摘要:

The preparation of manageable low-ash, low-moisture coal combustion and/or conversion (i.e., liquefaction, gasification) feedstocks is a priority for future energy development Physical cleaning by conventional washability techniques, followed by dilute acid leaching, has produced lignite, subbiluminous, and brown coal products with less than I wt, % ash on a dry basis on a laboratory scale. Agglomeration yields have ranged from 85 to 99wt. %. Ash contents have been less than 2wt. % moisture- and oil-free for a North Dakota lignite. After air-drying the agglomerates overnight, Karl-Fischer moisture analysis indicates the moisture levels are less than 5 wt. % in the agglomerates. After thermal drying of the coal, the moisture levels are less than 0.5wt. %.

ISSN:0734-9343    

DOI:10.1080/07349349208905203

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The influence of interfacial properties in oil agglomeration of coal has been experimentally studied by testing four coals of different rank using a series of agglomerating agents obtained by mixing, in variable proportions, two basic commercial oils having distinct densities. The results show that oil agglomeration is always more efficient on coals of higher rank for which fuel recovery can be increased by using suitable mixtures of basic oils. The improvement in recovery is much more marked in the case of subbituminous coals. The experimental results are discussed and a scientific interpretation is given.

ISSN:0734-9343    

DOI:10.1080/07349349208905204

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A common challenge to coal cleaning technologies is the development of suitable mechanical equipment together with the necessary instrumentation and control devices. This challenge was encountered in the design of a continuous unit for the LICADO (LIquidCArbonDiOxide) process for fine coal cleaning. A microcomputer-based control system was developed for the operation. The computer is equipped with A/D and D/A converter modules which accept input data from pressure transducers, Coriolis type mass flowmeters, a capacitance type liquid-liquid interface position probe, and liquid level switches while transmit control signals to pumps, pneumatic ball valves and regulating valves. Simple strategies were implemented to manage the feed and discharge from the process unit, to control operating variables, and to perform on-line data acquisition.

ISSN:0734-9343    

DOI:10.1080/07349349208905205

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A mathematical model was developed for coal-coal pyrite separation by selective flocculation technology. The model predicted that selectivity is primarily governed by polymer adsorption, although improvements in selectivity may also be obtained by controlling the polymer dosage when the selectivity in polymer adsorption is not very high. Selectivity predicted for coal-coal pyrite-cationic polyacrylamide flocculant was in agreement with the experimental results. Poor selectivity achieved was attributed to hetroflocculation and kaolinite associated with coal and coal pyrite samples.

ISSN:0734-9343    

DOI:10.1080/07349349208905206

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A useful predictive model is developed for the partition function when fine coal is cleaned on a spiral concentrator. The calculation of the partition function for the spiral is complicated because the behaviour of any particle is strongly influenced by its size as well as its density. In addition two distinct regimes of behaviour are identified depending on whether the particle is in suspension in the flowing water or in the sliding bed on the floor of the spiral trough. Although the (density) cut point is a strong function of the position of the splitter at the foot of the spiral, the range of cut points that can be achieved is limited. This is the chief limitation of the spiral as a device for the production of clean coal. Also the density cut-point was found to be a strong function of particle size with a distinct minimum that varied with the splitter position.

ISSN:0734-9343    

DOI:10.1080/07349349208905207

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The production of fine coal in America's mines and coal preparation plants is increasing. A fraction of this coal can be blended with the larger-size clean coal and shipped to the user. However, a convenient means to handle, store, transport, and use the balance must be devised. Coal reconstitution, encompassing briquetting, disk pelleting, extrusion pelletization and roller-and-die pelletization, is a means frequently proposed for this service.

ISSN:0734-9343    

DOI:10.1080/07349349208905208

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The effect of grinding coal in perchloroethylene, use of different sulfur extraction conditions, and separation of coal from other mineral matter were studied using the Midwest Ore Processing Co., Inc. proprietary perchloroethylene coal beneficiation process. Solvent grinding of coal in perchloroethylene reduces generation of fine (− 0.149 mm) particles, increases the mill capacity, and reduces power consumption. Extraction at atmospheric pressure and 120°C removes up to 75% of the organic sulfur for Indiana No. 5 and Illinois No. 6 coals with essentially no change in the pyritic sulfur. Organic sulfur removal can be enhanced for the Indiana coal by heating in warm, moist air. One stage gravity sedimentation at a specific gravity of 1.4 reduces the pyritic sulfur by 80% for the same coals when ground to less than 0.595 mm.

ISSN:0734-9343    

DOI:10.1080/07349349208905209

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Today most coals cleaned by advanced or conventional techniques are processed in an aqueous slurry. To optimize cleaning efficiency and better control cleaning operations, more rapid feedback on the coals' ash and sulfur content (while still in the slurry) is needed. Battelle has recently completed a project to evaluate and develop on-line slurry ash, percent solids, and sulfur analysis instrumentation and identify process control technologies.

ISSN:0734-9343    

DOI:10.1080/07349349208905210

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fine coal cleaning has come a long way in South Africa in the past decade, as evidenced by the installation of 5 Mtpa of spiral plant capacity, the re-appraisal of froth notation technology resulting in major modifications to most operating flotation plants, and vigorous research into column flotation and oil agglomeration. This paper reviews the developments which have been made, and the reasons, both metallurgical and economic, which have given rise to these developments. In particular, the nature of South African coals makes it preferable to treat the fines in separate size fractions, comprising −0.5 +0.1 mm “fines” and −0.1 mm “ultrafines”, using equipment of different separating efficiency, depending on the desired quality of the final product.

ISSN:0734-9343    

DOI:10.1080/07349349208905211

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor