Search Documents

As part of its regular program to provide timely information on domestic mineral commodities, the Bureau of Mines conducted an engineering appraisal of more than 1,300 lode and placer gold deposits in the United States to deter-mine their gold production potential. While these deposits were estimated to contain over 400 million ounces of gold, only 9 million ounces, or slightly more than 2 percent, was found to be producible at $35 per ounce under prevailing mining and metallurgical technologies. The study revealed that any significant increase in available gold in the United States is most likely to come from the discovery of new sources, intensive exploration and development of the more promising known mineralized areas, and development of new or improved mining and metallurgical techniques.

Jan 1, 1967

By J. J. Poveromo

"Iron ore for alternate iron processes concerns alternate iron products designed for use in EAF (electric arc furnace) steelmaking processes. These alternate iron products include both DRI (direct reduced iron), HBI (hot briquetted iron) and merchant pig iron. Merchant pig iron can be produced in conventional blast furnaces, mini blast furnaces (including charcoal BF's) or novel processes such as RHF/SAF (rotary hearth furnace/submerged arc furnace) such as Iron Dynamics or RHF such as Mesabi Nugget. These novel processes are coal based and can use iron ore concentrates or recycled steel plant oxides. The blast furnace processes can use conventional feed materials: pellets, sinter, lump ore and coke. However, DRI and HBI processes are predominantly pellet based but require DR grade pellets that are low enough in acidic gangue (SiO2 and Al2O3) to avoid additional expense in the EAF process This paper will focus on the quality and availability of DR grade pellets for NAFTA DRI/HBI plants but also concentrates for fines based processes and feed materials for merchant pig iron production. INTRODUCTION This paper will outline alternative (to the blast furnace) competitive ironmaking processes and process routes. Within each section the types of iron ore to be utilized will be discussed. Before discussing some of the details of these processes, it may be appropriate to review some definitions and commonly used terms within this industry. DefinitionsDirect Reduction: Reduce iron oxide to metallic iron without melting. Unreduced ore compounds remain as undesirable oxides • Direct Reduced Iron: Iron oxide feedstock exits in same form as entered (pellets in, pellets out; lumps in, lumps out) • Hot Briquetted Iron: DRI that has been hot (1200°F, 650°C) briquetted to a high density pillow shaped briquette • Hot Metal: Molten iron in liquid form, above 2500°F, 1370°C • Pig Iron: Solid product of the iron blast furnace • Residuals: Undesirable elements such as copper, nickel, chromium, tin, sulfur, molybdenum and phosphorus • Gangue: Rock minerals in the iron ore such as silica (SiO2), alumina (A2O3), calcia (CaO), magnesia (MgO). These remain in the oxide form in DR processes. • Reduction: Fe2O3 + 3 CO = 2 Fe + 3CO2 2 Fe2O3 + 3 H2 = 2 Fe + 3H2O (Fe2O3 > Fe3O4 > FeO > Fe)"

Jan 1, 2018

By Q. G. Reynolds

The presence of dust and fume suspended in the freeboard region is a common feature of the operation of direct current (DC) plasma smelting furnaces. This occurs primarily as a result of the use of fine feed materials together with the open-arc, open-bath operation of such smelters, and is exacerbated by the high velocities and turbulent mixing of the gas in the vicinity of the arc jet. Dust and fume losses into the furnace off-gas system can be significant in some cases and may have economic, operational, and environmental impacts on the process. A computational modelling study is presented in which the concentration of dust material was considered as a continuous field subject to a governing partial differential equation. Settling behaviour was calculated as a function of particle size, local gas/plasma temperature, and other physical properties. Development of the coupling between the concentration field and a magneto-hydrodynamic description of the arc is shown, and the resulting models were used to compute various aspects of the behaviour of the concentration field in the arc region for a variety of furnace conditions. Time-averaged as well as transient models of the arc were used to generate the results presented. Qualitative case studies produced several practical suggestions for furnace operation, including increased dust capture by the bath when feed ports are located closer to the electrode, and the possible effects of feed segregation in the furnace freeboard based on dust particle size and density.

Jan 1, 2014

By V. R. Miller

The Bureau of Mines conducted research on substitute brazing filler alloys with properties similar to those of silver filler alloys in an effort to conserve silver and reduce hazards from cadmium emissions. Experimental work was conducted first on the commercial silver brazing alloys BAg-I, BAg-la, BAg-2, and BAg-3 to establish criteria for evalu-ating the substitute alloys. Properties investigated included the wettability of copper, brass, and steel substrates, and the strength of joints made with the filler alloys. A series of experimental alloys containing 50 to 60 pct Cu, 20 to 28 pct Mn, and 17 to 30 pct Zn was prepared and evaluated, together with Cu-Mn-Zn alloys with 5 pct Pb or 2 pct Ni. Wetting properties and joint strengths were not as good as those for silver filler alloys, and the high application temperatures reduced the copper and brass base metal strengths. However, experimental alloys containing 70 pct Cu, 15 to 20 pct Mn, and 10 to 16 pct Sn had wetting and strength properties approaching those of the silver filler alloys. The application temperatures for these alloys were high-er than those for silver fillers, but not as high as those for the Cu-Mn-Zn alloys. With the Cu-Mn-Sn alloy fillers, copper alloy joint members are less deteriorated by recrystallization than when applying Cu-Mn-Zn alloys. The Cu-Mn-Sn system has potential for further devel-opment as a substitute brazing alloy system, particularly if the melting temperature can be reduced by the addition of other elements without decreasing the ductility and wetting.

Jan 1, 1983

By C. R. Julian

THE large pyrites ore-bodies, the underground mining of which is to be described, are situated at Rio Tinto in the Province of Huelva in Southern Spain. The situation of the different ore-bodies with relation to one another is shown in Figure 1. It will be seen on the plan that the strike of the ore-bodies is approximately east and west. The geology of the district has been very fully described by Dr. D. Williams (1), so that for the purposes of this paper it will be sufficient to give briefly the salient features o each of the two larger ore-bodies which are being mined by underground methods at the present time. (a) San Dionisio.-This ore-body is the largest single deposit in Rio Tinto, having on its upper levels a length of 3,500 ft. On the upper levels the average width is approximately 200ft. but in places on the lower levels there is a width of 900ft. of un broken pyrites. Diamond-drill holes, without running out of ore, show the ore-body to persist to a depth of at least 1,600 ft. The ore-body in the upper part lies between slate and porphyry walls, but in depth is enclosed in porphyry walls. (b) South Lode.-Faulting is considered to be responsible for the break in the solid ore between South Lode and San Dionisio. On the upper levels, the South Lode ore-body has an unbroken length of 4,000 ft. The massive pyrites has a maximum width of 300ft. and an average of about 100 ft. Ore has been proved to a depth of 1,000 ft., at which depth the ore-body is much reduced both in length and breadth. This ore-body, to the depth at which it has been proved, lies entirely between slate and porphyry walls. The South Lode and the San Dionisio ore-bodies are mined both by open-cast and by underground methods. There is evidence that these mines have been exploited intermittently during the last 3,000 years; but, as is to be expected, no records are available of the tonnage mined prior to the time of purchase by the present company.

Jan 1, 1940

By D Frost, G Harbort, T Lipiec, N Deonarain

"The use of flotation columns has remained a contentious issue among mill operators. There are those who consider them an essential part of any mineral processing operation, while others consider them a necessary evil, which should only be installed if there is no alternative. Lastly, there are those who believe they should not be installed, no matter how great the perceived benefit.This paper provides an analysis of over 4000 installed flotation columns, contained in the Amec Foster Wheeler flotation database. Changing trends in column flotation use by type, commodity and geographical region are discussed. The effect of changing commodity prices and the China ‘phenomenon’ are reviewed. Special reference is made to the changing face of column flotation in Australia.Of note is the fact that after falling to a 20 year low in installed flotation column capacity in 2014, flotation columns during 2015 went through a resurgence in popularity. This resurgence was in direct contradiction to depressed metal prices and was driven by brownfield optimisations to reduce off-site costs, particularly in base metals. A case study is presented comparing the benefits of column flotation at high commodity prices with low commodity prices.Citation:Harbort, G, Deonarain, N, Frost, D, Lipiec, T and David, D, 2016. Changing Trends in Column Flotation Use - Their Impact for Australian Mill Operators, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 93–104 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By C T. Dunbar, P A. Walker, G E. LeJuge

A programme of blast improvement was initiated at the Mt Whaleback iron ore mine by BHPIO management in early-1998. One component of that work was the need to improve wall control blasting practices to better achieve the designed pit slope elements. This paper describes the geological conditions in which pit walls are developed, the mine operating equipment, the blast design concepts applied to minimise blast damage, the techniques applied in an assessment of the blast performance and the operational procedures developed to ensure that the blast concepts are effectively implemented in the production environment. Substantial changes have been implemented in both technical and operational aspects of the mining operation in order to achieve the improvements in pit wall condition, in particular recognising the need for a more flexible approach to limits blasting in response to highly variable and complex geology. The benefits to the mine are not only an improved wall condition, but increased confidence on the part of mine management that mine plans may be implemented on design and on schedule.

