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By Leandro de Almeida

As curvas limite de conformação (CLC) são utilizadas há mais de 50 anos. Propostas inicialmente para o desenvolvimento de produtos provenientes da indústria automobilística, em função das necessidades apresentadas pela indústria de estampagem elas são aplicadas atualmente de maneira geral na produção de inúmeros tipos de peças, oferecendo previsões de possíveis falhas e/ou defeitos durante as etapas do processo de estampagem. As CLC´s permitem prever o afinamento excessivo, enrugamento, estiramento e é claro, a fratura da peça. A raiz da curva limite de conformação (CLC0) é considerada como a mínima deformação obtida pela curva, ou seja, a obtenção de deformações superiores pode levar a peça a falha. As ligas de latão compostas por cobre e zinco, são utilizadas em inúmeras aplicações que necessitam de excelente estampabilidade, como o repuxo profundo, objetivado na fabricação de projéteis. Desta forma, torna-se interessante o entendimento da CLC ou CLC0 para liga de latão em estudo. A obtenção da CLC0 através de ensaios de tração uniaxial no plano da chapa pode ser realizada de acordo com corpos de prova de formatos específicos, como os propostos por Björklund e Nilsson (2014), IRSID (1975) e Wagoner (1980 e 1981). Concluiu-se que o corpo de prova proposto pelo IRSID (1975) é o que melhor se apresentou na determinação das deformações e1 x e2 e com rompimentos dos corpos de prova na região central.

Oct 30, 2017

By N. S. Wagner

The production of lightweight aggregates in Oregon is a new industry, and, like all new enterprises, it is suffering from growing pains characterized by numerous, small operations some of which flourish for a short time and then cease altogether. Normally all industrial mineral products are produced in a highly competitive atmosphere. At the present time this condition does not exist to a very marked degree in the state because as yet producers have not saturated the constantly expanding market. This paper has been prepared with the intention of outlining very briefly the current status of the various products now being used as lightweight aggregates in Oregon. The present picture will surely change, perhaps quite radically within even a short space of time.

Jan 1, 1949

By Sergio Neves Monteiro

The efficiency by which an applied load is transmitted through the composite structure depends on the strength of the interface between the matrix and the second phase. In fiber reinforced composites, the interfacial shear stress plays a major role in the composite capacity to support the applied load. This interfacial stress can be obtained by means of pullout tests using the fiber embedded to a certain length in a socket of the matrix material. In the present work, pullout tests were performed to evaluate the interfacial shear stress of ramie, a relatively strong natural fiber, reinforcing polyester matrix composites. The general result permitted to calculate a critical length for the ramie fiber embedded in polyester resin. From this critical length, the value of the interfacial shear stress was calculated. An interpretation of this result together with SEM observation displayed a relatively weak bond between the ramie fiber and the polyester matrix.

Jan 1, 2010

By S. P. Sandoval

The U.S. Bureau of Mines investigated the separation of aluminum from copper dump leaching liquors using a supported liquid membrane. Aluminum was selectively transported through porous polypropylene impregnated with di (2-ethylhexyl) phosphoric acid in an aliphatic diluent. The effects of variables, such as solution composition, temperature, and extractant concentration, were measured with a three-level fractional factorial experimental design. Experimental results were used to derive equations for predicting transport rates for aluminum, iron, and copper. The major variables influencing aluminum transport were solution temperature, feed solution pH, aluminum concentration in the feed solution, and extractant concentration. Copper and iron transport rates were almost zero when aluminum transport rates were high. Measured aluminum transport rates under the best conditions of 55° C, pH 3.0, 16 g/L A13+, and 65 pct extractant solution confIrmed the predicted value of 210 f.'g/(cm2.h). Transport rates for iron and copper were less than 5 ug/(cm2.h) under these conditions. Aluminum was recovered from the stripping solutions by sparging with gaseous hydrogen chloride to crystallize aluminum chloride hexahydrate, which was calcined to alumina. Sparging crystallization regenerated the stripping acid for recycle.

Jan 1, 1989

The operations management system at Olympic Dam has evolved over a two-year period to the state described in this paper. This evolution has been driven largely by the requirements of the recent expansion of the Olympic Dam operation from three to nine million tonnes of ore per year. Such a change process demands an holistic approach to mine management and several techniques have been employed including XPAC, Mine Works Planner as well as a basic philosophy of æjust-in-timeÆ completion. The philosophies, software and tracking mechanisms for managing a large tonnage operation are described, outlining a fully integrated scheduling system from shift to shift detailed activity planning to a 20 year production plan. Moreover, the vision of production exceeding the current limit of nine million tonnes means that there are to be further developments to this state-of-the-art system in use at the Olympic Dam mine.

Jan 1, 2000

The subject of my paper is one which, I am certain, has exercised the mind of every man on whom depends the safe and economical conduct of mining operations; particularly in this district where the enormous size of the ore body has necessitated the mine workings assuming a scale that was hitherto unknown in the history of Australian mining. I, therefore, approach the subject with the feeling that I am displaying considerable t.emerity, knowing as I do that the subject has engaged the earnest attention and thought of everybody immediately concerned in the extraction of the ore of this district, and particularly of the Broken Hill lode.I think I shall not be contradicted in asserting that a very large proportion of eur accidents are distinctly traiceable to inexperience on the part of the miner, and records at the mines and verdicts of coroners' juries in many instances uphold this assertion by showing that the accident under notice was the direct result of lack of knowledge of the conditions of the work, or, at any rate, of an error of judgment hardly conceivable in the experienced miner. That this assertion is correct may also be proved by visiting any of the mines of the district.To the experienced eye it will be evident at once that a very large number are not in way skilful in the use of their tools and, therefore, lack the experience which of necessity must be coincident with the acquirement of skill. Now in making this' assertion, I do not intend to be too sweeping...

Jan 1, 1903

By C. R. Julian

THE large pyrites ore-bodies, the underground mining of which is to be described, are situated at Rio Tinto in the Province of Huelva in Southern Spain. The situation of the different ore-bodies with relation to one another is shown in Figure 1. It will be seen on the plan that the strike of the ore-bodies is approximately east and west. The geology of the district has been very fully described by Dr. D. Williams (1), so that for the purposes of this paper it will be sufficient to give briefly the salient features o each of the two larger ore-bodies which are being mined by underground methods at the present time. (a) San Dionisio.-This ore-body is the largest single deposit in Rio Tinto, having on its upper levels a length of 3,500 ft. On the upper levels the average width is approximately 200ft. but in places on the lower levels there is a width of 900ft. of un broken pyrites. Diamond-drill holes, without running out of ore, show the ore-body to persist to a depth of at least 1,600 ft. The ore-body in the upper part lies between slate and porphyry walls, but in depth is enclosed in porphyry walls. (b) South Lode.-Faulting is considered to be responsible for the break in the solid ore between South Lode and San Dionisio. On the upper levels, the South Lode ore-body has an unbroken length of 4,000 ft. The massive pyrites has a maximum width of 300ft. and an average of about 100 ft. Ore has been proved to a depth of 1,000 ft., at which depth the ore-body is much reduced both in length and breadth. This ore-body, to the depth at which it has been proved, lies entirely between slate and porphyry walls. The South Lode and the San Dionisio ore-bodies are mined both by open-cast and by underground methods. There is evidence that these mines have been exploited intermittently during the last 3,000 years; but, as is to be expected, no records are available of the tonnage mined prior to the time of purchase by the present company.

Jan 1, 1940

By B E. Hall, J Poniewierski, A J. Hills

Following a review of life-of-asset work at MMG’s Rosebery mine in which a proposal to increase production from 0.8 Mt/a to 1.2 Mt/a was mooted, questions were raised as to the seemingly arbitrary reasoning for the production increase. They included: Did the proposal actually add value? Was the production rate from the mine sustainable? Was it the best identifiable value-adding configuration?A multiple scenario analysis study commenced to model how various cut-off grade values against mill throughput, along with associated capital expenditure, would impact on the potential value of the operation. This was carried out utilising the ‘hill of value’ approach promoted by AMC Consultants.The traditional approach to these studies uses a constant cut-off value (NSR – net smelter return) for the whole mine analysis. This was thought to potentially introduce a large amount of variability to the model as different ore types were thought to have different processing costs and different underground lenses were thought to have different mining costs. With the aim of developing a consistent value measure that would be comparable between the lenses, an alternative measure was suggested for all ore block values in this model, irrespective of lens location.The new measure used was a mine variable value (MVV). This allowed for the variable factors of final metal concentrate production to be removed from the ore value. From a mining point this was the haulage distance from ore source to run-of-mine (ROM). For the mill it was the amount of reagents required, varying based on grade together with the amount of power required for crushing, grinding and tailings handling.From the initial run of the model, preliminary results lead to a conclusion of increased value being gained by either increasing cut-off grade or increased mill throughput rate. The validity of the result was tested using alternative price scenarios, which although changed the absolute value achieved did not significantly change the identified value-adding strategies. The realisation of these value increases identified are however contingent on higher sustainable development rates being able to be achieved mine-wide, higher backfilling rates being able to be achieved and overcoming recognised ventilation constraints. Further detailed studies are being put in place to identify the practicality of overcoming these recognised constraints and achieving the higher-value strategies identified.The ongoing objective of the hill of value model built is to keep the model alive as a life-of-asset planning tool and to continue refining the foundation data, such that various mining strategies can be analysed with increased confidence.CITATION:Hills, A J, Hall, B E and Poniewierski, J, 2014. Mining scenario analysis and mine variable value, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 111–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By M. L. Cao

In this study, a montmorillonite organo-intercalation compound (MOIC) was synthesized by using a Na-modified bentonite (NaB) as a matrix and hexadecyltrimethylammonium (HDTMA) bromide as an intercalating reagent under microwave irradiation. The synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), organic carbon content measurement, and adsorption density determination. The results show that, at 10% suspension concentration and 10 minutes irradiation in a 130-W microwave oven, the basal spacing d(001) of the synthesized MOIC increases to 2.209 nm from the original 1.218 nm of NaB. The MOIC has much higher adsorptive densities to nitrobenzene and aniline from aqueous solution than the NaB. The adsorption isotherm of nitrobenzene on the MOIC is linear, and the adsorption is mainly the result of nitrobenzene?s preferred partition in MOIC over aqueous solution due to MOIC?s hydrophobicity. The adsorption isotherm of aniline on MOIC follows the Freundlich equation and the increased adsorption is not only the result of aniline?s preferred partition in MOIC over aqueous solution but also that of the MOIC?s surface adsorptions.

Jan 1, 2014

By Russell Clough

The Pacheco Pumping Plant is situated on the west end of San Luis Reservoir in western Merced County, California. It is designed to draw water from the reservoir and pump it into a 3,500,000 gallon regulating tank. The water then flows entirely by gravity to the Coyote Pump Station in Morgan Hill, a distance of 40 miles, where it is pumped into Anderson Reservoir. This water is used to recharge the depleted groundwater table in the Santa Clara Valley. Eventually, some of the water will be diverted to Hollister in San Benito County and to Watsonville and Santa Cruz in Santa Cruz County. The owner is the United States Bureau of Reclamation. The underground work consisted of a fifteen foot finished diameter surge shaft 250 feet deep to the crown of the pump chamber; a twenty foot finished diameter pump chamber which declined from the shaft at 14.2% for ninety feet and then ran horizontally for 180 feet; and twelve each five foot diameter steel lined intake shafts 240 feet deep which intersect the pump chamber in the horizontal section. (Figure 1) Upon completion of the pump chamber, the contractor had to dewater the existing tunnel under the reservoir, excavate the remaining fifteen foot plug, and concrete the transition. The low bidder for this contract was Underground - Continental-Heller at 414,456,000. Excavation of the open cut for the pumping plant and surge shaft began on April 14, 1983. This was performed using a Koehring 1066D backhoe, dozer, trucks, and two Cat 631 scrapers. The excavation was started at the surge shaft so that the grouting could begin

Jan 1, 1985

By C. P. Crawford

In the current issue of Link-Belt News is this quotation: "Advancing waves of other people's progress sweep over the unchanging man and wash him out." As we look over the industrial world today we are struck by the many waves which are sweeping over backward industries. Mergers are being consummated in all lines of endeavor. General Motors are making radios and the Bendix Brake Company are making airplanes. Railroads which twenty years ago were called to account by the Federal Government for their efforts to form combinations are today being ordered to combine. But what is of immediate concern to the coal industry is the fact that there is now in existence or in project a total of 3,641 miles of pipe lines to carry natural gas to most of the country's industrial centers. This is the wave of progress which is sweeping toward you and me. If we are to grasp the significance of these many changes, we must widen our vision so that we may learn some- thing from 'the other fellow's experience. The first lesson is that cost of production alone is not a measure of profit. It is an interesting fact that the production of an article represents a definite loss until that article has been sold for a price in excess of its total cost, and the money is in the hands of the producer. If this is true, then the selling price is more important than the production cost.

