Separation of plastics by froth flotation. The role of size, shape and density of the particles

Pita, Fernando; Castilho, Ana

doi:10.1016/j.wasman.2016.07.041

Cited by 85 publications

(42 citation statements)

References 42 publications

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“…The particle size smaller than 1 mm increases the specific surface area and decreases the selectivity. The efficiency of the plastics separation depends on the plastics mixture type, the different hydrophobity grade, the size, density, shape of the particle and the particle weight [3,10] .…”

Section: Resultsmentioning

confidence: 99%

Selecting chemicals for separation of ABS and HIPS in WEEE by froth flotation

et al. 2019

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SbstractThe feasibility of using common chemicals to separate plastics from waste electrical and electronic equipment (WEEE) by froth flotation is investigated. Plastic waste is one of the WEEE polluters and a separation is necessary to recycle it. The most common plastics in electronic industries are acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS). These plastics are difficult to separate due to the similar specific weights and to both being repellent to water. Froth flotation allows for separating particles by the differences in their surface characteristics by selective wetting agents. The common chemicals are ethanol and acetic acid to depress the plastics. The process with 20% weight of ethanol was able to produce a recovery concentrate of HIPS with 98% and ABS with 96%. The process with 40% weight of acetic acid produces a recovery concentrate of HIPS with 96% and ABS with 83%.

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Section: Resultsmentioning

confidence: 99%

Selecting chemicals for separation of ABS and HIPS in WEEE by froth flotation

et al. 2019

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“…In the flotation tests, the copper and plastic recovery in the sink increased with increasing particles size. Other authors also verified that small plastic particles are easier to float than coarse ones [25][26][27][28]. Moreover, Sarvar et al [23] verified that metal recovery in the floated decreased with increasing particles size.…”

Section: Effect Of Particle Size In the Three Methods Of Separationmentioning

confidence: 91%

Separation of Copper from Electric Cable Waste Based on Mineral Processing Methods: A Case Study

Pita

Castilho

2018

Minerals

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Recycling of electrical cable waste requires a separation between the metal and the insulating material. The objective of this work was to separate the copper from the plastic in electrical cable waste previously ground below 2 mm, using jigging, shaking table and froth flotation techniques. The effect of particle size was also analysed. Jigging and shaking table proved to be effective in the separation of copper from plastics. The result was a copper concentrate with a copper grade of about 97% by both methods and a copper recovery of about 97%. Jigging separation had similar separation efficiencies in the seven-sized fractions, but in shaking table, the separation efficiency improved with an increase in particles size. The separation achieved by froth flotation had lower efficiencies (85%), because plastics are naturally hydrophobic and copper presents some hydrophobic behaviour. In this technique, the addition of depressant agents was mandatory for the depression of copper, even at low concentrations. The best results were obtained with concentrations of 10 −1 mg/L of sodium sulfide (407410 Sigma-Aldrich, Sigma-Aldrich Corporation, St. Louis, MO, USA) and meso-2,3-Dimercaptosuccinic acid (D7881 Sigma-Aldrich).

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“…To study the influence of the particle size, the material was classified by sieving in five size fractions: +1-1.4 mm, +1.4-2 mm, +2-2.8 mm, +2.8-4 mm and +4-5.6 mm. The shape factor, defined by the ratio between the thickness (D min ) and length (D max ), of the six plastics versus size fractions was already assessed [22] . PMMA, PS and PVC-D particles presented more spherical shapes, while PET-D particles showed lamellar shapes.…”

Section: Methodsmentioning

confidence: 99%

“…Methyl cellulose, polyvinyl alcohol, polyethylene glycol, gelatin, tannic acid, saponin, terpineol, triton X-100, calcium lignosulfonate and sodium lignosulfonate have been used as wetting agents by several authors [6][7][8][9][10][11][12][13][14][15][16][17] . Plastic flotation is controlled not only by the hydrophobicity, but also by the shape and size of the plastic particles [18][19][20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

“…This work aimed to study the influence of saponin and sodium lignosulfonate on the floatability of six plastics, and also, to compare it with the effect of tannic acid [22] . Moreover, it tried to establish the ideal concentrations of these two wetting agents to separate plastic mixtures and evaluate the relations of the floatability of plastics with contact angles and gravity factors, such as particle density, particle shape and particle size.…”

Section: Introductionmentioning

confidence: 99%

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Plastics floatability: effect of saponin and sodium lignosulfonate as wetting agents

Pita

Castilho

2019

Polímeros

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Froth flotation is the most common process in mineral processing. For the separation of plastic mixtures by flotation, the use of appropriate wetting agents is mandatory. The floatability of six post-consumer plastics was studied at different concentrations of the wetting agents, saponin and sodium lignosulfonate. Also, the influence of size and shape of the particles were analyzed. Contact angle and floatability of the six plastics decreased with increasing wetting agents concentration. The order of floatability is similar to the order of the contact angles values. However, the influence of the wetting agents in the plastics floatability is more pronounced than in the contact angle. Floatability decreased with the increase of particle density, particle size and spherical shape. For fine particles floatability is fundamentally conditioned by the contact angle, while for coarse particles floatability is fundamentally conditioned by the particles weight.

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Separation of plastics by froth flotation. The role of size, shape and density of the particles

Cited by 85 publications

References 42 publications

Selecting chemicals for separation of ABS and HIPS in WEEE by froth flotation

Selecting chemicals for separation of ABS and HIPS in WEEE by froth flotation

Separation of Copper from Electric Cable Waste Based on Mineral Processing Methods: A Case Study

Plastics floatability: effect of saponin and sodium lignosulfonate as wetting agents

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