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By Norman A. M Macleod

FOR the past seven years, all flotation at the Britannia mill has been done in Forrester Air-Lift cells. Prior to 1931, the roughing and part of the cleaning operation had been performed in four 21-cell and two 14-cell M.S. machines. The resulting economies in reagent, power, maintenance, and general operating costs, and the increased recovery, more than justified the exclusive use of the Forrester machine. About three years ago, the possibility of still further improving the efficiency of the flotation section was the subject of considerable discussion and experiment. Arising from these experiments, tests were made of the practicability of using a cell of greater depth than that of any pneumatic or mechanically-agitated machine in common use. Cells were constructed with depths of 7 .5 feet, 10 feet, and 15 feet, and, in all cases, a very definite improvement in operation was indicated. The cell now being used in the mill treats from 5,500 to 6,200 tons of dry feed per day. It is 100 ft. long by 5 ft. wide by 8 ft. deep, and has replaced a total length of over 500 feet of standard Forrester machine. The choice of a depth of 8 feet was governed by the type of blower which was available-in this case, a Roots-Connersville blower, driven by a synchronous motor and delivering 6,000 c.f.m. of free air at 4.0 pounds per square inch. At the Chelan Division of the Howe Sound Company, where a new mill was recently built, all flotation is carried on in cells 10 feet deep, with good results.

Jan 1, 1938

By D. Virely, M. Gasc-Barbier, J. Guittard

"The valleys of the Dordogne and the Vézère (France) have been inhabited since prehistoric times, as evidenced by the famous site of Lascaux. A few miles away, the village of La Roque-Gageac is also a very popular tourist destination (about 1.5 million tourists per year): The village is sandwiched between a massive limestone cliff and the Dordogne river. The collapse of a cave roof high above the village in January 2010 led us to characterize instability together for the cave and the whole cliff and propose a adapted instrumentation to monitor the fracture openings in the rock mass that are linked to climatic variations. Measurements have been going on and been recorded for nearly 4 years. They point out the role of thermal stress fatigue in the breakdown of the rock mass. In this paper we describe the site under study, the instrumentation and its main results. INTRODUCTIONThe phenomenon of thermal fatigue has been very little studied as far as rocks are concerned, whereas it is rather well characterized for other types of materials: Elsevier published a journal dedicated to fatigue (International Journal of fatigue). In the case of rocks, thermal phenomena and their impacts on mechanical behavior have been analyzed from a micro-structural point of view, and it is now well-known that an increase in temperature causes a dilatation of crystals (Arnould et al., 2004; Berest & Weber, 1998). This dilatation may lead to the development of inter-granular traction and compression stresses, and if those stresses are greater than fracture strength, inter-granular and intra-granular cracks may take place. On the other hand, the fatigue phenomenon (cyclic repetition of a temperature variation which is less extreme than the one that may lead to this inter-granular or intra-granular fracture) is a phenomenon which has not been much studied.The principal studies on thermal fatigue on rocks come mainly from the field of geomorphology, particularly in connection with the analysis of the evolutions of past climate that can explain the present shapes of those landforms: those studies remained essentially qualitative and not quantitative. Le Ber & Oter Duthoit (1987) proposed a thermal and thermodynamic approach to analyse the disaggregation of rock masses. This analysis is dedicated to the study of paleoclimates and was implemented to better understand the formation of slope deposits in order to propose transfer models permitting the reconstruction of the climactic conditions contemporary to their appearance. Since deterioration in the cliff only appears after several cycles, it means that it is a gradual and irreversible deterioration which leads to an increase of the « disorder ». Seen from a macroscopic system point of view, this irreversible evolution is quantified by the internal creation of entropy."

