CN1114642A

CN1114642A - Method for producing high-purity micro-crystal white alundum

Info

Publication number: CN1114642A
Application number: CN 94108417
Authority: CN
Inventors: 董杰; 潘先瑜; 孙润秀; 王家金; 李华昌
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-08
Filing date: 1994-07-08
Publication date: 1996-01-10

Abstract

The present invention provides a production method of high-purity micro-crystal white alundum. Its method is as follows: H3PO4 and gamma Al2O3 are uniformly mixed, and then calcined so as to convert gamma Al2O3 to alpha Al2O3, and then HF is used, and water-grinding balls are added and uniformly mixed with the alpha Al2O3, and water-ground, and then the water-ground alpha Al2O3 is dried, and then an organic binding agent is mixed uniformly with the dried alpha Al2O3, and then the above-mentioned materials are passed through such processes of forming, drying and calcining at high-temp., natural cooling, so that the invented product can be obtained. Said product is refractory, stable in chemical and physical properties, and its micro-crystal complex is small, so that it is favourable for practical application.

Description

The production method of high-purity micro-crystal white alundum

The present invention relates to a kind of production method of high-purity micro-crystal white alundum, belong to alumina high temperature stupalith field.

At present, in the alumina high temperature ceramic material of selling, according to Inst. of Geochemistry, Chinese Academy of Sciences the tabular white fused alumina of japanese product is carried out the random sampling chemical examination on market, its result is:

Chemical analysis: Al ₂O ₃97%

Na ₂O＋K ₂O 0.32％

SiO ₂ 0.25％

CaO＋MgO 0.25％

γ Al ₂O ₃Remaining phase 1.5%

Physical property: volume density 3.65g/cm ³

Crystalline phase 20 μ μ crystallite aggregates are wherein because Na ₂O+K ₂O, SiO ₂And γ Al ₂O ₃(gamma aluminium oxide) remaining height of comparing, so the resistance to elevated temperatures of its product is just not so good with chemistry, physical stability, because its crystallite aggregate is also bigger than normal, this will be unfavorable for use in addition.

Purpose of the present invention just provides a kind of Na of containing ₂O, K ₂O, SiO ₂And γ Al ₂O ₃The production method of the high-purity micro-crystal white alundum low, that the crystallite aggregate is little.

The present invention is achieved in that it comprises H ₃PO ₄(phosphoric acid), γ Al ₂O ₃, HF (hydrofluoric acid), will account for γ Al ₂O ₃The H of gross weight 1%～5% ₃PO ₄With γ Al ₂O ₃Mix, 1200 ℃～1600 ℃ temperature lower calcinations 2～6 hours, so just obliterated part Na ₂O, K ₂O, CaO, MgO and Fe ₂O ₃, make γ Al ₂O ₃Convert α Al to ₂O ₃, and guarantee α Al ₂O ₃Content reach 80%, be that 1%～5% HF adds water mill ball and α Al with concentration ₂O ₃Mix and carried out water mill 32～40 hours, to remove SiO ₂With raising density, then with the α Al behind the water mill ₂O ₃Carrying out drying, is 1 ‰～4 ‰ organic bond and dried α Al with concentration ₂O ₃Mix, afterwards reshaping, drying, and naturally lower the temperature to come out of the stove after 3～7 hours at 1600 ℃～1800 ℃ temperature lower calcination and get final product.

Owing to adopted aforementioned production method, the performance of its product is as follows:

Chemical analysis: Al ₂O ₃99.5%

Na ₂O＋K ₂O ＜0.032％

SiO ₂ ＜0.2％

CaO＋MgO ＜0.02％

γ Al ₂O ₃Remaining phase＜1%

Physical property: volume density 〉=3.7g/cm ³

Crystalline phase＜5 μ μ crystallite aggregates

From on can find out the present invention compared with prior art, its Na ₂O, K ₂O, SiO ₂And γ Al ₂O ₃Low, the crystallite aggregate is little, so the resistance to elevated temperatures of its product and chemistry, physical stability is all good than prior art, because its crystallite aggregate is little, this is conducive to actual use very much in addition.

Further specify embodiments of the invention below:

In the present embodiment: will account for γ Al ₂O ₃The H of gross weight 2% ₃PO ₄With γ Al ₂O ₃Mixing, 1450 ℃ of temperature lower calcinations 4 hours, is that 3% HF adds water mill ball and α Al with concentration ₂O ₃Mix and carried out water mill 36 hours, then with the α Al behind the water mill ₂O ₃Carrying out drying, is 2 ‰ organic bond and dried α Al with concentration ₂O ₃Mix, afterwards again balling-up in pan-pelletizer, then dry, and naturally lower the temperature to come out of the stove after 5 hours at 1750 ℃ temperature lower calcination and get final product.

Claims

1, a kind of production method of high-purity micro-crystal white alundum, it comprises H ₃PO ₄, γ Al ₂O ₃, HF, it is characterized in that: will account for γ Al ₂O ₃The H of gross weight 1%～5% ₃PO ₄With γ Al ₂O ₃Mix, 1200 ℃～1600 ℃ temperature lower calcinations 2～6 hours, make γ Al ₂O ₃Convert α Al to ₂O ₃, be that 1%～5% HF adds water mill ball and α Al with concentration ₂O ₃Mix and carried out water mill 32～40 hours, then with the α Al behind the water mill ₂O ₃Carrying out drying, is 1 ‰～4 ‰ organic bond and dried α Al with concentration ₂O ₃Mix, afterwards reshaping, drying, and naturally lower the temperature to come out of the stove after 3～7 hours at 1300 ℃～1800 ℃ temperature lower calcination and get final product.