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By Gregory Harbort, Sarah K. DeBono, Alan J. Monaghan, Emmanual V. Manlapig

"The Jameson Cell is a type of flotation machine in which air and pulp are brought together in a vertical tube called a downcomer. Within the downcomer the air and pulp are dispersed into a dense foam of fine bubbles, which creates a favourable environment for bubble-particle collision and subsequent collection of hydrophobic particles. The intense collection zone within the downcomer can be considered similar to the zone between the rotor and stator in mechanical flotation cells.Research into the bubble-particle collision and fluid dynamics of mechanical cells rotor-stator zone has been limited by the difficulty of achieving accurate measurements in production sized machines. With the Jameson Cell the downcomer is largely external and separated from the flotation tank, allowing ready access to the primary contacting zone for measurement and analysis.An investigation has been undertaken into the operating characteristics of the downcomer relating to bubble-particle collision. An effective mapping of the downcomer has been made through measurements of void fraction and bubble size taken across cross sections of the downcomer. Analysis of these measurements has provided an interpretation of the variations in the air and fluid dynamics, bubble size and distribution throughout the downcomer chamber.Existing models of bubble-particle collision efficiency are reviewed in respect to the collected information and refinements conducted. The area of maximum bubble-particle collision efficiency is defined. Findings are related to operation within the rotor-stator zone of mechanical flotation cells."

Jan 1, 2003

By G. W. Birge

As a part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report.2/ The inherent suitability of coal for metallurgical use depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, as well as the available reserves, are considered in selecting coals for carbonization tests. The selection of coal beds in Westmoreland County for coking tests was based, in part, on estimates of the coal reserves by Dowd,3/ who estimated the recoverable reserves in beds 28 inches or more thick, in thousands of tons, as follows: [ ]

Jan 1, 1957

By Animesh Jha

"Fine ceramic powders (<500 nm) exhibit exceptional physical and mechanical properties in engineered structural ceramics. The production of fine powders, in particular the non-oxide ceramics, via a cheaper route than the organic solvent route has been rather elusive. This paper examines the physical chemistry of sub-oxide vapour-phase reduction reaction for the nucleation of non-oxide ceramic phase. Well known vapour species eg SiO and BO in the production of technical ceramic powders (SiC, BN) are particularly discussed for understanding the nucleation process of SiC and BN ceramic phases respectively. The regimes of partial pressures and temperatures are particularly 'identified. The calculated nucleation rate as a function of the temperature is compared with the experimental results on powder morphology. The production of amorphous and nanocrystalline h-BN powders is discussed in the context of substrate structure and thermodynamic parameters.IntroductionThe physical and mechanical properties of ceramic components are strongly dependent on the powder particle size and morphology used for their fabrication. For example the strength (Os) of the structural ceramic components increases with decreasing average grain-size (d) in accordance with the Hall-Petch relationship: Os = 0""0 + k/(d)1/2. Here k is an empirical constant which can be established from the graphical relationship. However as the particle size approaches submicrometer-size range, the dependence of strength on the particle size becomes more complex [1]. The design of ceramic components based on nanometer-size particles have recently become an important field which can offer ceramic materials with properties comparable to their metal counterparts. Several materials based on these concepts have been developed and reported by Niihara [2]. For example, the Al2O 3-SiC nanocomposite, having average B-SiC grain size 0.3-2um with intragranular SiC particulates of 5-10 nm has unusually high strengths (1100 MN/m2) at low and elevated temperatures combined with enhanced fracture toughness (> 4 MN-ml.5) which is an unusual combination in structural ceramics. Besides mechanical properties, as the particle size of ceramic powders approaches the nanometer-size range, the charge transport properties also improve by many times. The effect of particle size on the electrical conductivity of Si3N4-TiN composites has been well documented [3.4]. The size of ceramic particulates without doubt plays a pivotal role in determining the properties of ceramic components."

Jan 1, 1996

By Serge Lavoie

Alcan&apos;s Guillaume-Tremblay plant, located in Jonquiere, Quebec, has been in operation since 1990. This was the first plasma dross processing plant ever built. In addition to the use of the plasma heating technology, Guillaume-Tremblay has other unique features making it a modern and efficient dross processing facility. This paper presents a general overview of the practical experience at the Guillaume-Tremblay plant. In particular, the utilization of plasma heating in industrial conditions, the metallurgical performance, the unique dross handling system, the control and information management system and the reclaiming of the by-products will be discussed. Finally, the use of the plasma process for salty dross will be addressed&apos; briefly.

Jan 1, 1995

By Glenn Mongillo

Discrete Element Method (DEM) software has been successfully used to simulate various machine/soil interactions and provide insight for industries such as mining and bulk material processing. This paper will investigate typical calibration techniques used in particle models for DEM simulation and physical calibration experiments with soft ground TBM cutting tools to incorporate parameters such as tool drag forces that contribute to required TBM torque. With a well calibrated DEM model, it is expected that TBM simulation results will be more meaningful and provide better insight into TBM performance, power requirements, cutting tool placement, and overall cutter head design.

Jun 13, 2021

By Greg Nutson, Jeremy Butkovich, Bill Perkins, Hollie Ellis, Paul Bott

"Dynamic soil-structure interaction (DSSI) analyses are becoming more common in bridge designs, especially in seismically active areas. Because of its proximity to two active fault zones, the Evergreen Point west approach bridge replacement will be base isolated, and will be designed using DSSI. The project team completed two independent bridge designs to satisfy peer review requirements. The designs required substantial characterization of the soil dynamic behavior using both laboratory and in-situ testing. The analyses made use of earthquake time histories spectrally matched to conditional mean spectra. This led to reduced, and more realistic seismic demands on the structure, compared to conventional uniform hazard spectrum matching. The bridge analyses suggest that the preliminary bridge design is relatively conservative. This will allow the design team to potentially reduce shaft/column diameters and reinforcement. The design team estimates that the dynamic analysis design could represent a net savings of around $60 to $90 million compared to a conventional design.INTRODUCTIONThe Evergreen Point Bridge conveys State Route (SR) 520 2.6 miles (4.2 kilometers [km]) from Seattle to Medina across Lake Washington. The bridge is located in a seismically active area, and the Washington State Department of Transportation (WSDOT) has determined that the western half of the 1960s-era bridge (the “west approach”) is vulnerable to earthquake damage. WSDOT has begun preliminary design to replace the west approach bridge.The west approach extends about 6,100 feet (1,900 meters [m]) east from Seattle’s Montlake neighborhood, over Union Bay and Foster Island, then into Lake Washington proper (Figure 1). Approximately 5,600 feet (1,700 m) of the replacement bridge would be constructed over water. Subsurface conditions along the bridge alignment consist of 5 to 80 feet (2 to 24 m) of very soft peat and clay, over very dense/hard sand and clay. Multiple pile supported columns support the existing bridge. The new bridge would be supported by 8- to 10- foot-diameter (2.4 to 3.0 m) drilled shafts that extend about 50 feet (15 m) into the underlying very dense/hard soil. To reduce seismic demands on the bridge superstructure, WSDOT has decided to incorporate a base-isolation system into the bridge design."

Jan 1, 2017

By Raymond W. Hiteshue, Henry H. Ginsberg, Paul S. Lewis

Coal was gasified in the presence of up to 3.57 million roentgens of gamma rays by the Bureau of Mines to determine whether the irradiation increased the gasification rate or yields of methane and hydrogen . High volatile A bituminous coal was gasified with steam at 500 and 1,500 psig and temperatures of 1,400 ° and 1,800 ° F ; five other coals ranging in rank from lignite to anthracite were gasified at 500 psig and 1,800 ° F. The average results of replicate experiments with and without radiation were compared for possible effects of radiation from 40,000 curies of radioactive cobalt . The irradiation had no gross effect on the gasification rate or on the yield and distribution of methane and hydrogen . It was concluded that gammaray irradiation produced no improvement in the technology or economics of coal gasification .

Jan 1, 1964

By I. AITKENS

The basic mining law of Cuba is contained in the basic Spanish mining decree having the effect of law December 29 , 1868. This legislation has remained substantially unchanged , with the exception of a few minor administrative changes made by the present Government . These changes provide for the register of mines , oil wells , and operations of such nature , and also provide for the keeping of records showing the value of minerals taken out . By Royal decree of April 17 , 1883 , the law of mines enacted for the Peninsula ( Spain ) on July 6 , 1859 , and the General Bases of December 29 , 1868 , were declared in force in Cuba . In order to encourage the mining of iron org , in 1883 the Crow of Spain issued a royal decree to the following effect.

