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Development of a Gas-Promoted Oil Agglomeration Process

Description: Further agglomeration tests were conducted in a series of tests designed to determine the effects of various parameters on the size and structure of the agglomerates formed, the rate of agglomeration, coal recovery, and ash rejection. For this series of tests, finely ground Pittsburgh No. 8 coal has been agglomerated with i-octane in a closed mixing system with a controlled amount of air present to promote particle agglomeration. The present results provide further evidence of the role played by air. As the concentration of air in the system was increased from 4.5 to 18 v/w% based on the weight of coal, coal recovery and ash rejection both increased. The results also show that coal recovery and ash rejection were improved by increasing agitator speed. On the other hand, coal recovery was not affected by a change in solids concentration from 20 to 30 w/w%.
Date: October 30, 1998
Creator: Shen, M. & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

POC-Scale Testing of Oil Agglomeration Techniques and Equipment for Fine Coal Processing

Description: The objective of this project is to develop and demonstrate a Proof-of-Concept (POC) scale oil agglomeration technology capable of increasing the recovery and improving the quality of fine coal strearrts. Two distinct agglomeration devices will be tested, namely, a conventional high shear mixer and a jet processor. To meet the overall objective an eleven task work plan has been designed. The work ranges from batch and continuous bench-scale testing through the design, commissioning and field testing of POC-scale agglomeration equipment.
Date: November 12, 1998
Partner: UNT Libraries Government Documents Department

Development of a Gas-Promoted Oil Agglomeration Process

Description: Two series of agglomeration tests were conducted as part of an effort to find a suitable basis for size scale-up of the mixing system used for a gas-promoted oil agglomeration process. In the first series of tests the agitator impeller diameter and speed were varied among runs so as to vary impeller tip speed and agitator power independently while keeping other conditions constant. In the second series of tests the mixing tank size and agitator speed were varied while the ratio of tank diameter to impeller diameter were held constant. All tests were conducted with finely ground Pittsburgh No. 8 coal and with i-octane as the agglomerant. The results of these tests showed that the minimum time te required to produce spherical agglomerates was predominantly a function of the agitator power input per unit volume. In addition, the size of the agglomerates produced in a given time was also strongly dependent on power input. At lower power input levels, the mean size rose as power input increased until a point was reached where agglomerate breakage became important and the mean size decreased. The results also showed that the ash content of the agglomerates produced in a given time tended to decrease with increasing power input. On the other hand, the recovery of clean coal on a dry, ash-free basis was not greatly affected by power input.
Date: October 30, 1998
Creator: Shen, M.; Abbott, R. & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

Development of a Gas-Promoted Oil Agglomeration Process

Description: The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal was carried out with scale model mixing systems in which aqueous suspensions of ultrafine coal particles were treated with a liquid hydrocarbon and a small amount of air. The resulting agglomerates were recovered by screening. During a batch agglomeration test the progress of agglomeration was monitored by observing changes in agitator torque in the case of concentrated suspensions or by observing changes in turbidity in the case of dilute suspensions. Dilute suspensions were employed for investigating the kinetics of agglomeration, whereas concentrated suspensions were used for determining parameters that characterize the process of agglomeration. A key parameter turned out to be the minimum time te required to produce compact spherical agglomerates. Other important parameters included the projected area mean particle diameter of the agglomerates recovered at the end of a test as well as the ash content and yield of agglomerates. Batch agglomeration tests were conducted with geometrically similar mixing tanks which ranged in volume from 0.346 to 11.07 liters. Each tank was enclosed to control the amount of air present. A variable speed agitator fitted with a six blade turbine impeller was used for agitation. Tests were conducted with moderately hydrophobic Pittsburgh No. 8 coal and with more hydrophobic Upper Freeport coal using either n-heptane, i-octane, or hexadecane as an agglomerant.
Date: November 1997
Creator: Nelson, C.; Zhang, F.; Drzymala, J.; Shen, M.; Abbott, R. & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

