In contrast, both additives (kaolin and calcium hydroxide) analyzed
here, improve sinter behavior strongly when have been
added in 1 wt.% and 2 wt.% steps to the biomass. As far as calcium
hydroxide is concerned, there is a significant difference between
the 1 and 2 wt.% step: By doubling the proportion of calcium
hydroxide, sinter degree is halved. In contrast, no big differences
are found in samples with 1 and 2 wt.% kaolin, respectively. The
1 wt.% kaolin sample has even been assessed at a lower sinter degree
than the 2 wt.% sample. Thus, an addition of 1 wt.% kaolin
seems to be sufficient in reducing sintering; higher amounts do
not have an additional effect. Again, no big difference could be detected
by analyzing wood–straw pellets with 60 and 80 wt.% straw,
respectively.