Common refractory bricks are refractory materials made of refractory clay or other refractory raw materials, and are generally light yellow or brown. It is mainly used for building smelting furnaces, which can withstand high temperatures of 1580°C-1770°C, and is usually called firebrick. It is a refractory material with a certain shape and size. According to the preparation process, it can be divided into fired bricks, non-fired bricks, fused bricks (fused cast bricks), refractory and heat insulation bricks; according to the shape and size, it can be divided into standard bricks, ordinary bricks, special-shaped bricks, etc. It can be used as high-temperature building materials and structural materials for building kilns and various thermal equipment, and can withstand various physical and chemical changes and mechanical effects at high temperatures. For example, refractory clay bricks,high alumina bricks, silica bricks, magnesia bricks, etc.
There are many factors that affect the plasticity of clay. One is the generation age, mineral type, crystal form and crystallinity of clay minerals. Kaolin composed of kaolinite with high degree of order has low plasticity; kaolin composed of kaolinite with low degree of order is the opposite. In addition, the particle size, cation exchangeability, and exchangeable cation types of clay all affect its plasticity. In actual production, the main methods to increase the plasticity of raw materials are:
1. Select materials and remove non-plastic impurities, such as quartz, etc.;
2. Grind the selected materials finely to increase their dispersion;
3. Add an appropriate amount of plastic binder, such as pulp waste liquid, dextrin, etc.;
4. Vacuum extruding the mud;
5. Extend the material trapping time.
Binding of raw materials refers to the combination of clay-based raw materials and non-plastic raw materials to form plastic mud masses and have certain drying strength capabilities. The binding properties of the bonded clay are usually reflected by the amount of standard quartz sand (particle composition 0.25—0.15mm accounting for 70%, 0.15—0.09mm accounting for 30%) and the flexural strength after drying to form a plastic mud mass. . Generally, clays with strong plasticity have strong binding capacity (there are exceptions, such as Nanning ball clay is very pure, fine-grained, and has good plasticity. However, due to its large surface energy, it absorbs more water and syneresis during drying, resulting in more fissures. The dry strength is poor. Its plasticity index can reach 36-47, while the flexural strength is only 0.48Mpa.
Construction procedures for refractory brick masonry:
Construction procedure of dynamic furnace
1. Dynamic kiln masonry can only be carried out after the kiln single machine has passed the acceptance test without load.
2. The basic procedure of masonry
The selection of the starting point should be from the hot end to the cold end or from the low end to the high end in order to clean up the line and select the bricks. According to the cold and hot sections, different materials of refractory bricks should be used. If the qualified bricks have anchor nails or supporting bricks If there is an insulation layer (such as calcium silicate board, etc.), the insulation layer must be installed and used first. The mortar should match the refractory brick. The expansion gap of the brickwork should be matched The reservation and filling.
Construction procedure of static furnace
Starting point selection (generally choose bottom-up, self-heating end to cold end sequence) layout and marking (generally the lower end of the tuyere or inspection opening, etc. as the benchmark) selection of bricks (select different materials and different shapes of refractory bricks according to different parts of the equipment ) Weld anchor nails and bracing boards according to the drawing requirements. If there is a heat insulation layer, the insulation layer should be installed first, and the mortar should be prepared and used. The material of the mortar should match the refractory bricks. Reservation and filling of expansion joints for arch tires.