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By Ian Orford, Ken L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper updates the principal author’s earlier publication, “Crushing Plant Design and Layout Considerations” (SME Mineral Processing Plant Design, Practise, and Control, 2002). It reviews the latest primary crushing and large cone crusher designs. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year.INTRODUCTIONAre larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? The principal author’s previous paper in the year 2002 on ""Crushing Plant Design and Layout Considerations"" provided a detailed design and layout review for the design of primary and fine crushing (Secondary, Tertiary, Quaternary) mineral processing facilities. Some of the conclusions in this previous paper had predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available.The rock size reduction process, from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized into four (4) stages:• Stage 1: Mining ( Rock Breakage and Fragmentation)• Stage 2: Pre-Screening (Scalping)• Stage 3: Primary Crushing• Stage 4: Fine Crushing (Secondary, Tertiary and Quaternary; the crushers used in this stage are identified by the titles which usage has conferred on them)Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once a project's design criteria and the mine plan has been established, the actual circuit's utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stake holders in the selection of the final comminution circuit and both departments should be familiar with and contribute to the design of the circuit."

Jan 1, 2016

By Larry J. Hughes

Ground-based electrical geophysical techniques have be valuable for three indirect exploration strategies: "tracer" sulfide mineralization, 2) mapping structure with or controlling mineralization, and 3) mapping proven to 1) mapping? associated alteration zones. When sulfide mineralization is associated with gold, it often can be mapped using induced polarization (IP). This technique can detect pyrite in amounts as small as 0.2% by volume, and in some cases can distinguish pyrite from anomalies due to graphite and clays. A case history illustrates mapping sulfides in a shear zone. Structure and alteration mapping are often the domain of controlled source audio-frequency magnetotellurics (CSAMT) due to the superior lateral resolution and depth penetration of this technique. Typical CSAMT targets include silicified sediments and volcanics, faults, brecciated zones, argillic alteration, clay and graphite horizons, and certain lithologies. Examples of mapping silicification and mapping epithermal alteration are presented in CSAMT case histories over Cannon mine in Washington and Hishikari mine in southern Japan. In our experience, four things are needed to use geophysics effectively in precious metals exploration. First, the explorationist must correctly identify the exploration stage at which the geophysics is most useful. Second, the explorationist must clearly define the types of "tracer" mineralization, host geology, or alteration which need to be defined by the geophysics. Third, the right electrical technique needs to be applied to the problem to provide the best chance of success. Fourth, the explorationist must be willing to commit adequate finances to do the geophysics properly. With careful adherence to these principles, geophysics can greatly enhance exploration success while reducing the total cost of exploration.

Jan 1, 1989

By John C. Machisak

The Nation's mining and quarrying industries have again met the annual challenge to their ingenuity--that of reducing disabling work injuries among their employees. The effectiveness of management in facing this problem and in meeting this responsibility from the results of the 1961 National Safety Competition. Three hundred ninety-three or 45.3 percent of the mines and quarries participating in the competition established a new record number of participants operating throughout the competition year without a disabling work injury. Another record established in the 1961 contest was the number of participants (868) enrolled in the competition. This annual safety competition was begun in 1925 and is conducted by the Bureau of Mines, U.S. Department of the Interior. It provides for six bronze Sentinels of safety trophies which are awarded each year to the winning participant in each group. Since its inception, the competition has exerted a strong influence in the field of safety promotion. The statistical record of its accomplishments over the years gives strong support to the theory that well-organized and well-administered safety programs are effective tools to be used to reduce the number of disabling work injuries. It stimulates and holds the interest of employees and management in accident prevention. Because of this, mines and quarries participating in the contest have a more favorable safety record than those operations not enrolled.

Jan 1, 1963

By John C. Machisak

The Nation's mining and quarrying industries have again met the annual challenge to their ingenuity--that of reducing disabling work injuries among their employees. The effectiveness of management in facing this problem and in meeting this responsibility is evident from the results of the 1961 National Safety Competition. Three hundred ninety-three or 45.3 percent of the mines and quarries participating in the competition established a new record number of participants operating throughout the competition year without a disabling work injury. Another record established in the 1961 contest was the number of participants (868) enrolled in the competition. This annual safety competition was begun in 1925 and is conducted by the Bureau of Mines, U.S. Department of the Interior. It provides for six bronze Sentinels of safety trophies which are awarded each year to the winning participant in each group. Since its inception, the competition has exerted a strong influence in the field of safety promotion. The statistical record of its accomplishments over the years gives strong support to the theory that well-organized and well- administered safety programs are effective tools to be used to reduce the number of disabling work injuries. It stimulates and holds the interest of employees and management in accident prevention. Because of this, mines and quarries participating in the contest have a more favorable safety record than those operations not enrolled.

