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By T. G. Joseph

A strain-softening constitutive relationship is introduced that describes the post-failure stress-strain curve for rock regardless of whether the rock is intact or broken. The core of this relationship is an ?apparent friction? concept that relates the post-failure apparent cohesive and frictional characteristics of the rock to the strain. The relationship can be determined for a given rock via a series of tri-axial strength tests establishing the peak strength and corresponding strain for a range of confining pressures, together with the determination of the base angle of friction via a simple tilt test. The postulates and assumptions used in deriving this relationship are verified from results of tri-axial tests on both intact and broken rock.

May 1, 2002

By N. Samman, S. N. Lau

"A series of new, grease-based, solvent free open gear lubricants were developed to meet the demanding service requirements of mining equipment. The use of these products has resulted in better performance under conditions of temperature extremes and in terms of longer component lives. They have gained widespread acceptance within the mining communities for such applications as the lubrication of mining shovels, draglines and ball mills.These products are WHMIS non-controlled and are environmentally acceptable. The benefits and advantages of using this type of product to lubricate mining equipment as well as the field evaluation and experience will be discussed."

Jan 1, 2002

By D. Janney

Kennecott's Utah Smelter commenced operations in June 1995 utilizing Outokumpu Flash Smelting (FSF) and Kennecott-Outokumpu Flash Converting (FCF) technology. After some initial teething and equipment problems the smelter achieved its design capacity in mid-1997 and now processes over 1.0 million tonnes of copper concentrate per year with exceptional environmental performance. The smelting furnace has operated for 11 years and the converting furnace for 5 years without major shutdowns. The first major smelter shutdown commenced in September 2006 after extensive planning. The FSF was completely re-bricked and the latest above and below bath containment systems installed. The FCF was inspected and re-bricked with some improvements made to the above bath containment system. The FCF life is now anticipated to be the same as the FSF. Numerous improvements and modifications were made to the rest of smelter facility including extensive upgrades to the dry electrostatic precipitators. Production ramp-up was smooth with the smelter now frequently operating at acid plant capacity.

Jan 1, 2007

By H. D. B. Wilson

"IntroductionRECENT ADVANCES in geo-chemistry and in •our knowledge •of crystal structure provide a key which enables us to create a systematic picture of the genesis of many ore deposits. This genetic scheme may be used with confidence in assessing certain types of orebodies and may be of some aid in actual exploration, since it affords a rational explanation of the dependence of the composition •of the ore minerals on that of the rock type in which they occur with which they -are •associated. For purposes of the present paper, .the elements chosen are •chromium, vanadium, iron, and titanium. The oxides of all these metals occur in deposits of similar or related type, and it is proposed to show that, for each, the composition of the •ore mineral is related to •the composition of the enclosing :rock, and that one of the principal factors controlling the composition of the ore is the ionic size of its constituent elements.Geochemical PrinciplesThe crystals of the rock-forming silicates and of the magmatic oxide minerals are essentially ionic types. This means that they are composed •of oppositely charged ions such as Mg²+ and 0²-, which are held together by electrostatic attraction. The ions of each element are spherical, with characteristic size known as the ionic radius. Crystals are built up by the packing of these spheres in the most stable arrangement compatible with the size and the size and valence of the ions• involved.Many of the principles governing the formation of ionic crystals are •simple ,and logical."

Jan 1, 1953

By W. W. Rudolph, L. N. Trevani, P. R. Tremaine

UV-visible spectroscopy, Raman spectroscopy, and vibrating tube densimetry have been used in our laboratory to determine equilibrium constants of aqueous species at temperatures as high as 325 °C. The UV-visible and Raman spectra of solutions containing metal complexes and ionized acids or bases can be used to yield formation constants by applying curve fitting methods to resolve the contribution of each species. Colorimetric pH indicators identified by Johnston and coworkers at the University of Texas (Austin) provide an alternative means of determining ionization constants and the pH of complex mixtures. High precision density measurements over the same range yield standard partial molar volumes, which are key parameters for "equations of state" for aqueous species. Examples are given for the copper-ammonia system, simple carboxylic acids, and the iron-sulphate system.

