Comparative Characterization of the Water-Physical Properties of Slime Fractions of Magnetite Concentrates from SSGOK
Abstract Generated abstract
This study compares the water-physical properties of slime fractions smaller than 0.030 mm in magnetite concentrates from the Sarbai deposit and from a Sokolov-Sarbai ore mixture. The authors separated slime fractions by washing, characterized particle-size distribution, specific surface, moisture capacity, and porosity, and assessed philicity from relative saturation rates with water and benzene. Although the two slime fractions had similar dispersity, they differed in maximum molecular moisture capacity and hydrophilicity, with the Sokolov-Sarbai mixture showing higher values. The difference is attributed to mineralogical composition, especially the greater role of ferrous silicate minerals such as chlorite and pyroxenes, whose surface properties promote stronger water retention.
Full Text
Comparative Characteristics of the Water-Physical Properties of Slime Fractions of Magnetite Concentrates from SSGOK
V. M. Vityugin, N. I. Biryukova
(Presented by the scientific seminar of the Department of General Chemical Technology)
Previous studies on the pelletizing of finely ground iron-ore concentrates have established that the ability of these dispersed materials to aggregate and the quality of green pellets depend substantially on the content in the concentrates of the fine (slime) fraction with a particle size of less than 0.030 mm [1, 2]. The finely dispersed fraction of iron-ore concentrates consists mainly of gangue components, such as actinolite, pyroxenes, amphiboles, epidote, calcite, quartz, chlorite, etc. At the same time, the content of individual minerals and their ratio in different concentrates vary within considerable limits. The study of the water-physical properties of slime fractions makes it possible to assess the influence of gangue components on the pelletizing process.
In the present work, the water-physical properties of the slime fraction of iron-ore concentrates obtained from ores of the Sarbai deposit (sample I) and from a mixture of ores of the Sokolov and Sarbai deposits (sample II) were investigated.
The slime fraction of the concentrates was obtained by the washing method. Table 1 gives the characteristics of the initial concentrates and their slime fractions.
From the data presented it is evident that the slimes of the concentrates differ little from one another in their dispersity: their bulk is represented by particles smaller than 0.010 mm; the content of the 0.010–0 mm size class is 74.8 and 73.4%, respectively, for samples I and II. However, the maximum hygroscopicity (MH) and maximum molecular moisture capacity (MMMC), which depend to a considerable degree on dispersity, in this case have different values, determined by the surface properties of the mineralogical components. One of these properties is the philicity of the materials under study.
The philicity of the concentrates and slimes was determined from the relative rate of their saturation with water and benzene. The results of these studies, shown in Fig. 1, indicate that the philicity of the materials studied, $\varphi = \frac{\beta \mathrm{H_2O}}{\beta \mathrm{C_6H_6}}$, is different. Here $\beta \mathrm{H_2O}$ and $\beta \mathrm{C_6H_6}$ are the tangents of the angle of inclination of the straight-line dependence of the moisture or benzene content on the saturation-rate coefficient of the materials studied. The slime fraction is the most hydrophilic component of the concentrates; moreover, the philicity value of the slimes of sample II is higher than that of sample I and is, respectively, 3.0 and 2.34, while for the concentrates it is 1.09 and 0.940.
Characteristics of the materials studied
Table 1
| Material | Specific gravity, g/cm³ | Magnetic fraction, % | Maximum molecular moisture capacity, %, mold 1 mm | Maximum molecular moisture capacity, %, mold 2 mm | Particle-size class content (mm), %, +0.1 | Particle-size class content (mm), %, −0.1 +0.074 | Particle-size class content (mm), %, −0.074 +0.044 | Particle-size class content (mm), %, −0.044 +0.030 | Particle-size class content (mm), %, −0.030 +0.020 | Particle-size class content (mm), %, −0.020 +0.010 | Particle-size class content (mm), %, −0.010 +0.005 | Particle-size class content (mm), %, −0.005 | Specific surface, cm²/g | Porosity |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Concentrate I | 4,68 | 0,56 | 6,1 | 8,2 | 0,9 | 1,2 | 15,6 | 6,7 | 15,3 | 29,1 | 9,7 | 21,5 | 1690 | 0,94 |
| Concentrate II | 4,27 | 0,70 | 7,47 | 7,92 | 0,5 | 1,3 | 14,6 | 7,9 | 17,3 | 32,2 | 10,2 | 16,0 | 1450 | 1,09 |
| Slimes I | 3,19 | 3,86 | 18,1 | 19,8 | — | — | — | 2,2 | 4,3 | 18,7 | 25,00 | 49,8 | 8700 | 2,34 |
| Slimes II | 2,94 | 4,33 | 20,1 | 21,57 | — | — | — | 3,7 | 8,2 | 14,7 | 28,7 | 54,7 | 9970 | 3,0 |
Fig. 1. Dependence of the water and benzene content on the saturation-rate coefficient: — saturation with water, - - - - - saturation with benzene; xΔ slime fraction of the 1st and 2nd samples, x▲ concentrates of samples 1 and 2.
The magnitude of the hydrophilicity of the slimes depends on their mineralogical constituents. Mineralogical analysis of the concentrates showed that the slime fraction of sample I is represented mainly by pyroxene, calcite, epidote, and quartz, while that of sample II is represented by chlorite, pyroxene, plagioclase, and calcite (the order of the constituents corresponds to a decrease in their content).
In studying the process of vacuum dewatering of fine-grained iron-ore concentrates, it was established that the most moisture-retentive minerals are those containing ferrous silicates (chlorites, amphiboles, pyroxenes), since they have uncompensated ionic forces on the surface, which strongly retain water. Quartz and magnetite, having compensated surface bonds, do not promote strong bonding of water with their surface [3]. This also explains why the hydrophilicity of the slimes of sample II is significantly higher than that of the first sample.
REFERENCES
- V. A. Martynenko, G. I. Serebryanykh. Influence of the properties of the components of a charge on the granulation process. Gornyi zhurnal, 1971, No. 4.
- A. N. Spektor et al. Grindability of iron-ore concentrates as a function of their properties. TsNIICHM, Series 3, Information 10, 1969.
- V. T. Baryshpolets. Some questions in the theory of dewatering fine-grained iron-ore concentrates. In: Material Composition of Sedimentary Ores and Questions of Their Beneficiation, Kiev, “Naukova Dumka,” 1971.