Inside a new HP laptop, the copper in its heat sink comes straight from old HP devices—making the company the first to reuse its own recycled metal in a closed loop. In partnership with HP, the New Zealand-based startup Mint Innovation took in circuit boards from thousands of old HP computers and servers, and then recycled them to supply pure refined copper back to the company. The process is designed to be more sustainable than traditional smelting. Instead of melting down metals in a furnac...