Search Documents

By Wei Wang

The SMCO copper plant is located in DR Congo, and was designed by China NERIN Engineering Co., Ltd. The process is a typical hydrometallurgical plant with Leach-SX-EW, with the project treating the oxide minerals with agitation leaching, followed with three stage of solvent extraction and two stages of stripping, and using permanent SS cathodes to produce LME grade copper. Because of the special characteristic of the ore, what contains 2 different type of oxides (one high carbonate oxide and the other low carbonate), there are several new technical measures that have been developed and adopted for the plant. For example, different grinding, leaching, and filtering are used to treat different oxides. This paper, presents the project process, engineering design, construction and commissioning. The paper also describes some of the problems encountered during plant commissioning, such as the agitation leaching tank issues, and corrosion in the settler-mixer. This paper discusses some NERIN solutions to these problems, and explains the use of the CN filter, which is used to filter PLS to treat high level suspend solids, instead of the traditional sand filter. Finally, this paper also proposes steps / measures for further improvement for future plant operation.

Jan 1, 2014

By Walter Greaves

THIS paper describes a series of tests performed at the Hollinger mill during the past four years, in which both metal and rubber-lined pumps were used for pumping sand and slime. While conditions will not be the same at other mills, it is felt that the information gained from the tests should be of value to other operators and of assistance to them in selecting the most efficient size of pump and kind of lining for economical operation. For the successful operation of pumps with rubber linings there are certain conditions, which, if recognized at the outset, will save the operator a good deal of work and trouble. First is the necessity of keeping sharp pieces of steel, or anything that might cut the lining, out of the pumps. This can be effected by placing screens in the proper locations. Second is to recognize the fact that the rubber lining of the shell, and the rubber cover of the impeller, are subjected to very different conditions. The shell lining, :being at rest and well supported by the metal case, has a relatively easy job compared ? with the impeller covering, which is subjected to centrifugal force and has a tendency to tear itself away from the metal core. Also, the pulp travels through and past the impeller at a high velocity. These two factors, centrifugal force and velocity of the pulp, would appear to set a limit to the speed at which, for a given set of conditions, it is economical to run a rubber-covered impeller. Therefore, a pump should be large enough for the work to be done. To get the best mechanical efficiency, it must be operated somewhere near the limit of its capacity, but this may not give the best overall cost, because the saving in power, due to the high efficiency, may easily be lost through excessive wear on the lining. It would appear that this condition is more critical in a rubber-lined pump than in one lined with metal.

Jan 1, 1939

By D. W. Euler, D. G. Brophey

"In an attempt to address the issue of rising labour costs, and to improve productivity, a laser-based system to guide underground LHDs and trucks has been developed. This comprehensive system is known as the Opti-Trak system.Essentially, the vehicle is equipped with front and rear-mounted lasers which scan a reference strip mounted on the drift back. The vehicle follows this reference strip and in addition, based on reflective bar codes mounted beside the reference strip, initiates certain functions (i.e. dump cycle, speed change, brake check, etc.). Any programming that is drift-specific is handled by the positioning of the reference strips and bar codes. Consequently, the vehicle can easily travel to many different haulageways or branches, providing the reference strip and bar codes are in place.The advantages of this system are an immediate elimination of haulage operator costs and an increase in available hauling time to 7 hours out of an 8-hour shift as compared to the typical 5Y2 out of 8 hours that a manned haulage system offers.This paper describes the Opti-Trak system and the benefits to be realized from automation of mine haulage requirements."

Jan 1, 1994

By Daven N. Compton

The optical properties of Au nanoparticles have been known for some time, with both Au colloids and Au nanoparticles embedded in glasses having been extensively studied. In this study, Pt nanoparticles have been incorporated into Au colloids, and the linear and non-linear optical properties investigated. UV-VIS spectrophotometry, fluorescence spectroscopy and the z-scan method have been used to examine the effects of such additions.

