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By Cem Altuntas

This paper is the second in a series of two describing the design and construction of a foundation for a major high-rise real estate development on the west side of Manhattan, N.Y. The foundation members consist of large-diameter rock-socketed caissons, driven closed-end steel pipe piles bearing on rock, and a secant-pile retaining wall surrounding the entire site. This paper focuses on the Osterberg cell (O-Cell) load test completed for determining the allowable side-shear resistance between the concrete and the sides of the rock socket. Different qualities of mica schist bedrock, demonstrated by the penetration of rock with the soil auger or drill casing, were encountered. Accordingly, an additional subsurface investigation consisting of test borings at each caisson location was completed. Unconfined compressive strength tests were performed on representative rock samples. The ?soft? mica schist was observed to have vertical foliations and high mica content. For the first time in Manhattan, an O-Cell load test was performed to determine the allowable side shear resistance for both the soft and hard mica schist bedrock. The side shear resistance obtained from the O-Cell load test is compared with the side shear resistance allowed by the New York City Building Code and empirical correlations using unconfined compressive strength values for rock. The rock socket design for the caissons was refined based on the O-Cell load test results.

Jan 1, 2008

By A. Podlesny, E. N. Rubinstein, J. J. Sammarco, B. Demich

Roof bolting typically follows the extraction of a commodity to help keep the roof from collapsing. During 2004 to 2013, roof bolter operators had the highest number of machinery-related injuries, accounting for 64.7 percent, at underground coal mines. This paper analyzes U.S. roof bolter fatal and nonfatal lost-time injury data at underground work locations for all commodities from 2004 through 2013 and determines risk indices for six roof bolting tasks. For fatal and nonfatal incidences combined, the roof bolting tasks in order of the highest to lowest risk index were bolting, handling of materials, setting the temporary roof support (TRS), drilling, tramming, and traversing. For fatalities, the roof bolting tasks in order of the highest to lowest risk index were handling of materials, setting the TRS, bolting, drilling, traversing, and tramming. Age was found to be a significant factor. Severity of injury, indicated by days lost, was found to increase with increasing age as well as with increasing experience, largely due to the confounding of age and experience. The operation of the roof bolting machine used in underground mining should be a research priority given the high frequency and severity of incidents. The results also suggest that temporal factors may exist, so additional research is warranted to better understand these factors and potentially develop interventions. This research provides a datadriven foundation from which future research can be conducted for safety interventions to reduce the frequency and severity of incidences involving the roof bolter activities of bolting, handling of materials, and setting the TRS.

Jan 1, 2016

By B. Pina

The conversion of maf coal to pyridine solubles and gas was investigated in a microautoclave batch reactor for two Kentucky washed coal samples (Ky. #9 and Ky. #11). Solvent hydrogen donor strength was controlled by the tetralin content of a mixed 1-methyl naphthalene-tetralin solvent. Primary liquefaction conversions greater than 90% in 10 minutes of reaction time at 427°C were achieved in liquefaction solvents with moderate hydrogen-donor strength (circa 40% tetralin). A modified irreversible first order rate expression, containing a parameter (a) to account for the intrinsic reactives of the maf coal, described the experimental kinetic data rather well. The integrated form of this rate expression is -k1e x = a (a- ß)e (eq. 1) Parameter ß in equation (I) is the pyridine solubility of the starting maf feed coal, x is the primary liquefaction fractional number of conversion, k1 is the specific reaction velocity constant and ? is reaction time. Primary liquefaction rate was found to be quite temperature sensitive and independent of coal when a liquefaction solvent containing 40% or more tetralin was employed. Primary liquefaction rate appears to depend on liquefaction solvent hydrogen donor strength for solvents containing = 40 wt.% tetralin. The intrinsic reactives in the maf feed coal or a appear to depend mainly on the inertinite group maceral content of the coal for the two coals studied in liquefaction solvents containing 3 40wt.% tetralin. In contrast, a appears to decrease in liquefaction solvents of low donor strength., i.e; solvents with less than 40wt.% tetralin.

Jan 1, 1984

By Alexander Sutulov

1. INTRODUCTION According to the classical economic approach of the open market economy, copper supply should be regulated by market forces which are (a) demand and (b) prices. In fact, demand is of primordial importance because prices are a reflection of supply-demand balance: they go up in times of shortages of supply and down when over-supply situation exists. In the past few years, this basic mechanism of market economy has been under pressure from a number of non-market forces, such as social and monetary problems of sane important copper producing countries; structural changes in copper mining companies through mergers with oil companies; and other factors which greatly contributed to distortion of the basic supply-¬demand equation. As a result, we have faced in the last three years a situation of oversupply rarely seen in the past, with a catastrophic fall in copper prices, huge losses at mines and unprecedented indebtedness of copper producers. This has deep repercussions in the copper business and its future supply outlook. This is particularly so when taking into consideration that high indebtedness and high interest rates conspire against the very survival of some traditional producers. As we write this comment (July of 1985), close to one half of U.S. copper production capacity is closed down, sane of it for good, while the same precarious situation exists in Canada, Australia, Zambia, and some other primary producers who cannot face present low prices with equally low costs. The question is then what this situation means for the medium-¬term future, until the end of this decade, Particularly when taking into consideration the fact that some of the factors influencing it are of a long-term character. 2. SUPPLY-DEMAND SITUATION IN THE LAST FIVE YEARS Since the last boon year, in 1979, when world copper consumption reached a record of 9.8 million metric tons of refined copper, demand dropped to only 9.0 million tons in 1982, when the crisis bottomed out, and then steadily recovered to the level of 9.7 million tons in 1984. Meanwhile, copper production, which in 1979 was only 9.4 million tons, in spite of the fall in demand, grew to 9.7 million tons in 1981 and 1983 and only temporarily was cut to 9.4 million tons in 1982 and to 9.5 million tons in 1984. As a result of this imbalance, hugh copper stocks were accumulated with supply systematically out¬growing demand by over 2 million tons at one time. With the Western World refined copper demand running at an average of 115,000 tons per week, this oversupply was equivalent to between 15 and 18 weeks production, i.e. twice as large as normal. This was immediately reflected in very low copper prices. Another contributing factor to relatively low copper prices was the lack of speculator interest for this commodity. Between 1981 and 1984 the world experienced a very intensive period of wealth distribution, high interest rates and intensive restructuring off world economy and its industrial sector. Therefore, much of the available money was attracted to more lucrative and attractive investments rather than to the lack-luster performance of copper, and for that matter, of the metal sector in general. The much announced and discussed recovery of the U.S. economy since 1983, and particularly in 1984, with an overall growth of the GNP by 6.8% in 1984, happened to be more oriented to the service sector than the industrial sector and therefore this recovery was not adequately reflected in copper consumption nor to metals in general. This put serious doubts about the future demand for copper. Consequently copper prices failed to improve in spite of an apparent fall in stocks and a healthy increase in the demand for copper since 1982. At the time of this writing (July, 1985), although same analysts claim that the available stocks are running at about 8 weeks of supply, which are considered to be below normal, copper prices are still very low at between 65 and 67 cents per pound of copper. Part of the answer may be the normal seasonal slow-down period in the Northern Hemisphere due to summer vacations and

Jan 1, 1986

By G Byrne

Long-term water management is typically ignored in mine closure planning. A review of 73 mine closure plans dating from 2007 to 2013 shows that, on average, relinquishment is proposed to be achieved in 11 years. A separate review of 57 mines in actual closure shows that only five have so far achieved relinquishment with an average closure period of 14 years after production cessation. The remaining 91 per cent of sites in closure have an average closure duration to date of 21 years - and still going.A common issue among those sites in closure is water management, with a further common issue being acid and metaliferous drainage (AMD). Of the closure plans that were reviewed only one site had allowance for long-term (>50 years) of water treatment. Of the sites in actual closure 25 per cent have reported that they expect such long-term water treatment, with many acknowledging that in perpetuity treatment is probable.Clearly there is a gap between what is being allowed in closure plans and the reality of closure. There are a number of factors leading to the optimism of the closure plans, including unrealistic assumptions, pressures to reduce closure cost provisions and the technical complexity of many AMD issues.Long-term water management is a reality that needs to be acknowledged and addressed. If addressed early in the mine life cycle the impacts for mining companies can be reduced.CITATION:Byrne, G, 2013. Long-term water management - the forgotten legacy of mine closure, in Proceedings Water in Mining 2013 , pp 163-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By R. J. Kuczynski

The U.S. Bureau of Mines Reno Research Center operated a batch pilot plant to demonstrate high-temperature cyanide leaching for recovering platinum group metals (PGM) from automobile catalysts. Approximately 1,600 kg of used pellet, monolith, and metal support catalyst containing 1,680 g (54 tr oz) of PGM were processed. Forty-five-kilogram batches of used catalyst were leached with sodium cyanide solution at 160° C for 1 h under basic conditions in a countercurrent processing sequence to dissolve the PGM. Extractions from the used pellet catalyst ranged from 94 to 95 pct for Pd, 95 to 97 pct for Pt, and 64 to 81 pct for Rh. Extractions from the used monolith catalyst ranged from 7B to BB pct for Pd, 75 to 90 pct for Pt, and 43 to 71 pct for Rh. Heating the pregnant leach solutions to 275' C for 4 h destroyed the PGM-cyanide complexes, resulting in over 99.7 pct of the PGM precipitating from solution. The PGM precipitate was predominantly a powder metallic concentrate, typically analyzing greater than 50 pct PGM. Heating destroyed cyanide to less than 0.2 mg/L. Both the pellet and monolith residues were evaluated for disposal using the EPA Toxicity Characteristic Leaching Procedure.

Jan 1, 1995

With mining development on hold and other underground works in a slowdown, the develop- ment of nuclear waste repositories takes center stage on the American rock engineering scene. Three repositories for commercial spent fuel -- in salt, tuff, and basalt -- are in the phase of site characterization and conceptual design, and one pilot project for defense high-level waste in salt is under construction. A repository design for crystal line rock has recently been postponed. Because of strict quality assurance requirements throughout design and construc- tion, and because of the need to predict and ascertain in advance the satisfactory perfor- mance of the underground openings, much intellectual energy has been expended to analyze underground openings in the unusual circumstances of the repository environment. In the long term, these efforts will lead to an improved understanding of rock behavior and improved methods of underground analysis and design. For the shorter term, a formalized ground control plan was developed, the princi- ples of which may be applied to other types of projects. This paper summarizes the status of underground design and construction for nuclear waste repositories and presents some details of the ground control plan and its individual elements.

Jan 1, 1987

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the eleventh. The-data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each halt township is followed by a description of each deposit developed in that halt township. The 14 halt-township maps and 77 detail maps of the bauxite deposits in this series at reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained tram the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each halt township is given with the discussion of that area.

Jan 1, 1948

By Anthony T. C. Goh, Zhiye Zhao, Laddu B. Jayasinghe, Hongyuan Zhou, Yilin Gui

"Ground vibrations from blasting are undesirable and they are very short in duration with high principal frequencies and high amplitude. Structural response to that kind of excitations may differ significantly from that generated by lower-frequency earthquake vibrations. In practice, the damage to nearby structures to generated ground vibrations has been controlled by various codes and regulations available. However, the existing vibrations limits are not always applicable, as they depend on the geological conditions of the site and the dynamic characteristics of the structure. This paper investigated the influence of the rock-soil interface on the response of pile foundation to ground-borne vibration from rock blasting, through numerical simulations using finite element software LS-DYNA. It is found that the slope of the rock-soil interface greatly influences the location of damage and the extent of damage on the pile. The bottom of the pile is subjected to a larger blast pressure and stresses are highly concentrated at the pile bottom. Thus, the pile bottom can fail in shear before it reaches its plastic moment capacity.INTRODUCTIONDrilling and blasting is the widely accepted method to large-scale rock breaking activities in civil engineering constructions due to its cost effectiveness, higher efficiency and ability to break hard rock. However, ground vibrations from blasting are undesirable and it can cause damage to nearby structures. In practice, the damage to nearby structures to generated ground vibrations has been controlled by various codes and regulations available. The existing vibration limits are not always applicable, as they depend on the geological conditions of the site and dynamic characteristics of the structure.Pile foundations are commonly used as foundations of high-rise buildings and bridges to transfer the heavy loads from the superstructure above through weak compressible soil strata into deeper, competent soil layers which have adequate capacity to carry these loads. In engineering practice, many piles are normally designed to carry mainly vertical loads and very little lateral loads, as typically the vertical loads (the gravity) are significantly larger than the horizontal loads such as wind loading. However, in recent years, there have been a number of reported case studies of translational soil movements that have induced stresses and bending moments that have damaged pile foundations and in some cases resulted in collapse of the superstructure. Typical lateral load include nearby construction activities such as an excavation for a basement or slope, the construction of a road embankment or a tunnel, as well as earthquakes (Abdoun 1997; Goh et al. 1997; 2003; Chen et al. 1999; Dobry et al. 2003; Boulanger et al. 2007; Black et al. 2007)."