Jan 1, 1963

By T. P. Meloy

Economic constraints require that the optimum mineral processing circuit be chosen for a given ore and then the circuit be optimized. Meloy (1983) developed a general methodology for finding the best circuit for a given ore. This analysis, however, did not specify a way to optimize the best circuit once it has been found. To optimize a given circuit, it is necessary to find the optimum set points for each unit operation in the circuit. Developed in this paper is a simple, general equation which, when applied, defines the optimum separation set point for the maximum mineral grade. This general equation, Equation (4), applies not only to simple ores, but also to complex ores containing variable and locked particles. Currently, the optimum set point can be calculated only for heavy media and cyclone circuits, because they are the only unit operations for which the necessary data has been measured.

Jan 1, 1984

By John Marsden, John Mansanti, Jim Arnold, Mike Gleason

DOUG HALBE: We're not quite to the end of our session, but we're close. We've had a lot of fun with some of these spill ideas. But these are serious problems, and I think we might be able to benefit by continuing to compile these. Several years ago, the metallurgists at the various operations of Gold Fields Mining Company had a newsletter that came out every two months for several years. This publication consisted of short articles by the staff at the various operations, plus a few others, on problems they'd had and how they solved them. One very useful article, "Things We'd Have Done Differently at Chimney Creek," was written shortly after start-up. John Marsden was the editor and John Mansanti contributed to it, as did Jim Arnold (our distinguished co-chair) and Mike Gleason. I would be interested, with the permission of the audience, in editing that article to make it a little bit less abrasive and putting it into the record here. I think it's a useful SME function to maintain a list of things we've done wrong in plant design, things we don't want to do again. If we have another open session in the future, would others be willing, even anonymously, to contribute, bring slides, and say "Hey, look at the goofs we made?" [laughter, followed by support from the audience] Okay, we'll plan on that. And we'll try to include the Chimney Creek list in the transcript of this session-perhaps edited a bit.

Jan 1, 1998

By A. J. DeArdo

Linepipe steels have come a long way in the past forty years. In fact, modern, high strength steels for large diameter linepipe applications represent one of the seminal accomplishments in metallurgy of the past half-century. The synergy of advanced steelmaking, alloy design including microalloying, hot rolling, and interrupted accelerated cooling has led to the marvelous steels being used today. The drive for higher performance pipelines has been motivated by the energy sector of our global economy who wanted both higher throughput capacity, i.e., larger diameters and higher pressures, and lower material cost, i.e., relatively thinner gauge wall thicknesses. These requirements led to new steels with higher strengths, better toughness and improved weldability. The goal of this paper is to trace the evolution of linepipe steels from the X60 grades of the small diameter pipelines of the 1960s to the (X80 - X120) grades used in the large diameter pipelines of today. The metallurgical triumphs permitting this success story, e.g., clean steel practices, controlled rolling, microalloying with Nb, and using IAC to obtain low temperature transformation products, will be highlighted and discussed.

Jan 1, 2005

By S. Banisi, A. R. Hasankhoei, A. R. Ghasemi, E. Razi, G. A. Parsapour

At the pelletizing plant of the Gol-E-Gohar mining and industrial company two parallel dry closed grinding circuits, each with the average throughput of 300 t/h, are used. Each grinding circuit consists of a burner, a dry ball mill (6.2 m×13 m) and an air separator. The ball mill consists of a 2 m-long drying and an 11 m-long grinding chambers. The iron ore concentrate is fed to the drying chamber by a feed chute. The first 1.35 m of the drying chamber consists of 56 flights in two rows to decrease the feed moisture from 5% to below 0.2% and the rest of dryer chamber consists of deflectors to pass the material to the grinding chamber. It was found that when the feed moisture content increased from 1.3% to 3.5%, the throughput decreased by 12% (35 t/h) indicating a low performance of the dryer. Monitoring the wear rate of flights for a period of 12 months showed that the first 0.8 m length of the flights length did not experience any wear. This means that about 59% of flights do not contribute in material distribution and drying. A DEM simulation of feed chute and the drying chamber demonstrated that due to the inappropriate design of feed chute most of materials do not get in touch with the first 0.8 m length of the drying chamber. To overcome this problem, various feed chute designs with different geometries were simulated by the KMPCDEM© software. With the aim of arriving at a proper material trajectory, where the total length of the flights are used, a new feed chute was selected. The simulation results indicated that if the height of the flights is increased from 1.60 to 2.26 m and the slope is increased from 45 to 48 degrees the material arrive at the first 0.48 m of drying chamber. In this manner, the unused part of the drying chamber decreases from 59% to 36% of the length. After installation of the new feed chute, during a period of three months the throughput increased by 36 t/h.

