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The acoustic signals emitted from a laboratory-scale ball mill were used for the estimation of the comminution of two complex sulphide ores, viz. Merensky and UG2 ores from the Bushveld Igneous Complex in South Africa. The digital acoustic signals were transformed to power spectral densities that could be related to particle size distributions (-75 µm to 4000 µm) in the mill by use of continuum regression. This approach is more general than principal component regression methods or Kalman filtering used previously and resulted in significantly more accurate calibration in the case of the Merensky ore, where approximately 93.4% of the variance in the particle size distributions could be explained. With fewer data available, the variance in the particle size distributions in the UG2ore could be explained less accurately (82.4%), but still satisfactorily. In addition, smaller particle sizes (less than 300 µm) could be modelled more accurately in the case of the UG2 ore.

Jan 1, 2000

The safety of personnel is the most important matter during a mine fire. However, there is not enough research on a case when a fire occurs near a shaft and the behavior of the fire gas is not well understood. Therefore, a series of experimental study using a scaled ventilation circuit model was carried out. The behavior of ventilation air during a mine fire near a shaft was investigated. The model consists of two vertical shafts, three horizontal ducts connecting the shafts and an exhaust fan from the shaft bottom. The cross section of the shaft and duct is a square of 200×200mm. The height of the shafts is 3400mm. The length of the ducts is 1540mm. The lower duct is set at the same level as the shaft bottom. The middle and upper duct are set at 750mm and 1760mm above the shaft bottom respectively. The airflow rates through the ducts can be adjusted by regulators installed in each duct. The behavior of the fire gas was measured by anemometer, thermometer, and visualized using laser light .The air was ventilated downward in both shafts before the initiation of the fire. Some amount of fire gas of high temperature rose upward gradually along the shaft wall regardless of the downward ventilation after the initiation of the fire. Then the direction of main ventilation air suddenly reversed upward in the shaft. The direction of ventilation reversed in many places in the model and the fire gas reached even the part not anticipated.

Jan 1, 2009

Ledcap Pty Ltd has developed two software tools for assisting in the determination of life-of-mine (LOM) trucking requirements. The first tool generates haul paths and the second calculates truck travel time over these paths. The two step approach allows the paths to be viewed and if required edited, to better represent the actual site haul routes.The first tool automatically creates haul paths between the mine bench and the dump. To do this the user supplies a master haul route and a scheduled block model. The master haul path and the block model are interacted to create multiple haul routes, one for each pit/dump bench pair in each scheduling period. Each path carries with it a record of the scheduling period it represents and the dry tonnage hauled over the path in that period.The second tool calculates truck travel time over the path. Data from the manufacturer's rimpull and retarder curves are used to calculate accelerations and speed over each segment of the haul path. As the paths are derived from digitised representations of mine haul routes the path f les often have over a hundred segments. This detailed representation of the haul route allows the software to automatically adjust speed for different radius corners and accurately simulates the changing accelerations over the gradient changes that occur in real life mine ramps. Rolling resistance can be specified at a global level, at a segment level and at a period level. This allows rolling resistance to be changed seasonally as well as spatially.Life-of-mine trucking studies attempt to calculate an accurate answer from extremely variable inputs. This paper will detail the features of the two software tools and how the tools provided in the software can assist the mine planner to have greater confidence in their life-of-mine trucking requirements and the subsequent production capacity inputs to their scheduling calculations.

Dec 6, 2010

By H. Saroglou

Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists). Testing was used to establish the anisotropic behaviour of selected gneissic rocks. The effect of anisotropy on various mechanical properties (strength, deformation) and dynamic properties (wave velocity) was examined. The rock samples were also tested at successively higher confining pressures in order to evaluate the effect of anisotropic behaviour at high overburden pressures.

