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By Ross W. Smith

Microflotation and surface chemical studies were conducted on a chromite from the Stillwater Complex in Montana and on some of the minerals usually found to be associated with such chromites. Considering the chromite it was found that aging the ground mineral in air or heating it markedly affected its flotation behavior. Much of the observed effects could be attributed to oxidation reactions involving surface chromium and iron species. Strongly acid pretreating the mineral appeared to reverse such effects. Thus, it can be concluded that the manner in which the mineral (or the ore) is pretreated is of utmost importance in its flotation. Work carried out on associated gangue minerals determined how they are likely to behave in a flotation environment and how certain foreign ions derived from a chromite ore itself can affect their surface characteristics and, thus, presumably also their behavior in a flotation circuit.

Jan 1, 1981

By K. J. Stanaway

Major world ilmenite and rutile accumulations reveal similar regional geology and Proterozoic age deeper crustal source rocks. During crustal collision titanium crystallizes as ilmenite and rutile at buried sites of high pressure and temperature rock metamorphism. Hydrothermal activity can convert titanium minerals to rutile, but titanium migration and enrichment seem only local. Many melts crystallize rocks with iron-titanium oxides in solid solution, but titanium enrichment at economic scale takes place in basic intrusive melts often associated with anorthosites and charnokite. Sedimentary placer enrichments have formed since the Proterozoic with water-resistant ilmenite, and rutile segregating by gravity from quartz sands deposited from flowing water. Placers have residual, alluvial, strand and shallow marine variants. Time, organic acids, and sand permeability play lead roles in the leaching of iron from ilmenite during weathering and diagenesis.

Jan 1, 2005

By Raymond Rivera, Federico Cernuschi

Este documento trata de actualizar el conocimiento de un tipo de venillas no tan conocidas que llevan el nombre early halos. El reconocimiento de este tipo de venillas puede servir mucho para la vectorización lateral y vertical de un sistema porfirítico, pero debido a la escasa información que existe sobre ellas muchas veces son subestimadas, desapercibidas o hasta incluso confundidas con otros tipos de venillas. Este tipo de venillas son más comunes en los pórfidos Cu – Mo, mientras que en los pórfidos con afinidad hacia el Au (Cu – Au / Au – Cu) suelen ser más escasas o no estar presentes, pero aun así su débil presencia puede servir como una herramienta de vectorización.

Sep 30, 2022

Study on Basic Theory of the Grain Settlement in Fluidised Bed This paper takes thick goal grains (less than 1.5 cm) as research object. According to different densities and particle sizes, thick goal grains are divided into 20 kinds of narrow density and narrow size level average grains. Free settling and hindered settling tests are respectively carried out in ?100 fluidised bed thick goal separators. Hindered settlement includes hindered settling velocity test and measurements of suspension density. Results show follows. (1) Fluid state in separator belongs to transition region. Alien's law is the appropriate formula of thick coal particles free settlement terminal velocity. (2) The main factors affecting hindered settling velocity are the number of solid particles in medium and the structure feature of the particle group. The bigger volume fractions of solids ? is, the smaller decreasing velocity coefficient of particle hindered settlement ¯ becomes. In the organism from bottom to top, density of suspended particles in fluidised bed gradually decreases, but near the top of the suspended particles, the density increased slightly. With increase of density and size, suspension density reducing extent increases from bottom to top of separators.

Sep 13, 2010

By R Hall

Subduction zone magmatism is a direct response to tectonic and chemical processes operating at convergent margins. Changes in the tectonic configuration of plate boundaries in SE Asia during the Cenozoic had consequences for the nature and volume of magma produced. Retreat or advance of the trench hinge has probably been an important process in controlling the presence or absence of magmatism in SE Asian subduction zones. This process also provides a means of replenishing the mantle wedge and counteracting the effects of melt extraction in depleting the wedge. Changes in the nature of recycled material and lithologies of the over-riding plate also have the potential to influence the lavas that are erupted in arcs. Several locations in SE Asia have experienced magmatism bearing the geochemical signature of subduction but are remote from coeval subduction zones. Such magmatism requires an earlier period of mantle enrichment by subduction but may result from localised extension. The distribution of such magmatism may provide information of tectonic value. Some adakitic magmatism occurred in tectonic settings where there is no evidence for subduction of young oceanic crust at the time of magma genesis. Slab melting in such settings is not possible and alternative mechanisms are required to explain the occurrence of, at least some, adakitic lavas.

