Application Advantages of Iron-free Aluminum Sulfate in Papermaking

In the papermaking industry, anhydrous aluminum sulfate is often used as an additive. Why choose anhydrous aluminum sulfate over regular aluminum sulfate? Below are its advantages:

1. Allows the addition of low-cost calcium carbonate fillers, which not only reduces production costs and improves paper whiteness and fold resistance, but also overcomes the unavoidable drawbacks of synthetic sizing agents (such as AKD), such as slipping and difficulty in controlling sizing degree.

2. Significantly enhances retention and drainage of pulp.

3. Appears white in color with extremely low iron content, meeting the requirements for producing high-quality paper.

4. Improves various paper performance indicators to varying degrees, except for breaking length.

5. As a pre-hydrolyzed product of aluminum chloride, its hydrolysis degree is relatively low, causing a smaller decrease in pulp pH compared to aluminum sulfate.

6. Conventional industrial aluminum sulfate is only suitable for acidic sizing, while iron-free aluminum sulfate can be used in both acidic and neutral environments, significantly reducing system corrosion and making wastewater treatment easier.

7. Poly aluminum chloride (PAC) can maintain a high positive charge even in neutral or alkaline conditions, unlike aluminum sulfate, which quickly forms Al(OH)₃ precipitates. Due to its pre-hydrolysis, PAC does not significantly lower the system's pH.