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By F. R. Ploeger, J. H. Crocket

"IntroductionRocks in the Kirkland Lake district form part of the Timiskaming Group, a south-facing homoclinal sequence of wackes, conglomerate, trachytic flows and pyroclastic rocks and syenitic intrusive rocks. Hewitt (1963) indicates that the thickest section, about 5 km, of the Timiskaming Group rocks is attained in Lebel Township. Several writers (Thomson, 1948; Hewitt, 1963; Hyde, 1978; Jensen, 1978; and Downes, 1979) have observed that the Timiskaming Group unconformably overlies the Keewatin volcanics, particularly along the northern contact. Recent work by Downes (1979) in McGarry and McVittie townships to the east of Kirkland Lake has shown that much of what had formerly been classified as Timiskaming actually belongs to an older group of rocks, the Larder Lake Group (Jensen 1978).General GeologyA series of fluviatile, braided-stream sedimentary rocks (Hyde, 1978) form the oldest of the three major rock suites at Kirkland Lake. Conglomerates constitute a large proportion of these sedimentary rocks and typically contain a large percentage of a variety of locally derived alkalic rock clasts as well as the distinctive red jasper iron-formation pebbles (Fig. 1a). The associated wacke units can be massive to finely bedded and are interbedded with the conglomerate. They also contain a large alkalic tuffaceous component.Interbedded with these sedimentary rocks are alkalic extrusive rocks, including tuffs, agglomerates, breccias and flows, which represent episodes of fissure and explosive crater eruption (Cooke and Moorhouse, 1969). The tuffs, although dominantly alkalic in composition, are commonly reworked and contain sedimentary features such as graded bedding, scouring and crossbedding (Fig. 1 b). The trachytic flows are massive to porphyritic and outcrop mainly east of Kirkland Lake in the adjoining townships. Altered leucitic porphyritic flows, locally referred to as red and green spotted trachytes, commonly occur."

Jan 1, 1982

By J. F. Perreault, J. Paraszczak

"The profitability of an underground mine depends to a great extent on the production cost.Random equipment failures and their consequences have significant influence on the total operating cost of a mining system. Having this in mind, a reliability study has been initiated for loadhaul- dump machines in an underground mine. The main purpose of this study is to identify the critical machine subsystems, determine their failure pattern and help work out an effective maintenance strategy. In the first part of this study, the failure data of diesel powered LHDs, gathered during an I8-month period have been analyzed. For the purpose of the analysis, the machines have been treated as systems comprising seven subsystems connected in series. The most critical subsystems, i.e. electrical and hydraulic, were further investigated, and analyzed by graphical and analytical methods. Different failure distribution models were applied and discussed. Basic Defmitions and ConceptsIn order to avoid confusion, several terms used in this paper are defined below, as compiled by O'Connor (1991). The acronymsBS and MIL-STD stand respectively for: British Standard and US Military Standard.Failure: the termination of the ability of an item to perform a required function (after BS 4778).Time Between Failures (TBF): the length of time between two consecutive failures.Observed Mean Time Between Failures (MTBF): For a stated period in the life of an item, the mean value of the length of time between consecutive failures computed as a ratio of the cumulative observed time to the number of failures under stated conditions (after BS 4778).Maintenance, Corrective: The actions performed, as a result of failure, to restore an item to a specified condition (after MIL-STD-721 B).Maintenance, Preventive: The actions performed in attempt to retain an item in a specified condition by providing systematic inspection, detection and prevention of incipient failure (after MIL-STD-721B)."

Jan 1, 1994

By F. Shi

The JKRBT (JK Rotary Breakage Tester) is a newly developed impact breakage testing device for rapid ore breakage characterisation, and has recently been commercialised after a three year comprehensive validation study, involving five major mining companies and six industrialised JKRBT units deployed worldwide. Comparisons of breakage mechanisms and characterisation data between the JKRBT and the Drop Weight Tester (DWT) indicate that, despite the differences in the breakage modes, the JKRBT can provide statistically similar A*b parameters, by using a data reduction procedure which takes into account the difference in the number of contact points, strain rate and potential for secondary breakage. Feedback from the validation sponsors has indicated higher productivity and better repeatability of the JKRBT compared with the DWT. This better precision, combined with the JKRBT’s wider particle size capability and wider specific energy range, provide a more powerful tool, ideally suited to rapid mapping of ore hardness in geometallurgical and comminution applications.

Jan 1, 2012

By G. W. H. Norman

"The Indian Molybdenum deposit occurs in granite near the centre of Indian peninsula, Kewagama lake, in Preissac township, Abitibi county, Quebec, about 40 miles east of Noranda. Quartz veins containing molybdenite were discovered in the vicinity of the deposit in 1901 by J. F. E. Johnston of the Geological Survey of Canada. Innumerable trenches and a few pits were excavated during and prior to the first great war, but there was no production. During the second great war systematic drilling along a favourable zone disclosed by the earlier trenching outlined an orebody of 225,000 tons with a molybdenite content of 0.46 per cent.A 500 on mill was built in 1943, and 91,489 tons of ore underwent treatment, from which 699,568 lb . of molybdenite was recovered. The mill closed down early in 1944 when the wartime need for Canadian molybdenum production eased .GEOLOGYThe general geology in the vicinity of the deposit is shown in Fig. 1. The deposit lies at the north edge of a muscovite-biotite granite mass about 2 miles wide and several miles long. West of Kewagama lake this granite is cut by great swarms of quartz veins . The only other granite in the district known to contain similar swarms of quartz veins, and which similarly has become a source of mo!ybdenite, occurs 20 miles east in La Corne township. The non-molybdenite-bearing granites of the district are either more basic and contain frw dykes except aplite or are distinctly pegmatitic types and contain up to 50 per cent pegmatite dykes with molybdenite only here and there in small amount."

Jan 1, 1954

By René G. del Villar, Jules Thibault, René del Villar

"Some key control variables of industrial processes, associated with product quality, often cannot be measured directly or frequently enough to establish adequate control. In such cases, it is possible to use available measurements to provide a prediction for these process variables and use them in a control strategy, thereby giving rise to what is now commonly called a softsensor.In some industrial grinding circuits, the on-line particle size analyzer is shared between various sampling points. Therefore, for a given location, the actual measurement is only available every 10 to 20 minutes, a delay which is unacceptable for automatic control purposes. To alleviate this problem, a softsensor based on an artificial neural network has been investigated. First, the structure of the neural network and different schemes for the training process are analyzed. Then, the performance of the neural network softsensor is compared with other inferential methods such as ARMA models and Kalman filters.IntroductionGRAHM, French acronym of the Research Group on Computer Applications in the Mineral Industry at Laval University, began in 1990 a research project on Knowledge Based Automatic Control (KBAC). This project, sponsored by a consortium of eight mining companies and the federal and provincial governments, seeked to screen advanced (knowledge-based) methods for data processing (filtering, mass balancing, etc) and automatic control (model-based) for their use in the mineral processing operations and the transfer of the project results to the sponsor companies.In parallel to more academic research work, a number of case-studies have been undertaken with the cooperation of partner companies. Among such works, a very successful one has been the design and installation of a new control strategy for one of the Kidd Creek (Falconbridge Ltd.) grinding circuits. This project was related to the evaluation of a number of control strategies and the implementation of one of them, as selected by the plant management, in the concentrator.A total of sixteen control schemes were evaluated on one of the dynamic phenomenological simulators developed at GRAHM, a trademark of this research group [ l]. The calibration of the simulator models was done based on industrial data gathered by GRAHM and Kidd Creek personnel. Then, the simulator was used to test the performance of various PID-based control schemes, designed to achieve the control objectives set by the Kidd Creek personnel. The best scheme proposed called for controlling the cyclone overflow particle size by manipulating the water addition rate to the cyclone feed box and the circulating load by manipulating the circuit ore feed. The particle size analyzer (PSI-200) available for monitoring the product size, was unfortunately shared (multiplexed) among various streams of the plant, which meant a 14 min delay between two consecutive readings for any particular stream. This induced the plant personnel to choose an alternative control strategy, one which controlled the cyclone feed density instead of the cyclone overflow particle size."

Jan 1, 1996

By Zhongxue Li

This paper reviews an analytical model that defines the relationship of weight-weighted or volume-weighted average haulage distance with bench height and other related parameters, presents the optimum bench heights under various conditions in terms of minimizing the weighted average haulage distance of ore/waste during the full lifetime of an open pit mine, and discusses the truck haulage economics of mining open pits by high bench, specifically by 15 m, 18 m and 20 m benches through marginal analyses. The observations from these analyses disapprove the previous conflicting assertions that the over-all weighted average haulage distance either increases or decreases directly with bench height. It is concluded that: (1) an increase of bench height to 15 m from 12 m is likely to be viable under the general conditions of large-scale deep open pit mines; (2) the reduction of haulage cost is much limited with the case of increasing bench height to 18 m from 15 m; and (3) the feasibility of mining open pits by 20 m benches is generally questionable. These conclusions may serve as a useful guide for those who advocate open pit mining by high bench.

Jan 1, 1995

By Carlos Antônio de Morais, Renata Dias Abreu

The present work describes a study of the separation of terbium and dysprosium from heavy RE concentrate through a solvent extraction circuit in a counter-current system. As the efficiency of the REE extraction by acid extractants rises with the increase of the atomic number of the element, the aim of this work is to extract the elements with higher atomic number maintaining Tb and Dy in the aqueous phase. Thus, terbium was separated first with subsequent separation of dysprosium. The experiments were carried out by using IONQUEST®801 as the extractant and a REE-hydrochloric liquor as feed solution. The optimum operational circuit in terbium separation was comprised of 37 stages: extraction, scrubbing, stripping, and solvent washing. For the dysprosium separation 39 stages were required. Terbium separation over 92% with over 95% purity and a Dy separation over 97% with over 95% purity were obtained.

Jan 1, 2014

By Masatsugu Morimitsu

This paper introduces new technology of oxygen evolution anodes which can be applied to produce copper, zinc, cobalt, and other metals by electrowinning. The anode consists of nano iridium oxide particles dispersed in amorphous tantalum oxide matrix as a catalytic layer formed on a titanium substrate. The anode can reduce oxygen evolution potential by 0.25 to 0.55 V compared to commercially available lead alloy anodes and can suppress unwanted side reactions such as manganese oxyhydroxide, lead oxide, cobalt oxyhydroxide which occur during oxygen evolution in the electrowinning solutions. This technology is effective for environmentally friendly electrowinning processes with low energy consumption and less anodic deposition.

Jan 1, 2011

By Craig Faulkner

Discharge cones for large Semi Autogenous Grinding (SAG) and Autogenous Grinding (AG) mills are subjected to high wear as significant volumes of ground ore and slurry exit the mill. With the larger diameter mills of 32ft to 40ft in size becoming the norm, very high, concentrated wear is highlighting the limitations of conventional discharge cones and frequent changes are subsequently required. This paper outlines the advances made in the design of the Bullnose discharge cone. Superior wear materials to increase wear life over conventional rubber or chrome-moly steel discharge cones and the introduction of key design features to reduce reline times and improve fit and safety during installation, offer significant opportunities for the mill operator. Collated from multiple case studies, the wear data and reline history from 2004 to present clearly illustrate the way in which superior component longevity has reduced the frequency of relines over the life of the product to increase mill availability and effectively increase the tonnes milled in a period.

Jan 1, 2012

By Mario Bureau

Need for a lab assembly reaching better and consistent static anchorage capacities

May 1, 2013

By S. Avalos, J. M. Ortiz, W. Kracht

Semi-autogenous grinding mills are intensive energy consumers. Current models base their energy consumption inference on operational variables and feeding ore characterization. While they provide adequate design guidelines, they are not suitable for real-time energy forecasting dealing with gaps in operational dataset and up/downstream process bottlenecks. This work explores the capability of Gated Recurrent Units to learn the semi-autogenous grinding mill consumption behaviour. Gated Recurrent Units are trained to forecast different time-support consumptions under a time-series operational dataset. The results show high performance on small supports (30 minutes) to capture local variability and long-trends while larger time supports (8 hours) can only capture time-trends but not local variability. The proposed technique seems promising for further research and implementation on real mine cases since the input variables are low-cost and easy to obtain. INTRODUCTION Current changes in the Chilean energy matrix (Román-Collado, Ordoñez, & Mundaca, 2018), from fossil fuels to renewable energies, have impacted different industries and particularly the mining sector. Solar energy incorporation into greenfield/brownfield projects will help reducing costs and will lead to rethink foundational paradigms (production and processing strategies) (Pamparana et al., 2017). Also, integration of new space-time predicting tools together with automated real-time updating models are some of the main challenges in the geometallurgical framework (Ortiz et al., 2015; van den Boogaart & Tolosana-Delgado, 2018). Those contexts encourage and demand the development of tools capable of predicting the energy consumed by mining systems, being comminution the greatest energy consumer with an average close to 50% of the entire mine consumption (Cochilco, 2013). In comminution, the semi-autogenous grinding mill (SAG) represents the largest energy consumer (~10 nominal each SAG). Theoretical and empirical energy consumption models (Jnr & Morrell, 1995; Morrell, 2004; Silva & Casali, 2015) base their inferences mainly on feed/product size distributions, SAG sizing, bearing pressure, feed hardness, water addition and grinding charge level, and commonly assume steady-state and work isolated from up and downstream processes. While those techniques provide adequate design guidelines, they are not suitable to predict hourly, daily or even weekly energy consumptions on interconnected comminution circuits where upstream/downstream bottlenecks lead SAGs to operate below designed regimes. Forecasting energy consumption is required by short-term energy management, medium and long-term planning energy consumption, designing the nominal capacity of renewable energy sources, among other. Also, when models are input-sensitive and some of those input measurements are expensive and/or time consuming, model robustness suffers when real-time predictions are required.

Jan 1, 2019

By Alireza Sarafi, Alijan Aftabi

"A hydrocyclic system used for mineral separation at the laboratory scale results in the separation of more than 90% of micas. The system functions only by water and might offer advantages where other methods of mica separation are not available. INTRODUCTIONVarious methods for the separation of micas, wollastonite, and garnet, e.g., screening, flotation, magnetic separation, and heavy liquids, are well known (e.g., Spence, 1929; Bates,I960; Gillson et al., 1960; Benjamin, 1971; Connor and Kolhnar, 1991; Collings and Andrews, 1991). However, where these methods are not available, the separation of micas by a hydrocyclic system developed by Sarafi and Aftabi (1991) may prove to be economic. This note is a brief description of the hydrocyclic system. Minerals and MethodFor testing the recovery of mica and other minerals from different rocks (garnet-mica schist, skarn, and pegmatite), standard minerals were tested first, and then rock samples. Pure mineral standards were prepared from coarse-grained samples of pegmatite, mica schist and skarn; the grain size of the minerals separated was more than I cm. The Hydrocyclic System and Mineral SeparationThe hydrocyclic system is shown schematically in Figure 1. In the first step in mineral separation, mineral and rock samples were crushed, milled, and then sieved to minus 250 plus 125 microns. Approximately 10 gm to 25 gm of the sample were inserted in decanter Dt • The motor pwnps, M1 and M2, were then turned on and the water valve rl was opened. At this time, water was flowing turbulently (30 em3/sec. to 50 em3/sec.) and minerals were separated according to their crystallographic nature, density and!or habit. The fInal separation was done by exit valves r2, r3 and r4, while the motor pwnps were still operating. After each experiment, the rt , r2' r3 and r4 valves were closed and the motor pumps were turned off. Following this, minerals in each decanter and the mter were collected, dried and weighed. The whole time of the experiment was optimized to be about 10 minutes, but varied from 3 to 15 minutes for micas and garnets. respectively."

Jan 1, 1994

By David Dreisinger

Arsenic occurs in nature in association with many valuable metals including copper, nickel, cobalt, gold and platinum group metals. The recovery of these valuable metals is of course complicated by the need to extract and stabilize arsenic in a form suitable for disposal. In this paper, a review of some recent developments related to hydrometallurgical treatment of arsenic bearing materials is provided. The key aspects of metal dissolution, arsenic stabilization and disposal are discussed.

Jan 1, 2014

By A. Suzue, T. H. Okabe, Y. Taninouchi

Methods for the physical separation and enrichment of platinum group metals (PGMs) from autocatalyst scrap were studied in order to develop an environmentally friendly and efficient recycling process. In general, an autocatalyst has a honeycomb-structured ceramic substrate that is coated with a catalyst layer containing platinum (Pt), palladium (Pd), and rhodium (Rh). Therefore, physical separation of the PGM-containing catalyst layer directly from the ceramic substrate is favorable for upgrading the autocatalyst scrap. In this paper, the authors present a scrap-upgrade process consisting of electroless iron plating and magnetic separation techniques. Iron was plated on the surface of a catalyst sample used to represent an autocatalyst, which was then crushed and magnetically separated. The Pd in the catalyst sample was successfully extracted and concentrated in the magnetic powder. Under certain conditions, the process increased the Pd concentration by a factor of 4 and recovered 89% of the Pd in the autocatalyst sample.

Jan 1, 2014

The successful application of color sorting machines has established sensor-based sorting in the mineral industry in recent years and is considered today as a significant innovation in processing technology. However, we are only at the beginning of (market) introduction. New sensor systems have been developed, which exploit material properties such as electrical conductivity, magnetization, molecular structure, thermal conductivity etc. This opens up new exciting pre-concentration and upgrading possibilities for many applications such as nickel, gold, copper and other ores as well as for industrial minerals, diamonds and other gem stones.

Oct 1, 2009

By Lawrence Devon Smith

What is a Failed Project? For mining projects, some key indicators of a ?failed? project are: ? Cost is more than it should be (particularly capital) ? Schedule ? It takes longer to build than expected ? It takes longer to ramp-up than expected ? It does not do what it is supposed to do ? Poor performance; output, product specifications; ? Low revenue ? High costs ? No one is happy about it: Management, Shareholders, Bankers ? Does a project fail if it does not meet expectations that were unrealistic and unattainable? ? Caution: Failure may not become evident until years later

May 1, 2010

By H. Wotruba, K. Neubert

Dual-energy X-ray transmission (DE-XRT) imaging is known from safety luggage inspections at airports. The use of DE-XRT technology for sorting applications in the primary raw materials industry has been the subject of numerous investigations. Beside other metal ores, X-ray transmission sorting is already used for the preconcentration of tungsten ore, gold ore and coal. The applicability of DE-XRT sorting is limited to ore types where differences in metal concentrations are measurable, based on an interpretation of X-ray images. Metal contents in particles occur in large varieties in terms of concentration, grain sizes, spatial distribution and mineralogy and therefore influence the X-ray absorption. As a result, each ore has to be tested individually for its suitability for DE-XRT sorting. The objective of current research at the Department of Mineral Processing (AMR) at RWTH Aachen University is to assess parameters influencing the detectability of rare earth oxides. Two approaches were followed: (1) Practical test work, based on artificial ore samples of defined compositions and (2) Computer-based simulation of absorption features of identical particle compositions. In total, more than 300 artificial samples of various compositions and metal grades were produced and X-ray images from DE-XRT sorting were analyzed. Results from the DE-XRT sensor were put into correlation with metal grades and particle sizes, to analyze influences and limits on the detectability of rare earth oxides. In addition, a new approach was tested in which the X-ray absorption of particles of various compositions was determined based on a Monte Carlo (MCNP) simulation. During the simulation, similar compositions, as used for the artificial samples, were tested and the X-ray absorption behavior during DE-XRT sorting was determined. A comparison of results from both approaches is used to assess the applicability of the MCNP-simulation for the prediction of the X-ray attenuation behavior during DE-XRT sorting.

