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Aimed to give a preliminary image of dioxin pollution in China, chemometric analysis was performed to determine background dioxin levels during the period 1994–2002 and potential emission sources. Using principal components analysis (PCA), the congener profiles of 71 sediment samples from rivers, lakes, and sea bays around China were compared with the congener profiles of various known or suspected industrial, residential, and municipal dioxin sources to determine whether the dioxin residues typically found in a broad range of potential environmental sources could explain the presence of these chemicals in China. It was found that the background dioxin levels of China were similar to those of lightly polluted samples from other countries during the period 1994–2002. Primary ferrous ore sintering and secondary lead and aluminum smelters were the major sources of dioxin emission in China. Chloranil and wastewater from chemical plants, sodium pentachlorophenate, and pulp bleaching were also important sources of dioxin emission. Open burning of e-waste as well as diesel-fueled and leaded gas-fueled vehicles were additional possible sources of dioxin. In contrast to other countries, in China, flue gases from incineration of municipal waste, hazardous waste, and medical waste might be minor sources of dioxin emission. [Copyright &y& Elsevier]

Sinter has been introduced into the composite burden of the COREX ironmaking process in China to lower the material cost, but the proportion is limited due to its poor low-temperature reduction degradation performance in the shaft furnace. This work dealt with the preparation of sinter for the COREX process by varying the MgO content and basicity. Their effects on the sintering and reduction properties under reducing condition simulating COREX shaft furnace were investigated, and the changes in the mineralogy of sinter with different MgO content and basicity were explored. The results showed that increasing MgO content affected the sinter strength and solid fuel consumption but restrained reduction degradation of sinter in the shaft furnace. In the basicity range of 0.8–2.6, the strength, RDI+6.3 and RDI+3.15 of sinter all presented a V-shaped curve and the minimum value occurred at a basicity of approximately 1.6. By comprehensive consideration, sinter with 2.35%+ MgO and 2.2+ basicity for COREX process was proposed and verified in industrial tests. Sinter with higher MgO content contained less SFCA and hematite, while glass and SFCA were dominant in the binding phase in sinter with low basicity (0.8) and high basicity (2.6) respectively and were associated with the relatively higher sinter strength. The changes in the mineralogy of sinter determined the variations of RDI of sinter with different MgO content and basicity, by affecting the sinter strength and the probable reduction of inner stress. [ABSTRACT FROM AUTHOR]