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By Vera Lúcia Othéro de Brito

Literature has shown that spinel Co-Mn ferrite have potential application in magneto-mechanical sensors, due to its relatively high magnetoelastic sensitivity. In this work, Co-Mn ferrite was processed by means of the ceramic method, using Fe2O3, MnO and Co3O4 as raw materials. Samples were liquid-phase sintered, using Bi2O3 additive as liquid-phase former. X-ray fluorescence analysis was carried out in the raw materials in order to evaluate their impurity content. Atomic absorption spectrometry analysis was used for quantifying the Co/Mn/Fe proportion in the ferrite. The microstructure of the sintered sample was analyzed by means of Scanning Electron Microscopy. The magnetization and magnetostrictive behavior of the ferrite were evaluated, obtaining curves for magnetic hysteresis, magnetostriction and magnetoelastic sensitivity. The impurity inclusions and the Bi-rich particles formed from the liquid phase were characterized. The sintered ferrite had a total magnetostriction of -126ppm, which is lower than the values reported in literature for a Co-Mn ferrite of similar composition. It was verified that sintering was carried out within a critical temperature range, in which the decomposition of Mn ferrites may occur when sintering in air. This decomposition affects the magnetic properties of the material, and it may be avoided by using controlled sintering atmospheres.

Aug 8, 2018

By R Symes

The Fosterville Goldmine in Victoria Australia employs the BIOX« Process to liberate gold from its sulfidic flotation concentrate through bacterial oxidation. Gold occurrence is primarily as submicron particles in pyrite and arsenopyrite and has been described as being in æsolid solutionÆ and therefore not amenable to direct cyanidation. Once liberated by the oxidation process, the gold is then available for cyanide leaching. During the oxidation process it has been found that a portion of the liberated gold becomes suspended in the liquid phase in what appears to be a colloidal state. This liquid becomes a waste stream during washing of the oxidised solids and the suspended gold is therefore lost. A method was previously developed using an addition of quebracho tannin to significantly reduce this loss by formation of an iron-tannin precipitate which captures the gold which then reports to the cyanide leach circuit with the oxidised concentrate solids onto which it is adsorbed.This paper discusses the development and plant trial of a second processing step to further enhance gold recovery by use of flotation tailings essentially as a source of extra surface area to capture residual tannin-iron precipitate and its associated gold not recovered in the first step.CITATION:Symes, R, 2012. Recovery of colloidal gold from oxidised concentrate wash liquor - Further improvement, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 383-388 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By T. Egleston

THE works of the Ore Knob Copper Company are situated in the county of Ashe in the northwestern part of the State of North Carolina, about ten miles from the Virginia line, at an elevation of 4600 feet above the sea. The nearest railroad station is at Marion, Smythe County, Virginia, about forty-five miles distant. The roads from the railroad to the works have been constructed by the company for the transportation of their material, and are very hilly, and in certain seasons of the year in bad repair. Transportation is therefore always limited and never easy, although it is done by contract at a very low price. The main difficulty with the transportation is not so much its cost as the fact that it puts a limit to the production of the works. These unfavorable conditions make it necessary for the owners of the mine to smelt their ores and to send to market nothing except the metal, which alone will bear the cost of transportation. The mine was opened previous to 1860, but has only been worked systematically during the last five or six years. The vein is a fissure vein from ten to twenty feet in thickness in the gneiss of the

Jan 1, 1882

By T. Egleston

The works of the Ore Knob Copper Company are situated in the county of Ashe in the northwestern part of the State of North Carolina, about ten miles from the Virginia line, at an elevation of 4600 feet above the sea. The nearest railroad station is at Marion, Smythe County, Virginia, about forty-five miles distant. The roads from the railroad to the works have been constructed by the company for the transportation of their material, and are very hilly, and in certain seasons of the year in bad repair. Transportation is therefore always limited and never easy, although it is done by contract at a very low price. The main difficulty with the transportation is not so much its cost as the fact that it puts a limit to the production of the works. These unfavorable conditions make it necessary for the owners of the mine to smelt their ores and to send to market nothing except the metal, which alone will bear the cost of transportation. The mine was opened previous to 1860, but has only been worked systematically during the last five or six years. The vein is a fissure vein from ten to twenty feet in thickness in the gneiss of the

Jan 1, 1882

By J. F. Smith

A series of studies of emissions from large coal-fired steam generators have included measurements of the concentrations of oxides of sulfur and oxides of notrogen. The sampling equipment, method of sampling, and analytical techniques used for processing of these samples are detailed. A method based on the precipitation of benzidine sulfate was developed for determining both SO3 and total oxides of sulfur in the presence of interfering acidic components in the stack gases. In addition, difficulties encountered with sampling and analytical techniques are also described.

Jan 1, 1968

By A. Chattopadhyay

Porphyry copper deposits are the most important source of copper and also gold within the orogenic belts. These deposits are characterized by low grade copper ore (0.2% to 1% copper) and host precious metals like gold, silver and platinum. A characterization tool has been developed for complex porphyry type copper-gold deposits with an aim to quantify copper and precious metal deportment. This quantification is a challenging task due to low grades and also due to the presence of both visible and invisible precious metal content in different sulphide and non-sulphide phases. Studies were initiated on various complex, ore deposits and also on samples representing various processing streams such as flotation and leach products. This paper presents the development of a systematic approach to diagnostic metallurgy using state-of-the-art optical and automated mineralogy, micro-probe, dynamic SIMS and TOF-SIMS analysis for quantification of invisible and visible precious metals content in various species. The relevance of this characterization to metallurgy will also be briefly discussed in this paper.

Sep 1, 2012

By Nick Barton

The ability to estimate that support is unnecessary for various dimensions of opening in certain rock mass environments is of particular relevance in the mining industry, where most excavations are not expected to remain open indefinitely. As Hoek1 observes: "the basic aim of any underground excavation design should be to utilize the rock itself as the principal structural material, creating as little disturbance as possible during the excavation process and adding as little as possible in the way of concrete or steel support". Approximately two hundred case records have been analysed for the purpose of determining the amount of permanent support normally used when a given span is excavated in known rock mass conditions Some thirty cases concerned unsupported openings. Excavations that can stand unsupported appear to have certain common characteristics as regards rock mass quality. However, the mechanical properties of the rock mass are not the only factors controlling the choice of design. The dimension of the opening (span or height) and the type of excavation are two important variables.

Jan 1, 1975

By Fabiane Leocádia da Silva

Cristais da família cristalográfica do sal de Tutton A2B(XO4)2.6H2O, A=K, NH4, Rb, Cs, Tl, B=Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd, V, Cr, X=S e Se tem sido investigados por diversas técnicas experimentais com o objetivo de compreender suas propriedades físicas e potenciais aplicações tecnológicas. Investigações sobre o comportamento estrutural têm sido realizadas por difração de raios-x a fim de compreender suas propriedades estruturais, principalmente a distorção Jahn-Teller presentes nos cristais com cromo e cobre. Soluções sólidas destes sais na forma A2B'xB”(1-x)- (SO4)2.6H2O, têm sido relativamente pouco investigadas embora possam apresentar distorção Jahn-Teller. A estrutura dos cristais desta série à temperatura ambiente é monoclínica, grupo espacial P21/a com duas moléculas por célula unitária. Bons monocristais da série (NH4)2NixCu(1-x)(SO4)2.6H2O com 0

Aug 16, 2017

By Haydn H. Murray

Although alumina constitutes about ii percent of the earth's crust, it is expensive to separate and purify for the production of aluminum with the exception off the alumina in bauxite. The United states has a variety of non-bauxite resources that could substitute for bauxite, including high alumina clays, alunite, dawsonite in oil shale, anorthosite, and nepheline syenite. Each of these resources are discussed from the standpoint of geology, geography, processing, potential recovery, and environmental problems. Potential by-products include silica from clays, potash and sulfuric acid from alunite, soda ash from dawsonite, and soda ash and potash from anorthosite and nepheline syenite.

Jan 1, 1982

By Steven E. Paulson

In situ mining is emerging as a potential alternative to conventional surf ace and underground mining techniques. A major factor in determining recoveries by in situ mining is the proportion of ore minerals that can be contacted and solubilized by the leach solutions. To provide basic information on the processes occurring during in situ leaching, particularly at the microscopic scale, the Bureau of Mines has developed a geologic characterization research program. This includes laboratory experiments using leaching apparatus that can accommodate whole core samples. Whole core experiments result in higher leach solution-ore mineral contact ratios than packed column experiments, and also allow for the assessment of permeability changes taking place as the result of mineral dissolution, precipitation, and clay swelling within the flow channels in the rock. A nonreactive, reusable reaction cell has been designed and tested. The leaching apparatus can be used for constant-pressure or constant-flow experiments and allows for the control of flow rate, pressure, and temperature during the experiments, thus permitting studies on a wide variety of ore samples. Details of the experimental apparatus and design are presented, as well as preliminary results from the first series of experiments on an oxide copper ore from the Casa Grande, AZ, area.

