[Questions and answers on further increasing production of imported wide-body roller kilns] Wide-body roller kiln

Answers and questions about the imported wide-body roller kiln to further increase production. Question: A factory produces micro-powder polished tiles. In order to reduce production costs, it chose an imported wide-body roller kiln. The kiln is 243.6m long and 3.15m wide inside. The start-up period was not smooth. After continuous exploration and debugging, its output has continued to increase, and now it slightly exceeds the budgeted output. However, its formula can be shortened compared with domestic kilns, and the firing cycle can be shortened. If the production is forced to increase, problems such as color, rotten bricks with open edges, cracked bricks in the center, poor oxidation, and rebound deformation will occur. I would like to ask Engineer, can the output of the wide-body kiln be increased again, and what measures need to be taken?

Answer: Increasing output is one of the effective channels to reduce production costs. However, the output cannot be increased. In addition to the reasons for the process formula, if the kiln process design of the drying kiln is not well controlled, it will also seriously restrict the plan to increase production. If cracks occur in the kiln and cannot be solved for a long time, the mud content can be increased in the formula to increase strength and solve problems such as brick damage and cracks. However, when the amount of mud in the formula is increased, the redox reaction may be blocked, and the bricks will appear white core, black core, poor oxidation, yin and yang colors, color marks, yellow edges, pores after polishing, poor anti-fouling, and sometimes Cause center surface cracks, even rebound deformation, etc. Problems such as increased firing temperature and rod breakage may also occur. Therefore, the formula does have a significant effect on solving cracked bricks, but it puts forward higher requirements for the "oxidation" of the kiln. If the formula remains unchanged, the kiln should be improved as much as possible to achieve an adaptive state. This will not only ensure the high-quality rate of existing production, but also provide sufficient preparation conditions for further increase in production.

Most of the current imported wide-body roller kilns are designed to have an inner height of about 680mm in the low smoke exhaust box section. The flow of flue gas in this section is subject to greater resistance. If the flue gas is forced to be exhausted, the flue gas will scouring the bricks more strongly. There are only two smoke exhaust pipes, which obviously cannot meet the gradient requirements of timely drainage of moisture in large-scale bricks, so it is necessary to increase the smoke exhaust sections. In the original kiln design, the first-level smoke exhaust is a small-power fan, and the fan platform is placed in the entrance section of the kiln, and the pipe in the first position is drawn at the kiln head; while the second-level smoke exhaust is a high-power fan, which is placed at the exhaust Later section. Since the front section of the kiln uses low-power smoke exhaust, the extraction power is far less than that of a large fan, which makes it difficult for the temperature of the kiln head section to rise and oxidize early. Therefore, increasing production will be restricted. If the temperature of the kiln head is forcibly raised, the suction force of the large fan will be turned off and the suction force of the small fan will be increased. This will cause the total exhaust suction force to be insufficient, which will affect the overall oxidation effect and further affect the requirements for increasing production. . Therefore, the settings of primary and secondary smoke exhaust are not reasonable, but they can also be improved. (Cheng Zhaohua)

Answers on how to improve the whiteness of composite zircon powder

Question: The performance of zircon powder produced by a domestic company and composite zircon powder produced by a foreign company are compared. Test, the results are shown in Table 1, Table 2, Table 3, and Table 4. It can be seen from Table 3 and Table 4 that the whiteness of composite zircon powder is higher than that of high-purity zircon powder, but the radioactivity index is significantly lower than that of high-purity zircon powder. Please analyze why? How is composite zirconium powder produced abroad?

Answer: According to the grading standard of YB834-87 zircon concentrate and the grading standard of HB5349-86 zircon powder for investment casting, the BF800 sample in Table 1 should belong to the low iron and low titanium type. The first-grade zircon concentrate is processed into first-grade zircon ultrafine powder (zircon powder for short). The sample M8-1 in Table 1 is obviously composite zircon powder. Because the iron and titanium are high, the zircon concentrate used is obviously only the relatively low-priced first-grade zircon stone with high iron and titanium. Composite zircon powder is processed from the concentrate, and the dosage of zircon concentrate is only 85%. Therefore, it can be inferred that the alumina provided by the zircon concentrate is 1.853 and the silica is 27.226; the alumina introduced is 6.017 and the silica is 8.104, and other elements may be lost by burning by 0.41 (here refers to the analysis Trace rare earth elements, unconventional elements or carbonates, nitrate volatiles, etc. that cannot or cannot be tested under conditions).

It can be seen from Table 2 that M8-1 has smaller particle size and more reasonable particle size distribution, which makes the composite zircon powder have better hiding power. Assume that the raw materials of composite zircon are calcined Datong soil, high white quartz, low-temperature calcining aid A and low-temperature calcining aid B. The chemical mass percentages of calcined Datong soil and high white quartz are shown in Table 5. Composite zircon powder The ingredients of the formula are shown in Table 6.

