Sentence Correction (SC) | Leaching, the recovery of copper from the drainage water of mines, as

Perhaps I can help clarify the trouble people are having with past perfect ("had been") vs. simple past ("was").

First, past tense does not necessarily mean that something is no longer true. For instance, I might say "When I was a child, I wanted to grow up fast because my brother was so much older than me." This doesn't mean that my brother is no longer older (thankfully, I still have my brother!). I am just talking about him in a past context. It would be wrong
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