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By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By Y. C. Kim

The results from a retrospective study are described in this gaper in which she past development drilling activities were investigated using geostatistics. The purpose of the study was to determine the amount of savings in drilling cost that could have been realized through the optimal placement of sequential drill holes using geostatistics. Out of 144 DDH's that were in place within the study area, the results showed a possible elimination of 34 DDH's without any reduction on the confidence interval of the global reserve estimates. If the incremental savings from one drilling campaign to the next were considered, however, the amount of percentage savings were even greater. Other interesting results from this study were; 1) tangible demonstration of the importance of a proper geologic delineation within the study zone, and 2) the robustness of the obtained experimental variograms from the rather early stage in development drilling.

Jan 1, 1981

By F. L. Bazzanella

Cyprus Pima has two concentrators, one with a conventional crushing-grinding circuit and the other using semi-autogenous grinding followed by ball mills.

Jan 1, 1978

By S. M. Bradshaw, E. Charikinya

"Microwave induced cracks have the potential to enhance metal recovery from coarse sphalerite particles in heap leaching operations by creating new crack surface areas for lixiviant and enhancing value mineral exposure. The mode of fracture and the extent of mineral exposure due to microwave induced cracks have not yet been investigated. The objective of this study was to determine the extent of particle damage and mineral exposure in microwave treated particles. This was done using X-ray computed tomography (XCT) and image analysis techniques. XCT analysis was conducted on small (–5+4.75 mm), medium (–16+9.5 mm), and large (–25+19 mm) sphalerite ore particles before and after microwave treatment (MT). Geometrical properties, such as volume and surface area of each mineral phase in each particle was determined from the XCT reconstructed images using VGStudioMax image analysis software. These geometrical properties were used to calculate the interfacial areas of sulphide mineral grains in microwave treated particles before and after MT. The ratio of specific interfacial area after MT to specific interfacial area before treatment was used as an indicator of the degree of preferential grain boundary fracture. The results showed significant grain boundary fracture after MT at all sizes. For small sized particles, about 31% of the interfacial area was lost compared to 23 and 16% for medium and large particles, respectively. The results also showed an increase in the degree of mineral grain exposure of 28, 26, and 15% for small, medium, and large particles, respectively, after MT. These results provide experimental evidence supporting improved mineral exposure due to MT. INTRODUCTIONFor some years it has been suggested that microwave treatment (MT) of ores might result in preferential grain boundary fracture that would have benefits such as improved grain exposure and particle weakening. (Kingman, 2006). Most of the experimental work investigating the application of microwaves to mineral processing flow sheets has focused on assessing the benefits of applying microwave technology to flow sheets consisting of size reduction and mechanical flotation cells (Kingman et al., 2004). Experimental studies have shown that coarse crushing during tertiary grinding of microwave treated ore resulted in a better liberated coarser flotation feed (Scott, Bradshaw, & Eksteen, 2008). It has been suggested that improved liberation in milled flotation feed, was due to the presence of grain boundary fracture in microwave treated particles. However, this improvement in coarse particle liberation does not necessarily translate to a significant improvement in downstream flotation recovery (Kobusheshe, 2010). This is as a result of the size limit to the flotation of coarse material, due to detachment forces acting on particle-bubble aggregates, which increase as the particle size increases (Jameson, 2012). Current conventional, mechanically agitated flotation cells are not designed to float coarse material (Jameson, 2012). Hence it has been difficult to show the downstream processing benefits of applying microwaves to ores processed by comminution followed by flotation (Kobusheshe, 2010). It is clear from investigations carried out so far that inappropriate downstream exploitation of microwave treated ore would fail to realise a meaningful process benefit (Kobusheshe, 2010; Ali & Bradshaw, 2011)."

Jan 1, 2016

By D. J. Bowen

"Abstract -The Great Dyke extends for 540 km along strike, to unknown depth, and varies in width from 3 km to 11 km. Rb/Sr age determinations gives values of approximately 2470 Ma.The Dyke consists of a variety of mafic and ultramafic rocks, many altered to serpentinites. These include, from top to bottom, successions of gabbro/norites, pyroxenites, peridotites/harzburgites, and dunites/picrites.The layers dip in from either margin, steepest at the edges (20°) and flattening toward the central sections. Four separate complexes are present. From north to south these are termed the Musengezi, Hartley, Selukwe and Wedza Complexes, and are described as 'boat-shaped' or 'pig-troughed'. All are similar in petrological sequences. Physiographically, the Dyke is spectacular in the north, where as a mountain range it meets the Zambezi Escarpment. Elsewhere in the central parts there is little surface expression and wide open treeless vleis. Dyke rocks cut through granite and schist belt terrain and are termed 'The Magnesia Belt'.Vast mineral resources exist. These include chrome, asbestos, platinoids, nickel, copper and gold. Up to eleven chrome seams numbered from top to bottom occur in the lower ultramafic sequences. Seams are narrow at 10 cm to 30 cm but of high grade. The platinum occurs 10 m to 40 m below the norite/pyroxenite contact.A 60 m wide zone of Light Sulfide Mineralization (LSM) of Jess than 1% sulfides extends from the lower gabbronorites into the upper pyroxenites. In this LSM, four enriched zones carry up to 5% sulfides. The most widespread is termed the Main Sulfide Zone (MSZ), below which is No. 2, No. 3 and No. 4 Sulfide Zones. The MSZ carrying pyrite, pyrrhotite and chalcopyrite is a multi­ element ore with components of PGE (Pt-Pd-Rh), nickel, copper and cobalt, and gold and silver.Extensive exploration programs have been carried out and the intention is to begin large-scale mining. However, with Russia supplying metals to the western markets, South Africa's cutback on production, and an end to the Cold War, delays have arisen."

Jan 1, 1994

By R. F. Hammen

Heavy metal contamination of water is a problem of immense national and international proportions. However, effective cleanup is complicated both by the toxicity and the low concentrations of metals in wastewater streams. Using high performance chelation chromatography, the solid phase extraction and purification of extremely dilute metals from water was highly effective. The process is based on selective displacement of metals from a chromatographic column containing a chelating resin. The resin is characterized by extremely efficient adsorption kinetics which allow rapid and complete removal of the metals.

Jan 1, 1993

By J. D. Zetterstrom

This report supplements an earlier publication on lightweight aggregates of North and South Dakota.3/ The purpose of the investigation was (1) to study the expansion characteristics of large samples of Dakota clays and shales in a 12-inch by 15-foot rotary kiln; and (2) to improve the laboratory bloating test as a tool for predicting the suitability of samples for the rotary-kiln process. This was done by comparing results of the laboratory and kiln tests.

Jan 1, 1956

By V 9. 0 / 300 dpi

ATHOUGH turquoise mining was, so far as we know, the first large, well-organized mining operation,' gem mining, from the Roman con-quest of Egypt until the opening of the South African pipe diamond mines some 50 years ago, was largely carried on' by individuals 01' small companies in a relatively primitive way. Now" however" gem mining does not yield in efficiency or in scale of operations to the mining of other mineral products. In 1926 the diamond mines of the world milled some 9,000,000 cu. yd. and produced 0,43 cu. yd. diamonds, a remarkable example of concentration. The Premier Diamond Mining Co. up to Oct. 31, 1927, had milled 116,455,550 loads (each of 16 cu. ft.) from which 26,-217,144 carats of diamonds" worth £29,897,971 2s, 9d., were recovered. The Burma Ruby Mines, Ltd., operating sever-al alluvial mines in Burma in 1911-12, mined and milled 1,479,845 truckloads of gemmiferous earth for 15c. per load. We of the industry can there-fore, with good grace, disclose some of the myths and also describe some of the primitive mining methods of the, dark ages of our industry. The methods, so far as I know, were not patented, and if they were, the patents have expired, so that engineers in other branches of the art are free to use them if they see fit.

Jan 1, 1928

By Ellis S. Hertzog

The data published in this retort cover only one phase of a special study of tile physical and chemical properties s of only Alabama coals made by the Bureau of Mines. In addition to determinations of friability, the survey included determinations of grindability, B.t.u. value, and ash-fusion temperature. Assay distillation tests, both for high- and low-temperature carbonization, and proximate and ultimate analyses were made also. However, this preliminary paper is concerned only with the results of friability tests and is issued to expedite the release of this information to the public. The friability, test measures the liability of a coal to break into smaller pieces when subjected to repeated handling, as occurs in the mining, preparation, and transportation operations. Friability depends on many physical characteristics of the coal that vary not only between different seams but also in the same seam. The laboratory methods of determining friability have been developed to give a practical means of estimating degradation of size. So far as is known to the authors, no data on the friability of Alabama coals have ever been published. This caper makes available for the first time fairly comprehensive3 information on this subject. Because the procedure for the tumbler test for determining the friability of coal is relatively new to the coal operators, the authors Lave included a, complete description of it in this report.

Jan 1, 1938

By S. V. Balikov

A close association of fine gold with pyrite and arsenopyrite is observed at many gold ore deposits. Gold forms and gold distribution in sulfides of different deposits were studied. A comprehensive method including optical spectrum analysis, X-ray diffraction analysis, high-temperature X-ray diffraction analysis, scanning electron microscopy and X-ray microanalysis was used for the de-tailed investigation of the defectiveness of the structure of pyrites from different deposits. It was shown that gold content in pyrites varied from 1.5 g/t to 100 g/t compared with 30 g/t to 230 g/t in arsenopyrites. The nature and arrangement of inner inclusions of foreign minerals in pyrites as well as occurrence of fractures and macro- and microdefects were examined. Iron, sulfur and arsenic contents in all pyrite samples were determined. Chemical composition of the detected inclusions was defined. Parameters of submicroscopic structure of pyrite were estimated using X-ray Fourier line shape analysis. Estimation of real structure characteristics with calculation of submicroscopic D-blocks and root-mean-square lattice deformation 2()evalues was performed. Defectiveness of the pyrite structure can be defined by the following parameters: K?1 and K?2 reflection resolution and its intensity within high Bragg angles; S content to Fe content ratio; the arsenic content and the local variation in its concentration within the pyrite grain; the size of submicroscopic blocks and the crystal lattice disturbance value. The performed analysis showed some relationships between these parameters and refractoriness of the pyrite concentrates. It was observed that at S/Fe ratio close to or higher than stoichiometry and at a low arsenic content (less than one per cent) pyrite concentrates were not refractory. The analysis results showed that concentrates of the Beryozovskaya gold plant (0.02~0.07 As%) and concentrates of the Kommunarovskaya gold plant (less than 0.05 As%) as well as some pyrites from the Sukhoi Log gold deposit had the same characteristics. It was found that average arsenic content did not excess 0.2 per cent. Arsenic distribution within the grain of all these pyrites was uniform. At S/Fe ratio lower than or close to stoichiometry and at high arsenic content (more than one per cent) and significant variation in its distribution within a pyrite grain the pyrite concentrates are refractory. Such pyrites are typical for the Sukhoi Log, the Bakyrchik and the Mardzhanbulak gold deposits. Direct correlation between arsenic and gold contents, in particular, in fine grains of pyrite was observed by many researches. This correlation was explained by impregnation of arsenopyrite which normally contains more gold than arsenic pyrites. The analyses results showed that no arsenopyrite impregnation was found: arsenic distribution within the grain was uniform but its concentration varied greatly. Such pyrite concentrates are more refractory. This paper presents the results of analyses of sulfides to determine the amenability of the associated gold recovery by hydro- and pyrometallurgy.

Jan 1, 2014

By D. Berberick

On January 5, 2012, the Mine Safety and Health Administration ordered the closure of the Silver Shaft, the primary underground access to Hecla?s Lucky Friday Mine, for removal of built up backfill material that accumulated over time on the shaft walls and furnishings. Lucky Friday and Cementation USA personnel worked quickly to identify the most effective means to get the mine back into production. The team developed a fast-track procurement and refurbishment plan utilizing shaft sinking winches, headframe modifications, a partial shaft sinking Galloway, and modified cages to not only complete clean-off of buildup, but also replace pipe brackets, shaft steel, and power and communications cables as needed in the 1,860 m (6,100 ft) deep shaft within 14 months.

Feb 23, 2014

By A. R. Chambers

At the 1924 Annual Meeting of the Institute, held in Toronto, the writer presented some notes on the occurrence of salt at Malagash, Nova Scotia, together with a few remarks on the uses of salt. The development of these salt mines has attracted considerable attention to the district, and it may be of interest at this time to call attention to some of the newer uses of salt, and to give a brief account of the genesis of the Maritime salines, As it is not proposed to treat the subject in technical detail, and the paper is written in a lighter vein than is usual in contributions to your Transactions, you will please overlook any variations from a strictly technical method of presentation. The world's supply of salt is obtained in three principal ways: (1) By flooding shallow areas, or pans, with sea water, allowing the water to evaporate naturally by the heat of the sun's rays, and collecting the residue of solid salt. This method is employed, for example, at Turks Island, B.W.I. (2) By mining the rock salt in its natural state, and preparing it for market by a grinding process. This is the method adopted at Malagash, which is the only place in Canada where salt is actually mined. (3) By drilling a hole into an underground salt deposit, forcing fresh water clown the hole, and, after it has become saturated with salt, pumping the brine to the surface and recovering the salt by evaporation. This is the method pursued by the Canadian Salt Company, the Dominion Salt Company, and other producers in Ontario.

Jan 1, 1929

By Ahmad Ghahreman, Denver Cowan, Yeonuk Choi

"Previous testwork by the authors has indicated that both granular coconut shell based activated carbon and a new microporous carbonaceous bead, Lewatit® AF 5, are highly effective in improving the oxidation kinetics and decreasing the elemental sulphur yield when assisting the atmospheric oxidation of pyrite. While the two carbon catalysts show similar results and improvements to the pyrite oxidation, there are differences between them. For example, the activated carbon assisted oxidation showed faster kinetics than the AF 5 assisted oxidation, while elemental sulphur seemed to remain adhered to the surface of the AF 5 after oxidation when much of the elemental sulphur formed during the activated carbon assisted tests was found in the oxidation residue. The objective of this paper is to investigate the differences between the two catalysts through the use of scanning electron microscopy, photography, Raman spectroscopy, surface chemistry analysis, and Brunauer-Emmett-Teller (BET) surface area analysis. With this investigation the authors should be able to achieve a better understanding of the surface chemistry of the two carbon catalysts (i.e. functional groups, charges, acidity etc.) and help explain the strengths and/or the weaknesses of the catalysts when applied to the atmospheric oxidation of pyrite.INTRODUCTION Previous research conducted by the authors, indicated that both a granular coconut shell based activated carbon (activated carbon) and a microporous carbonaceous bead, Lewatit® AF 5 (AF 5), acting as a catalyst enhanced atmospheric pyrite oxidation in ferric sulphate media by approximately 40% when compared to unassisted oxidation and that elemental sulphur yields were increased from 23% to approximately 69 and 63% when assisted by AF 5 and activated carbon respectively (Cowan, Jahromi, & Ghahreman, 2017). The study indicated that although total pyrite oxidation assisted by the two catalysts was similar, differences were noticed in the impact that the two catalysts had on the outcome of the oxidation. Kinetic curves in the Cowan et al. study indicated that atmospheric oxidation of pyrite seemed to reach completion after 48 hours of oxidation when assisted by activated carbon. A similar trend was noticed in the kinetic curves for oxidation when assisted by AF 5, however the oxidation curve did not reach completion until approximately 96 hours (Cowan et al., 2017). This observation indicated that the kinetics of pyrite oxidation are enhanced by both catalysts, oxidation kinetics are much faster when assisted by activated carbon rather than AF 5."

Jan 1, 2017

By V Novoselov, R Sabirov

Flotation processing technology of water-soluble minerals has made it possible to realise, since the 1960s, the wide scale industrial processing of potash and potassium-magnesium ores (about 200 million tonnes per year) as well as to create the multi-tonnage worldwide production of sylvite (KCl) for industrial and agricultural application. In this paper the particularities of the effect of reagents (blinders, collectors and frothers) during cation flotation in saturated saline solutions are outlined. New reagent modes for activating the effects of alkylamines during the flotation of KCl and the perfecting of technological flow sheets for processing potassium ore have been developed. The results of research on the reverse flotation of carnallite ore, with the help of alkylmorpholine û a new developing technology for benefication carnallite as raw material for the production of metal magnesium and fertilisers are listed. Examples are given of the industrial applications of processed reagent modes at potash flotation factories in Russia.

Jan 1, 2005

By Linlin Zhang

Rare earth elements (REEs) are a group of lanthanides elements which have been widely used in the electronic, petrochemistry, metallurgy, and defense industries. Their demand has increased sharply in the past decade with the boom in electronic device production. Some countries now consider them strategic metals for the future and it has been forecasted that REEs may become a dominant contributor to global economy. In the wake of REE exploration, mining and processing, concern has grown over occupational and community health issues and risks. A portion of available literature on this topic however is written in the Chinese language, and thus research information related to health and REE mining is not readily accessible to mineral development planners in countries such as Canada, where REE mining is now evolving. As REEs also represent an important commodity, primarily stemming from Chinese production, it is important to begin to understand the potential health costs related to this mining sector. There are two main objectives of this paper. The first is to present an overview of REE mining with a focus on geological characteristics, global production and uses with particular attention to the main producer: China. The second is to present the results of a literature review (using both Chinese and English sources) on REE mining and health and identifies key occupational and community health issues that require consideration. This paper concludes by identifying some critical issues this sector needs to address to ensure the sustainable development of this mining activity.

Aug 1, 2013

By P. J. Coleman

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners? activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly under-stand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985.

