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By A. Tsekov, Stefan Neufeind, T. Angelov, G. Savov

"A complementary ion exchange/solvent extraction process for the recovery of copper from low-grade ores developed by Iontech Engineering Ltd. is described. It has successfully been implemented on a full-scale plant level at the Buchim Copper Mine in Macedonia, yielding a maximum copper cathode production of 2400 tonnes per year. Technical and economic aspects of three years of operational experience are comprehensively compared with the Asarel Medet copper plant in Bulgaria, which is utilizing conventional solvent extraction in the enrichment/purification step. INTRODUCTION The concentration and separation of copper from primary leachates is one of the key operations in the hydrometallurgical processing of oxide ores (Langner, 2011). Conventionally, this basic operation is conducted by submitting the pregnant leach solution (PLS), with a 1–5 g/L Cu content, from the initial sulfuric acid leach to a solvent-extraction (SX) process in which copper reports to the organic phase (see Figure 1). After phase separation, the metal is stripped from the extractant/diluent mixture employing sulfuric acid to furnish a concentrated metal solution, usually containing 40–50 g Cu/L. The final products of the overall process are copper cathodes, which are obtained from a terminal electrowinning step.Although considered as “technology of choice”, SX to date is still suffering from several drawbacks, such as the risk of poor phase disengagement and the high capital costs of solvent-extraction plants. Especially, the processing of leachates with lower copper tenors (< 1 g/L) is often economically less attractive. As a result, tremendous efforts have been dedicated to the evaluation of alternative technologies to address these challenges."

Jan 1, 2015

By D. L. H. Bulbring

The removal of a cylindrical core from thick-wall sections for creep analysis by the relatively new Weldcore® process represents a very exciting methodology for obtaining more representative creep damage data from large engineering structures. The cylindrical core that is removed, representing about 60% of the wall thickness, leaves a substantial removal site that needs to be repaired. This paper presents data pertaining to taper Friction Hydro Pillar Processing as an alternative repair technique for filling the core removal site. Process parameters were evaluated with special attention being paid to the effect of downward force on process response variables, weld defects, and mechanical properties of 10CrMo910 steel. Process temperature and torque response as well as total process energy input were also considered. This paper also assesses the static and dynamic performance of this repair technique. The influence of a varying downward force and the occurrence and position of discontinuities were quantified. Downward force was shown to have the most notable effect on weld joint dynamic performance and was found to be related to the process temperatures achieved in close proximity to the weld interface.

Jan 1, 2013

International Solvent Extraction Conference 1971 ISEC &apos;71, which will be held in The Hague, The Netherlands, from 18th to 23rd April, 1971, is being sponsored by the Society of Chemical Industry in association with the Koninklijk Instituut van Ingenieurs, the Institution of Chemical Engineers and the Koninklijke Nederlandse Chemische Vereniging. The Working Party on Distillation, Absorption and Extraction of the European Federation of Chemical Engineering is participating in the Conference, which is the 101st event of the Federation. The scope of the Conference covers the entire science and technology of liquid-liquid extraction as applied in all branches of industry. Thus sessions will cover both chemical and chemical engineering aspects of the subject as applied to both inorganic and organic solutes. The conference aims to bring together academic and industrial workers in the field from all parts of the world. The programme includes over 100 papers by authors in 26 countries. Full details of the papers, together with registration forms, are contained in a detailed programme, copies of which are now available from: ISEC &apos;71, 14 Belgrave Square, London, S.W.1, U.K. Department of Mining and Mineral Technology of the Royal School of Mines Postgraduate Courses Technical and economic challenges facing the minerals industry, together with progressive change in methods and equipment, increasingly necessitate re-training of experienced professional engineers who aim for top places. In order to meet this need, this Department has for some years run one year M.Sc. courses. Engineers, often sponsored by their employers, have a choice of three courses which are respectively devoted to mining, applied rock mechanics or mineral process design. The course in Mining is divided into five subjects, which are treated from the business management point of view. It is intended to provide middle management with a knowledge of those techniques that are required by the mining engineering function in the preparation of modern projects. The course in Mineral Process Design provides a systematic use of mineral sciences, engineering and economics for ore testing and process design, so as best to balance the technical and financial requirements for specific mineral resources. The course in Engineering Rock Mechanics is designed to provide a specialized training in the engineering applications of rock mechanics for engineers and geologists, so that they are equipped to treat a wide variety of problems in mining and civil engineering. Prerequisite qualifications are a good first degree in a related subject, plus industrial experience: The rewards include an M.Sc. of the University of London and the Diploma of the Imperial College (DIC). The limited number of places available (12 in each group) makes early application advisable. Full details are available from the Registrar, Imperial College, London, S.W.7.

