576
Y. Sakata
Fig. 7 Behavior of Sn in the smelting process
tends to be transferred to the slag. But a part of Sn is also going to the crude lead and
other by-products. Sn is recycled to all over the lead refining circuit including the
sintering process and blast furnace by a certain amount. Eventually, Sn is distributed
51% to the slag, 30% to copper matte, and 19% to speiss and discharged outside the
process.
Sn impacts various processes and has major influence on the purity of electric
lead in the electrolysis process. Since Sn cannot be removed completely in the copper removal casting process at our refinery, Sn contained in the anode is partially
transferred to the cathode in the electrolysis process. In our recent operation, the
Sn content in the cathode is higher than 100 ppm. Sn shall be removed in order to
keep the quality of the electric lead>99.99% as the final product. Harris purification
method shown in reaction (1) is used in the electric lead purification process.
Sn + O 2 + 2NaOH → Na 2 SnO 3 + H 2 O
( 1 )
If the Sn content in the cathode increases, the operation cost is increased by the
higher cost of caustic soda used for purification and the extension of the purification
Y. Sakata
Fig. 7 Behavior of Sn in the smelting process
tends to be transferred to the slag. But a part of Sn is also going to the crude lead and
other by-products. Sn is recycled to all over the lead refining circuit including the
sintering process and blast furnace by a certain amount. Eventually, Sn is distributed
51% to the slag, 30% to copper matte, and 19% to speiss and discharged outside the
process.
Sn impacts various processes and has major influence on the purity of electric
lead in the electrolysis process. Since Sn cannot be removed completely in the copper removal casting process at our refinery, Sn contained in the anode is partially
transferred to the cathode in the electrolysis process. In our recent operation, the
Sn content in the cathode is higher than 100 ppm. Sn shall be removed in order to
keep the quality of the electric lead>99.99% as the final product. Harris purification
method shown in reaction (1) is used in the electric lead purification process.
Sn + O 2 + 2NaOH → Na 2 SnO 3 + H 2 O
( 1 )
If the Sn content in the cathode increases, the operation cost is increased by the
higher cost of caustic soda used for purification and the extension of the purification