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By Manuel Gomez

Bituminous coals having maximum fluidity values in the 40- to 25,400-dial-divisions-per-minute (ddpm) range were carbonized in a continuous, entrained-bed reactor. Carbonization was conducted in an 8-inch diameter, vertical reactor at temperatures from 955° to 1,345° F and at air-to-coal ratios ranging from 4.63 to 16.12 scf/lb of moisture-and ash-free coal charged. Carbonization rates from about 118 to 360 lb/hr, as-carbonized basis, were examined. It was demonstrated that carbonization temperature and air-to-coal ratio must exceed minimum values for continuous operation. Within the operating conditions discussed, highly fluid bituminous coal was carbonized to produce tar and nonagglomerated char. The yield of tar ranged from 21.3 to 38.9 gallons per ton and the char yield ranged from 1,109 to 1,563 pounds per ton, all units expressed on a moisture-and ash-free basis. It was demonstrated that the maximum fluidity and the average size of the coal along with the air-to-coal ratio and the carbonization temperature act together to influence the carbonization product yields and certain properties of the products. Prediction equations were developed from the data for product yields and selected properties of the char, tar, and gas.

Jan 1, 1968

By Gordon King

The City of Atlanta Water Department required the construction of a two sludge tanks and a wet well at the existing Chattahoochee Water Treatment Plant. Western Summit won a design build contract to build the project and proceeded to evaluate the wet well size options, and construction procedures. The final design required the construction of a 1 million gallon tank. The proximity of the underground tank to adjacent roads and existing plant structures ruled out laying back the excavation. As a result a tied back sheet pile retaining wall was initially proposed.

Jan 1, 2003

By Clyde N. Baker

Foundations for the Sohio Corporate Headquarters in downtown Cleveland have column loads of 11,400 kips, which increase to 15,000 kips with wind loading. An extensive exploratory program was conducted and comprehensive studies made to select the economically dependable support for the 46-story structure. A test on bond or socket friction for the caissons has usable values.

Jan 1, 1984

By Willard L. Hunter

The research described in this Bureau of Minus report was conducted to improve the chromium-iron ratio of offgrade chromite. Two methods were used: (1) Iron was selectively reduced from chromite by carbothermic reduction in an electric-arc furnace, and (2) a mixture of carbon, chromite, and sometimes fluorspar was chlorinated to remove a substantial part of the iron. Chromite concentrate from the Mouat deposit in Montana and from northern California was used in the test work. Chromium-bearing slag and chromite that had been beneficiated by a roast-leach process were each smelted to produce high-carbon ferrochromium. Iron was selectively reduced in a laboratory-scale., electric-arc furnace. Carbon additions to the smelting charges varied from 40 to 100 percent of the stoichiometric requirement, and slag basicities were varied from 0.4 to 1.0 chromium-iron ratios of more than 4:1 were obtained with 89 percent recovery of chromium in a chromium-bearing slag.

Jan 1, 1962

By Archie Richardson

The trona mines in the Green River Basin, commonly known as the "trona patch," present an interesting set of rock mechanics issues stemming from mining in a unique underground environment. Like other minerals occurring in tabular deposits, trona is mined using high-productivity room-and-pillar and longwall methods. However, trona does not behave quite like other evaporites and behaves far differently than coal. In this paper, the following key issues in trona patch rock mechanics are discussed: material properties, in situ stress field, water and gas pressure effects, creep characteristics, pillar behavior, roof span stability, floor stability, underground tailings storage, longwall mining, two-seam mining. and solution mining. Many of the existing trona producers are entering potentially more difficult mining conditions, and much consideration is being given to "new" technologies such as longwall mining and solution mining. In analyzing 20 years of experience with trona patch rock mechanics issues the authors have identified key comparisons and contrasts with conventional tabular deposit rock mechanics that will help illuminate what has been learned as the trona patch enters the 21" century.

Jan 1, 1999

By K. M. Tompson, R. L. Armstrong, C. I. Godwin

"Tungsten skarn deposits on the Clea property in the Selwyn Mountains, Y. T., are related genetically to a quartz monzonite stock, about 500 metres in diameter at the surface. Lower Paleozoic sedimentary rocks are metamorphosed for a distance of 3 km from the stock. Tungsten-bearing skarn mineralization within the altered sedimentary rocks is of two types: sulphide-rich pods and calc-silicate beds. The most significant scheelite concentration is in calc-silicate beds near or adjacent to the quartz monzonite stock. Discordant K-Ar and Rb-Sr isotopic dates indicate that the stock is probably of early Late Cretaceous age, 94 Ma or slightly older, and that it cooled slowly. High initial 87Srl86Sr ratios and disequilibrium relationships between K-jeldspar phenocrysts and groundmass minerals in the porphyritic phase of the granitic rock , and between different granitic rock specimens, indicate contamination of crystallizing magma by old sialic continental crust which extends westward under the Selwyn Basin.This study is significant to regional tungsten exploration. Granitic rocks associated with tungsten deposits, in this part of the Canadian Cordillera at least, appear to have specific isotope characteristics that indicate they were generated at a specific time and in a particular way.IntroductionThe Clea tungsten skarn property (Fig. I) is owned by Canex Placer Limited, and lies in the Selwyn Mountains (Bostock, 1948) near the eastern margin of the Selwyn Basin (Wheeler and Gabrielse, 1972), Yukon Territory. The property covers a 20-square-mile area centered near latitude 62°47 ' north and longitude 129°52' west, and is accessible by helicopter. An airstrip and the terminus of a summer-use gravel road at MacMillan Pass, Yukon, are about 20 miles to the northnorthwest.This paper deals mainly with the geochronemetry of granitic rocks from a stock associated with tungsten mineralization on the Clea property. We show that these rocks have specific characteristics that not only define the genesis of this stock, but also have significance for regional tungsten exploration around plutons in the Canadian Cordillera."

Jan 1, 1980

Geological hazards such as faulting, basement ridges, and zones of "thin" (< 6 m) coal have a major impact on mining economics of underground operations in Huntly Coalfield. Experience has shown that drillhole-based investigations do not yield sufficiently detailed models of the coal seam to allow management of the planning risks associated with these hazards. Consequently, operational performance is affected by unplanned costs associated with lower productivity, loss of coal reserves, and expensive strata control remedies in problem ground conditions. Huntly Coalfield is a challenging environment for acquisition of good quality seismic reflection data due to the very thick (10-85m) weathering layer. Since 1994, successful acquisition of 2D and 3D data has been achieved through a combination of careful testing of technical parameters and experimental trials prior to committing to production recording. High resolution seismic reflection (HRSR) is proving to be an investigations technique which generates accurate and reliable models of the coal seam and associated structures, such as normal faults and topography of the surface on which the coal seam rests. The HRSR technique has been applied and developed in the Okowhao Sector where Huntly East Mine is developing and extracting coal reserves. Results of a recent 3D survey demonstrate that this technique is capable of revolutionising risk management in mine planning for underground mines in structurally complicated coal deposits.

Jan 1, 1997

By Gerald Stolarczyk

The Radio Imaging Method (RIM) is based upon electromagnetic (EM) wave propagation in the coal seam waveguide. The radio geophysics theory underlying RIM was developed by Hill of the national Institute for Science and Technology (Hill, 1984). Recent advances in radio geophysics instrumentation have increased operating range in the coal seam waveguide to almost 3,000 feet. This paper describes RIM longwall panel reconnaissance scans and tomography results.

Jan 1, 2006

By E. H. Jr. Dix

THE use of magnesium as an alloying element in aluminum alloys has been limited, in general, to comparatively small quantities. In duralumin-type, strong-aluminum alloys, magnesium is present to the extent of ½ to ¾ per cent. and various grades of Magnalite and the "Y" alloy of the National Physical Laboratory of England contain up to 1 1/2 per cent. In this country small quantities of aluminum alloy sheet containing 4 per cent. magnesium are produced commercially. All commercial aluminum contains sufficient silicon to convert a portion of the magnesium added to the compound Mg2Si. It is well known that the solubility of both magnesium and magnesium-silicide decrease with decrease in temperature. It is, therefore, impossible to separate the age-hardening effect of the magnesium-silicide from that of magnesium, except by the use of aluminum of such high purity that the silicon content is negligible. The present paper is the fifth1, 2,3,4 of a series from the laboratories of the Aluminum Co. of America reporting the results of investigations of the equilibrium relations in aluminum-rich alloys made from the high purity aluminum manufactured by this company .5

Jan 1, 1929

By Michael Amick

Over the last few years as the coal industry has seen an increase in the price of coal, a renewed interest in the additional mining of pre-law highwall sites has occurred. Much premium coal and property remains behind these pre-law highwalls but access to mining is limited because prior mining used auger machines to remove coal from under the highwall. Older augers seldom reached more than 200 feet and often no more than 100 feet but this zone of auger holes destabilizes the highwall to where additional mining is often unsafe. If the reserve is large enough, the highwall can be stabilized with common flyash and cement grouts to form a face-up for an underground mine but this expensive method is usually not practical for continuous use with a highwall mining machine. It is estimated there are hundreds of miles of highwall riddled with auger holes where the coal reserve available is ill-suited for deep mining for a variety of reasons. However, these same properties are ideal for additional mining with state-of-the-art highwall mining machines that have a reach up to 1200 feet, except to the relatively thin auger mined de-stabilized zone. The renewed interest in highwall mining these properties has driven research into finding an economical way to stabilize the highwall so the highwall mining machine can recover additional coal. This research discovered and fine-tuned a process that is economical and is successfully supporting the highwall at a highwall mining operation. This paper discusses the research involved in determining the strengths need, the methodology used to place any grouts, the effect on mining plans and the increased recoveries. ARMPS-HWM is used extensively in this research. The failure of the highwall, when not grouting, and the success, when grouting using the new materials and equipment utilized, confirmed the ARMPS-HWM method.

Jan 1, 2007

By R J. Holmes

The procedures and equipment used for sampling iron ore process streams have generally improved in recent years. However, there are a number of areas where significant issues still commonly occur, including sampling high capacity streams, sample cutter design and operation, division of primary increments at the secondary sampling stage, the performance of crushers installed to reduce the particle size prior to sample division, and the sample mass that is retained at each sampling stage. These issues of non-conformance with correct sampling principles are caused by factors such as increasing the speed and loading of conveyor belts to increase throughput, which changes the trajectory of the ore stream and may result in an inability of the sample cutter to handle the increased flow rate without sample loss. Failure to sample the entire primary increment stream at the secondary sampling stage is also a common issue as well as failure of crushers to provide crushed products of the required particle size due to ongoing maintenance and/or adjustment issues. These common pitfalls can all be addressed through careful attention to detail.CITATION:Holmes, R J, 2017. Common pitfalls in sampling iron ore, in Proceedings Eighth World Conference on Sampling and Blending , pp 261–264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Clayton V. Deutsch

Indicator Kriging (IK) is being commonly applied to mineral resource assessment problems. More recently, indicator simulation has also been used for sensitivity analysis and difficult change of support problems. The essential theory underlying indicator geostatistics has not changed since its introduction 10 years ago; however, the last decade has produced many important developments in its implementation. The objective of this paper is to consider some of the more important implementation details. Examples from the Porgera gold deposit in Papua New Guinea are used to illustrate the steps in an indicator geostatistical study and the importance of various implementation decisions. Specifically, in many precious metals deposits the continuity of the grades is typically quite anisotropic. This anisotropy varies in both magnitude and direction throughout the deposit. Building a model of this anisotropy can considerably improve the local kriged or simulated points. One approach to build this model is presented. In addition, there is typically more than one mineralization style and geological rock type; the spatial character of the mineralization can be quite different within each geological rock type. The rational treatment of anisotropy and geological subdivisions is common to all mineral resource assessment procedures; the importance of this qualitative geological information is not diminished with more sophisticated techniques such as indicator kriging. This paper presents an overdue comprehensive look at the practical aspects of indicator methodology. Many of the techniques and procedures documented in this paper have been developed during the course of detailed mine feasibility studies.

Jan 1, 1992

By C. E. Hennig

On January 1, 1961 there were 311 petroleum refineries in the United States with a total crude-oil throughput capacity of slightly more than 10 million barrels per day, according to the Bureau of Mines' annual survey. Compared with a year ago, this represents net increases of one in the number of plants and 109 thousand barrels per day in total capacity. Contributing to this increase was the completion of two new plants, one in Hawaii and another in Michigan, during the year. At the beginning of 1961 the industry was building facilities which will increase this overall crude capacity by 36,500 barrels per day. As part of its building program, it was also replacing 329,000 barrels per day of its present capacity. Of the total 10 million barrel per day installed capacity, the industry reported 380,000 barrels per day as being shut-down on January 1, 1961. This included 11,500 barrels per day considered inoperable without extensive reconditioning.

Jan 1, 1961

By Litvinenko V. I

Being a source of structural materials for many centuries, the modern image of the ferrous metallurgy is burdened with obsolete technologies with disregard towards new environmental protection requirements. The production cycle of metallurgical products have two clear-cut stages: I . production of liquid metal and casting into steel billets; and 2. processing of steel billets in solid state under high temperature to produce various shapes and profiles of metal products. Plastic deformation of metal at the second stage is least associated with environmental pollution and is presently being provided with more and more advanced equipment.

Jan 1, 1999

By H. Aykul

The choice of which mining method to use at many large surface coal mines is often dicated by what machinery is available or what experience the mine management can offer. One of the most significant surface coal mines in Turkey is owned and operated by the Turkish National Coal Board, located to the west of the city of Kütahya. The Seyitömer Lignite Enterprise (SLE) extracts low quality coal, the majority of which is supplied to an adjacent power station. The coal seems at SLE contain bands of ash which under normal mining conditions are extracted with the coal. This increases the ash content of the run of mine coal and results in lower efficiency at the power station and financial penalties for SLE. In this paper, therefore, selection of the best possible equipment and production method was identified to achieve high selective mining at SLE. The research found that two different high selective mining methods were suitable for selective excavation of the B3 seam, which were hydraulic excavator and truck and surface miner and truck combinations. It was also found that high selective excavation could provide the desired coal quality at 52% lower costs when the whole process (excavation, transportation, processing, etc.) was considered. Keywords: coal mining, surface mining, selective mining.

Jan 1, 2007

By André de Jager, Henk Ludik

Navachab Mine experiences difficulties with pit wall stability in certain areas of the mine. The main reason for the instability is the fact that the geology comprises many joints and faults. Blasting, without impacting negatively on the stability of the pit walls, poses a major challenge. The mine has installed a technologically advanced seismic monitoring system with monitoring sensors positioned at various locations and depths throughout the pit. The electronic data recording system records all relevant information on a continuous basis with early warning signals in cases of potential danger. From the information recorded by this micro-seismic system it was established that the energy release into the high-wall is predominantly influenced by the mining rate, water content and mining tempo and to a lesser extent by the blasting operations. To limit the negative effects of blast vibrations, the use of Electronic Delay Detonators (EDDs) was introduced. The optimal delays were determined through signature trace analysis. The vibrations obtained during blasts initiated by means of electronic delay detonators were monitored and compared to those traditionally obtained when standard pyrotechnic delay detonators had been used. The measured vibration data indicated an improvement of 25% to 100% drop in vibration amplitude compared. The accuracy and programmability of EDDs presented huge potential for blast optimization in terms of limiting the vibrations without compromising fragmentation. The whole project was conducted over a twelve week period with some 4000 EDDs. The average size of a blast was in the order of 350 holes using about 40kg explosives per hole, which equates to 14,000 kg explosives over 12 different blasts. The paper deals in detail with the blast optimization process with regard to: - determining the rock response time; - establishing the signature traces; - analyzing the wave interference patterns; - predicting the direction of constructive and destructive wave interferences; - optimizing of the inter-hole and inter-row delay periods; - measuring the ground vibrations. The results obtained during electronic blasting are compared to those obtained during pyrotechnic blasting. Comparisons are being made with regard to the following: - ground vibration measurements; - pit wall stability measurements; - blast safety.

Jan 1, 2006

Separation of Iron Particles from Banded Haematite Quartzite (BHQ) Ore by Selective Magnetic Coating The separation of fine iron particles from banded hematite quartzite (BHQ) has been studied using selective magnetic coating. The BHQ ore assays as 38.9 per cent Fe, 42.5 per cent SiO2 and 1.0 per cent Al2O3. Mineralogically, the ore contains hematite and quartz as the major mineral phases where as goethite and magnetite is present in minor entities. Natural magnetite of very fine size and oleate-magnetite in colloidal form, prepared synthetically in the laboratory are used as the coating material on the surface of hematite particles. The selective coatings of oleate-magnetite on BHQ surfaces followed by magnetic separation studies have indicated that, it is possible to achieve 62.3 per cent Fe with 8.5 per cent SiO2 at 85.4 per cent iron recovery. The recovery of iron values is found to be superior in comparison to the conventional magnetic separation techniques. The selectivity of coating for enhancing the magnetic response of iron particles is achieved by controlling the surface properties of the particle via electrokinetic potential adjustment by controling pH and addition of oleate-magnetite. In the separation process, the effects of pH, magnetic intensity and addition of oleate-magnetite are studied to achieve the maximum grade and recovery of iron values. The optimum separation is observed at pH of 7.5, oleate-magnetite concentration of 0.25 ml/g of BHQ ore and a magnetic intensity of around 0.8 Tesla. The X-ray diffraction (XRD), Infra-red spectroscopy (IR) and UV-visible spectroscopic studies strongly suggest preferential coating of magnetite on hematite surfaces. Scanning electron microscopy (SEM) studies have brought out the semi-quantitative features of BHQ ore. The recovery of iron values from a lean grade ore such as BHQ is carried out looking into the future needs of this ore in India for iron and steel making.

Sep 13, 2010

By L. Hanschar, C. Bwalya, E. Mokola, K. Musonda, A. Makayi

This paper describes the installation, commissioning and operation of porous plugs featuring nitrogen gas purging in both Anode Furnaces at the Kansanshi Copper Smelter (KCS), a greenfield copper smelter which commenced operation in March 2015. The decision to install porous plugs was taken in November 2016 and the facilities were successfully commissioned on both anode furnaces in October 2017. The project was successful and has demonstrated the following process improvements: 12.2% reduction in main burner fuel consumption Larger average charge size, due to fewer accretions; 17 minute decrease in average refining cycle times Improvements in slag skimming operations Improved casting rates INTRODUCTION Porous plugs The application of porous plug technology in copper smelter anode furnaces is well established around the world. Vukovic and Gamweger (2017) and Wallner (2004) noted that the stirring and mixing action induced by the injection of inert nitrogen gas into the molten copper via porous plugs has potential benefits in the following areas: Homogenization of the temperature and composition of the molten copper resulting in Reduced fuel consumption Less tendency to overheat slag (reduced risk of refractory attack) Less slag produced with a lower degree of oxidation (lower rate of refractory wear) Less tendency for buildups to form Improved environmental performance (produce low sulphur blister at Peirce Smith converters) Elimination of buildups inside the furnace and potential for larger charges per cycle Reduced processing times and potential for shorter cycle times More efficient skimming of anode slag Shorter skimming time Less copper carry over to Peirce Smith converters Very little slag remaining in the furnace (reduced potential for buildups to form)

Jan 1, 2019

By D. Bitzios, A. Gracia, V. Meggiolaro, J. D. Baker

Synthesis report on a project carried out under the EC-funded BRITE-EURAM programme. A large deposit in Spain and several smaller ones in Greece and Sweden were investigated. Beneficiation testwork, including the development of an innovative wet circuit, was undertaken in Italy. The Spanish Ilustracion deposit lies occurs in thin, white layers throughout a zone 35-40 m thick and 1.5 km long, in laminated calcsilicates. Total resources of more than 100 000 000 t include proven open-pittable reserves of 4 500 000 t averaging 35% wollastonite. The beneficiated product is suitable for various applications, including ceramics. The Swedish and Greek marble-hosted skarn deposits include Albatross, with 2 500 000 t of reserves at 30% wollastonite, and Panorama, with reserves estimated at more than 700 000 t

Jun 21, 1905

By D. H. Desy

The Bureau of Mines has conducted research on the ignition of methane-air mixtures by sparks caused by frictional impact of aluminum alloys on rusted steel at typical coal mine fan speeds. The objectives were to establish the incendivity of aluminum alloys under these conditions, to investigate differences between aluminum alloys, and to evaluate substitute materials for the aluminum-steel combination. With a specially designed apparatus, three commercial aluminum casting alloys and a number of experimental aluminum alloys were tested for incendivity of the frictional impact against rusted steel in flammable methane-air mixtures. All aluminum alloys tested produced some ignitions. Of the experimental alloys, the harder alloys and those containing silicon tended to be more incendive than the others. With the normal experimental conditions, constructional steel, stainless steel, brass, and plastic did not cause ignition of methane-air mixtures in frictional impact against rusted steel. Some ignitions occurred with constructional steel at high speed in more flammable gas mixtures enriched with oxygen. From these findings, it is suggested that constructional material combinations other than the aluminum-steel combustion would minimize this inc endive hazard. A detailed description is given of previous research, and comparison is made with present results where appropriate.

Jan 1, 1975