How to improve the durability of refractories for cement ultrafine grinding

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How to improve the durability of refractories for cement ultrafine grinding

With the rapid development and improvement of related technologies and equipment for large-scale pre-decomposition cement ultrafine mill in China, the overall technical level of China’s cement industry has approached or reached the international advanced level, but the overall service life of domestic refractory materials compared with foreign technology There is also a certain gap. The reason for this is that in addition to the level of product research and development of refractory materials manufacturers, it also has a greater relationship with the overall construction level of refractory materials and people’s attention to construction quality.

Through long-term visits to domestic cement production companies, it has been found that most cement companies have the following conditions that restrict the service life of refractory materials: Some cement companies do not pay much attention to the matching of refractory materials and construction, and there is no refractories configuration. Reasonable and repeated shutdown of kiln maintenance. Second, the overall technical level of the domestic refractories construction team is uneven. Third, because most cement companies implement the separation of refractory materials supply and construction, some construction teams know little about the performance and construction requirements of refractory materials and have low levels of specialization. It is difficult to guarantee the construction performance and service life of refractory materials.

The service life and service life of refractories are closely related to the performance of refractories and the quality of construction. In particular, refractory castables are used. Because they are semi-finished materials, the relationship between the use effect and the construction quality is greater. It is called “three-point material, seven-point construction”. Therefore, the construction of refractory materials must strictly follow the construction specifications and control every aspect and every detail. Taking refractory castables as an example, the following details should be strictly controlled during construction:

  • 1. Add water. General fireproof castables will provide a construction instruction after leaving the factory, which clearly specifies the amount of water added to the castable during construction. In actual construction, it is necessary to control the amount of water added during the stirring process (not to exceed the upper limit of the recommended value) to ensure that the castable material has sufficient fluidity, but it cannot allow the castable material to flow. If only for the convenience of construction, the amount of water to be added is not required, the overall performance of the castable will be greatly reduced, which is how much the castable strength changes with the amount of added water.
  • 2. Mixing time. The mixing time of the pouring material is closely related to the amount of water added during construction. Generally, the mixing time is controlled between 3 minutes and 5 minutes, and the stirring speed is above 19 rotations per minute. With the same amount of water added, the longer the mixing time, the better the flowability of the castable.
  • 3. Welding and thermal expansion of anchors. The first step in the welding process of anchors should be to ensure that they are properly arranged and the direction of force is in line with the requirements. At the same time, the stainless steel welding rod used for welding must be performed in accordance with the specifications. The weld should be smooth and full, and thermal expansion of the anchor should be done.

Construction should pay attention to:

  • 1. Template selection and support. No matter whether the formwork is made of wood formwork or steel formwork, it must meet the strength requirements. In the installation process, the size of the drawings must be strictly followed, and the drum die, mold up, and running die cannot occur during the vibration process.
  • 2. Pouring material conservation. Casting material curing time and stripping curing time should meet the specification requirements, generally in the ambient temperature of 5 °C ~ 35 °C case, with mold curing time of not less than 24 hours, stripping curing time of not less than 24 hours before Ensure the early strength of castables.
  • 3. Casting material baking. Before pouring, the castable must be baked. The baking should meet the baking system to ensure that the free water and crystal water in the castable can be fully discharged, so as to avoid the phenomenon of “peeling and bursting” in the early stage of feeding or use, affecting The normal use of castables. For some special parts, separate baking is performed before the whole baking. For some key (such as the front kiln mouth, the kiln hood, the hot section of the cooler, etc.), the bamboo chopsticks can be used to reserve the exhaust hole.

The construction of fire bricks should pay attention to: the correct mix of fire mud, mud saturation, control of the gray seam.

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