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By J. H. Swisher

HIGH-temperature anneals in wet hydrogen are widely used in research as a technique for decarburiz-ing Fe-C alloys. This technique is also used commercially in processing low-carbon steels for magnetic applications. The results of some calculations to be presented show that for temperatures up to 1100°C there is a critical temperature for maximizing the decarburization rate of alloys containing about 0.1 pct C. The low-temperature portion of the iron side of the Fe-C phase diagram1 is reproduced in Fig. 1. Preliminary calculations show that the critical temperature is between 727" and 905°C. In this range, the alloy contains two phases during heat treatment, ferrite and austenite. Decarburization therefore occurs by a process termed "diffusion accompanied by a phase change".' For intermediate stages of decarburization, the carbon concentration profile in a flat plate is shown in Fig. 2. The carbon content increases linearly from zero at the surface to a value, cB , at the two-phase boundary. cB is known from the phase diagram, see Fig. 1. At the interface where x = 5, the carbon content increases to ci, the initial concentration in the alloy. smith3 has derived an equation which describes the rate of movement of the boundary. With a rearrange-

Jan 1, 1969

By Dan Brown

Deep foundation contracting for transportation projects in the United States has typically followed the design-bid-build model in which contractors bid on a specific work product according to relatively inflexible prescriptive specifications. With continuous flight auger piling and the many types of proprietary drilled displacement auger piling, there appear to be advantages to contracting this work according to a different model. This paper provides a discussion of the use of a performance specification for this work in which the contractor has greater freedom to choose the most appropriate foundation system and also greater responsibility for the performance of the completed foundation. With public agencies subject to open bidding, this type of contractual arrangement presents opportunities to encourage innovation. There are also challenges for implementation in public works projects, notably the selection of qualified contractors and the verification of performance requirements on production foundations.

Jan 1, 2006

There are several simulators available and are being used for analysis, improvement and optimal control of the grinding process. However, these tend to be developed on informal software engineering methodologies. The informal approach is not suitable for long term development and a formal design methodology is necessary to develop efficient, error-free, and easy-to-use and to maintain software. In meeting this goal, basic concepts of a software model for describing the mineral process objects has been proposed. The software model forms the basis for software design and efficient implementation of the simulation. This paper describes the development of software models for grinding circuits. The work constitutes the theoretical foundation for the development of an advanced simulator for comminution.

Jan 1, 1995

By George S. Koch

We evaluate the exploration effort by diamond drilling for zinc in central Tennessee and southern Kentucky through a statistical analysis comparing the Middle Tennessee district with the older Tri-State and Upper Mississippi Valley districts. All of the ore deposits are of the Mississippi Valley type and are similar geologically. Through statistical analyses we attempt to answer these questions: Had the drilling density in the Middle Tennessee district been applied to the Tri-State district, how much of the ore in the Tri-State would have been discovered? Had this drilling been done in the Upper Mississippi Valley district, how much of the ore in that district would have been found? Which of these two older districts does Middle Tennessee more closely resemble in intensity of zinc mineralization? Is more drilling warranted in the Middle Tennessee district? Our data base includes tonnage and area distributions of ore deposits in the Tri-State dis¬trict, sizes of ore bodies and probabilities of their recognition in the three districts, and data for the Elmwood mine in the Middle Tennessee district. Our statistical analysis considers the consequences of drilling holes in the three districts on square grids at coarse, intermediate, and fine spacings. We conclude that the drilling pattern assumed for Middle Tennessee would have found some but not all of the ore in the two older districts. We believe that in intensity of mineralization Middle Tennessee more closely resembles the Tri-State than the Upper Mississippi Valley district, and that more drilling is warranted in the Middle Tennessee district.

Jan 1, 1979

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa.*...May, '71.. 1 3 2. Bethlehem, Pa Aug., '71.. 1 10 3. Troy, N. Y Nov., '71, , 1 13 4. Phildelphia, Pa Feb., '72.. 1 17 5. New York, N. Y. May, '72 120 6. Pittsburgh, Pa Oct., 7. Boston, Mass Feb., '73.. 1 28 8. Philadelphia, Pa.* ... May, '73.. 2 3 9. Easton, Pa Oct., '73.. 2 7 10. New York, N. Y Feb., '74.. 2 11 11. St. Louis, Mo.* May, '74.. 3 3 12. Hazleton, Pa Oct., '74.. 3 8 13. New Haven, Conn.... Feb., '75.. 3 15]

Jan 1, 1940

By George D. Coumoulos

The following aspects of diasporic bauxite are discussed: The importance of world reserves of diasporic bauxites; the geological, chemical and mineralogical characteristics of the Greek diasporic bauxite; the uniformity of bauxite deliveries; the significance of the absence of organics; the excellent settling properties of the red mud; the production of sandy alumina from diasporic bauxites; the advantages of applying tube digestion systems in processing diasporic bauxites; the conditions for introducing diasporic bauxite in the existing European refineries.

Jan 1, 1984

By J. Robert Woolsey

The Marine Minerals Technology Center (MMTC) was established by Congress in FY 1988 as part of the Mineral Institutes Program, administered by the U.S. Bureau of Mines under the auspices of the Department of the Interior. The primary objective of the MMTC is to encourage the development of selected mineral materials from U.S. seabeds by providing opportunities for appropriate engineering systems research, development, and technology transfer within academic, government, and industrial communities. The center will also provide the leadership and facilities required for the education and training of the nation's scientists and engineers in the field of ocean mineral development. Because of the broad spectrum of study encompassed by the field of ocean mining and mineral resources, the MMTC is organized to include separate divisions for nearshore and deep ocean research. The Continental Shelf Division is administered by The Mississippi Mineral Resources Institute (MMRI) of the School of Engineering at The university of Mississippi. Operational activities will be based at the John C. Stennis Space Center near Bay St. Louis, Mississippi and the Gulf Coast Research Laboratory, Ocean Springs,

Jan 1, 1988

By E. Pezennec

A voluntary comprehensive environmental Risk Assessment was launched at the end of 2004 by the International Chromium Development Association. The completion is scheduled for mid 2006.EURAS, a leading environmental consultancy, was commissioned for this project, as this firm wrote in particular the Metals Environmental Risk Assessment Guidelines, the reference document for the metals and metals compounds, in particular for the forthcoming European new Chemical Policy and the Globally Harmonized System for the Classification and Labelling of Chemicals (GHS). This project follows a stepwise approach, comprising 3 distinct steps: - Initial Risk Assessment: compilation, evaluation of the existing effects and exposure data for chromium III compounds and chromium metal. This information will be used for the compilation of an initial Risk Assessment Report. - Data gap analysis: which type of additional effects data should be collected and/or which exposure scenarios merit a more detailed targeted risk assessment? Recommendations and/or suggestions for further research will be formulated. - Road map: prioritization and ranking of the different proposed research programs. The presentation will mainly focus on the results and recommendations of the initial environmental Risk Assessment from an International perspective and not from an European point of view. - Hazard assessment ? definition of the Predicted Non effect Concentration (PNEC) for each environmental compartment (water, sediment, soil) - Exposure assessment ? definition of the Predicted Environmental Concentrations (PEC) for each environ-mental compartment - Comparison of the local PEC with PNEC for the chromium III compounds and chromium metal EU industry sectors covered in the project: mining of chromite, metallurgical production of chromium metal, chromium containing alloys production, production of trivalent chromium chemicals and the main applications (pigments, leather tanning, etc..). The current status on the environmental Classification and Ranking for chromium III compounds, Chromium metal and its alloys in the GHS will also be covered.

Jan 1, 2007

By A. Engelbrecht, B. North, B. Oboirien

"There is large electricity generation potential in discard coal, both in stockpiles and current arisings. Power stations with a combined capacity of up to 18 GW electrical (GWe) could be fuelled by discard coal. Modern circulating fluidized bed combustion (CFBC) boilers, with capital costs comparable to equivalent pulverized fuel (PF) boilers, are capable of utilizing discard coal at a high efficiency while reducing sulphur dioxide (SO2) emissions though the use of limestone sorbent for ‘in-situ’ capture.A detailed economic assessment of the feasibility of electricity generation from discard coal, comprising material and energy balances and the construction of a discounted cash flow (DCF) table, shows that it is also potentially attractive from an economic perspective. A base case analysis shows positive net present values (NPVs) and an internal rate of return (IRR) of 21.4%. Sensitivity analyses on critical parameters show that the economic viability is heavily dependent on parameters such as coal cost and the value of electricity. The project becomes unattractive above a coal price of approximately R300 per ton and at an electricity value below approximately 59c per kilowatt-hour (kWh).Site- and project-specific information such as the delivered cost of coal, location and efficacy of sorbents, and effective value of the electricity produced can be used as input to the economic analysis to evaluate siting options and sorbent source options for such a power station."

Jan 1, 2015

By Syd S. Peng

University research in the U.S. consists of three components; faculty, funding, and graduate students or postdoctorals. Individual faculty is the unit area of research that is not limited, although faculty normally performs research in their areas of expertise. Faculty can and often do join with other faculty in multidisciplinary research. Faculty research achievements or reputation reflects the standing of the program and university. Therefore, research is highly encouraged and regarded within the university community. Graduate students are the work force of faculty research and doctoral students are preferred for high-quality products. The federal government provides the majority of funding sources, with the remainder coming from industry, state government and others. Compared with other engineering majors, the mining engineering programs in the U.S. are unique in that they: ? Are small in terms of the number of programs, and number of faculty and students in each program. ? Serve a single industry (i.e., mining) and are thus cyclic, reflecting the up and down economic state of the mineral industries. Enrollment statistics during the past 70 years show that a cycle consists of approximately 30 years with the first 10 years up, followed by 20 years down. ? Have curriculum designed to emphasize and thus serve for either the coal, hardrock or industrial minerals industries. These unique features make mining engineering programs hard to manage in university environments. Funding for mining research has relied primarily on the federal government, i.e., the former U.S. Bureau of Mines (USBM) and currently the National Institute for Occupational Safety and Health (NIOSH). The mining industry does not directly perform, nor sponsor research projects. Federal funding provides primarily in-house research. In the last four decades, federal extramural funding was only available when Congress appropriated extra funding in response to mine disasters. For instance, a string of coal mine explosions in the mid to late 1960s prompted Congress to enact the Coal Mine Health and Safety Act of 1969. It provided massive research funding from 1970 to 1983 covering all mining-related subject areas. From 1984 to 1995, federal extramural research funding was minimal, through two generic mineral technology research centers for selected mining engineering programs. In 1995, Congress closed the USBM and transferred the health and safety of miners program to NIOSH. Federally-funded extra-mural research practically stopped from 1995 to 2006. In 2006 and 2007, in response to a series of disasters, including those at Sago, Aracoma, Darby and Crandall Canyon, Congress again appropriated funding for short-term re-search in selected subjected areas such as underground tracking and communication, mine seal and ventilation, and deep cover pillar extraction. Therefore, to develop a meaningful academic mining research program during the past three decades, funding needed to be drawn from other sources such as the mining industries. A ?meaningful? program requires a sufficient amount of consistent funding in order to produce effective results. A review of federally funded extramural research pro-grams shows that a great majority of contractors/grantees are private entities, involving few mining engineering faculty. This, in part, is due to the fact that mining engineering involves so many different subjects. Therefore, a small mining engineering program can only have resources to cover teaching in the core subject areas (i.e., extraction, ground control, ventilation and material handling), at best. In this respect, a successful and meaningful academic mining re-search effort requires strong supporting programs such as geology/geophysics, structural (applied) mechanics, material sciences, compute/software application, etc. Therefore, academic mining research had to rely on private sources such as coal companies, in the author?s case, for sustained funding in the past three decades. Relying on funding from coal companies presents several problems. The projects were small and considered routine consulting projects requiring practical answers in a very short time frame. This is not really suitable for academic research, for which the major goal of research is the training of graduate students. These short-term projects vary with time and mines, most of which are driven by U.S. Mine Safety and Health Administration (MSHA) or U.S. Office of Surface Mining (OSM) regulations. So sustained funding under such condition requires broad experience of coal mining operations, which is also not well-aligned for academic research where faculty tends to specialize in a narrow field. Consequently, under such a funding environment, it is important to keep in mind how to develop long-term academic research objectives from conducting small short-term consulting projects that require quick solutions. In other words, how to look beyond the quick answers and to develop broader and more fundamental theories applicable to other situations that advance the-state-of-the-art. In order to achieve this objective, faculty must act as the connecting link because graduate students come and go. Faculty must know the detail of each project such that they know what are the important unsolved problems, what to assign to specific graduate students and how to guide the next group of graduate students to continue the development and advance the mining science. Under such funding environments, the most effective way to conduct academic mining research and ensure quality products is to maintain a research group consisting of postdoctoral, PhD, and MS students of various rankings such that the senior ranks can assist in guiding the junior ranks, especially the senior PhD students who are experts in their dissertation research areas. A weekly meeting should be scheduled for the group in which problems encountered in the research are discussed or individuals take turns presenting the progress of their projects. During each meeting, the importance of open discussion on scientific issues must be emphasized. Thus, opinions are encouraged, debated, and rejected or accepted. Students are encouraged to listen to and analyze other points of view. In addition to training of this thought process, the meeting also helps identify the strengths and weakness of each individual. As the subject of research expands over time, the group?s and, thus, the faculty?s research experience broadens. With this approach, companies can get the quick answer they desire from expert research experience and the faculty can engage in meaningful applied and basic research that is most relevant to routine mine operations. The end result is that companies will have a high regard for academic mining research.

Jan 1, 2009

By Robert N. Morris

Ladies and Gentlemen: It is a distinct pleasure and honor to appear before you representing the railway industry as I do, but there is a much closer personal relationship. I am a graduate Mining Engineer and worked in the coal industry for 15 years prior to becoming a railroader only 4 ½ years ago. I have been a member of AIME most of my adult working life and am currently active in the Washington, D. C. Section. While having been in the railway industry only a short time, I have become involved during the recent period of innovation and development of the new railroad technique known as unit train service. I have had the privilege of helping to work out a number of unit train movements to both electric utility companies and to a major steel concern, handling coal from mines on the Southern Railway to the consuming plants. On Southern, our unit trains are all of what I shall describe as shuttle train operations whereas within the railroad industry today several types of service are characterized as unit train service and many don't offer comparable efficiencies.

Jan 1, 1968

By Campbell Osborn

FROM the viewpoint of practical economic engineering the main value in studies of demand and supply lies in the information they give concerning the next movement of price. The title of this discussion is too comprehensive for detailed analysis and it will, therefore, be narrowed to the question of price measurement. The oil operator is interested primarily in net profits. Prices, costs and production determine them. Production is here used in its broadest sense. It includes refining and marketing. It is an operating problem. Prices and costs are economic considerations. Though costs are an important element of prices and profits, the subject is too large to be treated in a brief paper of this sort. In the long run, costs govern prices, but for the purpose of gaging prices in the immediate future the relationship of current demand and supply are more significant. Operating, expansion, retrenchment, sales and storage policies of oil companies are largely influenced by the feeling of executives concerning this relationship. The stockholders of companies whose executives are wrong may suffer. Investors who err in their judgment may likewise lose. On the other hand, oil companies and investors who appraise these factors correctly and move accordingly will profit. It is an important subject worthy of careful consideration.

Jan 1, 1928

By Walshe JL, Solomon M

The Emperor vein system lies on the eastern margin of the Tavua volcanic structure. This is of Miocene age and occurs in basalts(the Mba Volcanics) probably underlain at about 2 km by calcite-rich sediments (the Vatukoro Formation). The lodes are generally flatmakes, or steep fault fillings, or complex shatter zones, and consist of quartz and altered wall rock. In areas of open cavities it is possible to establish a paragenesis which involves five quartz stages and two ore mineral stages. The first ore stage contains calaverite, krennerite, sylvanite and native tellurium, the second petzite, hessite and native gold. The quartz stages are thought to have formed slowly (102 years) from boiling solutions of low salinity at temperatures varying with time from about 250¦C to 190¦C. The system was sealed, the temperature gradient near vertical and the mass flux small. The ore mineral stages probably formed relatively rapidly (101years) from boiling solutions at 250¦ to 200¦C when the system was mainly open. Gold deposition was probably largely a result of fall in aH2S due to boiling, the calculated solution concentration falling from a maximum of about 8 ppb at 250¦C to about 8.10-3ppb at 200¦C. Boiling is also probably responsible for an increase in a02 (by loss of H2) and fall in aTe2 (by loss of H2Te). The fluids are thought to have had a large component of meteoric water and to have been heated by plutons in the core of the volcanic structure. Stable isotope data indicate that they derived their carbon from the underlying Vatukoro Formation and their sulphur from sediments. Circulation may have been confined to the outside of the volcanic structure because of the relatively low permeability of the flows, pyroclastics and dykes within it.

Jan 1, 1987

By D. F. Reed

As a part of a comprehensive survey of the Adirondack region, the Bureau of Mines, 1944 and 1945, conducted investigation of magnetic deposits at Dennemora, Russia Station, Redford-Clayburg, Standish, and the Ausable river region. Later in 1945, the Federal Geological Survey, started an aeromagnetic survey of the area and completed it in .1946. The Bureau of Mines extended its magnetic surveys in 1946 in the Redford-Clayburg area. In 1947 the Bureau of Mines .diamond-drilled throe holes in the Redford-Clayburg district. Clinton County has one active magnetite mine at Lyon Mountain and inactive mines at Palmer Hill and Arnold Hill, as well as along the Saranac River.

Jan 1, 1949

By Chang-Yu Ou, Shao-Chi Chien, Hsuan-Hsiang Chang

"A field test was performed to investigate the applicability of electroosmosis with the injection of saline solution of Taipei silty clay. The calcium chloride solution and sodium silicate solution were used as the saline solution for the injection in this test. The results of this study indicate that injection using calcium chloride solution and sodium silicate solution during the electroosmosis to increase drained water from cathode and electro-chemical reaction can greatly improve the effect of electroosmosis and shorten the time of treatment. The results of field vane tests showed that the undrained shear strength after treatment increased an average of approximately 120% for a treatment period of 24 days.INTRODUCTIONThe first field application of electroosmosis in soil was demonstrated by Casagrande in 1939. Since then, more complete field applications of electroosmosis such as Bjerrum (1967), Fetzer (1967), and Lo et al. (1991b) have been made.The results of field electroosmotic work for a period of 120 days were presented by Bjerrum et al. ( 1967). The mean undrained shear strength, Su, increased from 18 to about 40 kPa, with a uniform surface settlement of about 0.5 m. Lo et al. (1991b), with a more sophisticated installation and a relatively larger spacing, also had positive results. For a 3 m electrode spacing during the treatment of a period of 33 days, the mean Su increased from 18 to about 25 kPa. Although the effect of the electroosmosis could be applied in the field based on the above examples, the response remained slow. For actual field work, the application of electroosmosis will be limited due to short project schedules and request of the effect of improvement."

Jan 1, 2005

By Erin Legault Seguin, Mike Rylatt, Curtis Mohns

"With energy costs increasing and ore grades diminishing, the role of pre-concentration in hard rock mining operations has been gaining greater interest. To maximize energy conservation, the pre-concentration process should be conducted at as coarse a crush size as possible while minimizing losses of pay metals. Dense medium separation (DMS) is a robust process that can be conducted at particle sizes as coarse as 300 mm and as fine as 500 µm with high separation efficiency, depending on liberation characteristics of the value minerals. The DMS process involves three steps: feed preparation, dense medium separation, and ferrous-based media recovery. This paper discusses each of these processing steps, but focus will be given to the dense medium separation stage. Various types of DMS equipment are reviewed. Pilot plant campaign case studies conducted at the SGS Lakefield site are presented, which have included a variety of mineral systems such as spodumene, sulphide-bearing gold ores, and complex sulphide ores. These case studies demonstrate that for amenable ores, mass rejection of 20-60% is possible while maintaining recoveries of greater than 90% in most cases.IntroductionPre-concentration is a process of rejecting mass of gangue while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Pre-concentration has been practiced in industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, typically requiring finer grind sizes and higher energy costs."

Jan 1, 2016

By Nicolae Dobritoiu

From experience and scientific references it is known that during information processing, the following error types are transmitted: technical, analogy errors and method errors. For decreasing the value of these errors, especially of the method ones, old algorithms should be perfected and new ones should be developed for processing, interpreting and achieving the graphical layout by means of automatic data processing. In this respect, we propose a new deposit model based on numeric mathematical modelling which requires the use of automatic data processing. The utilization of the numeric model of the proposed deposit, allows the obtaining of the following advantages: • the model is used for any deposit form; • it is used for the calculation of deposit resources (volume, weight, and content); • it is used in design due to the facility of obtaining sections through the deposits area; • it eliminates at "0" the errors of graphical data transcription; • the use of the model imposes a uniform geological research; • the algorithm is transposed in a package of programs.

Jan 1, 2002

By Michel Aubertin

Les activités minières peuvent produire de grandes quantités de roches stériles, qui sont typiquement entreposées dans des empilements de surface, au dessus la nappe phréatique. Ces haldes peuvent occuper une superficie de plusieurs dizaines d?hectares, et s?élever à plus de cent mètres. Pour des exploitations en roches dures, les roches stériles ont usuellement une granulométrie qui contient des particules de la taille d?un sol silteux jusqu?à des cailloux et blocs de taille métrique. La structure interne d?une halde construite sur une surface relativement plane comprend généralement deux zones principales. La première zone se trouve au coeur de l?empilement, et elle est formée par la présence de plusieurs stratifications subhorizontales (avec des couches denses et lâches) due à l?effet des équipements lourds qui compactent et brisent les grains. La deuxième zone se trouve aux endroits où les stériles ont été déversés en crête, par des camions ou des butoirs, ce qui induit une ségrégation des particules sur les flancs, le long de la pente. Selon la séquence de mise en place, la distribution granulométrique et la hauteur des bancs, un grano-classement plus ou moins développé se produit, avec les particules les plus grosses au bas de la pente et les particules plus fines au sommet ; on observe aussi une stratification inclinée due à l?avancement latéral du front de déposition. Ces éléments de la structure interne d?une halde influencent la distribution et le mouvement de l?eau (et de l?air). Pour évaluer la distribution des propriétés des matériaux dans une halde, on doit usuellement avoir recours à une combinaison de techniques qui fournissent des informations sur les caractéristiques hydrogéologiques et géochimiques des roches stériles. A cet égard, certaines techniques géophysiques sont particulièrement intéressantes car elles permettent une cartographie tridimensionnelle des variations des propriétés. Les informations obtenues de diverses techniques de mesures utilisées conjointement peuvent alors être employées afin de construire un modèle numérique qui permet d?analyser les écoulements non saturés de l?eau et le transport réactif des contaminants. De telles simulations aident à mieux comprendre la réponse de la halde dans son état actuel et futur, ce qui fournit des arguments pour ajuster la séquence de déposition pour élaborer le plan de fermeture et pour sélectionner la stratégie d?instrumentation et de suivi de l?empilement. La présentation inclura un survol des diverses techniques qui ont été développées afin de caractériser les propriétés des matériaux en laboratoire et sur le terrain, et pour obtenir un portrait global de la structure interne d?une halde. Des résultats additionnels sur la modélisation du transport réactif seront aussi montrés afin d?illustrer l?influence de la structure interne d?un empilement sur sa réponse hydro-géochimique et environnementale.

