Preparation method for sintered corundum

Abstract

The invention discloses a preparation method for sintered corundum. The method comprises the following steps: (1) uniformly mixing gamma-Al2O3 and caustic-burned magnesia powder and carrying out crushing so as to obtain mixed powder, wherein a weight ratio of gamma-Al2O3 to caustic-burned magnesia powder is 94-96: 3-6; (2) subjecting the mixed powder prepared in the step (1) to balling twice so as to obtain a pre-sintered material; and (3) drying the pre-sintered material prepared in the step (2) and carrying out calcining and cooling molding so as to obtain sintered corundum. Preferably, the weight ratio of gamma-Al2O3 to caustic-burned magnesia powder is 95: 3-6. The method is energy saving and environment-friendly; the prepared sintered corundum has high volume density and low impurity content; a microstructure shows that crystal grain of the sintered corundum is of a sheet structure and has a size of 10 to 200 mu m, pores in the crystal exist in an enclosed form, and a crystal structure is compact; and the sintered corundum is widely applicable to production of high-grade shaped or shapeless refractory products.

Description

technical field [0001] The invention relates to the field of refractory materials, in particular to a method for preparing sintered corundum. Background technique [0002] Sintered corundum is a high-purity refractory raw material, which is widely used in the production of high-grade shaped or unshaped refractory products. It has the characteristics of high refractoriness, good wear resistance, and good corrosion resistance. Sintered corundum generally uses calcined alumina or industrial alumina as raw material, adding an appropriate amount of sintering agent, through dry grinding or wet grinding, so that the weight percentage of particles with a particle size of less than 10 μm is greater than 95%, and then through extrusion or pelletization, and then through Drying and firing at high temperature (1800-2000°C). [0003] Sintered tabular alumina is a high-purity alumina raw material that was developed by Alcoa in the 1930s and put into industrial production in the 1970s. A...

AI Technical Summary

Problems solved by technology

Although the sintered tabular alumina produced by Alcoa has stable performance, its production capacity is quite limited and the price is expensive. The price of tabular alumina produced by Alcoa is 1200-2000 yuan / ton higher than that of the same quality domestic tabular alumina

[0004] At present, domestic companies such as Hanzhong Qinyuan New Material Co., Ltd. and Zibo Taibelier Aluminum Magnesium Co., Ltd. have begun to develop and produce sintered corundum. Among them, the quality of tabular corundum produced by Hanzhong Qinyuan New Material Co., Ltd. is the most stable, but the production capacity is not limited. (The annual output is about 10,000 tons), which is completely unable to meet the needs of the domestic market; the tabular corundum produced by Zibo Taibelier Aluminum Magnesium Co., Ltd. has a slightly larger production capacity (annual output is about 30,000 tons), but the quality is very unstable. quality problem

[0005] With the increasing demand for tabular alumina, the supply and quality of tabular alumina cannot meet the demand, so it is necessary to provide a sintered corundum with good product quality and high production capacity

[0006] The invention with authorized notification number CN101085706B discloses a process for producing sintered tabular corundum using an ultra-high temperature shaft kiln. Because the patent uses low-sodium and high-purity pre-fired alumina powder as raw material, the firing temperature is relatively high, as high as 1850~ 1920°C. At the same time, when the patent uses a ball forming disc and a roller to form balls, it is required to spray the ball liquid intermittently. The ball liquid is made of high-purity aluminum glue and phosphoric acid. The concentration of high-purity aluminum glue is 0.3%, and the concentration of phosphoric acid is 0.15%. The ball forming liquid is beneficial to the ball forming, but the introduction of impurity phosphorus leads to a decrease in the purity of the product

[0007] Similarly, the invention with the application publication number CN102503448A discloses a preparation process of sintered tabular alumina. In this preparation process, a ball-forming liquid containing aluminum glue and phosphoric acid is still used, resulting in a decrease in product purity.

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