Best ore dressing depth of iron ore

The main task of the iron ore beneficiation is: under conditions to maximize the recovery of metals from ore, smelting get the most economical iron ore.
Technical and economic indicators for the production of metals from ores (including mining, beneficiation and agglomeration, transportation and smelting costs) should be based on the cost of each ton of pig iron (or metals directly reduced from selected iron ore raw materials). Evaluation:

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The ore dressing costs for the production of metals are evident from equations (2) and (3), depending on the ore processing fee during ore dressing, the metal content of the ore and the metal recovery of the concentrate.
The iron recovery of the concentrate in formula (2) is only considered as a factor in increasing the cost of the metal. But the impact of this parameter is more significant. Especially when iron ore resources are limited in a certain area, with the increase of the beneficiation ratio, the reduction of the recovery rate will inevitably lead to the use of ore which is more expensive than other ore sources. The processing cost of dressing depends on the beneficiation process used and the final grinding size. Under the conditions of the stage beneficiation process, changes in costs due to tailings discharged from the process without being processed through the next stage must be considered.
Transportation costs and concentrate agglomeration are inversely proportional to concentrate iron grade. When transporting concentrates over long distances, higher grades of concentrate iron can significantly save on transportation costs because gangues are thrown away at the concentrator. The cost of the concentrate's agglomeration is not very volatile and can be considered constant when comparing various options for the same ore dressing process. In the production and investment costs of smelting, the cost of building blocks is a function of the grade of concentrate iron. The location of the block also has an impact, especially when the concentrate is sintered. In the long-distance transportation of sinter, the amount of fine ore therein increases, which adversely affects the production capacity of the blast furnace and the consumption of coke .
The smelting cost after concentrate ore is mainly determined by the consumption of coke, natural gas , limestone and processing costs. The relationship between coke and natural gas consumption and concentrate iron grade during blast furnace smelting is shown in Figure 1. As the grade of concentrate iron increases, all the consumption coefficients of smelting decrease. At the same time, the production capacity of the blast furnace is improved. According to the data of the smelting test, the blast furnace production capacity is increased by 1.3~2.2% for each +1 increase of the concentrate iron grade. The chemical composition of the concentrate also has a greater impact on the smelting smelting index. When the refined iron ore containing acidic gangue is smelted with concentrate of the same iron grade with the majority of the gangue, it consumes 15-20% of coke. In the case of a concentrate after smelting, the flux consumption and slag rate are low, and the heat required for normal smelting of the blast furnace is supplemented with cheaper natural gas. The investment cost of beneficiation and smelting in formula (1) is considered according to the conditions of the 8-year recovery investment period, and the ferrous metallurgy is rated equal to 0.125. The impact of concentrate iron grade on unit capital investment in agglomeration and smelting depends on the increase in production capacity of the agglomeration plant and the smelter. This is because as the iron grade of the concentrate increases, the relationship per ton is calculated as 1/β. Metal concentrate consumption is reduced. In this case also reduces the cost of coking coal transportation investment, flux and gas and mining and processing and other related departments. [next]

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At the time of ore preparation, the increase of concentrate iron grade requires an increase in the recovery of ore and the cost of ore dressing, thereby increasing the production cost and investment cost per ton of concentrate. Therefore, based on the economic evaluation of the beneficiation efficiency, various indicators can be compared according to the two types of technical and economic factors of ore preparation and smelting. The two types of factors have the opposite effect on the cost per ton of metal and unit investment. Therefore, based on the results of comparing economic indicators with two types of technical and economic factors, the conclusion about the economic effects of the beneficiation process can be drawn. As the iron grade of concentrates increases, the reduction of smelting costs may not necessarily compensate for the increase in ore dressing costs. Therefore, from the perspective of mining-mineralization-agglomeration-transport-smelting and processing, it is reasonable to determine the refined iron grade of the concentrate to ensure the minimum calculation cost of the metal. The iron grade that guarantees the minimum calculation cost of producing 1 ton of metal is called the best iron grade. This condition can be expressed by equation (1):

C+eK=minimum

The optimal iron grade of the concentrate depends on the mineral composition of the ore, the optionality and ore processing, the ability to concentrate the agglomerate, the consumption of coke, natural gas, flux, the smelting and processing conditions, the rational ore and the ore of the metallurgical plant. supply. For each iron deposit, the optimum beneficiation limits are different due to these factors.
The optimum beneficiation depth can be determined by comparing the smelting technical economic indicators of various iron grade concentrates obtained by various different beneficiation schemes. In this case, starting from the argument that all the compared schemes are economically valid, the best option is chosen according to the relative economic effects. Comparisons of economically ineffective programs (exceeding the rated repayment period, metal failures, and short service years) can lead to erroneous conclusions. The final degree of completion of economic calculations takes into account the following important factors, usually calculated in the process stage of producing metals, in which the same quality products are obtained from iron ore raw materials or products that meet the same requirements of the national economy are obtained. If the same composition (grade) of pig iron is obtained when using concentrates of various iron grades and impurities, it is calculated per ton of pig iron. When the quality of the pig iron (based on the content of useful ingredients or harmful impurities) is different, the economic calculation proceeds until each ton of steel and the corresponding by-products are obtained. In this case, the calculation may be limited to the additional cost associated with pig iron processing in steel production (or the removal of proceeds from the sale of scraped products, such as phosphorus slag, vanadium slag, etc.) to each ton of pig iron. Blast furnace smelting. [next]
The technical and economic calculations for determining the best beneficiation depth of iron ore in the Soviet Union were carried out by researchers at the Black Metallurgical Research Institute. The calculations take into account the mature experience of supplying metal ore raw materials, coke, flux, natural gas, etc. in metallurgical plants. In determining the concentrate iron grade and beneficiation process in the studied scheme, the latest scientific research results and beneficiation practices of selected iron ore in the former Soviet Union and other countries were considered. According to the beneficiation process plan, the grinding size and the metal recovery rate of the concentrate, the changes in mining and ore dressing production costs and infrastructure investment are considered separately for each deposit. The effect of iron grade on production costs per ton of concentrate and unit capital investment is shown in Figure 2. With the improvement of iron grade, the characteristics of unit production cost and investment cost increase are very similar. When the iron grade is close to the mineral grade, the production cost is extremely high. Such quality concentrates can be obtained according to the magnetic-floating combined beneficiation process. When selecting the magnetite quartzite , the most favorable unit cost was achieved for various solutions. For other types of ore, the unit cost is increased in the following order: skarn-type magnetite, magnesia magnetite, hematite-magnetite, and erythr iron-like hematite. The unit cost per ton of concentrate has the same characteristics as the refined iron grade. However, due to the difference in the yield of concentrates, the increase in the unit cost of various types of ore varies somewhat in a different order from the magnetite ore depending on the absolute value of the unit cost. For titanium magnetite ore with 16~17% iron grade, the processing cost per ton of concentrate is the highest.
The cost of mineral processing accounts for 20~30% of the production cost per ton of pig iron produced and 10~20% of the investment cost. Together with the cost of building and shipping, this value is increased to 35% and 25% respectively.
The dressing and smelting iron grade data production and investment costs impact of, for various types of iron ore concentrate at iron grade changes, to determine the cost per ton of pig iron calculated (FIG. 3). Use of iron ore in the smelting most favorable indicator is the variety of magnet quartz rock, ore production is calculated using this lowest cost metal. According to the technological nature of quartzite, the absolute cost per ton of metal is between 42 and 55 rubles. This fluctuation depends on two factors: the selectivity and the iron content of the metal mineral. The metallurgical value of quartzite is basically in line with its process characteristics. Under the condition that the metal mineral iron content is qualified, the various magnetite quartzites from coarse grain inlay to fine grain inlay are reduced. Figure 1-1-4 shows the standard sub-items of three kinds of magnetite quartzite according to metallurgical value, and the lower limit of the division is equivalent to the most poor fine-grained quartzite in the field. The absolute value of other types of ore calculation costs is increased in the following order: skarn type magnetite ore, titanium magnetite ore, limonite ore and magnesite magnetite. For this type of ore, in addition to the optional and metallic mineral iron content, the geographical location of the mining companies and the more difficult climatic conditions also have a major impact. [next]

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With the improvement of the grade of concentrate iron, the calculation of the change in the cost per ton of metal produced and taking into account the significance of the national economy, the optimal beneficiation depth can be accurately determined. The optimal beneficiation depth of the magnetite quartzite of alkaline gangue is 63~66% of the concentrate iron grade; for the ore of acid gangue, the best beneficiation depth is 66~69% of the concentrate iron grade. In

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When refining a deep-separated concentrate with a low-grade iron ore or other iron-containing product, the optimum iron grade value of this concentrate is always higher than when the concentrate is smelted separately. If the concentrate is used as an additive to the iron grade high charge, the optimum iron grade in the concentrate is lower than when it is used alone. The same is true when adding concentrate to a charge having an alkaline gangue (when a concentrate using an acid gangue) or an acid gangue (at the time of using a concentrate of an alkaline gangue). Olenigorsk and Kovdor mining companies consider this situation in production, the concentrate is sintered, and then blast furnace smelting without adding magnesium oxide, magnesium oxide has been with the concentrate of Coffdor Enter together (the table below).

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