Sodium lignosulfonate is a kind of high molecular electrolyte, its molecular weight is from 1,000-100,000, it has a branched and cross-linked molecular structure, so it has strong decomposition, bonding, crabbing, and is widely used as a reinforcing agent for ceramic blanks and refractory material bonding agent.
A. Application in refractory industry with sodium lignosulfonate and calcium lignosulfonate
When manufacturing refractory bricks and tiles, the use of sodium lignosulfonate as dispersant and binder can significantly improve the operating properties, and has a good effect of water reduction, enhancement, and prevention of cracking.
Regardless of which raw material fired refractories, lignin sulfonate can be added as a binder to produce finished refractories, all of which can meet the international requirements. For example, adding 4%~5% lignosulfonate in the billet can make the refractory bricks with 2.2 times higher tensile and compressive strength, 2.5 times higher cutting strength, 5 times higher impact strength, and, in the production process, it can improve the strength of wet billet, shorten the drying time, and fire the finished products with smooth surface, complete angles, significantly reduced brick cracks, strong and durable. Now, some places directly with sulfite slurry black liquid concentrate for refractory binder, the use of the effect is also very good, and thus reduce production costs, worth promoting.
Combined with corundum, is a kind of aluminum silicon oxygen nitrogen polymer material, both corundum alkali erosion and metal erosion performance and high strength, good resistance to vibration, effectively extending the life of the blast furnace cylinder, the last 20 years of rapid development. Combined corundum is synthesized from corundum, silica powder and alumina fine powder with sodium lignosulfonate as binder and 6 % of water by premixing, mixing, pressing, drying and nitriding. The bonded corundum sintered by sodium lignosulfonate has a dense structure and a strong bond between the corundum particles and the matrix.
Second, applied to the ceramic industry, mostly used in high-temperature ceramics
Lignin sulfonate can reduce the carbon content to increase the strength of raw billets, reduce the amount of plastic clay, good fluidity of slurry, improve the yield of 70-90%, and reduce the sintering speed from 70 minutes to 40 minutes.
Lignosulfonates are mainly used in billets (plasticized billets and slurries), glazes, jointing clay and plaster molds and sagger clay. It can improve plasticity, shorten the aging time of clay, and improve the molding performance. Improve the strength of dry billet, reduce the rate of half-breakage in the molding process, reduce the cracking of the billet, and facilitate mechanical operation. It also can effectively shorten the drying time and reduce the drying deformation. The glaze absorption capacity increases and the glossiness of the finished glaze increases. It can improve the mechanical strength of plaster mold and prolong the service life when pouring plaster mold. The effect of adding small amount is remarkable. Lignosulfonate has good results in the range of 0.1 ~ 0.15%. Drying shrinkage has a certain influence on the quality of ceramic products, and a blank with low drying shrinkage is less prone to deformation defects during firing.
Another great use of lignosulfonates in the ceramics industry is their use in slurries. It gives a good release and a thinner body with less loss of the plaster model. The performance of lignosulfonates with water glass is significantly improved compared to water glass alone in the past.