Oct 1, 2003

By J. Someehneshin

Nowadays along with population growth, industry development, consumption of mineral resources and the fact that the reserves on hand are running out, the depth of surface and underground mines for further exploitation are increasing. During recent years, in underground mining, the block caving method for low-grade and large-scale deposits has shown a growing rate of application. This method is very cost effective and economically affordable. The dimensions of blocks are one of the most important parameters which should be taken into account since it has been proved to have a great deal of effect on technical issues such as commencement of caving and mine design. Proper calculation of the length and width for a block in this method leads to proper caving and discharging which are the most important stages. Therefore, in this method, the calculation of the optimized dimensions (length and width) of blocks is not only important but also directly helps the productivity of extraction. In this study, firstly for the purpose of facilitation, some assumptions were considered and having used these assumptions for estimation of optimized length and width of block, a relationship based on rock mechanics and physics was explored. Furthermore, some necessary details were added to the said relationship and finally, it was transformed into an inequality. Solving this inequality provides us with the optimized length and width of the block. The explored relationship was analyzed with MATLAB software and the graphs thereof were drawn. In these graphs, each time one of the input parameters has been drawn up in a logical range so that it could be compared with previous states.

Aug 1, 2013

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimizing the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give account of the uranium processing optimization journey embarked on over the years; namely, the operational trade-offs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper.

Jan 1, 2020

By Larry G. Twidwell, Corby G. Anderson, Camille M. Fleuriault

"The selective precipitation of iron as ammonium jarosite is a well-established industrial technology in base metals hydrometallurgy. It is a key technology in minimizing iron tenors which would be disruptive to downstream processing. It also provides a more readily filterable iron solid to better facilitate materials handling. This paper elucidates the fundamentals behind industrial iron precipitation. Then, the details of the successful optimization of an industrial ammonium jarosite circuit are presented.HYDROMETALLURGICAL IRON REMOVAL FUNDAMENTALS Iron is the fourth most abundant element in the Earth’s crust (5% by weight) and is often found in complex ores such as sulphide-bearing formations. Iron represents an issue though during leaching, a technology which is widely used for the treatment of this type of ore: •,Iron has the particularity of forming hydroxides when leached under certain conditions. Iron hydroxides form a viscous gel, which is difficult to filter and traps valuable elements such as silver. •,Iron is solubilized along with other metals and interferes with the subsequent extraction steps. As a result, purification of the pregnant leach solutions is required to achieve economical extraction of base metals. In the 1960s, metallurgists developed iron precipitation processes for solution purification (Habashi, 1999). Nowadays, precipitation of iron bearing species, such as goethite, hematite or jarosite, has become one of the most common methods used in the industry to purify leach liquors. To be suitable, the precipitate has to be readily filterable and thus must not be too fine of particle size. Precipitation can take place in autoclaves at medium to high temperatures, under an oxygen or air overpressure (Tourre, 1984, Fleuriault 2016, Fleuriault Anderson Shuey, 2016))."

Jan 1, 2016

By M. B. McClenaghan, O. P. Lavin, Ian Nichol

"Abstract-Exploration in most areas of Canada has to contend with problems posed by glacial overburden. In many areas exploration for gold has been based on the sampling of tills, frequently by deep overburden drilling, and analyses of heavy mineral concentrates. Notwithstanding the significant role that till geochemistry has played in the discovery of some important gold deposits over the last few years, increased appreciation of the nature of the glacial history and stratigraphy and the character of gold within till has led to the recognition of a number of ways whereby the effectiveness of exploration can be improved upon.In order for till geochemistry to be useful in exploration, a number of conditions must be fulfilled, including:1. mineralization, or alteration halo related to mineralization, subcropping at the bedrock /over­ burden interface; 2.glacial erosion and dispersal of a recognizable signature of mineralization into the glacialsediments; 3, preservation of glacial sediments containing this geochemical component (trace metal or mineral) at positions subsequently selected for sampling (normally drill sites); 4. correct identification of specific till units and associated ice movement history; 5. collection of adequately large and representative samples; 6. appropriate sample preparation and processing; 7, appropriate geochemical analyses; and 8. correct data processing and interpretation.While we have no control over the first two geological conditions, and only limited controlover till availability, we can control the quality and thoroughness of sampling, sample identification, sample preparation, analysis and interpretation. In particular attention needs to be focussed on obtaining a large enough sample to be adequately representative, an unbiased sample must be collected, together with appropriate sample processing, analysis, data processing and interpretation. It is considered that by modifying or extending existing approaches to gold exploration the chances of exploration success can be increased. In particular, analyses of both the heavy mineral and minus 63 ?m fractions of till is recommended because gold in till may occur in different size fractions."

