Environmental study and valorization of an ashy waste: case of pyrrhotite ash

Abstract

Pyrrhotite ash is an industrial waste which is currently stored in large quantities in a large area in southwest of Morocco. The literature review revealed that this waste has been used by some cement industries and has not been the subject of any environmental study or valuation in another area. This work focuses on the environmental study of pyrrhotite ash. This study consists of a dynamic test with renewing lixiviate more particularly the leaching tank test. The protocol used is extracted from the Dutch standard NEN 7345 with modification of the volume of water used and the number of extraction. Quantitative analysis by ICP has shown that pyrrhotite ash releases heavy metals in aqueous medium. However, the concentration of these is very low compared to the limits estimated by the Dutch standard adapted to the Moroccan hydrological context (MBMD), this result encouraged us to find a way to valorise this waste and to make it a raw material for the manufacture of terracotta bricks made of clay.

Towards the Use of Yellow Clay in Fired Bricks

“…Pyrrhotite ash was chosen to this end. It is a mineral waste that was studied and valorized for the first time in our previous work [19,21]. The physicochemical characterization of the pyrrhotite ash showed that it is a mineral waste rich in hematite, silica and alumina.…”

“…So the material fills the volume more compactly [19]. Another work dedicated to the study of the behavior of pyrrhotite ash towards the environment has been published [21].…”

“…Among the ash waste category, there is another industrial waste, rich in hematite Fe 2 O 3 , which is the pyrrhotite ash. Few studies were carried out for this waste to explore areas of its recovery in industry [18][19][20][21][22]. It was generated between 1964 and 1982 [1] by the sulfuric acid manufacturing process from the combustion of pyrrhotite ore extracted from the Kettara mine in Marrakech (Morocco).…”