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By A. B. C. Stothart

"IntroductionIn the past four years Ontario Mines have made great progress in the development of reliable mine conveyance safety dogs. History shows that, prior to 1945, a rope failure on a descending conveyance was usually followed by unsatisfactory safety dog operation.It is proposed in this paper to discuss briefly;The history of this development. Progressive .development of one type (E. Long).Free fall testing of safety dogs. Anti-trailing rope device.HistoryOn February 2nd., 1945, a hoisting rope broke at the Paymaster mine. The safety dogs proved ineffective and permitted the cage to crash through to the bottom of the shaft, with disastrous results.Following this accident, the Ontario Government appointed a Technical Committee to investigate The Safety of Hoisting Equipment and Hoisting Practice in Ontario Mines. This Committee consisted of Dr. C. R. Young (Chairman) and Professors T. R. Loudon, E. A. Allcut, V. G. Smith, and Lloyd M. Pidgeon. The Ontario Mining Association (at the request of the Ontario Government) also appointed a Committee consisting of Messrs. R. E. Dye, R. D. Parker, and R. L. Healy."

Jan 1, 1950

By The Staff

FOR forty years cyanide men have been intensively engaged on the treatment of sulpho-telluride ores. So far as we know, the processes used today were-with the important exception of the concentration plus high-lime process at the Victor mill (1915)-in use, or had been tried, in the earl y years of the century. Roasting, bromocyanide, ordinary cyanide, table and vanner concentration, floating and treating the concentrate, roasting con-centrates prior to treatment, etc., all were used at Kalgoorlie in 1904 or earlier. Flotation, followed by shipment of the concentrate to the Golden Cycle mill, was the practice at the Vindicator mine, Cripple Creek, for some years prior to 1917. Similar practice was employed in the Portland Independence mill at Victor, Colorado, and was lacer superseded by the table concentration, high-lime cyanide treatment of rails of the older Portland Victor mill. During all this time, an immense amount of research was being clone on these ores by the staffs of numberless companies. Conclusions were drawn and mills built. But if the results of one per cent of this research were ever published in sufficient detail for intelligent use by others, the Lake Shore staff has been unable to discover them, or does not recall having clone so. Government laboratories-as for instance chose of the Mines Branch, Ottawa, in or about 1927-have touched upon certain methods in their publications, but they simply have not had the time to finish the job. The paper by W. E. Johnston, Tellurides-Problem or Alibi? (E. & M.]., Aug., 1933), aroused wide interest and comment. It published conclusions, some right and some wrong, and gave the evidence adduced by the author i:n support thereof. Conclusions published without supporting evidence are to most of us worse than no conclusions at all. We suggest chat, if even one-tenth of the operators had published full, detailed results of their laboratory work, ad vance in the treatment of sulpho-telluride ores would have been very much accelerated. Therefore, we venture to inflict upon the Institute a compendium of the results of laboratory work performed during the past few years at the Lake Shore mill. It is really a summary of the more interesting results to date, prepared by the mill staff for their own use and benefit. But we hope chat the discussion under any heading is so detailed chat it will be intelligible to anyone interested in that phase of the subject.

Jan 1, 1936

By José L. Carvalho

"Time-dependent swelling deformation of several shaley rock formations in Ontario is a wellknown phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. The swelling phenomenon appears to be related to ion exchange between the rock porewater and the surrounding water.The swelling potential is expressed as the percent swelling strain that occurs per log cycle of time, in either the vertical (perpendicular to bedding) or horizontal (parallel to bedding) directions. In addition, the swelling potential is also noted to be stress dependent. In practice, therefore, the conditions required for swelling are (i) the accessibility to water, and (ii) an outward salt concentration gradient from pore fluid of the rock to the ambient fluid. The relief of in-situ rock stress during excavation serves an initiating mechanism (Lo and Micic, 2010).INTRODUCTIONTime-dependent swelling deformation of several shaley rock formations in Ontario is a well-known phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. Swelling is also controlled by the inter-particle bonding; if the bond strength exceeds the osmotic pressure, swelling will not occur, and vice-versa. The bond strength can be reflected by the calcite content which forms cementation bond between rock particles."

