Lisandro Simão

Structural and fluid dynamic characterization of calcium carbonate-based porous ceramics

The aim of this work was to experimentally evaluate the use of calcium carbonate as a pore-generating agent in ceramic compositions. Compositions that contained 50% kaolin, 20% limestone, and different concentrations of quartz and feldspar were prepared by uniaxial pressing. Samples were heat-treated at a heating rate appropriate to induce calcium carbonate degassing, and they were then sintered at 800, 900, and 1050 °C. Tests of X-ray fluorescence, thermogravimetric analysis, porosimetry, and air permeation were performed. The composition (wt%) that contained 50% kaolin, 20% limestone, 20% feldspar, and 10% quartz and heat treated at 1050 °C (

Porous Ceramic Structures Obtained from Calcium Carbonate as Pore Generating Agent

The aim of this work is to present experimental results related to the use of calcium carbonate as pore generating agent. Four compositions containing 20 wt.% of limestone were used and characterized chemically and thermally. Each composition was homogenized in a porcelain ball mill, dried in a laboratory drier, humidified at 7 wt.%, and pressed in an uniaxial hydraulic press. Compacted samples were dried and heat treated with a suitable heating rate for the degasification of calcium carbonate and sintered at 800, 900, and 1050 °C. Sintered samples were characterized to determine the porosity, crystalline phases formed and microstructural features. The results showed that the porosity has increased with the sintering temperature of the compositions increasing due porosity generated by the calcium carbonate degasification and the material expansion.

Obtainment of Porous Ceramic Structures: A Comparison among Different Compositions and Methods of Conformation

This paper presents comparative results concerning to the obtaining of porous ceramic structures obtained by pressing, slip casting and polymeric sponge method. Three compositions were prepared, using calcium carbonate as pore-generating agent and characterized by X-ray fluorescence, thermogravimetric analysis and determination of sintering behavior. Each formulation was wet mixed and dried. Then, each formulation was formed by each one of the investigated methods. The obtained samples were dried and heat treated with the appropriate heating rate for calcium carbonate degasification and sintered at 900, 1100 and 1180 °C. The sintered samples were characterized by determination of porosity, crystalline phases formed, compressive strength and permeability. Results showed that porosity and permeability depends strongly on the composition and used conformation method.

Structural Refinement by the Rietveld Method on Clinkers Obtained from Waste from Pulp and Paper Mills

Pulp and paper mills have a process that generates waste with high levels of CaO and SiO2, which can be valued as an alternative mineral source in the cement industry. In this work the lime mud, biomass ashes and WWTP sludge are used in the production of clinker. Analysis of X-ray diffraction (XRD) confirmed the crystalline phases calcite and quartz. Chemical analysis by X-ray fluorescence (XRF) identified Al2O3, CaO and SiO2, providing support for the calculation of theoretical stages by applying the Bogue equations. Five formulations and three processing temperatures (1350, 1400, 1455 °C) were studied. The products obtained and an ordinary Portland cement (OPC) were characterized by XRD with quantification by the Rietveld method. The results showed that the processing conditions used produced belíticos (higher content of C2S) and Portland (C3S content greater) ecoclinker.

Wastes from pulp and paper mills - a review of generation and recycling alternatives

The concept of sustainability has been applied over the years in all manufacturing activities, including pulp and paper mills, which represent an important worldwide economic activity and cause remarkable environmental impact [1]. In this context, waste management plays an important role in a modern management system [2] and becomes one of the requirements for attenuation of the generated impact, not only from the environmental stance but also from the economic and social points of view. According to the European Commission (EC) and the United States Environmental Protection Agency (USEPA), residues are classified as wastes and by-products [3, 4]. The Resource Conservation and Recovery Act (RCRA) §1004(27) of the USEPA defines solid waste as any garbage, sludge from a wastewater or water treatment plant, or any other discarded material (solid, liquid, semisolid, or contained gaseous material) resulting from industrial activities, commercial, mining, or agricultural operations or from communities. Likewise, a by-product is defined by RCRA §261.1(c) (3) [4] as a material that is not one of the primary products of a production process and is not solely or separately produced by the production process. A by-product may include most wastes that are not spent materials or sludge. The Directive of EC 2008/98/CE defines a by-product as any residue whose subsequent use without Wastes from pulp and paper mills a review of generation and recycling alternatives

Thermal characterization of hydrated eco-friendly clinkers produced from pulp and paper mill waste

Industrial wastes from pulp and paper mills are potentially useful materials to use as alternative materials in clinker production. In this study, eco-friendly clinkers were obtained using only waste as feedstock. Eco-friendly clinker with different C3S and C2S contents were produced and hydrated for 7 days at 40 °C, or for 28 and 90 days at room temperature. The potentialities of these waste and the products obtained were revealed through chemical (XRF), thermal (DTA/TG) and surface area (BET) analysis. For comparison, a common ordinary Portland cement (OPC) was tested. As expected, the hydration rate of formulations presenting higher C3S content was higher, generating higher amounts of Ca(OH)2. Furthermore, the amount of Portlandite formed was lower when compared to OPC.

Permeability of Porous Ceramic Membranes Obtained from Waste of the Coal Extraction Process

The coal extraction generates large amounts of coal waste. Powders of this waste can be pressed with the addition of binder in order to obtain ceramics, such as ceramic membranes. In this case, polymeric fibers can be used to increase permeability. This work aims to study the permeability of ceramic structures composed by coal waste and different amounts of polymeric fibers. The compositions were homogenized, pressed and thermally treated at 1050 °C. Samples were characterized in relation to porosity determination, permeability and microstructural features. The results showed that the permeability increased with the increase of the fiber content. However, the composition containing 0.5 vol% of polypropylene fibers showed the best results for using in aerosol filtration permeability.