Date

2021-12-17

Author

Bawani, Muhammad Raheel

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Oltu-stone (Jet Stone), also known as black amber, is a fossilized, organic, and natural material formed by the transformation of certain trees under high pressure. It is called Oltu-stone because its occurrences are primarily located in the Oltu district of Erzurum. Generally, it is mined by small miners from nearby villages using rather primitive methods. After a rough sorting at the mine site, Oltu-stone is mainly used in manufacturing worry beads, tespih, and to a lesser extent, certain ornamental goods. It has been reported that only 2% of Oltu-stone mined is converted to sellable end products. The rest, the waste, is either burnt or disposed of, causing economic losses. On the other hand, a much cheaper product known as Russian Stone produced in Georgia replaced Oltu-stone. To protect the brand, Oltu-stone, and produce higher economic values from this stone, the wastes of Oltu-stone should be converted into products. First, the cleaned Oltu-stone wastes obtained from dense medium separation were characterized in this study. Cleaned Oltu-stone had nearly similar petrographical, physical and chemical properties coMPared to standard Oltu-stone. It was found that the cleaned Oltu-stone is liptinite-rich (including suberinite, resinite, and sporinite) coal with a small amount of huminite. Due to liptinite content, cleaned Oltu-stone has high volatile matters and aliphatic hydrocarbons. It is a well-known fact that this type of waste, especially amber, has been converted to sellable products by agglomeration under heat and pressure treatment. To produce such agglomerates from the Oltu-stone wastes by this method, first, the agglomeration parameters such as pre-heating time, pressure, and temperature were optimized. The cleaned Oltu-stone was successfully pressed without a binder at 450 MPa pressure with two-stage heating until 200 ˚C temperature. Compared to standard Oltu-stone, pressed Oltu-stones were nearly similar in bulk density (1.22-1.25 g.cm-3), indirect tensile strength (8-9 MPa), and nano-indentation hardness (Hv=464.6 MPa, E=5.2 GPa). But chemically, it was degraded, such as reducing volatile matters and losing conjugated carbonyl groups. The pressed Oltu-stone obtained from the binderless agglomeration of cleaned Oltu-stone waste was tested by ateliers in Oltu, the quality of the pressed Oltu-stone was found to be satisfactory.

Subject Keywords

Agglomeration, cleaned Oltu-stone waste, pressed Oltu-stone, liptinite, resinite

URI

https://hdl.handle.net/11511/95231

Collections

Graduate School of Natural and Applied Sciences, Thesis