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By Xiaolong Lin, Yuanbo Zhang, Tiancheng Nie, Guanghui Li, Zhizhong Li, Zhiwei Peng, Tao Jiang

The coal-based direct reduction process has gradually become the focus of research concerning direct reduced iron production due to its advantages, including high reduction rate, stable chemical composition, and good metallurgical properties of products. Based on coal-based reduction theory and briquetting technique, this paper reports the use of microwave energy for intensifying the reduction of carbon-containing briquettes mainly consisting of magnetite concentrate and biochar. The heating behaviors of the raw materials show that under the conditions of microwave power of 1250 W, N flow rate of 4 L min −1 and briquetting pressure of 400 N, the briquettes present the highest heating rate. The average heating rate reaches 35.16 °C min −1. When the briquettes are irradiated by microwaves at 1050 °C for 45 min, the metallization degree of the reduced briquettes reaches 93.58%.

Mar 1, 2017

The Mount Isa mine in North West Queens- land produces a total of nearly 10 million t/yr from separate copper and silver lead zinc orebodies. Sampling information is mainly obtained from diamond drilling on 30 to 40 metre centers in both types of orebodies. For the copper orebodies the majority of the core is analysed for copper content using a non-destructive bulk analyser developed by the Australian Atomic Energy Commission. The diamond drill core in the silver lead zinc orebodies is usually sam- pled as sawn half core and assayed in the com- pany laboratory using a variety of methods dependent upon the level of metal content and/or the elements required. Underground development is sampled where additional information is required to improve the ore reserve estimate. The copper areas are sampled using a standard 2.0 m by 2.0 m chip sample of the wall. The chips are taken on a 250 mm spacing. Lead areas are sampled using a 100 mm wide by 4 mm deep channel over intervals determined by the area geologists. The massive, irregularly shaped copper ore bodies are mined as large sublevel open stopes and pillars. Ore reserve estimation on both a production unit and global scale is routinely carried out using a geostatistical system developed in-house and running on a Sperry 1100 mainframe computer. Copper grade, tonnes and the Kriging var- iance are estimated at points on a user defined grid. The Kriging program uses 10 m assay composites from diamond drill core and underground chip samples. One average (rela- tive) variogram is used throughout the main copper orebodies. The validity of using an average variogram was verified by the original geostatistical study undertaken in the late 1970's.

Jan 1, 1987

By AIME AIME

N EARLY 1300 members and guests crowded the halls of the Engineering Societies Building during the winter meeting of the Institute just closed, and more than 600 attended the banquet. In variety of program, quality of papers, interest in discussion, and brilliance of social features, the meeting maintained the high reputation of the past. Nothing elaborate in the way of excursions was attempted, experience having proved that February weather in New York is much too uncertain to warrant extensive field trips. A sight-seeing journey up the Hudson to the Bear Mountain bridge was, however, made despite the snows of the week before and the week after. The annual business meeting, while attended by a minority of the members in the building, was marked by the display of keen interest in the work and called out several interesting discussions. The excellent reports of the committees that had organized their work and directed it along definite lines, emphasized the need of funds with which to support assistants or Fellows who shall correlate and put to the highest use the facilities of the Institute in research along technical lines. This thought was developed at the banquet by the retiring president, J. V. W. Reynders, and it is expected that the Directors will take early steps to collect a fund for this purpose. The number of the individual sessions was too great and the papers and discussions too numerous to permit mention here of all the features of inter- est. A general review only follows. The papers and detailed discussions will be printed and sent to members as promptly as possible.

Jan 1, 1926

By C. J. Bauer

WHEN the pipe lines from the Middle East to the Mediterranean are completed, the Middle East supplies will relieve the strain on Western Hemisphere petroleum resources, part of which are now shipped for Eastern Hemisphere use. A sketch of the world petroleum situation as it appears today and in the immediate future will help in understanding the future place of Middle East oil supplies. Anticipated 1951 world demand is slightly under four billion barrels. To meet this requirement, crude output and refinery runs throughout the world (including Russia) must be increased about two million barrels per day above the average of 1947. This increment, together with pipe lines, tankers, and other facilities, will require in excess of ten billion dollars of new capital in the next four years. We are, therefore, looking forward to the greatest expansion program in the history of the industry.

Jan 1, 1948

By Casper A. Nelson, Wendell M. Whitecotton

A WIDE variety of lead ore is treated by the Midvale Smelter, for it is a custom plant not only treating Company lead concentrate and direct-smelting ores but also custom ores and concentrates, principally from Utah, Idaho, and Nevada, with lesser amounts from Arizona, California, Colorado, Montana, Oregon, and Washington. The principal operating departments of the plant are weighing and sampling, Wedge roaster, D&L sintering, blast furnace and drossing, and baghouse. The lead bullion produced is shipped to a subsidiary, the U.S.S. Lead Refinery, Inc., at East Chicago, while the by-products, such as matte and speiss, are shipped to other smelters or re-treated at the plant.

