A method for estimating the specific heat capacity of a raw clay mixture

»1 Comparison of measured specific heat values and those of the literature for a pure tin oxide powder [4]

»2 DTA and TGA thermograms of the model clays: kaolinite (a), muscovite (b), illite (c) and montmorillonite (d)

»3 Measurement of heat capacity of kaolinite showing a peak

»4 Influence of residual humidity on heat capacity of kaolinite

»5 Measured specific heat values of fired and unfired model clays for kaolinite (a), muscovite (b), illite (c) and montmorillonite (d)

»6 Specific heat of fired model clays, measured values and predictions with the rule of mixture for kaolinite (a), muscovite (b), illite (c) and montmorillonite (d)

»7 Specific heat values at 147° C of raw and fired model clays

»8 Heat capacity evolution for the commercial green and fired clay-based material

»9 Prediction of the heat capacity of the commercial clay-based material

For an industrial clay mixture, the presence of hydroxyl groups in the phyllosilicate phases significantly increases the value of the specific heat capacity. Following dehydroxylation, the rule of mixtures can be used to predict the heat capacity of the thermally treated clay material based on literature values attributed to the simpler component oxides. In this work, a value for the hydroxyl component has been determined from comparison of data for hydroxylated compounds before and after dehydroxylation. The mean value equal to 2 950 Jkg^-1K^-1 at room temperature is then used with the rule of mixtures to predict values for simplified and industrial grade raw clay mixtures with an accuracy of ± 3%.

1 Introduction

Clays are basic raw materials used in large quantities for the manufacture of tiles, bricks, fireclay refractories and whitewares. The energy cost for such large-scale production in the ceramic industry has become a critical issue. Typically, the fabrication process involves forming where the raw material mixture is worked into the required shape, for example by (wet) pressing, drying and then firing to obtain a dense, robust object. Consequently, evaluation of the specific heat capacity of the raw material and its subsequent variation with thermal treatment represents...

Issue 04/2021

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

1 Introduction Energy savings and the associated cost reductions are a key issue in the clay brick and roofing tile industry. It is known that the enthalpy of the heavy clay raw materials to be fired...

Issue 06/2014

Differences in the production-related properties of the three primary clay minerals kaolinite-illite-montmorillonite (Part 2)

4 Shaping properties To this day, there is no uniform laboratory process for measuring plasticity as this is used as a collective term for many complex properties such as viscosity, yield or...

Issue 04/2014

Differences in the production-related properties of the three primary clay minerals kaolinite-illite-montmorillonite (Part 1)

1 Introduction Nanotechnology and nanopowders have become very popular terms today. There is, however, one raw material that has been used for thousands of years and whose special properties are...

Issue 4/2018 Dr.-Ing. A. Tretau1, M.Sc. M. Powilleit2, Dr. S. Kirschbaum2

Short-term heat storage in the heavy clay industry

1 Introduction The manufacture of clay bricks and roofing tiles involves a very complex production process. Slight deviations in the composition of the clay body, the shaping parameters or the drying...

Issue 03/2024

Hydrogen – a future fuel gas for brick plants? (part 3)

6 Results of the laboratory tests 6.1 Composition of the raw materials Depending on the type of the deposit, the raw materials differ substantially from each other in some cases, and were assigned to...