Jan 1, 2016

By O. Guyot, A. Broussaud, M. Revalor, G. Legrand, D. Kok, E. Roux

"The paper describes the advanced grinding control system implemented at Newmont Ahafo gold mine, Ghana in 2009 and 2010. It shows how the different components of the Advanced Process Control (APC) system cooperate for increasing plant performance.The SABC circuit processes hard rock from different pits mixed with a variable proportion of oxides. The control strategy is designed to address specific disturbances, including start/stops of pebble crushers, unavailability of oxides, changes in rock size distribution resulting from segregation in the stockpile, and changes in ore type and hardness.The system consists of an expert system per se with extensive use of fuzzy logic, supplemented by an online dynamic model of the process used as a soft sensor, a VisioRock™ rock size measurement system over SAG mill feed before addition of recycled pebbles, and an AudioMill™ system to analyze the SAG mill sound and detect impacts on liners. All these components are embedded in the same OCS© software platform, which, among other benefits, makes it easy to support the entire system remotely. The paper details the physical constraints and the variables that are manipulated. It describes the control strategy and the contribution of each component of the system. It also describes the project implementation and the performance of the system. In addition to a strong involvement and support of management, the very good acceptance of the operators has been facilitated by the remote access system that made it possible to immediately modify the system each time it was needed during the baby sitting phase.The system made it possible to increase gold production significantly through increases in tonnage and recovery thanks to a better control of the grind size through a stabilization of the secondary ball milling circuit and an improvement of the operating conditions of the classifying cyclones."

Jan 1, 2012

By W. Dan Hausel

"Hundreds of diamonds have been found in the United States. The majority of the discoveries occurred during the 19th century as a by-product of placer gold mining. Most of these early diamond finds have no known source, and in many cases are situated in areas unfavorable for diamond exploration based on current models that require kimberlite or lamproite to be emplaced in a stable Archean craton or Proterozoic craton margin.Diamonds have also been recovered in situ from lamproite at Murfreesburo, Arkansas, from kimberlite in the Lake Ellen region of Michigan, and in several kimberlites in the Colorado–Wyoming State Line district. Unverifed reports also suggest that diamonds may have been recovered from other related intrusions at a number of localities in the United States.IntroductionTo date, diamonds have been recovered in situ from kimberlite in the Colorado–Wyoming State Line district and from a kimberlite in Michigan. Additionally, diamonds have been recovered from lamproites in Arkansas. Diamonds have also been reported from kimberlite in Kansas, and from peridotite in New York and Maryland. However, these latter reports have not been verified."

Jan 1, 1995

By J. Baumbach, H. Bombach, M. Stelter

"Today technical electro-refining processes for copper exclusively use sulfuric acid, for silver refining nitric acid electrolytes are used. Sulfuric acid is characterized by very good chemical and electrochemical stability, good conductivity and low cost. The disadvantages of sulfuric acid are the precipitation of fine-grained cathodes with smooth surfaces only by using additives like glue, thiourea and chloride. In case of silver the electrolyte is electrochemical unstable and bears the risk of the formation of toxic NOx when pH is too low. A second disadvantage is the form of electrodeposition of silver as dendrites with their removal from the bottom of the Möbius cells.This paper reports the results concerning the application of an alternative electrolyte in copper and silver electro-refining. At first the electrolyte was characterized by the determination of current density potential curves. Electrolysis experiments were performed in laboratory scale using technical anodes for copper and synthetic anodes for silver. During the copper tests the solubility of contaminations from the anodes and the amount and chemical composition of the anode slimes were determined. Moreover the influence of current density, electrolyte temperature and the effect of several additives on the precipitation and chemical purity of the cathodes were investigated. In all experiments cell voltage as well as anodic and cathodic polarization was measured and current efficiency and specific energy consumption were calculated. A comparison with the results with those of tests using conventional sulfuric acid electrolyte shows the advantages and disadvantages of both systems, additionally the technical application chances and limitations for the new electrolyte. This electrolyte enables the precipitation of smooth copper cathodes with low silver and sulfur concentrations even at lower temperatures without any additive. For silver refining the electrodeposition of compact silver sheets is possible, that can be stripped comparable to those in copper electro-refining."

Jan 1, 2016