Jan 1, 1930

By Gabriel S. Esterhuizen, Jarek Jakubec

In 2000, Laubscher’s Mining Rock Mass Rating (MRMR) classification system was updated and published. The new system brought a few fundamental changes that were in direct response to the challenges and problems encountered when applying the classification system in the mining environment, specifically caving operations. The fundamental changes introduced into the MRMR system in 2000 were the abandonment of the Rock Quality Designation (RQD) as an input parameter, accounting for healed and cemented joints, and the concept of rock block strength. The objective of this paper is not to discuss the role and usefulness of classification systems; the fact that classification systems are widely used in every stage of mining projects speaks for itself. This paper discusses some of the experiences gained with the MRMR 2000 system in various mining projects and shows how the changes to the system have resulted in improved assessment of rock mass conditions. Issues related to core logging for rock mass assessment are also presented.

Jan 5, 2007

By J. D. Sargent

Selenium might be described as a paradoxical element, being either a metal or a nonmetal, a conductor or nonconductor, amorphous or crystalline, colorant or decolorant, and a hydrogenator or dehydrogenator. Selenium was discovered in 1817 by the Swedish chemist, Berzelius, while studying flue dust from the lead chambers of the sulfuric acid works at Gripsholm, Sweden, The ordinary stable form of selenium is a crystalline, grayish solid with semi-metallic luster. It melts at 217° C., boils at 684.8° C., and has a density of 4.79.

Jan 1, 1955

By Myles E. Robinson

Significant changes in the markets for coal have taken place since World War II, As used in this study the term ?coal? will refer to bituminous coal, The anthracite industry in size, characteristics, and problems differs materially from the bituminous coal industry, These changes have both influenced and been influenced by the mechanization of mines, and by decreased distribution costs, especially in transportation. It is the purpose of this paper to examine these post-war changes, to assess their impact upon the production and distribution of coal, and to explore future market developments in the light of past and present trends and relationships. The layman lacks adequate informatian on the production, demand, and distribution of coal. There are two reasons for this. First, there is a relative lack of statistics coveting the industry, Coal operators and distributors are not required to file with any government agency the type of much more complete statistics filed by the railroads and public utilities with national and State agencies. The Bureau of Mines assembles much useful information on the coal industry, but several areas, including that of investment and finance, have no central depository which can be used to keep the public informed of the nature and extent of the industry and its problems.

Jan 1, 1964

By Albert L. Toenges, Theodore R. Jolley

"INTRODUCTION The construction of frame houses (fig. 1) in recent years instead of the conventional sod hut (igloo) (fig. 2) by the Eskimos in the villages along the Arctic Ocean has increased the demand for fuel in these villages. The frame houses, which are not insulated against extreme cold and are difficult to heat, are equipped with Goal stoves. The well-insulated sod huts were heated comfortably with whale-oil stoves. In some years whaling is Door, consequently there is a demand for solid fuel.The Eskimo villages usually are on the sand spits at the mouths of rivers and points of land near the best fishing and hunting grounds. These narrow necks of land usually are sand bars that are not underlain with coal, and coal must be transported to the villages. Lack of development of coal deposits in the Arctic has made it necessary to import coal from the States, generally from 'Washington, to supply these villages. This coal is imported by boat and is received once a year. Its cost is, high, and development of coal deposits in the Arctic to supply these native villages should result in a considerable saving to the Government-operated schools and hospitals as well as to the natives.Early traders attempted to establish coaling stations in the Arctic, and the Eskimos generally know where the coal deposits are situated. A. reconnaissance of a number of deposits in the Arctic was made in the summer of 1946 by engineers of the Coal Division, Fuels and Explosives Branch, Bureau of Mines, and this report describes the areas investigated and suggests plans for the development of some of these deposits."

Dec 1, 1947

By JOE SIERAKOSKI, W. R. Hardwick

This paper , which describes mining methods and practices at the Johnson Camp copper -zinc mine , Coronado Copper & Zinc Co. , Cochise County , Ariz . , is one of a series being prepared by the Bureau of Mines on mining methods , practices , and costs in various mining districts of the United States . Johnson Camp is in the eastern foothills of the Little Dragoon Mountains in secs . 23 , 24 , 25 , and 26 , T. 15 S. , R. 22 E. ( fig . 1 ) . The mining property is in the low, rolling foothills at an altitude of slightly over 5,000 feet above sea level ( fig . 2 ) . The area is covered with scattered grass and small desert shrubs . The climate is mild , with hot summers and mild winters . The average annual precipitation is about 12 inches . The nearest surface water is the San Pedro River , some 12 miles west of the mine . The property is owned by the Coronado Copper & Zinc Co. , Los Angeles , Calif . This report gives a brief history of the property , describes the general geology of the area and of the ore deposits , outlines the methods of prospecting and exploration , and gives the methods of sampling and of estimating ore reserves . Development and stoping methods are explained . Underground transportation , ventilation , mine drainage , and safety measures also are described . The last section gives a brief description of the milling practice .

Jun 1, 1957

By Denise C. R. Espinosa

Rechargeable lithium batteries are one of the most promISIng technology in battery development. Although Li ion batteries have been used as an alternative to the more polluting and less performing Ni-Cd batteries, Li ion batteries have limited life and their disposal is uncertain. It is imperative that valuables from wastes, such as lithium, should be recovered. The main objective of the present work was to characterize secondary lithium batteries for cellular phones. This was done using unit operations of mining processing, x-ray diffraction (XRD), chemical analyses and the rmogravimetric analysis (TG). The unit operations were hammer mill grinding, knife mill grinding, size separation and magnetic separation. After the hammer grinding process, the plastic cases were almost intact, however, they have released the cylindrical lithium batteries themselves and these parts correspond to 70% of the total battery weight.

Jan 1, 2001

By Shenghua Yin, Xun Chen, Rongfu Yan, Zepeng Yan, Wei Chen

The application of cemented paste backfill (CPB) with alkali-activated slag and phosphogypsum (ASP) can contribute to the sustainable development of the mining industry. The effects of PG content, NaOH content, solid content, and waste rock-rod milling sand (W/R) ratio on workability, unconfined compressive strength (UCS), and setting time of ASP-CPB were investigated in this paper. The results showed that the workability of ASP-CPB decreased with PG content and NaOH content. Compared to OPC-CPB, ASP-CPB exhibited better workability and higher long-term (7 days and 28 days) strength at predetermined backfill formulations and curing times. The mid-term strength of ASP-CPB first increased and then decreased with PG content, while the short-term strength (3 days) decreased gradually due to the influence of soluble acidic impurities. Excessive NaOH will harm the strength of ASP-CPB, possibly due to the swelling effect of the reaction products (ettringite and sulfate). Strength and setting time increased and decreased with solid contents, respectively. Moreover, the compactness of the mixture has an important effect on strength and workability. The workability and strength of ASP-CPB reached the minimum and maximum values at a W/R ratio of 5:5, respectively. Pollutant index detection indicated that most of the pollutants in ASP-CPB leachate met the discharge standard, which proved that ASP-CPB is an effective method to recover PG. The results of the research will provide theoretical guidance for the efficient recovery of PG resources and support the achievement of safe, clean, and efficient mining.

Nov 17, 2023

Jan 1, 1970

By Herty, C. H.

Three distinct processes take place during the conversion of iron ore to steel. First: the raw ore is reduced to metallic iron in the blast furnace and during this reduction certain constituents are dissolved in the iron, either through the solution of a solid into a liquid phase, as in the case of carbon, or by reduction of an oxide existing in the slag to the metallic element of that oxide, with subsequent solution of the metallic element in the iron. Thus by the process of solution and reduction, a pig iron results which contains about 4 per cent carbon, 1 per cent silicon, 1 to 2 per cent manganese, 0.1 to 0.4 per cent phosphorus, and 0.03 to 0.10 per cent sulfur. To obtain a sufficient yield of iron from the ore it is necessary that the reducing process be carried as far as possible, with the result that the impurities mentioned accompany the reduced iron. Second: to convert this iron into steel it is necessary to oxidize a part of the iron in eliminating the impurities to the extent desired for the particular product being made. In eliminating these impurities by oxidation a certain amount of iron oxide (FeO) dissolves in the steel. This dissolved FeO reacts with the metalloids, except sulfur, and to eliminate them to the desired extent it is necessary to leave a considerable amount of FeO in the metal. The reaction of iron oxide with silicon, manganese, and phosphorus results in the formation of the oxides of these elements. The oxides enter the slag and the extent of elimination of the elements depends on certain equilibria between the slag and the metal. The reaction of FeO with carbon results in the formation of the gases CO and CO, which, after saturating the metal, pass into the furnace gases. Third: after the iron has been purified to the desired extent as far as the elements listed are concerned, it is necessary to deoxidize the bath to remove the FeO, which is the vital factor in gas formation as the steel solidifies.

Jan 1, 1957