Dynamic Hardness of Charcoal Varies According to the Final Temperature of Carbonization

Abstract

Hardness has been considered to be one of the most important mechanical indicators of material quality. Here, an automated portable hardness tester was used to evaluate dynamic hardness (DH) of vegetable charcoal for industrial application, correlating these results to vegetal material and final temperature of carbonization. Wood specimens from nine vegetal materials were pyrolysed at final temperatures of 300, 450, 600, and 750 °C. A total of 45 wood specimens were used as the sample control. DH of wood and charcoal was determined by an automated portable hardness tester. Wood specimen DH varied from 12.9 to 44 MPa. Wood density (ρ) presented a high positive correlation (r = 0.94) with wood DH. The heavier wood species (ρ = 988.6 kg m–3) is on average 1.93 times denser than the lighter wood (ρ = 512 kg m–3), while the harder wood (DH = 44 MPa) is 3.41 times harder than the softer material (DH = 12.9 MPa). Charcoal specimen DH significantly varies with the final temperature of carbonization: DH was 10.89 MPa for charcoal specimens produced at 300 °C, 3.05 MPa for charcoal produced at 450 °C, 3.44 MPa for charcoal produced at 600 °C, and 4.59 MPa for charcoal produced at 750 °C. Hardness variation between vegetal materials also decreases with the final temperature of carbonization. These findings are important, especially for industries that use the Eucalyptus charcoal as a reducing agent and supporting material in blast furnaces for producing “green steel”. In this industrial segment, a homogeneous product is necessary and the control of the characteristics of the raw material becomes essential.

Influence of Feedstock and Final Pyrolysis Temperature on Breaking Strength and Dust Production of Wood-Derived Biochars

“…Nevertheless, the analyzed feedstocks have different bulk densities, which could also play a key role in determining the impact resistance and shear strength of HO-derived. This is in line with the results reported by Kumar et al [37] and de Abreu Neto et al [43], who observed a positive correlation between hardness and apparent density of wood chars. However, Dias Júnior et al [38], in view on their breaking strength measurements for several charcoals produced at different pyrolysis temperatures, suggested that the apparent density of charcoal by itself was not a suitable indicator of its mechanical resistance.…”

“…Morphological characterization was carried out for three samples (i.e., three different pyrolysis runs) of each type of biochar (or treatment). 10% in weight of the coarse fraction (>2 mm length) was sampled fragment (resulting in 368 and 172 fragments for VS and HO-derived biochars, respectively) and the following measures were performed: length and diameter (digital caliper Twin-Cal IP40, TESA, Renens, Switzerland), mass (precision balance cp224s-Oce, Sartorius, Goettingen, Germany), volume (by displacement of water in a graduate tube [43]), and bulk density of each individual fragment as a quotient between the two latter parameters. The shape coefficient was calculated as the quotient between the measured diameter of each fragment and the equivalent diameter (diameter of a cylinder with equivalent volume).…”

“…Several studies showed clear correlations between the properties of the parent material used as biochar feedstock and the mechanical behavior of biochar [40][41][42][43]. Furthermore, relying on previous studies, pyrolysis operating conditions play a significant role in the final product behavior, with a general trend of increasing the material resistance with final pyrolysis temperature [37,41,42,44].…”

Exploring the potential of the Tachigali vulgaris wood from an experimental planting for producing charcoal in the Eastern Amazonia

“…In addition, lower SCF indicates a smaller volume of wood to be stored and transported in the industry and better use of the volume of carbonization kilns, reducing operational costs. In this study, even in the narrowest spacings, the SCF tends to be higher, which is probably related to the WBD they presented, since the WBD positively affects the CAD and its CGY, and denser wood would be consumed more slowly during pyrolysis [21,32] A signi cant effect of forking on SCF also occurred. Forked trees had higher SCF (6.0 of wood ton − 1 of charcoal) compared to the non-forked trees (5.5 m 3 of wood ton − 1 of charcoal) (Fig.…”

“…S1 (Supplementary material) shows the variation in FCP with basic density. Temperature stands out as the primary parameter in uencing carbonization yields [32,33], potentially elucidating why the CGY, PLY, NCGY, and FCY of T. vulgaris wood, subjected to identical heating rates and nal temperatures, exhibited no statistically signi cant differences.…”