Jan 1, 2004

By Mario A. Morin

Mine design, planning and scheduling is a very complex, iterative process comprising several interrelated and interdependent activities. Understanding how this process works, identifying the critical pieces of information and the decisions to be made is key to initiating business process improvements (BPI) or business process reengineering (BPR) activities. Fundamental to most BPI and BPR work is some form of systems analysis. Structured Analysis is a powerful systems analysis technique that is well suited for modeling and analyzing complex process activities. Through a series of diagrams, this paper presents a vertical slice through the analysis work performed for formally describing the underground hardrock mine design and planning process. These diagrams illustrate how simple graphic constructs can be used to decompose the most complex situations into easily understandable diagrams that facilitate understanding, communication, improvement and reengineering.

May 1, 2002

By C. L. Reichardt

"Pressure exerted on gold producers by regulators, project financiers, and civil society in the wake of the Baia Mare tailings spill in Romania during 2000 prompted most responsible gold companies to sign up to the International Cyanide Management Code for the Manufacture, Transport, and Use of Cyanide in the Production of Gold (the Code). The Code stipulates a ‘cradle to grave’ approach more comprehensive than that applied to any other mining reagent and poses particular challenges for operators who use cyanide-bearing tailings for backfill. This paper examine some of the challenges for Code compliance facing deep underground gold mines that employ backfill technology, most particularly the requirement to demonstrate that the potential migration of cyanide (and its degradation products) from emplaced backfill will not have an unacceptable impact on worker health and safety or on the receiving environment, either during mine life or after closure.Although the Code only contains a single reference to backfill, more careful consideration confirms that most sections of the Code that deal with tailings management are potentially applicable to mines where tailings material is used for backfill. Certain principles of the Code also pertain to aspects of operations, worker safety, emergency response, training, and dialogue with stakeholders relating to backfilling practice.For gold mines of the Far West Rand, the most significant cyanide-related risks associated with backfill operations relate to worker exposure to cyanide-bearing seepage and HCN gas. There is potential for seepage of cyanide-bearing water from backfill to compromise the beneficial use of surface and groundwater, and thus impact on downstream users and ecosystems. However, the extreme depth of mining and the specific geological and hydrological controls on the Far West Rand suggest that the potential environmental risks associated with backfill are likely to be considerably less significant than the cyanide-related risks to the workforce."

Jan 1, 2007

By R. F. Sharpe

THE Bullion mine, in the famous Cariboo district of British Columbia, is situated on the left bank of the South fork of the Quesnel river, approximately three miles below the outlet of Quesnel lake. A good road leads 63 miles northeast to the property from Williams lake, the railhead on the Pacific Great Eastern railway. The mine may also be reached over good roads from Vancouver via the Fraser canyon, Ashcroft, Clinton, and the 150-mile house, a total distance of 407 miles. In the early days of placer mining on the South fork of the Quesnel, several rich bars were found. The 'pay' on one of these at the mouth of Dancing Bill gulch was followed up the gulch by a Chinese company, who proved to be the discoverers of the present Bullion mine. This Chinese company commenced working in 1884, in what was then referred to as the China pit. Although working under very primitive conditions, it is reported that, during the ten years they operated the property, they recovered in excess of $900,000 in gold. This somewhat large recovery was due to a local concentration, the result of Dancing Bill creek having meandered down that portion of the channel and washed off the overburden. In 1894, a syndicate composed largely of the Canadian Pacific Railway directorate of that time, with J. B. Hobson as their field manager, acquired the property, as the apparent magnitude of the operation was too great for the resources of the Chinese company. Mr. Hobson, during the first ten years of his regime, developed the mine into a large-scale hydraulic operation, and during that period, from 1894 to 1905, recovered approximately $1,234,000 in gold. In 1906, the property was sold to the Guggenheim Exploration Company, who retained Mr. Hobson as Manager and embarked on an extensive programme to bring in additional water. This project was never completed, however, work being suddenly abandoned in 1907 and the mine closed down. Shortly afterwards, the property was purchased by a small operator on what is believed to have been largely borrowed capital. This venture resulted in no production, but in much litigation, which eventually reached the Privy Council in 1920.

