摘要:

Many developments have occurred over the last ten years in coal preparation. Especially noteworthy are the growing demands for more efficient processing methods, better and more consistent coal quality and the need for greater environmental awareness. This review focuses on coal preparation technology developments, advances, and trends which were recently put into practice as well as those which are still under investigation in the pilot plant or laboratory.

ISSN:0734-9343    

DOI:10.1080/07349349208905212

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The jig in its variety of forms applied in coal preparation has been a major unit in coal washeries for one hundred years; yet the principles of jigging are still less well understood than those governing many other coal preparation unit operations. Jig control has also been viewed as an art rather than a science until recently. This review considers some of the history of jigs and the theories that have been advanced to explain their operation. Special emphasis is placed on discussion of the means of control of jigs, starting from the traditional means and working towards the novel methods that have been proposed recently. It is clear that our understanding of jigs and the means by which they will be controlled in the future will benefit from our rapidly increasing engineering computational power and will make much fuller use of microprocessor control and modern instrumentation.

ISSN:0734-9343    

DOI:10.1080/07349349208905213

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fine-size particles of coal and pyrite were suspended in aqueous solutions of various salts and agglomerated with heptane. The agglomerates were recovered by screening. For highly oleophilic Upper Freeport coal, the addition of a salt to the suspension improved the recovery, whereas for weakly oleophilic Illinois No. 6 coal or pyrite the addition of salt reduced the recovery. The improvement in recovery of Upper Freeport coal was independent of the type of salt, provided the ionic strength was held constant and complexation was avoided. On the other hand, the reduction in pyrite recovery was dependent on the type of salt with the effect increasing in the following order: NaCl < CaCl: < MgCl2. The agglomeration of both Upper Freeport coal and Illinois No. 6 coal was suppressed by adsorption of the metal hydroxy complexes of certain multivalent cations within specific and relatively narrow ranges of pH.

ISSN:0734-9343    

DOI:10.1080/07349349208905214

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The problem of balancing raw washability data is investigated. A technique utilizing the maximum entropy approach for balancing raw washability data is developed such that the generated data satisfy both mass and ash balance conditions. The cases of equal and unequal float and sink terminal conditions are identified and the corresponding solutions are derived. The effectiveness of the proposed technique is demonstrated by using actual data.

ISSN:0734-9343    

DOI:10.1080/07349349208905215

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An extensive plant-orientated testwork campaign was undertaken to quantify and determine the causes of significant dense medium cyclone operating inefficiencies. Comprehensive plant trials, with 20–30 people sampling up to 100 process (medium and coal) streams simultaneously for eight hour shifts permitted both magnetite media and coal processing characteristics to be simultaneously quantified. Dense medium classification and coal partition curves were principally used to show that the root cause of inefficient cyclone performance was related to incorrect magnetite particle size in the cyclone circuits. When magnetite with the correct specifications was used in the plant, the reasons for coarse magnetite in the cyclone circuits was found not to result from selective fine magnetite losses in the small coal circuits, but from a fundamental design flaw in the magnetite distribution system. The flawed system was shown to prevent correct specification magnetite entering the cyclone circuits, thereby starving these coal circuits of ultrafine magnetite particles. Redesign of the distribution system, which maintained existing sumps and pumps but revised flows and functions, was demonstrated to significantly increase dense medium cyclone separating efficiencies. Further plant testwork results are presented which show that plant feed rate plays a critical role in dense medium cyclone separations, with both separating density and efficiency being sensitive to raw coal feed rate. To extract maximum efficiency from these units, it is critical to control RD50.

ISSN:0734-9343    

DOI:10.1080/07349349208905216

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349349208905217

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor