| 1. |
- Tohry, A., et al.
(författare)
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Mechanism of humic acid adsorption as a flotation separation depressant on the complex silicates and hematite
- 2021
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Humic acid (HA), as an environmentally friendly depressant, absorbed significant attention for possible cleaner production within mineral separation by selective separation, especially for reverse flotation of iron oxides. However, a few systematic studies were addressed its effect on the iron ore reverse cationic flotation in the presence of complex silicates and its adsorption mechanism on the surface of these minerals. This work is going to fill this gap by exploring the depression mechanisms of HA through the reverse cationic flotation (separation of hematite from complex silicates; augite and hornblende). Wettability analyses, micro and batch flotation scale tests were employed for such a purpose. Adsorption test, turbidity measurement, zeta potential measurement, and Fourier Transform Infrared (FTIR) analyses were conducted to understand HA adsorption's mechanism on these minerals' surface. Results relieved that at the low concentration of HA (20 mg/L), adsorption on the examined minerals' surface occurred. Based on the micro-flotation test results, HA's depression impact has the following order: hematite ≫ augite > hornblende. The surface analysis results suggested that HA can interact with the Fe ions on the hematite surface by chemical and hydrogen bonding. The same mechanism was observed for HA adsorption on the considered silicates; however, the adsorption rate was lower, while lower polyvalent cations are available on these silicates' surface.
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| 2. |
- Tohry, A., et al.
(författare)
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Tannin : An eco-friendly depressant for the green flotation separation of hematite from quartz
- 2021
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 168
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Tidskriftsartikel (refereegranskat)abstract
- Reverse cationic flotation is the most known beneficiation method for the separation of fine hematite particles from silicates. In this process, the depression of the hematite surface is an essential factor. Thus, the development of environmentally friendly depressants plays a critical role. Tannin (TA) as a natural and eco-friendly organic reagent has not yet been considered for such a purpose. Through the reverse cationic flotation, the depression effect of TA was investigated by single and mixture of minerals. Micro-flotation tests and wettability analysis based on contact angle measurements by the captive bubble method (CBM) were conducted. The surface adsorption mechanism of TA on the hematite and quartz was explored through turbidity, zeta-potential measurements, surface adsorption tests, and Fourier transform infrared (FT-IR) analyses. The micro-flotation results indicated that TA could selectively depress more than 90% of hematite, while its effect on quartz floatability was negligible (<8% depressing). Surface wettability analysis demonstrated that TA in the presence of 30 mg/L collector could significantly increase the work of adhesion of hematite from 135.5 to 143.1 erg/cm2, whereas it increased the work of adhesion of quartz from 117.1 to 120.7 erg/cm2. Surface adsorption analysis depicted that in the presence of 100 mg/L TA, the adsorption amount of TA on the hematite surface was 0.99 mg/g, while this amount for quartz was 0.17 mg/g (around 6 times lower than hematite). Turbidity measurements, applied to clarify the aggregation – dispersion behavior of pure minerals in the TA presence, showed that TA had a dispersion effect on the quartz particles, whereas TA caused hematite aggregation. Surface analyses proved that TA selective adsorption occurred on the hematite surface mainly by chemisorption. In contrast, poor physical adsorption was the main interaction between TA and the quartz surface.
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