Jul 1, 1931

By Xin Li, Hai-Xing Fang, Bing Xie, Hong-Yi Li

Chromium-containing vanadium slag (V-Cr slag) was obtained by an industrial smelting process of Hongge Ore, which is valuable vanadium-titanium magnetite to extract V and Cr in China. Sodium roasting thermodynamics of V-Cr slag in presence of oxygen were calculated to evaluate the reactivity of chemical compounds. Results showed that the oxidation of FeV2O4 was intensified in presence of Na2CO3 while the oxidation tendency of FeCr2O4 was far lower than that of FeV2O4. It was probably that reactions of impurities including Al2O3, SiO2 and Fe2O3 with Na2CO3 happened and the products can promote the oxidation of vanadium or chromium compounds in lower valence. Based on thermodynamic analysis, a two-step selective extraction process of vanadium and chromium was proposed. Extraction rate of vanadium was 88.6% while 7.0% for chromium in the first extraction step; extraction rate of 90.7% and 95.4% for vanadium and chromium, respectively, were obtained in the second step.

Jan 1, 2014

By K. Huttu, A. van Wageningen

"The Kittilä underground mine in northern Finland is extracting one of the largest known gold deposits in Europe. Kittilä achieved commercial production on May 1, 2009, becoming Agnico Eagle’s first mine to open outside of Canada. The Kittilä orebodies were initially mined from two openpits – Suuri and Roura – and underground operations were added in October 2010. The pits were mined out in November 2012, so mining is now entirely underground in the Suuri and Roura deposits. Additional, small openpits will mine any remaining near-surface reserves in the future.The Kittilä Mine is located in the Lapland region of northern Finland, approximately 900 km (560 miles) north of Helsinki and 150 km (93 miles) north of the Arctic Circle. With a mine life estimated through 2034, Kittilä is Agnico’s longest-life mine.The mine’s proven and probable reserves contain 32 Mt (4.7 million oz) at 4.6 g/t (0.13 oz/ st) gold. Ore has been mined from underground since 2010. The original 3 kt/d (3,300 stpd) operation underwent an expansion project to increase the throughput capacity of the mill by 1 kt/d (1,100 stpd), starting by the end of 2014.The region around the Kittilä Mine is underlain by mafic volcanic and sedimentary rocks of the Kittilä Greenstone Belt oriented nearly vertical. This greenstone belt is similar to those hosting Agnico Eagle’s Canadian deposits in Quebec’s Abitibi region and Nunavut. At the contact point between ironrich and magnesium-rich rocks lies a 100- to 200- m (330- to 660-ft) thick structural zone known as the Suurikuusikko Trend. This trend hosts the Kittilä deposit, where multiple mineralized zones have been traced over a strike length of more than 25 km (15 miles).Most of Agnico Eagle’s work has focused on a 4.5-km (2-mile) segment of the Suurikuusikko Trend that hosts the five main zones of the known gold reserves and resources. From south to north they are: Ketola, Etela, Suuri, Roura and Rimpi.The ore at the Kittilä Mine is refractory, making gold extraction relatively difficult because the gold is generally locked inside the two main sulfide minerals – arsenopyrite and arsenic-rich pyrite. Only about 4 percent is very fine-grained “free gold” (not locked in sulfide grains) and easier to extract. Most of this free gold is found in the outer, oxidized or eroded sections of the ore."

Jan 1, 2015

By C. Harold Riches

This article is directed co a commentary on the patent system in its relation to the public interest. As man gained supremacy over his environment, he could devote progressively increasing portions o his time to improving his standards of living. In the history of the human race, we have advanced from the hollowed floating log to the modern steamship of the present age; from the sickle and flail to the reaper and combine; from the trumpet and drum as a means of communication co the telegraph, telephone, and radio; from the horse and ox cart to the automobile, truck, aeroplane, and train; and so on ad infinitum through the list of inventions on which are based the industrial and political economies and standards of living we enjoy today. It has also been a long road from the day of the alchemist and his closely guarded secrets to the era of the patent system and its storehouses of knowledge open to the world. The alchemist and the craft and merchant guilds closely guarded their secrets. In fact, they largely opposed innovations on the grounds that they might injure profits and restrict employment. In these days of unrest, with great clamour out of doors for radical changes in our political and industrial economies, it may not be untimely to examine one of the keystones which support the economic structure we know as the free enterprise system, the system which is predicated upon the right of the individual to own property. Many, through impractical idealism, ignorance, confused thinking, or blind political prejudice, advocate the substitution of ownership by the State ? for the right of ownership by the individual. As civilization has advanced to the high standards of living we enjoy today through the efforts of a comparatively few inventors, the patent system which has provided the incentive that created the inventions on which our industries and our employment are based is fully understood and appreciated by a comparatively small percentage of our people. As a result, the patent system, as a keystone in our free enterprise economy, is an apt target for destructive criticism, with the thought, possibly, that by eliminating or drastically restricting the several rights to individual ownership one by one, ownership by the State will progressively replace ownership by the individual.

