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By E. E. Carpenter

(San Francisco Meeting, September, 1915) BELIEVING that the results accomplished in the mill of the Churchill Milling Co., Wonder, Nev., during the fiscal year ended Sept. 30, 1914, will be of interest, I am presenting the more prominent facts and figures showing the progress made in treating this ore with especial reference to tonnage, supplies, costs, and extractions. The mill is situated at Wonder, Nev., in the Wonder mining district, 55 miles east from Fallon, Nev., the nearest railroad point. All supplies are hauled this distance by freight teams, this method of transportation having been found more reliable for continuous service than trucks, the price paid for hauling being slightly under one cent per pound. In this mill are treated the ores of the Nevada Wonder Mining Co. ,

Jan 6, 1915

By Michael J. Virnig, Keith E. Weerts

The development of heap leach technology for the treatment of low grade gold and silver ores has led to a boom in gold production in the Western United States in the last 15 years. The heap leaching process consists of stacking the mined ore on a specially prepared leach pad followed by leaching with dilute alkaline cyanide solution. Depending on the nature of the ore, it may require crushing and/or agglomeration prior to stacking on the leach pad. As the dilute alkaline cyanide solution migrates down through the stacked ore, the precious metal values along with a portion of the base metal values present in the ore are dissolved to give a pregnant leach solution which is collected at the base of the stacked ore. The precious metal values are then recovered by zinc precipitation or by adsorption on activated carbon. Once all of the economic metal values have been leached from the ore, the spent heap leach pad, the leached materials, and associated process solutions must be decomissioned. Decommissioning requires that the spent heap leach pad along with the leached materials and process solution be treated to reduce the concentration of the residual cyanide, base metal cyanide complexes, and other anionic metal species to levels where they no longer represent a long tenn liability for the environment and the operator. The levels to which these components must be reduced is dependent upon the applicable water quality standards as determined by the responsible federal, state, and local agencies. As environmental awareness has grown, these standards have become increasingly stringent. A number of treatment options have been developed for the de-toxification of the process residues. These include natural degradation which incorporates bio-degradation, fresh water rinsing, alkaline chlorination, hydrogen peroxide, and sulfur dioxide/air. Each of these options has been reviewed with regard to relative effectiveness, generation of hazardous by­products, reagent handling considerations, relative costs, and time requirements by Denton, Iverson, and Gosling I. As an outgrowth of the program to develop Henkel's guanidine based gold extractants, COGNIS, Inc., the environmental ann of Henkel, has developed the CyanoMet R process for the extraction and concentration of the various cyanide and anionic metal species from the dilute aqueous alkaline solutions generated during the process of detoxifying spent heap leach pads. This paper describes the CyanoMet R process, its application to three different feed solutions, and treatment of the concentrate generated by the process.

Jan 1, 1993

By C James Dahn

A new generation of high performance and high density ammonium nitrate prills have been developed. These cycled "prills" offer significant improvement in ANFO mixing time, detonation velocity performance, and heaving capabilities. In addition, their safety characteristics are better than standard ANFO explosives.

Jan 1, 1980

By R Fanni, D Reid, M Kulessa

Recent updates to Australian industry guidelines emphasise the importance of the assessment of liquefaction potential of tailings. This includes assessment of the cyclic liquefaction potential, and the post-seismic strength of tailings expected to undergo strength loss from seismic loading. Despite this increase in focus, a relatively small number of Australian tailings appear to have been characterised through cyclic and post-cyclic testing. This paper presents the cyclic characterisation of four Australian tailings, consisting of iron ore, lateritic nickel, vanadium and bauxite residue. Material was obtained either from surficial tube sampling or through remoulding samples in the laboratory from slurries. Testing consisted of monotonic, cyclic and post-cyclic tests for each material. For three of the materials, laboratory-scale shear vane testing was also performed to provide a comparison to post-cyclic strengths from direct simple shear.The results indicated cyclic resistances consistent with the results of other tailings presented in the literature. The lateritic nickel tailings provided the greatest cyclic resistance of the four materials tested, followed by the vanadium tailings. This was somewhat consistent with expectations for material behaviour based on index properties. Post-cyclic strengths were seen to decrease as cyclic strains increased, consistent with typical observations in the literature. Following significant cyclic straining, in some instances the post-cyclic strengths approached those obtained through residual shear vane testing. This provides further insight into the strain-dependent nature of post-cyclic strengths for some materials. The implications of these observations on the post-seismic stability condition are discussed.CITATION:Reid, D, Fanni, R and Kulessa, M, 2015. Cyclic and post-cyclic behaviour of four Australian tailings, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 207–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Paul Doherty