By T. A. Silva, A. C. Bragança

Lime has been added to the iron ore slurry transported by the Samarco pipeline since its operation start-up in 1977.Initially, internal corrosion was the main concern therefore the reagent was used only for pH correction. Over the last ten years, though, transport of more complex slurries demanded a significantly higher dosage of lime to guarantee adequate rheology control. Several other reagents have been tested for the same purpose yet none has proven to be as effective regarding technical performance, environmental impact and cost. However, an alternative was sought so that the slurry rheology could still be controlled in case lime addition became impracticable. The objective of this paper is to present a technical solution for this matter, which takes into account environmental aspects. It consists of adding soda for pH correction and an organic coagulant as a rheology modifier. The latter is a quaternary ammonium salt which affected the slurry transport properties in the same manner as lime when tested in a laboratory. It showed no plug formation and allowed solid particles to settle, forming a loose sediment after rest. These results indicate a low probability of plug occurrence in the pipeline and the formation of a readily reslurryable sediment upon shutdown of the pumping system. Industrial tests should be performed in order to validate the laboratory results.

Jan 1, 2007

By Kathryn C. Sole, Owen Tinkler

"Although the first large-scale application of copper recovery by solvent extraction (SX) took place in Zambia in the early 1970s, it is only in the last decade that this technology has become widely employed in this part of the world and is now a mainstay unit operation in most copper hydrometallurgical flowsheets. The mineralogy of the ores in the African Copper Belt, and hence the characteristics of the African leach liquors, differ significantly from those in Chile and the south-western USA, where copper SX has had a long and successful history. These differences provide operators, metallurgists, reagent vendors and engineers with many challenges: new approaches are needed to adapt this technology for successful implementation in this region. This paper examines typical operating practice in the African Copper Belt, discusses differences compared with other parts of the world and looks at some of the challenges and opportunities presented by these flowsheets. INTRODUCTION Following the success of the Rancher’s Bluebird and Bagdad solvent extraction and electrowinning (SX–EW) operations in Arizona in the late 1960s, the Tailings Leach Plant at Chingola, Zambia became the first large-scale copper SX plant in the world, commissioned in 1974. Despite the equipment design now being outdated, this plant still continues to operate successfully, indicating the versatility and adaptability of this technology. Today, there are some 75 copper SX operations worldwide with cathode production above 10 kt/a. The top ten producers currently account for some 40% of the global 4.3 Mt/a SX–EW copper production. South America (predominantly Chile and Peru) is the largest copper cathode-producing region, with annual production of some 2 Mt. The Central African Copper Belt (Zambia and the Democratic Republic of Congo (DRC)) is second, with cathode production of 1.2 Mt/a and North America (USA and Mexico) third, producing close to 0.8 Mt/a Cu (Cytec data, 2014). The remaining 0.35 Mt/a comes from all other regions combined (referred to as “Rest-of-World”). Current and future operations in Zambia and the DRC are summarised in Figure 1. The industry in this region is characterised by a large number of small (3 to 20 kt/a) plants, mainly Chinese-owned, and a few very large (>200 kt/a) operations, owned by major multinational corporations. This paper examines typical operating practice in the African Copper Belt, discusses the differences compared with other parts of the world and looks at some of the challenges presented by the conditions, as well as innovations in flowsheets, reagents and operating conditions that have been introduced in these circuits."

