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By Donald E. Raab, Lee W. Saperstein

INTRODUCTION The Premise Not much time has to be spent in a tunneling project to realize the tremendous interdependence that exists among the various unit operations. The research that is to be described attempts to examine one set of these linked operations, namely, the effect of cutters on muck handling properties. All too often research focuses on too minute an aspect of a problem for the results to be of much immediate, practical use. The goal of this research is to avoid this specificity. Apologies are tendered if this goal is missed. It is known that the mode of flow of bulk solids under the influence of gravity -- emptying a bin or hopper -- is dependent on several basic parameters. The size of the particles and the distribution of sizes (consist) determine whether the solids will first flow out of a given aperture; the cohesion of the solids will determine if flow will continue after the bin is opened; and the angle of internal friction determines the size of the flow regime (1,2,3). It is well understood that the latter two parameters affect the behavior of bulk material on a conveyor belt. Cohesion of material to a belt is always an undesired problem. Heaping of material on a belt depends on the material's internal friction. It is also known that varying the particle size, and the packing density of the material can affect the material's angle of internal friction (4,5). The question was posed whether sufficient variation in a mechanical tunneling machine's (mole) cutting function could be arranged to affect materially the handling properties of the muck

Jan 1, 1974

Experiments on the Rate of Heat Transfer from a Hot Gas' to a Cooler Metallic Surface Members of the American Institute of Mining Engineers will be much interested in the subject of teat transfer from a hot gas to a cooler metallic surface, and although the book on this subject recently published by the Babcock & Wilcox Co., of New York, deals primarily with boilers, it contains a great deal of information which metallurgical engineers will find of great value. The book starts out with an introduction giving some of the current theories regarding this subject; it then describes in detail the experimental apparatus used, and the methods of conducting the experiment's and recording the data. Then follow some account of the determination of radiation losses in jackets and cooler; measurement of metal temperatures; detection and correction of errors; etc., concluding with a discussion of the results and derivation of corrective formula for heat absorption; heat pressure rate and specific heat of gas.

Jan 5, 1916

By X. M. Prévost

The reassessment of coal reserves has become a matter of urgency and has come as a result of the present situation of the industry, in the context of globalized coal economies, as well as new mining legislation and the advantages and difficulties of domestic coal suppliers. The de Jager report concerning coal reserves, released twenty years ago, can no longer be used as an estimate for accurately forecasting South Africa’s future coal production. The new reserve and resource study will promote the diversification of energy sources and provide a clearer view of the future of coal mining in the country. With plans to increase South Africa’s coal export capacity to approximately 84 million tons by 2005, it is uncertain whether the country really has sufficient reserves to meet this expansion, as well as satisfy the projected increase in inland demand. The face of South Africa’s coal industry and by association, the economy of our coal-dependent country, are both set to change. This is mainly due to factors such as the demise of most of the large collieries over the last approximately twenty years, growing numbers of economic empowerment producers, the emergence of strong competition in the export market, the dawn of Clean Coal Technologies (CCTs) and the Kyoto Protocol The paper will attempt to dispel some of the current myths about coalfields and reserves and highlight potential areas of high quality coal reserves, available mainly to new entrants in the industry. Keywords: Central Basin, Clean coal technologies, Coal combustion, Coal exports, Coalfields, coalLink, Coal reserves, Coal resources, Coal processing, Colliery, Economic empowerment, Discards, Fluidized bed combustion, Low-ash coal, Metallurgical coal, Power generation, Pulverized fuel, Reserve blocks, Richards Bay Coal Terminal, Run-of-mine production, Saleable production, SAMREC Code, South Dunes Coal Terminal, Steam coal, Synthetic fuels.

Jan 1, 2003

By Prakash Venkatesan, Mehmet Ali Recai Ӧnal, Shaik Saida, Veerendra Singh, Chenna Rao Borra, Manish Kumar Kar

A laboratory-scale investigation of the effect of milling operation and catalyst addition ( K2CO3) on the partial reduction of low-grade pyrolusite ore pellets was carried out using coke as a reductant. Thermogravimetric analysis was used to understand the correlation between milling and catalyst addition parameters with the reduction temperatures. DTG analysis of pyrolusite pellet reduction showed three distinctive peaks associated with a three-step reduction mechanism (i.e., MnO2→ Mn2O3→Mn3O4→MnO). The results showed that the grinding and addition of the catalyst have a significant effect on lowering the MnO2 reduction temperature independently. But maximum reduction temperature drop is obtained when combining grinding and catalyst addition in this work. By 3 h milling and 10 wt% catalyst addition, the reduction temperatures were reduced by more than 200 °C compared to the raw ore pellets. These results obtained from the DTG analysis were further supported by XRD analysis of the reduced samples.

Dec 20, 2022

By Jean-Paul Franzidis, Robert G. Coleman, Emmy V. Manlapig

"The Floatability Characterisation Test Rig (FCTR) is a self-contained, highly instrumented mobile pilot flotation plant developed by the Julius Kruttschnitt Mineral Research Centre, the Mineral Processing Research Unit of the University of Cape Town and EIMCO, as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. Apart from being a fully operational pilot plant, the FCTR was designed to determine flotation model parameters and to develop and validate flotation plant modelling, scale-up and simulation methodologies.The FCTR was installed at WMC’s Kambalda Nickel Operation where circuit modelling, simulation and scale-up test work was performed using the AMIRA P9 flotation model as the basis of the analysis. The model parameters were obtained through metallurgical sampling, batch flotation tests and gas dispersion characterisation around the FCTR. Model parameters were determined for four FCTR circuits, each of increasing complexity. The circuits ranged from a simple rougher-cleaner configuration with no recycle streams, to a more complex rougher-cleaner-recleaner configuration with two recycle streams.Using the P9 modelling methodology, the system was analysed using four mineral species: nickel sulphide, iron sulphide, copper sulphide and non-sulphide gangue. The floatability of each mineral was analysed as two floating species (fast and slow) and a non-floating species. Mass balanced data from all four FCTR circuits were regressed simultaneously together with data from 47 batch flotation tests. Nonlinear regression was used to determine the solution. The model fit was found to be accurate with most data points predicted within experimental standard deviations. A Monte Carlo sensitivity analysis was also performed to establish the stability of the regressed parameters.Using the P9 simulation methodology, simulations of five FCTR circuits (different from the previous four) were performed. The FCTR was also operated in these five circuit configurations to obtain experimental data to validate the simulated predictions. The simulations were found to predict the recovery and grade of nickel sulphide and copper sulphide within experimental standard deviations. The prediction of recovery and grade of iron sulphide and non-sulphide gangue was less accurate. Overall the FCTR simulations predicted the changes in circuit configuration well."

Jan 1, 2003

By Donald Warren, J. F. Libsch

HIS investigation originated as a result of a pre-vious experimental study' of the magnetic properties of Fe-Co alloys fabricated by the powder metallurgy technique. Densities of powder compacts prepared for the magnetics investigation varied from 7.45 to 7.70 g per cu cm or from 93 to 95 pct of the experimental value of 8.08 g per cu cm for a fused alloy of the same composition.' While this range of density is considered sufficiently high for most applications, the highest possible density is to be desired for maximum magnetic properties. By applying a technique similar to the one described above to a pure electrolytic iron powder, Rostoker³ was able to achieve a density of 7.895 g per cu cm, which is the highest density ever reported for sintered iron. While Rostoker's work involved the sintering of an elemental powder rather than a mixture, it was believed that higher densities should also have been obtained for alloys using the above technique because of the recoining operation and the high sintering temperature. Consequently, it was decided to investigate the various factors affecting the density of this alloy with the idea that such a study might lead to higher densities and, as a result, powder alloys having magnetic properties identical with those of the fused alloys. It was believed that the principal reason that near-theoretical densities for the powdered alloy were not obtained was the interference of gases with the normal sintering mechanism. When present during the sintering operation, gases can exert several harmful effects: they can remain on the particle surface and interfere with surface diffusion and plastic flow; they can be released and, under certain conditions, expand the void spaces through gas pressure; or they can remain trapped in the pores and exert a hydrostatic pressure that retards elimination of the pores. Jones,4 Rhines,5 Goetzel," and others have given the effect of gases in the sintering of powder compacts an extensive treatment. Among the more important sources of gases in the sintering process are dissolved gases, adsorbed gases, air entrapped during pressing, and gaseous products of chemical reactions. During sintering adsorbed gases are partly released at a relatively low temperature, while those gases entrapped during pressing cannot escape until their pressure is increased sufficiently through increasing temperature to expand the interpartjcle openings. The remaining adsorbed gases, gaseous reduction products, and dissolved gases produce a similar effect at the higher temperatures. If, in the sintering process, gas evolution occurs after the interpore channels have been sealed, an exaggerated expansion of the void spaces results. This is particularly true if the temperature is high enough for extensive plastic flow. In his fabrication of powder bars from tantalum, Balke7 had to consider the effect of adsorbed hydrogen and provide for its escape during sintering by limiting the compacting pressure to a maximum of 50 tons per sq in. The effect of gases entrapped during pressing was first noted by Trzebiatowski8 when he found that gold and silver powders decrease in density with increasing sintering temperature if pressed at 200 tsi, while they exhibit the usual increase when pressed at 40 tsi. Recent investigators9-11 have also noted that entrapped gases have an effect on the expansion of copper compacts during sintering. Proper provision for the escape of gaseous products of reduction must be made in order to avoid deleterious effects. Myers" states that in the sintering of electrolytic tantalum powder, the temperature was gradually raised to 2600°F with a pause at 2000°F to permit reduction of the oxides. Experimental Details For the present study, 50 pct Co-50 pct Fe compacts in the form of circular disks 1½ in. in diam and 0.15 in. thick were fabricated by the pressing and sintering of a mixture of the elemental powders. It was decided to follow the sintering process by means of liquid permeability measurements, because it was thought that such measurements might serve as a measure of relative pore sizes, as well as a possible indication of the point at which most of the interpore channels become sealed. However, since the permeability as measured by the flow of a liquid, such as ethylene glycol, does not give an absolute indication of the point where the pores have become isolated, a method for determining the percentage of pores connected to the surface was set up. As an additional cross check on the permeability measurements, metallographic methods were used to study the relative pore size. Finally, the property of ultimate interest, the density, was measured. Raw Materials: The powders used consisted of an annealed, 99.9 pct pure, —150 mesh grade of electrolytic iron powder, and a 98 pct pure, —200 mesh grade of reduced and comminuted cobalt powder. The cobalt powder was not further processed either by hydrogen reduction or annealing. The screen analyses for the iron and cobalt powders are given in Table I, while the chemical analyses for each type of powder are listed in Table 11. Table 111 gives the hydrogen loss measurements for the powders according to the M.P.A. Standard Method and for a higher temperature as well. Preparation of Compacts: Equal amounts of the elemental powders were mixed by rotation for 1 hr and then pressed into compacts approximately 0.15

Jan 1, 1952

By Keith Leonard Sutherland

THIS paper is a study of the differential flotation of the sulphide minerals in the presence of salts of silver, lead and zinc. In practice, accidental activation due to these salts is more important than their use as reagents to replace copper sulphate. The general method of investigation has been based upon contact tests, the temperature of 35°C. being chosen in conformity with earlier work. Potassium ethyl xanthate and potassium amyl xanthate were selected as collectors and pure sulphide minerals were used. The experimental procedure has been outlined in earlier papers and all solutions were kept carbonate -free.1,4 Contact, or spreading of an air bubble, at a mineral surface indicates the presence of an adsorbed collector film. PURITY OF REAGENTS The xanthates were purified in the usual manner.1 Neither the cyanide nor the sodium hydroxide solutions contained sufficient carbonate to give a precipitate with barium chloride solution. The silver sulphate was prepared from pure silver nitrate by evaporation with concentrated sulphuric acid until there was no evidence of brown fumes. This solution was diluted and the difficultly soluble sulphate washed with water so that unchanged nitrate was dissolved. The resultant crystalline powder was pure white. The lead and zinc salts were prepared by dissolving especially pure lead and zinc in C.P. nitric and sulphuric acid solution and the crystals drained. The standard solutions were checked by titration. It was felt desirable to use the sulphate radical wherever possible, but since lead sulphate was insufficiently soluble for the purpose of the experiments, it was necessary to use some other lead salt. A.R. copper sulphate was used without further purification. RESULTS The results are presented in the accompanying figures; the areas of noncontact (nonflotation) are shaded in Figs. 8, 9, 10 and 11; in the remainder they lie to the right of the curve. Zinc Sulphate The curves in Fig. I are to be compared with those for Fig. 2, for which zinc sulphate is absent. This comparison shows that the influence of the zinc ion is usually small. Its influence is more marked, however, for chalcopyrite in the absence of cyanide. The influence of zinc sulphate is also marked for copper-activated sphalerite, for which tests were made only in the absence of cyanide. The results are of importance in the separation of pyrite from copper-activated sphalerite when, zinc sulphate is added in the lead flotation section (p. 204 of ref. I). Sphalerite does not adsorb the collector (i.e., become floatable) under the conditions chosen.

Jan 1, 1942

By Hessam Yazdani

In comparison to the conventional piled foundations, the piled-raft foundations provide a more economical solution to support high-rise buildings constructed on soft soils. In this type of foundations, the bearing capacity of the underlying soil is taken into account to support the superstructure loads and the piles are placed to control both the total and differential settlements of the superstructure. Currently, there is not a standard and worldwide acceptable approach to select the location of the piles and most of piled-raft foundations are designed based on the experience of designers. Therefore, particular attention should be given to the optimal design of this type of foundations in order to minimize the considerable construction costs involved. This paper examines the capability of the ant colony optimization (ACO) algorithm to optimize the piled-raft foundations subjected to static and seismic loadings. The soil-pile interaction is considered by modeling the side and tip resistance components of the piles using the nonlinear Winkler-based p-y and t-z curves in the OpenSees program. The soil-raft interaction is taken into consideration using the Winkler springs beneath the raft. The objective of the optimization problem is to minimize the construction cost of the foundation by taking the configuration and number of the piles as design variables. The side and tip forces of the piles as well as the total and differential settlements of the foundation under the serviceability limit state are considered as the constraints for the optimization problem. Results show that in addition to the type of analysis (linear/nonlinear), the regard or disregard of the soil-pile interaction in the analysis can significantly change the optimal solution. The optimal solutions obtained match the engineering expectations and indicate the effectiveness and capability of the ACO algorithm to minimize the construction cost.

Jan 1, 2013

By Steve Dillingham

Change occurs all of the time. In fact, it’s fair to say that change is a constant. Sometimes the change is inconsequential, but sometimes the change impacts us d i rectly and severely. Take regulations, for instance. Complying with regulatory requirements is just part of the job for those involved with explosives. But in recent years, it seems as if new or revised regulations in areas such as hazardous materials training, drug and alcohol testing, security issues, or local licensing/permitting standards are changing the way we operate on a recurring basis. Simply keeping track of all of these regulations has become a full-time job.

Jan 1, 2003

By Jack D. Melin

The commercial development of the Liwell Screen is a result of a thorough search for a non-blinding and highly efficient screening device capable of handling even the most difficult-to- screen feed materials. A proprietary development of Hein, Lehmann A.G. of Duesseldorf, West Germany, the Liwell Screen utilizes a unique flexible deck motion for sizing a variety of sticky, high surface moisture feed materials including raw coal and lignite at separations ranging from 3/4-inches (19mm) down to 10 mesh (1.5 mm).

Jan 1, 1983

By H. Sato, B. Thornton, K. Nishi, A. Usui

"Northwestern Pacific submarine seamounts are believed to be future marine mining areas of ferromanganese crusts, which contain hi-tech industrial metals, such as Co, Ni, Te, Ti, Pt, and REEs. The Takuyo No. 5 seamount is a member of the Cretaceous super-plume seamounts in the north Pacific, located within a Japanese EEZ (100 nm from the Minami- Torishima Is. or Marcus Is.), and only 300 nm away from the Japan’s Licensed area for exploration of Co-rich ferromanganese crusts under the ISA. This is an on-going program supported by independent academic communities but not a state-run program or managed by private funding.We have observed, sampled, measured, and analyzed the occurrences, distribution, physical properties, and microbiological environments at a selected flat topped seamount named Takuyo No.5 as a model area for scientific study of ferromanganese crusts within the Japanese EEZ. We then characterized crust structures, composition, age, and growth history, resulting in an understanding of the overall nature and distribution of these deposits from wide range of areas, water depths and geological environments. The study started with a ROV (Hyper-Dolphin 3K of JAMSTEC) exploration jointly with universities and national institutions (Japan Agency for Marine-Earth Science and Technology, Japan Oil, Gas, and Metal Exploration Corporation, and Geological Survey of Japan) in 2009 using marine geology vessels, remotely-operated vehicle, an oceanbottom drill machine, deep-tow TV camera, as well as conventional dredges and corers. We have been studying the topography, geology, nature of the bottom material of the seamounts using delicate sampling devices and measurement tools, and characterized the distribution patterns of the metal-rich ferromanganese deposits from chemical, mineralogical, and microbiological points of view."

Sep 1, 2014

By Fred C. Bond

COMPRESSION TESTS THE standard method of determining the crushing resistance of rocks consists of crushing prepared shapes under slow compression, and expressing the ultimate crushing resistance at the load causing failure in pounds per square inch of crossectional area perpendicular to the crushing force, with the height approximately equal to the diameter. One-inch cubes or cylindrical drill cores are commonly used. Cubes and drill cores are cut by a high-speed steel disk with diamond dust embedded in the edges, and running under a water spray. Such a saw will cut one square inch or more of hard stone per minute. An oiled, spherical, swivel compression block of small diameter should be used to equalize the pressure. Each sample is crushed between sheets of cardboard or blotting paper extending about one-half inch beyond the edges of the stone. A cloth is wrapped around it to prevent dangerous explosive shattering. It is probably preferable to place the swivel block below the specimen, with either a rigid head or another swivel block above. Whatever the arrangement, the conditions should be selected that will develop the maximum crushing strength of the specimen, even though its top and bottom planes may not be precisely parallel. The cardboard pads may be dispensed with if the ends of the specimens are polished smooth. The use of lead pads was discontinued because of the observed tendency to split the material. The samples are weighed and measured before breaking, and the density is calculated. Cubes that contain bedding planes or veinlets are usually placed with these vertical and parallel to the crushing force, in order to develop the maximum resistance possible. A number of compression tests were made on Canadian ores, by Forrest Nagler, of the Allis-Chalmers Manufacturing Co., and are listed alphabetically in Table 1. These tests were made on one inch cubes or on diamond-drill cores approximately one inch in diameter and one inch long. The drill cores represent virgin rock, while the cubes may have been previously weakened by explosives. Compression tests have been made in the Allis-Chalmers Milwaukee Laboratory on a number of ores and other materials. These are listed alphabetically in Table 2. In test No. 1339, on limestone from the Hanna Coal Co., comparison was made between 2 by 2-in. diamond-drill core segments and one-inch cubes cut from the cores in the same strata. Results for the cylinders are tabulated directly below those for the cubes. The bedding planes were normal to the compressive force in breaking the cylinders and parallel in breaking the cubes, which accounts for the lower strength obtained from the cylinders. The percentage of net linear compression at the ultimate pressure was measured in test No. 1055 for Fontana TVA quartzite as 0.30 for cube A, and 0.37 for cube D.