Jan 1, 2001

By Arthur F. Hagner

The titaniferous magnetite deposit at Iron Mountain, Wyoming, is in Precambrian anorthosite. Individual ore bodies are lenses, commonly arranged en echelon, conformable to the platy crystal structure and compositional layering of the anorthosite; a few transect these features at various angles. The ore bodies are on the east flank of the principal anticline in the anorthosite mass. Magnetite and ilmenite, accompanied by spine!, are the ore minerals. The principal gangue minerals are olivine, which was introduced with the ore, and plagioclase, the chief constituent of the anorthosite. The anticlinal region appears to have been a structurally weak zone, and westward-bowing curves of the axis were especially favorable sites for localization of the two largest massive ore bodies. These bodies are synclinal and plunge southeast. The proportion of magnetite-ilmenite to olivine and to anorthosite appears to be related to structural features. Where magnetite-ilmenite is present with olivine, the magnetite-ilmenite is encountered along the most pronounced parts of a fold where anorthite content is highest, whereas olivine is associated principally with more gently folded portions. During granulation and recrystallization of the anorthosite mass, temperature and pressure changes furnished the energy required to release and mobilize iron and other elements that migrated to areas of low pressure, the ore zone. Some iron and magnesium may have combined with silica from partly dissociated plagioclase to form olivine. The ore formed by replacement of anorthosite as indicated by: (1) the marked changes in mineralogy along strike, dip, and plunge of an ore body; (2) the concentration of massive ore in folds and olivine on limbs; ( 3) the halo of low-grade mineralized rock that transects the structure of the anorthosite in the hanging wall; and ( 4) the layering in the large southern ore body, that strikes more easterly than the trend of the body.

Jan 1, 1968

By Larry F. Brown

Mining has been the mainstay of the Woods Creek Valley for more than a century. The head of the valley is at the Continental Divide, about 50 miles west of Denver, Colorado. First, it was the quest for gold and silver that drew people to the valley. Then, when molybdenum was classified as a strategic metal by the U. S. Government during World War I, it was the valley's molybdenum mineralization which attracted the most attention. Molybdenum is used primarily as an alloying material in superior grades of steel. Circumstances responsible for providing the label "Urad" are unknown, but Urad is variously reported to be an acronym for "Uranium Research and Development" or "Uranium Research of America Division". The search for uranium was fruitless as no ore grade uranium exists in this area. The moly orebody was first developed and mined by the Primos Exploration Company from 1914 to 1919. During World War II, the mine was purchased by the government and turned over to the Molybdenum Corporation of America to operate. In 1963 AMAX Inc. purchased the property for $2 million. After spending nearly $30 million for exploration and development, AMAX put the mine into production again in 1967.

Jan 1, 1984

By J. A. Finch

For base metal sulphides, iron rejection starts in mineral processing. This review focuses on the changes in plant practice specifically to improve iron sulphide rejection by controlling contaminant ion effects and discusses selected innovations in mineral processing that can be expected to play a role in iron control. One change to control contaminant ions is size reduction (the use of stage grinding and inert stirred milling) and another is system chemistry (order of reagent addition and exploitation of the flexibility of sulphoxy species). Plant examples illustrate the successes, and indicate that there are several options available. The general innovations consider the new tools for measuring gas dispersion properties and quantifying froth characteristics from images. Examples of their application to improve concentrate quality illustrate the potential. Other innovations adapt geostatistics to model variations in ore flotation response to provide feed forward control and rigorously apply the statistical experimental methodology in plant test work. An example from one concentrator shows that significant improvements to reduce the iron content of concentrates can be achieved by applying these basic principles.