Jan 1, 2015

By O. A. Olaseinde

The 2101 lean duplex stainless steel has wide potential application in storage, heat exchangers, and in the oil and gas industries. This work investigates the electrochemical behaviour of 2101 duplex stainless steel with an addition of 0.15 wt% ruthenium, using potentiodynamic techniques in 1M H2SO4 at 25º, 40º, 60º, and 80ºC. The microstructures of samples were characterized using optical metallography and scanning electron microscopy. The results showed that the ruthenium addition moved the corrosion potential of alloy 2101 to a more positive potential. All samples containing ruthenium displayed longer passive regions at 25°C and 80°C compared to those without ruthenium. Alloys without ruthenium had higher critical current density (icrit) values when compared to the alloys with ruthenium. Ruthenium additions decreased the passive current densities and inhibited anodic dissolution. At room temperature the corrosion rate of alloys with ruthenium was lower than these without ruthenium.

Jan 1, 2012

By A. M. Thyer

Throughout the history of mining, underground fires or explosions have killed many hundreds or thousands of people. Fortunately, the safety record has gradually improved as a result of many people’s work on improving safety standards and work practices. However, fire and explosion still remains a threat in many situations. As a result the UK Mines Inspectorate commissioned a project to study materials used underground and to develop a fire/explosion risk assessment system. Such a system has been developed, following the study of incidents, specified fire resistance criteria, and fire safety practices. The final methodology uses a series of check sheets to identify potential fuels and ignition sources, preventative measures, fire/explosion mitigation systems, and items for inclusion in emergency plans.

Jan 1, 2003

By S. Dessureault

Computer Integrated Mining (CIMG) is a process of using computer networks to transform islands of enabling technologies into a highly interconnected mining system. CIMG involves the integration of advanced technologies at various levels in the mine business to achieve higher flexibility, better quality of processes and control, and improved profitability. Justifying the benefits of CIMG are difficult as many of the advantages are derived from improved flexibility, quality, and control. Justification is based on the evaluation of the benefits to be gained, compared to the required capital investment. Management tools used in mining are currently inadequate in assessing the value of advanced technology whose benefits are primarily qualitative. A key aspect of successful implementation is management acceptance, which has to be won through the capability to justify the technology?s financial costs and the true value of all of its benefits. The manufacturing industry faced similar justification difficulties when adopting advanced technology in factories. A significant amount of funding and research was invested in developing management strategies and approaches to justification. Many of the problems that faced the transformation of the manufacturing industry in the late Eighties and early Nineties are now facing mining. The solutions derived for manufacturing may help mining in its transition to an increased reliance on integration technology. Reviewing the industrial history of computer integrated manufacturing identifies several tools and strategic frameworks that can be adapted for mining. Keywords: Computer integrated mining, justification techniques, CIM, information technology.

Jan 1, 2004

By K. M. Godiwalla, S. Ranganathan

The thermal state in submerged-arc furnaces (S.A.F.) producing ferro alloys is important for the conditions of both the grade of alloy produced as well as specific energy consumption. The temperature profile in the S.A.F. is affected by the endothermic chemical reactions and the rate of gas evolution. The gas evolution commences at about 900 C due to the reduction of iron in the ore. A first-principle-based 2-D model has been developed to predict the temperature profile in the furnace. In this study, four ores of different grades have been considered in order to simulate the thermal profile in the S.A.F. The influence of the composition of the ore on the thermal profile and its significance in rationalisation of charge distribution to optimise the process are discussed.