Jan 1, 2018

By Shailin Lalloo, Allan B. Nesbitt

"Gravity separation by centrifugal equipment, particularly in the mineral processing industry is a novel approach of optimising product recovery. The manufacture and sale of centrifugal equipment by recently established companies is now beginning to have a significant impact on the industry. Some benefits of operating at increased gravity include: reduced environmental issues, a shorter lead time, lower capital cost and improved recoveries of elemental mineral before entering the grinding circuit.Of topical discussion is the use of centrifugal separators for the recovery of less valuable minerals that will form a greater proportion of the feed compared to traditional scalping circuits where the gold content is extremely low. This ultimately results in the centrifugal system having to have a greater mass pull. In addition, the relative density difference between gangue and valuable mineral is likely to be less and therefore modelling and optimisation of this separation process will be necessary. Some researchers have muted using fluidisation models to model the forces present in the separation zone of a centrifugal separator2. It is not unusual for the manufactures of centrifugal separation equipment to use fluidisation terminology to describe what happens in the separation zone. Most fluidisation models are based on the empirical/classic relationship between superficial fluid velocity and voidage postulated by Richardson and Zaki. However, no researcher has proved the effectiveness of this relationship in an increased gravity Environment."

Jan 1, 2003

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By John E. Pahlman

The Bureau of Mines has conducted research on a dual leaching method that offers the potential for the economic recovery of the silver, as well as of the manganese, contained in some domestic manganiferous silver deposits. The method consists of an initial leach of manganese with aqueous sulfur dioxide (S02) followed first by a neutralization rinse, and then by a second leach with cyanide solution for the extraction of silver. Refractory silver in these ores was either (1) intimately associated with the manganese, (2) chemically resistant to cyanide leaching, or (3) rendered inaccessible to cyanide leach solution by the surrounding manganese mineralization. Less than 10 pct of the silver was extracted when minus 2.5-plus 1.3-cm ore pieces were leached directly with cyanide. However, extractions of 25 to 82 pct of the silver and 65 to 96 pet of the manganese were attained in laboratory column-leach tests using the dual leaching method on equivalent-sized ore pieces from seven domestic deposits.

Jan 1, 1987

By A. N. Rogers

Jan 1, 1883

By C. H. Curtis

The valuable mineral content of the current feed to the Miami concentrator is as follows: copper, 0.7 pct total; molybdenum, 0.01. Flotation of this ore yields a sulphide concentrate containing: chalcocite, 44 pct; molybdenite, 0.5; pyrite, 50.0; insol, 5.5. A combination of potassium ethyl xanthate and pentasol amyl xanthate as collectors, and pine oil as frother, are used in this flotation. Rejection of pyrite is encouraged by holding the amount of collectors used to the minimum consistent with copper recovery and by operating at high alkalinity (equivalent to 0.35-0.40 lb CaO per ton solution of pH 11.0).

