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By D. A. Munro, G. P. Contractor

Fourteen 50-lb laboratory melts were investigated to determine the effect of uranium on the tenpering characteristics of loo-carbon (0.06 to 0.1 pct C) steels. It was found that uranium additions, particularly in the range 0.30 to 0.45 pct, enhanced the hardness and both ultimate and yield strength of the experivzental steels in the quenched and tempered condition. The structural and morphological chazges indicated that uranium retarded tempering of the tnartensite, thereby hindering the normal formation of polygonal ferrite formed in the late stages of tempering. The effect of this was to make possible the re-tension of the acicilar ferritic structure in the uranium-bearing' steels. The iraniuin-bearing steels also showed IVidnzanstatten-type growth of ferrite plates and had large prior austenite grains containing assenzblies of fine ferrite grains, mainly acicular in geometry. The fine-grained ferrite structure and the presence of more numerous and apparently smaller precipitates in the uranium-bearing steels are thought to he principally responsible for the itnproved tensile strength and hardness of the experinzental uranium-bearing steels. At ternperirzg temperatures above 455% (850'F) the ferrite in the higher-uraniun steels nzaintained acicularity and, hence, its strength and resistance to tempering. Uranium did not produce a secondary hardening peak. However, it retarded softening during the third stage of tempering because of its effect of inhibiting the grouth of cementite particles and of retaining the acicularity of ferrite plates. The resistance to coalescence accounted for the slow grocth of the ferrite grains in the uranium-modified steels and, hence, fov the persistence of the acicular ferrite structure. IT had been found previously1 that uranium additions up to about 0.45 pct had no significant effect on the tensile properties of low-carbon steel (0.06 to 0.10 pct C) in the as-rolled and normalized conditions, Fig. 1. On the other hand, it was observed that uranium in excess of about 0.30 pct had an embrittling effect as revealed by Charpy V-notch impact results. It was also noted that, as the uranium content increased, the morphology of pearlite changed from lamellar to feathery and the ferrite grains showed an etching effect resembling striated or dashed markings, suggestive of precipitation. The sharp drop in the impact properties shown in Fig. 2 warranted an assumption that the uranium content of about 0.30 to 0.45 pct may produce some secondary hardening reaction on tempering, analogous to that associated with a Cr-Mo-V steel, which shows very poor CVN toughness at the secondary hardness peak in the tempering curve.1' With this background and the reported findings of Hasegawa and noda that low-carbon uranium-treated steel showed signs of secondary hardening, the present investigation was undertaken to determine the effect of uranium additions on the mechanical properties of 0.10 pct C steels. No attempts were made to investigate in detail the mechanisms of hardening, although some suggestions based on the experiments are made. MATERIALS AND PROCEDURES A series of 50-lb induction-furnace melts was made using AISI 1008 rimming steel billets as the melting stock. The melting, forging, and rolling techniques proven satisfactory in previous projects'-3 were employed as a guide for this investigation. The steel was deoxidized with aluminum (2 lb per ton) prior to the addition of high-purity uranium. The analysis of each melt is given in Table I. Properties were evaluated as a function of heat treatment and are presented in terms of hardness and tensile strength vs tempering temperatures. The variation of hardness with the tempering temperature was studied on the quenched and tempered specimens, some of which measured 0.50 by 0.25 in. diam and the others 0.40-in. cubes. Before quenching, the specimens were vacuum-sealed in glass tubes and normalized at 900°C (1650°F) for 20 min. Following this treatment, the sealed specimens were hardened by austenitizing at 955°C (1750°F) for 20 min and water quenching, and then tempered for 1 hr in the range 150 to 730°C

Jan 1, 1967

By P. C. A. Maia, J Alexandre, F. A. J. Saboya, A. R. G. Azevedo, G. C. Xavier

"This work shows the characterization of clay and the granite waste by-product from the sawing process of the granitic blocks, used as raw material for brick ceramic. Besides, shows the degradation of the ceramic material obtained with different by-product contents in the waste after lab test degradation, is investigated. The clay is obtained from mine use areas of ceramic industry in Campos-RI and the waste is originating from of the area of Cachoeiro-ES, an important center of decorative stone in Brazil. The mixes were made by the addition of 0% up to 10% of the waste in the raw material. After drying and firing up to 900°C, obtained prismatic pieces were considered intact. Physico-mechanical properties were obtained from wet and drying tests in laboratory considering 50 and 150 cycles. The results showed that the use of powder byproduct has a considerably influence on the weathering and strength of the material.IntroductionThe ornamental rocks and coating defines the most promising areas of business in the mineral sector [l]. In this context, the Espirito Santo appears as the main Brazilian state in production and export of ornamental rocks, representing 47% of national production [2] which in tum is one of the economic sectors most representative of this State, due of its transport logistics and port vocation that facilitates the export of such products.It is estimated that the state of Espirito Santo there are approximately 1,200 companies dedicated to the activities of ornamental rock by providing 20,000 direct jobs [ 1]. These mobilize support activities, such as companies that provide machinery, equipment and supplies for industries, including service providers for maintenance.However, the production of rocks produces about 15,000 tons of granite waste/month [3] only in the municipality of Cachoeiro ltapemirim-ES. This is justified by the presence of more than 500 extraction industries, cutting and processing of stone, with about 900 looms, waste generators.According to [4], there is great potential for the use of granite waste in red ceramics introduced for the manufacture of bricks, blocks structural ceramics. and other ceramic products, especially when evaluated on exposure to weathering."

Jan 1, 2014

By Guohua Bai, Yuanbo Zhang, Guihong Han, Zijian Su, Daoyuan Zhang

"Specularite ores have poor hydrophilicity and ballability as well as inferior high-temperature reactivity, which restrict the large-scale application of them in the pelletizing and sintering production. Modified humic acid (MHA) organic binders are firstly used for pellet preparation from specularite in this paper. The results show that the drop strength of green pellets is 3.7 times/0.5m and compression strength is 12.5 N/P by using 1.0 wt% MHA as binder. Under the optimal experimental conditions of preheating temperature 980 °C, preheating time 12 min, roasting temperature 1280 °C and roasting time 10 min, the preheated pellets have the compression strength more than 400 N/P, and that of roasted pellets is 2747 N/P. The strength of finished pellets meets the requirements of blast furnace iron-making. MHA is a kind of more effective organic binder for specularite pellets compared with the inorganic bentonite.IntroductionAcid Pellets have advantages of good strength, uniformity particle size, high iron grade and good reducibility, which can be used as high-quality burdens for blast furnaces [1]. With fast development of Chinese iron and steel industry domestic magnetite concentrates with high grade of iron and good firing performances become shortage.Imported specularite ores have advantages of low price and high grade of iron (generally above 67 wt%), so the application of them in pellets is an effective way for sustainable development of pellet industry in China. However, the specularites have not been utilized in pelletizing and sintering at present because of the poor ballability and high-temperature reactivity [2, 3]. Most of the pellet plants use bentonite as binders, the amount of which is about 2~3 wt%. The pellet production practice shows that 90 wt% bentonite is still residual in finished pellets and reduces the iron grade [3]. Developing a new organic binder instead of bentonite is very important to the high-quality pellet production. On one hand, the consumption of bentonite is obviously reduced, resulting in decreasing the ironmaking coke ratio and slag discharge; On the other hand, the iron grade of finished pellets are improved, which brings the benefit for the ironmaking production."

Jan 1, 2011

By Warnie Flint

According to statistics compiled by the National Safety Council, US Bureau of Mines, American Medical Association, and other agencies, accidental injuries cause more deaths than all the leading diseases. No one is immune to an accident. Probably the best way to describe an accident is to say that it is an unexpected happening. The automobile driver is not expecting a terrifying crash, the electrician does not expect to be electrocuted, nor is the coal miner expecting the roof to fall on him. All personal injuries will not result in death. There is a multitude of victims who are living proof of what accidents can mean to an individual-victims who are blind, paralytic, missing arms, legs, etc. In most instances the earning power of these individuals is gone, and they are utterly dependent upon family or welfare. For many years there seemed to be an attitude that prevailed in industrial America that accidents were inevitable, and that so many fatalities and injuries should be expected. This, of course, was utter nonsense. Since the birth of such organizations as The National Safety Council, American Society of Safety Engineers, and. the US Bureau of Mines, much progress has been made in reducing accidents. The enactment of compensation laws greatly contributed to the progress that has been made. Does this mean that all accidents can be prevented? Unfortunately, it does not. Human psychology indicates that men will work unsafely or perform unsafe acts for the following reasons : 1) Lack of knowledge or skill. 2) Conflicting motivations, such as: (a) to be more comfortable, (b) to save time or effort, (c) to be accepted by a group. 3) Physical or mental condition. Nearly everyone desires his own safety, but not all individuals are willing to do what they know to do to insure their own safety.

Jan 1, 1981

By Rollin E. Hook, Attwell M. Adair

The response of CrzO3 and C~304 to various heat treatments was studied in are-melted iodide chromizim over the temperature range 1000" to 1750°C. These oxides, which are present as impurity phases in this material, were identified by X-ray diffraction teclzniques which were supplemented by optical metallop-aphy. As a function of increasing temperature, Crs04 is first observable in samples annealed at 1300°C and coexists with Cr2O3 (the low-temperature oxide) over a temperature range exceeding 200°C. As the temperature decreases, Cr3O4 dissolves with the concomitant precipttation of Cr2Y2. Both oxides precipitate predominantly at pain boundaries. The reactions which occur are involved with at least ternary equilibria, possibly due to iron which is present as an impurity in arc-melted iodide chromium. HILTY, Forgeng, and Folkman' reported in their investigation of the Fe-Cr-0 system that Cr3O4 (with about 8 pct Fe substituted for chromium) is a primary phase found in alloys with 9 or more pct Cr. They reported that this phase is stable only at high temperatures and that below the liquidus Cr3O4 is disproportionated into Cr2O3 and chromium-rich metal for both Fe-Cr-O alloys and in oxygen saturated pure chromium. Further, they proposed that CrsO4 forms by a peritectic reaction between Cr2O3 and the liquid. On the other hand, Hook, Garrett, and Adair2 found in their investigation of impurity phases formed in "pure" chromium (material consolidated from iodide chromium crystals) that Cr3O4 forms intergranularly and is stable as low as 1500°C which is 375OC below the melting point of chromium. The purpose of the research described herein is to determine the temperature range of stability of Cr3O4, and to show the nature of its decomposition. This further investigation indicates that Cr3O4 undoubtedly occurs in this material as low as 1300°C. The chromium studied was consolidated and fabricated from iodide chromium crystals (ICr-5) and contained Fe r 135 ppm, Si = 20 to 100 ppm, and 0 = 35 to 137 ppm. A complete chemical analysis is given elsewhere.' Annealing was conducted in 1 atm of purified helium and all samples were rapidly cooled (-200°C per sec) by withdrawing them from the furnace hot zone under a high flow rate of helium. The details of the electrolytic-etching technique and electrolytic-digestion techniques for preparation of insoluble residues for X-ray examination are given elsewhere also.' EXPERIMENTAL RESULTS The Starting Material. The as-swaged rod (final swaging done at 900°C) had a wrought grain structure and contained a dispersion of CrzO3 inclusions of maximum particle size of about 2 or 3 p, Fig. 1. The microstructure also contained a dispersed

Jan 1, 1964

By Matters, R T, Coldham, Slee, J C, R J, Wallman

The Committee desires to thank the managers of the various mines along the line of lode for their hearty co-operation in its labours. It would also extend thanks to Messrs J C Moulden, Howchin, Twelvetrees, and the West Australian Geological Surveyfor various information; to Messrs J G Dreyer, S Pope, T Read, P Moncrieff, R Williams, and W J Rose for analyses; and to a number of local gentlemen for advice and help. Professor Skeats, of Melbourne University, gave much valued assistance in petrology, and Mr Herbert Lavers kindly undertook the study of the garnets.INTRODUCTIONThe famous Broken Hill lode is situated in a low range of hills, the Barrier Ranges, near the western border of New South Wales. It has been worked since 1884-fust for silver, then for silver and lead, and at present for lead, silver, and zinc...

Jan 1, 1910

By AIME AIME

A MODERN copper reduction works has both a genera1 chemical laboratory for control work and a research laboratory for the study of improvement of present processes and better working-up of by-products. The division of work in the general laboratory would naturally differ in different plants. The following statement to the writer from a chemist in one of the works will give a good idea of the type. of work in the general laboratory :

Jan 1, 1929

By G. H. Thomas, M. C. O’Riordan, S. Rae

INTRODUCTION The British mining industry comprises 228 nationalised coal mines producing some 113 million tonnes of deep mined coal and employing 242,600 persons of whom 185,200 work below ground. There are in addition 174 small privately-owned coal mines employing 1500 persons underground and producing 1.5 million tones of coal. In the non-coal sector there are 108 privately-owned mines producing some 20 different minerals, including tin, wolfram, fluorspar, potash, rock salt, china clay, ball clay and fireclay. There are currently 4,100 persons employed in these mines of whom 2,346 are employed below ground. One mine producing potash employs 870 persons of whom 465 are underground workers. Since 1975 all matters relating to the health and safety of persons at work and of the general public who are exposed to industrial hazards have come within the purview of the Health and Safety Executive (HSE). The Mines and Quarries Inspectorate (MQI) is a constituent part of that organisation and enforces legislation applicable to all mines and quarries. The National Radiological Protection Board (NRPB) is a statutory and independent body that was established in 1970 to advance knowledge and provide information and advice about radiological protection. The NRPB has an agency agreement with HSE to provide advice and services relating to radiological protection, including protection against exposure to radon decay products in mines. There are as yet no statutory requirements controlling exposure to this source of radiation in Britain. Investigations for the presence of radon in British coal mines were begun in the mid 195Os. The concentrations found were of low order, typically around 2 pCi/l (Duggan et al., 1968). This was not surprising since big coal mines are well ventilated to control methane and airborne dust and it is now generally accepted that radon and its decay products do not constitute a health hazard in British coal mines. At one or two small mines where igneous intrusions were in close proximity to the coal workings, slightly higher readings were recorded. The MQI then commissioned NRPB to make investigations at metalliferous mines and in these much higher readings were detected. It was later agreed that the NRPB should undertake a survey of all non-coal mines in Britain to establish the extent of the problem. This survey was conducted mainly in 1973, (Strong et al.,1975) and follow-up surveys at various mines have since been conducted by the MQI. These investigations revealed that radon readings could be high in mines producing tin, haematite and fluorspar. Some small mines working other minerals in the same localities also showed high readings. More recently owners have been making environmental measurements at mines where there was some cause for concern. LEGISLATION AND RADIATION STANDARDS As a result of the survey work for MQI the Board in 1975 recommended an occupational limit of 4 WLM in a year from radon decay products together with a programme of radiological supervision (Strong et al., 1975). The MQI accepted the recommendation and advised employers and employees that the 4 WLM limit should be adopted. The limit corresponds to a concentration of 0.3 WL, equivalent to 30 pCi/l of radon-222 in equilibrium with the decay products, and was in accordance with an earlier recommendation by the International Commission on Radiological Protection (ICRP, 1959). ICRP recommendations are usually endorsed in Britain. It was recognised that some years would probably be required to achieve general compliance, and this is proving to be the case. Some confusion has been caused in Britain by the conflict between successive Euratom Directives on this and other standards of safety. As relative newcomers to the Community, we were not affected by earlier Directives, but the situation is different now. In 1959, the Commission of the European Communities provisionally recommended a maximum permissible concentration for radon-222 and daughters of 3 x 10-7 µCi/cm3, which corresponds to 300 pCi/l (CEC, 1959). The number was affirmed in 1962 (CEC, 1962) and reaffirmed in 1966 (CEC, 1966) but without any specification of the state of equilibrium. In 1976, the CEC again recommended 300 pCi/l, but on this occasion, the daughters were assumed to be present in the same quantities as in unfiltered air (CEC, 1976): this implies 40 WLM a year in poorly-ventilated mines. The formula is repeated in the latest version of the Directive (CEC, 1980), but the value is now said to be an interim one because it might not ensure compliance with the appropriate dose limit. ICRP (1955) recommended 300 pCi/l in equilibrium with the decay products in 1955 and reduced this value to 30 pCi/l for unfiltered air in 1959 (ICRP, 1959), endorsed it for equilibrium conditions in 1976 (ICRP, 1976), and held to it until 1980: these values imply respectively 40 and 4 WLM a year. The recent recommendation of the ICRP (1980) that the annual limit of intake for the decay products should be 0.02 J in a year corresponds to 5 WLM, but there is a rider that reduction should be made for exposure to gamma rays and long-lived airborne radioactivity. An allowance of 20% is suggested for uranium mines, implying 4 WLM a year for the decay products. The

