## 3 Results and Discussion
### Characterization of the Inputs and Output Products of the Phosphate Laundries
#### 3.1.3 Geochemistry  
Results of the geochemical analysis of the input and output products from the two laundries are summarized in Table 3.  
These results show considerable amounts of OM in the samples in particular those of the Redeyer (1.22-3.89%). This is one of the characteristics of the phosphorites of the Gafsa-Metlaoui Basin. It should be also noted that the raw phosphates and the fine wastes from the two laundries contain the highest OM contents (1.22% to 1.36% and 1.51% to 3.89%, respectively). According to [PERSON] [26], this OM makes an absorption/adsorption surface for some metals such as zinc. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mineralogy**} & \multicolumn{8}{c}{**Sample**} \\ \cline{2-10}  & **RP–ZL** & **MP–ZL** & **CW–ZL** & **FW–ZL** & **RP–R** & **MP–R** & **CW–R** & **FW–R** \\ \hline
**Carbonate fluorapatite(CFA)** & 34 & 48.5 & 26.3 & 23.2 & 27.3 & 35.7 & 16.2 & 17 \\
**Calcite** & 8 & 7.9 & 23.2 & 16.2 & 9.1 & 4.1 & 22.2 & 18 \\
**Ankerite** & 13 & 3 & 12.1 & 14.2 & 6.1 & 2 & 6.1 & 2 \\
**Dolomite** & 14 & 5 & 16.2 & 17.2 & 6.1 & 2 & 9.1 & 4 \\
**Clinoptiolite** & 23 & 27.7 & 18.2 & 24.2 & 25.3 & 37.8 & 17.2 & 34 \\
**Gypsum** & 6 & 6.9 & 3 & 3 & 8.1 & 5.2 & 4 & 4 \\
**Quartz** & 2 & 1 & 1 & 1 & 5.1 & 1 & 9 & 1 \\
**Palygorskite** & - & - & - & 1 & 12.9 & 12.2 & 16.2 & 20 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Semi-quantitative mineralogical composition (%). CW: coarse waste from the M’Dhilla-Zone L (ZL) and Redeyer (R) laundries (other references are as in Table 1). Figure 2: X-rays diffractograms. RP–ZL, MP–ZL, CW–ZL, and FW–ZL: raw phosphate, marketable phosphate, coarse waste, and fine waste from M’Dhilla-Zone L, respectively. RP–R, MP–R, CW–R, and FW–R: raw phosphate, marketable phosphate, coarse waste, and fine waste from Redeyer, respectively. CFA: carbonate fluorapatite, D: dolomite, C: calcite, Q: quartz, A: ankerite, G: gypsum, Cl: clinoptiolite, and P: palygorskite. Concerning the total nitrogen, all the samples contain low contents 0.003% to 0.01%; the highest content (0.01%) characterizes the sample FW-R. Likewise, the highest CaCO\({}_{3}\) contents (27.16% to 24.19%) characterize the coarse wastes from the two laundries, thus substantiating the carbonated nature of these wastes. In terms of major elements, results show that CaO and P\({}_{2}\)O\({}_{5}\) have the highest concentrations as major elements for all samples. The highest levels of CaO characterized the marketable phosphate with a maximum of around 49.51% for the Redeyef laundry, and 47.93% for the ZL laundry, whereas the lowest levels are recorded with the fine wastes (Table 3). Considering the P\({}_{2}\)O\({}_{5}\) contents, it is worth noting that the washing process at M'Dhill-Zone L and Redeyef results in the enrichment of the marketable ore (29.37% and 28.45%, respectively), consequently eliminating the coarse and fine wastes, which are low in phosphate (18.81% and 8.45% P\({}_{2}\)O\({}_{5}\), respectively). With regards to samples extracted from both laundries, the CaO/P\({}_{2}\)O\({}_{5}\) ratios show that the values for raw and market phosphates range from 1.63 to 1.94, the lowest values (1.63-1.74) characterize the marketable phosphates. The latter are slightly higher than the corresponding ratio in pure CFA, which is estimated at 1.57 [27]-1.62 [28], indicating that the apatite dealt with is chemically identifiable to CFA [8; 29; 30; 31; 32; 33; 34; 35; 36]. The higher values obtained for the coarse and fine wastes (2.03-2.54) are indicative of high contents of carbonates as gangue minerals.