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Siderite is one of the common iron ores. The iron grade of siderite (FeCO3) is low, and the theoretical iron grade is only 48.20%. Some of them also contain Mg and Mn. Moreover, siderite is weakly magnetic iron ore, most of the siderites are fine-grained and complex in composition, and belong to refractory iron ore resources.
After the accumulation of production practice, there are 4 Siderite ore extraction methods:
Gravity separation
Strong magnetic separation
Strong magnetic separation - flotation
Magnetization roasting - weak magnetic separation
The extraction of a single siderite ore is relatively simple. Generally, a single siderite ore with coarse or coarse grains is processed by jigging or heavy medium gravity separation. Among them, heavy medium beneficiation is more common.
( Jigging machine )
Siderite has weak magnetic properties, and it can be successfully separated by strong magnetic separation technology. The siderite after weak magnetic separation is thrown tail with SHP strong magnetic separator, and the iron grade is improved. For example, when the iron grade is 23.17%, the iron grade can reach 28.77% by strong magnetic separation.
In addition, the use of Slon high gradient magnetic separator can also effectively improve the separation index of siderite.
( Strong magnetic separator )
In siderite beneficiation, the combined beneficiation method of strong magnetic separation and flotation can effectively reduce the impurity content in iron concentrate.
First, the siderite is subjected to strong magnetic separation to obtain high-grade iron concentrate, and then the iron concentrate is further processed by flotation process, which can effectively improve the ore grade.
( Flotation machine )
For the flotation of weak magnetic minerals such as siderite, there are mainly two flotation processes: positive flotation for iron enrichment and reverse flotation for desilication.
Grinding - desliming - adding collector (fatty acid) in neutral medium to preferentially flotation iron minerals; or grinding - adding conditioner (soda) - in weak alkaline medium Flotation of iron minerals using collectors (oxidized paraffin soap and tar oil).
Grinding - desliming - pH>11 (sodium hydroxide or sodium hydroxide mixed with sodium carbonate) - activated quartz (adding calcium salt in strong alkaline medium) - adding iron minerals Inhibitors (starch or lignosulfonate) - flotation of quartz and other silicates by adding collectors (fatty acids) .
Or grinding - desliming - pH>8-9 (sodium carbonate) - adding siderite mineral inhibitor (starch, dextrin, tannin) - flotation of Quartz gangue by adding collector (ether amine or fatty amine).
For fine-grained Khenpo siderite, roasting magnetic separation is the most effective.
Magnetization roasting is a process in which the ore is first heated to a certain temperature, and then a physical (calcining decomposition) or chemical reaction (adding a reducing agent) is carried out in the corresponding atmosphere.
Siderite is a carbonate of iron. After neutral or weak reduction roasting, carbon dioxide is decomposed from the ore, and the ore grade is improved. For example, when the iron grade is 35%, after roasting at 600-700 °C, the iron grade up to 50%;
( Rotary kiln )
The siderite is transformed into magnetite after roasting, which has strong magnetic properties and is easy to magnetic separation, so that the material can be separated by efficient weak magnetic separation.
Therefore, siderite is an ore that is easy to enrich after magnetization roasting.
The above are four methods for extracting iron from siderite. Among them, gravity separation and strong magnetic separation are the most economical, but these two processes are difficult to effectively reduce the impurity content in iron concentrate. The combined process of strong magnetic separation-flotation or magnetization roasting-weak magnetic separation can effectively reduce the impurity content in iron concentrate, but the process will be more complicated.
Due to the difference in the properties of the ore, the mine owners can do the Siderite ore beneficiation test first to determine the most suitable siderite beneficiation process.
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