Can Thiourea Dioxide Reduce the Chemical Consumption?

Direct Answer

Direct Answer Physical consumption of the reducing agent does fall, but chemical consumption has to be read on two separate measures, and mixing them leads to the opposite conclusion.

Measure 1: the reducing agent itself

According to our technical data sheet, stripping uses about one third of the sodium dithionite weight. Consumption, packaging, warehousing and freight all fall with it.

Measure 2: the whole chemical package

Thiourea dioxide needs enough alkali to activate, and caustic soda consumption does not necessarily fall. If a blended recipe is used during the transition, the hydrosulfite share still has to be counted.

Calculate per tonne of fabric

Example: assume sodium hydrosulfite at US$1.20/kg and thiourea dioxide at US$2.00/kg. A mill currently uses 4 kg hydrosulfite per tonne of fabric, that is 4 x 1.20 = US$4.80/tonne. If about 1.3 kg of thiourea dioxide achieves the same result, that is about 1.3 x 2.00 = US$2.60/tonne, a clear reduction in chemical cost per tonne.

• Cost per tonne = reducing agent dose x unit price + alkali dose x unit price + changes in utilities and labour
• Effluent treatment cost belongs in the calculation too: thiourea dioxide decomposes to urea and sodium sulphate, contains no heavy metals, but the urea carries a total-nitrogen load

Bottom line

Physical consumption certainly falls. Whether money is saved depends on alkali demand and how much the process has to be re-tuned, so it must be calculated per tonne of fabric.

Sources

1. 我司产品技术数据表《THIOUREA DIOXIDE Technical Data Sheet》（TDO-TDS，签发日期 2024-05-08）
2. US5958184A, Process for producing thiourea dioxide（还原当量质量比、碱中水解式、木浆与脱墨浆等当量漂白实施例），https://patents.google.com/patent/US5958184A/en
3. Effective reduction clearing parameters involving alternative reducing agent（2021），DOI 10.54693/piche.04916