 8.62m long by 2.0m wide by 200mm thick and weigh close to 9 tonne need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100mm. This paper details the events of how the Transcity JV tunnel fit out team, comprising some of Europe and Australia’s leading tunnel construction specialists, drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system to solve this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began."

Jan 1, 2016

Nautilus Minerals and Neptune Minerals are betting that the next great metals rush will take place more than 1,500 m (5,000 ft) below the sea. Nautilus is the first company to commercially explore the ocean floor for gold and copper seafloor massive sulfide (SMS) deposits. Its main focus is the Solwara 1 Project, a polymetallic copper, gold, zinc, silver deposit that is under 1,600 m (5,200 ft) of water off the coast of Papua New Guinea in the western Pacific Oceans? Rim of Fire. Nautilus Minerals, in a joint venture with Placer Dome (now Barrick Gold), began its exploration of what would become the Solwara 1 area in 2005 with side scan sonar and dredge sampling. The dredge and grab sampling confirmed the grade tenor of earlier sampling by scientific research programs. The 45 dredge samples aver-aged 10.8 percent copper, 3.7 percent zinc, 224 g/t (6.5 oz/st) silver and 13.7 g/t (0.4 oz/st) gold. Nautilus has since staked out more than 300,000 km2 (115,800 sq miles) of tenement licenses and exploration applications in the waters off Papua New Guinea, Fiji, New Zealand, Tonga and the Solomon Islands. That is an area about the same size of the United Kingdom. Interest in Nautilus and its projects has grown tremendously since its inception. The company is now listed on the Toronto Stock Exchange. It has raised more than $300 million and spent more than $23 million on exploration. The company has gained the backing of mining majors such as Teck Cominco, Epion, Anglo American and Barrick Gold. It is positioned to become an emerging producer in 2010. Teck Cominco recently agreed to exercise share purchase warrants to acquire three million additional common shares of Nautilus at a price of US$15 million. This will take Teck Cominco?s shareholding to approximately 7.2 percent of the issued shares. Teck Cominco will conduct and manage a ship-based exploration program that will run in addition to the exploration that was already planned for 2008.

Jan 1, 2008

By Robert B. Bittner

Large diameter piles (2 to 3 m diameter, both driven and drilled) are being used more frequently by designers of bridge foundations. The use of these large piles allows the pile cap to be positioned off the bottom but usually still below water. Conventional cofferdams as shown in Figure 1 below are not suited to this type of pile cap. However, float-in cofferdams offer a viable alternative. This paper describes the float-in cofferdam system, its initial development for use on the Bath-Woolwich Bridge in Maine and its most recent application on the new Carquinez Bridge in California.

Jan 1, 2013

By Joël P. T. Kapusta

Back in 1995, Air Liquide and Union Minière presented a joint paper at the Copper 95 – Cobre 95 Conference in Santiago, Chile, describing the first full scale plant trials of shrouded sonic injection in a Hoboken converter at the Hoboken smelter in Belgium. Almost a quarter of a century later, the technology known as ALSI, or Air Liquide Shrouded Injection, has been tested or commercially implemented in several copper and nickel smelters. Despite these successes, the copper industry did not adopt it widely in the same manner the steel industry adopted the Savard-Lee tuyere in the 1970s and beyond, not even in the way the lead industry adopted it with the Queneau-Schuhmann-Lurgi, or QSL, process. The development and implementation of bottom-blowing smelting and converting technologies in China in the last ten years, however, changed the industry’s perception that high- and ultra-high oxygen injection in copper smelting and converting was indeed possible under specific process conditions. In this paper, I retrace the key learnings of my journey with sonic injection over the twenty five years from my humble beginnings in my early years with Air Liquide, through plant trials and technology implementation in the late 1990s and into the first decade of the new millennium, and ultimately, to the most conclusive proof that the sonic injection design methodology I established is valid, and the calculation tools I developed are accurate. I conclude by sharing my thoughts about whether the deployment of the Savard and Lee legacy within the nonferrous industry was just a pipe dream or whether it will become a reality. INTRODUCTION In the context of lower quality ores and changing economic markets, copper smelters need to continuously innovate and improve to remain competitive and respect their corporate social responsibility engagements. One avenue towards this business, social, and environmental goal is to increase process intensity while lowering fossil fuel consumption to lower greenhouse gas emissions and reducing process off-gas volumes to better capture As and SO2–laden emissions. I believe high oxygen sonic injection for submerged tuyere copper bath smelting and converting is one technology that can help smelters achieve that goal of higher business, social, and environmental performance. Twenty five years ago, when I discovered that the Savard-Lee tuyere had revolutionized the steel industry (Savard & Lee, 1966; Knuppel, Brotzmann, Fassbieder, Savard, & Lee, 1972), I had a dream — or was it a vision? — that within the first decade of the new millennium, modern copper smelters operating submerged tuyere bath smelting and converting vessels will have implemented high oxygen sonic injection and will be reaping the financial and environmental benefits that the steel industry enjoyed in the 1970s. As we approach the end of the second decade of the new millennium, I have to admit that my dream has been all but shattered as the majority of copper bath smelting and converting vessels today continue to operate under bubbling regime conditions. This mode of operation is archaic, still requires tuyere punching and blows at inherently low enrichment levels, particularly in converting, producing large volumes of process off-gases. Under such operating conditions, regulations and emission quotas for As, SO2, and particulate matter oblige smelters to use not just primary or secondary hoods, but sometimes even tertiary hoods. I vividly recall being told, fifteen or twenty years ago when visiting smelters to promote the application of the Savard-Lee tuyere in nonferrous processes, that implementing sonic injection was not economically viable due to the high cost of compressing air and oxygen. Some of the smelters I visited back then have since mandated their engineering partners to design and build secondary or even tertiary hoods. I cannot fathom how secondary and particularly tertiary hoods, with all of their auxiliary equipment and added ducting, could be more economically viable than purchasing and installing a few compressors, expanding the pipeline network for compressed air and oxygen, and installing a new control valve train to feed sonic tuyeres. Besides, adding hoods does not address the problem of As and SO2-laden fugitive emissions at its source but merely provides a costly mitigation for it by capturing larger volumes of process off-gases rather than reducing these large volumes in the first place. Moreover, hooding does not reduce energy consumption nor does it increase process intensity, two aspects that I believe are critical for smelters to remain competitive and sustainable in a deeply changing market environment.

Jan 1, 2019

The work to be described is part of a comprehensive research on the influence of impurities on the properties of lead. The author had previously compared an electrolytic lead containing less than 0.002% total impurities with a commercial lead containing 0.008% impurities (excluding oxygen) and had shown that the former recrystallised more readily than the latter under the same conditions of cold work and annealing. This difference in properties was attributed to the difference in purity. Electrolytic lead containing only 0.0005% total impurities has been prepared and cast in vacuo. Some interesting effects have been obtained by working and annealing this lead, and by adding silver to it. The preparation of this lead, and the effects obtained thereon, are described in this paper. Thepaper is divided into the following sections:(I) Preparation of electrolytic lead.(II) Vacuum Casting.(III) Effect of Cold, Work and Annealing on two Electrolytic Leads, having 0.002% and 0.0005% Total Impurities respectively.1 Research Fellow, Dept. of Metallurgy, University of Melbourne.2 Proc. Aust. lnst. Min. Met., 1932, 87, 145.

Jan 1, 1934

I have chosen this subject in view of the fact that, while there are many and ample opportuuities of getting reliable assays made, there are but few who are in a position to obtain reliable data on the sampling of minerals and metals my long experience at Port Pirie, where, for five years, I had charge of the Refining and Sampling Mill, showed me how important it was that a correct sample should be taken.Weighing; This, to the ordinary layman, seems so simple that no expert knowledge is needed, but in actual practice there are hundreds of pounds to be lost by the lack of knowledge in this department.(1.) There is the matter of weighing in large or small quantities.(2.) The class of weighing machine used.(3.) The accuracy of weights used.We all know that, say, 1000 tons of ore cannot be weighed in one parcel; but the fewer the weighings the less loss to the seller (and usually wishes it weighed in small lots carefully) for it is a well known fact that the most sensitive scales take a certain weight to show distinctly the indication of the balance, or, in other words, what is known as "the pull of the scales." As for instance, 1000 tons weighed in lots of 1 c. each, taking the pull of the scale as being equal to 1 lb., would give a result of 9 tons loss to tbe seller, and as most of the ore sent to Customs works is worth 5. -£20 per ton-this would mean £180 loss to the careful man.

Jan 1, 1901

By D. Shin

The gold leaching using cyanide from ore or waste has been almost universally in use [1]. Recently, biological gold bioleaching using cyanide producing bacteria, e.g. Chromobacterium violaceum, Pseudomonas fluorescens, or P. aeruginosa, has been investigated as environmental friendly and cost effective method. Among them, C. violaceum has been reported as effective cyanide producing bacterium on gold leaching [2, 3]. C. violaceum produces cyanide using glycine as a direct precursor and subsequently detoxify the cyanide by ß-cyanoalanine synthase [4]. However, until today only 0.026 ? 16.9 mg/L of cyanide production in YP medium has been reported in the literatures by C. violaceum [4-6]. Comparing with adding cyanide chemical, biogenic cyanide concentration is lower than the cyanide concentration added in traditional cyanidation. Since cyanide also forms complexes with a number of other elements such as iron, nickel, zinc, silver, copper, and platinum, it is very important for gold recovery to investigate the enhancement of biological cyanide production and set optimal experimental condition. Most of early studies on gold bioleaching by C. violaceum have been performed to investigate gold leaching mechanism using gold powder, and recently various resources such as ores, electronic scrap, and printed circuit boards of waste electronics [7]. Few studies have dealt with gold bioleaching from low-grade ore. In this research the feasibility of gold bioleaching by C. violaceum from low-grade ores containing gold was evaluated and fundamental study was performed for further scale-up study. The aim of this study was to improve the potential of gold bioleaching by C. violaceum from gold-containing ore; in particular, enhancement of biological cyanide production.

Jan 1, 2012

The geologist is often called upon to give judgment on the possibilities of reviving a former mining field presumably worked out as far as the evidence then available indicated. From time to time, scarcity and consequent high prices of metals has led to there-examination of many old fields. The possibility of resuming investigation on them where the practical miner ceased work, even where he had the aid of the trained geologist, has long since disappeared.Means of access to mines have been removed and water fills the workings. Hence an indirect mode of attack becomes essential.This method depends mainly on past history, and may be described as a reaching out by faith supported by shrewd guessing from the known to the unknown. Apart from whatever general intelligent observations may be made in situ of the evidence of former mining activity, the method depends largely on the examination of the past history of the field as revealed in the official records, company reports, plans of underground workings, local newspaper accounts, and the testimony of practical miners formerly employedon the field, the' reliability of which has to be carefully sifted. The matter derived from the examination of these sources must next be rigorously collated and correlated where possible. When the review of all individu!1l features and aspects has been completed, tentative and speculative conclusions may be drawn which, though not verifiable before the event, will usually prove to be more serviceable guides in exploratory operations than mere "blind stabbing."As an actual illustration of what is involved in the mode of procedure outlined above, the following is the description of an investigation in which the writer took part.In 1937, during the course of the Commonwealth Aerial, Geological and Geophysical Survey of Northern Australia, a detailed geological investigation was undertaken of the Croydon gold field, situated near the south-eastern. extremity of the Gulf of Carpentaria in North Queensland.The history of the field briefly is as follows: It was discovered in 1885, reached its peak of production 1896, declining thereafter till 1906, when operations ceased. The total production was about 1,000,000 ounces of gold bullion, containing approximately 40 per cent. of silver. The gold bullion was won from flat-dipping quartz reefs, which yielded an average of 2.oz. to the ton, and the maximum depth to which production occurred was 500 feet. Subsequent prospecting below this depth failed to locate further ore.In consequence of the inaccessibility of the mines and the almost total masking of the' surface by alluvium, the investigation of future possibilities became largely an. office ,study, which was conducted under the following headings:-1. Recording of factual data of each mine separately.

Jan 1, 1950

By Chris Larsen, Ian Orford, Marilene Renaud, Mike Cooper, Lud Strah

"An AG/SAG mill was commissioned at the Brunswick Mine concentrator in October 1998. This paper discusses the original liner design for the bi-directional AG/SAG mill, observed liner wear, subsequent liner design modifications, and benefits. The mill liners consist of steel top hat shell liners, steel end liners, rubber grates and rubber lined pulp lifters.Lifter profile and plate thickness measurements were made on monthly shop days. Trends of wear rates were used to project when liners required replacement. Wear profile information was also used to determine where liner re-design would improve wear life or minimize scrap loss. Charge motion simulation modeling was used as a tool to assist liner design modifications.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is a large underground lead/zinc mine with a nominal production rate of 10,000 tonnes per day. The Brunswick concentrator commenced operation in 1964 with conventional surface crushing followed by rod and ball milling to reduce run of mine ore to the required size to feed two parallel flotation circuits. In 1998 the AG (autogenous grinding) mill was commissioned for a nominal production rate of 9,000 tonnes per day replacing two surface crushing plants, three rod mills and three primary ball mills. In May of 1999 the mining rate was increased and the service of the AG mill was changed to a SAG (semi-autogenous grinding) mill with the addition of 4 inch steel balls (4% volume). The mill operates in closed circuit with 0.66 meter horizontal cyclones to produce a ground product of 90 micron nominal size (K80).The AG/SAG mill liners are steel (Norsteel, chrome-moly steel) with rubber grates and rubber lined pulp lifters.The original liner design was based on studying other AG/SAG mills and recommendations by the liner supplier, Norcast. Design factors taken into account were total cost of lining (including material and labour), protection of mill shell and impact on operating performance."

Jan 1, 2003