Jan 1, 1987

Legislation introduced for Queensland and New South Wales Coal mines provides different levels of prescription regarding specification of mine seals û generally in relation to capacity to withstand overpressure. In Queensland, the Coal Mining Safety and Health Regulation (2001), Section 341 (d) places a further onus on the statutory ventilation officer to æensure all ventilation control devices at the mine are properly constructed and maintainedÆ and that the ventilation officer æmust ensure a ventilation control device mentioned in the regulation à and installed at the mine meets the design criteria statedÆ for the ætype of deviceÆ. Based on the experience of the author, it appears that risk management and life cycle approach to seals has not been adopted to the same extent as for other aspects of operations. Further, because of the number of disciplines and personnel involved that may influence various factors affecting seal integrity, the opportunity for oversight or unclear allocation of responsibility is considerable. While suppliers can provide explosion or design rated seals, this should only be a starting point for application of the product in a coal mine. Application is often considered by mine planning staff (taking into consideration mine environment parameters such as water, control of gas, spontaneous combustion risk, etc) in conjunction with the colliery ventilation officer, and then construction completed by contractors under supervision of operational staff. After construction, seals often are managed by operational personnel with input from the ventilation officer. Input of the geotechnical engineer into pillar design, roadway opening size, ground support specification and most stable seal location is also required. The need for a customised design approach for each seal site is proposed in order to take into account the many and variable factors that may influence a site so that improved seal performance reliability and predictability can be developed. A program of quantitative as well as qualitative monitoring of performance and triggers for rectification or maintenance action is required, and would provide support to the aforementioned proposal. Many mines rely on visual/audible inspection and periodic bag sampling as the primary means of assessment. Other significant factors such as seal material properties, rib degradation, convergence, floor heave, effects of water on both structural integrity of the seal as well as the air tightness of the seal do not generally receive the same level of attention. Based on the above observations, the author has compiled a reference checklist in regard to the above matters, including aspects of and approaches to mine and pillar design, geotechnical modelling and data collection, civil engineering design, site evaluation and practical options available.

Jan 1, 2005

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 4, 1919

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 12, 1919

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL,. MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J., JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX, NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 3, 1919

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. LOUIS, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON. . . . ' NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y

Jan 6, 1919

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL, MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON, NEW, YORK, N. Y.

Jan 8, 1919

For the -year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 5, 1919

By Alyse Munro Hindley

The increasing negative public opinion toward blasting has led to stricter regulations and increased costs. This paper outlines alternative methods of rock excavation and the safety regulations and certification required by blasting professionals. Most importantly, however, it showcases the benefits and accomplishments that controlled blasting bring to society, giving the public a better understanding of the necessity of blasting in modern society.

Jan 1, 2015

By Paulo Henrique da Silva Gomes

O tráfego rodoviário de cargas está em franco crescimento, se diversificando nas rodovias e também nos grandes centros urbanos. O uso de novos implementos (carretas maiores e com maior capacidade de carga) resulta no travamento das vias urbanas, causando grandes transtornos à população. Em muitas cidades, o tráfego exige um novo planejamento urbano e construção de vias alternativas. Em Volta Redonda, RJ, estão sendo desenvolvidos projetos com alternativas de fluxos rodoviários, que buscam soluções para o transporte coletivo, bem como, para fluxo de veículos pequenos, médios e de cargas da cidade. O fluxo de caminhões que abastecem e escoam os produtos da CSN - Usina Presidente Vargas, tendem a crescer com o aumento de produtividade da planta de Cimentos e startup da planta de Aços Longos, com início de suas operações em Janeiro/14. Alternativas como a intensificação do uso de ferrovia são foco do trabalho da área de logística da CSN, porém não eliminam o uso do modal rodoviário.

Jul 29, 2018

By Manoel Farias Martins

A utilização de antracito na produção de pelotas de minério de ferro é uma prática utilizada pelas mineradoras para reduzir custos com combustíveis e melhorar a qualidade física do produto. Objetivando uma melhor compreensão dos efeitos ocasionados pela adição de carvão na mistura (pellet feed moído e aditivos) sobre a resistência a compressão das pelotas queimadas, foram confrontados os resultados dos ensaios de resistência à compressão obtidos através da rotina de ensaios da mineradora VALE SA, com as seguintes variáveis: percentual em massa de carbono (%C fixo), porosidade e granulometria do antracito. Com a elevação de carbono, observou-se a redução nos valores da resistência à compressão, sobretudo, nas pelotas de redução direta. No que diz respeito à porosidade, a resistência à compressão das pelotas aumentou com a diminuição dos poros no interior das mesmas. Analisou-se também a granulometria do carvão, todavia, constatou-se que a mesma não teve influência significativa sobre os resultados da resistência à compressão.

Oct 30, 2017