There are numerous types of iron-bearing minerals; approximately 300 types have been discovered so far, with over 170 being common. However, under current technological conditions, the main types with industrial value are magnetite, hematite, maghematite, ilmenite, limonite, and siderite. Among these, weakly magnetic iron ores such as limonite, siderite, and hematite are the most difficult to process. The physicochemical properties of weakly magnetic iron minerals and gangue minerals in these difficult-to-process iron ores are shown in Tables 4-11 and 4-12. The reserves of various difficult-to-process iron ores in my country are shown in Table 4-13.
Table 4-11 Physicochemical properties of weakly magnetic iron minerals
| type | mineral | Element | Include iron quantity / % | Density (g/ cm³ ) | Specific magnetic susceptibility / ( cm³ /g) | Specific conductivity | Mohs hardness |
| waterless Hematite | Hematite | Fe ₂ O ₃ | 70.1 | 4.8~5.3 | (40~200)×10-6 | 2.23 | 5.5~6.5 |
| Specimenite | Fe ₂ O ₃ | 70.1 | 4.8~5.3 | (200~300)×10-6 | 5.5~6.5 | ||
| Illusory hematite | nFe ₂ O ₃ ·mFe ₂ O ₃ (n<m) | about 7 0 | 4.8~5.3 | (500~1000)×10-6 | |||
| Water content Hematite | Hematite | 2FeO ₃ ·H ₂ O | 66.1 | 4.0~5.0 | (20~80)×10-6 | 3.06 | 1~5.5 |
| Goethite | Fe ₂ O ₃ ·H ₂ O | 62.9 | 4.0~4.5 | ||||
| Water needle iron ore | 3Fe₂O₃ ·4H ₂ O | 60.9 | 3.0~4.4 | ||||
| goethite | 2Fe₂O₃ ·3H ₂ O | 60 | 3.0~4.2 | ||||
| Yellow needle iron ore | Fe ₂ O ₃ ·2H ₂ O | 57.2 | 3.0~4.0 | ||||
| Brownish stone | Fe ₂ O ₃ ·3H ₂ O | 52.2 | 2.5~4.0 | ||||
| Siderite | Siderite | FeCO₃ | 48.2 | 3.8~3.9 | (40~100)×10-6 | 2.56 | 3.5~4.5 |
Table 4-12 Physicochemical properties of gangue minerals
| mineral | Element | iron content/% | density /(g/cm³) | Specific magnetization coefficient /(cm³/g) | Specific conductivity | Mohs hardness |
| quartz | SiO₂ | 2.65 | 10×10⁻⁶ | 3~3.5 | 7 | |
| Biotite | (H,K)(Mg,Fe) ₃ [AISi ₂ O ₁₀ ]( OH,F)2 | Approximately 20 | 2.71~3.1 | 40×10-6 | 1.73 | 2.5~3.0 |
| Garnet | (Ca,Mg,Fe,Mn) ₃ (Al,Fe , Mn,Cr,Ti) ₂ ( SO₄ ) ₃ | Approximately 22 | 3.4~4.3 | 63×10-6 | 6.48 | 6.5~7.0 |
| Pyroxene | Ca(Mg,Fe,Al)[(Si,Al) ₂ O ₆ ] | Approximately 41 | 3.2~3.6 | 2.17 | 5-6 | |
| amphibole | (Ca,Mg,Al,Fe,Mn,Na2, K₂ ) | Approximately 24 | 2.9~3.4 | 2.51 | 5-6 | |
| Actinolite | Caz(Mg,Fe) ₃ [Si ₄ On] ₂ (OH) ₂ | Approximately 28.8 | 3~3.2 | 5-6 | ||
| Epidote | Caz(Al,Fe)Al ₂ [SiO ₄ J[Si ₂ O ₇ JO(OH) | Approximately 15 | 3.25~3.45 | 6-7 | ||
| Peridot | (Mg,Fe)2 SiO₄ | Approximately 44.5 | 3.3 | 3.28 | 6.5~7 | |
| calcite | CaCO₃ | 2.7 | 3.9 | 3 | ||
| dolomite | (Ca,Mg)CO ₃ | 2.8~2.9 | 2.95 | 3.5~4 |
Table 4-13 Reserves and utilization rates of various types of refractory iron ores in my country
| Ore type | Cumulative exploration | keep | Harvested | Utilization /% | |||
| 100 million tons | % | 100 million tons | % | 100 million tons | % | ||
| Hematite | 95.93 | 72.55 | 89.91 | 72.10 | 6.02 | 79.98 | 6.27 |
| Siderite | 18.35 | 13.88 | 18.25 | 14.64 | 0.10 | 1.33 | 0.55 |
| goethite | 12.30 | 9.30 | 10.90 | 8.74 | 1.40 | 18.60 | 11.39 |
| Specimenite | 5.65 | 4.27 | 5.64 | 4.52 | 0.007 | 0.09 | 0.12 |
| total | 132.23 | 100.00 | 124.71 | 100.00 | 7.527 | 100.00 | 5.69 |
Following significant advancements in the beneficiation technology of magnetite and Anshan-type single-quartz hematite, the following deposits are of enormous value . There are still breakthroughs to be made in iron ore beneficiation technology: beneficiation of fine-grained, intercalated Anshan-type lean magnetite ore, and fine- grained intercalated… Anshan-type hematite ore beneficiation, siderite ore beneficiation, limonite ore beneficiation, fine-grained disseminated high-phosphorus hematite (limonite) ore beneficiation, high-phosphorus mandarin orange-shaped hematite ore beneficiation, Baotou Bayan Obo- type iron ore beneficiation, Panzhihua-type vanadium-titanium magnetite. Stone beneficiation, carbonate iron ore beneficiation, Jilin Linjiang antelope stone beneficiation, etc.