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By A. D. Davis

The disposal of spent ore from cyanide heap-leach processing facilities is of concern to the mining industry, regulatory agencies, and the public. Disposal of several hundred million tons of additional spent ore is planned in the western United States during the next decade, with increased amounts likely if gold prices rise. In the past decade, more than fifteen million tons of spent ore have been disposed of in the Black Hills. South Dakota's off-loading criterion for cyanide has been set by the state's Department of Environment and Natural Resources at 0.5 parts per million (ppm) as weak acid dissociable (WAD) cyanide. Nitrate off-loading limits vary for each mine in the state, depending on ore type and other factors. Nitrate concentrations in leachate from spent ore depositories could be caused by conversion from other nitrogen-containing species. One likely source of nitrate is residual explosives from blasting of ore. Previous work on the combustion products of nitrogen explosives has shown incomplete 3xidation (Johansson and Persson, 1970). Another likely nitrate source is degradation of cyanide to ammonia, followed by oxidation to nitrite and nitrate.

Jan 1, 1994

An atomic force microscopy (AFM) has been applied to study the adsorption of collectors on mineral surfaces in a copper/molybdenum flotation system. AFM images show that collectors absorb on chalcopyrite surface in patches at pH 11. A study of temperature effect on surface morphology excludes the possibility that these patches are nanobubbles forming on hydrophobized mineral surface. Hydrocarbon oil absorbs on molybdenite quickly, while KEX (potassium ethyl xanthate) has little affinity for molybdenite. Pyrite is much more reactive in water and its surface is easily coated in Ca(OH)2 solutions at pH 11. Based on the obtained AFM images, the adsorption of chemicals on mineral surface and its impact on copper/molybdenum flotation were discussed.

Jan 1, 2012

By Raymond L. Jones

With the inauguration of the open pit operation in Bagdad, plans were formulated for a large scale leaching operation. Dump stockpiling was started almost immediately, but actual production was not initiated until the spring of 1961. Like all neophytes, we started something about which, on a commercial scale, we knew next to nothing, either dump preparation or leach procedure, and as a consequence, we are still paying the piper. True, we had been through an extensive laboratory pilot program, but it soon became apparent that there was considerably more to increasing solution volumes than simple multiplication. Had we initially possessed our present acumen, the Cyprus Bagdad plant could be operated more efficiently and at a better profit. During the past several years, the art of dump leaching of copper has improved in many ways, primarily because of the application of scientific principles gleaned from general mining practice. Rigid pH control and the use of atomic absorption techniques for rapid," accurate assaying have probably played a leading role in this respect, although we cannot overlook the other sophisticated electronic controls lending improvement to acid addition and pumping, better piping materials, and lastly, the more efficient use of our pregnant liquors. Thin too, the years of experience have given us a greater understanding of dump behavior in general; and, we can, to a greater extent, measure, predict, and avoid some of the idiosyncrasies inherent in every dump. However, it is my firm belief that we will still be confronted with unexplainable dump behavior as long as we are involved in leaching. We have found our dump to be a wonderful money bank, but one that is capable of yielding a wildly fluctuating profit.

Jan 1, 1975

The Sage Mill Project w approved by Santa Fe Pacific Gold Corporation's Board of Directors in October 1994. The Sage Mill Project included a pressure oxidation plant designed and constructed to process refractory carbonaceous ore using fine grinding/autoclaving technology developed specifically to treat Twin Creeks ore. The project was constructed in two phases. The first phase was put into operation on May 5, 1997, just hours before the transfer of ownership to Newmont Gold Company occurred. The second phase started in October 1997. This paper reviews schedule, costs, scope changes, and methodology used on the project that spanned almost five years from project definition through commercial operation.

Jan 1, 1999

By C. W. Overton

The operations of Bethlehem Copper are situated in the south-central interior of British Colombia at an elevation of 4900 feet above sea level. Main road and rail transportation systems pass through Ashcroft in the Thompson Valley, which is 28 miles by road from the minesite. The operation was the first low-grade open-pit porphyry copper mine in British Colombia. The minerals are chiefly chalcopyrite and bornite, while the rock is principally feldspar and quartz. In the outer fringes of the orebodies sane pyrite is present. Average grade of mill feed is 0.55% copper.

Jan 1, 1973

By T. Karlkvist, H. R. Kota, F. Andreas, B. I. Pålsson

"Separation of different calcium minerals have long been an interesting and challenging problem. In this investigation calcium mineral separation is examined by: microflotation, zeta potential measurement and adsorption, using novel collectors having two functional groups instead of one. In theory, by varying the distance between the functional groups, it could be possible to preferentially target one calcium mineral by matching the spatial distance between the sites on the mineral surface. In this investigation two new surfactants have been tested to estimate their ability to float apatite and/or calcite. Preliminary findings show that an increase in distance between the functional groups favors one mineral over the other, and this might be due to differences in the mineral surface structure. INTRODUCTION Apatite is a strategically important mineral which has both great value for industrial use as a precursor to phosphoric acid; and in the agricultural industry as an important source of phosphorous in fertilizers. This has led both the European Union and the United States to recognize it as an important resource for the future. Currently there is no lack of apatite in the world, but it is important to develop the beneficiation to ensure future supply. A common problem in apatite flotation is the selectivity towards calcite, which it is commonly associated with. Although calcite is an important industrial mineral its abundance makes it not usually worth to extract from apatite ores unless it is easy to separate1,2. Both apatite and calcite are semi soluble minerals with calcium as one of their constituents. The most common way to separate apatite and calcite is to use flotation. A process that involves making the mineral particles to extract from the system hydrophobic by adsorbing a collector on the mineral surface. One way to study collector adsorption on a mineral surface is by zeta potential measurements. The zeta potential is the charge at a slip plane a short distance from the surface. By measuring the zeta potential with and without the presence of collector it is possible to investigate if the collector is present at the surface or not, a change is indicative of collector adsorption. The zeta potential of fluorite, apatite and calcite without collector can be seen in Figure 1. The small difference in zeta potential between apatite and calcite shows the similarity in their surface properties and gives an indication of their separation difficulty. One additional problem with semi soluble minerals is their tendency to slightly dissolve in the pulp and thereby change the ionic composition of the solution. This makes separation and research problematic as the freed ions may readsorb on the mineral surface and interfere with the collector adsorption on the mineral surfaces3–5."

Jan 1, 2016

By John Greenhalgh, Benoit De Rivaz

"1.INTRODUCTIONThis paper is based on the Lee Tunnel project, which is part of the Thames Water’s Tideway Project.The client Thames Water has employed a Joint Venture of Morgan Sindall/Vinci Grand Projets and Bachy Soletanche to undertake the design and construction of the project under the management of CH2M Hill at a value in excess of £635 million ($990 million). The 3 main elements of the tunnel project are the permanent lining to the shafts, the precast segmental lining, and the secondary tunnel lining. All 3 are reinforced with different types of Dramix steel wire fibers and each element will be described in this paper. This paper will explain the basic structural design of FRC (Fiber reinforced concrete) based on the post cracking residual strength and will describe all the steps of this project, the testing program realized to support innovative design and the main technical learning point. 2.BASIC CONCEPT OF STRUCTURAL DESIGN OF FRCStructural design of FRC elements is based on the post-cracking residual strength provided by fiberreinforcement. Other cases, like early age crack-control or fire resistance, are considered non-structural use of FRC. For structural use, a minimum mechanical performance of FRC must be guaranteed. Fibers can be used to improve the behavior at SLS (Service Limit State) since they can reduce crack spacing and crack width, thereby improving durability and they can be used to improve the behavior at ULS (Ultimate Limit State) where they can partially or totally substitute conventional reinforcement in most conditions. In the design process, the definition of the performance expected from the material is a key factor and the mix-design of the material has to be optimized for the required structural performance.2.1 Testing Method In order to ascertain the structural requirements requested for the FRC segments, preliminary testing on samples will be required and the effectiveness of the proposed solution will also be assured by the testing of full scale specimens. Structural design of FRC elements is based on the post-cracking residual strength provided by fiber reinforcement. For structural use, a minimum mechanical performance of FRC must be guaranteed. Nominal values of the material properties can be determined by performing a 3-point bending test on a notched beam according to EN14651 (figure 1) or by performing the ASTM C1609 beam test:"

