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By J. Gebhardt, D. McBride, C. R. Bennett, Croft. N., M. Cross

A comprehensive model of solution flow through heap leach systems requires a numerical solution with the ability to predict variably saturated-unsaturated flow through porous media domains that contain materials with spatially variable properties. The types of flow associated with stockpile leach processes lead to flow problems, such as infiltration into dry soil, drainage, perched water tables and flow through heterogeneous materials. Computational methods for modelling this class of flow behaviour are conventionally based on the classical Richards' equation. However, the governing equations are highly non-linear, difficult to solve, and require iterative numerical solution methods. The pressure-based form of the Richards' equation suffers from poor mass balance, while the mixed form can possess convergence difficulties. An adaptive transformed mixed algorithm is described, which reduces the non-linearity of the problem, optimizes the time step size, and provides a fast, numerically robust scheme that significantly reduces computation (or CPU) time. This method is shown to give fast, accurate solutions on a number of complex flow problems. The utility of this algorithm is illustrated through its implementation within the PHYSICA computational modelling software, which incidentally, provides a framework for a comprehensive heap leach model.

Jan 1, 2005

By B. Yamamoto, D. Post, J. De Leon, A. Meike

"This paper describes the theory, design, building, and testing of the passive magnetic bearing stabilizing system which is the core of the passive magnetic bearing system. The stabilizing system is made up of two large magnetic disks opposing themselves with a stabilizing disk in the center which allows the system to self-locate in a null position without the need for external power sources or sensors. When outside forces act upon the stabilizer, the magnetic fields interact with the stabilizing plate to return the system to its null position. Collaboration between two industry leaders has allowed an actual prototype to be built and tested providing real data to prove out the theory.INTRODUCTIONMagnetic bearing/stabilizer systems have many advantages over conventional mechanical bearing systems. These include near-zero drag losses and no need for lubrication since the rotating elements make no mechanical contact with the stationary elements of the bearing system. However all magnetic bearing systems must contend with a constraint known as Earnshaw’s Theorem in the early 1800’s, this theorem asserts the impossibility of constructing a stable, non-contacting, electrostatic or magnetostatic levitation system using only fixed charges or fixed magnetic poles, such as those produced by permanent magnets. Because of the constraint imposed by Earnshaw’s Theorem virtually all present-day commercial magnetic bearing systems are of the “active” type. That is, they employ electromagnets that are powered by amplifiers the inputs to which come from sensors embedded in the bearing system. These sensors are a part of a feedback loop that operates to keep the levitated rotating parts of the bearing stable and centered. The resulting complexity means that active magnetic bearings are expensive, require periodic maintenance, and continuously consume electrical power to energize their amplifiers and their electromagnets.Passive magnetic bearings are, of course, also subject to the constraints imposed by Earnshaw’s Theorem but they solve this problem in a straightforward and simple way, with only “passive” elements that take advantage of a loophole implicit in the derivation of Earnshaw’s Theorem. This loophole is that Earnshaw’s Theorem as derived applies only to static systems, i.e. an assembly of stationary permanent magnets arranged so as to levitate an object containing other permanent magnets. The theorem can be overcome if dynamic effects are taken into account. In active magnetic bearings the “dynamic effects” involve the afore-mentioned sensors, amplifiers, and electromagnets."

Jan 1, 2012

By Kenneth Blower

This paper gives a detailed coverage of the ore flow through the primary crusher, cobbing plant and concentrator, including equipment sizes, recoveries, reagent consumptions and product descriptions. Special features, such as rubber chutes, rubber-lined mills, pebble-mill grinding, steam-hooded filters and process control instrumentation, are also discussed.

Jan 1, 1968

By L. Lafrenière

A trend in mining exploration is to increase the number of geophysical parameters collected and interpreted for geological features in a given area. Airborne technology now allows us to simultaneously combine electromagnetic, gravity, aeromagnetic and radiometric surveys. We report the results of a multiparameter survey conducted in the area of Kamiskotia, Ontario. This area is located near and on the West side of the multi-metalliferous Kidd Creek deposit. Various metallic occurrences are reported in the studied area. Integrating multiple parameters in the interpretation produces a more detailed pseudogeological map than what has already been published. 3D interpretation has been undertaken using some of these parameters and suggests that future work is required in 3D earth model solutions in order to fully use all parameters.

Aug 1, 2013

By P. M. Chapman

Risks to aquatic receiving environments from uranium mining and milling fall into three categories: physical (habitat change), chemical (e.g., uranium, selenium, total dissolved solids [TDS], metals including vanadium), and radiological. Although all categories of risk need to be managed, chemical risks are the most significant and are typically chronic rather than acute. For instance, selenium toxicity is primarily manifested as reproductive impairment due to maternal transfer, resulting in embryotoxicity and teratogenicity in egg-laying vertebrates. Risk is best assessed using a weight of evidence approach focused on ecosystem services. Risk management should be based on both risk assessment and adaptive monitoring.

Aug 1, 2010

By Eduardo A. Pérez, Alejandro R. Alonso, Rosa María Luna-Sánchez, Gretchen T. Lapidus

Rare earth elements have been widely used in various sectors, from the aerospace and steel industries, to electronic applications, particularly in displays and batteries for portable devices. The high demand for newer and better equipment, such as cell phones, tablets and lap tops, has increased the consumption of the rare earth elements and at the same time the need for its recovery from electronic wastes. For that reason, the recycling of batteries is important, principally the Ni-HM batteries, due to their elevated content of rare earths elements, in addition to the high concentrations of cobalt and nickel. The current processes are based on dissolution in strong acid solutions (sulfuric acid concentrations from 2 to 4 mol/L), and temperatures from 30 to 90°C. In the present work, electrodes from spent Ni-HM batteries were leached using 1 mol/L H2SO4, in the presence of ozone as the oxidant, where recoveries of 96% for La, Ce and Nd were obtained at room temperature. The separation of Ni and Co from the leach solutions was performed using an electrochemical reactor, after which rare earth elements were precipitated, obtaining a mixture of its hydroxides with impurities below 1%, according to EDS analysis.

Jan 1, 2014

By P. Abachi

Cemented carbides or hard metals that generally consist of hard tungsten carbide and a tough metal binder such as cobalt are important in many segments of the world economy, ranging from automobile related components to machining, cutting, and drilling tools. For metal cutting operations such as turning and milling, replaceable cemented carbide inserts are frequently used. The exposure of inserts to very severe conditions (e.g. temperatures as high as 1000°C) in combination with very high loads, limits their lifetime. When the tools and components are scrapped, they are collected with a view to recovering the tungsten carbide and cobalt due to both their environmental aspects and their strategic importance. In this work, a selective electrolysis process was used for recovery of WC powder particles from cemented carbide scraps. The WC-10Co and WC-10Co-VC up to 3 wt.% VC was produced using powder metallurgy route. The mean particle size of WC, Co and VC were selected as 2.5, l.5 and 2.2 µm respectively. Referring to electrochemical curves of WC-10Co cemented carbides in hydrochloric acid solutions with different concentrations, the recovery rate was enhanced in IN acid. Therefore, this solution was selected for recycling of all samples. The surfaces of as-produced and corroded specimens were investigated using a scanning electron microscopy (SEM). Detection of corrosion products was provided by energy dispersive spectrometry (EDS). According to results, the selective electrolysis process could be useful in the recycling of scrap carbide materials, although more studies should be undertaken on economical aspects of the process and the quality of samples produced using recovered powders.

Jan 1, 2005

By Yulin Zhou, WenFeng Li, Wen Chen

"In this article, with the help of the X-ray photoelectron Spectroscopy (XPS), a modern test method, all the characteristics of the chlorite,and adsorption collector A6 on the surface of chlorite have been studied. There exist abundant carboxylic C-O and C=O structures in the Carbon XPS atlas with strong adhesive ability after the reaction between new collector A6 and chlorite, which indicates that the ring structure and ether-base functional groups can strengthen the reaction between collector A6 molecule and chlorite surface. The results of XPS analysis indicate that the photoelectron spectroscopy peaks of Mg2p and Al2p moved towards low energy after collector A6 absorbed on chlorite surface, which indicates that chemical bonding through electron cloud transfer happened between collector A6 and Mg, Al ions of chlorite surface. The chemical reaction promoted the adsorption of A6 on chlorite surface and eventually improved the ability of A6 to float and collect chlorite.INTRODUCTIONThere are a large amount of iron-bearing silicate minerals such as chlorite in different types of gangue minerals in iron ore from different areas besides quartz (Yingyong et al, 2012; Qiang et al, 2009). There always exist Mg2+, Al3+ Fe3+ and other metallic ions due the isomorphic replacement among the irons of this kind of minerals. The dissolution often occurs on the surface of minerals with abundant metallic ions during grinding process, and some ions are exposed on the surface, such as Mg2+, Fe3+, Al3+, Si4+, which can increase the surface electrical behaviour of iron-bearing silicate minerals (Wanzhong & Chuanyao, 2002; Yuping et al., 2007), making it easy for the surface to react preferentially with the depressants such as causticizing starch which making it impossible for the surface to reach with conventional anionic fatty acid collector (Mowla et al, 2008). Thus, the beneficiation efficiency is dramatically decreased and the improvement of concentrate grade becomes very difficult. The conventional aliphatic acid collector has some defects such as poor selectivity, poor low temperature resistance, sensitive to water hardness, etc. Thus, the addition of synergist (Liu, & Yu, 2015) or other compound reagents (Zhou et al, 2015) can promote the adsorption of reagents to mineral surface, and improve the collecting capacity and selectivity of aliphatic acid collector to minerals. The addition of polar group to nonpolar group in aliphatic acid can improve the water solubility, dispensability and hard water resistance (Tian et al, 2013). The nitrogen atoms in amid ate aliphatic acid collector can adsorb on mineral surface by itself and supply coordinate electron which can form chelating keys to improve the collecting capacity of collector. There exist coordinate electron in oxygen atoms of ether acid collector, which, along with the oxygen on carboxyl compose chelate with metal (Luo et al, 2015). There are also exist some opinions that the ether acid can arrange into similar crown ether structure which can absorb on mineral surface. A new alicyclic unsaturated ether acid compounds collector A6 is adopted in this paper, the structural formula is listed in Figure 1. The A6 has a strong collecting ability to chlorite with strong water solubility and low temperature resistance."

Jan 1, 2016

By F. W. Wellmer

"I would like to comment on the classification scheme of ore reserves based on geestatistical and economic parameters as proposed by Wober and Morgan in the CIM Bulletin, January 1993.In principle, a classification system that combines quantitative data for levels of confidence and errors with economic expectations must be welcomed. I would like to point out, however, two aspects of the proposed classification system which might create ambiguities, and therefore problems, by working with two levels of confidence and two kinds of block sizes. A normal classification scheme reflects the information density, the highest reserve category such as class A, or proven, or measured reserves having the highest density. This is not necessarily the case in the scheme of Wober and Morgan (1993), unless the definitions are amended.I. Assuming, as the authors do, that the estimation errors show an approximately normal clistribution, at the 95% confidence level, the standard deviation has to be multiplied by about 2 for the error and, at the 84% confidence level by about 104. Reserves (or resources) with the same or even higher information density than class A reserves, which at the 95% confidence level would not fulfill the required economic criteria at the threshold level, i.e. not qualify as ""ore"" at all, could be retained ""on paper"" to class B reserves by just multiplying the standard deviation by the factor 104 instead of 2, thereby narrowing the error.This statistical ambiguity was partly inherent in the old German classification scheme which used varying confidence levels and errors (GDMB 1956; Jahns 1959). In the new German scheme, which was later adopted in Austria in a moclified version, the level of confidence was therefore fixed at 90070 for all reserve categories (Wellmer 1983; ONORM 1989)."

Jan 1, 1993

By J. G. Schofield, R. C. Francki, K. M. Donaldson, F. E. Ham

"Developments in pyrometallurgical technology have led to larger furnaces operating under more intense process conditions. In order to maintain the reliability of these furnaces, which are frequently single-line units, the design of the refractories, cooling systems and bindings has become more critical. Traditional thermal and chemical requirements for the refractory to resist slag attack must still be carefully determined. The larger, modem furnaces have placed a new emphasis on the structural properties of the refractories as well as their thermal properties to suit the extensive cooling systems. Based on operating experience, supported by computer models, the refractories and bindings are designed to work together to accommodate the thermal expansions and contractions in order to minimize permanent furnace growth and the risks of leaks. IntroductionElectric furnaces are used extensively in smelting copper and nickel ores and concentrates. Laterite nickel ores and high-magnesia copper, nickel and platinum sulphide concentrates are smelted virtually exclusively in electric furnaces to accommodate the high melting point of the slags produced. Although a number of smelting processes using oxygen-enriched and/or preheated air have been developed to replace reverberatory furnace smelting of conventional copper and copper-nickel concentrates, (lnco, Noranda, Outokumpu, Mitsubishi) electric matte furnaces remain a strong process alternative for these concentrates, either as the primary smelting vessel or for cleaning the slags produced from these processes.The development of large, high-powered furnaces has been an important factor in the growth of electric smelting technology, as evidenced by the list of operating matte and ferronickel furnaces shown in Table I. Because the compressive forces required to maintain a tight, leak-free furnace increase with furnace dimensions, the selection and design of the furnace refractories, cooling systems and bindings require increased attention."

Jan 1, 1993

By P. G. Hallof

The exploration staff of Campbell-Chibougamau Mines Limited has used past experience to delineate several areas of geologic interest under Lake. Chibougamau. Du• ring the winter of 1964-65, a reconnaissance induced polarization survey was carried out on the lake. First, several lines were surveyed over the known mu1.erahza-tion at the Henderson mine; the grid was then extended into the areas of interest. Several anomalous zones were located and drilled; one, of these proved to be of economic interest.

Jan 1, 1967

By L. B. Tsymbulov, L. Sh. Tsemekhman, A. N. Golov

Gipronickel Institute, JS is developing a process of continuous converting of Nicontaining copper matte and concentrates resulting in the production of blister copper and fluid NiO-containing slag in a two-zone Vaniukov furnace. The process under development is an alternative for the existing technology of blister copper production in converters, the latter being characterized with insufficient sulphur utilization, low direct copper recovery and the production of inconvenient for further processing solid slag on the basis of NiO and NiFe20 4- The results of pilot testing on processing of copper concentrate obtained from high-grade matte (HGM) separation in the two-zone Vaniukov furnace with the hearth area of 11.4 m2 are presented.

Jan 1, 2007

By T. A. Chepushtanova, I. U. Motovilov, V. A. Luganov, G. D. Guseynova

"Kazakhstan has significant reserves of oxidized nickel ore with low nickel content. Processing of such ores is effective via pyrometallurgical technologies such as smelting to ferronickel or matte with consecutive extraction of metals from melting products. There are also many options for direct hydrometallurgical processing. However, they do not provide high nickel recovery.We studied extraction of nickel and cobalt by using combined technology of low-grade ore processing from the Shevchenko Kazakhstan deposit, which includes smelting to poor matte followed by hydrometallurgical processing of the matte. The nickel content in the initial ore was 0.75–0.9%. Pyrite concentrate of Sokolov-Sarybai Kazakhstan deposit containing 0.17% cobalt and 0.06% nickel had been used as a sulphidizer at smelting.As a result of the study, we were able to extract up to 98% of the nickel and up to 80% of the available cobalt. Obtained matte contained 3.1% nickel, 0.29% cobalt, 71.6% iron and 24.3% sulfur. Matte leaching was carried out by hydrochloric acid. The iron content in the pregnant solution was 170–185 g/dm3. Nickel and cobalt precipitation from the pregnant solution was carried out by hydrogen sulfide. Initial matte or cast iron was used as neutralizers during the process. Practically complete precipitation of nickel was achieved at 3–5% excess of neutralizer at 333–343°K in 4 hours; up to 95% of cobalt precipitation was achieved in 50% excess of neutralizer at 363°K in 8 hours. The purified solution contained 200–600 mg/dm3 of nickel, 80-100 mg/dm3of cobalt and 175–185 g/dm3 of iron. The purified solution allows to obtain iron oxides by high-temperature hydrolysis, and to regenerate hydrochloric acid.As a result of non-ferrous metals precipitation we obtained sulfide concentrate with concentration of Ni up to 25% and concentration of Co up to 5.5%. The technology is recommended for semi-industrial testing."

