Aluminum salts perform a large range of functions in papermaking. For each of these paper or board-mills there are many options for product selection, optimum addition points and optimum input rates
The main functions of the aluminum compounds
- Removal of detrimental substances / anionic trash
- Improvement of Retention
- Fixation of resin size
- Support of AKD and ASA sizing
- Support of starch fixation
- Sizing-press optimization
- Improvement of dewatering
- Whitewater and waste-water optimization
Rising sensitivity to high chloride and sulfate burdens has become apparent in the paper industry. The reason for NICASAL being particular suitable for a large range of applications in closed and semi-closed water circuits can be found in the chemical structure of the product.
Nicasal contains predominantly Nitrate, which can be degraded via denitrification and contains little Sulfate and no Chloride.
Denitrification: Nitrate —> Nitrite —> Nitrogen
With denitrification microorganisms metabolize Nitrate to Nitrite, which is converted directly afterwards to elemental gaseous Nitrogen. Originally, NICASAL was developed as a Chloride-free PAC alternative to prevent Chloride corrosion. But the product can do even more: Due to the increased degradable Nitrate input, it positively changes the microbiology and prevents the formation of Hydrogen Sulfide (H2S) and organic acids.
In many cases, flocculant action is significantly better than that of comparable PAC products, with parameters such as reaction rate, floc size and floc stability, residual turbidity of the treated water and input quantities, providing convincing arguments in this context.
Two practical examples:
Conversion from PAC to NICASAL in a water circuit for paper production
Diagram 1 shows the plot of concentration of parameters examined in a closed papermaking circuit. In addition to various other benefits for the papermaking process the use of NICASAL in the flotation stage of a whitewater cleaning system gave a significant improvement in cleaning performance combined with a severely reduced salt burden, as can be seen from the trend in chloride concentrations. In addition to improved elimination of turbidity from 900 to below 500FNU, COD reduction better by an average of 30 % was also observed. Denitrification started after only five days and residual nitrate burden stabilized at below 30 mg/l. Nitrite could be detected only shortly. NICASAL achieved significant optimization improvements in both cleaning efficiency and mastery of chloride problems.
Example 1: Conversion from Polyaluminumchloride (PAC) to NICASAL
Example 2: Conversion from Aluminumsulfate to NICASAL
- Runability and product quality were stable
- Water system is now cleaner with NICASAL
- Less turbidity, conductivity and hardness
- Chemical additives could be reduced with NICASAL
- Rosin dispersion, starch, retention aid and Biocide
- Overall chemical additives cost top layer down by 15 %
- It is not the cost of the aluminum salt that determines the success of the project, but the total costs
The use of polymeric aluminum compounds, especially those of aluminum nitrate sulphate NICASAL, relieves the wet-end system and wastewater in paper and board mills. In addition to the very good fixation of fines, filler and anionic trash, the minimization of salt loads is in the foreground. This relief of the water systems often leads to significant production improvements and cost reductions.
In certain cases, combinations with other chemical additives are useful. Our NICASAL product line therefore meanwhile includes a large number of different products for use in fresh water, wastewater or in the wet-end of the paper machine.
We gladly support you on site with extensive investigations to optimize your water system.