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By John C. Loretto

"Answers to some of the problems ofRecovery and Metallurgical AccountingIn Gold and Silver Hydrometallurgical PlantsThe start-up over the last few years of new hydrometallurgical plants for the recovery of gold and silver has brought to the surface again a number of problems. Most of the problems have existed for some time and they manifest themselves mainly in two ways. Firstly, the plant results do not agree with the Metallurgical Test work figures and secondly, the Metallurgical Accounting figures do not balance.The plant results not agreeing with testwork figures are mainly due to:a) The testwork samples were not representative of the eventual plantfeed;b) Misinterpretation or misunderstanding of testwork;c) Plant losses;d) Plant design not allowing testwork results to be achieved;e) Operating deficiencies.a} The testwork samples being dissimilar to the plant feed occurs on a very high proportion of projects. The effects of this can beccr.ie exaggerated because the upper levels of the mining company often regard the original testwork figures as sacred and therefore base their judgement of current plant performance on these figures.Frequently the test work samples represent only a minor part of the orebody or alternatively a single composite of the whole ore body is used for the testwork long before it has been determined that all of the potentially different ore zones behave in the same manner. These errors can be compensated for by repeating the ""testwork tests 11 on current plant feed on a routine basis and using these tests to determine whether or not the plant is operating satisfactorily."

Jan 1, 1982

By Gaston Giuliani, Jérome Massot, Didier Bourlès, Lionel Siame

"Abstract - We present a new approach for the evaluation of the potential of emerald reserves in gem projects using beryllium (Be) mobility. The distribution of Be in the different phases of hydrothermally altered (albitized) black shale hosting Colombian emerald deposits indicates that Be mobility is associated with the breakdown of Fe-Mn oxyhydroxide phases. The amount of Be that can be mobilized (~0.7 x 10-6 g/g; i.e., 0.7 ppm) may represent up to 18 wt% of the total Be contained in the black shale. A mass balance calculation applied to a well-constrained alteration zone of the Chivor mines, and based on the quantification of Be that can be mobilized under hydrothermal conditions, gives an estimate of the total gem reserves of these mines. Resumé - Une nouvelle approche, basée sur la mobilité du béryllium (Be) pour l’évaluation des réserves d’émeraude dans des projets d’exploitation de gemmes est présentée. La distribution du Be dans les différentes phases minérales de schistes noirs hydrothermalisés (albitisés) qui contiennent les gisements d’émeraude colombiens, indique que le Be mobilisable se trouve dans les oxyhydroxydes de fer et de manganèse. La quantité de Be potentiellement mobilisable (~0,7 x 10-6 g/g; soit 0,7 ppm) constitue jusqu’à 18% poids du Be global contenu dans le schiste noir. Un bilan de masse appliqué à la zone d’altération hydrothermale des mines de Chivor et basé sur la quantification du Be mobilisable, donne une première estimation des réserves à émeraude de ces mines. rieur."

Jan 1, 1999

By Y. Hou, E. Arinaitwe, L. Tong

A series of dense medium separation (DMS) tests were performed on four low-grade copper ores from Mount Polley mine in order to determine their amenability to pre-concentration. The tested ores contained disseminated sulphides, mostly chalcopyrite with low copper grades (0.15% - 0.2%) and relatively high iron grades (4.76% - 5.63%). The samples were screened into different size fractions ranging from 9.5 mm to 50.8 mm and DMS tests were performed on each size fraction at various separation densities. The pre-concentration efficiency at different size fractions and separation densities was evaluated in terms of metal upgrading and distribution. Mineralogical tests were also performed on selected DMS sink and float samples in order to understand the influence of mineralogy on the pre-concentration efficiency. The results showed that significant copper upgrading was achieved for intermediate size fractions only at the highest separation density tested. The copper recoveries generally increased with particle size at all separation densities. However, it was impossible to upgrade the copper content in the ores and achieve acceptable recoveries and mass rejections at the same time. Copper recoveries and grades showed a strong correlation with iron recoveries and grades indicating that it is possible to pre-concentrate copper by recovering magnetite and other iron-containing minerals in the ore. Overall, the results suggest that the optimum separation density and pre-concentration efficiency is a function of particle size, and that the ore mineralization properties limit the performance of DMS as a pre-concentration technology for such low-grade disseminated ores.

Jan 1, 2014

By H. M. Howard

"The subject of Grinding Media is perhaps still quite controversial. Many people will state today that the spherical ball is the only way, and also will state that this was settled long ago others are not so sure, and I am in this second category. Over the years there have been many changes in grinding and in our evaluation of grinding media we should always be ready to review the overall situation at regular intervals. There is quite a lot of inertia in all branches of Hineral Dressing and this is particularly true of grinding or, more correctly, comminution.In order to understand some of the things which are done today, and to understand some of the thinking on grinding, it is desirable to go back some sixty years and trace the developments in comminution. In doing this we should consider perhaps three general categories with respect to daily tonnage. An arbitrary division would be under 500 T.P.D., 500-5000 T.P.D., and large operations which might have several parallel units, each with a capacity of about 5000 T.P.D. For the future, in the broad picture, this last category will be the important one because we will be more and more dependent on large-tonnage low-grade operations for most of the metals of the future. Some such division is necessary because the daily tonnage will have a very great effect on what we can and cannot do. It is also necessary to consider the entire flowsheet, and to remember in particular that grinding is not merely to make small particles but is also a conditioning process, to prepare the materi.al for the process which follows. The relationship of crushing to grinding must also be considered. It is logical to include the liners as part of the grinding media and we should try to distinguish between the wear of grinding media and the consumption of media by corrosion. Finally, the whole question of grinding media should be examined in relation to the possibilities of using some form of autogenous grinding."

Jan 1, 1970

By N. Molaei, E. R. Bobicki

The continued demand for mineral products, coupled with the depletion of high-grade ore resources, has led to the mining of lower grade ores, which often require fine grinding to achieve mineral liberation. Regrinding of low-grade ores results in the production of fine gangue mineral solids and produces vast quantities of fluid fine tailings which are difficult to separate from water, particularly if they are composed of clay minerals. Organic synthetic polymers and inorganic salts have been widely applied in flocculation of colloidal suspensions in the treatment of mining tailings. However, there are growing concerns regarding their impact on the environment and human health. Recently, extracellular biopolymer flocculants or bioflocculants have attracted much attention as alternative reagents. In this study, much effort has been devoted to considering the effectiveness of protein and polysaccharide-based biopolymers for the dewatering of clay slurries. The interaction between kaolinite and illite clays and biopolymers was investigated via settling tests at pH 7 and 10. Zeta potential measurements were also conducted as a complementary technique. Results showed that protamine and lysozyme protein- based biopolymers were generally the more effective bioflocculants. Pectin, a polysaccharide-based biopolymer, showed a dispersing effect and has the potential to be used as a dispersant and/or depressant for clay minerals in froth flotation. INTRODUCTION With the depletion of high-grade ore resources, the need for mining of low-grade ores has increased over the past few decades (Bourgès-Gastaud, Stoltz, Dolez, Blond, & Touze-Foltz, 2014; Chen, Walshe, Fru, Ciborowski, & Weisener, 2013; C. Wang, Harbottle, Liu, & Xu, 2014). Low-grade ores often require fine grinding and contain clay minerals, leading to the generation of fluid fine tailings (FFT). It is a challenging process to separate suspended clay particles from water (Craciun, Manaila, & Stelescu, 2013; Dompierre, Lindsay, Cruz-Hernández, & Halferdahl, 2016; Kasperski & Mikula, 2011; Mercier et al., 2012). Clay minerals form stable dispersions in water due to their anisotropic nature, non-spherical morphology and colloidal size (Lagaly & Ziesmer, 2003; Olphen, 1977). The difficulty in separating clay minerals from water has led to the accumulation of vast quantities of FFT in oil sands, phosphate, copper and nickel operations, representing a huge liability for mining companies (Chen et al., 2013; Mercier et al., 2012)

Jan 1, 2019

By Sarah Bélair, Denis Beltrami, Deka Moussa Ragueh, Valérie Weigel

"Scandium is a highly valuable element belonging to the rare earth elements (REE) but it has different chemical and physical properties from those of lanthanides. This metal is generally used in aluminum-scandium alloys and in fuel cells but the development of its market is slowed down by its high price (more than 1000 US$/kg for a 99.0% grade product). Indeed, the low scandium content in the continental crust (an average of 22 ppm) and the difficulties to extract it selectively from solutions containing high impurity concentrations increase the cost of the recovery processes. Nowadays, scandium is primarily recovered as a byproduct.ERAMET is developing a hydrometallurgical process in Gabon (Mabounié) in which the scandium content in the deposit reaches 10 to 100 ppm. The Maboumine project consists in the extraction and purification of uranium, niobium, tantalum and REE from Mabounié ore. In the frame of this hydrometallurgical project, ERAMET had also studied the feasibility to recover scandium as a byproduct. During the ore leaching, uranium and rare earth elements including scandium are solubilized into the pregnant leach solution (PLS). Among the various methods investigated to recover scandium from the PLS, liquid-liquid extraction using Primene JM-T as extractant was chosen and tested first at laboratory scale and then at pilot scale. Selective stripping of the loaded organic was carried out by using phosphoric acid solution, allowing the selective recovery of scandium from thorium and zirconium partially extracted from the PLS by Primene JM-T under the process conditions."

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 Xian Jian Guo, Lei Li, Hua Wang

Direct smelting of copper concentrate to blister copper has the advantages of energy saving and environmental protection. There has been a lot of effort invested in process development including test work and theoretic analysis in the past half century. However, the process has only been applied commercially to a few smelters that treat chalcocite types of copper concentrate. The main limitation to treating chalcopyrite types of copper concentrate is high copper content in smelting slag and low direct copper recovery. Thus intensive slag cleaning is needed. In this paper, the thermodynamic analysis was mainly carried out for the multiphase equilibrium of direct to blister copper smelting for both chalcopyrite and chalcocite concentrates. The practical problems in direct to blister copper smelting, which are mainly in copper content in slag, are clarified. The operational window of slag composition for different temperatures and oxygen partial pressure for the treatment of chalcocite type concentrates is identified. The process operation optimization for the blending of chalcocite, pyrite and chalcopyrite concentrates was done. INTRODUCTION The extractive metallurgy of copper can be divided into two broad groups of processes, namely, pyrometallurgy and hydrometallurgy, and the former is dominant. About 80% of copper in the world is produced by pyrometallurgy (Christopher et al., 2006). The first stage of conventional copper pyrometallurgy processing is to smelt copper concentrate to copper matte composed of FeS and Cu2S with slagging to remove a proportion of the iron (Gargul, Boryczko, & Bukowska, 2017). The smelting processes include bath and flash smelting. The second stage of the process is to convert copper matte to blister copper. In most cases, the copper matte is converted in Peirce Smith (P-S) converters, which are batch operations (Kubiszewski, 2015). The P-S converting can be divided into two periods, slagging and copper blowing. During slagging period, FeS in copper matte is oxidized to FeO, which reacts with silica flux forming slag. When the iron content in matte is less than 1%, copper begins to oxidize and reduce to form blister copper (Kucharski, Sak, Madej, Wędrychowicz, & Mróz, 2013).

