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By V. Jokovic

Hydrocyclones are the most commonly used classifiers in the mining industry. The reason for this is their low operating cost and a small footprint. Data from plant trials where screens replaced hydrocyclones indicated that lower bypass of fines and sharper separation could improve breakage rates, with a positive effect on flotation circuit performance throughput. Despite the importance of classification, hydrocyclones have not received as much attention as more expensive comminution units, and their technological progress has been incremental. Noticeable water split (Rf) reductions of a semi-inverted hydrocyclone have been reported in the past. According to theory, the hydrocyclone with reduced Rf will improve classification of fines. A classification study using semi-inverted hydrocyclones was conducted to determine if a hydrocyclone could be operated in a way that would minimise misclassified fines. The classification performance of a semi-inverted hydrocyclone will be presented in this paper and other potential applications will be discussed. Keywords: Semi-inverted hydrocyclone, water split, misclassification of fines

Jan 1, 2020

By Michael T. Nigbor

This Bureau of Mines publication identifies the significant environmental issues associated with the potential development of strategic and critical minerals in the Stillwater Complex, MT. The Stillwater Complex contains deposits of Cr, platinum-group metals (PGM), and Ni. Issues that must be addressed prior to minerals development include the effects mining, milling, and smelting will have on the land, water, and air, and methods of minimizing the environmental impacts.

Jan 1, 1985

By Maria do Socorro da Silva

Aços inoxidáveis são aços caracterizados principalmente por sua alta resistência à corrosão em diversos ambientes. Essa característica advém da formação de uma camada de óxido de cromo. A classe de aços inoxidáveis superausteníticos é derivada dos austeníticos pela adição de elementos de liga. A temperatura do ambiente de trabalho pode favorecer a formação de precipitados que podem afetar as propriedades mecânicas e de resistência à corrosão desses aços. Em decorrência da quantidade de Mo, Ni e Cr ocorre precipitação de fases secundárias, sendo mais comuns as fases sigma (s) e qui (c). Para caracterizar a microestrutura e formação da fase s nos superausteníticos, foram realizados os seguintes tratamentos térmicos de solubilização: 1170oC (para formação da maior fração volumétrica da fase s) e 1210oC (para menor fração volumétrica da fase s) por 2h. Foram realizadas caracterizações por meio das técnicas de microscopia óptica e eletrônica, assim como a utilização das técnicas de análise por energia dispersiva de raios-X (EDX) e dispersão de elétrons retroespalhados (EBSD). Os resultados obtidos foram comparados ao estado como recebido do material (bruto de fusão). Verifica-se a presença da fase s em todas as condições, havendo diferença quanto a fração volumétrica em função do tratamento aplicado.

Aug 16, 2017

By W. S. Kirk

World cobalt production in 1987 was estimated to be about 26,600 metric tons (MT) of which Market Economy Country (MEC) production was estimated to be about 22,000 MT. Zaire and Zambia produce about 80 percent of the primary cobalt produced among Market Economy Countries (MEC). Production cutbacks. lowering cobalt grades and mining curtailments in Finland and Zambia in 1987, resulted in lower production than that of 1986. The trend is expected to continue through 1988. Cobalt production from Canadian ores and from Botswana is expected to increase significantly in 1988 as a result of increased nickel production. MEC production in 1988 is estimated to be 22,100 MT, only slightly higher than that of 1987. There are currently no primary cobalt mines. Virtually all cobalt is recovered as a byproduct of copper and/or nickel mining. Zaire, which produces cobalt as a byproduct of copper, is the worlds largest cobalt producer, with over 50 percent of total estimated world cobalt production and nearly 65 percent of MEC production. Zambia follows with about 14 percent and 17 percent, respectively. Zambia's cobalt production also results from copper production.

