No abstract

According to the experimental results of hot metal dephosphorization by CaO-based slags at a commercial-scale hot metal pretreatment station, the collected 16 models of equilibrium quotient k P or phosphorus partition L P between CaO-based slags and iron-based melts from the literature have been evaluated. The collected 16 models for predicting equilibrium quotient k P can be transferred to predict phosphorus partition L P . The predicted results by the collected 16 models cannot be applied to be criteria for evaluating k P or L P due to various forms or definitions of k P or L P . Thus, the measured phosphorus content [pct P] in a hot metal bath at the end point of the dephosphorization pretreatment process is applied to be the fixed criteria for evaluating the collected 16 models. The collected 16 models can be described in the form of linear functions as y ¼ c 0 þ c 1 x, in which independent variable x represents the chemical composition of slags, intercept c 0 including the constant term depicts the temperature effect and other unmentioned or acquiescent thermodynamic factors, and slope c 1 is regressed by the experimental results of k P or L P . Thus, a general approach to developing the thermodynamic model for predicting equilibrium quotient k P or phosphorus partition L P or [pct P] in iron-based melts during the dephosphorization process is proposed by revising the constant term in intercept c 0 for the summarized 15 models except for Suito's model (M3). The better models with an ideal revising possibility or flexibility among the collected 16 models have been selected and recommended. Compared with the predicted result by the revised 15 models and Suito's model (M3), the developed IMCT-L P model coupled with the proposed dephosphorization mechanism by the present authors can be applied to accurately predict phosphorus partition L P with the lowest mean deviation d L P of log L P as 2.33, as well as to predict [pct P] in a hot metal bath with the smallest mean deviation d ½%P of [pct P] as 12.31.

No abstract

The Qinghai-Tibet Plateau is the highest geographical unit in the world. Thus, it serves an important role in evaluating long-term ecologic conditions and environmental status and changes over time. This study summarizes major and trace element concentrations in biota and in water and soil. It also pays attention to gaseous pollutant and particle concentrations in air around the Qinghai-Tibet Plateau. The degree of soil heavy metal contamination and the water heavy metal hazard index were respectively evaluated. The contamination degrees of two sampling areas around the Qinghai-Tibet Plateau reached extremely high levels with soil mC d (modified degree of contamination) values exceeding 20. Surprisingly, over 54% of sampling areas showed moderate or more serious soil contamination degree (mC d N 1.5). Moreover, the hazard indexes of two important rivers were 1.56 and 7.59, reaching unacceptable level. The potential risk might be beyond our expectation. Therefore, it should be an urgent and top priority to identify and confirm possible pollution sources around the Qinghai-Tibet Plateau. Then, it is imperative to implement feasible and effective environmental quality control strategies.