Jan 1, 1999

By Jay L. Hodkinson

Replacement of an aging twin span river crossing in Vermont required a temporary bridge to accommodate traffic during construction. Soils beneath the temporary approach embankment consisted of very soft organic clayey silt underlain by interbedded, loose alluvial fine sand and silt/clayey silt. Reinforcement was required for the southern temporary approach embankment to limit settlement and to increase global stability factors of safety. A ground improvement design was developed using Rammed Aggregate Pier® reinforcement and was included in the contract documents as an FHWA Category II Experimental Feature. Instrumentation intended to document the performance of the supported embankment was installed. Piers were then constructed and monitoring commenced as embankment and bridge construction occurred. Weekly instrumentation data reports indicated continuing excess pore water pressure, settlement, and lateral deformation of the subgrade soils as the embankment and temporary bridge abutment was constructed. In response to the unanticipated monitoring results, further investigation indicated that significant deviations from the conditions and basis upon which the ground support design was developed were made during construction. This paper discusses these deviations and their specific impacts to embankment support performance, how these deviations occurred, the role that the ground support system played in maintaining global stability, measures taken to limit further detrimental impacts to the embankment, and provides recommendations for contract document preparation and construction oversight to prevent similar situations from occurring on future projects.

Jan 1, 2011

By A. K. Bhattacharya

Cylindrical bridge piers are widely used and equations exist that can predict the maximum depth of local scour around such piers. Scour around piers is an undesirable phenomenon, as it requires the foundation to be placed to a greater depth resulting in increased cost, making it worthwhile to investigate scour-reducing measures. A number of scour-reducing measures have been tried out for cylindrical bridge piers including placing a concrete collar around the pier, having a delta-wing projecting upstream in front of the pier, placing riprap around the pier, using a group of piers instead of a single pier, having a slot in the pier aligned in the longitudinal direction. The objective of this study is to investigate the effect of upstream protective piles on reduction of maximum local scour depth around a cylindrical bridge pier. The upstream piles are placed at different radial distances in front of the pier and the scour depths are observed. The proposed equation of Dey (1997) for determining the maximum depth of scour around a cylindrical bridge pier is used. The reduction of local scour around the pier is compared with local scour around an unprotected pier.

Jan 1, 2009

By G. W. Bonnell, D. A. Young, D. G. Genter

Through 1996 and 1997, CANMET and the Cape Breton Development Corporation (CBDC) conducted a project to study the Phalen Mine’s 7 East longwall ventilation network to help determine methane emission patterns that were having a negative impact on coal production. Increased methane emissions were primarily related to mining depth and were also affected by the influence of a large sandstone body located above the worked seam. The research included the installation of tube bundle systems to monitor waste (gob) methane and pressure differentials. The focus of this paper is on the novel use of tracer gas techniques that helped shed light on the performance of the ventilation system and in determining the methane migration paths in the waste.

Jan 1, 2001

By Mirian Mamani

Como resultado de la exploración por litio, hoy se conocen ocurrencias importantes (de hasta 3,000 ppm de litio) en la tobas de composición riolítica en la región de Puno, Perú. Para conocer el estado actual de las principales concentraciones de litio en rocas félsicas (granitos y riolitas), se ha compilado información geoquímica (>10,000 muestras) de varias fuentes en el territorio peruano. La distribución espacial y temporal de las concentraciones de litio muestra que los valores mayores a 300 ppm se encuentran en las rocas félsicas, riolitas del Oligoceno-Mioceno y monzogranitos del Triásico del trasarco, y también en los diques de sienitas nefelínicas (30-100 ppm); todas las cuales se ubican en la margen oeste de la franja de Sn, W, Mo. Los valores más altos (mayores a 600 ppm) corresponden a la región de Puno. Sin embargo, niveles de tobas retrabajadas del altiplano que fueron emitidos por las calderas volcánicas del trasarco y sedimentos que desembocan en el lago Titicaca muestran concentraciones de 100 a 400 ppm de litio. Además, las fuentes termales de Tacna y Moquegua contienen entre 10 y 50 ppm de litio, lo que indica que por debajo de los volcanes recientes existen sedimentos con litio. Finalmente, debe indicarse que el mayor potencial de litio (3,000 ppm) está relacionado con los minerales denominados como macusanitas.

Nov 30, 2018

By André Vien, Pedro Gonzalez, Julio Palomino, Rob Perry

"In many mineral processing plants ore is reclaimed from a stockpile using multiple feeders. The discharge from these feeders is combined onto a single conveyor from which total tonnage is measured. Typically, operators set feeder output ratios to adjust the proportion of total tonnage drawn from each feeder. From a process control perspective, this system is not easy to control because the response time of each feeder depends on the distance from the feeder to the weightometer. This paper proposes a simple and elegant process control strategy to manage feeder ratio changes and the associated long and varying process dead-times. Changes in feeder speed are delayed and filtered to compensate for transport delays between feeders. The strategy was evaluated by simulation and installed on a mill feed system.ResumenEn numerosas plantas procesadoras de minerales, el mineral es extraido desde una pila de almacenamiento usando varios alimentadores. La descarga de estos alimentadores es recibida por zinica correa transportadora, en la cual se mide el tonelaje total. Comzinmente, los operadores colocan un valor determinado en cada controlador de razdn para ajustar la proporcidn del tonelaje total extraido por los alimentadores. Desde el punto de vista del control automatic0 de procesos, este sistema es dijkil de manejar debido a que el tiempo de respuesta de cada alimentador depende de la distancia de este respecto a la ubicacidn del pesdmetro. Este trabajo, propone una estrategia de control, simple y elegante, para compensar los cambios de razdn a cada alimentador y los tiempos muertos del proceso largos y variables. Los cambios en la velocidad de los alimentadores son retardadas y filtradas para compensar los retardos del transporte entre alimentadores. La estrategia fue evaluada por simulacidn, instalada y probada en un sistema de alimentacidn a molino."

Jan 1, 2000

By David B. George

Kennecott Utah Copper adopted Outokumpu Flash Smelting and Kennecott-Outokumpu Flash Converting in 1995, a process based on granulating high grade copper matte. While nickel mattes and very small quantities of copper matte had been commercially granulated for years, no large scale copper matte granulation system had been built. This paper summarizes the history and benefits of copper matte granulation, the Kennecott design basis, the successful operation for over 10 years and potential problems inherent in some matte granulation approaches.

Jan 1, 2006

A pilot steel ladle injection facility designed to assist in the production of high quality steels suitable for use in pipelines has been built and commissioned at the Basic Oxygen Steelmaking (BOS) plant at Port Kembla Works.The plant design and the injection procedure are described.The performance of the unit and some metallurgical results are discussed in terms of the addition to the steel ladle of various quantities of calcium silicide and a lime based material. The effects of these additions on sulphur content and inclusion morphology and hence on steel ductility are also presented. The influence of ladle lining on desulphurisation is illustrated.On the basis of the experience gathered in the pilot plant a permanent and more sophisticated injection facility has been designed.

Jan 1, 1983

By Walter D. Holland

This is one of a series of instruction guides developed to help instructors present health and safety training courses to workers in the metal and nonmetal mining industry. This course is intended for training those, usually the safety officers, who perform surveys for inhalation contaminants in above ground work areas. The handbook entitled ?Handbook for Surveys of Inhalation Contaminants in Above Ground Metal and Nonmetal Mining and Processing Work Areas? is used as a manual for the course and as a prime reference when performing the actual surveys or interpreting the sampling results. There are six experiments for the students to perform during the course to familiarize them with the sampling devices routinely used during the surveys.

Jan 1, 2011

By Victor R. Spironello

The Bureau of Mines has conducted studies of the slags related to ferrous technology to evaluate experimentally acceptable substitutes for the auxiliary flux, mineral fluorspar, in steelmaking operations. Comparative heats were made in a 1/4-ton, pilot-scale, basic oxygen furnace (BOF) to evaluate a waste material known as "used potlining." Used pot lining is recovered from alumina reduction cells after its useful life and contains significant levels of fluorine and sodium in various compounds. This material in both lump and pelletized form provided adequately fluid slags, based on observations made during BOF operation. No adverse effects were found on furnace performance, metal and slag chemsitry, the strength of the steel produced, or the environment. Fluorine recovery in the slag was about the same as that obtained when using fluorspar, as were the losses to the scrubber water and solids. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag. The sodium recovered in the slag apparently also contributed to fluidity, since the fluorine input was at about two-thirds that of the fluorspar. Used potlining was determined experimentally to be a satisfactory substitute for fluorspar in basic oxygen steelmaking.

Jan 1, 1982

By H. W. Gillett, E. L. Mack

Prior to 1911 the literature on melting brass by electricity consisted entirely-save for some suggestions made in patent literature but not actually worked out-of a few observations by farseeing men ' on the theoretical advantages of melting brass and other nonferrous alloys in electric furnaces. Roeber was the first to see and clearly state the possible advantages of the electric furnace in brass melting. The same factors tha.t make it desirable to manufacture special steels in the electric furnace rather than in crucibles, he declared, apply to brass as well. He pointed out the possibility of using larger melting units, of eliminating crucible cost, of readily controlling the purity of the product. and of nearly eliminating the loss of zinc. "The replacement of the • old crucible process is sure to come," he said; "perhaps it will come in two years, but it will, necessarily, in ten years .... The inevitable advance along this industrial line will have great influence in the metal world and will also provide, in large cities, a new kind of load for the central station." The years 1905 to 1910 may be termed the purely theoretical period of the development of the electric brass furnace, though the Conley furnace was tried out e:xperimenta.lly about 1910 and a few heats were made in an induction furnace. 2 In December, 1911, the American Chemical Society held a symposium on mineral wastes, at which Bassett s discussed the zinc· losses that attend making brass in fuel-fired furnaces.

Jan 1, 1922

By P. L. Ngwenyama, W. W. deGraaf

South Africa is one of the leading producers and exporters of coal globally. A significant amount of the country’s production is obtained from previously mined underground bord and pillar workings. This coal is in the form of pillars and remnants on the roof and floor of the old workings. The good quality coal pillars were left behind as primary support during underground bord and pillar mining operations. Due to the depletion of virgin coal reserves, the pillars and remnant coal are now removed using opencast mining rather than underground methods. However, the secondary extraction of pillars and remnant coal from the old workings using opencast methods entails some serious challenges that have a negative impact on the safety and productivity of the operations, affecting both personnel and machinery. If these risk factors and challenges are managed properly, then the opencast mining operations could remove the pillars safely at recoveries competitive with those of virgin coal operations. In this study we review the recurring challenges affecting opencast pillar mining by means of field investigations and consultations with experts at five opencast pillar mining operations, and evaluate the best practices used to combat these challenges. It was found that each mine has its own unique conditions and challenges.

