Dissertation > Industrial Technology > Metallurgical Industry > Nonferrous metal smelting > Heavy metals smelting

Zinc Electrowinning with the preparation and properties of new lead-based alloy anodes

Author CaoYuanDong
Tutor GuoZhongCheng
School Kunming University of Science and Technology
Course Non-ferrous metallurgy
Keywords Lead-based alloys Anode Zinc Electrowinning Aluminum peptide boron Electrochemical properties
Type Master's thesis
Year 2009
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The zinc electrowinning industries, is widely used Pb-(O.8 1)% Ag alloy as the anode, its dominance is not yet completely replaced. Because silver is an expensive metal, has long been metallurgy workers has been committed to research by the addition of other alloying elements in the case does not affect the overall performance of the lead-silver alloy to reduce the silver content in order to achieve cost savings. Elements such as Ca, Sr, RE been shown to enhance the overall performance of the lead-silver alloy, and to make up for the loss of silver. Immiscible based alloys have excellent properties, such as lead and aluminum complementary good performance, it is based on this point, this research lead alloy aluminum titanium boron alloy and pass the test alloy mechanics join anti-corrosion, and electrochemical properties of aluminum to explore the performance of lead-based alloy anode, access to literature, no relevant reports. First, through the analysis of lead - aluminum phase diagram, discusses the thermodynamic and kinetic conditions required to get uniform composition lead alloy. The gravity casting method, a lead-silver, lead-calcium, lead and rare earth intermediate alloy prepared under certain conditions, and finally formulated into a standard alloy, Pb-1% Ag, Pb-0.15% an Ag-0.11% Al, Pb-0.15% Ag, Pb-0.11% Al, Pb-0.3% Ag-0.06? -0.05? alloy anode. Through metallographic observation lead-based alloys and found that the addition of the aluminum-titanium-boron alloy, refined grains of lead, aluminum was the second phase distributed in the form of lead-based body, there is a larger segregation. Study the mechanical properties of lead alloy hardness, tensile strength, percentage elongation, the results show that the aluminum titanium boron alloy added to improve the hardness of the lead, which adds aluminum-titanium-boron alloy Pb-0.11% Al alloy hardness than pure of lead the high hardness 0.22kg/mm2; hardness than that of the Pb-0.15 of% an Ag-0.11% Al Pb-0.15% Ag high 0.35kg/mm2, Pb-0.11% Al higher than the tensile strength of pure lead 3.2N/mm2 , so as to arrive, aluminum titanium boron added to improve the tensile strength of the lead. Studied in ZnSO4-H2SO4 and ZnSO4-MnSO4-H2SO4 system Pb-0.15% Ag-0.11% Al, Pb-0.15% Ag, Pb-1% Ag, Pb-0.3% Ag-0.06? -0.05? The anode corrosion rate ZnSO4-H2SO4 system polarization 48h anodic oxide film morphology and material composition. The corrosion resistance of the Pb-0.15% Ag-0.11% Al in the above two systems are better than the Pb-0.15% Ag, but compared to the Pb-1% Ag, Pb-0.3% Ag-0.06? -0.05? Alloy resistant poor corrosion. By steady-state polarization curves, cyclic voltammetry, AC impedance study the electrochemical properties of the alloy. Through the the steady anodic polarization draw ZnSO4-H2SO4 system, Pb-0.15% Ag-0.11% Al anodic oxygen evolution potential minimum, showing excellent catalytic activity. By AC impedance analysis shows, Al doping in the lead alloy is conducive to improve the alloy's activity, especially 24h after the anodic polarization Pb-0.15% an Ag-0.11% Al, and Pb-0.11% Al anode surface of the catalytic activity.

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