COAL CLEANING BY GAS AGGLOMERATION

Description: The agglomeration of ultrafine-size coal particles in an aqueous suspension by means of microscopic gas bubbles was demonstrated in numerous experiments with a scale model mixing system. Coal samples from both the Pittsburgh No. 8 Seam and the Upper Freeport Seam were used for these experiments. A small amount of i-octane was added to facilitate the process. Microscopic gas bubbles were generated by saturating the water used for suspending coal particles with gas under pressure and then reducing the pressure. Microagglomerates were produced which appeared to consist of gas bubbles encapsulated in coal particles. Since dilute particle suspensions were employed, it was possible to monitor the progress of agglomeration by observing changes in turbidity. By such means it became apparent that the rate of agglomeration depends on the concentration of microscopic gas bubbles and to a lesser extent on the concentration of i-octane. Similar results were obtained with both Pittsburgh No. 8 coal and Upper Freeport coal.
Date: September 30, 1998
Creator: SHEN, MEIYU; ABBOTT, ROYCE & WHEELOCK, T.D.
Partner: UNT Libraries Government Documents Department

Coal Cleaning by Gas Agglomeration

Description: The gas agglomeration method of coal cleaning was demonstrated with laboratory scale mixing equipment which made it possible to generate microscopic gas bubbles in aqueous suspensions of coal particles. A small amount of i-octane was introduced to enhance the hydrophobicity of the coal. Between 1.0 and 2.5 v/w% i-octane was sufficient based on coal weight. Coal agglomerates or aggregates were produced which were bound together by small gas bubbles.
Date: March 1, 1998
Creator: Shen, Meiyu; Abbott, Royce & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

Overlapping Schwarz for Nonlinear Problems. An Element Agglomeration Nonlinear Additive Schwarz Preconditioned Newton Method for Unstructured Finite Element Problems

Description: This paper extends previous results on nonlinear Schwarz preconditioning ([4]) to unstructured finite element elliptic problems exploiting now nonlocal (but small) subspaces. The non-local finite element subspaces are associated with subdomains obtained from a non-overlapping element partitioning of the original set of elements and are coarse outside the prescribed element subdomain. The coarsening is based on a modification of the agglomeration based AMGe method proposed in [8]. Then, the algebraic construction from [9] of the corresponding non-linear finite element subproblems is applied to generate the subspace based nonlinear preconditioner. The overall nonlinearly preconditioned problem is solved by an inexact Newton method. Numerical illustration is also provided.
Date: February 10, 2005
Creator: Cai, X C; Marcinkowski, L & Vassilevski, P S
Partner: UNT Libraries Government Documents Department

Novel Binders and Methods for Agglomeration of Ore

Description: Heap leaching is one of the methods being used to recover metal from low grade ore deposits. The main problem faced during heap leaching is the migration of fine grained particles through the heap, forming impermeable beds which result in poor solution flow. The poor solution flow leads to less contact between the leach solution and the ore, resulting in low recovery rates. Agglomeration of ore into coarse, porous masses prevents fine particles from migrating and clogging the spaces and channels between the larger ore particles. Currently, there is one facility in the United States which uses agglomeration. This operation agglomerates their ore using leach solution (raffinate), but is still experiencing undesirable metal recovery from the heaps due to agglomerate breakdown. The use of a binder, in addition to the leach solution, during agglomeration would help to produce stronger agglomerates that did not break down during processing. However, there are no known binders that will work satisfactorily in the acidic environment of a heap, at a reasonable cost. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. Increasing copper recovery in heap leaching by the use of binders and agglomeration would result in a significant decrease in the amount of energy consumed. Assuming that 70% of all the leaching heaps would convert to using agglomeration technology, as much as 1.64*10{sup 12} BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, which is equivalent to saving approximately 18% of the energy currently being used in leaching heaps. For every week a leach cycle was decreased, a savings of as much as 1.23*10{sup 11} BTU per week would result. This project has identified several acid-resistant binders and agglomeration procedures. ...
Date: September 30, 2006
Creator: Kawatra, S. K.; Eisele, T. C.; Lewandowski, K. A. & Gurtler, J. A.
Partner: UNT Libraries Government Documents Department

On Some Versions of the Element Agglomeration AMGe Method

Description: The present paper deals with element-based AMG methods that target linear systems of equations coming from finite element discretizations of elliptic PDEs. The individual element information (element matrices and element topology) is the main input to construct the AMG hierarchy. We study a number of variants of the spectral agglomerate element based AMG method. The core of the algorithms relies on element agglomeration utilizing the element topology (built recursively from fine to coarse levels). The actual selection of the coarse degrees of freedom (dofs) is based on solving large number of local eigenvalue problems. Additionally, we investigate strategies for adaptive AMG as well as multigrid cycles that are more expensive than the V-cycle utilizing simple interpolation matrices and nested conjugate gradient (CG) based recursive calls between the levels. The presented algorithms are illustrated with an extensive set of experiments based on a matlab implementation of the methods.
Date: August 9, 2007
Creator: Lashuk, I & Vassilevski, P
Partner: UNT Libraries Government Documents Department

Multiple Vector Preserving Interpolation Mappings in Algebraic Multigrid

Description: We propose algorithms for the construction of AMG (algebraic multigrid) interpolation mappings such that the resulting coarse space to span (locally and globally) any number of a priori given set of vectors. Specific constructions in the case of element agglomeration AMG methods are given. Some numerical illustration is also provided.
Date: November 3, 2004
Creator: Vassilevski, P S & Zikatanov, L T
Partner: UNT Libraries Government Documents Department

Aerosol cluster impact and break-up : model and implementation.

Description: In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.
Date: October 1, 2010
Creator: Lechman, Jeremy B.
Partner: UNT Libraries Government Documents Department

Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

Description: In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.
Date: August 9, 2006
Creator: Enlow, Drew Lenzen
Partner: UNT Libraries Government Documents Department

Pourability Enhancement of PETN Explosive Powders

Description: Manufacture of precision detonators requires the pelletizing of very fine, organic, crystalline explosive powders. Production of pellets in automatic machines within critical dimensional and weight tolerances requires that the powders pour uniformly into die cavities. The pellets must be able to be initiated with low energy and have a predictable energy output. Modifications to needle-like crystalline PETN explosive powders to make them pourable were introduced by the application of about 80 A thick polymeric coatings to the individual crystals, followed by a controlled agglomeration into a spherical prill. Microencapsulation techniques provided the key to achieving the result using less than 0.5 wt. % coating (an order of magnitude less coating than in usual PBX systems). These coatings did not appreciably alter the energy required to initiate and significantly increased the strength of the pellets. A key point demonstrated, which may be translated to other applications, was that powders that exhibit performance based on physical characteristics could have their handling and strength properties tailored with little change in their primary function.
Date: January 1, 1987
Creator: Vannet, M. D. & Ball, G. L.
Partner: UNT Libraries Government Documents Department

POC-SCALE TESTING OF OIL AGGLOMERATION TECHNIQUES AND EQUIPMENT FOR FINE COAL PROCESSING

Description: This report covers the technical progress achieved from July 01, 1997 to September 30, 1997 on the POC-Scale Testing Agglomeration Techniques and Equipment for Fine Coal Processing project. Experimental procedures and test data for recovery of fine coal from coal fines streams generated at a commercial coal preparation plant are described. Two coal fines streams, namely Sieve Bend Effluent and Cyclone Overflow were investigated. The test results showed that ash was reduced by more than 50% at combustible matter recovery levels exceeding 95%.
Date: January 1, 1998
Partner: UNT Libraries Government Documents Department

Micro-agglomerate flotation for deep cleaning of coal. Quarterly progress report, July 1, 1995--September 30, 1995

Description: The development of practical technologies for the deep cleaning of coal has been seriously hampered by the problems of carrying out efficient coal/mineral separations at the very fine sizes (often finer than 10 mm) needed to achieve adequate liberation of the mineral matter from the coal matrix. It is generally recognized that surface-based separation processes such as froth flotation or selective agglomeration offer considerable potential for such applications but there remain many problems in obtaining the required selectivity with acceptable recovery of combustible matter. In froth flotation, selectivity is substantially reduced at fine sizes due, primarily, to overloading of the froth phase which leads to excessive carryover of water and entrained mineral matter. Oil agglomeration, on the other hand, can provide good selectivity at low levels of oil addition but the agglomerates tend to be too fragile for separation by the screening methods normally used. The addition of larger amounts of oil can yield large, strong agglomerates which are easily separated but the selectivity is reduced and reagent costs can become excessive.
Date: July 1, 1995
Creator: Chander, S. & Hogg, R.
Partner: UNT Libraries Government Documents Department

Development of a gas-promoted oil agglomeration process. Quarterly technical progress report, July 1, 1995--September 30, 1995