Jan 1, 2015

By T. W. Wlodek

Abstract A simplified method of fatigue testing full-dimension, as-rolled, non-machined, mining drill rods is very desirable to the mining and steel industries in the classification of steels available on the market, through the evaluation of their fatigue limits and endurance strength. In this paper one such simplified method is presented and analysed. The preliminary results show many advantages of this method, such as simplicity and constancy of loading. The type of loading applied more or less simulates the working conditions of the outside fibres of the mining drill rods. Additional advantages of this method are the possibility of testing under dry and wet conditions, its quietness, and its ease of operation. Specially designed adaptors and specially applied techniques of fixing and preparation of samples make possible the breaking of a quarter-octagon hollow drill rod in a free length of uniform section in a rotating beam machine. At first glance this seems to be difficult to achieve. In the first preliminary test three different lots of steel were used. S-N curves under dry conditions were determined. These curves permit of the classification of the drill rods on the basis of the fatigue limit and endurance strength of the outside fibres of the metal, which is dependent to a greater or lesser extent on the effect of surface decarburization, surface imperfections, and special surface treatments. The average slope of the S.N curve in the damaging zone, and the fatigue limit in equal tension-compression rotating bending, were determined for SAE 1080, chromium-molybdenum and nickel-chromium-molybdenum mining drill rods. INTRODUCTION The fatigue limit and the endurance strength of mining drill rod steels are of interest to both the mining and the steel industries. These industries are greatly interested in lowering the cost of mining by reducing the consumption of these steels per ton of ore exploited.

Jan 1, 1951

By F. Rashchi, A. Ghahreman, J. Moghaddam, S. Karimi

"In this work, the kinetics of ferric-ferrous redox reaction on a passivated sphalerite electrode is studied by the application of chronoamperometry method in 0.5 mol L-1 H2SO4 solution. The electrochemical behaviour of ferric and ferrous couple was investigated on two sphalerite minerals acquired from two different geological regions (Iran and Canada). The carbon paste electrode (CPE) of sphalerite was initially prepared and passivated in 0.5 mol L-1 H2SO4 solution and after reaching the steady-state condition, ferric and ferrous sulfate solution was added. The registered current density differences between the current density of the passivated electrode and that of the electrode in the iron salts added solution were interpreted for kinetics of ferric-ferrous reduction-oxidation reaction. The equilibrium potential for ferric-ferrous couple on sphalerites surface was about 500 mV vs. Ag/AgCl. The exchange current density (i0) for ferric-ferrous redox reactions on the sphalerite samples had the same magnitude of 10–6 A cm–2. The electrochemical impedance spectroscopy (EIS) measurements at 550 mV vs. Ag/AgCl illustrated that sphalerite oxidation was controlled by two charge transfer process in both of Fe-free and Fe-containing solutions. The charge transfer resistance remarkably decreased when Fe salts added to the 0.5 mol L-1 H2SO4 solution, owing to the ferric-ferrous redox reactions being the predominant reactions on sphalerite surface.INTRODUCTION Direct atmospheric leaching processes for sphalerite concentrates are performed by reduction of an oxidant (e.g. ferric ion and oxygen) and oxidation of sphalerite to zinc ions. Oxygen could be an oxidizing agent as well, but the concentration of oxygen is very low in the solution. The role of ferric ions is predominate in this oxidation (Babu, Sahu, & Pandey, 2002). The oxidation reaction for sphalerite in the presence of ferric in can be presented as follows (Lampinen, Laari, & Turunen, 2015):"

Jan 1, 2017

By William Petruk

Image analysis studies were performed on mill products from pilot-plant and laboratory tests that had been conducted to determine the effect of grinding media on the selective flotation of two zinc-lead-copper ores. It was found that, when the ores had been ground to the same degree of fineness with flint pebbles, ceramic pebbles or ore fragments (autogenous grinding) as with steel balls, there generally was increased sphalerite, chalcopyrite and galena liberation in the flotation feeds, depending on the textures of the minerals. The increased sphalerite liberation fully accounted for the improved zinc recoveries that were obtained when steel balls were replaced by either pebbles or ore fragments. The increased chalcopyrite and galena liberation accounted for part of the changed technical efficiency of concentration, but other factors, probably changes in oxidation and reduction of iron and in consumption of oxygen, also contributed.

