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By A. Pavlidis

This paper investigates variations of lignite quality attributes with geostatistical methods. The study focuses on lignite from the Southern Field in the Greek province of West Macedonia. The targeted quality variable is the ash water-free content (AWF). A geostatistical model is constructed based on data from 480 drillholes (approximate drill hole spacing of 250m). For each drillhole, the vertical average of the AWF is calculated. The coarse-grained AWF is then modeled as the superposition of a trend surface and fluctuations. The spatial dependence of the fluctuations is modeled by means of the experimental variogram. Kriging estimators are used to determine the AWF values on a rectangular grid, and the uncertainty of the estimates is calculated. Implications of the analysis for the variability of the produced lignite are discussed, and recommendations for additional drilling are proposed.

Jan 1, 2006

By O. P. Arora, J. B. Darby, Paul A. Beck

LAVES and Wallbaum' reported that the phases occurring at the compositions TiFe, TiRu, and TiOs, which are stable over a wide range of temperatures and are separated from neighboring phases by wide two phase fields, have a CsC1-type ordered structure. For TiRu and TiOs, this was recently confirmed by C. B. Jordan.2 Recent results of Greenfield and Beck3 show that solid solutions with ruthenium of the body-centered-cubic elements vanadium and tantalum (and presumably also of colum-bium) in group Va of the periodic table undergo CsC1-type ordering. Although detailed phase diagrams for these systems are not yet available, it would appear that these ordered structures are separated from the neighboring body-centered-cubic solid solutions by relatively narrow two phase fields.

Jan 1, 1957

By R. R. Klimpel

This paper is a summary of the author's industrial experiences on the selection and optimization of flotation reagent schemes for the recovery of gold species. The trends given are a composite of data and experiences gained on 24 different gold ores from around the globe. The primary emphasis is on the benefits of matching the associated gold mineralogy to a reagent scheme most appropriate for that mineralogy. Two general categories are discussed: the flotation of free or native gold species and the flotation of gold associated with a variety of sulfide minerals. Important plant operating factors influencing each of these two categories are presented with supporting examples. Carefully matching reagent chemistry and appropriate operating conditions to any given gold-bearing ore will not only lower the total reagent cost but, more importantly, can lead to measurable increases in gold recovery.

Jan 1, 2000

By Brian Metcalfe, Kord Wissmann, Gianni Martinez

The Middle East consists of vast deserts that reach temperatures up to 50 degrees Celsius, with some areas characterized by endless sand dunes. When the project team selected the location for a large new transportation project, little did they know that the site would be characterized by soft, nearly normally consolidated silt and clay extending below a thin sand crust. Searching for solutions, the design team elected to reinforce the subsurface with Rammed Aggregate Pier® (RAP) ground improvement elements and desired verification that the novel method would stand the test of prolonged static loads. Because the concrete pavements would serve to spread the load, a “zone load test” was performed, consisting of applying a uniform bearing pressure of 150 kPa over a 7.5m square concrete footing. Unlike individual pier load tests, the zone test allowed the project engineers the opportunity to confirm design parameter values under large-loading area conditions, a situation not often available to most designers. This paper presents the results of the zone load test whose results may be interpreted to better understand design parameter values. This paper is of particular significance because it adds a value contribution to the relatively few numbers of “group load tests” available in the literature for ground improvement applications.

May 1, 2022

By Harry M. Castrantas, James L. Manganaro, Craig W. Rautiola, James Carmichael

Caro's acid (peroxymonosulfuric acid) was successfully field tested as a cyanide detoxification agent at a North American gold mine. An on-site FMC generator injected Caro's acid into a mill tailings slurry sump. The WAD cN-(weakly acid dissociable plus free cN-) was reduced from 40-108 ppm to below the target level of 20 ppm using a 1/1 mole ratio of CA (Caro's acid) /CN-. At an inlet CA/CN-mole ratio of 1.8/1, WAD CN­concentrations as low as 4 ppm cN-were achieved. Raw material costs for the cyanide detoxification were cut by 60% compared to using hydrogen peroxide (H202) alone. Detoxification time with Caro's acid was much faster compared to H202. This resulted in completion of detoxification before the treated slurry reached the tailings pond thereby substantially reducing the probability of wildlife fatalities.

Jan 1, 1993

By Richards RG

The Australian glass sand industry produces some 2.8 million tonnes per annum of silica sand, of which about 2.0 million tonnes are exported and the rest is for the domestic market. Approximate production rates for each Australian state are listed.The variety of processing methods used in the currently exploited deposits reflects the size, location, and characteristics of the various deposits and the requirement of the end market/s. The industry uses to a large extent equipment developed for the separation of mineral sands, particularly as it applies to low grade heavy mineral deposits, where low cost, high capacity and metallurgically efficient equipment has proved eminently suitable for the production of the low value glass sands.The requirements of the domestic market, as well as those of the present and potential export markets are discussed covering quality requirements, distribution channels and other factors critical to success.

Jan 1, 1990

By J. S. Bays

Industries are challenged to meet increasingly stringent regulations for selenium and metals. Cost-effective treatment is required to minimize the economic impact of environmental compliance. Low-cost biological treatment of selenium can be achieved passively using biochemical reactor cells composed of natural organic media components such as wood chips, sawdust, hay, composted manure, and peat. The reactor cells create an anaerobic microenvironment for biological reduction and sequestration of selenium and other metals. Biochemical reactors can be combined with constructed wetlands for flow equalization and to remove the organic byproducts in reactor cell outflow. Passive treatment reduces capital cost and operational effort compared to more expensive and complex physical and chemical treatment. Recent pilot and full-scale projects by mining companies and by the US Bureau of Reclamation demonstrate that passive treatment can achieve compliance with selenium concentrations over a range of flows and environmental conditions. Case histories of passive selenium treatment systems and their key findings are provided, and prospects for future applications are summarized.

Feb 27, 2013

By G. F. Trainor

At the Canadian Natural Resources Limited (CNRL) Horizon Mine they use Wenco International Mining Systems Ltd (Wenco) Fleet Management System to monitor and control their production fleet with the goal of increasing operator productivity and safety, and raising dispatcher awareness and control. Amongst the broad productivity goals CNRL wanted to achieve with help from the system was a very specific need to blend ore at the truck level. CNRL uses 25m x 25m block geological model information to represent their complex ore body. Wenco's High Precision GPS application, BenchManager provides precise graphical actual-vs-design operator feedback and system integration. Together the two companies advanced the BenchManager product to meet CNRL's needs by using live camera feeds to compare activity with data collection that ultimately lead to changes in the algorithm to include enhanced GPS indicators and the support of a GLONASS assisted solution generating distance and bearing information.

May 1, 2011

By H. Dijkman

The PAQUES Bio Systems' core technology, marketed under the name THIOPAQ®, consists of various high-rate biological processes for metal-sulfur-water systems, complemented with common solid/liquid and gas separation steps. Sulfur species are converted to sulfide, which is a valuable component as it can be used for metals reduction and precipitation. Selective recovery of valuable metals can be employed, leading to revenue from metal values. In this paper, biotechnological systems for the treatment of metal sulfate solutions and dilute SO, gases are described. These installations can be designed to either produce predominantly aqueous (NaHS) or gaseous (H2S) sulfide. The emphasis here is on hydrogen sulfide gas. The main case history discussed is the demonstration plant that ran on hydrogen gas at Kennecott Utah Copper. Three years of operating experience clearly show that sulfate reduction with hydrogen gas is a viable option. Furthermore, the selective recovery of copper from leach water with the hydrogen sulfide produced was shown to be very effective.

Jan 1, 1999

By S Latchireddi

Close circuiting autogenous and semi-autogenous mills is anenergy efficient way of grinding and a number of operations haveutilised this in the design of their comminution circuits. Owing tothe large flow of slurry through the mill that results fromoperating this way the grates and pulp lifters have to be designedto cope. However, the literature has little or no information onhow grate and pulp lifter size and design are related to theirability to remove slurry from the mill. Over the last few years theJKMRC has been researching this area and has developedrelationships between grate/pulp lifter design and flowratecapacity. At the same time it has determined the major causes ofpulp lifter inefficiency and a solution to preventing thisinefficiency (the Twin Chamber Pulp Lifter). This paperdescribes the models that have been developed through thisprogram and uses industrial scale data to illustrate their accuracy.Results from the industrial trials of the Twin Chamber PulpLifter are also presented.

Jan 1, 2001

Since early 1968 the Bureau of Mineral Resources (B.M.R.) has carried out VLF-EM test surveys in various parts of Australia and Papua. The aim of the work, primarily, was to examine the effect- iveness of the method as an exploration tool under a variety of Australian conditions. Selection of test areas was determined by the availability of geological, geophysical and drilling information and by the desirability to include a variety of physical variables such as depth of weathering and topography. The aim of the present account is to review the results of this work and to make an assessment of the method available to the mining industry. The author wishes to acknowledge considerable assistance both by way of data and discussion provided by Messrs. Paul Gillespie (B.M.R.). and John Haigh (formerly B.M.R., now Senior Geophysicist, McPhar Geophysics Australia.) The article is presented with permission from the Director, B.M.R.

Jan 1, 1971

By A. Galip Ulsoy, K. V. S. Sastry

"This review paper is intended to provide, the mineral process engineer with an introduction to the concepts, terminology. and practice of mineral process control. It also provides an extensive sampling of the vast body of literature relevant to this topic. The topics discussed include the principles of automatic control, instrumentation, mineral processing unit operations, process modeling and simulation, and process and plant control. IntroductionEconomically accessible higher-grade ores are being rapidly depleted, and at the same time the demand for mineral raw materials continues to increase. Mineral recovery from the remaining low-grade or finely dispersed ores requires grinding for liberation. High energy consumption during grinding and poor efficiency associated with the beneficiation of fine minerals are two important problems facing the mineral industry . These problems, coupled with advances over the last 10 to 15 years in the areas of process modeling, instrumentation, computer technology and control theory, have made automatic control of mineral processing systems an important research area(23,52,66,67,120,129,152)."

Jan 1, 1981

By P. Prakash

A dual-drive planetary mill, which has a rotating shaft that sweeps a circle of diameter 750 mm, has been designed. The planetary mill is powered by a 5 hp motor to rotate the main shaft and a 3 hp motor to rotate the jars. The charge dynamics inside the horizontal-axis planetary ball mill was established using three-dimensional DEM simulations. The simulation results provided data to determine the impact energy distribution and the effect of process parameters such as mill speed and filling. It has been observed that the mean impact energy per unit time increases with rotation-to-revolution ratio, whereas the average number of inter-particle impacts per unit time decreases. The mill was also used to synthesize a variety of powders. Here three case studies of reaction milling are briefly presented: (i) cementite and silicon carbide, (ii) oxide dispersed strengthened (ODS) steel, and (iii) magnetite from blue dust. In each case, the powder was produced by mixing and then milling the corresponding pure components. The phase evolution, particle size distribution, and morphology of particles during milling were studied for various samples collected at different milling times using laser size analyzer, SEM, TEM, and Mössbauerspectroscopy. The results established a convenient way to produce powders of high technological and commercial value.

Sep 1, 2012

By S Blackburn, T Veasey

The physical and mechanical properties of rock can be measured by a variety of standard tests, and studies have shown that there should be a fundamental connection between breakage in comminution and rock æstrengthÆ. The current study aims to develop the ring-loaded strength test, used as an industry standard for the characterisation of brittle ceramics, for determination of comminution behaviour from exploration borehole core samples. The test procedure is simple, reproducible and can yield 250 separate measurements from a one metre length of drill core. The effects of material grain size and fabric on the degree of scatter of results have been investigated with respect to the ring-loaded strength test. This study has also compared the ring loaded strength to the chevron bend test used to determine the Mode I fracture toughness. A wide range of rock materials have been studied and with further work it is conceivable that an operational work index could be obtained directly from exploration drill cores tested via the ring-loaded disc test.