Jan 1, 1939

By A. K. Verma

This paper provides a brief overview of evolution of deformations, stresses, and pore pressures due to different excavation stages during construction of an URL. Excavation of a rockmass develops a damage zone of finite width around the excavated zone which is associated with changes in permeability and which affects the fluid flow mechanism. In this study, a coupled hydromechanical (HM) analysis has been conducted for a water saturated porous rock mass which has been created by sequential excavation and backfill of vertical disposal pit of an URL. For this purpose, an Atomic Energy of Canada Limited?s in-floor concept for a deep geologic repository suitable for Indian conditions has been used. Changes in rock deformations, stresses, strains and mechanically induced pore pressure in an undrained condition, during excavation, as well as those caused by mechanically induced rock deformations after backfill of the disposal pit, have been modeled. A three-dimensional finite difference tool FLAC3D has been used for the analysis.

Jun 1, 2012

By Dina M. Aloi

In today?s evolving and globalized world, mining companies are being pressured to move beyond compliance towards long-term sustainability and sustainable development. Companies are expected to ?engage? communities without a clear understanding of ?how? to do this or to what end. This move, away from compliance, develops more of a focus on ?Community? Social Responsibility and sustainability. This shift leads to the development of world-class projects that provide sustainable development for people, reduce the incidence of costly delays, and promote good global citizenship for companies. The process of ?engaging? communities in mining project design and development leads to a stronger license to operate, and a reduction in social and political risk. To create this mutually beneficial relationship between communities and companies, communities must be ?engaged? in the project development and risk assessment processes as early as possible, preferably during the exploration or the concept phases. How to create this ?engagement? and manage this risk will be discussed.

May 1, 2007

By M. Drozd, A. Ibrado, P. Butcher

While effective in treating refractory sulfide ores, pressure oxidation leaves carbonaceous matter unscathed and able to adsorb gold from cyanide solutions. Barrick Goldstrike's strategy to mitigate this problem is to minimize contact between dissolved gold and native carbon in advance of the carbon-in-leach (CIL) process. Measures currently in use include limiting carbonaceous matter in the plant feed by meticulous blending of ore, controlling the degree of oxidation in the autoclaves and blinding native carbon surfaces with lauryl sulfate. The presence of residual cyanide and thiocyanate in the process water remains to be a cause of premature gold dissolution and loss of gold by adsorption on carbonaceous matter. This cyanide is introduced by water that is recycled from the tailing pond. Of several treatment options considered, oxidation by peroxymonosulfuric acid, also known as Caro's acid, is deemed to be the most effective. Laboratory and pilot plant tests show that Caro's acid can oxidize free cyanide, weak¬acid-dissociable (WAD) cyanide and thiocyanate, resulting in significant improvements in gold recovery downstream. The process requires Caro's acid at 125 % of the stoichiometric requirement and pH in the range of 9.5 to 10 to accomplish the desired destruction in about twenty minutes. A cyanide destruction plant is currently being designed and construction should be completed by the end of 2005.

Jan 1, 2005

By L. R. Plitt

A new simple correlation has been developed to evaluate the performance of classifiers. The new correlation has been tested on existing data from 150 different hydro-cyclone classification tests. It is shown that this model provides a meaningful improved method of mathematically describing the classification process.

Jan 1, 1971

By S. Hume, J. Shepherd

Meso-2,3-dimercaptosuccinic acid(DMSA) was studied as an additive for thiosulfate leaching of gold. DMSA was added to solutionscomposed of either sodium thiosulfate or calcium thiosulfate and the solutions were tested for their ability to leach pure gold samples as well as a calcined gold ore from Barrick Gold Corp. Results showed prolonged leaching of pure gold samples when DMSA was added at a concentration of 5µM; however, higher concentrations were shown to inhibit leaching. Differential capacitance measurements of the interface indicated that DMSA adsorbed as a defective monolayer on the surface of gold at low concentrations and formed a more compact monolayer with increased concentration. It is proposed that a concentration of 5µM DMSA produces a defectivemonolayer on the surface that still allowsthe transport of oxidants to the underling metal while inhibiting the formation of polysulfide passive layers that arise fromdecomposed thiosulfate.The 5µM DMSA/CaS2O3 system was also studied using calcined ore. Results showed that the initial leaching rates in the presence of DMSA are lower than those obtained in thiosulfate alone. However, after 10h, prolonged leaching is again observed when DMSA is included.

Jan 1, 2015

By M. Zamalloa, P. J. Mackey, P. Coursol, Y. Prévost

"Over the last decade or so, the availability of commercial thermodynamic modelling packages, such as FactSageTM, have been utilized to help the plant optimize slag chemistry and to minimize slag handling issues that can arise, such as those due to a process upset, for example, by undue feed variability. This paper illustrates an extension of the application of this software in examining a large range of NCV operating parameters, such as the %Fe/SiO2 ratio in the slag and the level of minor gangue components in the slag including CaO, Al2O3, ZnO, MgO, and PbO. The conditions influencing the slag liquidus range of NCV slag are discussed with respect to the overall process chemistry.Given that a sufficiently low %Fe/SiO2 ratio is used in NCV slag, most components such as CaO-ZnOPbO- Al2O3-MgO, in small concentration, all contribute to lowering the NCV slag liquidus. Considering the present level of these minor components, the NCV can operate consistently at 1200°C if the %Fe/SiO2 is between 0.6 and 0.8 in the slag. Using the type of phase diagrams presented in this paper, it is possible to develop different Noranda reactor/Noranda converter operating strategies adapted to the feedstocks available at Xstrata mines/plants or from other sources. The NCV is unique in that a fayalite-based slag is employed for high-efficiency continuous converting with excellent operating results."

Jan 1, 2007

By T. V. Simpkinson

Abstract A brief history of the electric arc furnace process of steel-making is given. The greater relative importance of this method of steel manufacture to the Canadian steel industry, as compared with its importance in the steel industry of the United States, is shown. The scope of the process is outlined and brief mention is made of the difficulty of obtaining melting stock low in alloy content. The physical chemistry of steel-making is discussed at length in simple terms, with emphasis on oxidation, de-oxidation, and the role of hydrogen. Carbide-type and silicon-type slags are described and the particular usefulness of each is outlined. The importance of various factors in the melting practice is evaluated on the basis of practical experience. Introduction Although electric furnace steels constitute only a small portion of the total weight of steel used in industrial operations, their importance is relatively much greater than is indicated by comparative tonnage figures. Tool steels, which are vital to all industry, are made almost exclusively by the basic electric arc furnace process, as are stainless steels, valve steels, and the higher alloy types of the class usually referred to as "alloy steels'. For many applications where steel other than electric furnace quality is often used, and when first cost is secondary to performance in service, the extra steel cost of electric furnace quality material is usually returned with interest by consistently longer service life. The electric furnace is pre-eminent in the quality alloy steel field because of the control that may be exercised over conditions of oxidation, de-oxidation, and temperature, the fundamental operations in steel making.

Jan 1, 1948

By T. Rigg, J. N. Stone

"The process described has been developed to utilize low-grade scrap -turnings, borings, tin cans and other types of ferrons scrap which currently has been of limited or no use in conventional steelmaking processes. If scrap of this type can be converted into high-purity iron by chemical means then there is a potential saving of several million tons of metal annually in North America.The process is chemically quite simple and consists of dissolving ferrons scrap in hydrochloric acid, followed by evaporation and crystallization of the resultant solution to yield ferrons chloride crystal.s. These crystals are dries, briquetted and converted to non sponge by reduction in hot hydrogen. The HCl produced from the reduction step. is absorbed in water and the hydrochloric acid so produced is returned to the dissolver circuit. The hydrogen produced from the initial dissolution of the scrap is used to reduce the ferrons chloride. Purity is maintained by bleeding off impure chloride solutions from the evaporator-crystallizer circuit, and converting these chlorides to oxides and HCI in a high-temperature spray roaster. The HCl produced in the roaster is absorbed in water and the hydrochloric acid returned to the dissolver."

