Tailored waste based glasses as secondary raw materials for porcelain stoneware

Abstract

The high temperature processing of porcelain stoneware products is attractive for the possibility to incorporate several inorganic wastes. However, even if recycling is an environmental benefit, it can be disadvantageous for the overall properties of the ceramic product, if wastes are not selected in terms of their chemical and physical characteristics. In the present work several kind of industrial and urban wastes, such as mining residues, lime, glass from dismantled cathode ray tubes and soda lime glass were used, after their vitrification. These newly formed glasses were used as partial substitution for natural feldspar sands (the glass content being from 5 to 7 wt-% of the total mix). Owing to the specific ('tailored') chemical formulation of the newly formed glasses, the modified products exhibited higher crystallisation, with a more homogeneous microstructure, leading to significant improvements in reliability and indentation fracture toughness.

Application of an Industrial Waste Glass in “Glass-Ceramic Stoneware”

“…Although attractive, any transformation of waste glasses into glass–ceramics faces a specific and quite limited market 3 . Traditional ceramics could be an alternative, because waste glasses may be used as a sintering aid for traditional formulations 17–20 . A limited amount of glass may be actually exploited for every unit of product, but it must be considered that traditional ceramics feature a mass market, very high production rates, and also a very simple and well‐established processing 3 …”

“…3 Traditional ceramics could be an alternative, because waste glasses may be used as a sintering aid for traditional formulations. [17][18][19][20] A limited amount of glass may be actually exploited for every unit of product, but it must be considered that traditional ceramics feature a mass market, very high pro-duction rates, and also a very simple and wellestablished processing. 3 The present paper is focused on a third way for the valorization of waste glasses, presented in recent papers, 21,22 applied to Plasmalit glass.…”

'Glass based stoneware' as a promising route for the recycling of waste glasses

“…The most important example of this second way is the use of recycled glass as sintering aid in the manufacturing of traditional ceramics, [6][7][8][9][10] successfully applied also to glasses from the vitrification of several inorganic waste. 11,12 The present paper is intended to explore the feasibility of a third way, focused on the massive usage of recycled glass, consisting of soda-lime glass and glasses from the dismantling of CRTs in the production of a new kind of traditional ceramics. In particular, the feldspar sand amounts, in a typical formulation for porcelain stoneware, were completely replaced by finely powdered glass, coupled with selected additives (calcium hydroxide for soda-lime glass and Al 2 O 3 platelets for CRT glasses).…”

Assessment of reuse potential of high alumina industrial waste as devitrification aid in common alumina–lime–silica glasses

“…In addition, glassy materials resulting from vitrification processes can find interesting applications, particularly when they are suited to controlled crystallisation into glass ceramics, and the utilisation of waste materials in glass ceramic production has been widely investigated. 1,4,10,11 Glass ceramics are usually produced from molten glass, which is cast to shape and subjected to heat treatment to promote crystallisation. As a result, the parent glass is transformed into a polycrystalline solid with a residual glassy phase, which displays different and sometimes outstanding properties.…”

“…Thus, the assessment of the reuse potential of all kinds of industrial wastes and byproducts is, nowadays, as important as the study of the effective inertisation of potentially hazardous components present in the waste. [1][2][3][4][5][6] Waste inertisation is generally concerned with heavy metals, and inertisation methods are aimed at reducing their quantity or mobility. To accomplish this, sintering and vitrification are among the most promising techniques, mostly due to the comparatively high processing temperatures, which lead to chemical stability, and to the significant waste volume reduction, with obvious benefits in storage and dumping requirements.…”