The preparation of slag from colliery shale

European Union

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Industrial research and development

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• Sciences et techniques

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• Publié par: EUROPEAN-UNION
• Nombre de lectures: 7
• Langue: English
• Poids de l'ouvrage: 3 Mo

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Commission of the European Communities
technical coal research
THE PREPARATION OF SLAG FROM SHALE
Report
EUR 9058 EN
Blow-up from microfiche original Commission of the European Communities
technical coal research
THE PREPARATION OF SLAG FROM SHALE
National Coal Board
Coal Research Establishment
Stoke Orchard
Cheltenham
UK - Gloucestershire CL52 4RZ
Contract No. 7220-EC/818
FINAL REPORT
Directorate-General Energy
1984 EUR 9058 EN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Information Market and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of then is responsible for the use which might be made of the following
information
©ECSC — EEC — EAEC, Brussels · Luxembourg, 1984 III
THE PREPARATION OF SLAG FROM COLLIERY SHALE
SUMMARY
In this study the preparation of slag from colliery shale, using
its inherent coal as a source of heat for the melting process, has
been investigated. The effects of different cooling methods on the
properties of the slag and ways of utilising the slag product were
also examined.
Previous work demonstrated that air-cooled slag was technically
satisfactory for use as concrete aggregate but that it was a brittle,
glassy material. Experiments in this study showed that air-cooling of
.the molten shale slag at a slow rate did not produce a highly
crystalline (low glass content) material or improve the mechanical
properties of the slag aggregate.
A totally glassy granulated slag product was prepared by
quenching molten shale slag in water. This material and also air
cooled slag, when finely ground, exhibited pozzolanic activity and may
have application as a substitute for ordinary Portland cement.
A lightweight aggregate was produced by foaming molten shale
slag. In order to attain the bulk density requirement for lightweight
aggregate (<960 kg/m3) it was necessary to reduce the slag viscosity
by the addition of flux. By varying the level of flux addition,
foamed slag of different bulk density was produced and the bulk
density was also directly related to the silica ratio of the slag. At
high levels of flux addition, bulk densities of 100-200 kg/m3 may be
achieved. This material, processed in the form of slabs, may be
suitable for roof and wall insulation. IV
Viscosity measurements on a range of shale slags showed that the
addition of flux significantly reduced their viscosity. A slag of
silica ratio 52 should have a viscosity low enough for fiberisation at
1340-1450OÇ, Samples of mineral fibre were produced from suitable
blends of shale and flux.
A cyclone furnace was evaluated as a possible continuous method
for producing slag from shale, using its inherent coal as a source of
heat. A small experimental cyclone furnace, operating at I600oc,
achieved combustion efficiencies of 91—95% whan producing slag from
shale. However the shale feed rate was lower than the design value
and the auxiliary coal input was higher than the theoretical
requirement. Operational problems were also encountered with the
experimental furnace because of blockages of the slag outlet and rapid
deterioration of the refractory lining. THE PREPARATION OF SLAG FROM COLLIERY SHALE
CONTENTS
Page No.
1 1. Introduction
Air-cooled Shale Slag 3
2.1 Introduction
2.2 Effect of cooling rate on the aicrostructure
of shale slag 4
2.2.1 Birch Coppice slag Ί
2.2.2 Pye Hill slag 5
2.3 Effect of cooling rate on the mechanical
properties of shale slag
3. Granulated Shale Slag 6
3.1 Introduction 6
3.2 Preparation of granulated slag 7
7 3.3 Assessment of pozzolanic activity
7 3.3.1 Pozzolanicity test
3.3.2 Compressive strength tests 8
4. Foamed Shale Slag 1C
4.1 Introduction
4.2 Preparation of foamed shale slag 11
4.3 Effect of flux addition on the bulk density
of foamed shale slag 1
4.4 Properties of foamed slag aggregate 14
4.5s of lightweight concrete prepared
from foamed slag aggregate
4.6 Properties of concrete building blocks
prepared from foamed slag aggregate 15
4.7 Possible application of foamed slag of very
low density 16 VI
Page No.
5. Low Viscosity Shale Slag for Mineral Fibres 17
5.1 Introduction 1
5.2 Determination of the viscosity/temperature
characteristics of flux-amended shale slag 18
5.3 Preparation of mineral fibres from shale/flux
blends 20
5.3.1 Continuous filament fibre 2
5.3.2 Discontinuous filament fibre1
6. Preparation of Shale Slag in the 0.3 m Diameter
Cyclone Furnace1
6.1 Introduction
6.2 The suitability of colliery shale as a fuel
for a cyclone furnace 22
6.3 The 0.3 m diameter cyclone furnace 24
6.4 Operational experience
6.5 Mass and heat balance determinations6
6.5.1 Firing on coal
6.5.2g on colliery shale and coal 28
7. Discussion 31
8. Conclusions7
9- References8
Tables 1-26
Figures 1 - 22 VII
Appendices
1. 50 mm Diameter Tube Furnace
2. 15 kg Gas-Fired Furnace
3. Determination of the Viscosity/Temperature
Characteristics of Shale Slag by the Terminal Force Method
4. 0.3 m Diameter Cyclone Furnace
5. Heat Balances for the Preparation of Slag from Colliery
Shale in a Cyclone Furnace