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By V. Ross

"Bench-scale flotation tests play a major role in the geometallurgical process value chain. Despite their apparent simplicity, these tests pose pitfalls in terms of operation, as well as the interpretation and modelling of results. In this paper we highlight key aspects to consider in generating accurate and reproducible experimental results, and critically review some assumptions relating to the estimation of entrainment and froth recovery. We subsequently focus on first-order equations to model kinetics and propose a method that accounts more realistically for the decay in kinetics over the duration of a float, and the contributions of froth stability and hence mass pull. The method was applied to three case studies on platinum group metal (PGM) ores and matched or outperformed first-order, two-component models. Also, it allows for a deeper analysis of the integrity of the bench-scale flotation results. IntroductionGeometallurgy is a structured, multidisciplinary approach that integrates key data from the geological, mining, mineralogical, and metallurgical aspects of the value chain to construct spatial models of an ore deposit such that the overall economic benefit and sustainability of an operation can be optimized. Process geometallurgy is aimed primarily at enhancing metallurgical efficiency and plant throughput by the application of appropriate mining and processing strategies, as well as supporting production planning and operational strategies to reduce the impact of highly variable ores. With flotation being the dominant concentrating process in the mineral value chain, the bench-scale flotation test is an important characterization tool – a relatively cheap, simple, and rapid way to obtain key information about the ore and its amenability to economic extraction of valuable minerals. This includes the evaluation of different ore types and the implications of mineralogical composition and texture for comminution and floatability, the effect of the grinding environment on the liberation of minerals, the electrochemical environment in the pulp (Bradshaw et al., 2006), the screening of reagents to improve floatability (Ekmekci et al., 2003), and the role of hydrodynamics in the recovery of valuables and the entrainment of gangue (Amini et al., 2016; Wang et al., 2016). It is also a critical tool in auditing the performance of a flotation plant by hot floats, paving the way for concept and feasibility studies and providing essential data on kinetics for the purposes of scale-up, optimization, and simulation of flotation circuits."

Mar 1, 2019

That electricity is an important and valuable agent, the limit of whose capacity for utilisation is as yet unknown, is a truism; although enormous advances have been made, the possible developments are yet greater. Mining, along with other industries, shares already to a large extent in the practical utilisation of this agent. Electrical engineers have been employed for several years past in developing and applying electricity to all classes of machinery, and for every purpose where power is required and in no instance, that the writer is aware of, has its use been curtailed in favour of any other agency now known, while extensions are continually made. The first modern electric motor was shown at the Vienna Exhibition of 1873, and it was used to work a pump through a mile length of cable but it was not before 1878, that an electric motor was put into daily commercial use by Messrs. Chretian and Felix to work a beet sugar hoist. This early plant effected a saving of 40 % as compared with hand work.In 1879, the first Electric Railway was constructed for the Berlin Exhibition, and in the same year, Mr. T. A. Edison was running an experimental line at Menlo Park. The first electric line opened for the public, was constructed by Siemens and Halske, in 1881, at Lichtenfelde, and was 11 miles in length.

By Krogerus. H., P. Jokinen, T. Lintumaa

Keywords: Pyrometallurgy, furnace, coke, smelting charge, optimization, ferrochrome The main consumer of ferrochrome is stainless steel production. Stainless steel must maintain a reasonable price against other competitive materials. Therefore, the ferrochrome price must be low enough and profitable for the producers of stainless steel. The investment and operational costs of ferrochrome production are greatly dependent on the availability of the process and the production rate. Thus the furnace size and production rate in submerged electric arc furnaces will be greatly increased in the near future. The ferrochrome production per furnace, e.g. at Outokumpu?s Tornio Works, increased from 30 000 t/a to 165 000 t/a in about 35 years. The same trend will continue globally but now much more quickly. The Outokumpu ferrochrome process at Tornio Works uses sintered chromite pellets and upgraded lumpy ore as a chromite source. Metallurgical coke is used as a reductant. Reliable smelting in a large furnace demands the correct charge composition and well-known characteristics of the charge components. The quality and electrical conductivity of cokes (normally used) has the most important role for the electrical conductivity of the smelting charge. The results of the measured electrical conductivity of different cokes and the smelting charge with many controlling factors are presented here. These measurements were performed over the years for our own purposes at the laboratory of Outokumpu Research Oy (ORC), in Pori, Finland.

Jan 1, 2006

By A. C. Fieldner

"Decline of the Beehive Coke OvenTwenty years ago a favorite theme of the crusader for fuel conservation was the enormous waste of valuable by-products incurred in the manufacture of blast-furnace coke in beehive ovens. Indeed, there was good reason for arousing the national conscience to this needless' loss of an irreplaceable mineral resource. In 1910, 83 per cent of the coke production was made in beehive ovens, from which surplus gas, tar, light oil, and ammonia, aggregating in value (at 1910 prices) 40 million dollars annually, were discharged into the atmosphere.In 1929, proportions were reversed and 90 per cent of the production was made in by-product ovens. The average value of by-products obtained in the production of 1 ton of coke in 1929 was $3.60, as compared with $1.16 in 1910, although the value of a ton of coke had increased only from $3.47 to $4.80. As shown in Figure 1,1 the production of by-product coke progressed rather slowly until 1915. War needs suddenly expanded the demand for coke and the by-products benzol and toluol for the manufacture of explosives. Except during the depression of 1921, this accelerating rate of production was maintained up to 1929, largely at the expense of beehive plants. The 1929 production of 60 million tons of coke will probably remain a record-breaking figure for several years. The developments which are now in progress in long-distance transmission of rural gas and in the utilization of volatile petroleum products and refinery gases for augmenting, city gas supplies may retard an other- wise accelerating demand for coke and coke-oven gas for domestic and industrial heating, Trends in Value of By-ProductsThe increasing value of by-products in comparison to the value of coke is shown in Figure 2. In 1913, the average value of by-product coke was $3.38, the value of the by-products per ton of coke was $1.41, and the cost of coal per ton of coke was $3,27, In 1929 not shown in figure) the value of the coke had risen to $4.80 per ton, the value of the by-products to $3.60, and the cost of coal per ton of coke to $5.07. The by-product values in were 155 per cent higher than in 1913, although the coke value had increased only 25 per And the cost of the coal 55 per cent. Actually the increase or the total value of coke plus by-products in this period was very little more than the increase in the coat of the coal, being 55per cent for coal and 60 per cent for coke plus by-products."

Mar 1, 1931

The Bayswater seam of the Singleton Coal Measures is discussed in relation to its field occurrence and related li~hotype profiles. The seam is correlated throughout widely separated areas of the Hunter Valley with the Farrells Creek seam at Howick, Broke seam at Broke, and Saddlers Creek seam at Mt. Arthur. The unusual features of composition of the seam in relation to adjacent seams is dealt with in terms of the seam environment, particular attention being given to the sandstone at the base of .the seam. Petrographic and other data are used to support the arguments submitted.

Jan 1, 1973

By M. Baumann

Introduction Gold Quarry is one of the largest gold deposits in Nevada, located along the Carlin Trend, approximately seven miles north of Carlin, NV. Owned and operated by Newmont Mining Corporation, as of December 31, 2005, Gold Quarry had produced over 13 million ounces of gold. Multiple simulations were constructed for gold and metallurgical variables using the Stepwise Conditional Transformation method. Analyses of these simulations have been used for a variety of purposes, including an assessment of uncertainty with various ore types. This assessment provides insight for improved modeling and reconciliation. Geological Framework Gold Quarry is a large, low-grade disseminated gold deposit hosted in Silurian-Devonian aged sediments at the Chukar/Alunite-Good Hope fault intersection. Gold bearing hydrothermal fluids appear to have migrated upwards along the Chukar/Alunite and Deep Sulfide Feeder faults and then moved outward along favorable stratigraphic horizons and structural intersections.

Jan 1, 2007

By L. Yuan, J. H. Rowland, D. Bahrami, R. Thomas

Blasting is the main method of production in many non-coal underground mining operations and produces multiple toxic gases as a result. The Mine Safety and Health Administration (MSHA) requires mine operators to measure the level of toxic gases in mines as frequently as necessary to ensure they are below regulatory safety limits. The current practice uses portable gas monitors to check the concentrations of toxic gases after a fixed post-blast time. This paper studies the application of a gas monitoring system in the return entry of a limestone mine to determine a safe re-entry time. The National Institute for Occupational Safety and Health (NIOSH) conducted such a monitoring program in a limestone mine from September 2016 through May 2018. NIOSH/PMRD (Pittsburgh Mining Research Division) is endeavoring to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions. This study showed that the use of gas monitoring in the return air can be a useful tool at the mine operator’s disposal to detect and reduce the risk of hazardous conditions and also to reliably estimate the re-entry time.

"Energy efficiency in mining and minerals processing has attracted considerable public and industry attention because of the significant quantities of energy consumption involved. In this context the question of what are worthwhile targets for energy efficiency improvements ought to be of the highest priority. It is however worth taking a step back to avoid falling in the trap of taking preconceived ideas that have been reiterated repeatedly before as gospel. The aim of this paper is to highlight areas where new or alternative approaches could potentially be the better way forward. Some may come as a surprise to conventional industry thinking. Ultimately any such solutions are attractive to practitioners not just in an environmental but also in an economic sense, and hence should be targeted through applied research and development efforts. This paper highlights key aspects of each group of opportunities and some of the individual approaches to provide an overview of the current status quo.MINING INDUSTRY POWER UTILISATION – WHERE IS THE BIGGEST BANG FOR THE BUCK?The question of where is the biggest bang for the buck when trying to determine worthwhile targets for energy efficiency improvements has not always been reported on broadly enough, typically because industry practitioners operate in specific areas of expertise and comfort zone. Looking beyond the familiar doesn’t always come easy. Any technology or methodology consideration to address energy efficiency needs to take into account the context of alternative opportunities of superior value or risks not achieving desired uptake. The following sub-chapters have been ordered by magnitude of improvement potential as best as is possible, starting with the biggest first, and the smallest last. Some may be a surprise relative to conventional mining industry thinking."

Jan 1, 2016

By Lei Pan, Venkata Atluri, Xuming Wang, Yuesheng Gao, Jan D. Miller

The wetting characteristics and water film stability at the talc surface have been studied, particularly the effect of polysaccharides such as guar gum, starch, and dextrin. Talc is a gangue mineral in the flotation of base metal sulfide ores, precious metal sulfide ores, and platinum group metal (PGM) sulfide ores. Talc surfaces were investigated using surface analysis techniques including atomic force microscopy, high-speed video bubble attachment measurements, and wetting film stability measurements using a synchronized tri-wavelength reflection interferometry microscope (STRIM). In the presence of polysaccharides, there is a significant increase in bubble attachment time at the talc surface, but only a slight change in contact angle, which suggests that polysaccharide depression of talc is due primarily to the slow rate of bubble attachment and not due to a change in contact angle. The critical rupture thickness (hc) for a hydrophobic talc surface was found to be 56 nm, while the hydrophilic phlogopite surface of similar structure has an equilibrium film thickness (he) of 25 nm. At low polysaccharide concentrations, the wetting films formed on the talc surfaces were unstable, but at high concentrations the wetting films became stable with similar thickness values as the critical rupture thickness, and bubble attachment did not occur. However, it was found that the critical and equilibrium film thickness values do not change significantly with the polysaccharide type or concentration. The results from this research help us understand further details of film rupture and displacement during bubble attachment.

By Sophia Wong

Nickel is used in a wide variety of applications from consumer goods to industrial uses. In many of these uses, nickel contributes to the environmental attributes of the product. The challenge, however, is measuring that contribution, comparing it to the environmental cost of production, and communicating the role of nickel to the customer in a way that is easy to understand. This paper presents the Nickel Institute?s approach to climate change as a global commodity industry association, and discusses where we stand with regard to some of these key questions. It also identifies issues for the nickel industry moving forward ? challenges that are likely to be common to other commodities.

May 1, 2009

By H. L. Barwood

Luminescence excited by electron bombardment, or cathodoluminescence (CL), is a very useful tool in petrographic examination of rocks, minerals and ores. Differences in luminescence colors and intensities allow detection and delineation of mineral species and composition zones difficult to separate visually by normal polarized light microscopy. The cold cathode CL chamber at Indiana University is used with a binocular microscope that has interchangeable attachments for a normal film camera, a digital camera and a fiber optic spectrometer. This allows imaging of the specimens as well as limited spectrographic analysis of the emitted luminescence. The chamber on this CL unit is large enough to accommodate several thin sections, polished mounts, grain mounts or rock slices at one time. Luminescence petrographic techniques were used to study alkali syenites and carbonatites from the Arkansas. Alkali feldspars in the syenites reveal a history of growth, fenitization and replacement through color and intensity differences. Primary orthoclase luminesces bright blue and is often zoned with a duller blue overgrowth of microcline. Fenitization of the feldspars is demonstrated by dull to bright red luminescence and replacement veins of albite often have a bright yellow green luminescence. Late microcline and perthites from the syenite pegmatites have a dull yellow to orange luminescence. Easily visible on this background of feldspars are grains of apatite (yellow), fluorite (violet), zircon (greenish), sodalite (orange) and mosandrite (green). Complex pseudoleucite syenites from Magnet Cove, Arkansas show similar minerals but also include xenolithic quartz (violet), manganwollastonite (bright orange), benitoite (intense blue) and lorenzenite (green). Carbonatites from Arkansas contain a wide variety of calcite textures and intensities of luminescence. Grains of carbonatite in well cuttings are easily distinguished from sedimentary calcites by their complex “flame” luminescence and the frequent presence of euhedral apatite grains (yellow). Apatite crystals separated from the Arkansas River Valley carbonatites by acid digestion show complex zoning. The cores of these apatites are yellow luminescing due to CL activation by Mn enrichment while the rims are violet luminescing due to REE enrichment. Complex zonation between the cores and rims is easily visible using CL.

Jan 1, 2001

By J. E. Cleveland

The major health concern for uranium miners is the release of radon gas and the resultant ingrowth of the short lived daughters in the mine atmosphere. Present methods of control are the utilization of mine ventilation systems for dilution and control of ingrowth time to maintain working levels below those set by regulations. This study examined pressure cycling efforts on the radon emanation. The mechanical ventilation systems were altered to allow pressure changes throughout the mine to increase radon influx during the off shifts and thus deplete the sources of radon gas. Continuous radon working level and environmental monitors, developed by the Bureau of Mines, were employed to monitor radiation and physical parameters in the mine workings. The mine ventilation system was then varied to induce radon flows during off shifts, thus, depleting the radon sources during normal production shifts. Electro-static precipitators were also tested to determine radon daughter collection efficiencies. Both radon and radon daughter concentrations were monitored and evaluated. Major problems were found in the simple mechanical operation of cleaning these units.

Jan 1, 1982

By D. Mohapatra

The possibility of using 2,2,4-trimethyl-1,3-pentanediol dissolved in tetrachloromethane as extractant for boron recovery is discussed. The parameters optimized for this purpose are contact time, boron concentration in the aqueous phase, extractant concentration, equilibrium pH and phase ratio. NaOH is used as stripping agent for boron recovery from the loaded organic phase. Boron extraction is found to be a slow process (equilibrium time 20 minutes) compared to boron stripping, which is reasonably fast (equilibrium time 5 min). Maximum boron extraction is possible at a broad pH range from 1.0 to 6.0. Using 1.0M extractant concentration, a 1:1 phase ratio (organic: aqueous) and two stages, ~99% boron extraction is achieved. More than 97% boron stripping is possible using 0.5M NaOH at a 1:1 (organic: aqueous) phase ratio in two stages. Overall, a 95.6% boron recovery was achieved. Loss of solvent into the aqueous phase and co-extraction of Ca, Na and K into the organic phase at higher equilibrium pH are two major concerns in his process.

Jan 1, 2008

THE Wonthaggi coal-field lies south easterly from Melbourne at a distance by rail of 86 miles, on the flats of the Powlett River, immediately to the south of the deep-cut valleys and steep intervening ridges in the Jurassic rocks of the Bass Range and itsfoot-hills. The coal-bearing area is covered with a thin layer of late Tertiary and Recent deposits, which serve to mask the true character of the underlying coal-bearing rocks and effectually prevent the appearance of any coal outcrop. Two or three bores sunk prior to 1890 had shown the locality to be really a potential coal-bearing one. Only one additional bore was sunk in the State Coal Mine area until 1908, when energetic boring was resumed, with the result that in November, 1909, when an acute shortage of black coal in Victoria resulted from the prolonged strike on the New South Wales coal-fields, coal-seams had been located at Wonthaggi offering sufficient inducement to start an...

Jan 1, 1918

By George C. Heikes

ALTHOUGH the application of light metals in war materiel increased during the year, based on the number of uses, the trend in aluminum and magnesium production in 1944 was characterized by a sharp decline in the production of both metals accompanied by a further accumulation of large Government reserve stocks. Several primary reduction plants were curtailed to prevent building excessive inventories. By the end of the year, however, a lively revival of war production took place when resistance stiffened on the western front in Europe. Production of primary aluminum ingot was reduced from over 90,000 tons per month at the start of the year to 45.000 tons per month by the end of the year.

Jan 1, 1945

By J. Dubinski

Underground mining of copper ore in the Legnicko-Glogowski Copper District basin generates a number of seismic events, whose energy often exceeds 108 J (Butra, 2010). The number of tremors and their location shows that the area of rock mass involved in the deformation and failure processes significantly exceeds the area of mining operations. Locations of seismic foci of high energy tremors, as well as the aftershocks that accompany them, extend hundreds of metres, confirming that processes to restore the energy balance of rock mass occur in a short amount of time and over a wide area. Thus, an area of similar size should be considered in predictive analyses of the tremor?s position. It should be emphasized that a large portion of the rock mass still has a level of freedom resulting from the way the rock mass is held together and its geometric continuity. This level of freedom is dependent on the scale and duration of mining, the number and size of natural structures, and rock mass pressure, including gravitational pressure constricting individual fragments of rock mass in the area (Burtan, 2012). It can therefore be assumed that in real conditions, areas where mechanical strength of the layers has been exceeded may be located a considerable distance from each other and do not necessarily need to coincide with the working area location. In this sense, a rock mass influenced by mining exploitation is essentially a rock mass in which numerous fragments with concentrated energy exist simultaneously. Energy will be released within these rock mass areas each time rock mass strengths are exceeded by the induced stress changes related to mining operations. This paper presents a discussion on how to predict the location of seismic activity areas based on a change of position of seismic energy equivalents. This parameter is calculated for a given set of seismic tremors with defined foci coordinates. For a given set of seismic tremors, the location of seismic energy equivalents may be used for predicting the location of high-energy seismic events.

Aug 1, 2013

On Dec. 20, 2013, an 8-m (26.2-ft) diameter Robbins hybrid single shield/earth pressure balance tunnel boring machine (EPB TBM) was launched to bore the Grosvenor decline tunnel for Australia?s Anglo American coal mine. The machine was built using onsite first time assembly (OFTA) in order to fit within a tight project schedule. Assembly at the remote jobsite near Moranbah, Australia took about four-and-a-half months, and then the machine was walked down into a launch tunnel. Two decline tunnels, at grades of 1:6 and 1:8, will be used for mine access to new coal seams. The hybrid machine is tackling mixed ground conditions ranging from sand and clay to varying types of sedimentary hard rock up to 120 MPa UCS, as well as coal seams. Methane gas is expected to be present throughout the tunnel, so the machine has been designed as explosion-proof-compliant to ERZ-1. ?Grosvenor is the first underground coal mine in Queensland to use a TBM for drift construction,? said Glenn Tonkin, Grosvenor project director. ?We are proud to be pioneering this technology.? Only about 300 m (984 ft) of ground in each decline tunnel is expected to require EPB mode, while the rest of the tunnel will be bored in hard rock mode. Thus, the design was optimized toward hard rock excavation.

A commercial Philips X-ray Fluorescence (X.R.F.) analyser was converted to an experimental instrument suitable for determination of the accuracy to be expected of X.R.F. on line analyses of concentrator slurries. Problems with stability of slurry sample presentation were eliminated by a number of minor modifications.By the use of multiple linear regression techniques instrument calibration equations including error terms were determined for copper flotation feed slurries. Results indicated that the accuracy of copper and iron analyses of flowing slurry samples could approach that of static pressed powder samples.Possible means of reducing the error terms to a level of at least that of pressed powdel' samples involve alternative methods of compensating for the per cent solids in the slurry, Design is under way for installation of a plant unit.

Jan 1, 1968

Models are used in engineering to reproduce reality as faithfully as possible so that the expected response of a system for given actions or inputs can be determined. In the field of rock engineering, both empirically based and numerical models are widely used to determine the likely response of the rock surrounding excavations. Many of the empirical models are developed from statistical analysis of case histories or from direct observation; however, empirical models are limited because they should be used only within the range of conditions of the observational database. Synergy exists between empirical and numerical models, because empirical models can be used to calibrate and validate numerical models. The empirical approach can benefit from the capability of numerical models to investigate specific mechanisms, which would not be possible using observations alone. Two cases are presented in which the synergy between empirical and numerical models is demonstrated. The first case examines the analysis of discontinuity effects on the strength of slender pillars in limestone mines, and the second case evaluates the effects of stress orientation on coal mine entry stability. It is concluded that numerical model calibration and verification comprises an important first stage in the successful application of models in rock engineering design. Application of numerical models allows mechanisms and interactions of various parameters to be analysed, greatly improving the understanding of the system. The improved understanding can be used to extend the application of empirical design methods, resulting in improved safety and efficiency of rock engineering designs.

Jan 1, 2014

By Keith Bowers, Frank Mimnagh, Eddie Woods

The CTRL London Tunnels The Channel Tunnel Rail Link (CTRL) London Tunnels comprise 36km of internal diameter bores that were driven by Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs). The tunnels were constructed between the autumn of 2002 and the spring of 2004. The permanent works also included the 1.1 km long station box at Stratford, five ventilation shafts of depths between 30 and 54 m, 29 cross passages and various large diameter sprayed concrete lined connecting tunnels. The tunnels were driven under densely populated areas of north and east London, as depicted in Figures 1 to 4. Under the parliamentary CTRL Act the project had obligations to make

Jan 1, 2005