New environmentally friendly forming technique of ceramic sanitary wares by isostatic pressing.

PROJECT DESCRIPTION

BACKGROUND

Slip casting in moulds made of plaster (traditional casting) or porous acrylic resin (pressure casting) is the common way of producing ceramic sanitary wares all over the world. But the process consumes significant amounts of water and energy, and produces high volumes of wastewater and other waste streams. For example, the washing of acrylic moulds consumes large amounts of water per piece, in order to regenerate the moulds for further castings. The same quantity of wastewater is thus generated, but it now contains material that must be removed using chemical products, such as coagulants and flocculants. The removed solid matter and the non-reusable moulds are also a source of solid waste. The actual forming process consumes a large amount of energy in the heating of water for washing the molds and drying the sanitary wares, resulting in CO2 emissions. A new solution based on an isostatic pressing process has the potential to reduce the consumption of natural resources and the generation of wastewater and solid waste. Eliminating water consumption, while reducing the energy consumption and the generation of wastewater, waste and CO2 emissions, is in line with the goals of the 7th Environment Action Programme.

OBJECTIVES

The main goal of the LIFE ENVIP project was to construct on a pre-industrial scale a prototype facility for forming sanitary wares by isostatic pressing of granulated body. This innovative technology is a promising alternative to the traditional method.

The main specific objectives of the project were to:

Eliminate the water consumption associated with the traditional forming process by pressure slip casting;

Reduce the volume of wastewater generated in the process;

Reduce the volume of waste generated in the process;

Reduce energy consumption and CO2 emissions;

Demonstrate that the forming process by isostatic pressing allows the production of sanitary wares with the required quality levels and technical specifications;

Identify the optimal conditions for the industrial forming process of sanitary wares with different geometries and dimensions;

Validate the compositions for different ceramic pastes used in the isostatic pressing process;

Disseminate the environmental improvements achieved with the new forming technology across the EU; and

Identify, validate and communicate the application of this innovative technology, which can be potentially considered as a Best Available Technique to update the BREF in the sanitary wares' industry.

RESULTS

The main outcome of the LIFE ENVIP project was the construction on a pre-industrial scale of a prototype facility, for forming sanitary wares by an innovative technology based on isostatic pressing of granulated body, This facility was developed and validated at the beneficiary’s factory in Gavà, Barcelona. This technology had never been used before in sanitary manufacturing.

The first step was to define the specifications of the different types of equipment making up the prototype, as well as the needed infrastructure and services. To improve the performance of the traditional process, the prototype was designed to produce more than 60 sanitary pieces per hour. The beneficiary also designed and subcontracted the manufacture of several moulds covering a wide range of sanitary pieces (washbasins, shower trays, bidets and pans). During the optimisation phase, these moulds were tested in the prototype, with several formulations of granulated bodies based on vitreous china and fine fire clay formulas. The project team were thus able to optimize the operational conditions of the new process: (humidity: 1.8% ±0.3); press pressure: 250 to 300 bar; and mould filling speed: 23". Finally, the new technology was integrated into the beneficiary’s existing glazing and firing processes. Because the pieces obtained from the isostatic press had the required humidity, no additional drying process was needed.

Furthermore, the project validated the compositions of different ceramic bodies used in the isostatic pressing process, based on several blends of the traditional sanitary ware formulas. Additionally, some alternative bodies were tested, combining different percentages of materials such as clay, kaolin, feldspar and quartz.

The results obtained in the validation phase confirm that the new technology is able to significantly reduce the overall environmental impact of the sanitary wares' forming process. Given that water is not required for washing the moulds, the volume of wastewater is zero, as well as the volume of waste generated in the treatment of the wastewater. The energy consumption and CO2 emissions are reduced because some processes (drying of sanitary pieces, treatment of wastewater) are not necessary with the new technology. This new technology was thus demonstrated to be a feasible alternative to the traditional process for forming sanitary wares by slip casting, increasing productivity and reducing environmental impacts. It could therefore be promoted as a Best Available Technology (BAT) of the sector, for specific geometries of sanitary ware. ROCA plans in a medium-term to replicate this technology in its plants across the world, as a complementary manufacturing technology. It is focused on optimising the system for extracting pieces from the isostatic press, and thus bring the process up to full operation.

Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).