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By G. Markopoulos

Thracean Gold Mining is a Greek Company specialized in gold exploration and exploitation. It is focused on the development of the advanced Perama Hill gold project, which is currently waiting approval of the environmental terms of reference from the Ministry of Environment. We have designed a mine operation that is completely safe environmentally. The mine design exceeds all the standards environmental safety set by the European Union. We are currently negotiating lasting relationships with the communities which surround the mine by creating sustainable projects within the area that will provide sources of income to the region long after the mine is exhausted.

Jan 1, 2007

By James Parkes

"The proposed Baltimore Red Line light rail system includes a 3.4 mile downtown tunnel (DTT) with five underground stations. The design of the underground stations involved overcoming several challenges, including limited right-of-way, high groundwater and uplift pressures, and metamorphic rock within the station depths. An innovative design was developed to maximize the internal station space while minimizing cost. The station designs use slurry walls for temporary and permanent support and groundwater control. Depths within rock are supported with cast-in-place concrete walls, the thickness of which are minimized through the use of permanent rock anchors for support of the rock mass and slurry wall toes. Permanent tiedown anchors are used for uplift resistance, which minimizes the station depths, volume of rock excavation, and the volume of deadweight concrete. Design considerations regarding individual elements and overall integration of the slurry walls, CIP walls, and multiple anchor types are presented.INTRODUCTION The Baltimore Red Line (BRL) project is a proposed light rail transit line for the Maryland Transit Administration (MTA) that runs east to west through Baltimore City and County. The project includes the Downtown Tunnel (DTT) consisting of 3.0 miles of twin running tunnels, two portals, five underground stations, and a pedestrian tunnel, as shown in Figure 1. The tunnels have an outside diameter of 21.8 feet and are designed to be mined using pressurized face tunnel boring machines (TBMs). The stations, portals, and the pedestrian tunnel are designed as cut-and-cover structures using slurry walls (concrete diaphragm walls) for both temporary support of excavation (SOE) and permanent structural walls. The dimensions of the five underground stations are summarized in Table 1. Design challenges included limited right-of-way (ROW), challenging soils conditions, strong metamorphic rock within the station depths, and high groundwater conditions. The final station designs included innovative use of slurry walls, tieback anchors, rock anchors, and tiedown anchors."

Jan 1, 2016

By J. C. Stankus

Accurate evaluation of stress and geological conditions is critical to ground control design in underground openings. For a slope entry, the problem is more difficult because a slope will transverse through many different types of strata. Over the past three years, Keystone Mining Services, LLC, an affiliate company of Jennmar Corporation, has developed a new methodology designated the ?Stress, Geologic, and Support Design System (SGSsm)?. This patent pending method analyzes the stress, geology, and support design for a mine slope. It has been successfully applied in various new slopes across the United States. This paper will detail the main concepts of the methodology including: (1) Analysis of stress and geology and identification of strong, fair and weak zones along the slope; (2) Primary and supplemental support design; (3) Long term support design in the form of steel square sets or arches, and (4) Validation of the support design utilizing advanced finite element computer modeling.

Jan 1, 2011

By Fergusson E.

An account is given of the history and operation of the Straits Tin market and the Penang price. The procedure by which the official ruling tin price is determined is presented and the way in which bids are treated is outlined: the price declared in Penang is the result of a joint operation by the two Malaysian smelters and is arrived at by finding the highest price at which the whole of the day's offerings for sale can be sold, thus reflecting the marriage of the offerings of the individual mine producers with the demand for Straits Tin from the consuming countries of the world. A system of accurate weighing, sampling and assaying of concentrates delivered to the smelters' premises enables the various ore-buying agencies of the two smelters to notify their central offices promptly of the estimated tin content of the concentrates their customers wish to price that day, so that by 11.00 a.m. both smelters will have exchanged with each other figures giving the total quantity of metal they have for inclusion in the day's market, at the same time exchanging particulars of the bids they have received. Miners are encouraged to sell regularly for cash and an evenness is thus achieved which avoids large daily fluctuations in overall quantity.

