Tessenderlo Kerley has ramped up production at its newly constructed Thio-Sul® plant within the Chemelot complex in Geleen, Netherlands.

The 130,000 t/y ammonium thiosulphate (ATS) plant is Tessenderlo Kerley’s third European production site for its ATS product Thio-Sul (12-0-0-26 S w/w), produced from the reaction of liquid ammonia and molten sulphur, which is pumped into the process.

Tessenderlo Kerley (TK) uses ammonia produced by OCI at the site at Geleen. Molten sulphur is brought in from European refineries. The reaction is exothermic and TK supplies steam to other manufacturers at the Chemelot complex. “We produce more energy than we need,” said Remo Kanders, TK’s Plant Manager at Geleen.

The intermediary product in the process is ammonium bisulphite, which has various applications. It can itself be applied as a fertilizer but is less common than ATS, and in the past was used widely in the developing process for print photographs.

The liquid Thio-Sul product is stored on-site in one of the two tanks, before being trucked to the Port of Chemelot at Stein, where it is barged north on the Juliana Canal which joins the River Maas (Meuse). Tonnes are taken onwards to Antwerp or Rotterdam. TK has additional storage at the inland terminal Cuijk, which lies on the Maas.

Construction of the new Thio-Sul plant began in 2022, and the first tonnes were produced in September this year, before the official opening on 21 November. TK held a conference and visitor day for its key customers and stakeholders on 11-12 December, which was attended by New AG International.

One of the large-volume uses for Thio-Sul is to be blended with UAN 32, UAN 30 or UAN 28, particularly in North America and European markets, as well as South America. When speaking about the agronomic benefits of the product, Régis Muteau, Lead Agronomy Manager, said that Thio-Sul was ‘a liquid by origin, it was born a liquid’. This was a reference to the development of the Thio-Sul product by the Kerley brothers in the USA during the 1950s. They took waste products from the refining process, creating sulphur-based liquid fertilizers that could be applied through irrigation equipment. The product offers the highest concentration of sulphur for a liquid fertilizer.

Double registration
Muteau described how Thio-Sul can also inhibit volatilization and nitrification. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES) officially recognised (homologated) Thio-Sul as a double inhibitor on 4 November 2024 (AMM: 1171327). Muteau said TK is working on the mutual recognition across the 27 member states of the European Union, as well as obtaining recognition in the United Kingdom and Australia.

Muteau made the point that the UAN and Thio-Sul need to be applied together for the Thio-Sul to work as an inhibitor. The optimum blending rate is between 10-25% of Thio-Sul to inhibit nitrification and volatilization. This slows the conversion of the ammonium to nitrates, retaining the ammonium for longer in the root zone, and lowering the risk of the nitrate leaching.

Complementing the discussion on inhibitors, Patrick Heffer, Deputy Director General International Fertilizer Association (IFA) gave a presentation on the latest estimates for inhibitor usage in fertilizer markets. He opened by detailing how nitrogen use efficiency has increased from around 40% in the 1980s to around 55% by 2022. He warned that to reach a global average of 70%, a consensus target approved by IFA’s board, the adoption rates need to increase from 0.4% per year in 1990-2022 to around 1.3% per year.

IFA estimates the global urease inhibitor market in 2023 to be approximately 8 million product tonnes, and 3 million product tonnes for the nitrification market.

Soil Health benefits
Muteau also described how Thio-Sul can improve soil health. The thiosulphate part of the fertilizer can stimulate microbes in the soil (thiobacillus bacteria), resulting in soil that is less compacted.
Writing for New AG International, Tessenderlo Kerley’s Portfolio and Knowledge Director Dr Nicolas White explained how the different forms of sulphur in a thiosulphate can be utilized to deliver sulphur to the crop over an extended period of time (see link below).

Expansion plans
The Geleen site is the third production site of Thio-Sul for TK in Europe. The first site outside the US was in Rouen, France, which began production in 2017. The second site is in Trecate in Italy, which is not a plant owned by TK but the company has the 100% off-take agreement. When discussing TK’s business strategy, Victor Soloukhin, Product Manager Nitrogen & Business Development Manager said a fourth European site was under consideration.

The Kerley business joined Tessenderlo in 1995. This gave Tessenderlo a liquid fertilizer business to build on its famous potassium sulphate (SOP) business. Tessenderlo is the world’s largest producer of water-soluble SOP and thiosulphates said Geert Gyselinck, Executive Vice President of Tessenderlo Kerley International, during his opening presentation.

“Thio-Sul® is really a unique product, because it is a fertilizer, bringing important nutrients to the crops, in a unique form, thiosulfates, and at the same time a double inhibitor that is preventing nitrogen losses through volatilization and nitrification. So it’s an important building block in farmers’ efforts to achieve maximum yields with minimal nitrogen losses, good for farmers, good for crops, good for the environment,” said Kathleen Dejaeghere, Marketing & Sales Director Europe told New AG International.

Tessenderlo Kerley’s main production site for SOP is approximately 60 km from Geleen, at Ham in Belgium.

For more on thiosulphate, read here from NOV/DEC 2024 issue of New AG International.