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By Y. X. Li, L. R. Xiao, S. Gong, S. S. He

Porous copper and porous copper based alloys with controllable pore structure have been manufactured successfully by sintering evaporation process. This process consisted of mixing copper or copper based alloys with NaCl powders, hot pressing and final high-temperature sintering to evaporate the filler material of NaCl powders. NaCl was eliminated completely during vacuum sintering, and strong metallurgical bonding in the walls was achieved. The pores’ structural parameter (pore size, shape, and direction) and porosity can be controlled effectively. These porous copper and porous copper based alloys with controllable pore structure have great potential in many fields. Including heat dissipating materials, heat absorbing materials, chemical catalyst carriers, electromagnetic shielding materials, filtering materials, damping materials, silencing materials, battery electrode materials. INTRODUCTION The development of porous materials began in the 1960s. The research of activated carbon with high specific surface area made porous materials enter the stage of material research (Belyakov et al., 2008; Ferey et al., 2008). With the rapid development of science and technology, porous materials play an important role in material research, and gradually become an indispensable part of the material research field (Wu et al., 2012). The research of porous materials has gradually extended to metal, ceramics, plastics and glass and other fields. It has been successfully applied in many fields, such as functional materials, industrial production, aviation, medical materials, biochemistry and electronics, which fully shows that porous materials have considerable development prospects. Porous silicon, plastic porous materials and glass porous materials are the most widely used in the field of non-metallic porous materials (Capelle et al., 2012). Compared with non-metallic porous materials, metal porous materials have developed rapidly in the late 1980s and become new materials with good mechanical properties and excellent physical properties. Porous metal materials have many advantages, such as large specific surface, small specific gravity, good silencing effect, high stiffness, high electromagnetic shielding performance, good shock absorption performance, etc (Li et al., 1999; Ferey et al., 2008). Among its many applications, metal porous materials can be used as both functional materials and structural materials. In some cases, metal porous materials have dual functions and structures. It is a multi-purpose engineering material with excellent performance. At present, porous copper, porous aluminium and porous nickel are the most concerned materials (Chen et al., 2002; Yang et al., 2017; Liu et al., 2018). The preparation methods of porous copper and copper-based alloys mainly include self-propagating high temperature synthesis (SHS), capsule-free hot isostatic pressing (CF-HIP), spark plasma sintering (SPS) (Kvanin et al., 2008; Takahashi et al., 2008; Zhang et al., 2014). However, these methods can not accurately control pore structure parameters (including pore size, shape, orientation, distribution, etc.). In porous materials, pore structure plays an important role in the overall performance of materials. In order to control pore structure parameters accurately and optimize material performance, it is necessary to explore and develop new preparation technology. In this paper, the sintering evaporation process (SEP) was introduced for the preparation of porous copper and copper-based alloys. The core process of the preparation method is hot pressing and evaporative desalination. Hot pressing can make the pore orientation consistent. Evaporative desalination can ensure the complete removal of NaCl in the form of vapor in a short time, thus eliminating the corrosion of residual NaCl on the matrix metal (Gong et al., 2011).

Jan 1, 2019

By R. W. Nice

Presently about 60% of the world's nickel resources are tied up with lateritic ores while about 25% of the world's nickel is produced from sulphides. Based on this the industry has to focus on improving lateritic nickel economics in order to maintain the high use of the metal worldwide. In 1997 three junior mining companies in Australia organised finance against all odds and commenced development of three separate nickel and cobalt extraction plants treating lateritic nickel ores. All three projects utilise similar pressure acid leaching (PAL) technologies while each has unique metal recovery technologies All projects have experienced numerous processing and maintenance related difficulties such that full ore throughput has been reached by only one operation after five years. This shortfall in performance has caused the owners considerable angst and financial pain. In 2000 Cawse went into receivership and was purchased by an international corporation. Recently, Bulong also went into receivership and has undergone an orderly shutdown, awaiting sale to a new buyer. Murrin Murrin has settled with its financiers and is in a position to operate as planned for many years forward. This paper will discuss a number of the technical difficulties that affect the ore preparation, PAL and solution treatment circuits of these plants. The objective is to identify the cause of some of the difficulties and propose possible solutions so that the next generation of lateritic operations can emerge as technically and, more importantly, economic successes. A number of these process improvements have been identified by the existing operators and in many instances have been or are being implemented into the existing operations.

Jan 1, 2004

By William M. Luff

"The Bathurst area has recorded mining production as early as 1837, although the bulk of the production has come in recent years. Production has been mainly from the well-known massive sulphide deposits, but vein, gossan, and a variety of other deposits have also been mined. This paper summarizes the history of the mined deposits, along with tonnages and grades produced. A number of ""firsts"" have been noted in the Bathurst area. The A Zone deposit, located in the Heath Steele area, was the first in the world discovered using airborne electromagnetic methods. Heap leaching of gold from the gossan zone at Caribou was the first operation of its kind in Canada. The Keymet mine was the first base metal (lead-zinc) mine in New Brunswick. For the past few years, the Brunswick No. 12 mine has been one of the largest zinc mines in the world.IntroductionThe Bathurst area (Fig. 1) first had mining production in 1837 when copper was mined from a deposit on the Nepisiquit river (MacKenzie, 1958). The majority of the production, however, has been in recent years from massive sulphide deposits, but there are also other significant operations. . Table 1 is a summary of Bathurst area mineral production, showing concentrator feed tonnages and mill feed grades. The table does not include peat deposits, sand and gravel, dimension stone or rock quarries. Figure I is a general geology map of the Bathurst area, indicating deposit locations. The deposits are divided into four categories: massive sulphide, vein, gossan and other. The deposits in each category are described in chronological order of exploitation."

Jan 1, 1995

By William M. Luff

"The Bathurst area has recorded mining production as early as 1837, although the bulk of the production has come in recent years. Production has been mainly from the well-known massive sulphide deposits, but vein, gossan, and a variety of other deposits have also been mined. This paper summarizes the history of the mined deposits, along with tonnages and grades produced.A number of ""firsts"" have been noted in the Bathurst area. The A Zone deposit, located in the Heath Steele area, was the first in the world discovered using airborne electromagnetic methods. Heap leaching of gold from the gossan zone at Caribou was the first operation of its kind in Canada. The Keymet mine was the first base metal (lead-zinc) mine in New Brunswick. For the past few years, the Brunswick No. 12 mine has been one of the largest zinc mines in the world.IntroductionThe Bathurst area (Fig. I) first had mining production in 1837 when copper was mined from a deposit on the Nepisiquit river (MacKenzie, 1958). The majority of the production, however, has been in recent years from massive sulphide deposits, but there are also other significant operations.Table I is a summary of Bathurst area mineral production, showing concentrator feed tonnages and mill feed grades. The table does not include peat deposits, sand and gravel, dimension stone or rock quarries. Figure I is a general geology map of the Bathurst area, indicating deposit locations. The deposits are divided into four categories: massive sulphide, vein, gossan and other. The deposits in each category are described in chronological order of exploitation."

Jan 1, 1995

By Fernand Dubuc

"The New Pascalis property is situated in Louvicourt and Pascalis townships, about 200 km east of Val d'Or, Quebec. It is made up of 38 claims under option to SOQUEM since August I, 1981 during which time SOQUEM has earned a 60% interest. The property is underlain by archean basaltic volcanics that have been intruded along the west boundary by the Bourlamaque batholith, and by north -trending dykes.The 1982 disco very is related to the re-evaluation of a 1931-gold showing located in the southeastern part of the property, a combination of the presence of a weak IP anomaly at the eastern end of the showing and overburden stripping at that location, resulted in the discovery of a mineralized diorite dyke.The dyke, which strikes N 20 ° Wand dips vertically , has intruded E-W striking agglomerates. The dyke contains south dipping, gold-hearing quart z-tourmaline-pyrite veins that are distributed in a ladder-type arrangement. Visible gold may he observed in drill core, and is generally associated with pyrite porphyroblasts.Diamond drilling has outlined th e dyke for a strike length of 300 11/ and a width of about 10 m, Result s of this drilling indicate, to a depth of 155 m, reserves of 834 000 metric tonnes grading 8.25 g Au/t un cut or 5.38 g Au/t cut to on e ounce. However, four deeper holes have added depth extension to 400m. Also, west of the dyke and within 150 m, other promising gold values have been intersected within quartz-tourmaline veins associated with other parallel dykes."