Jan 1, 1992

By M. B. McClenaghan, O. P. Lavin, Ian Nichol

"Exploration in most areas of Canada has to contend with problems posed by glacial overburden. In many areas exploration for gold has been based on the sampling of tills, frequently by deep overburden drilling, and analyses of heavy mineral concentrates. Notwithstanding the significant role that till geochemistry has played in the discovery of some important gold deposits over the last few years, increased appreciation of the nature of the glacial history and stratigraphy and the character of gold within till has led to the recognition of a number of ways whereby the effectiveness of exploration can be improved upon.In order for till geochemistry to be useful in exploration, a number of conditions must be fulfilled, including:1. mineralization, or alteration halo related to mineralization, subcropping at the bedrock/overburden interface;2. glacial erosion and dispersal of a recognizable signature of mineralization into the glacial sediments;3. preservation of glacial sediments containing this geochemical component (trace metal or mineral) at positions subsequently selected for sampling (normally drill sites);4. correct identification of specific till units and associated ice movement history;5. collection of adequately large and representative samples;6. appropriate sample preparation and processing;7. appropriate geochemical analyses; and8. correct data processing and interpretation.While we have no control over the first two geological conditions, and only limited control over till availability, we can control the quality and thoroughness of sampling, sample identification, sample preparation, analysis and interpretation. In particular attention needs to be focussed on obtaining a large enough sample to be adequately representative, an unbiased sample must be collected, together with appropriate sample processing, analysis, data processing and interpretation. It is considered that by modifying or extending existing approaches to gold exploration the chances of exploration success can be increased. In particular, analyses of both the heavy mineral and minus 63 µ m fractions of till is recommended because gold in till may occur in different size fractions."

Jan 1, 1992

By A. Mazhary, T. Huff

Sensor-based ore sorting technology is a growing area of interest due to lower-grade ore deposits and higher costs of processing, among other reasons. Among the sensors currently utilized in the particle sorting industry, X-Ray Fluorescence (XRF), as the only sensor with elemental analysis capabilities, has always attracted more attention. Currently, the bench-scale amenability tests for this sensor are performed using hand-held XRF analysers. However, this testing method overestimates the performance of the XRF sorter, and therefore, the results from these tests can be misleading and are often mispresented. The work presented here was conducted on a copper mine and investigates how the sensor’s sensitivity to copper deteriorates under different testing methods. This work compares and correlates the results of an Olympus hand-held XRF analyser, static, and dynamic sorter responses with the actual grades of the rocks. The results confirmed that, the sorter response was extremely prone to blind spots. Furthermore, the results demonstrated that although the static sorter’s responses were comparable in terms of rock identification to those of the hand-held XRF analyzer and assays, the accuracy of the dynamic sorter response deteriorated both as a function of grade of the rocks as well as the potential for blind spots. INTRODUCTION Sensor-based sorting technology has been gaining increasing attention even by larger mining corporations as ore grades decrease, deposits get deeper and therefore cost of mining and processing increases. There are various types of sensors that are currently being used in the particle sorting industry such as X-Ray Transmission (XRT), Color, Electromagnetic (EM), Near-Infrared (NIR) and others. However, none of the sensors are capable of identifying and quantifying particles by the elemental content, except for X-Ray Fluorescence (XRF). XRF is a non-destructive, surficial analytical technique used to measure elemental composition of materials. X-ray fluorescence happens when a secondary x-ray (fluorescence) is released after a sample is bombarded by a primary x-ray source. From a sorting perspective, the most common and expected issues that are associated with XRF sorting are lower throughputs compared to other sensors due to particle presentation limitation as well as the need to wash the material before introducing to the sorter. However, one important issue that is mostly neglected is how the amenability tests are performed and how realistic the obtained results are. Current amenability test procedure utilises a handheld XRF analyser (such as an Olympus InnovX, as used in this work) on multiple, generally 4, sides of the rock and uses the average measured grade as a criterion for separation. While this is a widely accepted technique, it fails to consider some important factors such as exposure time and the distance between the sensor and the particle. These factors can significantly affect the sorting outcome.

Jan 1, 2019

By Steve R. McCutcheon, Cees R. Van Staal, John P. Langton, Leslie R. Fyffe

Abstract -The volcanic-dominated Tetagouche Group in northern New Brunswick contains numerous massive-sulfide deposits and intimately associated metalliferous sediments. The massive sulfides are generally hosted by Llanvirnian-Llandeilian volcaniclastic sedimentary rocks of the Nepisiguit Falls, Patrick Brook, and Boucher Brook formations. These formations are intercalated or closely associated with rhyolitic-dacitic flows and/or domes, and minor continental tholeiites of the Flat Landing Brook Formation. Pyroclastic rocks are relatively scarce in the silicic volcanic complex. Tuffites and epiclastic sandstones, of the Nepisiguit Falls and Patrick Brook formations, respective­ ly, generally occur along the fringes of the silicic volcanic complex. The flows and tuffites are intruded by quartz- and feldspar-phyric rhyolite (porphyry) dykes, sills, and domes. Although the volume of the silicic volcanic complex is large, evidence for a previously proposed collapsed-caldera model is lacking. On the basis of host-rock type and stratigraphic position, the sediment-hosted massive sulfides have been divided into three groups: the Brunswick-, Caribou- and Halfmile Lake-type deposits. Syngenetic feeder pipes and asociated alteration zones are generally not present beneath the Caribou- and the Halfmile Lake-type deposits and, if present at all, are poorly developed underneath the Brunswick-type.

Jan 1, 1992

By Steve R. McCutcheon, Cees R. Van Staal, John P. Langton, Leslie R. Fyffe

The volcanic-dominated Tetagouche Group in northern New Brunswick contains numerous massive-sulfide deposits and intimately associated metalliferous sediments. The massive sulfides are generally hosted by Llanvirnian-Llandeilian volcaniclastic sedimentary rocks of the Nepisiguit Falls, Patrick Brook, and Boucher Brook formations. These formations are intercalated or closely associated with rhyolitic-dacitic flows and/or domes, and minor continental tholeiites of the Flat Landing Brook Formation. Pyroclastic rocks are relatively scarce in the silicic volcanic complex. Tuffites and epiclastic sandstones, of the Nepisiguit Falls and Patrick Brook formations, respectively, generally occur along the fringes of the silicic volcanic complex. The flows and tuffites are intruded by quartz- and feldspar-phyric rhyolite (porphyry) dykes, sills, and domes. Although the volume of the silicic volcanic complex is large, evidence for a previously proposed collapsed-caldera model is lacking. On the basis of host-rock type and stratigraphic position, the sediment-hosted massive sulfides have been divided into three groups: the Brunswick-, Caribou- and Halfmile Lake-type deposits. Syngenetic feeder pipes and asociated alteration zones are generally not present beneath the Caribou- and the Halfmile Lake-type deposits and, if present at all, are poorly developed underneath the Brunswick-type.

Jan 1, 1992

By Paul Billingsley

NICKEL Plate mountain coincides closely with that portion of the Hedley mining district which is of economic interest. From it has come almost the entire past production, and the active mines of the present epoch, Nickel Plate-Sunnyside and Hedley Mascot, lie in a compact group near its summit. The Hedley district, which is 210 miles due east of Vancouver, is situated in the Okanagan range of southern British Columbia, where this rather gentle uplift is deeply dissected by the canyons of the Similkameen and its tributaries. The region is essentially part of the Interior Plateau of the Province (Figure 1), but is adjacent to easterly elements of the Coast Range. The Similkameen canyon, 4,000 feet in depth and frequently less than 4 miles from rim to rim, traverses the district from northwest to southeast. The deepest and narrowest portion of the canyon lies between Hedley and Keremeos, 18 miles to the southeast. At Hedley, an important tributary, Twenty Mile creek, enters from the north in a bold canyon, making a focus of unusually rugged topography. Nickel Plate mountain occupies the sector to the east of this junction (see Figure 2) and its flanks are ringed by the cliffs of Twenty Mile canyon on the west and by those of the Similkameen canyon on the south. On the east, it slopes gently to the hanging valley of Eighteen Mile creek, and on the north, with only slight loss of elevation, it merges into the moderately hilly surface of the plateau.

Jan 1, 1941

By François Robert, Rex Brommecker, Don S. Bubar

"The Orenada Zone 4 deposit is a small vein-type gold deposit occurring directly within the Cadillac Break southeast of Val d' Or in southeastern Abitibi Sub province. Mineralization is hosted by the Piche Group which, on the Orenada property, consists of talcchlorite- carbonate, chlorite-carbonate, and sericite-chlorite schists, derived from ultramafic volcanic, mafic igneous, and intermediate to felsic volcaniclastic rocks, respectively. All these rocks have been carbonatized.Rocks of the Pichi Group display a strong east-west, subvertical S1foliation, which is superimposed by asymmetric, intrafolial F2folds with shallow to moderate plunge to the east and to the west. F2folds are accompanied by an S2, subvertical axial planar cleavage, and are interpreted to result from dextral transcurrent shearing along sr.The Zone 4 deposit occurs within a large F2 fold, 60 m wide and plunging at 45 to the east, down to a depth of at least 300m. The auriferous zones consist essentially of zones of closely spaced, parallel quartz-tourmaline-albite-carbonate-arsenopyrite veins concordant to Sr these veins have been folded by the large F2fold and may pre-date the folding. A few discordant quartz-tourmaline-arsenopyrite veins, post- dating the F2 folding, also contain gold. Wallrocks adjacent to concordant veins have been carbonatized, albitized and contain significant amounts of tourmaline and arsenopyrite, with which gold is intimately associated.The Orenada Zone 4 deposit is a unique example of a deformed vein- type gold deposit, and exemplifies one of several types of association of lode gold deposits with folds."

Jan 1, 1990

By H. Helmstaedt, P. Thurston, R. Harrap

"Evolution of the continental lithosphere over Earth’s 4.6 billion year history is one of the fundamental questions of geoscience. Much of the Earth’s present-day continental crust formed during the first 2 billion years, the Archean eon, of the planet’s lifetime and thus, Archean processes of lithospheric formation must be studied in order to address this question. Until recently, the processes of Archean lithospheric evolution were thought to be fundamentally different from present-day plate tectonic processes. However, subsequent evidence suggests that the growth of Archean continents may be explained in terms of modern tectonic accretionary tectonics similar to those presently operating in the southwest Pacific region. The evidence supporting this hypothesis was compiled largely by Canadian geoscientists working in the Superior Province of the Canadian Shield in northwestern Ontario, over the past 15 years. Study of Archean rocks is also economically important because the Archean rocks of the world, although comprising only a relatively small fraction of the exposed continental crust, contain much of the world’s mineral wealth, including more than half of the world’s gold, as well as significant base metal reserves. Furthermore, the vast majority of primary economic diamond deposits are derived from the lithospheric roots beneath Archean cratons.The LITHOPROBE Western Superior Transect is located within the western part of the Superior Province in northwestern Ontario (Fig. 1). The Superior Province is the largest and best exposed Archean crustal block in the world and forms the nucleus of the North American continent. The internal structure of the Superior Province records a history of the processes that formed the earliest lithospheric elements of the Earth into cratons, thus providing an ideal laboratory for investigating early crustal evolution. The Western Superior Province is characterized by a regional pattern of alternating, 100 km to 200 km wide geological belts (Fig. 2). The observed geologic relationships between and within these subprovinces have been explained in terms of a modern tectonic model of terrane accretion. Oceanic floor, volcanic island arcs, oceanic sediments and continental fragments were accreted successively from north to south against the southern margin of a cratonic nucleus (North Caribou terrane, Fig. 2) which grew steadily in size with the arrival of new terranes through geologic time. If this model is correct, it suggests that the tectonic processes operating today have been active without major variation over the past 3 billion years."

Jan 1, 1998

By V Dolmage

Copper Mountain is the third largest copper mine in British Columbia, and is now producing close to 20 million pounds of copper per year, with which is recovered also 4,000 ounces of gold and. 13,800 ounces of silver. After a long and checkered career, during which the ownership and management changed several times, this deposit finally came into the possession of the Granby Consolidated Mining, Smelting and Power Company in 1923. It was not, however, until the end of 1925 that the mine, under the management of Charles Bocking and C. H. Smith, was successfully placed on a basis of profitable production. It is a low-grade deposit of the contact-metamorphic type, with refractory ores consisting of chalcopyrite and bornite in a gangue of altered andesitic and basaltic breccia. The ore is concentrated to a product carrying over 30 percent copper, which is smelted in Tacoma. The deposit is 12 miles south of the town of Princeton, which is on the Kettle Valley railway, 150 miles east of Vancouver and 40 miles north of the International Boundary line. Princeton is served also by a branch of the Great Northern railway, which leads clown the Similkameen, Okanagan, and Columbia valleys. Copper Mountain mine and camp are connected to Princeton by a good mo tor road extending up Wolf Creek valley, while the haulage level of the mine, which emerges on the steep side of the Similkameen valley 1,000 feet below the camp, is connected with Princeton by a spur of the Kettle Valley railway leading up the Similkameen canyon and passing en route through Allenby, where the concentrator is situated.

Jan 1, 1929

By F. Habashi

The pioneer work on pressure hydrometallurgy was conducted in Russia at the end of the nineteenth, and the beginning of the twentieth centuries, by Karl Josef Bayer (1847-1904) and Vladimir Nikolyevitch Ipatieff (1867-1952), both working independently in Saint Petersburg. Bayer was studying pressure leaching while Ipatieff was studying the precipitation of metals and their compounds by hydrogen under pressure. Gradually, industrial applications took place first in the aluminium and later in the nickel industry. Today, the technology is well established in a large number of industries, such as uranium, gold, zinc, titanium, tungsten, and more recently copper.

Jan 1, 2004

By J. E. Dutrizac, J. B. O'Reilly

"Zinc is a relatively abundant element which occurs as both high-grade sulphide ores {sphalerite ZnS) and oxide ores which the ancients collectively termed ""calamine"" (smithsonite ZnC03 and/ or hemimorphite Zn4Si201(0H)2 - H20 and/ or hydrozincite Zn5(C03) 2(0H)6). Although oxidic zinc is readily reduced by carbon, the process becomes thermodynamically viable only at - 1000°C, and at this temperature the zinc is released as a vapour (B.P. 907°C). Casual cooling of the vapour results in its re-oxidation by excess combustion air or even the carbon monoxide product of the reduction reaction. ZnO + C = C09,, + Zn vapom Only fairly rapid quenching of the zinc vapour and the isolation of the reduction products from the combustion gases will yield metallic zinc; these conditions were not produced deliberately until the advent of distillation technology. Until quite recently, the principal use of zinc was in brass manufacture; galvanized iron was not discovered until the 19th century and zinc casting alloys are a relatively recent invention. As will be seen, brass could be produced without recourse to a pure zinc intermediary, and the discovery of brass preceded that of zinc by many centuries. The purpose of this paper is to outline the discovery and early development of both zinc and brass with special reference to the European scene."

