This paper describes a kinetic study of the decomposition of waste printed circuit boards (WPCB) under conventional and microwave-induced pyrolysis conditions. We discuss the heating rates and the influence of the pyrolysis on the thermal decomposition kinetics of WPCB. We find that the thermal degradation of WPCB in a controlled conventional thermogravimetric analyzer (TGA) occurred in the temperature range of 300 °C–600 °C, where the main pyrolysis of organic matter takes place along with an expulsion of volumetric volatiles. The corresponding activation energy is decreased from 267 kJ/mol to 168 kJ/mol with increased heating rates from 20 °C/min to 50 °C/min. Similarly, the process of microwave-induced pyrolysis of WPCB material manifests in only one stage, judging by experiments with a microwave power of 700 W. Here, the activation energy is determined to be only 49 kJ/mol, much lower than that found in a conventional TGA subject to a similar heating rate. The low activation energy found in microwave-induced pyrolysis suggests that the adoption of microwave technology for the disposal of WPCB material and even for waste electronic and electrical equipment (WEEE) could be an attractive option.

To solve the problems of difficult treatment of desulfurized gypsum and overmining of limestone, a kind of lime/gypsum flue gas desulfurization (FGD) collaborative desulfurized gypsum resource utilization process (LCS) was proposed. The system mainly includes the LCS-LFGD (lime/gypsum flue gas desulfurization system), LCS-C (desulfurized gypsum reduction calcining process), and carbon monoxide-coupled activated carbon reduction of SO₂ to sulfur process (LCS-S). Taking a typical wet FGD unit of 300 MW power plant in China as an example, the limestone/gypsum flue gas desulfurization system (L-FGD) process was compared with the LCS by using the method of life cycle assessment and life cycle cost (LCC). The result shows that the overall environmental impact of the LCS is 0.2913. The environmental impacts of LCS-LFGD, LCS-C, and LCS-S were 0.1322, 0.1543, and 0.0048, respectively. Both LCS-LFGD and LCS-C are the key processes in this case study, and electricity consumption and coal gas consumption are the key substances in each key process. LCC analysis showed that although the initial investment of LCS was 4.32 × 10⁶ USD ∼5.76 × 10⁶ USD more compared with L-FGD, the running cost of LCS was 1.41 × 10⁶ USD per year lower compared with L-FGD. Besides, the cost of ore mining, the quality of calcined products, and environmental protection policy will affect the financial cost of the process.

Supercritical water oxidation (SCWO) is a new and promising technology for treating organic waste and recovering energy. High energy consumption is a major problem preventing its commercial application. Energy recovery is the most effective method for reducing energy consumption of an SCWO system. To maximize the energy recovery of the SCWO pilot plant with a transpiring wall reactor, the reactor effluent is used to preheat both feed and transpiring water and produce hot water. An experimental study was conducted to investigate the influence of the operating parameters on energy consumption per unit total organic carbon (TOC) removal (ECPT) for saving the energy of the system. Results show that the effect of feed concentration on ECPT is the most significant and that of high feed concentrations, result in lower ECPT. Lower ECPT is also present at high feed flow rates, but at the expense of the decrease of TOC removal efficiency when the feed flow rate exceeds 14 kg/h.

In this study, a targeted oxygen-enrichment technology was proposed to enhance coal combustion in an ironmaking blast furnace. The coal flow and combustion characteristics under targeted oxygen-enrichment were investigated using the computational fluid dynamics (CFD) method. The results showed that oxygen utilization and coal burnout were significantly increased under targeted oxygen-enrichment. The coal burnout at 24% O₂ concentration was 86.29%, which was the maximum and indicated an increase of 13.13%. However, the cooling effect of room-temperature oxygen had some adverse effects on coal combustion. Given this, the effect of coal particle temperature on coal combustion was investigated based on targeted oxygen-enrichment. The coal combustion process was further enhanced. The coal burnout at a 600 K particle temperature and 25% oxygen concentration was 91.12% and had an increase of 17.96%, which was the maximum.