The Influencing Mechanisms of Sodium Hexametaphosphate on Chalcopyrite Flotation in the Presence of MgCl2 and CaCl2

Li, Wanqing; Li, Yubiao; Xiao, Qing; Wei, Zhenlun; Song, Shaoxian

doi:10.3390/min8040150

Cited by 32 publications

(32 citation statements)

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“…It should be noted that the depressing effect due to MgCl 2 was more apparent than that of CaCl 2 . Although Nagaraj and Farinato [45] reported that Ca 2+ had a negligible effect on Mo floatability, many other studies indicated that both Mg 2+ and Ca 2+ played negative roles on sulfide mineral flotation, [22,23,26,29,46], consistent with this study. The differences were probably due to the different mineral samples and flotation conditions used.…”

Section: Theory Calculationsupporting

confidence: 88%

“…Both froth concentrates and tailing were filtered and air dried at 70 • C prior to weighing. The concentrations of Ca 2+ (0.01 M) and Mg 2+ (0.05 M) selected in this study were the same as those contained in seawater [23], thereby providing evidence to understand the primary ions playing the most significant inhibition role. The recovery shown in the Figures 4-6 was the average value of three repeated experiments, with the error bar being as one standard deviation.…”

Section: Minerals and Reagentsmentioning

confidence: 99%

“…For instance, Raglan concentrator in Northern Quebec, Canada, utilizes saline water with a salt concentration ranging from 20,000 to 35,000 ppm in the absence of frother [21]. However, the presence of some divalent cations such as Ca 2+ and Mg 2+ was reported to have a negative effect on mineral flotation due to the adsorption of metal hydroxyl-complexes and colloidal precipitates onto mineral surfaces, reducing hydrophobicity [22][23][24][25]. Many investigators indicated that seawater played a negative role on MoS 2 flotation under alkaline conditions [20,[26][27][28][29], mainly due to the formation of divalent metallic complexes and colloidal precipitates on mineral surfaces, reducing hydrophobicity and the adsorption of collectors.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Wei

et al. 2018

Minerals

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Seawater has been considered as an alternative to freshwater for flotation. However, many ions in seawater were reported to depress molybdenite (MoS2), with the depressing mechanisms being insufficiently understood. In this study, the influence of divalent ions (e.g., Ca2+ and Mg2+) and dispersant on MoS2 flotation was systematically investigated. It was found that the detrimental effects of Ca2+ and Mg2+ on the natural flotability of MoS2 were mainly due to the attachment of formed CaMoO4 precipitates and Mg(OH)2 colloids onto MoS2 surface. However, the addition of sodium hexametaphosphate (SHMP) reduced the negative effects. Various measurements, including contact angle, zeta potential, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), were conducted to understand the influencing mechanisms of divalent ions and the beneficial effects of SHMP on MoS2 flotation. In addition, the Extended Derjguin–Landau–Verwey–Overbeek (EDLVO) theory was applied to investigate the total interaction energy between MoS2 particles and formed colloids, revealing that the reduced attraction force between MoS2 and Mg(OH)2 colloids in the presence of SHMP primarily resulted in the increased MoS2 recovery. In addition, SHMP combined with Mg2+ and Ca2+ to form dissolvable complexes, thereby reducing insoluble Mg2+ and Ca2+ compounds or precipitation. Thus, this study demonstrated for the first time two influencing mechanisms of SHMP in improving MoS2 recovery in the presence of Ca2+ and Mg2+.

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Section: Theory Calculationsupporting

confidence: 88%

Section: Minerals and Reagentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Wei

et al. 2018

Minerals

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“…Sin embargo, la fuerza iónica no es el único aspecto que se debe considerar respecto al agua de mar, ya que a condiciones altamente alcalinas los iones de calcio y magnesio se hidrolizan en la forma de CaOH + /MgOH + y surgen complejos que precipitan como Ca(OH)2/Mg(OH)2. Estas especies, cuya concentración depende del pH y la concentración inicial de cada elemento, han mostrado ser muy perjudiciales en operaciones de flotación de sulfuros, ya que su capacidad para adherirse a la superficie de algunos minerales conduce a que estos pierdan hidrofobicidad y consecuentemente disminuyan su flotabilidad (Castro, 2012;Jeldres et al, 2017aJeldres et al, , 2016Li et al, 2018;Ruan et al, 2018). Menor es la información disponible acerca del impacto que genera la formación de estos complejos en operaciones de espesamiento.…”

Section: Introductionunclassified

Remoción de Calcio y Magnesio en Agua de Mar para Mejorar la Concentración de Sólidos en la Descarga de Espesadores

et al. 2019

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Con el objetivo de aumentar la concentración de sólidos de sedimentos de un relave minero, se utilizó agua de mar con cantidades reducidas de calcio y magnesio. Los experimentos se efectuaron considerando un relave sintético, compuesto por cuarzo y caolinita, y utilizando un floculante aniónico de alta masa molecular. El agua de mar generó un comportamiento eficiente al trabajar a pH < 9. Sin embargo, a mayor alcalinidad la concentración de sólidos del sedimento se redujo sustancialmente. Examinando los principales iones por separado se encontró que el magnesio, y en menor medida el calcio, son los principales responsables de reducir la eficiencia del proceso, producto de la formación de complejos MgOH + /CaOH + y precipitados de Mg(OH)2. Por este motivo, al utilizar el agua de mar con concentraciones reducidas de calcio y magnesio se logró aumentar considerablemente la concentración de sólidos, ofreciendo una alternativa eficaz para operar a condiciones altamente alcalinas.

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“…This excessive addition of lime means a considerable extra cost to the process, in addition to an increase of water hardness. (ii) Calcium and magnesium ions precipitate, which significantly affects the recovery of molybdenite and copper sulfides [16][17][18][19]. For these reasons, one of the main recommendations is working at a natural pH (or close to it), separating pyrite through the addition of new depressants reagents.…”

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confidence: 99%

Depression of Pyrite in Seawater Flotation by Guar Gum

Castellón

Piceros

Toro

et al. 2020

Metals

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The application of guar gum for pyrite depression in seawater flotation was assessed through microflotation tests, Focused Beam Reflectance Measurements (FBRM), and Particle Vision Measurements (PVM). Potassium amyl xanthate (PAX) and methyl isobutyl carbinol (MIBC) were used as collector and frother, respectively. Chemical species on the pyrite surface were characterized by Fourier-transform infrared spectroscopy (FTIR) spectroscopy. The microflotation tests were performed at pH 8, which is the pH at the copper sulfide processing plants that operate with seawater. Pyrite flotation recovery was correlated with FBRM and PVM characterization to delineate the pyrite depression mechanisms by the guar gum. The high flotation recovery of pyrite with PAX was significantly lowered by guar gum, indicating that this polysaccharide could be used as an effective depressant in flotation with sea water. FTIR analysis showed that PAX and guar gum co-adsorbed on the pyrite surface, but the highly hydrophilic nature of the guar gum embedded the hydrophobicity due to the PAX. FBRM and PVM revealed that the guar gum promoted the formation of flocs whose size depended on the addition of guar gum and PAX. It is proposed that the highest pyrite depression occurred not only because of the hydrophilicity induced by the guar gum, but also due to the formation of large flocs, which could not be transported by the bubbles to the froth phase. Furthermore, it is shown that an overdose of guar gum hindered the depression effect due to redispersion of the flocs.Metals 2020, 10, 239 2 of 15 pyrite declines by rising the pH [3][4][5]. This inverse relationship between recovery and pH has been associated with the greater abundance of hydrophilic hydroxides concerning hydrophobic sulfides that found on the pyrite surface. This happens because, at alkaline conditions, ferric hydroxide is generated from the ferrous hydroxide released from inside the pyrite [6][7][8]. Subsequently, ferric hydroxide that has a hydrophilic nature precipitates on the surface of the pyrite, decreasing its contact angle and consequently lowering its floatability [9,10]. In this way, by regulating the pH with alkalizing agents such as sodium hydroxide, sodium carbonate, or lime, it can make the pyrite no float. An interesting aspect is that lime is more effective compared to sodium hydroxide, which is explained by the participation of calcium ions as, at pH less than 12.5, Ca(OH) + is the main component of the solution. This hydrophilic element has a high affinity for the surface of pyrite, so it also helps to boost their depression. It is common that in the copper industry lime is used as the sole depressant for pyrite, primarily when flotation is carried out in freshwater [11,12]. Interestingly, the use of seawater is a strategy that is being frequently adopted in sectors that have a shortage of freshwater, highlighting mining plants in countries such as Chile, Australia, Indonesia, etc. [13]. However, when the operations are carried out in seawater, these are unlikely t...

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The Influencing Mechanisms of Sodium Hexametaphosphate on Chalcopyrite Flotation in the Presence of MgCl2 and CaCl2

Cited by 32 publications

References 54 publications

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Remoción de Calcio y Magnesio en Agua de Mar para Mejorar la Concentración de Sólidos en la Descarga de Espesadores

Depression of Pyrite in Seawater Flotation by Guar Gum

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