Month: April 2021

What is the Bulk Density of Refractory Castables?

KilnRefractory

What is the bulk density of refractory castables? This is mainly based on the specific construction site and high-temperature resistance requirements. The preparation of refractory castables is customized according to the index requirements provided by users. These indicators mainly include refractoriness, material chemical composition, bulk density, compressive strength, flexural strength, and so on. Bulk density or bulk density is one of the important indicators, which intuitively reflects the compactness of refractory products and characterizes the mass of refractory materials per unit volume. It is an important measure of the quality level of refractory raw materials and dense refractory products.

RS Monolithic Refractory Castable Factory
RS Monolithic Refractory Castable Factory

The Significance of the Bulk Density of Refractories

Bulk density is the ratio of the dry mass of the refractory material to the total volume. The higher the volume density, the higher the density. The bulk density of the material has a significant effect on many other properties, such as porosity, strength, corrosion resistance, load softening temperature, wear resistance, thermal shock resistance, etc. For lightweight thermal insulation materials, such as thermal insulation bricks, light weight castables, etc., the bulk density is also closely related to its thermal conductivity and heat capacity. Generally speaking, the bulk density of the material is high, which is beneficial to its strength, corrosion resistance, wear resistance, and load softening temperature.

Therefore, with regard to the volume density of refractory castables, each manufacturer has its own standards. In order to increase the bulk density of refractory castables, a reasonable ratio of multi-stage particles should be adopted, which should meet the requirement of “large at two ends and small in the middle”. That is, under the premise of not affecting the performance of refractory castables, adding fine powder matrix or using silicon powder to replace part of the binder material, reducing the amount of water added to increase its bulk density.

Bulk Density of Refractory Castables

The bulk density of refractory castables is different depending on the location of use. It is mainly divided into two parts, namely dense refractory castable and light refractory castable. Dense refractory castables are used for parts that are exposed to high temperature, molten slag, scouring, and thermal shock stress. The use of castables with high bulk density can improve structural strength, wear resistance, slag penetration resistance, thermal shock resistance, etc. Lightweight refractory castables are only used for the material of the thermal insulation layer close to the furnace shell, with the main purpose of thermal insulation. Its strength is low, density is small, porosity is high, and it can’t touch slag or chemically corroded parts.

The density of dense refractory castables configured by different materials is different. For example, the bulk density of clay refractory castables is 2.1~2.2 g/cm3. The bulk density of high-aluminum refractory castables is generally 2.5~2.85 g/cm3, which increases with the increase of aluminum content. The bulk density of clay low cement castable is 2.2~2.3g/cm3. The bulk density of corundum low cement castable is 3.0~3.1g/cm3, etc.

The lightweight refractory castables configured by different materials are different. For example, the bulk density of lightweight floating bead castables is 0.6~1.0g/cm3. The bulk density of the castable prepared with clay porous clinker is 0.8~1.3g/cm3. The volume density of the castable configured with mullite porous clinker is 1.2~1.6g/cm3, etc.

In short, the bulk density of refractory castables depends on the temperature and location of use. For example, the bulk density of high alumina refractory castable is 2.5g/cm3 or 2500kg/m3, which means that a cubic high alumina refractory castable weighs about 2.5 tons. The bulk density of lightweight castables is 0.8g/cm3 or 800kg/m3, representing a cubic weight of 0.8 tons. The volume density of refractory castables is the specific manifestation of bulk density, and the weight of materials required for construction parts can be calculated through this index. Refractory castables will inevitably be lost during the construction process. In order to prepare all the materials at one time, the total quantity can be increased by about 0.5 tons to avoid suspension due to insufficient construction materials.

Refractory Castable Manufacturer and Sales Manufacturer

This is the introduction about the appropriate density of the castable. I hope it will be helpful to you. If you have any other questions, please feel free to contact us. Purchasing suitable refractory materials for the kiln lining, and looking for a suitable refractory lining material solution, the strength of the Rongsheng refractory manufacturer is your reliable guarantee. Our experienced technical team and our advanced refractory production line have won us many return customers and long-term cooperative customers. If you have any questions about refractory materials or refractory lining materials, please contact us or follow our blog.

Can the Price of Refractory Bricks be Determined by Color?

KilnRefractory

Can the color of refractory bricks determine the price of refractory bricks? is this real? Among the customers I have contacted in the past, I have encountered customers who left messages saying that they want to buy red or black refractory bricks from our manufacturer, as well as those who buy white smooth refractory bricks. Similarly, some purchasing managers are obsessed with buying refractory bricks of a certain color. So can the price of refractory bricks be judged by the color?

Rongsheng Kinds of Refractory Bricks for Sale
Rongsheng Kinds of Refractory Bricks for Sale

After specific communication with customers, they found that some of them are looking at the color of our refractory bricks that are very suitable for the color of their crafts, so they want to buy a certain color of refractory bricks. Their needs are not in line with our goal of serving refractory linings for industrial kilns. And when customers learned that we were providing refractory brick materials for the lining of industrial kilns, they stopped insisting. Among the refractory bricks lined with industrial kilns, the color of the refractory bricks reflects the proportion of the refractory raw materials added to a certain extent and has a certain influence on the properties of the refractory materials. Similarly, it also affects the price of refractory bricks.

The Colors of Some Common Refractory Bricks

People who are often exposed to refractory materials can basically judge the material of refractory bricks based on the color. The color of fireclay refractory bricks is generally light yellow or brownish yellow, dark yellow, and there will be brown or black spots on the surface of the brick. This is generally a spot formed by impurities in the refractory raw material after being fired at a high temperature. The color of high-alumina bricks is mostly beige, and even a little whitish. Refractory brick products made of magnesia, graphite, and silicon carbide are mostly blue. Corundum and mullite are mostly white.

High alumina bricks are often used to judge the quality and grade of bricks by color. In fact, the color of refractory bricks with the same index content will also appear inconsistent. This is because there are many factors that affect the color of refractory bricks.

  • ① The bricks are unreasonably stacked when loading the kiln car, and the sparseness and unevenness cause the flame to not uniformly heat all the bricks. The bricks are heated unevenly during preheating, and the moisture of the refractory bricks cannot be completely eliminated and enters the firing zone, causing some refractory bricks to appear different in color and light.
  • ②The processing temperature of refractory bricks is not well controlled, resulting in too much fluctuation of the firing temperature, which will make some parking spaces have high temperatures and some low temperatures.
  • ③If the pulling force of the smoke exhauster is too large, when the flame cannot reach the top of the kiln, it will be pulled out of the high-temperature zone by the pulling force in a horizontal direction, causing the temperature difference between the top and the bottom to be too large. The temperature difference of the fired refractory bricks can reach 50 degrees so that sometimes the lower part sticks and deforms to produce waste products, but the upper part still does not reach the sintering temperature.

In addition to the influence of the process during the firing process, after the refractory bricks are discharged from the kiln, with the influence of the storage time and storage environment, some chemical reactions will gradually occur on the surface of the refractory bricks, which will eventually cause the color difference of the refractory bricks.

There are more factors affecting the appearance and color of fused-cast refractory bricks, such as the oxidizing atmosphere and reducing atmosphere when the batch material is melted, and the degree of solubility of impurities during the conversion process.

RS Refractory Bricks Factory
RS Refractory Bricks Factory

How Can I Buy High-Quality Refractory Bricks?

Having said that, what should be the standard when buying refractory bricks? First of all, we must know that there are corresponding national standards for the appearance of refractory brick products. “GB/T 10326-2016 Inspection Method for Dimensions, Appearance, and Section of Shaped Refractory Products”, this standard is required from the appearance of refractory bricks.

Secondly, when we buy refractory bricks, we must look at the content of the material, the main material, and the content of impurities. Because generally, shoddy manufacturers will make a fuss about the ratio of raw materials and materials, such as materials with a low main material content, such as the wrong proportion of materials, such as materials with more impurities, and so on. After this type of brick is produced, the surface will generally be rougher and the color will be uneven. The purchaser may require the supplier to provide the inspection report or quality certificate of the goods at the time of purchase. The test report of refractory bricks can reflect the content, porosity, refractoriness, load softening temperature, compressive strength, and other values of this batch of bricks.

Finally, in addition to the content detection, because refractory bricks also involve bulk density, specifications, and dimensions. Therefore, some manufacturers also have unit weight or body density requirements when purchasing. Because, based on the unit weight, we can also make a rough judgment on the quality of refractory bricks.

To learn more about the recognition and identification of the color of refractory bricks, please start with the basic knowledge of refractory materials. Our blog not only introduces our products to you but also introduces you to the relevant knowledge of refractory materials at any time. Please pay attention to our blog to know why there are black spots, black hearts, or cracks in refractory bricks at any time? You can also understand the requirements of binders and additives in the production of refractory bricks of different materials, and so on.