Jan 1, 2016

By M. A. EI Zeky, A. E. El-Nikbaily, M. A. Shahin

"Possible mechanisms of microsilica dust formation and factors affecting its quantity have been discussed. General mathematical models to predict the dust quantity based on electrical and coke consumptions, and flue gas temperature as functions of silicon recovery in the process and silicon content of the alloy have been established. It has also been shown that the flue gas temperature can be used as an additional process control parameter. Comments are made on the effect of the dust formation on the whole process economics and it is pointed out that the formed microsilica dust is a valuable by-product and not an industrial waste. INTRODUCTIONFerrosilicon is produced in electric arc furnaces with submerged electrodes. The charge mixture consist s mainly of quartzite, coke as the reducing agent and iron chips. The products are ferro silicon and carbon monoxide, various other volatile materials, water vapour and silicon monoxide gas. Carbon monoxide and silicon monoxide oxidize at the charge surface when mixed with air entering through the furnace hood openings. The off-gas contains a considerable amount of dust, which is mainly very fine particles of silica formed as a result of oxidation. The emission of dust containing gases to the atmosphere causes serious pollution problems to the environment. Therefore, the control of the formation of the dust, preventing it from escaping to the atmosphere, and dealing with this very fine dust collected from the flue gases represent important technological and economical parameters in the ferrosilicon production industry.This paper is concerned with the relations between the quantity of formed micro silica dust, as a function of both silicon recovery and silicon content in the alloy, and various other technological parameters; and their possible effects on the energy consumption and economics of the whole process."

Jan 1, 1989

By R. Loney, M. Militzer

There is a significant demand for new high strength steels with fine grain sizes for structural applications. One approach in this regard is to develop hot-rolled HSLA steels where refining the microstructure leads to increased strength levels, e.g. 700 MPa yield strength, that can be attained by suitable modifications of chemistry and processing. Here, an HSLA steel is investigated that contains 0.05wt%C-1.65wt%Mn-0.20wt%Mo¬0.07wt%Nb-0.02wt%Ti and approaches the above strength class. The ability to control and predict the mechanical properties of hot rolled steel depends strongly on the thermomechanical processes, which the steel undergoes. The final microstructure and, thus, the properties of the hot-rolled steel are a function of the austenite decomposition obtained during accelerated cooling on the run-out table and precipitation during coiling. The austenite-to-ferrite phase transformation under run-out table conditions has been investigated using a Gleeble 3500 thermomechanical simulator equipped with a dilatometer. The effects of cooling rate and initial austenite microstructure including the degree of work hardening on austenite decomposition kinetics and ferrite grain refinement have been quantified. Results show that grain refinement can be optimized by the presence of work hardened austenite and accelerated cooling. Based on the experimental results, a model is proposed to predict the transformation start temperature and the resulting ferrite grain size for run-out table cooling conditions.

Jan 1, 2004

By S. Sundararajan, Z. Lin

ABSTRACT Fierce market competition and demand have made it imperative for mining companies to achieve higher productivity and operational efficiency. The selection of the best mining method and equipment combinations will enable companies to meet production and efficiency targets. Continuous mining is increasingly preferred by companies for its high efficiency and low unit costs. We developed simulation models for two continuous mining systems: the continuous surface miner (CSM) system and the at-face slurrying (AFS) system. Considering two different case studies, the paper discusses application of developed models to determine the optimal number of trucks and equipment capacities for the two systems.