Dec 1, 2021

By Z. A. Md-Nor

Risk management is an established loss-control methodology that has been applied successfully in many industries. Recently, interest in this structured approach has grown in the mining industry. The main objective of this research was to develop a risk-assessment process, which is a part of risk management, that can be used by the U.S. mining industry to more thoroughly characterize risks associated with haul truck-related fatalities. The assessment is based on historical data obtained from the U.S. Mine Safety and Health Administration (MSHA) investigation reports, which includes 113 fatal incidents that occurred from 1995 through 2006. The risk-assessment process used in this research involves the following basic steps: identification of the risks, risk analysis and risk evaluation. The preliminary hazard assessment (PHA) method is used in identifying and quantifying risks. Risk levels are then developed using a pre-established risk matrix that ranks them according to probability and severity. The resulting assigned risk value can then be used to prioritize control strategies. This paper is a part of a detailed study on risk assessment for equipment-related fatalities in mining sponsored by the Western U.S. Mining Safety and Health Training and Translation Center.

Jan 1, 2008

By H. Pempel, J. Markowski, P. Ay

"Metal-coated thermoplastic parts find more and more functional and aesthetic applications in the interior and exterior of cars. The vapor-deposited or electroplated coatings are usually composed of a plurality of nickel- and chromium-containing layers, which are applied to copper-containing carrier layers on the polymers. Previously, recycling processes are mainly focussed at the recovery or thermal utilization of the plastics. Targeted and selective recycling of the metallic coatings is usually not carried out. Together with several SME, BTU developed a process, in which a complete and separate recovery of all components in high purity is possible with biotechnological methods. The bioleaching is carried out with iron and sulfur-oxidizing bacteria, especially Acidithiobacillus ferrooxidans. The copper-containing layers are dissolved in the solution; chromium- and nickel-containing particles are precipitated as solids. After the bioleaching, a mechanical separation of the individual metal-containing components and their separate workup are carried out. End-products are metallic copper, a nickel- and chromium-containing solid and the cleaned plastics. The bioleaching ensures a high purity of the end products. Through the use of bacteria, which are also found in nature, the process is environmentally friendly. Compared to chemical leaching using inorganic acids, considerably shorter leaching times can be achieved. In addition to the optimization of the leaching process, the R/D-project also includes the development and testing of the apparatus technology.INTRODUCTION The material complexity of many end-user products has increased in recent years, especially in the fields of electrical appliances, vehicle technology and medical technology. However, the demands on functionality, safety, comfort and energy efficiency still play a greater role in product design as factors such as sustainability and usability. For example, if a car still holds more than 70% of steel in the 1980s, a vehicle nowadays includes a larger proportion of a variety of difficultly separable plastics and composite materials, as well as complex metal composites. This relates in particular to composites made from such different materials as metals and plastics. The processing and recovery of the components of those complex material mixtures is difficult for recycling companies."

Jan 1, 2017

By Gregory M. Molinda

The Coal Mine Roof Rating (CMRR) was developed 10 years ago to fill the gap between geologic characterization and engineering design. It combines many years of geologic studies in underground coal mines with world-wide experience with rock mass classification systems. Like other classification systems, the CMRR begins with the premise that the structural competence of mine roof rock is determined mainly by the discontinuities that weaken the rock fabric. However, the CMRR is specifically designed for bedded coal measure rock. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, extended-cut evaluation, and others. It has also become truly inter-national, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. This paper discusses the sources used in developing the CMRR, describes the CMRR data collection and calculation procedures, and briefly presents a number of practical mining applications in which the CMRR has played a prominent role.

Jan 5, 2007

By David Vergara Segura

Una empresa minera, en condiciones normales, maximiza su operación y minimiza sus pérdidas por tener operativos y equipos ligados a la producción. Por lo que es necesario la integración entre las áreas de la empresa, específicamente entre las de Mantenimiento y Logística. En este sentido, el presente texto señala la importancia del trabajo en equipo entre estas dos áreas, cuyo objetivo común es optimizar la gestión del activo que tiene un impacto significativo y directo en la producción. También se plantea bajo del esquema de una empresa minera ficticia, el desarrollo de estrategias conjuntas, y se define un modelo de gestión logístico, generador de ventaja competitiva, el cual está orientado a la optimización del uso del activo.

Sep 12, 2005