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By Cesar A. Urbano Jr., Gretchen T. Lapidus

A series of experiments examined silver extraction from a high-grade sulfide concentrate employing thiourea solution. Thiourea was initially oxidized with hydrogen peroxide (H2O2) to form formamidine disulfide (FADS) and used to extract silver from the as-received concentrate and after various pretreatments. Very low recoveries (~30%) were obtained with the as-received concentrate due to competitive cementation reactions by metallic iron and easily oxidizable copper phases. Over 80% Ag recovery was obtained when the concentrate was pretreated to remove this iron and copper. The results suggest that an oxidative acid pretreatment of this concentrates significantly improves silver recovery upon leaching with thiourea.

Jan 1, 2014

By A. Poor Zaeif Doost

With columns being installed in rougher section at Miduk Copper Complex, the rougher feed mainly reports to rougher-scavenger cells. To evaluate the efficiency of regrinding circuit, we conducted flotation experiments on samples of the feed and the products of the regrinding circuit. The grade difference of these products at 85% recovery was considered as the efficiency index. Results show that, with weight recovery of the rougher-scavengers the efficiency of the circuit increases. Exclusion of the rougher-scavenger concentrate from the feed to the regrinding circuit, resulted in an increase in the efficiency index from 10.12 to 17.6%.

Jan 1, 2012

By L. Fernandes

A two level factorial study was undertaken to investigate the relative impacts of factors affecting the kinetics of polytetrafluoroethylene, PTFE, assisted pressure oxidation of chalcopyrite. A copper flotation concentrate, principally composed of chalcopyrite, was leached in 850 mL of leach solution under conditions similar to those of the CESL process. The factors manipulated were: the amount of 1/8" PTFE beads added (100 g or 650 g), oxygen pressure (690 kPa or 1030 kPa), and concentrate addition (10 grams or 65 grams). Copper extraction data, which indicated complete leaching under certain conditions, were fit using a shrinking core model from which rate constants were estimated and further used to generate a statistical model containing only the factors of significance and their interactions. Results indicated a strong positive effect of PTFE addition and a strong negative effect of increasing pulp density. A weak negative interaction between increasing PTFE addition and pulp density was attributed to PTFE/concentrate agglomeration.

Jan 1, 2014

By Ron Jessulat

"IntroductionBrunswick Mining and Smelting Corp. Ltd. is a IO 500 tid base metal producer. Development is carried out by Jarvis Clark MJM-21 3-boom development jumbos, using Tamrock E400, 410 and 550 pneumatic drills. Typical drift size is 13 ft by 18 ft with a 12-ft advance per round. Blast holes are 1 ½ in. in diameter while reamed holes are 3 in. in diameter. AN/FO is the principal blasting agent, being loaded by C-I-L model60R intermediate loader. The detonators are NONELS and DETINELS. Sulphide dust explosions occur during blasting when dusts from certain minerals such as pyrite and pyrrhotite are ignited by name from the detonating shots. The result is a secondary unwanted explosion with a characteristic shock wave and name front that are very destructive to mine services such as ventilation ducting, electrical cable, and ventilation control doors.A typical reaction in the Brunswick orebody occurs according to the chemical formula:4FeS 2 + IIOs-2Fe2O3 + 8SO2 + 3458--(Enright , 1988)The hematite (FeO3) is deposited as a red dust in the blast area while the toxic sulphur dioxide gas (S00 contaminates the underground workings . The presence of S02 gas disrupts production until it is purged from the area by the mine ventilation system or dissipates slowly in those areas where the vent ducting has been melted by the name front or torn down by the shock wave.Sulphide dust explosions exact a high economic toll. Direct costs in damaged materials and wages are probably exceeded by the value of lost production and disruption to the mining cycle. In addition, the health and safety concerns associated with sulphide dust explosions cannot be ignored."

Jan 1, 1993

By Richard S. Allen

"The casual visitor is not apt to think of the Adirondacks as a one-time hive of mining and manufacturing activity. However, where there are mountains there are usually minerals and northern New York State is no exception.The Adirondacks are a rocky shield, a great stone cap pulled down over what is now northern New York. The bedrock consists of layered metamorphic rocks which were once sandstones or limestones on the bottom of a shallow sea that covered the region 1000 million years ago. The highlands are composed for the most part of the igneous rock anorthosite. Ancient earth upheavals at temperatures of at least 750°C mixed molten masses of anorthosite and the minerals it contained with the older metamorphic rock, resulting in deposits of iron-titanium oxide s, red garnet and other valuable minerals. Of these, the most readily recognizable was iron.The first hint of the existence of iron ore in the Adirondack Lake Champlain region of upper New York State seems to have come from a Swedish naturalist, Peter Kalm (1716-1769), who travelled through French Canada and visited the military outpost of Fort St. Frederic in 1749. In July of that year, Kalm wrote:""Among the kinds of sand which are found on the shores of Lake Champlain; one is black and the other garnet-colored... and they sparkle when the sun shines. All the grains of this sand without exception are attracted to the magnet, the uppermost or black sand being about a quarter inch deep...""Concerned primarily with the fur trade, the officers and men who occupied this remote bastion of La Belle France were apparently unaware of the industrial and commercial possibilities beneath their feet. No deposit of iron was then known to exist any closer than the Three River s area in Lower Canada."

Jan 1, 1983

By N. Shi, T. G. Joseph

ABSTRACT A revised equilibrium approach to evaluate dipper-ground interactions during the dig cycle of ultra-class mining shovels operating in soft unblasted uniform ground conditions is presented. A review of previous approaches, leading to an outline of the modifications and ground condition considerations, is made in support of the reasoning and basis for the derivation presented. An analytical solution is provided to the scenario of a cable shovel dipper digging in soft ground material such as oil sands.

Jan 1, 2012

By M. Sokoto, H. Hata, K. Nishina, K. Haiki

Fluoride ions in zinc electrolyte cause corrosion to aluminum cathode plates at zinc electrowinning process, so we have developed an iron compound as a fluoride ion adsorbent used in zinc sulfate solution. The iron compound is synthesized from FeC13 solution with a small amount of sulfate ion by neutralizing reaction with Na2CO3 solution. The fluoride ions adsorbed on the surface of the iron compound are desorbed in alkaline solution and the iron compound can be reuse as a fluoride ion adsorbent. Moreover, if adsorption capacity of the iron compound decreases, it can be dissolved in HCl solution and re-synthesized.

Jan 1, 2008

By D. R. Schmitt, Q. Jia, R. Kofman

"Tests were carried out on clear glass blocks containing borehole aligned with and at an angle to applied principal stress states in order to study the growth of drilling induced tensile fractures. The samples were illuminated such that photoelastic fringes could be video recorded during the measurements; this was useful in assessing states of stress and in determining fracture initiation. Axial drilling induced fractures were observed at the azimuths of the applied uniaxial stress as would be expected from the concentrated stresses. En echelon fractures were observed from the borehole deviated at 45° to the direction of the compression. These preliminary and currently qualitative results show that glass blocks serve as a useful test medium for studies of stress concentration and drilling induced fracture creation. INTRODUCTIONWith the increasing exploitation of unconventional oil/gas reservoirs using deviated drilling in recent years, the effects of the in-situ stress on the success of energy production have become more critical than ever before. Knowledge of the state of stress in the earth enables us to determine well trajectories, well locations, hydraulic fracturing design and production rates, but knowing the crustal stress is always challenging. Strictly, it can only be obtained to varying quantitative degrees by accessing the earth through drilling. Failure of the rock at the borehole wall produces borehole breakouts (e.g., Bell & Gough, 1979; Haimson & Herrick, 1986; Zoback et al., 1985) and drilling-induced tensile fractures (DITF) (e.g., Aadnoy, 1990; Aadnoy & Bell, 1998; Barton et al., 1997; Brudy & Zoback, 1999; Davatzes & Hickman, 2010; Peska & Zoback, 1995). Thus, it is important to understand the failure mechanism of the rock in the vicinity of the borehole. A number of closed-form expressions have been developed that allow the stress concentrations to be calculated in the vicinity of a borehole including Kirsch’s (1898) 2-D plane strain solution and 3D formulae for elastically isotropic (Hiramatsu and Oka, 1962) and anisotropic (Lekhnitskii, 1981; Amadei, 1983) continua. These solutions have been applied in numerous studies (e.g., Ong, 1994; Ong & Roegiers, 1996; Vahid & Ghassemi, 2011; Jia & Schmitt, 2014; Ito et al., 2001) to analyze the failure mechanisms of drilling-induced tensile fractures (DITF) on the borehole wall."

Jan 1, 2015

By R. J. Mitchell

"Centrifuge modelling of earth structures is a well-proven technique for evaluating the performance of prototype structures using physical models. The applications of this technique have increased dramatically during the last decade such that even the modelling of dynamic responses in structures has been accomplished.This paper presents the first model test results used to design a mine backfill. The models were tested using a 3 m radius 30 g-tonne geotechnical centrifuge which was constructed at Queen's University specifically for model studies on mine backfill stability and subsidence. The models represent the first production blast-hole stope to be mined at Westmin Resources Ltd. 's H. ~ Mine on Vancouver Island. This paper includes photographs of:model failures in the centrifuge and correlations of model test results with analyses based on unconfined and triaxial test data.IntroductionDuring the feasibility study and development stages for the H.W. Mine, Westmin Resources Ltd. conducted a comprehensive rock mechanics and backfill engineering program. The results of these studies indicated the need for assurance of backfill stability during pillar recovery on the initial blast-hole mining block. The cemented tailings backfill had to be free standing for heights up to 25 m and the potential for surcharge loading from a weak hanging wall zone, the potential for fill block sliding down-dip and the potential for seismic loading had to be considered in the design of the fill strength. The basic questions to be answered were: what cement content is required and will the resulting backfill costs be economic relative to the proposed mining method and sequence? Figure I shows a typical cross-section through the first mining block . The up-dip stope is to be mined first and backfilled with cemented tailings . The down-dip stope would then be mined and filled. Depending on ground conditions encountered, the complete intervening pillar could be recovered and the void backfilled with uncemented tailings or it could be recovered in small sections by exposing limited back and wall areas, backfilling with waste rock and I or cemented tailings . This latter method is commonly referred to as the Avoca method"

Jan 1, 1987

By G. Sperlins

"IntroductionBrenda Mines Ltd. is a low-grade open-pit mining and milling operation located near Peachland, B.C. Brought into production in late 1969, the plant treats an average of 30,000 tons per day of an ore that contains 0.130% copper and 0.030% molybdenum.The operation is divided into six areas of responsibility, namely the mine, mill, plant, accounting, industrial relations and purchasing /stores departments.The purchasing and warehousing area handled in excess of 11,000 items valued at $31,000,000 in 198J. Over and above this, the warehousing area issued in excess of 74,000 line items valued at $15,000,000 during that same period.Materials Management- DefinitionWhat is meant by the term ""Materials Management""? Reference to the dictionary will reveal that a material is ""that of which anything is composed or may be constructed; the tools, instruments, implements', etc. for doing something"". Management is defined as ""the act, or manner of managing; the skillful use of means to accomplish a purpose"". Presumably combining these words defines materials management.Of greater importance are the materials managers who will carry out the function. At Brenda Mines Ltd., all employees and suppliers contribute to the materials management function. Each has a specialized knowledge of the materials used in his field. Each has a different view concerning the use and description of the same material. The key is to focus this knowledge so as to make the materials management system useful to everyone."

Jan 1, 1982

By V. Fiedler, H. Lachmund, R. Bruckhaus

"After producing some 50 million tonnes of crude steel the two BOF vessels at Dillinger Hüitte steel plant had to be replaced in 2000/01 due to large deformations. The new vessel design was optimised after a number of theoretical evaluations.Refractory investigations were carried out as well as temperature measurements of the shell to provide a basis for selecting a suitable steel grade. This was found in a DH-GTS development - P420M HT - with high strength at elevated temperatures and excellent weldability and made it also possible to build the vessel without any cooling system.After putting the first vessel into operation the metallurgical results showed no remarkable improvement compared to the old vessel, and were therefore not satisfying. With the help of cold model investigations the arrangement of the tuyeres was modified to improve the flow conditions and the interactions between oxygen jet and the heterogeneous plume of the bottom stirring gas. Further optimisations were obtained by a variation of lance tips and a newly developed lime addition model."

Jan 1, 2004

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By John H. Fowler

"Barytes is one of the major components of drilling fluids used in oil and gas well-drilling. This mineral's close association with the petroleum industry bestows it with a commodity status not enjoyed by many other industrial minerals. Approximately 85% of world barytes production is used as a weighting agent in oil and gas well drilling while the remaining 15% is consumed mainly in the manufacture of barium chemicals, glass and as a pigment, filler or extender.Barytes mining began in Nova Scotia around 1865 and has continued until the present. Currently there are three barytes producers in the province one exporting pharmaceutical-grade barium sulphate and the other two supplying drilling mud-grade barytes to the offshore. Several barytes exploration and development programs are underway with excellent possibilities that Nova Scotia deposits will supply a significantly larger share of the drilling mud-grade barytes used in east coast drilling programs.Currently there is renewed interest in barytes activities in Nova Scotia because of its use as a weighting agent in drilling flu ids used in offshore oil and gas drilling programs.This paper reviews the use of barytes by the well drilling industry; outlines the history of barytes mining in the province, progressing to present-day exploration, development and production activities underway in Nova Scotia; and concludes with the market potential for Nova Scotia barytes."

Jan 1, 1986

By C. Gu

Flow field design is critical for PEM fuel cells. The flow field design can affect reactant distribution to the catalyst surface, water management, thermal management and current collection. Therefore, it has tremendous impacts on the fuel cell performance and durability as well as reliability and operational flexibility. In this paper, an optical method is used to study the reactant distribution in the flow field channels of two commonly used flow field designs, straight channel design and serpentine channel design. Images of the flow patterns are shown followed by discussions of the flow patterns.

Jan 1, 2005

By Dave N. K., T. P. Lim

"A fast, reliable and accurate method for radium-226 determination in environmental water samples has been devised, using an alpha spectroscopic technique. The correlation between barium-133 and radium-226 in the barium-radium sulphate precipitation mechanism was studied and in the limited experimental recovery range, the coefficient of correlation was r = 0.986. A self-absorption study for various barium carrier concentrations was also undertaken to obtain the least broadening of alpha energy line widths. An optimum value of 0.3 mg barium carrier was obtained for chemical recovery in the range of 85%.IntroductionWith the increase in uranium mining activities, the migration and spread of radioactivity via various environmental pathways is of great concern. Because of its inherent biological hazard and relatively long half-life, (approximately 1620 years), raidum-226 is frequently monitored as a measure of radioactive contamination of the environment. It is, therefore, necessary to modify existing methods for rapid determination of radium-226 in environmental samples for quick corrective measures in the event of seepage, dam leakage or discharge violations."

Jan 1, 1981

By W. G. Jeffery

"The mining and mineral industries have been, and remain, a major component of the Canadian economy. There are approximately 560 producing mining establishments of which there are some 130 metal mines and an equal number of non-metal mines, the balance being quarries for stone, sand and gravel. For 17 metals and minerals, Canada ranks within the top five as a world producer. There are 29 metallurgical plants. Employment in mining, smelting and refining was about 150000 in 1990. Mineral production, including coal, is about $20 billion. Exports up to the metal stage amount to $15 billion providing a positive trade balance of some $10 billion.The producing industry has a wide diversity of products. The companies range from small single mining operations to large multinationals. In terms of technology the industry has always been in the forefront of cost-effective practice, either using home-grown innovation or freely importing technology from around the world,The Mining Industry Technology Council (MITEC) makes an annual survey of the exploration and R&D expenditures of the senior mining industry that is the mining companies that are involved in mineral production from their existing mines. It does not include those companies solely involved in exploration using funds raised through equity sales.Table 1 shows the actual R&D and exploration expenditures as a per cent of sales. R&D shows a rising trend since 1988although the drop in value of output due to lower prices must be recognized as contributing to the increase. The point about this compilation is that the mining industry re-invests some 4070 of its sales in both exploration and R&D in order to sustain itself. Exploration for the renewal of metal inventories for future mining is a process unique to mining. It is not classified as R&D, and the necessity for this investment goes unrecognized by those who state that the industry does not do enough R&D."

Jan 1, 1993

By M. H. Moys, C. Bhondayi, Eric Tshibwabwa

"The relationship between froth bubble size as represented by intra-bubble impact distances (IID) and flotation performance is investigated. Experiments using an artificial ore comprising of limestone as the floatable component and silica as the gangue material were carried out in pseudo-steady-state circuit. A method to measure IIDs developed by Bhondayi and Moys (2014) was then used to measure froth bubble sizes as a function of froth height, superficial gas velocity and feed rate (pulp residence time). Samples for flotation performance evaluation were also taken. Results indicate that as froth height increases, the average IID values increase resulting in a decrease in limestone recovery while the grade increases. Increasing gas rate results in lower IID values that are accompanied by high recovery and low limestone grade. The effect of feed rate on both flotation performance and average IID values depended on froth depth and gas rate. Average IIDs largely remained the same at the two feed rates investigated.INTRODUCTIONIt is regarded as obvious that froth bubble size distribution (FBSD) will have an effect on plant grade and recovery. As the average FBSD decreases, the bubble surface area flux will increase making possible an increase in recovery and a decrease in grade. The opposite trend will be involved if average FBSD is increased. However: no method for measuring FBSD has been available, so these trends have not been studied in any detail. Bhondayi and Moys (2014) developed a novel technique to measure or estimate froth bubble sizes. Although they established a potential to use this method in understanding froth performance, no data have been presented to assess the correlation between the estimates of bubble sizes and actual flotation performance. In this work experiments are done to establish how the change in froth phase bubble sizes affect flotation performance. Flotation performance will be evaluated using recovery and grade. How water recovery to the concentrate changes with changes in bubble sizes will also be evaluated. It is known that water recovery is approximately inversely proportional to the square of the overflowing bubbles sizes. It will be interesting to establish how the rate of change of bubble sizes changes with water recovery."

Jan 1, 2016

"Classification is an important aspect of mineral processing plants and if not operated efficiently can compromise both the throughput and recovery of the circuit. This paper discusses the benefits that can be obtained by operating the classification section efficiently. Since classification in most of the mineral processing plants is carried out using either hydrocyclones or screens the case studies involving the two classifiers were used in the discussion. Studies where optimising the classification circuit lead to improvements in the performance of the overall plant were included to show the benefits of paying attention to this area that is usually neglected. The data from the mill-float mill float, SABC, and Single Stage SAG mill circuit case studies have shown that the circuit throughput can be increased throughputs without compromising recoveries by optimising the classification circuit. On plants where the ore can be liberated at coarser sizes the experimental results have shown that replacing hydrocyclones with high frequency screens can lead to improved plant throughput with no detrimental effect on recovery. The discussion has included information on design and operational considerations for plants that have or intend to use hydrocyclones or screens that could make the classification circuit more efficient.INTRODUCTIONComminution is the process in which particles are reduced in size mainly by crushing and grinding. In most mineral processing circuits comminution is carried out to liberate the valuable minerals prior to subjecting the ore to a recovery process were values are concentrated or extracted (Mainza, Evertsson, Benzer, Tavares, Powell, Rule, Plint, …, 2013). Comminution is an energy intensive process and is usually achieved in stages. It is common to have a classifier after each comminution stage. The process is carried out in stages to minimize energy usage and to improve the efficiency of the process in meeting product specifications. Although comminution circuits have been advancing classification has remained a key component of the comminution circuit design (Mainza et al., 2013). Mainza et al. (2013) summarised the role of classification in mineral processing circuit as: to allow material in the equipment that can promote high operational efficiency, to improve material handling in the circuit, to minimize overgrinding of material to reduce energy consumption, and to provide the best quality product to enter the next stage of processing. Classification stages are employed in comminution circuits to ensure that high throughputs are processed without compromising the product quality or to produce a fine product at relatively low energy. If neglected classification can have detrimental effects on plant performance."

Jan 1, 2016

By L. Zeka, I. Ndala, J. Frenay, S. Gaydardzhiev

"Reductive leaching of cobalt (III) from a heterogenite bearing ore has been performed. Pyrite was added to the system and simultaneously bioleached in order to provide ferrous iron as reducing agent. Within such arrangement the iron ions are continuously re-circulated inside a Fe 3+ / Fe 2+ loop. As a result Co(III) is solubilized in the presence of Fe 2+ ions in concentrations well below the stoichiometric requirement. The ore has been initially subjected to acid pre-leaching in order to guarantee that the available Co (II) has been entirely removed. Two technological parameters have been studied to show influence on the degree of cobalt leaching: concentration of ferric iron in the inoculum and the presence of bacteria. The bacterial role could be mainly viewed in supplying ferric ions in the system which chemically react with the pyrite to generate ferrous ions used as Co(III) reducing agent. Co(III) dissolution has been less efficient when the concentration of total iron in the system was low, but also when microorganisms were absent. SEM observations on leached heterogenite have evidenced bacterial attack on the mineral; however the precise role of bacterial presence on cobalt (III) leaching is still to be elucidated.INTRODUCTIONCobalt accompanies quite often copper in secondary oxidized ore deposits (Rumbu, 2013). In such associations cobalt is found both as CoII+ as well as CoIII+ (Deliens, 1974). In contrast to cobalt (III), cobalt (II) is leached relatively easy in sulphuric acid solutions. Cobalt (III) when present in mineral form belongs to the heterogenite mineral group with a simplified chemical formulae Co2O3.H2O or CoOOH. In order to be brought in solution, heterogenite should capture two electrons, likewise shown in reaction 1 below:"

Jan 1, 2016

By A. Warczok

The mechanisms and kinetics of copper oxidation and reduction have been investigated in small scale thermal gravimetric experiments as well as in laboratory pilot scale, packed bed reactors. With blister copper flowing gravitationally down through a packed bed of ceramic particles, counter-current to low oxygen containing combustion gases, the rate of oxidation was found to be very high due to the large surface area created. Similarly, reduction by flowing copper through a packed bed of charcoal lead to rapid de-oxidation. Based on these laboratory measurements, fundamental rate data have been obtained. Modeling of industrial sized packed bed reactors using the laboratory results, opened up the possibilities of developing a new, very intensive, continuous process for copper fire refining. The developed mathematical model together with a computer process simulator, allowed for the design of the industrial-pilot installation to be built and tested at the ENAMI Paipote smelter in Chile.

Jan 1, 2007