GB/T 24221-2009 Determination of calcium and mg content in chromium ore by EDTA Titrimetric method. Suitable for all kinds of chromium ore samples. This method takes advantage of the characteristics that EDTA can form stable complexes with calcium and mg ions, and titrates calcium and mg ions respectively with EDTA standard solution by controlling the reaction conditions. The standard specifies the required instruments, such as Burette, etc., and specifies the preparation of reagents. Detailed description of Sample Handling steps, including ore dissolving and masking of interfering elements. Standardized titration operation procedures, such as titration speed, indicator use and end point judgment. According to this standard, the calcium and mg content in chromium ore can be accurately determined, providing key data support for chromium ore mass assessment and metallurgical process.