Estudo da aplicação de resíduo de galvanoplastia oriundo do Polo Industrial de Manaus como matéria-prima em cerâmica vermelha

Abstract

Electroplating is a chemical or electrolytic process where a thin layer of a metal is applied over a part that can be metallic or not, to give resistance, beauty and prevent corrosion of these parts. Because it is an activity that generates toxic waste, they are dangerous, and cause impacts to the environment and living beings when disposed of inappropriately. This research aims to verify the incorporation of electroplating sludge from a company in the Manaus industrial pole in the clay mass for the manufacture of red ceramics. The raw materials were collected and characterized by means of X-ray fluorescence tests, X-ray diffraction, thermal analysis (TG and DSC), Atterberg indexes and particle analysis. Based on a 2³ factorial experimental design, samples were formulated with incorporation of the residue in the proportions of 0, 10 and 20% by weight in the clay, the sintering temperatures were 850, 950 and 1050ºC and 60 min firing levels were used, 120 min and 180 min. Specimens with dimensions of 60x20x5 mm³ were prepared by uniaxial pressing of 30 MPa. Technological properties such as water absorption, linear burning shrinkage, flexural rupture stress, apparent porosity, apparent specific mass were evaluated. In addition, the immobilization in the ceramic body of the dangerous elements present in the galvanic sludge was evaluated, by means of the leaching test (NBR 10005) and scanning electron microscopy (SEM) of the rupture section. It was found that the increase in the incorporation of electroplating sludge reduced the compressive strength and increased the linear shrinkage, apparent porosity and water absorption. Although the introduction of galvanic sludge has influenced the mechanical and physical properties, these parameters are sufficient according to the values required by normative standards. Through factorial planning, it was possible to verify that water absorption and the flexural tensile strength of the specimens with a percentage of up to 20% of residue in the ceramic mass, can be suitable for the production of solid bricks for sealing, bricks for sealing with horizontal holes and tiles meeting the requirements required by NBR 15270-1 and by the literature. It was also found that the sintering temperature for the percentage of 20% may be lower than the maximum used (1050 ºC), promoting energy savings. The leaching test indicated immobilization of the Cr metal analyzed according to NBR 10004, making it possible to use this residue to minimize the negative impacts caused to the environment and human health.