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By G. P. Cooper

A comprehensive computational heap leach model was used to evaluate options for operating a chalcocite-ore heap leach process. The stockpile leach model is based on the computational fluid dynamic software framework PHYSICA+ and incorporates various physical and chemical phenomena to simulate fluid transport, mineral reaction kinetics, bacterial effects, and heat, energy and acid balances for the overall leach process. The leach model is calibrated against small-scale column leach tests, and simulation results are validated against closely controlled column pilot-scale tests. For a given set of ore conditions, the effects of raffinate irrigation rate are examined. Several options for pulse leaching were investigated, and the effects on copper recovery and pregnant leach solution (PLS) grade are described. Model simulations indicated that pulse leaching could be used to control copper grade of the PLS. Finally, an analysis of inventory issues is presented for various lift heights including multi-lift simulations to examine potential operating options. U sing irrigation rate, raffinate copper grade, and lift height as variables in a factorial design of experiments, the simulations showed that raffinate copper grade is the main factor that affects the soluble copper inventory grade.

Jan 1, 2007

In the investigation described here, it was found that the main effect of temperature is on the rate of flotation, and that adsorption of the reagent is not rate controlling. Above 10°C, the flotation rate of pyrite and gangue increases almost exponentially with a rise in temperature. Below that temperature, the flotation rate of pyrite shows a sudden marked decrease, that of gangue increases, and the sulphur grades are significantly poorer. In the flotation of pyrite, the mass transfer of the pyrite from the pulp to the troth is thought to be the ratecontrolling step, whereas the flotation of gangue is controlled by the combined effect of the stability and velocity of the froth and the viscosity of the elutriating medium. The latter is probably the controlling effect at temperatures below 10°C. Little difference was noted in the recoveries (provided no time limit was set) with changes in temperature; hence adequate recoveries can be obtained at Iow temperatures by the introduction of longer residence times for the pulp. The adverse effects of Iow temperatures on grades can be overcome only by additional cleaning or by heating of the pulp.

Jan 1, 1984

By K. F. Veit, R. L. Marovelli, T. S. Chen

There is an error at the bottom of the right-hand column of p. 11, and the top left-hand column of p. 12. The first paragraph of the section EXPERIMENTAL RESULTS should read: "Thermal shock tests were conducted on circular discs of basalt, quartzite, and taconite. Average grain sizes ranged between 0.10 and 0.25 mm. Individual discs were tested only once, either in a cooling or heating shock. Several discs of the same rock type were shocked at a temperature, and the temperature level then was increased for another test by 10° to 20°F until complete fracture occurred when a specimen was quenched. The minimum temperature difference required to initiate cracking, TmiN was observed and used, together with other property values, to compute the dimensionless stress o*max . The observed ?Tmin for cooling shock in different media is tabulated in Table I. The property values E, St, a, and K are shown in Figs. 6, 8, 10, and 11, respectively. Discs of various rocks shocked in different isothermal baths gave o*max values for a wide range of Biot numbers. These o*max values were then compared with the theoretically predicted values."

Jan 1, 1968

By D. P. Fenton

The Phelps Dodge El Paso Rod Mill produces approximately 2.4 million pounds per day of copper rod from a casting and rolling operation. The newly formed rod is treated to remove mill scale and oxides using a sulfuric acid and hydrogen peroxide solution which is bled periodically when the copper concentration reaches 30-35 g/L. The bleed solution is heated to 75° C to destroy the residual peroxide. Copper is then recovered in a 270 cell EMEW electrowinning plant. Clean acid is also regenerated in the EMEW plant and is returned to the rod cleaning circuit. The EMEW plant commissioned in January 2006, has two operators and replaces a copper sulfate plant with fourteen operators. The EMEW plant has a capacity of 1700 kg/day of cathode copper at 2.1 kWh/kg copper deposited. The electrowinning plant operates in closed circuit with the rod mill returning up to 2600 kg/day of sulfuric acid resulting in zero discharge. Use of dimensionally stable anodes (DSA®) ensures that the acid quality is maintained in the closed loop operation. The operating conditions, performance and plant experience of the EMEW copper and acid recovery plant are discussed.

Jan 1, 2007

By L. W. Scott, T. H. Dubaniewicz, F. T. Duda, P. G. Kovalchik

Recent research conducted by NIOSH, Pittsburgh Research Laboratory showed that electrical current levels permitted under parent regulations may not limit cable temperatures to less than 90 °C in reeled trailing cables. Reeled cables, tightly wrapped with many turns, ell carrying current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften and become easily damaged. The damaged insulation reduces the life of the cable and can lead to shock, electrocution, and mine foes. This paper describes a method of measuring the conductor temperature of untie trailing cables during no anal operation. The temperature is measured using a 50/175 micrometer Graded Index Multimode Optical Fiber located in the center of the metallic conductors. Distributed temperature measurements arc made using an Optical Time Domain Reflectometer (OTDR). This system is capable of measuring temperature with an accuracy of plus or minus one degree centigrade over a length of 4 km at 1-m intervals. With this unique way of measuring temperature, tests can be conducted simulating actual mine conditions and provide important data to allow MSHA's Approval and Certification Center to develop approval criteria for cyclically rated reeled machines.

