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By K Kongolo, M K. Kalenga

It is well known that the electrochemical precipitation of metals from aqueous solutions is conducted by the electrochemical standard potential scale. This scale indicates the order of nobility of different metals. Consequently, the standard potential scale shows the nocivity of metals when they are present as impurities in aqueous solutions containing metals. In the hydrometallurgy of cobalt, nickel and zinc are co-deposited during cobalt electrodeposition. Nickel has almost the same chemical, physical and electrochemical properties as cobalt. Furthermore, the electrochemical potential of nickel is relatively higher than that of cobalt. For this reason nickel is preferentially reduced at the cathode in the presence of cobalt. The presence of small amounts of zinc in solution leads to contamination of cobalt electro won. In spite of its lower electrochemical potential in comparison to cobalt, zinc is reduced on the cathode because of its higher hydrogen-overvoltage. But, in the hydrometallurgy of zinc, small amounts of cobalt present into solution will contaminates the zinc reduced at the cathode. This is easily explained by the fact that cobalt is more electropositive than zinc. The co-deposition mechanism of sulphur at the cathode is not yet well understood. Great attention has to be paid to the mechanism of co-deposition of sulphur during cobalt electrolysis..This work aimed to investigate the influence of some parameters on the co-deposition of nickel, zinc and sulphur during cobalt electrowinning. The following parameters have been investigated : Co2+ concentration in the electrolyte, current density and ammonium sulphate (NH4)2SO4 additions. It has been established that important nickel, zinc and sulphur co-deposition takes place at relatively low Co2+ concentration in solution. The behaviour of these elements with regard to the cathodic phenomena has been established.

Jan 1, 2005

One of the seminal pioneering papers in reserve evaluation was published by Danie Krige in 1951. In that paper he introduced the concept of regression techniques in providing better estimates for stope grades and correcting for what later became known as the ‘conditional bias’. In South Africa, the development of this approach led to the phenomenon being dubbed the ‘regression effect’, and regression techniques ultimately formed the basis of simple kriging in Krige’s later papers. In the late 1950s and early 1960s, Georges Matheron (1965) formulated the general theory of ‘regionalized variables’ and included copious discussion on what he termed the ‘volume-variance’ effect. Matheron defined mathematically the reason for, and quantification of, the difference in variability between estimated values and the actual unknown values. In 1983, this author published a paper that combined these two philosophies so that the ‘regression effect’ could be quantified before actual mining block values were available. In 1996 and in some earlier presentations, Krige revisited the regression effect in terms of the conditional bias and suggested two measures that might enable a practitioner of geostatistics to assess the ‘efficiency’ of the kriging estimator in any particular case. In this article, we revisit the trail from ‘regression effect’ to ‘kriging efficiency’ in conceptual terms and endeavour to explain exactly what is measured by these parameters and how to use (or abuse) them in practical cases.

Jan 1, 2015

By Geoffrey Berry

Exposure?response relationships between the relative risk of lung cancer and quantitative measures of exposure to asbestos are available from a number of epidemiological studies. Meta-analyses of these relationships have been published by Lash et al. (1997) [Lash, T.L., Crouch, E.A.C., Green, L.C., 1997. A meta-analysis of the relation between cumulative exposure to asbestos and relative risk of lung cancer. Occup. Environ. Med. 54, 254?263] and Hodgson and Darnton (2000) [Hodgson, J.T., Darnton, A., 2000. The quantitative risks of mesothelioma and lung cancer in relation to asbestos exposure. Ann. Occup. Hyg. 44, 565?601]. In this paper, the risks derived in these meta-analyses have been compared. Lash et al., concentrated on process and found that the risk of lung cancer increased as the asbestos is refined by processing. Hodgson and Darnton concentrated on fibre type and found that the risk was highest for exposure to amphibole asbestos (crocidolite and amosite), lowest for chrysotile and intermediate for mixed exposure. Some of the differences between the conclusions from the two meta-analyses are a consequence of the choice of studies included. The range of asbestos types included in the studies in the analysis of Hodgson and Darnton was wider than that in Lash et al., enabling differences between fibre types to be analyzed more readily. There are situations where occupational exposure to chrysotile asbestos has shown no detectable increase in risk of lung cancer. Taconite miners have shown no increased risk of mortality due to lung cancer. © 2007 Elsevier Inc. All rights reserved. Keywords: Mesothelioma; Amosite; Grunerite; Taconite; Crocidolite; Tremolite; Anthophyllite; Winchite; Risk assessment; Etiology

