Multi-nutrient fertilizer with core-layer structure

A key advantage of a multi-nutrient composite fertiliser is that it can often be applied to crops in a single spreading operation.

In April 2024, Anglo American Woodsmith Limited was granted UK patent GB2620718B titled Composite fertiliser pellet. The patent covers a method for manufacturing a fertiliser pellet.

With reference to the illustrated example, the method of manufacturing a fertiliser pellet (1) comprises forming a core (2) comprising a first fertiliser composition of polyhalite and a second fertiliser composition that provides a first micronutrient. The method then includes coating the exterior of the core (2) in a layer (3). The layer (3) comprises a third fertiliser composition that provides a second micronutrient. The fertiliser pellet comprises at least 0.03 wt. % of the first micronutrient.

Each fertiliser pellet therefore comprises a core which includes two fertiliser compositions over which is a layer that includes a third fertiliser composition.

In effect, the patented method provides a fertiliser pellet that has polyhalite in combination with two other fertiliser compositions, each of which are sources for micronutrients; the first micronutrient is from the core, and the second micronutrient is from the outer layer.

According to the patent, the fertiliser pellets can be applied to crops, seedbeds, or similar areas to serve as a plant fertiliser.

The core may be formed by processing raw or chipped polyhalite to form polyhalite powder – for example, using high pressure grinding roller equipment, or a ball mill and optionally, by adding water and a binder to the polyhalite powder, and drying the core to remove the water thereafter.

When forming the core, the polyhalite powder or the pellets of polyhalite powder and binder mixture may undergo a screening process – for example, using a 500 µm screen to filter the powder size.

When coating the exterior of the core, the method may include tumbling the core with the second micronutrient powder or applying the core and the second micronutrient powder to a pan pelletiser. At this stage, the core coated in the layer may again undergo a screening process.

The fertiliser pellet produced via the patented method – with its core and outer layer structure – may offer a readily spreadable fertiliser product that delivers multiple nutrients efficiently.

This innovation could significantly benefit agricultural practices by enhancing nutrient delivery to crops and plants.

Read the full patent here.

In an earlier post on The Patent Eye blog – we summarised a patent titled Seed coating comprising polyhalite, GB2525511B granted to Sirius Minerals plc. Read more here – Potash pit to coated pip. This patent discloses a coated seed product comprising at least one plant seed (1) having an exterior coating (2) wherein the coating comprises one or more evaporate minerals, such as polyhalite.

In March 2020, Sirius Minerals plc was acquired by Anglo American Woodsmith Limited. As a result, Sirius Minerals plc became wholly owned by Anglo American plc, which has since taken over the Woodsmith Project.

This project involves developing the world’s largest and highest-grade polyhalite deposit, leveraging the ore’s unique multi-nutrient properties to produce a new multi-nutrient fertiliser [1].

References:

[1] The polyhalite deposit – https://siriusminerals.com/our-project/the-deposit/