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By K. N. (Mani) Subramanian

A 2.5 meter diameter column has been successfully used in a 100 tph flotation plant at the Harbour Lights Mine in Leonora, Western Australia, to produce a final gold bearing sulfide concentrate from the ore in a single stage. This pioneering application of column flotation cells to rougher stage was pilot tested using a 11 cm column, which demonstrated column's capability in rougher, scavenger and cleaner flotation stages. A hybrid circuit involving columns and mechanically agitated flotation cell s was adopted for the commercial installation. This paper describes pilot plant results, design of the plant flotation circuit, and early results of commercial operation.

Jan 1, 1988

By P. R. Busmann, D. J. Rogers

The Bureau of Reclamation's Syar Tunnel project included excavation of a 9.2 kilometer (5.7 mile) long, 3.6 meter (11.8 ft) diameter tunnel through gently dipping sedimentary rocks consisting of shales, siltstones, sandstones and limestone. The tunnel was supported full length with precast concrete invert segments and lightweight steel sets and lagging. Several world records for advance rate were set, including 57 meters (187 ft) in an eight hour shift and 127 meters (417 ft) in a 24 hour day. The tunneling system utilized a remanufactured and modified Robbins hardrock TBM and a 9,280 meter (30,450 ft) long, 61 centimeter (24 inch) wide, continuous conveyor system.

Jan 1, 1991

By K. S. Shivakumar, R. Bhima Rao, M. R. Patil

Liberation size can be estimated using various techniques such as grain counting, frequency curves, X-ray intensity and the mesh of grind. The present investigation deals with the estimation of the liberation size of graphite flake contained in a schistose ore from Shivaganga, India. It was observed that the flakes are liberated at from 75 to 150µm. The rougher flotation concentrate obtained after grinding the run-of-mine ore for 5 min contained 54% fixed carbon. This represented the first stage of liberation. After regrinding to <90 µm in the presence of sodium silicate and guar gum, a cleaner concentrate containing 82% fixed carbon was obtained.

Jan 1, 1998

By Levent Ozdemir, Roy H. Spitzer, Don W. Deere, John B. Blyler

This paper documents the construction of the Stanley Canyon Tunnel, the geologic conditions encountered, boreability of the rock, and the impacts of the conditions encountered on the construction. The 5.05 kilometer long (3.1 miles), 3.47 meter (11.4 feet) diameter, tunnel was driven through granites with a refurbished tunnel boring machine (TBM). Difficult ground conditions encountered included shear zones, high groundwater flows, and hard, tough, and strong rock. Detailed geotechnical studies during construction revealed that microscopic changes in the rock grain boundaries due to contact metamorphism, resulted in the hard boreability. Originally scheduled for five months, the tunnel construction required nearly three years, including periods of project shutdown.

Jan 1, 1995

By A. P. Chaves, A. Gomes

The cyanidation and adsorption processes at Fazenda Brasileiro mine were studied with the aim of increasing hydrometallurgical recovery. Technical evaluation of the processes consisted of (i) quantitative mineralogy of ore samples collected in different points of the circuit, and (ii) comparison of plant performance in the original (designed CIP) and in the modified (current CIP/CIL) circuits. An empirical correlation between process variables and gold grades in the cyanidation tailings was established. The suggested modifications in the circuit and in the operation conditions led to an increase in gold recovery, from 91 to 93.5%. Annual revenue is expected to show an increase of approximately US$ 1 million.

Jan 1, 1998

By Lawrence Pelham

The importance of fluorspar to the United States and the world and the role it plays in industry and society extend far beyond that which is suggested by its measured production and consumption quantities and declared value. Compared to many other industrial minerals, the annual worldwide consumption of 5 million short tons valued at less than $500 million are not impressive figures. Fluorspar is made special primarily because of its status as a critical and strategic commodity; it is essential for the processing of most steels and all aluminum. It also is the raw material for the production of elemental fluorine, which plays a part in uranium refining.

Jan 1, 1988

By Mollie Hunt, William Riley, Russ Downer, Kate Willa Brown Requist, Víctor O. Tenorio, Geoffrey Gill

One of the first activities after returning to the Moon will be finding sources of water and materials for the construction of human settlements and other infrastructure. There is evidence of the existence of deposits in the bottom of craters at the South Polar region and in flat areas around. Based on geological data from the Moon, a block model representing a deposit or icy regolith has been defined in the vicinities of Shackleton Crater, with unique characteristics of shape, thickness, and water contents. A mine plan utilizing surface mine modeling software for ore extraction from an open pit- type of excavation to a delivery point near a water processing facility is proposed, with monthly, quarterly, and yearly schedules. Production results, dashboard charts and progress of the topographic changes are also presented.