Dec 30, 1971

By L. M. Cumming

"The contact between dolomite of the St. George formation (Cambro-Ordovician) and limestone of the overlying Table Head formation (Middle Ordovician) is a regional disconformity. This is best illustrated from exposures on Pointe Riche Peninsula, near Table Point, and along Port au Port Bay. The contact occurs along 180 miles of the west coast of Newfoundland from St. John Island in the north to the western part of Port au Port Peninsula in the south. A disconformity of the same age occurs between the Romaine and Mingan formations on the north side of the Gulf of St. Lawrence.Dolomitic beds beneath the disconformity locally contain concentrations of base-metal sulphides. Sphalerite occurs in dolomite pseudobreccias of the St. George formation at Zinc Lake, 7 miles northeast of Daniels Harbour. The 'Western Newfoundland Lower-Middle Ordovician regional disconformity is interpreted as having originated on and near the edge of a broad platform, and to have provided an important regional geological control in the localization of zinc mineralization."

Jan 1, 1968

By H. H. Schrenk, L. B. Berger, W. P. Yant, F. A. Patty

"The use of small such as canaries and white mice, for detecting carbon monoxide depends primarily on the fact that the volume of respiration of these animals in proportion to their volume of blood is much higher than for man. Accordingly, when animals and men are simultaneously exposed to a given concentration of carbon monoxide the animals will absorb it more rapidly and attain serious poisoning in less time than men. Prom a practical viewpoint the use of the animals depends on the margin of time between observable symptoms in them and serious poisoning in man, during which man can return to fresh air or use respiratory protection. It should be remembered, however, that during the time the animal is incurring a detectable degree of poisoning, man is also absorbing some carbon monoxide, and the margin of time is not very wide. Experience with canaries has shown that an occasional specimen may have a tolerance above the average of the species and fail to exhibit symptoms before man incurs a very discomforting and possibly a serious degree of poisoning.It is also well known that physical activity increases the demand for oxygen by the body, and the respiratory exchange and circulation of the blood are increased to meet the demand. This sets up a vicious condition if carbon monoxide is present in the air because the rate of absorption of carbon monoxide is not only increased by the increase in respiration and circulation, but the absorption of carbon monoxide decreases the capacity of the blood for carrying oxygen at a time when the demand is high. These facts, together with the increase in respiration and circulation which attend excitement, underlie the caution to be calm and to walk slowly and to reduce physical exertion to a minimum when exposed to carbon monoxide. For these same reasons, when using animals for detecting carbon monoxide it is endeavored to keep them active, thereby tending to increase the response of the birds and widen the time between observable effects in the birds and effects in the man. As rule canaries are kept fairly active through fright at the unnatural surroundings and in their endeavor to remain on the perch of the cage when carried into the atmosphere to be examined. They also experience an excitement stage with oncoming carbon monoxide poisoning. Sometimes, however, especially if the air is cold, they tend to be inactive and quiet. Ordinary mice and white mice become inactive with use and also with oncoming poisoning. They huddle in the corner or the cage, and thereby not only reduce their sensitivity but make it difficult to observe signs of poisoning."

Oct 1, 1930

By Hamid Maleki

A novel ground control program has been developed at Plateau Mining Company through five years of geotechnical investigations. The study was initiated to determine the causes for roof stability problems and to develop alternative support and monitoring systems for increased safety and productivity. From systematic roof fall observations, extensive geologic mapping, roof drilling and monitoring ground movements along gate entries of four longwall panels, a sand- stone channel system was detected and shown to impact roof stability. In particular, underlying mudstones up to seven feet thick experienced instability due to differential compaction and load transfer from the gob. Roof bolter operators were trained to report roof lithology for mapping channel positions into the roof and for selective use of longer bolts. This boosted operator morale, and improved ground conditions. Monitoring rates of roof movement is used in these areas for detection of instability and for application of secondary support: This has significantly increased safety and productivity.