Jan 1, 2007

By L. R. C. Cairncross

In this study, the general case of semi-batch precipitation of nickel hydroxide, Ni(OH)2, is modelled. In practical terms, this precipitation may occur at high ionic strengths, and therefore the model for solution chemistry requires a thermodynamic model that is applicable for these non-ideal systems. The activity coefficient model used is the ELEC-NRTL. The simulation of the solution chemistry is performed using AspenPlusTM, which is a steady-state process simulation program. This allows for rigorous evaluation of the solution speciation, and hence the degree of supersaturation which dictates the precipitation kinetics. The solution chemistry provides the basis for predicting the formation of solids. The model consists of a solution chemistry part and a solids formation part. The inputs to the model include the initial concentrations of the streams entering the reactor, kinetic parameters for the precipitation processes, and a particle size distribution obtained from experiments. The solids formation part of the model employs the method of moments for the evaluation of the population balance. The population balance accounts for total particle number, and the formation and increase in size of particles across the entire particle size range. This balance requires kinetic parameters for the processes of nucleation, growth and agglomeration. Using optimization routines inherent in AspenPlusTM, parameters for the rate of nucleation, growth and agglomeration may be extracted from experimental particle size distributions. These are then used in the model to extrapolate to other conditions. Once an understanding of the kinetics of the precipitation processes is gained, the model provides a predictive tool for optimization of these kinetics, in order to increase the overall particle size and therefore improve solid-liquid separation. The work is deemed to be significant as it sheds some light on solids formation processes involved in precipitation?including nucleation, growth and aggregation?and develops a predictive modelling tool applicable to solutions of high ionic strength. We argue that this dewatering of suspensions is affected significantly by particle size distribution and surface properties of the solids formed by precipitation. This modelling tool should facilitate the design of solids formation processes where downstream dewatering is enhanced.

Jan 1, 1997

By N. Watson

Historically the insurance industry&apos;s involvement in any project has been relatively late in the process. Often it was a case of the last item to be ticked off the checklist has been to ensure that the insurance is in place. However, in more recent times insurers have imposed more restrictions on the cover they are prepared to provide, which has in some cases necessitated a change in the contracting structure to accommodate the insurance policy(ies). In addition, changing contractual practices have changed the allocation of risk between the various parties involved. This calls for a more proactive approach to the design and implementation of an insurance program for both the construction and operational phases of any resource project. This paper explores how a risk managed approach to the design and implementation of an insurance program for a resource project can align itself with current management approaches to project development. From the authors&apos; experience, this approach is best adopted early on in the project (often in conjunction with the bankable feasibility study) and follows AZ/NZS4360 to objectively examine and compare a wide range of risk exposures of the project in a time-effective manner across the following areas: ? personnel; ? environment; ? general management; ? compliance - legislation, systems, protocols; ? asset management; ? change management; ? financial impacts to the organisation; ? products/services; ? service delivery; and ? technology. Having identified and then analysed the risk exposures according to common consequence and likelihood ratings the next step is to develop a risk map of all considered exposures. The true value of this approach lies in the development and implementation of a risk treatment plan for identified exposures where the exposure is unacceptable. The plans will lead to the optimal solution to the appropriate risk prevention, risk mitigation and risk transfer options available. This paper also examines other benefits to the project that may arise from adopting a risk managed approach in addition to the ability to design an insurance program which recognises the exposures and the ability of the organisation (and other project parties) to retain risk.

Jan 1, 2007

By T. Khumalo, L. P. Coetzer

This paper addresses the impact of the variable speed drive on the particle size distribution in the product of a fully autogenous UG2 grinding circuit. It further discusses the impact of a varying particle size distribution in the product of the mill on the downstream classification and milling circuits. An industrial case study was used and data is presented to illustrate the techniques applied to identify the root cause of the shift in operational efficiency. The results achieved from both the investigation into the shift in plant efficiency and the sub-sequent corrective action taken illustrate that the root-cause methodology used in advance control can be effectively applied on production sites to both detect the shift and identify probable root-causes. The industrial example used confirms that the variable speed drive in a UG2 autogenous milling operation is a critical control parameter to ensure that the plant operates to design specifications.

