# Complex Processing of Saponite Waste from a Diamond-Mining Enterprise
## 5 Research on the Mineral Composition of Pulp after Enrichment  
The clay mineral saponite forms a finely dispersed clay suspension with a concentration of saponite in the circulating water of 5-200 g/dm\({}^{3}\) and colloidal particles, which are 1-3 \(\upmu\)m in size. Without treatment with coagulants and flocculants, the deposition of the clay mineral saponite ends after 1.5 years. Because of the properties of the saponite mineral, which has the characteristic not only to \"swell\", but also to disperse and stabilize, forming a non-precipitating fine-grained gel-like structure bonded with Ca and Mg ions (\(\sim\)20%), the tailing sites allocated by its project increase [18; 19]. The pure mineral saponite-stevensite has the mineralogical structural formula Na\({}_{x}\)Mg\({}_{3}\) (Al\({}_{x}\)Si\({}_{4-x}\)O\({}_{10}\))(OH\({}_{2}\))-4H\({}_{2}\)O, a monoclinic syngony, a density of 2 g/cm\({}^{3}\), and a Mohs hardness of two (refined data: density 2.3-2.5 g/cm\({}^{3}\), Mohs hardness 2.5) [20]. The chemical and physical characteristics of the liquid phase samples were investigated and found to be almost identical and characterized by slightly base pH values, low oxidation-reduction potential, and a small amount of mineralization. According to the information provided by the company, it is not difficult to obtain the required quality discharge (500 mg/L), but it is impossible to obtain a thickened product with a density of 70 wt%. The increased content of clay particles in the circulating water to enrich the ore means that the scheme has to be scaled up or additional water must be gathered from other circulating water for primary sources. The soil composition is heterogeneous and varies in the depth of occurrence. Thus, in the upper layers, its composition is a mixture of sandy loam (up to 30 wt%), saponite (up to 60 wt%), and vermiculite (up to 10 wt%). When the soil depth increases, the content of saponite increases (up to 90 wt%) and, accordingly, the content of sandy loam decreases (down to 5 wt%), as does that of vermiculite (down to 5 wt%). The mineral composition is shown in Figure 2 and Table 1.  
Figure 2: The ore mineral composition. The results of the X-ray diffractometric analysis (XRD) are summarized in Table 1. According to the data obtained, almost 55.4 wt% of the suspension is represented by complex silicates and 34 wt% by aluminosilicates of a layered structure belonging to various mineralogical groups: montmorillonite (nontronite, saponite, beidellite) and zeolites (natrolite) [21]. All of these minerals can be attributed to the light fraction of the matter suspended in the recycled water of the regional processing plant. This is freely suspended throughout the volume. The minerals' precipitation is difficult not only due to the relatively low density of minerals but also due to their lamellar structure and ability to interact with water. This ability is most predominant in saponite and other minerals of the montmorillonite group due to the weak intermolecular bonds between three-layer packages containing two silicon-oxygen tetrahedral layers and an octahedral layer, with aluminum cations located between them. Due to these structural features, water and other polar liquids can freely infiltrate between the layers, increasing the interplane distance from 0.92 nm to 14 nm, which causes a significant change in the density of the mineral and leads to the formation of a non-settling gel mass. Taking into account the sufficient mineral deposition rate of particles of enstatite, phlogopite, albite, and quartz, the remainder is represented by clay minerals, of which about 35% are in the montmorillonite group. In order to determine how the montmorillonite group influencing the diamond enrichment process is subsequently disposed, studies were conducted on the mineral composition of suspended particles in recycled water entering the processing and storage in the tailing basin.