High cash prices have led futures prices to rise, but the gains are overdone. Those who want to import may draw metal from warehouses in South Korea, which would only take a week to reach China.
Overall, the push from speculators is the main driver for higher copper prices.
Given such high copper prices, no traders dare to put on short positions, and that's why volume reduced. Some traders pulled investments from copper into aluminum, betting gains in aluminum might be bigger.