Studies on Pitch Trouble, its Cause and its Measures to be taken for its Prevention XI

On the Action on Pitch Trouble of the pH and Temperatue of, and of the Inorganic Ions occurring in the Water used

Abstract

Pitch trouble varies in magnitude according to the pH and temperature of, and to the inorganic ions present in, the water in which the pulp is in suspension. A study on this problem led to this conclusion :
1) The water in use must be kept very low in pH-acidified if possible-and at 50°C, if the pitch trouble is to be minimized. The trouble begins to increase when the water is at oraround 20°C and to decrease when it is 40°C∼50°C, but such a high temperature renders the operation inflasible in a factory.
2) Of the inorganic substances occurring in ions in the water, Cu, Ca, Mg and Fe aggravate the trouble in no small measure and Na is negligible.
3) The water, when it contains Ca and Cu in ions, must be acidified at pH 6 or less it is to be safely used.
4) A mineral acid or an organic acid is preferable to Al₂ (SO₄) ₃ as an agent to beused for adjustment of the pH of the water, becuase Al₂ (SO₄) ₃ used for the purpose in its originate state enhances the trouble by its own action as an acid.