Jan 1, 2006

By J. A. H. Church

The report is too voluminous to be considered in detail within the scope of a single paper, so I will confine my consideration of it to the broader aspects, leaving other members to deal with points of particular interest. The method of presentation leaves one with an uneasy sense of prolixity and confusion of thought; the foreword by the Chairman may well be accepted as a true index of the whole. His argument amounts to this: Recognizing at the outset the futility of divided counsels, it was deemed advisable to arrive at unanimity. To this end, some members subscribed to views to which they do not whole-heartedly assent, thus giving weight to conclusions with which they were at variance. Unanimity cannot be qualified-either it exists or is absent-and, moreover, in the text of the Com-mission I can find no word that unanimity is required. Surely it would have been preferable to have a unanimous report covering such aspects as were acceptable to all members, with minority reports by individual members on such other aspects as were controversial, leaving it to the Government to give such weight to the divergent views as the personality of their sponsors might warrant. In the final analysis the value of an opinion varies directly as the personality of its exponent.

Jan 1, 1926

"Option pricing is used in finance for valuing options to buy (or sell) shares at some future date because it provides a convenient framework for quantifying values subject to uncertainty. As one of the main sources of uncertainty in mining is the price (sales) of the metal, this approach can also be used for valuing mining projects.The first part of this paper reviews options and option pricing; the second part presents the approach developed by Brennan and Schwartz (1985) for using option pricing to value natural resources. Several applications of this methodology have been published; these are described. From a mining point of view, the assumptions made by Brennan and Schwartz are too simplistic. The weaknesses are discussed with a view to improving an apparently promising new way of assessing the value of projects. IntroductionThe collapse of the British merchant banking group, Barings, has highlighted the risks that can be incurred by speculators and arbitragers in the futures and options markets. But this negative attention on futures and options should not make us forget their positive aspects. They can provide producers and consumers of metals with more predictable sales prices. The introduction of the new traded average price options, TAPOS, by the London Metal Exchange in January 1997 is a response to this need. Equally important, the theory that the finance industry has developed for valuing options provides an interesting framework for valuing mineral projects as well. While this paper was being revised, the South African gold mining house, JCI, announced that it was using a methodology based on option pricing for valuing the mineral rights to deeplevel gold resources (see Box 1)."

Jan 1, 1997

By Paul R. Smith

The theoretical requirements for the flotation d large particles are discussed. A flotation machine is described which has components which meet many of the theoretical requirements for the flotation of large particles. The machine's salient features include multiple fine-bubble attachment, froth level feeding, quiescence, shallow depth, and short flotation time. Test conditions and results are presented for the laboratory flotation of 10 mesh phosphate, 4 mesh potash, and 1/2 inch coal. In addition, test conditions and results of pilot plant flotation of minus 14 plus 35 mesh phosphate and minus 14 plus 150 mesh phosphate are also presented.

Jan 1, 1969

By V. A. Cooney

Introduction For the compliment paid me by the Institute's kind invitation to speak this afternoon, I am very grateful. For the astuteness of your officers in determining that encouragement should be given, through the medium of a paper, towards accident prevention in coal mines, the coal industry cannot but be grateful. Some day, and let us hope soon, a more developed paper may supersede this one. In the meantime, if some knowledge of what one coal field has been able to accomplish, even in the initial stages of its effort, will induce other fields and other sections of the mining industry to launch similar experiments, much good will result and a more developed dissertation on the subject will make its appearance.

Jan 1, 1946

By A. Kontopoulos

Refractory sulfide gold ores or concentrates require an oxidation pretreatment step to yield the contained gold amenable to the subsequent leaching step. The process options for oxidation pretreatment can be broadly classified as follows: roasting, high or low pressure oxidation bacterial oxidation, chemical oxidation, each with a number of alternative suboptions. Roasting and high pressure oxidation are being applied on an industrial scale; the stage of development of the other options range from preliminary laboratory to advanced pilot plant- In this paper, the major technical, environmental and economic aspects of the above processes are being discussed. Future industrial trends will also be considered. Particular emphasis will be placed on the treatment of arsenical ores and concentrates, where safe plant operation as well as, handling and disposal of the arsenic containing products and/or effluents 'and residues is of paramount importance.

Jan 1, 1990

By D. A. Douglass

This report describes the tri-n-butyl phosphate extraction of cerium (IV) from a sulfate leach liquor prepared from a bastnaesite concentrate as well as from pure eerie nitrate solutions. The work was done on a laboratory scale using separatory funnels. Extraction from pure cerium solutions entailed no great difficulties; however, extraction from the bastnaesite solution proved more difficult, mainly because of the inhibiting effect of the sulfate ion. Despite this, procedures were developed for obtaining good single-state cerium extraction (95+ percent) and a high-purity product (99+ percent), although the maximization of both cannot be achieved simultaneously. This necessitates a compromise in any extraction scheme.

