Survey of Pitch Control in Newsprint Mills Using Pine, 1995 Papermakers Conference Proceedings

Dr. William E. Smith, Technical Director Calgon Corporation In newsprint operations where pine is a major component of the mechanical pulp, pitch problems are seasonal in nature. This is true in not only the Southern United States but in the Northwest and other regions of the country. Heavy rains can disrupt flow of wood to the mill, which is many times attempting to store minimal quantities of wood for inventory cost reasons. As a result, the TMP or groundwood operations cycle from very green wood to somewhat seasoned wood. This places a demand for pitch control chemistry to cycle with the intensity of the problem, in order to be cost effective. Added to the above stated problem is the fact that in the winter season the temperature of the basic raw material, chips or bolts of wood, decreases. This means that at the point of attrition in the grinders or TMP refiners, the low temperature of the wood extractives retards complete emulsification. Emulsification is achieved by high shear degradation of pitch droplets in the presence of water and colloid stabilizers. This paper will examine how practical changes in operations can address the problem areas listed above to achieve a balance of wet end chemistry that will make the papermaking operation more efficient...