Provided is a method for preparing high-purity
magnesium oxide with high
boron salt lake brine.
Salt lake brine is evaporated through a
salt pan, concentrated to crystallize
potassium sulfate,
sodium chloride and
potassium chloride and is drawn with
lithium in adsorption mode so as to obtain master sauce brine containing
magnesium and
boron. Concentrated
sulfuric acid is added into master sauce brine for reacting, and coarse boracic acid and acidized brine are obtained after cooling and filtering. Potential of
hydrogen (pH) value of acidized brine is adjusted to be 5.5-6.5, and acidized brine passes through
ion exchange resin adsorbing
boron. When
boron concentration in
effluent liquid is higher than 5 mg / L, brine is not injected, boron-removed brine is obtained, then boron-removed brine and
ammonium chloride solution are filled with
ammonia for stirring and to produce
magnesium sedimentation reaction,
reaction temperature ranges from 60 DEG C to 80 DEG C, pH ranges from 7.5 to 8.0, the reaction is stopped when concentration of free
ammonia reaches 1.8-2.2 mol / L, and magnesium
hydroxide and magnesium
sedimentation mother solution are obtained.
Magnesium oxide is obtained by calcining magnesium
hydroxide, content of magnesium
oxide is larger than 99.8%, and magnesium
extraction ratio is larger than 90%.
Sedimentation mother solution adopts
lime to steam
ammonia, and generated ammonia circulates to magnesium
sedimentation reaction. Mother solution after ammonia
steaming is evaporated, concentrated and crystallized to obtain
calcium chloride.
Ion exchange resin adsorbing boron is washed, analyzed and regeneratively cycled for use.
Boron-containing analysis solution is concentrated and cooled to pick up coarse boracic acid, and coarse boracic acid is recrystallized to obtain refined boracic acid with purity larger than 99%. High-purity magnesium oxide prepared by the method is high in purity, good in economic benefit, free of environment
pollution, strong in
operability and favorable for industrial production.