摘要:

Coal fines were suspended in water or in salt solutions for agglomeration with either heptane or paraffin oil. Coal recovery with a limited amount of oil was found to increase markedly as the salt concentration was raised. The increase in recovery appeared due to compression of the electrical double layer surrounding individual coal particles and oil droplets. The recovery was observed to depend on the pH of the suspension with the greatest recovery occurring at the isoelectric point. When a mixture of hydrophobic coal particles and kaolin particles was suspended in 1.5 M sodium chloride and agglomerated with paraffin oil at a level of 0.065 goil/gcoal, 95% of the coal was recovered and over 90% of the kaolin was rejected. This recovery was 265% greater than the recovery achieved by suspending the mixture in water and agglomerating it with the same amount of oil. These results show that the use of salt solutions in the oil agglomeration process can result in reduced oil consumption

ISSN:0734-9343    

DOI:10.1080/07349348808945562

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Contact time during bubble/particle collision is calculated by taking into consideration the effect of surface tension, buoyant force, gravitational force, and particle motion during collision. From this analysis for the estimation of contact times and from induction lime measurements, the flotabilities of different coals have been predicted. A good agreement between the predicted and experimentally measured Hallimond-tube flotation response was found

ISSN:0734-9343    

DOI:10.1080/07349348808945563

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The rheological behaviour of operating and consequently contaminated magnetite suspensions, such as those used in the dynamic dense media separation of coal is investigated. The apparatus and the procedures used for rheological characterization and viscosity measurement are described. Wide ranges of density and suspension contamination by coal fines are explored. A mathematical framework is presented, which allows the prediction, of the relative viscosity as a function of solids volume concentration, disperse phase composition and shear rate. The adjustable parameters of the suggested model are calculated on the basis of the experimental viscosity data collected on the tested magnetite dense media. The reliability, general applicability and usefulness of the proposed model are pointed out

ISSN:0734-9343    

DOI:10.1080/07349348808945564

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The partition function has been determined for fine coal in a dense-medium cyclone. The partition curve is characterised by four parameters; the cut point, the separation efficiency, the short circuit to underflow and the short circuit to overflow. Each of these parameters is a strong function of particle size for fine coal. The effect of slimes in the feed is shown to have only a small effect on the measured partition curves

ISSN:0734-9343    

DOI:10.1080/07349348808945565

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The development of mathematical models is essential for optimizing coal comminution processes such as crushing, grinding and pulverising operations in various stages of coal preparation. This requires a simple but accurate laboratory technique to determine the comminution characteristics of coal. To achieve this objective, a single particle breakage technique has been developed. A computer monitored twin pendulum apparatus was used to measure the energy available for the breakage of a particle, the comminution energy.

ISSN:0734-9343    

DOI:10.1080/07349348808945566

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The paper deals with the fundamentals of sizing coals on hydraulic screens with stationary screening surfaces of various configurations. Empirical equations for selecting optimum separation conditions and for predicting performance of stationary hydraulic screens with flat separation surfaces are presented. Various stationary hydraulic screen designs are described and their specifications given. The fact that stationary hydraulic screens are high specific capacity units having neither moving or rotating parts nor electric drive and low water consumption, has led to their widespread application in coal preparation plants in the USSR

ISSN:0734-9343    

DOI:10.1080/07349348808945567

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Water recirculation and the addition of lime as a pH modifier may lead to a build up of dissolved calcium salts in coal preparation plant waters. Under certain conditions precipitates may form on product filters or dewatering screens, with the possibility of serious operating difficulties, even to the extent of total plant shutdowns in extreme cases.

ISSN:0734-9343    

DOI:10.1080/07349348808945568

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349348808945569

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor