Mineral Concentration
The concentration of dissolved calcium and magnesium ions in industrial process water governs the chemical behavior of surfactants and sizing agents used in paper manufacturing. Correct water hardness is essential for stabilizing deinking processes and ensuring that chemical collectors precipitate correctly to remove printing ink. This parameter is measured as equivalent calcium carbonate and must be monitored closely to maintain system chemistry.
Soap Precipitation
Soluble fatty acid soaps require a specific level of hardness to transition into insoluble calcium soaps, which are necessary for the flotation deinking of recovered paper. If the process water is too soft, the soap does not precipitate and generates excessive foam that carries usable wood fibres into the waste stream. Conversely, when the water is excessively hard, the premature precipitation of chemicals reduces their cleaning power and leads to the formation of scale on pipes and paper machine wires.
Process Stability
Maintaining the mineral level within a narrow range prevents fluctuations in chemical efficiency and sheet brightness. Mills use chemical additives or water softeners to adjust the ionic concentration depending on the source of the incoming water. This continuous adjustment protects the machinery from deposits while securing the optimal recovery of high-quality cellulose fibres.
