Sulfate Concentration in Galvanizing Preflux .

1.0   Purpose

1.1   To monitor residual sulfate that is carried over into the preflux tank from the acid and rinse tanks.

1.2   To evaluate the rinsing efficiency by the history of sulfate buildup in the preflux tank.

2.0  Additional equipment needed

2.1   Purchase a centrifuge with 10-15 ml centrifuge tubes (2 qty) to perform this test.

3.0   Reagents

3.1   Barium Chloride ( BaCl2) solution is used to precipitate ( milky white solid) Barium Sulfate.   Barium Chloride is toxic wear rubber gloves and safety glasses when handling.  Wash hands when done.  Read MSDS before using.

4.0   Procedure

4.1   Obtain a preflux sample  and let it cool down while the particulate matter settles to the bottom..

4.2   Using the 10 ml (cc) syringe place exactly 3 mls of clear preflux liquid into each of the 2 test tubes

4.3   Using the dropper bottle of Sulfate Precipitation  solution, add exactly 1 drop of Barium Chloride to the first test tube and look for a precipitate  to form.  (cloudy, white ).  Make a note if the cloudy white precipitate was formed.

4.4   Stopper the first test tube that the BaCl2 was added to and invert the test tube several  times.

4.5   Stopper the second test tube and place both test tubes opposite each other in the centrifuge and centrifuge the precipitate to the bottom. ( about 2-3 minutes.)  The solution should be clear to continue.

4.6   Now place 1 drop of Barium Chloride solution in each of the test tubes and look for a precipitate.  ( First test tube should have 2 drops of Bacl2 and second should have one drop of Bacl2)

4.1   Continue this procedure until no additional precipitate is observed when the Barium Chloride is added.  ( Test tube one will show no sign of precipitate first then test tube 2 will follow after another drop of BaCl2 is added)

4.2   Record the drops of BaCl2 used to precipitate the  cloudy BaSO4 for one test tube only.

Note :     The white precipitate can easily be cleaned off the walls of the test tube with

acidic acid or vinegar.

5.0   Calculations

5.1   Every drop of Barium Chloride solution added to the test tube that shows a precipitate  ( Milky white) is  = to 0.1 % wt Sulfate in the preflux tank.