Jan 1, 1977

By K. Webb

At both the international and country level, the issue of how the mining sector and indigenous populations should engage on issues of mutual interest or concern has emerged as one of central importance and controversy; involving the mining industry, Aboriginal communities, governments, the courts, and other stakeholders. At its heart, stakeholder engagement is an ethical issue, although it manifests itself in international instruments, domestic laws, industry guidance and agreements. At the international level, the concept of ?free, prior and informed consent? (FPIC), while not subject to widespread agreement on the finer details of evolving definitions, seems to be emerging as an increasingly recognized engagement norm. Within Canada, through a series of decisions, the Supreme Court of Canada (SCC) has articulated a fiduciary obligation of the Crown to consult with and accommodate impacted Aboriginal groups on resource management issues. Provincial governments have been variously attempting to adjust their resource management regimes to stay in alignment with SCC and lower court decisions. Mining sector organizations, working with First Nations partners, have developed agreements to work together for mutual benefit. At the individual mine and community level, there have been instances of constructive engagement, as well situations of physical resistance and legal challenges. The purpose of this paper is to examine the potential impact of new rules under the Ontario Mining Act introduced in 2012 and taking full effect in 2013, which amongst other procedural specifications, addresses the issue of mining industry-Aboriginal consultation in exploration and development activities. Leading up to the passage of the regulations, representatives from some junior mineral exploration companies have been highly critical of the new rules. Similarly, there have been a range of responses to the new rules from some in the First Nations community. The paper will review the regulation in terms of its apparent alignment with SCC decisions and the international norm, compare the regulations with existing mining sector organization guidance documents, and it will draw on the stated perspectives and commentaries of First Nations communities, mining firms, governments, nongovernmental organizations, and others. Building on the foregoing, the paper will provide a preliminary analysis of the perspectives and potential impacts of the new regulation on various stakeholders, and on that basis, possible avenues for further consideration will be suggested.

Aug 1, 2013

By K. Bachmann, M. Rudolph, U. A. Peuker, H. H. Duong, T. Heinig, T. Leißner, H. Schubert, Helmholtz-Institute Freiberg for Resource Technology, Technische Universität Bergakademie Freiberg

"Minerals can be liberated by random fracture of particles into smaller fragments or by detachment along phase boundaries. These two mechanisms represent borderline cases. When ores get comminuted the liberation of minerals is achieved to some extent by both mechanisms. This article describes a method to determine the extent of transgranular and intergranular fracture on surface exposure of minerals based on 2-dimensional liberation analysis.The approach uses the non-biased surface information like phase specific surface area (PSSA), phase specific free surface (PSFS) and phase specific locked surface (PSLS) of minerals and their change with comminution. The amount of transgranular and intergranular fracture on surface exposure can be calculated using the phase specific surface parameters.A sedimentary rock (apatite ore), an igneous rock (nepheline-syenite) and an artificial material (copper slags) were ground to different fineness. Based on the mineral liberation analysis (MLA) of feed and products, the extent of phase boundary fracture on the surface exposure of the minerals is studied.INTRODUCTIONMinerals can be liberated ether by comminution or by detachment (Gaudin, 1939). Liberation by comminution is a random fracture mechanism, which is not being influenced by ore texture, grain boundaries and mineral features (transgranular fracture). Liberation by detachment represents a fracture along grain boundaries (intergranular fracture). Random fracture often is named as the dominating mechanism for the liberation of ore minerals. This has been the basis to simplify models for liberation modelling (Barbery, 1991; King, 1979; Meloy, 1984) assuming that the probability of cracks moving along grain boundaries is zero. Thus, no interfacial area is lost during comminution."

