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"The first SkimAir flash flotation cell was installed in Outokumpu’s Hammaslahti Copper Concentrator in 1982 to prevent overgrinding of soft sulphides in the milling circuit. Since this first installation the popularity of the flash flotation has fluctuated depending on metal market conditions and regional preferences. Units have been installed in many commodities including copper, lead, gold, PGMs, silver and nickel. Though it has been successfully employed in many operations around the world, flash flotation technology is still not well understood by many in the mining industry. This paper will discuss aspects of flash flotation flowsheet development along with some of the metallurgical and engineering considerations required to successfully incorporate flash flotation into new or existing milling circuits. This paper will also try and debunk some of the myths that exist around flash flotation cells and their operation. Case studies of flash flotation implementation will be discussed.IntroductionModern flash flotation technology was developed several decades ago by Outokumpu, with the first commercial installation of this technology being at the Hammaslahti concentrator in Finland in 1982 (Kallioinen & Niitti, 1985). This was a relatively modestly sized SK80 cell producing final grade copper concentrate directly from the flash flotation cell operating in the grinding circuit. Since that time the size and number of flash flotation cells installed globally has grown considerably to the point where today, it is a widely known application of flotation technology for amenable ores. Owing to their long history in developing the technology, Outotec are the market leader with their SkimAir range of flash flotation cells. Though there is a general awareness of flash flotation process in the mineral processing industry, there is a lack of detailed understanding of the process and the benefits it can provide to new and existing operations."

Jan 1, 2017

By Arthur L. Hall

The purpose of this symposium is to challenge industry to better air classification, and as a first step toward fulfillment, to spotlight three fairly recent, aerodynamically designed, highly efficient air classifiers. This discussion does not intend to imply that present practice is bad. Actually, when present air separators are used for the jobs for which they were originally designed, they give high production and uniform operation, with a minimum of maintenance. The customers of nonmetallic mineral pigment producers, however, are making increasing demands for finer products, such as 99.9 pct -20µ, which appears to be beyond the economic capabilities of standard air separators industrially used over the last 10 to 30 years. Here is an actual example. A 10-ft diam pebble mill is in closed circuit with a conventional 12-ft diam centrifugal air separator, grinding 20-mesh wollastonite to a series of fine grades up to 99.97 pct - U.S. No. 325 mesh (44µ). Fig. 1 shows variations in fineness of mill discharge (or air separator feed), recycle for regrinding (or air separator tails), and product as measured by a wet rotating sieve test. For example, when the mill is turning out a product 80 pct -325, the mill discharge or separator feed is 30 pct -325, and the coarse tailings or recycle is only 5 pct -325. Hence 25 pct of the 30 pct available is accepted as product. This is efficient separation, and the ratio of recycle to feed is only about 2: 1. How- ever, to make a product testing 99.97 pct -325 the separator feed is 62 pct -325 and the coarse tailing 60 pct -325. In this case the recycle ratio is about 13: 1 and the economic limit to produce fineness has been substantially reached with this given equipment and process arrangement.

Jan 10, 1957

By G. L. Oldright

The data presented in this paper were collected at the smelter of the Consolidated Mining & Smelting Co. of Canada, Ltd., Trail (Tadanac), British Columbia. Many thanks are due to S. G. Blaylock, vice president and general manager, James Buchanan, smelter superintendent, and George Murray, assistant smelter superintendent, for their broad general policy in permitting these data to be taken and published. life are also grateful for the help given by the staff members stated in Paper XI, Report of Investigations Acknowledgment is given several excerpts from experiments by F. E. Lee, head of the research staff. INTRODUCTION The past reputation of zinc as an ingredient in lead blast furnace slags has been bad. Zinc is thought of as a cause of accretions in the shaft of the blast furnace, of hot tops, of the formation of "zinc mush" in the crucible and forehearth, of lead-rich slags, of viscous slags, and. of low capacity in smelting.

Jan 1, 1934

By Raphaël Mermillod-Blondin, Claude Bazin

"Sampling is an important step for ore body evaluation and daily plant material balances. The Gy’s equation is regularly used to assess the size of the samples to be collected and to estimate the reproducibility of the collected samples. The equation works well for iron and base metal ores but seems to produce pessimistic estimates of the gold content reproducibility for gold ores. A model is proposed to simulate the division of samples using a standard splitter and discrepancies are observed between the Gy’s equation predictions and simulated samples reproducibility for crushed gold ore. Results of the simulation show that sampling a pile of ore crushed to -2 mm should lead to more reproducible gold content than it is observed in practice and predicted by the Gy’s equation.INTRODUCTION With current gold prices above $1400 per troy ounce operators seek for new economical ore bodies. The metallurgical evaluation of an ore body is one of the numerous steps required to justify the investment for the development of a gold mine. Metallurgical testing requires to sample the ore body and to prepare the ore sample for the grinding and separation tests. The preparation implies crushing the ore usually to less than 2mm and its division into batches of a given weight for subsequent processing. For gold ore testing a batch of crushed ore is ground in a laboratory mill and leached using cyanide. Gold recovered in the solution is used as an indicator of the ore processing amenability. One difficulty associated with ore testing is due to the reproducibility of gold content measurements of the feed sample. According to the Gy’s equation (Gy, 1979; Morisson, 2009) the division of a 20 kg batch of -2 mm ore containing 5 g/t of gold into batches of 1 kg may lead to batches containing 5 ± 5 g/t of gold. For this reason the gold content of a feed sample is usually back calculated from the assays of the solution and solids residues of the leaching process. However, these two assays may contain measurement errors that can propagate through the calculation of the gold recovery. The use of the feed assays as a redundant information could add robustness in the evaluation of ore amenability to processing. This paper discusses the problem of sampling reproducibility for a gold ore. The analysis is carried out with reference to the Gy’s equation for the sampling of particular materials."

Jan 1, 2012

By Charles Pretorius, Henk Ludik

Navachab Mine experiences difficulties with pit wall stability in certain areas of the mine. The main reason for the instability is the fact that the geology comprises many joints and faults. Blasting, without impacting negatively on the stability of the pit walls, poses a major challenge.

Jan 1, 2006

By S. Chung

Mining in highly stressed ground conditions has been an increasing challenge at the Brunswick mine. Over the past 30 years, two large regional pillars were established on the 1000 m Level to support the ground for safe extraction of the surrounding ore. The South Regional Pillar contains about 5 Mt of ore and the North Regional Pillar has about 3 Mt of ore. In the fall of 2000, mining activities were suspended following a series of ground movements around the South Regional Pillar along weak geological structures. After extensive geotechnical investigations, a decision was made to carry out a mass de-stress blast in the West Ore Zone (WOZ) to cut the principal stress across an area of 135 m along strike and 86 m high. At the end of July 2001, the WOZ mass blast was successfully initiated. Following this success, the mine decided to take a similar approach to de-stressing the North Regional Pillar (NRP). The final mass blast was taken in early February 2003. Advanced blasting technologies, including state-of-the-art electronic detonators and blast simulation, played an important role in achieving the successful blasts. The high precision of delay timing and long delay duration of the electronic detonators ensured accurate and reliable initiations of over 800 blastholes in the WOZ mass blast. Orica’s DMC_Blast (Distinct Motion Code) simulation code was used to study different blasting blocks for the desired timing in the initiation sequence. This paper describes the process of applying electronic detonators in complex blasts, and discusses how blast simulation results were interpreted to guide engineering design of the mass blasts.

Jan 1, 2005

By Q. Wu

Neural network methodology is used to predict mean particle size resulting from rock blast fragmentation. A blast data base developed in a previous study is used in the current study. A part of this blast data was used to train a single-hidden layer back propagation neural network model for each of the similarity groups obtained in the same previous study. Levenberg-Marquardt algorithm provided the most stable and efficient training out of the four algorithms evaluated. An extensive analysis was performed using a part of the blast data to estimate the optimum number of units for the hidden layer for each similarity group. The remaining blast data are used to validate the trained neural network models. Capability of the developed neural network models is determined by comparing predictions with measured values and predictions based on one of the most applied fragmentation prediction models appearing in the blasting literature. Prediction capability of the neural network models was found to be strong and better than the existing most applied model. Diversity of the blasts data used is one of the most important aspects of the developed models. The developed neural network models are suitable for practical use at mines.

Jan 1, 2011

By A. T. Iannacchione

From 1990 to 1996, 16 states reported 92 injuries from falls of roof, rib or face in the more than 90 underground stone mines in the United States (Fig.1). Missouri, Pennsylvania and Kentucky accounted for 48% of the total number of injuries (Fig. 2). Of this total, 11 miners were killed. Of the 11 fatalities, 10, or 91%, were associated with unrecognized loose or failed rock within the roof beam. Additionally, unrecognized roof beam failures resulted in a majority of the falls of ground injuries occurring in underground US stone mines from1990 to 1996. This number is not large in magnitude. But a workforce of fewer than 2,000 miners makes for a high fatal-accident rate. The severity of the typical fall-of-ground injury is, in general, very high. About three-fifths of all roof, face and rib fall injuries were designated by the US Mine Safety and Health Administration (MSHA) as some kind of lost time accident. MSHA assigns each accident a severity value from one to six. A one represents a fatality, a two, a permanent disability and three, a lost time accident (Fig. 3).

Jan 1, 2000

By Donald J. Hallbom

"While pipeline hydrotransport is often the most economical way to transport large volumes of mineral concentrate, tailings, or fine ore slurry over long distances, it is in mountainous terrain that pipelining becomes particularly attractive. These areas are often remote, with limited existing infrastructure and few potential users willing to share in the cost of new infrastructure. The rugged terrain makes the construction of railways or roads suitable for haul trucks difficult and expensive. The elevation difference between the mine and the terminal means that the empty trains or haul trucks need to return up-hill, resulting in high fuel costs. With pipelines, this elevation difference may reduce or even eliminate the need for pumping. As a result, numerous pipelines have been built, or are being considered, in mountainous regions around the world including: Tasmania, New Guinea, China, Madagascar, the Rockies of North America, and the Andes of South America. However, there are technical difficulties that need to be overcome in the design and operation of mountain pipelines that do not affect pipelines on more level terrain. This presentation reviews some of these difficulties and methods used to overcome them.INTRODUCTIONPipeline transport of solid-liquid slurry (“hydrotransport”) is an important and cost-effective means of transporting large volumes of solids over long distances, especially from a single supplier to a single user (e.g., a concentrator to a port, a concentrator to a tailings dam, or a coal mine to a power plant). Pipelines are generally found to be more economically attractive than alternate transportation methods (e.g. trucking, rail, conveyors, shipping, or some combination) over the life of a project (Aude et al. 1974).Hydrotransport systems have been built in a variety of terrains, but it is in mountainous regions that pipelining becomes particularly attractive. These regions are often remote and generally do not have existing transportation infrastructure (roads, railways, navigable rivers). There are few potential users (e.g., farmers, other mines, forestry companies, etc.) who may be willing to share in the cost of new infrastructure. The rugged terrain makes the construction and maintenance of railways or all weather roads suitable for large haul trucks difficult and expensive. Mines tend to be higher than the receiving terminal (e.g. a port). This means that the empty trains or haul trucks need to return up-hill, resulting in high fuel costs. With pipelines, this elevation difference may reduce or even eliminate the need for pumping. Pipelines are easier to construct than roads and railroads in these areas for several reasons, including:"

Jan 1, 2006

By Ross R

Although mining is an old industry its management is quite a new science, and its complications are now being recognised as demanding expert knowledge in many branches of technical and professional education. Not the least amongst these isaccountancy, for probably its most important problem is "How to control the expenditure." Unlike most businesses a mining company stands almost entirely in the light of a purchaser in the world's markets, and not as a seller, except say for product so the established and perfected systems of modern industries cannot be adopted for mining purposes. For this reason it has been left for late years to consider the matter seriously, and now a number of well-managed concerns have devised costs systems to suit their own requirements.Very little, however, has been published and even that is disjoined and difficult to make use of. Some of the costs systems in vogue, although elaborate and imposing, are not of very great value for keeping check on wasteful expenditure, or for displaying the commercial effect brought about 'by any particular change in practice, or by an addition or alteration to a portion of existing plant.

Jan 1, 1912

By Doug Tesarik

Researchers from the National Institute for Occupational Safety and Health1 (NIOSH), together with employees from The Doe Run Company, are monitoring and evaluating the stability of a pillar retreat section at the Fletcher Mine, a lead/zinc, room-and-pillar mine near Bunker, MO. Cemented rockfill is being used to provide roof support as high-grade, remnant ore pillars are mined. Earth pressure cells and deformation meters placed in backfill panel pillars monitor stress change and vertical deformation, respectively, as nearby ore-bearing pillars are extracted. Similarly, biaxial stressmeters and borehole extensometers are used to monitor mining-induced stress change and deformation, respectively, in long-term support pillars. Data from these instruments indicate that when ore-bearing pillars were mined, stress was redistributed from support pillars to a backfill panel pillar. The data also indicate that the backfill and support pillars have remained stable for two years after pillar extraction was completed in the area. This research demonstrates the importance of using reliable instruments to document the geomechanical behavior of pillars and backfill. Gaining a better understanding of roof support and stress redistribution mechanisms is a fundamental part of NIOSH's goal to reduce and/or predict rockfalls, which are still among the leading causes of injuries in metal/nonmetal underground mines.