Jan 1, 2007

By Juan Oswaldo Alfaro, Angel C. Nuñez, Hildebrando A. Cóndor

Se ha desarrollado un software para facilitar la evaluación del proceso molienda-clasificación en plantas concentradoras. Se ha modelado en UML-Lenguaje Unificado de Modelado; los datos e información se almacenó en SQL Server; se programó en Java (Programación Orientada a Objetos). Investigación Aplicada y Cuantitativa obteniendo como resultados un Software para Circuito de Molienda-Clasificación (Directa e Integral).

Sep 1, 2017

By Deepak Vidyarthi

This paper deals with the significance of Explosive Energy in the optimization of blast design parameters, and the benefits emerging out of it. It is based on the original work done by the author in developing and successfully implementing a site-specific software package on ‘Blast Design Optimization’ at Kudremukh Iron Ore Mine in India with a production level of 22.5 million tonnes of crude ore and off-take of Explosives of approximately 5500 tonnes per annum. The software package has yielded tangible results in effecting reduction in Explosive Consumption, substantial savings in the Cost of Explosive, besides Environmental Improvements by way of attenuation of Blast Induced Ground Vibrations as well as Air-Blasts. By carrying out regular ‘Regression Analysis’, and determination of the Rock Constants, it has been possible to further develop software packages as well as prediction curves for prediction of Peak Particle Velocity, Safe Charge of Explosive, Air-Blasts etc. A model has also been developed for the prediction of ‘Fly Rock’ although at KIOCL, fly rock does not pose any problem.

Jan 1, 2006

By Fengyu Ren, Ruslan Puscasu, Kunpeng Yu, Gideon Chitombo, Liangliang Kang

Weak rock mass and poor flow of material can cause excessive ore loss and dilution in sublevel caving. This paper proposes a method to establish design parameters for an inclined deposit within a weak rock mass and evaluates its effectiveness through a case study. In order to solve the problem of low production capacity and poor safety conditions of sublevel caving mining at the Yingfangzi silver mine in China and to ensure a smooth production from the refractory ore body, it is necessary to select appropriate stope structure parameters. Based on random medium theory of gravity flow and the improved equation of ore discharge in random medium, an end wall drawing experiment is carried out to determine the optimum design and flow parameters. It was observed from the experiment that, due to the influence of the randomness of particle movement, there is a mismatch in the flow parameter measurement. The flow characteristics and distribution of the marker particles are different from that of the tested particles resulting in large drawbody shape distortion. The study finds that the flow parameters obtained by the new method are more practical and account for drawpoint width and recommends that the new method for determining the sublevel stope height is used when the drawbody is a non-standard ellipsoid. The outcomes have shown a significant reduction in the dilution and improvement in the recovery rates, and the safety and efficiency of mining have been greatly improved.

IN a mine with any considerable output the economical handling and transport of ore underground is a matter of prime importance, and in the design or lay-out of a trucking system the question of what form the points and crossings are to take should be one of the first considered. Trucks may be moved from one line of rails to another by the following means: by flat sheets, with which may be coupled turn-tables, or by points and crossings. The latter class may be further divided into fixed and movable points.Flat sheets and turn-tables, owing to the time and skill needed by the trucker in using them, are seldom of great value with large tonnages, unless for purely temporary work, and the choice narrows down to one between fixed and movable points andcrossings. Both systems have their disadvantages - movable points being liable to jamb with dirt and get out of order, whilst with fixed points trucks may sometimes run over the points and capsize, or go on to the wrong line, though this is not of frequent occurrence. On the other hand. the fixed points are simple, easily laid, and strong, and there is no necessity for the trucker to work any levers, the truck being guided on to its new direction by screwing.Cast-iron points and crossings were first introduced into the North mine during the opening-up of the 950-ft. level, and the first arrangement was designed for a double turn-out in the main crosscut. Since then both the points and crossings have beenmodified several times, and it may be interesting to briefly outline the various forms through which they have passed, showing the reasons for the retention of some features and the rejection of others.

Jan 1, 1915

The growth and influence of Sherritt Gordon Mines Ltd. in the nickel producing industry has been quite phenomenal. Although the company's Lynn Lake deposit in Manitoba was actually dis- covered in 1941, it was not until 1945, when men and materials were more readily available as a result of the end of World War II, that the area was staked and news of the discovery leaked out. As a result of the discovery, Professor Frank Forward of the University of British Columbia was commissioned by Eldon Brown, then President and Man- aging Director of Sherritt, to develop a new nickel refining process. A pilot plant, based on the results of Professor Forward's research, was constructed in Ottawa, and after the successful testing of the Lynn Lake ore, Chemical Construction Co. was given a con- tract in 1952 for construction of a producing plant. By 1954, the Fort Saskatchewan refinery was operating at an annual production of 15 million lb of nickel metal in the form of briquetts or powder. Capacity has since been increased to 30 million lb.

Jan 10, 1968

The Mount Angelo prospect outcrops as two copper rich gossans, the larger of which is 250 ft long and 70 ftwide. The mineralization is epigenetic and replaces part of a brecciated and disturbed lime tone and calcareou sediment sequence.Magnetic and self potential survey indicated a substantial body of sulphide mineralization, the top of which was approximately 100 ft below the surface.Diamond drilling confirmed this and established the presence of a mineral body of at least 500,000 tons, extending to a depth of 300 ft. Of the 500,000 tons, 200,000 ton are primary copper ore which a ays 2 per cent copper.This mineral body is not economic at present, but could become economic if copper mining is established elsewhere in the district...

Jan 1, 1966

By Thomas Kuhn, Carsten Ruehlemann, Christina Heller, Anna Wegorzewski

The commercial extraction of metals from manganese nodules on an industrial scale requires more than 50% of the investment necessary to realize manganese nodule mining. This is mainly due to the fact that a completely new metallurgical processing scheme for the extraction of both base metals (Ni, Cu, Co) and high-tech metals (Mo, Li, Ga) has to be developed and upgraded to industrial scale. There are a number of conventional processing technologies that combine hydro- and pyro-metallurgical approaches such as the INCO and CUPRION processes which have been developed in the 1970s and 1980s. Today, new approaches based on selective leaching with chelating agents and bioleaching try to minimize energy consumption and waste production. All of these extraction methods require knowledge how the metals are structurally bound in the manganese oxides. In this contribution we will review the current knowledge about the mineralogy of iron and manganese minerals in the different marine oxide deposits, present our results, and discuss the possible consequences for metal extraction.

Sep 1, 2014

By T P. Fischer, S N. Williams, N C. Sturchio

Chemical and isotopic analyses of fumarole gases from Galeras Volcano, Colombia provide significant insights into the origin of volatile components in the magma. Water comprises a mixture of magmatic (rock-equilibrated at high temperature) and meteoric, with the relative proportions varying through time. Carbon isotopes are most consistent with a mantle source, although other contributions to the system cannot be ruled out. Nitrogen most likely originated from organic matter in subducted oceanic sediments. All of these 'primary' components have been modified somewhat by interaction or exchange with other reservoirs during ascent to the surface. In addition to information on the origin of the gases, these data show significant temporal variations precursory to eruptive events. Chemical ratios change and water becomes more meteoric in character prior to eruptions.