Expansion of the global piling industry has been coupled with significant research efforts investigating the mechanisms controlling pile capacity. Static pile design has transitioned from total stress approaches toward effective stress design, with associated improvements in predicting pile performance. As a result, the available literature is heavily skewed toward static capacity prediction. However, when considering piles offshore, the majority of loading is not static but highly variable and cyclic in nature. This paper outlines the additional factors that require consideration for cyclic pile design, including elevated loading rates, cyclic displacements and capacity degradation. A review of the literature identified a number of cyclic pile testing programs which are collated in this paper. General trends are established through comparison of the tests within the database and the conditions where cyclic loading is most likely to be a concern are identified. In particular, loading conditions which involve full plastic shear reversals are seen to cause the most extreme cyclic damage, with the degraded capacity as low as 31% of the precyclic static capacity. The underlying mechanisms which can result in cyclic damage are explored, with particular attention given to the pore pressure response, radial stresses, shear transfer and particle reorientation.

Jan 1, 2009

By Fabian Kirsch

Cyclic behaviour of axially loaded piles has been an issue since studies revealed that the capability to transfer skin friction into the ground is highly depending on the level and the number of load cycles the pile is subjected. It has been shown that degradation of skin friction due to axial cyclic loading leads to accumulating displacements and a severe reduction in pile capacity. In Germany the DIN 1054 as well as the Recommendations of the Working Group 2.1 ?Piles? of the German Geotechnical Society (EA-Pfähle) require the consideration of cyclic loading for the assessment of both the displacements and the capacity. Up to now no broadly accepted design method exists, which enables the engineer to give a reliable judgement on the pile capacity under axial cyclic loading and the displacements respectively. Instead numerous design charts make it possible to distinguish between stable and instable loading levels in order to ensure a design on the safe side. A newly developed design approach based on engineering models is presented which delivers a calculation algorithm for the remaining axial pile capacity after a defined number of load cycles to allow for the analysis of stability of the foundation. Furthermore the computation of accumulating displacements is made possible. The results are verified with pile load tests undertaken at Dunkirk, France and showed that the axial capacity after cyclic loading calculated with the newly developed design approach predicts actual capacity with an accuracy of ±20%.

Jan 1, 2011

By Yazen Khasawneh, Osvaldo P. M. Vitali, Mohammad Nassim

Wind turbines are subjected to complex form of cyclic loadings with variable amplitudes and frequencies. The cyclic loading and the accumulation of plastic strains with the number of cycles will result in degradation of the foundation soil stiffness. The foundation stiffness degradation will result in a shift (reduction) of the fundamental frequency of the wind turbine. Although this issue is recognized in the guidelines for wind turbines foundation design, no specific provisions are provided in the guidelines to consider the long-term stiffness degradation. In this paper, a practical procedure to consider the long-term cyclic loading effects on the stiffness of wind turbine foundations in cohesive soil is proposed. The procedure is based on 3D FEM modeling and reliable empirical methods to estimate the stiffness degradation due to the cyclic loading. Using the proposed procedure, the long-term performance of the P&H tensionless pier foundation with and without a reinforcing collar at the top of the pier is assessed. The numerical results demonstrated that the long-term performance of the P&H tensionless pier foundation with a reinforcing collar at the top of the pier is outstanding with negligible long-term degradation of the foundation stiffness.