Jan 4, 1950

By J. T. Lapsley, I. I. Cornet, A. E. Flanigan, R. Hultgren, J. E. Dorn

With the greatly expanding use of magnesium during the war, it appeared necessary to the War Metallurgy Committee that procedures of heat treating common magnesium casting alloys be investigated systematically. Accordingly, the National Defense Research Committee of the Office of Scientific Research and Development placed a research contract with the University of California, supervised by the War Metallurgy Committee. Research on the solution heat treatment and aging of magnesium alloy AZg2, (formerly ASTM No. 17; also known as Dowmetal C or AM26o) which was done under "Restricted" Project NRC-2I, in 1942-1943, and reported in detail in a final report to the OSRD on September 3, 1943, is the basis of this paper, which has been released for publication by the OSRD. American experience with magnesium alloys prior to World War II was limited, although some of these alloys had been in commercial use since 1909. Requirements of the aircraft industry for light alloys made it imperative to understand and utilize the advantageous strength-weight properties of magnesium castings. Magnesium casting alloys are commonly solution heat- treated to increase their ultimate tensile strength and ductility; this treatment may be followed by an age hardening at elevated temperatures, which raises the tensile yield strength but diminishes the ductility. In the present investigation, AZp was studied to determine the effects on properties of various solution heat treatment and aging schedules. The principles of heat treatment of magnesium alloys are the same as for other non-ferrous alloys. The alloy studied, AZp, has a nominal composition of 9 pct aluminum, 2 pct zinc, and minor constituents. Fig I shows, by the projection of isothermal sections on the concentration plane, the solubility surface1 of the ternary magnesium-rich solid solutions as determined by X ray 'analysis. From this figure it may be seen that above approximately 375°C (707OF), AZp alloy is a single phase alloy at equilibrium; below this temperature the equilibrium condition is a two phase alloy. The beta constituent which precipitates from the solid solution exerts a hardening effect. Because the zinc concentration is only 2 pct, ancl because of its solubility relations, AZqz resembles a binary alloy of magnesium with aluminum. The solubility curve1 of Fig 2 shows how rapidly the solubility of the beta phase decreases with decreasing temperatures. Unlike many aluminum alloys, magnesium alloys do not age harden at room temperatures; precipitation hardening of AZ² alloy is performed at about 177°C (350°F). At this temperature about 3 pct aluminum

Jan 1, 1949

By L. M. Bigler, J. L. Dobra

With the passage of Mexico's Mining Law in 1992, the tax treaty with the US in the same year, and the passage of the North American Free Trade Agreement, gold mining for non-Mexican mining companies in Mexico has changed dramatically. The statutory changes have created an opportunity for non-Mexican precious metals' producers to own 100% of a Mexican gold concession. This paper examines the financial feasibility of a hypothetical gold mine and processing plant in Mexico. The analysis includes the operational consequences of the recent weakness of the peso, as well as tax and employment issues.

Jan 1, 1996

By C. M. Diaz, S. W. Marcuson

In the late 19th century, the discovery of rich nickel-copper sulfide ore bodies in Sudbury and the need for tonnage quantities of the metal to be used in nickel steel armor provided the foundation for establishing the Canadian nickel industry. For almost 50 years, International Nickel was the key player. In 1930, Falconbridge Nickel entered the field. These two companies remain the key Canadian nickel producers. This paper discusses the factors that have influenced the evolution of nickel smelting processes. The initial Sudbury ore smelting and nickel copper separation technologies were imported from abroad. It was only in 1937 that International Nickel established a process research laboratory in Copper Cliff The explosive post WW II industrial development created a strong demand for a broader variety of nickel products. For both International Nickel and Falconbridge, R&D became an essential business tool to succeed in the new market scenery. In the last few decades, new technologies were developed and commercialized to respond to the raising cost of energy, society pressing environmental concerns, the advent of nickel laterites as an important source of new metal, the incorporation of new nickel producers to the market, and, therefore, the need to increase productivity. Canada thus became an important exporter of technology. In this paper, the authors review this history with the objective of highlighting the forces that have triggered the most important changes in Canadian nickel smelting.

Jan 1, 2005

By C. Richard Tinsley

INTRODUCTION The economic analysis (Chapter 3), the engineering studies (Chapter 10), the credit structure (and the consequential funding sources) - Chapter 11, and the overall feasibility structure for any venture are all directed to determining one major decision element: How much and how certain is the reward for taking these risks? Risk assessment is a surprisingly weak area of analysis and is usually addressed in a checklist fashion. It is much preferable to deal within a risk system so that the inevitable tradeoffs among risks are correctly made. DEFINITION The first step toward risk definition must be to ascertain all of the risks to which a project or a company is exposed; otherwise one will remain ignorant of the possibility of a financially crippling loss until it occurs. (Carter and Crockford, 1974). However, simply stating what "risk" is can lead to debate. For example, risk could be (adapted from Vaughan, 1982): -the chance of a loss - uncertainty of loss -possibility of loss - uncertainty -dispersion of actual from expected results - probability of an outcome different from the one expected - possibility of an occurrence of an undesirable contingency -a condition in which a possibility of a loss exists. For the minerals industry financier, the last definition is probably the most appropriate. However, from a mineral company's point of view the definition might well include the possibility of not achieving the expected financial return. RISK CLASSIFICATION Risk identification will be readily agreed as the all-important first step. There are five major "branches" of risk classification. These are: -Statistical -Modellers -Checklist -Project Financing -Insurance The Statistical set discovered probability theory and any risk discussion soon deteriorates into a mathematical jungle (Megill, 1977; Hartman, 1976; Reutlinger, 1970; and Pouliquen, 1970).Their use of terminology tells its own story: coin toss (binomial distribution), gamblers' ruin, delphi (oracle) techniques, monte-carlo simulations, random walks, etcetera. These techniques inadequately represent the judgements necessary in an increasingly complicated and interrelated world. The risk Modellers have turned to the computer to handle these inter-relationships but soon find barriers because of "simultaneity". Certainly the computer has its uses to conduct various analyses (marketed as "sensitivity" analyses) but very often one finds that this involves changing one or two variables at a time, all other things being equal. Unfortunately, in a modern and complex world all other things do not remain equal. The statisticians will, no doubt, jump to their own defence by citing this

