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By Henry M. Howe

A discussion of the paper published in Bi-Monthly Bulletin, No. 20, March, 1908, pp. 227 to 237, and No. 22, July, 1908, pp. 615 to 620. PROF. HENRY M. HOWE, New York, N. Y. (communication to the Secretary *) :-Mr. Hibbard's definition of steel would be the best yet offered were it not for its one defect, the vagueness or equivocalness of "fusion-process." Puddling is surely in one sense a fusion-process, and so are the charcoal-hearth or knobbling-processes. But what he says suggests the following definition, which seems to me a good one: " Steel: any variety of iron which is usefully malleable at least at some one temperature, and is either cast when molten into a malleable mass, or if not so cast can be much hardened by sudden cooling." It is not necessary in a definition that quantitative bounds should be set up, for instance, that the exact height at which dwarf apple-trees cease and standards begin, or at which hills cease and mountains begin, should be stated. These quantitative measures are proper for specifications and contracts, but are not necessary for purposes such as the present. HENRY D. HIBBARD, Plainfield, N. J. (communication to the Secretary t) :-Professor Howe's criticisms of my definition of steel are not, it seems to me, well founded, for the . following reasons: The term "fusion-process" has been used during the past quarter or half century to distinguish the crucible, Bessemer and Siemens-Martin processes from the puddling- and cementation-processes, and probably no one at all conversant with the art of iron-metallurgy would now mistake its meaning. Moreover, no steel-metallurgist is in doubt of the meaning of the term "hardened? as applied to steel. If it were really necessary to describe what is meant by the term then it would

Nov 1, 1908

By Peter Faust

The foundations for the new South Viaduct Bridge in San Francisco were extremely challenging due to the requirement for very large and deep piles installed adjacent to historic structures. Drilled shafts up to 12? foot in diameter were constructed to a maximum depth of 200? feet in alluvial soils and Franciscan Bedrock using an oscillator system for the installation of the permanent steel casing. This paper provides an overview of the construction techniques, the equipment, and the challenges associated with constructing 12? foot diameter shafts on this very complex project in one of the nation?s nicest landscape setting.

Jan 1, 2011

By lves Matiolo, Jorge Rubio, Carlos Perez Guerrero, Denise G. Nunes, Fabiano Capponi

The problem (very old) of processing by flotation, the fine (“F”, 38-13 µm) and ultrafines (“UF”, < 13 µm) mineral particles continues to be a major technical challenge in the area of mineral processing. Many different processes have been proposed over the last three decades but, unfortunately, most of them have not found practical applications yet. This paper describes some advances in flotation research in fines (“F”, 38-13 µm) and ultrafines (“UF”, < 13 µm) mineral recovery by two different techniques. Extender flotation (EF) and flotation with bubbles with a wide size distribution-SB of copper sulphide ore fines (1 % Cu) were compared with a “standardised” (STD) mill laboratory procedure. Comparative evaluation was made through concentrate grade and recovery (size by size results included), “true” flotation recoveries and process kinetics. Copper porphyry samples, containing about 1/3 of the mass and about 37 % of the total copper content in the fines and ultrafines fractions were used. In the EF tests diesel-in-water emulsions were used as an extra reagent, added after the collector and frother addition. In SB tests, drawing air through an aspiration nozzle, directly in the pulp, generated bubbles sized about 50-200 µm. Both techniques yielded higher metallurgical efficiencies than the mill standard but better results were obtained with the extender flotation, with emulsified diesel oil (90 gt-1). Concentrate recoveries were of the order of 85-90 % (84 % in standard conditions), 14-17 % Cu grade (15 % Cu in the standard) and 3.5-4.5 min-1 for the Klimpel rate constant (3 min-1 in the standard). Size by size and true flotation results proved that metallurgical and kinetic gains, obtained with the two techniques, might be attributed to fines and ultrafines enhancement. Data obtained are discussed in terms of physical and physicochemical parameters related to aggregation and capture (of particles by bubbles) phenomena and the practical potential of these techniques are envisaged. The following figure shows size-by-size copper recoveries results, after classification of produced concentrates and tailings using micro-sieves. Results clearly show that flotation of the F and UF fractions is highly improved with injection of small bubbles (SB) and with the addition of an extender collector. It is believed that the techniques presented here will establish shortly a new basis for the flotation enhancement of the F and UF, aimed at solving a very old problem. This work is being continued, now at pilot plant scale, and results will be published en the near future.

Jan 1, 2003

By Tim Neil, O&apos

Copper price rebounds A worldwide scramble for diminishing supplies of copper has pushed the red metal&apos;s price to more than $2.20/kg ($1 per lb), the highest level since 1980. The first nine months of 1987, world copper production was down 1% from a year ago, while consumption rose 7%. Demand has been fueled by economic strength in several countries, particularly Japan, South Korea, and Taiwan. The price has also been helped by interest rate declines that have prompted manufacturers to build up inventories. In addition, China is expected to be a major buyer in 1988 as it stocks up for its five-year industrialization plan. There appears to be no sign of any significant increase in copper supplies until later 1988 or early 1989. This means supplies probably will remain tight for some time even if world economic activity slows. Strikes and other production problems slowed world output of copper in 1987. As a result, copper supplies are the lowest they have been in 14 years. World inventories currently total 625 kt (690,000 st). That is not much above the 585 kt (645,000 st) level reached in 1974 when the price of copper rose to a record $3.84/kg ($1.74 per lb). This makes all the more interesting what Chile, the world&apos;s largest copper producer, has been doing lately. Chile has been the world&apos;s largest copper producer since 1982, when it overtook the United States. Table 1 shows Chile&apos;s copper grades, reserves, and production at its mines. Chile contains roughly one-fifth of the world&apos;s copper reserves. At present production rates, these reserves would last for more than 100 years. In 1986, Chile produced 1.4 Mt (1.5 million st) of fine copper, up 3%. Chile accounted for 17% of the world&apos;s copper output.

Jan 1, 1988

By John D. Thornley

Alaskan villages typically store a one-year supply of fuel to reduce significant delivery costs. Alaska Village Electric Cooperative (AVEC), an electric utility cooperative providing power to 51 Alaska villages, has made a concerted effort to upgrade and improve their undersized and aging facilities. The Village of Stebbins, located south of Nome on Norton Sound is receiving upgrades to its AVEC bulk fuel facilities. Stebbins offered unique challenges from a foundations perspective due to the nature of the soil. The geotechnical investigation found the soil below roughly a third of the footprint of the bulk fuel facility to be thawed with seasonal freezing and the remainder was found to be warm permafrost with ground temperatures of between 30°F and 32°F. This is a unique and challenging arctic engineering design issue because foundations are designed differently for frozen ground conditions. Driven piles were selected because of site constraints, such as the design flood elevation and the change from thawed to frozen ground conditions. The pile design specified that the pile embedment depths would be selected based on the results of pile driving analyzer (PDA) testing during construction in the thawed ground and maintained within the frozen ground portion of the footprint. Difficulties during pile driving in the frozen ground resulted in several piles becoming severely damaged, requiring subsequent removal. This resulted in a reevaluation of the means and methods for pile installation. Additional fieldwork was performed to further characterize the subsurface soils and their frozen nature. Options for installation of piles in difficult areas were evaluated including ground thawing, predrilling, and reducing embedment depths. Presented within this paper are the findings from the initial and subsequent field explorations, discussion of the design methodology, and the decisions that led to successful installation of piles at this challenging remote village.

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals dore&apos; from ores, principally silver bearing with associated gold co-products. In late 1995 a new orebody was commissioned, the Stone Cabin orebody, and the site began a phased shift from silver dominance to gold dominance in terms of precious metals revenue. The Knelson Concentrator was selected to remove gold from a portion of the cyclone underflow stream in the grinding circuit. This paper describes the development of the flow sheet, specific mineralogical impacts on Knelson product and downstream materials, and impacts on mine/mill grade reconciliation.

Jan 1, 1997

By Steve Kral

The mining industry has had three difficult years. Commodity prices have remained low and investor confidence in the industry has been shaken. And even though the Asian economy appears to be improving, it will be some time before this improvement will translate into better commodity price conditions for mining. In addition, increased environmental and social restrictions that have been placed on the industry in developed and developing countries have made mining a more difficult proposition. And, if that is not enough, the global mining industry has found itself in fierce competition with Internet businesses for investor capital. Despite that gloomy picture, more than 10,500 mining industry professionals from about 70 countries gathered in Toronto, Ontario March 5-10, 2000 for the Mining Millennium 2000 conference. This meeting was a joint effort between the Canadian Institute of Mining, Metallurgy and Petroleum(CIM) and the Prospectors and Developers Association of Canada (PDAC).The joint meeting also featured two trade exhibitions and more than 150speakers. PDAC’s trade show attracted about 400 exhibitors and an additional 200 in the concurrent Investors’ Exchange. CIM’s exhibition attracted about 600 equipment and service companies.

Jan 1, 2000

By P. Leo

The Al-Zn-Mg alloys (e.g. 7004, 7020) are employed for land transport and architectural applications whereas the Al-Zn-Mg-Cu alloys (e.g. 7075, 7050) provide the high strength aircraft alloys. The Cu gives rise to suitably sized and distributed precipitation but causes high quench sensitivity. Their hot work processing also has marked differences; the Cu-free alloys have good extrudability whereas the Cu-bearing alloys have low extrudability and are difficult in rolling as well. The behaviors of the two classes are described in terms of flow stresses and ductility over 300 - 500°C, along with constitutive contrasts. The ductility of the alloys with Cu is much reduced above 400°C by precipitation of a phase at the grain boundaries that can be avoided by suitable heating schedules. The high strength alloys are subject to de-lamination corrosion of sheared edges due to severely pancaked grains; this can be alleviated by holding between passes, in mid-rolling schedule. In torsion tests at 10-1 to 10 s-1/ 250 - 500°C, the stresses (ductilities) at 300°C/ 1s-1 and activation energy Q for 7004 were 118 MPa (2) and 262 kJ/mol. The 7075 was tested after several pretreatments: completely over-aged (softened): 107 MPa (5), Q=150 kJ/mol; whereas, solution and quick cooling to testing caused extraordinarily high peaks related to dynamic precipitation resulting in 160 MPa (1.2), Q=300 kJ/mol.

Jan 1, 2011

By S. C. Borah

Graphite, a mineral form of pure carbon, is one of the most versatile minerals in industry, because of its varying physical properties and characteristics. The mineral occurs naturally in the form of tubular crystals or microcrystalline earthy lumps, or it is disseminated in rocks, which have undergone intense metamorphism. India has a large deposition of graphite minerals out of which about 43% are found in Arunachal Pradesh. However, compared to the rest of the country, the North-East Region and particularly Arunachal Pradesh has not attracted attention till date for detail investigation for characterization, beneficiation, prospecting and/or exploitation of the mineral resources including graphite. Bulk graphite sample were collected from upper Subanshiri district of Arunachal Pradesh. Chemical analysis of the representative samples were carried out and found that 7.29%, 19.60% and 6.07% of fixed carbon (FC) is present in graphite sample collected from La-Lamdak, Bopi and Taliha, Arunachal Pradesh, respectively. Chemical analysis of the ash of the graphite sample shows presence of impurities such as silica, Al2O3, Fe2O3, Ca, Mg etc in the graphite sample which are also supported by XRD and SEM-EDX investigation. The graphite samples of Arunachal Pradesh are low grade and do not fulfill the market requirement for the industrial applications. Therefore, low-grade graphite is subjected to beneficiation for the upgradation of the graphite for industrial applications. We have adopted the dispersion?cum-settling technique for the beneficiation of the graphite sample collected from Arunachal Pradesh. The FC of 40.21% with 41.17% raw graphite recovery which is equivalent to 71.02% carbon recovery have been obtained by gravity separation technique using only distilled water without any chemical reagent in case of graphite sample collected from Bopi, Arunachal Pradesh. The graphite sample is upgraded up to 47.75% FC with 41.91% raw graphite recovery, which is equivalent to 85.85% carbon recovery with the pH adjustment at 9 with NaOH. Keywords: graphite, beneficiation, gravity separation, arunachal Pradesh

