摘要:

Experimental apparatus for the determination of powder wettability is described. The principle of the technique is based on the measurement of the equilibrium capillary pressure in a packed bed of particles. Both the macroscopic solid-solution-vapour contact angle, θ, and the specific surface area, A(m2g−1), of the powder, can be obtained. Experiments on angular quartz particles have been performed. A wide range of situations have been covered: hydrophilic and hydrophobic particles wetted with water, a variety of organic liquids and solutions of surfactants. The results show that reliable and reproducible values for θ and A for angular and relatively coarse powders can be obtained with the proposed equipment for advancing liquid fronts in the absence of soluble surfactants. In the latter case, and for receding liquid fronts in general, only qualitative trends have been obtained.

ISSN:0734-9343    

DOI:10.1080/07349349308905118

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effect of reducing agents on the flotation of steam coal is studied and it is shown that such a treatment may result in significant improvement in coal floatability.

ISSN:0734-9343    

DOI:10.1080/07349349308905119

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

It has been found that selective resinite flotation from Wasatch Plateau coal can be achieved at high pH. For example, a high grade resin concentrate (>70% resin) was obtained at an excellent recovery (>90%) by single-stage flotation above pH 12 from a feed containing only 7.2% resin. This rougher concentrate was then cleaned to produce a cleaner concentrate containing >90% resin. The flotation results thus obtained by pH control can be explained to be due to: (1) improved dispersion of the resinite/coal suspension as evidenced by microscopic observation, electrokinetic behavior, and sedimentation phenomena: and (2) improved depression of coal particles; their hydrophilic state being stabilized by surface precipitation and/or adsorption of calcium species at higher pH values as determined by FTIR and XPS spectroscopic analysis.

ISSN:0734-9343    

DOI:10.1080/07349349308905120

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A group of bifunctional organosulfur compounds were tested as pyrite depressants for improving the separation of coal and pyrite by selective oil agglomeration. Preliminary screening tests of potential depressants were carried out with pyrite which had been sulfurized by treatment with a freshly acidified solution of sodium sulfide to increase its response to oil agglomeration. High-grade mineral pyrite was used for most of these tests, but pyrite extracted from coal was used for some tests. When heptane was used as an agglomerant, the following organic thiols were found to suppress the agglomeration of sulfurized pyrite: thioglycolic acid, thiolactic acid, mercaptosuccinic acid, 3-mercaplopropionic acid, and 2-mercaptoetbanesulfonic acid. Each of these materials contains both a sulfhydryl group (-SH) and a hydrophilic group. The materials were also shown to improve the separation of artificial mixtures of Illinois No. 6 coal and sulfurized pyrite in other tests involving agglomeration with heptane. However, the best separation was achieved when thioglycolic acid was employed.

ISSN:0734-9343    

DOI:10.1080/07349349308905121

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effect of grinding mode on the efficiency of separation of pyrite and non-pyritic minerals from Pittshurgh No. S scam coal hy froth flotation was investigated. In the case of minus 600 micron feed, grinding mode had no effect on the efficiency of separation of cither pyrite or non-pyritic minerals. With minus 75 micron feed, however, the selectivity achieved with the wet ground feed was higher than that ohtaincd using the dry grind and this was attributed to the dry state aggregation of coal with mineral matter. Comparison of flotation selectivity and washahilitv curves showed that entrainment of fines due to water flow was the reason for the loss of selectivity during flotation of coal from non-pyritic minerals. In the ease of pyrite, in audition to entrainment. flotation of pyrite due to its natural hydrophobicity contributed to the loss of selectivity.

ISSN:0734-9343    

DOI:10.1080/07349349308905122

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Coal preparation plant operators often do not optimize the flotation and dewatering processes. In order for these processes to operate efficiently, the equipment should be adjusted after every change in feed rate or quality. Unfortunately, neglect of the final coal processes causes processing additives and coal to be wasted and in some cases, unnecessary outages of the entire cleaning plant. Consequently, revenues decrease.

ISSN:0734-9343    

DOI:10.1080/07349349308905123

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A technique for balancing raw washability data utilizing the least-squares approach is proposed. The sum of the squares of the relative errors between the raw and estimated data is minimized. The generated balanced data satisfy mass and ash balance conditions. Actual data are used to illustrate the proposed technique.

ISSN:0734-9343    

DOI:10.1080/07349349308905124

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effective coal desulphurization may be achieved prior to combustion by electrostatic separation of pyrite grains. In this paper, the problem of the contact electrification of pyrite and coal grains is considered and the conditions for efficient liberation and separation of pyrite microcrystals from the coal matrix are discussed. The low cost electrostatic separator and the coal crusher of our own construction are briefly described. As an example, the results of the electrostatic desulphurization of five Polish steam coals are presented. An idea to apply (for ecological reasons) an electrostatic separation together with other more expensive desulphurization methods is suggested.

ISSN:0734-9343    

DOI:10.1080/07349349308905125

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A new device has been constructed for measuring of rheological properties of rapidly sedimenting suspensions. It is a double-gap coaxial fixture attached to a driving unit of a commercial rheometer. The suspension is kept from sedimenting by circulation which influences the results and, therefore, should be stopped during measurement. The influence of the circulational axial flow on the measured viscosity was presented on examples of a contaminated and pure magnetite dense medium. It is due to the additional shearing caused by the axial flow and to the inertia of the entering fluid to which the rotation must be applied.

ISSN:0734-9343    

DOI:10.1080/07349349308905126

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0734-9343    

DOI:10.1080/07349349308905127

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor