Featured in refining iron ore benefit, but beneficiation plant is a price to pay. The selection of ore selection is mainly due to the increase in investment in infrastructure and technological transformation of the concentrator, as well as other indicators such as recovery rate and treatment capacity, thereby reducing concentrate production and increasing concentrate costs. Where P original ore smelting tonne pig for an original --- mined, t / t; It can be seen that the consumption of raw ore per ton of pig iron is inversely related to the metal recovery rate. [next] The difference between the two is 4.762-4.695=0.067t/t It can be seen from Figure 1 that the metal recovery rate of the Dashihe Concentrator has not decreased with the increase of concentrate grade, and has remained at 80-83%. The metal recovery rate was 82.47% in 1985 and 82.64% in 1986. Dashihe Concentrator The reason why the metal recovery rate does not decrease is: (1) With the improvement of the concentrate grade, the process flow has been continuously changed over the years. For example, before 1976, the old process was adopted. In 1977, the fine-screen self-recycling and re-grinding process was adopted. In 1980, it was changed from a fine sieve to a second-stage fine sieve. At the same time, the magnetic separator before filtration was changed to double-tube magnetic separation. machine. In recent years, some measures have been taken successively. For example, the size of the ore selected is changed from -15mm to -12mm. The magnetic pulley is used to increase the grade of the ore selected, and the new process of re-election by magnetic agglomeration is used. These measures have a certain effect on reducing tailings grade and increasing metal recovery rate. (2) Changes in ore properties. After 1980, the Dashihe mine stopped production, and the optional Liuheyu ore began to be put into operation, which made the basis of comparison. Not consistent enough. In order to avoid the above effects as much as possible, after the fine screening and re-grinding process was put into operation, the regression analysis of the data with less external influence before the Liuheyu ore was selected from 1977 to 1979 found that the recovery rate was related to the concentrate grade. The improvement is still affected. Many industries have begun to use optical brighteners, such as paper, plastics, leather, and detergents. At the same time, fluorescent whitening agents are also used in many high-tech fields, such as fluorescence detection, dye lasers, anti-counterfeiting printing, etc., and even high-sensitivity films for high-altitude photography. In order to improve the sensitivity of photosensitive latexes, fluorescence is also used. Brightener. Optical Brightener,Fluorescent Brightener,PVC Brightener,Optical Whitener,Brightening Agent Yucheng Jinhe Industrial Co.,Ltd , https://www.hnchromiumoxidegreen.com
(1) Increase the investment in mineral processing
The selection of ore must take certain technological transformation measures to increase grinding and equipment selection, thus increasing infrastructure costs.
There are 15 ф2.7×2.1m ball mill series in the magnetic separation workshop of Dagangshan Concentrator of Anshan Iron and Steel Co., Ltd. The designed annual processing capacity is 3.6 million tons. When the original design process was produced from 1972 to 1976, the concentrate grade fluctuated at 62.78~ Between 63.71%. In order to improve concentrate grade in the case, the original plant design flow instead the fine screen from the circulation flow in 1977, capacity will remain basically unchanged or slightly lower when the metal recoveries and mill table concentrate grade of 64.32% In order to continue to improve the concentrate grade, a fine screen regrind system was added at the end of 1977, and four ф2.7×3.6m regrind mills, three sections of fine screens and corresponding ancillary facilities were installed, with an investment of 4.426 million yuan. After the addition, the iron concentrate grade reached more than 66%.
The processing capacity of the ore processing in the magnetic separation workshop of Gongchangling Concentrator of Anshan Iron and Steel Co., Ltd. is 5.6 million t/a. There are 14 series of ф2.7×3.6m ball mills, which were put into operation in 1959. After the magnetic separation workshop was put into operation, the concentrate grade was between 61% and 63%. In the second half of 1978, the process was reformed. The fine sieving and regrind process was used, and 6 ф2.7×3.6m regrind mills and 195 fine screens were added. It was put into operation at the end of 1978, and the cost of renovation was about 7.78 million yuan. After upgrading, the grade of concentrate was increased from 62.86% to 65-66%.
In April 1978, Anshan Mine Design and Research Institute carried out the re-grinding and re-election workshop design on the basis of the cation reverse flotation industrial test of Angang Sintering Plant, and treated the plant's coarse concentrate from 115 to 1.2 million t/a. The final concentrate of flotation is 105-1.1 million t/a, the operation recovery rate is 97-88%, and the final concentrate grade is increased from 62-63% to 66-68%. The total estimated investment is 5.16 million yuan.
The above is an example of an old factory renovation. The capital cost for the new concentrator is also increased as the depth of the selection increases. Sometimes, in order to improve the depth of ore selection, various technical solutions can be adopted. The production processes of each scheme are different, the capital construction costs and operating expenses are different, and the selection indicators are different. This requires a detailed technical and economic comparison. For example, in May 1988, the Design Institute of Anshan Iron and Steel Mine Co., Ltd. provided four feasible solutions for the technical and economic demonstration of the roasting magnetic separation concentrate project of Qidashan Concentrator. The Qi Dashan roasting magnetic separation process was the second phase of the Qidashan Concentrator. It was completed and put into operation from April 1971 to April 1973. It has ф3.6×4m and 5 ball mill series. At present, No. 1, No. 2 and No. 3 systems are two-stage continuous grinding-dehydration-magnetic separation-fine screening process, and No. 4 and No. 5 systems are stage grinding-magnetic-heavy-magnetic processes. Statistic indicators in 1987: raw ore 30.1% iron, 61.5% iron concentrate, 62.5% after secondary dewatering tank, recovery rate 78.52%. According to the "seventh five-year" planning requirements of Anshan Iron and Steel, Qi Dashan roasting magnetic separation concentrate grade should reach more than 64%, metal recycling The rate is above 74%.
The ore properties and process flow of each selected plant are different, and the investment costs required to improve the concentrate grade vary greatly. The Dashihe Concentrator was only spent more than 1.6 million yuan before and after 1977, and the concentrate grade increased to 67-68%. The Dagushan and Gongchangling plants need several million yuan, and the concentrate grade reaches 65-66%. The Dashan plant has reached the same sample level and its renovation costs will increase. [next]
(II) Impact of other selection indicators 1. Increasing the impact of concentrate grade on metal recovery rate of ore dressings The change in the recovery rate of mineral processing metals affects the utilization of mineral resources and also affects the ore consumption of unit pig iron. Increasing the metal recovery rate can reduce the cost of mining per ton of pig iron and reduce the cost of pig iron. The reduction of pig iron consumption can also reduce the mine investment per ton of pig iron and improve the investment effect.
The consumption of raw ore per ton of pig iron can be calculated by the following formula: 
a———The original ore grade, %;
ω———Recovery rate of ore dressing metal (actual recovery rate).%;
(The difference between the theoretical recovery rate and the actual recovery rate varies with the beneficiation method and management level. The general magnetic separation method differs by about 1.5%; the roasting magnetic separation method differs by about 2%; the flotation method differs by about 3%)
K 1 ——— metal loss coefficient of the ore during sintering and smelting (non-recyclable);
When the sinter is in the furnace, K 1 = 3%
Natural mine into the furnace for K 2 = 2-3%
K 2 ———The loss coefficient of ore in the process of crushing, beneficiation, transportation, etc. (non-recyclable);
K 2 = 4% when the lean ore beneficiation is put into the furnace
When the natural lump ore is put into the furnace, K 2 = 2%
When selecting raw Fe = 0.94, 1 = 0.03, K 2 = 0.04 , the above equation K
When the ore grade with 30% grade is selected, the recovery rate is increased from 80% to 81%. The original P consumption per ton of iron is changed to:
When the ore grade is 30%, the metallizing metal recovery rate is increased by 1% from 80%, the ton iron ore consumption is reduced by 52kg; the 70% increase is 1%, and the ton iron ore consumption is reduced by 67kg. The lower the recovery rate, the more the impact Big.
Changes in mine consumption will affect the cost of mining per ton of pig iron. Taking the impact on the cost of pig iron as an example, the recovery rate is increased by 1% from 70%. If the ore is a well-selected large deposit, it is assumed that the mining cost per ton of ore is 8.50 yuan, and the processing cost per ton of ore is 9.80 yuan.
The recovery rate is increased by 1%, and the cost of mining per ton of pig iron is reduced by 87.15-85.92=1.23 yuan.
If the ore is a difficult or difficult to choose ore, if the ore mining cost is 18.00 yuan, and the ore processing cost per ton of ore is 15.00 yuan, the impact on the cost of pig iron will be even greater.
The cost per ton of pig iron varies from 157.15 to 154.94 = 2.21 yuan.
It can be seen from the above analysis that the recovery rate of ore dressing metal is not only an important economic indicator of the ore dressing plant, but also an important economic indicator of the entire metallurgical joint venture. It is as important as the concentrate grade. The grade reflects the quality of the product, and the recycling rate reflects the quantity of the product. The two are not negligible. In particular, for some concentrating plants with high mining costs, difficult ore processing, and low recovery rates, we should pay close attention to the changes in metal recovery rate after ore selection.
Whether the recovery rate will be reduced after the ore is selected depends on the depth of the ore selection and measures to improve the concentrate grade. The changes in the recovery rate of some domestic concentrators after improving the concentrate grade are as follows:
Shougang Dashihe Concentrator originally designed 7 series of ф2.7×3.6m ball mills, with an annual processing capacity of 40.75 million tons of ore. In April 1977, a fine screen was installed to realize the fine screen self-circulation and regrind process. In order to increase the capacity of plant selection, four new series of the same model and corresponding ancillary facilities were expanded in 1975. All of them were operated in 1978, and a fine screen was installed in June 1979. The total processing capacity of the plant was 6.5 million tons. Improve the efficiency of fine screening and screening. In 1980, the old system (except No.1 and No.2) was successively changed into two-stage fine screening. In the same year, the magnetic separators before the filtration of 1~11 series were changed into double-tube magnetic separators.
Before the 1976, the original process was produced with a concentrate grade of about 63.5%. After the fine screening and re-grinding process in April 1977, the grade of concentrate was significantly improved, reaching 66-67%. In the fourth quarter of 1979, it was over 68%, 1980~ In the first quarter of 1981, it reached 68.5%, and the highest in March 1980 reached 69%. [next]
The main technical and economic indicators of the Dashihe Concentrator from 1975 to the first quarter of 1981 are shown in Figure 1.
The regression analysis results of the concentrate grade and theoretical recovery rate from 1977 to 1979 are as follows:
Y=122.05-0.60x (3)
The analysis results show that when the separation process is basically unchanged and the ore properties are basically the same, when the concentrate grade changes between 65 and 68.5%, the metal recovery rate decreases by about 0.6% for each 1% increase in concentrate grade.
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