Search Documents

By Diego Canez Fernandes

O atual cenário mundial do mercado de carvões e da fabricação de aço vem estimulando mudanças no mix de carvões praticados na Usiminas. Neste contexto, foram realizadas alterações significativas no mix, com destaque para o aumento da participação de carvões alto voláteis e coque verde de petróleo. A qualidade do coque foi mantida por meio de ajustes de parâmetros operacionais na britagem, aliados à adição de óleo na mistura. O objetivo desse trabalho é apresentar a evolução do consumo desses materiais e os resultados de qualidade do coque. Os resultados de qualidade do coque (DI15/150, CSR e CRI) não sofreram variações significativas com a elevação da participação dos carvões alto voláteis e coque verde de petróleo, mantendo-se dentro da faixa visada.

Aug 1, 2018

By H. C. Rolseth

The first step in the quarrying of granite, following removal of any overburden material, involves the freeing of large blocks from the formation. For many years the use of explosives was the accepted method of obtaining these blocks. Even today there are operations where this is considered to be the most economical method even though it does result in a high percentage of damaged stone. In more recent times the preferred procedure at most quarries has been to produce a continuous vertical cut or slot completely around the block to be separated. Originally, this was done by drilling a series of closely spaced holes around the block and breaking the web between the holes with a chisel-like tool known as a broaching bar. The machine used in this mechanical method of producing the relief slot is known as the channel bar. The modern day approach to the production of continuous channels was introduced to the industry around 1955 by the Linde Division of Union Carbide Corporation. The method employs a small rocket - jet burner producing a high temperature, high velocity exhaust flame which when directed against the granite causes it to disintegrate. This method, which has come to be known as "Jet Channeling", is now used by practically every major granite producer in the United States and Canada.

Jan 1, 1968

By John S. Berber

To improve the economics of low-temperature carbonization of coal, the Bureau of Mines is conducting research on the upgrading of the product tar to marketable chemicals. This report describes experiments on the catalytic hydrodealkylation, followed by catalytic vapor-phase oxidation of the dealkylate to phthalic and maleic anhydrides, of mixed residues from the urea adduction of lignite-neutral oil fraction and on the catalytic thermal dealkylation of high-boiling tar acids. The hydrodealkylation experiments were conducted at pressures from 1,000 to 1,750 psig and at temperatures from 600° to 1,000° F. The oxidation was, in all cases, at atmospheric pressure and 9500 F. Maximum yield of maleic anhydride, based on the liquid feed to the hydrodealky1ation unit, was 12.2 percent at 750° F and 1,500 psig; that of phthalic anhydirde was 6.9 percent at 650° F and 1,500 psig. Maximum yield of combined anhydrides was 18.8 percent at 650° F and 1,500 psig. The non-dealkylated feed material, upon oxidation, yielded 8.9 percent and 3.8 percent maleic anhydride and phthalic anhydride, respectively.

Jan 1, 1967

By H. Ahrens

El presente estudio refiere la importancia de los explosivos y detonaciones en el campo de la minería a través de una breve revisión historiográfica, legislación, problemas relacionados con la voladura y métodos empleados. Cabe sa señalar que la evaluación de estos explosivos, así como las pruebas características de estos conllevan una aplicación práctica, de forma que se pueda conocer la composición del explosivo y determinar una posible falla en los disparos.

Nov 20, 1972

By Milton E. Jennings

On May 11, 1977, the SAMARCO 20-inch, 396-kilometer (246-mile) Pipeline was placed in service. This system represents the latest thinking in slurry pipeline design and is one of the main contributors to the viability of the SAMARCO Project. This paper presents the background, description and latest information on the system's operation. Special attention is given to the handling limitations of the slurry and to the unique hardware requirements.

Jan 1, 1978

By T B. T Nguyen, L Matthews, D O’Dea, T Honeyands, T Harvey

Productivity and fuel consumption of the blast furnace is driven by the quality of the iron ore sinter, which in turn is related to the sinter mineralogy. The sintering conditions including temperature and gas composition have a significant influence on the formation of melt and finally the mineralogy of the sinter. In this work, analogue sinter tablets were produced from iron ore fines in a laboratory furnace with tightly controlled temperature profile and oxygen partial pressure in the gas. The mineralogy of the sinters was analysed using reflected light microscopy. The results showed that increasing thermal enclosed area (area enclosed by heating and cooling curve above a reference temperature) reduces primary hematite and platy silico-ferrite of calcium and aluminium (SFCA) contents. This is attributed to increasing melt formation, leading to greater assimilation of the iron ore particles. Lower magnetite was found for tablets with greater median pore size, which is thought to be due to greater oxidation of magnetite to hematite during cooling in air. It was also found that higher alumina content was found to result in more SFCA formation under the same heating/cooling conditions, whereas tablets with higher goethite had higher assimilation and produced more secondary hematite on cooling. Finally, it is necessary to relate the enclosed area to the temperature at which the melt formation becomes significant which strongly depends on chemical composition of the ore studied.

Nov 8, 2021

By Tom B. Corry

INTRODUCTION Located approximately 48 km (30 miles) south of Dallas, Texas, use to be the site of the Superconducting Super Collider. For those of you unfamiliar with the project, this was a multi-billion dollar project taken on by the U.S. Government for the further advancement of technology, medicine, and science. Major components of the project consisted of a Linear Accelerator known as the LINAC; three accelerating rings known as the Low Energy Boosters (LEB), Medium Energy Booster (MEB) and the High Energy Booster (HEB); the East and West Campuses where the Inner Reactor Halls would have been located; and the 87 km (54 mile) main collider tunnel. Unfortunately, this all came to an end on December 6, 1993, with the termination of the project due to the Government's cancellation of funds. This paper will deal with the two of the underground contracts before the termination. These two contracts were the 1122 contract which ran from N25 to N40 and the 1130 contract which ran from N40 to N55. (See figure 1) The 1122 contract was awarded to us in July of 1992 and consisted of the excavation and support of six (6) shaft varying in diameter from 5.5 m (18 feet) to 8 m (26 feet) and ranging from 39.6 m (130 feet) to 61 m (200 feet) deep and the driving of approximately 13,100 m (.43,000 If.) of main collider tunnel. Our second contract, the 1130, was almost identical to our first

Jan 1, 1995

By K. K. Kershner

To meet an increasing demand for high-purity cobalt, the Bureau of Mines has conducted investigations for producing this metal. Cobalt having a purity of 99.95 percent or higher is needed to determine heats of formation, corrosion resistances, phase diagrams, and other basic properties of the element and its compounds. This grade of cobalt may be used for preparing radioactive metal. As a result of its investigations a detailed procedure, which is of practical significance to the production of high-purity cobalt, has been developed by the Bureau for purifying cobalt solutions and for electrolytic deposition of the metal. Cobalt metal, which had a purity of 99.99 percent with reference to metallic contaminations, was deposited electrolytically. Qualitative spectrographic analysis showed only traces of calcium, copper, iron, magnesium, nickel, and zinc.

Jan 1, 1956

By Dong Joon Min, Joo Hyun Park, Mi Sun Choi, Jae Hong Shin

Sublimation of ZrCl4 is important for the production of nuclear grade metallic Zr in Kroll’s process. The sublimation kinetics of ZrCl4 was investigated by TGA under both isothermal and non-isothermal conditions. The sublimation rate of ZrCl4 increased with increasing temperature under isothermal conditions. ZrCl4 sublimation was confirmed to be a zero-order process under isothermal conditions, whereas it was first-order kinetics under non-isothermal conditions. The activation energy of ZrCl4 sublimation under isothermal conditions was 21.7 kJ/mol. The activation energy for non-isothermal sublimation was 101.4 kJ/mol and 108.1 kJ/mol with the Kissinger method and Flynn- Wall-Ozawa method, respectively. These non-isothermal activation energies were very close to the heat of sublimation (103.3 kJ/mol). Sublimation occurs by two elementary steps: surface reaction and desorption. Therefore, the overall activation energy of ZrCl4 sublimation is 104.8(±3.4) kJ/mol. The activation energy of the surface reaction and desorption steps are proposed to be 83.1 kJ/mol and 21.7 kJ/mol, respectively.

Jan 1, 2014

By Norman J. Sather

LOCATION AND HISTORY The Bunker Hill Mine is situated on the south side of the Coeur d’Alene River in Shoshone County of Northern Idaho near the City of Kellogg. Kellogg, the largest in the Coeur d’Alene District cities, is at an elevation of 2,300 feet and has a population of approximately 7,000 people. It can be reached by air, railway or highway. The history of the Bunker Hill Mine dates back to August 26, 1885, when Noah S . Kellogg found the outcrop of the Bunker Hill ore body on the hillside above the present town of Wardner, Idaho, in Milo Gulch. A small concentrator was erected in 1886. Before the railroad came, the mine output was transported by mule teams to the head of navigation on Coeur d’Alene Lake. After ten years of production, an interest was purchased in the Tacoma Smelter at Tacoma, Washington, to which the entire output was shipped. In 1916 and 1917 a modern lead smelting plant and refinery was erected and in 1927 and 1928, a modern Electrolytic Zinc Reduction Plant was built and put into operation by the Sullivan Mining Company which was 50% owned and now totally owned by The Bunker Hill Company. GEOLOGY AND MINERALOGY The Bunker Hill ore bodies are found in gray and greenish gray quartzite and argillaceous quartzite of Precambrian age and are known as the Revett and St. Regis formations. Most of the ore bodies are found in the St. Regis formation.

Jan 1, 1970

By M. Tsesarsky, M. Hazan, E. Gal

"Rock masses comprised of stiff inclusions in softer matrix are common in various geological environments. The heterogeneity and multi-scale nature of these materials make the evaluation of their mechanical properties a challenging task, which cannot be accomplished using conventional laboratory tests and composite mixture rules. We employ the homogenization method to estimate the mechanical properties of geological materials with inclusions. The homogenization method solves the equations of elasticity on the material (microscopic) scale for a unit cell subjected to unit strains under periodic boundary condition. The micro-scale elasticity equations are solved using the Finite Elements Method, and are in turn used to obtain the structure scale (macroscopic) material matrix.In this research, Finite Element models for unit cells with spherical and ellipsoidal inclusions were developed. Using the unit cells, a parametric study of the geometrical and statistical microscopic properties of the material composites was performed. The following parameters were studied: volumetric ratio, Young’s modulus ratio, size-distribution of inclusion and inclination angle of inclusions. The main purpose of the parametric study was to study the deviation from isotropy as a function of the aforementioned parameters.It was found that for volumetric ratio of 5%-40%, the deviation from isotropy increases, as the volumetric ratio of inclusions increases. For spherical inclusions, most of the cases studied exhibit quasiisotropic behaviour; whereas ellipsoidal inclusions exhibit considerable deviation from isotropy. The inclination of the ellipsoidal inclusions enlarges the deviation from isotropy (9% at random orientation and 26% at 0°)."

Jan 1, 2015

By V. Baboudjian, R. J. Geren, J. Thiriar

"The electrolytic tankhouse at CCR was recognized by management as lagging behind modem refineries in terms of productivity, energy efficiency and controls. The operation was also burdened by high maintenance costs of cells, floors and electrolyte recirculation systems.A bench marking program was started in 1986 to evaluate processes and other technology by visiting major copper refineries in North America, Europe and Japan. The basic principles necessary to optimize the operation were defined, and a program calledCCR 2000 was prepared for approval of the necessary capital investments.This paper describes the results obtained to date and outlines the remaining work to complete the modernization program, in particular, the control of electrolytes, the elimination of the Baltimore groove and studies to modernize the stripping operation or adopt permanent cathode technology.IntroductionThe CCR Refinery of Noranda Copper Smelting and Refining (Noranda Minerals Inc.) , in Montreal East, is one of the world 's largest custom copper and precious metal refineries with a capacity to refine 350000 tonnes of copper per year. The silver refinery, which treats the copper tankhouse anode slime, foreign slime and precious metal ingots, produces 800 000 kg of silver, 26 000 kg of gold and 3800 kg of platinum-palladium concentrate annually. Copper anodes are received from the Horne Smelter at Rouyn-Noranda, Quebec, and Mines Gaspe Division in Murdochville, Quebec. CCR also refines anodes from Hudson Bay Mining and Smelting Co. Ltd. in FIin Flon, Manitoba, and remelts anode scrap along with blister and purchased copper scrap ."

Jan 1, 1993

By Forrest T. Moyer

THIS CHAPTER of the Minerals Yearbook (Volume III) contains overall injury experience for coal mines, both anthracite and bituminous coal, coke plants, petroleum and natural gas, peat, and asphalt and related bitumens (native); metal mines, metallurgical plants, including ore-dressing plants and primary nonferrous reduction plants and refineries; nonmetal mines; nonmetal mills; sand and gravel operations; slag (iron blast-furnace) plants; and stone quarries and their related plants. Volume I of the yearbook contains a chapter showing injury experience and employment data treated separately by categories: Metal mines, nonmetal mines, quarries and their related plants, metallurgical plants (ore-dressing plants and primary nonferrous reduction plants and refineries are shown separately), nonmetal mills, sand and gravel plants, and iron blast-furnace slag plants. Volume II contains injury and employment experience in the fuel industries (anthracite, bituminous coal including lignite, coke, petroleum and natural gas, native asphalt and related bitumens, and peat). Injury and employment data were collected from coal producers on the regular mandatory basis as required by the Federal Coal Mine Safety Act (30 U.S.C., sec. 455). Similar data for 1962 from metal, nonmetal (except well and brine operations), stone, and sand and gravel producers were collected by a. mandatory reporting system under the provisions of the Act of September 26, 1961, Public Law 87-300 (75 Stat. 649). Before 1962, these nonfuel producers reported voluntarily to the Bureau of Mines. Producers of all other minerals (fuel and nonfuel) reported the requested injury and employment data voluntarily to the Bureau for 1962, the same as in preceding years.

Jan 1, 1963

By D. W. Frommer, L. Bonicatto, M. M. Fine

A mineral - dressing investigation was conducted to demonstrate the ability of an anionic silica - flotation process to produce high- grade concentrates from submarginal iron ores of the western Mesabi and Menominee ranges . Commercially available equipment and reagents were used . Samples from the Menominee range were exclusively from the Groveland , Mich . , mine and contained hematite as the chief iron - bearing mineral . Bench- scale investigations established that the anionic silica flotation method can function effectively on a variety of undeslimed ores . Continuous tests completed on one Mesabi semitaconite ore and on Groveland mill feed , have verified the validity of the bench research . The Mesabi samples yielded a concentrate containing 60.3 percent Fe and 6.0 percent Sio with an accompanying iron unit recovery at 90.5 percent . Iron recoveries from the mill feed ranged from 79.0 to 87.4 percent .

Jan 1, 1964

By Jonguk Kim

The North Fiji Basin (NFB) is a mature intraoceanic back arc basin with an age of ~12 Ma. Recent volcanism and spreading activity are focused along the Central Spreading Ridge (CSR), A ridge segment more than 800 km long, composed of four main segments, the N160°, N15°, north-south (N-S), and southernmost segments from north to south. The dominant volcanic rock in the entire central spreading ridge is normal mid-ocean ridge basalt (N-MORB), very similar to those emplaced along mid-oceanic ridges. Conversely, influence of an oceanic island basalt (OIB) source increases northward from 18°20'S. Several basalts which show a significant subduction-related component are also observed in the southern part of the NFB. Hydrothermal activity along the spreading centers of the North Fiji Basin was investigated by several previous works, especially by the STARMER project in 1989 and 1991. Both extinct and active hydrothermal vents are found on the N15° and N-S segments. In contrast, only traces of hydrothermal activity have been found on the N160° segment. Although high temperature activity and related massive sulfide deposit on the N15° segment was further investigated by several follow-up studies, no systematic survey for other hydrothermal sites was conducted after their discovery. In 2012 and 2013, KIOST performed two hydrothermal expeditions aboard the R/V Onnuri in the three targeted areas of hydrothermal activity along the CSR of North Fiji Basin. All targeted areas include sites for hydrothermal activity reported in previous works. Occurrence and distribution of hydrothermal plume were investigated by combined

Sep 14, 2011

By S. Agatzini-Leonardou

The objective of this work was to prove repeated loading capacities and investigate the selectivity of physically stabilized algal biomass from Spirulina platensis and Chlorella sp. for the removal and recovery of cobalt, nickel and chromium from laterite heap leach liquors. The testwork was carried out on a bench scale in small glass columns and proved that it was possible to immobilize the biomass on the highly porous surface of pumice stone (kissiris). Nickel and cobalt could be removed from pure aqueous solutions of each metal by the immobilized cyanobacterial biomass. Nickel and also cobalt biosorption was sensitive to the initial solution pH. Cobalt recoveries up to 80% were achieved after 5 loading cycles, from low concentration solutions, at pH 6.0. Nickel removal was complete under the same conditions, whereas chromium sorption was ineffective. Desorption of the metal loaded columns was effected by dilute sulfuric acid. The algal species giving the best adsorption capacities for the metals under consideration was selected for further experimental work with real laterite heap leach solution produced by column leaching. A statistical analysis of all obtained results was conducted using the fraction of metal removed as response. The ratio "mass of metal removed to mass of protein contained in the immobilized cells" was determined as well. The described method might be applicable for recovery of cobalt and nickel from diluted laterite heap leach solutions, such as heap wash waters, or for their removal from waste streams of a hydrometallurgical extraction process.

Jan 1, 1997

By R. Simon, A. Khosravi

"Tensile strength of rock samples is measured by direct and indirect tensile tests in accordance with standard guidelines. Due to the difficulties in performing direct tensile test, the indirect tensile (Brazilian) test is conventionally carried out to obtain the ultimate tensile strength. A limited number of studies have been conducted to investigate the role of sample size (length to diameter ratio = L/D) in the stress distribution of the Brazilian test using numerical and analytical methods. These investigations showed that the tensile stress distribution along the loading diameter is not uniform. They also indicated that the difference between the tensile stress at the middle part and at the sides of the sample with higher L/D ratio is greater than that in the other samples.The objective of this study is to show the effect of tensile stress distribution on the fracture surface created by the Brazilian test from a morphological point of view on the samples with different L/D ratio. Hence, a series of fracture surfaces created using the Brazilian tests on the rock samples with L/D of 0.5, 0.75, 1, 1.25 and 1.5 were investigated.In this study, all fracture surfaces were scanned by a 3D laser profilommeter. A number of roughness profiles parallel and perpendicular to loading axis have been selected from the samples with different L/D ratio and spacing of 1 mm. The results show that the roughness of the profiles perpendicular to the loading axis increases with an increase of L/D ratio, while the roughness of the profiles parallel to the loading axis decreases. Furthermore, some roughness profiles parallel to the loading axis were chosen and divided into three segments. The results revealed that the segment in adjacent to the upper loading platen possesses higher roughness than the other segments."

