# Inorganic Waste Generated in Kraft Pulp Mills:
## 3 Main Properties of the Inorganic Wastes
### Physico-chemical properties
This property is particularly important for assessing the potential applications as a liming agent of soil or as neutralization material for acid wastewaters or in alkaline barriers. All of those materials are generated in granular form. BFA shows, in general, a coarser particle size distribution, while GLD is a very fine powder with a mean particle size of a few micrometers [29]. Some of them are generated in agglomerates (SG and LM) but could be easily disintegrated if required. Thus, the bulk density is lower or close to 1 g/cm\({}^{3}\), whereas the real (or skeletal) density may reach values higher than 2.4 g/cm\({}^{3}\) for all of those wastes. Indeed, for instance for GLD, although the bulk density ranges between 0.44 and 0.67 g/cm\({}^{3}\), the real density may achieve from 2.47 to 2.60 g/cm\({}^{3}\)[37]. The specific surface area, Sa, may vary within each waste, but expected values are from a few m\({}^{2}\)/g to about 100 m\({}^{2}\)/g. For using these materials in geotechnical applications such as sealing layer for water and oxygen, the hydraulic conductivity is a relevant property. This parameter has not been \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Property** & **GLD** & **SG** & **LM** & **BFA** \\ \hline Moisture (\%) & 50.8 [36]: 48.0–57.0 [17] & 157 [36]: 28.4 [19], & 41.1 [38], 1.1–45,6 & \\  & 54.0 [37] & 7.0–16.0 [17], & [17], 28.0 [39], & 0.30–0.80 [40] \\ pH & 12.8 [36]: 12.2 [25]: 12.9 [4] & 13.1 [36]: 12.6 [25], & 12.6 [41] & 11 [32]: 12.8 [42]: 13.3 [43] \\ EC (mS(cm) & 26.2 [36]: 9.76 [4] & 20.8 [36]: 9.4 [39] & 7.3 [41] & 13.6 [42]: 11.63 [43] \\ VS (\% TS) & 8.3 [36] & 2 [41] & & \\ ANC (\% CaCO) & 64.4–95.6 [25]: 8.3 mmol & 69.4–100 [25] & 106 [41] & 54.3–77.7 [25] \\ H+/g [4] & & & & \\ D50 (um) & 11.6 [24]: 8.97 [4]: 6 [29] & 24.1 [24] & & 49.3 [5]: 150–250 [32] \\ Density (g/cm\({}^{3}\)) & 2.498 [24]: 24.7–26.0 [37] & 2.703 [24] & 2.83 [44], 2.43 [39] & 2.4–2.8 [32], 2.615 [23] \\ Bulk density (g/cm\({}^{3}\)) & 1.2–1.64 [4], 0.4–0.67 [37] & & & 0.15–1.3 [32] \\ Sa (m\({}^{2}\)/g) & 72.08 [24]: 12–21 [37] & 2.901 [24] & 5.17 [44] & 3.03 [5]: 42–101 [32], \\ HC (m/s) & \(8.8\times 10^{-9}-1\times 10^{-8}\)[4] & & & 3.25 [32] \\ Kjeldahl N (\%) & 0.07 [25] & 0.05 [25] & & 0.17 [25] \\ Chlorides (\%) & 0.30 [29]: 0.8 [36] & 0.1 [12]: 0.02 [19]: & 0.08 [44]: \(\text{CLO}\)[45]: & 1.5 [29]: 2.7 [23]: 1.2 [45]: \\  & & 0.1 [36] & 0.06 [46] & 1.2 [43]: 0.10 [46] \\ \hline \hline \multicolumn{4}{l}{EC–electrical conductivity; VS–volatile solids; ANC–acid neutralization capacity; D\({}_{50}\)–median size; Sa–specific area; HC–hydraulic conductivity.} \\ \end{tabular}
\end{table} 
Table 4: Other relevant physicochemical properties to select technological applications. reported much in the literature. Nevertheless, the hydraulic conductivity measured for GLD vary from \(3.7\times 10^{-9}\)-\(4.6\times 10^{-8}\) m/s, which is a low value and similar to those of silt or muddy moraine [4]. It is important to note that these wastes are definitely not nitrogen sources (Kjeldahl N less than 0.05%). The content of chlorides could limit specific applications, namely for clinker production or in concrete and mortar applications. Data from the literature shows that the content of chlorides in GLD, SG, and LM is normally low, whilst BFA can contain a slightly higher amount.