Conversion of cleaned Oltu-stone wastes (a semi-precious stone) into a valuable product using binderless agglomeration

Abstract

Oltu-stone, a semi-precious stone found in Erzurum's Oltu area, is commonly utilized in the creation of decorative ornaments. More than 90% of the Oltu-stone mined is classified as Oltu-stone waste, consisting of poor Oltu-stone due to mineral impurities and small fragment sizes (OW). This waste is thrown or burnt, resulting in financial losses. Such losses might be reduced by using Oltu-stone waste (OW) instead of standard Oltu-stone (SO). The purpose of this study was to convert Oltu-stone waste into a useful pressed product. It was cleaned using the float-sink method with a density of 1.25 g.cm-3 and then utilized for binderless high-pressure agglomeration to create pressed Oltu-stone. The physical, mechanical, microscopic, and spectroscopic characteristics of the material were investigated. The bulk density of pressed Oltu-stone was reported to be 1.22-1.26 g.cm-3. However, with the same pressing time, indirect tensile strength was identical and varied when the pressing time was changed. The surface morphology of the crushed Oltu-stone revealed that it was more intact and had a less porous structure. Oltu-stone includes a lot of volatile matter and aliphatic carbon structures because of its high liptinite content. An FTIR investigation revealed that altering the pressing time affects the chemical structure but not the pressure. This effect was seen in molecules containing oxygen, namely conjugated carbonyl and carboxylic groups. It was discovered that pressed Oltu-stone has nearly identical properties to standard Oltu-stone and could be produced on a large scale commercially.