摘要:

The separation of coal and pyrite particles by selective agglomeration with oil can be troublesome for coals which are weakly hydrophobic or hydrophilic and, therefore, are not strongly agglomerable. The hydrophobicity of lower rank coals and other coals which have become oxidized is generally low. On the other hand, the hydrophobicity of oxidized pyrite can be appreciable. The problem of separating such coals from pyrite was studied by oxidizing a moderately hydrophobic coal with air at 150°C for either 8, 20, or 72 hr to systematically reduce its hydrophobicity. Samples of the raw and treated coal were subsequently mixed with aged mineral pyrite from Peru and agglomerated with heptane. Although a mixture of raw, unoxidized coal and pyrite was largely separated by this method, it proved increasingly difficult to separate the materials as the coal became increasingly oxidized. While raw coal was agglomerated in preference to pyrite, this preference changed as the coal was oxidized. After 20 hr. of oxidation, coal and pyrite were agglomerated almost to the same extent. Finally after 72 hr. of oxidation, more pyrite was agglomerated than coal. This trend was reversed by adding thioglycolic acid (TGA) to suppress the agglomeration of pyrite. Therefore, by conducting agglomeration in the presence of 0.002 M TGA, the separation of coal oxidized for 20 hr from pyrite was nearly as good as the separation of the unoxidized coal and pyrite without TGA.

ISSN:0734-9343    

DOI:10.1080/07349349408905218

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Unlike dense media separation, froth flotation has no widely accepted counterpart to float-sink analysis for characterizing process performance. However, release analysis, developed by C.C. Dell in 1953, could serve as this counterpart by providing a measure of the "state of release" or ultimate separability of a sample by froth flotation. In an attempt to encourage the acceptance of this technique as a standard for characterizing flotation performance, release analysis has been carried out on a variety of U.S. coals including Pittsburgh No. 8, Upper Freeport and Illinois No. 6. Tests conducted as a function of various frother types and frother and collector dosages indicate that the release curve is relatively independent of these parameters. Run-of-mine coals, generally containing large amounts of free mineral matter, produce superior release curves to precleaned samples of the same material, while increased grinding lends to improve the release curve. When compared to centrifugal float-sink analysis, release analysis produces an inferior separation, indicating that float-sink data are not appropriate for characterizing a surface-based process such as froth flotation.

ISSN:0734-9343    

DOI:10.1080/07349349408905219

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The problem of balancing raw direct float-sink or size analysis data is investigated. A technique utilizing the least-squares approach is developed such that the generated data satisfy both mass and ash balance conditions. The effectiveness of the proposed technique is demonstrated by using actual data.

ISSN:0734-9343    

DOI:10.1080/07349349408905220

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The limitation of sulfur dioxide in power plant emissions dictates that sulfur in coal be reduced to the lowest possible level before combustion so as not to aggravate the emission control problem at the stack. For coal fired power plants, the methods in practice to achieve low sulfur coal include mining areas with relatively low sulfur, reducing sulfur in the mined coal through preparation techniques, and blending high and low sulfur coals. A prerequisite to the successful implementation of any of these practices is the knowledge of the spatial distribution and the capability to predict sulfur values in a coal seam. In recent years, geostatistics has increasingly been applied not only for coal reserve quantity estimation but also for quality prediction. This paper presents the results of an investigation to study the variability of coal quality parameters in a longwall panel. Four sides of a yet to be mined longwall panel were extensively sampled at closely spaced intervals. The details of the longwall sampling plan and analysis procedures are discussed. The results of the statistical and geostatistical analysis are presented.

ISSN:0734-9343    

DOI:10.1080/07349349408905221

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Analysis of longwall channel sample data discussed in the earlier paper by the authors revealed negligible spatial correlation in sulfur content over short distances. As most coal is washed prior to use in power plants, it was decided to investigate the spatial behavior of sulfur in washed samples. This paper discusses the results of the analysis of spatial variability of sulfur in homogeneous size-gravity fractions. Procedures used for data transformations, detection of outliers and estimation of robust and nonergodic variograms are also discussed.

ISSN:0734-9343    

DOI:10.1080/07349349408905222

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Prediction of run-of-mine (R.O.M.) coal washability characteristics is of great interest during mine and preparation plant planning. The prediction is usually based on the data available from drillholes sampled during the exploration stage. This paper deals with the comparative analysis of washability data from a variety of coal seam samples—drillhole, channel, belt and R.O.M., The data was compared to investigate differences between the various types of samples. Both statistical and empirical tests were used to facilitate the comparisons. Conclusions and recommendations from these comparative analyses are presented.

ISSN:0734-9343    

DOI:10.1080/07349349408905223

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Over the past several years, much has been written about on-line analyzers: their theory of operation, their design, and their accuracy as compared to laboratory techniques. However, very little information has appeared in literature regarding the application for these analyzers and the resulting economic benefits.

ISSN:0734-9343    

DOI:10.1080/07349349408905224

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349349408905225

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349349408905226

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor