摘要:

This study investigated the effects of temperature, residence time, and particle size on the degree of low-rank coal (LRC) upgrading for a non-evaporative drying process, hot water drying (HWD). Usibelli Coal (Seam No. 4) from the Nenana Coal Field, Alaska was used in this study. Replicated, factorial tests were conducted. The discussion is based on the results of analysis of variance (ANOVA) of the experimental data. Within the tested particle size range, there was no significant effect due to particle size and no interaction effects between the factors were significant. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10 minutes of residence time. Thereafter, the upgrading process slows down and over 100 minutes of additional residence time are required to produce similar percentage increases in coal properties to those achieved in the first 10 minutes. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, and equilibrium moisture level all appear to change linearly with temperature within the 275°C to 325°C range.

ISSN:0734-9343    

DOI:10.1080/07349349308905128

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Hughes' has proposed a method for dealing with the problems of interpolating coal washability data which eliminates many of the difficulties encountered in previously proposed procedures, In particular, the problem of the interpolating function becoming negative was solved, but the computational procedure proposed was not suited to convenient computation. Lyman2 modified the solution to provide a smoother interpolating function, recast the computations in a manner well-suited to fully-automatic operation, and generalised and further extended the method to deal with a more difficult problem relating to interpolation of bulk density, size distribution and density distributions as a function of bed depth in samples taken from a jig bed. These methods were implemented in a major project by the author.

ISSN:0734-9343    

DOI:10.1080/07349349308905129

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A substantial research project on the performance of a 600 tonne per hour Batac jig involved removing large bed samples from four locations across the bed in the first compartment. The bed was sampled as four or more layers of constant thickness. In order to arrive at estimates of the continuous variation of bulk density and concentrations of particle size and density fractions with depth in a bed, a new method of interpolation, the basis of which is developed in the first paper in this series, was applied to the data. While it was not possible to determine trends in stratification with operating conditions of the jig, the work provided insight into bed stratification. A new jig bed stratification index was devised to quantify the state of stratification of the bed. The use of the interpolation method made possible the objective estimation of stratification.

ISSN:0734-9343    

DOI:10.1080/07349349308905130

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The first paper in this series' presented the mathematical basis and computational procedures for problems of interpolation of sizing and density data commonly encountered in coal preparation problems. Robust methods having the desirable property that the interpolations reduce exactly to the original data were developed. This work discusses the application of the method to two-dimensional interpolation of size-by-size density and ash data. The primary application of the method is in consistently recalculating washability information to some chosen set of size and density intervals, given sets of data defined on a different set of intervals. Such a problem occurs when preparing drill core or bulk sample data for washery calculations. No ‘model’ of coal properties or assumptions regarding the forms of the mass or ash distribution are involved. The method is consistent, objective and computationally robust.coal preparation, Coal, density distribution, interpolation, size distribution, washability.

ISSN:0734-9343    

DOI:10.1080/07349349308905131

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Jigging is one of the most important separation methods used in coal preparation plants. The process is very complicated and is affected by many factors.

ISSN:0734-9343    

DOI:10.1080/07349349308905132

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The results of laboratory-based research into factors which may influence the shear strength of dewatered coal preparation plant tailings when mixed with small quantities of ordinary Portland cement are presented. The effects of cement source and dosage, tailings moisture content, particle size distribution and ash content, together with liquid properties (pH, flocculant type and dosage) are reported. The failure of cemented tailings to regain their shear strength after disturbance through reworking is noted.

ISSN:0734-9343    

DOI:10.1080/07349349308905133

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349349308905134

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor