Refractory Materials for Sintering of Iron Ore Concentrates
Refractory materials are essential components in the sintering process of iron ore concentrate, which involves intense high temperature heating to form products with desired properties. The challenges in this process arise from the extreme temperatures and the wide range of chemical forces in the reaction zone. This article will discuss the properties and applications of refractory materials used in the sintering of iron ore concentrate and the methods for their protection during the process.
Refractory materials play a vital role in the sintering process, primarily by providing a skeleton material to support the iron ore concentrate during sintering along with other components like reducing agents and binders. The refractories must have a high melting point, good thermal insulation properties and should be able to withstand the chemical attack of the sintering process. The high melting point allows the refractory to act as a heat barrier so that the temperature in the reaction zone remains at the desired level and the thermal insulation property prevents the heat from escaping and keeps it in the reaction zone. In addition, the refractory materials should have good spalling and thermal shock resistance characteristics, especially when molten slag is used in the sintering process.
The refractory materials used for sintering of iron ore concentrate can be broadly divided into two types, clay and non-clay refractories. Clay refractories are made from a mixture of clay, sand, and other materials and are used for lining and insulation in the sintering process. The main types of clay refractories used for sintering include fireclay and high alumina materials. The high alumina materials offer an increased level of protection from chemical attack and thermal shocks, and are used for sintering in molten slag environments. Non-clay refractories include magnesia and alumina based, graphite based, and silicon carbide and zirconium carbide materials. These materials have excellent spalling and thermal shock resistance properties and are used when the use of clay refractories is not feasible.
In addition to providing a skeleton material, refractories also protect the sintering process from chemical attacks, especially those caused by molten slag. The refractories must be able to withstand the corrosive and erosive effects of the slag and form a stable and protective layer on the surface of the sintering bed. To help protect the refractories from the corrosive effects of the slag, a slag towel layer is placed between the refractories and the iron ore concentrate. This layer serves as a buffer for the slag, providing a physical barrier and allowing for the release of heat from the reaction zone.
In order to maintain the desired level of protection for the refractory materials, proper maintenance and care should be taken to ensure that their surface remains smooth and free from damaging effects. In particular, the surface of the refractories should be inspected regularly and any signs of wear or damage should be addressed immediately. Additionally, the refractories should be inspected periodically and cleaned thoroughly as needed to remove any dirt, dust or other contaminants that may lead to premature degradation.
In summary, refractory materials are an essential component in the sintering process of iron ore concentrate. The refractories must have a high melting point, good thermal insulation properties, and should be able to withstand the chemical attack of the sintering process. The main types of refractories used for this application are clay and non-clay materials, with clay being used most commonly. In order to achieve the desired level of protection for the refractories, proper maintenance and care should be taken to ensure that their surface remains smooth and free from damage.
