Abstract: The massive accumulation of bischofite produced after extracting potassium and soduim from salt lake has become
a key constraint on the development of salt lakes. In this study,light-burned magnesium oxide (MgO) was prepared via a
two-step method using bischofite from salt lake brine as the raw material. The effects of light-burning process parameters on the
activity of the prepared light-burned MgO were systematically investigated. The results showed that the magnesium hydroxide
(Mg(OH)2) prepared with calcium oxide and ammonium chloride as precipitants had high purity (99. 17%) and a dense,
regular structure,making it suitable as a precursor for MgO preparation. At a fixed temperature,prolonging the light-burning
time promoted crystal perfection and reduced lattice defects,while leading to a decrease in grain size and structural densification.
Light-burning temperature was identified as the primary factor affecting MgO activity,with the highest activity achieved at
500 ℃. MgO activity exhibited a negative correlation with grain size;Excessively low or high temperatures resulted in reduced
activity due to poor grain growth. The activity of MgO decreased moderately when the grain size ranged from 50 nm to 70 nm,
but declined sharply when the grain size increased from 70 nm to 100 nm. The MgO prepared using the Mg(OH)2 precursor
(with calcium oxide and ammonium chloride as precipitants) under the conditions of 500 ℃ and a calcination time of 2 hours
showed excellent activity,with a citric acid activity (CAA) value of 95 seconds. This study provides reference process parameters
for the preparation of activated MgO from bischofite and holds great significance for the utilization of waste magnesium resources in salt lakes.