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By Siavash Zamiran, Abdolreza Osouli

"One of the most concerns of room and pillar mining system is subsidence of the ground surface due to coal mining particularly in room and pillar mines. Subsidence of ground surface is a result of floor, pillar, or roof failure of the mine. At the same, due to many difficulties associated with surface disposal facilities of coal refuse, some mining companies are trying to use underground space as a disposal storage place. In this study, stability and subsidence analyses of an underground coal mine located in the Illinois Basin are conducted. This room and pillar mine was abandoned and later on was used as a storage place to accommodate the coal fine refuse with slurry backfilling method. The geological stratigrophy and geomechanical properties of the mine floor and roof were collected. Floor and pillar stability analyses were conducted for areas with various extraction ratios. The stability of the mine was evaluated both prior and after slurry backfilling. The floor and pillar stability analyses results of the mine due to moisture exposure after slurry backfilling are discussed. The subsidence potential due to mine failure is also evaluated.INTRODUCTIONA typical lithology of coal seams in the Illinois Basin consists of weak underclay stratum. The immediate weak underclay causes frequent floor instability problems in Illinois underground coal mines. There are two different stages in assessing floor stability of the mines where slurry backfilling is planned. The first stage is during the mining operation when weak underclay layer squeezes under pillar stress and results in punching or bearing capacity failure. The second stage is after slurry backfilling. During this stage, the slurry material soaks non-durable floor layers and causes strength reduction in floor material. Pillar stability conditions should also be taken into account during both the operational period and after the slurry backfilling."

Jan 1, 2015

By N. Djilali

Many of the transport phenomena encountered in proton exchange membrane fuel cells occur intrinsically at the microscale level. Physically representative models that fully account for the salient physico-chemical and transport processes in PEM fuel cells are necessary to achieve truly predictive models that can be used with confidence to: (i) gain a better understanding of in-situ processes and couplings, (ii) explore new concepts, and (iii) support design and optimization. The development of more general, rationally based macroscale models requires use of knowledge on the microscale level to provide guidance, and to determine the required parameters and coefficients (model "constants"). In this paper we present a new membrane transport model, the binary friction membrane model (BFM2), recently developed to account for coupled protonic and water transport in polymer membranes. This general model is based on rational and physical consideration, removes several of the limitations of the empirical models used to date, and is formulated for all purfluoro-sulfonic acid membranes. The use of the BFM2 in a fuel cell model is illustrated highlighting significant performance predictions compared to existing empirical model. The second part of the paper addresses the fundamentals of two-phase transport in hydrophobic gad diffusion media. Computational and experimental visualizations resolving the microscale dynamics of water transport between the fibres of a GDL are presented, revealing transport mechanisms that are, contrary to assumptions used to date, dominated by fingering and channeling.

Jan 1, 2005

By A. G. Beer

The evolution of microstructure is examined during the annealing of hot worked magnesium alloy AZ31. The influences of deformation and annealing conditions on the developed microstructures are assessed. It is found that annealing at a low temperature (300 °C), after deformation at a low temperature and strain rate (300 °C and 0.001 5-1 respectively), results in the development of abnormally large grains. With increasing values of Z (lower temperatures, higher strain rates), static recrystallization of the dynamically recrystallised structure takes place; smaller annealed grain sizes are attained and the time at which coarsening begins is reduced. Whilst both the deformation and annealing conditions influence the time it takes to reach a stable annealed microstructure, the grain size attained is governed solely by the prior deformation conditions employed.

Jan 1, 2006

By E. J. Marcotte

"INTRODUCTIONThe Upper Canada Mine is located at Dobie, approximately ten miles east of Kirkland Lake, Ontario.The mill contains Upper Canada's cyanide circuit and Upper Beaver's flotation circuit. The combined capacity is 590 tons per day consisting of 415 t.p.d. of Upper Canada gold ore and 175 t.p.d. of Upper Beaver copper-gold ore.The Upper Beaver ore is trucked five miles to the Upper Canada mine site.Crushing:The crushing circuit consists of primary, secondary and tertiary crushing employing one C .A. C. 15 in. x 24 in. Superior jaw crusher, one 4 ft. x 8 ft. Tyler-Niagara double deck screen, one 3 ft. Symons standard cone crusher and one 3 ft. Symons shorthead cone crusher.The -2 in. product from the jaw crusher is fed to the double deck screen. The+ 5/ 8 in. passes over the top deck to the 3 ft. standard cone crusher; the+ 3/ 16 in. material passes over the lower deck to the shorthead cone crusher. The - 3 / 16 in. material pas sing through the lower deck of screens is the product to the mill.The screens used prior to the installation of rubber screen cloths were: one 4 ft. x 4 ft. section with 3/ 4 in. square openings and one 4 ft. x 4 ft. section with 5/ 8 in. square openings on the top deck; two 4 ft. x 4 ft. sections with openings of 3/16 in. x 4 1/2 in. slot on the lower deck. The fine screens were positioned so that the 4 1/ 2 in. slots were parallel to the flow of feed.The crushing circuit is operated on a three shift per day basis by one operator per shift."

Jan 1, 1968

By S. Hussien, P. Somasundaran, P. Patra

"Rare earth elements (REEs) are essential for many applications in electronics, energy harvesting, and defense. The common resources for economic extraction of REEs are oxides such as bastnaesite and monazite, which are scarcely available in the earth’s crust. On the other hand, REEs are available in many clay and phosphate ores where REEs substitute Ca or Si in the mineral lattices or as physically adsorbed cations at negatively charged sites on the clay surface. While REE oxides readily dissolve in acid, making the chemical leaching of REEs an economically viable option, adopting a similar approach for leaching of silicates and phosphate ores is unfeasible because of significantly low REEs content in these ore deposits. Bio-leaching approaches are environmentally benign and economically viable. We investigated the bio-leaching (Acidothiobacillus ferrooxidans (Af) and the fungal Aspergillus niger (An)) of REEs from a phosphate ore, and examined the factors governing the leaching processes. Based on the shake flask leaching studies, an increase in surface area combined with an increase in pulp density (1-15 wt. %) was found to lead to an increase in the amount of REEs leached. In contrast, an increase in the surface area by reducing the particle size from 75 to 35 led to a decrease in the amount of REEs leached. These differing attributes are proposed to be due to the poor bacterial growth/activity with high F- ions in the leaching media, F- released from the edge-sites of the smaller particles. On the other hand, several advantages that associate with the Af bacterial bio-leaching processes relate to the media composition (Mg2+ and (NH4)+) and phenomena occurring at the electrical double layers of the mineral and bacterial- water interfaces. These studies suggested that leaching of particles occur in a layer-by-layer manner.INTRODUCTIONRare Earth Elements (REEs) are essential for many important applications, such as in electronics, energy generation, and defense. The common resources for economic extraction of REEs are typically carbonates such as bastnaesite and monazite, which are scarcely available in the earth’s crust (Y. Kanazawa and M. Kamitani, 2006). REEs are abundantly available in many clay and phosphate ores where REEs substitute Ca or Si of the mineral lattices. Conventional acid leaching of REEs from oxides is not economically feasible for clay and phosphate ores because of significantly low REE content (parts per billion) in these ores (Tian, J., Chi, R., Yin, J., 2010a; Moldoveanu G. A. and Papangelakis V. G., 2013; WK Goyne, LS Brantley and J Chorover, 2010). In some cases, REEs could be extracted from these ores via chemical leaching routes as they constitute reasonable amounts of REEs (0.1 - 1% REEs). A major challenge faced in general in chemical leaching processes (Chi, R., 1988) is the loss of REEs in the phosphate/gypsum precipitates/crystals, which are overcome in a step-by-step manner by sequentially removing impurities such as fluorine and calcium, including steps carried out at elevated temperatures. On the other hand, bio-leaching approaches provide environmentally benign and economical alternatives. Acidophilic bacteria are currently being used for industrial scale bio-leaching of Au/Cu/Ni from low grade ores. Studies on bioleaching of REEs from red mud (Al2O3) using Penicillium tricolor and Aspergilus niger (An), and, of bio-leaching (lab-scale) of phosphate rocks using Acidithiobacillus ferrooxidans (Af) have been reported (Boon, M., Heijnen, J.J., 1993; Qu, Y. and Lian, B., 2013). We conducted bacterial (Af) bio-leaching of REEs from a phosphate ore in shake flasks and columns, while examining the key factors that govern leaching kinetics."

Jan 1, 2016

By R. Flood

"Oil has been discovered off Newfoundland in a number of locations on the Grand Banks, the most notable and exciting being in 1979 when Hibernia was discovered. This discovery has brought new challenges to the province as well as to all of Canada. During the seven years"" since its discovery, both industry and governments have attempted to define its parameters and to find the most efficient and economical way to develop the field.A number of studies have been completed during the interval and in 1985, Mobil Canada Ltd. and partners stated that they would prefer to develop the field by using a concrete Gravity-Based Structure (GBS). IntroductionHibernia is located in an environmental climate much more severe than that of any previously developed oil field. The wind and wave conditions are similar to those of the North Sea, but unlike the North Sea, any structure on the Grand Banks would have to contend with ice floes and icebergs. Decisions had to be made on whether fixed structures could be put in place that would withstand the pressures of the ice and the impact of an iceberg, or whether structures that could be removed when such impacts were imminent would be used.Early studies in 1981, determined that it was possible to build a concrete Gravity-Based Structure which could withstand the impact of the largest icebergs that are anticipated to float in that area of the banks.Additional studies increased the knowledge of icebergs: their patterns and size, and verified the original conclusions that Concrete Gravity-Based platforms would provide a practical solution."

Jan 1, 1988

By M. Li, T. H. Dubaniewicz, H. N. Dougherty

"INTRODUCTION Underground mines have the risk of accumulation of gases if not ventilated properly or during and after emergency situations when ventilation controls become damaged or stop working. Common gases that are monitored in underground coal are carbon monoxide (CO), oxygen (O2), and methane (CH4). Methane is a gas found in coal and released through mining; its explosive range is between 5% and 15%. Methane is commonly monitored on all mining equipment and with handheld gas sensors carried by most underground coal miners. Fiber optics (FO) is a popular technology applied in underground mining, particularly for its electric isolation. Many miners are familiar with FO cables hung throughout the mine, which are primarily used in the communication of voice and data (Taylor et al. 2010). Advancements in laser and fiber optics have made this technology well suited for gas sensing the harsh environment of mining applications. The work of the U.S. Bureau of Mines on the use of fiber optic monitoring of gases in mines started in 1992. Dubaniewicz et al. (1992, 1993, 1995, 1999, 2003) developed prototype gas sensors, including methane gas sensors, for research purposes. Previous research (Dubaniewicz & Chilton 1992) identified potential fiber optic gas detection cross-sensitivities associated with the index of refraction of various gases. Index of refraction effects was noted for carbon dioxide (CO2), which is produced in significant quantities by mine fires or explosions. NIOSH released a broad agency announcement (BAA) for the development and demonstration of mine safety and health technology (CDC NIOSH 2017). The objective of this announcement was to validate a sensor, specifically fiber optic, for the mine environment and test it in an actual working mine. The RSL FO sensor “OptoSniff” provided from this work is capable of hundreds of sensing points over distances of up to 20 km, has a measurement range of 0.05% to 100%, senses in an oxygen- deficient environment, and has no gas cross-sensitivity (RSL, 2014). The RSL system is totally electrically passive outside the central control unit (CCU), which can be housed in an MSHA-approved explosion-proof (XP) enclosure or in a control room outside of the permissive area. The sensor was tested in dusty and signal loss situations, showing it is tolerant of dust, has functioned at signal losses up to 90%, and was successfully tested in a mine environment for a five-month period (Walsh et al. 2014). This paper describes how the RSL FO sensor is used for testing using smoke and its contaminants for applicability in emergency situations. The testing investigates individual contaminants such as CO2, temperature, and smoke. Each test was performed separately and methane concentration, laser power, and response time data were collected."

Jan 1, 2019

By D. Satish Kumar, D. Mazumdar

"95% bulk mixing times in three different size water model ladles of a 140 T cylindrical shaped , dual plug ( located diametrically opposite at mid bath radius position) stirred, industrial ladle were determined experimentally with and without an upper buoyant phase. Based on dimensional analysis and a regression of the experimental data and, it was shown that in the inertial and gravitational force dominated flow regimes, 95% bulk mixing times for a slag-less situation can be described via:[equation]Parallel to this, a large number of experiments were also carried out in one of the water models (D=0.30m) to quantify the influence of an upper buoyant phase on mixing. These indicated that mixing time, operating variables and thermo-physical properties of the upper phase liquid can be correlated via a dimensionless relationship of the type:[equation]in which, Q is the ambient gas flow rate, L is the depth of liquid , (AL) is the slag layer thickness and 6 and t are respectively the surface tension and viscosity of the upper phase fluid The dimensional analysis, regression of experimental data as well as the adequacy of the proposed correlations are discussed in the text."

Jan 1, 2004

By Mario E. Rossi

Geostatistical conditional simulations are becoming increasingly popular as tools that provide models of uncertainty at different stages of a mining project. They have been used as grade control tools in daily operations, to assess the uncertainty of minable reserves at the project?s feasibility stage, and to assess mineralization potential in certain settings. Other applications include assessment of recoverable reserves, resource and reserve classification, and drill hole spacing optimization studies. All large-scale applications of conditional simulations intend to benefit from the ?correct? (or ?accurate?) characterization of uncertainty, adequately describing the variability observed from the data and its impact on the final objective. The objective of this paper is to compare the ad-hoc ?uncertainty model? provided by a traditional classification scheme with the probability intervals resulting from a conditional simulation model. It is argued that the uncertainty model derived from the use of classification schemes is of little practical use to the mining company or operation. The paper emphasizes differences in uncertainty based on the size of the mining unit considered and the extraction method, and local geological differences. Most importantly, it discusses confidence intervals for these mining units, as compared to the relative precision envisioned by a typical classification scheme. The application described in this paper is taken from a medium-sized Cu open and underground mine in northern Chile, and it demonstrates the impact of several variables on the resulting conditional simulation models. It also compares a more ?traditional? resource classification scheme applied, and the wide difference in local confidence intervals for each mining unit.

May 1, 2001

By E. Brouillette

Difficult operating and mining conditions such as low visibility, difficult roadbeds, fast cycling, small openings, and sharp corners create high demand for LHD manoeuvrability and operator dexterity. Operator experience and patience is especially solicited to fill the bucket rapidly and efficiently and performance can be particularly affected by the skill level of individual operators. Teleoperation and automated loading are viewed as options to improve overall equipment and operation performance in certain mining conditions. Comparative statistical measurements of autoloading performance in different production environments at Noranda demonstrate an increase in bucket filling efficiency and a reduction in filling variance, allowing LHD operation to be more consistent and within manufacturer specifications. Consequential cost savings and productivity increases are demonstrated to be transferable to other mining situations.

May 1, 2003

By S. Xu

Magnesium alloy AM50 is of interest to automotive cradle application because of it excellent castability and good ductility. In this work, microstructure and mechanical properties of both low pressure die cast (LPDC) and high pressure die cast (HPDC) AM50 test bars are characterized. Microstructure was examined using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Phase identifications were performed using energy dispersive x-ray spectrometer (EDS) and TEM diffraction. It has been found that LPDC produces much coarser microstructure than HPDC. At the same time, the HPDC samples are more heterogeneous in microstructure and composition close to grain boundaries. Particles with various dimensions and morphologies of two different intermetallic phases, Mg17A112 and A18Mn5, were found in all the samples. Mechanical tests were performed under conditions similar to those related to an engine cradle application. LPDC samples show lower strength but better creep resistance than HPDC mainly due to the difference in grain sizes and grain boundary microstructure between LPDC and HPDC. Creep curves are well described by the empirical Andrade equation. Tensile-compressive yield and creep asymmetries were found in AM50, i.e. better deformation resistance in tension than in compression. The average yield asymmetry ratio for all the samples is 0.87. Microstructural examinations on the samples tested in tension, compression and creep showed that the deformation mechanisms in AM50 were slip plus twining at temperatures up to 125°C. The examinations indicate the important role of twining in the asymmetry phenomenon. The creep results indicate that dynamic precipitation of the Mg17A112 phase during testing is not the mechanism directly responsible for the creep asymmetry in AM50.

Jan 1, 2004

By R. W. Seedsman

In 1984 and 1985, two 7.6m diameter TBM tunnels were driven from the Donkin-Morien peninsula in Nova Scotia to access the Harbour coal seam. The design of the ground support was based on identifying zones of rock failure through the application of the Hoek Brown failure criterion and the early use of finite element analyses. In 1992, the mining project was abandoned and the tunnels allowed to flood. Monitoring data from the tunnel was subsequently used as a case study in the development of the concepts of brittle rock behaviour. In 2007, the tunnels were pumped out as part of a feasibility study into the reintroduction of longwall mining into the coalfield. There is a good match between observations of the collapse zones in the roof and sides of the tunnel and a simple elastic analysis using brittle parameters, a spalling limit of 5, and a low independent shear modulus. The brittle analyses form the basis of the design for the resupport of the tunnels.