Jan 1, 1981

By John C. Branner

Within a couple of years I have received many inquiries in regard to the manganese-mines of Brazil. These inquiries were doubtless directed to mc because I had lived and traveled in Brazil for more than eight years, and was therefore supposed to be pretty well acquainted with its geology and mineral resources. Somewhat to my chagrin, I not only knew nothing of manganese-mines in that country, but I had never before heard of the mineral having been found here in quantity, and I did not even know in what State the mines were located. The present summer found me in Brazil again, trying to finish up some of my early geological investigations along the northeast coast, and I have used the occasion to find out something about the manganese-deposits. Very little is known of these mines, even in Brazil. While at Pernambuco I was told that they were in the distant interior of the State of Bahia. In August I reached Bahia, and there I found out, concerning the mines and their geology, enough to be worth telling for the benefit of those interested in the mining or using of this mineral. Thus far, all the manganese-ore shipped from this State has come from two mines, the principal one of which is known as the Pedras Pretas mine. This was the first mine opened, is the best developed, and was the original discovery; the second one is on an adjoining tract, and the general geology and natural conditions are about the same in both. The Pedras Pretas mine is on the Nazareth-Amargosa railway, twenty-six kilometers west of the town of Nazareth, which is on tide-water, at the head of navigation, and is reached from the city of Bahia by a small side-wheel steamer that runs across the bay of Bahia and up the Rio Jaguaripe

Jan 1, 1900

By Carl Belser

This paper summarizes the data on the oil-shale deposits of western Colorado, Utah and Wyoming. It is based on published reports by the U. S. Geological Survey, on the results of core drilling and sampling by the Bureau of Mines, on the drill cuttings from the Genera1 Petroleum well, on a recent unpublished report by the Geological Survey on the geology of Naval Oil-Shale Reserves No. I and No' 21 and from information supplied by geologists of private companies who have investigated the Green River formation. The paper also contains a revised estimate of the grade and tonnage of minable thicknesses of oil shale of western Colorado. Introduction The oil shales of the Green River formation of Colorado, Utah and Wyoming comprise an important natural resource for the production of synthetic liquid fuels. The oil shale in western Colorado generally is more amenable to exploitation, apparently richer, and probably more persistent than in Utah or Wyoming. Work is now being done by the Bureau of Mines near Rifle, Cola. to ascertain the best procedures for mining the oil shale, producing shale oil from the oil shale, and converting the oil into more salable products. As a part of this program, holes were drilled and cores were taken of the oil shale on Naval Oil-Shale Reserve No. I. In addi- tion, drill cuttings were obtained from a well drilled through the Green River formation by the General Petroleum Co. about 18 miles northerly of the Naval Oil-Shale Reserve. Geology During middle Eocene time a broad, shallow body of water, now called Uinta Lake, covered northwestern Colorado and east-central Utah; a similar lake, known as Gosiute Lake, was in southwestern Wyoming Each of these contemporary lakes was bounded by high hills; the drainage was to the south. The Green River formation was laid down as sediments in the bottoms of these lakes. It is 3000 ft thick and has been divided into the following four members:

Jan 1, 1949

By Charles Colcock Jones

In any discussion of this very large subject we are confronted at the outset with so many obstacles that at best only a fragmentary and rather disconnected presentation can be made of it, and my hope is that building from the few facts I have to offer a more complete knowledge may be secured. In the whole intermountain and Pacific Coast region, west of Pueblo, Col., and from Canada to Mexico, there is no production of pig iron, and steel production is confined to the manufacture of a small amount of open-hearth steel from scrap. When we consider the area, the resources, and the several centers of population, this condition seems anomalous, even in the face of every counter argument as to cheap water transportation, or other means of transport from the Atlantic Seaboard or from the iron and steel centers of the Middle West. This comatose condition, if such a term may be applied, is certainly not due to a lack of all the essential materials and factors for success in iron and steel smelting, but is rather, I think, due largely to the general fact that it is only within a comparatively few years that the centers of population on the Pacific Coast have attained a size that would entitle them to the position of distributing or freight centers, or that the "back country" has been enough built up to make it sufficiently interesting to the railroads to foster trade from the local centers to the interior points rather than seek to supply such local centers and the interior by a transcontinental haul. "Ore Supply Edwin C. Eckel, in his monumental work on Iron Ores, has but little to say concerning the Pacific Coast deposits. He mentions (p. 269) those of Minaret, Madera County, and the Eagle Mountains, Riverside County, Cal., "perhaps 50 to 100 million tons each;" the deposits in Shasta County, worked for the electric furnace on Pitt River; and

Jan 1, 1916

By Nils Eivind Kamfjord, Halvard Tveit, Ingeborg Solheim

"Because of its negative environmental effect the attention towards NO emissions increases. This again leads to new demands from the authorities for better surveillance and control of emissions. Earlier and recent industrial measurements towards FeSi- and Si-metal furnaces reveal quite high NO-emission. The NO is believed to be produced in the combustion zone above the furnace surface, mainly as thermal NO.In order to expand the knowledge on NO-formation in silicon metal production, a pilot scale experiment in a 440 kVA silicon furnace has been carried out. The experimental set-up was designed with a view to be able to copy and manipulate the formation mechanisms for NO by controlling the flow of false air into the off-gas system.The resulting NO-values corresponding to the different air inlet to the furnace top, show significantly differences between the different air inlet geometries.IntroductionNOx is the common notion for the two gases nitric oxide (NO) and nitrogen dioxide (NO2). Since combustion of fuels, such as gasoline, diesel, bio diesel, propane, coal, and ethanol, forms NOx the dominating contributors to NOx emissions are the on-/offshore transportation industry and power generation based on fossil fuels [1]."

Jan 1, 2012

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean useage, the porphyry deposits are divided into either: (a) a stockwork, or (b) a tourmaline breccia model. Stockwork type deposits tend to occur on major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusive. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with tourmaline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusive8 which have a close time-space relationship to ore and in each model, mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alterntion halos (phyllic, argillic, prophllitic) as are developed in intru- sive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1973

By J R. Taylor, J A. Muchan, S M. Pape, B S. Davis

Acid and metalliferous drainage (AMD) is routinely derived from waste rock, tailings, pit wall rock, underground mine voids, heap leach pads, ore stockpiles, concentrate stockpiles and even slag piles. In many jurisdictions, there is an assumption that tailings materials represent the highest AMD risk. This is likely due to their highly sulfidic and ultra-fine grained nature, and the fact that they occur in large tonnage, partially unsaturated deposits. These characteristics are not unreasonably associated with reactive and therefore highly polluting mine waste materials. Interestingly, however, the high sulfide content and highly reactive nature of tailings achieves the rapid consumption of oxygen in tailings pore spaces. This oxygen depletion can limit or halt sulfide oxidation throughout much of the tailings pile. Oxygen can only be resupplied to the tailings via atmospheric exchange at the air-tailings interface. The grain size of most tailings materials limits this resupply to a diffusion related process that only affects the uppermost 100–2000 mm. Hence sulfide oxidation in tailings can be inherently self-limiting. Unfortunately, the same cannot be concluded for waste rock materials.Using a unique site assessment strategy that focuses on quantifying acidity fluxes from various domains at a mine site, it has become increasingly evident that sulfidic waste rock produces the majority (typically 60–80 per cent) of the soluble acid and metalliferous pollution at most active and decommissioned sulfide-bearing mine sites. Whether sulfidic waste rock is disposed in engineered above ground facilities, backfilled into pits or even underground voids, it remains the primary source of pollutants for decades to centuries.Conventional end-dumping waste rock practices result in angle-of-repose pathways for air and water, and these internal fabrics exacerbate sulfide oxidation (ie pollution generation) and discharge from waste rock materials. The primary aim of many cover systems is to retard the access of air and water to these conduits. Recent thinking is that more emphasis needs to be directed at strategic waste rock pile construction practices, and less reliance placed on thin soil cover systems to prevent AMD.Waste rock pile construction approaches that minimise porosity and permeability but raise the retained moisture content and enhance water residence times have the potential to lower sulfide oxidation rates and thereby improve water quality outcomes. For example, innovative base-up, layered and compacted (BULC) waste rock piles have the potential to avoid or minimise the generation of AMD, supersede the need for treatment and facilitate successful closure and relinquishment across the mining sector (Figure 1).CITATION:Taylor, J R, Pape, S M, Davis, B S and Muchan, J A, 2016. Waste rock pile construction to lower closure and relinquishment costs, in Proceedings Life-of-Mine 2016 Conference, pp 97–99 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By F. Habashi

"While bioleaching of pyrite concentrates has been successfully used in industry to liberate gold from the sulphide matrix for subsequent cyanidation, the same technology cannot be recommended for leaching chalcopyrite concentrates for copper recovery. It will be shown to be uneconomical and cannot compete with pressure leaching technology. Data on the pilot plants that were constructed for this purpose and were shut down will be given.INTRODUCTIONBacterial leaching has been successfully applied for heap leaching of low-grade copper ores (Habashi, 1978, 1999). One of the major operations is that at Bingham in Utah (Figure 1). The leach solution collected at the bottom of the heap is extracted by organic solvents and the strip solution is electrolyzed to get high purity copper. The process was extended to treat auriferous pyrite concentrates to liberate gold and render it amenable to cyanidation by a process known as BIOX (Marsden & House, 2006; Lunt & Briggs, 2005).BIOX plants currently or recently in operation are the following:??Ashanti Goldfields Company, Ghana. Designed with an initial capacity of treating 720 tonnes of concentrate per day, the Sansu plant has since been expanded and currently has four modules processing 960 tonnes per day in all. It is by far the largest biooxidation plant in the world. The capital cost of the plant totalled US $25 million (1994 terms) and the operating cost is currently US $17/tonne milled.??Fairview, South Africa. The plant at the Fairview mine in Barberton, which was the initial pilot plant, has been fully operational since 1986. It was originally designed to treat 10 tonnes/day of concentrate but with the success of the project this has been increased to 55 tonnes per day. With the purchase of Fairview by Avgold’s Eastern Transvaal Consolidated, Avgold concluded a licensing agreement with Gold Fields, formerly known as Gencor, entitling it to use the BIOX technology to treat itsconcentrate.??Saõ Bento, Brazil. A BIOX plant was recently in operation in Brazil at the Saõ Bento Mine where a pressure oxidation circuit is used to treat the refractory flotation concentrate. This plant has confirmed the viability of combining bio-oxidation with pressure oxidation as a cost-effective method ofincreasing capacity at an existing oxidation plant.??Wiluna, Australia. The plant at Wiluna Gold Mine, Western Australia, was commissioned in 1993. Although originally designed to treat 115 tonnes per day of concentrate this has subsequently been increased to 158.??Other plants at Tamboraque in Peru, Harbour Lights and at Youanami in Australia have been commissioned recently."

Jan 1, 2012

By Bruce L. Bryson

In the past decade a principal growth area in refractory technology has been the development and use of extra high alumina refractories. The refractories user is asking for, and is prepared to pay for, higher purity, more dense materials with longer life, less maintenance, and better dimensional tolerance to meet the exacting demand of high output processes. High alumina and bauxite refractories are being used more and more to keep pace with the demand for guaranteed performance. The steel industry, for example, is starting to place great reliance on these products. A unique material now available with all the requirements for extreme purity and density is tabular alumina, already proving itself in many refractory applications.

Jan 1, 1973

By K. El-Barawi, Hussein M. Kamal

Chlorination was performed of iron-rich chromite ore from Barramyia, United Arab Republic (UAR), together with its concentrate. The effects of change of grain size, chlorine gas flow rate, time and temperature were studied. The extent and mechanism of chlorination were followed through chemical and structural analyses of the feeds and complete chemical analysis of the chlorination products. By conducting the chlorination process for short periods at 600°C or lower temperatures, products having high Cr-Fe ratios suitable for ferrochrome production can be obtained.

Dec 1, 1971

By Kenneth A. Brunk

"This address discusses how ""Mineral Processing Technology"" can play a major role in the life and profitability of a mining company. Examples of past and present technological breakthroughs and their impacts will be examined. Also, the future of processing technology will be emphasized.IntroductionThis talk will center on the role of technology as an important component of a business plan for mining companies. I'll attempt to explain how I see technology development as an underpinning of a successful mining company. We will examine an example of a technology that has resulted in a re-birth of segments of the industry, examine a technology life cycle and discuss technology as it relates to ore reserve replacement. Also, we will touch on technology in today's mining company and propose some food for thought for those designers of corporate organizations."

Jan 1, 1997

By Jerry F. Fountain

Variations in ore grade, mineralogy, and copper pricing structures over the life of the Inspiration mine have mandated many modifications to the treatment methods to maximize process economics. In the 1970's, copper prices generally declined, while inflation, wages, and interest rates increased. A metallurgical treatment route had to be developed for this continuing economic climate which would be capable of minimizing labor, energy, and capital cost requirements. After many years of development, the patented "Ferric Cure" process was introduced to satisfy these requirements. This dump leach process for treatment of mixed oxide/sulfide ore includes: strict mineralogical control of ore placed for leaching, controlled leach pad construction, solution saturation and curing of the pads with higher acid concentrations, and, finally, rinsing of the cured pads for removal of dissolved copper. Leach solutions, high in sulfuric acid during the cure application and low in sulfuric acid during the rinse, contain sufficient ferric iron to enhance the leaching of chalcocitic sulfide minerals.

Jan 1, 1983

By Yanagase T, Nakamura T, Ueda Y

The possibility of removing the phos phorus and sulphur contained in steelmaking slag has been studied by observing directly through the microscope melts heated on Pt- filaments. After a CaO crystal was placed in the molten slag, distributions of P, S and other elements formed around the CaO crystal were determined with the aid of EPMA. The results indicated that a layer of 2CaO SiO2 is formed on solid CaO in CaO-Si02 melts. Then between CaO and the newly formed compound the molten slag tends to migrate through cracks. For higher Fe 2 03 contents, the layers of the compounds 2CaO.Si02 and 3CaO SiO2 formed around the CaO crystal are not continuous but look more like particles, which promotes the dissolution of CaO. Phosphorus in slag was found to be enriched in the 2CaOòSi02 layer. Phosphorus in the 2CaO SiO2 phase is not related to the primary slag composition, being about 5-7% P205.. Sulphur in slag,as well as the phos- phorus,was concentrated in the 2CaO.Si02 phase. Disintegration due to weathering observed for slags produced in these investigations appeared to be due principally to hydration of lime.

Jan 1, 1980