Impact and Control of Inorganic Contaminants on Recycle Fiber Processing, 1996 Pulping Conference Proceedings

K. Keegan, BetzDearborn
A great deal of information has been published on the impact of stickies and other organic contaminants in recycle fiber processing. On the other hand, very little has been presented on the impact of inorganic contaminants. Recycle mills are experiencing increasing deposition of inorganic based materials such as calcium carbonate, calcium oxalate, barium sulfate, aluminum hydroxide and mixed silicates. Process related issues such as water circuit closure, lower quality furnish, and the increased use of silicate based peroxide stabilizers are just some of the factors leading to higher scaling potentials. Inorganic scales often lead to major operational problems requiring extensive shutdowns for equipment cleaning. This panel discussion will present information on the basis of scale formation in recycle mills, the impact of inorganic contaminants on processing equipment, mechanisms for the control of scale formation, and operational experience from recycle mills.