# Inorganic Waste Generated in Kraft Pulp Mills:
## 4 Potential Applications
### Lime Mud  
LM has also attracted attention to develop novel management strategies and expand the applications available for reuse. Table 8 presents a list of studies reported in the literature and their main highlights. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Application** & **Highlights** & **Scale** \\ \hline Construction materials & & \\ \hline
**Geopolymer mortars** & Efficient reuse as aggregates with the best mechanical resistance achieved using a binder-aggregate ratio of 1 to 5, belonging to at least class M10 (UCS \(\geq\)10 MPa) [5]. Mortars prepared with belite-based cement (CEM II A-L) using 16 wt \% of LM showed properties that fulfill the requirements of indoor and outdoor plasters [45]. & Laboratory \\
**Cement** & A belite-based cement (CEM II A-L) was prepared with 80 wt \% of F4 clinker, 16 wt \% of LM and 4 wt \% gypsum [45]. & Laboratory \\
**Clinker** & Belite and Portland clinkers were obtained using only mixtures of biomass sludge, LM and BFA from the pulp and paper process [45]. & Laboratory \\
**Anorthite ceramics** & Another title was the major phase in formulations containing 36 wt \% LM and 64 wt \% BFA synthesized at 1100 \% C [26]. & Laboratory \\
**Bricks** & A mixture of soil:LM (80:20 wt \%) achieved a compressive strength that satisfies the requirements of International standard codes for the production of burnt bricks [66]. & Laboratory \\ \hline Geotechnical & & \\ \hline
**Landfill cover** & LM showed strong potential for replacing soils as intermediate covering in municipal solid waste landfill [27]. & Industrial \\ \hline Environmental & & \\ \hline
**Phosphorous removal** & LM was used to synthesize Ca(OH)\({}_{2}\) nanoparticles (CNP). P removal from aqueous solutions after 10 min was 53\% for a CNP/P mass ratio of 2.2 [67]. & Laboratory \\
**Desulfurization of flue** & LM performed better than commercial limestone in the same conditions, due gas & Laboratory \\
**SO\({}_{2}\) sorbent** & to higher specific surface area and near-optimal pore size [68]. & Laboratory \\  & The CaO derived from LM achieves the maximum sulfation conversion of 83\% at about 940 \({}^{\circ}\)C which is 1.7 times higher than that derived from limestone at about 880 \({}^{\circ}\)C [68]. & Laboratory \\ \hline Agricultural & & \\ \hline
**Fertilizer and soil amendment** & LM (7.5 t/ha) buffered soil acidity, increased pH, doubled the base saturation, and reduced exchangeable acidity [28; 38]. & Laboratory \\
**Liming agent** & The soil amendment shows promising results in the replacement of commercial lining materials (neutralizing value 38.3\% Ca eq, d.w.) [69]. & Laboratory \\ \hline Others & & \\ \hline
**Catalyst** & LM doped with potassium fluoride was used as a transesterification catalyst. Oil conversion of 99.09\% was achieved with 5 wt \% catalyst, methanol/oil molar ratio = 12, t = 2 h and T = 64 \({}^{\circ}\)C [70]. & Laboratory \\
**Sorbent** & LM with the addition of a cationic polymer adsorbed 134.1 mg/g of lignocelllosses from pre-hydrolysis wood chip liquor [71]. & Laboratory \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Applications of LM reported in the literature. The data collected suggests that most of LM potential applications are still at lab scale, except for the case as an intermediate covering for replacing soil in MSW landfills [27]. Some uses for LM as construction materials could be good alternatives to reuse huge amounts of this waste. The production of materials such as geopolymer mortars, cement, clinker, anorthite ceramics or bricks has been evaluated. However, high moisture content (up to 60%) and the existence of silica in LM have created many difficulties in handling this material [28; 72] and may hamper the scale-up as a construction material. In Portugal, LM has been tested in a research project as filler or fine aggregate replacement in the construction of an industrial pavilion [59].