Jan 1, 2016

By K. Webb, M. Hohn

"This paper reviews the evolving Ontario mining regime for mining industry-Aboriginal engagement and its apparent alignment with court decisions, domestic law, emerging international norms, mining industry rules, and mining firm-Aboriginal agreements, drawing on publicly available commentary from government officials, the private sector, and Indigenous communities. This paper provides a preliminary analysis of the potential implications of the new regime, especially for the mining industry and Aboriginal communities and, on that basis, discusses possible future developments.RÉSUMÉ Le présent article analyse le régime minier de l’Ontario pour l’engagement entre l’industrie minière et les Autochtones et son harmonisation avec les décisions des tribunaux, le droit interne, les nouvelles normes internationales, les règles de l’industrie minière et les ententes compagnies minières- Autochtones en se basant sur des commentaires, disponibles publiquement, d’officiels gouvernementaux, du secteur privé et des communautés autochtones. Cet article fournit une analyse préliminaire des implications potentielles du nouveau régime, surtout pour l’industrie minière et les communautés autochtones et, en s’appuyant sur ces données, il traite des futurs développements possibles."

Jan 1, 2016

By A. H. A. Robinson

Until quite recently-practically up to the present time-all but an insignificant amount of the copper produced in Canada was shipped abroad in the form of ore, matte, blister, etc., there to undergo the further treatment necessary to bring it to the refined state in which it is required by fabricators of copper. Consequently, Canadian manufacturers were forced to import nearly all the copper required in their business; and a considerable portion of the ultimate value to be derived from a Canadian raw material was lost to the country of its origin. In the early days of Canadian copper mining, when both the production and consumption of copper in Canada were much smaller than now, such a condition of affairs was perhaps economically unavoidable, and, in any case, was not a matte~ of sufficient importance to attract general attention. Later on, however, when there had been large and rapid increases both in the production and consumption of copper in Canada, it formed the basis of much adverse criticism, deserved or not, of producers of Canadian copper-criticism that became intensified during the war and subsequent years. Happily, the chief grounds of complaint have now been removed, and there are today copper refineries in Canada, either operating or under construction, that are capable, in the aggregate, of turning out amounts of refined copper greatly in excess of any indicated Canadian consumption.

Jan 1, 1931

By A. Ingelson

Conflict over mineral development and its impacts on indigenous peoples occurs in many countries around the world. Canada, Bolivia and Peru have experienced mine development for centuries in areas where indigenous communities have been and continue to be affected by the mining industry. On a global basis the mining industry continues to face the challenge of implementing meaningful consultation programs with indigenous peoples. Many governments around the world have adopted sustainable development as a policy and one important element of sustainable development is minimizing social conflict. John Moffet and Francois Bregha (Moffet & Bregha, 1996), in their analysis of the role of law reform in promoting sustainable development, noted that stakeholder participation can reduce this type of conflict. Social conflict can result in expensive litigation and costly project delays for mine developers. Meaningful consultation with indigenous peoples in areas where mine development is proposed can be a critical factor in securing a social licence to operate. A report released by the United Nations in 2005, outlined the elements of a concept called ?free, prior informed consent? (FPIC) that promotes more sustainable development. FPIC provides that mineral exploration and mining should not proceed unless the mining company has secured the consent of the relevant indigenous group(s). This paper employs a comparative approach to evaluate the extent to which three active mining nations, Canada, Bolivia and Peru, require consultation with indigenous residents and adhere to the principle of FPIC. The comparative approach assists in the identification of those consultation elements in the legal regimes of each country that can minimize social conflict in mineral exploration and mine development and therefore contribute to more sustainable development. First, we examine the legal requirements to consult with and accommodate indigenous communities in Canada, a country with a long history of mineral development over a large geographic area that has entrenched in its Constitution the protection of indigenous peoples? rights. We then turn to an analysis of Bolivia, one of the most indigenously conscious mining jurisdictions that has followed the Canadian lead in entrenching constitutional protection for indigenous peoples. Third, the approach to consultation with indigenous peoples in Peru, a nation that has not adopted the Canadian and Bolivian approaches to constitutional protection of indigenous peoples rights, is considered.

Aug 1, 2013

By A. Koning, P. Lauzon

Pressure hydrometallurgy operations require vessels to be lined with an impermeable membrane for corrosion protection and one or more courses of refractory or ceramic brick. Examples of unit operations that utilize composite lining systems include pressure oxidation autoclaves, sulphide precipitation autoclaves, chloride leach reactors, flash vessels, cyclone separators, and direct contact condensers (heater vessels and quench vessels). The refractory lining must satisfy multiple requirements: it must thermally insulate the membrane from process fluid, be structurally stable, provide erosion resistance, be chemically compatible with process fluid, and provide an economic service life. New hydrometallurgical processes are pushing the pressure, and temperature, with each new generation of plants. A fundamental understanding of all factors affecting the mechanical stability of the lining system is essential as lining designs move further away from the industry's experience base. The impact of irreversible chemical swell, operating factors, design factors, and installation factors are presented based on modifications to the traditional one-dimensional mechanical stress model. A new stability criterion - that the brick lining remain in contact with the steel shell membrane - is presented. This new stability criterion imposes new restrictions on the lining design.The effect of geometry and adding additional degrees of freedom to the analysis is explored using two-dimensional and three-dimensional Finite Element Analysis (FEA). The effect of these additional degrees of freedom on the results of the one-dimensional model are discussed.

Jan 1, 2004

By M. Pötsch, W. Schubert

"The kinematic analysis of rock blocks is one part of a block stability assessment. It provides information about a block’s movability, i.e. if a block can detach from the adjacent rock mass and move towards the free space. This paper introduces an analytical method for the analysis of pure rotations of arbitrary finite polyhedral blocks. It enables the engineer to judge a block’s rotatability about a corner or an edge. The method is presented using a graphical and computational method. The application of the method is illustrated with an example. INTRODUCTIONThe kinematic analysis of rock blocks deals with the determination of the movability of blocks. Established methods typically cover: (a) translational motion (John 1968, Markland 1972, Londe et al. 1969, 1970, Goodman & Shi 1985, Warburton 1981) and (b) the specific rotational cases Toppling (Goodman & Bray 1977) and Slumping (Kieffer 1998). Mauldon & Goodman (1990, 1996) and Tonon (1998) introduced rotational kinematic analyses for three-joint pyramids and tetrahedral blocks extending Goodman & Shi’s block theory.All mentioned methods are subject to assumptions that limit the applicability to engineering problems. For example, the kinematic test of daylighting joints or intersections inherently assumes a finite block, which only can be proved by the finiteness theorem (Goodman & Shi 1985). Daylighting of an intersection or plane is not a sufficient condition for removability. Goodman & Shi’s and Warburton’s methods are limited to translational block motion. The methods for block rotations so far address tetrahedral blocks only. They also address only pure rotational modes and neglect the general motion of a rigid body. This paper introduces an analytical method for the analysis of the kinematic rotatability of finite rock blocks. It extends Mauldon's and Tonon's theory of rotatability of tetrahedra to arbitrary polyhedral blocks. A graphical method using the stereographic projection and a computational method are presented."

Jan 1, 2015

By M. Jackson, R. McDonald, T. Osken, D. Robinson

"The addition of sulphidic materials in the leaching of nickel laterites has several potential benefits that include improvements in the rheological behaviour of the blends, reductions in the sulphuric acid and steam requirements, sweetening of the nickel grade of the combined feed material, and the option of using a range of sulphidic materials. The current study examines the oxidative processing of 30% w/w blends of nickel concentrate and nickel laterite ore at 250oC. In particular, the viability of using low oxygen overpressures was examined for significant amounts of nickel flotation concentrate, up to 12% w/w. Further to this the impact of process water quality, in particular the presence of chloride, upon the kinetics of extraction and the mineralogy of the residue were also investigated. This paper will present the results of preliminary work in this area.INTRODUCTIONThe use of sulphidic ore as a source of sulphuric acid during oxidative hydrometallurgical processing is not a novel idea and can be traced back over forty years (Seidel & Fitzhugh, 1968). A series of patents pertaining to application of this approach for laterite ores can be subsequently found (O’Neill, 1973; Opratko et al., 1974; Rodriguez, 2008a, 2008b; O’Callaghan, 2010; Liu et al., 2011) and a few of articles containing published data (Ferron & Fleming, 2004; Quinn et al., 2009). The use of pyrrhotite tailings as a source of sulphuric acid has also been employed for the leaching of converter slags (Perederiy et al., 2011).It is known that hydrometallurgical operations such as the HPAL plant at Murrin Murrin have added small amounts of sulphides as either transitional (mixed sulphide/oxide) ore or non-smeltable concentrate. This can improve the rheology (Rodriguez, 2009) and provide heat credits. However these plants are generally limited in their ability to add such materials due to their reducing nature and given under highly acidic conditions that the breakdown potential of the titanium used for the autoclave lining is significantly reduced. A suitable oxidant must therefore be present to ensure the potential remains sufficiently high."

