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By B. Mishra, Rahul Mohanty, Swati Mohanty, Swagatika Dash

Wet high intensity magnetic separators have been widely used in the mineral industry for separation of mineral particles based on magnetic properties. Usually, magnetic separators employ ordered array of grooved plates such as Lenoir and Jones plates onto which the magnetic particles get attached in the presence of a magnetic field. In the present work, we have carried out computational fluid dynamic (CFD) simulation, using Eulerian-Eulerian model to study the flow dynamics of magnetic and nonmagnetic particles within a matrix consisting of 2 mm size spheres of magnetic material, which are interconnected by wires, in the presence of a magnetic field. The three phases considered were the water, magnetic particles and non-magnetic particles. Model equations were developed considering each sphere in the matrix as a magnetic dipole, and the strength of the magnetic field at any point in the domain is due to all the dipoles. The size of the magnetic and nonmagnetic particles was 45 and 40 micron, respectively. The feed consisted of a slurry having 25 wt. % solids. The volume fraction of the magnetic particles was 0.04, and that of the non-magnetic particles was 0.045. The simulation was first carried out without the imposition of the magnetic field till a steady state was reached, and then the magnetic field was applied. The magnetic particles, as they flow down the matrix were attracted towards the region of maximum field gradient, which was in the central region of the matrix. A symmetrical pattern in the upper half as well as the lower half of the matrix was observed. As the particles moved downwards, the pattern changed, and near the outlet, most of the particles were found to flow out from the central part of the plane. This study can lead to a better design of a magnetic separator.

Jan 1, 2014

By Hazel Lyman Nickel

Daring to try where others had failed, Herbert and Lou Henry Hoover translated from the Latin the principal (and first) textbook on the mining and metallurgical profession, De Re Metallica, 1556, which had been in use for two centuries and then had lain dormant for 350 years in a language unreadable except by a chosen few. Thus the Hoovers enriched the English tongue with a vitally important contribution to history in the fields of mining, metallurgy, and chemistry. To them it was a joint hobby, because they were actively interested in the beginnings of the mining profession in which they had both been trained. Illuminating the years of toil to perfect this translation shone their ideal of service to humanity, since, in the Preface, they refer to their task as "a labour of love", which had to find the moments for its execution in night hours, weekends, and holidays, extending over a period of about five years. And they add: "If the work serves to strengthen the traditions of one of the most important and least recognized of the world's professions, we shall be amply repaid". While a student at Stanford University, during the years of 1891-95, Herbert Hoover had become familiar with a copy of this Latin mineralogy classic, De Re Metallica, a rare book in the private library of Dr. John C. Branner, at that time head of the department of geology and mining. Another Stanford student in geology was also examining and studying the ponderous volume of twelve 'books'. She was Miss Lou Henry, of Monterey, who graduated in 1898, and the following year became Mrs. Herbert Hoover. Interwoven through the tapestry of their life experiences gleamed the silver thread of their interest in this mediaeval Latin textbook. Just nine years lacer, the Hoovers had commenced their translation, while they were in temporary residence in London after the seething years in China under the shadow of the Boxer rebellion.

Jan 1, 1949

Potential hlghwaJl mining reserves in Australia are large, but geotechnical and operating conditions are quite different from those where highwall mining has evolved in the USA. In order to achieve safe and effective resource recovery, equipment and procedures should be developed to penetrate 250 m in the Australian mining environment. This paper identifies key auributes to be incorporated in such machinery and methodology. These suggestions are intended to promote discussion on innovations to satisfy Australian requirements for highly productive, safe and environmentally acceptable techniques.

Jan 1, 1993

By D. R. Knowlton

IF I were a minister, and this were a sermon, and such a passage appeared in the Bible, I would choose for my text: "From whence cometh the oil for our war?" And no preacher was ever more serious than I am. You petroleum engineers recognize that the producing branch of the industry is passing through an era of plenty and inflated potentials into an era of scarcity and unmet allowables. Not too long ago the oil operators of Kansas, California, and Texas were appearing before operators' meetings and regulatory authorities asserting that these States were capable of producing at rates far in excess of what the demand at that time would absorb. Today every oil-producing area in the United States except the Texas Gulf Coast and West Texas is producing close to or in excess of its maximum efficient rate.

Jan 1, 1943

By V. C. Pandolfelli, L. Paulino, C. E. Zangiacomi

The continuous improvement in aluminum industry over the last years has increased metal output at lower cost. The potlining plays an important role in this regard due to high cost involved and more recently in its environmental aspects. In order to increase potlife and thus minimize the aluminum cash cost, a systemic approach is needed, through investigating the main cathode failure mechanisms by using a pot autopsy as a powerful tool, and then making the necessary chances to achieve extended potlife. In addition, preheating and pot start-up may also damage the cathode if not performed with an appropriate technique or even if the lining materials are not specified correctly, among other factors. All these aspects will be presented and discussed in this paper. Increased potlife, especially now that the current is reaching values up to 300kA, will allow aluminum plants to match their goals more efficiently at lower costs.

Jan 1, 2006

By J. Golamnejad

This paper attempts to model long-term production scheduling problems by chance constrained binary integer programming in a stochastic environment. This stochastic model is set up to account for ore block grade uncertainty. The probability distribution function of grade in each block is used as a stochastic input to the optimization model. This distribution function in each block should be determined using a Geostatistical Simulation approach. The deterministic equivalents of these chance constraints are then achieved, which are in the form of nonlinear in binary variables. A confidence level at which it is desired that the uncertain constraints holds, is specified in each scheduling period. Rather than the previous risk-based model, this formulation will yield schedules with a high chance of achieving planned production targets while maximizes the expectation of net present value and minimizing the variance function simultaneously. Using this method, the grade uncertainty is integrated explicitly into the optimization process.

Jan 1, 2006

By R Wynn, N Stoitis, R A. Lauten, H Liang

At the Century mine in North West Queensland, MMG produces lead and zinc concentrates. The current production rate is close to 500 000 t of zinc per annum. Graphite is the main gangue in the orebody and a substantial quantity of chemicals are used to achieve an acceptable depression of graphite and other gangue materials in the current operation. In the future, it is anticipated that the content of graphite in the orebody will increase while the zinc grade will gradually drop. This scenario illustrates the importance of an optimised suite of flotation chemicals to maximise concentrate grade and recovery. As an alternative to the current reagent suite where dextrin is used to depress graphite, laboratory test work and subsequent plant trials were conducted with alternative depressants. These depressants facilitated both graphite depression and elevated zinc grades in the rougher concentrate. As an added benefit, it was also observed that the silica content in the zinc concentrate was reduced in the presence of the biopolymer selected for the plant trials. Results from both laboratory tests and plant trials will be discussed to illustrate how this change of reagent suite improved flotation yield at the MMG Century Mine.CITATION:Wynn, R, Lauten, R A, Liang, H and Stoitis, N, 2014. A change in graphite depressant to improve the recovery of zinc at MMG Century mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 179–186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Steven J. Schatzel

A study was made of frictional ignitions in the underground coal mining industry from 1980 to 1992. The population of frictional ignitions was correlated to a variety of potential contributing factors including the mined coalbed, geographic location, mine production, methane gas emissions, and the type of mining equipment in use. The number of frictional ignitions reported in 1991 and 1992 surpassed the annual totals in all previous years included in the study. Most frictional ignitions occur during cutting operations at a coal face by a continuous miner. The average coal production of mines experiencing frictional ignitions is greater than the average of all underground coal mines throughout the survey period. Methane drainage may have produced a drop in the ratio of gas emissions to coal production (E/P) in mines experiencing frictional ignitions.

Jan 1, 1995

By Albert D. Brokaw

THE accompanying chart was devised to provide a rapid and simple method of correcting for temperature and compressibility (deviation from Boyle's law) of gas under relatively high pressures and temperatures, such as are encountered in many deep reservoirs. The chart was prepared by interpolating for the desired values in the experimental data of Burke and Keyes1 and Kvalnes and Gaddy2 on the compressibility of methane, after adjusting their results from 0°C. to 60°F. and combining the correction factors for compressibility and temperature into a single multiplier, which, applied to the product of pressure and reservoir volume, gives at once the volume at one atmosphere (14.7 lb. per sq. in. abs.) and 60°F. The relationship 0f this multiplier to the compressibility factor Z, as used in most discussions, is simply: [Multiplier = 460° + 60°ZT –] where Z is the compressibility factor and T the absolute temperature (Rankine). Fahrenheit temperatures are shown on the vertical axis and pressures in pounds per square inch absolute on the horizontal axis. Correction factors or multipliers at intervals of 0.05 from 0.55 to 1.40 have been plotted on the chart and are calculated t0 give volume of gas at one atmosphere pressure (14.7 lb.) and 60°F. The operation is as follows: The reservoir volume, times the number of atmospheres pressure, times the multiplier, gives the volume of gas measured at one atmosphere (14.7 lb. per sq. in.) and 60°F. For example, a reservoir is estimated to have a volume of 10,000,000 cu. ft., bottom-hole pressure is 2940 lb. per sq. in. and temperature is 184°F To make the correction for methane, follow the 184° line horizontally to the 2940-lb. pressure line. The intersection lies between the 0.85 and 0.90 correction lines, and by interpolation we may estimate the multiplier at 0.863. The computation is simply: [ ] Using the chart for methane prepared by Prof. G. G. Brown3 and his associates, the multiplier is found to be 0.867. Details 0f computation are as follows: Correction factor to apply to PV to correct for deviation from Boyle's law and adjust to measurement basis of 60°F.: [ ]

Jan 1, 1941

DCF Valuations are very important to individuals and companies involved in the mining industry. Such valuations are critical to investment decisions in relation to new and existing projects. In particular they provide fundamental information to shareholders in the event of a capital raising or takeover and to financiers supporting mining companies and projects. Also, DCF Valuations are often used to support asset carrying values in the financial statements of mining companies. This paper presents a Chartered Accountant's (CA's) perspective on the main issues to be considered in preparing, analysing and relying upon DCF methods in mineral valuations and provides some practical examples relating to key issues. The paper makes the important point that DCF methods involve making assumptions about future events and circumstances that inherently contain uncertainty which results in a valuation prepared on a DCF basis providing a range of values that are not perfect or accurate. In order that DCF valuations provide meaningful information the underlying methodology used and assumptions made must be consistent, sound and well supported. Credibility of those involved in preparing mineral valuations is vital and this paper supports the adoption of sound practices by all concerned.

Jan 1, 1994

By N. Kumar Kittusamy

By J. E. Dutrizac

The mineral forms of silver, lead and cadmium in the zinc concentrates and the various roaster products made by the Kidd Creek Division of Falconbridge Inc. have been elucidated. In the concentrates, all three elements occur mainly in sulphide form, either in solid solution in the principal ore minerals or as discrete mineral grains. During roasting, Ag, Pb and Cd are preferentially concentrated in the hot cyclone and ESP dusts of the roaster train. Silver is converted to <0.5 µm grains of silver metal and to Ag2S04 which dissolves in or impregnates silicates. Lead is converted to Pb-bearing silicates or to PbS04 and PbO which are present either as tiny free grains in ZnO or as an intergrowth with lead silicate. Lead is also a minor constituent of the ferrite phase. Cadmium occurs mostly as cadmium-bearing zno and ZnFe2o4 , but a significant amount also reports as Cd-bearing silicates or zinc sulphate.

Jan 1, 1990

By A. J. Weinig

NEED for some simple method of determining tonnages in mill circuits has always been felt by operators and consultants alike. To meet this demand the following method was evolved and has been found accurate and practical after considerable testing on various mill flows. The essence of the method is to add a chemical at a uniform rate to a mill flow, such as a launder conveying pulp, and then determine the concentration of the added chemical in a sample of the pulp. From this procedure the tonnage can be calculated. Common table salt has proved the most satisfactory chemical for ordinary conditions. It has many decided advantages for use in tonnage determinations, among them being the following:

Jan 1, 1933

By R. C. Hubli

A chemical model has been developed to investigate the dissolution of sulphide minerals in brine solutions containing copper and iron chlorides. The model has been employed to study the dissolution .of synthetic NiS using different initial concentrations of Cu(II), Cu(I), Fe(III) and temperature. The speciation of copper with particular reference to the formation of hydroxy-chlorides as a function of total chloride and H+ has been computed. The model predictions are in agreement with experimental results. It has been found that addition of Fe(III) results in the maintenance of a high Cu(II)/Cu(I) ratio leading to enhanced rates of dissolution and suppresses the loss of Cu(II) due to the formation of hydroxyl-complexes.

