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By L. Garycki, P. Poks, R. Urbaniak, T. Gabka

In 2016 at Głogów Copper Smelter KGHM Polska Miedź S.A., after shutting down the shaft furnaces new FSF was launched. Currently, it is the only smelter with two direct to blister flash smelting furnaces in operation. The main difference between the vessels are the dimensions and production capacity. The new furnace design output is about 30% higher compared to the old flash smelting furnace working for 40 years. The paper presents a comparison of both FSFs operation, differences in technology and the way to optimize the process to maximize efficiency. INTRODUCTION KGHM Polska Miedź S.A. is the only company in Poland (eastern part of Europe) that extracts and processes copper ores. It is located in the south west of Poland and this region is called the "Copper Basin”. KGHM PM S.A. consists of three underground mines: Lubin, Polkowice-Sieroszowice, Rudna, concentrator plants, a tailings pond plant, three copper plants: Legnica, Głogów and Cedynia wire rod plant in Orsk. The publication relates to the operation of the furnaces in Głogów (the plant in Głogów consists of Głogów 1 and Głogów 2 which form integrated smelting and refining facilities). In 2016, after closure of the shaft furnaces technologies in the Głogów 1, a new FSF commenced operation. The simplified process flow sheets are given in Figure 1 and 2. Technological schemes are similar, but due to the differences in them, they will be discussed separately. Głogów 1 Enriched ores are discharged and directed to the feed preparation plant. Delivered concentrates are built up on the three bedding aisles in appropriate proportions. The concentrates are distributed in even layers in one of the three aisles. Aisle emptying is done with a blending machine which cuts across the concentrate layers and collects thus blended material, sending it via belt conveyors to a storage bin. From the cross- blending machine and conveyor assembly, the mixture of concentrates is directed to drying in the steam dryer. Part of the charge is directed to the FSF and part to the roaster for carbon elimination. Known in the world roasters are used to eliminate sulfur compounds or arsenic. In the case of KGHM deposits, the aim of the process is to reduce the energy value of the feed by eliminating carbon and converting sulfur from sulfide to sulfate. Changing the nature of exothermic to endothermic material is crucial in the case of furnace operation with design performance. Roaster is a separate furnace with an innovative character.

Jan 1, 2019

By Terry Keough

Contents for discussion ?Current liner technology ?Innovation of magnetic products ?Development of magnetic wear liners ?Installation and change out method ?Uses and capabilities ?Internal wear liners ?Summary Vulcanized rubber ?Many of you are familiar with using vulcanized rubber to provide wear protection on mining equipment. For years, this was the standard for most mining equipment, and mines spent a lot of money fabricating and lining steel equipment.

May 1, 2010

By C. Dirscherl, M. Combes

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71% - as confirmed by real operational data from the Antapaccay mine in Peru. It was the first plant worldwide to use gearless drives for both applications.INTRODUCTION – THE GEARLESS PRINCIPLE The principle idea behind a gearless drive system is to reduce the number of components and diversity of parts. Especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material. In order to apply this principle of simplification we will take a look at the components of a conventional drive system consisting of: - Driven equipment (mill, conveyor, slurry pump) - Components altering the rated speed (gearboxes, girth gear / pinion) - The electric motor - Starting devices for the motor (VSD, CCV, LRS, clutch), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage - Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation - The electrical supply system (cables, switchgear, transformers, protection equipment)"

Jan 1, 2014

By Stephen Hammond

?Our own prejudices form the greatest barrier to creating an inclusive working environment.? Have you witnessed? Racism or Negative Comments about an Aboriginal Person? ?You are free to compete with all the others?, and still justly believe that you have been completely fair.? Lyndon B. Johnson

May 1, 2008

By Jonas Olsson

"The picture of China as an antiquated continent is changing rapidly and fast-forwarding progress is a fact in most infrastructural fields. Mining is not an exception. China is today the largest producer of aluminum, coal, steel, zinc, tin, lead and manganese and the country’s mineral resources comprising approximately 12% of the global reserves ranks them number three in the world after US and Russia.In order to feed the growth industry is needed to take extra ordinary strides to improve supply of raw material and Chinese mines are continuously being upgraded with the latest western technology to meet the increasing domestic demand of base metals.In Anshan located in China’s northeast province Liaoning we find one of the fastest developing mining companies, Angang Iron & Steel Group Co. Ltd. With their six mines that together process approximately 60 M ton iron ore/year Angang Iron & Steel Group Co. Ltd is the largest iron ore company in China. The group’s thorough pre-studies and technical evaluations over the past five years have made them very successful in both plant upgrades of existing operations and green field projects.INTRODUCTIONWe live in a time when the world market is gradually acclimatising to the global consequences of “The China effect”. An effect caused by a formerly sleeping giant nation that during the last years has awakened and developed beyond comparison, primarily because of booming infrastructure projects and demand for capital and consumer goods"