Jan 1, 1995

By Verya Nasri, Scott Thorburn

The City of Toronto and the Toronto Transit Commission (TTC) have conducted an Individual Environmental Assessment (EA) for a 6.2 km, 4-station underground extension of the Spadina Subway from Downsview Station to Steeles Avenue. This Environmental Assessment Study was performed in three phases including routes and general station locations, alignments and station concepts and detailed assessment of the effects of the undertaking. URS Canada Inc. has led the consultant team for this Study. The anticipated total duration of the project is approximately 6 years and its estimated total cost is about $1.4 billion. This paper presents the planning process of the project, the environmental and engineering challenges, and the measures taken to address them.

Jan 1, 2007

By L. A. Thompson, A. J. Linington

"Copper–cobalt extraction is a reagent-intensive process resulting in acid consumption greatly contributing towards production costs, which in the current market conditions curtail profitability. Nanofiltration (NF) membranes have become an attractive approach in the mining and minerals industry for product concentration and reagent recovery based on the ability of the membrane to separate monovalent ions from divalent ions. NF membranes can selectively separate acids from metals and salts allowing acid to be recycled as well as the concentration and purification of product streams. Membrane technology in the field of copper–cobalt processing focusses on the concentration of Cu2+ and Co2+ in the pregnant leach solution, recovery of acid from waste streams to neutralization, recovery of valuable metals from waste ponds and process water recovery. This paper aims to provide insight into the potential applications of NF membranes in copper–cobalt processing circuits as well as a brief overview of the effects of process conditions on membrane performance and process development. INTRODUCTION The copper–cobalt industry commonly uses inorganic acids, such as sulfuric acid, in large quantities for primary leaching of copper–cobalt oxide ores and releaching during product purification (Stuurman et al., 2014). This results in numerous acidic intermediate streams containing high metal concentrations and acidic waste streams with low metal concentrations. Acid consumption typically accounts for 10–15% of the operating costs of mines in the Democratic Republic of Congo (DRC) and Zambia (Acid Plant Database, 2015). Due to remote mine locations, poorly maintained roads and cross-border conflict, the cost of sulphuric acid can range between USD 300 and 400 per ton. The pivotal role of acid in the copper–cobalt extraction process has driven many mines to build sulphuric acid plants on site to ensure a reliable acid supply, however elemental sulphur still needs to be imported which faces similar logistical challenges and contributes towards operating costs."

Jan 1, 2015

By J. J. Gusek

Several final pits in the Seneca No. 1 Surface Coal Mine were abandoned in the 1960's without king reclaimed. In addition, a progressive landslide aggravated by the abandoned mine land conditions was threatening a county mad and private property. An AML-funded project to stabilize the landslide and reclaim the final pits was completed in 1986 for the Colorado Division of Mines and Geology (formerly Colorado Mine Land Reclamation Division). The site was visited after ten growing seasons. The land is stable and the vegetation re-establishment is strong. Volunteer native plant species are now invading the reclaimed sites.

Feb 24, 1997

Tapira Mine (Tapira, MG, Brazil) is the largest phosphate ore and concentrate producer in Brazil. The mine is an open pit, which until recently operated with a large equipment fleet and now uses a smaller fleet operated by contractors. The annual production reaches 17 Mt of ore plus 14 Mt of waste at a stripping ratio of 0.82. Defining the geological boundaries and forecasting the annual production can be a difficult task if not performed on a reliable model. The geological model has been totally reviewed as well as the estimation process. Ordinary Kriging has been used to build the new block model with P2O5 and contaminant grades. After estimation, block model validation and classification criteria definition to assess resources and reserves, the result is given by the life-of-mine plan is defined after pit optimisation and design. The Lerchs-Grossmann algorithm implemented in the NPV Scheduler was used to define the long-term production targets based on the main parameters P2O5 and the contaminants that are just important to the beneficiation process.

