Copper mining in the United States has been a major industry since the rise of the northern . Later copper mining used improved gravity classification machinery, . The United States is a net exporter of copper ore and copper concentrate.
copper processing . Definition, History, & Facts . Britannica
Copper processing, the extraction of copper from its ores and the preparation of are carried out on special machines that are largely automatic in operation. . In the preliminary stages of manufacture, the copper castings are rolled hot, but.