Jan 1, 2004

The fundamental objective of mine plans are usually to maximize the mine profit by extracting ore at the lowest possible cost over the mine life while some technical constraints are satisfied. Since the costs associated with the operation of trucks and shovels as resources are significant, determining the optimum number and allocation of these resources is an essential issue. This paper presents a Mixed Integer Linear Programming (MILP) model to determine the optimum number of shovels and trucks required to meet the short-term plan?s goals. Also, the model takes into account the allocation of trucks and shovels to mining faces. This model minimizes operational costs, while attempting to meet the production demand and to satisfy technological constraints. This paper also analyzes the operations of trucks and shovels in an open pit mine using ARENA simulation software.

Jan 1, 2012

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Basic parameters affecting the stability of foams have been studied. We used the thin film pressure balance (TFPB) technique of Scheludko and Exerowa (1959) to measure the surface forces in foam films stabilized with various frothers such as pentanol, octanol, MIBC, and PPG. The results were compared with the froth stabilities measured using the shake tests and the film elasticity calculated using the model developed by Wang and Yoon (2006). It was found that the froth stability is controlled by both film elasticity and surface forces (or disjoining pressure), the relative contributions from each changing with frother concentration and type.

Jan 1, 2006

By Y. Nakata, K. Nagata

Plasma is partially ionized gas composed of ions, electrons and activated elements at high temperature. Some flying ash from incinerated municipal waste is melted to become glass by a transfer-type arc plasma furnace. As the glass is ionic silicate, when an electric current passes through anode to cathode, ions in molten slag electrochemically react with electron in plasma at the surface of molten slag. In case of molten Na2O-SiO2, sodium ions in the molten slag carry electric current and SiO2are reduced to evaporate as SiO gas by electron in plasma. The cases of Ag+in NaNO3-KNO3molten salt and Fe2+in FeO-SiO2slag were examined. The amount of cathodic reaction is larger than that of anodic reaction and not apparently according to the Faraday?s law on the electrochemical reactions.

Jan 1, 2004

By Roger A. Archabal, Omar A. Conte, Gustavo Langoni

This international case study focuses on the rigorous geotechnical interaction and results of a soil improvement program utilized to mitigate consolidation settlements of over 1.5 m [5.0 ft]. The extreme settlement results from very deep, nearly normally consolidated clay and the required high floor loading of a new Logistics Park near Bogota, Colombia. The general subsurface conditions consist of very soft clay extending to depths beyond the 50 m [164.0 ft] explored. A required 1.2 m [3.9 ft] thick fill combined with high floor loads resulted in an applied areal load of approximately 7 ton/m2 [1300 psf] (equivalent to about 4.5m [15.0 ft] of fill). Langan recommended performing a test section to validate the initial consolidation settlement calculations and evaluate possible optimization of the prefabricated vertical drain (PVD) spacing and length. The test section sizing was designed to accurately represent the stresses at depth of the future structures. Extreme settlements of over 1.5 m [5.0 ft] in the center and large differential settlements of over 0.6 m [2.0 ft] were measured between the center and corners of the test section over a relatively short test time. Discussion on the methodology, instrumentation, measured results and future optimization are presented. The recommended soil improvement varied from the standard approaches typically utilized in the area. PROJECT LOCATION AND DESCRIPTION The project site is immediately north-northwest of the city of Bogota in the Bogota Valley. The site is bordered with, and has historically been, farming land bordered to the south by the El Rosal-Bogotá highway. The overall site encompasses about 570,000 m2 [141.0 acres] of gross area and about 484,000 m2 [119.6 acres] of net buildable area. The warehouse complex will consist of 10 very large warehouses with footprints ranging from about 15,000 m2 [3.7 acres] to 30,000 m2 [7.4 acres]. The total building area is about 210,000 m2 [51.9 acres] with most of the remaining areas being paved principal drives, truck parking or administrative parking. The topography of the site is relatively flat and close to final grade in roadway areas. However, the warehouse floors will be raised about 1.2 m [3.9 ft] (equivalent to about 2 t/m2 [370 psf] considering engineered fill) to allow for truck docking. In addition, the design floor loads are heavy and estimated to be up to 5 t/m2 [930 psf] and equivalent to about 2.5m [8.2 ft] of fill. Geotechnical conditions at the site are very weak at depths of 50 meters [165 ft] or more, with soft compressible clays comprising the majority of the soil profile. The Bogota Valley is composed in some areas of very deep alluvial deposits. These deposits have been classified as an important challenge and limitation to the development of high/heavy structures such as the project in question for many years (Orozco, 2006). Soft clay deposits have been encountered even beyond depths of 100 meters [328 ft] in some regions of the Bogota Valley (Sanz, 1994). Extreme settlements can be expected if extensive and high permanent loads (above preconsolidation stress levels) are supported in these thick alluvial deposits.

Jan 1, 2018

By T. Tamura

It is known that the CaO-FetO-P2O5slag system has a wide liquid miscibility gap at steelmaking temperatures and this two-liquid slag phase has many advantages such as high activities of both FetO and CaO and high amount of P2O5. The phosphorus distribution ratio between the two-liquid slag and molten steel was confirmed to be higher than that between CaOsat.-FetO-P2O5slag and molten steel. The two-liquid slag may be useful for dephosphorization of molten steel and reduction of slag volume. Furthermore, the phase equilibrium of two-liquid CaO-FetO-P2O5slagsaturated with MgO was measured to determine the applicability of the two-liquid slag to dephosphorization in steelmaking process. Keywords: slag, refractories, solid solution, two-liquid phase, dephosphorization, steelmaking, phase equilibrium.

Jan 1, 2004

By Glenn Kosick, John Starkey, Glenn Dobby

"A practical new test has been developed for SAG hardness determination. Using two kilogram samples of minus one inch diamond drill core or crushed muck samples, the Starkey SAG Test has been shown to give accurate predictive information which directly relates to on-stream SAG mill performance. Typical results and test criteria are discussed in the paperAchievements to date include:• Identification of hardness profiles and the location of hard and soft zones in a large ore body.• Accurate prediction of the hardness of a bulk sample by using an adjacent diamond drill hole.• Derivation of a plotted curve relating pilot plant power to laboratory relative hardness.• Demonstration that for every test done to date, the Starkey SAG Test produced a product size distribution identical to that produced in a pilot plant or full scale plant SAG operation.This test can now be used for blast hardness monitoring and short term control of mine production in existing plants and for identifying the proper locations for bulk samples in new projects. In addition, new SAG mill design can now be rationalized in a low cost way to eliminate unforeseen production shortfalls.IntroductionThis paper is presented to introduce the Starkey SAG Test, a practical new laboratory tool for measuring the relative hardness of small ore samples in a semi-autogenous grinding (SAG) environment. The test was first designed for use on diamond drill core samples during the prefeasibility stage of new mining projects, to provide new information about the ore body at reasonable cost. It is a new tool and does not replace existing pilot plant test requirements.The test will also be useful for throughput prediction in existing SAG plants by assisting in short and long term mine planning, where forecasting of metal grades and milled tonnage is used to control mine profitability. Because in-plant hardness testing has previously been unavailable on small samples, this test offers exciting possibilities for SAG mill operations where hardness variation is or could be a problem.The Starkey SAG Test provides the following benefits to the mining industry"

Jan 1, 1994

Traditionally, capital costs of major resource development projects have been estimated as a single amount to which a percentage accuracy has been assigned based on the method of preparation of the estimate, that is, on the amount of information available to develop the estimate.However, there is a growing recognition of the importance of a probabilistic approach to capital cost estimates, and of a more rigorous calculation of estimate accuracies and of the presentation thereof. Accuracies can be expressed with more certainty as a percentage of the estimate amount where the percentage represents one standard distribution on the probability curve for the capital cost of that specific project. Thus confidence levels can be stated for various estimated amounts - for example, it can be stated that there is an 85% chance that a stated amount will not be exceeded, or a 90% certainty that a (higher) amount will not be exceeded. Moreover, the right skewness of the probability distribution curve for most projects can be readily recognised and reflected in the evaluations. This enables senior executives and board members to have a clearer understanding of investment uncertainties, and the possible magnitude of commitments.

Jan 1, 1990

By Nick Salisbury, Alan Howard, Scott Tunison

INTRODUCTION Geotechnical investigations for tunneling projects typically use vertical test borings and, to a lesser extent, angled borings. Horizontal drilling applications were often limited to specialty testing programs and to perform probe drilling from a tunnel boring machine (TBM) as part of production tunneling. The former often involved cumbersome setups with skid rigs and cribbing in a pilot tunnel or shaft. The latter usually was limited to generic probing for rock quality and ground water conditions with no sampling. Neither yielded continuous core at production rates suitable for design and construction planning. Conventional vertical investigations still make sense in many instances, particularly for tunnels planned beneath urban settings where truck access is convenient and where the tunnel horizon is not readily accessible via a portal or shaft. However, equipment is presently available to conduct horizontal geotechnicall investigations at reasonable production rates and cost. Advantages include continuously sampling the tunneling horizon and minimizing “access drilling” to get the zone of interest at the underground construction horizon. Horizontal boring lengths of up to approximately 800 m are considered feasible and those in the range of 150 to300 m are now routine. These capabilities make horizontal borings an attractive option to consider when looking at deep tunnels beneath ridges, especially where access is limited. Fewer drilling staging sites can also mean reduced environmental impacts when investigating tunnels proposed beneath sensitive lands such as public wilderness areas. Investment in early construction packages to develop portals for investigation access and, possibly in excavating test shafts for the same purpose should even be considered. Potential benefits in the form of achieving improved overall project costs using horizontal borings exist because of the significant additional data collected in the tunnel horizon. For this reason they should be considered during the routine cost-benefit analyses generally conducted for planning geotechnical investigations for tunneling. The authors also believe that collection of such data will reduce Geotechnical Baseline Report (GBR) conservatism and lead to lower potential for

Jan 1, 2005

By A Rojc, J Ronaszeki, C Smith

Nuclear logging was tested for the in situ determination of Fe, Si, and Al in iron ore blastholes with field tests at the BHP Billiton Iron Ore, Mount Waleback Mine. Prompt gamma neutron activation analysis (PGNAA) was used to determine percentages of Fe and Si while natural gamma logging was employed for the determination of Al. The accuracy given by nuclear logging is comparable to the accuracy provided by the laboratory analysis which was determined by taking the average of four samples collected from the cuttings deposited on the surface around the perimeter of a drill hole. The work also indicated that there is a chance of determining Al by PGNAA.

Jan 1, 2002

By S. Asokan, CVGK Murty, R. Upadhyay

The principal mineral sources of titanium are rutile, anatase (both TiO2), ilmenite (FeTiO3) and leucoxene (a weathered ilmenite of variable concentration of TiO2 but similar to pseudorutile Fe2Ti3O9). These titaniferous minerals along with their value added products like Synthetic Rutile and TiO2 slag constitute ?Titanium Feed-stocks? for TiO2 pigment, Ti metal and welding electrodes industries. Unlike in other industries, the demand driver for titanium minerals is not the metal, but the TiO2 pigment ?a specialty chemical. Of the total titanium feedstocks usage in the world, about 93 % is consumed in TiO2pigment, with only about 3 % is utilized in metal production. India?s heavy mineral sands resources are among the largest and also one of the richest grades in the world. The country?s Ilmenite resource base stands at 348 million tonnes of Ilmenite (18% of the total world reserves)along with 18 million tonnes of Rutile, 21 million tonnes of Zircon, 8 million tonnes of Monazite, 107 million tonnes of Garnet and 107 million tonnes of Sillimanite. Though the grades (Total Heavy Minerals (THM) present in the sand) of Indian deposits are relatively rich, the contained ilmenite are termed as sulphate grade with 50-53% TiO2 (Chavra deposit of Kerala and Ratangiri deposit of Maharastra are an exception with 60% of TiO2). While superior grades with adequate reserves lead to a cost advantage in ilmenite production, the lower TiO2 percentage allows the direct use of Indian ilmenite only in the production of TiO2 pigment through sulphate route and for the chloride pigment production; such ilmenite is required to be upgraded either to Synthetic Rutile (SR) or TiO2 slag. However, in order to produce TiO2 slag in India at a globally competitive cost, the issues like high power tariff, inadequate infrastructure, expensive logistics, less enthusiastic market preferences, supply-demand gaps are to be adequately addressed. This paper deals with some of the above issues and possible solutions thereto in production of TiO2 slag from Indian ilmenite.

