Search Documents

By Seffen Leppla, Rolf Katzenbach, Matthias Seip

"Abstract The economic and safe design of deep foundation systems in difficult soil conditions is based on a reduction of construction material used, construction time spent, energy consumed and a high-level modelling of the soil-structure-interaction. The special foundation system Combined Pile- Raft Foundation (CPRF), in-situ load tests on the construction site and a sufficient soil investigation allow cost optimised constructions. In any case at challenging projects the observational method has to be applied for verification and quality control of the design. Regarding the 4-Eye-Principle as basis of the quality control management an independent peer review of the planning, design and construction phases is the guarantee for safety, serviceability and optimisation of all projects. Main execution standards for the construction of deep foundations based on the Eurocode 7 are summarised and discussed. The paper presents the basics of the safe and qualified design and construction of foundation systems including quality assurance. The application in engineering practice is shown on achallenging project of high-rise buildings with difficult boundary conditions.IntroductionThe construction of deep foundation elements in inner cities are special challenges due to the limited space for the construction works and the effects on existing buildings (Figure 1).An economic and safe design of deep foundation systems in difficult soil conditions is based on the following main aspects:•,qualified experts for planning, design and construction•,interaction between architects, structural engineers and geotechnical engineers•,adequate soil investigation•,design of deep foundation systems using the Finite-Element-Method (FEM) in combination with•,enhanced in-situ load tests for calibrating the soil parameters used in the numerical simulations•,quality assurance by an independent peer review process (4-eye-principle) combined with theobservational method if necessary"

Jan 1, 2014

By I P. Hodkinson

SMC Resources Limited is implementing a selective mining approach at the Hadleigh Castle mine, formerly operated by Aurora Gold Limited. The main ore zone has a length of 250 metres and dips at 40 - 45¦ to the south. Gold mineralisation occurs in a variety of quartz-sulphide lodes in sericitised granodiorite. Shallow dips, alteration intensity and mineralisation style combine to make mining relatively difficult. Previously unworked, high-grade, shallow dipping (30 - 45¦), narrow quartz-sulphide lodes within the hanging-wall of the deposit are also being selectively exploited. Annual production of 35 000 oz Au is forecast from 185 000 tpa ore grading 6.5 g/t Au over a currently envisaged mine life of six years. Operations completed to-date include deepening the decline and access development of the first two levels beneath the previous workings. Longhole stoping operations have commenced in the main ore zone with air leg stoping also underway in the hanging wall lodes.

Jan 1, 1998

By N. E. Idenyi

The effects of compositions and firing temperatures on the physico-mechanical properties of blended Nsu fireclay and Nkalaha redbrick clay have been investigated. The clay samples were compounded according to the following ratios: 10:90, 20:80, 30:70, 40:60 50:50, 60:40, 70:30, 80:20 and 90:10 in the order Nsu: Nkalaha respectively, and test samples made and fired at 9000C, 10000C 11000C and 12000C. The properties tested for were the modulus of rupture, porosity, shrinkage, apparent density, water absorption and bulk density. From the results obtained, it is inferred that the blends have a maximum service temperature of 11000C, with the 30: 70 blend presenting the best characteristics. A conclusion is drawn to the effect that the blend could be adapted for the production of ceramic earthenware, electrical porcelain pin insulators, cement manufacture and for refractory linings where temperature requirements are less severe.

Jan 1, 2006

During incineration of municipal solid waste (MSW), various environmentally harmful elements and heavy metals are liberated partly into bottom ash, and partly carried away with the off-gases and subsequently trapped in fly-ash. If these waste incineration residues are not properly processed and immobilized, it can lead to secondary environmental pollution to the air, soil and water. The stricter environmental regulations require a higher immobilization efficiency of the waste incineration residues, which is the main objective of the present cooperation research. Within the present project, a systematic scientific research on various MSWI residues has been carried out, including sampling, low or high temperature processing and leaching tests. In the present paper, the major results have been summarized. The research results reveal that through appropriate combined pre-processing and high temperature vitrification, the bottom ash and fly ash can be efficiently stabilized. The results achieved provide a valuable alternative route to treat the solid residues from incinerators, and to make efficient recycling and safe utilization possible.

Jan 1, 2014

By B. Karnath, K. Guha, S. Tandon

At Jhagadia Copper Ltd (India), Copper is produced through secondary route using Top Blown Rotary Converter (Kaldo Furnace). The basic raw material being treated includes Matte-slag Reverts, Copper Cakes, dross & Cement, Oxide Ore, Low S bearing Concentrates & various metallics along with high grade copper scraps. The plant has capability to refine & produce Blister grade copper from Kaldo furnace as well as PS Converter . Blister is fire refined in Anode furnace & electro refined in Refinery to produce cathode copper. Our product , Copper Cathode , has already been established in the market as its quality is better than 'LME Gr'. The paper deals with the experiences encountered during commissioning & stabilization of the plant.

Jan 1, 2007

By J. E. Chilton

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to determine the influence of mining machine-mounted scrubbers on airflows and methane concentrations at the face when blowing ventilation systems are used. Tests were conducted in a full-scale ventilation gallery with a model mining machine that simulated airflow created by a dust scrubber. During the tests, ultrasonic anemometers were used to measure airflow speed and direction at several locations near the face. For the same test conditions, methane was released from the face and gas concentrations were measured at 21 locations above the machine using fixed point methanometers. Changes in airflow speed and direction are correlated with scrubber airflow and the measured methane distribution above the mining machine. The research results showed that operation of machine-mounted scrubbers improved face ventilation when blowing ventilation is used by increasing both the intake flow and the quantity of air reaching the face.

By A. C. Neiva

An energy-dispersive x-ray fluorescence spectrometer was assembled with the aim of analysing alloys and corrosion products of artistic, ethnological and archaeological pieces. The spectrometer is semiportable and consists basically of an 60kV/1.5mA X-ray tube with W anode and a Si-drift X-ray detector with Peltier cooling, with no need of liquid nitrogen. It was used for the analysis of the alloys and occasional corrosion products of several metallic pre-Hispanic pieces of the Museum of Ethnology and Archaeology of the University of São Paulo. Special care was taken to account for the contribution of spurious radiation from both the Pb primary collimator and the Zr detector collimator. The main components of most alloys were Au, Ag and Cu, but Pb, Ca, Fe and other elements were also identified. The characterization of the alloys and corrosion products is important for the subsequent conservation of the collection.

Jan 1, 2006

By Stephen C. Tadolini

The anchorage capacity of four types of bolting systems was investigated in two mines with thick coal roofs. In conjunction with the in-mine tests, a simple axisymmetric finite element computer program was developed. Both the field and computer results indicated that thick coal roofs can be effectively supported entirely by the coal member.

Jan 1, 1986

A major domestic aluminum producer raised its price for primary aluminum metal from 44 cents per pound to 48 cents per pound, effective August 5, 1976. Other major producers have increased their list prices by equivalent amounts COAL: The strike which began July 19 in southern West Virginia enlarged by early August to involve approximately 80,000 miners in nine States. As of August 4, the aggregated loss of production is estimated to be 5.8 million tons. Reportedly, at this time, the railroads which serve the struck areas are feeling the largest impact with coke plants and electric utilities relying on stocks which are generally high.

Jan 1, 1976

By F. D. Cannon

"In metal and nonmetallic mineral mines during the 15-year period 1911 to 1925, 30.17 per cent of all fatalities and 16.57 per cent of all injuries were caused by falls of rock or ore from the back or roof or from the wail; 1.24 per cent of the fatalities and 11.05 per cent of the injuries were caused by rock or ore while loading at the working face; 6.66 per cent of the .fatalities and 2.49 per cent of the injuries resulted from men falling down 3 chute, winze, raise, or stope; and run of ore from chute or pocket caused 1.48 per cent of the fatalities and 1.93 per cent of the injuries.3 Hence, accidents due to falls of men and material caused. 39.55 per cent of the fatalities and 34.05 per cent of the injuries in these mines. Accident prevention can best be assisted by each company's preserving complete records of accidents classified according to cause and rate per thousand or 10,000 shifts. A systematic method of recording accidents and the employment of graphs or charts will be helpful to the company safety department in analyzing the cruses of accidents. The purpose of this publication is to analyze data on accidents caused by falls of men and material in metal -mines of the United States, and to suggest methods of preventing or reducing such accidents."

Jun 1, 1929

By Anthony Iannacchione

Coal mine bursts have represented a major hazard for U.S. mining operations for more than 90 years. During this time, many prevention controls have been developed and tested. This paper reviews 11 prevention control techniques. Although coal mine bursts are not common events in most underground coal mines, their occurrence almost always requires a change in mining practice. Over the many years of dealing with these hazards, specialized requirements for layouts and novel extraction sequences have been developed on a site specific basis. The keys to mitigating risks are to properly assess the coal burst hazards and to possess the knowledge and skills to prevent or remediate their occurrence.

Jan 1, 2008

By S. Ndlovu

To investigate the influence of orientation of crystal lattice on the bacterial leaching of pyrite crystals, single crystals of 100, 111 and110 plane orientations were used for the study. Experiments were carried out in the presence of a Thiobacillus ferrooxidans culture. The different corrosion patterns observed on the surfaces of the bioleached samples suggests a variation in cell-surface interaction from one crystal plane to the other. The surface corrosion patterns generally reflected the influence of the symmetrical arrangement of the atomic planes in the lattice on which they formed. The results indicate that the surface properties of mineral sulphides may control the evolution of corrosion patterns and consequently the initial oxidation process in acid bacterial leaching.

Jan 1, 2004

By Dipak C. Talapatra

This report describes the development of guidelines for design, inspection and maintenance of automatic couplers. In order to devise the guidelines, performance requirements for automatic couplers were carefully established. This was clone through a comprehensive survey of coupler manufacturers and extensive observation of automatic couplers in service in a broad spectrum of mines. The capability of the couplers to withstand the demands of the mining environment in terms of strength characteristics, gathering range, curve negotiability, and other factors were all carefully evaluated. An analysis of coupler related accidents for the years 1972-1976 was carried out to provide information on the safety and reliability of existing automatic couplers. This formed an important input to the development of the guidelines. It is expected that these guidelines will he useful to coupler manufacturers for establishing designs for improved automatic couplers, and to mine operators for maintaining their couplers in a safe and good operating condition throughout their expected lifetimes. This report is in two volumes: Volume l - Technical Report Volume 2 - Design, Inspection, and Maintenance Manual

Jan 1, 1977

By William F. Hahn

The Bureau of Mines recognized the problems encountered in low seam mining illumination systems. It was determined that the best way of implementing an illumination system is to integrate the design during the design and fabrication of new machinery at the factory. The purpose of this program was to integrate an approved lighting system in a low seam battery powered scoop and evaluate its performance. This report documents the work performed on this program and the results obtained.

Jan 1, 1980

By James C. Barker

The U. S. Bureau of Mines made a reconnaissance In the western Crazy Mountains for cobalt and associated metals as part of the Alaska-wide critical and strategic metals program. The area, located about 75 miles north of Fairbanks in central Alaska, is underlain by complexly faulted, predominantly clastic sedimentary rocks bordering the Tintina Fault system. Above background metal concentrations were found to occur in altered fault zones, tectonic breccias, soils, and ground water seeps and precipitates that either cut or are derived from the faulted clastic sedimentary rocks. Up to 0.115 pct cobalt and more than 2.0 pct zinc were detected in soil samples. Spring precipitates contained up to 1.3 pct zinc, 0.037 pct tungsten, and other metals. Some localities lacked cobalt but contained anomalous amounts of copper, lead, zinc, silver, and other metals. No outcropping of primary metallic minerals was located because of Colluvium and vegetation cover and extensive deep leaching. Therefore, whether the metal values encountered are due to primary deposits with economic development potential or are the results of concentration by ground water from low-grade sources is unknown. The presence of cobalt, nickel and zinc, and the identification of minor tin and tungsten indicate that further investigation is warranted.

Jan 1, 1983

By S. A. Sayed, M. N. M. Ahmed, M. A. Doheim

The performance of a 12.7 cm hydrocyclone was investigated by considering the effect of design variables (diameters of the vortex finder and apex) and operating variables (pressure drop and solids content of the feed) at a medium feed solids concentration of mixed minerals. Cut-size was found to be the most important parameter in hydrocyclone design and operation. The effect of feed pressure in reducing hydrocyclone cut-size is less pronounced at medium feed solids concentration with a mixed mineral feed. The choice of vortex finder diameter and apex diameter becomes more sensitive at medium feed solids concentrations. The effect of feed solids concentration in increasing the cut-size becomes less marked at higher concentrations. Predictions of an empirical model were found to be in good agreement with experimental data. Comparison of results obtained from the model with those predicted by theoretically derived models showed the latter to be more promising, with the turbulent two-phase model giving closer agreement with the experimental data

