Search Documents

The corrosion behaviour of a low carbon steel was investigated in synthetic seawaters with and without Sr2+. It was found that strontium substitutes for calcium in aragonite, rather than precipitating as discrete strontianite (SrCO3). The aragonite deposits that formed in the presence of Sr2+ were finer than those that formed in the absence of Sr2+. It is believed that an increase in the strontium content of aragonite induces a decrease in its solubility, which in turn results in a higher nucleation rate of the precipitates. Furthermore, the growth rate of aragonite is decreased by the presence of Sr2+in the solution. It is concluded that Sr2+is an essential ingredient in any artificial seawater when calcareous deposits are investigated on steel. Keywords: corrosion, seawater, calcareous deposits, strontium, aragonite.

Jan 1, 2007

By Hamid-Reza Manouchehri

Mining & Sustainability? A Paradox?! ? Production: gradually or exponentially increasing (giant mining) ? Ore Grades: gradually declining, ? Open Cut Mining: now widespread, likely to be sustained in the future though the long-term is hard to predict as new mineral deposits are likely to be deeper ? Waste Rock / Overburden: increasing rapidly, likely to be sustained in the future and closely linked to open cut mining, especially for coal and base metals ? Economic Resources: commonly increasing but some remain stable or gradually declining, future is linked closely to exploration, technology and economics; Increasing population, changing life style and technology development, ultimately result in sustainability in mining industry to hang in the balance and continue.

May 1, 2013

By Richard K. Sandaas

Start Date: April 4, 1988 Completion Date: Dec. 29, 1989 Contractor: SCI Contractors Past and present transportation centers will come together at International District Station, located at the south entrance to the tunnel next to the turn-of-the-century Union Station train depot. The area will bustle once again with activity as commuters and visitors converge on the modern transit station at the edge of Seattle's International District. Buses coming from south Interstate 5 and Interstate 90 will enter the tunnel through this station. [ ] International District Station is an open-air station, 1,060 feet long and 82 feet wide (about 15,400 cubic yards of concrete were used to build the station). A concrete lid over the southern portion of the station staging area is held in place by 131 support piles. The station will include entrances on Jackson Street and King Street. Union Pacific Realty is planning to build an office and retail complex upon the lid. The station also has an international flair. Symbols of the Chinese zodiac will be etched into the station plaza floor. The station platform walls will be lined with large steel panels embellished with designs in origami?a Japanese folded paper art form. [ ]

Jan 1, 1990

By Curtis Wilson

FROM the results of his investigation of the hardenable copper-nickel-silicon and copper-cobalt-silicon alloys, M. G. Corson1 explained the dispersion-hardening effect by assuming the precipitation of the inter-metallic compounds nickel silicide and cobalt silicide, and on this basis he constructed diagrams for the pseudobinary systems copper-nickel silicide and copper-cobalt silicide. A consideration of these diagrams and of the factors that exert such an important influence upon the rate of precipitation, such as degree of supersaturation, nucleus number and rate of diffusion, leads to the expectation that the rate of precipitation of the silicides on reheating the quenched solid solutions at temperatures below the alpha-phase boundary should increase continuously as the reheating temperature is raised. The present investigation shows that while this rate does increase with the reheating temperature in a general way, it does not do so continuously. Supplements to Corson's diagrams are offered, showing the discontinuities, and slight modifications in the solubility curves are suggested.

Jan 1, 1933

RME has a vision for a new grinding plant operational paradigm made possible by RME's fast, safe Mill Relining System. Some new liner designs can degrade SAG mill performance because of mill volume loss, ball strike (rotational speed limitations) and other issues often brought about by modifying liner design for maximum life and without a backward glance at metallurgical consequences. Freshly relined mills can initially produce as little as 80 per cent of their maximum throughput, that maximum occurring toward the end of the liners' wear life. RME's proposition is to see new liners designed for maximum commercial performance. This may mean more frequent mill relines but with liners designed to yield optimum grinding, metallurgical and profitability performance, not maximum life. In other words, mill liner profiles and mill relining speed become key operational controls and not simply `must do' maintenance functions. Taken to the extreme, liner profiles may prove capable of `tuning' a grinding plant for maximum profitability in any metal price environment. Following the introduction, the first section of this paper provides an update describing recent and significant developments within RME's range of Mill Relining Systems, the enabling technologies which permit more frequent liner exchange without incurring additional downtime imposts. The second section outlines RME's vision of a `liner profile versus profitability' commercial model, developed either intuitively or by using a combination of new measurement and modelling technologies. These new measurement and modelling tools provide the opportunity to predict the optimum commercial outcome, off-line in the virtual world, before committing to an expensive liner experiment.

