Galvanic industries

The galvanic industry contains degreasing, galvanizing, burnishing and pickling of materials. Depending on the kind and the size of the plant, not all steps are used in one company. Which kind of treatment is used for the several steps, depends on the kind of plant, the used processes and the amount ofprocess water. Below, we introduce treatment methods for several steps in galvanic industries.

Degreasing process

To attach a thin layer of metal on a piece of work it is necessary to have a good carrying capacity. The surface has to be free of oil, dust, fat, water, metal splinters, and chemicals to guarantee the finish. Because of negative effects on the degrease process, it is important to clean the degreasing bath continuously. There are different efficient methods to clean process chemicals. After afiltrationprocess to get out particles,ion exchangersfor cations, anions and surface active agents used to remove dissolved parts of the solution. Alsoultra filtrationis used to remove dissolved particles.

Pickleing

To remove corrosion from the piece of work, strong acids are used. The metal will put into an acid for the reaction. After the process, the rest of the acid has to be removed by water. The water has to be neutralized.

Galvanizing process

The bath where processes happens, has to be cleaned from sludge. The sludge contains metal hydroxides and other compounds, made by precipitation. Depending on the process you find different kinds of metal compounds which can be separated. Especially in galvanic processes where noble metals are used, the sludge is valuable. Generally the sludge will be collected, and treated byelectrolysis, to recycle the metal.

Problematically substances are toxic cyanide compounds, which can be also found in the sludge. The high amount of metal ions in the galvanic bath are also an environmental problem by waste disposal.

Burnishing

这一过程创建一个氧化的影响layer on the surface of the piece of work. For the process the metal will be dunked into an alkaline- oxidizing solution. This process is useful to have a better carrying capacity on the surface. Further, the surface is more resistant against corrosion by dry and wet, basic conditions.

To edit the surface well, several steps of cleaning and flushing prepare the piece of work before burnishing. To give it a finish against腐蚀, the material will be oiled.

Because of the different kinds of production steps, pollutions are various. Neutralization and detoxiation (sodium nitrite) are necessary.

Flushing

Because of flushing after every production step, the amount of flush water is high and polluted by different kinds of chemicals. To treat the water, you have to remove chemicals, acids or basics and also sludge.