Enrichment of coal macerals using froth flotation

A full-scale (470 m3) process for biological treatment of dredging spoil from the Petroleum Harbour in Amsterdam has been monitored during a pilot project. The dredging spoil was heavily polluted with polycyclic aromatic hydrocarbons (PAH) and mineral oil. The remediation chain involved dredging, transport of dredged spoil, hydrocyclone separation, froth flotation of the coarse particles, and biological treatment of the silt fraction (<20 μm) in stirred bioractors. The independent monitoring was aimed at recording the environmental effects, product quality and performance of the biological process. Hydrocyclone separation (cut point 20 m) resulted in two bulk streams: 65% sand and 30% silt (based on total dry weight of the input). The sand was cleaned and could be reused as building material. PAH and mineral oil were successfully concentrated in the silt fraction (<20 μm), which was treated biologically. Biological treatment during continuous feeding of fine fraction, at a residence time of 8-10 days for the entire bioreactor system, resulted in considerably reduced mineral oil and PAH contents. Furthermore, the leaching of organic contaminants was reduced, as well as the ecotoxicity. The obtained silt product however did not meet the demands, and had to be landfilled. Minor emissions of contaminants were measured in wastewater and offgas. The energy and chemicals consumption were acceptable. The biological process appears to be promising for the treatment of less-severely contaminated dredged material.

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Probing the Effect of Water Recycling on Flotation through Anion Spiking Using a Low-Grade Cu–Ni–PGM Ore: The Effect of NO3−, SO42− and S2O32−

Minerals ◽

10.3390/min11040340 ◽

2021 ◽

Vol 11 (4) ◽

pp. 340

Author(s):

Mathew Dzingai ◽

Malibongwe S. Manono ◽

Kirsten C. Corin

Keyword(s):

Water Chemistry ◽

Froth Flotation ◽

Water Source ◽

Threshold Concentration ◽

Process Water ◽

Low Grade ◽

Unit Operations ◽

Flotation Performance ◽

Anion Distribution ◽

Nickel Grade

Water scarcity necessitates the recycling of process water within mineral processing practices. This may however come with its disadvantages for unit operations such as froth flotation as this process is water intensive and sensitive to water chemistry. It is therefore important to monitor the water chemistry of the recycle stream of process water and any other water source to flotation. Monitoring the concentrations of the anions in recycled process water is therefore important to consider as these are speculated to impact flotation performance. Batch flotation tests were conducted using synthetically prepared plant water (3 SPW) with a TDS of 3069 mg/L as the baseline experiment. 3 SPW contained 528 mg/LNO3− and 720 mg/L SO42−, other anions and cations, and no S2O32−. Upon spiking 3 SPW with selected anions, viz, NO3−, SO42− and S2O32−, it was noted that NO3− and SO42− exhibited threshold concentrations while S2O32− did not show a threshold concentration for both copper and nickel grade. Spiking 3 SPW with 352 mg/L more of NO3− to a total 880 mg/L NO3− concentration resulted in the highest copper and nickel grade compared to 3 SPW while increasing the S2O32− from 60 to 78 mg/L increased nickel and copper grade. 720 to 1200 mg/L SO42− and 528 to 880 mg/L NO3− were deemed the concentration boundaries within which lies the threshold concentration above which flotation performance declines with respect to metal grades, while for S2O32− the threshold concentration lies outside the range considered for this study. Anion distribution between the pulp and the froth did not seem to impact the recovery of copper or nickel. Notably, the correlation between the concentrate grades and anion distribution between the froth and the pulp seemed to be ion dependent.

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Specific Ion Effects on the Behavior of Mixtures of Sodium Iso-Butyl Xanthate and Sodium Diethyl Dithiophosphate during the Flotation of a Cu-Ni-PGM Ore: Effects of CaCl2 and NaCl

Environmental Sciences Proceedings ◽

10.3390/iecms2021-10632 ◽

2021 ◽

Vol 6 (1) ◽

pp. 22

Author(s):

Malibongwe S. Manono ◽

Katlego Matibidi ◽

Kirsten C. Corin ◽

Catherine K. Thubakgale ◽

Iyiola O. Otunniyi ◽

...

Keyword(s):

Froth Flotation ◽

Monovalent Cation ◽

Process Water ◽

Polyvalent Cation ◽

Flotation Reagents ◽

Sulfide Flotation ◽

Froth Stability ◽

Ion Effects ◽

The Relationship ◽

Diethyl Dithiophosphate

Inorganic electrolytes present in the process water used during froth flotation may have both beneficial and detrimental effects. These effects are said to be ion specific, as some ions may result in enhanced froth stability, increased mineral recoveries and decreased concentrate grades, while others may bring the opposite effects. Onsite process water quality variations have intensified the need to understand the relationship between inorganic electrolytes and flotation reagents on flotation performance. The use of mixtures of thiol collectors in sulfide flotation is a common practice across the globe; however, very few investigations have considered these in process waters of varying compositions. This study considers the effect of common cations, Na+ and Ca2+, in process water on the behavior of mixtures of thiol collectors. Single-salt solutions of NaCl and CaCl2 at an ionic strength of 0.0213 mol·dm−3 were used to investigate the behavior of mixtures of two thiol collectors. These were carefully selected to understand how mixtures of thiol collectors behave in the presence of a monovalent cation versus a polyvalent cation. Bench-scale froth flotation tests were conducted using a Cu-Ni-PGM ore from the Merensky Reef. The results have shown that the divalent cation, Ca2+, resulted in higher %Cu and %Ni recoveries at all collector mixtures compared to the monovalent cation, Na+. The concentrate grades were, however, slightly compromised, as slightly more gangue reported to the concentrate in the presence of Ca2+. This behavior is attributed to the effect of polyvalent cations on bubble coalescence and froth stability.

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Understanding the mechanism of froth flotation of molybdenite using oily collectors from a perspective of thinning and rupture of thin liquid film

Minerals Engineering ◽

10.1016/j.mineng.2021.106805 ◽

2021 ◽

Vol 163 ◽

pp. 106805

Author(s):

Yuesheng Gao ◽

Lei Pan

Keyword(s):

Liquid Film ◽

Froth Flotation ◽

Thin Liquid Film

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Relationship of coal extraction with free radicals and coal macerals

Fuel Processing Technology ◽

10.1016/0378-3820(88)90052-5 ◽

1988 ◽

Vol 18 (3) ◽

pp. 279-286 ◽

Cited By ~ 19

Author(s):

Mohindar S. Seehra ◽

Bikas Ghosh ◽

John W. Zondlo ◽

Eric A. Mintz

Keyword(s):

Free Radicals ◽

Coal Extraction ◽

Coal Macerals ◽

Relationship Of

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