保护渣对连铸二冷水中氟含量的影响

Influence of continuous casting mould powder fluxes on fluorine content in secondary cooling water

调查了使用不同氟含量保护渣时连铸二冷水中F-质量浓度的变化，并在实验室研究了保护渣组分及保护渣在水中的浸泡时间对水浸液中F-质量浓度的影响．研究结果表明，A厂使用低氟保护渣，二冷水中F-质量浓度增幅为1．2～24．3mg·L^-1水样呈中性；B厂使用高氟保护渣，二冷水中F-质量浓度增幅为57．9mg·L^-1，水样呈酸性．保护渣中氟含量越高，保护渣在水中的浸泡时间越长，渣中氟向水中的转移量就越多．控制保护渣中氟不超过2％，有利于减弱保护渣氟的浸出对二冷水的危害．在研究的组成范围内，碱度CaO／SiO2和Li2O对渣中氟的浸出无明显影响．增加保护渣中B2O3含量，有利于降低保护渣中氟在二冷水中的浸出．

Under the use of mould fluxes with different fluorine contents, the change of fluorine ion （F-） concentration in the continuous casting secondary cooling water was investigated in two plants. An experiment was also conducted to understand how the components and the soaking time of fluxes influence the F-concentration of leaching water. The results showed that, when a flux with low fluorine content was used in Plant A, the increase of F- concentration in the secondary cooling water was 1.2- 24.3 mg· L^-1, and the water behaved in neutrality. While in Plant B, a flux containing high fluorine was used, the increase of F- concentration in the secondary cooling water reached at 57.9 mg· L^-1, and the water behaved in acidity. The higher the fluorine content in the fluxes was and the longer the soak time of the fluxes in the water was, the more the fluorine would transfer into the water. Controlling the fluorine in the fluxes less than 2 % in mass fraction was helpful to reduce the hazard effects of the mould fluxes on the secondary cooling water. In the researched composition ranges, the basicity （CaO/SiO2） and the Li20 content had not an evident influence on the leaching of fluorine. Increasing the content of B2O3 could reduce the leaching of fluorine from the mould fluxes into the secondary cooling water.