Jan 1, 1985

Kahama Mining Corporation Limited (KMCL), a wholly owned subsidiary of Barrick Gold Corporation, operates the Bulyanhulu gold mine. The operation has been in commercial production since April 2001 and is the first modern underground mine to be developed on the Lake Victoria goldfield in Tanzania. Bulyanhulu is located in a major mineralised system along an emerging gold trend. This area, the Lake Victoria Greenstone belt, has been the focus of significant exploration and development programs since 1994, with over 34 million ounces of gold having been discovered and four new mines commissioned. The Bulyanhulu project has accounted for just over a third of the gold resources discovered during this period. From an initial exploration program, which outlined a resource of 1.37 million ounces of gold, Bulyanhulu now hosts a reserve of some 12 million ounces in a resource base, the limits of which are, as yet, undefined. The Bulyanhulu property is located approximately 56 km south of Lake Victoria, in northwestern Tanzania, eastern Africa. A Mining Licence issued by the Government of Tanzania on July 23, 1999 grants to KMCL the exclusive right to mine a concession area covering 51.48 km2. The property is reached via a 75-km road from the main road to Dar es Salaam. The nearest towns are Mwanza to the north on Lake Victoria, 155 km by road and ferry, Kahama, 86 km by road to the south and Isaka, 126 km by road. Isaka is on the rail line between Mwanza and Dar es Salaam and has facilities to receive heavy equipment, and a fuel depot. A gravel airstrip, 1,700 m long has been constructed at the property.

May 1, 2003

By R. M. de Carvalho

Empirical and phenomenological models of SAG and AG mills have dominated the scene for the last few decades, being used nearly every time a mill is scale-up or an attempt is made to improve its performance. However, in spite of their success, these models fail to describe the details of both the grinding environment and the breakage mechanisms. The result is a generally good track record, with a few – but very important – instances when these models fall short in their predictions, which can be very costly. Further, nearly all of these models require detailed calibration to industrial and pilot plant data, being costly in their application, although still with limited predictive capabilities. Recognizing these challenges, a new model framework has been proposed which overcomes the limitations of currently used models by coupling the microscale population balance model, the discrete element model and functions that describe internal classification at the mill grate. This model framework has already been applied to describe breakage in ball mills, with showing very promising results. However, in the case of SAG and AG mills a much greater level of complexity is involved in the model, given the interaction between the mechanical environment that is formed totally or, in part, by the ore itself, and the breakage response in the mill. The paper describes the model framework, demonstrating how it can address appropriately effects such as mill speed, mill filling and size distribution, on the response from the mill. Some of the advantages of the model are related to its intrinsic multi-component and dynamic nature, which allows simulating appropriately mixtures of ores of different competences in a transient manner.

Jan 1, 2012

By Robert B. Parsons

"The new Ontario Liberal government introduced its first budget in October. The changes to The Mining Tax Act proposed in the budget are mean t 10 simplify the current system without any loss of revenue to the government. It goes without saying that some operators will benefit from the changes while others will pay more taxes after 1985.With regard to ongoing matters at the federal level, the proposed carve-out legislation and the issue of northern allowances are being discussed with government officials, and a small victory has recently been scored with regard 10 the laxation of certain share transactions of prospectors and grubstakers. A report on these issues is provided herein.Ontario BudgetOn October 24, 1985, Ontario Finance Minister Robert F. Nixon tabled a budget proposing several significant changes to both the Ontario Mining Tax Act and the province’s income tax legislation.Mining Tax ActA flat rate of tax and reduced processing allowances highlight proposed changes to The Mining Tax Act. The proposed changes, with a comparison to the existing system, are set out in Table I.The most significant change is the replacement of the graduated tax rate schedule with a flat 20010 tax rate. This is a welcome change for most mine operators who viewed the high rate of 30% on profit over $20 million as counter-productive.However, the flat rate of ta x may not be welcome to all operators. Generally speaking, operators with less than $ 10 million annual profit are better off under the graduated rate system, while operators with annual profit exceeding $10 million will benefit from the 20010 tax rate."

Jan 1, 1986

By W. Evans, C. E. Ells

Nuclear power reactors using zirconium alloy pressure tubes generate electricity in several countries. Such reactors are particularly important in Ontario, where CANDUs* generate about 30% of the total electricity produced in the Province. Starting with the commitment of NPD-2 in 1956, the pressure tubes of the first five CANDU reactors were made of coldworked Zircaloy-Z, an alloy of Zr and Sn. This alloy was developed by the US Navy, but the decision to use it in a cold-worked condition was based on AECL work. In 1958, the USSR published information on a new alloy, Zr-2.5 wt% Nb. The Nb promotes stabilization of the (3-phase in the material, thus presenting opportunities of exploiting metallurgically strong pressure tubes analogous to the heat-treatable cx-{3 titanium alloys. After construction of two reactors using Zr-2.5 wt% Nb in a quenched and aged condition, an extensive development program on cold-worked Zr-2.5 wt% Nb pressure tubes resulted in them becoming the reference tubes for all CANDU reactors committed since 1966. Anticipating the future needs of the domestic and export markets, AECL have pressure tubes of Zr-3.3 wt% Sn-0.8 wt% Nb-0.8 wt% Mo (Excel) in an advanced state of development. These tubes will be used in an annealed condition; our projections show that they will have improved dimensional stability over the lifetime of the reactors. These improvements result from experimental programs leading to an understanding of the relationship between microstructures and fabrication variables and effects of the environment during service in nuclear reactors.

Jan 1, 1981

By Charles S. Ney

"ZINC-LEAD REPLACEMENT deposits straddle the steep-sided valley of Kicking Horse River at a point three miles east of Field, B.c., in Yoho National Park. The Monarch orebodies extend into Mt. Stephen on the south side of the valley, and outcrop at two points, 1,000 and 1,200 feet above the valley floor. The Kicking Horse deposits are in Mt. Field, on the north side of the valley, and they outcrop 200 feet lower.The East Monarch outcrop is said to have been discovered in 1884 during construction of the Canadian Pacific Railway. The larger West Monarch outcrop, 700 feet west of the original discovery, was not reached till 1917 because of its nearly inaccessible location on the cliff face.The Kicking Horse mine was staked in 1906. Little development was done for several decades, and mining was not commenced till 1935.At the East Monarch, mining was commenced soon after location, and several thousand tons of ore were shipped prior to 1912. At this time a gravity concentrator was installed. This was operated till 1924, and a total of 42,000 tons of ore were mined, including about 10,000 tons from the West Monarch. The period from 1928 to 1935 featured flotation milling and the mining of 265,000 tons of ore, mostly from the West Monarch orebody. Intensive exploratory development was carried out in both Monarch and Kicking Horse from 1935 to 1946. Production from both mines in this period totalled 380,000 tons. From 1947 to the time of closure in 1952, considerable new ore was found in both mines and 185,000 tons were milled. Immediate possibilities for finding ore in the Monarch were considered exhausted. Kicking Horse orebodies are known to persist with a low grade of zinc. Total production from the two mines amounts to 842,500 tons grading approximately 7 per cent lead, 10 per cent zinc, and 1.2 ounces per ton silver."

Jan 1, 1949

By L. H. Thorleifson

Demand for both gem and industrial diamonds is very strong. Synthetic production supplies industrial uses, but synthetic gems remain inferior and expensive, so the large gem market is supplied by mining. Several major mines have been depleted, and the market is receptive to new sources of high quality gems. Canada's Precambrian terrane, extending across the Canadian Shield and under the Phanerozoic cover of the Plains and Hudson Bay, has excellent potential for diamonds, but exploration conditions are difficult due to recent glaciation. Early world exploration relying on recognition of diamond in alluvial sediments was adequate to launch pre-1900 production from India, Brazil, and Africa. Exploration success in Canada, as was the case in Russia and other more recently discovered sources, however, had to await large investments in effort supported by advanced science and technology. Canadian exploration in many ways is similar to that in other regions, relying on analysis of tectonics, indicator minerals, geophysical surveys, and multiple stages of drilling and sampling. Very different from other regions, however, is Canada's surficial environment, in which recent glaciation has caused fresh indicator minerals to be transported hundreds of km. Exploration accelerated in Canada after 1960, first in Ontario and the Arctic Islands, then in Saskatchewan in 1988, and most importantly after the Chuck Fipke - Stew Blusson discovery at Lac de Gras, Northwest Territories, in 1991 that led to the billion-dollar BHP - Dia Met Ekati Mine that opened in 1998. In 2003, production from Ekati is expected to be supplemented by that from the similar and nearby Diavik Mine of Rio Tinto and Aber, currently under construction. These mines will bring Canadian output to over 10% of world supply, and will position Canada with Botswana and Russia as world leaders in production of high quality gem diamonds. There could be other mines as well, as sites across the Arctic and in the south from Alberta to Québec are being explored by an array of companies, including De Beers, other majors, and several juniors.

May 1, 2001

By Haibin Wang, Zhiwei Huang, Zhixiang Cui, Wenzhao Cui, Zhi Wang

Fangyuan Two-Step copper smelting process was commercialized in October, 2015 and has been operating for 3 years and 5 months. As the unique continuous copper smelting process with simplified flow in the world, production parameters have been significantly improved after three years. In the first half of 2018, the feed rate was above 200t/h, availability reached 97.5%, operation cost was about 20% lower than the conventional three-step processes showing obvious economic advantages. The Two-Step process in Fangyuan is composed of 1 Submerged Lance Smelting furnace (SLS) and 2 Submerged Lance Converting& Refining furnaces (SLCR). Two SLCRs work alternatively to ensure continuous production. High grade and liquid matte from the SLS is introduced to the SLCR by sealed launder to complete converting and refining. The SLCR is an original and independent innovation of Fangyuan, for which Fangyuan completed lots of development and improvement. This paper will introduce the process and experience. INTRODUCTION China is the largest producer and consumer of refined copper. Most of the processes adopted in China are conventional "Three-Step" copper smelting processes, which are comprised of smelting, converting and refining. There exists some problems in the conventional processes, such as high energy consumption, large heat loss, low altitude emission of SO2, etc. To deal with these problems, Fangyuan developed the new copper smelting process with simplified flow, low cost, clean and high efficiency. The SLCR that combines converting and the refining process was also developed, which shortens the process flow from conventional three steps to two steps. The SLCR is of great significance in promoting the development of the copper industry. Development and industrialization of SLCR At present, copper concentrates are treated in three steps: smelting, converting and refining. Anodes are also produced by continuous converting processes such as the Mitsubishi process and the Double Flash process. Problems like matte transportation by ladle, capacity limitation, and low altitude pollution exist.

Jan 1, 2019

By G. W. Diehl, G. A. Griffiths

"Gentlemen, one week ago, I attended the University of Minnesota's Annual Symposium on Mining, in Duluth. A good part of this symposium was dedicated to mill linings of rubber.At this symposium, three mining companies published results from long time full scale tests with rubber linings in mills at four different mines. These were the Republic and Empire Mines of Cleveland Cliffs Iron Company, the Groveland Mine of Hanna Mining Company and the Eagle Mountain Mine of Kaiser Steel Corporation. These papers will be printed in due time and I will not endeavour to relate their full contents, let me only say that in three of the plants, the linings were found to be very economical compared wi.th steel, and that these three are converting over completely to rubber linings, while the fourth, Empire Mine, reported no economical results as far as the shell lining goes, whereas the grates showed promise of becoming economical. The authors of the Cleveland Cliff's paper, however, stated that design improvements in the rubber lining possibly could result in an economical lining also for Empire Mine.That rubber linings in mills, in most cases, show better wear life than steel linings, is known by most of the audience. But, one thing that has not before been disclosed by the endusers is the effect of rubber linings on the grinding economy. All three papers mentioned above reported no change in capacity or grind and two of them reported a decrease in power consumption per ton ground. Hanna Mining reported an average decrease over a three year period for one mill of over 10%. This, of course, puts the economy of a rubber lining in a completely new light. Finally, a point of interest at this meeting was that all three papers emphasized the design aspect, Thus the industry has acknowledged what I believe to be a very important fact - the design of a lining is often more important than the material it is made of."

Jan 1, 1970

By Poul Hansen

"In mid-1986, a world-class mining enterprise was created in Highland Valley, British Columbia, bringing together the copper mining operations of Lomex and Cominco . In 1988, Highmont joined the new partnership.Highland Valley Copper is the largest copper mine in North America in terms of both tonnage mined and tonnage milled, and it is one of the largest in the world. Due to its relatively low ore grade its production of copper in concentrate ranks about ninth in the Western World.The current eighteen year mine plan is based on ore reserves of 761 million tonnes. The daily milling rate is 133 000 tonnes. At the end of mine life, a total area of approximately 6500 hectares will have been disturbed. At this time, vegetation has been established on about 600 hectares and while work will be done during the operating years, it will not be until the end of mine life, about 2008, that the last half of the land can be reclaimed and revegetated.Once final reclamation has been accomplished, Highland Valley Copper will have completed its "" temporary use of the land"". In the meantime, about 1250people have had employment for about 50 000 man years, at wages ranking among the best in Canada.IntroductionTo provide and sustain our way of life, we need steel, copper, aluminum, zinc and many other minerals.To sustain mining, we must have adequate ore reserves and replacement of reserves as they are mined. Each year the search becomes more difficult as more of the Earth's surface is investigated and depo sits are mined. This calls for aggressive and sustained efforts.In British Columbia, past and present mining activities have disturbed less than one-tenth of one per cent of the land.With today’s technology, mining operations can be substantially reclaimed and thus complete the cycle of ""A Temporary Use of the Land""."

Jan 1, 1992

By J. Karonen, M. Tiihonen, J. Guentner, L. Haavanlammi, Outotec GmbH, E. Kolehmainen

"Rare earth elements have obtained significant attention during the last few years due to predicted increase in their demand. Several projects worldwide are at pre-feasibility or feasibility stage aiming to commence production. Deposits of rare earth elements are typically complex and multi-metallic of nature. This means that production processes are often also complex and therefore, various metallurgical unit processes are needed. Outotec’s equipment and technology portfolio is very comprehensive and includes hydrometallurgical and pyrometallurgical apparatus and processes applicable to the efficient exploitation of rare earth deposits. Outotec has gained useful experience relevant to the processing of rare earths through several assignments including those for Alkane Resources Ltd. (Dubbo Zirconia Project), Greenland Minerals and Energy Ltd (Kvanefjeld Project), Frontier Rare Earths Limited (Zandkopsdrift project), Tantalus Rare Earths AG (Madagascar), Quest Rare Metals (Strange Lake project) and Orbite Aluminae Inc. (HPA project). The hydrometallurgical test work of two process flowsheets is presented in the paper. A roasting or acid baking step is common to several proposed rare earth projects. In the past, rotary kilns have been used, but Outotec has developed a new process concept to handle the rare earth material in fluid bed reactors. The basis for this development is long experience in fluid bed technology of Outotec in Germany. One advantage of fluid bed roasting is the higher throughput per unit. In combination with the roasting and baking, Outotec offers the gas cleaning and acid plant and provides a complete and closed concept.INTRODUCTIONRecovery of rare earth elements (REE) has obtained significant attention during recent years. It has been estimated that their demand will be boosted because of their need in many technology areas. REE can be utilized in magnets, batteries, displays, catalysts, optical devices etc. (Jordens, Cheng, & Waters, 2013; Zhang & Edwards, 2013). The production of REE is focused in China, which means that production outside of China is very scarce. However, there are multiple active development projects worldwide working towards production of REE containing products outside of China (Chen, 2011)."

Jan 1, 2016

By Kostas Fytas

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulphide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidize to produce low pH water. This acid effluent has the potential to mobilize any heavy metals contained in the rock. Coating the sulphide minerals with silicates is a new promising technology to reduce AMD. Pyrite is treated with a solution containing H2O2, sodium silicate and a buffering agent. H2O2 oxidizes a small part of pyrite producing ferric iron (Fe3+) ions. These ions subsequently react with the silicate ions to produce ferric hydroxide-silica that precipitates on the pyrite surface producing a passive coating. This silicate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that silicate coating can considerably reduce AMD.

May 1, 2001

Despite the claims of energy efficiency and the considerable development that has gone into dramatically extending rolls’ life and facilitating rolls’ change-out, in the six years since the last SAG conference, only a few HPGR operations have entered the realm of mineral processing. Risk barriers to the take-up of new equipment or processes are: a massive increase in materials handling issues as well as in the number of pieces of equipment required, low total circuit potential energy savings, and similar or higher capital costs. An alternative route is to make use of the complementary strengths of the HPGR and SAG in hybrid circuits. Minimising materials handling issues, providing an ideal balanced feed to the AG or SAG mill, and improving controllability through shifting grinding load as the RoM feed changes, are all potential major advantages to this approach. Conceptual circuit layouts, based on real measured ore and equipment data, are presented here to illustrate the potential production upside, the reduction in operating costs and the reduction in the physical and energy footprints.

Jan 1, 2012

By Jr. Santos, T. V. Pignaton, R. B. Gomides, W. Phillips, M. P. D. Gomes

Kinross Paracatu started the operation of the new gold processing plant in the end of 2008, being composed by one SAG mill and two ball mills. During the first year of operation the plant had several problems related to stability and throughput capacity, mainly due to low grinding efficiency of the ball mills. In this period many actions were taken to maximize the throughput rate. Among the actions are reducing the size of balls in the mills, increasing the ball charge in the SAG mill, changing cyclone configuration and return of circulating load to SAG mill. With better stability of the circuit, the second stage of improvements has begun with the objective of increasing throughput rate and also reducing operation costs. Among the actions are the optimization of ball charge in the mills and a better operational control of cyclone parts. After two years of operation was obtained a significant increase in plant capacity, but still requires the addition of a third ball mill in order to maximize the use of SAG mill, which has spare capacity.

Jan 1, 2012

By Guichao Wang, Geoffrey M. Evans, Graeme J. Jameson

"In this paper we present a new method for studying the detachment of particles from bubbles in a rotating turbulent eddy. The eddy is formed in a wall cavity in a two-dimensional water tunnel with transparent walls. When water flows through the tunnel, a vortical flow field develops in the cavity. The properties of the eddy can be modulated by changing the free-stream velocity of the water in the tunnel. Bubbles are pre-loaded with one or more particles in a fluidized bed flotation device located beneath the vortex cavity. Loaded bubbles are released one at a time into the cavity, and the motion of the bubbleparticle aggregate is studied using a high-speed video camera. The diameters of the particles and the bubbles, and the number of particles initially attached to the bubble, can be varied. The trajectories taken by the bubbles are quite complicated. In some cases, the bubble moves to the centre of the eddy, and particles rotate around its axis. If the rotational speed is sufficient, particles may detach due to centrifugal force. However, other modes were observed, including inertial detachment due to rapid changes in direction of the surface of the bubble, because of changes in trajectory of the bubble as a whole, or because of pulsations and oscillations of the bubble surface. Clusters of bubbles held together by particles were seen to form and reform. In the traditional explanation for the detachment of particles in flotation cells, it is assumed that particles detach from bubbles rotating in an eddy due to centrifugal force (Schulze, 1977). Although the conditions assumed in Schulze's theory may exist, it is only one of a range of phenomena that can lead to the detachment of particles from bubbles in a turbulent vortex.INTRODUCTIONThe recovery of particles by flotation methods is dependent on the particle size. The recovery in the existing flotation machines reaches a peak for particle size, typically in the range of 20 to 100 µm. This size range varies as a function of the particle’s properties (type and composites). For coarser particles, the recovery drops very quickly (Gaudin, Groh & Henderson, 1931; Jowett, 1980). If the upper size limit can be increased for flotation, dramatic savings in the grinding energy can be achieved."

Jan 1, 2016

Heap leaching accounts for around 20% of the global production of copper. In heap leaching coarsely crushed ore particles are contacted with an aqueous lixiviant percolating through large packed beds (heaps) of the ore particles, with the loaded solution collected at the foot of the heap for metal recovery, solution make-up and recycle. While dominant for copper oxide acid leaching, it finds application also in copper sulphide (bio) leaching. Despite their apparent simplicity, heaps are in fact complex chemical reactors in which a number of competing sub-processes determine the overall rate of metal extraction. Therefore, meaningful prediction of copper production rates from heaps, as well as operational optimisation and control, all hinge on a comprehensive and quantitative understanding of these complexities. The paper gives a comprehensive overview of the various sub-processes in copper heap leaching and their interactions, including those relating to mineral-particle-solution-gas phase interactions at the micro-scale bulk transport and distribution of solution in unsaturated dense beds at the macro-scale. On the basis of a more fundamental understanding and modelling, the potential for optimized operation offers new opportunities for the extraction of value from both low-grade and complex polymetallic ores. INTRODUCTION Heap leaching is one of the percolation leaching technologies, which includes in situ leaching, dump leaching, heap leaching and vat leaching (Bartlett, 1998). The common phenomenon in all these technologies is the transport of leach solution through a fixed bed of ore particles, which interacts with the solid as it migrates along its path. The target minerals are released into solution and with its flow are carried out of the bed. The targeted dissolved metal species are recovered from solution through various hydrometallurgical techniques, especially solvent extraction (SX), before the barren solution is returned to the leach process. Heap leaching is practised in three main types of applications: sulphuric acid leaching of copper oxide ores, cyanide leaching of gold ores as well as the oxidative acid leaching of secondary copper sulphide ores, usually with the assistance of certain microorganisms and, more recently, in the presence of chlorides (CaCl2, sea water). While gold heap leaching dates back to the 1960s, large scale copper heap leaching commenced in Chile from the 1980s, and sulphide heap leaching emerged essentially as a consequence of acid leaching from mixed oxide/sulphide ores from the 1990s (Watling, 2006).

Jan 1, 2019