Optimized Solidification of Mixtures of MSWI Fly Ash and Blast Furnace Slag: Use of the Statistical Design of Experiments

This study proposes a new method for a process development based on specific planning and use of experiments. It is the 'Statistical Design of Experiments' method, comprising the selection of experiments in a manner where the results derived from these experiments can be used for the calculation of values to be analysed. Ash produced from the Incineration of Municipal Solid Wastes is required to be solidified and stabilised prior to landfilling. MSWI fly ash is a powdery material. It is comprised of hydraulic and toxic elements. Ground granulated blast furnace slag is a suitable hydraulic binder to stabilise this ash and MSWI ash can activate the slag hydraulicity. A preliminary study was undertaken on artificial MSWI ash to analyse the influence of the variation of the content of (Ca(OH)2, CaClOH, CaS04) ash components, while taking into account their interactions effects. It was demonstrated that CaClOH content significantly influences the behavior of the material. Empirical laws were also developed to determine the mechanical and physical behavior of mixtures of industrial MSWI ash and slag. The parameters of these models were A/S, W/(A+S), and the water temperature. Then, using the various models developed, an optimum formulation of the MSWI ash and slag mixture was developed, which fulfils the requirements of French Regulations.