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By V. A. Marple

At the Twin Cities "lining Research Center (TCMRC) a project is underway to determine how varying the parameters of a coal-cutting process would affect the amount and the size distribution of the generated dust. The cutting parameters being investigated are the cutting speed, depth of cut and shape of the cutting, tool. To accomplish this research ft is necessary to collect and transport the coal dust venerated at the cutting tool to measuring instruments for analysis. The purpose of this contract was to develop and deliver a system of instruments for measuring the size distributions of the generated coal dust. The instruments employed are essentially those developed for particulate air pollution measurements (1, 2). The instrument system covers a particle size range of 0.005 to 20 microns and is capable of performing in situ measurement and presenting data in real time.

Jan 1, 1974

By E. G. Davis

As a result of interest by the U.S. Department of Energy, the Bureau of Mines conducted studies on comminution of bituminous coal to the 2-um particle size range using the Bureau-developed turbomill. Both "plant grind" size (80 pct minus 75 um) and microsize (minus 10 um) coal can be produced in a single step with the Bureau's turbomill. In 15 min, minus 2.4-mm coal milled in water with steel shot was reduced tc 65 pct minus 75 m and 26 pct minus 2 m, with an energy requirement of 139 kW^h/mt coal. Plant-grind size coal milled in water, with Ottawa sand as the milling medium, was reduced to more than 45 pct minus 2 m in 15 min, at 175 kW?h/mt. Plant-grind coal milled with steel shot was reduced to 57 pct minus 2 um in 15 min, at 138 kW?h/mt. When diesel fuel was substituted for water, the milling of the coal was less effective and less energy efficient. Keeping the pulp dispersed was critical. Without an effective dispersant, the slurry became very viscous with increased milling time, resulting in higher energy requirements, low heat dissipation, and poor grinding efficiency.

Jan 1, 1987

Perhaps the most significant development in China's base metal sector is the discovery of major copper porphyries in northern Jiangxi Province and the adjacent southern Anhui Province. At the center of the new exciting district is the proposed Dexing copper complex, located some 350 km east of Nanchang, the provincial capital of Jiangxi. This project represents China's first attempt to put together a major large-scale open-pit operation, comparable in magnitude to Arizona porphyry operations. With the aid of Fluor Mining and Metals, the Chinese plan to develop a 135-175 kt/d open-pit mine, a matching large-scale mill, and the infrastructure needed to accommodate the big operations. An operation of this magnitude would significantly reduce China's import requirements by some 75%. China imports of the red metal are running around 200 kt/a. Under the direction of the Ministry of Metallurgical Industry, the Chinese are currently operating a 10-kt/d mine and mill with equipment primarily of Chinese origin. Dexing engineers told ME that they are considering a possible scale-up to 20 kt/d. How this effort will ultimately jell with the major expansion program is largely a matter of conjecture. Fluor Mining and Metals received a $10-million contract in December 1978 to develop a preliminary engineering and design program. While the original plans called for a 175-kt/d capacity complex, the Chinese subsequently decided to scale it down somewhat. The current proposal is around a 135 kt/d, which would in- elude the existing operation, according to Dexing engineers. Completion of the engineering and design phase is expected by March 1980 and a go-ahead decision will likely be made at that time. The value of the engineering and construction contract is estimated between $800 million and $1 billion. At right, mined ore is dumped 150 m down the mountain to a holding pocket below for rail haulage to the processing plant. Below, a Chinese miner tackles the universal problem of hard toes in the pit with a jack leg. Reserves and Early History The Dexing mineralization consists of three principal ore bodies, including the Chushahung on the north mountain, and the Tungchang and Fuchiawu on the south mountain. Combined ore reserves are estimated by mine geologists at 1.7 Gt of 0.4-0.5% copper. As is characteristic of porphyries, the ore contains important associated values of molybdenum, rhenium, pyrite, gold, and silver. There is also some secondary calcocite and bornite with an oxidized capping. Historically, copper was recovered with iron from the pregnant solutions emanating from the Tungchang deposit as early as the Tang Dynasty (700 AD). Modern day exploration was conducted by the Bureau of Geology in 1956 and reserve figures were es-

Jan 3, 1980

The dynamic response of holdup in a continuous ball mill has a direct influence on the rate function of grinding kinetics and is useful for predicting the variation in the size distribution of the finished product with time.A model was proposed involving three interacting, completely mixed chambers and this was used to derive analytically the transfer function of the system, from which the unit impulse response and the unit step response of the holdup with feed rate were obtained.The theory was confirmed by comparing it with previously published experimental data for the residence time distribution of particles passing through a ball mill.

Jan 1, 1975

By B. G. Kelley

The MIDREX® Direct Reduction Process was developed during the 1960s by the Midland-Ross Corporation, which had pioneered shaft furnace technology and stoichiometric gas reforming for use in processing minerals. In 1969, the first MIDREX® Direct Reduction Plant was built in Portland, OR. Since then, 49 additional modules have been sold in 18 countries. For the last ten years, over 60 percent of the world's direct reduced iron has been produced in MIDREX Plants. During the quarter century since commercialization, many technical improvements have been made, including larger shaft furnaces, in-situ reforming, greater heat recovery, improved catalysts, and hot briquetting. Midrex continues to enhance the technology in the areas of economy-of-scale, energy efficiency, alternate fuels, and raw material flexibility.

Jan 1, 1998

By D. A. Reynolds

THIS PAPER gives results of an investigation of the composition and carbonizing properties of coals from the Beckley bed, Caretta No. 5 mine, Susanna, McDowell County, and Glen Rogers No. 2 mine, Glen Rogers, Wyoming County, W. Va. The investigation included BM-AGA carbonization tests at. 800° and 900° C. and various chemical and physical tests designed to evaluate agglutinating, plastic, and expanding properties of coal. Both coals were of low-volatile bituminous rank, and each was blended with 70 and 80 percent high-volatile A coal from the Pittsburgh bed, Warden mine, Allegheny County, Pa. The Beckley bed was 39 to 58 inches thick at three points in the Caretta No. 5 mine, and the coal was 39 to 49 inches thick. The carbonizing sample contained 83.0 percent fixed carbon on the dry, mineral-matter-free basis. It contained 3.1 percent moisture, 15.8 percent volatile matter, 72.4 percent fixed carbon, 0.7 percent sulfur, and 8.7 percent ash, as carbonized. The ash softened at 2,680° F. The free-swelling index was 7;i, and the agglutinating value was 7.7. This sample fused weakly in the Gieseler plastometer; its blends with 70 and 80 percent Pittsburgh coal attained maximum fluidities of 830 and 600 dial divisions per minute, respectively. The single coal yielded 83.0 percent coke at 900° C. Yields of other carbonization products per ton of coal at 900° C. were: Gas, 9,950 cubic feet; tar, 3.5 gallons; light oil, 1.36 gallons; and ammonium sulfate, 16.3 pounds. Blending with Pittsburgh coal lowered the yield of coke and raised the yields of other products significantly. Caretta coal yielded strong, blocky coke at 900° C., 89 percent of which was plus-2-inch size. Strength indexes of 900° C. coke from 30:70 blends of Caretta No. 5 and Pittsburgh and of Pocahontas No. 3 and Pittsburgh coals were, respectively: 2-inch shatter, 68 and 53; 1%-inch shatter, 90 and 85; 1-inch tumbler, 50 and 53; and %-inch tumbler, 62 and 65. The specific gravity of the 900° C. gas from Caretta No. 5 coal was 0.272, and the heating values were 491 B. t. u. per cubic foot and 2,440 B. t. u. per pound of coal. The blends yielded much richer gas. Yields of tar acids and bases (0.09 and 0.04 gallon per ton, respectively) were within the normal ranges for low-volatile coals. Caretta No. 5 coal expanded 7.5 percent in the sole-heated oven at a charge density of 55.5 pounds per cubic foot. The blends containing 70 and 80 percent Pittsburgh coal contracted 4.8 and 7.5 percent, respectively.

Jan 1, 1953

By J. A. Kost

The objectives of this contract were to determine the amount, size, and deposition of float coal dust (74 x 10 microns) generated during the mining and transporting of coal in underground U.S. mining operations. Rock dust distributed by trickle dusters was also sampled. In addition to four belt-transfer points, two continuous and two conventional mining sections were sampled at five mines located in Pennsylvania, West Virginia, Kentucky, and Illinois. Float-dust samples were collected on deposition pans; total airborne dust was collected with MSA Model C personal samplers equipped with Unico filter casettes; Andersen cascade impactors provided relative size distributions of the samples. Production, airflow, and water flow were monitored to examine their effect on dust levels.

Jan 1, 1981

By Su-Ping Peng

Three dimensional (3D) seismic exploration has been carried out since the 1980s in the mining district of China, where it has been playing an indispensable role in the high yield and efficiency of coal mining. Unlike oil exploration, this technique uses high density seismic acquisition technology. In recent years, it has focused on wide azimuth 3D seismic acquisition. Evaluation of geometry moved away from depending on folds, azimuth and offset, toward being based upon a focus-ray beam. Conventionally, coalfield 3D seismic interpretation focused on time domain and was based on kinematics information, which is only suitable for less complex geological conditions. To achieve high-resolution processing for the complex topography and structure in coalfields, data processing shifted from poststack to prestack. The means to improve the accuracy of interpretation for complex geological conditions are 1) integration of multiple attributes and multiple disciplines, 2) combination of seismic and geological data, and 3) comprehensive combination of time domain and depth domain data. With the demand for lithological exploration, high-resolution data processing must also take into account the requirements of preserving amplitude in seismic data. Seismic attributes technology, seismic inversion technology, and dynamic tracking interpretation are key techniques in 3D seismic exploration. They greatly improve interpretation accuracy, produce better results in the goaf space description of the coal-bearing strata and coal seam structure, and effectively reduce exploration costs under complicated geological conditions. Therefore, these techniques will be the primary means employed in the future to deal with coalfield complex structure and lithological exploration.

Aug 1, 2013

By G. Barr

"The Polymetallic Twin Metals Project deposits in Northern Minnesota are being developed by Twin Metals Minnesota. Amongst the flowsheet alternatives being examined at a prefeasibility study level is one involving flotation of a bulk concentrate followed by high temperature autoclaving of the concentrate using the PlatsolTM Process to solubilize all the valuable metals in the concentrate (Cu, Ni, Pt, Pd and Au). Autoclave operating conditions have been established in which recoveries of all the pay metals are in the 92 to 99% range, and the autoclave residence time has been reduced to an hour. The stability of the precious metals in solution after autoclaving has been assessed, as well as the impact of internally recycling process liquors to the feed to the autoclave.INTRODUCTIONPlatinum group metals (PGMs; platinum, palladium, rhodium, ruthenium, iridium and osmium) are traditionally recovered from their ores by production of a high-grade concentrate by flotation and/or gravity concentration followed by smelting of the concentrate. Concentrates are smelted to remove nonsulphide minerals and converted to remove iron and sulphur. The resulting high PGM grade matte is processed hydrometallurgically to leach the base metals, leaving a residue with a very high grade (20-40%) PGM concentrate for final refining to individual PGMs. Due to the complexity of this process and its high capital cost, this process can only be applied economically to high grade PGM ores. Lower grade PGM concentrates might be accepted as copper and nickel concentrates but may not yield attractive payment terms for the PGMs. The mineralized Duluth Gabbro region of Minnesota hosts several low grade base and PGM deposits and Twin Metals Minnesota is working to develop the Twin Metals Project deposits. Earlier studies at both pre-feasibility and feasibility level, by other mining companies, have failed to yield an economically viable project based on the traditional process. It is possible to produce a saleable copper concentrate from these ores, but economic recovery of nickel and PGMs into saleable concentrates proved elusive.In the late 1990’s and early 2000’s the Platsol™ process was developed at SGS in Lakefield, Ontario (at the time Lakefield Research Limited) for the NorthMet deposit (also within the Duluth Gabbro) owned by PolyMet Mining. The process developed was a high temperature chloride-assisted pressure oxidation process capable of dissolving simultaneously the base metals (Cu, Ni, Co, Zn), gold and the PGMs."

