Metallurgical value of iron ore (1)
When smelting the best iron grade concentrate, the blast furnace smelting costs are mainly determined by the beneficiation costs. At the same time, without the election of other kinds of natural iron ore grade is calculated depending on the cost of blast furnace integrated metallurgical factors (coke and limestone consumption, blast furnace production capacity). In view of this situation, the classification criteria for natural iron-rich ore and iron-poor ore are the calculated cost of the per-ton of pig iron in the ore and the best iron grade from the same ore selected with the same ore. It is selected to be equal to the iron grade at the expense of the production of metal from the concentrate of this grade with the least cost. The criteria can be calculated according to the following equation: П K =П P Where П K — the calculation cost per ton of pig iron in the smelting of the best iron grade concentrate, rubles per ton; Calculating the calculation cost per ton of pig iron is correct for a dressing process. In the case of two or more stages of beneficiation, in view of the fact that a certain amount of final tailings is discharged in the first few beneficiation stages, the amount of material to be treated is reduced in the subsequent stages, so various cost changes must be considered. In this case, the calculation cost for sorting each ton of ore can be expressed as: The unit consumption of coke for iron making depends on the ratio of the thermal equivalent of the iron mineral material to the coke and is inversely proportional to the pig iron yield per unit of iron ore raw material. Considering this situation, when converted into one ton of pig iron, the calculation cost of coke П п К can be expressed by the following equation: According to the equations obtained, the relationship between the calculation cost per ton of pig iron and the iron grade of the ore produced has a hyperbolic nature (Fig. 1). Compared with unselected ore, the selected ore iron is equivalent to the ore iron grade α which saves the ironmaking calculation cost. In Figure 2, the second type of ore is divided into a group and a group. To represent. Its value can be calculated by means of a derivative. П i is calculated according to the formula (Figure 1). Custom Logo Tape,Custom Packing Tape,Cutom Brand Tape,Custom Tape Dongguan Guanhong Packing Industry Co., Ltd. , https://www.tapegh.com
П P ———The calculation cost per ton of pig iron when smelting unsorted ore, the calculation cost of rouble/ton 1 ton of pig iron, considering the continuous treatment of ore can be expressed by the following formula:
For natural rich ore: 
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In this way, the iron ore of each deposit can theoretically be classified into three categories according to the natural iron grade. The boundary between the types is the intersection of hyperbola, which is equivalent to the calculation cost of smelting pig iron with selected ore and unselected ore.
Under the modern technical level, the ore that is unreasonable in smelting and processing belongs to the first category. The result of sorting out this ore is economically uneconomical because the cost of pig iron exceeds the corresponding effect of iron making.
The ore to be selected belongs to the second category. The ore smelting after the ore's concentrate is more economical than the smelting of the unselected ore. The cost of smelting each ton of pig iron from the selected ore is lower than the cost of smelting each ton of pig iron from the ore of natural iron.
The natural rich ore that does not need to be selected belongs to the third category. Because of the economic effects obtained by reducing coke and increasing the production capacity of the blast furnace, the cost of mineral processing cannot be compensated.
The second type of ore can be divided into two groups. The boundary between them is equivalent to such a natural iron grade α , that is, when it is selected to the best iron grade β o of the concentrate, it can guarantee the maximum calculation cost of ironmaking in the blast furnace production. Iron ore with low metallurgical processing belongs to the first group (α). Although the cost of the calculation is lower than the cost of smelting unselected ore, the pig iron from this ore-selected concentrate will be expensive, and the second group (b) will be the effect of beneficiation and metallurgical processing. There is no doubt about the ore. [next] [next]
For the iron ore with different chemical composition in the largest iron ore deposit of the former Soviet Union, the boundary iron grade that can guarantee the effective metallurgical processing of natural ore and lean ore is determined according to its mining method. As evidenced by the calculation: the limit iron grade in the ore has two values ​​- the lower limit and the upper limit. When these limits are used for metallurgical processing with selected and unselected raw materials, the range defined by the hyperbolic relationship of the calculated cost per ton of metal is a reasonable range of application beneficiation.
The lower limit of the iron grade in the ore indicates that the irrationality of the lowest iron grade ore is selected due to the large loss of metal during ore dressing. This lower limit is within the range of unqualified ore iron grades and exceeding standard production and investment costs. From a scientific point of view, the study of this boundary is beneficial because the effect of beneficiation on metallurgical processing can be thoroughly studied based on the full range of ore iron grade changes. The lower limit of the ore iron grade is calculated based on the type of ore recoverable (metal mineral) iron grade and the total recovery of the metal. For various types of iron ore, the lower limit of the ore iron grade is in the range of 5 to 46%, and is close to the iron grade of the tailings at the time of beneficiation. In this case, the iron recovery rate of the concentrate is 0.5 to 5% for magnetite and 10 to 50% for hematite.
Of practical significance is the upper limit of the ore iron grade, which is the standard for dividing the ore into natural rich ore and the need to select lean ore. The upper limit of the ore iron grade is determined by the optimal iron grade of the concentrate, the calculation cost of the beneficiation and the chemical composition of the gangue. The upper limit of the ore iron grade decreases as the calculation cost of the beneficiation increases, the optimum iron grade of the concentrate decreases, and the alkaline oxide content of the concentrate increases. The difference between the boundary grade of natural rich ore and the best grade of concentrate is in the range of 4 to 5% for siliceous ores and 6 to 10% for alkaline ore-based ore.
The actual proposal corresponding to the lower limit of the ore iron grade should be reasonably corrected according to the economic indicators obtained from the production of metals. According to the conditions that the cost of pig iron must be close to the average production cost of each department, the calculation cost per ton of pig iron per department can be taken as the criterion for dividing the poor ore into unqualified and subject to sorting and then metallurgical treatment. In view of this factor, in addition to hematite with mixed (acid-alkaline) gangue, the grade iron grade of lean ore should be increased for all types of ore. Whether it is the metallurgical treatment of this ore of natural iron grades or the metallurgical treatment of the selected concentrates is closely related to the average level of costs of the above-mentioned sectors, which should be considered in its economic evaluation.
The calculation limit of the natural rich iron grade that can be used for effective metallurgical processing without beneficiation is as follows, %:[next]
Acid gangue magnetite ore 62
Alkaline gangue-based magnetite ore 50
Acidic gangue hematite 60
Alkaline ore-based hematite ore 48
Limonite ore 46
Siderite ore 35
In the actual activities of mining enterprises, the commercial ore iron grade ratio for metallurgical processing is based on the technical economy due to the lack of mineral processing technology, small ore storage or large ore dressing investment, and the use of ore as a rich ore-rich additive. The condition of the effect is calculated to have a low iron grade.
The indicators of ore metallurgical evaluation with or without mining can best reflect the comparative classification of ores according to the optionality. The metallurgical evaluation index is the average calculation cost (П OT ) of each department per ton of metal and the best selection. The ratio of the calculated cost of the ore metallurgical processing of the iron grade (П i ):
The metallurgical value of the ore is determined by the metal mineral iron content, mining, mineral processing and concentrate metallurgical processing costs (including transportation and agglomeration). As the metal mineral iron grade increases, its metallurgical value increases, and the cost per ton of concentrate decreases.