Printed circuit boards（PCBs） contain many toxic substances as well as valuable metals, e.g., lead（Pb） and tin（Sn）. In this study, a novel technology, named supergravity, was used to separate different mass ratio...Printed circuit boards（PCBs） contain many toxic substances as well as valuable metals, e.g., lead（Pb） and tin（Sn）. In this study, a novel technology, named supergravity, was used to separate different mass ratios of Pb and Sn from Pb–Sn alloys in PCBs. In a supergravity field, the liquid metal phase can permeate from solid particles. Hence, temperatures of 200, 280, and 400°C were chosen to separate Pb and Sn from PCBs. The results depicted that gravity coefficient only affected the recovery rates of Pb and Sn, whereas it had little effect on the mass ratios of Pb and Sn in the obtained alloys. With an increase in gravity coefficient, the recovery values of Pb and Sn in each step of the separation process increased. In the single-step separation process, the mass ratios of Pb and Sn in Pb–Sn alloys were 0.55, 0.40, and 0.64 at 200, 280, and 400°C, respectively. In the two-step separation process, the mass ratios were 0.12 and 0.55 at 280 and 400°C, respectively. Further, the mass ratio was observed to be 0.76 at 400°C in the three-step separation process. This process provides an innovative approach to the recycling mechanism of Pb and Sn from PCBs.展开更多
The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered ...The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO ：SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L Cr ′^ m/s , and a linear relationship between L Cr ′^m/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51704022)
文摘Printed circuit boards（PCBs） contain many toxic substances as well as valuable metals, e.g., lead（Pb） and tin（Sn）. In this study, a novel technology, named supergravity, was used to separate different mass ratios of Pb and Sn from Pb–Sn alloys in PCBs. In a supergravity field, the liquid metal phase can permeate from solid particles. Hence, temperatures of 200, 280, and 400°C were chosen to separate Pb and Sn from PCBs. The results depicted that gravity coefficient only affected the recovery rates of Pb and Sn, whereas it had little effect on the mass ratios of Pb and Sn in the obtained alloys. With an increase in gravity coefficient, the recovery values of Pb and Sn in each step of the separation process increased. In the single-step separation process, the mass ratios of Pb and Sn in Pb–Sn alloys were 0.55, 0.40, and 0.64 at 200, 280, and 400°C, respectively. In the two-step separation process, the mass ratios were 0.12 and 0.55 at 280 and 400°C, respectively. Further, the mass ratio was observed to be 0.76 at 400°C in the three-step separation process. This process provides an innovative approach to the recycling mechanism of Pb and Sn from PCBs.
基金financially supported by the National Natural Science Foundation of China (No. 51474021)the Fundamental Research Funds for the Central Universities of China (No. FRF-SD-12-009A)
文摘The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO ：SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L Cr ′^ m/s , and a linear relationship between L Cr ′^m/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.
