vase rafineerimisprotsess sulatusprotsessi lõpustaadiumis vase oksiidide taandamise eesmärgil; taandajatena kasutatakse gaase, nt maagaasi, ammoniaaki jms, a metallurgical reduction method employed in the purification copper which contains copper oxide as an impurity; in reduction is primarily involved reducing gas mixtures, normally natural gas, ammonia etc