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By L. Jones, S. R. Lawrence, A. R. Holloway

Whilst dense medium separation is best known for its ability to concentrate diamond and coal deposits, the process is now being employed in southern Africa as a pre-concentration step to improve the economics of platinum group metal and nickel ores. DMS plants built for these industries (such as the 1600tph unit at Tati Nickel, Botswana), are spearheading an expansion in this area by reducing mine and process operating costs yet maintaining economic metal recoveries. This paper provides an overview of DMS technology and examines the economic benefits available to North American operators and projects, with recent case studies as reference.

Jan 1, 2009

By J. Stiksma, R. Kalanchey, M. J. Collins, G. Owusu, R. Raudsepp, K. R. Buban, L. A. Barta, I. M. Masters

This paper describes the results of testwork for the treatment of Ambatovy laterite ore by a pressure acid leach process, with recovery of the soluble nickel and cobalt values as mixed sulphide intermediate by precipitation with hydrogen sulphide, and subsequent refining of the mixed sulphide to nickel and cobalt metals. These process development studies were carried out primarily in 2004, as part of a bankable feasibility study for the Ambatovy Nickel Project. The Ambatovy orebody is located in Madagascar. The mini pilot plant testwork was carried out in the Dynatec metallurgical laboratory in Fort Saskatchewan, Alberta. The results of the testwork were very encouraging, including nickel and cobalt extractions in the range of 95.5% to 97.0%, and 94.0% to 97.0%, respectively, in the ore leach step with sulphuric acid. High recoveries of nickel and cobalt were achieved throughout the remaining process steps, yielding separate nickel and cobalt metal powders with better than acceptable purity.

Jan 1, 2005

By Michael E. Charles, Jaroslav J. Vocadlo

"The hydraulic transport of solids through pipelines can have many advantages over other modes of transport. Numerous successful applications both within plants and over longer distances have demonstrated the technical and economic feasibility of slurry pipelining. Solids successfully transported include kaolin, coal, iron ore, gilsonite and limestone, and others, such as sulphur and potash, are likely to be transported in Canada in the near future. However, though the technology of solids pipelining is quite advanced the underlying principles have not yet been formulated past the semi-empirical stage. The main objective of this paper is to present a discussion of the important technical and economic considerations in the design of so lids pipeline systems by reference to typical data. The Worthington slurry pumps and pilot facilities are briefly described."

Jan 1, 1972

By H. Salamanca

Recently, the mining industry has become one of the leading target markets for the technology industry as they need to innovate in their productive processes in order to boost productivity, reduce operation costs, increase operation safety, and improve the quality of life of their workers. This work presents the technological developments that HighService has done in different stages of the mining productive processes to include robotic manipulators in their automation solutions as well as the development of new equipment and sensors. The robotic technology integration is presented in different applications such as handling and selection of cathodes in E-W machines, automation of base plate maintenance, automation of cathode stripping machine, and multi-tools handler for liner bolt replacement in SAG mill liner maintenance activities. The proposed solutions show technical and economical viability with low initial investment and short implementation period of six (6) to ten (10) months. The results have been validated in plant, obtaining higher production rates and availability.

Jan 1, 2007

By S. Bozorgi, K. Anders

"The automotive applications of heat treatable AlCu cast alloys are designed for performance at high temperature, which can be improved using specially alloying element as well as different heat treatment. In this research work an effect of alloying element such as Cu, Ni and heat treatment on microstructures and mechanical properties of AlCu alloy were investigated using optical microscope (LIMI), scanning electronic microscope (SEM) equipped with energy dispersive X-ray detection (EDS), Differential scanning calorimetry (DSC) and mechanical testing. It was found that during solidification most of the elements Cu, Mg and Ni segregated at the grain boundaries in the form of Al2CuMg or Al7Cu4Ni and a very small part of Cu and Ni element dissolved in the FCC-Al matrix. The latter is not completely reclaimable for strengthening mechanisms in FCC-Al matrix in its as-cast state. The results of mechanical test show that yield strength and ultimate tensile strength increases after heat treatment significantly compared with the as-cast state. Furthermore the mechanical properties at elevates temperature (240°C) is higher with higher Cu+Ni+Si containing alloys compared with the less Cu+Ni+Si containing alloy.INTRODUCTION Due to the high strength-to-weight ratio, high strength and ductility at room- and elevated temperature, AlCuSi cast alloys are widely applied in the automotive industries specially for producing cylinder head and engine block, where modified alloys with enhanced metallurgical properties are always needed to satisfy the ever increasing demands for the applications. The AlCu based cast alloys can be strengthened by age hardening. The precipitation processes from which this hardening is derived can be attributed to the presence of selected trace element additions or micro alloying, which can change the process or kinetics of precipitation in age hardenable AlCu cast alloys (Polmear, 1998; Morris, 1991). Furthermore their strength is mainly controlled by the aging process through the precipitation and growth of very fine precipitates of the ?'-phase (a semi-coherent, metastable form of the equilibrium Al2Cu phase) from the Al and Cu Guinier-Preston (GP) zones. Several studies have shown that solute clustering occurs prior to the precipitation of GP zones, and this modifies both the nature and kinetics of the precipitation process. The typical size of GP zones is in the order of tens of nanometers, and the chemical composition of these precipitates is not easily measured, even with a typically analytical electron microscope (Polmear, 1989)."

Jan 1, 2018

By M. Vaillé, B. Bossé, N. Durupt, A. Michaut

Imouraren is a sedimentary uranium deposit (> 150,000 tU @ 800 ppm), located approximately 100 km North-Northwest of Agadez (Niger); its depth reaches 110 to 170 meters. For low-grades ores, heap leaching is commonly considered as the appropriate technology for metal recovery. More precisely, the ore is crushed (≤ 300 mm) and agglomerated before being stacked. In this case, sulfuric acid can be added during agglomeration and/or irrigation (for three months to a year) to improve uranium recovery. It is known that mineralogical, chemical and physical properties of the uranium ore impact recovery, yet many challenges remain to increase recovery using this process. For example, ore heterogeneity and spatial variability (e.g., variation in uranium, carbonate and/or clay contents) can affect heap leaching performances (i.e., metal recovery, acid consumption or neutralization, percolation rate). However, laboratory column tests using composite ore sample that do not consider ore heterogeneity are widely used to anticipate recovery. Consequently, a new approach that consists in using Imouraren drill core ore samples was recently investigated. This latter also enabled a better assessment of the main parameters that influence uranium recovery and proposed a new predictive model to optimize mining operations.

Jan 1, 2020

By L. Li

ABSTRACT Stope backfilling is a common operation in many underground mines, which requires a barricade at the base of the stope near the drift entrance to retain the backfill in place. In this paper, the distribution of pore-water pressure in barricades made of waste rock is analyzed. An analytical solution is introduced and applied to estimate the pore-water pressure along the base and full height of the barricade. Results show that the analytical solution generally accurately predicts the distribution of pore-water pressure obtained from the numerical calculations, especially in the upstream part of the barricade, where it is most critical.

Jan 1, 2013

By S. Abu-Samra

By virtue of its complex nature, the construction industry comprises a wide spectrum of interrelated variables and factors. This multifaceted character of the construction industry puts the use of engineering modeling tools and techniques on top of project management necessities. This research introduces a macro-level earthmoving management system using Genetic Algorithms (GAs) to reach the optimum allocation of earthmoving equipment. The Earthmoving Equipment Management System (EEMS) functions through four integrated modules: (1) A Central Database containing information about projects and available equipment; (2) An Equipment per Segment Selection module that calculates the cut and fill quantities, plots the Mass Haul Diagrams, and selects the equipment types to be used for each segment; (3) An Equipment Pool module which determines the production and cost for each available equipment, based upon the project site conditions; and (4) An Optimization Engine equipped with a GA optimization solver. This engine formulates the optimum earthmoving cost for all projects, by changing the number of allocated equipment. The Optimization Engine takes into account the number of available equipment and calculates the weekly equipment allocation. The EEMS model was implemented on an earthmoving company conducting five different projects on hand. The model proved to be an effective tool in providing decision makers with optimum equipment utilization on a multi-project scale to minimize the earthmoving cost. The results were then compared with the company?s existing micro-level management system, demonstrating better performance on the level of savings, amounting to 13% of total earthmoving cost.

Aug 1, 2013

By H. J. lgner

Hydraulic fills are widely used in the tabular, steeply dipping stopes of the South African gold and platinum mines as an integrated process within a daily cycle of drill and blast. There is therefore only a small time window in which to fill the geotextile bags used as primary fill containment, without the risk of loosing production. Consequently, mines tend to increase the flow rate to the stopes, although this compromises adequate drainage, consolidation and strength development during filling. Recent underground measurements inside the geotextile bag have revealed that at high rates of rise and at 25 degrees dip, the backfill can remobilise within a limited area inside the geotextile bag during filling. This sudden downward surge of backfill exerts, for only a few seconds, additional loading on the geotextile, its supporting mesh and the props. This unstable behaviour poses a serious threat as it can push props out of place, thereby damaging the geotextile bag and causing a mud slide in the stope. To reduce the risk of accidents, the phenomenon of sudden slumping was further investigated for various filling conditions in the laboratory. The results confirmed that the maximum pressures associated with the sudden slumping can be more than five times those experienced during steady-state consolidation. Based on this new insight, the current best practice for hydraulic backfilling was critically reviewed. A practical approach to implementing meaningful standards is presented to ensure safe operations in relation to the consistency of the backfill quality and the appropriate matching of geotextile characteristics with backfill properties.

May 1, 2007

By P Hulteberg

In this article, an integrated catalytic reactor design approach to produce PEMFC-quality hydrogen is evaluated. The design is based on a high level of heat exchanging perfonned internally, highly active noble metal catalysts and a woven wire mesh catalyst support system. It consists of an integrated steam refonner and a catalytic burner section, a water gas shift section and a preferential carbon monoxide oxidation section. The reactor design is described and experiments perfonned to evaluate the two reactors built are reported. The two reactors have a maximum output of 3 Nm and 10 Nm3 hydrogen/h respectively. In the larger unit, a total of six fuels, three gaseous (methane, natural gas and liquid propane gas) and three liquid (naphtha, ethanol and methanol), were evaluated. The larger unit was also used to investigate how variations of parameters such as steam-to-carbon ratio in the steam reforming part of the system and the relation between oxygen and carbon monoxide in the preferential carbon monoxide oxidation affect the reactor perfonnance. The smaller unit was used, after implementing automatic control, to run a system life time test for 480 h. The refonner system perfonned according to specifications on almost every aspect.

Jan 1, 2005

By M. Abdellatif

Successful demonstration of The Mintek Thermal Magnesium Process (MTMP) was achieved in November 2004 at the pilot-scale, About 30 tons of magnesium producing recipe was smelted in the DC arc furnace over a continuous operation of 8-days, Twenty-two furnace batching-tapping operations were carried out at a feed rate of 525kg/h and a smelting temperature of 1600-1700°C, The MgO content in the produced slag was as low as 6,7%, and averaged 9,2% MgO, resulting in an overall magnesium extraction of 77%, which reached 87% during good operating periods, Magnesium vapour was extracted at a rate of 70-85kg/h and was delivered to the condenser that was operated at 680-720°C, The magnesium was captured in the condenser crucible in a liquid state, allowing its prompt tapping, More than 3500kg of crude metal were produced over 15 on-line metal tapping operations, On average, a condensation efficiency of 85% was achieved during the entire testwork, which peaked at 87% during steady operations, The quality of the crude metal was similar to, if not better than, that of the Magnetherm's crude magnesium, A pre-feasibility study has indicated that the MTMP has the potential for lower capital and operating costs as compared to the electrolytic process, and therefore Mintek and its consortium partners are exploring opportunities for a commercial production facility.

Jan 1, 2006

By Mosquera. J.

Tailings Storage Facilities (TSFs) are vast structures that respond to site-specific characteristics, rate of production, placement techniques, and the physical and mechanical properties of tailings. As a common denominator, TSFs are in some degree vulnerable to failure due to liquefaction, poor management, slope instability and/or unusual climatic events. In practice, stability of TSFS is determined by calculating a minimum Factor of Safety (FOS) using the Limit Equilibrium Method (LEM). However, it has been proven that relying exclusively on the limit equilibrium approach is not accurate because it is basically a static method that does not take into account the stress-strain distribution and displacement experienced by the constitutive materials of a TSF. In order to overcome these limitations of the LEM, the finite element method - Shear Reduction Technique (SRT) has been used as a more reliable tool for TSFs stability assessment. This paper presents a comparative stability analysis between an upstream tailings storage facility (UTSF), and a water retention tailings dam (WRTD) under static and pseudo-static states using simplified and rigorous LEMs and the SRT. Additionally, and taking into consideration the intrinsic uncertainty of tailings properties, sensitivity and probabilistic analyses in the form of Monte Carlo Simulation (MCS) and the Point Estimate Method (PEM) are applied to determine the Probability of Failure (Pf) and Reliability Index (ß) of each TSF. It is shown that the friction angle of UTSF?s foundation and the core?s cohesion of the WRTD are the main variables that govern stability. Further analysis shows that the WRTD has a higher reliability index and a lower probability of failure than the UTSF.

Aug 1, 2013

By Steve Custer, Chris Bennett, Patrick Garretson, Glenn Dobby, Jacques McMullen

"Barrick Gold is in the process of expanding one of its grinding circuits at the Goldstrike property as a response to both increasing ore hardness and increased ore sensitivity to finer grinding as it relates to gold recovery. The plant currently operates with two parallel grinding lines, each with a SAG mill, a pebble crusher, and a ball milling arrangement. As part of determining what additional equipment was to be required, a CEET evaluation program was conducted (CEET is an acronym for Comminution Economic Evaluation Tool). The work included: Development of a hardness ‘model’ for the ore body, as described by SAG Power Index and Bond Work Index;Site benchmarking surveys to fine tune the SAG and ball mill calibrations within CEET;Conducting CEET studies to examine the process options;Comparing CEET results to standard grinding circuit design techniques.The recommendation of the study, presently being implemented, is the installation of an additional ball mill on one of the two grinding lines. This paper reviews the sizing techniques applied, providing a CEET case study for circuit performance analysis and circuit design. OVERVIEW OF COMMINUTION AT GOLDSTRIKEOre feeding the autoclaves at Goldstrike are first processed through two parallel grinding lines. Both lines use SAG mills with cone crushing of pebbles followed by ball milling. A summary of the key circuit parameters is provided in Table 1. Line 1 primarily processes underground Meikle ore, although when no Meikle ore is available, it processes open pit Betze ore. Line 2 processes Betze ore exclusively. The Mill Line 1 P80 objective for Meikle ore is 74 microns. According to the recovery optimization analysis, a P80 of 90 microns was recommended for Betze ore. The potential however exists to perform co-mingling of both ore types and feed the higher grade Betze ore to Line 1, in which case the P80 of 74 microns would be retained."

Jan 1, 2001

By V. A. Leão, A. M. Silva, S. M. Bertolino, B. C. S. Ferreira, D. Guimarães

Although not considered a high risk pollutant as compared to toxic metals and acidity, environmental agencies worldwide are proposing regulations to control sulphate in effluents and drainages by setting a threshold value varying between 250 mg/L and 500 mg/L. The aim of this study was thus to compare four different techniques for removing sulphate ions from mining/metallurgy effluents. The first alternative studied was sulphate removal by precipitation as ettringite. Treating a synthetic solution containing 1650 mg/L sulphate at 22±1 ºC resulted in removals close to 85% during continuous precipitation. Sulphate sorption was also investigated using three different ion exchange resins as well as limestone. Fixed bed experiments produced sulphate loadings of up to 70 mg SO4 2-/L resin, at pH 2.0. In neutral wastewaters, limestone is also a potential adsorbent producing a maximum particle loading of 19 mg/g. Sulphate sorption on limestone seems to be an alternative to treating mine waters with sulphate concentrations below the 1200-2000 mg/L range, where lime precipitation is not effective. Subsequently, sulphate removal by sulphate reducing bacteria was also investigated and it was observed that reactor’s hydrodynamic conditions and the choice of substrate are important factors for the process. The different technical aspects of each technology are addressed.

Jan 1, 2014

By D. Michaud, C. Bazin, S. Lévesque, L. Pérez-Barnuevo, H. Longuepée

In recent years, with the emergence of Geometallurgy, a great effort has been made to characterize ore resources as early and accurately as possible, to allow better design and a more efficient operation of mineral processing circuits. In this context, core logging plays an important role, since drill cores provide the first insight into the ore characteristics. However, to satisfy geometallurgical requirements, traditional core logging does not suffice. New tools and methodologies need to be developed for the automation of core logging and the acquisition of mineralogical data better related to mineral processing performances. In this paper, a methodology for the geometallurgical characterization of drill cores is proposed, based on the drill core textural patterns. Textural pattern is defined here as the macroscopic spatial arrangement of minerals. The Mont-Wright iron ore deposit (Quebec, Canada) is used as a case study. The first part of this work aimed at analyzing the potential link between the iron ores textural patterns observed in drill cores and their response to ore processing, namely comminution and concentration. Preliminary results show similar performances in terms of energy consumption and heavy liquid separation for samples showing the same textural pattern. In the second part, this work seeks to develop a methodology for the automated identification of drill core textural patterns by the application of digital image analysis and discriminant function analysis. The results obtained show that this methodology is able to discriminate between the textural patterns identified at Mont-Wright with a good rate of success. Therefore, this work lays the foundation for the development of a new drill core characterization tool, which would allow for the early prediction of the iron ore behaviour during mineral processing through the identification of drill core textural patterns.

