Agripower Australia Limited operates mining and processing facilities in the north of Queensland in Australia. The company has one of the world's largest deposits of diatomaceous earth – with more than one billion tons ready to be mined in the opencast mine. The most important market for this substance is its use as a silicon fertilizer and soil improver. For this purpose, the diatomaceous earth is transformed to granules. Agripower decided to opt for mixing and granulating technology from EIRICH.
Immediately after it was founded around ten years ago, the company Agripower started to systematically investigate the potential uses of diatomaceous earth. Use as a soil improver brought particularly promising results. An initial pilot production of approx. 130,000 tons per year commenced in 2013. Based on the excellent response from the market, there are now plans to expand the annual production capacity to up to one million tons in various systematic stages.
The natural raw material diatomaceous earth, which is also known as diatomite or kieselguhr, is a whitish, powdery substance that consists of the shells of fossil diatoms. These diatoms are an important part of the plant-based plankton in oceans and inland waters. They represent more than one fifth of the biomass produced via photosynthesis. The cell walls of the algae consist primarily of amorphous mono-silicic acid. These freshwater algae were found in huge inland lakes in the Eocene and Miocene periods many millions of years ago. At that time, the dying algae formed layers of sediment deposits that were as much as several tens of meters thick.
The diatomaceous earth that is mined in Australia is characterized by a uniquely high Cation Exchange Capacity, Plant Available Silicon (PAS) and Water Holding Capacity. As a soil improver, it can noticeably improve water and nutrient retention in various soil types. In hundreds of domestic and international field trials, Agripower has shown that this amorphous silicic acid offers a wide range of beneficial effects for plants and soils.
By mixing in NPK mineral fertilizers, the yield and quality of harvests can be significantly increased. Not only this, but the amount of the NPK fertilizer needed is reduced to obtain better yields and the plants also become more resistant to problems like dryness, pests and diseases. The silicic acid products that are available for plants are marketed by Agripower under the name Agrisilica as soil improvers.
As is known, the machines used to deliver soil improvers require granulated product. However, with its low density and an extremely porous structure, the raw material diatomaceous earth can only be transformed with great difficulty into a mechanically derived granule. One cubic centimeter of diatomaceous earth contains more than a million diatom shells and their fragments. When it came to dealing with this special challenge, the customer was able to rely on the expertise and know-how that has been accrued by EIRICH over the course of more than a century in relation to the processing of such materials.
After extensive tests at the EIRICH test center, Agripower was more than satisfied with the results. In particular, the originally assumed content of up to six percent binding agents was reduced to zero thanks to research and development and also intelligent process engineering optimizations. At the forecast production scale, this will lead to yearly savings of millions of dollars.
For the planned production expansion, the latest design of mixer of type R33-72 (with an inclined mixing pan, seven cubic meters of usable capacity) with two downstream disk pelletizers (with a diameter of 4.5 m) will now be installed. Most of the granulating process already takes place in the mixer, while the disk pelletizers perform the finishing of the granulates and narrow the spread of grain sizes to within the required range.
The commissioning of the plant is scheduled for 2019. Further production lines of this type are due to follow over the coming years.
Contact: Oliver Zeitner, e-mail: firstname.lastname@example.org