Method of refining a melt of aluminium scrap melt and aluminium alloy obtained from the refined melt

摘要

A method of refining a melt of aluminium scrap material which comprises metallic aluminium and impurities including iron, in order to obtain a target iron level, comprises(i) determining the initial amounts, in % by weight, in the melt of Mn, Fe and Si, these amounts being [Mn₀] , [Fe₀] and [Si₀]; and(ii) adding a quantity Mn_x of Mn to the melt, so as to obtain in the melt, after the refining of the melt, a ratio δ given by$\mathop{\mathrm{image}} \[ {\text{δ = [Mn}}_{\text{1}}{\text{]/ [Fe}}_{\text{1}}\text{]} \]$ wherein [Mn₁] and [Fe₁] are the amounts in % by weight of Mn and Fe after the refining of the melt, [Fe₁] being the desired target level of Fe and [Mn₁] being given by$\mathop{\mathrm{image}} \[ {\text{[Mn}}_{\text{1}}{\text{] = A - B * [Fe}}_{\text{1}}\text{]} \]$ wherein$\mathop{\mathrm{image}} \[ {\text{1.86-0.17 * [Si}}_{\text{0}}{\text{] + 0.004 * [Si}}_{\text{0}}{\text{]}}^{\text{2}}{\text{A 2.21 - 0.17 * [Si}}_{\text{0}}{\text{] + 0.005 * [Si}}_{\text{0}}{\text{]}}^{\text{2}} \]$ and$\mathop{\mathrm{image}} \[ {\text{0.42 + 0.50 * exp (- 0.28 * [Si}}_{\text{0}}{\text{]) B 0.57 + 0.50 * exp (- 0.28 * [Si}}_{\text{0}}\text{]).} \]$;The added quantity Mn_x of Mn is given by$\mathop{\mathrm{image}} \[ {\text{Mn}}_{\text{x}}{\text{= δ * Fe}}_{\text{0}}{\text{- Mn}}_{\text{0}} \]$ wherein Fe₀ and Mn₀ are the initial quantities of Fe and Mn in the melt.;Thereafter the method comprises homogenizing the melt by heating, cooling the melt and maintaining it at a super-eutectic holding temperature so that solid intermetallic compounds form, and separating the solid intermetallic compounds.