Bayer process of alumina production: to use NaOH solution to dissolve the bauxite and the alumina in the resulting sodium aluminate solution is separated as aluminium hydroxide under adding seeds or stirring continuously. The heat exchange equipment used in this process is as follows:
Pre-heater: to heat up the raw pulp to 90 ℃, removing the silicon from the pulp.
Condenser: to cool down the raw pulp after high-pressure dissolution, for pulp dilution.
Plate heat exchanger: to heat the refined sodium aluminate solution, separated to obtain more mother liquor.
Evaporator: to evaporate and condense the mother liquor generated in the whole process, which can be used to dissolve out new bauxite at high temperature and achieve the cycle collection of mother liquor.
Due to the sodium aluminate, sodium hydroxide, sodium carbonate, sodium silicate, and other substances in the pulp (such as nickel). At the same time, the recommended pre-heater and condenser should adopt the tube type to prevent the particles in the pulp and the adhesive silicon aluminium from blocking the machine.
The mother liquor may contain sodium, aluminium ions, silicon ions, calcium ions, magnesium ions, iron ions, titanium ions, sulfur ions, etc.