Aplicações industriais de natas resultantes da indústria transformadora de rochas ornamentais carbonatadas

Abstract

As industrias extractivas e transformadoras de rochas ornamentais, produzem grandes quantidades de residuos, que por niio terem nenhuma aplicaqiio industrial, siio amontoados a ciu aberto causando impactes ambientais de variada ordem. Numa tentativa de rninirnizar OS problemas ambientais existentes na zona de Estremoz (Alto Alentejo), bem como rentabiliiar residuos, que pelas suas caracteristicas se podem tornar hturas materias primas para diierentes industrias, realizaram-se estudos com vista a aplicabilidade das lamas provenientes do corte, serragem e polimento dos marmores. Estas lamas, quando drenadas para tanques de decantagiio, t6m um aspect0 pastoso e esbranquigado, raziio pela qual, na linguagem utilizada por aqueles que trabalham nesta actividade B vulgar o uso do termo "natas". A investigagiio iniciou-se com um levantamento das fabricas nas zonas de Estremoz, Borba, Vila Vigosa e Alandroal. AtravBs de um questionhi0 distribuido aos industriais, tentou-se quantificar a produqiio de "natas" nesta zona, e definir os problemas causados pela acumulaqiio de tais residuos. Seguiu-se uma fase laboratorial, que consistiu na caracterizaqiio fisico-quimica das lamas, com vista a uma hra aplicagiio em indhtrias previamente seleccionadas. Por fim, foram executadas experisncias nas indhstrias dos marmores compactos, da cerhica e do papel, tendo-se obtido os respectivos produtos finais, que posteriormente foram testados corn vista a comprovagiio da exequibilidade tBcnica destas lamas. A investigagiio desenvolvida levou a resultados anirnadores nas tr2s industrias estudadas, tendo-se provado a sua aplicabilidade.

The extractive and manufacturing marble industries produce a great quantity of residues which don't have any industrial application and are piled up in the open air causing several environmental impacts. Attempting to minimize the environmental problems existing in the area of Estremoz (Alto Alentejo), as well to make sludges profitable, which by its distinguishing marks can be worked in order to become natural material for different kinds of industries, essays have been worked up in order to achieve the workability of marble sludges proceeding from the cutting, sawing and polishing of marble. These muds when drained to decantation tanks have a thick and white appearance. This is the reason why according to the language used by those who work in this activity is usual to use the word "natas" - cream (the fatty part of milk). The investigation began with the study of the factories in the region of Estremoz, Borba, Vila Vigosa and Alandroal. Through a questionaire given to the producers we tried to quantify the production of rnuds ("natas") in this area and define the problems caused by the accumulation of the sludges. A laboratorial phase was followed, it consisted in the physicochemical charaterization of the muds aiming their potencial application in industries previously selected. To conclude the investigation experimental research was carried out concerned with compact applications of the rnuds in marble industries, pottery and paper industries. Teclrnological properties of the final products were tested on a second stage seeking evidence of the technological workability of the carbonate muds. The investigation so far developed disclosed encouraging results in any of the three industrial applications referred to, having corroborated its workability.