By T. Sterry Hunt

I HAVE lately had occasion to examine sulphuretted ores of bismuth' both from Tudor, Ontario, and Latete, New Brunswick. The former consisted chiefly of bismuth-glance, carbonated at the outcrop, and within associated with some metallic bismuth, iron-pyrites and graphite, in a quartz gangue. In the second locality, where it appears to be present in considerable quantity, the veinstone is also quartz, but the associates of the bismuth-glance are chalcopyrite and galena. The treatment of such mixed ores in the furnace for the extraction of the bismuth could yield only a very impure product, and in view of the high price of the metal I tried with success a wet method for the treatment of the ore, which is based on well-known chemical reactions, and may, in some cases, be advantageously used. The pulverized ore is dissolved by heat in commercial nitric acid, and the remaining gangue washed by displacement, first with a little strong acid (which is used to attack a fresh portion of ore) and then with a moderate quantity of water, which is added to the first solution. This, if the excess of acid be considerable, may be partially

By L D. Meinert

Skarns typically are zoned and the deposit- or district-scale zonation pattern is an important tool in exploration for skarn deposits. Zonation in individual deposits has been described in many publications, and the general zoning patterns have been summarised by Einaudi, Meinert and Newberry (1981), Meinert (1997), and Meinert, Dipple and Nicolescu (2005). Although zonation is present in most skarns as the result of a basic process of transferring heat and fluids from magmas to wall rocks, the specific zoning pattern in each skarn may vary greatly. For example some zones may be missing entirely or multiple zones may be telescoped. Such variations can be caused by several factors including depth of formation, magma composition, timing of the exsolution of magmatic aqueous fluids, redox state of the magma and redox state of the wall rocks. To use zonation as a predictive tool in skarn exploration, all the controlling factors have to be considered. In this study, we discuss some of the factors that may affect the zoning patterns in Ca skarns. Magnesium skarn has dramatically different mineralogy and is not discussed here. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Contribution by G. Narsimhan It was with much pleasure that I went through D.F. Malan's excellent paper. The following explanatory and critical note has been the result of my deep study of the paper. Although by qualifications and experience I have been a chemical engineer, involved over four decades with problems in the modeling and simulation of transport-limited (heat and mass) chemical reactions in multi-phase systems, I have of and on interested myself in challenging problems in extractive metallurgy. This is the first time I have veered of to continuum mechanics, at the age of 71! Author's reply. I thank Professor Narsimhan for his extensive contribution to the paper. It provided me with the stimulus to derive an extended model. However, there are some inaccuracies in his arguments that need further discussion. Professor Narsimhan's main concern is that there is not a good enough fit between the derived viscoelastic Kelvin model and the experimental data supplied by Güler1 (see Figure l1 on page 218 of my paper). I will therefore explain the choice of a viscoelastic model in more detail and also make specific comments on the arguments given in his contribution.

Jan 1, 1996

By T. Prof. Egleston

DURING the last winter we have been actively engaged in the School of Mines in search for boracic acid. This has been owing to the fact that Mr. M. W. Iles, assistant in the qualitative laboratory, has discovered a test for that substance which makes its discovery exceedingly simple instead of being, as previously, very difficult. It consists in powdering the mineral, calcining it, then moistening it with sulphuric acid, and heating on a platinum wire until the sulphuric acid is expelled. It is then moistened with glycerin and made to take fire. If boracic acid is present it infallibly gives a green flame. It is not at all surprising, under such circumstances, the test being so easy, that boracic acid has been found by the students in a great many cases where its presence was not previously suspected, and in some where its detection was previously too difficult to warrant looking for it. We were not prepared, however, for its discovery in Lake Superior iron ores, and were disposed at first to think that a mistake had been made. After, however, it had been frequently reported in these ores it was considered worth while

Jan 1, 1877

By R. V. Ramani, P. M. T. White, D. Sutton

3.1 Criteria for Selection A coal deposit has the following major characteristics: i) wide distribution as a flat-lying, thin, bedded deposit ii) stable nature of its major components and ranking characteristics such as carbon, heat content, volatile components, specific gravity, etc. iii) number of constituents and characteristics which under present regulations limit usage, such as content of ash, sulphur, sodium, etc. iv) effect of characteristics of over- and under- lying host rocks including porosity and permeability, lithology and general geology v) low value, high bulk nature. Because of the relative stability of its major components and its low unit price, coal does not require the same attention to detail as do the metal deposits. However, new regulations combined with social pressures make it imperative that more accurate information be made available concerning factors which affect the quality of coal and which may have an adverse effect on the environment when the coal is mined or burnt. The method selected for the evaluation of a coal deposit must, therefore, be flexible and sensitive enough to be used to interpolate stable parameters whose general distribution character-

Jan 1, 1974

By V. M. Mukhin

Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose. In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a full-scale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon. During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.). Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.

Jan 1, 2006

By L. D. Jaffe, D. C. Buffum

EARLY papers1-' reported that temper brittleness is influenced by microstructure. This conclusion was based on room temperature impact tests, the inadequacy of which has been pointed out. Pellini and Queneau7 measured impact energy absorption at —80O to +25oC for several microstructures. On the basis of the shift, associated with temper brittleness, in the energy vs testing temperature curve they concluded that tempered martensite is somewhat more susceptible to temper brittleness than is tempered pearlite. The range of temperatures was insufficient to give complete curves covering the transition from tough to brittle behavior, so it is difficult to evaluate quantitatively the shift for the different microstructures. Also, the smaller shift of pearlite might be attributed to its already being temper embrittled at its temperature of formation. Accordingly, blanks 2 3/16 in. long were cut from a heat of SAE 3140 hot rolled steel barstock, 5/8 in. diameter, on which other work has been reported? A set of blanks was austenitized 1 hr at 900°c, water-quenched, tempered 16 hr at 675oC, and water-quenched, giving a microstructure of 100 pct

Jan 1, 1954

By T. Sterry Hunt

I HAVE lately had occasion to examine sulphuretted ores of bismuth both from Tudor, Ontario, and Latete, New Brunswick. The former consisted chiefly of bismuth-glance, carbonated at the outcrop, and within associated with some metallic bismuth, iron-pyrites and graphite, in a quartz gangue. In the second locality, where it appears to be present in considerable quantity, the veinstone is also quartz, but the associates of the bismuth-glance are chalcopyrite and galena. The treatment of such mixed ores in the furnace for the extraction of the bismuth could yield only a very impure product, and in view of the high price of the metal I tried with success a wet method for the treatment of the ore, which is based on well-known chemical reactions, and may, in some cases, be advantageously used. The pulverized ore is dissolved by heat in commercial nitric acid, and the remaining gangue washed by displacement, first with a little strong acid (which is used to attack a fresh portion of ore) and then with a moderate quantity of water, which is added to the first solution. This, if the excess of acid be considerable, may be partially

Jan 1, 1873

By C. A. Stetefeldt

In my paper on "The Consumption of Fuel in the Taylor Gas-Producer Plants at the Aspen and Marsac Mills" (Trans., xxiii., 134), I mentioned that in the plant which I had designed for the Ontario mill, the gas-tubes were to be covered with thin, corrugated sheet-iron, over which a coating of asbestos-magnesia would be spread in order to effect a good insulation and keep the gas as hot as possible. At the Ontario mill, two Stetefeldt furnaces and two revolving driers are fired with gas. One furnace is connected with a Taylor producer of 5 feet diameter, and the other furnace and the two driers are heated by the gas from a Taylor producer of 7 feet diameter. In the latter case the gas-tubes are necessarily somewhat long, and the cleaning of them takes time. In order to prevent overheating of the tubes during that operation, it has been found advantageous not to provide them with an insulating covering. If a tube becomes red-hot at any place by the burning of soot, this is at once observed, and the tube is closed until it cools down. The tubes con-

Jan 1, 1895

R. W. NEWCOMB, New York, N. Y. (written discussion *).-This paper is particularly interesting to me, because it gives data on a much mooted question, viz., the serviceability of Le Chatelier (platinum-platinum-rhodium) thermocouples under severe industrial conditions. It has always been supposed that platinum-platinum-rhodium thermo-couples, used at high temperatures under strong reducing conditions, would not give long service and were subject to rapid volatilization. The fact, however, that the carefully kept records indicate that a little more than 3 gm. out of more than 830 gm. was lost over this considerable period, shows what kind of service can -be obtained from platinum-platinum-rhodium thermocouples,, when properly installed, and well cared for. While the writer has no actual figures on the loss of weight, etc. of platinum-platinum-rhodium thermocouples under service, he was told, by the man in charge of pyrometers at a large industrial plant in which over 400 platinum-platinum-rhodium thermocouples were installed in furnaces doing various kinds of heat-treating work, that the average maintenance cost, for materials alone, including platinum-platinum-rhodium wires and protecting tubes, was 27 c. per furnace, per month:

Jan 12, 1919

By T. Egleston

During the last winter we have been actively engaged in the School of Mines in search for boracic acid. This has been owing to the fact that Mr. M. W. Iles, assistant in the qualitative laboratory, has discovered a test for that substance which makes its discovery exceedingly simple instead of being, as previously, very difficult. It consists in powdering the mineral, calcining it, then moistening it with sulphuric acid, and heating on a platinum wire until the sulphuric acid is expelled. It is then moistened with glycerin and made to take fire. If boracic acid is present it infallibly gives a green flame. It is not at all surprising, under such circumstances, the test being so easy, that boracic acid has been found by the students in a great many cases where its presence was not previously suspected, and in some where its detection was previously too difficult to warrant looking for it. We were not prepared, however, for its discovery in Lake Superior iron ores, and were disposed at first to think that a mistake had been made. After, however, it had been frequently reported in these ores it was considered worth while

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Mining Geologist. Age, 34; wide experience in all Lake Superior iron-ore districts and Arkansas bauxite district. Examinations, tonnage estimates, reports, direction of prospecting, geologic mapping, churn and diamond drilling. Excellent references. A-2681. Mine Superintendent or Manager. Graduate mining engineer, age 31, married, 10 years' experience, now in government employ as metal-lurgist, desires employment with reputable mining company. New York interview if desired. A-4219. Research Engineer, now in Chile on erection of 50-ton mill with modern machinery for treatment of Chilean nitrate, desires connection, from the first of next year, with firm operating in South or Central America. A-4915. Mining Engineer. Young graduate of Michigan College of Mines; capable of handling men, conscientious worker; desires a position that will lead to assistant superintendency. Any place in the United States. Initial salary relatively unimportant. A-5195. Metallurgist, married, age 25; technical graduate; 3 years' experience in blast and open-hearth furnaces, blooming mills, metallographic, and heat treatment work; desires position as sales engineer in the Pittsburgh district. A-5196.

Jan 12, 1919

By Clark T. M

Underground coal mining involves the disturbance of natural strata stresses formerly in equilibrium, the production of noxious and flammable gases and dust which can be both an explosion and a health hazard. It involves also the use of heavy, large equipment operating on natural floors and in confined spaces. Such operations are required to be carried out under artificial light. Much of the easier won coal, that is the shallower coal, from this State has already been extracted and in future workings will be required to go deeper. As the depth increases strata pressures will increase, gas production is likely to be greater and the production of dust will also increase. A further problem which has not yet reached significant proportions in Australia is the potential rise in working temperature. This will be occasioned not only by the use of large items of equipment which themselves generate heat, but due also to thermal gradients as the depths increase. The need for better employee training is now being widely recognised throughout the industry. Under present highly mechanised conditions new employees should not be required to work with or near heavy mobile machinery without proper training

Jan 1, 1976

By K. Takahashi, G. Dodbiba, T. Fujita, N. Sato, S. Matsuo, K. Okaya

Different materials are used for manufacturing various parts of a cellular phone. Considering that a great number of mobile phones are being discarded every year, it is important to recover these materials and then recycle them in order to save resources. The primary objective of this work is therefore to find and suggest ways on how to recover various materials from discarded cellular phones for recycling. Much effort, for example, has been put in recovering and recycling tin oxide (ITO), a mixture of indium (III) oxide, (UI2O3) and tin(IV) oxide from the discarded liquid crystal displays (LCDs). Here we report a simple and cost-effective process, which includes a HC1 treatment process for altering the structure of the indium (III) compound into a chlorideinduced indium compound, in order to facilitate the vaporization of indium at a relatively low temperature. The experimental results indicated that 96.2 % of indium can be recovered from ITO, when the sample was heated at 973 K for 90 minutes. In addition, some thermodynamic calculations were also carried out in order to better understand the mechanism for chlorideinduced vaporization of indium.

Jan 1, 2011

ALTHOUGH it might seem more fitting to discuss this subject in the Ninth Book in connection with the smelting of iron where I had thought to treat of it in detail, this process of making steel appears to be almost a branch of the above chapter on iron itself; hence I did not wish to separate these two so far that they might seem to be [18v] different things. Therefore I wish to write of it here and to tell you that steel is nothing other than iron, well purified by means of art and given a more perfect elemental mixture and quality by the great decoction of the fire than it had before. By the attraction of some suitable substances in the things that are added to it, its natural dryness is mollified by a certain amount of moisture and it becomes whiter and more dense so that it seems almost to have been removed from its original nature. Finally, when its pores have been well dilated and softened by the strong fire and the heat has been driven out of them by the violence of the coldness of the

Jan 1, 1942