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By Gláucio Barros Barcelos

Os sistemas de automação Nível 2 da LTQ da Aperam estão em operação a mais de uma década. Esses sistemas foram desenvolvidos sobre plataforma de hardware Alpha Server DS20E e sistema operacional OpenVMS 7.2. Apesar da confiabilidade da plataforma utilizada, atualmente está descontinuada pelo fabricante, bem como o serviço de suporte ao sistema operacional utilizado que também foi encerrado. Com a evolução da tecnologia Intel, apresentando baixo custo de hardware, suporte, manutenção e desempenho, foi tomada a decisão de migração dos sistemas de automação de Nível 2 da LTQ para a arquitetura de hardware Intel e sistema operacional Linux. Esta migração teve como objetivo a eliminação da obsolescência a que os sistemas estavam submetidos. A migração envolveu uma estratégia que minimiza riscos e reduz modificações necessárias nos sistemas de automação envolvidos. Dessa forma, bibliotecas de funções com funcionalidades semelhantes as disponíveis no sistema OpenVMS foram desenvolvidas. Este artigo descreve todo esforço envolvido na migração dos sistemas e os resultados obtidos.

Aug 16, 2017

By Savita Schlesinger, Mike Hanna, Nathan Scalla, James O’Shaughnessy, Steve Miller

Loudoun Water’s Quarry A (Milestone Reservoir) project involves conversion of a rock quarry to a billion-gallon raw water reservoir. The project includes a new 40 MGD pump station, deep intake shaft, and three drill and blast intake tunnels for accessing the reservoir. Due to concerns regarding constructability and construction risks, the project design was paused while a Construction Manager At-Risk (CMAR) contractor was procured. The CMAR contractor was engaged collaboratively with the design team to provide risk and constructability input for refining the design. Aspects of the original design, design modifications, and benefits of the CMAR collaboration will be presented.

Jun 13, 2023

By Dan B. Kivari

One of the key operations in any milling circuit is grinding. Over the last two decades, large diameter Semi-Autogenous Grinding (SAG) mills have become the preferred primary grinding mills. The drive systems became more complex as the size of the mills became larger, during which time operating and design experience for SAG mill accumulated. Considerable reliance is now placed in power electronics to provide flexibility in SAG mill operation to meet the demands of lower operating costs. Whereas earlier most SAG mills were designed to operate at fixed speeds, present day SAG mills can operate at a fixed speed or variable speed through the use of an AC synchronous motor or DC motor. However, this flexibility comes with an increase in capital and operating costs. Since the capital and operating costs of a project directly affect the project's rate of return, the selection of a SAG mill and its drive system should depend, in part, on the impact that the extra cost makes on the project. This impact can be measured by performing an economic analysis based on Net Present Cost (NPC) calculations. Although the NPC calculation is an important factor in the grinding mill selection, other factors such as reliability of mill drives and power source are important elements in the decision making process. This paper examines how the NPC calculation, plus reliability and power source, influence SAG mill selection.

Jan 1, 1991

By Dan B. Kivari

A key operation of any milling circuit is grinding. Over the last two decades, large diameter semiautogenous grinding (SAG) mills have become the preferred primary grinding mills. The drive systems became more complex as the size of the mills became larger, during which time operating and design experience for SAG mill accumulated. Considerable reliance is now placed in power electronics to provide flexibility in SAG mill operation to meet the demands of lower operating costs. Most earlier SAG mills were designed to operate at fixed speeds. Present day SAG mills can operate at a fixed speed or variable speed through the use of an ac synchronous motor or dc motor. This flexibility, however, comes with an increase in capital and operating costs. Since the capital and operating costs of a project directly affect the project's rate of return, the selection of a SAG mill and its drive system should depend, in part, on the impact that the extra cost makes on the project. This impact can be measured by performing an economic analysis based on net present cost (NPC) calculations. Although the NPC calculation is an important factor in the grinding mill selection, other factors, such as reliability of mill drives and power source, are important elements in the decision making process. This article examines how the NPC calculation, plus reliability and power source, influence SAG mill selection.

Jan 1, 1992

By E. Busse

"Heath Steele Mines Ltd. operates a lead-zinc-copper mining and milling complex in New Brunswick.• During the past seven years, as ore reserves increased, the mill capacity was first expanded to 1,600 tpd and then to 3,000 tpd. In the last expansion, instead of building a completely new 3,000-tpd mill, or adding to existing installations, Heath Steele retained service facilities, buildings, ore bins, Jab, etc., and removed and replaced almost all existing process facilities. Requiring a complete mill shutdown, the expansion had to be carried out in minimum time. Also, new equipment had to fit into existing space. Critical path networks of the project were prepared, a tight schedule for construction was mapped out and progress charted daily to detect problems before they could interrupt the schedule. Heath Steele supervised the purchasing, handling and storage of new equipment, maintained liaison with the engineering contractor and became a sub-contractor, using its own staff to install all flotation equipment and process piping. The 1,600-tpd installation was dismantled and a 3,000- tpd unit was successfully put onstream in 5 months - on time and within budget. One benefit stemming from the expansion: production increased 87 per cent while operating and maintenance labour rose only 8 per cent."

Jan 1, 1972

By R. L. Russell

Production at Freeport Indonesia's Ertsberg open pit copper/gold mine started in 1972 at a rate of 7500 t/d. Mill throughput remained at that rate for a number of years until the discovery of the Ertsberg East (GBT) orebody. This discovery prompted three successive expansion stages from 1981 to 1988 that boosted production to 20,000 t/d. The discovery of the huge Grasberg porphyry copper deposit in 1988 launched a new era of much larger expansions. The first of these involved installation of a fourth primary mill in 1989 to bring production up to 32,000 t/d and was immediately followed by an expansion of the crushing and screening plant and the addition of a new south concentrator to bring production to 57,000 t/d in 1991. The addition of a primary ball mill and the changeout of the original Denver flotation cells in 1993 has served to optimize current production at a level of 66,000 t/d. A major expansion is now in progress. This includes construction of another new concentrator to house a SAG mill circuit and large Wemco flotation cells in an area created by the removal of 6,000,000t of glacial material. This current expansion, with a planned completion in 1995, will take production to 115,000 t/d. This paper describes the evolution of the Freeport Indonesia (FI) concentrator to-date and will then go into an in-depth discussion of the 66,000 and 115,000 t/d expansions.

Jan 1, 1994

By David Kress

Grinding mills, both autogenous and ball can be powered by several basic means. The three methods used today are girth gear drives, gearless drives and trunnion coupled reducers. This paper will focus on the first of these methods -girth gear drives. The girth gear drive has been used on thousands of mills which continue to operate successfully. These drives are noted for their simplicity and low cost. In the past, the horsepower capacity of girth gears has been slow to keep up with the horsepower increase required by the mill builders, particularly since the advent of the SAG mill. Gear manufacturers had capacity for 2000 HP mills in the 1950's, 5000 HP in the 1960's and 6500 horsepower in the 1970's. The 70's and 80's brought dual pinion girth gear drives which allowed mill sizes beyond 10,000 horsepower. Gear manufactures who could not keep up with the pace of the horsepower demands and the quality and reliability demanded by the mill builders and users have fallen by the wayside.

Jan 1, 1991

By The Staff

FOR forty years cyanide men have been intensively engaged on the treatment of sulpho-telluride ores. So far as we know, the processes used today were-with the important exception of the concentration plus high-lime process at the Victor mill (1915)-in use, or had been tried, in the earl y years of the century. Roasting, bromocyanide, ordinary cyanide, table and vanner concentration, floating and treating the concentrate, roasting con-centrates prior to treatment, etc., all were used at Kalgoorlie in 1904 or earlier. Flotation, followed by shipment of the concentrate to the Golden Cycle mill, was the practice at the Vindicator mine, Cripple Creek, for some years prior to 1917. Similar practice was employed in the Portland Independence mill at Victor, Colorado, and was lacer superseded by the table concentration, high-lime cyanide treatment of rails of the older Portland Victor mill. During all this time, an immense amount of research was being clone on these ores by the staffs of numberless companies. Conclusions were drawn and mills built. But if the results of one per cent of this research were ever published in sufficient detail for intelligent use by others, the Lake Shore staff has been unable to discover them, or does not recall having clone so. Government laboratories-as for instance chose of the Mines Branch, Ottawa, in or about 1927-have touched upon certain methods in their publications, but they simply have not had the time to finish the job. The paper by W. E. Johnston, Tellurides-Problem or Alibi? (E. & M.]., Aug., 1933), aroused wide interest and comment. It published conclusions, some right and some wrong, and gave the evidence adduced by the author i:n support thereof. Conclusions published without supporting evidence are to most of us worse than no conclusions at all. We suggest chat, if even one-tenth of the operators had published full, detailed results of their laboratory work, ad vance in the treatment of sulpho-telluride ores would have been very much accelerated. Therefore, we venture to inflict upon the Institute a compendium of the results of laboratory work performed during the past few years at the Lake Shore mill. It is really a summary of the more interesting results to date, prepared by the mill staff for their own use and benefit. But we hope chat the discussion under any heading is so detailed chat it will be intelligible to anyone interested in that phase of the subject.

Jan 1, 1936

By C. S. Parsons

Introduction Up to the present, the operation of small mills for the treatment of gold ores has not been favoured in Canada to the extent that it has in other countries. For instance, a list of the operating properties in Southern Rhodesia, published in The Rhodesian Mining Journal of November, 1934, shows for the month of September, 1934, that there were over 500 small mills treating less than 50 tons per day, and the majority of these between 5 and 25 tons. They are operated by individuals, syndicates, and small mining companies. It is presumed that the operations are profitable, although from the published figures of the tonnages treated and the yields, it is difficult for one familiar with Canadian operations to understand how this can be possible, in the majority of cases. Most of these small mills employ stamps with plate amalgamation and with, occasionally, tables to produce a concentrate. Enquiries have been received from many parts of the world respecting milling practice suitable for small gold mines and the type of plant used in Canada. The tenor of these enquiries leaves the impression that the majority of the writers assume that the practice would be similar at all small properties. This, of course, is not the case. Conditions vary widely, and what would be a suitable mill for a typical Nova Scotia ore would not necessarily be wholly adaptable to many ores in Ontario, Quebec, or British Columbia. This paper has been written with the intention of inviting discussion, and it is hoped that, by such discussion, the subject will be more fully dealt with than has been possible in the time at the disposal of the writer. Only more or less standard principles and practices have been dealt with, and, purposely, no reference has been made to plants using mills of the Hadsel, the Nutt, or the Gibson type. As there is available but little reliable information on the costs of installation and operation of small mills, it is also hoped that those contributing to the discussion of milling practices for small mines will be in a position to give these data for the benefit of those contemplating the erection of small plants in Canada. Although it is difficult to generalize, it can be said that there are three types of gold mills commonly used at small mines: (1) Amalgamation and Gravity Concentration; (2) Amalgamation and Flotation; and (3) Cyanidation.

Jan 1, 1935

By J R. Brinkmann, S G. Giltner

Nearly all of the South African gold mining industry still uses fuse and igniter-cord initiation systems. Over the past 30 years numerous attempts at developing new initiation systems have not yielded a viable alternative. New initiation systems for narrow stopes are currently being developed by various concerns and the likelihood of these efforts producing feasible alternatives is greatly improved due to the recent advances in electronics technology. The greatest potential benefit of alternative initiation systems is increased production rates through improvements in accuracy and reliability of firing over that of fuse/igniter-cord. Another important feature is the capability of millisecond delay firing as this can lead to reduced stope cleaning times by way of enhanced rock throw and improved fragmentation characteristics.

Jan 1, 1989

This paper describes the MillMapper technology developed for condition monitoring of liners and other operational parameters in grinding mills used for mineral comminution, by presenting a case study of its application. MillMapper provides maintenance engineers, operations managers and process and plant metallurgists with quantitative, accurate and reliable condition monitoring data for informed decision making regarding the maintenance and metallurgical aspects of such mills. MillMapper uses calibrated laser scanners for the capture of three-dimensional surface representations inside a mill during a shutdown so as to determine shell, feed and discharge liner thickness at a resolution of several million data points, a procedure that nominally takes five minutes to complete. Once several data sets over time have been collected inside a mill, MillMapper can be used for liner wear, liner wear zone, liner weight, ball charge volume, ball charge weight and intelligent profile tracking over time. Liner tracking in combination with site defined reline and failure criteria and with throughput tonnage data is utilised for change out prediction of each separate liner segment type.

Jan 1, 2008

By M. L. Lissberger

entirely suitable for certain uses and even possess advantages over present solders at high temperatures, but they are certainly not suitable for all uses. However, it is conceivable that their use in many places will effect a material conservation of tin. It will probably be wiser to use cadmium in solders where good results have been obtained than in brass where this element will be a source of possible trouble. F. F. Colcord,* New York, N. Y.-—The cadmium-lead solder has a higher conductivity than the lead-tin alloy, which ought to make it advantageous in the manufacture of electrical machinery. In the case of solder for tin-can work, one of the high officials of the American Can Co. said that he fully intended to .give it a good trial, and I do not believe they are going to reach hasty conclusions and run the risk of poisoning the public. Solder, Its Use and Abuse Milton L. LissbeRgeR,† New York, N. Y.—Solder is a mechanical mixture of tin and lead, a fact which is susceptible of very simple demonstration. A bar of solder of a grade even as low as 30 per cent. tin and 70 per cent. lead, passed through a buffing machine, will show a surface practically identical with that of a bar of second-quality or reclaimed tin. The buffings, on chemical analysis, will prove to be almost pure lead. According to the best practice, solder is made in the following manner. Virgin pig lead is first melted, and when it is thoroughly liquefied, virgin pig tin is added, together with a small amount of flux; the latter is for the purpose of bringing to the surface the so-called "liver," consisting of impurities that may have remained in either the lead or the tin as a result of incomplete refining. The combined material, when completely liquid, is thoroughly stirred for some hours, and is then cast into small pigs. Just before casting, and continuously during this operation, the molten metal yields dross, consisting largely of the oxides of lead and tin; this should be carefully skimmed off. After the pigs have cooled, they are taken to a smaller kettle, re-melted, and cast into the desired shape for use; or if wires, ribbons, etc., are to be made, the solder is cast into slugs suitable for extrusion and rolling. During this second operation, the skimming of dross should be even more carefully done than at first. Hand mixing has proved to be the only reliable method for the production of the best quality of solder, irrespective of its percentages of lead and tin. The best quality of solder is not necessarily that which contains the highest percentage of tin, but rather is that composition which performs best on the required piece of work. In order to produce

Jan 1, 1919

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1993

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1991

By Theodore H. Budd, Austin M. Cooney

The paper discusses the background and theories of the conditions that led to the settlement of a Lovat TBM mining in an earth pressure balance mode on a recent project in Milwaukee, Wisconsin. The settlement occurred independent of human error and caused the cost of the project to increase 50 percent. The project was mined in the highly congested downtown area in alluvial and estuarine deposits, 7.6 m below the water table with a prescribed contract requirement that precluded dewatering in deference to concern for foundations of adjacent existing buildings.

Jan 1, 1989

By S. Chatterjee, F. Suparno, A. Paithankar

Estimating reserves and quantifying resources stand as pivotal and intricate endeavours within the realm of coal mining operations. Intricate geological formations compound the challenges in resource estimation, thereby complicating reserve calculations. The uncertainties tied to geological attributes of coal, encompassing parameters like tonnage and coal quality, wield significant sway over resource and reserve computations within coal mines. This research delves into the domain of geological uncertainties, with a specific focus on calorific value, aiming to numerically characterise resources and reserves within an open-pit coal mine situated in Indonesia. To quantify resources, the coal seam geometry underwent simulation via a multipoint geostatistical technique known as single normal equation simulation. A geologically established coal seam served as the training image for generating 20 equiprobable coal models. To simulate CV, 50 realisations were generated for each simulated coal seam, utilising sequential Gaussian simulation. Deviations of the simulated coal seams ranged from -0.07% to 5.48% in comparison to the training image. The CV simulation yielded an average value of 5,920.29 kcal/kg, accompanied by a standard deviation of 586.54 kcal/kg. However, the average CV spanned from 5,305.26 kcal/kg to 6,526.55 kcal/kg across diverse simulations. For reserve calculation within the context of geological uncertainties, an algorithm rooted in maximum flow graph theory was employed to construct the ultimate pit for the coal mine. Within this final pit, the average stripping ratio was 1.62, coupled with a CV value of 6,019.66 kcal/kg. When juxtaposed with the deterministic model, the findings underscore that the stochastic ultimate pit delineates a more expansive excavation, accompanied by a heightened undiscounted cash flow.

Oct 2, 2025

By Robert J. Mitchell

A general approach to mine backfill design, including laboratory testing procedures, is outlined in this paper. Relationships between certain design parameters are developed and the effect of other factors is discussed. It is concluded that the inclusion of backfill design calculations at an early stage of mine design can often produce over-all design economies. Not only are the data needed for backfill plant and tailings disposal area design, but also the pillar recovery method and over-all mine stability are dependent on the attainable fill properties.

Jan 1, 1979

By P Shead, M A. Tuck

Both climate and methane control have been a prime concern in the development of the workings within the Deep Soft seam at Harworth Colliery. This paper describes the numerous methods employed over the past 15 years to effect control over these two major environmental pollutants at Harworth and describes a future method of working which will enable the output levels required to be achieved, whilst effecting the required level of both climatic and methane control. Firstly, the paper gives a broad historical overview of the steps taken since 1981, when production started in the Deep Soft seam at Harworth Colliery, to effect control over the main environmental pollutants in the seam. Secondly, the paper details the results of planning exercises undertaken to assess the various options with respect to panel layout, to achieve environmental control in future production districts. Finally, the recommended method of panel design to achieve the levels of production required is detailed.

Jan 7, 1997

By Paul T. Fitzgerald

Risk financing solutions are emerging to fully address environmental liabilities for mining operations. Supported by specialized insurance and alternative risk transfer (ART) products, mine owners can fund, cap and guarantee the environmental liabilities and closure obligations of a mine within a financial structure that will be acceptable to regulators. An environmental risk financing program will permit an owner to transfer the liabilities and indeed the ownership of a site to a third party that has the ability and resources to responsibly execute the closure plan. A properly structured program will be financially viable for the owner and will also respond to community and environmental opposition concerns about sustainable development and the environmental legacies associated with mining activities.

Apr 1, 2005

By R. L. Kloberdanz

Compania Minera Disputada de las Condes S.A. (Disputada) is proactively implementing closure and reclamation planning activities at its mining and beneficiation facilities (mining facilities) in Chile where regulations governing mine reclamation are not yet fully in place. These activities are being implemented to improve currently employed measures to protect human health and the environment and to enhance reclamation and facilitate future closure with regard to these areas when mining is completed. As part of this process, Disputada, with the assistance of Shepherd Miller, Inc., developed recommendations and guidelines for future closure and reclamation of the Disputada sites. These recommendations and guidance incorporate planning and operational and post-operational design considerations and practices, and standards used by the mining industry and regulatory agencies around the world. The criteria presented in the guidance are based on achieving conditions that will be suitable for the anticipated post-mining land use. This paper discusses the process and approach taken, and the results.

Jan 1, 1999