Jan 1, 1959

By D. R. Spink

An historical background is presented to provide a basis for the lack of normally expected developmental effort over the first 20-25 years of viable zirconium production operations. This is followed by a description of developing technology, which is the result of years of research and piloting effort directed to the development of a more economical method to produce high-grade metallic zirconium. It is predicted that many of the process improvements described will have a significant impact on future zirconium production methods and consequently on future prices and markets.

Jan 1, 1977

By D. W. Boydell

The response of reclaimed gold tailings to acid leaching was investigated in the laboratory, followed by a pilot-plant program in which the operations of CCD, CIX and SX were tested with plant feed material. These results formed the basis for the design of the extension to the existing uranium plant at Blyvooruitzicht Gold Mine, commissioned in July 1977. This circuit consists of slimes-dam reclamation by bucket-wheel excavator at a rate of 100,000 t solids per month, acid leaching in pachucas, a five-stage CCD washing section, two parallel C1X absorption columns and two elution columns, SX and an ADU precipitation section. Barren solution is recycled to the CCD section as wash and to the repulper at the slimes dam. The performance of the plant during the first year of operation is compared with the predictions on which the plant design was based. Rated capacity was achieved within three weeks of start-up at a nominal dissolved uranium recovery in the ion-exchange section of around 98%. Owing to recycle, the over-all recovery in the ion-exchange and solvent extraction sections is somewhat higher than this figure.

Jan 1, 1979

By A. H. Rhoades

The modern polarizing microscope with such accessories as cameras, infrared devices, reflectance and/or transmission photometers, indention hardness, and heating stage is used to characterize coal, coke, and other carbon forms. It allows characterization of coke by-products, such as tars and pitches and their insoluble residues. A useful product of the microscopic approach is the coal petrographic analysis which permits the prediction of coke strength carbonization pressure and volume change. Carbonization tests are expensive, time-consuming and require large amounts of coal. Tests on the coke show it to be strong or weak but give no indication of why. Petrographic analysis requires grams of coal and yields data that indicates why the coal produces coke of a given quality. Small samples from drill cores are sufficient for petrographic analysis. These data are also used to optimize blends for coke production. When coke-plant problems occur, ~he microscope can be used to check the coal blend proportions, as well as for weathered coal. Microscopy is useful in spore correlation work which may be a prerequisite to sound coal reserve estimates. Dispersed vitrinoid reflectance studies are used to determine the degree of organic metamorphism which serves to establish oil and gas deadlines. Tars and pitches are examined microscopically for the amount of normal solids as well as the size of undesirable carry-over solids resulting from pollution abatement practices in coke works. The microscope is also used to study coals for gasification and liquefaction.

Jan 1, 1981

By E. C. de Beer

"SynopsisA number of important areas in nuclear fuel cycle, at both the front end and back end, offer ideal opportunities for the application of non-destructive evaluation techniques. These techniques do not only provide opportunities for non-invasive testing of e.g. irradiated materials, but also play an important role in the development of new materials in the nuclear sector. The advantage of penetrating radiation used as probe in the investigation and testing of nuclear materials makes X-ray and neutron radiography (2D) and tomography (3D) suitable for various applications in the total nuclear fuel cycle. The unique and different interaction modes of the two radiation probes with materials provide several opportunities. Their complementary nature and non-destructive character makes them most suitable for nuclear material analyses, analytical method development, and the evaluation of the performance of existing nuclear material compositions. This article gives an overview of the X-ray and neutron radiography/tomography applications in the field of nuclear material testing, and highlights a few of the success stories. Several selected areas of application in the nuclear fuel cycle are discussed to illustrate the complementary nature of these techniques as applied to nuclear materials.IntroductionDuring the development of new materials for the nuclear industry, materials testing and characterization are of the outmost importance to maintain safety standards and reliability. No compromise on safety in the workplace in any area within the total nuclear fuel cycle can be tolerated, and therefore most in-situ material characterization and testing is conducted by certified and qualified personnel schooled in destructive and non-destructive testing (DT and NDT) methods. Certification and qualification in NDT can be obtained through many training centres in South Africa in accordance with European, American, and other international standards (SGS, n.d.; SAIW, n.d.; African NTD Centre, n.d.)."

Jan 1, 2015