Sep 8, 2021

By Dietmar Eifler, Marcus Klein, Hendrik Kramer

Conventional methods to characterize the fatigue behavior of metallic materials are very time and cost consuming. That is why the new short-time procedure PHYBALCHT was developed at the Institute of Materials Science and Engineering at the University of Kaiserslautern. This innovative method requires only a planar material surface to perform cyclic force-controlled hardness indentation tests. To characterize the cyclic elastic-plastic behavior of the test material the change of the force-indentation-depth-hysteresis is plotted versus the number of indentation cycles. In accordance to the plastic strain amplitude the indentation-depth width of the hysteresis loop is measured at half minimum force and is called plastic indentation-depth amplitude. Its change as a function of the number of cycles of indentation can be described by power-laws. One of these power-laws contains the hardening-exponentCHT eII, which correlates very well with the amount of cyclic hardening in conventional constant amplitude fatigue tests. To identify heat-treatment-parameters and SAE 52100 TRIP-alloys with high hardening rates as well as their damage tolerance the PHYBALCHT- and PHYBALLIT-method were used. One modified SAE 52100 TRIP-alloy was investigated in detail. The fatigue behavior and the cyclic hardening of the selected SAE 52100 TRIP-alloy was investigated and compared with conventional SAE 52100. Conventional stress-controlled fatigue tests were performed on a servo-hydraulic test system with a frequency of 5 Hz and a load ratio of R = -1. Different rates of cyclic hardening were identified. The size of the nonmetallic inclusions leading to crack initiation and the number of cycles to failure were used to evaluate differences in the damage tolerance capability.

Jan 1, 2015

By V. V. Pankov, W. R. Chen, L. R. Zhao

Diffusion nickel aluminide and overlay NiCrAlY coatings were deposited on single crystal Ni-base superalloy CMSX-4 substrate using the chemical vapour deposition and cathodic arc evaporation techniques, respectively. The NiCrAlY coating underwent a post-deposition heat treatment in an argon atmosphere at 1100°C for 2 hours. All the coated specimens were subjected to furnace cyclic oxidation testing at 1000°C up to 1500 one-hour cycles. The morphology, elemental composition and phase constituents of the oxide scales formed on the coating surface were analyzed using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. It was observed that the diffusion aluminide coating experienced accelerated weight gain at an early stage of the test (150-400 cycles), whereas the overlay NiCrAlY coating fabricated by cathodic arc evaporation maintained steady-state weight gain throughout the entire 1500 cycle test duration. This difference in oxidation behaviour between the two types of coatings is attributed to the early development of nickel-aluminum spinel on the surface of the diffusion aluminide coating, in contrast to the stable aluminum oxide scale formed on the overlay NiCrAlY coating during cyclic oxidation testing.

Jan 1, 2015

Stellite-6 coatings were formulated on two Ni-base superalloys, namely Superni 75 and Superni 600, by a shrouded plasma-spray process, and the oxidation behaviour of these coatings has been investigated in air and in an aggressive environment of Na2SO4- 60%V2O5. Accelerated oxidation tests were conducted in a silicon-carbide tube furnace under cyclic conditions at an elevated temperature of 900°C for 50 cycles. Each cycle consisted of 1 h heating and 20 min cooling in air. A thermogravimetric technique was used to approximate the oxidation kinetics. The corrosion scales were characterised by XRD, SEM/EDAX and EPMA analysis. It has been observed that the coatings nearly followed the parabolic rate law of oxidation. Overall weight gain conceived in air was just 51% of that in the aggressive environment in the case of coated Superni 75, whereas in case of coated Superni 600, the cumulative weight gain in air was found to be one-third of that in the Na2SO4-60% V2O5 atmosphere. Furthermore, the coating showed very good adherence to both of the substrates during the course of air oxidation, whereas some superficial cracks were observed near the edges of the specimens during the molten salt induced oxidation. XRD analysis revealed the presence of phase-like CoO, CoCr2O4 and Cr2O3 in the oxide scales, which are reported be protective against high-temperature oxidation. The XRD results were further supported by SEM/EDAX and EPMA.

Jan 1, 2005

By W. Choi

The present study revealed that the bioleachability of a chalcopyrite flotation concentrate is influenced by the semiconductor properties of CuFeS2. The overall reaction of biooxidation,

Jan 1, 1991

By C. -S. Jiang

In most copper refineries, addition agents are added at predetermined rates with no further monitoring of their activity or concentration in the electrolyte. Increasingly stringent cathode quality requirements, and a desire for better process control in tankhouse operations, have recently directed a number of refineries to search for a better addition agent control strategy. Extensive development work has been carried out at the Noranda Technology Centre for the monitor in of glue and thiourea in copper refinery electrolyte using cyclic voltammetry (cv~. Data from both synthetrc and commercial electrolytes are presented, showing the ability of CV to produce reliable and easily identifiable fingerprints of addition agent concentrations in copper refinery electrolyte.

Jan 1, 1991

By Roy A. Grancher

CYCLING WITH CEMENT "THE WHEEL IS COME FULL CIRCLE" Shakespeare's King Lear Act V, Scene 3, Line 176 The time clock of the cement industry has been turned back to the early 1950s. After the trials and tribulations of the decade of the Sixties, the hands now stand where they did just over twenty years ago. Cement shipments have steadily increased, with a record 419 million barrel level (78.8 million tons) being reached last year. Plants are operating at average utilization rates in excess of 85 percent of rated capacity. The spread between supply and demand has narrowed to where a definite shortage of cement now exists within the industry. The notable and unfortunate difference between the two periods however is that, back then, cement's returns were a respectable 14 to 18 percent, whereas today they stand at less than half those levels. Insufficient return forms the present foundation of the U.S. cement industry. This lack is destined to have a cumulative effect. Just as the industry's balance between supply and demand is returning to favorable proportions, promising a period that has historically and now should generate those profit levels required to modernize and provide for capacity addition, cement instead finds itself frozen by federal price controls into the semi-depressed condition that has existed for over a decade and from which it was just starting to emerge. Capital is not attracted to continued low returns, and increasingly restrictive pollution control measures are necessitating great non-productive expenditures be made as definite costs to stay in business. Even a clouded crystal ball would reveal that additional cement plant closings can be expected.

Jan 1, 1972

By R. N. Murarka

"Hydrocyclone modelling and selection procedure is illustrated. Computerized procedure for hydrocyclone cut size determination for grinding and non-grinding applications is described.A standard procedure for evaluating operating hydrocyclones is described in detail. Many case studies are illustrated comparing actual plant performance with the computer simulation output in terms of overflow product size distributions.INTRODUCTION Cyclones are widely used for applications such as: close circuit grinding, backfill, tailings and dewatering. Normally, cyclones are used for very fine separations where screens are not suitable or too expensive. Figure 1 shows the separation size range of various classifying devices. Cyclones are popular because of their low capital and operating cost. Cyclone selection procedure for different applications depends on the amount of information available on the cyclone feed slurry characteristics. Closed circuit grinding applications will be discussed in detail in this paper. The Cut Size:The size of the material in the feed which reports 50% to each product stream (i.e. underflow and overflow), after correcting for the feed solids by-passing with the underflow liquid, is termed the cut size or ""d50c"". This is often used as the criterion and the basis for cyclone design.When the corrected recovery to underflow of each mesh size in the feed is plotted against the geometric mean size in microns on a log scale, the micron size corresponding to 50% recovery is the d50c size."

Jan 1, 1992

By D. A. Dahlstrom

Although the liquid-solid cyclone is a relatively recent innovation in the field of coal preparation, various authors have already indicated three distinct applications to operations encountered in the modern tipple. Driessen's articles and work at the Dutch State Mines exhibited its possibilities in the beneficiation of fine coal with apparently high efficiencies down to the 200-mesh fraction. 1 2 3 4 Other publications point out its use as a recoverer, thickener, and preliminary dewatering agent of fine coal which in too many cases is being wasted due largely to former high operating cost limitations 5 6. Finally, certain authors have emphasized the practicability of applying the cyclone to the elimination of coarse and fine solids from water slurries in the tipple in order to produce a water suitable for recycle purposes containing only minute particles far below the 200-mesh size.6 This would result in a closed water system for many cases, with its accompanying economic and operating advantages to locations where water quantity and quality problems are severe; better operation of washing equipment using a consistent water devoid of injurious fine particles; lowered maintenance costs due to the lesser abrasion resulting when the fine abraiding particles are removed; and the greater ease of disposing of refuse streams of reduced volume containing greater percentages of solids.

