X-ray analysis on iron ores and reduced iron powders revealed that the main acid-insoluble substances were hexagonal and tetragonal quartz, another substances were sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. Their particle size was in the range of . Statistics analysis showed that the AIC for high-grade magnetite powder was ) during the latest five months. The predicting value for reduced iron powder should be 0.179%. However, the testing value for reduced iron powder was . The limited difference of 0.013% might imply rare pollution coming from the reduction and milling processes. The most important step for control AIC should be the separation process of iron ore powders.

• Wang
• Chonglin
• Zhang
• Chunguang