Jan 1, 1988

By M S. Kizil, T OÆConnor

It is predicted that underground coal mines in the Bowen Basin will have a significant rise in heat problems as mines aim to increase production, depth of extraction and length of longwall panels. At an actual Bowen Basin mine, extended longwall panels greater than 4 km in length are planned to be mined at depths with a virgin rock temperature (VRT) of more than 40¦C. Research has been completed into the reasons for the substantial increase in temperature at the face for underground coal mines in the Bowen Basin. An analysis into heat loads produced at the Bowen Basin mine for the development and production phases shows a significant amount of additional cooling will be required to ensure safe working temperatures. All of the major sources of heat, which included both natural and mine induced heating, were considered for the analysis. Maximum heat loads were assessed, together with peak intake surface temperature to determine the maximum cooling capacity required at a Bowen Basin mine. These maximum heat loads were assessed for a specific longwall panel, Longwall A, which extends to over 4.1 km in length and at a maximum depth of over 330 m, resulting in a VRT above 40¦C. The cooling system positional efficiency was analysed, determining that underground cooling via an indirect heat exchanger was preferred to increasing the capacity of the current bulk air cooling (BAC) on the surface. A preliminary cost analysis was also detailed which compared the cost of additional BAC compared to implementing underground cooling.CITATION:OÆConnor, T, Kizil, M S and Belle, B, 2013. Required cooling system capacities for extended longwall panels at a Bowen Basin mine, in Proceedings The Australian Mine Ventilation Conference , pp 249-256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By Liam Bussey, Graham Speirs

Si bien la automatización de plantas de proceso es quizás la norma actual en la minería, la adopción de esta en la minería subterránea se ha retrasado. En este artículo se compartirán algunas ideas de cómo implementar los sistemas de automatización en la mina subterránea y se explicará cómo la tecnología puede mejorar la operación, de manera que las minas sean más seguras y sus operaciones más competitivas. Se discutirán diversos aspectos tales como los sistemas de comunicación, los sistemas de seguridad, los equipos de producción, los servicios mineros y la gestión de operaciones.

Sep 20, 2019

By Charles S. Allbright, Frank G. Schwartz, Marvin L. Whisman

Radioactive tracer techniques were used to gain a better knowledge of the types of compounds that cause gum formation in gasoline during storage . A selected organic compound was labeled with tritium and purified . An unstable gasoline was tagged by adding a small amount of the labeled compound . After storage of the gasoline at 110 ° F for 16 weeks , the gum that had formed was recovered . The amount of the test compound converted to gum was determined by liquid scintillation counting . About 70 compounds , including several classes and types , were studied . The compounds , listed in order of descending reactivity in the test fuel , were sulfur compounds , nitrogen compounds , polycyclic hydrocarbons , olefins , alkylbenzenes , and saturates . In the order of decreasing percentage of each in the gum , the compounds were monoolefins , alkylbenzenes , sulfur compounds , polycyclic hydrocarbons , nitrogen compounds , and diolefins . This type of information should be helpful in developing a method for predicting the storage stability of gasoline .

Jan 1, 1964

By John D. Spencer

Projects aimed at achieving the least disturbance to the Nation's air, water, and land resources in the mining and utilization of coal continued to be a feature of the Bureau of Mines coal program. This reflects the current concern about damage inflicted on the environment by our growing and increasingly affluent society. Mine Health and Safety research, along with investigations related to all other aspects of coal extraction and use, also continued to be implemented and expanded.

Jan 1, 1970

By AIME AIME

AN IMPORTANT innovation in Alabama in the semi-longwall type of coal mining as applied to low-dipping thin seams has been introduced by the Galloway Coal Co., mining the Mary Lee high-ash seam which averages only 26 in. thick. The property is their Mill Creek mine, near Carbon Hill, Ala., in the Warrior coal field. The results, although not final, indicate that roof conditions can be successfully handled by this method without loss of walls, with a rate of recovery much above that possible with the room-and-pillar method, and at the low production cost necessary for this grade of coal. Double cross-headings are turned off a main haulageway on 60-ft. centers and driven 40 ft. wide with thin chain pillars between. These double entries are turned at 525-ft. intervals, leaving a solid block of coal 440 ft. across; that is, from the outside of one pair of headings to the inside of the next pair is 440 ft. The bottom, which consists of hard fireclay, is taken in these entries 8 ft. wide and 4 ft. deep for head room.

Jan 1, 1934

By K Johnson, G Morrison, N Lisowiec

The Mount Wright gold deposit is located near the town of Ravenswood, ~90 km south of Townsville, in north Queensland. The deposit has been mined by underground methods since 2006. It produced approximately 138 koz Au in the 2011 - 2012 financial year and has a total endowment of approximately 1 Moz Au. To facilitate near mine exploration, a re-logging campaign of 600+ diamond and RC drill holes was recently conducted, resulting in a revised three-dimensional (3D) geological model and improved understanding of the ore controls and the mineralised system. The deposit is within a Permo-Carboniferous breccia complex approximately 350 m diameter and more than 1200 m deep. It consists of early peripheral granite-rich breccia, polymict breccia, a rhyolite spine and a late tuffisite (fine-grained milled breccia) pipe. The rhyolite spine is approximately 60 m + 250 m + at least 1200 m deep and is zoned with massive, flow-banded and breccia phases that are in part gradational with the other breccias. There is extensive sericitic alteration centred on the tuffisite and rhyolite units and fading out into the shallower and peripheral polymict and granite-rich breccias. There is also a broad pattern of metal zoning with elevated Pb-Zn ¦ Ag in the upper 400 m, Au-Cu-Bi below 400 m fading out below ~850 m, and a poorly defined deep Mo-W-Te-Sb anomaly. The majority of the Au ore is between 400 and 850 m below the surface in the rhyolite spine. Below this, Au mineralisation is less coherent, and more localised in the margins of the rhyolite and in the adjacent tuffisite. The developing model is that the ore is not confined to or necessarily directly genetically related to the rhyolite spine, but is driven by other phases of intrusion that also generated the tuffisite pipe. This model is being used to generate additional drill targets away from the present mine development.CITATION:Johnson, K, Morrison, G and Lisowiec, N, 2013. Advancing near-mine exploration with an updated geological model for the Mount Wright gold deposit, Queensland, in Proceedings World Gold 2013 , pp 469-478 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Leandro Augusto Viana Teixeira, Márcio Francisco Dill Junges, Adauto Caldara

Innovation in the mining industry is critical when facing ever growing challenges, like the need to increase safety, reduce social and environmental impact, deal with commodities price fluctuations among others. However, successful innovation is not only the product of technological innovation, but it is also dependent on Innovation Management, which consists of changing the way a company fosters innovation, creating a new structure able to leverage technology knowledge and the ability to convert this knowledge in value. This paper presents a restructure option for innovation that focus on R&D development linked to business needs and company strategy. This new system was approached based on four fundamental blocks for innovation management (Approach, Organization, Resources and Metrics), showing how the technology master plan and a management tool are able to bring together all aspects necessary for the proper operation of the system. The new system confirmed the importance of having the initiatives organized as innovation roadmaps, connecting techno-scientific development with the company needs through the use of KPIs that are relevant to the business.

Oct 3, 2019

By Peter Cali, David Yang, Rakshya Shrestha, Ralph Griffin, Sushil Kafle, Motoji Watanabe

"As a part of the ‘US Army Corps of Engineers - New Orleans to Venice, Louisiana Hurricane Protection Project’, deep mixing ground improvement was designed to reinforce the soft ground for the emergency repair of a 7297-foot (2,224 m) long section of the Mississippi River West Bank levee in Buras Levee District under the contract ‘Emergency Levee Repairs – Contract P-17A, Plaquemines Parish, Louisiana’. The ground improvement utilizes a series of soil-cement panels oriented in the transverse direction of the levee. Each soil-cement panel consists of overlapped columns installed by the deep mixing method (DMM). DMM is performed from the existing top of levee and extended to competent stratum at depths varying from 26 feet (7.9 m) to 47 feet (14.3 m) below the working platform. The main purpose of the DMM panels is to provide shear resistance to the levee against lateral loads at high flood water condition. The DMM panels support the additional vertical load created by the increased height of the levee for hurricane protection and control the long-term settlement of the remediated levee, which might otherwise occur due to the compression of soft foundation soils. The total amount of DMM treatment is approximately 54,000 cubic yards (41,500 cubic meters). This paper reviews the project background, subsurface soil conditions and presents the design, construction and quality control of the deep mixing work for this levee repair project.INTRODUCTIONIn August 2005, Hurricane Katrina caused major damage to the federal and non-federal flood control projects in southeast Louisiana. In September 2005, Hurricane Rita caused further damage to this flood protection system. In an effort to minimize further damage and to enhance the protection level, certain non-federal levees located on the west bank of the Mississippi river in Plaquemines Parish, Louisiana were incorporated into the New Orleans to Venice Hurricane Protection project by the US Army Corps of Engineers (USACE). DMM techniques were then utilized by the USACE in several of these emergency projects and in many medium sized projects between 2006 and 2010 (Bruce et al. 2012). This project (called P-17A hereafter) which forms a part of this protection system is executed under the contract Emergency Levee Repairs, Contract P-17A. This is one of the largest projects of the USACE after LPV- 111. The huge LPV-111 project (5.5 miles (8.9 km) of levee) treated by DMM), the largest DMM project ever conducted outside Japan, began in 2010 and was completed in 2012 (Cali et al. 2012, Bruce et al. 2012).DMM is utilized at P-17A to construct a series of soil-cement panels oriented in the transverse direction of the existing levee to provide shear resistance to the levee against the lateral load during high flood water condition. The project extends 7297-foot (2,224 m) along the West Bank Levee of the Mississippi River in the Buras district of Louisiana, parallel to Louisiana Highway 23 (LA-23) as shown in Figure 1. It is located approximately 60 miles (96 km) south-east of downtown New Orleans."

Jan 1, 2015

By John Beaumont

The Plate-Steckel mill combines the asset utilization of the strip rolling process with the grade and width range of the reversing plate mill, delivering a broad range of steel products at low cost. Among rolling mill types, plate mills are distinctive in the way that they exploit the metallurgical attributes of their product. The downside of this flexibility, though, is a low level of asset utilization. The Plate-Steckel mill was originally developed to combine the utilization of the strip mill and the width of the plate mill. The Plate-Steckel mill is now setting new benchmarks in accessible grades and applications, whilst pushing the width boundaries of the process. Long experience in the Steckel process control and coiler furnace design is coupled with caster and plate mill expertise to deliver high level of performance in this increasingly important plate and coil rolling technique. Several new design features have been incorporated and the vertical integration of mechanics with process models is the key for better product quality and flexibility at these plants. The use of fully automatic thermo-mechanical rolling using the latest physical models and intelligent sequencing strategies achieves the optimum grain refinement and thus improves mechanical properties. The novel profile and flatness strategy relies on comprehensive physical models and makes use of SmartCrown® as a powerful actuator, enabling large reductions to be taken without risking poor flatness. Throughout the rolling and cooling stages of processing, accurate calculation of the thermal-mechanical state of the product is performed by the temperature monitor. This enables tighter control of the final plate mechanical properties by providing an insight into the plate evolution during the thermo-mechanical processing. Advanced pacing functionalities provide an optimized mill throughput, utilizing new cooling bed charging strategies. Considering the rolling process, process automation applies state-of-the-art model calculations to achieve saleable coil/plate target dimensions even in non steady state rolling conditions.

Aug 16, 2017

By R. W. Michelson

The Bureau of Mines developed computerized mathematical models to estimate the economic availability of Mesabi Range taconite concentrates; these are a quality model, a cost model, and an economic availability model. The quality model evaluates metallurgical test data; the cost model determines iron unit cost from mining and processing cost data; and the economic availability model determines quantity from geologic and ore quality data. By correlating all of the physical resource quality factors and dimensional characteristics with the economic cost factors associated with producing iron ore pellets, these three models combine to establish a final relation between iron ore reserve quantities and iron unit cost.

Jan 1, 1970

The twenty-ninth regular meeting of the Rocky Mountain Coal Mining Institute was called to order at 11:30 o'clock a. m., Monday, May 26, 1930, President B. W. Snodgrass presiding: PRESIDENT SNODGRASS (condensed report): The meeting will please come to order. As President of your Institute, I take pleasure in welcoming you to this convention, and to those who come from outside of the city, I take pleasure in Welcoming you to the city of Denver. This is the first convention at Denver in fifteen months. I hope that the annual rather than the semi-annual meetings will prove satisfactory to all, and that no mistake has been made in that respect. We are gathered together here to discuss problems common to all of us, and I am sure that we will profit by such discussion. We have with us, outside of the membership of our organization, representatives of two other organizations, Mr. Callbreath of the American Mining Congress, and Mr. Huntress of the National Coal Association. We will be honored by having them with us, and we shall expect to hear from them during this meeting.

Jan 1, 1930

By Ivette E. Torres

The final 26 tables of this chapter, tables 24-49, extend and expand the statistical series on production that was started in the 1963 edition of the Area Reports: International volume of the Minerals Yearbook and that was subsequently updated and expanded in the 1965 and 1967-90 editions. Mainly because of the separation of the countries that formed the U.S.S.R., the column that provided a 5-year average, was deleted. The listing order of major producers, however, continued to be, as in past years, in descending order of rank in the year of review, 1992. This group of tables now includes each of the top 19 crude minerals in 1983 in terms of value of their output plus 3 others of lesser rank. These 22 crude mineral commodities accounted for more than 98 % of the estimated value of world crude mineral production in 1983. Coal production, included in the 1983 value of production table as two separated entries, is combined in one table in this chapter. World output of five key downstream products-aluminum, steel, cement, nitrogen in ammonia, and refined oil-is included because of their significance as products.