Description: The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal advanced in three major research areas. One area of research resulted in the development of a method for measuring the rate of agglomeration of dilute particle suspensions and using the method to relate the rate of agglomeration of coal particles to various key parameters. A second area of research led to the development of a method for monitoring a batch agglomeration process by measuring changes in agitator torque. With this method it was possible to show that the agglomeration of a concentrated coal particle suspension is triggered by the introduction of a small amount of gas. The method was also used in conjunction with optical microscopy to study the mechanism of agglomeration. A third area of research led to the discovery that highly hydrophobic particles in an aqueous suspension can be agglomerated by air alone.
Date: December 31, 1995
Creator: Wheelock, T.D.
Partner: UNT Libraries Government Documents Department

Engineering development of advanced physical fine coal cleaning for premium fuel applications. Quarterly technical progress report 15, April--June 1996

Description: Goal is engineering development of two advanced physical fine coal cleaning processes, column flotation and selective agglomeration, for premium fuel applications. Scope includes laboratory research and bench-scale testing on 6 coals to optimize these processes, followed by design/construction/operation of a 2-t/hr PDU. During this quarter, parametric testing of the 30-in. Microcel{trademark} flotation column at the Lady Dunn plant was completed and clean coal samples submitted for briquetting. A study of a novel hydrophobic dewatering process continued at Virginia Tech. Benefits of slurry PSD (particle size distribution) modification and pH adjustment were evaluated for the Taggart and Hiawatha coals; they were found to be small. Agglomeration bench-scale test results were positive, meeting product ash specifications. PDU Flotation Module operations continued; work was performed with Taggart coal to determine scaleup similitude between the 12-in. and 6-ft Microcel{trademark} columns. Construction of the PDU selective agglomeration module continued.
Date: July 25, 1996
Creator: Moro, N.; Shields, G.L.; Smit, F.J. & Jha, M.C.
Partner: UNT Libraries Government Documents Department

Engineering Development of Advanced Physical Fine Coal Cleaning for Premium Fuel Applications: Task 9 - Selective agglomeration Module Testing and Evaluation.

Description: The primary goal of this project was the engineering development of two advanced physical fine coal cleaning processes, column flotation and selective agglomeration, for premium fuel applications. The project scope included laboratory research and bench-scale testing of both processes on six coals to optimize the processes, followed by the design, construction, and operation of a 2 t/hr process development unit (PDU). The project began in October, 1992, and is scheduled for completion by September 1997. This report summarizes the findings of all the selective agglomeration (SA) test work performed with emphasis on the results of the PDU SA Module testing. Two light hydrocarbons, heptane and pentane, were tested as agglomerants in the laboratory research program which investigated two reactor design concepts: a conventional two-stage agglomeration circuit and a unitized reactor that combined the high- and low-shear operations in one vessel. The results were used to design and build a 25 lb/hr bench-scale unit with two-stage agglomeration. The unit also included a steam stripping and condensation circuit for recovery and recycle of heptane. It was tested on six coals to determine the optimum grind and other process conditions that resulted in the recovery of about 99% of the energy while producing low ash (1-2 lb/MBtu) products. The fineness of the grind was the most important variable with the D80 (80% passing size) varying in the 12 to 68 micron range. All the clean coals could be formulated into coal-water-slurry-fuels with acceptable properties. The bench-scale results were used for the conceptual and detailed design of the PDU SA Module which was integrated with the existing grinding and dewatering circuits. The PDU was operated for about 9 months. During the first three months, the shakedown testing was performed to fine tune the operation and control of various equipment. This was followed by parametric ...
Date: September 29, 1997
Creator: Moro, N. & Jha, M. C.
Partner: UNT Libraries Government Documents Department

POC-SCALE TESTING OF OIL AGGLOMERATION TECHNIQUES AND EQUIPMENT FOR FINE COAL PROCESSING

Description: This report covers the technical progress achieved from October 1, 1997 to December 31, 1997 on the POC-Scale Testing of Oil Agglomeration Techniques and Equipment for Fine Coal Processing project. Experimental test procedures and the results related to the processing of coal fines originating from process streams generated at the Shoal Creek Mine preparation plant, owned and operated by the Drummond Company Inc. of Alabama, are described. Two samples of coal fines, namely Cyclone Overflow and Pond Fines were investigated. The batch test results showed that by applying the Aglofloat technology a significant ash removal might be achieved at a very high combustible matter recovery: · for the Cyclone Overflow sample the ash reduction was in the range 50 to 55% at combustible matter recovery about 98% · for the Pond Fines sample the ash reduction was up to 48% at combustible matter recovery up to 85%. Additional tests were carried out with the Alberta origin Luscar Mine coal, which will be used for the parametric studies of agglomeration equipment at the 250 kg/h pilot plant. The Luscar coal is very similar to the Mary Lee Coal Group (processed at Shoal Creek Mine preparation plant) in terms of rank and chemical composition.
Date: January 1, 1998
Partner: UNT Libraries Government Documents Department

COAL CLEANING BY GAS AGGLOMERATION

Description: The technical feasibility of a gas agglomeration method for cleaning coal was demonstrated by means of bench-scale tests conducted with a mixing system which enabled the treatment of ultra-fine coal particles with a colloidal suspension of microscopic gas bubbles in water. A suitable suspension of microbubbles was prepared by first saturating water with air or carbon dioxide under pressure then reducing the pressure to release the dissolved gas. The formation of microbubbles was facilitated by agitation and a small amount of i-octane. When the suspension of microbubbles and coal particles was mixed, agglomeration was rapid and small spherical agglomerates were produced. Since the agglomerates floated, they were separated from the nonfloating tailings in a settling chamber. By employing this process in numerous agglomeration tests of moderately hydrophobic coals with 26 wt.% ash, it was shown that the ash content would be reduced to 6--7 wt.% while achieving a coal recovery of 75 to 85% on a dry, ash-free basis. This was accomplished by employing a solids concentration of 3 to 5 w/w%, an air saturation pressure of 136 to 205 kPa (5 to 15 psig), and an i-octane concentration of 1.0 v/w% based on the weight of coal.
Date: March 1, 1999
Creator: Wheelock, T.D.
Partner: UNT Libraries Government Documents Department

ADVANCED DIRECT LIQUEFACTION CONCEPTS FOR PETC GENERIC UNITS - PHASE II

Description: The results of Laboratory and Bench-Scale experiments and supporting technical and economic assessments conducted under DOE Contract No. DE-AC22-91PC91040 are reported for the period January 1, 1999 to March 31, 2000. This contract is with the University of kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Research, CONSOL, Inc., LDP Associates, and Hydrocarbon Technologies, Inc. This work involves the introduction into the basic two-stage liquefaction process several novel concepts, which include dispersed lower-cost catalysts, coal cleaning by oil agglomeration, and distillate hydrotreating and dewaxing. This project has been modified to include an investigation into the production of value added materials from coal using low-severity liquefaction based technologies.
Date: October 1, 2000
Partner: UNT Libraries Government Documents Department

OPTIMIZING PERFORMANCE OF THE HESKETT STATION

Description: The overall conclusion from this work is that a switch from river sand bed material to limestone at the R.M. Heskett Station would provide substantial benefits to MDU. A switch to limestone would increase the fuel flexibility of the unit, allowing fuels higher in both sodium and sulfur to be burned. The limestone bed can tolerate a much higher buildup of sodium in the bed without agglomeration, allowing either the bed turnover rate to be reduced to half the current sand feed rate for a fuel with equivalent sodium or allow a higher sodium fuel to be burned with limestone feed rates equivalent to the current sand feed rate. Both stack and ambient SO{sub 2} emissions can be controlled. A small improvement in boiler efficiency should be achievable by operating at lower excess oxygen levels at low load. This reduction in oxygen will also lower NO{sub x} emissions, providing a margin of safety for meeting emission standards. No detrimental effects of using limestone at the Heskett Station were uncovered as a result of the test burn. Some specific conclusions from this work include the following: The bed material feed rate can be reduced from the current rate of 5.4% of the coal feed rate (57.4 tons of sand/day) to 2.5% of the coal feed rate (27 tons of limestone/day). This will result in an annual savings of approximately $200,000. (1) SO{sub 2} emissions at the recommended feed rate would be approximately 250 ppm (0.82 lb/MMBtu) using a similar lignite. Based on the cost of the limestones, SO{sub 2} allowances could be generated at a cost of $60/ton SO{sub 2} , leaving a large profit margin for the sale of allowances. The addition of limestone at the same rate currently used for sand feed could generate $455,000 net income if allowances ...
Date: March 1, 1999
Creator: Mann, Michael D. & Henderson, Ann K.
Partner: UNT Libraries Government Documents Department

Continuous air Agglomeration Method for high Carbon fly ash Beneficiation

Description: The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carbon-free mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.
Date: September 29, 1998
Creator: Gray, McMahan L.; Champagne, Kenneth J. & Finseth, Dennis H.
Partner: UNT Libraries Government Documents Department