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By B. Haneman, J. A. Gorst, W. Slabbert

"The Bayer process involves the digestion of bauxite in caustic liquors at high temperature and pressure. Typically the digestion section of the plant involves the heating of liquors up to the digestion temperature followed by flashing of the digestion product to atmospheric pressure with the flashed steam used to pre-heat the incoming cold slurry. Despite the heat recovery, the digestion process is a high consumer of energy. The application of tube digestion technology in such plants has resulted in significant improvements in refinery energy efficiency with associated benefits of process simplification and refinery flow sheet capital cost reduction. This paper reviews the potential application of this technology to other metals within the non-ferrous industry.THE BAYER PROCESSA typical Bayer flow sheet is shown in Figure 1. The raw feed material bauxite (containing aluminium hydroxide as gibbsite Al(OH)3 and boehmite AlO(OH)) is digested in caustic liquors (caustic soda is the solvent) at high temperature and pressure. This process extracts the alumina and silica and any carbon present on the ore. The slurry is then flashed down to atmospheric condition allowing for heat recovery from the flashed vapour and producing slurry supersaturated in alumina.Following the digestion process the mud is removed via thickening and then pressure filtration to remove fine particulate and produce a clarified liquor with dissolved alumina in solution. The resulting pregnant liquor is then cooled allowing the alumina in solution to precipitate as aluminium trihydrate Al(OH)3. The precipitated hydrate is then filtered and washed and classified into fine and coarse fractions. The fine material is returned to the precipitation process as seed while the coarse fraction is calcined at high temperature to produce alumina. The filtrate from the filtration process (spent liquor) is then heated by the incoming pregnant liquor before being fed to an evaporation process which produced the strong caustic liquor required in the digestion process. Finally, the mud from the thickening process is washed to recover caustic and then fed to tailings ponds. The washer overflow is then mixed with the digester product to increase super-saturation."

Jan 1, 2012

By Yoginder P. Chugh

This paper discusses an ongoing field study in southern Illinois (USA) that focuses on: 1) Identifying mechanisms of instability in the set-up rooms (SR) and their T-junctions with headgate and tailgate entries, 2) Developing alternate 3-entry and 4-entry set-up rooms geometry using 3-D numerical analyses, 3) Implementing developed geometries in cooperation with mining professionals and regulatory agencies, and 4) Demonstrating performance of implemented geometries through field monitoring. Illinois longwall mining operations typically experience ground control problems (roof falls, rib sloughing, floor heave, etc.) within SR layouts and around the T-junctions of SR. These occur around the areas where the SR for adjacent longwall face (to be mined) connect with the SR of the previously mined face, and around the tail-gate entries of the mined-out longwall face and around the T-junctions of SR. The problems manifest as highly fractured immediate roof strata, major shear zones in the roof, horizontal displacements within the excavations that result in shearing off the heads of the bolts, floor heave and severe rib sloughing. Similar observations have also been made in longwall mining in Utah.

Aug 1, 2013

By H. Shafick Hanna

The major problems are identified the high phosphorus content and the fine dissemination or encapsulation of mineral impurities, in, ,the iron bearing minerals, A process which combined extreme fine grinding techniques with magnetizing roasting or flotation separation methods, is suggested. By these methods concentrates assaying 60-61 percent Fe exceeding the widely accepted upper limit of 56 percent Fe set for these ores, were produced with 75-90 percent iron recovery. Moreover it was shown that the phosphorus content of these concentrates could be reduced from 0.25 to 0.03 percent phosphorus by acid leaching. A brief discussion on production costs based on current and future developments in iron ore processing is given.

Jan 1, 1980

By Richard D. Mehring

A refined ad improved self-sealing brattice for use in coal mine rescue and recovery operations for directing the flow of air has been developed and tested by Goodyear Aerospace Corporation for the U.S. Bureau of Mines. The brattice is made from a lightweight, low cost material that meets MSHA flammability requirements. The units can be erected using pins, spade or lightweight extensible poles. Tests here conducted to determine leakage rate from minimal to a maximum of 1.5" H20. The ability to handle reverse flows was demonstrated and a non-flammable foam was used as an auxiliary sealing agent.

Jan 1, 1978

By M. R. Geer

The widespread adoption during the past decade of the dense-medium process for cleaning coal increases the need for technologic studies of the process. Such studies provide information that will insure maximum usefulness of this process in its present form and may well lead to substantial improvements in design and opera¬tion. The Bureau of Mines has published the results of cleaning trials on a wide variety of coals in two dense-medium pilot plants5/ and reported the recovery of coal from waste by dense-medium treatment.6./ The present report deals with the viscosity of magnetite dense medium, an important subject about which virtually nothing has been published. Specifically, the report concerns methods for measuring viscosity, the influence of various medium contaminants on viscosity, the effect of viscosity on cleaning results, and the influence of viscosity on consumption of medium. Cleaning trials on four coals of varied density composition in a pilot plant, using mediums of different viscosities, showed a steady reduction in cleaning efficiency with increasing viscosity in every instance. However, the behavior of each coal in a viscous medium was distinctly individual. With one, an increase of only 1 centipoise in viscosity caused a reduction in recovery efficiency of 7.7 percent, whereas the same increase in viscosity with another reduced recovery efficiency only 2.7 percent.

Jan 1, 1957

By Robert W. Geehan

A preliminary examination of the Dayton iron deposit was made in 1941 and 1942 by Paul E. Pesonen and O. H. Metzger, engineers of the Bureau of Nines. Trenching and sampling were recommended, to be followed by core drilling if favorable results were obtained. The Bureau of Mines conducted a project at the property from June to December 1942. The deposit is in sec. 6, T. 17 N., R. 23 E.; sec. 31, T. 18 N., R. 23 E.; sec. 36, T. 18 N., R. 22 E.; and sec. 1, T. 17 N., R. 22 E., M. D. B. & M., about 15 miles west of Lahontan Reservoir in Lyon and Storey Counties, Nev. It lies at an altitude of about 4,500 feet north of the Carson Plains, in the foothill section of mountains that rise to about 7,000 feet to the north of the property. The deposit may be reached by driving 12.5 miles northeast of Dayton over U. S. Highway 50, thence northerly 2.7 miles over a dirt road to the property. The climate is hot and dry in summer, with occasional thunderstorms some of cloudburst variety, and frequent high winds. Winters are usually moderate, with light snowfall and some subfreezing temperature.

Jan 1, 1949

By C. J. Hall

Twenty eight pulse release sulfur hexafluoride tracer gas field tests were run in a multi-level multi-vein hard rock mine to measure leakage ventilation. The mine had numerous underground booster fans and gob filled old stoping areas and consequently numerous leakage paths. The tests proved that the equipment and methods developed by the USBM can be used successfully in complicated ventilation circuits. The leakage quantities varied each time a major change was made in the main ventilation circuit. Usually leakage quantities had to be remeasured after a main ventilation change, but measurements could be duplicated for anyone configuration except under certain defined circumstances. The characteristics of an individual leakage path could be determined from the difference between the measured sum of two paths and the calculated characteristics of one of the paths. Many leakage paths could not be evaluated accurately on one shift. Comments are made on equipment performance and field techniques. Programs for the calculation of gas concentrations and recirculation from measured data and for the mechanical integration necessary for a calculated leakage characteristic have been written for an HP 9810 and are included.

Jan 1, 1975

By Wesley A. Grosh

The Cuyuna range in central Minnesota has been the source of substantial tonnages of, manganiferous iron ores for almost four decades. To Increase the Nation's self-sufficiency in manganese reserves, the Bureau of Mines initiated a comprehensive investigative program to determine and develop the potential manganese reserves in the region. In the course of compiling all available information on the Cuyuna range, the Scallop-Todd lease appeared to be an area having favorable possibilities for developing substantial reserves of manganese. Early drilling on this lease indicated considerable tonnages of material relatively high in manganese. More recent drilling substantiated the size of the deposit but Indicated lower manganese values. However, beneficiation tests of samples obtained from the recent drilling indicated that the material was amenable to concentration.

Jan 1, 1953

By W. R. Hardwick

This paper describes mining methods and practices of the Morenci Branch, Phelps Dodge Corp., Greenlee County, Ariz. It is one of a series being prepared by the Bureau of Mines on mining methods, practices, and costs in various mining districts in the United States. A similar program, conducted from 1928 to 1939, was generally conceded to have contributed substantially to improving the efficiency of mining operations. The morenci open-pit mine (see photograph, fig. 1) is in southeastern [zona] (fig. 2), on U.S. Highway 666 about 5 miles north of Clifton, county at of Greenlee County. The concentrator and smelter are near the mine at an altitude of about 4,400 feet. Figure 3 is a map of the mine and plant.

Jan 1, 1959

The Australian Centre for Minesite Rehabilitation Research (ACMRR) was established through a mining industry initiative to meet the need of industry, governments and the community for sustainable systems for land affected by exploration, mining and mineral processing activities. The Centre, which is a consortium of the major groups associated with mining rehabilitation research in Australia, has a focus on both strategic research and technology transfer and combines a wide range of multidisciplinary skills covering engineering and the physical and biological sciences. The paper briefly describes the goals, structure, expertise and research and technology transfer activities of the Centre. The major research program areas of waste rock dump and final void stability, acid mine drainage, tailings disposal, and remediation of ecosystem reconstruction are described in the context of national priorities.

Jan 1, 1995

By D. D. Murphy

The Bureau of Mines has studied the mechanism of shear-flocculation of silica with stearic acid. At pH 6 and 12, shear-flocculation of silica was not observed with up to 10-4M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations 10-4 M (5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labelled with a doxyl group. The presence of the spin-labelling group did not greatly affect the shear-flocculation properties of stearic acid. Adsorption of labelled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicate the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-414 (5 lb/st). The results are discussed in terms of a possible mechanism for shear-flocculation.

Jan 1, 1993

By M. Morales, J. Yianatos

"In this work, an alternative approach to evaluate the flotation performance along a flotation rougher row is presented. The collection zone as well as the froth zone performances were separately evaluated. For this purpose, sampling for metallurgical balances along with sampling of top-of-froth (TOF) grades in each cell of a flotation row were employed. The modelling of the rougher circuit consisted of using TOF grades for evaluating the collection zone recovery, because they are a good representation of the bubble loading, which identifies the true flotation process, as shown in previous studies for shallow froths. In addition, the feed characterization, size-by-liberation, allowed the identification of the mineral distribution and its evolution along the circuit. The latter result was obtained by fitting the recovery profiles as well as the TOF grades down the flotation bank. The flotation rates and the maximum recoveries in terms of size-by-liberation (size classes: -45 µm, +45-150 µm, +150 µm, and liberation classes: -20%, +20%-80%, +80%) were then estimated. The results were in good agreement with those reported in literature by other authors and showed the new approach allows flotation kinetics to be characterized in industrial circuits.INTRODUCTIONMineral recovery in industrial flotation circuits is a function of the mineral characteristics, such as particle size distribution and liberation (Trahar, 1981, Jameson, 2012), and operating conditions such as air flowrate, pulp flowrate, solids percent and reagent conditioning (Jameson 1977; Klimpel, 1980; Mehrotra and Kapur, 1974). The cell type and size (self-aerated or forced air) and the circuit arrangement (single cells or banks of cells in series) are also relevant factors. Sampling of circuits (e.g. rougher, cleaner or scavenger) are commonly carried out using standard automatic samplers for metallurgical balance assessment. However, the flotation plants are generally not provided with proper accesses for local streams, which hinders the recovery estimations and the flotation rate characterization."

Jan 1, 2018

By P. R. Taylor

A review of the advantages and disadvantages of plasma technology for metal and mineral wastes is presented. Examples of the use of plasma systems are given and possible future uses are outlined. Among the potential uses are treatment of electric arc furnace (EAF) dusts, the vitrification of nuclear wastes and the removal of toxic metals. Over the past few decades, plasma technology has been studied for potential applications over a wide range of metals/materials processing areas. One promising area of plasma technology applications is the treatment of industrial hazardous waste. The potential generation of hazardous and toxic waste by various industries has become a matter of public and political awareness. Environmental regulations have put stringent toxicity emission limits on disposable waste streams. An intensive research effort is currently underway in the area of hazardous waste treatment.