Jan 1, 1900

By George A. Bell

This paper reviewing the leaching practice of the New Cornelia mines of the Calumet & Arizona Mining Co. at Ajo, Ariz., is the first of a series being prepared by the Bureau of Mines on leaching methods and costs in the various mining districts. ACKNOWLEDGMENTS The author acknowledges the assistance of T. G. Chapman, consulting engineer, and E. D. Gardner, supervising engineer of the Southwest Experiment Station, Bureau of Mines, Tucson, Ariz.

Jan 1, 1930

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By Dennis S. Kostick

Sodium is a silver-colored metal that is so unstable that it reacts violently in the presence of water, and chlorine is a greenish-colored gas that is dangerous and lethal. Yet the combination of these two elements forms sodium chloride, commonly known as salt, which is a white-colored compound essential to life itself. Salt is perhaps the only mineral in the world that is used virtually by every human being in every country. Although its importance has diminished over time, salt has had a profound influence on history. Sources of salt have determined the location of cities, such as Salzburg, Austria, Salzgitter, Germany, Salt Lake City, UT, and Saltville, VA. Populations have migrated in search of salt, and wars have been fought to obtain or to protect it. Although there is no written record of when prehistoric man first discovered salt, he probably instantly appreciated its unique and distinctive taste and sought more of it. He noticed animals were attracted to salt springs and salt licks, where they satisfied their innate cravings. Man used this knowledge to hunt for food; where he found the salt, he would find the animals. Because prehistoric man was not aware of his physiologic need for salt, he automatically received his salt requirements from the meat of the animals he ate. A Mesopotamian tale tells of a wounded pig that ran into the ocean and drowned. After being recovered from the ocean, where it was saturated in the salt brine, the pork was found to taste better than unsalted meat. It was not until man graduated from a nomadic to an agricultural society when he introduced vegetables and cereals into his diet that he realized he needed additional supplements of salt. The Sumerians ate salted meat and used salt to preserve food about 3500 BC. In approximately 1000 BC, the Trojans learned to use salt for preserving fish. The maritime civilizations, such as that of the Phoenicians, engaged in an extensive salt trade throughout the Mediterranean. Many superstitions, customs, and traditions surround the religious, social, economic, and political aspects of civilization. Although some commodities have provided the basis of some ageless metaphors and cliches (i.e., heart of gold, strong as steel, etc.), none are more commonly used than those pertaining to salt. Being "the salt of the earth" referred to a person's worthiness, as referenced in Matthew 5:13 of the Bible. Someone "not worth his salt" reportedly was used in ancient Greece in bartering salt for slaves. When a laborer was worth his salt, he was paid a salary (sal is Latin for salt), a term still in use today that dates back to Roman times when part of a soldier's pay was salt rations. Fearing those around him, the Roman leader Pompey was known to add a grain of salt to his drinks as a supposed antidote to poison. Hence, "taking it with a grain of salt'' is to regard something with suspicion. The earliest known record of salt production was in China about 2000 BC when Emperor Yu decreed that salt had to be supplied to the court as a tribute. Because salt was a commodity that had universal demand, governments often intervened to control salt production and distribution to generate revenue for major national projects. State-run salt monopolies were common in history, such as in Rome about 506 BC. Revenue was also derived from taxes levied on salt sales. The word gabelle refers to the direct salt tax used in France. This tax was so despised that it was a major cause of the French Revolution. Although the tax was repealed in 1790, it was reinstated in 1805 to raise revenue for war. France continued to used the gabelle until 1945. Salt making was an important economic activity in many areas of the world. Archaeological evidence indicates that salt was quarried from hills near the Dead Sea before the Bronze Age. At Hallstatt in the eastern Alps of Austria, rock salt was mined as early as 1400 BC. Solar salt was being produced in the northern Yucatan peninsula by the Mayan civilization from about 50 BC to AD 300. Other than the prehistoric use of salt in the southwestern part of the United States by the Native Americans, the first production of salt by American colonists began in June 1614 on Smith's Island, VA, seven years after the founding of the Jamestown colony. The short-lived activity was in response to the high price of salt being charged by ship's captains who brought salt over as ballast from England. Although Nathaniel Loomis is credited with starting the first commercial inland salt production in the United States at Onondaga Lake in New York in 1790, salt had been made by individuals for private use years earlier. Indians had long known of the salt springs in the Kanawha Valley of Virginia (now known as West Virginia). In 1755, Mary Ingles, a white settler, was kidnapped by Indians and was forced to make salt from the saline springs. After her escape, she told other settlers how to make salt. At Saltville, VA, Arthur Campbell began making salt in 1782 by boiling brine obtained from salt springs. In 1799, William King sank a shaft about 3 m in diameter down about 61 m to the underlying Saltville salt deposits. The shaft flooded before he could extract any rock salt; however, King has the distinction of digging the shaft of the first salt mine in the United States. Fig. 1 shows the King site as it appears today in Saltville, VA. Production of brine from the shaft continued until 1892. Settlers moved into the Kanawha Valley in 1785, but it wasn't until 1806 that Elisha Brooks established the first commercial salt works in Kanawha.

Jan 1, 1994

By R. V. Ramani, J. Qin

"During the mining process, the insitu material is broken into different size ranges, from very, large pieces to very fine particles. Some of the fine particles become airborne. In underground coal mining, airborne respirable. dust is associated with health and safety of the miners: The amount and size distributions of airborne dust are important parameters to effective dust control measures. The design of underground mine experiments, including sampling procedures and sample analyses methods to determine these parameters are presented in this paper.. A total of fifteen continuous miner cuts were sampled. The amount of dust generated during the cutting process and the relationship between total and respirable airborne dust concentrations and amounts are examined.The amount of respirable dust airborne is on the average only. 0.016% of the respirable dust generated. On the average, 61% of the total .airborne dust measured is in the respirable size range. The amount of respirable airborne' is on the average 36% of the respirable size fraction in the total airborne dust. For equal proportion of rock and coal material cut, rock contributes about twice as much fines (<0.22 mm) as coal. Additional fundamental research is necessary to further the understanding of 'the airborne propensity of respirable dusts in mine atmospheres.INTRODUCTIONMining is a sequential process of breaking, gathering, loading, and transporting the in-situ .materials.' In underground coal mines, duet in both the non-respirable and respirable size ranges is generated and entrained in every phase of the process. Even though large amounts of dust particles' adhere to run-of-mine coals, part of the dust generated becomes airborne (Cheng and Zukovich, 1973). Studies have shown that bit type affects the amount of dust generated'(Evans and Pomeroy, 1966; Kurth et al., 1975; Roepke et al., 1976; Stecklein et al., 1982; and Khair and 'Reddy, 1986). Deep cutting can reduce airborne dust generation (Black and Schmidt, 1977 arid, Black et 1978). Mechanical properties of. coal seams are also important factors in dust generation. Laboratory studies have shown that Hardgrove Grindability Index (HGI) of the coal has a relationship with the amount of respirable. dust generated (Beafi and Ramani, 1979; Moore and Bise, 1984; and Moore, 1986). However, these relationships have not yet been validated with' data from the mines. The amount of dust airborne depends on a number of factors. Suppression of the airborne propensity of dust by water sprays is'widely practiced and is very effective. Water flow rate; pressure and configuration of water sprays have been identified as major factors affecting dust capture by sprays (Courtney and Cheng, 1977; Courtney et al., 1978; and Kissell et al., 1979). Ventilation is a very important means of controlling the dust level at the coal face (Jayaraman, 1977). According to a National Academy of Sciences study (1980), the mechanism of dust generation and the process by which the generated dust becomes airborne are complex and not yet completely understood coal seams are also important factors in dust generation. Laboratory studies have shown that Hardgrove Grindability Index (HGI) of the coal has a relationship with the amount of respirable dust generated (Beafi and Ramani, 1979; Moore and Bise, 1984; and Moore, 1986). However, these relationships have not yet been validated with data from the mines. The amount of dust airborne depends on a number of factors. Suppression of the airborne propensity of dust by water sprays is widely practiced and is very effective. Water flow rate; pressure and configuration of water sprays have been identified as major factors affecting dust capture by sprays (Courtney and Cheng, 1977; Courtney et al., 1978; and Kissell et al., 1979). Ventilation is a very important means of controlling the dust level at the coal face (Jayaraman, 1977). According to a National Academy of Sciences study (1980), the mechanism"

Jan 1, 1989

By Aline Aguiar Lopes

A piora na qualidade dos minérios de ferro tem levado as empresas a adaptarem seus processos a novas condições de qualidade das matérias-primas, surgindo assim a necessidade de desenvolver estudos que auxiliem as tomadas de decisão. Esse trabalho avaliou a influência da qualidade do sínter e da composição da carga metálica na zona coesiva do alto-forno através dos parâmetros de amolecimento e fusão. A importância de se obter informações sobre a zona coesiva se deve principalmente ao fato de nessa região ocorrer a maior parte da perda de carga no interior do alto-forno. Cinco amostras de sínter de qualidades químicas distintas, produzidas nas sinterizações da CSN (Companhia Siderúrgica Nacional), foram selecionadas e caracterizadas para esse estudo. Os ensaios de Amolecimento e Fusão foram realizados no Centro de Tecnologia de Ferrosos da Vale através de um acordo de cooperação técnica entre as empresas. Os resultados obtidos mostraram que as técnicas utilizadas são adequadas para avaliação das propriedades em altas temperaturas, fornecendo dados importantes para a interpretação do comportamento da carga metálica no interior do alto-forno, como espessura e posicionamento da zona coesiva, permeabilidade e redutibilidade da carga, indicando assim, a composição da carga metálica de melhor desempenho para o alto-forno.

Aug 17, 2017

By François Robert

"The Eastern Abitibi Sub province (Quebec segment), contains two main types of gold deposits: the common quartz-vein type and the rare pyritic type. Both occur in areas dominated by volcanic rocks and are spatially associated with major fault zones.Quartz-vein gold deposits consist of simple to complex networks of quartz-carbonate-pyrite veins in reverse shear zones and extensional fractures. They occur in areas dominated by mafic volcanic rocks and are commonly associated with small syn- to late-tectonic porphyritic felsic intrusions. Associated alteration, which postdates peak metamorphism, is dominated by carbonatization, sericitization and pyritization of the wallrocks. These deposits formed late in the geologicalevolution of the Abitibi.Pyritic gold deposits range from deformed massive sulphide lenses to zones of syntectonic pyrite-rich veinlets and associated pyrite disseminations. These deposits occur in environments dominated by felsic volcanic rocks that are typically converted to sericite schists near the deposits. The associated pre-metamorphic aluminous alteration is now characterized by metamorphic sericite, andalusite, kyanite and chloritoid, overprinted by a late retrogression of alumino- silicates. These deposits probably represent deformed volcanogenic massive sulphide deposits, but the timing of gold introduction in these is not fully understood.The differences in geological attributes reflect significant differences in the genesis these deposits: the pyritic deposits probably have a multistage genesis, including a pre-tectonic stage, in contrast to a single stage late-tectonic genesis for the quartz-vein deposits.RESUMELa partie Est de la Sous-Province de l’Abitibi( segment québécois) renferme deux types de gites d' or: ceux de type ""veine de quartz"" et ceux, plus rares, de type ""pyriteux"". Ces deux types se trouvent dans des secteurs particulièrement riches en roches volcaniques et mantrent une association spatiale avec des zones de failles majeures.Les gites de type ""veine de quartz"" correspondent à des réseaux de complexité variable de veines de quartz-carbonate-pyrite se développant dans des zones de cisaillement inverse et des fractures de tension. Ils se concentrent dans les régions dominées par des roches volcaniques mafiques et s’associent fréquemment à de petites intrusions porphyriques felsiques syn- a tardi-tectoniques. L’altération associée ace type de glte est postérieure à la phase majeure du métamorphisme et consiste en une carbonatisation, une sericitisation et une pyritisation des épontes. La mise en place de ces gites est tardive par rapport à l'évolution géologique de l'Abitibi.Les gites d' or de type pyriteux consistent en des lentilles de sulfures massifs déformes, des zones d' abondantes veinules pyrite uses syntectoniques, et des zones de pyrite disséminée. Ces gites se retrouvent dans des empilements contenant surtout des roches volcaniques felsiques qui sont transformées en schiste à séricine pres des gisements. L’altération a l’umineuse pre-metamorphique associée a ce type de glte a donné naissance, lors du metamorphisme regional, a la sericite, a 'andal ousite, a Ia lcyanite et au chloritoi""de; par la suite, les alumino-silicates ont été affectes par une alteration retrograde tardive. Ces gites representent probablement des depOts de sulfures massifs volcan gènes déformes, mais la chronologie de la mise en place de l'or dans ceux-ci est encore mal comprise.Les caractéristiques géologiques propres à chacun de ces types de gites reflètent des conditions de formation différentes: le type ""pyriteux"" montre une histoire génétique polyphasée, incluant une étape pre-tectonique alors que le type ""veine de quartz"" s’est développe au cours d’une seule phase tardi-tectonique."

Jan 1, 1990

By Arnold K. Reese

It is not the purpose of the writer to set forth in these notes anything new or surprising in blast-furnace practice, but simply to lay before the Institute the somewhat unusual results obtained during a period of six consecutive months, ending April 30, 1896, at the Dover furnace of the Penn Iron and Coal Co., and to give, with these results, the conditions under which they were obtained, and all figures pertaining to that period. This plant was entirely rebuilt, on thoroughly modern and improved plans, in the spring of 1895, by Frank C. Roberts & Co., of Philadelphia.

Jan 1, 1898

By M Kim, J Park, I-K Suh, E Kim, J Lee

One of the key technologies in developing hydrogen-enriched ironmaking operations is the control of the carburisation, melting, and dripping behaviour of the iron ore burden materials. When a hot compacted iron (HCI) is charged in the blast furnace or the FINEX Melter-Gasifier, iron oxide reduction, the reduced iron’s carburisation, and the melting of iron and slag occur successively. This study investigated the reduction, carburisation, melting and dripping behaviour of HCI under a COH2 gas mixture using the high-temperature X-ray radiographic technique. Under 100 per cent CO gas atmosphere, the dripping temperature was 1410°C. When 5 per cent H2 was introduced, the dripping temperature slightly decreased to 1400°C. Furthermore, the dripping temperature gradually increased as the H2 gas composition increased. As 30 per cent H2 was introduced, the dripping temperature reached 1414°C. The carbon concentration in the drained metal samples gradually increased with increasing H2 composition. It is considered that H2 decreased FeO content in the slag, yielding the increased melting temperature and viscosity of the slag. On the other hand, H2 accelerated the carburisation of the reduced iron by CO gas, enabling the homogenisation of the oxide materials to form a liquid phase. Therefore, it is considered that introducing H2 in the reactor is helpful to increase productivity and energy efficiency by accelerating the liquid phase’s formation.

Aug 21, 2024

By Mariella Cortez Caillahua

No presente estudo o gesso FGD (flue gas desulfurization) foi avaliado como aditivo retardador do tempo de pega, substituindo o gesso natural na fabricação do cimento Portland (CP II E-32). Os resultados da caracterização físico-química e morfológica do gesso natural e do gesso FGD identificaram um material de alta pureza, sulfato de cálcio di-hidratado para o gesso natural e a presença, principalmente, de bassanita (CaSO4.0,6H2O) e hannebachite (CaSO3.0,5H2O) com baixas concentrações de impurezas no gesso FGD. Baseado nos resultados, o gesso FGD é uma alternativa adequada para substituir o gesso natural. O tempo de pega mostrou cerca de uma hora de retardo em comparação com gesso natural e seu efeito sobre a resistência à compressão para as amostras de 3, 7 e 28 dias dependem da composição das misturas, atingindo um valor máximo para a argamassa com 2,1% de gesso FGD e 1,4% de gesso natural. Seguindo a norma ABNT NBR 10004:2004 o resíduo é classificado como não perigoso e não inerte.

Aug 8, 2018

By J. Brune

The need for reliable and adaptable underground mine communications has become a focal point for both the safety and logistics of a mining operation. New mine communication technology aims to connect personnel, equipment, and data together while setting up a network that can be utilized during normal operations and also in an emergency event. The Mine Improvement and New Emergency Response Act of 2006 (also known as the MINER Act) requires mine operators to establish post-accident, two-way communication between underground and surface personnel and electronic tracking for all mine personnel. Communications systems must be designed such that they can survive major mine accidents, including explosions, fires, inundations and ground falls. Typical, wire-bound communication technologies are vulnerable because wires are often destroyed in such accidents. Wireless technologies that work well on the surface, such as cellular telephone networks; have limited applicability underground because the wireless signals do not propagate through rock.

Feb 23, 2014