The invention provides a method for synergistically removing
oxalate and
carbonate in a
sodium aluminate solution, and belongs to the technical field of
metal smelting.
Oxalate is removed from
mother liquor to be subjected to
decarburization, so that the harmful influence of
oxalate crystallization is removed, and subsequent
filtration and causticization are facilitated; meanwhile, heat of the first filtrate and the second filtrate is recovered through the
heat exchanger, and
system energy loss is reduced; in addition, filtrate obtained by filtering the causticized
slurry is conveyed to a grader, so that the washing efficiency of the
red mud settling and washing procedure is not influenced, the internal circulation of the seed
precipitation mother liquor is reduced, and the utilization efficiency of alkali is improved; and finally, unreacted
calcium hydroxide in a third
filter cake obtained by separating causticized
slag after causticization and the refined
sodium aluminate solution are subjected to slurrying reaction to generate 3CaO. Al2O3. 6H2O with good
crystallinity, and the 3CaO. Al2O3. 6H2O is used as a filter aid with a good effect, so that the use amount of
lime milk can be saved, and the production cost is saved. In conclusion, the method saves raw materials, can be continuously operated, is high in operation efficiency and low in operation cost, and is beneficial to purifying the solution and improving the overall production efficiency.