For a usable iron ore, it must have the following properties: Grade-it should contain as much iron oxide as possible; Density-it should not be too dense nor too crumbly;

• 有价值的铁矿石，必须具备以下特点:品位--铁氧化物的含量应尽可能高;致密度--不能太密实，也不能太容易破碎;