Jan 1, 2006

By D. P. Power

The development of an accounting code for the metallurgical industry has been debated for many years. Following the series of tumultuous economic events in the nineties and earlier this century that have affected business, there was much need for legislation to be passed to minimize potential risk. One of the consequences to affect the mining industry was the enhancement of existing geological codes for reporting. In parallel the sponsors of AMIRA have taken the brave step to develop a generic code for metal accounting that embraces the full gamut of industry. In this paper the code will be reviewed in the context of metallurgical accounting as it applies to coal preparation. This paper provides the background for this development and an insight into the mechanism for the debate for the generation of this code. The key elements of the code as it applies to the coal industry are explained but most importantly the key opportunities are highlighted.

Jan 1, 2010

By Timo Niitti, Antti Rinne, Janne Turunen, Klaus Schommarz, Sami Grönstrand

This paper captures the essential steps employed in developing Outotec?s new FloatForceTM mechanism. The development of a flotation mechanism essentially revolves around the efficient transfer of installed power, or capital cost, to optimum flotation performance. Optimum flotation performance will be achieved if a balance between metallurgical results, operating and capital costs is maintained. The development of the FloatForceTM mechanism was done by careful evaluation of each of these three areas. This paper focuses on how experience, CFD and laboratory equipment, pilot and plant tests are used to test and evaluate a new flotation mechanism. Validated variables include mixing profile, power draw and local air hold-up. Metallurgical and mechanical design considerations are not covered in this paper. Besides using the FloatForceTM mechanism in new flotation equipment, the FloatForceTM mechanism can be used in existing flotation cell installations, thus enabling improvements in the mixing profiles, solids suspension and metallurgical performance of operating flotation circuits. Results of several tests carried out in existing plant operations are presented.

Jan 1, 2007

By M J. Van Der Merwe

The mining industry is facing a serious skills resource shortage, growing commodity demand and cyclical prices. This makes focus and allocation of resources in the early stages of project development very important. To assist with these six key elements in the project prioritization process is proposed, namely: 1) Define the project vision, objectives and business case, 2) Determine the potential show stoppers, 3) Determine the key value drivers, 4) Track changes and provide regular feedback, 5) Evaluate the alternatives and, 6) Ensure proper gate management governance at the decision point. Incorporating these elements in the project development process will assist in resource allocation and focus on the high value aspects of projects and alternatives during the early stages of the project development lifecycle. Keywords: Resource allocation and focus, vision, show stoppers, value drivers, project prioritization, linear programming, business case modelling, management decision.

Jan 1, 2008

Poorly designed sampling protocols generally result in high project risk by artificially increasing grade variability (ie the nugget effect). Sample collection, preparation and assay protocols that suit the ore type, together with QA/QC systems, will reduce this risk. All reporting codes (eg JORC, 2004) require the Competent Person to consider the quality and implication of sampling and assaying programs. High sampling errors beget higher project uncertainty; despite this fact, sampling does not receive the attention it deserves. The case studies presented show that many sampling issues frequently go unrecognised or unaddressed, resulting in poor project decisions during exploration through to feasibility and production. The overall conclusion is that correct sampling is critical to mining project success and that there is often a need for its optimisation.

