Search Documents

By C. I. Basilio

The mechanisms involved in the adsorption of modified thiol-type collectors on sulfide minerals have been investigated in the present work. These collectors belong to the broad classes of thionocarbamates, thioureas, thiophosphates and thiophosphinates. They differ significantly from the traditionally used thiol-type collectors, such as xanthates and dithiophosphates, in terms of structural features that involve either the introduction of an additional oxygen donor or the alteration of electron densities on donor atoms. Electrochemical studies suggest that the adsorption of these classes of collectors is probably the result of a coupled reaction of the EC-type, involving an initial electron transfer step (E), followed immediately by a chemical reaction (C). Thus, the overall adsorption process is controlled by both the E, and pK of the system. The role of structural features in changing the interaction of the donor atoms with sulfide minerals is also discussed.

Jan 1, 1991

By S. Amira

In the last two decades, many new creep-resistant magnesium alloys have been developed for high temperatures applications. Their mechanical performance and corrosion behaviour were reported for various experimental conditions. However, these conditions often led to uneven comparison basis. In the present study the microstructure, mechanical properties and corrosion performance of four of these newly developed creep-resistant magnesium alloys were systematically compared. Specimens were obtained from experimental box-like components that were die-cast and thixocast in comparable conditions. Their mechanical and corrosion properties were compared using similar testing conditions. Results show that the creep resistance, strength and impact resistance of specimens are comparable but systematically lower compared to specimens cast under optimized conditions. The reduced concentration of elements such as Al, Ca, Sr and Ce lead to a decrease of the corrosion resistance of the magnesium alloys in 3.5% NaCI solution.

Jan 1, 2007

By P. H. Francis

In This report, factors which currently enter into the design, manufacture, and quality assurance of explosion-proof enclosures are reviewed, with special emphasis given to the sealing concepts and sealants/cements, per se, for lenses. The physical and mechanical properties of a number of representative sealants and adhesives are measured, and found to exhibit great variance, with few discernible trends which might afford a firm base on which to establish minimum property standards. Accordingly, acceptance criteria for adhesives and sealants are suggested based on the survivability of an explosion-proof enclosure as a structure rather than upon the minimum mat real properties of its constituents. Procedures or surface preparation of adherends, and for quality assurance, also are proposed.

Jan 1, 1980

By O. C. Ralston

Natural or artificial manganese dioxide of a grade pure enough to be satisfactory as depolarizer for dry cells has never been available in large supply simultaneously with being available in desired quality . The Second World War called for more of it than ever . A supply of natural material from the Gold Coast was ample for the war and was not completely exhausted . Whereas the crystal form of the manganese oxide was not recognized as a matter of importance until the war came , it is now known that gamma MnO2 is a desirable form and that pyrolusite , once thought acceptable , is not the best mineral . The following paper is a translation of an internal company report filed at the Bitterfeld office of the I. G. Farbenindustrie A.G. by Dr. Peter Marx in 1933 , just a year after G. W. Nichols had published in the Transactions of the American Electrochemical Society a study of making anodic manganese dioxide from solutions of manganous sulfate . The I. G. experiments were made to confirm the American work and were also extended to a larger scale . Only chemical purity was considered , and no mention is made of crystal form . The report adds to the knowledge submitted by Nichols but has not been previously available to the general public . Believing it of value to the United States industry , a translation has been made .

May 1, 1948

By E. A. Zawadzki

The problem of pollution of water by mine drainage is at least as old as the mining industry itself. However, research on the formation, composition, treatment, and abatement of mine water is a relatively recent historical event. At Bituminous Coal Research, Inc., acid mine drainage control has been an important area of work since 1944, at which time BCR began sponsorship of research at West Virginia University. The work at West Virginia University involved a detailed study of the acid mine drainage problem and led to the identification of iron oxidizing bacteria as important factors in the formation of acid mine water. The results of this research were summarized in 1954 by Temple and Koehler (1) who concluded that "no practical solution for the problem" of controlling acid mine drainage is yet known.?

Jan 1, 1967

By C. M. Iheagwara

An overview of the scope and ramifications of scrap recycling in the Nigerian metallurgical industries has been presented in this paper. The modern state-of-the-art processing techniques and the operational strategies employed in the recycling plants are discussed. Optimization techniques for cost effective recycling operations are highlighted. As new units within existing metallurgical plants and new metal working plants approach commercial operations, expansion of existing recycling plants and the emergence of new ones have been showing to hold the key to their profitability from the raw material standpoint. The present economic predicament of the entire industrial sub-sector, lack of sufficient foreign exchange to procure new machineries and the emergence of a maintenance culture have triggered a phenomenal increase in the number of spin-off industries which depend on metal recycling activities. This, it is argued, widens the horizon for scrap processing/recycling.

