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By J J. McEwan

Silver tarnishes readily in common atmospheres and is accelerated in humid atmospheres. Tarnish is the formation of silver sulphide on the surface of silver when it is exposed to a wide range of sulphur-containing atmospheres. Tarnish is unattractive and highly undesirable, and can be removed either with a silver polish or a chemical dip. Dips are generally only recommended when heavy black tarnish cannot be removed with a polish, and care must be taken during cleaning because these can contain aggressive chemicals and give off hazardous and unpleasant smelling fumes. Polishes work best for large areas of plain undecorated silver, and form part of a regular cleaning programme. Some polishes contain chemicals that inhibit tarnishing, but these generally only have a short life. Several methods have been developed to reduce tarnish formation on Silver; these include alloying, surface treatment, and coatings. The authors evaluated a range of self-assembled monolayer (SAM) surface treatments and coatings in earlier research. Four treatments/coatings increased the time to noticeable tarnish by more than ten fold, and the results were reported at the International Corrosion Congress (ICC) in 2005, and at the Mint Directors Conference (MDC) in 2006. SAM treatment using 95% 1-hexadecanethiol (C16H34S) was found to give good anti-tarnish performance and showed potential for the commercial treatment of Sterling silver. Therefore research was performed to optimise the methods of application of this type of coating to provide an easier, faster, and more-user friendly technique to provide an anti-tarnish treatment. Keywords: silver, tarnish resistant coatings.

Jan 1, 2006

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 a 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, optimising 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 an account of the uranium processing optimisation journey embarked on over the years; namely, the operational tradeoffs 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. Keywords: By-products, gold extraction, reverse leach benefit, uranium extraction

Jan 1, 2020

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 Mojtaba Ghorbannezhad, Abbas Sam, Soroush Arabzadeh

One of the dewatering methods in mineral processing plant is filtration system. Disk filters are included the porous surface with pressure drop on both sides, Water in the pulp passes through the surface and solid particles remain as a cake on it. Wet concentrate production of magnetite processing plant at Golgohar Mining and Industrial Company with solid tonnage of 160 ton per hour and 49% solid amount contains 166 m3/h of water. In the present study, in addition to studying disc filter performance, the effective parameters on cake moisture were studied using Vacuum Bottom-Feed Leaf method (in the laboratory scale). Optimization was performed using the Taguchi method. The results showed that the cake moisture is reduced by increasing particle size and solid percentage (because of specific resistivity reduction), while the rate of cake formation and its thickness are increased. Also, it was found that by increasing pressure, the cake moisture is reduced and cake formation rate and its thickness are increased. In this study, the effect of fabric texture was also examined. Lowest cake moisture was obtained in condition of using compressed plain fabric with mono-multi filament fibres, pressure at 75kPa, solid percentage of 65 to 70, particle size (D80) equivalent to 123µm and disk rotation speed of 1.25 rpm.

Jan 1, 2014

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 U. M. J. Boin, W. L. Dalmijn, T. P. R. de Jong

"This paper explores the complex interrelationship between the resource cycle, recycling and metal production as a function of economics, environmental legislation, and product design. It is argued that central to optimising this resource cycle lies the control in particular of physical separation plants by the application of advanced sensor technology and sorting equipment, as well as suitable control and sampling algorithms supported by optimising mass balance models.Metals are produced through a long chain of processes. For primary resources, metals production goes through mining, mineral processing, ore smelting, conversion and refining steps or via low temperature hydrometallurgical processes, or a combination of both pyro- and hydrometallurgical operations. For the recycling of resources, metals are separated and recovered from metal scrap, which plays an increasingly important role in the world. Metals after being produced, either from primary or recycling resources, have to be further refined or manufactured into various types of alloys and finally shaped into different products for the end-users. Since the end-user discards products the contained materials find their way back into the resource cycle as scrap. Therefore, controlling the metallurgical reactors also controls, in a much broader sense, the material quality in the complete metals cycle, from the production phase, to the end-use phase, up to the recycling phase (Reuter et al., 2003). The recycling phase includes separation of materials into saleable intermediate products, which are reintroduced into the production phase as a recycling resource. Therefore, the metallurgical processes in each unit operation in the metals production and processing chain have to be controlled, so as to achieve optimal performance of high product quality, low energy and materials consumption, and low environmental impact."

Jan 1, 2003

By Giannini LM, Carras S

A fundamental problem in mine planning is that of determining the "optimum pit limit" of a mine. This optimum pit limit yields information which is considered essential in the evaluation of the economic potential of a mineral deposit, and in the formulation of long -, intermediate -, and short-range mine plans. Since the mid 1960's a number of mathematical techniques based on the "block model" have been proposed for solving this problem. When applied to large ore-bodies the implementation of these techniques, especially the more elaborate ones, poses considerable computational problems. In this paper we report on our work, done jointly with Systems Research Institute of Australia (SRIA), in devising strategies for overcoming these Problems.

Jan 1, 1986

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 Yousef Ghorbani, Jafar Abdolahi Sharif, Fatemeh Kazemi, Ataallah Bahrami

Kinetic models are the most important tool for predicting and evaluating the performance of flotation circuits. Gilsonite is a natural fossil resource similar to an oil asphalt, high in asphaltenes. Here, in order to determine the kinetic order and flotation rate of a gilsonite sample, flotation experiments were carried out in both rougher and cleaner stages. Experiments were conducted using the combinations of oil–MIBC and gas oil–pine oil, with one test without collector and frother. Five kinetic models were applied to the data obtained from the flotation tests using MATLAB software. Statistical analysis showed that the results of the experiment with oil–MIBC were highly in compliance with all models. Kinetic constants (k) were calculated as 0.1548 (s−1 ) and 0.0450 (s−1 ) for rougher and cleaner stages, respectively. Rougher and cleaner tests without collector and frother also matched all models well (R2 > 0.98), with k values of 0.2163 (s−1 ) and 0.284 (s−1 ), respectively. The relationship between flotation rate constant, maximum combustible recovery, and particle size showed that the maximum flotation combustible recovery and flotation rate were obtained in the size range of −250 + 106 μm in the rougher and cleaner stages. The combustible recovery and flotation rate were higher in the rougher flotation process than in the cleaner stage.

By R. W. Sayers

The Duval Corporation porphyry copper deposits at Copper Canyon and Copper Basin, though widely separated, form an economic unit requiring integrated exploitation. Contrasts in mineralization, host rocks, and mode of occurrence present unique mining and milling problems. Mixed oxide-sulfide ore is treated in extensive dump leaching facilities in both areas. Complex copper-gold-silver ore is treated in a 4,000 tpd mill at Copper Canyon. In both areas, hypogene metallization occurs within large aureoles of metamorphism and hydrothermal alteration related to quartz monzonite intrusions of mid-Tertiary age. Supergene processes further altered the rocks and enriched the hypogene protore. At Copper Canyon, hypogene copper and iron sulfides with gold and silver occur in fractures, as partial replacement of favorable beds, and as disseminations in Paleozoic sedimentary rocks. The lower part of the Pennsylvanian Battle Formation was a particularly favorable host. Metallization occurs to a lesser extent in quartz monzonite. Metal zoning is well developed. The deposits at Copper Basin consist principally of supergene copper minerals in arenites of the Cambrian Harmony Formation. Oxidation of hypogene copper and iron sulfides in tactite zones has formed at least two commercial deposits; intersections of fractures with favorable beds exerted important ore controls.

Jan 1, 1968

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 George M. Fowler

THE Tri-State district, as outlined in this paper, refers to the entire mineralized area in southwestern Missouri, southeastern Kansas and northeastern Oklahoma (Fig. 1). The part of the district in Missouri and near Galena, Kans., is still sometimes referred to as the Joplin district (Fig. 2). The Picher-Miami area is that part of the Tri-State district located contiguously in Kansas and Oklahoma in the vicinity of Baxter Springs, Picher and Miami. This paper is confined almost wholly to the ore deposits of the Tri-State district and particularly to the Picher-Miami area. Our study of the ore deposits of this district dates from late in 1925 (by Fowler) and early in 1927 (by Lyden) to the present. Our work has been confined almost entirely to the search for ore for numerous companies and individuals. It was not possible for us to undertake numerous highly interesting investigations which presented themselves but which would not immediately help in finding ore. We particularly refer to the general structural geology of the Ozark uplift, the genesis of the ore, and other problems of a similar nature. The local and general structural problems of the district are being solved gradually as the work progresses. The factors that control the loci of the several orebodies are evident. This paper is based almost exclusively upon our own observations. Most of the important mines in the Picher-Miami area were studied in detail. A map (Fig. 5) is included which shows this area and the properties we have examined to date. When it was convenient we visited, studied and compared structural relations in numerous mines in states outside the district. Some of these observations are noted in this paper.

Jan 1, 1932

By B. Z. Wu

The ore dressing of tin-polymetallic lean ores is a difficult problem and the research emphasis in domestic nonferrous metals mining field. Through research and tackle key problem,and in order to supply reference in dealing with the same types ores, this paper expatiates the exploiture and appli-cation of six item new technology and technics in ore dressing of tin-polymetallic lean ores. It include the technics of multi-step compounding disposing tailings, grinding step by step, grinding and processing circularly technology, high thickness without circle flotation technology, dispersedly flotation tin step by step technology, exceed fine lean plumbum stibium zinc flocculation flotation technology, the synthetically recovery of waste water after ore dressing technology.

Jan 1, 2014

By Peter Joraleman

Man has always felt more comfortable breaking his life into categories or classifications. An otherwise bewildering life somehow becomes easier to bear when divided into neat measurable sections, each of which is fitted into its proper niche. It seems likely that the world's first economic geologist, when faced with the world's first two ore bodies, started his career by classifying them. Early on, he divided his ore bodies into those born of water, of fire, and of air. In retrospect this threefold classification was probably about as useful as the more complex ones that followed. This division of ore bodies probably did not help him in his search for new deposits, but it made him feel more secure in dealing with those already known.

