05 Geological Science:Earth's Crust
—Aluminum
地矿学：关于铝矿石的种类及铝的冶炼
导读
铝矿石主要有一水硬铝石、一水软铝石和三水铝石。这些都是炼铝的矿石。铝矾土（aluminous soil; bauxite）又称矾土或铝土矿，主要成分是氧化铝，系含有杂质的水合氧化铝，是一种土状矿物。白色或灰白色，因含铁而呈褐黄或浅红色，不透明，质脆。极难熔化。不溶于水，能溶于硫酸、氢氧化钠溶液。主要用于炼铝，制耐火材料。本文主要介绍了关于铝矿石的种类及铝的冶炼。
Eight percent of the Earth's crust is aluminum, and there are hundreds of aluminum-bearing minerals and vast quantities of the rocks that contain them. The best aluminum ore is bauxite, defined as aggregates of aluminous minerals, more or less impure, in which aluminum is present as hydrated oxides. Bauxite is the richest of all those aluminous rocks that occur in large quantities, and it yields alumina, the intermediate product required for the production of aluminum. Alumina also occurs naturally as the mineral corundum, but corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum. Most of the many abundant nonbauxite aluminous minerals are silicates, and, like all silicate minerals, they are refractory, resistant to analysis, and extremely difficult to process. The aluminum silicates are therefore generally unsuitable alternatives to bauxite because considerably more energy is required to extract alumina from them.
地球地壳的85%是铝元素。地球上有好几百种含铝的矿物，以及大量含有铝矿物的岩石。最好的铝矾矿石是铝矾土，铝矾土是多少有点不纯的铝矿物聚成岩，铝元素以水合氧化物的形式存在其中。铝矾土是所有大量铝质岩中存量最丰富的。铝矾土提供氧化铝，这是生产铝所必需的中间产品。氧化铝也天然存在于矿石刚玉中，但是目前还没有发现有高纯度的巨大的刚玉矿床，因而不是制铝的实际来源。许多含铝丰富的非铝矾土矿石，其中大多数是硅酸盐。像所有硅酸盐矿石那样，这些硅酸盐铝矿石耐熔解，难分解，加工非常困难。因此，硅酸盐铝矿石一般不适用做铝矾土的替代物，因为从中提取氧化铝需要更多的能源。
Sentence Translation
句子翻译
1. The best aluminum ore is bauxite, defined as aggregates of aluminous minerals, more or less impure, in which aluminum is present as hydrated oxides.
2. Alumina also occurs naturally as the mineral corundum, but corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum.
Key
1．最好的铝矾矿石是铝矾土，铝矾土是多少有点不纯的铝矿物聚成岩，铝元素以水合氧化物的形式存在其中。
2．氧化铝也天然存在于矿石刚玉中，但是目前还没有发现有高纯度的巨大的刚玉矿床，因而不是制铝的实际来源。