Jan 1, 1946

By R. J. Gochin, P. Bevilacqua, G. D. Schena

This class of flowsheet-dependent simulators does not replace modular simulators, such as Modsim and Microsim, which are necessary for the assessment of different flowsheets before selection of the most desirable technical option and for investigation of the fine details of unit processes. The system presented here is regarded as complementary, serving in the early stages of feasibility studies as an aid to assessing the convenience and economics of preconcentration; the example used is of dense-medium preconcentration of a barytes-fluorite ore

Jun 13, 1905

By B T. Lusk, John J. Silva Castro

The signature hole method uses a convolution operation to predict the waveform of a production blast based on the record of a waveform produced by a single blast hole. Convolution is a mathematical operation on two functions, (generally the product) to produce a third one. Recent research communication and publications highlight a lack of discussion in the literature about the available methodologies to calculate the convolution for blast vibration prediction. The goal of this paper is to discuss and present in detail for students in ground vibrations from blasting, several techniques to calculate the convolution between signals when the signature hole method is used. Convolution is a straightforward operation when signals produced by each hole are assumed the same, however; variations in the signals from each hole in a production blast require a more complex convolution operation. A graphical procedure is shown in this paper to solve a convolution when signals vary hole-to-hole (as expected in a mining production blast). The graphical methodology was tested using a recorded blast event and the results were compared to the regular mathematical procedure (convolution) and the results from a commercial software used in the mining industry. Results show that the graphical procedure is in agreement with the results from the other two.

Jan 1, 2014

By Robert L. Lagace

The attention of this group was focussed on four through-the-earth communication systems that are presently of high interest to the U.S. Bureau of Mines; four systems for providing operational/emergency communications on the working sections of coal mines, indeed up to the very face of the section. The systems are: uplink-data, downlink-voice, sidelink-call alert coded page, sidelink-roof bolt voice page. Each of these systems makes use of the mine overburden as the signal transmission medium, as opposed to the guiding wires, cables, and tunnels treated by the operational communications working group. Each of these systems satisfies one or more of the Bureau's objectives for mine communications systems; namely • reliable links for monitoring the mine environment under both operational and emergency conditions. • reliable links for communicating with miners during emergencies. • special links for increasing the efficiency of day-to-day operations of the mine. Each of these systems has been successfully demonstrated on a limited experimental basis, and prototypes of all these systems are installed and operating in the USBM experimental mine in Bruceton, Pa. Each of these systems must now be optimized regarding its performance, and engineered for practical routine application to the working sections of actual operating coal mines, particularly those of the room and pillar type. This optimization and engineering must take place subject to the principal constraints listed by Howard E. Parkinson in his Workshop paper entitled, "Objectives and Constraints of Through-the-Earth Electromagnetic Communications Systems'' and enumerated below. • Depth of Mine Overburden • Overburden Conductivity • Electromagnetic Noise In and Above Mines • Limited In-Mine Electrical Energy (Stationary or Man Carried) During an Emergency • Intrinsic Safety for In-Mine Equipment • Practical and Rugged Equipment for Use Under Both operational/Emergency conditions • Severe Weight Limitations for Man Carried Equipment • Reasonably Low Costs Especially for Man Carried Equipment Part II of this paper provides a brief description of each system, while Part III summarizes the present status of developments related to these systems and some recommendations for future work needed to advance these systems to the practical application stage.

