Abstract: When paigeite ores were used as raw materials to prepare borax， the ores must be calcined at first to enhance its activity.The purpose of high-temperature calcination process was to change the structure of ascharite，which could hardly be decomposed by carbonate decomposition process，into suanite，which can be decomposed much easier.Several methods of calcination of paigeite ores and ranges of calcinating temperature were introduced.It was pointed out that powder flash-calcinating process would have a good prospect because of its large production capacity of single unit，high mechanization degree，easy control of calcinating temperature and other production situation，and good and stable quality of calcined ore powder etc..The temperature range of ascharite transforming into suanite was at 620~800 ℃.The higher magnesium content in the ores，the wider and higher calcinating temperature range would be.The higher iron content in the ores would lead to a narrower and lower calcinating temperature range.For single phase of ludwigite，the current calcination methods could not change its structure.

Key words: ascharite, calcination, suanite, activity