WASTES: Solutions, Treatments and Opportunities 1 St International Conference September 12th – 14th 2011 ANALISYS OF THE PROPERTIES OF WASTE-BASED GEOPOLYMERIC BINDERS AFTER CURING IN WATER I.C. Silva 1 , J. Castro-Gomes 2 , A. Albuquerque 3 1 Castelo Branco Polytechnic Institute and Centre of Materials and Building Technologies, University of Beira Interior, 6201-001 Covilhã, Portugal, icastanheira@ipcb.pt 2 Centre of Materials and Building Technologies, University of Beira Interior, 6201-001 Covilhã, Portugal, castro.gomes@ubi.pt 3 Centre of Materials and Building Technologies, University of Beira Interior, 6201-001 Covilhã, Portugal, ajca@ubi.pt ABSTRACT Tungsten mud from a local mine exploration may be recycled to produce geopolymeric binders after an alkaline activation. This procedure allows using these binders in several applications in construction and hydraulic works avoiding the landfilling of those wastes with several economic and environmental benefits. Preliminary tests were carried out to study the effect of different dry curing temperatures, curing water periods and mixes of mud and alkaline solutions on the structural stability and pH variation in water of waste- based geopolymeric binders. The properties (bulk density, specific surface area, chemical composition, microporosity, durability and mechanical compressive strength) of a mix with ratios R(P/S) = 5 and R(S/H) = 4 were analyzed after curing in water. The durability was also studied in solutions with 5% of acetic acid and sulfuric acid, revealing good resistance of the binders to acid attack. This study also demonstrates that mining waste mud can be used to produce geopolymeric binders for wastewater treatment processes. Keywords: acid conditions, compressive strength, mine waste mud, wastewater treatment INTRODUCTION Geopolymeric binders (or just geopolymers) may be obtained through a complex chemical reaction in an alkaline environment (condensation and polymerization) of alumino-silicate materials, called precursors (e.g., waste sludge, fly ash, slag and calcined clays). Due to its chemical composition, a particularly waste mud of the Panasqueira mine, located in Portugal, one of the most important and largest tungsten mines in the world, presents very good reactivity with alkaline activators after a thermal calcination process and under certain mixing conditions [1] to produce waste-based geopolymeric binders (WGB). They have potential for use in wastewater treatment processes, due to its suitable mechanical strength [2], good durability, capacity for resistance to acids and sulfates [3], and appropriate porosity, void ratio and specific surface. Therefore, the objective of this investigation was to analyze several properties of WGB when in contact with water and acide solutions in order to evaluate the suitability of the binders to be used in wastewater treatment processes for the treatment of urban, stormwater and industrial effluents. MATERIALS AND METHODS Characterization of the waste mud and production of alkali-activated materials Mining waste mud obtained from Panasqueira, after submitted to calcination at 800ºC temperature for 2 hours, was used as precursor (P) for the alkali-activated process. The chemical oxide and mineral compositions of the mine waste mud, determined by energy dispersive X-ray spectroscopy (SEM/EDS, RONTEC equipment, USA) and X-ray diffraction analysis (XRD, Rigaku - DMAX III/C equipment, USA) showed that has 70% of Al 2 O 3 and SiO 2 and a ratio SiO 2 /Al 2 O 3 between 3 and 4, and it consists mainly of quartz and muscovite.