Jan 1, 1997

By Edgar Stanfield

Since April, 1923, the Scientific & Industrial Research Council of Alberta has had an analyst, Mr. W. P. Campbell, steadily employed analyzing coal samples taken by the provincial Mine Inspectors. Mr. Campbell has also analyzed a number of coal samples taken by one of the Council&apos;s Geological Survey parties. We have thus, at the time of writing, over four hundred analyses of Alberta coal, made by the same analyst, and strictly comparable. These samples come from widely distributed points, some 88 townships being represented. The stream of samples is still flowing in, and it is hoped by the end of this year that the number of townships represented will be increased at least fifty percent. The time has arrived to publish some of the data collected; but it must be clearly understood that this is merely a progress report, subject to revision as further information is obtained. Three hundred and fifty-three coal mines in the province were operated during 1923. The production per mine varied from 5 up to 500,000 tons. With this number of mines to examine (and fresh mines are being opened every year) it is a large task to make even a proximate analysis of representative samples from every mine. Any chemist will appreciate the fact that to make ultimate analyses representative of even the larger mines will be a long and tedious task. It has seemed better to make a comprehensive survey by proximate analysis and determination of calorific value before beginning the more thorough survey by ultimate analysis. This paper, therefore, deals only with proximate analyses and calorific values; and, owing to limitations of time and space, does not deal with other chemical and physical characteristics of coal, such as storage quality and fusibility of ash, important though these are.

Jan 1, 1925

By A. Hayatdavoudi, K. G. Sawant, F. Boukadi

"In this work, we found that contact between shale and water results in development of micro fractures. Based on results of experiments on Pierre shale, we conclude that appearance of micro fractures begin with saturation of capillaries, ionic and diffusive transport of water into the shale clays and once capillaries are saturated, the cause of micro fracture propagation is the conversion of ionic activity/exchange to excess pressure that did not exist before fracking. Based on these findings, the spread of micro fractures appear to be a time-dependent phenomenon which has not been addressed in the existing macro/micro fracture models.INTRODUCTIONShale has often been involved as a hazard in drilling operations. This hazard can be defined as “destabilization” of shale. When contacted with water-based drilling fluids, some shales readily swell and sometimes, cause the wellbore to cave-in, slough, wash-out, close, and pack-off, impeding the drilling by sticking the drill-pipe. However, once drilling reaches the desired depth or length, the casing is set, cemented, and perforated, and then actually we wish to initiate fractures and destabilize the shale formation, using hydraulic fracturing.Clays constitute a major portion of minerals in shale. These clays contain a large amount of free energy which is the main factor for “slick” water adsorption/absorption. In fact, the reason for using “surfactants” in hydraulic fracturing fluids is to make the penetration of the fluid into the capillaries much easier, thus water meets with less resistance to enter the small capillaries. Also, the result of high capillary suction pressure is due to small Angstrom size capillaries, smaller pores and presence of ions and hydrateable metal atoms. The free energy is thus, related to all the above mentioned and other affects. Capillary pressure, osmotic pressure and other pressures are responsible for creating the micro-fractures in shale, thus, increasing the network of micro-fractures which leads to more gas production. The objective of this study is to evaluate the pressures of the individual ions which are released by the diffusing “slick” water into shale. These pressures would be added to the above mentioned capillary pressure, osmotic pressure, bacterially-induced pressures, chemically-induced reaction pressure, pressure due to exchangeable ion-transport, pressure due to release of free energy of solvation and eventually to the pore pressure as suggested by Terzaghi’s equation."

Jan 1, 2015

Results obtained from small scale tests using Australian tin concentrates indicate that metallic tin containing less than 0&#183;1 per cent iron can be recovered by a two-stage process using hydrogen and make-up chlorine. In the first stage the concentrate is ground,. pelletized, roasted, and reacted at 650&#176;C with HCI and H2 to volatilize the tin as SnOI2. The volatilization reaction is conducted with cocurrent gas and solids flow because it was found that the use of cocurrent flow yielded a solids residue substantially free from FeCI2. The second stage uses a technique termed &quot;reflux reduction&quot; during which the SnOl2 produced by volatilization is reduced by hydrogen to form tin and a gas containing HCI and H2 of sufficiently high HCI tenor for recycle to the volatilization stage. The elimination of tin ranged from 98+ to 99&#183;7+ per cent of the tin from concentrates containing 5 to 50 per cent tin, respectively. The process should be capable of continuous operation, and a tentative calculation has shown ,that a treatment rate of 12,000 tonnes of tin concentrate per year could be obtained in a volatilization reactor 1&#183;1 m in diameter and 6&#183;1 m high. The process may have particular application to finely divided concentrates containing less than 20 per cent tin.

Jan 1, 1974

By Ana E. Bohé

Chlorination process is an attractive and efficient method for the metal recovery from complex materials. The process that is performed at high temperatures, allows converting all the metals contained in the material into their respective chlorides which are further separated in a selective way. Aluminum metal matrix composites with discontinuous ceramic reinforcement of short fibers, whiskers, and particles have been gaining wide acceptance as an important engineering material in automotive, aerospace, and electronic industries. Since the ceramic reinforcements are still quite expensive and contribute significantly to the final cost of composite materials, the feasibility of their recovery from the manufacturing scrap and further recycling is a factor of increasing economic interest. In the present work, a theoretical and experimental study is given for the recovery of Al2O3 and SiC particles and short fibers from three commercially available aluminum-matrix composites produced by molten metal mixing route. The process consists of transforming the constituents of metallic alloy matrices in gaseous chlorides that are dragged by the gaseous stream, while the ceramic reinforcement remains as a solid residue in the reaction bed.

Jan 1, 2006

By R C. A Minnitt

This paper illustrates the use of variography and moving average plots as an aid to analysing variations in the process that can be used to direct the improvement efforts. The hydrometallurgical processes used in manganese metal production consist of sequential unit operations that include milling and reduction of manganese ores. Leaching of the reduced ore, is followed by solid-liquid separation, residue disposal, solution purification and electrowinning of manganese metal completes the process. The nearly 250 integrated process control loops rely on reports of pH, flow pressure, level, temperature and chemical analyses. Metallurgical accounting, reconciliation and process control is achieved through monitoring of the chemical and mass balances within the manganese reduction plant, requiring approximately 50 000 analyses of solids, powders and liquids each month. The largest numbers of samples are taken in the cell house. Changes and variations monitored by sample statistics ensure that the manganese products comply with predetermined specification limits. Optimising the information-value of the approximately 50 000 samples in the manganese plant is carried out in tandem with ongoing process optimisation. Variographic analysis of daily sampling data suggests that the cyclical behaviour evident in the moving average plots is only a reflection of random residual variability and not a reflection of true underlying variability related to cyclical phenomena. Low resolution in the variogram of daily sampling data masks the short-range variability that emerges when hourly data are analysed. Hourly samples collected over a 39-day period (giving 941 sample data), helped identify short-range cycles in the process. The relative distribution of variability for daily sample intervals, indicate that 57 per cent arises from V[0], 18 per cent from V[process] and 16 per cent from random residual variation. V[0] includes all the uncontrolled sampling error arising from a poor sampling protocol, the fundamental error (FE), the grouping and segregation errors (GSE), the delimitation error (DE), the extraction error (EE), etc. This confirms the suspicions regarding the suboptimality of the sampling protocol and the way it is implemented. The absence of long-term trends in the leach suggests that short-term variation (less than one day) dominates the process. While the control charts indicate that the overall processes are maintained above the lower specification limits and the target values, there is nevertheless a considerable amount of variability in the system that overhangs the processes and threatens to impact them negatively. Although the variability in the leach is above the prescribed limits, the volatility is a matter of concern because it seems to be uncontrolled. The comparison of the various sources of variability in data collected on an hourly basis suggests that the short-term random variability (V[0]) accounts for almost 50 per cent of the variability in the process. The main source of this variability is due to errors in the sampling protocol and is probably related to the size of the fundamental error (FE), the grouping and segregation errors (GSE), the delimitation error (DE), the extraction error (EE), etc. Remediation of FE and GSE will probably lead to a reduction in V[0], whereas V[process] could be mitigated by reducing the biases associated with DE and EE in particular.

Jan 1, 2008

By S. H. Brown

In our work as health physicists*, we do a lot of public speaking and interaction with the public on issues related to development of uranium mining and milling (?uranium recovery?) in the US. Understandingly, the public has important concerns about this. Accordingly, this paper is presented in a ?question and answer? format in which we have tried to capture what are some of the most common concerns we hear from citizens and address them. We have attempted to do so based on the best scientific information we have, representing information well documented in peer-reviewed scientific literature and consensus positions from both national and international scientific standard setting bodies and related committees. We have included some of the more important of these scientifically-based references to support the information provided. Practical space limitations prevent completeness in this regard in some cases. Visit the Health Physics Society?s web site or feel free to contact me directly for additional references, information or detail ? Steve Brown. The health physicist?s primary objective is to manage the beneficial uses of ionizing radiation while protecting workers and the public from potential hazards. For more information on what a health physicist is and on the Health Physics Society, visit the Society?s web site at www.hps.org.

Feb 23, 2014