Jan 1, 2006

By Kimiz Dalkir

Some things to keep in mind? ! What is your role in knowledge management? ! What knowledge-related challenges are you facing today? ! How does important knowledge get shared in your organization? ! Can you name factors that enable/block innovation and organizational learning in your work context? A brief history of KM? ! Top-down / imposed ! Rigid / bureaucratic ! Slow deployments ! Expensive ! Unpopular: empty libraries, info-junkyards, low adoption rates ! Problems measuring success ! The result: traditional KM is not the answer

May 1, 2003

By Robert J. Maron, Mark Fernald, Alex Van der Spek, O’Keefe. Christian, Tim Bailey

"Sonar array-based non-invasive flow measurement technology is becoming an accepted and many times a preferred method of measuring challenging single and multi-phase flows in the mineral processing industry. This fundamental sensor and measurement technology has been extended to two developments that provide new measurement capabilities useful for monitoring and managing slurry flows and pipes.The first development is the non-invasive measurement of real-time velocity profile of slurry flow in horizontal pipes. Multiple non-invasive passive sensors measure localized velocities and are combined to provide a velocity profile measurement. This information can be used to determine the approach and onset of solid deposition on the bottom of the pipe. Having this information in real time can enable operation at lower velocities and/or higher solids concentration while avoiding solids deposition or plugging and its associated operational costs.The second development is the non-invasive measurement of pipe wear on slurry lines. Presently, such measurements are made by hand-held portable ultrasonic thickness gages. The numerous shortfalls associated with the manual method are overcome with a set of permanently or semi-permanently installed transducers clamped onto the outside of the pipe. This ring of sensors contains a series of conformable ultrasonic transducers spaced around the circumference, which are used to measure the thickness of the pipe under their respective locations. Compared to manual methods, this system and approach results in better repeatability and accuracy. It also decreases inspection labor costs and pipe access requirements. The minimal accuracy variations in the presence of varying environmental temperatures will be shown. Trending of pipe wall thicknesses in high wear pipelines will be illustrated. The benefits of significantly improved pipe wear monitoring in hydrotransport lines with abrasive solids, and associated improvement in the ability to insure safe operation and avoidance of costly environmental damage due to leaks caused by pipe wear will be discussed."

Jan 1, 2009

By G. Ellie, D. F. Coates

"The mining of coal in thick and inclined seams is difficult, and there are only a few countries in the world that are really interested in the problems associated with their exploitation. In France a considerable amount of investment has been made in the mechanization of systems appropriate for such conditions.For seams inclined up to 50 degrees, of normal thickness, a new system was introduced in 1967. It consists of a longwall advancing to the rise with walking props, a shearer and hydraulic backfill. During the first two years the panel productivity was an average of 25 TN/MS, and they foresee the possibility of reaching an average of 30 TN/MS.A system for thick beds, both horizontal and inclined, is in p•rocess of being mechanized. In 1969 they started with a method consisting of a longwall in a footwall slice, or sub-level drifts with walking props, and caving and drawing up to a height of 20 m of coal. Recent experiments with a shearer have produced panel productivities between 9 and 11 TN /MS, and there is hope that with experience an average of 16 TN/MS will be obtained.In 1964 a method was initiated for beds inclined from 60 to 90 degrees, based on a mechanical cutter designed by the collieries in Lorraine. An overhand slice of 4.2 m in height is taken with a drum cutter mounted on the end of a boom. Hydraulic fill is placed at the completion of a slice. The face productivity, which has been from 13-20 TN /MS, can be perhaps increased to an average of 22 TN/MS. For those companies with important reserves in inclined and thick seams, these French systems may be worth the trouble of examining in some detail."

