| 摘要 |
1,147,501. Magnesite brick. DRESSER INDUSTRIES Inc. 3 May, 1967 [7 June, 1966], No. 20576/67. Heading C1J. Magnesite brick consists of at least 85% MgO, less than 3% Al 2 O 3 +Fe 2 O 3 +Cr 2 O 3 , and CaO, SiO 2 and P 2 O 5 together totalling at least 2% and being in substantially the proportions enclosed by the area ABCD shown in Fig. 1, with the proviso that (a) the shape contains at least 0À2% P 2 O 5 ; (b) said P 2 O 5 , CaO and SiO 2 are substantially all combined as calcium silicophosphates; and (c) the B 2 O 3 content is sufficiently low and the proportions of the said P 2 O 5 , CaO and SiO 2 are such that the shape has a modulus of rupture at 2,600‹ F. in excess of 500 p.s.i. It is essential that the CaO and P 2 O 5 are allowed to react with each other rather than with the magnesia. The brick-making batch may be made by: (a) forming the batch from size-graded dead burned magnesite, finely divided silica, lime-yielding materials and calcium phosphate-yielding materials such as monetite, whitlockite, brushite, fluorapatite, chlorapatite, hydroxylapatite, carbonateapatite and isoclasite; (b) forming a prereacted grain from dead-burned magnesite, caustic magnesia, silica, lime-yielding materials and calcium phosphate-yielding materials, intimately mixing, burning, e.g. at 3140‹ F. and sizing and grading to form the brick-making batch; and (c) burning and ball-milling a binder batch of lime, silica, lime-yielding and phosphateyielding materials to form a prereacted binder batch which is then added to a size-graded dead burned magnesite brick-making batch. The brick-making batches are tempered with 5% lignin liquor pressed into brick at 10,000 p.s.i., dried at 250‹ F. for 10 hours and fired at 2800‹ F. for 10 hours. The fired brick may be impregnated with a non-aqueous cokeable binder such a star. |