Jan 1, 1987

By V. L. Gravitis

Radioisotope X -ray techniques of analysis for nickel have been tested in laboratory and plant trials. In the laboratory tests. a comparison was made of radioisotope and conventional analyses for nickel in solid s samples taken from streams of a nickel concentrator. Coefficients of variation of 1.7% for feed and concentrate samples , and equal to 10% for final tailing samples, were obtained. Continuous determination of nickel in final tailing slurries was demonstrated in a trial lasting 20 days at a nickel concentrator (Western Mining Corporation), nickel being determined with a standard error of 0.036% Ni in the slurry solids within the range of 0.24 to 0.68% Ni. This error, obtained by comparison of on-stream probe analyses with assays of samples taken from the stream, includes errors in sampling and assay by conventional techniques.

Jan 1, 1977

By G. Gabra, M. Nagamori, J. J. Panneton

"RESUMELa calcination contrôlée de 10 serpentine permet de produire de 10 magnésie active. Le degré de I'activation est mesure par 10 solubilité du magnésium dans les acides faibles tel que I'acide acétique, La serpentine contenue dans les résidus d'amiante du Québec peut donc être activée par calcination. Le teneur en magnésie active des rejets d'amiante calcinés est fonction de divers paramètres: température, temps de calcination, granulométrie, etc. Les rejets d'amiante de différentes provenances démontrent des comportements thermochimiques différents qui sont étudiés dans Ie présent travail au moyen d'ATD, de TG, de la diffraction des rayons X et de la lixivation par l'acide acétique. On constate qu'un maximum d'environ 80% de la magnésie totale peut être activé dans certains rejets d'amiante du Québec et Ie degré d'activation dépend de la provenance.vIntroductionOn sait depuis longtemps que la serpentine, Mg3Si2O5(OH)4, un silicate hydroxylé de magnésium, devient amorphe lorsqu'elle perd de I'eau d'hydratation entre 600 et 700 °C. La serpentine ainsi calcinée est alors dissociée en magnésie et en silice. Cette magnésie, dite active, est soluble dans un acide faible ou même dans les solutions de sels d'ammonium.Plusieurs precédés chimiques ont été proposés afin d'extraire sous forme de composés magnésiens la magnésie de la serpentine. La plupart de ces procédés comportent une activation par calcination de la serpentine préalablement à une Iixiviation par un acide ou par une solution d'un sel d'ammonium.Malgré la contamination par Ie fer et par d'autres éléments, les compositions chimiques des rejets de différentes mines d 'amiante du Québec, présentées au tableau 1, sont très proches de la serpentine typique. Puisque Ie degré d'activation de la magnésie varie grandement d'une serpentine à I'autre lors de la calcination, la première étape de la recherche sur la transformation chimique des rejets d'amiante du Québec se résume à une étude de leurs comportements thermochimiques."

Jan 1, 1982

By J. H. Hedges

During the World War Leadville was an important producer of manganese and maganiferous ores for then steel industry. Normally, the market for these ores is limited to the requirements of the local steel mill at Pueblo for low-grade ores used in making, basic pig iron containing 1 to 2 percent Mr and spiegoloison containing 20 percent Mn, but during the war and a brief period of postwar readjustment, a good deal of 25- to 40-percent manganese ore qua shipped to in-stern steel-manufacturing centers. Throughout the active life of the camp, manganiferous iron ore carrying a little silver and lead and sometimes as such as 35 percent Mn was chipped to load smelters for flux. The total reordered production is 936,024 tons of metallurgical ore shinned to steel mills and 2,576,514 tons of fluxing ore, much of it of metallurgical grade.

Jan 1, 1940

By Detlef Sulzer, Winfried Rosenstock

"At the end of this century a great breakthrough in the field of blasting technology is finally going tobecome reality. That, in the true sense of the word, is the long expected and desired “HighTechnology Blasting”. So far trials have been carried out in Australia, Africa and Europe with remarkable results, that have been predicted by the authors. As a result, significant reductions of explosives and drilling expenditure are emerging for the future."

Jan 1, 1999

By Woods PW

Consulting Engineers have been used in the mining and metallurgical industries for many years. The traditional role of the consultant overseas has been one of assisting with conceptual design right through to con- struction and commissioning as well as on occasion acting solely in specialist fields. This role developed because mining companies wished to concentrate on building up the permanent organisation they require to operate their mines and treatment plants without the traumas of increasing staff for the design and construction period and reducing it on completion. In Australia where there have been few individual minerals projects of magnitude (until recently) companies have looked after their own detailed engineering and construct- ion management employing consultants mainly in specialised fields.

Jan 1, 1975

By R. V. Ramani, W. Miola

"A relationship exists between the quartz contents in the underground coal nine airborne dust samples and those in the coal and host rocks that are mined [17, 18, 19] The prescribed method for quartz analysis in respirable airborne coal dust samples is the MSHA P-7 method. Accurate quartz analysis procedures are needed for bulk samples in order to predict the potential quartz content in airborne nine dust, which in turn will aid the design of quartz dust control procedures during mining. thereby reducing the airborne quartz dust in underground atmospheres. The requirements of this method are that the amount of quartz is the sample be less than 250ug, and the total sample weight less than 2,500 ug. Unlike with airborne dust samples, there are no limitations to the available mass of bulk samples. However, these are no standard procedures for the preparation of bulk samples for scanning or prescribed methods for quartz analysis. The NIOSH and MSHA methods are certified for roped* dust and the acceptance of these methods for bulk samples assumes that the bulk samples will be reduced to the conditions specified for respirable dust samples. An alternative method is X-ray diffraction, which provides higher average quartz values than those obtained from P-7 method for the same samples.An investigation was carried out to determine the optimal procedure for preparing the bulk samples for the IR and XRD analyses. In this paper, the investigations on the effects of calibration, particle sizes, matrix composition, interferrous, and behavior of the filter substances on IR, XRD and FTIR results are presented. The error introduced by the presence of kaolinite and a new sample asking procedure to reduce it are discussed. The problems experienced with conventional sample holders for scanning were eliminated with the design and development of a new hollow sample holder. Quantitative comparison of quartz determinations by IR, XRD and MR methods on coal, roof and floor rocks, and airborne dust samples are presented. The important factors affecting the results of quartz analysis methods are: 1) bulk sample preparation for obtaining representative and homogeneous analysis samples: 2) particle size distributions of the analysis samples and calibration standards; 3) qualitative matrix composition of the analysis sample; 4) matching calibration standards to analysis sample; 5) substrates for sample deposition during analysis sample preparation; 6) procedures for analysis sample mounting; 7) selection of proper portions of she response profile for insanity measurement; and 8) interferences of spurious phases with the critical analyses. The recommendations of this study are important to enable comparisons and interpretations of analysis and research results."

Nov 1, 1995

By S. du Plessis

Nationalization is high on the policy agenda in South Africa. This paper considers the case for nationalizing the local mining sector from an evidence-based perspective, which is derived from theoretical considerations and related to the known features of the South African mining sector and economy. A strong case against nationalization emerges, which can be summarized as follows. The mining sector is competitive and therefore a poor candidate for public ownership. Furthermore, the resources sector does not dominate the South African economy nor does it create the risk of a decrease in the competitiveness of the industrial sector via the unintended adverse impact of an appreciating real exchange rate due to a commodity boom (Dutch Disease). Nationalizing the mining sector will cost the government more than it receives. This is not only a bad idea in itself, but it will limit the scope for distributive policies on the national budget. The contemporary international experience demonstrates the risks of fiscal imprudence. Finally, nationalizing the resources sector will undermine support for those very market-based institutions required to achieve a higher long-run growth trajectory.

Jan 1, 2013

By A Harburg, A Dendys, G Green

Dugald River Mine (DRM) is located approximately 85 km north-east of Mount Isa, and 65 km northwest of Cloncurry, in the north-west Queensland Minerals Province of Australia. DRM is an underground operation and includes an above ground processing area, a 200 ha tailings facility, two waste rock dumps and associated infrastructure. The mining method is conventional underground longhole open stoping and downhole benching of a lead/zinc deposit within a black slate environment. The deposit is estimated to contain ~53 Mt of zinc and lead, which will be mined over a 30-year period. During operations, waste rock is segregated into either Potentially Acid Forming (PAF) or Non-Acid Forming (NAF) based primarily on the sulfide concentration of the rock. In particular, the NAF waste rock is an asset and is used for various small construction projects during operation; however, its primary use is for rehabilitation work at closure. Since beginning operations in 2017, DRM has generated more NAF than was originally anticipated. Whilst this is an excellent asset to DRM, it did pose a logistical problem of where to store the additional NAF for the life-of-mine and how to manage the run-off. DRM experiences distinct wet and dry seasons with hot conditions and periods of rainfall between November to April, and relatively dry and mild conditions between May to October. Majority of rainfall is received between January and February with an annual average rainfall of 501.1 mm. Short and intense rainfall events are common. DRM’s above ground infrastructure is land-locked between two large ephemeral watercourses, making the significant expansion of any assets challenging from a permitting/regulation and cost perspective. MMG is also a member of the International Council on Mining and Metals (ICMM) and is committed to adapting to a changing climate through operations and closure. Following extensive studies DRM opted to store the additional NAF material into the adjoining NAF Dam and concurrently upgrade a previously minor sediment basin into a highly engineered sediment basin which relies on automatic flocculant dosing to meet the required discharge quality limits. This basin is climate-resilient in that the dosing system can be adjusted to counter high intensity extended rainfall events which produce highly variable inflow water quality. This abstract broadly describes how DRM designed and implemented an engineering innovation to enable the site to meet the changing climatic challenges. The abstract then describes the process to design the sediment basin and how the dosing rate was established and validated. Finally, the abstract comments on the effectiveness of the sediment basin and how it has revolutionised DRM’s approach to water treatment and management; all whilst minimising the disturbance footprint of the operation

Aug 2, 2023

By James A. Finch

The Gaudin lecture is devoted to fundamentals. Given my involvement with column flotation over the last 20 years, this is my topic. I have tried to identify spinoff basic research and provide a personal list of favorites. Two are selected for discussion here. They are single bubble rise and bubble surface area flux. The rationale for such work, as well as some of the findings, are reviewed. Support for fundamental work seems as volatile as the economy (and the link is probably not coincidental). I hope some utility to the minerals industry is evident in the text. Column flotation in its current form originated in the early 1960s. The method was invented by Boutin, patented by Boutin and Tremblay and pursued doggedly by Wheeler. Their aim was to overcome the problem of mechanical entrainment of fine particles in the water carried by the bubbles, which they were convinced contributed to lowering flotation concentrate grades (Wheeler, 1988; Finch and Dobby, 1990). The solution was a combination of columnar geometry, the addition of wash water into a deep froth and the maintenance of an excess of water to the tailings, as compared to the feed (a so-called positive bias). Success at Les Mines Gaspe, Quebec, on cleaning Mo in the early 1980s signaled the start of industrial acceptance, making the column one of the flotation machines of choice today. Over the next 20 years, column applications mushroomed to cover virtually all mineral commodities, as well as nonmineral applications such as soil decontamination, deoiling of water and deinking of recycled paper. In the wake, research groups are continuing to probe the fundamentals, conferences and workshops have been transferring the technology and specialist companies have emerged to service the demand. Innovations were triggered as problems arose (for instance, in gas injection systems) and novel flotation cells, much in vogue in the 1990s, had the door opened. Mechanical cell manufacturers have not been idle - there is nothing like competition to provoke a fresh look at an established business. Flotation-cell technology has probably not seen so much activity since the patent rush in the early days of flotation, which occurred around the turn of the century. For an industry often considered reluctant to risk innovation, this is not a bad record. A good idea will find a place, but patience (not always an innovators strong suit) and careful preparation are required. Two books (Finch and Dobby, 1990; Rubenstein, 1996), three symposia (Sastry, 1988; Agar and Huls, 1991; Gomez and Finch, 1996), and a series of reviews (Dobby and Finch, 1991; Finch and Dobby, 1991; Finch, 1995; Finch et al., 1995) document the period. Like many good ideas, column flotation has been overexposed, and there have been disappointments. In a recent example, columns performing scavenging duty were replaced by mechanical cells (Chong et al., 1998). The further applications stray from the original - to