Nov 1, 2008

By Richard D. Grove

The on-stream analysis of phosphorus and silica has not been possible by XRF techniques and only recently has some success been indicated with quantitative XRD for P. Yet there has been a recognized need for an on-stream analysis of P and acid insoluble to permit the automatic control of phosphate rock flotation plants which produce some 30-40 million tons of concentrate each year in the southeastern U.S. IMC Fertilizer, Inc., the largest U.S. phosphate rock producer, embarked on a program to develop such an on-stream analysis capability several years ago. Following many months of lab and prototype development, the first commercial installations started in December 1986 and now have completed some 400,000 analyses with surprising accuracy, precision and reliability. The use of these devices in the improved control of the phosphate flotation plant is currently receiving some very serious attention at IMC.

Jan 1, 1989

By Z. Ren, M. Tomlinson, E. Asselin

"Organic carbon blinding is a common, yet often partial, solution to the reduction of preg-robbing. A quantitative method to assess the extent of adsorption of a given blinding agent is presented herein. The adsorption of several blinding reagents on various carbon samples is quantified using electrochemical impedance spectroscopy (EIS). EIS results showed that kerosene is more strongly adsorbed on carbon than sodium lauryl sulphate (SLS), while SLS can hinder the charge transfer process of the oxygen reduction reaction on the carbon surface more effectively. The effectiveness of SLS is pronounced when its concentration is higher than 100 ppm. Raman spectra are presented for selected carbon samples: as the area ratio of the disordered peak to the graphitic peak increases, blinding agent adsorption increases.INTRODUCTION The presence of naturally occurring constituents in gold ores may adversely affect the extraction of gold in cyanide leaching since the gold cyanide complex, Au(CN)2–, can be adsorbed by these constituents (M. Adams & Fleming, 1989; Afenya, 1991; Miller, Wan, & Díaz, 2005). Such ores are known as “preg-robbing”. Preg-robbing behavior may arise from natural carbonaceous materials in the ore (M. Adams & Burger, 1998). In the past decades, a number of pre-treating methods have been developed for refractory carbonaceous ores (Arriagada & Osseo-Asare, 1984; Beer, 1994; Dunne et al., 2007; Jiang, Liu, Xiao, & Yang, 2012; Kohr, 1997; Kulpa & Brierley, 1993; Menne, 1992; Menne & Revy, 1994; Moyes & Houllis, 2010; Petrie, Craw, & Ryan, 2005; Simmons, 1996). The method known as blinding is one of the most effective and economical pre-treatment methods (M. D. Adams & Burger, 1998; Albert, 1923; Darrow, 1924; McQuiston & Shoemaker, 1975; Van den Berg, 2000). Blinding, also referred to as blanking or passivation, uses a chemical reagent to passivate the preg-robbing carbon by selective absorption or wetting (Bas, Altinkaya, Yazici, & Deveci, 2012; Brierley & Kulpa Jr, 1993; Dunne et al., 2012; Van den Berg, 2000; Yang, Qian, Song, & Dong, 2013; Yen, Amankwah, & Choi, 2008; Zhou, Jiang, & Choi, 2014). Organic reagents, which selectively adsorb on the surfaces of activated carbon and “smother” the surface, have been used for blinding carbonaceous matter in gold ores prior to cyanidation. Two comprehensive studies by Abotsi and Osseo-Asare and Adams and Burger have been published on this topic (Abotsi & Osseo-Asare, 1986; M. D. Adams & Burger, 1998)."

Jan 1, 2017