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 to 2.5 ~ 4, and PTMS MAGNETIC SEPARATOR can produce bleaching reaction.
The reaction to form sodium dithionite is as follows: NaBH4+9NaOH+9SO2=4Na2S2O4+NaBO2+NaHSO3+6H2O
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. When the pH value is subsequently reduced, sodium disulfite reacts immediately with the iron oxide in the kaolin slurry, and the PTMS MAGNETIC SEPARATOR process is utilized in time, thus avoiding the decomposition loss of sodium disulfite.
If the trivalent iron in kaolin is reduced to divalent iron by sodium disulfite, the product will return to yellow if it is not filtered and washed immediately. The effective method of PTMS MAGNETIC SEPARATOR to solve this problem is to add complexing agent, so that the bivalent iron ions can be complexed and not easily oxidized. There are many agents that can be used to complex iron, including phosphoric acid, polyethylene alcohol, hydroxylamine, hydroxylamine salt, oxalic acid, polyphosphate, ethylenediamine acetate, citric acid, etc.
Contact: DELLA
Mob: +86-13929907491
Адрес : No.9, Factory 2, Shijin Industry Park, Shishan Town, Nanhai District, Foshan City, Guangdong, China
Тел. : +86 -13929907491
Эл. адрес : sales@ptmsmagnet.com
Веб-сайт : https://www.dellamagnet.com