1. Production techniques of the direct method:
Using zinc concentrate as a raw material, after high-temperature oxidation roasting to remove impurities such as lead, cadmium, and sulfur, coal (as a reducing agent) is added and compressed into a mass, and then reduced at high temperature in the furnace to make the Zinc steam and oxygen introduced into the air oxidize to form zinc oxide. Direct method The product quality of zinc oxide is not only related to the quality of the technology and zinc concentrate used, but also to the quality of coal, because the volatilized zinc vapor is directly affected by coal combustion products. The content of zinc oxide produced by direct method art is generally between 90% and 95%.
2. Production techniques of the indirect method:
Put the zinc slag or zinc ingot in a high temperature resistant crucible and heat it to 600~700℃ to melt, then convert it into zinc steam at a high temperature of 907℃ (usually around 1000℃), and then conduct hot air It is oxidized, and the zinc oxide produced is cooled and separated by a cyclone, and then the fine particles are collected with a cloth bag. The zinc oxide obtained in this way is the indirect zinc oxide. The quality of the indirect zinc oxide product and the heavy content of the zinc slag and zinc ingot raw materials used directly affect the heavy content of the product. The content of zinc oxide produced by the indirect method is 99.5%~99.7%
3. Production technology of wet process:
Wet method is divided into: acid method and ammonia method.
Zinc oxide produced by acid method is made of zinc sulfate or zinc chloride as raw materials. After removing impurities, adding sodium carbonate solution to form basic zinc carbonate precipitation, after rinsing, filtering and drying, the resulting powder is roasted The zinc oxide obtained. The obtained zinc oxide has a relatively large surface area, and is called active zinc oxide.
The zinc oxide produced by the ammonia method uses zinc hypoxide as the raw material, adding ammonia water and leaching at a certain temperature for one hour, adding a certain ratio of ammonium bicarbonate to the reaction for two hours, adding sodium sulfide to remove impurities Add metal zinc powder for replacement, remove all the replaced metal and mixed salt through filtration, and finally evaporate and roast to obtain zinc oxide.