May 1, 2009

By Zetti Gavelán

Globalization and the search for new ore deposits inevitably lead to investment in foreign markets. Investors need to be aware of the effect of their venture on regional, social and economic issues when they invest. Decades of detailed statistics from various sources can be integrated and analyzed to predict the social-economic impact of investment, thereby mitigating risk. To this end, the correlation among variables such as foreign direct investment into mining (FDIM), reserves, and socio-economic indexes is examined. The investigation focuses on South America from 1992 to 2000. Throughout the past decade, South America has benefited from capital investment from more developed countries. This huge investment by the mining industry has impacted the South American economies and can be measured directly using the FDIM. Other economic variables investigated include mining gross domestic product, direct employment, and human development indexes. The correlation is based on data compiled from the World Bank, international risk assessment agencies, the United States Geological Survey (USGS), and the information agencies of various South American countries. Initial analysis of the economic data suggests various expected outcomes. For example, foreign investors may disregard a measured, highly negative country risk in deference to the quality of its mineral resources. It is important to note that the standard measures of country risk published by investment analysts are not industry or investor-specific. In the case of the investor, the level of accepted risk is based on their managed investment portfolio. It is noted that arguments for level-playing fields may be the antithesis of globalization. The discovery and exploitation of ore bodies in a globalized environment necessitates the development of economic measures that standardize mining-specific risk variables and trends. The latest published information on the security of mineral investments in South America is investigated by integrating databases of economic, geologic, production, human indexes, and risk ranking.

May 1, 2003

By P. D. Barrette

This paper deals with the flow of granular materials in bins. A hybrid Lagrangian-Eulerian numerical model is introduced. The model is based on Particle-In-Cell (PIC) advection, and continuum equations describing a Mohr-Coulomb criterion. Experiments were conducted to test and verify the performance of the numerical model. Tests were done using three types of particles. Measurements of material properties and flow rates were carried out. Video records were also obtained and used to examine flow patterns. The results indicate that the numerical simulations produce deformation patterns and flow rates which are in good agreement with the experimental observations.

May 1, 2007

By M. J. Sapko, R. W. Watson, E. S. Weiss

The relative incerdivity of several blasting agents was evaluated in the Bureau's Bruceton Experimental Mine (BEM) . The minimum charge weights resulting in the ignition of predispersed oil shale dust clouds were measured for each of the explosives. A 400 g unstennned charge of ANFO (ammonium nitrate-fuel oil) was sufficient to initiate an oil shale dust explosion, whereas a 1000 g unstenuned charge of an emulsion blend did not ignite the dust even with the addition of 4% methane gas. Several stenuning materials were evaluated in the BEM for their effectiveness in preventing the ignition of near stoichiometric methane-air mixtures. Water stenuning was superior to all other inhibitors tested against methane. Explosibility testing of fine sulfide ore dust in a 20 L chamber and in the BEM show that the dust is capable of propagating an explosion given nominal concentrations of 700 to 800 g/m3. Results are encouraging and irrlicate that there is merit in pursuing explosive composition as a means of reducing ignition probability of oil shale and sulfide dust clouds generated during nonnal blasting operations. The proper selection of explosives and stenuning materials should significantly reduce the probability of secondacy dust explosions in oil shale and sulfide ore mining.

May 11, 1988

By A. Moyano

The development of the traditional converting process performed in a PeirceSmith or Hoboken converter is limited by the investment magnitude associated to the fulfillment of the environmental regulations. Thus, the continuous converting process rather than a conceptual process alternative is becoming a necessity for a smelter facing limited converting capacity and/or lacking of fulfillment of the environmental regulation with its maximum converting capacity. The objective of this paper is to present the progress of the Codelco continuous converting process evaluated at pilot-scale level when converting solid mattes or white metal into blister copper. These tests allowed for gathering of relevant data to be considered for a new stage of evaluating the Codelco continuous converting at industrial-scale test. The pilot-scale tests were done in a Teniente Converter pilot scale unit at the Codelco Norte Smelter. The results of processing solid copper mattes (65-75% Cu) and producing low sulfur content blister copper with production of a constant S02 gas concentration, and the production of liquid slag with low copper solubility was achieved and is discussed in the present paper.

Jan 1, 2007

By S. Khoshkhooei

In this research, the effects of rare earth elements addition on thermal fatigue behaviors of AZ91 alloy were studied. Repeated heating and cooling cycles were applied on the samples at 170°C and 210 °C to develop thermal fatigue cracks, Crack growth mechanisms and microstructural influences were investigated by optical and scanning electron microscopy (SEM) as well as energy dispersive X-ray spectroscopy (EDS), Thermal fatigue behaviors were improved successively by addition of up to 2-wt% RE, This improvement is attributed to consummation of the aluminum of the melt by precipitation of the needle shape Al 11 RE3 phases, This process reduces the volume of Mg17Al12 phases and consequently decreases the brittle Mg/Mg17Al12 interfaces which are the main reason of weak thermal properties of the alloy at rather high temperatures, Further additions of RE, however, reduced the thermal shock resistance of samples by increasing in the mean length of the brittle needle shape phases.

Jan 1, 2005

By I. H. Warren, F. A. Forward, A. Vizsolyi

"Observations are reported on the pressure leaching of material produced by subjecting chalcopyrite to two types of heat treatment. Calcination of the mineral at 825°C, in the absence of oxygen, induces some sulphur loss by volatization, producing a material from which copper can be leached more rapidly than from chalcopyrite. Treatment of the mineral with elemental sulphur at 475°C leads to sulphur uptake accompanied by a change in mineralogical structure of the chalcopyrite. Copper is prefer-entially and rapidly leached from the sulphur-treated material. A tentative explanation of the sulphur-chalcopyrite re-action is presented."

Jan 1, 1968

By R. Baker

A novel electrochemical half-cell and corresponding working electrode were designed to evaluate the electro-catalytic activities of catalysts in an environment close to that of an operating proton exchange or polymer electrolyte fuel cell (PEMFC). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were employed using the novel cell to characterize various methanol electro-oxidation parameters that contribute to the overall reaction on a fuel cell anode. The effect of temperature on methanol oxidation kinetics was examined in the potential range of 0.31 to 0.65V (vs. NHE). The data was collected in the temperature range of 20 to 80°C. Based on the experimental analysis and literature data, an equivalent circuit model (ECM) for methanol oxidation was proposed and was used to fit the EIS experimental data. The experimental data and ECM electrochemical data was used to extract electrochemical kinetic parameters for methanol oxidation such as the exchange current density, Tafel slope, and energy of activation for the reaction. Kinetic data, especially at different temperatures, is very limited in the literature.

Jan 1, 2005

By C. R. Edwards

"Since the first commercial extraction of uranium in the early 1940s, the range of feasible process alternatives has greatly increased. This paper reviews process options to reduce extraction costs, improve efficiencies, effect safer operations, and lessen environmental impacts. Equipment and processes used in the past, in use now, and that could be considered for future use are described.BackgroundTwo billion years ago life on earth consisted solely of single celled creatures of the simplest design (Gould 1989). Incredible as it may seem, uranium fission reactors were operating then also. In what is now western Africa, a series of natural reactors were fueled by rich uranium deposits in contact with underground rivers. Water from the rivers provided the moderator necessary to sustain the nuclear fission chain reaction. These primordial reactors ran down after about 600 000 years (Ontario Hydro 1989).Because it is ubiquitous in the earth's crust, humans have always been in contact with uranium. Mining of uranium, albeit not intentional, is ancient ; uranium minerals were embedded in ore veins mined for metals such as silver and copper.Uranium was discovered in 1789 in Berlin by an apothecary, Martin Heinrich Klaproth, who named the element after the recently discovered planet Uranus. The metallic element uranium, as opposed to its compounds, was extracted in 1841 by the French chemist Eugene-Melchior Peligot. The atomic mass of uranium was calculated to be 120, but the Russian genius Dmitri Ivanovich Mendeleev (famous and welcome everywhere except in Russia, where his liberal politics were detested by the Tsar), found this did not fit into his periodic table, and submitted a value of 240. Mendeleev was close; the exact atomic mass is 238.029.Henri Becquerel's detection of the radioactivity of uranium in 1896excited scientific study of the metal, but virtually no practical use was found for uranium outside of a minimal consumption as a colouring agent for glass and ceramics. Scientific interest intensified in the 19305. In 1933 Leo Szilard patented the concept of the nuclear chain reaction. While walking to work on a fine fall London morning and mulling over the problem of how to release atomic energy, he was stopped by a red light. He stood in thought and conceived the notion of the neutron-activated chain reaction before the light turned green. The patent was filed in 1934, and Szilard assigned it to the British Admiralty in order to keep it secret, in an honourable but ultimately futile effort to prevent the misuse of science (Bronowski 1973)."

Jan 1, 1992