Experimental Study on Treating Waste Printed Circuit Boards by Molten Salt Oxidation

Lin, Chengqian; Chi, Yong; Jin, Yuqi

doi:10.1007/s12649-017-9836-x

Cited by 17 publications

(5 citation statements)

References 34 publications

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“…Because CaO encapsulated the low-melting eutectic, a layer similar to a refractory material was formed on the surface of the residual slag sample. Moreover, the substance did not have cohesiveness; thus, it reduced the mutual adhesion of molten NaCl and furnace charge [ 22 ]. After adding MgO to the high-salinity organic wastewater, the surface of the carbonized product became rough to form several pores.…”

Section: Resultsmentioning

confidence: 99%

“…In this experiment, because the CaO wraps the low-melting-point eutectic, a layer of refractory-like material was formed on the surface of the residual slag sample, and the material was not cohesive, thus, reducing the bonding between the molten NaCl and the furnace charge [ 22 ]. After adding the MgO, the high-melting-point MgO powder could dilute the molten NaCl and formed a protective layer on the surface of the charged particles.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the influence of the air factor on the composition of the molten carbonate and the type of feed pipe was smaller than that of the temperature; the chlorine retention efficiency of molten carbonate was above 99.9%. They also found that when using molten salt oxidation of waste printed circuit boards [ 22 ], more than 95% of the copper was recycled, as the major component of ash, glass fiber is dissolved by molten carbonate and retained in the salt bath, obtaining an effective resource recovery.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Metal Oxides on Carbonation and Coking of High-Salinity Organic Wastewater

et al. 2020

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Slag is difficult to treat quantitatively due to the formation of a molten mixture in the carbonization process of high-salinity organic wastewater. Thus, aiming at solving this difficulty, the effects of metal oxide additives, additive ratio, furnace burden ratio, and carbonization temperature on the carbonization and coking of high-salinity organic wastewater are systematically analyzed. The analysis is performed using scanning electron microscopy, X-ray diffraction, and Vickers hardness tests. The results show that all five metal oxide additives can reduce the hardness of carbonized products. The relative effect of reducing the coked hardness is as follows: MgO > CaO > kaolin > F e 2 O 3 > A l 2 O 3 . Thus, the effect of MgO on reducing the coking hardness is stronger than that of the other four metal oxides, reducing the hardness of carbonized products by approximately 81%. Furthermore, the adding charge can reduce the hardness index by at least 60%. When the carbonization temperature is higher than 800°C, the hardness index of the carbonized product decreases by approximately 5% each 50°C of increase in temperature. This study shows that the addition of metal oxides can effectively reduce the hardness of coking during the treatment of high-salt organic wastewater by carbonization and oxidation and provide theoretical support for the subsequent treatment of high-salt organic wastewater by carbonization and oxidation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Metal Oxides on Carbonation and Coking of High-Salinity Organic Wastewater

et al. 2020

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“…The molten salt gasification experiments were performed using a lab-scale molten salt reaction system with a 30-150 g/h waste PVC treatment capacity, which was modified from the reaction setup used in our previous works [33,34]. Figure 1 shows the diagram of the setup.…”

Section: Experiments Setup and Proceduresmentioning

confidence: 99%

“…At 300 • C, molten alkali effectively absorbed the bromine in the circuit boards, with more than 99.99% of bromine being absorbed and neutralized by the molten salt, and all metals were efficiently recovered. In our previous works, molten salt demonstrated high halogen retention efficiency and low PCDD/F generation for the disposal of waste printed circuit boards and hazardous waste with high salt content [33,34]. It should be noted that during the molten salt oxidation process, an ash content of less than 20 wt.% must be maintained to sustain the fluidity of the melt, and the concentration of alkali metal carbonates should be higher than 15 wt.% to maintain the acid gas absorption capability.…”

Section: Introductionmentioning

confidence: 98%

Characteristics of Molten Salt Gasification of Waste PVC

Lin,

Yang,

Chen

et al. 2024

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Molten salt oxidation is a robust thermal process with the inherent capability to catalytically oxidize the organic compounds while retaining the inorganic ingredients in salt bath. In the present study, molten salt gasification was used for the disposal of waste PVC. The characteristics of molten salt gasification of PVC under different temperatures and air equivalence ratios (ERs) on the gasification characteristics, chlorine retention efficiency, PCDD/F generation, and the distribution of heavy metals such as Cu, Pb, and Zn were investigated. The results showed that increasing the temperature and ER could effectively enhance the yield of gasification gas and carbon conversion efficiency. The highest gasification efficiency of 41.2% was achieved at 750 °C and ER = 0.4, with a gas yield of 0.442 Nm3/kg PVC. Molten carbonates showed an absorption and retention efficiency of more than 99.5% for chlorine under all conditions. Increasing temperature resulted in a significant reduction in the generation of PCDD/F. At 750 °C, the PCDD/F generation was less than 19 pg/g PVC with an I-TEQ of less than 1.4 pg/g PVC, and the ER had a minor effect on PCDD/F. During the molten salt gasification process, most of the heavy metals, such as Cu, Pb, and Zn, were retained in the salt bath.

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Pyrometallurgical Processes for Recycling Waste Electrical and Electronic Equipment

2021

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Experimental Study on Treating Waste Printed Circuit Boards by Molten Salt Oxidation

Cited by 17 publications

References 34 publications

Effects of Metal Oxides on Carbonation and Coking of High-Salinity Organic Wastewater

Effects of Metal Oxides on Carbonation and Coking of High-Salinity Organic Wastewater

Characteristics of Molten Salt Gasification of Waste PVC

Pyrometallurgical Processes for Recycling Waste Electrical and Electronic Equipment

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