Jan 1, 2013

By Nicholas Bonderoff, Amily Xu

The evaluation of battery electric vehicles (BEVs) in underground mines involves comprehensive business case analysis beyond just the capital and operating costs of the equipment itself. BEVs demonstrate benefits from an EHS perspective, reduced mine ventilation costs, lower energy operating costs, reduced overall GHG emissions (dependent on the source of electricity), elimination of DPM, lower equipment maintenance costs, and reduced cooling requirements in deep mines. When including batteries and supporting infrastructure, BEV capital costs are approx. 80% greater than that of diesel equipment. The project economics are highly dependent on the cost of electricity and diesel fuel, and these can vary widely depending on the location of the mining operation. Battery charging and swapping methodologies must be evaluated as there are a variety of approaches that can be employed which vary by manufacturer and type of equipment. Careful consideration of the cycle times, charging methodologies, and location of the battery charging infrastructure is necessary. Specific operating conditions must also be taken into consideration. For example, the time for blast gases to clear will be increased by reducing ventilation flow, and the potential impact on production needs to be evaluated. Similarly, the electrical distribution system needs to be evaluated for peak loading conditions when BEVs are charging. Criteria including maintainability, reliability, commercial availability, and performance need to be evaluated. BEVs have fewer components than diesel equipment and this correlates to lower overall maintenance costs, however, BEVs require maintenance personnel with specific skill sets in order to maintain the equipment. Battery lifecycle costs need to be considered as battery replacement incurs significant capital expense. Some manufacturers offer services to offset these capital costs through usage agreements. Recycling and disposal of batteries at the end of their lifecycles also need to be considered. With the increased selection of BEV equipment that will be available in the next 2-4 years, 100% BEV adoption is also possible. We recommend a holistic approach when evaluating BEVs for underground mines. This will ensure that everything is considered in order to evaluate the full impact of BEV implementation.

Jan 1, 2023

By R. C. E. Bray, Peter Price

"The property of Pamour Porcupine Mines, Limited, is in the eastern Porcupine area, about 12 miles northeast of Timmins. It covers parts of lots 3-6 (inclusive), cons. 5 and 6, Whitney tp., Cochrane district, Ontario. It is an amalgamation of the old La Palme, Three Nations, and Porcupine Grande properties.The first discovery on the Pamour was made in 1911. During 1911 to 1914 a small shaft was sunk on the Three Nations vein to the 200-foot level and a 100-ton stamp mill was put in operation, but only a small production was achieved. The property remained idle from 1914 to 1923. In 1924 some diamond drilling was done along the Keewatin-Timiskaming contact with some encouraging results, but the gold mineralization encountered was too low in general at the price of gold then prevailing to warrant further · work. The increase in the price of gold revived interest in the area, and the above noted amalgamation was effected in 1934. Options were taken and successively dropped by two large mining companies. Following this, exploration both on the surface and underground was started by Quebec Gold Mining Corporation, Limited. Diamond drilling in the early part of 1933 showed considerable ore in conglomerate and greywacke to the east. In the middle of 1935 Noranda Mines, Limited, assumed control and management. A new shaft was sunk and the property was ·equipped with a mill having an initial capacity of750 tons a day. This was subsequently enlarged to 1,500 tons a day.From the commencement of milling (May 16, 1936) to the end of 1946, 5,025,545 tons of ore having an average grade of 0.1327 oz. a ton ($4.64 at $35 an oz.) have been mined and milled."

Jan 1, 1954

By L. Dufourm

This paper presents a review of plant layout considerations incorporated into recent designs of SAG/Ball mill circuits for two medium sized concentrators. The plant layouts presented and the design concepts discussed, relate to smaller SAG circuits, but can equally apply to larger milling circuits. Included are design concepts and ideas introduced by the various project teams, and the focus is on the primary factors of any layout design which are safety, constructability, operability, and capital cost.

Jan 1, 2012

By Sadough vanini Ali

Hot deformation behavior of functionally graded steel (FGS) was investigated via conducting hot compression tests at different temperatures and strain rates. Functionally graded steels consist of ferrite, austenite, bainite and martensite layers that are made by diffusion of alloy elements during the melting process. The zenerhollomon parameter has been used to describe the flow stress variations as a function of temperatures and strain rates. The parameter values for all the layers via using the boundary conditions was determined based on composite graded behaviors. Furthermore by applying the rule of phase mixtures, the whole strain rate applied on composite would be the sum of layers strain rates considering the layers volume fraction, while the layers have the same stress. Consequently the composite flow stress for each strain rate and temperature was determined.

Oct 1, 2011