Jan 1, 1994

By C. E. Abbott

THE Birmingham district, Alabama, is distinctive in the proximity to one another of its deposits of iron ore, coal and flux. These three basic requisites for the making of iron and steel are found within a radius of 10 miles. Both dolomite and limestone are produced, the former for blast-furnace flux and the latter for basic open-hearth operations. The Tennessee Coal, Iron and Railroad Co., a subsidiary of the United States Steel Corporation, operates a limestone mine at Muscoda, near Bessemer, 12 miles southwest of Birmingham, served by its own railroad transportation system. The mine has a capacity of 130 tons per hour. Average analyses of a recent month's production are as follows: Fe2O3 Si02 A12O3 CAC03 MGCO Lump, per cent 0.51 0.22 98.63 0.14 Crushed and washed, percent 0.70 0.26 98.36 0.18 Lump stone, 2 1/2 to 7 1/2 in., is used in open-hearth operations at Fairfield Steel Works. Fine crushed and washed stone, 1 ¼ to 0.063 in., is calcined at the, lime-burning plant and used for lime charges at the Ensley open hearths.

Jan 1, 1936

By J Seppelt, G S. Lane, E Wang

Newcrest’s Cadia concentrator operated from 1998 to 2012 with a traditional SABC grinding circuit treating Cadia open pit ore. The Cadia comminution circuit was well characterised through surveys and data that are available in the public domain, and became a benchmark standard for the industry and practitioners modelling large SAG mill based circuits. In 2012, the HPGR-based crushing circuit was introduced in front of the SAG mill to increase throughput when treating the Cadia East ore that was derived from an underground block cave. This ore was expected to be more competent and have a coarser run-of-mine size distribution.Numerous previous papers have described the design and commissioning of the Cadia HPGR-based circuit.This paper describes the improvement in comminution energy consumption resulting from the introduction of the HPGR, including identifying the impact of process complexity and an increase in ancillary energy consumption for conveyors, screening, and crushing.CITATION:Lane, G S, Seppelt, J and Wang, E, 2018. Quantifying the energy efficiency transformation at Cadia due to HPGR crushing, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 141–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Arturo Mauricci

El reencauche de neumáticos es un proceso que consiste en adicionar, previa evaluación y reparación, una capa de caucho al casco original, de manera que se pueda reutilizar y evitar consumir uno nuevo. Si bien este proceso no es una práctica común, pues se tiene la creencia de que no es rentable, en Minera Las Bambas se viene implementando con éxito. En el 2017, para una flota de 44 camiones Komatsu 930, se desecharon 542 neumáticos en la medida 53/80 R 63, mientras que en el 2018, al reencauchar 130 neumáticos, se desecharon 187 neumáticos menos, equivalentes a 654.5 toneladas anuales. Esto, replicado por los 30 años de estimado de vida de la mina, resulta en 19 635 toneladas menos de desechos contaminantes, con lo que se logra una reducción considerable del impacto en el medio ambiente.

Sep 20, 2019

By A. M. Anthony, A. Y. Atta, S. S. Magaji, U. Abubakar-Zaria

There are two major gold recovery methods: the hydrometallurgical technique, which employs cyanide solutions, and amalgamation method, which involves mercury (Hg). These methods present considerable health, safety, and environmental concerns. Past applications of alpha-cyclodextrin (α-CD) on gold scraps show that α-CD is not only inexpensive, but is also environmentally friendly. This research work used α-CD to recover gold from gold ores instead of gold scraps. The gold ore was sourced from Shanono gold deposit site Kano State,Nigeria. The gold ore was characterized by fire assay (FA) for the precious metal. The concentrate was digested with aqua regia (AR) for 24 h. Modified AR, where hydrochloric acid was replaced with hydrobromic acid, was used for the gold digestion due to the good match in molecular recognition between gold bromide ion (AuBr)− and α- CD in a second sphere coordination complex. The digestate was characterized using atomic absorption spectroscopy (AAS). Gold recovery using this technique is pH sensitive, and five pH values (2.0, 3.6, 4.0, 5.4, and 6.0) were investigated. FA analysis showed the Shanono gold ore deposit contains an average of 4.71 ppm of gold, AAS analysis showed highest gold recovery of 69% at pH 4.0, which is lower than recoveries from the metal scraps. This could be due to the presence of other gangue minerals closely associated with the ore. However, gold recovery using α-CD on Shanono gold ore has shown to have a higher yield of 69% compared to 35.5% yield obtainable by Artisan Small Scale Miners using mercury.

May 5, 2020