Jan 1, 1999

By D. R. Lentz, S. H. Mcclenaghan, J. A. Walker

"Abstract - The Orvan Brook deposit is one of several (Zn+Pb>>Cu)-rich sulfide deposits hosted by the Spruce Lake Formation (California Lake Group) in the northwestern part of the Bathurst Mining Camp. This parautochthonous deposit is hosted by a narrow band of highly deformed, locally graphitic shale that appears to conformably overlie felsic volcanic rocks of the Spruce Lake Formation, and is in tectonic contact with overlying mafic volcanic and related sedimentary rocks of the Canoe Landing Lake Formation. The Spruce Lake Formation is dominated by felsic volcanic rocks and subordinate fine-grained sedimentary rocks, and mafic volcanic rocks (Canoe Landing Lake member). The felsic volcanic rocks can be divided into aphyric and feldspar-phyric rock types. The feldspar-phyric rocks and a few of the aphyric varieties have a Zr/TiO2 ratio of 0.06, and fall into the California Lake Group field on a Y/TiO2 versus Zr/TiO2 diagram. In contrast, the aphyric felsic volcanic rocks have Zr/TiO2 ˜ 0.09 and are marked by high Zr and Th, which is consistent with highly fractionated felsic magma of Spruce Lake affinity. Major and trace element analyses of host rocks suggest that weak to moderate hydrothermal alteration developed on the south side (stratigraphic footwall) of the deposit, which is consistent with a north-younging succession. The sulfide lens strikes east-west for approximately 2.3 km, extends down-dip for at least 500 m locally, and has an average thickness of between 0.75 and 1 m, but is locally up to 5.5 m thick. The contacts of the massive sulfide lens with its host rocks are invariably sharp. Host rocks show evidence of intense ductile deformation as well as later brittle deformation. Compositional layering and sulfide breccia textures in the sulfide body are interpreted to result from deformation or tectonic enhancement of original primary layering. The deposit contains an estimated resource of 2.69 Mt grading 1.73% Pb, 5.95% Zn, 0.37% Cu, 72 g/t Ag, and 0.9 g/t Au. Similarities in bulk d34S between the Orvan Brook (+8.6‰) and the nearby Cu-rich McMaster deposit (+8.2‰) suggest a common depositional setting."

Jan 1, 2006

By E. Barnard, J. Tero, J. Rajala, N. Avenido, M. Fullam, A. Nashitati, S. Mbalamba

"The Otjikoto mining and milling complex is 90% owned by B2Gold Corporation, and began commercial operation on February 28, 2015. The milling circuit operates at a throughput 3.3 million tonnes per annum, with an average reserve gold grade of 1.28 g/t. The ore is high in Gravity Recoverable Gold (GRG), which varies between 73-91%, depending on ore type. Overall gold recovery since start-up is 98.2%, with about 63.5 % coming from the gravity circuit as doré. 2016 cash operating costs, and all in sustaining cost (“AISC”) were $361 and $604 per ounce, respectively.During design, three ore types were tested for GRG content, and based on the high GRG value of all three ore types, the decision was made to treat the full ball mill circulating load by gravity. Once operating, the gravity circuit performance was characterized by performing a detailed gravity audit, which included the ore, cyclone classification, Knelson concentrators, and the Consep Acacia intensive leach system. The deeper ores contain significant pyrrhotite, and this created some unusual challenges that had to be overcome. This paper presents the gravity circuit design process, the circuit commissioning, and the audit results and ongoing improvements.IntroductionHeadquartered in Vancouver, Canada, B2Gold Corp. was founded in 2007. Currently, B2Gold has five operating mines, and numerous exploration projects in various countries, including Nicaragua, the Philippines, Namibia, Mali and Burkina Faso. The Otjikoto Mine is located in the north-central part of the Republic of Namibia. It is situated approximately 300 kilometers north of Windhoek, the country’s capital, within the Province of Otjozondjupa. The Otjikoto mining and milling complex is 90% owned by B2Gold Corporation, and began commercial operation on February 28, 2015. The milling circuit operates at a throughput 3.3 million tonnes per annum. During design, a large emphasis was placed on gravity recovery, as the Otjikoto ores are unusually high in Gravity Recoverable Gold (GRG)."

Jan 1, 2018