Production steps of silica gel desiccant
Silica gel desiccant is a highly active adsorption material and is the most commonly used desiccant. Belongs to amorphous substance. The silica gel desiccant has strong moisture absorption capacity and strong adsorption performance. Even if the silica gel desiccant
is completely immersed in water, it will not soften or liquefy. It is non-toxic, tasteless, non-corrosive and non-polluting, so it can be in direct contact with any object.
The raw materials that need to be prepared for the production of silica gel desiccant
are: sodium silicate (sodium silicate, water glass) and sulfuric acid.
1. Prepare the alkali and acid in advance, then melt the solid sodium silicate at high temperature and filter to prepare a certain concentration of liquid, and then prepare a certain concentration of liquid with sulfuric acid, the sulfuric acid concentration is 20%.
2. The second step is gel preparation (gel granulation). This step is the most critical. The pre-prepared soaking lye and sulfuric acid are reacted under specific conditions to form a lytic gel solution to achieve a proper After concentration, it will become gel particles. The shape and size of the particles can be determined according to the needs of users and production capacity. The common method of gel granulation is air granulation. The acid-base ratio, concentration, temperature and gel granulation time of the gel are the specific process parameters of the gel granulation process.
3. The aging gel needs to pass a certain time and temperature, as well as the pH value to aging, which makes the gel skeleton strong. During the aging process, the glue between the particles condenses to form Si-O-Si bonds, which enhances the strength of the skeleton, and the particles are close to each other and shrink. The space in the grid structure and part of the water contained in it is squeezed out.
4. Pickling, water washing, and glue washing
Pickling, water washing, and gel washing are also very important steps in the process, because the Na2SO4 formed by the granular gel is washed away. Control each anion and cation to the range of process requirements.
5. Desiccant, put the prepared hydrogel (after washing) into the drying room, and under specific conditions, reduce the water content of the gel itself and dry it to the required range. The higher the drying temperature, the greater the speed of primary particle aggregation and the larger the pore size.
6. Screening: Use a ball sorter to filter the dried silica gel through screens of different apertures according to a certain particle size, and screen out the broken silica gel at the same time.
7. Glue picking: After picking out the heterochromatic balls and impurities in the silica gel, they are packed with composite paper as required, and then sealed.