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1

The effect of sodium carboxymethyl cellulose on the entrainment of zoisite in flotation

Zhang Zhengjun, Ou Leming, Jin Saizhen, Zhou Hao

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 2

34--47

EN

During flotation, fine gangue minerals can enter the concentrate through mechanical entrainment, which seriously affects the quality of concentrate. In this work, the effect of sodium carboxymethyl cellulose (CMC) on the flotation performance of zoisite, a silicate mineral, was studied. The role of CMC in reducing zoisite entrainment was investigated by dynamic foaming tests, surface tension measurements, rheology measurements, sedimentation tests, and optical microscopy experiments. The flotation results showed that zoisite mainly entered the concentrate by entrainment; the addition of low dosages of CMC decreased zoisite entrainment and efficiently separated cassiterite from zoisite; moreover, the concentrate grade and recovery of SnO2 increased by 1.27 % and 5.63 %, respectively, by using CMC in closed-circuit flotation tests. Dynamic foaming studies on the two-phase and three-phase foam/froth revealed that the presence of CMC decreased the froth ability and froth stability, and greatly altered the three-phase froth structure. Basically, the bubbles in the foam were larger after adding CMC. For the two-phase foam, the change of foam property had little to do with surface activity and bulk viscosity. For the three-phase froth, the froth property was strongly affected by the interaction of CMC and zoisite. The results of the sedimentation test and microscopy experiment demonstrated that CMC can cause zoisite to flocculate and enlarge the particle size, which was the main reason for the decrease of froth stability and entrainment. This study indicates that the side effects of depressants should not be overlooked when discussing the role of depressants in flotation.

2

Effects of single and mixed reagent systems on improved diaspore recovery

Jiang Hao, Xiang Guoyuan, Gao Ya, Khoso Sultan Ahmed, Peng Weiwen

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 5

1179--1191

EN

Frothing performance and stability of sodium oleate (NaOL) alone and in presence of methyl isobutyl methanol (MIBC), octanol (OCT) and polyethylene glycol (PEG) systems were studied and compared in order to enhance flotation separation of diasporic bauxite ore. Performance of a single (NaOL) and mixed systems (NaOL-MIBC, NaOL-OCT, NaOL-PEG) was evaluated through flotation tests, three-phase dynamic froth stability tests, zeta potential measurements and adsorption analysis. The mixed systems showed a stable froth and an improved recovery with their descending order NaOLPEG˃NaOL-OCT ˃ NaOL-MIBC. Adsorption analysis and zeta potential measurements suggested that, except NaOL adsorption, there was no significant co-adsorption of alcohols on the diaspore surface. However, adsorbed amount of NaOL on the diaspore surface was extremely high; accounts for more than 90% of the total substance used in the pulp.

3

A fundamental study of monovalent and divalent ions on froth properties in the presence of terpenic oil

Li Yubiao, Wang Hongduo, Li Wanqing, Song Shaoxian

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 3

643--654

EN

In order to minimize fresh water usage, much attention has been paid to the flotation using saline or sea water. However, the effects of various ions in these waters on froth properties in flotation are not fully understood. In this study, the effects of electrolyte solutions containing NaCl, KCl, CaCl2, and MgCl2 at different concentrations in the presence of terpenic oil as a frother were investigated on froth performance, dynamic froth stability (DFS). It was found that KCl had the best synergistic effects with terpenic oil in reducing the solution surface tension. In the presence of terpenic oil, the DFS and half-life time were reduced with the increased ion concentration. Dynamics foamability index measurements (DFI) confirmed that the increased ion concentration increased the foamability, as frother did. In addition, Gibbs adsorption isotherm suggested that the amount of terpenic oil adsorbed at the gas-liquid interface was increased with the increased ion concentration. This study therefore indicated that the presence of ions can reduce the froth stability but not decline foamability due to terpenic oil, enlighting the application of saline or sea water in defoaming process in flotation.

4

Water quality effects on a sulfidic PGM ore: Implications for froth stability and gangue management

Manono M. S., Corin K., Wiese J.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1253--1265

EN

Polysaccharide depressants play a crucial role in the flotation of sulfidic PGM bearing ores as they prevent naturally floatable gangue (NFG) from reporting to the concentrate. This action is regarded as critically important because less dilution of the concentrate means lower costs for downstream processes. However, abnormal water conditions such as high concentrations of ions in the flotation system can modify the selectivity of these depressants. It is well known that the existence of selected electrolytes in water can alter the behaviour of some polysaccharide depressants by enhancing their adsorption onto gangue minerals and thereby prevent naturally floatable gangue from moving into the froth phase. Concurrently these same electrolytes may enhance frothability owing to their stabilising effect on the bubbles within the system. Plant water at various ionic strengths was investigated against sodium carboxymethyl cellulose (CMC) dosages in order to understand electrolyte-depressant interactive effects during the flotation of a Merensky ore in a batch flotation cell, using entrainment, rate of NFG recovery, and total gangue recovery as proxies. The study showed that the NFG recovery per unit mass of water decreased with increasing ionic strength at all CMC dosages, however the total amount of gangue reporting to the concentrate increased with increasing ionic strength at all CMC dosages. Thus, this paper considers the effects of both ionic strength and CMC dosage within flotation. It further investigates whether any interactive effects exist between froth stability and entrainment when considered simultaneously.

