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Why is 5N Aluminum so much more expensive than 4N Aluminum?

5N (99.999%) Aluminum and higher purities use 4N Aluminum as the starting raw material and separates the lower grade aluminum from the pure metal. The same two methods – Three-Layer and Crystallization - are used for both 4N and 5N purities, but for 4N production, the waste generated is minimal since the difference from 99.9 to 99.99% is not so great.    Crystallization is the preferred method for 5N production since Three-Layer method adds Copper contamination.  To produce 5N and better purities, energy and processing represent the majority of the cost, and the aluminum raw material is much less portion of the cost since so much of the aluminum raw material is discarded in the process. Higher purities require even more...

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4N (99.99% - 1199 Alloy) Purity

High Purity Aluminum (HPA) is used for many applications due to the purity and conductivity of the various grades of aluminum. 4N (99.99%- 1199 alloy) is the highest purity that can be produced in standard primary aluminum electrolytic production in one of the two main processes:(1) Fractional Crystallization method works by taking advantage of differences in solubility.  This is more expensive process which produces pure metal with particularly low Copper (Cu) content (1 to 3 ppm), while most other elements are reduced in 4N production.(2) Three-Layer method is the lower cost process where the higher purity aluminum segregates from the lower purity aluminum with the addition of trace amounts of Cu, but which results in slightly higher Cu content (20 to 40...

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