Abstract： In order to explore the practicability of acid soluble (aqua regia) - EDTA complexometric titration method for the determination of calcium oxide in limestone, a large number of samples from different batches of limestone ore for cement in mashantou mining area of Xiao county were selected. Under the condition that it is not required to determine silicon dioxide, aqua regia - EDTA complexometric titration method and alkali melting - EDTA complexometric titration method were used for comparison. The results show that the results of calcium oxide determined by aqua regia decomposition are consistent with those determined by alkali fusion, and both meet the requirements of dz/t0130-2006 quality management specification for geological and mineral laboratory testing. Through a large number of experiments, it is verified that aqua regia has fast decomposition speed and low cost. Especially for samples with calcium oxide content below 40%, the mutation of titration end point is more decisive. It is suitable for the determination of calcium oxide and magnesium oxide in large quantities of limestone (magnesium oxide titration is not included in this discussion). It provides timely and reliable analysis data for geological prospecting and plays a positive guiding role in production and operation.
