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Waste plaster casts and fireclay as a by-product

The manufacturing process of porcelain sanitary equipment undertaken by Roca Radiadores, S.A., is based on the casting, drying, enamelling and firing of the ceramic paste through different operations. Different mineral materials such as clay, kaolin, feldspar and silica are used as raw materials. The plaster molds used for the manufacture of ceramic pieces are produced in the same plant and are made of a mixture of plaster and water. Nevertheless, every 90 pieces manufactured they have to be replaced by new molds due to the clogging.

This process generates large quantities of waste that can be managed as a by-product: pieces of sanitary porcelain that are broken or that have not passed the quality control (ceramic chamotte) and rejected plaster molds. The residue of ceramic chamotte contains as major components SiO2 (65-68%) and Al2O3 (24-26%), and the rejected gypsum molds contain mostly hydrolysed calcium sulphate (58.5%).

The main applications of this waste are mentioned below:

  • Filling spaces generated by extraction activities, by replacing natural soil.
  • Contribution of silica, aluminium and calcium in the cement manufacturing process.
  • Substitution of aggregates in the production of refractory material, when the chamotte is incorporated.
  • Substitution of natural feldspar in extraction companies.

All these applications allow to minimize the volume of waste sent to final disposal, reduce the consumption of virgin raw materials and natural resources, reduction of costs associated with waste management and simplification of administrative procedures once the waste is classified as by-products under the Catalan administrative framework.