Apr 1, 1995

By D. J. Dollhopf

The specific objective of this three year study is to investigate the means of reestablishing non-polluted hydrologic systems in areas where surface mining directly impacts shallow ground-water resources. The research area chosen for the study is located near Colstrip, Montana it a new mine site where chemical analysis of core samples from the overburden suggested that excessive concentrations of several elements would he encountered during the mining process. This report discusses local vegetation; soils; and regional geology, and hydrology. Stratigraphic cross sections and regression analyses were used to study the litho-chemical relationships in the overburden. Cross sections indicated Inimical material may be related to both rock tune and position within the overburden profile. In overburden zoness where clay content was high, there was a greater probability that Pb, Cu, Ni, and Mn concentrations would also be higher than average; similarly, the likelihood of overburden exceeding a suspect level became less as the sand content increased. Highest value, of conductance were usually found within a few meters of the surface. High concentrations of clay, nickel, and zinc were frequently found directly above and below the Rosebud coal. Regression analysis indicated overburden SAR was predictable with only a Na analysis. A strong relationship also existed in the overburden between conductance, Ca, and Mg.

Jan 1, 1977

By Michael M. Hamilton

U.S. Bureau of Mines personnel examined mines, prospects, and mineralized areas to determine mineral resources and resource potential in and adjacent to the North fork Smith RARE II study area. Most mineral resources identified in this area are in laterites, highly-weathered residual soil zones. In the RARE II area, resources of nickel, cobalt, chromium, and magnesium were identified at 15 laterite properties and chromium resources at one chromite mine. Other commodities include copper, gold, silver, and mercury (fig. 1). Approximately 1,100 lode and 1,200 placer claims have been located in or adjacent to the area. Most placer claims are for literites. There are no patented claims or mineral leases. Forty laterite deposits on 15 ,properties within the RARE II area (fig. 2) contain about 16 million tons of identified marginal reserves and subeconomic resources containing nickel, cobalt, chromium, an magnesium (table 1). Most deposits have keen explored and are currently claimed. California Nickel Corporation is developing laterites on Gasguet Mountain, within and adjacent to the southeastern and western parts of the study area. If this project proceeds to production, a laterite processing plant on Gasquet Mountain would enhance the minability of other deposits in the study area. The Climax, PFM, DF, and Stone Corral properties (fig. 1, nos. 1, 6, 9, and 23) have deposits of sufficient tonnage and grade to attract mining interest; resources at these properties are in and adjacent to the RARE II area.

Jan 1, 1983

By Gale D. C, Giles D. E, James Parker A

A zinc-lead-iron sulphide concentrate from McArthur River can be leached at atmospheric pressure in aqueous solutions with HCI, FeCl3, CuCI2, HCl/02 HC1/02/ CuCI2, Cl2, and CI2/CuCI2 to extract >98 per cent zinc, >90 per cent silver, and <15 per cent iron in 1-7 h at 95°. Galena is more reactive than sphalerite and is converted to lead chloride. Except for leaching with HCI, elemental sulphur is the the main by-product of the leach with little or no sulphate ion detected. The rates and products of these reactions are compared. It is recommended that aqueous slurries of the concentrate (50 per cent w/v) are leached at atmospheric pressure with Cl2 in the presence of copper(II) chloride, which accelerates the extraction of zinc. Hydrochloric acid is a by-product which is consumed bYJeaction with fresh concentrate in air at 60°. Copper is subsequently stripped from the leach solution and recycled by reaction with fresh concentrate at 100°. The separation, recovery, and electrolysis of zinc and lead chloride is outlined since this process would produce Cl2 gas which can be recycled and used directly in the leaching stage.

Jan 1, 1976

By Gary Friedline

As a consequence of the Coal Mine Health and Safety Act of 1969(PL91-173), the Bureau of Mines (BOM) entered into a contract with Ocean Energy Inc. (OEI) to develop, fabricate, install, and evaluate a permissible lighting system for use on a longwall coal mining operation. The program schedule is shown in Figure 1.1. The proposed regulations are contained in Appendix A. The initial part of the program involved a survey of existing longwall lighting practices in Germany and England and an evaluation of a variety of lighting components on a mockup of a longwall mining operation that was fabricated under this program. Visits made to German and British mines uncovered major differences in lighting level requirements, permissibility aspects, size, and operating constraints which identified wide disparities and essentially eliminated from further consideration any known imported lighting devices for meeting the higher lighting levels and standards proposed for US coal mines by the Mining Enforcement and Safety Administration (MESA). The longwall mockup provided use¬ful information regarding the amount of illumination required, physical size and shape of lamps, light distribution problems, cable routing, use of connectors, signaling, glare, and other important factors unique to the lighting of low coal longwalls.

Jan 1, 1975