Copper Blocks, added by IC2, have no true uses except for storage/decoration.
Storage Saving Application
If you have too much Copper, then you can take 9 Copper Ingots to create a Copper Block to save space in Chests. You can then convert the block back into 9 Copper Ingots with no loss. It takes 576 Copper Ingots to create one full stack of Copper Blocks, going from 9 full stacks of Copper Ingots into only one stack of Copper Blocks. This is true for all other metal blocks, such as Iron or Tin Blocks.