Jan 1, 2012

OneSteel and BlueScope Steel have been working with the CSIRO to develop sustainable carbon fuels and reductants which are suitable for use in the iron and steel industry. One of the initial focuses of this work has been a process called steel recarburisation which is the addition of carbon to liquid steel to produce particular steel grades. This paper reports on the preliminary work and the recent full scale recarburisation plant trials conducted at the OneSteel Sydney Steel Mill.   Preliminary experimental work involved kilogram scale recarburisation of liquid steel with a range of commercial and prepared charcoal products. This work showed that charcoal dissolves into liquid steel very quickly and that carbon recovery to steel was inversely related to the charcoal volatile content. Initial larger scale work focused on the collection of wood, and preparation of low volatile charcoal which is required for steel recarburisation. Approximately three tonnes of charcoal was prepared at the Corrimal coke ovens of the Illawarra Coke Company. This charcoal was dried, crushed, sized and packaged in a form suitable for addition to 80 tonne liquid steel ladles.   The recarburisation trial was conducted over 30 ladle heats during June 2009. The charcoal was manually added to the liquid steel in 5 kg bags using normal plant practice. Conventional commercial recarburiser was also added to the liquid steel in alternate ladle heats. The performance of the charcoal was compared with the conventional recarburiser based on the carbon recovery to steel, hydrogen pick-up by steel and the rate of carbon dissolution into steel.   An analysis of the trial results showed that the charcoal performed at least as well as commercial recarburiser in carbon recovery and rate of dissolution but may have resulted in a slightly higher hydrogen content of steel. This is probably due to the higher moisture content of charcoal. The main challenges in the future include: increasing the charcoal density to improve transport and handling economics, securing a sustainable supply of biomass for the steel industry and developing a charcoal production industry so materials of suitable quality for both production and trials on other applications can be conducted.

Jun 1, 2010

By Saulo Morais de Andrade

Aços de alta resistência mecânica têm sido aplicados largamente no setor automotivo para redução do peso veicular e aumento da segurança. O aço de alta resistência e baixa liga (ARBL) é um dos exemplos de materiais utilizados em peças estruturais e de reforço dos automóveis. Nesse trabalho foi avaliado o efeito das temperaturas de bobinamento e encharque nas propriedades mecânicas do aço ARBL laminado a frio microligado ao nióbio, com limite de escoamento mínimo de 410 MPa, produzido em escala industrial. De uma forma geral, foram observados queda nos limites de escoamento e resistência, e aumento do alongamento total do aço com a elevação das temperaturas avaliadas. Foi observado que a temperatura de encharque apresentou uma maior influência, ocasionando uma maior queda na resistência mecânica. Como não foram verificadas alterações significativas no tamanho de grão ferrítico, as variações nos valores de propriedades mecânicas podem ser atribuídas ao coalescimento de precipitados.

Aug 16, 2017

By A. du Plessis

The study summarized in this paper focused on expanding existing South African mine closure cost calculation models to provide a new model that incorporates risks, which could have an effect on the closure costs during the life cycle of the mine. This research is important because currently there are a number of mines that do not have sufficient financial provision to close and rehabilitate the mines. The magnitude of the lack of funds could be reduced or eliminated if the closure cost calculation is done in a more risk-orientated manner. The model consists of an expansion of existing closure cost calculation models, by applying the Monte Carlo risk simulation technique to model influences of external and internal changes affecting closure costs. It is shown that the proposed risk-based model provides a way to understand better the implications of uncertainty on the closure costs.

