Permanent magnet magnetic separator

In addition to sodium dithionite and zinc dithionite, the reducing agent commonly used in kaolin production is very unstable. The latter is much more stable. However, bleaching with zinc dithionite will make the concentration of zinc ions in the wastewater too high, causing pollution to the river water. For this purpose, sodium borohydride reduction method can be used to remove iron from PTMS magnetic separator. This method is actually bleaching by reacting sodium borohydride with other agents to produce sodium dithionite during the bleaching process. The specific process is:

PTMS magnetic separation

 
Under the condition of pH 7.0 ~ 10.0, a certain amount of sodium borohydride and NaOH are mixed with the pulp, and then SO2 gas is passed into the pulp. The pH value is adjusted between 6 and 7, which is conducive to the production of the maximum amount of sodium dithionite in the pulp. Then H2SO3 or SO2 is used to adjust the pH value to 2.5 ~ 4, at which time bleaching reaction can occur, which is conducive to the removal of iron by PTMS magnetic separator. The reaction to produce sodium dithionite is as follows:
NaBH4+9NaOH+9SO2=4Na2S2O4+NaBO2+NaHSO3+6H2O

what is magnetic separation used for？

The essence of this method is still sodium bisulfite plays a reducing bleaching role, but at pH6 ~ 7, the generated large amounts of sodium bisulfite are very stable. In the subsequent decrease of pH value, sodium disulfite immediately reacts with the iron oxide in the kaolin slurry, and is used in time, and the PTMS magnetic separator removes the iron, thus avoiding the decomposition loss of sodium disulfite.
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