Feb 1, 2024

By J. F. Whelan, B. D. Marshall, Z. E. Peterman, J. B. Paces, L. A. Neymark

Observations of calcite and opal in cavities in the unsaturated zone at Yucca Mountain indicate that: 1) seeps are not regularly spaced in underground workings and not all fractures sustain flow, 2) many cavities represent sites of seepage that have remained stable for millions of years, 3) typically there is no evidence (such as dripstone) for seepage dripping into cavities from their ceilings, and 4) seepage is not likely to be greater than about 1 liter of water per year (per 5-m-long drift) based on calcite abundances observed in the ESF. This estimate of seepage is significantly lower than that used for performance assessment.

Jan 1, 2000

By Qiu Rongqing, Huang Kongxuan

This paper summarizes the results of treating arsenic­bearing refractory gold concentrates from six gold Mines of Chi­na by using bioleaching method and discusses the conditions of bioleaching processes. Results indicate that Thiobacillus fer­rooxidans T-3 Strain can intensely oxidize arsenopyrite, how­ever oxidation rate and degree differe considerably for different. During initial inoculation of 5 X 106 cell/ml. FeH contration generaly 4 -8 g/1. Sample size > 80 % - 3 20 mesh and pulp density 10 % ( w /v) and leaching time ,1 -- G clays, arsenic re­moval rate reached more than 80 % , Fe extraction ,10 - GO% desulfurization rate 30-45% after bacterial oxidation of 4-G days.

Jan 1, 1992

By Daniel P. Farjeat, Hector A. Canseco, Juan M. Schmitter

Since the early sixties, tunneling in the soft clay of Mexico City, has been done with the aid of open face shields and recently with compressed air. The use of pressurized shafts up to 1.5 kilograms per square centimeter, (147 kilo pascals) with vertical locks to launch the shields, have been used in two cases. After advancing almost 200 meters of tunnel, the same vertical locks were transformed into horizontal locks, to continue the work. Due to the high decompression times involved, it was necessary to install long locks, using the tunnel itself as part of the system. This article describes those cases.

Jan 1, 1981

By S. Michael Feroz, Michael J. Britch, Frank S. Buehler

The City of Portland is constructing the Columbia Slough Consolidation Conduit as a part of its commitment to reduce combined sewer overflows into the Willamette River and the Columbia Slough. Known as “The Big Pipe,” the conduit has a 3.7 m. (12 ft.) internal diameter and is 5,640 m. (18,500 ft.) long. Construction Segment 1 of the project includes 250 m. (814 ft.) of reinforced concrete pipe (RCP) installed by boring and jacking. Five separate crossings were constructed beneath Union Pacific Railroad tracks and Columbia Boulevard, an adjacent arterial roadway. This paper describes the design and construction of these bored and jacked crossings.

Jan 1, 1999

By Fathi Habashi

THE MINERAL monazite (µ?v??e?? = to be alone) is a rare earth phosphate containing some thorium and small amounts of uranium. It is widely distributed in the earth&apos;s crust. It occurs in small proportions in granites. Table 7-1. Mineralogical analysis of Rosetta black sands, U.A.R. (Nakhla, 1958). [Black sands Concentrate Augite 10.8 - Calcite 1.1 - Felspar 0.1 - Garnet 1.8 - Hornblende 2.4 - Ilmenite 50.7 8.0 Magnetite 15.3 Monazite 1.1 84.3 Quarz 7.3 - Rutile 1.0 0.5 Titanite 0.2 - Zircon 7.3 7.1 Others 1.0 0.1 100.0 100.0]

Jan 1, 1970

By Jacques L. Mauboussin

The EUROPEAN ORGANIZATION for NUCLEAR RESEARCH (CERN) has undertaken the construction of a LARGE ELECTRON POSITRON COLLIDER (LEP), near GENEVA (Switzerland). The facility includes the main 27 km long tunnelled ring, 18 shafts, 20 experimental caverns and many auxiliary galleries. Roughly 800 000 cu.m were excavated in the molasse at 50-140 m depths, using roadheaders for caverns and auxiliary tunnels and 3 WIRTH, 4.5 m diameter, fullface TBMs for the main circular tunnel. Each TBM performs 25-30 m/day. Provisory lining behind them uses either precast concrete elements or shotcrete. Works a e being carried out by a joint-venture of European contractors led by FOUGEROLLE (France).

