The magnesium sulfite is an inorganic metal compound that is an intermediate product of the magnesium oxide flue gas desulfurization process. It can be further oxidized to produce magnesium sulfate crystals, calcined to recover sulfur dioxide and magnesium oxide, and can also be used to process plant fiber raw materials and produce pulp.

To optimize and control the above process, it is necessary to conduct experimental research using high-purity magnesium sulfite samples. However, due to the high oxidation rate of magnesium sulfite to magnesium sulfate, it may undergo spoilage during its production process, and many factors affect its oxidation rate.

At present, the known preparation of high-purity magnesium sulfite is based on its insoluble nature. By introducing sulfur dioxide gas into the aqueous solution of magnesium oxide, a suspension of magnesium sulfite can be obtained. The main component of the filtered residue is magnesium sulfite.

However, the actual operation process of this method is complex, and the resulting magnesium sulfite sample has a high moisture content, making it difficult to transport and store. In the preparation of magnesium sulfite on a larger scale, the magnesium oxide flue gas desulfurization process can be used to react magnesium hydroxide slurry with sulfur dioxide in the flue gas, and then coagulate and precipitate the formed desulfurization slurry for solid-liquid separation to obtain magnesium sulfite crystals.

During this process, it is necessary to simultaneously place an oxidation inhibitor in the desulfurization tower to consume the oxygen in the flue gas, thereby avoiding the oxidation of magnesium sulfite into magnesium sulfate. However, due to the complex composition of flue gas, impurities such as fine fly ash and inhibitors are easily mixed into magnesium sulfite precipitation. At the same time, the water content of magnesium sulfite obtained by solid-liquid separation is high, so the purity of magnesium sulfite obtained by this method is not high.