Jan 1, 1970

By Scott A. Stebbins

Cost evaluation models constructed specifically to evaluate the economic potential of an individually motorized railcar system of ore and waste transport demonstrate that the approach may be considerably more cost effective than traditional rubber-tired haulage methods. The system design places a motorized drive unit on each railcar, as opposed to the more common configuration in which a series of un-motorized cars trail behind a single locomotive. These motorized railcars are directed to various load and dump points by a computerized dispatch system, and as such have the advantage of operating unmanned. In addition, the tractive effort of the rail-type drive system is noticeably more efficient than that of the rubber-tired mode of transport. The savings are realized primarily through comparative reductions in the requirements for labor and, to a lesser degree, energy.

Nov 1, 2011

By H. Watari

In 1998, a voluntary agreement was reached between the European Commission and the European Car Manufacturers Association (ACEA) to reduce average carbon dioxide emissions of new cars to 25% below 1995 levels by 2008, Agreements have also been reached between the European Commission and the Japanese Automobile Manufacturers Association (JAMA) and the Korean Automobile Manufacturers Association (KAMA), However, the target average of carbon dioxide emissions of less than 140g/km in 2008 is a very challenging goal, Therefore, total product weight reduction is an objective for many manufacturers, This can be achieved utilizing materials possessing high strength and low weight, One material that has recently attracted interest is magnesium alloys, The magnesium alloys are expected to play an important role as next-generation materials, which have possibilities of contributing to lighten the total product weight when magnesium products can be used to replace aluminum and mild steel products.

Jan 1, 2005

By Nicholas J. Welham

"The effect of extended ball milling has been studied for two industrial processes: (1) the processing of metal sulphide concentrates; and (2) the carbothermic reduction of ilmenite to synthetic rutile. The plant concentrates were a gold ore with 128 g/t Au of which 8% was non-refractory and a zinc concentrate with copper impurities.The gold concentrate showed complete dissolution of the gold bearing minerals after milling giving almost complete gold liberation. The zinc concentrate showed almost all of the sulphides had solubilized leaving the gangue and elemental sulphur. A study of pure pyrite and arsenopyrite shows that selective dissolution should be possible by a simple leaching process directly after milling.The milling of ilmenite and coal together results in a temperature decrease of 150°C in the subsequent carbothermic reduction of ilmenite, in addition to improving both the rate of reaction and the selectivity of reduction to rutile. IntroductionAlmost all mineral processing plants use mills for the size reduction of particles prior to physical and chemical processing. When continuing beyond size reduction the energy transferred causes deformation, breakage and realloying of particles giving a steady-state particle size. The breaking also causes increasing damage to the crystal structure by formation of smaller grains giving an increasing number of grain boundaries and increasing crystalline defects due to deformation. The increasing number of grain boundaries and defects leads to increased reactivity, which can be seen directly by a reaction within the mill, or indirectly, via a decrease in the subsequent annealing temperature required for reaction."

Jan 1, 1997

By J. Bouchard, A. Clapperton, L. Ebacher, N. Singh

"Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Froth flotation is used to produce nickel and copper concentrates. As is the case at other operations, the presence of magnesium is detrimental to the flotation products. In the past year, the exploitation of a new deposit has increased magnesium in the feed. Thus, it has been challenging to meet the required ratio in the final nickel concentrate. In search for a consistent solution for this problematic, an empirical flotation simulator making use of selectivity curves was developed. The circuit was expressed as a system of linear equations, which considered the distribution of copper, nickel and gangue minerals in the different streams. The relative quantities of each mineral are given by the separation efficiency curves of the various banks in the circuit. Three sources of data were used to calibrate the simulator: historical plant data (metallurgical balance), infinite dilution bench-scale flotation tests, and direct sampling of flotation cells. The calibrated separation curves were used to predict the recovery of the different species based on a single mineral recovery. Validation of the simulator showed good fit for the valuable minerals. The simulator was then used to infer the optimal operating conditions of the flotation circuit to optimise magnesium oxide content of the nickel concentrate. Simulation of two re-arrangements of the circuit gave a promising solution with a Fe:MgO ratio 2.42 times higher than the minimum value.INTRODUCTION Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Figure 1 shows the location of the mine site. After crushing and grinding, froth flotation is used to produce nickel and copper concentrates. The flotation circuit is designed with multiple stages consisting of bulk copper/nickel flotation, copper/nickel separation, and a separate nickel circuit (bulk float and cleaning)."

Jan 1, 2018