Clays from the Rhenish lignite mining –
alternative raw materials for heavy clay ceramics

Pictures/Bilder: RWE Power AG

»1 Hambach opencast mine

Pictures/Bilder: RWE Power AG

»2 SW-NE-cross-section through the layers of sediment in the Lower Rhine Embayment. a: Garzweile, b: Hambach, c: Inden ([2])

»3 Samples of the clays from four horizons at the opencast mines Inden (Rur block; sample 6E) and Hambach (Erft block, samples 13E and 7A and 6B). Assignment of the figures to the horizons of the deposit: cf.

»4 Thermogravimetry on the analysed samples

»5 Differential thermal analysis (exothermic and endothermic reactions):

1. Dehydration
2. Oxidation of the organics
3: Dehydroxylation of clay minerals
4. Oxidation of Fe-sulphides
cf. [7]

»6 Results of the expansion-shrinkage analysis by means of dilatometry:
1: Firing shrinkage 13E
2: Sintering interval 6E
3: Swelling interval 7A
Sintering point 6B [5]

»7 Dilatometry – section in the range of the α-β quartz inversion at 573° C

»8 Results of the hot-stage
microscopy based on the example of sample 13E:

a) Start of the analysis
b) Softening point
c) Spherical point
d) Hemisphere point
e) Yield point

»9 Specimens after firing:
clay 6E top left, clay 13E top right, clay 7A bottom left and
clay 6B bottom right

»10 Firing shrinkage of the extruded specimens at different temperatures

»11 Total shrinkage of the extruded specimens at different temperatures

»12 Water absorption of the fired samples at different temperatures

$»13 Particle size distribution of the total sample 7A (left) and light microscopy image of the fraction > 100 µm (right)$

»13 Particle size distribution of the total sample 7A (left) and light microscopy image of the fraction > 100 µm (right)

$»14 Comparison of the water absorption of the total sample 7A and the prepared sample 7A (fraction < 100 µm) at different temperatures$

»14 Comparison of the water absorption of the total sample 7A and the prepared sample 7A (fraction < 100 µm) at different temperatures

During opencast mining in the Rhenish lignite mining district, with the extraction of the coal, clays are also won from several-metres-thick and homogeneous mining horizons. The individual horizons differ in their chemical composition and mineralogy, resulting in a wide array of potentially usable raw materials. Studies on the suitability of clay raw materials from opencast lignite mines show that the clays won during opencast lignite mining are suitable for use in the ceramics industry.

1 Introduction

Lignite mining in the Rhenish mining district has a long history and has been going on in the region at the latest since industrialization in the 19th century.

In the three opencast mines Hambach, Garzweiler and Inden, around 90 mill. t lignite are mined each year, from which 70 to 75 TWh/a power is generated in the nearby power plants [1]. In addition, around 5 mill. t refined products are produced, which are used in decentralized cogeneration in numerous industrial operations as well as for environmental protection purposes. In geological terms, the lignite deposits form part...

Stefan Ginzel¹, Christoph Piribauer¹, Stefan Link¹, Rita Knodt¹, Michael Eyll-Vetter², Sven Asmus², Ulrich Krüger^2

1FGK – Forschungsinstitut für Anorganische Werkstoffe – Glas/Keramik – GmbH, Höhr-Grenzhausen
www.fgk.keramik.de

²RWE Power AG, Sparte Tagebauentwicklung, Köln
www.rwe.com

Clays from the Rhenish lignite mining –
alternative raw materials for heavy clay ceramics

1 Introduction

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Clay as a raw material – geological code determines its firing behaviour (part 1)

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Raw material enthalpy of heavy clay raw materials (Part 1)

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1 Introduction

ZI 5/2018

ZI 5/2018

Related articles:

Clays from the lignite mining district in the Rhineland – new raw materials for building ceramics!?

Clay as a raw material – geological code determines its firing behaviour (part 1)

Assessing the suitability of selected wastes as additives to clay bodies in brick manufacture

Raw material enthalpy of heavy clay raw materials (Part 1)

Test methods for heavy clay ceramic raw materials: raw material composition (primary properties) – part 1