Jan 1, 2000

By N. B. Devi

The extraction of Cu(II) from HCl media using Cyanex 923 in kerosene was investigated. The effect of shaking time, aqueous phase acid concentration, extractant concentration, chloride ion concentration, various metal ions (Mn2+, Mg2+, Fe2+, and Ni2+), and temperature on the extraction were studied. Using 0.1 M Cyanex 923 the extraction of Cu(II) was 6.7 per cent from 3 M HCl, which increased up to 78.5 per cent with 6.5 M HCl and then decreased due to acid extraction by the extractant. The maximum extraction (97.5 per cent) was obtained with 1 M Cyanex 923 from 5 M HCl solution. A mathematical model has been developed to describe solvent extraction equllibria over wide ranges of concentration of extractant, acid, and chloride ions. The composition of the extracted species has been predicted on the basis of slope analysis results and extraction equilibrium modelling. The negative values of enthalpy change and entropy change confirm the exothermic formation of the extracted complex.

Jan 1, 2012

The accurate determination of trace level gold in ores, metallurgical samples and process solutions is required because of the value of gold, the efficiency of the cyanide leach process and because of the high gold recovery from these cyanide solutions. It is thus necessary to routinely analyse geological and metallurgical samples with gold concentrations of 3 g tonne (ug g- 1ppm) and process solutions with a gold concentration of 0.01 mgL 1 (ppm) preferably with sufficient accuracy to quote at least two significant figures. Several techniques have been reviewed for their suitability for the routine gold analysis of these samples which also contain signif- icant concentrations of other ions. The classic fire assay technique has achieved the respect and confidence of mining personnel because of the results achieved by very experienced assayers. Other extraction and concentration techniques have now been shown to be equally effective. The use of instrumental analytical techniques particularly atomic absorption spectrometry have shown that cheaper procedures, which are as reliable, are now available to gold producers for the routine analysis required to maintain an efficient gold recovery process.

Jan 1, 1982

By M. B. Kime

"A set of experimental batch leaching tests studied the effect of pH, time, temperature, and stirring speed on the relative Cu, Co, Ni, and Fe leaching yields of an oxidized copper-cobalt ore sample in an aqueous hydrochloric acid solution. The results were statistically analyzed and modelled using the structural equation modelling method. Models showed that Cu, Co, and Ni leaching yields were strong functions of the leaching time and leaching temperature, whereas the Fe leaching yield depended on the leaching temperature, stirring speed, and pH. Under optimum leaching conditions yields were 99.8% Cu, 82.4% Co, 91.3% Ni, and 30.6% Fe.RÉSUMÉ Une série d’essais expérimentaux de lixiviation en bâchée ont été menés pour étudier l’effet du pH, de la durée d’attaque, de la température et de la vitesse de brassage sur les rendements relatifs de lixiviation du cuivre (Cu), du cobalt (Co), du nickel (Ni) et du fer (Fe) d’un échantillon de minerai de cuivre-cobalt oxydé dans une solution aqueuse d’acide chlorhydrique. Les résultats ont été analysés et modélisés statistiquement à l’aide de la méthode de modélisation par équation structurelle (SEM, de l’anglais structural equation modelling). Les modèles ont montré que les rendements de lixiviation du Cu, du Co et du Ni dépendaient énormément de la durée d’attaque et de la température de la lixiviation ; le rendement de lixiviation du Fe, quant à lui, dépendait de la température de la lixiviation, de la vitesse de brassage et du pH. Dans des conditions optimales de lixiviation, les rendements étaient de 99,8 % pour le Cu, de 82,4 % pour le Co, de 91,3 % pour le Ni et de 30,6 % pour le Fe."

Jan 1, 2017

By T. G. Joseph, R. K. Soni, M. Curley

"Rapid dampening suspension is a proposed suspension design for ultra-class haulers that is intended to avoid metal-to-metal contact inside a strut and under shock loading, thus improving ride quality and ameliorating fatigue loading issues on a hauler structure. Laboratory testing has shown the ability of the proposed design to reduce the opportunity for bottoming out, that is, metal-to-metal contact between the colliding ends of oleo-pneumatic, two-piece suspension struts during the compression cycle. This paper predicts the performance of a full-size rapid dampening suspension strut by applying scaling rules to test the proposed design based on a set of field data from a Caterpillar 797B ultra-class haul truck operating in the oil sands region of the province of Alberta, Canada. The predicted performance of the suspension strut is compared to that of the original equipment manufacturer model, which was monitored on board the truck during field data collection. ¦ KEYWORDS Haul truck, Original equipment manufacturer (OEM), Rapid dampening, Strut, Suspension RÉSUMÉ La suspension à amortissement rapide est une conception de suspension proposée pour des camions de transport de catégorie ultra-class (des engins dont la charge utile dépasse les 320 tonnes métriques), visant à empêcher un contact métal sur métal à l’intérieur d’une jambe de suspension et dans des conditions de choc au chargement. Elle améliore la qualité du roulement et les problèmes de charge de fatigue sur la structure d’un camion de transport. Les essais en laboratoire ont confirmé que la concep¬tion proposée évitera au cylindre interne de heurter le cylindre externe, autrement dit empêchera le contact métal sur métal des jambes de suspension oléopneumatique en deux parties pendant le cycle de compres¬sion. Cet article prévoit la performance d’une jambe de suspension à amortissement rapide à taille réelle en appliquant les lois d’échelle afin de mettre à l’essai la conception proposée, sur la base d’une série de données de terrain relatives à un camion de transport 797B de catégorie ultra-class de Caterpillar (aujourd’hui remplacé par le nouveau modèle 797F) utilisé dans la région des sables bitumineux de la pro¬vince de l’Alberta, Canada. On compare la performance prévue de la jambe de suspension à celle du modèle du fabricant d’équipement d’origine (FEO), qui a été contrôlée à bord du tombereau pendant la collecte des données de terrain. ¦ MOTS CLÉS amortissement rapide, camion de transport, fabricant d’équipement d’origine (FEO), jambe de suspension, suspensionINTRODUCTION Research basis for the paper This paper is based on the unpublished MSc thesis work of El-Sayed (2003), Santos (2007), and Soni (2009) under the direction of Dr. Tim Joseph within the oil sands–equipment interactions program (OsEIP). OsEIP is part of the Alberta equipment–ground interactions syndicate (AEGIS) surface mining research group, School of Mining and Petroleum Engineering, University of Alberta. The aforementioned work spanned a decade of progressive studies into rapid dampening suspension systems, leading to the scale performance indications highlighted here. Although this paper uses a specific Caterpillar 797B suspension strut for field monitoring and as a basis for scale prediction of a modified rapid dampening suspension strut design, the design scaling principles used here could be applicable to any such design change consideration for an oleo-pneumatic suspension system."

Jan 1, 2019

By Robin Schott

The blast furnace process is the most important process to produce pig iron. The necessary process energy is mainly covered by coke. But the production of coke is connected with CO2-emissions and high costs. A significant measure to reduce the coke rate and with it the CO2-emissions plus costs is pulverized coal injection (PCI) through the tuyeres into the blast furnace. A further increase to substitute coke by coal can be achieved by using the Oxycoal+ technology. This article compares and shows the cost effectiveness and the decrease of CO2-emissions with the help of simplified energy balances for the only coke operation of the blast furnace, the operation using pulverized coal injection and the operation using the Oxycoal+ technology.

Aug 17, 2017

By Fengyu Ren, Kunpeng Yu, Gideon Chitomb, Qiangqiang Gao, Liqiang Ma, Jiangtao Zhai, Ichhuy Ngo

The penetration of rock fragments of overlying strata causes advanced ore dilution during drawing. The results of numerical and physical experiments showed that the proposed numerical simulation was applicable and the microscopic parameters of the model were reliable. The penetration under the variables of particle diameter ratio, density ratio, overlying strata thickness, and particle morphology was clarified. The penetration was quantitatively characterized by the discharge amount and the dilution rate. The experimental results showed that the diameter ratio and density ratio had a significant influence on the penetration. On the irregular shape of particles, the penetration is weakened. The overlying strata thickness had little effect on the penetration. This study could provide a theoretical basis for the full section uniform drawing, avoiding advanced ore dilution and further optimization of recovery rate.

Nov 13, 2023