How do I increase the scrap copper value?

Sort your copper so it isn't classified as an undesirable grade of copper at the scrap yard. 

Purchase futures contracts for 350 million metric tons

Add shards of diamonds.

All you can really do is remove any elements that aren't actually copper.

For example bare copper wire is worth more than insulated copper wire because the recycling yard has to spend time and money stripping the rubber insulation off the wire before they can melt it down.

Copper pipe that has sections that have been soldered with lead based soldering are worth less than sections of pure copper pipe - again because they have to spend time and effort cutting out the sections that have been contaminated with lead so they don't contaminate an entire batch of copper.

Add more copper or wait until the market price increases.