Jan 1, 1949

In the spring of 1944 the Congress passed Public Law 290 (58 Stat. 190, 30 U. S. C. Sec. 321) "authorizing the construction and operation of demonstration plants to produce synthetic liquid fuels from coal, oil shales, agricultural and forestry products, and other substances, in order to aid the prosecution of the war, to conserve and increase the oil resources of the Nation, and for other purposes." Section 2 reads: "In order to carry out the :purpose of this act, the Secretary of the Interior is authorized- (a) to conduct laboratory research and development work, and, with pilot plants and semi-works plants, to make careful process engineering studies, along with structural engineering studies, in order to ascertain lowest investment and operating costs necessary to determine the best demonstration plant designs and conditions of operation;

Jan 1, 1948

By Paolo Cavalcoli, Federico Pagliacci, Marco Chiarabelli

"The Sheikh Jaber Al-Ahmad Causeway Project in Kuwait is estimated at approximately $US3.7 billion and consists of constructing a causeway across the Kuwait Bay, connecting the Shuwaikh Port with the northern Subiyah area, where the new “Silk City” will be established. The $US77 billion Silk City will revive the ancient “Silk Road” trade route and will become a major free trade zone linking central Asia with Europe. The new city will be completed in 2030, it will house about 700,000 people and, furthermore, it will include the tallest tower in the world. The Causeway will stretch approximately 23.3 miles and will be composed of a combination of low-level bridges, embankments and transition islands. A bridge of about 16.8 miles in length will span the navigation channel and a free flow interchange at the Shuwaikh Port will connect the causeway to the main road network in Kuwait City. The geo-construction portion of the project involves the execution of 1,200 drilled shafts with diameters of 98 inches and 118 inches embedded to a maximum depth of about 276 feet. Details are provided concerning the subsurface conditions, the geotechnical characteristics and the strength parameters, illustrating, as well, the installation technique implemented for the construction of the drilled shafts. In addition, particular attention is paid to the description of the challenges faced while constructing the drilled shafts at a distance of about 10 miles from the shore, such as the depth of the water above the midline (more than 160 feet), an underwater current and the tidal variation.INTRODUCTIONThis paper presents an overview of the foundation works executed for a 37km causeway across the Bay of Kuwait, connecting Shuwaikh Port with Subiyah New Town Development. The project, in which Trevi is actively engaged, includes a 27 km low-level bridge across the bay, a main bridge with a span of 200 m, an overpass and a 5 km approach road onshore in Subiyah.The main purpose of this report is to provide information about the nature and features of the applied technique of bored piles, including a description of each work phase and other related details, in order to aid in the design of the foundations for the proposed construction.Works for the soil investigation were carried out in accordance with accepted geotechnical standards/guidelines. Brief descriptions of the methodology of the field are also provided in this report."