Jan 1, 2007

By B. Orgilbayar, B. Unursaikhan, S. Sukhbat, Ts. Zagarzusem, D. Baasanjav, L. Jargalsaikhan, E. Otgonjargal, N. Sugir-Erdene, Ts. Soyolmaa

This study has investigated the efficacy of the gravity beneficiation method based on gravitation and centrifugal forces for manganese ore. Powdered samples of manganese ores from the Unagad deposit in Mongolia were analysed for their element and mineralogical composition using ICP-MS and X-ray powder diffraction (XRD). The analysis presented the mineralogical compositions of the ores as hydro goethite, manganese minerals and magnetite, gangue minerals as quartz, albite, orthoclase and microcline of manganese ore. Manganese minerals are white in colour and have micro-veinlet, fine grained-aggregates associated with gangue minerals. The most important manganese minerals are hausmannite, pyrolusite, rhodochrosite, and manganosite. The composite of feed containing 17.31 % Mn and 36.3 % SiO2 was processed in a shaking table. In the experiment, a concentrate assaying 41.37% Mn was obtained from this composite with 65% recovery. In another experiment, f80=0.074 mm particle size ore was used in the MGS concentration test. A concentrate containing 38.34 % Mn with 75.2% recovery was produced in this experiment. The results showed that it is possible to obtain concentrate through gravity processing of manganese ore, which is an economically beneficial process for producing a product of a standard requirement. Keywords: Manganese ore, gravity separator, centrifuge, shaking table 1. Introduction

Jan 1, 2020

By E. Laine

Rock density determinations are necessary for ore resource evaluations from estimated block grades in g/t. Rock density depends on the mineral composition and, thus, it is specific for each rock type. The rock density distributions for different rock types are often symmetric. Hence, the arithmetic mean is a good approximation for the average density for lithological units. However, there may exist spatial variation in density values due to alteration, fracturing and original heterogeneities such as layering. This study compares the kriged density model with the one with constant density values for different lithological units in the evaluation of metal amounts in rock blocks. The case study consisted of rock densities measured from the drill cores at Ahmavaara PGE deposit in northern Finland. The used Ni contents were simulated in accordance with the spatial distribution of rock densities. The Ni amounts in 2x2x2 m3blocks are higher for the kriged densities than for the average densities. The difference is increasing with the increasing metal amounts due to the nonlinear correlation between Ni content and rock density. The final effect on the resource estimation depends on the cutt off grade and prices of the metal, for example, for a very valuable metal the small differences are significant

Jan 1, 2003

By P. Michalcik, V. Petros, M. N. Bagde, K. Holub

The objective of this paper is to present some results of laboratory experiments during the investigation of stress-strain characteristics of Carboniferous sandstones at dynamic loading. During these experiments increasing frequency and the constant amplitude of dynamic loading and/or constant frequency at different amplitude of dynamic loading were applied. Der Gegenstand dieses Artikels ist, irgendeine von Ergebnissen von Laborexperimenten bei Messung der Spannungs- und Deformationscharakteristik der Karbonsandsteine bei ihrer dynamischen Belastung vorzustellen. Im Laufe diesen Experimenten wurden entweder anwachsende Frequenzen bei konstanter Amplitude der dynamischen Belastung, oder gleiche Frequenzen bei variabler Amplitude der dynamischen Belastung verwendet. L&apos;objectif de ce papier est présenter quelques résultats d&apos;expériences de laboratoire pendant l&apos;enquête de caractéristiques de la tension – deformation de grès Carbonifère à sollicitation dynamique. Pendant ces expériences fréquence croissante et l&apos;amplitude constante de sollicitation dynamique et/ou fréquence de la constante à amplitude différente de sollicitation dynamique ont été appliquées.

Jan 1, 2003

By C. L. de Jongh

The number and scale of backfilling operations in the South African gold mining industry have grown rapidly in recent years. The application of backfilling as a means of stope support in a wide range of geological conditions and mining systems has resulted in the development of a variety of alternative fill systems. Experience gained in the evaluation of operating fill systems has contributed to a knowledge of the essential concepts to be considered in their design. This knowledge can also influence management&apos;s perception of what is expected of a backfilling system. The factors to be assessed in stating and satisfying these objectives are examined. The areas of investigation cover the selection of a suitable material, its preparation, distribution and placement, and the engineering logistics involved in the management of such a system. Finally, the integration of a filling system with an existing mining operation is examined.

Jan 1, 1988