The Recovery Of Heavy Soda Ash Purge


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2016

Student: FATİH FURKAN YILMAZ

Supervisor: ÖZKAN MURAT DOĞAN

Abstract:

In this study, the possibility of recovery of waste purge stream of Eti Soda Inc. which includes valuable sodium carbonate minerals is examined. The stream includes several impurities but the major impurities assumed as sodium chloride. The main purpose of the study is to seperate sodium chloride impurities from sodium carbonate minerals in the waste stream which can be used in several points in the facility and also can be marketed. The facility has its own seperation system and in this system sodium carbonate minerals are crystallized as sodium carbonate decahydrate form. However, the waste purge stream again includes serious amount of sodium carbonate minerals as %18 mass percentage. During the crystallization process pressure, stream input temperature, crystallization tempereture and density parameters were adjusted and several experiments were conducted to obtain optimum crystallization condition. The pressure parameters were taken as two different input values which are 200 mbar and 1000 mbar. The facility's operating decahydrate crystallizator is conducted at 200 mbar that is why this parameter was selected. The feeding stream temperature was selected as 70-80-90°C, again, by considering the operating decahydrate crystallizator operation conditions. The waste stream density was increased to 1320-1365 kg/m3 because of the fact that waste stream was not crystallized as it is initial condition at 1256 kg/m3. The crystallization temperature was chosen according to the solubility curves of the sodium carbonate and it is hydrated. As a result of experiments, it is well understood that the waste purge stream can be seperated by crystallizing sodium carbonate minerals as in the decahydrate form. After that crystallization process, the seperated crystals can be mixed with fresh stream which is obtained by using solution mining techniques and pumped together through to the facility.