摘要:

The potential usefulness of liberation estimates is discussed and the issues arising from the presence of inherent ash in coal components are considered. The concepts of native ash and native coal and the appropriate corrections to ash assays are introduced prior to presenting a technique for estimating the degree of liberation of both components from the results of washability analyses. If the washability data relates to a separation, the liberation in the products can also be estimated. For generality, the analysis is based on imperfect separations in die first instance and it therefore incorporates a selectivity correction, but this feature suitably ceases to be effective when perfect separations are achieved.

ISSN:0734-9343    

DOI:10.1080/07349349408905285

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The film flotation method has been used to investigate the effect of polar and apolar substances on variations in the surface energy of coals with various degrees of coalification. The polar and apolar substances which have been utilized are commonly used as flotation reagents. With regard to the heterogeneous structure of the coal surface, the results are presented in the form of distribution curves of particle population as a function of their surface energy, while the magnitude of variations of this energy under the influence of the tested reagents is expressed quantitatively by the mean critical surface energy γcand standard deviation from γc, σγc. Testing of the surface energy was conducted on coal surfaces pre-wetted with reagents outside of the flotation environment.

ISSN:0734-9343    

DOI:10.1080/07349349408905286

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Ozone conditioning can be used for the selective flotation of macroscopic fossil resin (resinite) from coal by treatment of the resin/coal suspension for an appropriate period of time prior to flotation. In this way, a significant improvement in resin separation efficiency can be achieved, but the chemistry of ozone reactions and its influence on particle behavior have not been reported. The improvement in the selective fossil resin flotation by ozone conditioning has been found to be due to (1) the improved depression of fine coal particles, which is evidenced from contact angle measurements, chemical analysis, and FTCR spectroscopic examination; and (2) the improved dispersion of the resin/coal suspension in which the coagulation between resin and coal particles in suspension was significantly reduced by ozonation as evidenced by optical microscopic observation.

ISSN:0734-9343    

DOI:10.1080/07349349408905287

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effects of agglomerant/coal weight ratio (ACR), grinding time, slurry pH, and agglomeration time on the performances of a selective agglomeration process using n-heptane as agglomerant were investigated for Upper Freeport and Pittsburgh #8 coals. The experimental conditions were selected following a statistical central composite design. Statistical regression models including inverse terms were developed to predict the process performances using the various operating variables. The response surfaces constructed with these models showed that the Btu recovery for the two coals was generally poor when the ACR was less than 0·2. It was also shown that high slurry pH improved both the ash and inorganic sulfur rejections for the two coals. For Pittsburgh #8 coal, the improvement in the inorganic sulfur rejection at high slurry pH was more pronounced when finer particle size and/or longer agglomeration time were used.

ISSN:0734-9343    

DOI:10.1080/07349349408905288

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Modelling of a 76 mm diameter dense medium cyclone treating coal in the size range - 2·0 + 0·5 mm have been done on the basis of extensive experimental data generated. The behaviour of independent sizes such as 2·0+ 1·4,-1·4+1·18,- 1·18 + 1·0,- 1·0 + 0·6,-0·6+0·5 mm fractions within the size range of-2·0+ 0·5 mm were separately analysed. Mathematical relationships for the throughput of slurry, water distribution to the overflow and underflow have been developed. Three methods have been devised for the prediction of yield and ash content of the clean coal under different combinations of design parameters such as vortex finder and spigot diameter and the operating condition such as relative density of the magnetite medium. Generalised distribution curves of independent size fractions for the separation of coal using the distribution curves of coal of different size fractions have been mathematically represented. It was found that classification size of magnetite medium solids has effect on the relative density of separation of coal.

ISSN:0734-9343    

DOI:10.1080/07349349408905289

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The paper describes the presently used methods of cake removal in disk vacuum filters, and points out some of their drawbacks. A new, unique method elaborated by the author is introduced, and its effectiveness is compared with that of other methods.

ISSN:0734-9343    

DOI:10.1080/07349349408905290

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor