Pickling solution

Pickling agent Pickling of steel Pickling solutions Pick s disease Pidoram [1918-02-1]... 

Corrosion. Ammonium bifluoride dissolves in aqueous solutions to yield the acidic bifluoride ion the pH of a 5% solution is 3.5. In most cases, NH4HF2 solutions react readily with surface oxide coatings on metals thus NH4HF2 is used in pickling solutions (see Metal surface treatments). Many plastics, such as polyethylene, polypropylene, unplasticized PVC, and carbon brick, are resistant to attack by ammonium bifluoride. 

The speed of the pickle reaction is also dependent on the concentration and temperature of the pickle, the degree of agitation of either the metal part or the pickle solution, the alloy being pickled, and the acid used. Pickling solutions may be appHed by either spray or immersion techniques. However, because of the noxious fumes emitted, there must be adequate ventilation. Sometimes, particularly when spraying techniques are used, an enclosure to contain the fumes and mist is employed. 

After being cleaned, ware that is to be pickled is immersed successively in one or more tanks of water at 80—95°C and then transferred to the acid pickling solution. The pickling solution of 6—8% sulfuric acid is contained in a stainless steel tank or, alternatively, a lead-lined wooden tank at 60—65°C. 

Consider the metal pickling plant shown in Fig. 6.5 (El-Halwagi and Manousiouthakis, 1990a). The objective of this process is to use a pickle solution (e.g., HCl) to remove corrosion products, oxides and scales from the metal surface. The spent pickle solution... 

In certain tests it is sometimes desirable to eliminate any effects of a mechanically achieved surface condition by chemical treatment or pickling of the surface prior to test. This may be done in a pickling solution alternatively, the test itself may be interrupted after sufficient corrosion has occurred to remove the original surface, the specimen then being cleaned and reweighed and the test started over again. Wesley found it to be desirable to pickle off about 0-008 mm from the surface of specimens in acid to improve the reproducibility of the tests. 

The metal must also be washed free of pickling solution. The resulting rinsewaters contain metal salts. Because of the low concentration of these contaminants the rinses are difficult to treat economically. 

Block B shows the electrolytic copper recovery cell, which recovers metallic copper and regenerates sulfuric acid from the metal salts in the hot sulfuric acid pickle solution. It was originally felt that trace metals (zinc, tin, lead) would interfere with the recovery of pure copper. By controlling current density at 50 to 100 A/m 1 2 3, however, pure copper can be recovered while maintaining the copper concentration in the pickle bath at 15 g/L. 

Pickle solutions that are used in the removal of metal oxides or scales and corrosion products are acids or acid mixtures. 

Hexavalent chromium is used in anodizing baths, and in pickling solutions that remove oxide layers from parts. The chromic acid in these solutions eventually enters the waste stream, either through dragout, or when the pickling or anodizing bath is disposed of. Less... 

Flux brush Pickle solution Copper tongs... 

Copper sheet metal easy silver solder scissors propane torch charcoal block fireproof surface for soldering flux brush pickle solution copper tongs tweezers. (See the list of basic equipment for jewelry making on page 256 for details.)... 

When the solder has flowed, remove the heat, grasp the piece with tweezers, and drop it into the pickle solution to clean it. Remove the soldered piece with copper tongs and rinse with water. 

Photographic printing paper 8.1, 8.3 Pickle solution Demo 6.1 Plaster files 5.4... 

Ortiz, I., Bringas, E., San Roman, M.F. and Urtiaga, A.M. (2004) Selective separation of zinc and iron from spent pickling solutions by membrane-based solvent extraction Process viability. Separation Science and Technology, 39, 2441. 

Electrolytic recovery of iron from pickling solutions using tungsten carbide gas diffusion anodes was studied by Streng et al. [23]. Replacement of Tainton anodes (99% lead and 1% silver) with a gas diffusion tungsten carbide anode led to a 1.5-1.7 V decrease in the cell voltage and a 50% reduction in energy consumption. Unwanted oxidation of ferrous ions to ferric ions did not occur on these gas diffusion anodes, since the cell was operated at a lower potential. 

Tomaszewa, M., Giyta, M., and Morawski, A.W. Recovery of hydrochloric acid from metal pickling solutions by membrane distillation, Sep. Purif. TechnoL, 23(1-3), 591, 2001. 

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