Jan 1, 1992

By M. A. Evanto

Since the late 1970's, the Roof Control Division (RCD) of MSHA's Technical Support has been performing linear analyses for the enhancement of miners' safety. This remote sensing process uses Landsat data to predict areas of potentially hazardous ground conditions in underground mines. To date approximately 700 analyses have been completed by the RCD, with nearly 75 being performed with the current equipment, software and methodology which was updated in early 1995. While success is difficult to measure, requests for linear analyses continue to come from large and small mining companies which suggests the industry's acceptance of the process.

Jan 1, 1998

By John W. Sweeney

Florida is usually thought of as a vacation State, not a mining State, yet Florida has been the leading producer of phosphate rock in the United States for 85 consecutive years and in 1978 supplied over 80 percent of the national output and over 30 percent of the world's output. It is estimated that the Central and South Florida phosphates contain 412,800 short tons (374,000 metric tons) of U308, that 115,000 short tons (104,000 metric tons) of U308 will be contained in the wet-process phosphoric" acid procsssed in the United States through the year 2000, and that 54,000 short tons (49,000 metric tons) of U308 will be available from Florida. In 1978, two companies in Florida and one in Louisiana went on-stream recovering uranium oxide from wet-process phosphoric acid and three others started construction of U308 extraction facilities. These six companies will have the capacity to recover 2,137 short tons (1,900 metric tons) of U308 annually in 1980, which will account for about 15 percent of our domestic requirements.

Jan 1, 1979

By T. R. A. Davey, J. W. Sherman, B. J. DiSanto, G. Bjorling, G. S. Stacey, J. T. Cullom, R. L. Bird, S. E. Woods, J. C. Blair, Jorma Honkasalo

Most pyrometallurgical processes take place at high temperature with rapid chemical reactions when the elements and compounds are usually liquid or gaseous. Smelting. The classical method of obtaining a metal from its ore or concentrate is to smelt it in a furnace. The initial letter "s" of this word implies that, in addition to the physical process of melting, a chemical change also occurs. This is usually the reduction of metal oxide to metal by carbon or through a series of processes involving oxidation and reduction. Since solid-solid contact would not be sufficient to give a high rate of reaction, most smelting reactions occur by medium of two reactions involving solid-gaseous contact: where M represents a metal. The commonly preferred unit for carrying out these reactions is the blast furnace,1 which is a vertical shaft of refractory brick or water-cooled steel in which lumps of metal oxide and coke are fed at the top, and an air-blast is injected through tuyeres (water-cooled pipes) in the bottom. Molten metal is withdrawn from a pool at the bottom of the furnace, while N2, CO, and CO2 gases leave the top of the furnace, carrying some fine dust or fume with them, which

Jan 1, 1985

Throughout the study phases (scoping, prefeasibility and feasibility) of new mining projects one is forced to work with and make predictions based upon limited date obtained from diamond and reverse circulation drill holes. These data are extrapolated to determine how much of the valuable metal is present in the ground, how it can be recovered it and the efficiency of this recovery. Mining methods to extract the ore are investigated with forecasts made regarding excavation stoping stability and performance in an attempt to optimise production. Extraction and use of rock mass data for use in characterising the mechanical behaviour of the rock mass is no exception. One often relies heavily upon the use of empirical charts developed over many years on hundreds of case histories based upon rock mass characterisation schemes. This is largely successful and indicative of what one might expect. However specific site characteristics can always play a significant role, and are not necessarily apparent in diamond drill core. Feasibility studies for the Favona orebodies indicated that the rock mass was generally poor to extremely poor, and that stoping conditions would be difficult in all of the orebodies for various reasons. A range stope performances were achieved ranging from very good to very poor and in some cases unexpected results were achieved. A comparison is made between what was actually achieved and what was expected since stoping commenced in 2007. Explanations are attempted for differences in stoping performance and, in some cases, unexpected results at the Favona underground mine are attempted.

Nov 25, 2010

By J T. Woodcock

This paper discusses characterisation techniques that can be applied to complex waste products from metal production and processing operations with the aim of devising treatment methods for upgrading the metal content for recycling. Two waste streams were selected to illustrate the role of characterisation in adapting mineral processing techniques to provide an effective recycling strategy. Waste products chosen were:aluminium dross, which contains metallic aluminium particles in a coarse matrix of many components; and steel shredder sludge that contains copper wire and other metallics in a matrix of plastic and natural fibres, iron oxides, metallic iron, and other compounds. Characterisation methods discussed include chemical analysis (XRF, ICP-AES, and selected specialised techniques), phase analysis (XRD, SEM, TEM, and optical microscopy), morphology (IFESEM), sizing analysis (screening, Cyclosizing, Infrasizing, Malvern sizing), and general techniques such as particle shape, surface area, and porosity determinations. The applicability of these techniques to the waste products is considered in relation to their advantages and disadvantages, and sampling issues.Treatment techniques considered for the two waste products included comminution, screening, air or water classification, simple water leaching, gravity separation, magnetic separation, flotation, and eddy current separation.Tentative flow sheets were developed for the two wastes. For aluminium dross, it was proposed to use fine crushing followed by water washing to remove soluble chlorides and aluminium nitride, and then desliming followed by flotation of the granular fraction to give a metallic aluminium-rich concentrate. For shredder sludge, it was proposed to use wet screening, water classification, and gravity concentration to produce a copper-rich product and magnetic separation to produce a metallic iron-rich product.

Jan 1, 2004

By Bernardo Martins Braga

O desgaseificador RH é um reator de refino secundário bem estabelecido. Nesse equipamento, gás inerte é usado para promover a circulação de aço entre a panela de aciaria e uma câmara de vácuo. A predição correta da dispersão de gás na perna de subida do RH é importante para a modelagem confiável do processo. O presente trabalho estudou a penetração de gás na perna de subida do RH por meio de modelos físico e matemático. No estudo, foram considerados apenas um ou dois bicos injetores e vazões de gás, por bico, entre 5l/min e 50l/min. Para as condições com um bico injetor, os resultados das duas abordagens mostraram boa concordância qualitativa. Já para as condições com dois bicos injetores, a concordância só foi satisfatória para vazões de até 30l/min por bico. Adicionalmente, os resultados obtidos indicaram que o problema de penetração de gás em modelos matemáticos de desgaseificador RH identificado na literatura está relacionado com erros numéricos e não com falhas na modelagem da física do problema.

Aug 17, 2017

By Hansmire WH

The 14.7 km Mt. MacDonald Tunnel beneath Rogers Pass in Canada used both drill-and-blast and machine boring methods. A unique ventilation system provides for diesel operations. The design featured minimum construction support and an unrei.nforced poured concrete lining. The west heading was excavated in a single-stage drill-and-blast operation. The east heading used a TBM top heading with a drill-and-blast keyhole bench. The choice of methods was controlled by varying geology, with up to 1,700 m rock cover. Construction performance and progress are evaluated.

Jan 1, 1987

By Tugba Cebeci, Bahjat Khoshaba, Bern Klein, Libin Tong, Andrew Bamber

"Sensor-based sorting technologies have potential to pre-concentrate low grade subeconomic ores through discarding the barren waste particles. However, the inability of sensors to accurately discriminate ore from waste is a barrier to prevent their wide applications. The present study focuses on the development of more intelligent sensing systems by using correlation and regression analysis of X-ray fluorescence (XRF) sensor responses on the copper ore samples obtained from Chile. The responses obtained through XRF scanning were reported both in the form of counts and the grades of elements. Linear and multiple linear correlation analyses were made between the XRF counts and the copper grades obtained through chemical analysis. Both the heterogeneity of the ore particles and the matrix effect in the XRF measurement are discussed in the study.INTRODUCTIONSorting can not only discard waste rocks away from the concentrator but also recover metal bearing ore particles that would be lost to the waste dump. The benefits of ore sorting include reduced energy consumption, water and reagent usage in the downstream operations (Bamber, 2008; Gunson, Klein, Veiga, & Dunbar, 2012; Kleine & Wotruba, 2010; Knapp, Neubert, Schropp, & Wotruba, 2014; Kobzev, 2014; Lessard, de Bakker, & McHugh, 2014; Mazhary & Klein, 2015; Robben, Wotruba, Robben, von Ketelhodt, & Kowalzcyk, 2013). X-ray fluorescence belongs to sensor-based sorting technologies and Xrays are a high energy-high frequency form of electromagnetic radiation inhabiting the region between the ultraviolet radiation and gamma rays (Shackley, 2011). Recent XRF sorting studies on low grade copper ores were carried out at MineSense Technologies Ltd. aimed at increasing the capacity related to improving the understanding of ore heterogeneity as the basis for developing semi-bulk or bulk sorting systems (MineSense Technologies Ltd., 2016)."

Jan 1, 2016

By Kevin A. Foo, Murray D. Bath, John H. Canterford, Arnaldo Ismay

There is no doubt that the dominant future source of gold will be the so-called refractory ores, especially those with gold in a pyrite/arsenopyrite matrix. Minproc Engineers is taking an active role in establishing detailed design criteria for a number of apparently competing processes. This involves generating a detailed understanding of the metallurgy involved, systematic pilot plant testing, and the application of advanced engineering technologies. This presentation outlines the approach adopted by Minproc as well as the design criteria for several current projects.

Jan 1, 1989

By Evan J. Owen, Virginia T. McLemore

There are tens of thousands of inactive mine features in 274 mining districts in New Mexico (including coal, uranium, metals, and industrial minerals districts). However, many of these mines have not been inventoried or prioritized for reclamation. Many of these mines have existing mine wastes, generated during mineral production, which could have potential for critical minerals, especially since the actual mineral production was generally for precious and base metals and not critical minerals. The purpose of this project is to characterize and estimate the critical mineral endowment of mine wastes and “beta-test” USGS sampling procedures. This project is important to the state of New Mexico because critical mineral resources must be identified before land exchanges, withdrawals or other land use decisions are made by government officials. Future mining of mine wastes that potentially contain critical minerals will directly benefit the economy of New Mexico. Possible re-mining of mine wastes could clean up these sites and pay for reclamation. Furthermore, this project will include training of younger, professional geologists and students in economic and reclamation geology by the PIs.

Feb 1, 2024

By Atta Ur Rehman, Kwame Awuah-Offei

This work evaluated the effect of bucket orientation and operating parameters on resistive forces and penetration for rubber tire loaders. The work used a 1:16 scale LHD model to test a rubber tire loader (RTL) bucket operating at different levels of tractive effort, speed, digging height, and rake angles in a full factorial design experiment. The work repeated the test on two different muck piles with different particle sizes and used generalized regression modeling to test the association of rake angle, tractive effort, speed, and digging height on penetration and resistive forces for RTL buckets. The results show that speed and tractive effort are more important in explaining RTL penetration and resistive forces than height above the floor and rake angle. Speed, tractive effort, and height above the floor are positively correlated to bucket penetration, whereas the rake angle is negatively correlated to penetration. Similarly, speed, tractive effort, rake angle, and height above the floor are all positively correlated to resistive forces incurred during initial penetration. The observation that the combined effect of speed and tractive effort is negatively correlated to penetration and resistive forces is a novel contribution that enhances our understanding of RTL loading. The results also show that the effect of speed, tractive effort, and height above the floor all change with changes in particle sizes. This work adds to the literature on the effect of rake angle, height above the floor, tractive effort, and speed on penetration and resistive forces for rubber tire loaders.

Aug 24, 2020

By Guangwei Wang, Changle Zheng, Yifan Chai, Jian Guo, Weiwei Geng, Jianliang Zhang

In this paper, characteristic and kinetics of CO2 reaction with four different kinds of coke such as top-loading coke, dry quenching tamping coke, wet quenching tamping coke and semi-coke were investigated based on isothermal method. Electric resistance reduction furnace was used to heat the sample. Volume Model (VM) and Shrinking Core Model (SCM) were used to calculate the kinetic parameters and to contrast with the experimental results. The results showed that the Volumetric Model (VM) was much suitable for the reaction of top-loading coke, dry quenching tamping coke and wet quenching tamping coke, while Shrinking Core Model (SCM) was much suitable for semi-coke.

Jan 1, 2015

By IRENE AITKENS

The Mining Law of 1910 , with amendments of 1914 and 1928 , is at present in force in the Dominican Republic . The first and basic mining law of the Republic was passed in 1876 , and although numerous changes and amendments have been made from time to time , the new laws and amendments thereto have not changed the original or basic law materially . However , these enactments have materially changed the legal methods governing the exploitation of the mineral resources of this country and have added new regulations and requirements to those concerning certain specific minerals , etc. The original or basic law still exists as it was first promulgated to protect the rights of the Dominican Republic itself , the rights of the landowner , and the rights of prospectors in general . The Mining Law of 1876 remained in force , without amendment , until it was superseded by the law of May 25 , 1904 , an enactment modeled after the Mexican mining law and designed especially to encourage the investment of

May 1, 1931

By W. E. Straszheim

Computerized microscopic techniques were used to determine the size and identity of the ash-forming mineral components, as well as their association with the organic coal matrix, in order to aid in the development of physical methods of beneficiation which require such characterization for the most effective cleaning. Examples of particle size measurements, mineral phase identification, and especially coal-mineral association results are given for selected samples of raw and physically cleaned coals. These measurements can reveal certain characteristics of coals which can be be of significant value in predicting coal recovery and mineral matter rejection for coals undergoing beneficiation.

Jan 1, 1989