Jan 1, 2015

By Ju-hyung Ha

New automated curing system for mass concrete has been developed to improve the quality of concrete structure and to save construction time and cost. The principle of this system is the automated water circulation system of heated curing water. Applied curing water on the surface of mass concrete keeps the temperature difference between center and surface of the structure below the threshold of specification. Mock-up test and field application have been conducted to investigate the performance of this system. In the results, new automated curing system reduced the chance of thermal crack occurrence and improved quality of the concrete structure as well.

Aug 1, 2013

"Successive seismic waves may cause progressive weakening of a fault zone, which has been recognized as the mechanism of earthquake aftershocks. However, it is unclear that how a fault zone slips under each wave cycle and how slip displacement accumulates under continuous wave cycles. This laboratory study provides direct evidences on the slip process of a simulated granular fault zone dynamically induced by an incident wave without the effects of late-arriving and reflected waves. The experimental observations show forward and backward slip paths of the fault zone and partially recovered slip displacement after a wave incidence. The unrecovered slip displacement after each wave cycle can be accumulated until it reaches a critical slip distance for seismic faulting, which may reinterpret delayed triggering in earthquake dynamics. The limited interseismic period restricts fault self-healing in strength. The experimental results also indicate that the dynamically induced frictional slip on the fault zone is associated with a complex frictional system, including seismic wave radiation, frictional slip initiation and normal stress vibration. Different from the dynamically induced frictional slip on the fault zone, the statically induced frictional slip causes a permanent increase of slip displacement along the shear loading direction. INTRODUCTIONAn earthquake mainshock may induce aftershocks by suddenly changing external stresses applied to another fault zone in the near field (Kilb et al., 2000) and by slightly perturbing a fault zone from a critical steady state to stick-slip faulting in the far field (Gomberg and Davis, 1996). The dynamically induced frictional slip on a fault zone has been recognized as the mechanism of earthquake aftershocks (Marsan and Lengliné, 2008; van der Elst and Brodsky, 2010). Although earthquake aftershocks have been extensively studied by many seismological methods, a simplified laboratory fault zone can provide possible interpretation on real faulting and detailed analysis on a friction process (Dieterich, 1979; Nielsen at al., 2010). According to a few laboratory experiments related to the dynamically induced frictional slip on a simulated fault zone (e.g., Uenishi et al., 1999; Johnson et al., 2012), the slip process induced by successive seismic waves exhibits continuous motions. However, it is unclear that fault slip response under each wave cycle and slip displacement accumulation under continuous wave cycles."

Jan 1, 2015

By R W. Drybrough

The program to increase production at Sherritt Gordon's Lynn Lake property, which began in 1956, included increasing the rope speed and the horsepower of the ore hoist at the "A" shaft. Because of the limited power sup-ply from the two 7,000-hp. hydroelectric plants, and the ? 3,600 hp. predicted for the combined hoisting requirements of the three production shafts, it was considered desirable to lessen the impact of this type of load on the relatively small power system by equipping all future hoisting arrangements with Ward Leonard direct-current drives. The manually operated 8-by 4-ft. hoist at the "A" shaft had a rope speed of 1000 f.p.m., and was driven by a 385-hp., 380-r.p.m. wound rotor motor with liquid rheostat control. This A.C. drive was replaced by a semi-automatic Ward Leonard direct-current drive with a 515-hp., 566-r.p.m., shunt wound motor, providing a rope speed of 1,500 f.p.m. During several months preceding the con-version, all possible preparations were carried out to keep the changeover period to a minimum, and this resulted in a total shutdown time of twelve days. The capability of the "A" Shaft hoist was increased from 109 tons per hour to 134 tons per hour, and both mechanical and electrical maintenance were reduced considerably. The total cost of the conversion amounted to $130,000. The hoistmen who had been required for the manual A.C. drive were transferred to the new Farley shaft, and the reduction in operating labour costs of the "A" Shaft hoist

Jan 1, 1965

By Zhenyu Han, Dion Weatherley, Ruslan Puscasu

"This study aims to demonstrate the capacity of the Discrete Element Method (DEM) to model and simulate fracture in brittle rock, capture the crack propagation process and determine crack propagation rates for various levels of external loading. In the numerical experiments reported here, a macroscopically homogeneous body of brittle rock, containing a single pre-existing crack, was subjected to tensile stress loading. Simulations concerned with model I crack growth process in 3D were carried out. The process of fracture has been observed under various steady state and dynamic conditions. The numerical results obtained reproduce qualitatively and quantitatively a variety of observed fracture phenomena. Specifically, this study examined the onset of cracks, single dominant cracks that grow across the specimen, crack bifurcations and branching. The density of fractures that can be nucleated and grow to a significant size with and without arresting each other, crack growth speed and stress distribution, all have been consistently and systematically analyzed. Suggestions on potential future developments are made and discussed.INTRODUCTIONFracture and failure mechanics are very important in mining, manufacturing, materials processing, mineral processing, civil and mechanical engineering, and many other disciplines of science and engineering. Yet, due to the complexity of fracture phenomena, no theoretical models of broad applicability are currently available (Bieniawski 1967). The simulation of crack propagation is therefore considered an open question in numerical rock mechanics. Although, a significant body of experimental research on fracture of materials was carried out since the early days of fracture mechanics (circa 1940s) (Poncelet 1946, Mott 1948), often in parallel with the development of fracture mechanics theories as well as with the development of experimental and observational techniques themselves, the experimental results were often done on particular classes of material such as glasses and other very brittle materials. Indeed, a number of specific experimental observations on the behavior of growing cracks in brittle materials were made in the 1940s for which generally accepted explanations based on physical principles are still lacking. Likewise, quantitative numerical modeling, based on both continuum and discrete methods, as a basis for understanding dynamic crack growth is still in a preliminary stage."

Jan 1, 2015

By K. J. Aglias, M. Jeffery, J. V. Simmons, J. A. Johnston, S. G. Fityus

"Shales and mudrocks undergo weathering in the near-surface geological environment, and degradation when directly exposed at the surface. Despite having superficially similar appearances, many shales have very different degradation behaviours. For example, some shales break down readily upon exposure whilst others remain more or less intact. Further, for those shales which break down, the style of degradation can vary greatly. A phenomenon is described where fresh shale blocks that are exposed at the surface undergo rapid breakdown to a fragmented texture which then persists for relatively long times, without further breakdown to finer soil particles. This is illustrated for some coal mine waste rocks. Furthermore, this metastable fragmented texture seems to be particular to each particular type of shale. The paper presents a conceptual model for this physical breakdown of shales which accounts for the differences in fragmental texture that are observed. The importance of several factors including strength, permeability and expansive clay content are identified for their contribution to the degradation behaviour of different shales.INTRODUCTIONShales and MudrocksThe term shale is applied widely to a class of mudrocks having a range of distinctive but gradational appearances and mechanical behaviours. Mudrocks are sedimentary rocks primarily composed of silt and clay sized particles (Tucker 1982). Mudrocks form in low to very low energy environments such as flood plains, lakes and deltaic environments, where the finest detrital particles are able to settle out of suspension (Reeves et al., 2006; Stow, 2005; Tucker, 2001).Unlike coarser siliciclastic sedimentary rocks, mudrocks do not present with a wide variety of sedimentary structures and textures. The most common texture is a preferred orientation of clays and micas parallel to the bedding plane. This textural component is related to the property of fissility or the ability for such textured mudrocks to split along smooth planes that are parallel to the bedding. Another common structure is lamination, formed by variations of grain sizes and types during deposition, Massive texture describes the situation where no sedimentary structures or textures are apparent (Boggs Jr., 2009; Tucker, 2001). The term shale varies between sources and contexts, with Reeves et al. (2006) stating that a shale is a fissile mudrock, where “fissility is a property that has developed at a certain stage of weathering”."

Jan 1, 2015

By Julian V. Simela

Conventional methods of underground surveying use theodolites/total stations and 3D laser scanners to obtain information about the underground environment. Current methods of geo-referencing these instruments to a mine reference system include triangulation, trilateration and resection. However, despite technological advancements, surveying procedures have remained slow, laborious and relatively unchanged during the last half-century. Recent innovations in the robotics community have shown that automated mapping of underground mining tunnels can be undertaken using 2D/3D laser scanners. These techniques have the potential to, in turn, improve upon current underground surveying and mapping methods. Automating surveying and mapping using current surveying tools without changing the setting up procedures or removing current constraints, or even changing the type of equipment used, does not change the status quo. The problem of moving from a static, tripod based surveying and mapping system to an unconstrained mobile surveying and mapping system is the subject of this paper. A current challenge for automated mapping is the ability to automatically geo-reference a mobile mapping system to a mine reference system. For a mobile mapping system that uses a horizontally mounted 2D laser scanner to gather data of the underground environment, the challenge of determining its position and orientation within the mine environment is magnified even more. This paper introduces Mobile Automated Scanner Triangulateration (MAST), a technique under development at Queen?s that is designed to geo-reference a mobile mapping system to a mine reference system for the purposes of underground mine surveying. MAST quickly and automatically determines scanner 2D position and orientation (azimuth) in a mine reference frame by using minimal human input.

Aug 1, 2013

By H. Salamanca

HighService has developed different equipment using wireless technology and machine vision systems that were specially designed to allow 1) the online determination of the SAG mills liner's service life, 2) the automatic detection of a missing dipper tooth in mineral extraction shovels, 3) the reduction of accident risk potential in the mineral transportation within the mine, and 4) the reduction of collision risk potential between shovels and wheel dozers during mineral extraction. For the development of all these systems at HighService, extensive research has been done in radio frequency and image processing fields. The integration of both technologies with the expert knowledge of the company on the typical harsh environment conditions of the mining industry has led to the development of heavy duty equipment that tolerate the extreme mechanical requirements of SAG mills and electrical mining shovels.

Jan 1, 2007

By Geoffrey Gilbert

Rossland is in the West Kootenay district; 5 miles north of the International boundary and 4 miles west of Columbia River at Trail. The first claim in the district was located in 1887; but there was little activity until 1890; when the showings that later became important were staked and development began. Production increased rapidly from 1; 800 tons in 1894 to a peak of 360; 000 tons in 1903; and averaged 286; 000 tons for the next 13 years. It declined sharply in 1917; and continued to decline until the closing of the main mines in 1928. Between 1933 and 1941 leasers mined a further 137; 000 tons. Total output has been about 6; 200; 000 tons; with average recovery of 0.47 oz. gold; 0.6 oz. silver; and 1 per cent copper. The total value was $82; 500; 000; of which aboµt three-quarters was in gold; the camp still leads the province in total gold produced. Ninety-eight per cent of the tonnage came from a small compact area worked by four inter-connected mines : the Le Roi (39 per cent); Centre Star (25 per cent); War Eagle (24 per cent); and Josie (10 per cent); all now owned by the Consolidated Mining and Smdting Company of Canada; Limited.

Jan 1, 1954

By C. Edwards

"The processes for rare earth (RE) extraction include the decomposition of RE ore concentrate minerals, and the concurrent or subsequent leaching of the rare earth elements (REEs) from the decomposed minerals. Ore beneficiation concentrate can be decomposed by, for example, acid roasting, caustic cracking, and chlorination. The REEs can be selectively extracted. The nature of the REE extraction process depends on the concentrate mineralogy and the targeted products. Based on the experience of the Saskatchewan Research Council (SRC) in RE processing, this paper reviews REE extraction from the major RE minerals, including bastnaesite, monazite, xenotime, ion-adsorption clay, allanite, cerite, and eudialyte. An update on the development of RE extraction processes is also provided.INTRODUCTIONRE processing usually involves two operation stages, physical processing and chemical processing. Physical processing, also known as ore beneficiation, separates the RE minerals from gangue minerals to produce an RE mineral concentrate. Chemical processing, which includes extraction and separation processes, converts the RE mineral concentrate to an RE compound which is either an end product or an intermediate product for the subsequent production of individual REEs or other compounds. The RE extraction process uses one or more reagents to decompose the RE minerals and to leach the REEs into solution. The RE separation process uses solvent extraction, ion-exchange, or chemical precipitation to produce either rare earth oxides (REOs) or individual REEs. The authors have previously reviewed RE ore beneficiation processes (Zhang & Edwards, 2012). This paper focuses on extraction processes for a variety of RE minerals. Table 1 gives the chemical compositions of the RE minerals mentioned in this paper. The varieties of RE extraction methods use many different reagents. These reagents are mainly inorganic acids, alkalis, salts, and chlorine gas. The commonly used acids include sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). Sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) are the most common alkalis. Salts include ammonium sulphate ((NH4)2SO4), ammonium chloride (NH4Cl), and sodium chloride (NaCl). HCl is normally used to extract RE from silicate ore minerals such as allanite and gadolinite. The alkalis and H2SO4 are mainly used to leach REs from phosphate ores minerals like monazite and xenotime. The carbonate ore RE minerals such as bastnaesite can be treated using either acids or alkalis. HNO3 is mainly used to leach eudialyte and apatite. The extraction of REs from ionadsorption clay deposits uses salt solutions. Chlorine gas (Cl2) is exclusively used in the RE chlorination process which can be used to treat any RE minerals."

Jan 1, 2012

By S. K. Sharma, Sanket Bacchuwar, Prabal Kumar Agrwal, G. V. Rao

"Iron ore processing industries play a vital role in the Indian economy. At present Iron ore of around +64% Fe is used for production of Iron through blast furnace. To produce +64% Fe from low/medium grade ores, crushing & beneficiation is compulsory. But during these processes, large amount of slime is generated. It is estimated that 18% -25% of tailing is generated during the processing of iron ore. The iron ore slime is discarded because of its particle size and chemical composition not being suitable as feed to the blast furnace. Although the fines/slimes can be agglomerated to larger particle, the alumina to silica ratio which is normally more than one pose serious problem during sintering process and subsequent smelting in blast furnace. The alumina content in the slime needs to be reduced for it to be used as the feed for blast furnace. The sample assayed 61.40% Fe, 7.68% SiO2, and 1.52% Al2O3, LOI 2.63% and all other elements were found in critical limit. A series of 27 tests were conducted by using a spiral for optimisation of process parameters to produce a pellet grade concentrate from the stacked slimes obtained from Kirandul. This paper deals with the optimisation studies of various parameters of a spiral concentrator and helps to utilize the fines from tailing ponds.INTRODUCTIONReserves of high-grade iron ores are diminishing all over the world at an alarming rate. As a result, alternative ways of augmenting and conserving precious and non - renewable natural resources are being seriously considered. One such attractive option is the recovery of metal values from slimes / tailings. Iron ore tailings containing around 48 - 60% Fe are generated from the iron ore washing plants and are disposed into tailing ponds without any further utility. These tailings in the form of slimes are not suitable in iron and steel making due to the presence of higher amount of gangue constituents. Several beneficiation techniques have been tried from time to time to reduce the gangue so that the beneficiated products could be effectively used."

Jan 1, 2016

By A. Trusiak

"Increasing energy costs in mineral processing is making it necessary for tighter controls over various parts of the concentrating process. Continuous monitoring and control of critical process streams can be easily performed by today's many computer systems. Indeed, the list of successful applications of computers to grinding and flotation control continues to grow. The day is rapidly approaching when the use of computers within concentrators for either process control or simply metallurgical accounting will no longer be a luxury, but a necessity. The benefits from such applications far out weight the initial investment.This paper describes the current application of a process control system at Brunswick Mining in north-eastern New Brunswick. Emphasis is placed on the control of a CuPb flotation circuit, and the benefits derived-from this control.No. 12 Cu-Pb Flotation: The complex nature of the Brunswick flotation process has been described else-where. 1,2,3 Four final concentrates are eventually produced, these being a Zn concentrate assaying 53% Zn, a 30% Pb concentrate, a 20% Cu concentrate, and a bulk Pb Zn concentrate assaying 35% Zn and 17% Pb. The Cu concentate, Pb concentrate, and bulk Pb Zn concentrate are all derived from a primary CuPb concentrate assaying 26% Pb, 11% Zn and 1.8% Cu.The No. 12 CuPb circuit produces approximately two thirds of the total primary CuPb concentrate. No. 12 ore, assaying 3.5% Pb, 9% Zn, 0.25% Cu and 100 g/tne silver, is ground in two parallel grinding circuits. Each line uses a 3.2 x 4.2 meter rod mill in closed circuit with two parallel 3.2 x 3.9 meter ball mills. Ball mill and rod mill discharges are classified in two stages of cycloning. The secondary cyclone overflow, or flotation feed, is controlled at 65% passing 37 microns."

Jan 1, 1981

By Z. Zhang, M. -Y. Liu, X. -G. Chen, F. Breton

"The microstructures of AlSi10Mg foundry alloy in permanent mould (PM) and high pressure vacuum die (HPVD) castings were analyzed and compared. The as-cast microstructures of two castings mainly consisted of eutectic silicon particles, primary Mg2Si and Fe-rich intermetallic phases. The surface layer in HPVD castings, which has a unique feature and different structures, was carefully characterized. The dimension variation of microstructural phases along the cross section in PM samples is less than that in HPVD samples, although the size of microstructural phases in PM samples was much larger than that in HPVD samples. The mechanical properties of PM and HPVD samples were evaluated on as-cast and T6-treated conditions. The tensile properties of HPVD castings are remarkable better than those of PM castings on the as-cast condition. The T6 heat treatment greatly improves the tensile strength of PM castings while it has limited impact on the tensile strength of HPVD castings.INTRODUCTION The AlSi10Mg alloys are widely applied to the high pressure die casting (HPD) and high pressure vacuum die casting (HPVD). In the HPD process, the melt is injected into the die cavity under a high speed (30–50 m/s in the gate velocity for aluminum alloys), and solidified under a high pressure (up to 200 MPa in the cavity) and with a high cooling rate (up to ~103 Ks–1) (Gourlay, Laukli & Dahle, 2007; Ji, Wang, Watson & Fan, 2013). This results in a unique microstructure feature that is different to other casting processes under gravity. One major concern in HPD castings is porosity due to trapped air in the cavity (Ji et al., 2013), which seriously restricts the application of a heat treatment on the improvement of mechanical prosperities because of the formation of blisters on casting surfaces. For the process improvement, the high pressure vacuum die casting was developed in 1980s (Uchida, 2009). In this process, the melt is injected into the die cavity under reduced pressure (vacuum), which greatly reduces gas porosity in castings due to effectively avoiding the trapped air. Consequently, HPVD castings are heat-treatable without the formation of blisters on castings surface during heat treatment. The HPVD process has been widely applied to produce high quality structural castings in recent years attributed to reliable vacuum system development (Uchida, 2009). However, the microstructure features of HPVD castings are not systemically characterized yet."

Jan 1, 2018

By R. Chen, K. Xia

In deep mining activities, blasting induced compressive stress wave would be reflected as tensile wave at a free surface around the openings, which would facilitate the tensile failure of the deep rock since it is much weaker in tension than in compression. It is thus critical to understand the dynamic tensile failure of rocks subjected to static tension for deep rock engineering applications. A modified split Hopkinson pressure bar (SHPB) system is adopted to load Brazilian disc (BD) samples statically, and then exert dynamic load to the sample through stress wave generated by impact. The pulse shaper technique is used to generate a slowly rising stress wave and thus to facilitate the stress equilibrium of samples during each test. Five groups of Laurentian granite (with tensile strength of 12.8 MPa) BD samples under the pretension stress of 0 MPa, 2 MPa, 4 MPa, 8 MPa, and 10 MPa are tested under different loading rates. The result shows that the dynamic tensile strength of the rock decreases with the increase of pre-tension stress, which is easy to understand because pre-tension stress weakens the rock sample. It is also observed that under the same pre-tension stress, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency that is common for engineering materials. Furthermore, it is found that the loading rate sensitivity of the rock increases with the increase of pre-tension stress. A qualitative explanation for this phenomenon is that more microcracks are generated and activated under higher pretension stress, resulting in a more viscous material. Based on the results, an empirical equation is proposed to fit the data and explain the dynamic tensile behaviour of rock under pre-tension stress. A physical model is used to simulate the dependency of the dynamic tensile strength of rock on the pre-tension stress and the loading rate, which is shown to be in good agreement with the experimental results.

Jan 1, 2015

By I. Imris

The chemical industries are using different type of catalysts, which after application usually produced many tons heap of residues. One of them is cupric oxide catalyst with high content of copper and silica. The recovery of copper from the waste has become major interest from a viewpoint of environmental protection and recycling of resources. The thermodynamic analysis and experimental results suggest that the copper from cupric oxide catalyst can be extracted by plasma reduction process. By plasma reduction process the inert slag and copper with following chemical composition: 99.04 % Cu, 0,042 % Fe could be obtained.

Jan 1, 2007

By M. Hamamoto, M. Furuta, S. Tanaka

The Tamano smelter and refinery has expanded its production from 228kt/y to 260kt/y since 2006. It was not a big jump, but efficient and economical improvements were executed. These were not only de-bottlenecking and modernization of the smelting plant, including the acid plant, but also additional processes were commissioned, e.g. slag cleaning furnace and steam dryer. On the other hand, a conversion to permanent cathode process in the #2 tank house made the biggest impact on production efficiency for the refinery plant. In order to overcome the drastic change of copper business, although each scale is not so big, continuous improvements are very important to survive. This paper mainly describes the recent improvements of the smelting plant.

Jan 1, 2007

By Libao Zhu, David J. Williams, Nazife Erarslan

"Statistics show that the drawbell in underground mines is usually subjected to significant damage by impact loading due to falling ore. Drawbell damage causes a large quantity of residual ore to remain on the drawbell, thus leading to a huge waste of ore resources. In this study, the Cavity Monitoring System (CMS) and Surpac software were employed to visualize the 3-D damage. Also, the Discrete Element Method (DEM) was employed to perform simulations of the falling ore to investigate the damage evolution of drawbells under repeated ore impact and obtain the dynamic damage accumulation mechanism. The reason of drawbell damage was found due to the micro-shear cracks. The numerical simulations of a drawbell damage process under repeated impact loading showed the main failure type was shear failure and this type damage was found increasing with more ore falling. INTRODUCTIONDrawbells are an important part of underground mines and play a significant role in ore recovery in terms of safety, economy and efficiency (Brunton et al., 2010; Hustrulid & Bullock, 2001; Trueman et al., 2002). In most cases, blasted ore is gravitated along the drawbell and finally arrives at the footwall of the drawpoint. However, some of the blasted oversize ore blocks clog the drawbell road and those ore pieces are called hang ups (Penswick, 1997). However, any damage on a drawbell is believed to be the reason for these hang-ups. In the literature, researchers have reported that the stability of the draw-point is influenced by the stress distribution above and near the drawbell (Butcher, 1999; Neverov & Neverov, 2013). Much research in the literature has been done on draw-points in underground mines. In fact, rockfalls cause very serious damage on a small impact area in a very short time (Volkwein et al., 2011). Hoek (2000) pointed out that the blasted ore causes progressive ravelling and even collapse of the drawpoint, thus the ore in the stope is abandoned. In this paper, the Cavity Monitoring System (CMS) was employed to obtain the damage profile of a drawbell due to the impact of rockfalls and to confirm the residual blocking ore on the damaged drawbell. Then, the drawbell damage evolution due to repeated falling ore was simulated by the Discrete Element Method (DEM)."

Jan 1, 2015

By Ma Yuxin, Niu Fusheng, Yuan Zhitao, Bai Limei, Han Yuexin

"Using batch flotation experiment, contact angle measurement, particle size analysis, and scanning electron microscope (SEM), the influence and difference of pH value on the flotation rate of talc and chalcopyrite were investigate without collector at the pH range of 3~11. The results showed that, the flotation rate of talc decrease with the increasing of flotation time, while that of chalcopyrite hardly affect by flotation time, besides, the flotation rate of chalcopyrite is much less than that of talc, so the laws of flotation rate of the two minerals are independent of pH value. The flotation test data of two minerals are simulated with first order and multi-rate flotation kinetic model respectively. The simulation results showed that flotation of talc only meet the first order kinetic model, while chalcopyrite’s meet the both. In addition, According to test results of talc and chalcopyrite by the particle size distribution, SEM photographs and the contact angle measurement, the reason why talc did not conform to the first order kinetic model is not because of particle size distribution, but of particle shape. That is to say, because of sheet structure of talc, the contact angle of layers and sections are 74°and 52°respectively. At the same time, the contact angle of layers and sections are different between the particles. So flotation rates between talc particles are difference.INTRODUCTIONPossessing superior self-induced, collector-induced and sulfur-induced floatability, chalcopyrite exhibits good floatability at a wide range of pH values and potentials. Serpentine are regarded as the most difficult selected type in various chalcopyrite ore, and the predominant reason is that it contains talc. Talc, as a nonpolar layered silicate mineral, is one kind of common associated mineral in sulfide ores (Lu, 2010). Concentrate quality and flotation process of chalcopyrite are influenced as a result from the presence of talc. It is because that talc has inherent floatability which makes it readily mixed with the floated mineral and talc is easy to slime causing the slime coating of the valuable mineral (Beattie et al., 2006). Thus in order to improve the flotation effect of chalcopyrite, methods can be introduced from two respects. One method is that fast-floating talc mineral is floated preferentially, and the other is that sulfide mineral is floated prior to talc by depressing the flotation of talc mineral (Beattie et al., 2006), nevertheless, no matter with which the flotation effect of fine-sized chalcopyrite is not positive. Therefore, in order to realize the flotation separation of talc and chalcopyrite, the difference between the inherent floatability of fine-sized chalcopyrite and talc is researched and analyzed in terms of flotation dynamics in the absence of collector and frother."

Jan 1, 2016

By Linlin Tong, Xiangling Song, Guobao Chen, Zhenan Jin, Hongying Yang

Biooxidation of a high arsenic-bearing refractory gold ore was investigated to determine the arsenic removal efficiency by the cultured bacteria and to examine the effect of biological pretreatment on subsequent gold cyanidation. The biooxidation pretreatment process utilizes the ability of adapted acidophilic bacteria to oxidize pyrite and arsenopyrite and release the encapsulated gold. The released gold can be efficiently extracted by the subsequent cyanidation process. The biooxidation experiments were conducted with cultured bacteria using various sizes of agitation tanks. Leaching results showed that over 96.26 % arsenic extraction could be obtained from this ore after 6 days of bioleaching with continuous stirred tank reactor (CSTR). Gold extraction during the cyanidation process was increased from 29.35% to 96.71% after biological pretreatment. The content of arsenic in the biooxidation residue was reduced to below 0.3%. The transformation process of As was considered as [AsS]2- ? As (?) ? As (?) during the biological pretreatment.

Jan 1, 2014