Jan 1, 1949

By P. R. Taylor

Recent research by the investigators has evaluated the oxidation roasting of refractory gold concentrates in the presence of hydrated lime. (Taylor, 1990, 1991, 1992, 1993). These results have indicated that it may be possible to roast concentrates in such a way as to contain nearly all of the sulfur and arsenic in the roaster calcine and that cyanidation may be possible. To further evaluate the behavior of this type of roasting system a laboratory cyclone reactor was built and operated using pyrite and hydrated lime as a .model system. Approximately 50 years ago, the principle of cyclone firing entered practical boiler construction. The appeal of the cyclone configuration was that it afforded the flash combustion process greater efficiency due to turbulence-induced increased mass transfer, heat exchange, and combustion rates.

Jan 1, 1994

By James K. Kindig

Solvent extraction as a method of purifying and concentrating metal values from solution has become a standard hydrometallurgical operation for recovery of both uranium and vanadium, and within the past two years it has been put into operation in a commercial plant for recovery of copper from leach solutions. In this first full scale solvent extraction plant for recovery of copper operated by Ranchers Exploration and Development Corporation near Miami, Arizona, a kerosene solution of an organic compound, LIX-64® is used to selectively extract the copper from the dilute acidic copper sulfate leach liquor obtained from heap leach operations. The copper is back extracted from the solvent into a stripping solution which is fed to an electrolysis circuit producing cathode copper for sale.

Jan 1, 1970

By Norman A. Jull

"IntroductionThe scope of this paper is intended to deal mainly with cyclones in grinding circuits. However, the section on Cyclone Equipment, contains more general descriptions, to cover most of the cyclones used in mineral separation plants.Cyclones as heavy media separation vessels are discussed by Mark Freberg (this volume). Their use in tailings deslirning is discussed by P.C. Lighthall, eta/. (this volume).Cyclone EquipmentCyclone TerminologyApexObviously, the apex of a cone is the smallest end. However, with cyclones the term is usually used for the fitting which is attached there to control discharge of the underflow stream.Note that the cyclone need not be so mounted that the apex is the lowest point, although that is the most common method. Keeping the apex below the rest of the cyclone helps avoid plugging when the underflow contains very large particles and the tonnage of underflow solids can fluctuate.Various devices for adjusting apex diameter or otherwise controlling the underflow are discussed later under ""Cyclone Construction"".BypassingThe transport of a portion of feed slurry directly to underflow so that classification is bypassed by that portion of feed.This action is fundamental in any hydraulic classification, whether gravity or centrifugal, because the large particles going to underflow have some void volume between them, which remains filled with feed slurry.D50By definition, D50 is that particle size which has an equal probability of going to overflow or to underflow.It is calculated by drawing a curve of recovery vs particle size and noting the size at which 500Jo recovery occurs.This may be done equally with corrected or with gross recovery (see below) and the resulting value should therefore be identified as d50c (corrected d50) or as d500 (gross d50).Note also that it is common in industry practice to plot size analysis data on the retained size rather than on the average of passing and retained (the middle of the size band). To portray sizing alone it makes no difference, but to read a D50 value off a curve of corrected or gross recoveries, it is essential to plot those values on the average size of each band."

Jan 1, 1989

By E. S. Allen, P. R. Kruesi, J. L. Lake

An electrochemical process is described for converting concentrates of base-metal sulphides to the corresponding pure metals and elemental sulphur. The application of the process to chalcopyrite is discussed. The process is also of potential interest in processing copper-nickel sulphides, and laboratory data concerning this potential are presented. The process creates neither air nor water pollution.

Jan 1, 1973

By Ross R. Bhappu

Anticipating a major power cost increase in 1990, Cyprus Copper Company decided to modernize the Miami Smelter at a cost of $92.5 million. The modernization project included the addition of an Isasmelt vessel for use as the primary copper smelter and the modification of the existing electric furnace to a slaglmatte separating vessel. The project was completed in June of 1992 and is currently operating at close to its design capacity. This paper provides a summary of the decision making process, a description of the project, a summary of start-up problems and solutions and the current status of the smelter operation.

Jan 1, 1994