Jan 1, 2007

By T. Braun, J. Parker

On June 25, 1999, BHP Billiton (BHPB) announced the suspension of operations at the BHP Copper Inc.(BHP) San Manuel copper mine in Pinal County, Arizona. Subsequent to this announcement, BHPB aggressively pursued a number of alternatives for the underground mine and open pit facilities, including continued curtailed operations, sale to a qualified mining operator and closure of the property. After consideration of these various alternatives over a 2.5-year period, BHPB announced final closure of the mine site on January 15, 2002.This paper describes how the BHPB charter and HSEC policy apply during the closure process.

Jan 1, 2004

By D Porta, E Grigolato, K Behrens

################

Aug 12, 2013

By M. Potesser

One of the main targets in the automotive mass industry and supplying industry is the weight reduction of the vehicle for decrease of the fuel consumption. For that reason combinations of different kinds of materials and connections of, for example, steel and aluminium are developed or are already successfully field-tested. A determining factor concerning the quality assessment of the welded joint during hybrid welding is the characterization of the intermetallic Fe-Al layer regarding strength, hardness, morphology and mainly the different phases in which Fe occurs together with the Aluminum (FeAl, Fe2Al5, FeAl3.). A combination of conventional light microscopy, SEM - EDX - analysis, the usage of an atomic force microscope including a Nanoindenter and theoretical thermodynamic calculations turned out to be highly effective. Based on the attained results, the constitution of the intermetallic FeAl layer, influenced by silicon, manganese and zinc, can be predicted.

Jan 1, 2006

By Peter Townsend, Sergei Diachenko, Allan Moss

The Palabora Mining Company has successfully extended the life of its operation by developing a 30,000tpd block cave underground mine below the now closed open pit. The process of transitioning from surface to underground mining has been technically, operationally and managerially challenging. This has been due to a number of factors; in particular, the development of a block cave in a very competent rock mass. The competence of the rock mass is clearly demonstrated in the open pit that preceded the block cave, one of the steepest deep open pit excavations in the world. With cave breakthrough, however, the pit was ?instantaneously? deepened by 400m causing a major failure of the northwest wall involving close to 100Mt of waste material.

Jan 1, 2006

By T. Holmes, D. C. Russell, G. Jolly

"The AMEC Oakville office is involved in the design and construction of an iron ore concentrator located in Liberia. Currently, the site ships Direct Shipped Ore (DSO) to overseas customers. The DSO mine-site and port can experience heavy annual rainfalls. The IMSBC Code requires that cargoes are only accepted for loading when the moisture content of the cargo is less than its Transportable Moisture Limit (TML). The moisture content of the DSO has, on occasions, risen to near or above its TML. AMEC was asked to advise whether the concentrate produced from the new concentrator would or would not have the same problems with moisture content and ship loading as the DSO.INTRODUCTION Liberia was, at one time, the world’s sixth largest exporter of iron ore and used some of the most modern mining operations of their time. However, the country has not produced iron ore over the past seventeen years because of civil unrest. The return of stability to the country has allowed the redevelopment of the iron ore industry. ArcelorMittal Liberia (AML) obtained a concession for mining in the Nimba County area of Liberia (Figure 1) in December, 2004 and has studied the known iron ore deposits and former mining operations in this area. It began phase 1 operations in June 2011 with the direct shipping of high grade ore at a rate of up to 4Mtpa. The processing of the lower grade ore in phase 2 of the project requires additional processing capability to produce at the design rate of 15Mtpa. DSO and Concentrate The DSO in the first phase is selectively mined at an average grade of 60% Fe, and then crushed and screened to -10 mm with no washing or concentration. Testing of samples has indicated a size distribution that is finer than typical sinter feed material, although critical material below 0.10 mm is low in most cases, and overall the ore is coarser than typical concentrates or ultrafine products (Feasibility study report, 2011). The phase 1 DSO facility will cease operation after the phase 2 concentrator comes into operation."

Jan 1, 2014

By Steve Kral

For an industry that provides more than half of the nation’s energy needs, the U.S. coal industry still attracts negative publicity. However, the nation’s energy appetite continues to increase. And political leaders and the public are beginning to understand that alternative fuels will not be enough to keep up with that appetite. Does that mean the nation will now embrace the coal industry? No, according to speakers at the Rocky Mountain Coal Mining Institute (RMCMI) meeting. The industry still needs to sell the public on coal’s advantages over other fuels. And the industry must continue to develop technology that will allow coal to meet and exceed strict clean air and clean water regulations.

Jan 1, 2002

By Xi Zhang

A technique for fabricating free-standing, high-aspect-ratio porous and pillar-type Ni structures has been developed using wet Si processing. A wafer of (100) Si was initially etched in HF solution to form deep pores with micron-sized diameter. The aspect ratio can exceed 200. By introducing the as-etched Si into a defined aqueous Ni2+ solution, Ni deposits grew rapidly onto the sidewalls and replaced the Si. Long-time immersion allows the Si sidewalls to be completely converted and thus form a metallic Ni structure with high-aspect-ratio pores. It is known that close-packed submicron Si pillars can be formed by oxidizing and subsequent etching of the macropore sidewalls. Treated in the same Ni solution, high-aspect-ratio Ni pillars were correspondingly emerged by replicating the original pillar-type Si structure.

Jan 1, 2006

By Paul Kunze

When a new bridge was needed across the upper reaches of the Yellowstone River in Montana, removing the old concrete bridge piers became an environmental concern for the highway department engineers. The location is about fifty miles downstream from the north edge of Yellowstone Park. The determination was made by the federal and state agencies charged with protecting the resource, that the old piers had to go but the river bed had to remain unchanged. Concerns were expressed that removing the concrete presented the potential for environmental damage to this protected portion of the river. These concerns prompted the state to place stringent restrictions on the contractor in the way they carried out the demolition and disposal of the piers. The reinforced concrete masses had to be removed to an elevation at least fifteen feet below the river bed and every bit of concrete debris had to be removed from the river channel. Explosive removal was discouraged, but the only other options: saw cutting, mechanical or chemical breaking, were not viable.

Jan 1, 2014

By D. V. Roberts

Approximately 800 private consulting engineering firms in America specialize in geotechnical engineering. The gross income from these firms totals about $500 to $600 million per year. Sixty-five to seventy-five percent of this geotechnical work is per­formed by consulting engineers that belong to the Association of Soil and Foundation Engineers (ASFE). This paper presents statistics concerning the business activities and functions provided by ASFE member firms. The procedures used in typical projects are described. The paper concludes with a summary of major trends which are impacting the American geotechnical practice today.

Jan 1, 2010

By F. E. Cash

"Explosions in bituminous coal mines are preventable. The combination of adequate ventilation, thorough rock-dusting, and water on the cutter bars of mining machines and of empty and loaded cars will certainly reduce the hazard to a minimum, if not remove it entirely. This is the attitude taken by the Woodward Iron Co. in lessening or removing the dust and gas explosion hazard from its Dolomite and Mulga mines.This report was made possible through the willingness of Frank H. Crockard, president of the Woodward Iron Co. to make records available and to authorize their publication for the benefit of the coal-mining industry.The compilation of these data and preparation of maps was facilitated by the cooperation of M. Heard, general superintendent of coal mines, J. B. Whatley, assistant general super-intendent of coal, and R. P. Whetmore, chief mining engineer.The Dolomite and Mulga mines are about 16 miles southwest of Birmingham, Jefferson County, Ala., on a company owned and operated railroad which connects ore mines, coal mines, coke ovens, and furnaces.In the Dolomite property there is a 30°, 860-foot, double-tracked slope for hoisting, three manway and air slopes and one air shaft, all in rock.At Mulga there is a 220-foot hoisting shaft, an air shaft and two manways, and material and air slopes, all in rock to the coal bed.The coal in both mines comes from the Pratt bed, which is the next coal above the Mary Lee bed in the Warrior Basin. The coal is horizontal or slightly undulating, with thickness varying from 36 to 72 inches and averaging 50 inches.The method of mining is essentially room-and-pillar with modifications for mechanized sections. The mines produced approximately 1,100,000 tons with 2,328,309 man-hours exposure n 1929 and 900,000 tons with 1,697,436 man-hours exposure in 1930.Through the work of the safety department the entire personnel in the coal mines, as well as in other departments, makes safety an essential part of efficient operation.Both mines are gassy; Dolomite produces about 334,000 cubic feet and Mulga about 919,000 cubic feet of methane every 24 hours.The ventilation maps, two of Dolomite mines (figs. 1 and 2) and one of Mulga (fig. 3) give as much of the details of ventilation as is practicable to put on maps of such scale. As will be seen from these maps there are two main ventilating fans in Dolomite mine and two in Mulga mine and the general direction of the air travel is indicated by long arrows to fan 1 and short arrows to fan 2 in each mine. Each fan has a gas or steam auxiliary drive and each mine has a complete fan and power unit ready for operation in emergency.In Dolomite, recently taken data show that fan 1 exhausts 82,000 cubic feet of air per minute at 3.2-inch water-gage pressure, with an analyzed methane content of 0.15 per cent, and fan 2 exhausts 115,500 cubic feet of air at 3.8-inch pressure and 0.10 per cent of methane. In addition, a Capell fan at No. 2 air shaft is a standby or emergency unit.In Mulga recently taken data show that fan 1 exhausts 83,000 cubic feet of air per minute at 3.0-inch pressure and 0.18 per cent of methane, and fan 3 exhaust 119,000 cubic feet of air per minute at 5.4 inch pressure and 0.35 per cent of methane. Fan 2 at No. 2 shaft is a standby or emergency unit for the Mulga mine.The ventilation is on a split system in both mines. All part split and total returns are measured, sampled, and analyzed weekly, requiring one man two days each week. During December, 1930, 77 samples were collected and analyzed in Mulga and 78 in Dolomite. Two weekly reports covering part of December, 1930, are given here so that they can be studied to show control of ventilation in the Dolomite and Mulga mines. In the event that a split sample shows more than 0.50 per cent of methane, immediate steps are taken to lower the explosive-gas content. The reports follow:"

Mar 1, 1932

By I. M. London, G. P. Hatch

The Canadian Rare Earth Elements Network (CREEN) was formally launched at the Rare Earth Symposium at The Metallurgy and Materials Society of CIM (MetSoc) Conference of Metallurgists in October 2013. CREEN is an industry-led, multi-stakeholder network focused on providing collaborative solutions that will advance Canada’s REE sector to produce a significant proportion of the global production of separated critical rare earth products by 2018. The Network is industry driven by companies with REE projects under development and supported by universities, engineering firms, national and commercial laboratories, and government. CREEN aims to accelerate the development and delivery of timely solutions to technical and economic issues specifically facing Canada’s emerging rare earth sector. It will facilitate partnerships with other national and international organizations to leverage existing research initiatives. It will also support training and education to ensure that the needed qualified human resources are available to achieve the sector’s goals. CREEN membership spans the full rare earth supply chain and technical support organizations, from prospective producers, advanced project developers, national and commercial laboratories, engineering consultants, university researchers, and other innovators. This paper provides an update on CREEN's developing networking and project develop

