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By L. G. Austin

INTRODUCTION Autogenous (including semi-autogenous) grinding has probably been the most important single innovation in milling practice for the last twenty years. However, the design of these units has been largely a matter of trial-and-error, since the normal empirical laws for the design of ball mill circuits do not apply with exactitude to autogenous grinding circuits. There have been examples of autogenous mills failing to achieve output or product specifications. It is worthwhile, therefore, to attempt to develop a more detailed and precise set of design laws, using the concepts of specific rates of breakages and daughter fragment distributions (1), and performing mill simulations by computer. This type of approach has been applied to ball and rod milling (2, 3,4,5), but even for these mills it is by no means complete as yet (6), because of the amount of experimental work involved. There has not been a strong incentive for industry to develop new design procedures in ball and rod milling because the prior back-log of experience with these mills makes for easy design by empirical comparsion with existing systems. The new approach has been followed mainly by University groups (7,8,9,10), although experience in Australia (9,11) has shown the advantages of the approach. Stanley (12) has applied the approach to results from a large autogenous mill, and we will use many similar concepts to his work, but extend the concepts to a more

Jan 1, 1977

By E. G. Leonardon

The object of this paper is to describe briefly the practical results obtained in several problems of civil engineering by resistivity measurements of the underground. It is intended for the mining engineer, as well as for the construction engineer; the stratigraphical problems discussed are general and frequently are encountered in mining exploration. Resistivity measurements have been used in mining and oil exploration for a number of years.' Their introduction in the field of civil engineering, on the contrary, is rather recent. It was applied for the first time in the spring of 1928 near Littleton, N. H., in the survey of two dam sites for the New England Power Assn.2 Since then, the geophysical firm with which the author is connected has had an opportunity to develop this field of activity, and more than 20 investigations at dam and tunnel sites have been carried out in the United States and Canada. A part of this work has been verified by underground or drilling exploration. This paper deals with but a few of the results, which we are permitted to make public now. The theoretical and technical sides of the processes employed will not be discussed; they have already been described in various technical publications. A few general points will be mentioned, to make clear the practical examples given. Resistivities OF the Rocks The surveys are based on the measurement of the specific resistance of the rocks. This resistivity is the electrical resistance of a cylinder of

Jan 1, 1932

By G. Milojcic

The opencast lignite mines in the Rhinel and Di strict/Germany are equipped with the continuously operating bucket-wheel excavator - conveyor - spreader system. High productivity requires large capital expenditure on main mine equipment as a precondition for efficient mining. In operation, the technology employed leads to a particular cost pattern which is quite different from that of other industries. Labour, auxiliary equipment and mobile vehicles are the most important cost factors which can be controlled by the management. In this respect information processing computer systems are used for systematical and interpretable representation of operational tasks and jobs both in planning and work preparation and in recording the operational data describing the work result and the use of resources. Another aim of the project is to relieve the middle management of major part of its administrative routine work. Job-related work planning and data recording open up various possibilities of analyzing the operational procedures. This analysis shows, for example, what auxiliary machines are particularly suitable for specific tasks, and working groups can be organized so as to take account of the different skills of individual employees for the sake of an optimal work product. Computerized information processing provides the decision makers with topical information related to their respective responsibilities. The mining department of the Hambach opencast mine is the first user of the PERMAD system. Due to the favorable evaluation it has been decided to introduce PERMAD in three other mines in the course of 1992/93.

Jan 1, 1992

Ranger Uranium Mines (RUM) operates an open cut located in the Top End of the North- ern Territory. Strict environmental controls govern all operations and the water management requirements have the greatest impact on mine planning. The two main goals of planning are to provide mill feed and to mine sufficient suitable quality waste rock for ongoing con- struction of the tailings dam. Early planning concentrated on staged development of the pit to provide access to as much ore as possible for a given amount of development. All waste was considered to be suitable construction material. Grade control of crusher feed was the main problem in planning, as wide vari- ations occur in ore grade over relatively short distances. Water management for the site ope- rates a no release' system for contaminated waters. Design storage has proven inadequate, and the open cut has been used as the extra storage. As construction of future stages of the tailings dam requires non-mineralised rock materials which meet specific quality criteria, the mine has had to re-examine long term plan- ning and pit development strategies. This has entailed the collection of much data not re- quired under normal mining conditions, such as the assaying of waste drill core. The overall impact on mine planning of the environmental regulations has been to alter the philosophy of earlier planning, making it necessary to create a new strategy for pit development with

Jan 1, 1984

By Leena Vesa, Antti Remes

Design of thickeners is based on laboratory test work, characterizing the material and determining the optimal reagents, dosages and settling regimes. Several methods for dimensioning plant scale equipment exist. Kynch and Talmage-Fitch design procedures has been applied widely for a long time. Nowadays, besides them, a dynamic laboratory test work is applied for design of high rate thickeners. In that the laboratory unit is operated with known solids load per area, feed and flocculation conditions and with raking of the underflow. All these test methods afford useful data for setting up and calibrating a dynamic simulation model of a plant scale thickener. This paper presents a flocculation kinetics based dynamic thickener simulation model and a procedure to calibrate the model parameters. With the model, the underflow stream composition can be simulated over time as a function of the thickener operating parameters, which are: the feed rate and composition, underflow pumping rate, flocculant dosage and dilution of the feed. In addition, the model incorporates calculation of the slurry bed level, the cone pressure, the yield stress and the rake torque. Such a dynamic modeling scheme enables setting up simulation aided operator trainings and developing and testing of advanced control strategies, for example. The unit model can be integrated as a part of concentrator-wide flow sheet simulation model as well. Here, calibration of the kinetic flocculation model based on a laboratory test case data and further the operation of a simulated plant scale thickener are presented.

Jan 1, 2014

By Seth C. Schaefer

As part of the Bureau of Mines, U.S. Department of the Interior, effort to provide thermodynamic data for the advancement of minerals technology, the Gibbs energy of formation of sphalerite (zinc sulfide) was investigated with a high-temperature galvanic cell employing stabilized zirconia as the electrolyte. In the temperature range 948 to 1,210 K, potential measurements were obtained for the cell Pt, ZnS + ZnO, S02 = 1 atm // Zr02 // Cu20 + Cu, Pt, with the overall cell reaction ZnS(c) + 3 Cu20(c) = ZnO(c) + 6 Cu(c) + S02(g). (1) These results, combined with the best available values of ?Gf° for ZnO, S02, and Cu20 from the literature, give the Gibbs energy of formation of zinc sulfide for the reaction Zn(l,v) + 1/2 S2(g) = ZnS© (2) ?Gf° = -64.223 + 24.02 X 10-3T ± 0.650 kcal/mole (3) (948-1,180 K; standard states - pure liquid zinc and S2 gas at 1 atm), and ?Gf° = -92.720 + 48.17 X 10-3 ± 0.650 kcal/mole (1,180-1,210 K; standard states - pure zinc vapor and S2 gas at 1 atm). A third law analysis yields for the formation reaction Zn(1) + 1/2 S2(g) = ZnS(c), (5) a standard enthalpy of formation as follows: ?Hf298.15 = -63.64 ± 0.700 kcal/mole.

Jan 1, 1978

By R. C. Wilcox, R. V. Lawrence, P. A. Calhoun

The V-Rh-Si, Nb-Rh-Si, and Cr-Rh-Si systems were investigated to evaluate the extent of solid solubility between binary Cr3O structures. All Cr3O components lie within the favorable atomic size range1 for the formation of the Cr3O structure. Previous studies indicated complete solid solubility between V3Si and V3Sn2 and no solubility between Sn and cr3si3 or Si and Nb3Rh.4 The Cr3O structure is not found in the Cr-Sn and Nb-Si binary systems. Powder compacts were are-melted under argon, homogenized in a vacuum at 1000°C, and water-quenched. Alloys containing greater than 15 at. pet Si were annealed 100 hr. X-ray diffractometer methods were used to study all systems utilizing copper radiation for the Cr-Rh-Si system and chromium radiation for the other two systems. V-Rh-Si System. The alloys prepared in the V-Rh-Si system and the measured lattice parameters for the Cr3O structure found in each alloy are listed in Table I. The characteristic Cr3O diffraction pattern was found in all binary alloys. The measured lattice parameter of V3Rh (VRS-1) is in agreement with the reported value5 while the value for V3Si (VRS-5) is only in fair agreement.' In

Jan 1, 1965

By Marc C. Bétournay

Replacing diesel power in underground metal mining vehicles with available clean energy (e.g. hydrogen, lithium-ion batteries) is now a priority due to worker health issues, the increasing price of diesel, ventilation costs and air quality. Hydrogen fuel cells are a known and broadly applied power technology. They have been the focus of a dedicated research program to carry our proof of concept projects as well as regulatory developments for mining application. However, hydrogen remains a demanding energy vector to use in confined, underground applications. Standardization and safety considerations are being addressed in the industrial consortium Hydrogen Mine Introduction Initiative (HMII). Research projects are being carried out to resolve the gaps for regulated use. This article focuses on HMII objectives and Project results. The first has reviewed the relevant codes and standards and mine regulations, indicating that hydrogen and fuel cells could be allowed underground and that current codes, especially the Canadian Hydrogen Installation Code would be sufficient for hydrogen use. The second project established the standard hydrogen storage and distribution architecture along with related risks and safety requirements for its use in the third project, using an underground test chamber to delineate the behaviour of hydrogen leaks in confined conditions with various ventilation regimes and ignition studies. This project will end in 2013. It will be followed by the last project, which will establish best practices in support of regulations development, and develop the ISO standard for mine hydrogen infrastructure and underground application.

Aug 1, 2013

By C Gunther

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

By Larkings RH

The high gas emissions associated with the depth of mining and very high coal extraction at some Australian Collieries have provided a need to investigate the influence of geological and mining conditions on levels of gassiness. The introduction of longwall extraction in particular is associated with complex strata control problems and quick changes in gassiness. To this stage of Australian coal mining, no standard method has been developed to predict the different levels of gassiness associated with the various geological and mining conditions; and the relationship between coal output and total methane make has not been established. For local conditions, with a large number of coal seams lying in close proximity to the working seam, the significant contribution of gas emissions from adjacent strata was expected, especially as strata relaxation occurred during longwall mining. This depends mainly on geological conditions, strata control and coal production. For the deepest of the B.H.P. Collieries in the Newcastle region, the relationship between coal output and total methane make has been investigated by systematic gas balance measurement during longwall extraction. The computer method of iteration was used to approximate the mathematical equation from the initial graphs of coal production versus quantity of methane in the ventilation system for various strata conditions. The angle of caving was established for local geological and mining conditions, for planning and design of the positions of cross measure boreholes.

Jan 1, 1986

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

By Leonard Klein

Reduction of oxygen-containing copper has always heretofore been brought about with wood poles. This paper reveals the first successful, economical, and Practical substitute for poles: a gaseous reductant, of which the production and plant use are detailed herein. THE art of fire refining of copper, consisting of melting, oxidation, slag removal, and finally reduction with wood poles, has been practiced for many centuries. An authentic record, discussed in detail in De Re Metallica,* mentions that as early as 1200 A.D. workers in this field of metallurgy were already acquainted with and practiced the basic principles of copper purification. Undoubtedly, the art was well developed marly centuries before the first written records began to appear. Notwithstanding the many advantages gained by application of mechanical con. trivances and by the tremendous increase in size of operations over the centuries, the reduction phase of the process has persisted essentially the same to the present time except for a very recent breakthrough. Numerous articles have been published and many patents have been issued on the subject of substitutes for wood poling in the past half century. They have dealt with a variety of gaseous, solid, and liquid reducing agents. But to the knowledge of the writer, no procedure has ever been prosecuted to a complete success on a large operating plant scale with the single exception of gaseous reduction of oxygen-containing copper revealed in detail herein. A natural gas-air reformer with ample capacity for

Jan 1, 1962

By D. Laguitton, D. Cimon

"BILMAT is one of the most powerful algorithms in existence for material balance computation in mineral processing flowsheets. It is based on a hierarchical decomposition coupled with the Lagrange multipliers method widely reported in the literature. Flowrates can be calculated optionally for pulp, solid or water. Assays are adjusted for a variety of subnetworks, such as assays of the solid as well as assays of fractions of the solid called level 4 data (l: pulp, 2:solid and water, 3:assays of solid, 4:assays of classes of solid).BILMAT4 is a new implementation of BIU1AT that operates in a new microcomputer environment and makes the method more accessible than ever. Its main features are a full-screen colour editor allowing graphic flowsheet drawing and data entry with automatic error checking. Mass balance equations are automatically generated by analysis of the graphics and corresponding data, thus relieving users from the error-prone definition of networks. Sensitivity analysis is performed to assess confidence intervals of computed flowrates and adjusted assays.BILMAT4 incorporates an option for gold leaching circuits where the element to be balanced appears in both the solid and liquid phases with negligible effect on the mass flows of solids. Recoveries are computed in all streams. This program is currently released by CANMET as part of the CAMP collection for Computer Aided Mineral Processing. A complete sample run of the program is discussed."

Jan 1, 1989

By Kevin Connor

The mineral industry continued to be an almost negligible contributor to the country's economy as the Government continued its 1979 ban on any mineral exploitation for export; a policy initiated at the end of 1979. A national program had been underway since that time to map and inventory all mineral resources so as to permit future exploitation of mineral wealth in the beat interests of the country and its inhabitants. In March 1982, the British Sulphur Corp. Ltd., under contract to the Burundi Government and the International Bank for Reconstruction and Development (World Bank), began a feasibility study of Burundi's phosphate deposits at Matongo-Bandaga for potential commercial exploitation. The 1-year project effort was to define ore reserves, conceptually design mining operations and processing facilities, estimate capital and production cost, and develop a regional market and distribution survey. Work completed during the year comprised geological exploration and reconnaissance and 1,200 meters of core drilling. Reserves in excess of 5 million tons of ore-grade phosphate were estimated available for mining. Rare earth mineralization was associated with the primary apatite. The associated carbonatite within the rock matrix was preliminarily assessed to be of value as a raw material for the manufacture of cement. The contract effort was valued at $1.2 million? Matongo-Bandaga is located approximately 40 kilometers north of the capital city of Bujumbura and alongside one of the country's few paved roads.

Jan 1, 1984

By J. H. Wernick

IN temperature-gradient zone-melting1 a molten zone is moved through a solid or across a solid surface by the establishment of a temperature gradient. This technique has both practical and fundamental aspects. One practical application is to make p-n junctions for semiconductive devices, particularly for devices in which the junctions are desired within the semiconductor. From a fundamental point of view, the technique is being investigated as a method for determining diffusivities in liquid alloys, and preliminary diffusivity results have been reported by the writer." In this paper, the effects of crystal orientation, temperature, and molten zone thickness in temperature-gradient zone-melting, and the bearing of these effects on diffusivity measurements and n-p-n junction formation are discussed. Experimental Procedure An effect of crystal orientation was noted in early experiments. To facilitate its study, movements of wire zones across a surface, rather than through the body of a single crystal, were observed for various surface planes and travel directions. The experirr-entai setup is illustrated in Fig. 1. The graphite end-section for the high temperature heater has an apron about 1/16 in. above the upper surface of the crystal. This apron insures that the surface temperature of the block is equal to or greater than the temperature within the block at every point, Thus, the zone does not penetrate the block and convection in the liquid is minimized. The experi-through a block is shown in Fig. 2,

Jan 1, 1958

By Hargraves A. J

At 4 MPa gas pres ure and 30°C the sorptive capacity of 10 selected Australian dried coal ranges from 17 to 23 m3/tonne of CH4 and 27 to 36 m3/tonne of CO2. Values for moist coals are about 25 per cent less. At 20°C, sorptive capacities are about 18 per cent greater. No clear relationship between coal rank and sorptive capacity was established.The permeability of coal to gas is dramatically reduced by progressive hydrostatic confinement. No single 'permeability' for a coal can be established because of relative affinities of coals and the gases (Ar, CH4 and CO2) used in experiments. Bedding plane permeability is significantly greater than permeability normal to bedding. Dependent on gas/coal combinations, permeabilities without confinement ranged from 150 to 0.05 millidarcies, and with 8 MPa hydrostatic confinement from 1.0 to 0.001 md. Generally, permeability is increased by reduction in temperature, and reduced by increase in moisture as one changes from Ar through CH4 to CO2. In retrospect, it is preferable to ubject permeability sample to 8 MPa hydrostatic stress only once, because changes occur in the samples and it is difficult to use other gases successively.The initial rate of desorption, DP, does not appear to be a reliable index of proneness to instantaneou outbursts for Australian coals.The methods used for determining quantitative gas-coal properties appear suitable and reliable for testing other coals.

