How a waste product is turned into a vital growth booster for crops With the global population heading towards 10 billion by 2050 and urbanization eating away at farmland, a significant rise in agricultural productivity will be needed to feed the planet in the future. As plant growth is largely dependent on the soil’s nutrient content, fertilizers play a key role. A new process developed at thyssenkrupp by Dr. Jens Mathiak and his team enables premium granulation of ammonium sulfate, a key component of nitrogen fertilizers.
By simultaneously supplying sulfate and nitrogen, ammonium sulfate boosts crop growth and yields. It also guarantees a long-lasting supply of nutrients and promotes the transfer of micronutrients, such as manganese, iron, and boron, from the soil to the plants. “There is a worldwide demand for granular ammonium sulfate, which very few manufacturers currently make,” explains Dr. Jens Mathiak, whose team has invested years of energy and innovative thinking to develop this new premium process. “We want to give fertilizer manufacturers the opportunity to convert an industrial by-product into high-quality nitrogen fertilizers.” The key benefits of granular ammonium sulfate as opposed to liquid or crystalline solutions are its improved storage, spreading, and mixing qualities.
Round, very hard, and resistant to impact and abrasion
The patented thyssenkrupp process starts with ammonium sulfate solution, an industrial by-product occurring mainly in the production of caprolactam and coal oven gas. An additive is mixed into the solution to reduce dust formation during granulation and give the end product high crushing strength. Then the liquid mixture is sprayed into a fluidized bed granulator and processed into solid granules, which are screened so that oversized pieces can be crushed and returned to the granulator along with any undersized particles. The resultant granules are round, very hard, and resistant to impact and abrasion.
Right now, ammonium sulfate is mostly sold in crystalline form, which is difficult to incorporate into granulated fertilizer blends. Moreover, as conventional granulation plants are unable to process ammonium sulfate solutions, they require more expensive ammonia and sulfuric acid as starting materials. Following successful lab and bench-scale tests, thyssenkrupp built a pilot plant in 2016 with an initial capacity of 500 kg per hour. “As all the tests have also been successful here, we are upping the process to industrial scale with capacities of 5–20 metric tons per hour,” Dr. Mathiak says. “Fertilizer manufacturers worldwide will benefit from improved cost efficiency.” The beneficial effects will not only be felt along the entire value chain. Ultimately, such an inexpensive premium process can help to extend the availability of fertilizers in the world’s poorer food-producing regions where soils are undernourished. And that way, this innovation can help feed a global population that is growing fastest in the poorest countries.