Indirectly processed zinc oxide, as the name implies, indicates that it is a product manufactured through an indirect process.

The indirect method typically uses zinc ingots as raw material, where the zinc ingots are converted into zinc vapor at a high temperature of 1000 °C within a graphite crucible. This vapor is then oxidized by the introduced air to form zinc oxide, which is collected as zinc oxide particles after passing through a cooling tube. Zinc slags can also be used as raw material. The heavy metal content of different zinc ingots and slags directly affects the heavy metal impurity content of the product. While the purity of the produced zinc oxide varies, the purity of zinc oxide products manufactured through the indirect method ranges from 99.5% to 99.7%.

The direct method of zinc oxide processing primarily uses zinc ore, zinc dust, and zinc concentrate as raw materials. It undergoes high-temperature oxidation roasting, followed by coal reduction to produce zinc vapor, which is then oxidized with hot air to obtain zinc oxide. This process yields a product with high impurity content and low purity, generally ranging from 0.75 to 0.95. Indirect method zinc oxide is a metal oxide that exists as white hexagonal crystal or powder at room temperature, with particle sizes of about 0.1-10 micrometers. It is poorly soluble in water but soluble in acids and strong alkalis, as well as in ammonia water and ammonium salt solutions. It is odorless and tasteless, and does not have a sandy texture. Upon heating, it turns yellow and returns to white upon cooling. It sublimes at 1800°C.

Indirect-method zinc oxide is used in industries such as rubber, sensitive resistors, paints, phosphating solutions, films, and thermal conductive materials. Products with low heavy metal content are also suitable for industries like livestock feed and health care. The molecular formula and chemical structure of zinc oxide are ZnO.