Jan 1, 2014

By K. Saito, Y. Miyauchi, T. Nishi, Y. Kizu

At Tokushima Plant of Nippon Denko Co., Ltd. high-carbon ferromanganese is produced by the electric furnace method using lump manganese ores and sintered manganese ores manufactured from fine manganese ores. However, the distribution of manganese ores is significantly uneven on earth, and their characteristics considerably vary by ore type. It is known from experience that the production of high-carbon ferromanganese by the electric furnace method depends greatly on material ores. Therefore, to maintain stable operation in the electric furnace-smelting field, it is important to identify the characteristics of each type of material ores in advance. Thus, we evaluated the high-temperature electric characteristics of manganese ores using the electrical conductivity measuring system developed by ourselves and provided the standards for determining ores and blending ratio necessary for stable operation of the electric furnace based on the evaluation results. This time we worked for optimisation of the high-temperature electric characteristics of sintered manganese ores through modification of the characteristics because the blending ratio of sintered manganese ores in the electric furnace is high. The electrical conductivity of sintered ores having various chemical components in a high-temperature region (up to 1 550°C) was measured using our electrical conductivity measuring system and high-temperature electric characteristics evaluating method reported at INFACON 9. As the result of the measurement, we revealed that the high-temperature electric characteristics of the sintered ores depend on their chemical contents and the sintered ores can be modified to those having excellent high-temperature electric characteristics by controlling their chemical contents, so that the resources can be effectively used.

Jan 1, 2004

By Kevin Landey, Eric Gerst

Expanding blast patterns to near the limit of an explosives’ ability to do the necessary amount of work is a common practice to reduce drilling and blasting costs. Choosing less expensive explosives such as ANFO vs. emulsion, bulk product versus packaged product, etc. are also common cost savers. Both practices are only effective as long as the pattern geometries are accurately drilled. However, will pushing the limits on pattern sizes and explosive products produce consistent results at the face, minimize oversize, produce superior fragmentation, and improve crusher throughput? Sometimes, but no amount of explosives can overcome a poorly drilled pattern. Knowing the probable outcome of any changes in drilling and blasting is valuable in achieving success.

Jan 1, 2018

At the treatment plant of the Broken Hill South Limited, Broken Hill, the zinc concentrates, with water, are pumped out to a more or less level area, and stored in dams to dry by drainage and evaporation.In-the construction of these dams a clay bank is first thrown up around the proposed dam site. The concentrate and water mixture are then run in from the perimeter, the solids being continuously shovelled up to increase the bank height, while the clear water is drained off at the centre and returned to the treatment plant.These dams vary in size up to 57,000 sq. ft. in area; when completed the banks are about 12 it. high, and the capacity for the largest dams is about 350,000 cub. ft., say, 20,000 tons.The survey office is called upon for a monthly survey of these dams, generally three of which are in process of building or refilling. The puggy nature of the material prohibits walking beyond the bank of the dam, therefore the following method of estimating concentrates was evolved. No originality is claimed, but as the need is for a true survey, and the results have shown the accuracy of the method, a description is warranted. The dam site is first laid out into 10-ft. squares with a theodoliteand 150-ft. steel tape, the outside lines being placed about 15 ft. from the clay bank - 15 ft. is the maximum convenient distance from the bank for working with the levelling staff mentioned later.As the dam is rarely rectangular in plan, the outside points pegged out are not always the corner of a square, but are placed to give the greatest convenience in later work, that is to say, there may be triangles and irregular figures. The plan (Fig. 1) and photographs (Figs. 5 and 6) will give the general idea of the layout. At each point is driven a 3 ft. 6 in. round iron peg about 3 ft. into the ground. This peg is to permanently mark the point, and is not liable to be...

Jan 1, 1925

By Bryan Wilson

Background ?Nickel Rim South Mine started production ramp-up in Q2, 2009. ?The main dewatering pumps were put into use in August 2009. ?3 Feluwa?multisafe?positive displacement pumps ?1700m single lift pumping ?Reliability has been an issue due to the amount of slimes and fibers (from shotcrete) at the pumps. ?Critiqued internal dewatering system to solve some issues we were having with our sumps Findings 1.Much of the final dewatering system was not in place. a)Temporary pain. Difficult to say something is not working when the system was not yet in place as per design. b)Not enough capacity to handle slimes within the system. 2.Need to address issues with the final design: a)Ongoing costs: The end design has operating costs of $2.5 million b)Scoops in Sumps: The end design relies on scoops to be used for cleaning the sumps c)Slimes Recovery: The system mixes 3 different products in the sumps along with the fibers d)Pump repair costs: The existing Tsurumi pumps are too light duty for our slimes

Nov 1, 2011