Jan 1, 1948

By Wilson Quispe, Luis Silva, Rubén Alvarado

El presente trabajo nos permitirá compartir los desafíos que en el pasado reciente se enfrentaron, cuando se pusieron en marcha las primeras operaciones de gran minería que contemplaban los molinos SAG el cual fue resuelto acudiendo a empresas extranjeras para poder cubrir la necesidad de realizar el cambio de los revestimientos. Esto porque los molinos SAG eran nuevos en el país y las empresas prestadoras de servicios mineros carecían de experiencia para poder ejecutarlo.

Sep 29, 2023

By Z. Sun

Magnetic fields have been used for inclusions removal from melt and preparation of materials with gradient compositions. Fundamental in these applications is that the induced magnetic forces on the particles/melt can enhance migration and change the interaction behavior. In the present paper, migration and interaction behavior of electrical-insulating particles in a conductive melt under strong magnetic field are theoretically analyzed. It is found that the migration can be considerably enhanced for micrometer sized particles by applying a strong magnetic field. In addition, two forces are involved in the interaction between two particles: the interparticle magnetic dipole-dipole attractive force due to magnetization and the repulsive force induced by flow of the melt. This theoretical analysis renders a better understanding of recent experimental results. Additionally, a new method by using strong magnetic field can be proposed to control the particle size distribution for the preparation of metal-matrix composites.

Jan 1, 2009

The following data cover a phase in the systematic testing of gold deposits which does not appear to have been specificalIy investigated.In boring either secondary or primary deposits, gold, by virtue of its high specific gravity, will tend to migrate downward, below the driving shoe or bit, and thus cause misinterpretation of value unless final recovery Can be effected after the hole has been bottomed.Unlike fortuitous and non-recurrent errors, due to, say, running ground, "pile driving" or rock fractures, systematic error due to migration may be unpredict.able from operating data alone, and, therefore, result in serious miscalculation of the weighted average upon which the engineer's recommendation is based.Applied to diamond drilling, loss by downward migration appears to have been largely responsible for distrust of sludge assays in the past. On the other hand, although modern practice rightly trends towards an integration of both core and sludge samples in borehole valuation, the possibility of systematic loss must be investigated when using combination graphs such as those of Longyear, Moehlman and WeIler. If the sludge value is incorrect the combination graphs will serve solely to stultify the core valuation.It appears to be axiomatic that: 1. With full core, sludge assays are of minor import.2. With recovery above 90%, differentjal grinding, of the high grade sections may have occurred, and this c!ln be corrected only by the us.e of cOJ;rect sludge valuation.3. With core recovery less than, say, 70%, no accurate valuation is possible without integrating the sludge assay.4. With less than, say, 10% core recovery, the sludge assay affords the sole basis of evaluating a borehole which may have cost many hundreds of pounds.The conditions demanded for reliable sludge valuation have, in practice, been restricted to high quantitative recovery and return of nearly 90% of the drill water. It is submitted, however, that the following additional knowledge is required:1. The nature of gold distribution in the ore.2. The lifting power of the return water column, which can be gauged by the maximum quartz particle, provided that the degree of "hindrance" can be determined.3. That all gold has been cleared from the bottom of the borehole immediately after it has passed through the orebody.The three cases discussed hereunder are offered not only as proof of the thesis, but also in the hope of promoting discussion on the interpretation of borehole values and on methods for saving free gold in the sludge. The fact that two of them cover alluvial boringand the third diamond drilling has resulted in this attempt to reduce the behaviour of free gold to a basis common to all types of boring.

Jan 1, 1950

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 E. Fritz

This paper reviews the history, developments and 10 milestones of the oxygen steelmaking processes, with a special focus on conventional autothermic converters, high-speed converters with a blowing rate up to 5 m3n/t min and allothermic converters with coal addition, post combustion and the possibility to increase the scrap rate up to 50%. Related operating results are introduced. A new process route, which is based on hot metal and chromium ore, is outlined. The cost advantage for the production of 304 stainless steel grade is higher than 100 USS/t. The synthesis of EAF and oxygen converter steelmaking, a comparison of decarburization rates, refining combustion burners for optimized oxygen-management in EAF and an example for a large advanced EAF are outlined. Possibilities of flexible steelmaking and the growth and outlook of worldwide oxygen steelmaking are described.