Obviously, the whiteness of zircon powder is related to the crystal morphology of zircon in the zircon powder, the particle size and particle size distribution of zircon, the content of zircon, and the composition, shape, and composition of other crystals. It is related to the particle size and is the result of the combined effect of the above factors. As a ceramic whitening agent, it is required to have three conditions: first, strong hiding power; second, low radioactivity index; third, the price of the product is lower than other products. Why does composite zircon powder have the above three advantages? It can be explained from the perspective of the green body formula. For specific content, please refer to the article "Discussion on Zirconium Silicate and Ultra-White Bricks" in the 5th issue of Foshan Ceramics in 2011.

Why is the whiteness of composite zircon powder so high? It can be analyzed from the production process and product particle size characteristics. The process flow is shown in Figure 1.

As can be seen from Figure 1, sodium nitrate is used as the ingredient. Its advantages are as follows: First, it is an oxidant. It can promote the conversion of iron oxide and titanium oxide to high valence states and improve the whiteness; secondly, it can form glass with high expansion coefficient with high white quartz and zircon, which can accelerate the destructive force during quenching and promote the crushing or cracking of zircon. ; Third, it can react with zircon, especially iron and titanium-containing substances, so that it can be dissolved during pickling. Of course, apatite can also be used as a flux. In addition to promoting the formation of a glass phase surrounding zircon together with sodium nitrate, it can also improve the hiding power of zircon and increase its whiteness. Dry crushing can make the particle size smaller and the particle size distribution more reasonable. The total amount of sodium nitrate and apatite in the formula is only 1, but less than 0.8 after calcination. It has little impact on the firing temperature of the zircon powder in the glaze, and can also improve the brightness of the glaze. The author believes that the flux can also be considered to introduce cerium oxide as a whitening agent.

(Han Fuxing)

Several processes for producing glazed tiles using body color materials

At present, the whole society is pursuing a low-carbon and environmentally friendly life , how to reduce energy consumption and save resources will become a part of our lives in the future. As a ceramic industry with high pollution and high energy consumption, if we can make full use of various industrial waste residues and perform low-temperature firing processes during the production process, it is a practical method and measure to save natural resources. For example, using green color materials to produce ceramic tiles with glazed effect can save expenses on raw material procurement and reduce costs; on the other hand, it can also save valuable rare metal materials, especially black and zirconium among useful color materials. Products, such as zirconium oxide, cobalt oxide, nickel oxide, praseodymium oxide and other rare precious metal materials.

As we all know, ceramic color materials can be roughly divided into two parts: body and glaze. Generally speaking, most of the color materials that can be used in glaze can be used in the body, and the body color materials generally have very light color in the glaze, or no color at all. Theoretically speaking, during the reaction process of the green body, it is mainly a combination reaction between solid phase materials, and the liquid phase reaction time is shorter. Therefore, the requirements for its high temperature stability and physical and chemical index performance are lower. Secondly, some industrial waste residues can be used to bake the brown color in the body color, as well as the black series with larger amounts, and the reaction temperature is usually low, generally around 1100°C. The brown color of some green bodies only needs about 800℃, and some products can even be used as colorants without firing. Glaze colorants are different. Zirconium series colorant products require the use of metal materials such as zirconium oxide, rare earth materials such as praseodymium oxide and vanadium oxide. Secondly, the firing temperature of glaze colorants is usually between 1100 and 1300°C, which requires a large amount of fuel to carry out the heating reaction. Therefore, if we can make use of the reasonable design of glaze formula and other process links, and the design of related stencils and other effects, I believe this will be a project with great social benefits and good economic benefits.

At present, some ceramic manufacturers are already debugging and utilizing some of the body colors and producing ceramic tiles with better glaze effects.

For example, a company adjusted the glaze and used the body color coral red to produce exterior wall tiles that replaced zirconium red and wrapped yellow effects. Secondly, using the black production base line of the green body can also achieve the goal by adjusting the frit formula.

In general, applying body color materials to the production of glazed tiles can be achieved in the following three ways.

(1) Adjustment of raw material formula. Mainly feldspar raw materials are used for formula matching, which can only be used for a specific color. By adding a certain amount of zirconium silicate to the glaze, the whiteness of the glaze is increased, making the color of the body color brighter. improve.

(2) Reasonable design of frit formula. It is suitable for the production of brown and black bodies. Through the reasonable combination of lead and boron in the formula, the glaze effect is particularly bright and the color of the iron series bodies is bright.

(3) A combination of frit and raw material. It has wide applicability, but the glaze effect is average.

(Qin Wei)

Inquiry hotline:

Editorial Department: 0757-82269827

Fax: 0757-82269827

Cai Feihu: 0757-82710910 (Foshan Green Ceramics Technology Development Co., Ltd., Foshan Bol

Ceramics Technology Co., Ltd.)

Kong Haifa: 0757-83135108 (0)13702559893

Cheng Zhaohua: 13927717401 (Foshan Jiayao Ceramics Technology Co., Ltd.)

https://www.Omitted

Pan Xiong: 13927769832 (Guangdong Xinruncheng Ceramics Co., Ltd.)

Han Fuxing: 18237699507 (Henan Xinyang Fanghao Industrial Co., Ltd.)