Jan 1, 1972

By Kazutoshi Haga, Batnasan Altansukh, Atsushi Shibayama

In this study, the dissolution behavior of copper and arsenic from five different copper concentrates containing 21-34.7 %wt. of Cu, 1.3-7.3 %wt. of As and 15.6-27.5 %wt. of Fe were investigated under high pressure oxidative leaching conditions. Leaching experiments were conducted using different leaching reagents such as ferric sulfate, sodium chloride, deionized water, sulfuric acid and ferric sulfate-sodium chloride mixture in order to compare the effectiveness of each on the dissolution of copper and arsenic from copper concentrates. The effects of ferric sulfate (0.1-1 mol/L), sodium chloride (0.1-0.5 mol/L) and leaching temperature (100-180C) were investigated under 1 MPa autoclave pressure , particle size >45 m, pulp density of 100 g/L, stirring speed of 750 rpm and leaching time of 60 min. Results showed that the most effective leaching reagents for the dissolution of copper are 0.34 M NaCl and a mixture of 0.1 M Fe2(SO4)3 - 0.34 M NaCl, in which As extraction did not exceed 7%. The copper concentration in the pregnant leach solution obtained after leaching using 0.1 M Fe2(SO4)3 - 0.34 M NaCl was 13-30 g/L, while the concentration of As and Fe were in a range between 0.3-1 g/L and 0.2-10 g/L at 160C. INTRODUCTION Copper sulfide minerals, such as chalcopyrite (CuFeS2), chalcocite (Cu2S) and covellite (CuS) are used for the production of copper in mining and metallurgical industries worldwide. The conventional pyrometallurgical processing followed by electrorefining is a common process for the production of high purity copper (Moskalyk, & Alfantazi, 2003; Padilla, Aracena, & Ruiz, 2012). However, the degradation of copper content and an increase in the amount of metal impurities, especially arsenic (As), antimony (Sb) and bismuth (Bi) in copper concentrates cause serious problems to the production of copper and environmental pollution (Basha, Selvi, Ramasamy, & Chellammal, 2008; Long, Peng, & Bradshaw, 2012). Hydrometallurgical processes are used to recover metals from refractory ores, concentrates and tailings by leaching (Long, Peng, & Bradshaw, 2012; Masloboev, Seleznev, Svetlov, & Makarov, 2018). During the last decades, hydrometallurgical processing for the recovery of copper from enargite-bearing copper ores and concentrates has been extensively investigated due to its relatively more environmentally benign and less capital costs than the conventional pyrometallurgical processes (Long, Peng, & Bradshaw, 2012; Masloboev, Seleznev, Svetlov, & Makarov, 2018; Choubey, Lee, Kim, & Kim 2018). However, several issues facing the hydrometallurgical processing are incomplete extraction of copper associated with the coprecipitation of iron compounds, difficult stabilization of toxic impurities and production of a contaminated copper product (Dreisinger, 2003; Safarzadeh, Moats, & Miller, 2014). Hence, a number of studies have been conducted on the selective dissolution of copper from copper ores and concentrates or selective removal of arsenic leaving a clean copper residue using various leaching reagents or lixiviants (Safarzadeh, Moats, & Miller, 2014; Mihajlovic, Strbac, Zivkovic, Kovacevic, & Stehernic, 2007; Tongamp, Takasaki, & Shibayama, 2009). More extensive studies on the selective extraction of copper from enargite- bearing copper ores and concentrates are much needed to improve copper recovery.

Jan 1, 2019

By J. G. Henning

Following completion of planned mining operations at the Goldcorp Dome Open Pit Mine, a high-grade Shaft Pillar located in the pit highwall was recovered. Mining of this Shaft pillar faced numerous rock engineering design and implementation challenges due to its remote position on the highwall and the presence of mine workings within the wall. The case example presented in this paper discusses the geotechnical investigation performed at the site, novel measures undertaken for installation of ground support required for rockmass reinforcement and for worker protection, as well as operational challenges to successful mining of the Shaft Pillar.

May 1, 2009

By Bruce Conard

For many years, Bruce Conard has been engaged in reading about and discussing the desired sustainability of the mining and metals resource industry. He has, however, become concerned that there is a greater issue that requires our urgent attention: what challenges do we face as a global society? His Distinguished Lecturer presentation traces the idea of environmentally sustainable economic development but concludes that a business’ interest in its sustainability is predicated on the sustainability of our global society. Conard reviews some of the most serious challenges, including population growth, clean energy supplies, freshwater availability and climate change, and calls on scientists and engineers not only to apply their skills in helping solve these challenges, but most urgently, to speak with intelligence and passion about the need to act now.

