Production Of Ceramic Bodies Research Articles

Thermal Behavior of Ceramic Bodies Based on Fly Ash and Smectites

Clay minerals have a great influence on the resulting properties of ceramic bodies. Fly ash as a waste material from burning black coal in power plants is a potentially valuable source of oxides (Al2O3, SiO2 or Fe2O3) for this production. Considering the process of ceramic firing, it is important to understand the thermal behavior of individual ingredients. The thermal behavior of natural smectite minerals (montmorillonite, beidellite, hectorite and nontronite) and their mixtures with added fly ash at different ratios (10%, 30% and 50%) was investigated. The phase analysis was obtained using X-ray diffraction and FT-IR spectroscopy. Under heating to 1200 °C, the structural changes of smectites were divided into four steps including dehydration, dehydroxylation, decomposition and crystallization of new phases. The addition of fly ash caused a shift in the reaction temperatures for all the mentioned phases. These changes were most noticeable for mixtures with hectorite; on the contrary, they were least noticeable for beidellite mixtures. Total mixture mass loss continually decreased with increasing fly ash amount. The obtained experimental thermal data can be applicable not only in the production of ceramic bodies or energy waste processing but also in construction and ensuring the safety of municipal waste landfills.

Analysis of Dimension Stone Waste Addition to the Clayey Mass Used in Roof Tile Production

Addition of dimension stone waste to clayey mass is an alternative to make the dimension stone sector more environmentally sustainable and to reduce the consumption of clayey raw material. Our aim is to study the technical feasibility of dimension stone waste addition to the clayey mass used in roof tile production. Samples of waste and clay were tested for physical, chemical, mineralogical and microstructural characterization. Samples containing dimension stone waste contents, varying from 10% to 90% (wt.), were produced and burned in industrial furnace of a structural ceramic factory at a 900°C maximum temperature for 24 hours. The technological characteristics evaluated were water absorption, apparent porosity, apparent density, loss on ignition, linear shrinkage and flexural strength. The results show that the samples with up to 60% waste content can be used in the production of ceramic bodies, since the waste promoted the physical packing of the grains, which increased the densification of ceramic bodies. With that, the waste-improved ceramic characteristics were analyzed. From 60% content onwards, the waste was not be able to fill the remaining interstices between the clay grains to densify the ceramic body because both raw materials have similar particle size distribution. Furthermore, the excess silica, in the form of quartz contained in the waste, presents an inert behavior in the factory firing temperature used in this research, causing fracture points and decreasing the flexural strength.

Manufacture of Ceramic Bodies by Using a Mud Waste from the TiO<sub>2</sub> Pigment Industry

The main objective of this paper is focused in the use of waste generated by the TiO2 pigment industry, ilmenite mud (MUD), on the production of ceramic bodies. These ceramic bodies were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt%). The samples were sintered to simulate a fast-firing process. The sintering behaviour of the fired samples was evaluated according to ISO rules by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, the activity concentrations of radionuclides were measured by high-resolution low-background gamma spectrometry, because this mud is a NORM (Naturally Occurring Radioactive Material) waste. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of use tiles from an environmental perspective. The results demonstrated that MUD can be successfully valorisated in the manufacture of red stoneware ceramic bodies with similar, or even better technological properties than commercial materials used currently.

Ceramic Tiles Obtained from Clay Mixtures with the Addition of Diverse Metallurgical Wastes

The generation of industrial residues is unavoidable, but these materials may be recovered, redirecting them toward new production processes, rather than allocating them to the stream of discards. The aim of this paper is to study the feasibility of utilization of metallurgical wastes as raw material for tiles in the ceramic industry, using the residual materials as aggregates in clay based ceramics. The residues used are: sludge and slag from several metallurgical processes, Ruthner dust and foundry sand. Samples were obtained from mixtures of clay and each waste in various percentages, which were then heat treated. The pieces obtained were characterized using several techniques, with the aim of determining the properties of these materials in relation to the commercial requirements. A high feasibility of reuse of most of these wastes as raw material in the production of ceramic bodies has been established.

Application of bauxite waste from amazon region in the heavy clay industry

In this work, a method was developed for the application of red mud, an alkaline leaching waste, from a bauxite processing plant located in northern Brazil (Amazon region) as starting material for heavy clay products. Samples were prepared by pressing blends of red mud and clay, which were then fired at temperatures from 900 ºC to 1190 ºC. Characterization was carried out by chemical analysis, differential thermal analysis (DTA) and X-ray diffraction (XRD), and the following ceramic properties were evaluated: water absorption, linear shrinkage and flexural strength. In order to evaluate the Na+ stability in the dense ceramic, leaching tests were also carried out on the specimens after sintering process. Results indicated that samples with 50 and 70 wt% of red mud are proper for being used in the production of ceramic bodies, due to its excellent properties, mainly high mechanical resistance and low water absorption, showing thus, an option to minimizing the environmental impacts caused by the aluminum industry.

Production of ceramic bodies from Tunisian Cretaceous clays

AbstractThe aim of this research was to assess the potential application of the Late Cretaceous levels as raw material for the production of ceramic tiles. Mineralogical, chemical and grain size distribution studies were carried out on four clays sampled at different sites in the Tunisian Central Atlas. Clays are mainly composed of phyllosilicates, usually illite and kaolinite. Quartz, feldspars and dolomite were also detected.Tiles were prepared by pressing clay bodies at 250 bar and then firing at different temperatures following industrial conditions as closely as possible. Thermal analysis showed the influence of mineralogical composition and grain size distribution on the material behaviour during firing. The physical properties of fired tiles were obtained from specific tests in accordance with international standards (ISO), i.e. the firing shrinkage, water absorption, apparent density and flexural strength. The development of physical properties indicates an optimal firing range between 1050–1150°C. Results demonstrate the potential of Late Cretaceous materials as raw materials for the production of ceramic tiles.

Effect of surface roughness on grain growth and sintering of alumina

The production of ceramic bodies with less surface roughness is industrially important when one considers the aspect of final machining processes. Hence an attempt have been made to study the variation in surface roughness parameters (R a, R y, R z) of alumina having three different kinds of roughness features at different sintering temperatures. Variation in surface roughness properties are also correlated with grain size. R z shows significant difference between fine and intermediate surfaces, hence predicts small difference in their microstructural features. As a general trend, average grain size increases with increase in sintering temperature, but wide distribution of grains with enhanced non-uniform grain growth is observed when the surface is coarse. Hence, creation of fine surface in the green body is necessary for homogeneously distributed grains with controlled uniform grain growth. The final roughness and grain size of the sintered alumina depend on the initial surface roughness of the green body.