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By D. C. Bailey, D. I. Hodson

Paper presented at the annual joint meeting of the IMM and IMinE held in Harrogate, 31 January 1991. The Neves-Corvo copper-tin mine is the highest-grade large-tonnage copper operation in the world and is now arguably the most significant producing base-metal mine in Europe, rating in the top ten world producers of both copper and tin. A description is given of the initial exploration work and the development of the project from the orebody discovery in the Iberian Pyrite Belt of southern Portugal in 1977 to full operating capacity in 1990. The chronological account includes discussion of the main organisational, financial, technical and environmental decisions and of the various difficulties encountered, and the challenges of the future are identified. The project was brought in on schedule and within budget

Jan 1, 1991

By Youliang He

Twin-roll casting is an integrated casting and rolling process that involves the continuous solidification of a melt and the plastic deformation of the solidified metal between two rotating rolls. Computer modeling is a valuable tool to help engineers understand the metallurgical process during twin-roll casting. However, commercially available software can only model either the fluid flow/heat transfer of the melt or the plastic deformation of the solid, but not both. In this study, an object-oriented finite element program was developed to simulate the steady-state fluid flow, solidification and plastic deformation of an A7,31 magnesium alloy in a horizontal twin-roll caster. The melt, the mush zone and the solid were treated as a generalized Newtonian flow in an Eulerian reference frame and different constitutive equations were employed to describe the material behaviours. The effect of operational parameters on the solidification process was discussed based on the simulation results.

Jan 1, 2010

Copper Extraction from Scrap Cables by Biotechnological Means

Sep 13, 2010

By R. V. Ramani

Procedures have been developed which permit determining in either existing or new mines the optimum diesel equipment deployment schemes and the effect of. diesel exhaust on mine-air quality. Specifically, the following areas are covered in the report: 1. Description of diesel deployment schemes in four underground coal mines that were visited is provided. 2. Description of the analysis procedure to determine the number of shuttle cars required to maintain maximum theoretical continuous miner (or loader) production rates in typical room-and-pillar mining systems and of exhaust contamination resulting from the deployment of diesel powered shuttle cars are provided. Sensitivity analyses to determine the effect of changes in input variables on production and contaminant concentrations are also discussed. 3. Description of the analysis procedure to develop the locomotive operating parameters is provided. Assessment of both production performance as well as estimates of the magnitude of diesel exhaust contamination of the mine air are also made. 4. Recommendations for extensions of this research are outlined and include developing and testing procedures for 1) determining equipment duty cycles for the diesel equipment, and 2) studying the exhuast contamination of mine air on the basis of these duty cycles.

Jan 1, 1978

Since March 28, domestic producer prices on 99.5 percent aluminum ingot have been at 5l¢ per pound. Dealers in this same time frame have held ingot quotes at 49¢-50.5¢ per pound. COBALT: Imports from southern Africa in 1976 constituted 73 percent of total cobalt imports. Moreover, the United States is 98 percent dependent on imports of cobalt. For this reason, the Bureau of Mines is closely monitoring developments abroad to ensure an advance notice of any possibility of a shortfall in supply. Included in these imports were those from Zaire (41 percent directly from Zaire and 15 percent via Belgium-Luxembourg), Zambia (11 percent), and Botswana (6 percent). Also being closely watched are industry stocks.

Jan 1, 1977

By Katsuyoshi Kondoh

The utilization of silica particles originated in rice husks as reinforcements of magnesium composites was discussed. By using the solid state reaction of rice husk silica particles with magnesium powder, P/M magnesium based composites dispersed with the magnesium silicide (Mg2Si) and magnesium oxide (MgO) were fabricated. High-purity silica particles were originated from rice husks, one of the major agricultural wastes, via the citric acid leaching treatment and combustion in air. The effects of the silica particle characteristics such as size, crystalline and porous structures, on the reactivity of silica and magnesium to synthesize Mg2Si intermetallic were discussed. Amorphous silica was more useful for this reaction than crystalline one. The reactivity of rice husk silica was superior to that of the conventional mineral silica particles because of not only its amorphous structure but the larger specific surface area due to their pore structures. In the case of the green compact of the mixture of the rice husk silica and Mg powder, the silica particle size was not effective on the reactivity because the coarse particles were fractured into fine ones by cold compaction. The distribution of Mg2Si intermetallics of magnesium powder composites consolidated by SPS process was investigated by XRD and SEM-EDS analysis. Their mechanical and physical properties were also evaluated in detail.

Jan 1, 2009

By Christopher J. Bise

INTRODUCTION The control of nuisance water in a mine is extremely important; left uncontrolled, nuisance water can have a severe effect on haulage, ventilation, production, and the health and safety of miners. To control water in mines, a four-step process is followed: (1) prevention, (2) collection, (3) transportation, and (4) treatment. This chapter will be devoted to the collection and transportation of mine water because prevention is usually dictated by pre-mining conditions and initial planning, while treatment is variable and highly site specific. A mine drainage system is nothing more than a collection of gathering points (sumps), machines that impart energy to the fluid (pumps), transportation ducts (pipes), and control devices (fittings, valves, etc.). A pump does not pull the fluid up the suction pipe; atmospheric or external pressure pushes the liquid up the suction pipe to the pump. All references in this chapter will be to centrifugal pumps, due to their popularity for mine drainage. PUMP CHARACTERISTIC CURVES The performance of a pump is plotted on a graph as an indication of its characteristic. To develop the data points, a test facility similar to that shown in Fig. 1 is established. The calibrated Venturi meter is used to measure quantity, the Bourdon gage measures pressure, and the wattmeter measures power input. Various discharge pressures are obtained by throttling with a gate valve in the discharge pipe. Quantity and power are measured at each of these pressure levels, giving the necessary data for plotting the characteristic curves. Fig. 2 shows a typical characteristic curve for a centrifugal pump. Notice that pressure is measured as so many feet of vertical water column above the outlet level, or head. Knowing the quantity (in gallons per minute), head (in feet), and power input (brake horsepower), the pump's efficiency can be plotted based upon the following relationship:

Jan 1, 1986

By M. I. F. S. Cruz, R. Pedersen, F. J. A. S. Barriga, A. Dias, A. F. A. Marques

"Underwater hydrothermal vents are known since the 1970s and their importance for the global economy is growing as new discoveries and new assessments are made each year (Cherkashov et al., 2010; Corliss et al., 1979). The similarities of seafloor massive sulfides, representing the younger versions of the well exploited on land volcanogenic massive sulfides, bring an increased awareness to the potential of the sea (Ajan G. Galley, 2007; Hannington et al., 2011; Herzig and Hannington, 1995). The Arctic Ocean presents itself as an opportunity to study new interest areas and numerous hydrothermal systems (active and inactive) were discovered along the Arctic Mid Ocean Ridge (AMOR) (Pedersen et al., 2010b). The Mohns ridge is an ultraslow spreading ridge of the AMOR (Vogt, 1986) where two hydrothermal vent sites were recently discovered, the Jan Mayen and the Loki’s Castle (Pedersen et al., 2010a; Pedersen et al., 2009; Pedersen, 2005). Here we compare these two Arctic hydrothermal systems, which represent two well-differentiated end-members of hydrothermal fields in the region."

Sep 1, 2014

By Roy F. Abernethy

All samples tested showed some loss of heating value for the 5-month period under all 4 storage conditions. The losses increased as the time of storage increased, with the pan-storage samples showing somewhat greater losses than those in cans. The individual daily analyses for the first 2 weeks and the analyses every other day for the third and fourth weeks of storage vary within the approximate tolerance of the test for heating value. During the first 2 months of storage the changes in heating values were not Significant for the samples from Pennsylvania, Indiana, and Colorado. The Ohio coal indicated some loss by the end of I month, which increased to a value measurable with certainty by the end of 2 months. These data show that (1) small changes may occur even to samples in closed cans and (2) the laboratory sample should be handled as expeditiously as is practical until the analysis is completed. The statement by the ASTM that "If the B.t.u. determination is an important consideration in the sale of coal, the time elapsed between sampling and analysis shall not exceed 30 days,"3/ is quite adequate for 3 of the 4 coals tested. The change in the Ohio coal stored for 30 days is merely indicated and could not be determined with certainty by the techniques normally employed. The data on free-swelling indexes determined on can samples, after 30° C. air drying, show that only the Indiana coal lost more than one unit in free-swelling index number in 120 days. No significant changes were observed with the samples from Pennsylvania, Ohio, and Colorado in the 5-month period.

Jan 1, 1958

By Bolestaw A. Ktosihski

Preloading of bored pile bases by grouting is an effective way of reducing foundation costs. The bearing performance of a pile may be considerably improved. Various techniques and devices are used. Preloading of a pile base by a special grouting installation is preferred. The grouting device consisting of a U-shaped grouting tube with sleeves and a plastic membrane, separating the tube from the pile concrete, has well proven in Polish practice. The preloading may raise the pile design loads by as much as 30%, and increase their stiffness by 50%, in suitable conditions. The preloading equalizes the deformability of piles in a foundation or a structure. Examples of the base preloading use and load tests of base grouted piles are presented.

Jan 1, 2006

By Joe Roby

Rolling disc cutters are the business end of hard rock and mixed face tunnel boring machines (TBMs). Since their first successful employment on a TBM over fifty years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates higher and cutter costs lower than ever before, proving the value of investment in cutter development. This paper describes recent improvements in disc cutter components including cutter ring materials and processing, as well as improvements in lubricants, bearings, seals and cutter condition monitoring. These developments have resulted in more reliable cutters capable of operating in a wide range of geological conditions. Ultimately these improvements result in a better value for both contractors and project owners.

Jan 1, 2008

By Frederic M. Langevin

?? Introduction ?? LaRonde ?? History of Seismicity and Rockbursting ?? November 27th 2002 Rockburst ?? April 1st 2006 Rockburst ?? December 11th 2006 & January 11th 2007 Rockbursts ?? Seismic Risk Management Plan ?? Conclusions ?? Located in Northwestern Quebec (Can.) ?? In operation since 1988 ?? Reserves at Shafts #1 and #2 depleted ?? Production now comes entirely from Penna Shaft ?? Deepest single-lift shaft in the western hemisphere (2240 metres) ?? 7300+ tonnes per day ?? 2007 Reserves (proven & probable): ?? By-products: Ag, Cu, Zn ?? Sinking #4 Shaft (LaRonde II winze)

Feb 1, 2008

By P. S. G. Leon

One of the most difficult areas in concession contracts in resource-rich developing countries is achieving an equitable balance between the interests of investors, host states and, increasingly, mine and near mine communities. While some countries in the Andean region have resorted to outright or creeping expropriation of natural resource contracts under the guise of resource nationalism, others such as the Democratic Republic of the Congo (DRC), have claimed international best practice in the review (and setting aside) of important concession contracts.

Jan 1, 2011

By J. D. Steenkamp, G. E. Williams

Keywords: Ilmenite, titania slag, pig iron, rutile, zircon Located on the eastern shores of South Africa, 180 km north of Durban, Richards Bay Minerals (RBM) produces approximately 2.0 million metric tonnes of product annually making RBM a leading producer of titania slag, high purity pig iron, rutile and zircon. Heavy minerals are extracted from the nearby dunes by dredging and concentration on a floating gravity separation plant, followed by separation of the ilmenite, rutile and zircon at the mineral separation plant located at the smelter site. The ilmenite is processed through an oxidizing roast followed by magnetic separation and is then partially reduced to an 85 per cent TiO2 slag in one of four six-in-line a.c. electric arc furnaces. The slag is milled and then classified into two product sizes suitable as a raw material for both the sulphate and chloride pigment processes. The high quality iron produced during the reduction process is further processed to produce various grades of low-manganese iron. Around 95 per cent of the products are exported, yielding a world market share of about 25 per cent of titania slag, rutile, high quality pig iron, and zircon.

Jan 1, 2006

By G. D. Buson

Driefontein Consolidated Limited has a proud history in the South African gold mining industry dating back to March 1945 with the formation of the West Driefontein Gold Mining Company. The reclamation gold plant at West Driefontein was originally built as a uranium recovery plant in 1970. With the collapse of the uranium oxide yellow cake market, the uranium plant was closed in 1988and successfully converted into a gold plant, recovering gold from repulped tailings dams1. The West Driefontein Reclaim plant utilized milling, leaching, conventional rotary vacuum filtration and cementation to recover the gold at a rate of 200,000 dry tons per month. The No. 1 tailings dam (at a head grade of 0.8 Au g/t) began to near the end of its life during 1996, and the next slimes dams to be treated, the No. 2tailings dam (at a lower head grade of 0.56 Au g/t) was found too marginal for reprocessing using the filtration technology. Alternate technologies were investigated, particularly the carbon-in-pulp (CIP) plant based on the Anglo-American Corporation (AAC) pump-cell technology at the Vaal Reefs Exploration and Mining Company?s East gold plant which was operating profitably at lower head grades2. The AAC pump-cell technology is based on the carousel mode of operation2. The suitability of CIP technology for the West Driefontein Reclaim plant was investigated using a pilot plant pump-cell supplied by Kemix The data gathered were utilized in sizing a full scale AAC pump-cell plant. This plant was motivated, built and commissioned on the 22nd of November 1996. Incorporating 6 eighty cubic metre AAC pump-cells. The West Driefontein Reclaim plant initially treated repulped slimes dam material. A subsequent change of feed material to current arisings (from the main gold plant) occurred in1997 in order to convert mills for waste rock treatment. Currently the reclaim plant treats a combination of current arisings and waste rock (milled at the reclaim site). The new CIP plant replaced twenty-seven rotary vacuum filters. A comparison between the filters and CIP in terms of operating costs was undertaken, as well as a performance analysis of the CIP plant to determine its flexibility in terms of variation of the throughput, pulp density, gold input, leaching efficiency prior to CIP, and the rate of carbon movement.

Jan 1, 1999

By A. E. Hall, R. N. Taylor, J. G. Taylor

The introduction of tunnel-boring machines to South African gold mines has created problems and challenges which accompany any new technique. This paper describes the experience gained in this field, especially in the design and erection of a tunnel borer and in boring and environmental conditions.

Jan 1, 1978

By Frederic P. Dewey

This old and well-known method of determining silver is, in bullion work, so far superior to the furnace-assay that it is looked upon with reverential awe by many, if not by most, users, and its ease of execution, with proper equipment, commends it highly where much commercial bullion work on silver is required. The method is so thoroughly well known that a description of it here may seem to be unnecessary, but many thousands of determinations are annually made by it in the U. S. Mint Service and its practice is there reduced to an art. This is necessary both for the sake of economy of time, and because high-grade work with it requires constant practice. It is useless for a person who uses it only occasionally to expect to attain high accuracy with it, without spending more time upon a detemination than is warranted in a busy commercial laboratory. It is always employed in the Mint service whenever possible, but its chief field is in the determination of silver in standard silver (ingots and coin), which is 900 fine in silver and 100 fine in copper, and I shall first briefly outline its use on this metal and then take up various points in detail, especially as related to the accuracy of the results obtained. For this determination 1,115 mg. of standard metal are weighed and transferred to a glass-stoppered bottle, the metal is dissolved in nitric acid, and 100 cc. of a standard solution of NaCl run in. The bottle is then vigorously shaken and a measured portion of a decimal salt solution added, and again shaken, if necessary. These operations are repeated until the silver is precipitated. Standard metal being 900 fine, 1,115 mg. should carry 1,003.5 mg. of silver, which is a convenient figure to work with.

Jan 1, 1914

By Frank Parrish

History and performance data of 17 water-injection projects in Cooke and Grayson Counties in north Texas are presented for the purpose of studying and comparing operating practices and oil-recovery techniques. Water is injected into Strawn and Canyon sands of Pennsylvanian age. The principal formation flooded is the Strawn, which ranges in depth from 725 to 6,900 ft in the projects covered. Estimated ultimate recoveries range as follows: Primary, 22 to 494 bbl per acre ft; and secondary; 63 to 296 bbl per acre ft. These figures represent the following percentages of original oil in place: Primary, 10 to 46 pct; and secondary, 8 to 23 pct. Shallower projects; 725 to 1,500 ft in depth, had higher average primary and secondary recoveries than did deeper projects. Crude-oil gravity, which ranges from 20° to 45° API, was not relatable to yield of secondary recovery oil. Analysis of the data indicates that five-spot injection patterns will yield the highest percentage of oil remaining at start of flooding; that is, 28.8 pct for five-spot injection patterns, compared with 20.8 pct for line-drive patterns and 11.6 pct for random patterns. Waterflooding in this area appears to be very successful. Secondary recoveries of most projects are expected to nearly equal primary recoveries.

Jan 1, 1963

By Larry Rayburn

In the spring of 1999, construction commenced on the new Steelers Football Stadium in downtown Pittsburgh, Pennsylvania. Richard Goettle, Inc. (RGI) was the successful bidder to install the specified augercast piles for the foundation package. Description - Pittsburgh Steelers Stadium The new stadium will house the Pittsburgh Steelers Professional Football Team. It is widely believed that if a team is provided with a modern playing facility, that a winning season will ensue (Not always the case). The new stadium location is on the north side of Pittsburgh on the Ohio River, and just downstream of the confluence of the Monongahela and Allegheny Rivers. The site is west of existing Three Rivers Stadium. The Three Rivers Stadium was built during the late sixties and housed both the Pirates Baseball and Steelers Football Teams. The Public Auditorium Authority elected to replace this outdated stadium with two new stadiums, one for each professional team. The landmark stadium was imploded in February of 2001.

Jan 1, 2001

A variety of environmental financial assurance instruments are in use across the globe. This paper reviews some of the more common forms currently used in New Zealand, Canada, USA and Australia. In order to be effective, the form of assurance instrument selected needs to be aligned with a countryÆs specific environmental objectives, geography and political climates and also allow for a healthy investment climate. Industry and Government both have a strong interest in ensuring financial assurance criteria meet these objectives.   Recently Golder Associates have been involved in financial assurance assessments for various mining and quarrying companies across the South Island. Multiple stakeholders and regulatory agencies can make the setting of effective and fair financial assurance criteria a complex exercise for both regulatory agencies and industry.  The author relates experience gained in assessing financial assurance under current New Zealand legislation (RMA, 1991), effectively dealing with issues such as ôdouble bondingö and overviews potential approaches to dealing with transitional issues for historic and existing operating mine sites.

Jan 1, 2006