| 摘要 |
<p>Alumina extrudates are made by the extrusion of a mixt. contg. (a) a substantial amt. of alumina in a rehydratable form; (b) water; (c) an effective amt. of alumina powder obtd. by pptn., bauxite ore concentrate, or fine alumina, where materials (c) are added to assist extrusion. The mixt. may also contain methyl cellulose, tall oil, surfactants, and/or flocculants. The mixt. pref. contains 15-65%, esp. 40-60% (a) and an amt. of materials (c) equal to 30 wt. % of material (a). The pref. materials (c) are (c1) returned fines obtd. in mfg. material (a); (c2) fine alumina and bauxite ore concentrate; or (c3) fine alumina and alumina powder obtd. by pptn. Material (a) (rho-alumina), has much better physical properties than other forms of alumina, but is difficult to extrude, as it forms a hard mass with the water and blocks the extrusion die. Materials (c) and the other addns. provide a mixt. which can readily be extruded.</p> |