Jan 1, 2016

By G. Vogt

Water is one of the most important ressources of our planet. Unlike many other natural resources, water cannot be substituted by anything and must therefore be handled with the utmost care. Depending on the region and the possible shortage of water, the importance of water increases even further. Water consumption is not the only factor. In the construction industry, water pollution from auxiliary and operating materials and processes as well as other contaminants and their resulting load on wastewater play an important role. The sources for wastewater on tunneling construction sites are various: Washing water, seepage water accumulating in construction pits, tunnel water, water used in the slurry circuit in fluid-assisted tunneling methods or water from concrete work and stone cutting all these waters are contaminated with a range of pollutants like solids, hydrocarbons, heavy metals, etc. These contaminants can be removed or treated/reduced with the help of specifically designed wastewater treatment plants (WTPs). After the treatment the cleaned water can be either, in best case, reused on the construction site itself or discharged into water utilities like the available sewer or river pin respecting their discharge requirements. Due to dwindling water resources globally, the continuously rising discharge limits and the ever more important aspect of sustainability the use of WTPs on tunneling construction site will be indispensable. In this paper, it will be presented how these systems are designed and work, what advantages they offer environmentally as well as financially and what to look out for when planning and implementing such a system onto jobsite.

Jun 23, 2024

By Gary E. McIntosh

This paper will discuss a U.S. Bureau of Mines project designed to assess and predict the impacts which surface coal mining will have on the regional shallow groundwater systems in the Powder River Basin. The primary objective will be met through the accomplishment of the following: (1) The design and establishment of a regional network for monitoring of shallow groundwater systems in the Basin. (2) Monitoring of the direction and rate of flow, water quality, and aquifer characteristics of the shallow groundwater systems. (3) Development of a regional groundwater simulation model with appurtenant subroutines to determine local effects.

Jan 1, 1978

By D. R. East

Recent experiences within certain sectors of the international mining industry suggest an underestimation of the environmental risk associated with the design of mine waste management facilities. These experiences show that the technical and managerial challenge of responsible mine waste management is not always fully appreciated. Unfortunately, the image of the mining industry's environmental performance is negatively impacted by a relatively few number of failures. This negative view overrides the many positive contributions made by the majority of mining companies. The fact that these failures continue to occur to this day in both developed and developing countries is indeed remarkable, and indicates a degree of risk-taking approaching unacceptable levels. The design requirements for tailing storage facilities are, in many cases, more demanding than those of conventional water dams, because seepage of fluids which contain dissolved metals may pose a greater threat than the mere loss of water.

Jan 1, 1999

Sandvik built its first stone crusher in 1896 and has since grown to become a world leader in mining equipment. ?We are the best in the world, and we can now be even better at making our cone and jaw crushers in different models,? Olle Lundberg, production engineer at the Sandvik Mining factory in Svedala, Sweden told freelance journalist U. Samuelsson, of mekpoint.com. As a specialty manufacturing business under the umbrella of the Sandvik Group, Sandvik Mining is a leading global supplier of equipment, tools, services and technical solutions for the mining industry. Its expertise covers the areas of rock drilling, cutting and crushing, as well as loading, hauling and the handling of materials. Lundberg, along with five colleagues, will write CNC programs for the lathes and machining centers that manufacture Sandvik?s specially constructed casting. In 1999, Sandvik chose ESPRIT computer-aided-manufacturing (CAM) software by DP Technology to program its array of machine tools, and has worked with ESPRIT reseller Holotech, based in Örebro, since 2003.

Jan 1, 2014

By Nicholas C. Lias

Quartz crystals are the raw material from which are made the crystal units utilized in filters and oscillators so vital to the performance of all long distance communications systems. These devices act as the heart of equipment that permits a single telephone cable to carry hundreds of conversations simultaneously. Quartz crystals are of value in communications because of this piezoelectric nature, that is when an electric signal is applied to the quartz, there is a resulting mechanical motion and conversely, a mechanical stress results in an electrical output signal. A plate cut from a quartz crystal will oscillate at some specific frequency, which is determined by the physical dimension of the plate. During the early stages of telephony, all quartz plates were cut from natural quartz, which was imported mainly from Brazil. Since the source of this important raw material was based upon a foreign supply which is located at a great distance from the user and could be vulnerable in time of a national emergent, it became necessary to maintain a large inventory of this strategic material. Also due to the considerable cost of natural crystals of a size and quality suitable for Bell System use, an investigation was made by Bell Laboratories into the possibility of developing a substitute material. The effort was successful and led to a joint development program between Bell Laboratories and Western Electric. This program brought about the design of manufacturing facilities capable of producing large quantities of cultured quartz at Western's Merrimack Valley Works, No. Andover, Massachusetts.

Jan 1, 1973

By W. M. Kidd

INTRODUCTION Uranium mine inspection in Canada forms one element of the enforcement of the Atomic Energy Control Act; it is under this Act that all Canadian uranium mines and mills are licensed to operate. Inspection duties are carried out by a small core staff of federal government inspectors (working for the Atomic Energy Control Board (AECB)) largely supplemented by provincial mine inspectors working on behalf of the AECB. Unlike most resource extraction in Canada, uranium mining is under federal jurisdiction and consequently it was the AECB who decided in 1975 that changes in the Canadian uranium mining industry, particularly its expansion and the expanding role of the mine inspector in the limiting of exposures, warranted the offering of a special radiation protection training course. The Uranium Mine Inspector Training Course (UMITC) was first conducted in 1976 at the Elliot Lake Centre in Elliot Lake, Ontario. Subscription for the course was not limited to mine inspectors to enable union stewards, management personnel and provincial/federal labour inspectors to attend. This paper will present an outline of the course content, the format of its presentation and non-curriculum aspects of running a course of this type in uranium-producing community. The core lecturers for UMITC are drawn from the Radiation Protection and Uranium Mine Divisions of the AECB. In addition, guest lecturers are invited from universities and medical research centres together with industry professionals and government researchers. In all some twenty-four plus presentations are made over the first five days of lectures. The program topic areas, hazards, controls, measurements, record-keeping and health effects are preceded by an intensive half-day session on radiation fundamentals. TOPICS Hazards [Dust] A review of the dynamics of airborne particles including the effects of particle size, gravity and wake-turbulence on the behaviour of dust clouds. Associated topics are migrational aspects of dust particles and specific dust-generating mine operations. [Radiation] Canadian uranium mines are increasingly diverse in nature ranging from large scale low-grade underground operations in Elliot Lake to smaller high-grade open pits in Saskatchewan. Papers are presented on assessments of internal and external exposure, the metabolic pathways of ingested or inhaled radiation and the specifics of mine and mill hazards. Radiation hazards are further broken down into gamma surveys of uranium mines, radon daughter concentrations and problem areas. Controls The relationship between mining methods and the operating environment is critically important to ensuring safe working conditions. This refers to both the selection of machinery/devices, etc., and to engineering controls which are instituted to remedy problems created by new technology. UMITC examines a number of possible mining techniques, their criteria for selection and impact on the working environment. Control measures, ventilation practices and design, the need for continuous water misting and special open-pit precautions are presented. These lectures frequently conclude with suggestions for better operating guidelines for mine ventilation systems and the need for greater co-operation between the ventilation department and the underground crews. Measurements Uranium mining regulations stress the need for a high standard of exposure monitoring, statistical planning and record-keeping. [Statistics] Although many course participants are well versed in statistics, certain fundamentals are repeated and include, the concepts of mean, variance, standard deviation and standard deviation of the mean. Confidence levels, decision-making based on sample statistics and statistical records are also discussed. [Dust Measurement] Dust measurement is particularly critical in the mines where the high silica content of the ore body, such as those at Elliot Lake, results in the continuous generation of dust. Sampling practices, filtration, impaction, thermal impaction and electrostatic precipitation are explained together with the methods of counting samples to determine free silica. Konimetric and gravimetric techniques for dust sampling are compared and contrasted. [Radiation Measurements] Both collective and personal dosimetry systems are used in the Canadian uranium mining industry and lectures are presented on each. Techniques and possible sources of error are discussed for a variety of radon and radon daughter measurement methods - Lucas method, Tsivoglou and modified Tsivoglou, Kusnetz, Rolle. Instant working level meters and personal alpha dosimeters are explained in terms of calibration, maintenance, readout and estimation of accuracy. A lecture outlining dose estimation by means of bio-assay, whole-body counting and the use of TLD's concludes the topic. Record-Keeping An overview of the problems of changing limits,

Jan 1, 1981

By Gregory P. White

A number of private companies and universities have developed computer programs which can be used to simulate surface coal mining by dragline. In this paper, we briefly discuss the concept of computer simulation, compare these computer programs with each other, describe the major changes required to convert these programs to an IBM computer system, and analyze their sensitivity to inaccurate input data. We also present a summary of the required data input for each program, core storage requirements, and output results. Sources for obtaining these programs and their documentation are listed at the end of the paper.

Jan 1, 1983

By R. L. Nielsen

The thematic mapper (TM) aboard Landsat II records image data at seven wavelength intervals or bands. Three record the visible region; three record reflected IR energy. A false color image combining bands 7, 4 and 2 rendered as red, green and blue respectively provides maximum discrimination of rock types in arid regions. Structural analyses and interpretation defines regional structures, large volcano-tectonic features intrusive complexes, all which localize mineralization. Special digital processing using the ratio: Band 3 / Band 1 can identify limonites and other iron minerals. The ratio: Band 5/ Band 7 identifies clays and alunite. These ratio images show features and patterns of hydrothermal mineral systems: ?patterns of sulfide and alteration zoning in large porphyry systems, and zones of strong silica, quartz-alunite-illite, and pyrite-sericite in epithermal centers. Thus, digitally processed Landsat TM images are a cost effective and rapid means to recognize altered areas and define targets for large mineralized systems.

Jan 1, 1995

"A cationic surfactant, tetradecyl tributyl phosphonium chloride (TTPC), was first used as a collector. Flotation characteristics of muscovite using TTPC have been investigated through flotation tests. And dodecyl trimethyl ammonium chloride (DTAC) was tested for comparison. Their adsorption mechanisms on muscovite surface were clarified using zeta potential measurement, DFT calculation and molecular dynamics (MD). The flotation results indicate that the recovery of muscovite decreases when the pH increases in the presence of surfactants. When a maximum of recovery was reached, the dosage of TTPC was 2×10-5mol/L which was half of that of DTAC. Zeta potential measurements confirm that the TTPC displays a stronger collecting power than DTAC and is a superior collector for the muscovite flotation. DFT calculation and MD simulations show that TTPC interacts with the muscovite mainly through electrostatic attraction and hydrogen-bonding. The conclusions drawn from purely theoretical computations matched remarkably well with the experimental results. Keywords: Quaternary phosphonium salts; Flotation collectors; Flotation INTRODUCTION Muscovite mica is widespread in igneous, sedimentary and metamorphic rocks. It has the general composition KAl2(AlSi3O10)(OH)2. Muscovite mica exhibits perfect cleavage along the (001) plane, which exposes interlayer potassium ions[1-3]. In aqueous suspensions, the potassium ions readily enter into solution, leading to the development of a net negative charge on the (001) plane[4-6]. The surface of the muscovite mica is negatively charged at all pH > 1[7]. Due to the negative charge surface over the whole pH range of 2–12, the muscovite mica would not be expected to respond to anionic collectors in the absence of an activator. Conversely, the mineral is readily recovered using cationic collectors. However, until now, various amines and their derivatives (with N atoms as the center) are still the only available cationic collectors which still had their shortcomings such as weak selectivity, low flotation speed. Since few types of cationic collectors could be used, in some sense, the limitations of collectors are increasing significantly and the cationic flotation is facing more and more challenges. Quaternary phosphonium salts, as novel cationic surfactants, are widely used in antimicrobial, catalysis and surface modification field due to their biological activities, hydrogen bonding capability, stability and superior group electrical property[8-10]. There are a number of processes where quaternary phosphonium salt surfactants have shown better properties than quaternary ammonium salts and amines. Although the adsorption of quaternary phosphonium salt surfactants at the bacterium–liquid interface has been studied thoroughly, the case of adsorption in mineral surface has not been investigated thus far."

Jan 1, 2016

By V. B. Achanti

Reliability of the compressive strength of a coal seam determined in the laboratory is often subjected to debate. Effects of the coal seam's inherent characteristics, specimen preparation, testing procedure, testing condition, and a number of tests often result in drastic variation of the strength data. This paper deals with the development of a testing procedure for determination of coal seam compressive strength in the laboratory. Coal samples from two different coal seams were tested. First, the inherent characteristics of each coal seam such as coal structure, Hardgrove Orindability Index (HOI), Slake Durability Index, proximate analysis, and mechanical properties namely Young's modulus and Poisson's ratio were determined to categorize them in terms of their characteristic severity liable to produce variable strength data in typical laboratory tests. Second, two commonly used laboratory specimen shapes namely; cylindrical and cubical, were tested to determine which shape produced the least variation of data and reproducible strength values. Third, four loading rates within the static testing range (Le. 0.007 MPa/s (1.0 psi/sec), 0.07 MPa/s (10 psi/sec), 0.34 MPa/s (50 psi/sec), and 0.7 MPa/s (100 psi/sec)) were used to determine an ideal loading rate. Finally, the number of test samples required to produce strength data within the acceptable standard deviation, considering coal seam characteristics were established.

