Se is a kind of scarce and scatter element, and it is very low-grade ore in mineral.

硒是一种稀少而又分散的元素，矿石中其品位一般都很低。

youdao

He also knows that big mining companies prefer mountains of low-grade ore to small, high-grade mines like his.

而且他也知道那些个大型矿产公司更喜欢那些低地势的矿山，而不是他那又小又高的。

youdao

The categories of the bacteria and its leaching mechanism are key factors for the bioleaching of low-grade ore.

微生物种类及其作用机理是浸出低品位矿石的关键所在。

youdao

They too want to reopen some of their closed mines to look for low-grade ore, and plan to expand production through joint ventures with international players.

BBC: Golden opportunity for old Indian mines

Low-grade uranium ore will be extracted at the Saghand mines and turned into purer uranium, known as yellowcake, at nearby Ardakan.

BBC: Iran unveils uranium activities at Saghand and Ardakan