Jan 1, 2006

By Lowell Stroud

This report is the third in a series presenting equilibrium vapor-liquid data for helium-bearing natural gases. The first two reports contained phase data for the gases processed for helium at the Bureau of Mines Amarillo and Exell, Tex., helium plants. The present report offers similar information for a lower-helium-content (0.75 mole-percent) natural gas to be processed in the Department of the Interior's long-range helium-conservation program. A windowed-cell apparatus was used to obtain 218 samples of equilibrium vapor and liquid phases at 73 experimental conditions ranging in temperature from -100° F to -275° F and in pressure from 100 to 500 psi. From the phase data, the condensation characteristics, helium solubility, and equilibrium-vaporization-coefficient data for helium, nitrogen, and methane were evaluated. The effect of using a. preliminary hydrocarbon trap upon the subsequent vapor-liquid compositions is reported. A brief comment regarding the composition effect of passing the gas through a gasoline-removal unit is also included.

Jan 1, 1963

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

By Mark R. Svinkin

This paper deals with application of the wave equation analysis to determine capacities of piles driven in saturated sandy soils. It shows that pile capacity in sandy soils changes with time after the completion of pile driving and depends on the ground water elevation. In saturated sandy soils the setup coefficient ranges between upper and lower curves represented by power functions. For a reliable prediction of pile capacity wave equation input should be adjusted with soil damping. Back calculation of soil damping from known pile capacity performed for five tested piles shows that skin damping coefficient changes with time in the same manner as the pile capacity and can be represented by the power functions for considered damping models.

Jan 1, 1995

By C. E. M. Meskers

End-of-life Electronic and Electrical Equipment, o_cially called WEEE, is unjustly regarded as mainly a waste management problem. What is structurally overlooked is the enormous resource impact of these devices. EEE rep- resents a tremendous metal resource, which should be uti- lized through e_ective recycling, which has a much lower environmental footprint than primary production. The actual amount of end-of-life EEE recycled today is embar- rassingly low since insu_cient EEE is collected and part of the collected EEE is exported to developing countries, where it is largely not entering o_cial recycling systems. To achieve a global recycling society issues like technol- ogy, economics, life cycle structure, stakeholder aware- ness and legislation have to be addressed in a global, co-operative manner so that sustainable closed product cycles can be obtained. Requirements for a "global re- cycling society" are de_ned to address today's reality of global ows of used consumer products, taking into ac- count the likely needs of the future.

Jan 1, 2009

By Zhan Jing

Keywords: thermodynamic, Ni-Co alloy powders, composition, fibrous The mathematics model of Ni(II)-Co(II)-C2O42?-NH3?H2O-H2O of thermodynamic equilibrium system has been developed theoretically according to the law of conservation of mass and the law of simultaneous equilibrium, and the logarithm concentration-pH (log[Me2+]T-pH) diagrams of this system have been made. The effect of ligand and pH value was studied. Two issues in coprecipitation route to synthesize fibrous nickel-cobalt alloy precursor powder, com-position and morphology which are a first priority, are addressed based on thermodynamic analysis and experiments. The results show that suitable pH value range of coprecipitation of nickel ions and cobalt ions in theory can be obtained to maintain fibrous, excellent compositonal homogeneity and stoichiometry in coprecipitation products. Experimental demonstration is also carried out.

