Use of secondary raw materials derived from waste streams in the ceramic sector reduces industry dependency from raw material prices and availability.
Glazed ceramic tiles are the most common building material for floor and wall covering. Glazes are produced from frits. Among the available commercial frits, those containing zircon (ZrSiO4) and zirconia (ZrO2) are of great interest. The cost of pure zircon and zirconia, in the last few years has greatly increased. Therefore, finding alternatives or replacements to these raw materials is an economic advantage.
An opportunity derives from industrial gas turbines applications which are protected by a so called Thermal Barrier Coating (TBC) system, containing zirconia. TBC are commonly applied via an Atmospheric Plasma Spraying deposition process, during which a high amount (70- 90%) of thermally sprayed zirconia does not stick to the growing coating, becoming “overspray”. That is a waste material which can either stick, instead, to the walls of the deposition chamber, or, mainly, fall on the ground or be sucked in by the air filter.
This demonstration project, with EU LIFE funding, has demonstrated the possibility of absorbing 100% of the waste produced by the thermal spraying plants as secondary raw material for frits. The material reuse is possible thanks to separating waste generation at the source, and immobilization of harmful contaminants of spent thermal spray powders (mainly heavy metals) in matrices (glass-ceramics, pigments, ceramic mixtures, glazes).
The project involved Ceramica Fondovalle s.p.a., Fritta Italia s.r.l., Turbocoating s.p.a., 4Sint s.r.l., Majorca s.p.a. and the University of Modena and Reggio Emilia. The overall budget was 2,5 M€ with an
EU contribution of 1,2 M€.
Evidence of success
The new process will allow to increase the direct economic value generated from 5% to 30%, depending on the type of product which will be manufactured using the spent powders.
This derives also from the expected reduction of manufacturing energy costs (reduction of 30%), raw materials costs (reduction of approximately 20% for glazes and frits and of 90% for SPS-ed products), reduction of the manufacturing cost per unit product (reduction of 10% for ceramic tiles and up to 40% for SPS).
The secondary raw material available from one thermal spraying plant alone is insufficient in terms of quantity to cover the whole demand from the sintered product producer. Therefore a wider application of this solution is needed.
Potential for learning or transfer
The proposed solution is applicable worldwide, but it will provide the best results when the waste production site (thermal spraying plants) is situated near a sintered product or a ceramic tile manufacturer. Similar conditions of ceramic industrial districts compared to that in the area of Modena can be found in many different EU areas, such as Spain (between Madrid and Valencia) or all over Germany and France.
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