One of the typical representatives of this kind of iron ore deposit is Anshan Iron Mine, which is the most important type of industrial iron ore deposit, accounting for about 60% of the world's iron ore production. The main minerals in iron ore are magnetite, hematite, pseudohematite, limonite, siderite, magnesium ankerite, Yingshi, tremolite, iron-magnesium amphibole, chlorite, actinolite and a small amount of pyrite and pyrrhotite. The phase analysis of this kind of iron ore focuses on the accurate determination of magnetic iron, followed by iron silicate. The following two analytical procedures are recommended, which can be used for the full-phase analysis of various irons in several separate samples of iron ore. See figure 1.23 and figure 1.24.
Figure 1.23 One of the phase analysis processes of iron in Anshan Iron Mine.
Matters needing attention
One (1) process is suitable for samples with more symbionts of magnetite and iron carbonate, and the other process is suitable for samples with less symbionts.
(2) Determination of iron carbonate: When iron (Ⅱ) is low, use phenanthroline spectrophotometry, and when iron (Ⅱ) is high, use K2Cr2O7 titration method.
(3) When the content of hematite is high, Fe (Ⅲ) should be determined simultaneously with iron carbonate contained in hematite phase.
(4) When using soluble iron silicate (chlorite) for a long time, one of the processes should be adopted, and when the amount of iron carbonate is high, the second process should be adopted.
(5) Pyrite is sampled and determined separately, and iron silicate is obtained by subtraction.
Figure 1.24 Phase Analysis Process of Iron in Anshan Iron Mine (Ⅱ)
2. Phase analysis of sedimentary iron deposits
The industrial significance of this kind of iron deposits is second only to metamorphic sedimentary iron deposits, and about 30% of the world's iron ore production belongs to this type. Long Xuan Iron Mine in Hebei Province and Ningxiang Iron Mine in Hunan Province are the representatives of this kind of iron mine. The composition of this kind of iron ore is relatively simple, mainly hematite and limonite, with less magnetite and siderite. Gangue minerals mainly include quartz, chlorite, glauconite, sericite, serpentine, mafic amphibole, epidote and kaolinite. Sulfide minerals include pyrite and pyrrhotite. Sometimes the high valence oxide of manganese can reach a few percent. The structural characteristics of this kind of iron ore are fine disseminated particle size and high mineral chemical activity.
One of Anshan-type iron mineral phase analysis methods can be used for phase analysis of this kind of ore.
3. Medium-low temperature hydrothermal and sedimentary (metamorphic) siderite deposits
This kind of iron deposit is widely distributed in China. Except for a few, it is generally small and medium-sized iron ore. Daxigou Iron Mine in Shaanxi and Guanyinshan Iron Mine in Guizhou are the representatives of this kind of deposits. The main minerals are siderite, magnetite, hematite, limonite and magnesium ankerite. Gangue minerals mainly include quartz, sericite, sodium amphibole, chlorite, plagioclase and barite, and often coexist with pyrite, chalcopyrite, sphalerite and galena. Oxidized ore contains oxides of manganese with high valence, and the phase analysis of this kind of iron ore focuses on the accurate determination of siderite and magnetic iron.
The following analysis process, combined with several separate sampling measurements, can complete the full-phase analysis of iron in this kind of ore. See figure 1.25.
4. Late magmatic iron deposits
This kind of iron ore is widely distributed in China, and the most famous one is Panzhihua vanadium-titanium magnetite. The metal minerals in the ore mainly include titanomagnetite, ilmenite, pyrite, pyrrhotite, nickel pyrite, chalcopyrite and nickel-cobalt sulfide. Gangue minerals include pyroxene, olivine, amphibole, plagioclase, chlorite, actinolite, spinel, epidote, serpentine, kaolinite, apatite and calcite. The main contradiction in the phase analysis of iron in this kind of iron ore is the determination of titanomagnetite and ilmenite.
The following analysis process is simple and reliable. See figure 1.26.
Figure 1.25 Phase analysis process of iron in Daxigou siderite
Figure 1.26 Phase analysis process of iron in Panzhihua iron mine