A study on physical separation processes for recovery metals from waste printed circuit boards (PCBs)
In view of increasing the waste PCBs, a physical separation process has been carried out to recover metals from waste PCBs. This research is aimed to implement an effective and environmental friendly recovery particularly cooper (Cu) of waste PCBs. The physical separation process begins with comm...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/12851/1/p.%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/12851/2/Full%20Text.pdf |
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| Summary: | In view of increasing the waste PCBs, a physical separation process has been carried out to
recover metals from waste PCBs. This research is aimed to implement an effective and
environmental friendly recovery particularly cooper (Cu) of waste PCBs. The physical
separation process begins with comminution to produce controlled particle size. Then, the
separation process was divided into two parts according optimum efficiencies at specific
size range. The size fraction -600+300µm and -1180+600µm were separated by gravity
separation using Mozley laboratory separator. Afterwards, an enrichment step of
concentrate fraction was done by magnetic separation using rare-earth roll magnetic
separator. Meanwhile, the size fraction -150µm, -300+150µm, and -600+300µm were
separated to froth flotation using Denver D-12 laboratory flotation cell. Characterisations of
waste PCBs were performed by micrographic analysis and elemental analysis. A qualitative
micrographic analysis was conducted using stereo- zoom microscope, optical microscope,
and scanning electron microscopy. An elemental analysis was conducted using atomic
absorption spectroscopy (AAS) analysis and energy dispersive spectrometer (EDS).
Regarding on the particle size analysis, maximising recovery of physical separation is done
by targeting recovery in a controlled four size range fraction; -150µm, -150+300µm, -
300+600µm and -600+1180µm. A qualitative liberation assessment of the waste PCBs
particle was establish unliberated particles still remain in the waste PCBs fines (-75µm). As
the highest metal element in waste PCBs, copper (Cu) recovery (R) and enrichment ratio
(ER) was discussed with more emphasis in this project. By Mozley laboratory separator, Cu
recovery increase from 80.85% (ER 2.07) at -600+300µm size fraction to 89.65% (1.93) at
-1180+600µm size. Thus, the efficiency of gravity separation increases with increasing
particle size. A significant of the low recovery at finer size fraction implies valuable metal
loss at this size range, thereby be evidence that it is not very effective for finer particles (-
300µm) was recovered by Mozley laboratory separator. For enrichment step using Rareearth
roll magnetic separator showed the enrichment ratio (ER) was highly improved. At -
600+300µm non-magnetic fraction, Cu enrichment ratio is 2.51 and 2.15 at -1180+600µm
size fraction. Through the reverse froth flotation, higher Cu recovery (R) and lower Cu
enrichment ratio (ER) are noticeably with increasing particle size fraction for both flotation
conditions (with and without frother). Thus, the efficiency of froth flotation is higher at
finer size fraction. At -75µm size fraction, Cu recovery is 84.66% (ER 3.03) under natural
hydrophobic responds (without frother). Meanwhile with frother addition, Cu recovery is
82.16% (ER 3.37). In view of frother addition, there is improved in enrichment ratio but
poor recovery percentage. Overall, the approach physical separation has high efficiency,
easy to run and at same could recover metals and non-metals. It is expected that physical
separation process will be developed for the upgrading of metals recovery in waste PCBs. |
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