Jan 1, 2004

By Robert S. Shoemaker

The development of a metallurgical project is a business venture rather than a technical exercise, and its real objective is to obtain the maximum return on investment consistent with the limitations imposed by company policy and the requirements of society. Demand for profits is the driving force for technical advances and naturally leads to improvements in processes, equipment and plant designs. In the mineral dressing field there have been virtually no new processes developed since the introduction of flotation, and the steady erosion of profits by inflation has been offset only by increasing equipment size. Unfortunately, in recent years, plant designers have not always utilized the largest equipment or the opportunities for functional and economic design presented by the development of larger equipment. Lower cost plants can be developed providing that unrealistic restraints arising from the prejudice of past practices are avoided. As an illustration of this premise, three different approaches were taken toward the design of a clearly delineated but hypothetical copper concentrator of 20, 000 tons per day capacity. While the same flowsheet was used in each case, designs were produced for a conventional plant, an alternate using the largest available equipment, and a third scheme utilizing large equipment and the most functional design which could be developed, including features derived from many plants in many different industries. Capital costs were developed for the three separate designs based on a location in the southwestern United States. Ancillary facilities were identical in each case and included a mine truck shop, a maintenance shop, a general office, and a nominal starter dam for tailings disposal within 5000 feet of the plant. Water supply within 1000 feet of the plant, and power furnished to the property boundary has been assumed in each case. The flowsheet of the three plants is shown in Figure 1 and represents the treatment of a typical sulfide copper ore by three- stage crushing followed by single-stage ball milling. Concentration is by flotation roughing and scavenging followed by regrinding of the concentrates and two stages of cleaning.

Jan 1, 1971

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 Craig M. Sams

Matching mill? drives to mill power draws is a relatively new practice with the introduction of variable speed drive arrangements. Semi-autogenous grinding (SAG) mills are the focus of this paper as ball and rod mill characteristics are easily charted as charge loading and speed change. In addition, a look at types of drives available in the market and mechanical ratings is outlined to match the specifics of each drive.

Jan 1, 1991

By Russell Spry

THE cyanide plant of the Cariboo Gold Quartz Mining Company, Limited, at Wells, B.C:, in the Barkerville section of the Cariboo mining division, was erected during the latter part of 1932 and placed in operation in January, 1933. The initial capacity of the plant was about 50 tons daily. This was increased to 100 tons at the end of 1934 and stepped-up to 150 tons in September, 1935. It is expected that further plant extensions, for milling a total of 200 tons daily, will be required during the early part of 1936. Recent additions to the mill have been so planned as to permit ready expansion to 275 tons daily when underground development warrants the milling of this tonnage. It is the purpose of this paper to outline briefly the steps taken to bring the plant to its present capacity and to comment on possibilities for further plant expansion. The gold in Cariboo Gold Quartz ore occurs as free gold in the quartz and on pyrite surfaces. Some of it is very finely divided, specks l/10,000 inch having been observed microscopically, according to Dr. G. Hanson. In addition to pyrite, which comprises probably 15 to 20 per cent of the mill feed, galena and sphalerite are present, with small amounts of arseno-pyrite and chalcopyrite. Sulphobismuthites-chiviatite, galenobismutite, cosalite, etc.-occur more or less frequently in certain sections of the mine. Following tests on Cariboo ore by the Mines Branch, Department of Mines, at Ottawa, treatment of the ore by straigh t cyanidation was recommended and a 50-ton plant employing continuous counter-current decantation was erected. This plant was built as a pilot mill, the intention being to erect a larger mill after metallurgical treatment had proved successful over an extended period. This original installation, however, has been enlarged and retained as an operating unit, additional equipment being added to it as capacity increases have been required.

Jan 1, 1936

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 G. H. McKay

AT the Eagle mine, near Gilman, Colorado, where the Empire Zinc Company have installed an underground mill, transportation problems were comparatively simple. A railway siding on the Denver and Rio Grande railway is equipped with an unloading dock or platform at the portal of their service incline adit to the mill. This 18-degree incline is approximately 600 feet long from the unloading track to the head of the mill skipway. For the Big Missouri mill, upwards of 2,500 tons of material and equipment had to be trucked from tidewater at Stewart, B.C., a distance of 21 miles to the Big Missouri camp at elevation 2,800. From that point, this freight had to be moved either over or through the Big Missouri ridge, rising to elevation 3,450, to its final location 800 feet from the surface between elevations 2,150 and 2,350. Immediately after leaving the government dock at Stewart, the road crosses the International boundary line into Hyder, Alaska, and then follows a water grade for eleven miles along the lower stretches of the Salmon river. leaving the river, the road climbs for two miles before crossing back into British Columbia territory at Silver Heights, and then continues for another mile and a half to where the Big Missouri road branches off from the main road to the Premier mine. For a distance of four miles from the junction of the roads, the Missouri road is very narrow, with many sharp curves and with irregular up and down pitches and grades up to 25 per cent until it reaches the Summit. From there on, a fairly easy grade leads a mile and a half to the end of the road on Joker Plats. In winter, the last stretch of road is subject to heavy snow drifting, especially through a narrow funnel-shaped gulch, known as 'The Gap', where the snow may pile up to a depth of over twenty feet.

Jan 1, 1938