How do I calculate the cost of using thiourea dioxide?

Direct answer

Never compare replacement cost by price per kilogram. Compare total chemical cost per tonne of fabric (or per oven-dry tonne of pulp): cost per tonne = reducing agent dose x unit price + alkali dose x unit price + changes in utilities and labour.

1. Six inputs you need

2. Worked example (polyester reduction clearing)

• Current route: 4 kg x 1.20 = US$4.80 per tonne
• Alternative: 1.3 kg x 2.00 = US$2.60 per tonne
• Saving on the reducing agent: about 46%

Even though thiourea dioxide costs 67% more per kilogram, the cost per tonne is lower - because the dose is roughly one third.

3. Do not forget

1. Alkali cost may rise: thiourea dioxide needs adequate alkali to activate, and caustic soda cannot be cut in step

2. Indirect costs fall: no temperature- and humidity-controlled store, no restriction on loading in rain, no sulphur dioxide in the workshop

3. Quality cost falls: better reproducibility means fewer reworks, and one full batch rework usually costs more than a year of chemical savings

4. Effluent treatment: decomposition gives urea and sodium sulphate with no heavy metals, but the urea carries a total-nitrogen load

4. When the advantage does not hold

• Deep-shade stripping needs a hydrosulfite blend, diluting the benefit
• A large rise in alkali consumption offsets the saving
• The existing process already uses very little, so the gap is small

5. Conclusion

Convert at one third first, then calculate cost per tonne. Comparing unit prices alone reverses the answer.

Sources

Prices are illustrative; substitution ratios follow our technical data sheet (about one third for stripping).