5

Perspectives from literature on the influence of inorganic electrolytes present in plant water on flotation performance

Manono M. S., Corin K., Wiese J.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1191--1214

EN

The interaction of inorganic electrolytes with reagents in the flotation of sulphidic PGM bearing ores is not well explored. It has been shown that specific inorganic electrolytes such as Ca2+ and SO42- can affect the wettability of gangue minerals. These could also hinder the adsorption of collectors onto valuable minerals and concurrently enhance or retard froth stability. This presents a challenge as regards understanding what the overarching or controlling mechanisms of interaction between electrolytes, reagents and minerals are as well as predicting how flotation performance will be affected. This review shows that studies in literature have simplified the question of electrolyte-reagent-mineral interactions and that current approaches have not provided fundamental solutions to the challenge of water quality. It is proposed that the complexity of the flotation system requires an in-depth knowledge of the individual electrolyte-reagent-mineral interactions so as to establish whether there are any dominant or synergistic interactions. Such in-depth knowledge should enable the development of pulp chemistry control measures against water quality variations in flotation.

6

Effect of electrolyte addition on flotation response of coal

Zhang H.

Physicochemical Problems of Mineral Processing

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2015

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Vol. 51, iss. 1

257--267

EN

In this study, the flotation of naturally hydrophobic coal particles in salt solutions with different cations (Na+, Ca2+, and Al3+) was investigated to clarify the flotation enhancement mechanism. The surface chemistry aspects were examined using the zeta potential measurements and bubble-particle attachment time experiments. The results of the flotation experiments showed that the presence of electrolytes in the flotation system clearly enhanced the flotation performance in a manner dependent on the type and concentration of the electrolytes. In the experiments, the AlCl3 and NaCl solutions showed the highest and the lowest flotation performance improvements, respectively. The zeta potential measurements showed that AlCl3 had a stronger influence on the surface charge of coal particles than CaCl2 or NaCl did. The induction time measurements indicated that the attachment decreased with increasing salt concentration and ionic valency state. In addition, abundant fine bubbles were generated in higher concentration salt solutions, particularly for the AlCl3 solutions, which prevented from the bubble coalescence and increased froth stability. It is concluded that the addition of salt solutions to a flotation system enhances the coal flotation performance, particularly for high-valence electrolyte solutions, which is attributed to the abundance of finer bubbles in the froth phase, depending on the type and concentration of the electrolyte.

7

Effect of seawater main components on frothability in the flotation of Cu-Mo sulfide ore

Laskowski J. S., Castro S., Ramos O.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 1

17--29

EN

The main problem in the flotation of Cu-Mo sulfide ores in seawater is poor floatability of molybdenite at pH>9.5. Froth stability plays a very important role in determining concentrate grade and recovery in flotation operations and in this paper both floatability and frothability have been tested. The frothability have been studied by measuring froth equilibrium layer thickness in a modified laboratory flotation cell. Two chemical aspects of seawater need to be considered: the content of NaCl (around 87% of salinity), and the concentration of secondary ions (around 13%) (sulfate, magnesium, calcium, bicarbonate ions, etc.). Seawater, NaCl solutions, and seawater’s ions were found to depress frothability. The effect of pH on frothability over the pH range from 9.5 to 11, which is very strong in freshwater, becomes negligible in seawater and the tested electrolyte solutions. The analysis of the relationship between the mechanisms of molybdenite depression and the loss of frothability in seawater implies that the effects of the studied ions on molybdenite floatability and on pulp frothability are different. While depression of molybdenite floatability could be tracked down to magnesium hydroxide precipitation as a main culprit, the depression of frothability is a much more complicated issue.

8

Specific ion effect of chloride salts on collectorless flotation of coal

Ozdemir O.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

511--524

EN

Separation of naturally hydrophobic particles, such as coal, by flotation is known to be enhanced with the addition of salt solutions into the system. In this study, the flotation of bituminous coal in the presence of NaCl, KCl, CaCl2 and MgCl2 without use of any flotation chemicals was investigated in detailed. In addition, zeta potential and foam stability tests were performed. The results from this study showed that the flotation behaviour of coal was influenced by these dissolved salts, and determined by the specific effect of these ions, while MgCl2 and KCl solutions showed the highest and the lowest flotation performance improvements, respectively. The ash content of the products also increased with the salt concentration. This can be attributed to the entrainment of the ash minerals in the salt solutions, particularly at higher salt concentrations. Meanwhile, the froth stability tests at 1 M salt concentration also indicated that there is a correlation between the flotation recovery and stability profile of the froth. These results also clearly indicated that Na+, K+, Ca2+, Mg2+ ions have a strong ion specific effect on the flotation recovery of the coal particles, and there is an optimum salt concentration to produce a clean coal in these salt solutions.