Jan 1, 2014

By Kathryn L. Neale, Derek L. Mulligan, Robin E. Goad, Norman A. Duke, A. Hamid Mumin, W. John Camier

"Abstract - The NICO and Sue-Dianne deposits are being explored and delineated by Fortune Minerals Limited in the Mazenod Lake District of the Northwest Territories, using an Olympic Dam model. The deposits were discovered in the south part of the Great Bear magmatic zone (GBMZ) within the Proterozoic, Bear Structural Province of the Canadian Shield. They are the only known significant Canadian examples of Proterozoic iron oxide-hosted polymetallic deposits. Worldwide, this class includes such deposits as Olympic Dam and Ernest Henry in Australia, Kiruna-Aitik in Sweden, and Salobo in Brazil. Their considerable size, up to 2 billion tonnes, and polymetallic ore assemblages make them highly attractive targets for exploration. Common characteristics of this class include their Early to Middle Proterozoic cratonic settings with extensional rifting evolving from collisional tectonics. Deposits typically occur along major structural lineaments within the aureoles of a distinctive suite of anorogenic potassium-rich "A-type" granite intrusions. Although hosted by diverse lithologies, deposits of this class are characterized by a number of other diagnostic regional- and deposit-scale features, which may be recognized in reconnaissance- and propertyscale geological and geophysical surveys.The southern GBMZ in Canada has several characteristics (age, tectonic setting, geology and geophysical attributes) similar to those of the Olympic Dam deposit and its other significant global analogues. Airborne and ground geophysical surveys carried out in the GBMZ identified coincident potassium, uranium, magnetic, resistivity, chargeability, and gravity anomalies centered over the NICO deposit. The nearby Sue-Dianne deposit is characterized by coincident uranium, potassium, magnetic, resistivity and chargeability anomalies. Both deposits occur within a regional, northweststriking, arcuate trend of volcanic and sedimentary rocks characterized by significant positive Bouguer-gravity and magnetic responses and are believed to represent a major basement discontinuity. The NICO anomalies are at the intersection of this regional trend with a major transverse fault through Lou Lake. Regional and local geophysical data indicate the presence of significant concentrations of iron oxide within a broad area of intense potassium metasomatism. Geological mapping identified cobalt, gold, bismuth, and copper mineralization in biotite-magnetite-amphibole-sulfiderich ironstone and schist. This mineralization is localized within altered wackes of the Snare Group, which are unconformably overlain by potassium feldspar- (±hematite ±magnetite) altered rhyolite of the Faber Group. The Sue-Dianne deposit is a hematite-magnetite-Fe-silicate-cemented diatreme complex enriched in copper, silver, gold, and uranium within a broad zone of potassium, iron, quartz, and epidote metasomatism. The diatreme is located at the intersection of two major faults at the north end of the basement discontinuity and is hosted in rhyodacite ignimbrite marginal to the Faber Lake rapakivi-granite pluton. At both deposits, diatreme- and maar-facies iron oxide-cemented breccia straddle the regional metasedimentary-volcanic unconformity, suggesting that mineralization formed in a near-surface environment synchronous with the onset of volcanism."

Jan 1, 2000

By Frank B. Amon

Highland Valley Copper had to make some significant changes in the way it was working in order to counter the effects of ever-increasing costs and decreasing metal prices. A mine/mill optimization plan started in 1997 introduced new technologies and management approaches that resulted in a dramatic drop in cash breakeven costs. The changes involved employee training, added authority and responsibility for staff, better communications, and a consistent approach to setting and achieving property-wide goals. The net effect was to change the culture of the organization from one that was fragmented and focussed on local objectives to one that is cohesive and has common goals. These changes have allowed the mine to remain in business during a protracted period of low metal prices, and have positioned the mine favourably to benefit even more from any future increase in prices.

May 1, 2004

By Louis Frost

"A FIRE which forced the sealing -of the east side of Dominion No. 16 Colliery in the Town of New Waterford, Nova Scotia, occurred on October 6th, 1952 (Figure 1).So far as can be ascertained, the fire was first noticed in the roof of No. 7 East Lateral, after a brushing shot had been fired in the pavement. There appears to .be no doubt that this shot •blew out, igniting a small feeder in the roof.Regular air measurements and air samples, taken over a long period prior to the fire, indicated that the ventilation was adequate, for at no time had the percentage of CH4 in the general air current exceeded one per cent in this location. The last regular monthly samples and air measurements, taken at the end of September, showed the condition of the ventilation to be:Return at the Top of No. 8 East WallQuantity .... 27,700 cu. ft. per min.CH4 .......................... 0.32 per centC02 ................................ 0.10 per centHowever, in the week preceding the fire the mine examiner on four occasions had reported small feeders of gas at the face of the brushing in No. 7 East Lateral.Figure 2 is a diagram of the working place where the shots were fired. The face brushing had been shot down at 3 :45 p.m. and cleaned up. Two 'hurdle screens' had also been erected, one close to the face brushing and the other fifteen feet from the face."

Jan 1, 1953

By J. R. Goode

"Canada developed pioneering rare earth solvent extraction methods to recover the rare earths and thorium as by-products of uranium recovery operations in Elliot Lake, Ontario, and was a major supplier of these key elements from about 1960 until 1990. At one stage, Elliot Lake was supplying perhaps one third of the world’s yttrium as well as much of its thorium. This paper reviews the development of Canada’s early rare earth and thorium production facilities. INTRODUCTIONThe rare earths and thorium were first identified in the early 19th century but were little more than curiosities for the next century. However, in the mid-1960s the invention of rare earth-based phosphors for the cathode ray picture tube used in colour television sets launched a major demand for certain rare earths.The use of thorium as an alloying agent in aircraft and missiles grew rapidly in the late 1950s. In the same period, demand for uranium for both weapons and power production soared. Also in the late 1950s, the Elliot Lake uranium-thorium-rare earth deposits (also known as the Blind River deposits) were discovered. This conjugation of events led to uranium production in the Elliot Lake camp, quickly followed by the co-production of thorium and, later, the rare earths.Uranium production in the Elliot Lake camp continued from 1955 to 1996. Thorium was produced continuously from 1959 to 1969. Rare earths were produced, intermittently, from 1965 to 1990. Complete production records are not readily available but unquestionably Elliot Lake made a significant contribution to world thorium and the rare earth production. This paper, presented earlier in an abbreviated form (Goode, 2012), is intended to present as much of the information that is available."

Jan 1, 2012

By A. Tylczak, C. Shook, A. Doogan-Smith, S. Loif, B. Hilscher, P. Nayak

"This paper discusses how to effectively conduct energy efficiency studies during the design of new mineral processing plants and plant expansions. Energy management studies for new plants are ideally conducted as part of the feasibility study, but can also be done at the detailed design stage prior to the purchasing of equipment. Energy management engineers work as part of the mineral processing plant design team.Such studies usually result in energy savings of approximately 3-8% of the predicted plant’s energy consumption and energy demand. Potential cost savings can be significant. A variety of mineral processing systems – crushing/grinding, pumping, materials handling, fans/blowers, compressed air, and others – are assessed within this study.Energy Management Information System (EMIS) studies can also be performed for the new plant or plant expansion, as an independent study. EMIS can be incorporated into the electrical and controls design of the plant.Most Canadian Utility companies fund new plant design studies and provide financial incentives based on the predicted energy savings and incremental cost of the more energy-efficient design. A new plant energy efficiency study improves the potential for energy reduction because only the incremental equipment cost is included in the project return-on-investment calculation. After the design and construction phases, energy efficiency projects must justify the entire cost of the upgrade, which is significantly higher than the incremental cost alone.This paper outlines the major steps of a new plant/plant expansion energy efficiency study, the available utility company incentives, and the areas yielding the largest potential energy savings.IntroductionThis paper discusses energy efficiency studies and energy management systems with regards to mining operations. Energy management refers to the systems of monitoring, analyzing, and optimizing energy usage within a facility. It includes energy efficiency optimization of the initial plant design as well as the implementation of an Energy Management System (EnMS) and Energy Management Information System (EMIS) for optimizing energy usage over the lifetime of the facility. An EnMS is the organizational framework and procedures for managing energy use; an EMIS is the system of monitoring, reporting, and tracking process energy use against targets."

