How To Use Iron Free Aluminum Sulfate For Paper Sizing?

Iron free aluminum sulfate is a chemical product that is soluble in water but insoluble in ethanol. The appearance is a crystalline state. There are generally 12-18 types of crystalline water, divided into industrial grade and iron free grade. The aluminum oxide content is mainly above 15.89% and 16%. It is an indispensable part of the papermaking industry. It is also widely used in water treatment. So, how should we use iron free aluminum sulfate for paper sizing? Now, let's take a look together.
Iron free aluminum sulfate is commonly used as a precipitant in papermaking (sizing). The dissolved solution is acidic and has a certain degree of corrosiveness. There should not be too many impurities in the product, especially iron salts, which can cause chemical reactions with dyes and rosin gum, thereby affecting the color of the paper. In the application of glue, its quality standards mainly require an iron content of less than 0.6%, a water insoluble content of less than 0.3%, and no iron free aluminum sulfate.
The amount of iron free aluminum sulfate added will have an impact on the pH value of the online slurry. By adjusting the pH value to control the potential, the retention rate and filtration performance of the online slurry can be effectively adjusted. Increasing its quantity can reduce the pH value in the pulp, thereby reducing the adhesion of the pulp and the breakage caused by the adhesive roller of the press paper. When there is a large amount of fuzz in the pressed paper, the amount of iron free aluminum sulfate can be increased appropriately, but not too much, otherwise the paper will become brittle. We usually control the pH value between 4.8 * 5.4.
The main methods for dissolving iron free aluminum sulfate are cold melting and hot melting. The former accelerates the diffusion of bauxite in aqueous solution through circulation to achieve dissolution, while the latter is heating. The dosage is generally determined based on the amount of rosin and water, usually 2-3 times its dosage.
Iron free aluminum sulfate is mainly used as a sizing agent for papermaking and a flocculant for drinking water, industrial water, and wastewater treatment. It is also a raw material for producing artificial gemstones and other aluminum salts, such as ammonium alum, potassium alum, and refined aluminum sulfate. In addition, aluminum sulfate is widely used in the production of clarifying agents, petroleum deodorizing and decolorizing agents, concrete waterproofing agents, paper forging whitening, titanium dioxide post film treatment, and catalyst carriers.