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By Filipe Beretta

This study investigates geophysical logging capacity to predict coal quality. It was analyzed for possible correlation, some parameters determined via laboratory analysis of coal against results for the same parameter derived from wireline logs recorded by a geophysical probe. These probes detect variations in some rock physical properties, such as their natural gamma ray emissions and electrical resistivity. Results showed a strong correlation between natural gamma and ash content, establishing a linear model to estimate ash content from geophysical logging data with a low estimation error (less than 5%). Besides, results showed that there is no correlation between sulphur content or volatile matter and resistivity, neither with natural gamma of the rocks. Ash content derived from gamma ray values can be used as secondary information to evaluate coal quality during resources estimation, using methods such as soft indicator kriging. The methodology is illustrated using a case study at a coal deposit in south of Brazil.

Oct 1, 2009

Similarities and Dissimilarities in Florida Phosphate Ore Types - Surface and Bulk Property Analysis of the Flotation Feed, Concentrate and Tails

Sep 13, 2010

By Paul Averitt

The coal-bearing rocks in Iowa occur in an arcuate belt across the central and southern parts of the State (fig. 1) at the northern end of the Western Interior coal field. Coal beds of minable thickness are sporadic throughout this area and are mined principally in the three districts indicated by dark shading on the index map, although coal occurs also in the areas indicated by light shading. The coal is mostly of high-volatile C bituminous rank in all parts of the State. SURFACE FEATURES The coal-bearing rocks in Iowa are concealed for the most part by a covering of glacial drift ranging in thickness from a few feet to several hundred feet. This covering has been dissected to form a gently rolling upland, rising from an elevation of 466 feet at the mouth of the Des Moines River to about 1,200 feet in Calhoun County in the central part of the State. The local relief, however, rarely exceeds 150 to 200 feet.

Jan 1, 1949

Interest in the tantalum-niobium minerals has been greatly stimulated in Western Australia by the fact that these rare minerals occur at numerous localities in that State, and in the adjoining parts of the Northern Territory, sometimes in mineable concentrations, as at Wodgina and Greenbushes. A large proportion of the world's tantalum comes from these deposits. The late Dr. E. S. Simpson, in particular, made an extensive study of the chemistry and mineralogy of these minerals, and the following observations are based upon the examination of specimens which he and Mr. H. Bawley, Government Mineralogist of Western Australia, have submitted to me for examination from time to time. The fact that so many of the specimens have been analysed provides a unique opportunity for the interpretation of the phenomena observed in the polished sections.TANTALITE-COLUMBITE SERIESIt has long been considered, on the basis of crystallographic form, chemical analyses, and specific gravity measurements, that ferrotantalite (FeO. Taz05), manganotantalite (MnO. Taz05)' ferrocolumbite (FeO. Nbz0 5), and manganocolumbite (MnO. Nbz0 5 ) form a complete isomorphous solid solution series (Simpson, 1937) and this is confirmed by study of polished sections of these minerals, Pehrman (1929) examined a series of five analysed specimens with Nbz0 5 contents as follows:-

Jan 1, 1940

By B. J. Schat, A. W. O. Bots, O. S. Langhorst

Amsterdam City Council is building a new metro line, the North–South Line. The line passes under Amsterdam Central Station (a listed building) about 18m below street level. The retaining wall that has to be built underneath the existing building is an innovative construction consisting of two rows of steel piles interspersed with a solid mass of overlapping jet grout columns: a composite ‘sandwich’ wall. This paper gives an overview of the approach taken to designing (computational models) and building the retaining wall. Special attention is paid to the observational method used for the construction of the jet grout columns.

Jan 1, 2007

By A. K. Tripathy, P. K. Pattnayak, H. S. Ray

The effects of water addition on the solid-state reaction between Cr2O3 and Na2CO3 at low temperatures (up to 873 K) were investigated to determine its possible influence on the reaction rate and the degree of conversion to soluble chromate. Experiments at high temperatures were conducted for comparison. It was found that adding water to the mixture before roasting enhanced both reaction rate and yield significantly. The reactions followed the Lesokhin-Tempelman equation at low temperature and the Ginstling-Brounshtein equation at above 973 K; the respective activation energies were 95 and 22 kJ/mol

Jun 19, 1905

By Pierre Laliberté

Objectifs ?Quantifier les économies d?énergie potentielles liées àl?utilisation de différentes technologies ?Créer un modèle permettant d?évaluer les économies possibles d?énergie en combinant plusieurs technologies ?On ne peut simplement additionner les pourcentages d?économie individuels pour en évaluer le total.

Feb 1, 2008

By Jørn H. Thomsen

This paper presents the experience gained and the lessons learned over the last decade within the numerous offshore foundation projects undertaken in the offshore waters of Denmark and Belgium by COWI A/S of Denmark. This experience derives from the close collaboration with, and interaction between the owners, contractors, and engineers in the various stages of project development. In turn, the experience draws on COWI's experience within foundation of large bridges world wide over half a century. Focus is on two pioneering gravity base foundation projects: ? Nysted in Denmark, currently the largest offshore windfarm worldwide with 72 Nos Bonus 2.3 MW turbines in water depths up to 10 m in the relatively benign inner Danish waters ? Thornton Bank in Belgium, where the first phase - comprising 6 Nos REpower 5MW-turbines of a total of 60 - are planned to be built in the rough North Sea in water depths exceeding 25 m.

Jan 1, 2013

By Ad. Breyre

Internal-combustion engines have been used in Belgian mines for a long time. As early as 1899, the use of these engines underground was considered, but the general policy was to prohibit such an application unless ministorial permission was granted in special instances. At that time only gasoline engines were available, and a few of these were installed as stationary engines, although in general they wore replaced later by electric or compressed air motors. However, the number of gasoline locomotives continued to increase. Regulations governing; the use of these locomotives seen were formulated and as early as 1920, when a new set of regulations was promulgated, these of gasoline locomotives in mines could be authorized by the Provincial Inspection Department and no longer depended on obtaining a ministerial decision. Since 1931 this authorization may be given by the Chief Inspector of Mines, Director of the Mining District. Since 1920, safe practices have been incorporated in the regulations.

Jan 1, 1940

By Ad. Breyre

[Internal-combustion engines have been used in Belgian mines for a long tine. As early as 1899, the use of these engines underground was considered, but the general policy was to prohibit such an application unless ministorial permission was granted' in special instances. At that time only gasoline engines were available, and a few of these were installed as stationary engines, although in general they were replaced later by electric or compressed-air motors. However, the number of gasoline locomotives continued to increase. Regulations governing the use of these locomotives soon were formulated and as early as 1920, when a now set of regulations was promulgated, the use of gasoline locomotives in mines could be authorized by the Provincial Inspection Department and no longer depended on obtaining a ministerial decision. Since 1931 this authorization may be given by the Chief Inspector of Mines, Director of the Mining District. Since 1920, safe practices have boon incorporated in the regulations.]

Jan 1, 1940

When the first rush of miners took place on the Molyneux River, in the Dunstan Gorge, the gold was won by means of cradling the gravel, which was shovelled from the various beaches and crevices in the rock-bound sides of the river.The above method of winning the gold was only practicable when the beaches were not covered with water, hence the work was usually carried on during the winter months, the ordinary level of the river during spring and summer months being some ten or twelve feet above winter level. The melting of the spow in the Lakes water-shed being responsible for the high summer level of the river.As the available beaches were worked out, other methods of winning the gold were proposed and worked with more or less successful results the first advance being to work the bed of the river by means of a spoon dredge. The spoon was made with a round lip or ring of iron, having a steel cutting edge on one half of the circumference, at the opposite side a socket being forged to take a long spar or boom, which was securely fitted thereto. At intervals round the hoop, half-inch holes were bored to enable. a bullock-hide bag to be laced on to same. The spoon was worked from a pontoon which carried a crab winch, tackles and the necessary washing appliances to treat the washdirt lifted. In starting to dredge, a tackle was attached to near the upper end of the boom, and a line or chain was carried over a cat head from the crab winch...

Jan 1, 1901

Following the Coalbrook Colliery disaster in 1960, Salamon and Munro (1967) established the well known empirical coal pillar strength formula in South Africa. This formula has prevented further violent multiple pillar failures. In 1996, a back analysis of the collapsed and uncollapsed cases in Australia led to the development of the Australian empirical coal pillar strength formulae. The original collapsed and uncollapsed coal pillar database of Salamon and Munro (1967) was updated in 2006. This study introduced various strength formulae for different coalfields and seams in South Africa through back analyses of collapsed and uncollapsed cases. Today, the resultant pillar strength formulae from these previous studies and the behaviour of coal pillars are mostly well understood and applied with confidence. However, it was assumed in the previous studies that the behaviour of pillars is not time dependent; therefore, the formulae established do not provide an associated time to failure of coal pillars. This paper attempts to evaluate the so called 'Geometrical Limits' concept to provide the Australian coal mining industry with a tool to assess the long-term behaviour of bord and pillar workings where the pillars are prone to failure due to spalling of ribs. In order to achieve this outcome, the principles of the safety factor concept and the probability of failure calculated using the coal pillar strength formulae have also been evaluated and practical design examples are presented in this paper.

Nov 25, 2010

By Peter L. McSwiggen

The mineralogy of the Biwabik Iron Formation changes dramatically from west to east as the formation nears the basal contact of the Duluth Complex. This reflects a contact metamorphism that took place with the emplacement of the igneous Duluth Complex at tem¬peratures as high as 1200 °C. However, the mineralogy of the Biwabik Iron Formation also varies vertically through the stratigraphy of the unit. This variability in both the vertical and horizontal dimensions makes it difficult to predict exact horizons where specific minerals will occur. The iron-formation has been subdivided into four broad stratigraphic units (lower cherty, lower slaty, upper cherty, and upper slaty) and into four lateral mineralogical zones (1-4). Zone 1, the westernmost zone, is characterized by quartz, magnetite, hematite, carbonates, talc, chamosite, greenalite, minnesotaite, and stilpnomelane. The silicate mineralogy in Zone 2 of the Biwabik Iron Forma¬tion changes very little. However, the minerals begin to change dramatically in Zone 3. Most significantly, Zone 3 is characterized by the appearance of grunerite in both a tabular form and a fibrous form. In Zone 4, the original silicate minerals have completely reacted, and a new suite of minerals occupies the iron-formation. These include grunerite, hornblende, hedenbergite, ferrohypersthene (ferrosilite), and fayalite.

Jan 1, 2007

By Peter L. McSwiggen

The mineralogy of the Biwabik Iron Formation changes dramatically from west to east as the formation nears the basal contact of the Duluth Complex. This reflects a contact metamorphism that took place with the emplacement of the igneous Duluth Complex at temperatures as high as 1200 °C. However, the mineralogy of the Biwabik Iron Formation also varies vertically through the stratigraphy of the unit. This variability in both the vertical and horizontal dimensions makes it difficult to predict exact horizons where specific minerals will occur. The iron-formation has been subdivided into four broad stratigraphic units (lower cherty, lower slaty, upper cherty, and upper slaty) and into four lateral mineralogical zones (1-4). Zone 1, the westernmost zone, is characterized by quartz, magnetite, hematite, carbonates, talc, chamosite, greenalite, minnesotaite, and stilpnomelane. The silicate mineralogy in Zone 2 of the Biwabik Iron Formation changes very little. However, the minerals begin to change dramatically in Zone 3. Most significantly, Zone 3 is characterized by the appearance of grunerite in both a tabular form and a fibrous form. In Zone 4, the original silicate minerals have completely reacted, and a new suite of minerals occupies the iron-formation. These include grunerite, hornblende, hedenbergite, ferrohypersthene (ferrosilite), and fayalite. © 2007 Elsevier Inc. All rights reserved. Keywords: Biwabik Iron Formation; Duluth Complex; Mineralogy

Jan 1, 2007

By R. H. Lien

The Bureau of Mines has conducted research on a flue gas desulfurization (FGD) process as part of its goal of minimizing the undesirable environmental impacts associated with sulfur dioxide (S02)-bearing waste gases. This FGD process, referred to as the modified citrate process, involves absorption of S02 in a buffered citric acid solution. The absorbed S02 is subsequently stripped from the solution using steam, which regenerates the solution and produces a wet S02 product. This product can be further processed to make sulfuric acid or liquid S02. Economic evaluations showed the process to be expensive when the stripper was operated at or near ambient pressures because of the large amounts of steam required for solution regeneration. Research was directed at reducing steam consumption in the stripper. The effect of stripper pressure on steam consumption was investigated. A process research unit (PRU) was operated with the stripper pressurized in the range of 5 to 150 psig. Test results showed that steam consumption decreased with increased stripper pressure. For example, when operating the PRU stripper at 150 psig, 4.1 grams of steam per gram of S02 was required to remove 90 pct of the S02 from a 1.0-vol-pct-S02 gas. This compares to 7.1 grams of steam per gram of S02 required for 90-pct S02 recovery at 5 psig.

Jan 1, 1982

Developments in the technology of explosive production and deliveryallow a greater amount of flexibility in rock fragmentation by blasting. The rock fragmentation efficiency of an explosive is currently given by a rating which is determined by the explosive manufacturers using proprietary formulae and methodology. Hence, comparison of explosives from different manufacturers may be misleading. Modeling of explosive energy, using a thermochemical code such as CHEETAH provides an objective standard by which the likely performance of different explosive formulations can be determined. Such modeling can be used for optimisation of explosive composition to match specific rockfragmentation objectives.

Jan 1, 2001

By Frank Cappuccitti, James A. Finch, Stéphanie Gélinas

"A colorimetric technique, originally developed for methyl iso butyl carbinol (MIBC) based on the Komarowsky reaction, has been extended to a wide range of common mineral flotation frothers. The procedure, which is briefly described, is shown suited to on-site determinations in a campaign at Kennecott Utah Copper Copperton Concentrator (Rio Tinto). Some observations are described, including: frother (MIBC) concentration evolution down a bank, frother distribution between pulp and froth phases, and loss of frother over time due to adsorption on certain minerals. A possible interference with a fuel oil addition was overcome. MIBC in recycle water was also measured.The ability to monitor frother easily will help interpret gas dispersion behaviour and should permit further optimization of flotation cell hydrodynamics and chemistry. The capability to directly measure should help optimize the type, amount and location of frother addition, and to assess frother recycled with reclaim process water.INTRODUCTIONOwing to the lack of analytical methods, the task of determining frother concentration in plant flotation circuits is not routinely performed. Industrial sites seldom outsource analyses that are both costly and inconvenient, due to the necessity of shipping freeze-dried samples to remote testing facilities. A more direct colorimetric method has recently been demonstrated for the laboratory characterization of common industrial frothers (Gélinas and Finch, 2004). The approach, based on the Komarowsky reaction (Penniman et al., 1936; Coles et al., 1942; Duke, 1947), was previously described by Parkhomovski et al. (1976) for methyl iso butyl carbinol (MIBC). The reaction involves the interaction of the OH group of a higher alcohol, concentrated sulphuric acid, and salicylaldehyde, to yield coloured solutions with intensities that can be analyzed by UV-visible spectrophotometry."

Jan 1, 2005

By T. A. Kirk

"The Linatex Dewatering System is a compact, low capital and maintenance cost matched set of processing equipment suitable for solids recovery, dewatering and desliming sand-like materials in the range 3/8"" to 325 mesh ( 1). Since its introduction to North America in the early 1970s, various elements of the system have been successfully installed in a variety of applic11tions both in Canada and the U.S.A. Examples are chosen from the coal, fine aggregates, iron ore and industrial minerals industries.II. Elements of the Linatex Solids Recovery System(A) The Linatex Separator (See Fig.I)The Linatex Separator, which is the heart of the system, is a specialized type of hydrocyclone designed to give a self regulating rope discharge product. It has the familiar cyclone geometry of cylindrical and conical section, tangential inlet, apex and vortex finder. The apex is enclosed in a unique patented automatic underflow regulator consisting of a collapsible rubber sleeve, and the overflow line is a siphon-leg, with a controlled air bleed valve. The siphon leg is adjusted so as to balance the internal negative pressure acting as a closing force on the underflow regulator against the mass of slurry pressing down on it from the cone section of the Separator. With correct adjustment the underflow regulator will close drip-tight on a water only feed. As solids accumulate in the apex of the cone the weight of solids counterbalances the vacuum and cat1ses the underflow regulator to open and discharge classified material at a controlled density."

Jan 1, 1978

By L. Kulik, J. den Drijver

Rhenish lignite will continue to play an indispensible role in the energy mix of the German Federal Republic for a long time to come. The use of lignite for electricity generation, upgrading and, if necessary, as a raw material is geared to the long term. The holistic management of opencast mines underpinned by approval law in the long term and a stronger focus on man, the environment and nature contribute to the acceptance of the mines by the local population. The same is true of state-of-the-art lignite uses: as regards their operational flexibility, lignite-fired power plants are ideal partners for the expansion of renewables. It is along these lines that RWE is continuing its power plant renewal programme as planned. With a view to that which will be conceivable the day after tomorrow, RWE is researching future technologies today in order to meet objectives such as security of supply, profitability and environmental compatibility to the same extent in the long term. Another important contribution to acceptance is public transparency and communications as means to support approval procedures and the implementation of measures in all areas related to lignite mining and utilization.

Jan 1, 2011

By A. Ebrahimabadi

Roadheaders are very versatile excavation machines used in tunnelling, mine development, and mine production for soft to medium strength rock formations. Performance prediction is an important factor for successful roadheader application and generally deals with machine selection, production rate and bit consumption. Among many different parameters, brittleness is also one of the material properties related to breakage characteristics and can be used as a cuttability parameter from a mechanical excavation point of view. The main objective of the research study is to contribute the brittleness of rock excavated to construct a new empirical equation for predicting the performance of roadheaders in different material and operational conditions. In this regard, a new performance prediction model for medium duty roadheaders based on a brittleness index (BI) is presented. In this study, rock mass brittleness index (RMBI) is defined in order to investigate the influence of BI on roadheader performance. RMBI is an index which can be used to relate the intact and rock mass characteristics to machine performance. Results demonstrated that RMBI is highly correlated to instantaneous cutting rate (ICR) (R²=0.94). Moreover, through the further analysis and normalization, the pick consumption index (PCI) was introduced as a parameter having a good relation with pick or bit consumption rates (PCR) (R²=0.79). Finally, the new predictive models for ICR and PCR showed very good correlations with the actual measured values. Keywords Performance prediction, roadheader, brittleness index, mechanical excavation.

Jan 1, 2011