ABSTRACT
Objective To understand the stability of iodine content in potassium iodide iodized salt and potassium iodate iodized salt during production.Methods The sodium sulfate type brine well rock salt and calcium salt brine well rock salt as raw material were used to produce potassium iodide salt and potassium iodate salt by different iodization methods of before and after fluid bed dryer and then the loss of iodine during production was measured,meanwhile iodine content of powder salt was determined.According to the "Belt Delivery Sampling of Sampling Methods of the Main Products in the Salt Industry" (GB/T 8616-2001),25 standard salt samples and 6-24 powder salt samples were collected in the same batch.The salt iodine content was determined by oxidationreduction titration and direct titration of the "General Test Method in Salt Industry-Determination of Iodine" (GB/T 13025.7-2012).Results For the sodium sulfate type brine well rock salt,there was no statistical difference in iodine loss rate between potassium iodide salt and potassium iodate salt (16.55％ vs.19.60％,x2 =0.01,P ＞ 0.05) by iodization of before fluid bed dryer.The iodine loss rate of potassium iodide salt was 2.17％ and the iodine loss of potassium iodate salt was undetectable and there was no statistical difference between the two (x2 =2.19,P ＞ 0.05)by iodization of after fluid bed dryer.For calcium salt brine well rock salt,the iodine loss rate of potassium iodide was less than that of potassium iodate (20.60％ vs.39.75％,x2 =8.70,P ＜ 0.05) by iodization of before fluid bed dryer and neither of them was lost by iodization of after fluid bed dryer.Conclusions For both sodium sulfate type brine well rock salt and calcium salt brine well rock salt,the iodine loss of iodide iodized salt is not higher than that of potassium iodate during iodization of before or after fluid bed dryer.Since the iodine loss during iodization of before fluid bed dryer is significantly higher than that after fluid bed dryer,adopting iodization of after fluid bed dryer to produce iodized salt should be recommended.