Jan 1, 2015

By R. Roufail

"Energy consumption in stirred mills has been studied, in the last couple of decades, on a macro scale. Effective operation and meeting particle size required for downstream operations used to be the main objectives behind energy utilization of stirred mills. In this paper, three energy terms are defined to assist in understanding the breakage mechanism for various types of minerals versus mill operation. The types of minerals studied had diverse physical and mechanical properties that are summarized as specific gravity, hardness and crystal structure. The minerals utilized in this study were quartz and galena. The effect of quartz and galena mix has been addressed as well as Lead-Zinc ore sample from SAG mill discharge. The energy input to the mill is function of the agitator speed, therefore three agitator speeds were evaluated, 1000, 1500 and 2000 RPM, respectively. The energy terms studied are specific energy (kWhr/ton). Effective energy is the ratio between net energy and total energy consumed by the mill. Last type of energy is the specific breakage energy, which is the net energy consumed by the mill per one-micron breakage. Results showed that specific energy and specific breakage rate are functions of mineral type, while effective energy is only function of mill input power (agitator speed).INTRODUCTIONGrinding is the largest energy consuming component of a mineral processing operation and typically consumes about 50% of the total energy used at a mining operation (Botin, 2009). Over the last two decades, stirred mills have been extensively utilized in mineral processing operations due to increased mineralogical complexity of ore bodies. Stirred mills grind particles to less than 10 µm by applying a high power intensity. The technology has been the focus of several research studies to investigate mill energy and grinding mechanisms. Becker, et. al. (2001) studied the relationship between different types of energy including input energy, specific energy, volume/mass specific energies, to stress intensity and final product particle size. Other studies such as by Kwade (1999), Kwade and Schwedes (2002), Blecher et al (1996), Partyka and Yan (2007), Stender et al (2004), focused on mill design and/or stress intensity distribution. Peukert (2004) studied the effect of mechanical properties of the grinding media and ground material on the comminution process."

Jan 1, 2016

By Lynn B. Hales

The Supervisory Computer System at Cities Service copper mine and concentrator at Miami, Arizona was installed at Pinto Valley in the spring of 1975. Design and specification [l] of the digital system was initiated jointly by key plant personnel at Pinto Valley and staff of Cities Service Research and Development Company. The Pinto Valley digital system [2] may be classified as a supervisory control system of hierarchical design. There are three fully independent satellite computers which retrieve and reduce the raw plant data from each of the three main operating areas - the primary crushing plant, the fine crushing plant, and the grinding and flotation plant. While the three satellite computers are core resident systems, the master computer is a disc-based operating system which also interfaces with a computer controlled on-stream x-ray analyzer system. Figure 1 illustrates the basic system configuration [3]. The software systems required to support a large system are quite diverse and vary greatly in function. The philosophy followed in dividing the software into three categories was designed to: 1) fully utilize existing process knowledge of technical staff; 2) delegate certain software tasks to outside sources already skilled and trained in software development; and 3) maintain final control over the design and operation of each system.

Jan 1, 1976

By M Nehring, M Kizil, P Knights, A Mousavi, F Sotoudeh

A cut-off grade is used to distinguish an economically viable block of ore from non-economical ones in mining operations. In order to obtain a high Net Present Value (NPV), a strategic and precise determination of cut-off grades (mill feed/marginal, marginal/waste) is required. In recent years, the significant depletion of feed grades and increasing mining operating costs have affected the viability of new and existing mining operations. Hence, the introduction of a pre-concentration system to process ore before sending it the main processing plant has gained increasing attention for its potential improvements in resource exploitation processes, mineral processing, energy consumption and environmental impacts. The primary potential advantage of implementing a pre-concentration system is the improvement of resource utilisation and increased reserves as a result of a reduction in cut-off grade. The objective of this paper is to present a new cut-off grade method, which can be used in the presence of a pre-concentration system for underground metalliferous mining operations. The results of this study illustrate the potential economic benefits of using a pre-concertation system prior to a mineral processing operation as a result of the reduced cut-off grade and increased NPV.

Nov 10, 2020