Sep 1, 2012

By Walter Murphy

For a number of years the Bureau of Mines has been studying the properties of crude petroleums produced in the United States and the Western Hemisphere. A number of reports have been published giving the analyses of crudes from the different fields and regions as made by the Bureau of Mines Hempel method of analysis.4 Several of these reports include analyses of crude oils from the Rocky Mountain region.5/ The search for new fields and new producing horizons in old fields in the Rocky Mountain region has been quite intensive during the last few years, and a number of discoveries have been made.

Jan 1, 1937

It is proposed to consider a new access, mining and hoisting system for underground deposits, as an alternative to the commonly used decline or vertical shaft access. The proposed system offers fundamental improvements in gathering of exploration data, reduction of capital expenditure and significant savings in mine operating costs. The cost reductions are achieved through:superior orebody definition by Supersucker winzing on ore prior to the commencement of capital development; considerable reduction of capital development in waste; full capitalisation on all benefits of a raisebored excavation; introduction of rubber tyred skip and rubber tyred Mine Rapid Response Vehicle; introduction of simplified ore handling system and reduction of underground mobile diesel fleet; and introduction of minimum maintenance shaft concept. The system is applicable to deposits ranging from shallow, low dip angle, narrow vein, high-grade to bigger, massive type vertical mineralisations accessed from the surface, preferably from the bottom of an open pit; it is also suitable as a down dip extension of an existing underground mine. The system is highly conducive to mine automation and emerging trend aimed to increase the ratio of mined metal/mineral to mined waste. It offers substantial reduction in diesel exhaust gas emissions to the mine atmosphere.

Jan 1, 2000

By M. B. Kime, A. T. Kaniki

"Grinding tests were conducted on an oxidized copper-cobalt ore using a pear-shaped ball mill. Twelve mono-sized ore fractions were prepared and wet ground batchwise. The mill was run for 0.5 to 30 min intervals. The shortest interval provided data more closely related to the breakage function (B) because less secondary breakage was hypothesized. Some selection function (S) and B parameters were determined. Remaining parameters were estimated using a population balance model simulator. To evaluate the kinetics model, an unsized ore sample was also milled. Predicted and measured particle size distributions (PSDs) agreed well, suggesting that S and B parameters can be used for continuous operation mass balances.RÉSUMÉ Des essais de broyage ont été menés sur un minerai oxydé de cuivre-cobalt à l’aide d’un broyeur à boulets piriforme. Douze fractions de minerai de dimension unique ont été préparés et broyés en voie humide en lots. Le broyeur était mis en route à des intervalles de 0,5 à 30 minutes. L’intervalle le plus court fournissait des données plus étroitement liées à la fonction d’abattage (B) car d’après l’hypothèse avancée, le besoin d’abattage secondaire était moindre. Certains paramètres de la fonction de sélection (S) et de B ont été déterminés ; les paramètres restants ont été estimés à l’aide d’un simulateur de modèle d’équilibre de population. Pour évaluer le modèle de cinétique, un échantillon de minerai non calibré a également été broyé. Les compositions granulométriques (PSD, de l’anglais particle size distributions) prévues et mesurées correspondaient bien, ce qui laisse penser que l’on peut se servir des paramètres S et B dans le cadre d’équilibrages massiques en fonctionnement continu. INTRODUCTIONSize reduction of solids is a very energy intensive and highly inefficient process. It consumes approximately 5% of the electricity produced worldwide (Rhodes, 1998), and more than 50% of the total energy used in mineral processing plants (Walkiewicz, Lindroth, & Clark, 1996). An increase in grinding efficiency can therefore result in significant reductions in operating costs. This often amounts to determining the optimal design configurations for milling an ore sample in a laboratory mill under standard conditions. Prior to optimizing the milling stage, the requirements for downstream processing in terms of particle size distribution (PSD) need to be understood because low liberation and overgrinding will lead to future problems. Once this is done, it is also important to clearly understand the breakage properties of the ore. The kinetics of size reduction in tumbling mills are often determined using two probabilistic functions: selection and breakage (Austin & Luckie, 1972). Knowledge of the selection and breakage functions also enables the prediction of the PSD for a given ore sample."

Jan 1, 2017

By Sergio N. Monteiro

From the leaves of the sisal plant (Agave sisilana) a relatively strong fiber can be extracted and is nowadays being investigated as a possible reinforcement for polymeric matrix composites. For this purpose, it is important to determine the critical length of the fiber with respect to the matrix to be reinforced. This has never been properly done for sisal fibers in polyester matrix. Therefore, this work characterized the critical length of sisal fibers, with different sizes, embedded in polyester capsules by means of pullout tests. The critical length obtained allowed the sisal fiber/polyester matrix interface shear stress to be calculated. The relevance of these values for polyester composites reinforcement with sisal fibers is discussed.

Jan 1, 2009

By V. T. Dow

This report describes construction details and methods used in driving the 5490 tunnel at the Kennecott Copper Corp, property, Bingham, Utah. The tunnel will provide railroad access to the world-famous open-pit copper mine at the projected 5490 level. This publication is one of a series prepared by the Bureau of Mines to depict mining operations and techniques in various mining districts in the United States. Utah Construction and Mining Go. (formerly Utah Construction Co.), contractor on the tunnel project, began work during September 1956 and completed the project in February 1959. The tunnel is 18 feet wide, 24 feet high, and about 18,000 feet long, It will accommodate a railroad locomotive on standard- gage track. With the exception of the last 1,700 feet, the tunnel is supported by steel sets embedded in concrete lining. The 1,700-fact segment of the tunnel is supported by timber sets that will eventually be removed as the pit is deepened.

Jan 1, 1962

The Century zinc-lead-silver deposit has a geological resource of 118 million tonnes averaging 10.2% zinc, 1.5% lead and 36 g/t silver. It lies approximately 250 km NNW of Mt Isa in NW Queensland, Australia, and is hosted by middle Proterozoic age siltstones and shales of the Lawn Hill Formation. Within the orebody, most mineralisation occurs selectively within black shale units as fine grained sphalerite and galena lamellae with minor pyrite and siderite. The black shale units are separated by weakly mineralised sideritic siltstone horizons. The deposit is unmetamorphosed and only weakly deformed, displaying excellent lateral stratigraphic and grade continuity.

Jan 1, 1995

By T. Lang

Clay sorbents from the North Bohemian Brown Coal Basin represent important but still some-what neglected accessory raw material. Submitted paper is concerned with relation between mineral structure, sorptive efficiency and reclamation exploitation of these rocks. Characters and localities of main clay sorbents from the North Bohemian Brown Coal Basin are shortly evaluated in an introduction. In next part, methodology of mineralogy survey for these accessory raw materials is stated, it is based on diffract analyse with D 5000 Siemens X-ray diffracto-meter. At the conclusion results are stated of mineralogy analyses from several clay sorbents. The determination of the zeolite and montmorillonite localities was accentuated. The paper presents also possibilities of practical clay sorbents utilization, especially by reclamation works.