Jan 1, 2019

By R. T. Seaman

There are several hydrometallurgical alternative processing options under development for high enargite and arsenic containing copper concentrates ranging from biological, atmospheric, medium temperature oxidation to total oxidative leaching. The most developed of these options is the CESL process boasting pilot campaigns totaling more than 8760 hours of fully integrated continuous operation, as well as, over two thousand batch scale oxidation tests performed on dozens of concentrates for flowsheet development. This paper reports the observed deportment of arsenic under varying arsenic, iron and acid oxidation conditions; it also describes the impact of iron to arsenic ratios and residue recycle on overall arsenic behavior and its stability in residue. INTRODUCTION The CESL Hydrometallurgical Process (CESL) was originally developed to compete with smelting of clean chalcopyrite concentrates. High Treatment Charges and Refining Charges (TC/RCs) combined with premiums on London Metal Exchange (LME) grade copper from onsite refining made treatment of copper concentrates using CESL a viable option at the time. As world demand for copper increased and a subsidized Chinese refining market developed, smelting contracts became more favourable for the miner and focus was placed on modifying the CESL Hydrometallurgical Process to handle concentrates with elevated deleterious elements. Dozens of pilot campaigns processing concentrates containing elevated concentrations of uranium, fluoride, mercury and nickel all led to further developments of the CESL Hydrometallurgical Process. In 2016 a United States patent was granted for a novel modification of the CESL Hydrometallurgical Process for recovery of copper from arsenic-bearing and/or antimony-bearing copper sulphide concentrates, Henry Salomon de Friedberg (2016). To date, over 2000 bench scale tests along with five fully integrated closed loop pilot campaigns, totaling over a year of online operation time, have been conducted processing arsenic bearing copper concentrates. This paper summarizes the observed behavior of arsenic under varying autoclave and process conditions.

Jan 1, 2019

By Martin Wacker

Cameco Corporation, on behalf of a joint venture, is preparing surface and underground facilities at their northern Saskatchewan property in preparation for the future operation of a high-grade uranium mine. The Cigar Lake orebody is situated about 430 metres below surface at the unconformity between metamorphic basement rocks and flat lying sandstone. Major technical factors influencing the mining method selection include ground stability, control of ground water, radiation exposure and ore handling and storage. A decade-long test mine program resulted in the selection and validation of ?jet boring? a non-entry mining method. Cigar Lake?s jet boring mining method involves several major steps; artificial ground freezing of the orebody and surrounding rock, TBM (tunnel boring) type development of access crosscuts below the orebody, installation of cased pilot holes upwards through the ore, and ore extraction using a rotating high pressure water jet within the pilot holes. The resulting cavities are surveyed and backfilled with concrete. The ore slurry will be processed underground and pumped to surface. This paper discusses the jet boring mining method in general terms and includes highlights of the Cigar Lake test mine program completed in 2000.

Apr 1, 2005

By R. R. Rogers

Introduction The subject of cathodic protection is not new. In 1824 Sir Humphry Davy, in publishing the results of his investigations for the British navy, pointed out that copper could be protected from sea-water corrosion by connecting it electrically with zinc or iron. Since that time much work has been clone in this field, particularly in the protection of metals from the action of sea water, neutral brines, and treated and untreated waters. Special mention should be made of the successful protection of underground pipe-lines which formerly were badly corroded by the water in the ground. So far, magnesium alloy and zinc anodes have been the most popular. However, fairly recent work has indicated that aluminium anodes will give good service under certain conditions. The principle of cathodic protection has been applied extensively in coating steel articles with zinc and in cladding aluminium alloy sheet with pure aluminium. A valuable discussion of the fundamentals and applications of cathodic protection recently was presented in the Corrosion Handbook. A useful list of references was included in the article.