Jan 12, 1975

The Emmaville district is located in the northern part of the New England region of New South Wales some 400 miles north of Sypney. Better known for its substantial production of tin and tungsten ores, the Emmaville district has also been the centre of a small and somewhat sporadic production of copper, arsenic, silver, lead and zinc. This production has come principally from three mines-Webb's Silver Mine, Webb's Consols and, to a lesser extent, Pye's Creek Silver Mine.The ores from these mixed sulphide deposits are texturally and mineralogically complex and the problems of beneficiation are rather formidable.GENERAL GEOLOGYThe main rock type of the Emmanville district is a dark, brown to blackish massive siltstone of Permian age which overlies acid volcanics possibly also of Permian age. In places the siltstone gives way to conglomerates and standstones with discontinuous lenses of calcareous sediments (David, 1887).The whole series is folded but because of the massive character of the more expansive siltstone, detailed structure is difficult to delineate.Toward the close of Permian time the area was intruded by a series of intermediate to acid plutonic and hypabyssal rocks. Mineralization within the region is ascribed to the more acid of these intrusives-granodiorite, granite, and quartz-felspar porphyry (Lawrence, 1957, 1960).No intrusive rocks outcrop in the immediate neighbourhood of Webb's Silver Mine though granite occurs two miles...

Jan 1, 1961

By Henry Newton

IT may seem somewhat a work of supererogation to present to the American Institute of Mining Engineers, composed largely of gentle- men with whom the subject is so familiar, a paper on iron ores and their distribution. To many of them, however, it possibly will not be without interest, as there may be some, like myself, who hare nowhere found a connected account of the character of the deposits and the circumstances upon which are founded the great iron-producing centres of the world. This blank I have endeavored to fill,

Jan 1, 1875

By F. L. Clerc

THE lead and zinc region of SW. Missouri is interesting, not only by reason of the value of its output, which ranges in the neighborhood of ten million dollars a year, but even more because of the facilities which it offers for the study of certain forms of ore-deposits, of which the loci and genesis are somewhat obscure. Although the mineral species found in the region are few and of common occurrence, crystallization has taken place on a generous scale, and unusual forms abound in many combinations, presenting examples of pseudomorphism, paragenesis, metasomatic replacement and the action of mineral-depositing and mineral-dissolving waters. For the mineralogist, lithologist, and specialist in certain lines of metamorphism, it has peculiar attractions, while the systematic geologist will perhaps find its chief claim to attention in the simplified problem it presents, in the study of ore-deposits. In addition to the phenomena above enumerated, it presents instances of well-developed comb-structure in the ores, fissures and faults, and slickensides-features usually associated with extensive movements in the earth's crust, and believed by some authorities to prove the deep-seated origin of the ores. In connection with these occurrences, the absence of all igneous rocks from this region is noteworthy and significant. For that reason, the simplified case presented by the Joplin region, from which these rocks have been eliminated as a factor, is specially valuable. Having had unusual opportunities to watch the development of this district, I have been deeply interested in the bearing of the revelations of the Joplin mines upon questions of universal importance to the science of ore-deposits ; and it was to my great regret that the project of a meeting of the American Institute of Mining Engineers at Joplin, proposed in 1892, was

Mar 1, 1907

By Richard Hunt

BINGHAM has produced 6 per cent. of this country's copper. In total production, it ranks fourth among the copper camps of North America, the order being Butte, Michigan, Bisbee, and Bingham. In its annual production, it held that same rank until 1919, when its production was exceeded by the combined production of the Globe-Miami district of Arizona. Bingham has also been a lead camp of the first order. Utah ranks third among the lead-producing states, and its production comes largely from three camps which, in the order of their productivity, are: Bingham, Tintic, Park City. Bingham's silver production is important, but it does not rank high as a silver producer. Utah owes its rank as first among the silver-producing states to Tintic, a camp 40 miles due south of Bingham. The United States Mineral Resources reports a total production from Bingham for the period 1865-1920 having a gross value of $528,043,432. Bingham is on the eastern flank of the Oquirrh range 30 miles south-west of Salt Lake City, from which it can be reached in an hour by auto, or by the Denver & Rio Grande or the Bingham & Garfield railroads.. The automobile route is a paved road across the floor of Great Salt Lake Valley, through farming country. The Bingham & Garfield railway leaves the level of Great Salt Lake at the northern end of the Oquirrh range, and in 20 miles it climbs 2100 ft., and deposits the traveler upon a shelf cut in the side of Bingham Canyon below most of the mines, which are farther up Bingham Canyon and its tributary Carr Fork. Below lies the town, a narrow ribbon running for a couple of miles along the bottom of a canyon 2000 ft. deep-an almost impossible site for a community numbering, in prosperous times, 5000 to 7000 inhabitants drawn from all quarters of the globe. Up the canyon and down, and beneath the steep slopes nearby, and beneath the town itself, are the mining operations of over half a century.

Jan 3, 1924

By M. Springett

Organization of teams for rapid and effective evaluation of international mining properties requires special considerations beyond those needed for domestic activities. Experience, technical ability, a sense of perspective, humor and self-discipline are vital characteristics to look for in the selection of individuals for forming an efficient and productive team.

Jan 1, 1994