Jan 1, 2012

By S. Mohammadnejad, M. Olizadeh, B. Mehrabi

A new method using a combination of comprehensive mineralogical and analytical approach which includes optical and electrical microscopy and several analytical techniques with diagnostic leaching has been used to characterize the associations and distribution of gold in a variety of minerals from the Zarshuran refractory gold ore, NW Iran. Zarshuran ore with an average of 7.9 g/t Au-grade and about 8% arsenic with gold recovery less than 20% in direct cyanidation is considered as high arsenic, high au-grade refractory gold ore. In most of the refractory ores, gold is associated with arsenopyrite and co-para genetic ore minerals, while in Zarshuran ore; gold is associated with orpiment, realgar and arsenian-pyrite. Considering its mineralogy and As content, it can be considered as the most difficult refractory ore for characterization and processing. Results from the mineralogical examination and diagnostic leaches indicate that there is only a small amount of free gold (17-19%) that is present in cyanide-soluble sulfo-arsenides compounds, predominantly orpiment and realgar. Diagnostic leaches also indicate that little gold is occluded within the silicate structure (14%). Overall, the gold is mostly included in sulfides, arsenic sulfides and sulfo-arsenides (50%). The results also have shown how the technique can be used to gain a good initial understanding of potential metallurgical problems for a refractory gold ore.

Jan 1, 2005

By E. M. Timoshenko, A. V. Tarasov

The results of laboratory, bench-scale and semi-commercial investigations of a method for adding surfactant (technical-grade lignosulphonate) to the process of pressure leaching of nickel-containing pyrrhotite concentrates have been discussed. Lt has been demonstrated that feeding of technical-grade lignosulphonate distributed along the length of an autoclave ensures a reduction in its requirement by a factor of 1.5 to 2 as compared with single-point feeding; it also results in a decrease by 5% in the unit requirement of metallized iron-bearing precipitator in the process of non-ferrous metals precipitation and reduces by 0.05 to 0.1% (abs.) the nickel and copper contents in the tailings of the given process. Technical solutions have been proposed for commercial introduction of the process.

Jan 1, 2004

By R. W. Pauls

"Many tens of thousands of hectares of forested land will be disturbed and reclaimed in the surface mineable Athabasca oil sands area during the next few decades. The surface area disturbed by Syncrude’s Mildred Lake development alone exceeds 10 000 ha to date. It is not clear that reforestation of disturbed areas will best accommodate the aspirations of all stakeholders, particularly traditional users of the land. A five-year research program by Syncrude Canada Limited and the Fort McKay First Nations has examined the feasibility of raising bison on land reclaimed after disturbance by oil sands development. Forage productivity and carrying capacity for bison was comparable to that of grasslands elsewhere in Alberta. Concerns regarding compaction of newly rebuilt soil by bison traffic proved unfounded. Bison demonstrated weight gains typical for ranched bison and calving rates averaged 90%, a value typical for ranched bison. The animal husbandry problems encountered were typical of those occurring on bison ranches elsewhere in Alberta. An economic analysis indicates that a 1000 ha bison ranch on reclaimed land has a net present value that compares very favourably with a similar area supporting commercial forest. Subject to approval by Alberta Environmental Protection, the current research project will be expanded as a pilot commercial ranching venture in order to explore its commercial viability as a business venture by the Fort McKay First Nations. At the same time, measures will be implemented to resolve various regulatory issues associated with commercial bison production in the oil sands area.BackgroundSyncrude Canada Ltd. (Syncrude) is proposing, in its land reclamation strategy, a feature that is, depending on one’s background and perspective, regarded as an innovative approach to land reclamation, a threat to the regional forest industry, a creative response to aboriginal stakeholder concerns, a reneging on reclamation commitments, an opportunity to provide an ongoing economic base for postoil sands regional economy, or an environmentally unsound use of the land. These diverse and sometimes strong reactions have been generated by the proposal to introduce bison, either free-ranging or commercial ranched, to the reclaimed landscape."