Jan 1, 1985

By Thos Stroup

RECENT contributions to the literature relating to the problems of coal mine management have discussed the pros, and cons of unionism among the miners as bearing upon the immediate problems of the industry, but have devoted singularly little thought to the underlying causes, and the fundamental reasons. for the remarkable growth of union sentiment among the miners, a growth paralleled only in the case of the railroad workers. It is all very well to revile their organization, its obvious stupidity and stubbornness, its multitude of economic and social crimes, but it is also well to realize that there have been deep-seated causes for all these things, causes that, while operating in all industries and amongst all workers, have in none of them found the optimum conditions for development such as exist in the coal mining industry. The rise of the United Mine Workers of America to a position of importance in the industry synchronizes roughly with the introduction of short-time operation; of course seasonal shutdowns and slow-time working have always been evident in our bituminous fields, but these evils have grown steadily worse since 1895 and the U. M. W. of A. has grown steadily stronger; yet short-time operation alone cannot account for this tremendous growth for, witness the signal failures that have always attended the attempts to organize the harvest workers, the fruit packers and other highly seasonal workers.

Jan 9, 1923

By L. Li

Iron removal is a common procedure in hydrometallurgy of non-ferrous metallic ores. Chemical precipitation and solvent extraction are currently the main methods employed for separation of iron from copper leach solution. However, chemical precipitation methods have the problem of producing large amounts of iron precipitates, and/or requiring high temperature and high pressure conditions for precipitation. The precipitates are difficult to separate from the solution. Emulsification is a general problem for solvent extraction, which causes loss of extractants and contamination of the electrolyte. A common problem for solvent extraction and chelating ion exchange processes is the difficult iron stripping process. Therefore, finding an efficient and environmentally friendly method for iron removal is of great significance. In this paper, new processes of using ion exchange resins to remove iron from copper leach solution have been investigated. Salicylic acid, amino carboxylic acid, amino phosphonic acid and hydroxy-oxime resins were employed to adsorb iron from a simulated copper leach solution containing 40 g/L of Cu2+ and 36 g/L of Fe3+. It was found that a hydroxy-oxime resin, named Z-Fe, has excellent adsorption selectivity on Fe3+. Desorption behavior of the resin was studied by two step elution using dilute H2SO4 and oxalic acid solution, respectively. After optimizing the adsorption-elution processes, the extent of removal of iron from the simulated copper leach solution using resin Z-Fe was 90%, while copper recovery could reach 100% in closed circuit processing.

Jan 1, 2016

Discussion of the paper of W. A. Forbes, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 82, October, 1913, pp. 2477 to 2514.. SAMUEL K. VARNES,* Steelton, Pa.:-We have a gas-cleaning plant consisting of a, centrifugal dry dust catcher, and two rain-type wet scrubbing towers, 25 by 60 ft. each, for rough cleaning of blast-furnace gas. This plant was put in early in 1910, with the intention of cleaning gas for use in hot blast stoves and under boilers, and was so used for several months. Soon after it went into service, the blast-furnace men complained that they could not get as high blast temperatures as they had obtained when using dirty gas. It was decided to run a series of careful tests to determine if this were true and to what degree the apparent results might be affected by other conditions. About 60 tests were run, covering a period of five months, and at the end we came to the conclusion that it did not pay us to scrub the gas for stoves and boilers. The tests were all run upon a single stove, no boiler tests being made, but the conclusions of the stove tests being applied to the boilers. The furnace burden was practically the same for all the tests and averaged: Per Cent. Daquari and other hard ores 57 Nodules 13 Raw Mayari ore 25 Mill cinder and scale 5

Jan 12, 1913

By Paul Sterling

The general impression regarding the preparation of merchantable anthracite is that it is confined to a colossal, grimy structure, called a " coal-breaker." This name is a misnomer; for the desired result is not to break the coal, but to prevent its being broken. Preparation may be said to begin at the face of the chamber, with the mining and loading of the coal. Local conditions vary, not only ill the same field or basin, but also in the same mine, so that there is no fixed empirical rule governing the method of blasting or cutting coal. Tests should be made, when possible, to determine the explosive, or the mechanical coal-cutter, which will produce the largest percentage of what are locally known as " lump " and " prepared sizes " of anthracite. The prepared sizes are those mostly consumed for clomestic purposes. All other sizes might be called by-products of the anthracite industry; for they are not especially desirable, being the degradation resulting from the mining and handling of a brittle or laminated material. Being low in volatile combustible matter, anthracite burns most successfully when nearly of a uniform size, permitting the easy passage of air through the voids. This accounts for the large number of sizes into which the coal is separated. Table I. gives the various sizes, the diameter of ring over and through which each size is made, and the usual purpose for which it is employed.

Jan 1, 1912