low-grade ore

例句：

1. 1. The mine produces low-grade ore that is difficult to refine.
   这个矿场生产出难以提炼的低品位矿石。
2. 2. The company specializes in producing high-quality low-grade ore.
   该公司专门生产高质量但品位较低的矿石。
3. 3.The mining operation has been criticized for extracting low-grade ore from the area.
   该采矿作业因从该地区提取低品位矿石而受到批评。