Jan 1, 1996

By H. J. Sohn

Systematic studies were carried out on the adsorption of the silver thiourea complex on activated carbon. The experimental isotherm data fit the Freundlich isotherm equation. The adsorption rates increased with increasing temperature and decreased slightly with the increase of free thiourea concentration. The concentration of sulfuric acid had little effect on the adsorption rate. Adsorption kinetics correlated well with the Elovich equation, indicating adsorption is the rate-determining step.

Jan 1, 1987

By D. E. Walsh

The behaviour of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effect of particle size, particle shape, pulp density, feed rate, and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that provided suitable precautions are taken, the technique is capable of providing valuable information that cannot be obtained by conventional studies, and could be used to better optimize spiral performance.

Jan 1, 1992

By Jae-Chun Lee, Sadia Ilyas

"The present study was carried out to develop an economically feasible and environmentally friendly technique to extract metals such as Al, Fe, Cu, Zn and Ni from electronic scrap by employing Penicillium chrysogenum strain KBS3. Studies were carried out in various leaching modes, including one-step leaching with combined growth and leaching phases (Mode 1), two-step leaching with alternative growth and leaching phases (Mode 2), spent medium leaching with separated growth and leaching phases (Mode 3), leaching with fresh growth medium without fungal culture (Mode 4), leaching with deionized water (Mode 5) and leaching with commercial organic acids (Mode 6). The main lixiviants produced in leaching Mode 1 were citric, tartaric, oxalic and gluconic acids in concentrations of 12, 2.5, 1.8 and 152 mM, whereas in leaching Mode 2, the concentrations were 15, 0.5, 1.0 and 1,162 mM, respectively. In leaching Mode 3, 63 mM citric acid, 23 mM tartaric acid and 29 mM oxalic acid was observed. At 5% pulp density, both leaching Modes 1 and 2 showed similar metal extraction yields from the electronic scrap at 35º C. Approximately 96% Al, 98% Zn, 48% Cu, 25% Fe, 66% Pb and 73% Ni were extracted in leaching Mode 1 in 14 days. In leaching Mode 3, 85% Al, 81% Zn, 97% Cu, 22% Fe, 50% Pb and 63% Ni were extracted in 14 days. The extraction yield of Cu was much lower in leaching Modes 1 and 2 (48- 50%) than in leaching Mode 3 (97%), as well as in leaching Mode 6 (98%) with organic acids, including citric, tartaric, oxalic and gluconic acids.IntroductionTechnical innovations in electrical and electronic equipment with new functionalities and designs stimulate consumer purchasing and lead a rapid increase in the production of waste materials. Terazono et al. (2006) have reviewed the data on electronic waste generation in different parts of the world. Studies by Bertram et al. (2002) have also affirmed that waste electrical and electronic components are the fastest growing waste category, which emphasizes the need for efficient recycling strategies. The recycling of electronic waste is an important subject, not only from the perspective of waste treatment, but also from the perspective of the recovery of valuable materials. However, the recycling of electronic scrap is still limited, due to the heterogeneity of the materials present in the products (Veit et al., 2005).Bioleaching-based processes offer a number of advantages over conventional pyro or hydrometallurgical methods (Lee et al. 2007; Lee and Pandey, 2012). These advantages include simple, inexpensive (in some cases) and ecofriendly approaches and the generation of less active leach residue relative to other metallurgical processes. Although biohydrometallurgical processes have been successfully applied to the leaching of metals from ores (Olson et al., 2003; Rawlings, 2002), data pertaining to the application of these processes for the extraction of electronic scrap are still scarce. Recently, a few studies have been undertaken for the extraction of metals from electronic scrap/ printed circuit boards (Brandl et al., 2001; Faramarzi et al., 2004; Ilyas et al., 2007; Ilyas et al., 2010). These studies were conducted with mesophilic chemolithotrophic bacteria (Acidithiobacillus ferooxidans and Acidithiobacillus thiooxidans), cyanogenic bacteria (Chromobacterium violaceum) or moderate thermophilic bacteria (Sulfobacillus thermosulfidooxidans). However, compared to bacterial leaching, fungal leaching has several advantages, including (i) the ability to grow at a higher pH, thus making it more suitable for the bioleaching of alkaline solid waste; (ii) a generally faster leaching process with a shorter lag phase and (iii) the chelation of excreted metabolites (e.g., organic acids) with metal ions, thus reducing toxicity to the biomass (Burgstaller and Schinner, 1993; Aung and Ting, 2005)."

Jan 1, 2015