Jan 1, 2005

The reality of rising electrical power costs and the haunting prospect of decreasing electrical power availability are a threat to the growth of new projects and expansion programmes that could negatively affect the sustainability of mining operations. These threats require the adoption of effective power saving measures aimed at three principal objectives: the elimination of wastage, the reduction of power usage particularly during peak demand periods and, more importantly, improving the efficiency of high power-demand processes. It is reasonable to assume that the greatest impact will be achieved by concentrating on those processes that are large electrical power consumers. For Anglo Platinum operations, mine ventilation and, currently to a lesser extent, mine cooling are two continuous processes that fall in this category. It is estimated that these may consume fifteen to thirty-five per cent of the power delivered to the shaft head-depending on the shaft's design. Mine ventilation systems suffer from inherent, historical inefficiencies that lead to excessive power consumption. Air cooling systems are designed to be energy-wise in terms of modulating refrigeration plant operation to meet the underground requirements while maximizing use of 'free' cooling from surface conditions. Currently about ninety-five per cent of the refrigeration capacity used in Anglo Platinum mines is dedicated to surface bulk air coolers. The net thermal efficiency of these systems is compromised as mines expand in depth and on strike. Looking to the future, this practice will be complemented by more energy demanding underground cooling tactics requiring considerably higher electrical power consumption per unit ton produced. To counter this increase in power consumption, more energy-efficient systems and advantageous transient strategies such as thermal storage and the use of ice-on surface and possibly even underground-are being considered. This paper describes work currently undertaken and planned by Anglo Platinum operations to reduce power consumption by main fans during off-shift periods, the associated efforts currently introduced to reduce underground air leakage, the possibility of introducing more efficient auxiliary ventilation systems, the feasibility of thermal storage, and a brief look at energy recovery system as a means of countering the anticipated power demand associated with underground cooling. Keywords Mine ventilation, mine air cooling, energy efficiency, chilled service water, energy recovery, air wastage, fan selection.

Jan 1, 2011

By M. K. Sichone

Anglo Platinum?s Waterval smelting complex based in South Africa operates the Anglo Converting Process (ACP) that produces SO2 offgas. This SO2 offgas is treated in a double-contact, double-absorption acid plant allowing for conversion efficiencies higher than 99.90 %. The catalytic converter used in the acid plant to convert the SO2 to SO3 is a 4-bed reactor loaded with a combination of cesium-promoted and conventional vanadium pentoxide catalysts. In June 2008 there was a shutdown, in which one of the main activities was to screen the catalyst. Before this shutdown, the operator would control the converter pass temperatures manually, via the SCADA, especially during plant start-ups after which some of the automatic temperature controllers were used. After the shutdown, the control philosophy was revisited and all temperature controllers were put on auto mode during plant start up. Furthermore the set points of the pass inlet temperatures were reduced to maximize conversion in the first two passes. The result has been a reduction of SO2 emissions, from a daily average of 50 ? 70 ppm to as low as 20 ppm for similar sulphur dioxide and oxygen concentrations. Further work has been done to maintain high bed temperatures in the third and fourth passes at low SO2 strengths by splitting the gas stream between pass 1 and 2 thus increasing the SO2 content in the gas to pass 2. This increases the temperature of the gas exiting the second pass, which results in higher temperatures in passes 3 and 4. Comparison of the converter performance prior to and after the changes is made. The benefits of partially bypassing the first pass to increase the SO2 content in the gas to the second pass are shown. Conclusions and scope for further work have been drawn from the comparisons.

Jan 1, 2009

By Rowan A' Murry Karstel

One way to ensure dragline productivity is by Increasing the size of the dragline bucket. In August 1994, Optimum Colliery in conjunction with Van Reenen Steel, Northwest Applied Technology, SSAB of Sweden and Barlows Equipment launched the new lightweight dragline buckets. Optimum built the first prototype bucket that was used for the deslgn for future buckets. After knowledge had been gained from measuring the input force of the bucket Northwest Technologies designed the new bucket with finite element analysis. Together with the knowledge of quenched and tempered steel from SSAB of Sweden and Barlow Equipment, the new Wrightech bucket was born.

Jan 1, 1998

Tailings embankments can develop a high phreatic surface if the original design for the embankment does not include drainage facilities or if existing drainage facilities become ineffective. Subsequent raises can develop a seepage surface due to a high phreatic surface that can lead to stability problems. The U. S. Bureau of Mines amended contract J0100013 to initiate this study of horizontal drains in tailings embankments. This study developed a technique for determining the length of and spacing between parallel drains through the use of the finite element model UNSAT2. The analysis is based on the combined output of a vertical planar mesh and a horizontal planar mesh. The slot opening in the drain pipe and the length of the perforated section are determined from an analogy to water well design. The pipe diameter and gradient can be determined from Manning's equation. To the authors' knowledge, this is the first attempt at horizontal drain design using a finite element model. Additional research is recommended in this area.

Jan 1, 1982