Jan 1, 2016

By Allen Chung, John Twomey, Christopher J. Greet

"It is widely accepted that the type of grinding media has an impact on the grinding chemistry and subsequent flotation behaviour of the sulphide minerals being separated. There are countless laboratory investigations demonstrating that inert grinding media produces more oxidising pulp potentials, reduced levels of grinding media corrosion products and superior concentrate grades and valuable metal recoveries. However, taking these results to industrial scale has proven difficult.Work conducted at the Ernest Henry Mine, in north western Queensland, Australia, at laboratory and pilot plant scale clearly indicated that using a high chrome grinding media resulted in significant improvements in both copper and gold recoveries. However, advancing this work to plant trial represented considerable financial and technical risk to the mine.This paper provides details of the protocol developed and used during the high chrome grinding media plant trial. It describes the test regime employed to measure changes in pulp chemistry, and the statistical methodology utilised to interpret the results. The work also highlighted the need for close cooperation between the metallurgists on site and the researchers conducting the trial.To date, the trial has produced excellent results: indicating that the copper recovery has improved by about 2 percent. The successful application of high chrome grinding media to the Ernest Henry ore has increased metal value by $18.7 million USD per annum based on current spot price for copper.INTRODUCTIONTheoryThe application of electrochemically inert grinding media to mineral systems has been extensively studied (Table 1). Broadly, these studies indicate that most sulphide minerals are more noble than the grinding media used during comminution. Therefore, the sulphide minerals are cathodic with respect to the forged steel grinding media, and the following reactions apply:"

Jan 1, 2011

By D. Richardson

Presentation Objectives ?Demonstrate the utility of 3D modelling for visualizing exploration data ?Demonstrate the target generation ability of 3D model query methods Exploration Criteria -Example Given the Geology of Sudbury What Are Our Exploration Criteria? (selected examples) ?Geometry ?Trends ?Lithology ?Proximity to Sulphides ?Length and Grade of Anomalous Mineralization ?Distance from Footwall In Addition ?Geophysical Criteria ?Economic Criteria ?Amount of Available Space ? Depth

May 1, 2006

By G. J. Knighton

Introduction The Sullivan concentrator treats the complex lead-zinc-iron ore from the Sullivan mine of the Consolidated Mining and Smelting Company of Canada, Limited, to make a lead and a zinc concentrate for its metallurgical plants at Trail. Three miles separate the mine and mill, which are situated near the town of Kimberley, in the East Kootenay district of British Columbia. The orebody consists typically of banded sulphides, mainly galena, sphalerite, pyrrhotite, and pyrite. Important factors in the concentration of the ore are its exceedingly complex and its high specific gravity. It should be remembered throughout the paper that results and figures are based on Consolidated's experience with the Sullivan ore. The present mill feed rate is 8,500 dry tons of ore per 24 hours, for an operating week of five and a half days. Grinding and classification of the ore are carried out in three stages and, in addition, there is a re-grind section which re-treats the zinc middling. It is the purpose of this paper to discuss the classification in the various stages and to give the results o comparative tests which have been carried out for the purpose of improving operations in the mill. The Primary stage consists of six units, each made up of a ball-mill and classifier (see accompanying flow-sheet). Four units operate in open circuit and two in closed circuit. The secondary stage consists of eight ball-mills operating in closed circuit with twenty-one classifiers. In the Tertiary stage are two ball-mills in closed circuit with eight classifiers. The re-treatment section for re-grinding the zinc middling comprises one ball-mill in closed circuit with two classifiers.

Jan 1, 1947

By D. K. Matlock, D. J. Hamre, J. G. Speer

Ultrafine ferrite (UFF) grains may be produced in surface layers of plate steels using controlled intermediate cooling followed by deformation. Experiments were conducted using a 0.12 C - 1.26 Mn steel on a Gleeble 1500 hot deformation simulator. Taguchi designed experiments were used to evaluate prior austenite grain size, intermediate cooling rate, intermediate cooling temperature, intermediate hold time and amount of reduction in order to observe the effects of variables and their interactions on the final microstructure while minimizing the number of required test runs. Evaluation of resulting microstructures and mechanical properties revealed a preferred thermal and mechanical history for developing ultrafine microstructures in surface layers of plate steels. Application of the fundamental concepts of phase transformations to industrial plate rolling is considered.

Jan 1, 2004