Jan 1, 1999

By M. Dupuis

Recently, a new approach to controlling alumina feeding in a H.H. cell has been proposed [1, 2 and 3]. This approach, labeled In Situ aluminium cell control, is based on a correlation between the slope of the cell voltage during a no feed observation period and the dissolved alumina concentration in the bath. Once the dissolved alumina concentration has been estimated, a primary calibration surface uniquely relating the dissolved alumina concentration and the anode-cathode-distance (ACD) to the cell voltage is used to estimate the cell ACD. Once both the alumina concentration and the ACD have been estimated at the end of the observation period, a PID controller can be used to regulate the rate of alumina feeding using only the normalized cell voltage to calculate the error between the estimated dissolved alumina concentration and a target value. The In Situ aluminium cell control algorithm has now been tested with the Dyna/Marc [4, 5 and 6] cell simulator demonstrating that it should be possible to control a H.H. cell in this manner with less variation in the dissolved alumina concentration and other process variables producing a prediction of improved cell current efficiency and power efficiency.

Jan 1, 2011

By R. K. Jonas

"Pressure leaching and pressure oxidation in autoclaves are important alternatives in the extractive processing of gold, copper and nickel ores. The application of advanced control to pressure leach and pressure oxidation autoclaves could achieve significant benefits as has been shown in alumina pressure leaching. This paper compares and contrasts alumina digestion autoclaves to other mining autoclaves with respect to advanced controls. The application of advanced control in alumina with over 30 units controlled worldwide, and its benefits will be reviewed. The design and potential benefits from advanced control for pressure oxidation and leaching will be presented.INTRODUCTIONIt is this author's position and the purpose of this paper to propose that advanced control could be effectively applied to autoclaves in the nickel, gold, and copper mining processes. This is based on the proven effectiveness of advanced control on autoclaves used in the alumina industry for pressure leaching of bauxite ores. Incremental, but significant increases in production could be realized by applying advanced control to autoclaves, as evidenced by the alumina industry, and this not being implemented in other autoclaves in the mining industry.In addition, today the mining industry is being challenged to improve their production methods. In some markets like nickel, there is pressure to improve productivity and reduce the cash cost per ton. While in other markets like copper and gold, demand is vigorous with favourable pricing, and there are advantages to increase production and productivity given limited plant capacity. Advanced control has proven its capability to improve mineral processing operations through increases in throughput, recovery, as well as reducing variability. In today's mines, autoclaves are being used to a much larger scale and with much larger importance, thus it would be beneficial to improve operational performance through the use of advanced control.Accordingly, it is the author supposition that an opportunity exists in the mining industry to use a proven advanced control technology to improve the operations and financial performance of mines using autoclaves."

Jan 1, 2012

By G. B. Harris

In recent years, increasing attention has been focused on the hydrometallurgical treatment of base metals feeds, especially nickel laterites and polymetallic sulphides. One approach that has received some attention is the use of high?concentration chloride solutions (brines), which are now showing some promise after initial setbacks. Iron is usually the major component in the base metal feed to such processes, and if physical means cannot be used to remove it, then the iron concentration in the pregnant leach solution is always significant. This paper presents some of the background theory on the hydrolysis of iron in high-strength (>3M) chloride brines, and discusses the roles of temperature, solution concentration and free acidity. It is shown that the system is complex, but that crystalline and readily-filterable hematite can be generated, and that the system has a low energy requirement.

Jan 1, 2006