Jan 1, 1985

By M. Maldonado, J. A. Finch

"A flotation bank consists of a serial arrangement of cells. How to optimally operate a bank remains a challenge. This article reviews three strategies for optimizing bank performance: air profiling, mass-pull (froth velocity) profiling and Peak Air Recovery (PAR) profiling. These are all ways of manipulating the recovery profile down a bank, which may be the property being exploited. Mathematical analysis has shown that a flat cell-by-cell recovery profile maximizes the separation of two floatable minerals for a given target bank recovery when the relative floatability is constant down the bank. Available bank survey data is analyzed in respect to recovery profiling. Possible variations on recovery profile to minimize entrainment are discussed.INTRODUCTION Flotation is used to separate valuable minerals from each other and from gangue. To reach a target metallurgical performance, usually assessed in terms of concentrate grade and recovery, feed is passed through stages such as roughing, cleaning and scavenging. All these stages comprise serial arrangements of flotation cells known as banks, lines or rows. Although a bank is the simplest interconnection of cells in a circuit, i.e. the tails of one cell is the feed to the next cell down the bank, how to operate each flotation cell in a way that the whole bank performance is optimized remains a challenge. Significant efforts have been made towards understanding the effect of operating variables on the flotation performance of an isolated cell (Lynch et al., 1981; Finch and Dobby, 1990; Gorain et al., 1998). However in the case of banks the variables that can be manipulated increase with the number of cells in the bank and the problem of how to manipulate them to achieve optimum performance is difficult even disregarding variation in ore characteristics (Lynch et al., 1981, p. 16). In general, the more manipulated variables available the better for optimization purposes, however without clear guidance how to effectively use them it becomes an “embarrassment of riches”."

Jan 1, 2012

By Andrew Hyslop

IN our never ending search for new and better ways of underground mining, we find that transportation has had its share of new ideas in the past few years. The old and still effective method of track haulage has had some competition from rubber tired cars and belt conveyors, each of which has its own safety hazards which demand close scrutiny in any safety study. The use of shuttle cars, in particular, has introduced clearance hazards caused by the absence of the more or less positive guides formed by the rails of a track sys¬tem; likewise the requirement of greater clearance tends to increase roof hazards which we all know to be great enough with the best of methods. However, the subject of transportation hazards is too broad to be covered entirely in one paper, so I will confine myself to track methods which carry the preponderance of underground tonnage. I am quite sure that to this group it is an evident fact that haulage accidents are of major importance. However, to stress the point, it may be well to look at a few figures. Safety statistics can be quite boring and often are subject to question as to mathematical accuracy because of different

Jan 1, 1948

By N. J. Bolin

The Aitik copper mine is located in the north of Sweden and the concentrator at the mine started its operation in 1968 with a capacity of 2 Mton ore per year. Since then the operation has expanded several times, and today the capacity is 18 Mton ore per year. A new expansion plan was investigated in 2005, however the building of a new concentrator was found to be a better solution, giving a lower cost, a longer lifetime and more concentrates to the smelter at the coast. Several choices have been evaluated regarding the location of the concentrator?s crushing, grinding, dewatering, process control and water systems. The energy cost comparison has been an important factor when evaluating the various choices. The single most important decision has been in choosing the grinding system. Once again the fully autogenous grinding system, favoured by Boliden, has proven to be the best solution. The location of the mill, high and near the tailing pond, gives lower transportation costs for the ore and tailings, compared to other locations. A new water system will lower the pumping cost, give better control of water circulation to the plant and create fewer problems with permafrost in the tailings disposal area. Molybdenum recovery will be installed in the new plant using a separate circuit. A gold leaching plant was also investigated. Gold leaching is planned for the pyrite concentrate from the chalcopyrite/pyrite separation and the concentrate from the desulphurisation circuit that will be installed on the bulk flotation tailings.

Jan 1, 2014