Jan 1, 1999

By L. A. Neumeier

The Bureau of Mines evaluated the properties of zinc alloys containing 25 to 40 wt pet Al and 0 to 0.7 pet Mg. Microstructures, hardness, and tensile properties were evaluated for material as extruded at 285° C, solution treated at 300° to 400° C, and subsequently aged at 100° to 200° C. The alloys without magnesium are characterized by low hardness and strength with high tensile elongation and reduction in area. It was verified that magnesium effectively retards the Zn-Al eutectoid transformation below 275° C and markedly increases hardness and strength with decreases in ductility. Solution treating at 350° C results in large grain sizes and gross embrittlement. Subsequent aging of the Zn-Al-Mg alloys at 200° C restores ductility substantially and stabilizes the structures, but strengths are considerably reduced. Combined strength and ductility properties are better for the as-extruded condition than for any heat-treated condition. There is usually little advantage in overall tensile properties from increasing magnesium above 0.1 pct.

Jan 1, 1971

By Y Peng, B Guo

In gold processing plants, the water from the cyanidation stages is treated to detoxify cyanide species and this recycle water becomes the main part of the process water. Despite the low concentration of free and weak acid dissociable (WAD) cyanides in process water, the recoveries of gold and silver is still affected during flotation, especially when gold and silver are associated with iron sulfide minerals. This is a case at the Hidden Valley (HV) Mine. In this study, the effect of free and WAD cyanides on gold and silver recoveries by flotation from the HV Mine was considered.WAD cyanide (WAD CN) was prepared by mixing sodium cyanide and copper sulfate at a cyanide to copper ratio of 3:1 dosed at different cyanide concentrations. It was found that both free and WAD CN depressed gold and silver and particularly iron sulfides in flotation. The depressed gold and silver recoveries were closely associated with the depressed recovery of iron sulfide minerals, suggesting that free and WAD CN may not depress the flotation of liberated gold and silver minerals significantly. It was also found that 10 ppm free cyanide completely depressed the flotation of iron sulfide minerals and WAD CN depression is probably through the WAD dissociation to free cyanide species (mainly aqueous HCN) during the grinding process, resulting from a decrease in pH. Thermodynamic calculation showed that 5.5 ppm free cyanide was released in the end of grinding at an initial WAD CN concentration of 50 ppm. This research provides a guideline to counteract the negative effect of WAD CN in the flotation of gold and silver minerals.CITATION:Guo, B, Peng, Y and Espinosa-Gomez, R, 2013. The effect of weak acid dissociable cyanide on gold and silver flotation in Hidden Valley Mine, in Proceedings World Gold 2013 , pp 341-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Bin Xu, Qian Li, Xin Min, Xiaoliang Liu, Yongbin Yang, Tao Jiang, Yan Zhang

The ringing characteristics of acid and alkaline iron ore pellets powder in kiln were studied by the thermodynamic calculation using software FactSage7.0, roasting experiments using briquetting method and analysis of SEM-EDS. The thermodynamic calculation demonstrated that liquid phase could be generated from alkaline pellets powder at a lower temperature and the amount of formed liquid phase was much more than that from acid pellets powder at the same temperature. Roasting experiments indicated that the compression strength of alkaline pellets powder briquettes were also higher than that of acid pellets powder briquettes. Additionally, the analysis of SEM-EDS suggested that the alkaline pellets powder briquette presented more liquid phase and a more compact structure comparing with the acid pellets powder briquette, which was consistent with the results of thermodynamic calculation and roasting experiments. Hence, in comparison with acid pellets powder, alkaline pellets powder is much easier to ring in the kiln.

Mar 1, 2017

By V. R. Degner

The trend in both the metallic and non-metallic mining industry is toward processing increasing y higher tonnages of lower grade ores, thereby resulting in a growing interest in progressively larger volume individual machines in the flotation circuit. Because of the relatively high cost of large flotation machine development and evaluation, it is important to establish a rational basis by which the existing smaller flotation machine experience can be extrapolated to establish the configuration of the next larger family of flotation machines with a minimum of development modification in the field. This paper reviews the R&D approach used in translating smaller flotation machine experience to establish the configuration of a 1000 cu ft (2B.3 cu m) induced air machine. Internal cell hydrodynamic principles, which governed this extrapolation, and cell (liquid) surface and froth management considerations will be reviewed, and prototype machine mill tests will be summarized.

Jan 1, 1978