May 1, 2010

By Mohamed Ourriban, Yongjun Peng, Qi Liu, Denis Cotnoir

"In the flotation of fine particles, there are two difficulties in general: low recovery of valuable minerals and high recovery of gangue minerals. The low recovery of fine valuable minerals is attributed to low bubble-particle collision and attachment efficiencies, while high recovery of fine gangue minerals is attributed to mechanical entrainment through water films between gas bubbles. Over the last five years COREM has been actively developing fine particle flotation techniques with the objective of improving fine particle flotation separation efficiencies.The fine particle flotation techniques with both generation of micro bubbles and enlargement of sizes of fine particles have been developed to increase bubble-particle collision efficiency. For oxidized fine sulphide minerals, both physical and chemical techniques have been developed to modify the hydrophilic surfaces and therefore increase bubble-particle attachment efficiency. To reduce mechanical entrainment of fine gangue minerals, a new approach, polymeric depression and flocculation, has been developed. By selecting the high molecular weight polymeric depressants to make fine gangue minerals hydrophilic and also enlarge their sizes, entrainment can be minimized. By combining these techniques, we are able to improve both flotation recovery and selectivity in some fine ore flotation systems.INTRODUCTIONWith depleting mineral resources and their declining grades, ores leaving grinding circuit for froth flotation are becoming increasingly finer to achieve mineral liberation. Together with the increasing demand for minerals, ever-increasing tonnages of fines are being produced. Therefore, flotation of fine particles is an immense challenge to be tackled by researchers all over the world today."

Jan 1, 2006

By Robert W. Yokom

As the search for new sources of energy and minerals leads to more remote areas of the country - and the world - the need to plan for adequate housing and community facilities for the construction and operations workforces and their families takes on an importance equal to the mining and processing facilities themselves. A corollary to the need for planning is the increasingly crucial need for development companies to devise effective strategies for dealing with the local communities impacted by these projects. Experience has amply demonstrated the high price to be paid for failure to learn this lesson, a price measured in lost productivity, confrontation with local communities, labor turnover, mental health and other social and eocnomic problems. In Sweetwater, Wyoming, a new industrial activity caused the population to double from 18,000 to 36,000 between 1970 and 1974. During that period industrial productivity fell 25 to 40 percent, cost overruns on the principal new industrial facility exceeded 33 percent, annual employee turnover rates climbed above 100 percent, the local mental health clinic workload increased nine times and complaints to the local law enforcement agency increased 60 percent.

Jan 1, 1981

By John Mathews

IT is a great honor to be asked by. the Board of Directors of this Institute to deliver the Henry Marion Howe lecture. The invitation carries with it a great responsibility, which I accept with considerable hesitation and with a feeling of unworthiness to perform the duties expected of me in this hour devoted to the memory of the life, character, and work of the late Professor Howe. Many of you recall the scholarly address delivered here a year ago by Prof. Albert Sauveur, and the beautiful tribute he paid-to his friend and colleague of many years in the great work of changing the art of iron making into the science of iron. My association with Professor Howe, was of brief duration-only one year-and the relation was that of pupil to teacher. My feeling toward him in later years was always that of a humble disciple at the feet of a master. He attained his third academic degree in the year that I was born. I recall the pride I felt when, after entering the, steel industry, I received from him, from time to time, letters asking for information or, perchance, asking my opinion, and he was always most punctilious in acknowledging the source of such bits of information in his writings. It was also my good fortune to sit at the feet of another great teacher-Sir William Roberts-Austen, at the Royal School of Mines. I mention him because his name was used by Osmond in coining the word "austenite," which is the subject of this address, and Osmond's suggestion was heartily approved by Howe. These three international metallurgists were the best of friends and delighted to honor the achievements of one another. There are other reasons for mentioning Roberts-Austen at this time. It was an introduction from Howe that opened to me the door of his -laboratory as well as of his heart. It was while at Roberts-Austen's laboratory that I .worked side by side with William Campbell

Jan 4, 1925

By Peter Zhang

The immediate roof at the test site consisted of laminated clay shale that is likely to be susceptible to weathering. With seasonal dry-wet cycles in the mine ventilation air, the roof in the intake air would deteriorate and lose integrity over time. In many instances, the weathering-prone roof would gradually scale off piece by piece between bolts and over the entry corners. In some long-term entries, roof weathering could develop up to 2-3 ft deep with columns of bolted roof hanging under the upper intact roof. If wire mesh is used, the roof bags down and reduces the entry height, and the weight of the bagged roof tends to pull the bolts out and poses a safety hazard. An effective measure is always sought to support this type of weak roof that is sensitive to moisture degradation. One solution is to seal the roof shortly after entry development to prevent moisture penetration so that roof integrity can be maintained for the long term. In this application, a polymer-based sealing material was tested in the Rockspring mine for weathering protection and reinforcement. The material is a one-component polymer powder for spray application onto the roof and rib. The sealant material is mixed with water in the spraying nozzle to apply to the roof and rib as a paste. The product sets within 5-10 minutes and forms a membrane as thin as about 1/8-in. The membrane will quickly develop tensile and bonding strength within minutes and completely cure within a few days. Through sealing, bonding and lateral reinforcement, the integrity of the weak roof can be maintained. The material has been tried in a long-term evaluation over several months in a set of main entries in the Rockspring mine owned and operated by Rockspring Development, Inc., affiliate of Foundation Coal. Preliminary evaluation has shown that the material is an effective and economical solution to ensuring the long-term stability of weathering-prone roof.

Jan 1, 2009

By Keila Gonçalves, Aline Tavares, Danielly Couto

"The sulphide copper deposits from the Carajás area (North region of Brazil) were generated by the percolation of hydrothermal fluids in volcanic and granitic rock and are denominated as IOCG deposits (iron oxide copper-gold deposits). During these hydrothermal events a wide variety of gangue minerals such as amphiboles, biotite and fluorite were formed. These gangue minerals are enriched in fluorine and chlorine which are deleterious elements in the copper concentrate. Chalcopyrite and bornite are the main copper-bearing minerals and they can occur in veins, in brecchia or disseminated in gangue.The study, which included bench scale flotation tests and minipilot plant tests was aimed at improving the fluorine rejection in the flotation process during the flowsheet design for one of these Carajás sulphide copper deposit. All of the study was supported by quantitative mineralogical techniques such as QEMSCAN and the use of a scanning electron microscope (SEM).This paper describes and discusses the results obtained in the metallurgical tests and emphasizes the importance of the quantitative mineralogical characterization during the process conditions optimization and flowsheet design.INTRODUCTIONIron oxide copper-gold (IOCG) deposits encompass a wide spectrum of sulphide-deficient low-Ti magnetite and/or hematite ore bodies of hydrothermal origin and normally have important copper sulphide reserves. In the Carajás mineral province, located at the southeast part of the Amazon Craton in Pará State (Brazil), there is a variety of world-class (>200 million tonnes) Fe-oxide Cu-Au deposits (e.g. Salobo, Cristalino and Sossego), whose genesis has been assigned to hydrothermal fluid percolation in volcanic and granitic rocks. Figure 1 displays the location of the Carajás area.The hydrothermal thermal fluid composition was extremely variable. It may have contained gases, salts (brine) and metals. The metals were carried as various complexes and it is thought to have involved sulphur, chlorine and fluorine containing species. This resulted in some minerals formed during the hydrothermal alteration having high fluorine and chlorine contents. These elements result in smelter penalties in a copper concentrate because they cause the smelter off-gases to be more corrosive."

Jan 1, 2011