Jan 1, 2007

By Martin Stoklossa

Surface mining operations typically require run-of-mine material to be sized for further processing. In-pit crushing facilities serve this need, as stationary, semi-mobile or fully mobile units. Although in particular fully mobile crushing facilities have been in use for over half of a century, other surface mining techniques have typically been implemented. However, with increasing operating costs in truck and shovel operations, and other economic considerations, mobile crushing plants are increasingly a viable option. The operational and economical parameters in relation to the optimal surface mining equipment selection will be reviewed. The role of the mobile crushing technology within the continuous vs. noncontinuous surface mining operation and basis for mine planning are also discussed. Current applications and respective case studies will be reviewed. Key performance indicators will be presented. These performance parameters can be viewed as a tool to aid in the equipment selection process. The future direction for further research and development in mobile crushing facilities will also be presented.

May 1, 2008

By M. Tarvainen, J. Kallioinen

"Depressed metal prices coupled with increasing production costs have presented a great challenge for operators to control and reduce the costs of production to maintain profitability. Depleting ore reserves, added to the above has forced Outokumpu to take a hard look at its operations, to develop new methods to profitably extend the life of its mines. One of the areas investigated and approved for further development has been the use of larger and more energy efficient equipment. As a result, large flotation machines were developed and today 38 and 60m3 flotation machines are in use.Secondly, ore preconcentration has been developed to avoid processing the part of the ore that has little or no mineral values.Another quite recent development and the topic of this paper, has been the use of coarse flotation before conventional flotation. The main idea is that part of the valuable mineral is separated as early as practical by floating it with specially designed flotation equipment, installed in the grinding classification circuit. The new flotation cell is specially designed for this application and differs from the conventional cells in the tank design, feed arrangement and modified mechanisms in some cases."

Jan 1, 1984

By B Rosemberg, F Lemos, A J. B Dutra

The chemistry of cyanide solutions is complex, this complexity being responsible for the ability to act as complex-forming agents in metal dissolution processes, among them gold and silver. Such ionic species are used in hydrometallurgical processes, in particular in gold extraction and electro-plating. Due to the high toxicity of cyanide, the discard of effluent from processes and/or industries demands rigorous treatment so as to minimise its concentration. Among the conventional chemical treatment of such effluents one can mention SO2/air; biological degradation; oxidation by using hydrogen peroxide; oxidation by sodium hypochlorite, etc. However, the electrolytic recycling process is also promising for cyanide recovery and offers the possibility of recycling it to the aforementioned industrial processes. Such a process does not use additional chemicals but enables direct re-utilisation to the main process aiming at adjusting the cyanide concentration.

Jan 1, 2002

Neither the copper orebodies nor the zinc-lead-silver orebodies at Mount Isa were formed syntectonically as has been claimed for the last 20 and 10 years respectively. Both orebody types were cogenetic, coeval, and formed early during the sedimentation and diagenesis of the host formation. The copper orebodies are interpreted as having formed diagenetically at hand specimen scale, syngenetically at formation scale. The zinc-lead-silver orebodies are interpreted as having formed primarily by sedimentary means at both hand specimen and formation scales.

Jan 1, 2000

By L. Franko, S. Klima

Wet-drum magnetic separators are used extensively for upgrading iron ore and for magnetite recovery in dense-medium circuits. In this study the performance of a continuous, laboratory wet-drum magnetic separator was evaluated with and without the application of ultrasonic energy when processing dense medium slurries. Test variables included magnetic-to-nonmagnetic ratio, solids concentration, and nonmagnetic materials. The results indicate that under certain conditions, the purity of the magnetic material increased after ultrasonic treatment.

Jan 1, 2001