Jan 1, 1994

By Shawna Von Stockhausen, Hong Yang, Tung T. Vu, Derek Penrice, Kevin Huynh

"The Regional Connector Transit Corridor is a 1.9 mile long light rail transit project in downtown Los Angeles, California. The project includes approximately 4,930 feet of twin bored tunnels together with a mined crossover cavern, 3 deep stations, and other cut-and-cover structures. The bored tunnels will be excavated using an earth pressure balance tunnel boring machine through Fernando Formation (extremely weak to weak rock) and alluvium. The tunneling will be performed in close proximity to a large number of existing structures, including the existing Metro Red Line tunnels with as little as 6 feet of separation. Thus, the evaluations of the tunneling effect on these structures and the instrumentation and monitoring program is an essential part of the project design. This paper provides a very brief overview of the considerations and evaluations of the tunneling effects on the existing structures and results of evaluation obtained during the final design stage of the project. INTRODUCTION The proposed Regional Connector Transit Corridor (RCTC) project provides a 1.9 mile-long connection between the Metro Gold Line from Pasadena and East Los Angeles; and the Metro Blue Line to Long Beach and the Expo Line to Culver City. The alignment is shown in Figure 1. The Regional Connector will provide new tracks through downtown Los Angeles. The project will extend underground from the Metro Blue, Expo, Red, and Purple Lines’ 7th Street/Metro Center Station following Flower Street, curving northeast to the north of 3rd Street under the 2nd Street Tunnel. The alignment will then continue eastward under 2nd Street, turning northeast to cross under the intersection of 1st and Alameda Streets, then splitting into two branches above the ground surface, one branch extending north along Alameda Street and the other extending east along 1st Street. The project elements include 3 deep stations, a SEM cavern, segments of TBM bored tunnels, and cut-and-cover guideway structures. The bored tunnels have an excavated diameter of 20.3 feet. The subsurface conditions along the tunnel alignment generally consist of artificial fill overlaying finer-grained alluvium (dominantly medium dense to dense sandy soils), underlain by coarser-grained alluvium (a wide variety of medium dense to dense sandy and gravely soils). Below the coarser-grained alluvium is Fernando Formation, which is characterized as extremely weak to very weak sedimentary bedrock. A long stretch of the alignment will be excavated in this formation. The soil layers above the Fernando Formation are of variable thickness and spatial distribution. The geologic profile is shown in Figure 2."

Jan 1, 2016

By J. L. Young

The McLaughlin Mill started operating in January, 1985. For the first eighteen (18) months start-up, initial operation, and circuit debottlenecking have been done. The mill was designed to recover gold from a refractory ore requiring acid autoclaving pretreatment. This paper discusses the problem associated with bringing this complex hydro-metallurgical plant to consistently achieve design tonnages. Also, briefly described are the mill flowsheet, training program, permitting, and process and project development.

Jan 1, 1987

By Stephen C. Tadolini, John Bolton, Bre-Anne Sainsbury, Tom Meikle

"The capacity of ground support components which have been affected by corrosion is reduced and may ultimately lead to dynamic failure of the component and the strata. In order to maintain an effective, long-term ground support system, significant campaigns of rehabilitation are often required in corrosion affected areas which also expose the workers to hazardous conditions. The most common corrosion protection for steel ground support utilises sacrificial systems such as galvanising. Galvanising has previously been proven to be susceptible to some corrosion processes. Stainless steel is the most effective in resistance to corrosion, but can be cost prohibitive, and its mechanical properties often make it unsuited to use in ground support components.Providing an outer protective plastic coating to bolts has proven to be an effective means of protecting the inner steel bar from corrosion. However, these support systems tend to be susceptible to coating damage, and require post cement grouting to provide full encapsulation. In comparison to a standard bolt/resin system, they can be slow to install and expensive. These systems have also been shown to reduce overall load transfer performance of the bolting system.In order provide a higher level of corrosion protection whilst maintaining current installation practices and bolting cycle times, Minova has developed the Enduro™ Steel Ground Support Range. The Enduro™ range consists of standard Minova steel ground support components which have been treated with a unique coating process. The Enduro™ coating has been tested in the harshest of conditions, in laboratory controlled conditions and in underground trials. It has been proven to effectively resist or completely eliminate the formation of corrosion, even in the most aggressive environments. This paper explains the process and provides the details of the laboratory and underground corrosion performance testing carried out on Enduro™ ground support products.INTRODUCTIONTraditionally, the most common form of corrosion protection in steel ground support consists of a sacrificial protective coating such as galvanising (Aziz, et al., 2013). Such coatings have proven to be ineffective in extreme high and low pH conditions with corrosion of the support system commonly encountered. There is also evidence that common forms of galvanising may actually increase the rate of corrosion in certain pH environments. Figure 1 shows typical corrosion and failure of a standard re-bar roof bolt."