Jan 1, 1973

By H. Karakul

Determination of P-wave velocity (Vp), which is closely related to intact rock, is a nondestructive, easy and less complicated procedure. Due to these advantages, there is an increasing trend to predict the geomechanical properties of rocks from Vp. In addition to mineral content, cementing material and porosity, degree of saturation (Sr) are also other factors influencing geomechanical properties of the intact rock. However, up to the present, in the studies on the prediction of geomechanical properties of rocks from Vp, the effect of Sr has not been investigated. By considering this issue, in this study, it was aimed to correlate strength properties (uniaxial compressive and tensile strengths) and Young’s modulus with Vp of various rock types under different degrees of saturation. In addition, geomechanical properties of rocks were estimated from theoretical P- and S-wave (Vs) velocities, which were calculated based on their mineralogical compositions. For this purpose, fourteen different rock types were collected from several parts of Turkey and a comprehensive laboratory testing program was conducted. In the statistical analyzes, a series of different prediction relationships were developed by using independent variables such as Vp, Sr and effective clay content (ECC). Simple regression analysis results indicated that although prediction of the geomechanical properties of rocks from Vp at different degrees of saturation was possible, the equations developed would yield some under- or over-predictions. On the other hand, the multivariate equations developed have very high prediction performances and are very useful tools to estimate the geomechanical properties from the measured Vp at any Sr value. In addition to mineralogy, the variation in geomechanical properties with increasing Sr is also associated with the combined effect of porosity and clay content, which is first described in this study by the term Effective Clay Content (ECC). It is also noted that strength properties of rocks at any Sr may also be estimated using the empirical relations based on the theoretical Vp and shear-wave velocity (Vs) values, which are calculated from their mineralogical compositions.

Jan 1, 2015

The different electrowinning cells presently developed for recovery of gold from CIP eluates are compared and contrasted. The efficiency of operation for each cell is,discussed in terms of the electrochemistry of (a) gold deposition, and (b) packed bed electrodes. The advantages and problems associated with each cell design are presented and recommendations are made as to the best method of gold recovery.

Jan 1, 1982

By J. -F. Blais, M. -O. Simonnot, P. Charbonnier, J. Mocellin, Université de Lorraine INRA, G. Mercier

"Huge amounts of air pollution scrubber sludge have been generated during ferromanganese production using blast furnace. These residues have been historically deposited in ponds near steel making plants. They are very rich in zinc, manganese and lead (5 to 40 %) and also contain aluminum and iron. Considering the market value of these metals, brownfield sites can now be used as secondary resources. These ponds also have to be cleaned up to meet the environmental regulations.We have developed a hydrometallurgical process to recover Zn, Mn and Pb in order to produce valuable compounds of Mn and Zn and recover the final Pb residue by pyrometallurgy. The Zn and Mn compounds need to be pure enough to be economically valuable. Batch laboratory tests were carried out to determine suitable selective leaching conditions. The investigated operating conditions were acid concentration, pulp density and temperature. Optimal conditions to maximize zinc extraction (100 %) and manganese extraction (95.9 %) were found using sulfuric acid and sodium metabisulfide. The final residue contained 14.8 to 23.8 % of Pb. Then, Zn was recovered in the form of ZnO or ZnS by precipitation and Zn metal by electrowinning, while Mn was recovered as MnCO3 with a fairly acceptable concentration of impurities.INTRODUCTIONFerromanganese has been produced by pyrometallurgy in much of Western Europe for centuries. Use of wet scrubber to remove pollutant and dust particles from gas stream was common for most of these operations. Those residues contain high concentration of Zn, Mn and Pb. They have been left to decant in settling ponds installed close to the steel production plants. They now constitute heavily contaminated artificial soils. Those sludges are so contaminated with Zn, Mn and Pb that they can be used for metal production. Currently, no method is available to decontaminate these residues and recover Zn, Mn and Pb. Therefore, an approach considering these brownfield sites as secondary resource is in development. Doing so would achieve two goals, decontaminate the site and produce metals.. (Huot, Faure, Biache, Lorgeoux, Simonnot, & Morel, 2014a; Huot, Simonnot, Marion, Yvon, De Donato, & Morel, 2012; Huot, Simonnot, Watteau, Marion, Yvon, De Donato, & Morel, 2014b)."

Jan 1, 2016

By C. P. Kempter, H. L. Brown

Recently Chang determined heat content values of tantalum monocarbide and tungsten monocarbide from 325" to985°Kand 326" to 912"K, respectively, and, using other published data, made certain solid-state calculations for these two compounds. Chang expressed his Cp values in units of cal per "g-atom alloy" OK. We consider this poor usage since l) tantalum monocarbide and tungsten monocarbide are not alloys, and 2) an atom of an alloy does not exist. However, one may convert his values to units of cal per mole OK by merely doubling them. For TaC he calculated a Nernst-Lindemann parameter of 9.07 x lo-' "g-atom per cal". We have refined the calculation of this parameter and have arrived at a much lower value. Rather than approximating the true coefficient of volume expansion, a,, as three times the true coefficient of linear expansion, a, we calculated u, from the TaCo.99, lattice expansion data of Fries and Wahman.38 At 25°C a, = 14.3 x 10s per OC. The molar volume was calculated to be 13.32 cu cm per mole at 25°C. From the lattice compression data of Champion and Drickamer~' for "TaC,.,," we determined the room-temperature compressibility to be 3.5 x 10-l3 sq cm per dyne by plotting l/Vo (aV/ap) vs applied pressure. (Since the lowest pressure at which Champion and Drickamer reported a relative volume was 20 kbars, one may calculate an approximate compressibility only. Chang calculated a compressibility of 3.175 x 10-l3 sq cm per dyne from the same data.) We also used twice Chang's value of Cp = 4.38 cal per "g-atom alloy" OK for the molar heat capacity at 25°C. From these four values we calculated a Nernst-Lindemann parameter of 5.8 x 10-l4 mole per erg or 2.4 x lo- ' mole per cal, and a Cdil value of 2.3 x 10' ergs per mole OK. In the case of tungsten monocarbide no isothermal compressibility has been reported; however, one may calculate an approximate Nernst-Lindemann parameter by using the adiabatic compressibility reported by Brown, Armstrong, and Kempter." Using the WC lattice expansion data of Mauer and Bolz~l we calculated a, to be 12., x l0-' per OC. The molar volume was calculated to be 12.5 cu cm per mole. We used twice Chang's value of Cp = 4.18 cal per "g-atom alloy" OK for the molar heat capacity at 25°C. From these four values we calculated an approximate Nernst-Lindemann parameter of 2 x lo-' mole per cal, which is much

Jan 1, 1969

By T M. El Hajj, A C. Chieregati, M T. G C Marques, J M. Braga Jr, H Delboni Jr

"The estimate and control of sampling errors is essential for all mining operations, especially when dealing with strategic materials, such as niobium. This paper is based on a traditional quality assurance and quality control technique used to confirm mineralised intersection zones, and proposes the validation of sampling data using diamond drill twin holes, in order to evaluate and improve the quality of the current data set. The geological model of the niobium mine – located in Araxá, Minas Gerais, Brazil – was built including 77 diamond drill holes of a sampling campaign carried out during the 1970s. There are few records about the collection and preparation procedures of these past samples, making it difficult to estimate the errors associated with their analytical results. Therefore, 11 twin drill holes were drilled to compare their samples against the samples from the 1970s drilling campaign. The new hole locations were chosen as near as possible to the old holes location. The JORC Code, 2012 edition, relates the use of twin holes as a good sampling technique to assess sampling and assay data. Three parameters were considered to validate the 1970s drill hole campaign by the twin drill hole campaign: the difference of the coordinates between the paired holes the difference among the positions of the geological contacts to validate the geologic description the difference between the paired samples grades was calculated to validate the analytical results.The analysis of the grade range variation between sample pairs was based on three techniques: geostatistical interpretation of vertical semivariogram to obtain the nugget effect calculation of the relative difference between duplicates calculation of the error associated with the sampling protocol established according to Pierre Gy’s Theory of Sampling.The results were satisfactory for hole coordinates; however, the ore content showed a high deviation, although this divergence can be explained by the nugget effect. For the lithological intervals, the new results contributed to an effective identification of variations among lithologies, ie brown weathered ore and saprolite. The twin drill holes campaign successfully validated the geological model data, allowing effective mine planning and higher reliability of the reconciliation results.CITATION:Marques, M T G C, El Hajj, T M, Braga Jr, J M, Chieregati, A C and Delboni Jr, H, 2017. Theory of Sampling and geostatistics for twin drill holes analysis in a niobium mine in Araxá, Brazil, Australia, in Proceedings Eighth World Conference on Sampling and Blending, pp 97–106 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 9, 2017