Jan 1, 2016

By M. Maley, S. Burling, R. Ring

ABSTRACT The numerous global uranium deposits vary significantly in mineralogy, grade, and textural characteristics; therefore, information from traditional (or conventional) sources on the fundamentals of leaching uranium and gangue minerals is not always applicable when studying particular ores. Empirical studies can be effective in understanding leach systems and can lead to improvements in process design but there remains a lack of fundamental understanding necessary for ongoing process optimization as ore bodies continue to vary. ANSTO Minerals has undertaken a work program to address several fundamental questions about uranium leaching, including the unexpected impact for some ore types of leaching at high oxidation potential.

Jan 1, 2012

By A. J. Makoka, B. C. Qi

Reliable monitoring of corrosion is vitally important in the combat against corrosion and over the last two decades the interpretation of electrochemical noise has received considerable attention as a means to discriminate between different types of corrosion. To this end, many different analytical methods have been proposed, such as power spectral density analysis and analysis via various other stochastic criteria. However, although many corrosion systems are nonlinear and therefore not readily interpretable by the abovementioned analytical approaches, few studies in the analysis of electrochemical noise to date have exploited advances made in the analysis of nonlinear systems. In this paper, the use of phase space methods to analyze and detect change in corrosion systems via electrochemical noise is considered. In particular, the electrochemical noise data are used to reconstruct trajectories in the so-called phase space of the system and changes in the topology of these trajectories or attractors as represented by correlation dimension curves are consequently interpreted as an indication of change in the dynamics of the system.

Jan 1, 2005

By L. Li

Backfill is increasingly used in underground mines, as it can help reduce the environmental impact from mining operations. However, the primary objective of backfilling is to provide safe working space for miners, by improving ground stability conditions. As cement is often added to the backfill, a critical issue is the determination of the required backfill strength (cohesion) due to the binder. This value is usually obtained from a solution proposed by Mitchell and co-workers, in the early 1980?s, for stopes with an exposed backfill face. This paper presents a brief review of the Mitchell et al. solution, with some of its main limitations. Some of the recently developed solutions for backfill design are then summarized and discussed.

Aug 1, 2013

By D. M. Aloi

In today's evolving and globalized world, mining companies are being pressured to move beyond compliance towards long-term sustainability and sustainable development. Companies are expected to "engage" with communities and measure the success of these engagements without a clear understanding of "how" to do this. This move, away from "Corporate" Social Responsibility (CSR) and compliance, develops more of a focus on "Community" Social Responsibility and sustainability. This shift in focus leads to the development of world-class projects that provide sustainable development for people, reduces the incidence of costly delays, and promotes good global citizenship for corporations. The process of "engaging" communities in mining project design and development leads to a stronger license to operate and sustainable development. To create this mutually beneficial relationship between communities and companies, communities must be "engaged" in the mining process as early as possible, preferably during the exploration or the concept phases. How to create this "engagement" remains elusive. How to measure the progress of this engagement is also problematic. The quantitative and qualitative metrics needed to measure both positive and negative impacts of the mining and community relationship will be discussed.

Jan 1, 2007

By Harry J. Cain

Introduction The property of Pioneer Gold Mines of B. C., Limited, is located in the Lillooet mining district of British Columbia, on Cadwallader creek, 54 miles distant by motor road from Shalalth, a station on the Pacific Great Eastern railway. Milling by the present Company was commenced in 1924, a small amalgamation plant, consisting of a crusher, Bryan mill, and plates being operated until 1928. Tailing from this plant was impounded and later treated in the 100-ton continuous counter-current decantation cyanide plant which was erected during 1927-28 and placed in operation during May of 1928. A second cyanide plant, employing continuous counter-current decantation, having a nominal capacity of 200 tons, has been erected during the past few months and was put into operation during September of the present year. The ultimate capacity of the combined units of the present mill has not been determined, but it is expected to be much in excess of the rated capacity. The Ore The ore, as received at the mill, consists chiefly of quartz carrying free gold, with small amounts of pyrite, arsenopyrite, and pyrrhotite in evidence, though probably amounting to less than one per cent of the total. Some gold is very closely associated with the sulphides. The country rock is a basic igneous rock, probably an augite diorite. Near the vein it is highly altered to sericite, which slimes readily on grinding, and does not settle very well. The quartz is of two types, clear and ribbon. In the latter, the ribbons, which are not much thicker than paper, consist of shattered sulphides. In crushing this ribbon quartz, breakage is often along the streaks, exposing these shattered faces to advantage in subsequent treatment. While gold is the metal for which the ore is mined, some silver is also present and is paid for by the mint. It is, however, unimportant from a commercial viewpoint. From the standpoint of crushing and grinding, the ore might be termed 'medium 'hard'.

Jan 1, 1932