Jan 1, 1949

By Robert Walker

Agenda ? Investment thesis ? Engagement ? Competitive advantages Corporate engagement ?The ESG Services team carries out engagement activity with the companies in the Ethical Funds portfolio on behalf of investors ?Each year about 50 companies (20% of our assets) are placed on our Focus List based on assessment of significance and severity of ESG risks and the extent of our portfolio exposure ?We engage in direct discussions on material ESG issues ranging from climate change to human rights to executive compensation ?This enables the team to gain insight into how management is addressing various risks to the business and encourage positive change where gaps exist

Aug 1, 2013

Mining companies around the globe have long struggled with the need to ensure that earth moving equipment is designed to be operated and maintained under all site conditions without causing harm to people. Incident and accident data from a range of sources clearly identify mining equipment related issues as major causal factors. One Australian source, the NSW Department of Primary Industries? International Mining Fatality Database Project Report (2008) noted that ?Approximately 77% of mining accidents resulting in a fatality have? involved equipment?. The largest number of fatalities were associated with trucks; the next with LHDs. Many of the technical advances in equipment design over the past few decades have not been matched by advances in the human factors design of mining equipment, resulting in a ?design vacuum? that must be filled prior to commissioning new equipment. This ?design vacuum? is generally filled by local dealers. They retrofit equipment according to customer requirements to mitigate risks that have not been designed out by the Original Equipment Manufacturer (OEM). Mining companies have been frustrated by lost time and additional costs associated with this need to retrofit ex-factory designs. Some companies have attempted to address the problem by negotiating company or site-wide ?solutions? to equipment designs, but this has not simplified or clarified the issue from the point of view of the equipment manufacturers. A number of mining companies operating in Australia first discussed the concept of a joint customer approach to improve the Human Factors design of earth moving equipment at the factory level in 2004. They agreed that a new approach to engaging with OEMs was needed; one that would define the ?Problem?, in other words, the basis of the risks, rather than dictate the ?Solution?. The Earth Moving Equipment Safety Round Table (EMESRT) was formally established in 2006 by six global mining companies to establish a process of engagement between Original Equipment Manufacturers (OEMs) and mining customers.

May 1, 2009

By Alok Porwal, E. J. M. Carranza, M. Hale

Abstract- Approaches to mineral potential mapping based on weights of evidence generally use binary maps, whereas, real-world geospatial data are mostly multi-class in nature. The consequent reclassification of multi-class maps into binary maps is a simplification that might result in a loss of information. This paper describes results of using multi-class evidential maps in an extended weights-of-evidence model vis-à-vis results of using binary evidential maps in a simple-weights-ofevidence model. The study area in the south-central part of Aravalli province (western India) hosts a number of SEDEX-type base metal deposits in Proterozoic supracrustal rocks. Recognition criteria for base metal deposits were represented as both multi-class and binary evidential maps. The known mineral deposits were divided into two subsets, viz., the training and the validation subsets. The training subset was used to calculate, for the evidential maps, the weights, contrasts, and posterior probabilities and their variances. The distributions of expected frequencies of base metal deposits estimated from the posterior probabilities and the observed frequencies were compared using standard goodness-of-fit tests to verify conditional independence of the input evidential maps. The posterior probabilities from both the models were mapped and interpreted to classify the study area into zones favorable, permissive, and non-permissive for base metal deposit occurrence. As compared to the simple weights-of-evidence model, the extended weights-of-evidence model results in more robust and finely differentiated posterior probabilities in favorable and permissive zones and has a better prediction rate. The results also reveal that the statistical properties of the weights of evidence, the contrasts, and the posterior probabilities are not significantly degenerated by using multi-class evidential maps in weights-of-evidence modelling.