Jan 1, 2016

By J. L. Huiatt

Kerosine, fuel oil No. 2, vapor oil, and fuel oil No. 6 were separated into general hydrocarbon fractions by ion exchange chromatography and adsorption chromatography. The collecting properties of these fractions were evaluated by flotation of molybdenum and copper minerals from a natural chalcopyrite ore. Paraffin fractions and aromatic fractions of low polarity produced the best molybdenum recoveries. Selective flotation of molybdenite from copper sulfide minerals was not possible with any of the chromatographic fractions.

Jan 1, 1972

By O. A. Bascur

"In recent years, metal producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Internet of Things (IoT) is one of many transformational initiatives, which can fundamentally revolutionize how industrial complexes operate. Whatever the issue, the answer is in the abundant and growing quantity of real time data and events collected in the grinding and flotation circuits in a mineral processing plant. Based on earlier work, today a grade recovery model permits identifying the best operating conditions in real time. We will review the strategy for increasing the value of the abundance instrumentation in current plants. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut to reduce metal losses in the flotation circuits. The large amount of sensors in a flotation circuits permits to estimate the recovery and to find the optimal froth depth and aeration using an air holdup flotation model. The paper will describe the strategy of classifying data for on line generation of insights to using operational intelligence tools. We will discuss the implementation Recovery/Grind strategy with industrial examples in non-ferrous mineral processing and iron beneficiation.INTRODUCTIONThe declining supplies of high grade ores and increasing consumption of mineral and metal products have demanded higher operational efficiencies with minimum capital investments. The objective of copper flotation objectives are based on maximizing the dollars return on the concentrate produced. The economic efficiency is maximized by manipulating the circuit along the grade/recovery curve relationship. To achieve such objective improved stabilization of the grinding and flotation circuits are required (Oosthuizen, Craig, and Jamsa-Jounela, 2017)."

Jan 1, 2018

By Yoshihiko Maeda

"Although Japanese mining industry once had been a polluter of toxic heavy metals and gasses, it has been struggling for improvement of environment at mining and smelting facilities under the strict Japanese regulations. Through these efforts, the industry has developed various environmental technologies to be applied in other industries and society.Recycling of metal scraps, for example, has been conducted at smelting facilities. Treatment of hazardous waste, cleanup of contaminated soil and management of landfill are other examples of application of mining and smelting technologies and facilities. In accordance with the worldwide environmental concerns, the industry has become one of the leading industries to promote ""Sustainable Development"", and it is expected further contribution in reducing various environmental burdens to earth by utilizing its mining and smelting technologies and facilities. Some of the examples of these applications are presented in this paper.IntroductionDowa Mining Co., Ltd., established in 1984, is known as one of the ~op Japanese producer of nonferrous metals. Base on its special expertise in the mining and smelting of complex ores, it has expanded its business areas to downstream activities ranging from highly purified metals and alloys, electronics materials, chemicals and related various businesses. Dowa Mining now is becoming more active in the field of waste treatment and recycling.Dowa Mining had operated some mines until 1980th, located at the western part and northern part of Honshuu Island in Japan; the former is pyrite mine while the later is ""Black Ore"" mine,· a complex sulfide ore composed of high grade of copper,· silver, lead and zinc. However, due to the strong yen began in1985; Dowa Mining closed its mining operation in 1994, and has sifted to mining operations in Mexico."

Jan 1, 2000

By Edward P. Barrett

Iron ore, when subjected to reducing gases at a temperature suitable for reduction of the oxide but not high enough to melt the ore or metal formed, is converted into metallic iron. The product, being the original piece of iron oxide minus its oxygen, is sponge-like in appearance when viewed under a magnifying glass, and hence is called 'sponge iron. Sponge iron was probably the form in which some of the first iron was recovered from the ores. As early as the eighth century the Catlan forge developed into a low shaft furnace known as the high bloomary, in which iron was produced in the form of a pasty mass. These furnaces were increased in height, and with increased temperatures came the production of liquid cast-iron, at first undesirable because of lack of knowledge of methods for working it. In 1340 the first true blast-furnace was built iri Belgium. Some castings were made, but the greater part of the iron was converted into wroughtiron blooms by a crude puddling process. Charcoal was the universal fuel until the latter part of the seventeenth century, when coke was first used in England. Larger scale developments of methods of refining pig-iron followed. In I 885 Bessemer built his first converter in England, and within a few years the Siemen' s regenerative open-hearth furnace was developed, also in England, to produce steel. Then followed the enormous expansion in the metallurgy of iron. The idea of a direct process for the production of iron and steel has persisted during all of this time.

Jan 1, 1925