The Manufacturing Method of Zinc Powder

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Zinc powder is dark grey, with strong covering power and can be used to make pigment. It has very good rust protection and resistance to atmospheric corrosion, and is usually used to produce antirust paint and strong reducing agent, etc. Generally, the zinc powder is manufactured from the zinc metal material. In coating industry, apart from tinting strength and covering power, zinc metal is also the preservative and brightening agent in coating. Below is the introduction about the preparation of zinc metal powder.

The materials used to manufacture zinc powder include zinc ingot, zinc deposition, and other zinc-containing materials. Zinc powder has negative standard electrode potential, larger specific area and chemical activity, which is usually utilized as displacer in the metallurgy and chemical engineering. Many zinc hydrometallurgy factories are equipped with zinc powder preparation workshop to produce zinc powder for self-use. It can also be used as the raw materials of coating and medicine. The commonly-used preparation methods of zinc powder are air atomization method and waterpower atomization method.

The steps of manufacturing zinc powder by air atomization method are as follows: firstly, melt the zinc ingot, the zinc precipitated after electrolysis, or the zinc granule obtained by processing dross of zinc casting in the electric furnace or flame furnace. The melted zinc liquid is then poured into a heat-retaining graphite container maintaining a temperature of about 823K. Liquid zinc takes the form of small streams flow at constant pressure on apertures of 2 to 3 mm at the bottom of the graphite container, and jetting with the 0.49-0.59MPa compressed air through the nozzle that is installed 120mm to 150mm perpendicular to the zinc trickle. The zinc trickle will be atomized into zinc powder. Next, collect them with bag filter, then, screening and grading.

Spray gun process is the improved version of air atomization method. By taking advantage of the special nozzle, the zinc liquid is sucked out through the 10mm diameter quartz siphon, and forcibly atomize and condensate into zinc powder. The production capacity of spray gun process is twice of the air atomization method, but with only half of the air consumption. The quality of the zinc powder is also improved.

The manufacturing of zinc powder by waterpower atomization method is a process of discharging the melted zinc into high-pressure (19.6MPa) atomized water flow through the bottom holes of graphite container and pulverizing. The atomizer is made of several nozzles, and the flow rate of the zinc liquid is 60kg/min. The volume flow rate of water and zinc is 4 to 1. After the grading of the zinc powder paste, it is used as a displacer in the form of thick liquid. The test shows that: the particle of zinc powder by air atomization method is smooth sphere; while the surface of the zinc powder by waterpower atomization method is rough and uneven. The superficial area of this zinc powder is twice of the zinc powder close in average diameter made by air atomization. Due to the fact that the waterpower-atomized zinc powder has large superficial area and the high activation because of the absence of oxidation film, the consumption is 30% less than that of air atomization in zinc sulfate solution to displace and remove cobalt (Please refer to the purification of zinc sulfate solution).

TTT metal powder supplier reminds you that CNS classifies zinc powders into 4 grades from FZn1 to Fzn4 according to different qualities in order to meet different uses. In zinc hydrometallurgy factories, the particle size of zinc powder for self-use is 124μm-175μm, containing over 98% zinc. Its quality is slightly lower than zinc powder commodity.