Search Documents

By Joseph T. Coe, Siavash Mahvelati, Alireza Kordjazi

This paper introduces recent advances in stress-wave NDT systems for use in assessments of in-service foundation integrity and drilled shaft construction. The primary results of the laboratory experiments are very promising, as the acquired image was capable of differentiating changes in pile cross section as low as 0.3 cm. The preliminary results with the same hardware components on a relatively large scale cemented sand model were also promising. A brief overview is provided of both systems including hardware, survey methods, and data processing techniques, followed by a discussion on application of the results to QA/QC of deep foundations. INTRODUCTION There are two main applications in which current QA/QC NDT technology fails to provide sufficient information regarding deep foundation conditions: (1) detection of flaws in outside cover concrete of drilled shafts and corrosion in steel piling; and (2) evaluation of anomalies beneath the bottom of drilled shaft excavations. Previous studies have demonstrated the capabilities of high frequency stress waves for geotechnical and foundation evaluation purposes (Lee and Santamarina 2005; Coe and Brandenberg 2010; Coe and Brandenberg 2012; Coe and Kermani 2016). Higher frequency waves can visualize smaller anomalous features at the expense of higher attenuation and smaller propagation distance. Therefore, the goal of this study was to advance the state of NDT practice by development of a prototype high resolution stress-wave imaging system as proof-of-concept. The equipment and hardware were modular, which allowed simultaneous development of two system configurations for application to in- service foundations as well as drilled shaft excavations during construction. Results are presented based on two large scale soil models. The first laboratory model simulated section loss in an in-service steel pipe pile and drilled shaft foundation (Fig. 1a). The second model simulated anomalous conditions beneath drilled shafts excavations as might be encountered in areas with significant karst (Fig. 1b). For both models, evaluation of foundation conditions relied on the propagation of small amplitude seismic stress waves using hardware similar to those described in Coe and Brandenberg (2010) and Coe and Brandenberg (2012).

Jan 1, 2018

By W. P. Heineken, A. T. Child

This paper presents the results of a series of experiments made in the metallurgical laboratory of Columbia University, New Pork City. The object of the investigation was to determine, as far as possible, the changes in micro-structure and physical properties caused by short periods of heat-treatment and the longer malleable cast-iron process. It was proposed to do this by means of micro-photographs, heating- and cooling-curves, and tensile tests after the various heat-treatments. I. Micro-Constituents of Iron and Steel. The list of the micro-constituents of iron and steel has grown till now it includes seven different substances, called ferrite, cementite, pearlite,* martensite, austenite, sorbite and troosite. Only the first five of these are mentioned in this paper, to facilitate the understanding of which, the following brief definitions are given: 1. Ferrite (named by Prof. Howe) is, chemically, iron free from carbon. It is the softest of the constituents, and is not colored by etching, except when long-continued. Under the microscope it is easily determined by its regular polygonal etructure; or, if structureless, as in malleable cast-iron, by the ease with which it is scratched. Ferrite appears in mild steel in small amount, in grey cast-iron, and in malleable cast-iron. 2. Cementite (also named by Prof. Howe) is now generally conceded to have the formula Fe3C. It is the hardest of the micro-constituents, having the hardness indicated by 7 of the mineralogical scale; and hence it is always left in relief after

Jan 1, 1901

By Herman D. Mendoza

A rapid recovery/recycling process was introduced utilizing the surface-chemical properties of finely dispersed mercury and alumina (Al2O3) fibers in aqueous environment. The conventional method of amalgamation or .ball milling. involves the mixing of a substantial amount of mercury to collect free gold during the grinding stage. In effect, a portion of the mercury is transformed into minute droplets that readily float and disperse in the amalgamation effluent. The fine droplets of mercury in the dispersion readily attached onto the positively charged macroscopic alumina fibers (i.e. = pH 9.8) at conditions pH 3 to 10. When an effluent from settling procedure after an amalgamation-grinding stage is passed through a column-bed packed with alumina fibers, maximum collection of negatively charged finely dispersed mercury occurred at pH 3 to 6. The collection/attachment efficiency was 99.5%. The collected droplets of mercury, which are left in the column-bed of alumina fibers, were subsequently rinsed with alkaline solution at pH 10 to 11.5. At these conditions, both mercury and alumina fibers carry negative surface potentials and resulted in the partial detachment of mercury from the alumina fibers. The detachment efficiency was only 30-35%. The attachment/detachment mechanisms in this study were analyzed using the DLVO theory.

Jan 1, 2003

By B. M. Davis

The uncertainty associated with a reserve estimate has generally been expressed as a subjective ranking rather than a quantitative expression of either reliability or uncertainty. These rankings of estimate reliability have taken a very nonquantitative bent as well. For example, the U.S. Securities and Exchange Commission definition of proven reserves is given as: Reserves for which (a) quantity is computed from dimensions revealed in outcrops, trenches, workings, or drill holes, grade and/or quality are computed from the results of detailed sampling and (b) the sites for inspection, sampling and measurement are spaced so closely and the geologic character is so well-defined that size, shape, depth and mineral content of reserves are well-established. (U.S. SEC, Form S-18, Item 17A)

Jan 1, 1992

By Robert E. Manning

At present, a need exists for more effective noise control in the coal-mining industry. In particular, new muffler designs with the required acoustic performance are needed for percussive pneumatic drills. Accordingly, the U. S. Bureau of Mines issued a contract to USS Engineers and Consultants to design a muffler capable of attenuating the noise from the air exhaust of a pneumatic drill. The specific objective of the contract was to design and deliver a prototype muffler that would attenuate the air-exhaust noise to 90 decibels on the A scale (90 dbA). The test drill used in this investigation was one used for roof-bolting purposes in coal mines. Using the combined approach of analysis by digital-computer program and experiment by simulated-noise tests, three prototype mufflers were designed and constructed at U. S. Steel Research. The mufflers consisted of a variety of resonator chambers and expansion-contraction chambers, and were of the following sizes: A muffler with a 3- by 5-inch elliptical cross section and about 8 inches in length. A muffler 5 inches in diameter and about 5-1/2 inches in length. A muffler 5 inches in diameter and about 10-1/2 inches in length. These mufflers were subjected to laboratory tests to determine their effectiveness in attenuating exhaust noise, mechanical noise, total drill noise, and simulated noise. All mufflers reduced the exhaust-noise level by about 25 dbA - from about 115 dbA without a muffler to below 90 dbA with a muffler - and thus were successful in meeting the contract objective. Field tests were conducted with the three prototype mufflers at U. S. Steel's Robena No. 4 Mine, and no icing problem was encountered. A fourth prototype muffler was designed to fit around the leg of the pneumatic drill. Tests showed that this kidney-shaped muffler also reduced the air-exhaust noise to below 90 dbA.

Jan 1, 1973

By Jochen Petersen, Jean-Paul Franzidis, Allan Nesbitt

This study presents a method for the determination of intra-particle diffusivities in ion-exchange resins for the purposes of evaluating the state of resin degradation during service. The method uses a zero length column (ZLC) in a closed circuit with variable speed pump and reservoir. The intra-particle diffusion is determined from absorption data by using the Nernst-Plank approximation along with the ‘mass transfer factor’ - which is a product of the mass transfer coefficient (kf )and the concentration of the adsorbing ion in the liquid at the surface of the resin - in a computer algorithm fitting simulated curves to experimental data.. Through this approach the changed intra-particle diffusivity, of a gel-type acid resin, over a 1000 loading and elution cycles, is shown.

