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By C. R. Jenkins, G. S. Taylor

Three sedimentation ponds had their performance evaluated before and after installation of modifications. Each pond had a floating baffle installed, two had siphon outlets, and one had a floating outlet device. Baffles inhibited short circuiting, and the outlet devices retarded flow following a rainfall event and drained the pond, creating a large storage volume to maximize detention time. Total suspended solids and settleable solids tests were measured on samples of influent and effluent to evaluate pond performance. Particle size analyses were conducted on samples containing measurable amounts of solids. Performance improved in each pond, with baffles providing the major improvement.

Jan 1, 1987

By Rick Sarkisian, Greg Girardey, David Keech

The Conveyor Equipment Manufacturers Association (CEMA) specification B105.1 "Welded Steel Conveyor Pulleys" adequately defines pulley assembly standards for light material handling applications. However, most mining applications demand pulleys of higher reliability and load capacity than that offered by CEMA standard pulleys. Various sources have published specifications for "Engineered" conveyor pulleys. Typically, these specifications require T-section type pulleys applicable to operating belt tensions exceeding 439 N/mm (2,500 lb./in.). This paper examines the application of CEMA standard pulleys, T-section pulleys and also a mining duty pulley design. The mining duty pulley fills the void between CEMA standard pulleys and T-section pulleys and can eliminate the high cost and long lead times associated with T-section type pulleys.

Jan 1, 1998

By A. I. Kalugin, A. A. Abramov, D. E. Kozlov

As a result of thermodynamic analysis of a mineral-sodium, oleate-water system, flotation and adsorption tests at various pH values, and sodium oleate concentrations, it has been established that due to regularities of phosphate-containing minerals (fluorapatite, hydroxyapatite, carbonatapatite) flotation cannot be explained by the formation of alkali-earth metal oleates on their surface. This paper presents a novel theory that connects optimal conditions for mineral flotation with zero charge of its surface, which can explain the regularity of minerals flotation observed. The quantitative physicochemical flotation models developed based on the theory are suitable for improving industrial processes, conditioning of recycling waters, and application in automatic control systems at the plants. Key words: apatite, oleate, flotation, modeling, control, and regulation.

Jan 1, 1999

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996

By Gary A. Almeraris, Thomas F. Peyton

This paper chronicles the mining of a main interceptor sewer through a residential neighborhood for the MWRA's Boston Harbor clean-up. The Wellesley Extension Sewer Tunnel consisted of 490 m (1600 ft) of rock tunnel, 107 m (35V ft) of mixed face and 336 m (1100 ft) of softground. The tunnel was located 4.6 m (15 ft) below water table and passed directly beneath six buildings with as little as 7 m (23 ft) of cover. In addition, the tunnel ran parallel to and within 4.6 m (15 ft) of an existing sewer tunnel with flows up to 187,5 million liters (50 million gal.) per day. The rock encountered by the tunnel was comprised of gramodiorite, amphibilite and diabase. The soils which passed through the tunnel face consisted of tills, sands and non-cohesive plastic silts. The techniques developed and the equipment utilized to successfully mine this complicated ground are described.

Jan 1, 1991

By J. H. Fewings

The rapidly escalating capital costs for new projects, or extension of existing projects, has placed greater emphasis on maximum use of existing resources. Thus, when increased grinding capacity was required to achieve metal production from lead-zinc ores a number of alternate approaches were studied. The most cost effective way of achieving the required 5% increase in grinding circuit capacity was to install upgraded instrumentation and computer control of grinding - Fewings, Wickham and Wiseman (1). Once the computer installation cost had been borne by the financial returns from that project, other projects involving computer control were economically viable on an Incremental cost basis. These Included centralised control of tailings thickening and return circuit water distribution, centralised control of the crushing plant and use of the computer as a data processor for an on-stream analysis system for flotation slurries.

Jan 1, 1979

By J. C. Ashby

Electric utility response to certain amendments of the Clean Air Act has resulted in a production of several types of alkaline coal combustion byproducts (CCB). Alkaline combustion byproducts are gaining increasing usage for acid mine drainage (AMD) mitigation as research leads to a better understanding of their beneficial applications. Since January 1997, Mettiki Coal has been injecting alkaline flue gas desulfurization material from Virginia Power's Mt. Storm Unit No. 3 wet limestone scrubber into abandoned portions of the active Mettiki Mine.

Jan 1, 1998

By B Faulkner, M. Weinecke

In 1997, Sveciala began a program to develop a process to convert waste tires into valuable commodities. A review of numerous approaches revealed shortcomings that were process related or mechanical related, while some of the approaches emphasized he production of low-value products. A market study revealed that a process that could produce a good grade of carbon black would be economically feasible. This paper discusses the laboratory and pilot-plant development and commercial plant design of such a process.

Jan 1, 2002

By R. D. Miller, L. Schulte, J. Davenport, D. W. Steeples

Shallow seismic reflection methods were successfully used to delineate the subsurface extent of roof failure associated with the dissolution mining of a 120-m (400 ft) deep and 60-m (200ft) thick salt bed in central Kansas. Surface subsidence at North American Salt's Hutchinson, KS, salt-dissolution well field represents a potential risk to surface structures and transportation facilities. Three intersecting common depth point (CDP) seismic reflection profiles, targeting the subsurface around an actively subsiding sinkhole, possess sufficient resolution to delineate the horizontal and vertical extent of subsurface rock failure associated with the subsidence. The three seismic profiles showed a disturbed subsurface area 90 to 105 m-diam (300 to 350 ft-diam) at a depth of between 60 to 75 m (200 ft and 250 ft). Confirmation drilling verified the interpretation of the seismic data. The seismic reflection method has the potential to resolve disturbed subsurface areas greater than 23 m-diam (75 ft-diam) at this site.

Jan 1, 1994

By David R. Baughman, John C. Gathje, K. C. Oberg, Gary L. Simmons

Santa Fe Pacific Gold Corp. conducted pressure-oxidation pilot plant studies on refractory carbonaceous gold ores from the Twin Creeks Mine in Nevada. The tests were conducted at Hazen Research Inc., Golden, CO, during 1993 and 1994. Laboratory investigations using CIL cyanidation after batch pressure oxidation demonstrated gold recoveries of 90% to 95%. However, pilot plant testing showed that several of the same ore types responded very poorly, with gold extractions of only 45% to 75%. Plant testing was suspended for approximately four months while extensive research was conducted to determine why these ores responded poorly and to identify potential solutions. This paper describes the batch and pilot plant test results, the extensive research activities that eventually identified the cause of the gold recovery problem and the final semicontinuous and continuous pilot plant operations that confirmed possible solutions. Final pilot plant results showed gold recoveries that were consistently greater than 90%.

Jan 1, 1999

By Gary L. Simmons

Many large (refractory) sulfide gold resources exist in Nevada and other parts of the world that are not amenable to conventional flotation concentration using air as the flotation gas medium. Over the past five years Santa Fe Pacific Gold Corporation (SFPG) has investigated flotation process options to economically treat refractory ores and resources of this type at its Lone Tree and Twin Creeks mines. Conventional flotation technology applied to the original high-grade gold resources at Lone Tree and Twin Creeks was initially unsuccessful. Review and analysis of auriferous (gold-bearing) iron sulfide mineralogical characteristics and flotation ..:hemistry provided a fundamental understanding that led to the development of a new flotation process that SFPG refers to as N2 TEC. This paper discusses the development of this technology and compares N TEC results with conventional flotation practice.

Jan 1, 1997

By J. Duarte Neto, V. M. Torres, A. Viana, G. S. P. Pereira, P. M. Andrade

There are technical and commercial limitations to using high fluorine copper concentrates in industrial copper smelters. The presence of more than 1,000-ppm fluorine affects the sulfuric acid units generally integrated to copper smelters. Price penalties are normally applied to copper concentrates with high fluorine contents. Several process alternatives to resolve this issue were studied at the Companhia Vale do Rio Doce (CVRD) Technology Center, Santa Luzia, Brazil. These alternatives included modifications to conventional sulfuric acid plants so that they can use high fluorine concentrates; removal of fluorine-containing minerals by flotation using depressants; selective leaching of fluorine minerals; and sulfuric acid leaching of the copper concentrates. As a result of this research, a hydro¬metallurgical process to remove fluorine and upgrade copper concentrates was developed by the CVRD.

Jan 1, 1999

By S. L. Jung, T. L. Nichols, K. Prisbrey

The problem was to evaluate the on-line detection of rock properties through acoustic emission sensors. Acoustic emission sensors, when attached to crushers, grinders, and roof bolters, are robust, economical, and relatively maintenance free. Our objective was to relate acoustic emissions to rock fracture mechanisms, including micropore closures, linear elastic deformations, and crack propagation. We evaluated acoustic emissions from steel jacketed rock cores during indentation tests. In addition we attached sensors to the rotating shaft of a rock bolter drill. A back propagation neural network "learned" rock fracture characteristics and rock type with 99% classification accuracy. A neural network's calibration and computational abilities suggest better acoustic emission sensor capabilities.

Jan 1, 1993

By Robert J. Guardia, James Rustvold, Robert A. Robinson, Christopher A. Robertson

In 1999, the Bonneville Power Administration (BPA) replaced approximately 730 m(2,400 ft) of damaged 42- and 36-inch concrete pipe by microtunneling Permalock pipe through sand and partly below groundwater. Microtunneling saved $3.5 to $5 million from the estimated cost of a shored excavation and avoided a railroad and contaminated valley fill. A slurry microtunnel boring machine (MTBM) was used for two segments where groundwater was present and a wheel excavator MTBM was used for one segment where groundwater was not present. This paper describes design and construction of this project that was completed within 2% of the bid and engineer’s estimate.

Jan 1, 2001

By D. E. Ranta, Neil D. O’Donnell, Thad B. Ostrowski

Ore reserve estimation at the Syncrude Canada Ltd. open-pit oil sands mine in Northern Alberta has evolved since the project's inception. Early techniques followed a conventional petroleum reservoir analysis format, with relatively widely spaced drill holes and semiquantitative grade data. Experience has developed a more standard mining approach, including classification of geological materials by both lithology and sedimentary origin, timely and multi-purpose drill holes, precise analytical data, empirical recovery factors, a computerized geological data base, and an orebody block model. Future efforts will involve enhancement of existing techniques, use of geostatistical algorithms, quantification of confidence limits, and improved control of the ore model by geological parameters.

Jan 1, 1992

By David G. Rasmussen

With low commodity prices and continuing high operating costs, the mining industry must revise planning and operating to take advantage of every tool available. Conveyors operated within open pits are such a tool. Dravo engineers have designed conveyor systems into pits as prime movers in unique situations. Three cases are presented with economic comparisons made to conventional truck haulage. Increasing energy and labor costs tend to make conversion of prime haulage from trucks to conveyors. Long term pit planning and scheduling reduce the effects of conveyor inflexibility.

Jan 1, 1983

By M. H. H. Mahmoud, T. A. El-Barbary, E. A. Abdel Aal, I. A. Ibrahim, A. K. Ismail

Fertilizer-grade phosphoric acid with a P2O5 concentration of 50% should contain less than 1.5% Fe2O3, otherwise, the P2O5 water solubility of the fertilizers prepared from high-iron acids will be low. High-iron Egyptian phosphate concentrates fromAbu-Tartur and Sebaiya- West were leached with sulfuric acid and recycled phosphoric acid to produce 50%-P2O5 phosphoric acids containing 4.0% and 2.7% Fe2O3, respectively. The high iron contents were reduced to the industrially accepted limit of 1.5% Fe2O3 by precipitation with potassium sulfate. The factors affecting the effi¬ciency of the precipitation process, e.g., temperature, time and K2O/Fe2O3 ratio, were systematically studied, and the optimum conditions were achieved. The clarification of the prepared phosphoric acid from iron-containing sludges was also investigated by varying the time and temperature. The utilization of the separated sludges as fertilizer and recovery of P205 by pulping in water were also evaluated.

Jan 1, 2000

By G. Righettini, P. Mousset-Jones

Diesel powered vehicles have made underground mines more efficient, but with the advent of DPM regulations, in most cases, extra ventilation and/or engine emissions control technology will be required. Using fuel cell powered vehicles will not need these measures to be taken. Nine US underground mines of varying production rates and mining methods were studied to determine possible ventilation reductions if their diesel fleets were replaced with identical fuel cell powered vehicles. Factors that might limit ventilation reductions, such as heat and the effects on other pollutants were determined for each mine. The ventilation cost savings and other benefits of fuel cell vehicles show that when they become commercially available they have the potential of being viable alternatives to diesel vehicles.

Jan 1, 2004

By Steven W. Hunt, Gregory C. Baker, Glen J. Rorison

Microtunneling methods were utilized beneath pile-supported clarifier basins to replace settlement damaged sludge drain lines at the Jones Island Wastewater Treatment Plant in Milwaukee, Wisconsin. To minimize the risk of blockage and expensive recovery of a microtunnel boring machine against pipe piles or construction debris, a Soltau RVS 80 was utilized. This machine allowed the alignment to be initially bored with guided 114-mm diameter rods to ensure proper alignment and lack of obstructions. Casing pipe was then installed by jacking 1-m long, 305-mm diameterclay pipe along the rods and behind an auger head. This case history also discusses how 2.4-m diameter precast concrete pipe was used as a one-pass sinking caisson for workshafts and new cleanout manholes.

Jan 1, 2001

By D. Triantis

This paper presents the results of laboratory experiments for the detection of electric signals from Fiber Reinforced Polymer (FRP) sheet samples which have undergone a temporally increasing loading of bending type up to fracture. Electric signals that were recorded while the sample was subjected to bending are referred from now on as Bending Stimulated Currents (BSC), in order to differentiate them from the relevant signals emitted by materials that suffer uniaxial compressional stress. The latter signals are referenced as Pressure Stimulated Currents (PSC). BSC emitted from FRP sheet samples presented here, were recorded after applying three successive load steps to samples. The increase rate of applied stress was about 0.15kN/s. Initially starting from low load values to higher load values until the FRP sheet reaches at a state just before its failure. The BSC records from FRP samples are compared to equivalent recordings from cement mortar beam and distinguishable differences are discussed.

Jan 1, 2006