The unwanted iron ions in the lixivium were removed with ethylenediamine tetra acetic acid (EDTA) and other soluble impurities were stripped by washing with distilled water. Lastly the purity of the alumina product is excess 99.6 percent.

• 此外；实验采用络合滴定法；以乙二胺四乙酸(EDTA)为络合剂有效除去其中的杂质铁；用蒸馏水洗涤除去钠和其它可溶性杂质；得到纯度高于99.；6%25的氧化铝粉体。