Jan 1, 1987

By S. R. S. Sastri, K. K. Bhattacharya, K. S. Narasimhan

Experimental results obtained on the recovery of below 0.5 x 10-3m coal fines by flotation employing geometrically similar columns of 0.056m, 0.080m, 0.100m and 0.220m diameter have been presented. The hydrodynamics of such a unit as well as its performance have been related to operating parameters to establish optimum conditions. The results have further been analysed critically in the light of the known relationship on the behaviour of similar systems to assign reasons for the critical factors established in a bid to reduce the empiricism required to be followed in the scale up of such a unit.

Jan 1, 1988

By G. Barelli, C. Giusti, W. H. Langer

Natural aggregate – sand, gravel, and crushed stone – is the number one non-energy mineral resource in the world in terms of both volume and value. A plan for the sustainable development of aggregate resources can include: 1) policies and economic incentives to encourage identification and protection of potential resources, 2)efficient quarrying and processing of aggregate, 3) efficient use of primary aggregates, 4) greater use of recycled, waste, or substitute material, 5) inclusion of costs of all environmental impacts in price of material, 6) reclamation to beneficial secondary uses, and 7)identification of objectives, targets, actions, and sustainability indicators. Quarrying can also contribute to sustainable ecosystems through natural habitat reclamation.

Jan 1, 2003

By D. M. Larsen, N. D. King

Since start-up in 1985, the Cannon Mine has produced and shipped a 170-g/ton (5 oz/ton) gold flotation concentrate to various smelters for gold and silver recovery. Several processes have been investigated to economically produce dore&apos; at the mine site from the refractory concentrate. This paper describes laboratory and pilot scale test work used in the process design and engineering feasibility study of a 73-t/d (80 stpd) pressure oxidation and carbon-in-leach (CIL) facility. The designed pressure oxidation circuit utilizes a series of vertical autoclave units operating at 170°C (338°F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1994

By John F. MacDonald, John W. Critchfield

This paper describes the shield excavation of twin transit tunnels, through soft ground, in downtown Seattle. The tunnels are 6.5 m (21.25 ft) diameter and 1525 m (5000 ft) long. Initial support consisted of expandable precast concrete segments, followed by a final lining of cast-in-place concrete. Waterproofing was provided by a PVC membrane installed between the initial support and the final lining. During the course of the excavation a variety of methods were used to control the ground and limit settlement. These included deep wells, vacuum well points, eductor wells, chemical grouting, compaction grouting, jet-grout underpinning, and extensive instrumentation.

Jan 1, 1989

By Jon Y. Kaneshiro, Donald W. Scapuzzi

The primary purpose of the Prototype Installation Facility (PIF) for the Superconducting Super Collider (SSC) in this conceptual design was to test the magnets and other physics equipment. PIF was located in the northwest quadrant of the SSC 54 mile (87 km) main ring and consists of the first segment of tunnels, approximately 17,060 lineal feet (5.2 km) of 12 foot inner-diameter (ID) (3.7 m) tunnel, three 250 ± foot (60 m) deep shafts, connecting tunnels, and associated niches and alcoves. PIF would be the first portion of the main ring collider tunnel to be constructed. The geology, underground excavation conditions, underground facilities, and contractual considerations are discussed.

Jan 1, 1991

By Richard Druesedow, Richard Ray

Tests at the VP-5 "C" shaft fan installation of Island Creek Coal&apos;s Virginia Pocahontas Mines were performed to determine pressure drop due to the design of the shaft collar and ductwork leading to the fan. Data from the test locations in the shaft, duct and fan indicate significant pressure losses in the system as well as significant turbulence in the flow. Data taken with a 3-D probe in the fan annulus confirmed the importance of using this type of instrument in turbulent flow applications. This data will be later supplemented with data taken after addition of turning vanes in the 45° turn adjacent to the fan inlet.

Jan 1, 1993

By Leif A. Nordell, Philip E. Freeland

A paper discussing specification, methods, situations and results encountered in underground phase construction of the Rocky Mountain Pumped Storage Project near Rome, Georgia. The scope of work included excavation, rockbolt/shotcrete/wire mesh primary support and cast-in-place concrete lining of the (1) 216 m, top flared shaft, connecting 1.57 radian elbow, and 590 m tunnel to a 10.67 m finished diameter; (2) complex double bifurcation section; (3) excavation, support, installation and backfill concrete for three parallel, 135 m steel penstocks of 5.79 m finished diameter; (4) construction of a 43 m diameter reinforced concrete intake/discharge structure atop the shaft.

Jan 1, 1985