Pelletizing of wheat straw: how to influence mechanical–physical properties

Abstract

Background: Herbaceous biomass, especially straw, has been taken into consideration as raw material for pelletizing. Because of low lignin content and a waxy plant cuticula, straw pellets show high abrasion and low bulk densities. Method: During experiments, the parameters of moisture content, particle size of raw material, concentrations of press aids and gap size between rolls and die were varied to determine their influence on mechanical–physical properties of the pellets. Results: With the help of small particle sizes (screen size = 2 mm) or press aid concentrations of 1 wt%, straw pellets can be produced that fulfil the Austrian standard for straw pellets as far as abrasion (<2.5 wt%) and bulk density (>600 kg/m³) are concerned. Furthermore, results show significant influence of moisture content and gap size on the pelletizing process.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.