Jan 1, 2016

By P. R. Miles, J. K. H. Ma, J. Y. C. Ma, L. Bowman

"The bisbenzylisoquinoline alkaloids are compounds which can be isolated from plants and which exhibit a broad range of pharmacological activities. Perhaps the best known alkaloid of this group is tetrandrine (TT), a compound isolated from the root of a traditional Chinese medicinal herb, Stephania tetrandra. It has been tested for its effects on the cardiovascular system, tumors, and the lungs. For example, tetrandrine has been shown to act as a calcium entry blocker in cardiac sarcolemmal vesicles (King et a/., 1988) and has been used in China as a treatment for angina and hypertension. Its possible effects as a tumor-inhibitory substance have also been investigated (Kupchan and Atland, 1973). In addition, there are several lines of evidence to suggest that it is a possible therapeutic agent for the treatment of silicosis. Yu et a/. (1983) have shown that TT inhibits the development of experimental silicosis in rats when it is administered orally after intratracheal instillation of quartz. Other studies have shown that the alkaloid inhibits the synthesis of collagen by fibroblasts and the formation of silicotic nodules in rats exposed to silica (Huang et al., 1981; Liu et al., 1983). In fact, tetrandrine has been used clinically in China as an antifibrotic agent and has been shown to improve both the appearance of chest radiographs and the measurements of diffusing capacity in patients with silicosis (Li et al., 1981).Since tetrandrine may have a potential use as a therapeutic agent for fibrotic lung diseases, its effects on various pulmonary cells and tissues should be studied. Alveolar type II cells are located in the alveolar regions of the lungs and are important because they are responsible for the synthesis and secretion of pulmonary surfactant (Dobbs et al., 1982; King, 1984), regeneration of the alveolar epithelium after lung injury (Kauffman et al., 1974), and metabolism of foreign compounds (Bend et al., 1985). Furthermore, in silicosis, for which TT has been suggested as a treatment, there are increased amounts of pulmonary surfactant produced (Dethloff et al., 1986a,b) as a result of increased rates of surfactant synthesis by type II cells (Dethloff et a/., 1989; Miller et al., 1988). Because type II cells play a critical role in maintaining normal lung function and because type II cells are affected in silicosis, for which 'TT has been used as a treatment, we studied the effects of tetrandrine on energy metabolism in these cells in vitro. Energy metabolism was chosen because it is a basic cellular function which is neces-sary for other cellular processes to occur. Since type II cells depend on mitochondrial metabolism for energy production (Fisher et al., 1980), we examined the effects of tetrandrine on cellular and mitochondrial ATP production and oxygen consumption. Additional experiments were performed in an effort to determine if intracellular calcium levels may be involved in the TT-induced effects. A preliminary report of those results has appeared previously (Ma et al., 1991)."

Nov 1, 1995

By W. Petruk

Mineralogical studies and concentration tests were conducted on samples from an oolitic iron deposit from the Peace River district in Alberta to determine what concentrate grades and metal recoveries could be obtained. The samples assayed 32 to 37 wt. % Fe, and consisted of goethite, nontronite, ferruginous opal, siderite , quartz, amorphous phosphate and illite . Flotation with fatty acids yielded the best over-all results. A flotation concentrate from a composite sample of the iron horizon assayed, by weight, 43.0% Fe, 12.3% SiO2 , 1.9% CaD, 0.9% MgO, 4.5% Al2O3 and 2.0% P2O5 and lost 17.2% on ignition, for an iron recovery of 48.8% and a silica rejection of 80%. When heated to drive off the water, the concentrate assayed 52 w t. % Fe and 14. 8% w t. % SiO2

Jan 1, 1977

Corrosion affects the performance of rock support and reinforcement at various underground mines, including the George Fisher Mine, where recent studies showed that this risk to mining operations is generally not well understood. Corrosion reduces the capacity and life expectancy of ground support and generally is undetected unless the traditional destructive pull out test is employed to detect defect bolts. Where it is still acknowledged that the pull out test has still an important role to play in determining critical bond lengths for static and quasi static ground support designs, it does not provide an underground operation with any reassurance regarding its bolt&apos;s integrity, which has been compromised by in situ aggressive conditions. Non-destructive rock reinforcement calibration testing on single and twin strand cable bolts, rebar bolts and friction bolts at the George Fisher Mine enabled the testing team to detect bolts with compromised integrity in one area of the mine. The non-destructive rock reinforcement integrity testing conducted uses a complex &apos;Stress Wave Analysis&apos; package based on the processing of clear seismic signals imparted into the rock reinforcement element that is being tested. The seismic signals are processed by &apos;Fourier Transform&apos; into various criteria which can be used to produce models of the element such as mechanical admittance, frequency spectra and velocity which are all being used in the final modelling of the rock reinforcement element under analysis. This paper highlights the enormous potential to effectively manage the geotechnical risk that corrosion presents for an underground mining operation.

Nov 25, 2010

By Jon C. Volkwein

The Bureau of Mines and many member companies of the Industrial Sand Association have been working in several areas to reduce personal exposure to respirable dust. Areas investigated include ventilation, modification of hardware, moisture addition to the product, and improved housekeeping practices. Ventilation systems have been devised and shown to contain 100 pct of a tracer gas released within the hood. An industrial clean air island has been developed and shown to reduce dust levels 90 pct at the opera- tor&apos;s position, Modification of hardware on a bag filling machine has been demonstrated to reduce dust 83 pct at the machine operator&apos;s lapel. This particular development has been termed a significant advancement in the state-of-the-art of bag filling by industry representatives. Addition of moisture to dried product materials has been tested with results showing dust reductions of 90 pct are possible!, Control of the moisture addition method still needs refinement and costs may be prohibitive. Dust sampling results clearly show the benefits of housekeeping practices such as building cleaning and vacuum sweeping. Rotation of work schedules is also effective for reducing personal exposure.

Jan 1, 1985

By R. D. Leitch

[The accepted theory of acid formation in coal mines with the subsequent appearance of the acid in coal-mine drainage, is oxidation of iron pyrite and subsequent solution and hydrolysis of the iron sulphate formed. It has also been found that 5 gobbed sections and worked-out areas, where there is usually an abundance of iron pyrite-bearing, materials in contact with air, are the sections that make the most important contribution to the quantity of acid drainage. It would thus seem obvious that if oxygen can be kept out of contact with tae acid-forming materials in tie- sections mentioned the amount of acid in coal-mine drainage could be reduced markedly and corrosion problems with mine pumping equipment and general stream pollution mitigated thereby. Although the efficiency of the suggested remedy as been borne out by laboratory experiments6, it has appeared desirable to substantiate the laboratory work by field observations in so far as pertinent data are available. It has been difficult to learn of mines or sections of mines about to be sealed, whereby an actual comparison of the drainage before and after sealing can be made. In view of that difficulty it has been necessary to devote attention to a comparison of the character of the water from areas already sealed with that from open but otherwise comparable sections of the sane mine. Previous cork has shown that the acidity of drainage in different parts of the same mine may vary, but if it can be shown also that the water from sealed areas is with but fen exceptions less acid than the otherwise similar open sections of tae same mine, the laboratory finding will be supported in a practical gray. This report presents some of the evidence that has been obtained.]

Jan 1, 1930

By J. Forster, C. A. Pickles, Mackowiak. K.

The future development of nickel laterite deposits is crucial with regards to satisfying impending nickel demands. The commercial implementation of new hydro/pyrometallurgical processes in recent years has led to significant improvements in the extraction of nickel from the laterite ores. One potential alternative pyrometallurgical processing route would be to selectively reduce the nickel and produce a concentrate with nickel contents similar to those attainable in the conventional flotation of sulphide ores. However, even bench scale studies have not yet been able to produce a high grade (>15% nickel) concentrate from a low grade laterite ore. The present research involved the microwave vacuum reduction roasting of a nickel laterite ore to yield a high grade concentrate, rich in nickel. Firstly, the effects of temperature and pressure on the nickel grade and recovery were investigated using a thermodynamic model. Secondly, briquettes containing a mixture of charcoal and a low grade silicate nickel laterite ore were reacted in a microwave vacuum system. The experimental variables studied were the input microwave energy, pressure and absorbed microwave power. Thirdly, the ferronickel in the reacted briquette was concentrated by magnetic separation and nickel grades of up to 21% could be achieved.

Jan 1, 2015

By D. E. Walsh

Over a period of seven years (1989-1996) the Mineral Industry Research Laboratory (MIRL) University of Alaska Fairbanks, has investigated the effects of temperature, residence time, and particle size on the degree of low-rank coal (LRC) upgrading for a non-evaporative, hydrothermal drying process, also known as hot water drying (HWD). Three Alaskan LRCs were used in this study: Usibelli coal (Seam No.4) from the Nenana Coal Field, Little Tonzona coal from near McGrath, and Beluga coal from the Beluga-Yentna field on the west side of Cook Inlet. Replicated, factorial tests were conducted. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10-20 minutes of residence time. Thereafter, the upgrading process slows down and over 100 minutes of additional residence time are required to produce similar percentage increases in coal properties to those achieved in the first 10-20 minutes. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, equilibrium moisture levels and Hardgrove grindabilities all appear to change linearly with temperature within the 275" C to 325" C range.

Jan 1, 1997