11
1.6.2 Hydrometallurgical Process
This method is used by applying acidic or caustic solutions on cathode-ray tube
funnel glass followed by separation and cleansing procedures to concentrate the
metals. However, to overcome the strong bonding of metals from glass and increase
the solubility of lead, some pretreatments such as acid washing in 5% nitric acid
for 3 h and rinsing with tap water on CRT funnel glass are carried out (Ling and
Poon 2011). Zhang et  al. (2013) used a strong alkaline solution combined with
chemical leaching and mechanical activation (stirring ball mill) as a novel hydrometallurgical process with lead removal efficiency of 97%. Yuan et al. (2015) separated lead from cathode-ray tube funnel glass by pretreating with hydroxyl ions
produced during an ion exchange reaction between metal ions in mechanically
activated funnel glass and water under hydrothermal sulfidisation. Hydrometallurgy
process is no longer profitable when transportation distance increases
significantly.
Fig. 1.5 Pyrometallurgical process. (Source: Adapted from Gong et al. 2016)
1 Solution and Challenges in Recycling Waste Cathode-Ray Tube