Jan 1, 2006

By J. A. Meech, R. J. Tucker

"Since the establishment of froth flotation as an effective method of mineral beneficiation there has been both academic and industrial interest in the levels of the various reagents required to perform the desired separations. Academic interest was spurred by a desire to understand the mechanisms involved - industrial interest by a need to improve the efficiency of the process. These efficiency improvements can take two forms: cost reductions due to reduced reagent consumption and/or improved separation efficiencies. The latter are indicated by either improved grade-recovery relationships for removal of a valuable mineral from gangue, or improved separation of two similar valuable minerals.The processing of lower grade ore bodies at higher tonnage rates has necessitated increased interest in both reagent consumption and metal recovery. Furthermore, the development of accurate and functional on-stream analysis equipment in the 1960's and 1970's has allowed for a better understanding of the dynamic processes involved in a flotation circuit and has required a more concrete statement of the relationships and reactions between the minerals and chemicals in the flotation pulp. Development of these relationships is necessary in order to make use of on-stream analysis to control the process at, or near its more efficient level."

Jan 1, 1984

By Bruce I. Thomas

The Fairbanks mining district forms an arc 40 miles long and 8 miles wide on the north side of the Tanana Valley in central Alaska. This is a region of broad valleys and rounded hills that range in elevation from 600 to 2,600 feet Lode-gold production started in 1910 and has continued sporadically to the present, but the largest single mine produced only 40 tons per 24-hour day. Total recorded lode-gold production of the district is 241,000 fine troy ounces of gold from ore that averaged 1.32 fine ounces per ton. The ore was mined chiefly from narrow veins and veinlets alined along anticlinal folds at Ester Dome and the Pedro Dome-Cleary area. The only proven reserves are reported to be at the Ryan Lode at Ester Dome and at the Keystone Mines, Inc., holdings in the Pedro Dome-Cleary area. An inferred lode-gold resource for the district of approximately 4,000,000 ounces is considered to indicate only the order of magnitude of the lode-gold potential because of the absence of detailed data needed to evaluate the numerous deposits.

Jan 1, 1973

By Jonas Pedro Caumor

As válvulas parcializadoras funcionam distribuindo a vazão de vapor em uma turbina de maneira uniforme e o mais próximo possível de uma atuação linear. Esta vazão depende da área de passagem que por sua vez depende do curso. Para o controle da parcialização de vapor, da potência e rotação, o curso da válvula deve ser mantido ao longo do tempo. Os servomotores que atuam nas válvulas, em sua grande maioria, possuem atuação linear, do tipo simples ação, são compostos de molas e são acionados por pressão hidráulica de óleo. Eles sofrem perdas de linearidade ao longo do tempo e entre as principais causas está a histerese de mola, necessitando assim de ajustes ao longo do tempo. Os ajustes são feitos de forma mecânica e hidráulica, manualmente. A leitura do curso é feita visualmente através de régua graduada, feitos com a turbina parada e sem considerar a atuação do vapor nas válvulas parcializadoras. São propostas modificações feitas no conceito do servomotor, usando um de dupla ação e para que o mesmo faça uma correção eletrônica do curso, a posição da válvula é medida através de um transformador diferencial variável linear (LVDT) Um dos conceitos apresentados é o uso do servomotor de dupla ação. O controle da turbina é feito por um regulador que envia um comando a um conversor eletro-hidráulico que atua no servomotor. Os conceitos apresentados fazem com que esta transformação eletro-hidráulica seja totalmente controlável, mais precisa e constante, mantendo o curso da válvula.

Jul 31, 2018

By A Unlutepe

The Bosphorus Rail Tunnel Project, located in Istanbul, Turkey, aims to provide a Euro-Asian rail link, via an immersed tube tunnel crossing the Bosphorus Strait, along which will run all commuter, freight and intercity passenger trains of Turkish State Railways (TCDD), as well as the future extension to the European rail network. The total length of upgrading and new railway construction will be approximately 76 km. The main structures include the immersed tube tunnel; mechanised shield tunnels; new Austrian tunnelling method (NATM) tunnels; cut-and-cover, at-grade and retained-cut/fill structures; and some service structures. This paper discusses Phase 1 implementation of the project, one of the major transportation infrastructure projects in the world today, whose varied structures present stimulating engineering and construction challenges.

