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By Roberto Giovanardi, Isabella Lancellotti, Luisa Barbieri, Ercole Soragni, Fernanda Andreola

"Recovery of precious metals (PMs) is a present topic, as they are used almost in every electronicelectric device. Gold is the second PM in order of consumption (following silver) and it is almost ubiquitary in electronics where it mainly finds application to produce bonding wires in integrated circuits and as a coating for contacts and connectors. Given this, discontinued electronic and, with a minor role, electric devices may represent a primary source of PMs as gold mines or jewelery wastes.At present the recovery of gold from such waste is generally accomplished by two strategies: by oxidative thermal treatment followed by metallurgical or chemical processes or by cyanide chemical etching; both techniques do not represent the optimum as the first one deserves a great amount of energy and non-combustible pollutant slag and fumes are produced, while the second procedure comports the use of a highly pollutant agent as cyanide.The aim of this work is the characterization of different electronics scraps to evaluate the gold concentration, and the selective recovery of this metal using enviromentally-friendly techniques. In particular, a new process was developed in order to overcome such environmental and efficiency issues. The process reaches the goal of detach the gold film from the substrate by selective leaching of the supporting metal.IntroductionThe treatment of waste from electrical and electronic equipments is a current topic as their role in modern life is increasing. The disposal of such waste represents both an environmental and an economical concern due to the vast amount of both precious and non precious metals.The use of precious metals (PM) in this field is of primary importance given PM’s unique properties, which give to each of them a specific and irreplaceable role. Silver is the most used, with a demand of over 5000 tonnes per year, mainly for switches and contacts in electric appliances. Gold is the second PM in order of consumption (over 250 tonnes per year and 8% of the total demand) and it is almost ubiquitous in electronics where it finds application to produce bonding wires in integrated circuits and as a coating for contacts and connectors. It is also used as solder in integrated circuits (in alloy with tin) or for wide coatings where it ensures protection against corrosion. Palladium, platinum, rhodium and iridium follow in order of consumption [1- 3]."

Jan 1, 2008

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

Jan 1, 1968

By M. McClintock

"High Pressure Grinding Rolls (HPGR) is increasingly being chosen for comminution circuits for its energy-efficiency for hard rock mining operations. Despite HPGR’s growing popularity, geo-metallurgy programs are still prohibitively expensive because of large sample requirements. Traditionally, sizing HPGR application requires a significant amount of sample, in the order of 1 to 10 tonnes, depending on the level of study and complexity of the resource. Therefore, engineering and design of HPGR circuits typically are reliant on few composites that are required to be representative of the resource and mine plan. Three bench scale HPGR test methodologies were developed in 2015 at NBK Institute of Mining Engineering at the University of British Columbia (UBC) capable of defining the energy size breakage relationship of pilot HPGR. These methodologies were developed to allow bench scale testing for different levels of study from PEA (Preliminary Economic Assessment) to detailed design and operations. The Piston Press test defines the energy size reduction relationship by measuring specific energy consumption and corresponding feed and product size distributions. The advantage of Piston Press testing is the small sample requirement of 5 to 10 kg. Small sample requirements allow multiple samples to be tested across a deposit. Piston Press testing allows extensive geo-metallurgy programs that can determine ore variability and inform in optimization and production planning. To date, the Piston Press methodologies have been validated on a pilot-scale HPGR unit located at UBC. Recently, testing was conducted to calibrate and validate the Piston Press test against full-scale HPGR on a gold sulphide ore deposit. The program included the collection of operational data with the respective HPGR feed and recycle sample. Sample collected was used both for Piston Press testing and HPGR piloting. This paper discusses the test-work and results as carried out during this program, using the aforementioned methodologies."

Jan 1, 2018

By L. B. Lindemuth

To those who are in a position to carry the thought to a conclusion; I would like to present a theory for the cause of blisters in galvanized sheets. Blisters that are caused from piping and shrinkage cavities will not be considered because the reason for their formation is entirely obvious. Blisters that occur periodically with no apparent system of ocation, number, size or grouping, and then disappear with no. apparent change in manufacturing method, are the ones to which this theory would apply. Examination of blisters of the latter type has shown that they contain hydrogen gas at atmospheric pressure, and that occasionally traces of oxide or sulfide are found on the inner surface of the blisters. These two characteristics have led to the rather general idea that hydrogen gas generated in pickling, and that iron oxide supposed to be inherent in the ingot and causing weak spots were, in some manner, responsible for the development of blisters in galvanizing. The theory which I wish to advance is that these blisters are caused by moisture that has penetrated the steel after the annealing operation. This moisture comes from the atmosphere, or from pickling or washing and when it is suddenly expanded into superheated steam in galvanizing, the increase in volume is so great that it cannot escape with sufficient rapidity through the small opening where it entered as moisture.The pressure so generated forces the sheet apart along those lines of lamination ;hat may be found in practically all flat sections of steel rolled comparatively cold. The increase in volume. from moisture to steam at 800° F. is 2244 times the original volume of the moisture. The pressure generated by ;he moisture heated to 800° F. and entirely confined would be enough to expand or explode any container. This would explain the source of sufficient pressure to cause a sheet to blister.

Jan 3, 1927

By A. H. Lang

THE recent production of important quantities of high-grade muscovite at the Purdy mine, near Eau Claire, Ontario, bas brought that district into prominence and bas added another strategic mineral to the list of Canadian products. The discoveries are thirteen miles west of Mattawa and about two miles north of the Trans-Canada highway and the Canadian Pacific railway. HISTORY Clear mica of low power factor is in considerable demand in Canada and in the United States for war purposes such as radio and telephone condensers, aircraft spark-plugs, radio tubes, and transformers. Some muscovite (white mica) bas been produced in North Carolina and New Hampshire, but the United States trade bas depended largely on importations of muscovite from India and of phlogopite (amber mica) from Madagascar. For many years Canada bas been a substantial producer of phlogopite, but was unable to compete extensively in the United States with importations from abroad. Canadian production of muscovite bas been negligible as no important deposits were known. Ever since the construction of the Canadian Pacific railway, attempts have been made from time to time to mine the pegmatite dykes in and near the Eau Claire area, but, although some feldspar has been mined, no appreciable muscovite was produced. Lace in 1941, J. Purdy and H. MacDonald discovered a dyke containing large crystals of high-grade muscovite from which they are reported to have sold $700 worth of mica. They recorded claims 35974 and 35975 in December, 1941, and claim 36095 in May, 1942.

Jan 1, 1943

By Leopoldo Gutierrez

Eight oil sand ores with the bitumen content ranging between 3.6 and 15 wt.% and the fines content (-44 micrometers size fraction) between 9 and 69 vol.% were subjected to the standard alkali extraction test used to measure the degree of oxidation of metallurgical coals. The results showed that there is a strong correlation between the absorbance of extracted solutions at a wavelength of 520 nm and the ratio of the fines content to the bitumen content. The latter factor is directly relevant to assessing the extractability of bitumen from oil sand ores. Bitumen extraction tests showed that the bitumen recovery decreased from 90 % to 30 % when the absorbance at 520 nm increased from 0.23 to 0.64. A comparison of the UV/visible spectra of solutions obtained from the alkali extraction tests with solutions of Aldrich Humic Acids suggest that low bitumen/high fines oil sand ores release substantial amounts of organic matter very similar, if not identical, to humic acids. In contrast, high-bitumen and low-fines ores do not release as much of the organic matter, and UV spectra of these leached substances are quite different from those of humic acids. Overall, the results show that chemical composition of bitumen in the tested ores varies greatly with ore type and oxidation, and that the alkali extraction test is a promising technique to quickly assess the extractability of bitumen from a given ore type.

Sep 1, 2012

By L. A. Matthews

The embrittlement of the Ti-6Al-4V alloy by hydrogen dosing at elevated temperature has been investigated. Metal coupons were subjected to isothermal treatments in a partial hydrogen atmosphere in the temperature range from 650ºC?950ºC and the degree of embrittlement after treatment was determined by drop-weight impact testing. Embrittlement was found to be inversely related to reaction temperature as a result of the combined effects of greater hydrogen absorption and titanium hydride precipitation at the lower isothermal temperatures. Keywords Titanium, hydrogen embrittlement, impact energy

Jan 1, 2011

By Jr. Koch

Statistical methods applied at the Bureau of Mines Denver Mining Research Center to data from metallic ore bodies were used to evaluate lignite reserves from core data and to predict the extent of lignite horizons in some Texas lignite beds. Six lignite seam units were studied using data from 361 drill holes. The data indicate a total of 214.2 million tons of lignite in the area examined, and probable reserves of 113 million tons in an area 2,000 feet beyond the limits established by the drill holes. It was demonstrated that lignite reserves present in lenticular beds could be reliably determined by statistical techniques, and that core drilling could be optimized to maximum information with minimum drill holes. The technique described is applicable to other coal beds.

Jan 1, 1966

By Thomas P. Meloy

There is much interest in the automation of entire comminution circuits, At the present technological level it is possible to automate a circuit but to date it has not been done, To successfully automate a circuit, a number of problems must be solved. Not all of them are engineering problems. The purpose of this paper is to discuss some of these problems, as certain the implications of these problems and indicate solutions to them. In this paper the term "automation" is used loosely but in the popular sense. Namely, that a plant is automated if a computer is used to control the basic flow of the materials as well as setting the critical parameters in the process. Specifically, the discussion will concern itself with the control of comminution circuits from the dumping of the ore into the primary crusher until the final interface between the comminution circuit and say, the flotation mill in the case of a sulfide ore.

Jan 1, 1965

By G. E. Joe

"This is a panel discussion on the milling experience with large volume flotation machines in Canada. Over the past ten years, the Canadian milling industry has been characterized by treatment of ever increasing tonnages of lower grade ores. In order to treat these ores efficiently, mineral processors have been employing increasingly larger volume flotation machines. In older established mills, standard flotation cells have been replaced by the larger volume models with very apparent savings in mill floor space as noted in the Opemiska copper mill.We are pleased to hear from four mill operators with extensive experience on large volume flotation machines. They are:1. I. E. Wahn, metallurgist with Falconbridge-Manibridge, who will describe their mill experiences with the Tank cell and the Maxwell cell.2. G. M. Hughes, mill superintendent of Sherritt Gordon-Ruttan, will detail recent experience with the Agitair cell.3. J. R. Maxwell, mill superintendent of Opemiska Copper, will report on their Maxwell cell installation and operation.4. A. H. Winckers, superintendent of Development and Technical Control, Sullivan Mill, will present a paper written by H. J. Chalmers describing Cominco's past experiences with large volume flotation machine installations including Denvers, Wemcos and Maxwells."

Jan 1, 1974

By F. McIntosh Galbraith

This paper describes the use of the magnetometer, under geological direction, in exploration of the Sudbury nickel district. The writer's experience at Falconbridge has led him to the belief that only through detailed work, and by careful correlation of both geological and geophysical results, can geophysical prospecting methods be applied successfully to mining exploration problems. It is hoped that the basic technique described in the paper will be found to have general application. Introduction Within the past 20 years, geophysical methods of prospecting have become solidly established in the field of petroleum exploration. They have not, however, been similarly adopted by the mining industry, although mining is a far older craft and should be the more advanced in its technique. While, therefore, it is almost a routine matter to have geophysical surveys performed in a new area being tested for oil, a new metal-mining district is usually teeming with prospectors and promoters long before the technical man appears on the scene. Even then, only the more primitive engineering methods are customary in the early stages of exploration. Three factors are chiefly responsible for this situation, The first is the difference between oil pools and ore deposits in their geological modes of occurrence. While most of the known metallic ore bodies have been found outcropping at the surface, petroleum deposits are characteristically buried. This does not mean that all ore deposits outcrop, but neither does it mean that we should rely on "wildcatting" to discover blind ore bodies. The second factor is the relative scale of metallic lodes and accumulations of petroleum. In areal extent, a metal-bearing vein deposit is typically a much smaller geological feature than an oil pool. Presenting a narrower target, it requires closer shooting to score a direct hit. And finally, there is the need, in mining work, for close correlation of the known local geology with geophysical observations. This becomes of increasing importance as the size of the objective diminishes. A geophysical disturbance on a large enough scale will be detected under almost any circumstances and by almost any technique; without benefit of geology, however, the significance of a local anomaly may easily be misread. Campaign at Sudbury In the Sudbury nickel district of Canada, new deposits of nickel and copper have been discovered recently by magnetic methods, under geological supervision. A campaign of exploration, designed to encompass the district eventually, was set in motion in the spring of 1935. After six years, a new and important Ore body has been discovered and its continuity established to 1000 ft. in depth; several areas have been eliminated; and a number of possibilities remain to be tested. This has been accomplished with the expenditure of less than $$I50,000-—including the cost of all diamond drilling. The responsibility for carrying out this campaign was entrusted by the company to its Geological Department, and the under

Jan 1, 1946

By K. Ilankoon, I. M. Saman, S. J. Neethling

In heap leaching the transport of the acid from the drippers to the surface of the ore particles is a major factor in the overall performance of a heap. This flow behaviour is complex as the flow is unsaturated and occurs along a tortuous set of inter-particle channels and connections. The particle properties such as size, shape and porosity are very important when modelling the liquid holdup and flow within heaps, since the dominant mechanisms at work are quite different. This paper investigates the effect of these particle properties experimentally on heap flow behaviour using a 1-D column leaching system consisting of non-porous glass beads with a system of actual ore particles. The similarities and differences between the two systems on flow behaviour are described using an inter-particle flow model. In addition, the applicability of positron emission particle tracking (PEPT) for laboratory column leaching will be detailed to calculate hydrodynamic dispersion in packed beds compared to more conventional residence time distribution (RTD) tests and also to obtain the time averaged rivulet flow paths through the particles of the bed for the better understanding of heap hydrodynamics.

Jan 1, 2014

By Fabjanczyk M. W

The design of underground mine roadways (tunnels) requires a detailed understanding of the in situ stressfield, the rock failure modes, the performance characteristics of reinforcement or support members and assessment of the stress state about the roadway. Definition of these factors, together with monitoring of roadway behaviour during both development and extraction operations, allows rational design procedures to be undertaken.The design approach utilised computational techniques to simulate the behaviour of the strata about the opening for a range of anticipated stressfields and various reinforcement options. Field validation studies are conducted to confirm the design expectations.

Jan 1, 1993

By C. E. Schmidt

Homestake crushing and grinding, practice-was completely revised during the period of 1951-1953. During the conversion, both crushing plants at the head frames the Ross and the Yates, were changes at each plant involved replacing the two 8K gyratories with a rebuilt, The flow sheet single thirty inch gyratory for primary crushing to four inch. The gyratory discharges to a seven foot Symons standard cone crusher set at 1-1/8 inch opening. The cone discharge goes to Tyrock screens fed by vibrating feeders. Screen openings, are l/2 inch by 5 inches: at the Ross. Plant, and 3/8 inch by 5; inches at the Yates. Screen oversize goes to a seven foot Symons cone brusher converted to the short head type; the crusher setting is 5/16 inch. Crusher, discharge; is closed circuited with the Tyrock screens, The above crushing installation delivers a minus 5/8 inch rod mill feed to the mill bins. The crushing revision eliminated the-180 heavy South African type stamps, which had previously reduced the 2 inch crushing plant product to a minus 5/8 inch feed for the 10 rod mills, and 8 ball and pebble.; mills, other revisions in the mill flow sheet, resulted in 3 identical units of about 1350 tons per day, capacity per unit, Each unit consists of an open, circuit 6 foot by 12 foot rod mill, fed from two 24 in by 48 inch vibrating feeders of the four feeders available per unit. A gathering belt delivers the ore discharge of the feeders to the Transportoweigher, which in turn discharge s, into the rod; mill feed spout. Rod Mill discharge is the feed for the 9 foot by 11 foot ball mill, The ball mill is closed circuited with a 16 foot by 30 foot Dorr Classifier. The Homestake make amalgamator, for coarse gold recovery in the ball mill circuit, made' necessary a 36 inch spiral conveyor between the classifier rake discharge and, the combination drum and double scoop feeder on the ball mill See Figure l - the flow sheet of the two stage grinding units.

Jan 1, 1958

The report of the Annual General Meeting of the Institution of Mining and Metallurgy held on Thursday, 20 May, 1971, in the rooms of the Geological Society of London, Burlington House, Piccadilly, London, W.1, at 4 p.m. (Chairman : M. J. Cahalan, President) includes details of awards and prizes presented to William Justin Kroll, Sir Gordon Colvin Lindesay Clark, John Convey, Evert Hoek, Peter Reginald Dawson and Christopher Michael St. John

Dec 1, 1971

By Bruce Pinkston

This report presents a description of the Prototype Demonstration Vehicle developed under U.S. Bureau of Mines Contract No. JO 366003, "Improving Man Transit Safety". This vehicle was constructed to assess the feasibility of a set of equipment related guidelines which were drafted in Phase I of the same contract. State-of-the-Art improvements were embodied in such areas as collision survivability, occupant comfort, and multiple mode (on and off rail) operation. The electric battery-powered vehicle carries a twelve man section crew at speeds up to 12 mph. The description of the demonstration vehicle is presented in Volume I. Safety Guidelines are presented in Volume II.

Jan 1, 1981

By Bernard E. Weichman

The oil shales in the Piceance Creek Basin of northwest Colorado occur in the Parachute Creek member of the Green River formation. The oil shales were deposited in a unique environment of deposition which caused the mineral nahcolite (NaHC03) to be precipitated within the oil shales. Post-depositional tectonics resulted in extensive fracturing of the Middle Zone of the Parachute Creek member, and to a lesser degree portions of the Lower Zone, which allowed percolating ground waters to dissolve the nahcolite in the fractured portion of the oil shale beds which is characterized by broken porous oil shale, certain beds of which have collapsed into rubble and debris. The extent and porosity of the Leach Zone aquifer is dependent upon the percentage of kerogen and nahcolite originally deposited in the oil shale. Any oil shale development program in the Piceance Creek Basin of northwest Colorado will need to be preceeded by an extensive study of the Leach Zone in order to determine the effects on a mining program.

Jan 1, 1973

By R. F. Mehl, G. V. Smith

The decomposition of austenite in steels, because of its immerse practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1"3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings—pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. -As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. Pearlite Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix.2--5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the' parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrong!:!, as Mehl and Smith6 have pointed out, that the lamellae delineate the {2I0} planes of ferrite.* Martensite It is known that martensite is a transiti0nal constituent of body-centered tetragonal lattice,' and that it forms suddenly

Jan 1, 1942

By Robert Lamarre

We will present the summary of a number of case studies whereby mining organizations have succeeded in maximizing equipment uptime by reducing the number of maintenance parts stock outs by more than 80% while scaling down total inventory maintenance parts by more than 20%. We will present a thorough comprehensive methodology to improve business processes in order to optimize inventory management and forecasting. We will examine: ? Demand management optimization ? Forecasting organization ? Inventory management parameters optimization ? Improved replenishment processes ? Inventory optimization and the right KPIs and exception reports We will provide cases in point such as Areva in Africa, Cambior (IAMGOLD) in South America, Osisko Mining Corporation, Barrick Gold/Bousquet Mine and Aurizon Mines Ltd./Casa Berardi in North America. We will discuss how Inventory Management World Best Practices operates in a maintenance environment. We will present how an integrated approach, coupled with a strong Enterprise Asset Management or CMMS system with an Inventory Optimization system specially designed to manage spare parts, actually promises and delivers results.

Nov 1, 2011