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Table 3 Proposed practices for salt-iodation at different scales of salt production

From: Improved salt iodation methods for small-scale salt producers in low-resource settings in Tanzania

Practice Large scale salt producer Medium scale salt producer Small scale salt producer
Quantity to iodate Above 100 tons/day 1 – 100 tons/day Below 1000 kgs/day
Type of iodating equipment/utensils Conventional salt iodating machines Knapsack sprayers with slit nozzles Knapsacks if externally provided, otherwise 1 – 2 litre hand bottle sprayers
Iodation procedure Machine calibrated spraying with automated mixing of salt Hand pump spraying with manual shovel mixing or cement mixer Hand pump spraying with manual mixing on mat
Amount of KIO3 used 76.5 g/ton 20 litres of solution (10 g/l) to iodate an average heap (2.5 tons) Solution of 20 g in 2 litres to iodate an average of five 50 kg bags
Frequency of spraying to achieve recommended levels Machine calibrated and controlled 2 – 4 times with manual mixing and 2 – 3 times with concrete mixer 4 – 5 times with hand bottle sprayers and manual mixing on mat
Homogeneity Excellent Good Fairly good
Quality control Laboratory control (both RTK and titration methods) Laboratory control (both RTK and titration methods) Semi quantitative method (RTK)
Frequency of internal quality control to determine magnitude of iodine variability* Periodic validation of iodation processing and batch to batch iodine testing Daily/periodic validation of iodation processing and batch to batch iodine testing Daily validation of iodation processing and batch to batch iodine testing
  1. NB * acceptable magnitude of variability is when the variation of the iodine content of all samples within and between batch(es) is less than 2% from the target value (e.g., 100 ppm) and the relative standard deviation (RSD) is equal to or less than 3%, then the potassium iodate/salt mixing is considered homogeneous [24].
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