Sodium silicate is a high-yield basic raw material in the inorganic silicon compound industry, widely used in industries such as chemistry, papermaking, welding, washing, daily chemical, casting, metallurgy, catalysis, coatings, packaging, etc. Due to the alkalinity of sodium silicate itself, as well as the buffering effect of its aqueous solution on pH value, and the micelle structure of silicic acid produced by hydrolysis, which has the functions of dispersing, emulsifying, suspending ink, and passivating metal ions, sodium silicate has a wide range of applications in deinking paper waste and conventional hydrogen peroxide bleaching.
However, sodium silicate, which is directly used in papermaking, also has shortcomings. In deinking and hydrogen peroxide bleaching applications, silicon scale can form in equipment and pipelines, hindering the flow of slurry, shortening the cycle of shutdown cleaning and replacing equipment components, and reducing production efficiency.
Sodium silicate is relatively stable under alkaline conditions. As the pH value decreases during deinking or bleaching applications, sodium silicate gradually loses its stability and combines with calcium ions in the slurry to form silicate precipitates that adhere to the metal surface, forming a scale layer.
Adding magnesium sulfate or sequentially adding magnesium sulfate and hydrogen peroxide with sodium silicate and sodium hydroxide in hydrogen peroxide bleaching can prevent scaling.
When calcium ions and magnesium ions coexist, sodium silicate preferentially reacts with magnesium ions to form magnesium silicate precipitates. This precipitate is soft, talc like, and does not adhere to the surface of stainless steel. However, calcium silicate precipitates form a scale layer on the metal surface.
In addition, reducing the modulus of sodium silicate by adding sodium hydroxide can also control scaling in waste paper deinking.
The above is the problem of sodium silicate in papermaking application introduced by Chengzhi Industry. We hope to provide you with good help. If you have any doubts or needs, please feel free to come to the website at any time http://www.jinhao360.com Consult us!