The linings of alkaline recovery furnaces in paper mills are often exposed to frequent temperature changes, black liquor injection, and high-speed erosion by various dusts and exhaust gases. Magnesium chrome bricks have excellent fire resistance, high temperature strength, and alkali resistance. It also has excellent slag erosion properties and has long been preferred as a lining material for alkali recovery furnaces. However, chromium-containing refractories can cause serious harm to the environment during use. Among them, Cr3+ gradually changes to Cr6+ under alkaline conditions. Cr6+ is carcinogenic. Considering the factors of environmental protection, the use of chromium-containing bricks should be avoided in order to reduce environmental pollution.
Usually, people are accustomed to calling magnesia-aluminum spinel (MgAl2O4) spinel for short.
Spinel refractories made from magnesium oxide and alumina have high refractory properties, and magnesium-aluminum spinel bricks are common.Spinel also has strong corrosion resistance against reducing atmospheres, free SO2/SO3, and free K2O/Na2O. At the same time, magnesia-aluminum spinel also has excellent thermal shock stability and wear resistance, and magnesium-aluminum spinel also has excellent corrosion resistance. The high melting point, low coefficient of thermal expansion, and high hardness make magnesia aluminum spinel an indispensable refractory material. Magnesium-rich spinel with a mass fraction of Al2O3 of 47% has good resistance to slag permeability and slag erosion.Spinel refractory materials can be a good choice for replacing the magnesia chrome bricks.
Andalusite has excellent high-temperature volume stability and melting resistance, and is easily transformed into mullite. Andalusite raw material can be used directly without calcination. Therefore, andalusite brick refractories can be widely used in applications requiring high thermal shock resistance and high temperature strength.
Corundum refractories refer to refractories with an Al2O3 content of 90% or more and a main crystalline phase of α-Al2O3. Corundum refractories have the characteristics of high thermalstrength, good thermal shock and abrasion resistance, good chemical stability, and strong ability to resist the action of reducing agents.
Choosing chromium-free refractory materials to replace the original magnesia chrome bricks can better protect the production environment.Fireramo can produce different kinds of refractory products including the magnesia spinel bricks, andalusite bricks, corundum bricks and other kinds of refractory mateirals
Specializing in refractory materials for over 20 years, we provide professional refractory solutions for the global high temperature industry.