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By José Gonçalves Pacheco Júnior

A caldeira de recuperação de calor de gás de coqueria, denominada caldeira 22, foi submetida à inspeção e reparo conforme os dispostos na NR13 em função de falhas repetitivas que levaram a uma perda repentina de nível de água no tubulão de vapor da Caldeira. O equipamento foi inspecionado levando em consideração técnicas qualitativas e quantitativas de inspeção de equipamento, o que gerou a possibilidade de especificar o reparo. Através do reparo foi possível liberar a caldeira para produção de vapor. Com os dados da inspeção foi realizada uma análise de falha por um grupo multidisciplinar com objetivo de determinar a causa raiz dos modos de falhas detectados durante a inspeção do equipamento: espessura de isolamento térmico inadequado e operação inadequada após detecção de vazamento de água no equipamento. Ações de controle foram definidas e replicadas para as outras caldeiras dessa coqueria. Assim sendo a caldeira 22 está operando em segurança conforme especificação do projeto e com os reparos preventivos já determinados.

Oct 30, 2017

AMONG the features that make Inspiration of outstanding A interest, particularly to the engineer, is the fact that at various times it has used, as a major method of production, three more or less distinct methods of mining and three distinct methods of treating its ores. The following chronology is of interest : Major Mining Methods: 1915-194 7 Underground block-caving, exclusively 1948-1952 Underground block-caving and opencut mining 1953-1954 Underground block-caving, opencut mining, and "glory-hole caved-block transfer" mining 1955 on Opencut mining and "glory-hole caved-block transfer" mining. Major Ore Treatment Methods: 1915-1925 Flotation concentration exclusively 1926-1930 Flotation concentration and ferric sulphate leaching 1931-1955 Ferric sulphate leaching (the so-called "Dual Process" was used for eleven months in 1937 when demand for copper was phenomenal; and the "leach-float" process was used for 24 months in 1942-44 as an expedient to help meet war demands for copper). 1956 on "Dual Process" combining a sulphuric acid leach followed by fine grinding and flotation of the residue from the leaching vats.

Jan 1, 1957

AMONG the fellow prospectors of Black Jack Newman, locator of the claims that became the Miami mine, were J. D. Coplen and Bud Woodson. Woodson was in the district when the Bloody Tanks Indian massacre occurred, near the present town of Miami. He was a prospector long before Jack Newman worked in a mine, and for years he had done assessment work on some of the claims that Coplen acquired for his Inspiration company. Woodson recalls that a Scotch geologist from Morenci once visited his claims; and that the geologist tried to get the Phelps Dodge company interested in the property, but without success. Coplen interested some people in Kansas City in his claims that lay west of Newman's. He induced them to organize the Inspiration Mining Co., and by 1908 this company controlled 23 claims, which had been prospected in desultory fashion by a series of adits. One of these, near the Keystone property, encountered some lean copper-bearing rock, but later development failed to disclose any substantial quantity of ore at this particular point. Coplen, as general manager, in September, 1908, was negotiating with several exploration companies which at the time were on the lookout for low-grade copper properties. As a matter of fact, when J. Parke Channing visited Globe, in December, 1906, F. C. Alsdorf showed him the Inspiration claims as well as Newman's. Channing evinced little interest in an option on Inspiration because he could get so much better terms from Newman. He decided to concentrate his work on the Newman claims, with the idea that if he were successful in developing ore, he could later get Inspiration on terms at least equally good. Subsequently, the United States Smelting & Refining Co., which has since added "Mining" to its corporate name, took an option on Inspiration.

Jan 1, 1933

The Inspiration ore body was discovered in 1904, but a 50 -ton mill which was installed to treat the disseminated copper ore promptly failed. The original Inspiration Company then gave way to another, backed by W. B. Thompson, which found 40 million tons of ore. Control then passed to Anaconda and Dr. Louis Ricketts took charge as consulting engineer. He abandoned the mill which had been partially built (to the horror of the stockholders, according to Ira Joralemon) and spent a year and a million dollars experimenting with flotation. The first large copper flotation plant was then built and recovered 50% more copper than had previous gravity mills. It, of course, was highly successful and became the forerunner of modern flotation plants. Inspiration is distinctive as the first fully integrated copper operation in the United States. Three open pits supply sulfide ore to the concentrator and mixed oxide and sulfide ore to a vat leaching and electrowinning operation with leached ore also being sent to the concentrator. In addition, dump leaching supplies pregnant solution for scrap iron precipitation. Inspiration has recently constructed an electric furnace smelter and also operates a continuous casting and rod plant. The new primary 54 in. by 74 in. crusher was completed in May of 1972 and replaced an older unit which was in the way of the open pit development. It is of an unusual circular silo design, which permits dumping 0 from two positions at 90 from each other. One dumping position is in line with the spider, while the other one is at right angles to it. A box girder splitter bar hung from the dump pocket slopes downward from the second dump point, across the spider cap, and rests on the pocket bottom. This splitter was not installed to protect the spider but was to aid in distributing wet ore being dumped from that position to both sides of the spider. Any large amount of wet ore delivered to one side of the spider would pack in the crusher cavity. The round front wall of the 18 ft (5.5 m) deep pocket is unlined except for light steel protection at the top, while the straight back wall is lined with vertically positioned railroad rails. Water for dust suppression is sprayed into the pocket through a cluster of 3/8 in. (9.5 mm) nozzles at the back of the pocket. About 5 gpm (19 lpm) of water are mixed with 90 psi (620 kPa) air upstream of the nozzles to produce a fog which is effective in dust control. The 54 in. Allis -Chalmers gyratory is placed mostly within one quadrant of the circular enclosure to permit placement of the apron feeder on the lowest level in the proper position to transfer crushed ore to the

Jan 1, 1978

By H. C., Weed

THE Inspiration Consolidated Copper Co., located in the Globe-Miami district at Inspiration, Ariz., became a producer of copper in 1915. From 1915 until 1948, 116,278,000 tons of ore were produced from underground workings by the block-caving system of mining. In April 1948, open-pit ore production from portions of the ore body was started and earlier plans for block-caving in these areas were abandoned. The change was due to economic conditions. Prior to the war years Inspiration's costs of mining by block-caving methods were comparable to, or even below, the costs of some open-pit operations. By the end of the war these conditions were completely changed. Underground costs had risen steadily for labor and supplies. Difficulty was being experienced in finding competent underground men and underground development was almost hopelessly behind schedule. On the other hand, open-pit costs had been sharply reduced through the development of modern earth-moving machinery and plenty of labor was available for surface work.

Jan 1, 1950

By H. C. Weed

THE Inspiration Consolidated Copper Co., located in the Globe-Miami district at Inspiration, Ariz., became a producer of copper in 1915. From 1915 until 1948, 116,278,000 tons of ore were produced from underground workings by the block-caving system of mining. In April 1948, open-pit ore production from portions of the ore body was started and earlier plans for block-caving in these areas were abandoned. The change was due to economic conditions.

Jan 8, 1950

By Anselmo Monteiro Ilkiu

No presente trabalho será apresentado um modelo matemático para a análise da instabilidade plástica de um cilindro de parede fina sujeita a pressão interna, considerando o material com anisotropia normal R no estado plano de tensões. As equações foram obtidas, com base nas teorias elásticas e plásticas, considerando o critério de escoamento de von Mises no estado plano de tensões em termos da anisotropia normal, e de acordo com os trabalhos realizados por Johnson & Mellor [1], Chakrabarty [2] e Al-Qureshi [3].

Aug 16, 2017

By B Abbasi

It is well known that most roof falls in coal mines typically occur at and around intersections. Room-and-pillar and longwall coal mining systems typically develop 3-way and 4-way intersections. This research develops an improved scientific understanding of stress distribution and associated instability behaviour around 3-way and 4-way coal mine intersections through 3-D numerical modelling and limited field observations. Numerical analyses were performed for an Illinois longwall coal mine to identify factors that influence intersection stability. The stability of immediate roof, floor strata, and coal ribs at and around intersections are considered with pre-mining regional horizontal stress. Non-linear failure analyses used the Hoek-Brown failure criterion for rock mass. Progressive failure zones in and around intersections were developed. For a typical 4-way intersection, pillar corners across the intersection fail first and lead to progressive failure of the immediate roof and floor layers. The mechanism of failure is similar for a 3-way intersection but the shape and extension of failed zones differ. For the 3-way intersection, the effect of off-set distance was analysed. It was found that minimum off-set distance of about 10 m (centre to centre distance between two 3-way intersections) was required to minimize interaction between two intersections. A simple instrumentation program monitor ground movements around intersections. These data were used to design the intersection geometry that is now being practiced by the mine. CITATION:Abbasi, B and Chugh, Y P, 2018. Instability analysis in three-way and four-way coal mine intersections, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 345–359 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By D. L. Ealy

At the Beckley Mine in southern West Virginia, forecasting unstable roof conditions in advance of mining is accomplished by using a rating system that combines historical information on mine roof failures with known mine geology. Failure frequency rates are derived for each category of roof rock composition, unit thickness, structure, and extraction ratio. In this manner, known geological environments are rated according to instability based on actual experience. Drill hole control and geological interpretation provide the basis for forecasting unstable conditions beyond working faces. The forecasting technique has assisted mine management in reducing fall frequencies by 80% over the past two years compared to the first five years of operation. This reduction in fall frequency was accomplished by modifying the plan of advancing sections to minimize mining exposure to unstable roof conditions.

Jan 1, 1980

By R. E. Mazurak, E. L. Ealy

At the Beckley mine in southern West Virginia, forecasting unstable roof conditions in advance of mining is accomplished by wing a rating system that combines historical information on mine roof failures with known mine geology. Failure frequency rates are derived for each category of roof rock composition, unit thickness, structure, and extraction ratio. In this manner, known geological environments are rated according to instability based on actual experience. Drill hole control and geological interpretation provide the basis for forecasting unstable conditions beyond working faces. The forecasting technique has assisted mine management in reducing fall frequencies by 80% over the past two years compared to the first five years of operation. This reduction in fall frequency was accomplished by modifying the plan of advancing sections to minimize mining exposure to unstable roof conditions.

Jan 1, 1983

By W. A. Niepelt, F. A. Locher

Flow in steep cascades may lead to the occurrence of a nearly periodic train of waves known as slug flow. This, in turn, may result in overtopping of the channel walls and problems with energy dissipation in receiving sumps. Experimental data from an operating facility was used to extend clear water technology for predicting the occurrence of slug flow to conditions with slurry flows. A design methodology and a design chart to determine the region of steady flows is presented that will permit the design engineer to avoid slug flow in cascade systems for conveyance of slurries.

Jan 1, 1990

By Panshi Xie, Yingyi Zhang, JIANJIE DUAN, Shenghu Luo

A multi-layer gangue roof of a steeply dipping coal seam with a large mining height face area was analyzed using physical simulation, numerical simulation, theoretical analysis, and field measurement methods to evaluate the roof deformation and the mechanisms associated with the instability of the hard gangue and soft coal interlayer. The results indicated that the first weighting step of the multi-gangue roof was larger than that of a non-gangue roof, but periodic weighting steps were similar. The overburden collapse height was lower in the multi-gangue roof than in the non-gangue roof due to the buffering and supporting function of the collapsed gangue. Moreover, the failure of the coal interlayer was the key factor in the collapse of the multi-layer gangue. A mechanical model was established for the hard gangue and soft coal interlayer based on a revised Prandtl squeezing theory. The limited load of the interlayer and maximum resistance of the shield support was thusmodeled. The maximum resistance of the support increased with the dip angle of the seam and burial depth. It also increased with the interlayer thickness at thicknesses below 2.75 m. It reached a peak when the interlayer thickness was between 2.75 and 3 m and exhibited a decreasing trend when the thickness was greater than 3 m. The results were confirmed using physical simulation and a field test. Certain measures were proposed to control the stability of the gangue roof, including zoning control of the mining height and resistance and advancing the support while maintaining roof contact, thus ensuring the integrity of the support and surrounding rock system.

Jun 30, 2020

By Panshi Xie, Yingyi Zhang, JIANJIE DUAN, Shenghu Luo

The most important safety aspect associated with great mining height in steeply dipping coal seam mining is the stability and control of the roof. When soft coal and hard gangue make up the immediate roof of a working face, the soft-coal interlayer plays a significant role in gangue damage and can cause problems such as roof collapse in front of the support, collapse of partial area supports and other problems that can affect the stability of the supports and the surrounding rock system. This study found that the first weighting step of a multigangue roof is larger than that of a nongangue roof, but periodic weighting steps are similar. The overburden collapse height is lower in a multigangue roof than in a nongangue roof due to the buffering and supporting function of the collapsed gangue. Failure of the coal interlayer is the key factor in the collapse of multilayer gangue. The limited load of the interlayer and maximum resistance of the support is concluded by the hard gangue and soft coal interlayer mechanical model. The maximum resistance of the support increased with the dip angle of the seam and burial depth. Certain measures are proposed to control the stability of the gangue roof, including zoning control of the mining height and resistance and advancing the support while maintaining roof contact, thus ensuring the integrity of the support and surrounding rock system.

By A. Golder, S. P. Dandapat, I. Roy

One of the consequences of large-scale opencast mining for coal is the disposal of an enormous volume of overburden material that needs to be removed. With the enlargement of opencast mines and associated high stripping ratios, the volume of overburden extraction is rising. Overburden from the initial mine cut has to be necessarily dumped outside the mining area until enough void is created inside the mine for back-filling operations. The quantity of overburden placed outside the mining area normally varies from 10% to 30% of the total overburden removal. The stability of these dumps placed outside the mining area is of prime importance from the point of view of smooth operations of the mines and safety of persons in and around the dumping area. Owing to increasing pressure on land use, mine operators do not have any other option other than to place the waste dumps very near to the surface edge of the pit, which may lead to failure of the topsoil benches of the working pit. This study identified major controlling parameters that influence a stable but economic combination of height and slope angle of external dumps located close to the edge of an open coal pit.

Nov 27, 2024

By John E. Udd

Introduction During the very long period in which man has mined minerals from the crust of the earth, falls of ground and collapes of under- ground workings have been the causes of a significant part of those accidents which have resulted in either death or in injury. At present, because of improvements in the approaches to the design of underground structures, in equipment, and in attitudes towards accident prevention, the proportion of accidents due to instability of rock is probably far less than it was historically. Nonetheless, in spite of the many advances which have been made, instabilities still account for about one-quarter of all fatalities, and one-tenth of all of the injuries, in the minerals industry. The means must be found whereby both the numbers of accidents and the accident rates due to falls of ground can be reduced to the lowest levels possible. At the outset it should be stated that, short of suspension of all mining activity, it will probably never be possible for us to eliminate accidents completely. Most human enterprise involves unknowns and risks, and mining is no exception. A certain number of accidents, then, must be viewed as the inevitable consequence of our attempting to work with unknowns and to make decisions that involve uncertainties. However, in retrospect, many instabilities can be attributed to factors which could have been within our control. The preventable accident must be eliminated. It should be our goal that we make every effort to direct our skills and technology to the creation of a safer working environment and should be constantly striving to

Jan 1, 1983

By Danielle Gonçalves Campos

Com o ensaio de RDI (Índice de Degradação sob Redução), pode-se determinar a geração de finos durante a redução da carga metálica no alto-forno, e com o RI (Índice de Redutibilidade) determina-se a capacidade do sínter em ceder oxigênio para o gás redutor. São ensaios de extrema importância, pois com o RDI é possível medir a degradação do sínter quando submetido a condições redutoras do alto-forno, e com o RI entende-se o grau de redução da carga metálica momentos antes do início de seu processo de amolecimento. Com a instalação deste forno no Laboratório de Redução da CSN, será possível correlacionar os componentes do sínter, e de outras cargas metálicas, avaliando suas influências no produto, e, consequentemente, em suas utilizações no alto-forno.

Aug 1, 2018

By Askew J. E

All facets of current practices of cable dowelling at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited are re- viewed. This includes materials specific- ations, installation practices and design pro- cedures. Cable dowelling for cut and fill stoping, square set timber stoping, longhole open stoping and level reinforcement is considered. Installation is simple and can be mechanised to eliminate heavy lifting. Quality control is essential for optimum performance of the re- inforcement. Design patterns must consider the mining method, reinforcement economics, acceptable stability standards and mine production priorities.

Jan 1, 1977

By Jason Herron, Joseph Brown

The common couplings for joining sections of helical piles with an outside diameter of 6.625 inches and 8.625 inches are square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. Each coupling type has advantages and disadvantages in efficiency, capacity, installation, and economics of the installed pile. All these coupling types have been used in the helical pile market in North America for various applications and designs. Many of these applications require on-site testing, but test records are not typically shared with the helical pile industry. Due to the lack of information available for square on square and flange to flange couplings, testing was done to compare the efficiency of installation, load to deflection response, and torque to capacity ratios of external pipe sleeve, square on square, and flange to flange couplings. Field installations and tension tests were performed in non-cohesive (sand type) soil near Caseyville, IL and in cohesive (clay type) soil in Centralia, MO. The data collected during these tests included rotations per foot during installation, installation torque, applied pressure, and deflection. The results of this testing are analyzed and discussed within this paper. The results indicate that the square to square coupling is the most efficient of the designs tested, but this conclusion cannot be fully justified without further testing due to the variability in the data gathered and the small number of piles tested. INTRODUCTION A helical pile is typically assumed to be a medium-displacement pile when its outside diameter is between 4.5 inches and 8 inches and a high-displacement pile when its outside diameter is greater than 8 inches. A helical pile designer has multiple options when selecting a coupling type for medium- to high-displacement helical piles. Each type of coupling has advantages and disadvantages and must be analyzed on the bases of efficiency, capacity, installation, and economics of a project. Typical couplings that are chosen by designers include square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. A helical pile must transfer axial, lateral, bending moment, and torsional loads, and the coupling must be designed to effectively and efficiently transfer each type of load. During the installation of a helical pile, the rate of penetration and the disturbance of soil layers play a critical role in the efficiency and torque to capacity ratio (Kt) of the pile. It is common for a coupling to protrude beyond the outside diameter of the pipe section being used. This is necessary for the function of certain coupling types and can facilitate the connection of couplings. However, it causes increased soil disturbance and reduce the rate of penetration due to soil bearing against the protruding portion of the coupling. A helical pile designer typically will work to minimize the coupling protrusion and create a pile with optimal installation efficiency but may choose a design with lower installation efficiency if it offers sufficient economic advantage.

Jan 1, 2019

By Milton Syamujulu

In 2004, KCM Nkana Smelter commissioned a 1200 tonne per day flash dryer and associated dry concentrate transport and injection system on the existing Teniente Modified converter (CT) unit. The aim was to upgrade the existing smelting unit, increase copper output and improve energy efficiency. This paper reviews the design, installation and commissioning phases of the introduction of this new technology and also discusses the initial two years of operating results for both the flash dryer and injection system at Nkana.

Jan 1, 2006

By Daniele Tolazzi

In today’s highly competitive market situation, it is of outmost importance for EAF steel makers to optimise their processes in order to reduce operating costs and to improve safety and reliability of the equipment. The laser based off-gas analysis technology, With laser units installed on the fix duct, downstream the combustion gap, uses the “Tuneable Diode Laser Absorption Spectroscopy” (TDLAS). The system performs real-time off-gas emissions measurements of CO, CO2, O2, H2O and temperature. A closed-loop operation is in place for dynamic control of the chemical energy package combustion/post-combustion of CO, H2 and CH4 gases into the EAF furnace shell. A statistical framework which builds on a data analysis engine, based on Danieli Automation Q3Intelligence technology, evaluates the “fingerprint” of the process represented by average and deviation trends of both gases and other process parameters. Process fingerprinting is conceived both for offline profile optimisation and on-line control of the refining process. This paper describes how the technology has been applied and the results achieved at ACCIAIERIE BERTOLI SAFAU (Italy) 100 t AC Electric Arc Furnace.

Aug 16, 2017