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Effects of Ca2+/Mg2+ ions in recycled water on the reverse flotation properties of iron oxides

Tang Min, Yan Wu, Fu Jiahao

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 3

art. no. 188465

EN

Water quality, particularly hardness, plays an important role in affecting the floatability of minerals as it interferes with the chemical/electro-chemical characteristics of mineral surfaces and their interactions with flotation reagents. It could become unpredictable when water sources characterized by different calcium or magnesium ion distributions were involved. This study aimed to identify the role of Ca2+/Mg2+ ions in the recycled water on the cationic reverse flotation selectivity of iron oxides through a series of bench/micro flotation tests, zeta potential, powder contact angle, and Fourier Transform Infrared (FTIR), etc. The results pointed out that the use of recycled tailing water deteriorates the flotation selectivity and dilutes the concentrates. This can be largely attributed to the presence of Ca2+ ions at higher concentrations as they induce a drop in the Fe recovery and an increase in SiO2 content while an increase in the content of Mg2+ ions seems to have little effect on the quality of concentrate. As evidenced by the data from micro-flotation, powder contact angle, zeta potentials, and FTIR, a hydrophilic colloidal layer formed by Ca-based hydrolyzed compounds, such as Ca(OH)+ or, CaCO3(s), etc., on quartz could change its zeta potentials and disturb its interactions with a cationic collector. They also play a role in weakening the flocculation of starch on hematite probably by prelocking the acidic groups on the starch remnants and contracting their configurations, thus preventing their adsorption on mineral surfaces. However, magnesium ions seem to be beneficial to in strengthening the flocculation of starch on hematite as magnesium-based species could act as adsorption bridges of between starch and mineral surfaces.

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Wytrącanie i krystalizacja struwitu z syntetycznego ścieku przy nadmiarze jonów magnezu

Kozik A., Hutnik N., Piotrowski K., Mazieńczuk A., Matynia A.

Przemysł Chemiczny

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2014

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T. 93, nr 5

756-761

PL

Z syntetycznego ścieku odzyskiwano jony fosforanowe (V) przez krystalizację z reakcją chemiczną wytrącania struwitu MgNH4PO4·6H2O. Proces prowadzono w sposób ciągły, przy nadmiarze jonów magnezu w stosunku do stężenia jonów fosforanowych(V) i jonów amonu. Otrzymano produkt zawierający 90-95% mas. struwitu i zanieczyszczenia wytrącone ze ścieku. W zależności od parametrów procesu (pH 9-11, τ 900-3600 s) średni rozmiar kryształów struwitu wynosił od 12 do ok. 44 μm przy liniowej szybkości ich wzrostu (4,21-16,9)∙10-9m/s.

EN

An artificial PO43-, Mg2+ and NH4+ ions-contg. Wastewater was treated with aq. soln. of NaOH in continuous flow to recover struvite by reaction crystn. at 298 K and pH 9-11 for 900-3600 s. The solid product contained struvite (90-95% by mass) and some impurities copptd. from the wastewater. The struvite crystals were 12-44 μm in size. Their linear growth rate was (4.21-16.9)∙10-9 m/s.

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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.