Jan 1, 2001

By M. Remillard, M. Garon, M. Thérien, D. Hodouin

"Nineteen streams in the copper and zinc flotation units of the concentrator of the Matagami division of Noranda Inc. have been sampled for particle size distributions chemical assays, and gold and silver contents in each particle size interval. The data are upgraded by the mass balance package BILMAT. These results, in conjunction with microprobe analyses, are used to quantify the silver losses in the copper clean¬ing flotation stages and to determine how overall silver and three silver-bearing minerals are recovered in the plant final products.RESUME Dix-neuf produits des circuits de flottation du cuivre et du zinc de la division Matagami de Noranda Inc. ont été échantillonnés pour leur distribution granulométrique, analyses chimiques et le contenu d'argent et d'or des fractions granulométriques. Le bilan métallurgique a été obtenu à l'aide du programme BILMAT. Ces résultats couples avec une etude minéralogique à la microsonde sont utilises pour quantifier les pertes argentifères aux diverses étapes de nettoyage du circuit de cuivre et pour de¬terminer la repartition de l'argent et des trois minéraux argentifères dans les produitsfinals de l'usine.INTRODUCTION The Matagami division of NORANDA INC. produces copper and zinc concentrates from a sulphide ore which contains a small amount of gold (0.34 g/t) and silver (20 g/t). Only a small part of the silver (~-30%) is presently recovered in the copper concentrate. The objective of this study is to evaluate the metallurgical behaviour of silver, and secondarily of gold, in the flotation circuit for a possible increase of its recovery in the copper concentrate to improve its economic value. For that purpose it is worthwhile to study the minerals which bear silver and to determine the critical flotation stages where they are lost in the tails. The methodology proposed here is based on a coupling of a mineralogical study and a detailed mass balance calculation in the flotation circuit."

Jan 1, 1986

By A. Abadías Llamas, N. Bartie, M. Stelter

Evaluating the economic viability as well as the sustainability of the Circular Economy (CE) system requires a deep understanding of the distribution of all elements, compounds, alloys, materials etc. in flows. In this paper, the circularity of the copper value chain, including primary and secondary processing, is rigorously evaluated. The studied system comprises the metallic copper production from primary sources (from mineral to metal), copper-containing commodity production (copper is mixed with other metals) and copper recycling through secondary smelting to close the loop. This is linked to photovoltaic (PV) panels and battery storage. A simulation model of this system is created using HSC Sim, considering more than 30 elements (and its various compounds), 180 unit operations and 800 flows. From the mass and energy balances obtained through the simulation, an exergy analysis is conducted to evaluate the resource consumption from a second law (entropy) perspective. Additionally, these results are complemented through a Life Cycle Assessment (LCA), the recovery of technology elements and by-products is discussed, while quantifying the losses through the value chain. Through the digitalization of the complete system, a better CAPEX and OPEX understanding of the metal recovery and losses can be obtained, as well as the associated resource consumption and environmental impacts. New flowsheets and technologies can be evaluated. Several scenarios show how the resource consumption and the environmental impacts are affected by the recovery of different materials to produce different products. INTRODUCTION A key challenge of the circular economy (CE) is the linkage and optimization of both resource and energy efficiency of the (renewable) energy infrastructure and the resource cycle depicted by Figure 1 simultaneously. In addition, the CE requires the linkage of all stakeholders as shown by Figure 1. This has been discussed in some detail by Reuter and Bartie (2019) and Reuter et al. (2019). Copper and all its associated technology elements is one of the key enabling metals that is an economical copper colored thread through CE society (Reuter & Kojo, 2014). The Metal Wheel (Figure 2) shows the linkage of and recovery of various elements associated with copper and other carrier metals. This reveals that copper acts as an important carrier metal because of its properties i.e. the wealth of technology elements it carries from geological ores, but also its capacity to act as solvent of valuable elements and thence a key closer of various complexly connected element and material cycles when these technology elements are released during copper refining. The same applies to all other carrier metals of modern CE society as shown for example recently in a lead policy brief (Blanpain, Reuter & Malfliet, 2019).

Jan 1, 2019

By Y. Miyabayashi, K. Nishikawa, H. Nagai

JX Nippon Mining & Metals Group recovers valuable metals from end-of-life electronic products in an economical and environmentally-benign way, based on technologies that have been acquired in mining, smelting, and refining operations over time. End-of-life electronic products contain halogens and hydrocarbons. When such materials are treated in the copper smelting process, corrosion of equipment and discoloration of sulfuric acid occur. As a countermeasure to these problems, we have developed pretreatment processes that include an incinerator, exhaust gas washing towers, and a defluorination facility. By implementing these improvements, we have been able to treat a large volume of end-of-life electronic products efficiently in the copper smelting process.

Jan 1, 2014

By J. F. Dorion

This paper presents the results of on-going investigations on the performance of support systems in Québec underground mines. The focus of these investigations is on site observations complemented by laboratory investigations. Of particular interest is deducing the corrosion rate, at selected mine sites, as determined by the installation of monitoring coupons.

May 1, 2009

By S. Caron, M. Bourassa, J. Châteauneuf, L. Tardif

"Since many years, the Yvan-Vézina gold plant custom mills and processes different ore types that show different behaviors. Because of this, cyanidation control is more complex than for a typical milling operation. In 1992, a Cyancor™ on-line « free cyanide » analyzer has been installed for monitoring and optimizing cyanidation. This implementation significantly reduced cyanide consumption for the overall cyanidation process. In order to further reduce cyanide costs, an automatic control strategy has been implemented to decrease fluctuations of« free cyanide » from their set points.This paper outlines the major steps of the project: process control audit, control strategy development, implementation and running-in period. Control strategy features include data filtering modules, adaptive PID algorithm and set points management modules are also presented. Finally, the strategy efficiency is illustrated with load-disturbance responses.IntroductionLocated in northwestern Quebec, the Yvan-Vézina plant has an average capacity of 1300 t/d using carbon-in-pulp technology. In 1991, the Yvan-Vézina gold plant was processing three types of ores (Beauchemin, Mouska and Silidor mines) and a pyrite concentrate (Beliveau mine). A cyanide reduction program was then undertaken to reduce « free cyanide» fluctuations <6>. To reach this objective, the optimum cyanide concentration was determined for each ore, a continuous monitoring method with the Cyancor™ on-line analyzer was developed and a tighter control of cyanide addition was applied. These modifications to the leaching practice significantly reduced cyanide consumption.After a while, it was observed that regulation of « free cyanide » concentrations could still be improved by the use of an automatic control strategy. Yvan-Vézina and CRM began collaborating in 1995 to develop and implement such a strategy. Results show that main disturbances of the circuit (e.g. ore mineralogy and pulp feed rate) can be significantly overcome in order to reduce their effects on the leaching operation."

Jan 1, 1998

By R. Bridge

Mining companies are progressively finding themselves having to develop operations for more complex, deeper ore bodies, which require the use of more complicated mining and mineral processing methods. This coupled with the generally increasing trend of higher capital and operational costs have led to a need in the industry for improving ore body knowledge, mining and mineral processing. Geometallurgy is a relatively new concept that can link the three aspects, and when used effectively it is a method that can produce the necessary information for designing and building operations for reliable and optimum performance. Geometallurgy not only involves the integration of geological, mining, and metallurgical fields, but it can also be expanded to include environmental and economic information to produce a block model that can be used to obtain the best outcome in terms of plant response and plant sustainability. The geometallurgical program should not end once the block model has been populated. A detailed geometallurgical approach should be applied to all stages of the operation encompassing sample selection, through to equipment sizing and production forecasting. It can also become a useful optimisation tool thereby allowing the operation to be proactive rather than reactive against changes in the ore characteristics. With the development of metallurgical performance predictors it is possible to quantify how the ore will behave in the process plant in terms of throughput, recoveries, reagent consumption, etc. Therefore, in terms of responsible mining and sustainable resource development, a geometallurgical approach to operations is the logical step for plant development. In this paper we describe the state of the technology with respect to the application of geometallurgical modeling and its utilisation in the fields of design, forecasting and optimisation of mining operations.

Aug 1, 2013