Jan 1, 2010

By O. Durand

The Cerro Verde Hydrometallurgical Plant, located at Arequipa in the southern part of Peru, started its operation in 1977 with a design capacity of 33,000 MT/year of copper cathodes. The plant has treated 61,055,000 MT of ore mainly oxides with a content of 1.01% total copper and 0.67% of soluble copper. The leaching plant has three pads that produce 4.0 gpl copper solution. The solvent extraction plant has four trains with three extraction stages, two stripping stages with a single mixer in all stages. The mixer-settlers are 316 stainless steel and the pumps are vertical turbines. The flowrates of 1,300 gal/mil of aqueous and 1,300 gal/min of organic at a 1/1 ratio. The electrowinning plant contains 208 commercial cells and 18 starting sheet cells. Each cell has 47 anodes and 46 cathodes. In addition to describing the hydrometallurgical plant, this paper also mentions efforts directed at reducing costs and improving operations. The initial results from leaching secondary sulfides, which started October 1985, are also discussed.

Jan 1, 1987

By N McKenzie, E Taylor, S V. L Barrett, H Lagger, A Purwodihardjo

This paper discusses the temporary support design methodology for the largest road caverns ever built in Australia—the Lutwyche Caverns—part of the Airport Link project in Brisbane, Australia. The Lutwyche Caverns with a maximum excavated span of 27 m form a key component of this major road project, allowing on and off ramps merging with the underground highway. In addition to the two large span caverns, a 15 m soft ground tunnel with 5 m cover above the caverns and two 24 m deep burial chambers for the 12.4 m tunnel boring machines (TBMs) had to be built in record time at Lutwyche.The temporary support design methodology involved the use of a range of analytical approaches, including empirical methods to provide a starting point for design development, key block models to determine the potential influence of discontinuities on excavation stability and 2/3D continuum and discontinuum models to determine the potential influence of adjacent excavations and the proposed construction staging on the design. In addition, probabilistic analysis of potential kinematic instability using a discrete fracture network (DFN) approach was also undertaken to establish the critical block loads for the temporary lining, while the continuum and discontinuum models were used to design the support for the 1.5 m diameter rock pillar at the north end of the northbound cavern.The numerical modelling was undertaken in close conjunction with the contractor to develop the optimal construction sequence, considering the available construction equipment on-site and the overall project program requirements. Part of the presentation will further show the applicability of the developed design during construction (deformations, monitoring field observations) and lessons learned for future cavern construction in Australia.CITATION:Lagger, H, Purwodihardjo, A, Barrett, S V L, McKenzie, N and Taylor, E, 2014. Temporary support design for the largest road caverns ever built in Australia – the Lutwyche Caverns, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 399–410 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By R. A. Matuszak

Throughout the history of power excavating machines, engineers have continuously tried to shape the main drive speed-torque characteristics to provide an optimum performance from each main motion. Selection of prime mover for the various motions has been the subject of many engineering studies and most forms of energy conversion have been tried. A new form of electrical power conversion looms on the horizon' as the most optimum yet. Controlled frequency operation of a squirrel cage induction motor increases the reliability of the most reliable form of energy conversion (electrical) found thus far and at the same time improves the performance characteristics.

Jan 1, 1977

By B. Waterman, D. Ramey, L. Schlink

"Water is a primary commodity for most industrial processes. It has become a global focus in light of climate change and population growth. Reuse of process water has two major benefits - minimize the amount of fresh water added now and minimize the amount of discharge water that requires treatment later.Mining and mine product processing has its share of reused water. For example, reclaim water from a tailings impoundment, overflow from thickeners and leach solution to raffinate and back again all demonstrate the use and reuse of water in mining circuits. Eventually, a mine reduces production or ceases operations completely, eliminating the option to reuse the impacted water and, thus, requires treatment of the remaining water.Current methods of water treatment remove the impacts, providing clean water for discharge, but leaves behind a concentrated waste that requires further treatment or disposal of a hazardous waste. Freeport- McMoRan is currently testing three water treatment technologies specific for sulfate and/or metal removal from mine impacted water with the approach of transformation not concentration. These technologies provide clean water for alternative use while creating byproducts that could be marketable, or disposed as a nonhazardous material, thereby reducing the cost and longterm liability of disposal.The selection of a water treatment process is site-specific. The volume of water, contaminant to be removed, disposal options, length of time for treatment, location of plant and reagents and discharge requirements are some of the factors that need to be considered when selecting a water treatment process. Common water treatment technologies for mine impacted water consist of low- or high-density sludge (LDS/ HDS), reverse osmosis (RO) and evaporative technologies. In addition to operating costs, these processes require additional handling of the concentrated sludge or brine. Advanced water treatment technologies include ion exchange, solvent extraction and metals precipitation with or without the aid of a biological system. Some of the more complex systems have a series of unit operations to achieve required discharge regulations."

Jan 1, 2014