Jan 1, 2014

By A. E. Brugger

SOME 2,000 years ago Pliny is supposed to have said, "Out of Africa always something new." It may perhaps even now be news to a great many that the Belgian Congo has in recent years been producing approximately a quarter of a ton of diamonds annually. For that is what the 1 1/4 million carats, the recovery from 40-odd operating mines, and about 20 or 25 per cent of the world's normal consumption, amounts to. In 1915, first exploitation operations produced less than 50,000 carats from two mines. The rapid expansion of operations following the Euro¬pean war meant a most rapid development of a virgin land. The interior is now reached by air in one day from the mouth of the Congo River, where steamers unload mail and passengers from Antwerp. This trip formerly consumed 4 to 6 weeks by a narrow-gage, wood-burning, railroad around the rapids of the lower Congo and Livingston Falls; by river boat to the heads of navigation, Djoko Punda on the Kasai or Luebo on the Lulua; and thence by caravan of native porters over narrow-trails to head¬quarters on the Tshikapa. Hundreds of miles of automobile roads have been constructed over veldt and through forest, bridging streams and ferrying rivers. The railway from Capetown to the Katanga copper district to the East, once two months away by trail is now reached in 2 or 3 days over fair automobile highway. Native "boys" who a few short years ago wore little more than a smile and a string of beads and to whom a wheelbarrow was a complicated piece of machinery, are today driving Fords, tending boilers and engines and operating electrical equipment, or are capable mine workmen, machinists and artisans, and dressed in all manner of cast-off white man's clothing. Even as late as 1920, due to difficulties of securing and transporting machinery during and just after the war, the crudest hand operations were the rule for the excavation, sizing, and concentration of the diamondiferous gravel. All washing and concentration is now mechanized, using steam or electric power, and where operations are sufficiently large to permit competition with native labor costs, excavation and transportation are also accomplished by machinery.

Jan 1, 1932

By Franklin M. Grynkewicz

As part of the Boston Harbor clean up project, the new 1,000 mgd Deer Island Sewerage treatment plant includes ten 240 feet high egg-shaped "residuals" tanks. Contract documents called for these structures to be supported on 2,600 sixteen inch concrete filled pipe piles. The project site is underlain by highly variable glacial and marine deposits. Subsurface conditions vary from one extreme where firm glacial deposits exist at subgrade to the other extreme where 70 feet of medium stiff clays overlying weathered bedrock must be dealt with. The most common profile consisted of 15-20 feet of sands, 20-40 feet of marine clays, and 20-60 feet of stratified glacial deposits (commonly called tills) overlying Argillitic bedrock. Post bid redesign work, initiated as a cooperative effort between the owner and the general contractor, demonstrated that an $8 million savings could be realized if high capacity 48 inch diameter caissons replaced the specified pipe piles. A highly unusual arrangement of having the general contractor and specialty subcontractor providing input to the owner's engineering team allowed the redesign work to proceed on a "fast-track" schedule.

Jan 1, 1992

By G. Fuentes, J. Viñals

"The nature and basic kinetics of the hydrothermal reactions of bornite, covellite pyrite and enargite with copper sulfate solutions were investigated, as a previous study on the behavior of the bulk Chilean copper concentrates. The reaction of bornite produced digenite at 160 °C and djurleite above this temperature. Covellite was transformed to digenite at < 200 °C and to chalcocite (Q and M) at > 200 °C. The pyrite reaction was significant at > 200 °C and extensive at 240 °C, enargite reacts only above 240°C and produces digenite. The hydrothermal treatment of Chilean Codelco-type copper concentrates with hydrothermal reactions was similar to those obtained from pure mineral samples.INTRODUCTIONStudies on the hydrothermal enrichment of chalcopyrite concentrates were begun by MacGauley and Roberts (1951), Roberts et al. (1953) and MacGauley and Schaufelberger (1956). In the 1970's these processes were reexamined by McKay et al. (1972), and Johnson and Coltrinari (1976), but it not was until the 1990s when the kinetics, mechanisms and full engineering aspects were studied by Barlett, (1992), Jang and Wadsworth, (1994) and Peterson and Wadsworth (1994). The main objectives were to solve some important problems in the copper pyrometallurgy: The increase of the smelting capacity, the reduction of the iron slag – and associated copper losses – as well as the reduction of sulfur emissions. The present rise in copper demand and price implies the production and subsequent treatment of very impure concentrates. Thus, a significant increase of environmental problems can be expected in the copper pyrometallurgy. The previous purification of concentrates can reduce the processing of wastes containing hazardous heavy metals in the copper refineries and the hydrothermal treatment can be an alternative which combines both enrichment and purification. On the other hand, Chuquicamatatype concentrates (Viñals et al., 2004a) contains digenite (Cu1.8S), pyrite (FeS2), chalcopyrite(CuFeS2), b ornite (Cu5FeS4), covellite (CuS) and sphalerite (ZnS) as the main mineral components, with minor amounts of enargite (Cu3AsS4), galena (PbS) and molybdenite (MoS2)."

Jan 1, 2012

By A. L. Engel

This report is a compilation of results of preliminary concentration tests of nine manganese-ore samples in 1953-1954. Three samples were from Nevada and the other six from California. These samples represent marginal or low-grade ores from deposits that have been mined selectively in the past. The present interest lies chiefly in the possibilities of concentration of the remaining low-grade ores for economical exploitation. The treatment methods included gravity concentration and flotation in most cases. Results were sometimes unsatisfactory, particularly when the ore was too fine grained for liberation of the minerals within economical grinding range. The contaminating gangue minerals, such as quartz and iron oxides, were locked with the manganese to an extent that prevented separation of high-grade concentrates with satisfactory recovery. In cases where fairly good concentrates were made, it was at the expense of recovery, a condition typical of low-grade ores.

Jan 1, 1955

By Cale J. Dubois

At Cameco Corporations&apos; Cigar Lake Project, large excavations are developed on the 480 Level and 500 Level must remain stable for at least 15 years to host underground processing infrastructure. Following the successful dewatering of the mine in October 2009, subsequent internal rockmechanics investigations augmented by third party technical investigations; determined that to keep the back of the Water Flush Crusher/Run-of-Mine (WFC/ROMs) excavation stable; required a rehabilitation strategy to mitigate deterioration/deformation of the WFC walls and intersection pillars. The mechanism of failure propagating the movement of the excavation walls is understood to be controlled by the presence of a dominant E-W striking and steeply dipping foliation within a relatively weak and mildly altered rockmass sub-parallel in strike with 14 meters high walls and an intersection span approaching 15 meters. The application of open and resourceful communications between site mining engineers, geologists, contract mining staff, construction management experts, corporate mining and civil engineers, and third party technical experts resulted in a multi-faceted short-term ground support strategy consisting of standard bolting and screening, deep-seated modified-strand cable bolts coupled with heavy gauge mesh straps, rockmass reconditioning using low-pressure grout injection, and horizontal cable-lacing for the intersection pillars applied in lifts using a top-down methodology. The intention of the short-term strategy was to stabilize the excavation so that a long-term structural steel support installation - consisting of composite concrete walls, and arch support applied to the side walls and crown of the back - could be constructed safely. This paper summarizes the evolution of the short and long-term ground support strategy and criteria for the WFC/ROMs excavation developed using elements of civil, mining and hydrogeologic design.

Nov 1, 2011

By Saeed Karimifard, Saman Nouranian, Shahram Tafazoli, Bahram Sameti, Frank Chu, Caitlin McKinnon, Tetiana Konstantynivska, Glen Turner

Continuing blast optimization is the cornerstone of any mine-to-mill approach, and particle size analysis is a key metric for meeting blast targets to reduce overall energy consumption and operating costs. To ensure the statistical validity of particle size data, it is important to sample material frequently. In most mines and quarries, the blasted material is loaded onto haul trucks and then transferred to the crusher; measuring the particle size of each haul truck load therefore provides an adequate sampling rate. We propose a particle size analysis solution for haul trucks that does not impact current operational workflows. Using artificial intelligence (AI) and 3D imaging technology, our solution reliably localizes and identifies haul trucks as they drive by, then accurately calculates the particle size distribution of the visible material in each truck load. In this paper, we identify the challenges of designing and implementing the proposed solution and explain the strategies we employ to overcome these. We also discuss a method for boulder detection that leverages the existing deep learning architecture to significantly reduce crusher downtime caused by oversized rocks. Finally, we present field data from a trial installation. To evaluate each change made to the blast design, it is necessary to measure the effect on particle size. An accurate particle size analysis solution is therefore the first step towards optimizing blasting practices and reducing energy consumption throughout the comminution circuit.

By C. R. Summers

In response to the Coal Mine Health and Safety Act of 1969, mandatory noise standards have been developed that specify time-noise limits of mine personnel exposure. Most affected by elevated noise levels is the pneumatic roof bolter operator, both in terms of levels near or in excess of 115 dbA and in terms of length of exposure. Therefore, the principal emphasis of this Bureau of Mines report is on pneumatic drill noise control. It is not the intent of this report to suggest any drill redesign; instead, methods are suggested to reduce the noise level by complementing existing machines. An integral muffler system and a separate muffler system were tested in an attempt to lower pneumatic drill noise levels. Pneumatic drills, when new, operate at about 115 dbA when drilling in sandstone. Using the drill muffler systems, it was possible to decrease the noise level of a 115-dbA stope drill to approximately 100 dbA.

Jan 1, 1974

By X. Q. Cao

As the second largest phosphate resource in the world, Chinese phosphate ores generally grades with low of P2O5. The presentation of beneficiation test on the low grade of phosphate rock in this paper may be used for a reference for development and utilization of the similar reserves. The ore is a marine sedimentary phosphate rock containing low grade of P2O5 and high content of MgO and R2O3; The banded structure shows its suitability for heavy medium separation. The laboratory heavy liquid testing results indicate that as specific gravity of the heavy liquid is 2.85 g/cm3, a rougher concentrate assaying 28.71% P2O5 could be obtained while the rougher tailings contain only 4.47% P2O5. When the combined process with heavy liquid separation followed by direct & re-verse flotation is employed to treat the feed containing 21.15% P2O5, 3.79% MgO, 1.86% Fe2O3, 3.66% Al2O3, 23.75% A.I, and specific gravity of heavy liquid is 2.84 g/cm3, the optimum mesh of grind is 67.5% minus 200 mesh, a phosphate concentrate contained 32.51% P2O5, 0.48% MgO, 0.81% Fe2O3, 1.69% Al2O3 can be produced at a yield of 55.24%. The concentrate P2O5 recovery is 85% with which quality comply with the Class A specifications for production of phosphate fertilizer.

Jan 1, 2014

By L. Bloom

"Man-Made Parameters" refers to the importance of selecting appropriate analytical procedures to acquire useful chemical data. The correct procedures are particularly critical at the sample preparation stage where decisions concerning pulverizing equipment, sample size, contamination and dissolution will impact on the final results independent of the instrumental method of analysis. Several experiments were designed to quantify the impact of these approaches.

Jan 1, 1993

By Ronald T. Mayerle

There are no producing or developing mines in the Rattlesnake RARE II area. Specific areas with mineral occurences are prospects for: 1) stratabound copper and silver in Belt sedimentary rocks on the northwest border of the study area; 2) base metal sulfides, in thin veins and shear zones in Belt sedimentary rock, and diabase dikes and adjacent metasedimentary rocks in the southern part of the study area; 3) barite in sedimentary rocks near Rattlesnake Creek and Sheep Mountain; 4) limestone near Rattlesnake Creek and Blue Point; and 5) silica in quartz veins near the headwaters of Rattlesnake Creek and Sanders Lake. Stone, sand and gravel suitable for construction material are in the study area; however, equal or better quality deposits are common throughout the region. The RARE II area has no known oil and gas, coal, or geothermal energy deposits.

Jan 1, 1983

By A. R. Rule

A flotation process was developed by the Bureau of Mines for separation of carbonate and phosphate minerals occurring in unaltered phosphate ores of the Phosphoria formation. The process involves depression of phosphate minerals with fluosilicic acid and flotation of carbonate minerals with fatty acid emulsions. In individual laboratory tests, selective removal of carbonates was achieved with phosphate recoveries ranging from 60 to 80 pct P205. In continuous-circuit testing, sizing and separate treatment of coarse and fine fractions was necessary to achieve 65-pct P205 recovery. Concentrate grade ranged from 26 to 33 pct P205. The flotation tailings containing primarily carbonate and phosphate minerals is a potential fertilizer material. When reacted with H3P04, concentrated superphosphate containing approximately 40 pct available P205 was obtained.

Jan 1, 1974

By Paul Semple

"In 2007, Noront Resources Inc. discovered the high grade nickel copper PGE deposit in northwestern Ontario in a region now known as the Ring of Fire. Since the initial discovery, Noront has advanced the Eagle¹s Nest Project and in September 2012 released a feasibility study for the development of the Eagle¹s Nest Project. This paper summarizes the results of this recent study and outlines additional work planned in the next stages of project development. INTRODUCTIONThe following paper summarizes the findings of the recently completed feasibility study on Noront Resources Ltd.’s Eagle’s Nest Project. The feasibility study was compiled into a NI 43-101 report by Micon International. This paper is intended to summarize the major technical findings and for complete information, interested parties can find the entire NI 43-101 report at www.norontresources.com or on SEDAR.LOCATIONThe McFaulds Lake project area, which includes the Eagle’s Nest deposit, is located at approximately UTM 5844000 N and 547000 E, and between approximately 52º42’ and 52º50’ N latitude and 86º06’ and 86º24’ W longitude, approximately 250 km west of the community of Attawapiskat on James Bay and 575 km northwest of Timmins. The closest all-season accessible community to the McFaulds Lake project area is Nakina, 300 km to the south, where there is a paved airstrip, in addition to all weather road and railroad access (see Figure 1).The First Nations communities of Webequie and Ogoki/Marten Falls are located 90 km west and 120 km south southeast of McFaulds Lake, respectively. Both communities are served by regularly scheduled air service, primarily from Thunder Bay; both Thunder Bay and Timmins serve as support centres for the James Bay communities and the exploration projects in the area."

Jan 1, 2013

By Jozef F. Zurawski

Increasingly new interceptors or new Combined Sewer Overflow (CSO) projects require connections to existing tunnels. More often than not, the existing facilities are old, in poor or questionable conditions, without proper construction records or as-built drawings. Many cannot be easily inspected unless major construction effort provides flow by-pass for safe access. This paper provides general guidelines on how to approach the problem of assessing the condition of old tunnels, how to plan and design the connection with limited physical assessment, how to develop the scope of work for the bid documents and how to provide geotechnical guidelines and designs for the bid documents.

Jan 1, 2008

By Kumar A, Mishra N. C

For each tonne of chromite ore mined in Sukinda, approximately ten tonnes of fine overburden material is generated. The overburden typically contains about 30 - 60 per cent Fe2O3, 0.3 - 1.1 per cent Ni, four to nine per cent Cr2O3 and 0.04 - 0.2 per cent cobalt and is being discarded leading to loss of valuable metals and creating environmental pollution. In order to take the advantage of presence of iron, nickel and chromium, the present studies advocate the utilisation of nickel lateritic chromite overburden for production of Ni bearing pig iron through blast furnace extracting maximum iron and nickel from the chromite overburden. The present paper deals mainly with the beneficiation of chromite overburden, sintering characteristics and thermodynamic studies. The beneficiation study shows that a beneficiated concentrate having Fe - 50 per cent and Ni -- 1.1 per cent can be achieved from chromite overburden having Fe - 30 per cent and Ni -- 0.7 per cent. Sintering studies have been carried out with bed height of 300 and 450 mm at a suction of 600 and 900 WG respectively. The results reveal that good quality sinter can be produced from chromite overburden concentrate with a basicity of about 1.0 and coke breeze consumption rate about 16 per cent. In all the experiments, Tumbler Index, Abrasion Index and Shatter Index was found to be in the range of 65 - 70, 4.5 - 5.5 and 85 - 90 respectively. The other parameters namely softening temperature, melt down temperature, reduction degradation test and relative reducibility have also been determined. A thermodynamic analysis has also been carried out to make a technological assessment of the process for the production of alloyed pig iron from chromite overburden in blast furnace which shows that it is possible to produce nickel bearing pig iron in blast furnace using the sinter up to 80 per cent. Techno-economic analysis reveals that this route will yield a substantial profit even after accounting for cost of beneficiation, extra coke, raw materials and extra slag produced.

Jan 1, 1999