The gas is fed back over the calcium oxide.

气体被化钙反作用。

Heating this chemical compound drives off carbon dioxide gas leaving calcium oxide.

加热这种化物会驱除二化碳气体，留下化钙。

The essential ingredient in cement is calcium oxide, CaO.

水泥中的基本分是化钙， CaO。

The essential ingredient in cement is calcium oxide, CaO. We get that calcium oxide from limestone, which is mostly made of calcium carbonate: CaCO3.

水泥中的基本分是化钙，CaO。 我们从石灰石中得到化钙， 它主要由碳酸钙：CaCO3。

Over time, some CO2 from the atmosphere drifts into all that cement in buildings and bridges, and reacts with the calcium oxide to form calcium carbonate again.

随着时间的推移，大气中的一些二化碳漂移到建筑物和桥梁的所有水泥中， 并与化钙反应再次形碳酸钙。

Limestone is refined to produce calcium oxide, or quicklime, for cement, in a reaction known as calcination, which releases a lot of carbon in the form of CO2.

石灰石被提炼以生产用于水泥的化钙或生石灰， 在称为煅烧的反应中，该反应以 CO2 的形式释放大量碳。

But in fact, most of the CO2 emissions come not from the heating, but from the breakdown of limestone, which is calcium carbonate, into calcium oxide and carbon dioxide, or CO2.

但事实上，大部分的二化碳排放不是来自加热，而是来自石灰石， 也就是碳酸钙， 分解化钙和二化碳， 即二化碳。