Why can zinc powder burn automatically

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Zinc powder which is supplied by metal powder supplier will have quick reaction with oxygen as it has big surface area. In fact, the metals which are usually considered to be inert will have obvious change in its properties after being processed into nano-particles, for example, they are spontaneous flammable in the air.

Zinc metal powder also has strong reducibility. When contacting with water, acids or alkali metal hydroxides, it will release flammable hydrogen. It will cause burns or blast when reacting with oxidizing agent and sulfur. Its powder will form explosive mixture with air, which is easy to light by the open fire and will cause blast, besides, the wet dust is easy to release heat and burn in the air. Therefore, the blast caused by the zinc powder will be effectively prevented by avoiding contacting with the damp environment and controlling the stable environment; meanwhile, zinc powder can be also stored with vacuum seal which is placed in the plastic cask and added with drying agent, thus can also prevent the blast. However, zinc powder is stable except for those that have ultrafine particle size of 400 meshes may have the spontaneous combustion danger.