Determination of mineral phosphate species in sedimentary phosphate rock in Mardin, SE Anatolia, Turkey by sequential extraction

Abstract

The importance of the effect of phosphate rock depends on the chemical form of phosphorus in which this element is combined. The paper presents the results of inorganic and organic forms of phosphorus in the phosphate rock from Mazidag-Derik, Semikan deposit located at Mardin city at SE Anatolia of Turkey. Total phosphorus concentration in the rock is an average 18.5%. The inorganic phosphorus mean % contents were 99.98% for studied sedimentary phosphate rock. Speciation of inorganic phosphorus was carried out using a method based on sequential extractions of the sedimentary phosphate rock each releasing four forms of inorganic phosphorus: loosely sorbed phosphorus, phosphorus bound to aluminium (P–Al), phosphorus bound to calcium (P–Ca) and phosphorus bound to iron (P–Fe). Calcium bound phosphorus is the dominant form of inorganic phosphorus in the studied sedimentary phosphate rock. Aluminium bound phosphorus is the second, iron bound phosphorus is the third most prevailing form. Loosely bound phosphorus is present in the lowest amounts. Analyses of phosphorus forms in sedimentary phosphate rock using a UV spectrophotometric method and ICP-AES are reported here. For the phosphorus the two methods give the same results and the concentrations are in good agreement with the reference values.