Jan 1, 2014

By H. O. Hofman

(Canal Zone Meeting, November, 1910.) I. INTRODUCTION. IN a previous paper,1 The Behavior of Calcium Sulphate at Elevated Temperatures with Some Fluxes, we published the results of our investigation, into the behavior of calcium sul-phate in air; that, is, under oxidizing conditions. The results as a whole hold good for a neutral atmosphere, or one which has no chemical effect upon calcium sulphate. The present paper deals with the behavior of calcium sulphate under reducing conditions, the reducing-agents employed being carbon monoxide and carbon, and the changes the calcium sulphide formed undergoes when it is subjected to an oxidizing-roast. Technical literature deals very sparingly with the subject. The information furnished by the recent leading chemical manuals is general. Thus Dammer,2 Moissan,3 and Abbegg,4 quote Berthier as having reduced, in 1823, calcium sulphate with carbon, and Stammer as having done the same in 1851 with carbon monoxide; Gmelin Kraut 5 add Leplay and Laurent (1848) as third investigators. Metallurgical authorities confine their statements to the known fact of reduction by carbon. II. PREPARATION OF RAW MATERIALS. 1. Calcium Sulphate.-This salt was prepared in the same manner as described in our previous paper,6 and was found to be chemically pure. * Professor of Metallurgy, Massachusetts Institute of Technology. + Metallurgical Instructor, Imperial Technological Institute. 1 Trans, xxxix., 628 to 653 (1909). 2 Handbuch der anorganischen. Chemie, vol. ii., part 2, p. 309 (1894). 3 Traité de Chimic Minérale, 1904, vol. iii., p. 543. 4 Handbuch der anorganischen Chemie, vol. ii., part ii., p. 116 (1905). 5 Handbuch der anorganischen Chemie, vol. ii., part 2, p. 233 (1909). 6 Trans., xxxix., 630 (1909).

Nov 1, 1910

Vertical flow systems (SAPS, vertical flow wetlands) are increasingly used for passive treatment of mine drainage that is net acid. Data on 30 systems in eastern US show that well designed systems typically add about 40 g/d/m2 of alkalinity to influent net acid water. If they are designed with a conservative loading rate of 25 g/d/m2 and carefully constructed, they produce net alkaline water. Alkalinity added depends on influent acidity, Fe, pH, and retention time, and ranges widely, from 7 to 484 mg/L, so this is not a useful design criterion. Some waters may benefit from retention times longer than the conventional 12 - 16 hours, but the design must be partly based on cost-benefit considerations. Systems with fine limestone added to the compost layer perform better than average, perhaps to an alkalinity generation rate of 80 g/m2/d. A variety of problems are noted in the 30 systems and others reported in the literature. Systems with high influent Fe (> ~75 mg/L, varying with pH) tend to gradually decrease in flow rate because of precipitation and settling of Fe hydroxides on top of the compost layer. Some high-Fe systems precipitate Fe in the limestone layer, suggesting inadequate compost thickness, or short-circuiting through thin spots. Systems with Al exceeding about 10 mg/L tend to plug because of Al hydroxide precipitation in the limestone layer. Flushing only removes a small part of this precipitate, but can extend life. Some systems are ineffective because of failure of the inflow system. Some systems are uneconomic because they are oversized. A continuing program of inspection and maintenance is necessary for long-term performance.

Jan 1, 2003

By Jukka S. Sulanto

Outokumpu has applied its well -known copper Fl ash Smelling Process also for smelting su1phide lead . concentrates. The lead in the Flash Smelting Furnace slag is recovered by reducing the oxygen potential of the slag in an electric furnace by injecting reductant into the slag bath. A series of tests have been carried out in a 1000 KVA electric furnace? adjacent to a pilot Flash Smelting Furnace. The furnace has been fed continuously with molten Flash Furnace Slag. The feed rate has varied from 0.5 to 3.1 MTPH (0.55 - 3..4 STPH) depending on the feed rate and the quality of concentrate to the Flash Smelting Furnace. The inlet slag contained 15 to 40% of lead and the cleaned slag 1. 5 to 3. 0%. The lead recovery from sol id raw material was tested in the same continuous process by feeding lead calcine into the furnace. Feed rate was 0.7 to 0.95 MTPH (0.8 - 1.05 STPH) and the calcine contained 33 to 34% of Pb. Several reduction agents and procedures were tested. The process proved to be suitable for continuous recovery of lead from solid oxide raw materials.

Jan 1, 1990

By Michael Hood

An overview is given of some of the major mining research activities in Australia. Automation of mining equipment is not an objective in its own right. The objective is to improve the safety and the economic performance of mining operations. Automation can be a useful method for achieving this objective. There is a strong focus on mining equipment automation and related issues and specific examples of ongoing and recently completed automation projects are described.

May 1, 2002