Jan 1, 2008

Platinum-group minerals (PGM) are recorded from a number of localities along theWaiau River, western Southland, and the south coast of the South Island, New Zealand. At each locality, small amounts of PGMs were recovered as by-products of historical gold mining operations. During the period 1890-1950 an estimated 1000-2000 oz. of æplatinumÆ were recovered from the region, the only area within New Zealand where PGM have been commercially exploited. The PGM suite of southern New Zealand consists of Pt-Fe alloys, IPGE (iridium subgroup, platinum-group elements) alloys, sperrylite (PtAs2), cooperite (PtS) and braggite ((Pt,Pd)S). The composition of Pt-Fe alloy exhibits considerable variation and two compositional populations are recognised. Some Pt-Fe alloy grains are chemically zoned. Iridium is the most abundant IPGE alloy phase and often contains considerable Pt, in contrast to osmium and ruthenium alloys. Cooperite and braggite grains are characterised by extremely low concentrations of Ni.   Exsolution of osmium and iridium from Pt-Fe alloy and Pt-Fe alloy from iridium is observed Several PGM host mineral inclusions which vary from single to poly-phase, display rounded to equant outlines and range in diameter from greater than 100 ¦m to less than 5 ¦m. Olivine and Ni-sulphide inclusions are only present within IPGE alloys. Pt-Fe alloy, cooperite, braggite and sperrylite host Cu-Fe sulphides, a wide variety of PGM, clinopyroxene, amphibole, magnetite and plagioclase within inclusions. Sperrylite also hosts Pd bismuthiotellurides, gold and several potassium-rich silicate phases. Similarities in inclusion phases and mineral chemistry from several localities suggest that the PGM are derived from a single (as yet unidentified), probably calc-alkaline magmatic source. This source is situated somewhere along the margins of the western Southland sedimentary basin where PGM liberated by erosion are transported down the Waiau River and dispersed eastwards along the coast by strong longshore currents.

Jan 1, 1995

By Henry Stoch

It?s a green, green world ? Public concern about the impact of human activities on the environment and the roles that businesses play in that impact is rising. What?s happened in the last few months? ? Recent news: ? British Columbia announces carbon tax in 2008 budget ? Federal Court ruling stalls oil sands approvals due to a lack of consideration of GHG implications ? US Energy Independence and Security Act could limit government procurement of oil sands-derived fuels ? Western Climate Initiative (WCI) suggests a ?first seller? approach for regulating generators outside WCI jurisdictions ? Implications ? A cost for carbon has arrived ? The lack of a GHG strategy can have a material impact on your business ? Regulations in other jurisdictions could affect your organization

May 1, 2008

By L. K. Weaver

Bureau of Mines investigated the progressive impact that petroleum (crude oil and condensate) operations in the Gulf of Mexico have had on onshore operations and the expected effect of increasing activities in this area on future petroleum supplies from domestic sources. The data analyzed include capital expenditures, number of wells drilled, success ratio for exploratory wells, daily production per completion, annual producing rates, and oil reserves. The report compares offshore and onshore data and ascertains trends in petroleum industry operations. Observed data and trends indicate that in the near future Gulf of Mexico development and production will continue to increase relative to total U.S. petroleum activity. By 1975 annual oil and condensate production from the Gulf of Mexico is expected to be in the range of 750 million bbl to 1,150 million bbl, and account for approximately 20 to 30 pct of the estimated total domestic production.

Jan 1, 1969

By Gary Choate

The work presented in this report represents the background activity which led to the fabrication and testing of a greenhorn and crowd limit switch system for electric shovels. The program began With a literature search and manufacturers product review to gather material as a basis for concept generation. Visits to three open pit mines provided information from operation and maintenance managers which was useful in preparing design concepts. These concepts were evaluated through laboratory tests and engineering analysis to select a final design concept. The resultant greenhorn is four separate shock absorbing pads each enclosed in a housing which bolts to the end of a dipper handle adaptor. The plungers impact against stops mounted to the saddle block. The crowd limit control is a nonmechanical device which senses the location of the dipper and makes appropriate commands to the crowd motor to insure against impacting the greenhorns. The electronic crowd limit control is redundant and indicates malfunction modes. The greenhorn prevents shovel damage in the unlikely event of impact.

Jan 1, 1983