GEOLOGY AND DEVELOPMENT OF THE KAZAN TRONA DEPOSIT, CENTRAL ANATOLIA, TURKEY

The Kazan trona deposit, situated 35km northwest of Ankara, was discovered in 1998 by Rio Tinto geologists, the first such deposit to be found as a result of commodity-specific exploration. 117 core holes totaling 43,600m have delineated >600 million tonnes (Mt) of ore grading 31% trona. 15 trona beds, collectively called the trona zone, have been discovered. Zone depth ranges from 420m to >850m, dipping 5º to 16º to the SE; thickness reaches a maximum of 109m, averaging 54m. The deposit covers 20km2 of areal extent.

Studies suggest that the deposit was formed in an Eocene playa lake environment. Two K-Ar radiomentric age dates made from ash fall tuffs yielded deposit ages of 45 and 46 Ma. The deposit is hosted within the informally named Mülk Fmtn that reaches a thickness of ~700m. Contained within are 3 principal members: An upper marlstone, a middle dolomitic mudstone and a lower oil shale that hosts trona mineralization.

Trona is refined to soda ash by means of dissolution and re-crystallization. Soda ash is one of the oldest known and largest volume inorganic chemicals produced and is used primarily in the manufacture of glass, chemicals, soap and detergents, pulp and paper and water treatment. Annual world consumption of ~35 Mt is supplied by 65 refineries operating in 27 countries. About 2/3's of all soda ash is made synthetically through the ammonia-soda (Solvay) process. Natural soda ash, made from conversion of Na2CO3 ores, comprises the balance and enjoys commercial and environmental advantage over synthetic product.

Solution mining is the preferred exploitation method as it minimizes the technical and environmental effects of the lower grade ore. Modeling suggests that solution mining will more than double soda ash recovery to 61 Mt of saleable product versus conventional mining. Conceptualized unit extraction consists of 2 vertical wells connected by a horizontal well that follows the mineralization base. High temperature and pressure water is pumped into the cavern from an injection well and pregnant solution is withdrawn from a collection well. Soda ash is produced by evaporation and crystallization. Over 500 horizontal well sets will be constructed over the life of the project. By size and economic value created, the project, if realized as envisaged, will be one of the largest natural resource projects in Turkey.