Anshan type magnetite-hematite mixed iron ore shunting separation method

Abstract

The invention relates to an Anshan type magnetite-hematite mixed iron ore diversion separation method which comprises the following steps: feeding raw ore into a first-section closed circuit grinding system and a second-section closed circuit grinding system, performing overflow feeding of a second-section cyclone into first-section barrel type low-intensity magnetic separation operation to obtain first-section low-intensity magnetic concentrate and tailings, performing second-section electromagnetic concentration operation on the first-section low-intensity magnetic concentrate to obtain first-section low-intensity magnetic concentrate and tailings, and performing second-section electromagnetic concentration operation on the first-section low-intensity magnetic concentrate; the first-section weak magnetic tailings and the second-section electromagnetic concentration tailings are combined and fed into high-intensity magnetic separation operation to obtain high-intensity magnetic concentrates and tailings, the high-intensity magnetic concentrates are fed into reverse flotation operation to obtain reverse flotation concentrates and tailings, and the reverse flotation concentrates and the electromagnetic concentration concentrates are combined to serve as final qualified iron concentrates. The strong magnetic tailings and the reverse flotation tailings are combined and discharged as final tailings. According to the method, easy-to-separate strong magnetic magnetite is recovered through a single low-intensity magnetic separation process, weak magnetic hematite is recovered in combination with a strong magnetic-reverse flotation process, and reselection operation is not needed, so that the separation process is simplified, the separation efficiency is improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mineral processing, and particularly relates to a method for split separation of Anshan-type mixed magnetite-hematite iron ore. BACKGROUND

[0002] Iron ore is a basic guarantee resource for China's steel industry and a major strategic mineral resource. China is rich in Anshan-type iron ore, but in recent years, as the mining depth increases, the ore properties have changed significantly, the proportion of magnetite contained in the ore has increased year by year, the content of ferrous oxide (FeO) has increased from 1-3% in the early stage to 6-11%, and the hematite ore has gradually changed into mixed magnetite-hematite iron ore. Typical mining areas include Anshan, Qidashan, Sijiaying, etc. The useful minerals of this type of ore mainly include magnetite and hematite, the gangue is mainly quartz, and a small amount of carbonate minerals and hornblende, etc.

[0003] At present, the traditional beneficiation process for Anshan-type mixed magnetite-hematite iron ore is a combined separation process of "stage grinding and stage separation, coarse and fine classification-gravity-magnetic-flotation", as shown in the figure. Figure 1 The ore is classified by a hydrocyclone after one-stage closed-circuit ball milling, the coarse particles are recovered by gravity separation using a spiral chute to obtain a gravity separation concentrate, the tailings of gravity separation are discarded by medium magnetic separation, and the medium magnetic separation middlings are returned to the hydrocyclone for coarse and fine classification after two-stage ball milling; the fine particles are pre-enriched by low-intensity magnetic separation-high-intensity magnetic separation to obtain mixed magnetic rough concentrate (i.e. low-intensity magnetic concentrate + high-intensity magnetic concentrate), and the mixed magnetic concentrate is desilicated by reverse flotation to obtain a flotation concentrate. The flotation concentrate and the gravity separation concentrate are mixed to obtain the final iron concentrate product. Although this combined process achieves ore separation to some extent, it still has the following problems: first, the separation efficiency of gravity separation operation is low, and it is difficult to enrich high-grade concentrate, so the comprehensive concentrate quality is limited; second, the process flow is long and complex, and the recycling ratio of coarse particle gravity separation middlings is high, which leads to unstable operation system and separation index; third, the single magnetic separation process does not fully play its role, and the magnetite rough concentrate recovered by low-intensity magnetic separation is mixed with the hematite rough concentrate obtained by high-intensity magnetic separation to enter the reverse flotation operation, which increases the flotation feed and reagent consumption, resulting in low separation efficiency and high production cost. Therefore, it is urgent to develop a new method suitable for the separation of Anshan-type mixed magnetite-hematite iron ore to cope with the challenges brought by the change in ore properties, and ultimately realize the efficient development and low-carbon utilization of low-grade and complex Anshan-type mixed magnetite-hematite iron ore in China. SUMMARY

[0004] The purpose of the present application is to solve the problems of complex process flow, low efficiency, high processing and utilization cost, etc. in the existing process for treating Anshan-type mixed magnetite-hematite iron ore, based on the content change and magnetic difference of useful iron minerals in mixed magnetite-hematite iron ore, a method for split separation of Anshan-type mixed magnetite-hematite iron ore is proposed.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] The method for separating and sorting the Anshan type magnetic and hematite mixed iron ore of the present application comprises the following steps:

[0007] (1) The raw ore (-12 mm) is fed into a first closed-circuit grinding classification operation to obtain a first classification overflow product and a first classification underflow product, and the first classification underflow product is returned to the first grinding system to form a closed circuit, and the first classification overflow product is fed into a second closed-circuit grinding classification operation to obtain a second classification overflow product and a second classification underflow product, and the second classification underflow product is returned to the second grinding system to form a closed circuit;

[0008] (2) The second classification overflow product obtained in step (1) is fed into a first cylinder type low-intensity magnetic separation operation to obtain a first low-intensity magnetic concentrate and a first low-intensity magnetic tailings; the first low-intensity magnetic concentrate is further fed into a second electromagnetic cleaning operation to obtain a second electromagnetic cleaning concentrate and a second electromagnetic cleaning tailings;

[0009] (3) The first low-intensity magnetic tailings and the second electromagnetic cleaning tailings obtained in step (2) are combined and fed into a high-intensity magnetic separation operation to obtain a high-intensity magnetic concentrate and a high-intensity magnetic tailings, and the high-intensity magnetic tailings are discarded as tailings;

[0010] (4) The high-intensity magnetic concentrate obtained in step (3) is fed into a reverse flotation operation, and a "one roughing, one cleaning and three scavenging" flotation process is adopted, and the middlings product is returned to the process in turn, and the reverse flotation operation separates a reverse flotation concentrate and a reverse flotation tailings;

[0011] (5) The second electromagnetic cleaning concentrate obtained in step (2) and the reverse flotation concentrate are combined as a final iron concentrate, the final concentrate has a TFe grade of ≥68%, and the recovery rate is ≥82%; and the high-intensity magnetic tailings and the reverse flotation tailings are combined as a final tailings, and the final tailings has a TFe grade of ≤9%.

[0012] In step (1), the raw ore is an Anshan type magnetic and hematite mixed iron ore, and contains TFe 25%-32%, FeO 6%-11%, SiO2 45-55%, Al2O3 0.1-1.5%, CaO 0.5%-3%, and MgO 0.5-5% by weight, and the particle size of the feed ore is less than 12 mm;

[0013] In step (1), the first classification overflow product has a -0.074 mm particle size content of 55%-70%, and the second classification overflow product has a -0.038 mm particle size content of 70%-90%;

[0014] In step (2), the magnetic field strength of the first cylinder type low-intensity magnetic separation operation is 1500 Oe-2500 Oe, and the magnetic field strength of the second electromagnetic cleaning operation is 800 Oe-1200 Oe;

[0015] The magnetic field strength of the strong magnetic separation operation in the step (3) is 7000 Oe-10000 Oe;

[0016] The reverse flotation operation in the step (4) is an anion reverse flotation operation, and the following reagent system is adopted:

[0017] The concentration of the roughing slurry is 30%-35%, the slurry temperature is 15-35 DEG C, the slurry pH value is 11.5+ / -0.5, the adjusting agent NaOH is used in an amount of 400-600 g / t, the depressant is a compound of starch and k6, and is used in an amount of 1200-2000 g / t, the activator CaO is used in an amount of 1000-2500 g / t, the roughing collector is used in an amount of 900-2000 g / t, the cleaning collector is used in an amount of 400-1000 g / t. The concentration of the roughing slurry is 30%-35%, the slurry temperature is 15-35 DEG C, the slurry pH value is 11.5+ / -0.5, the adjusting agent NaOH is used in an amount of 400-600 g / t, the depressant is a compound of starch and k6, and is used in an amount of 1200-2000 g / t, the activator CaO is used in an amount of 1000-2500 g / t, the roughing collector is used in an amount of 900-2000 g / t, the cleaning collector is used in an amount of 400-1000 g / t. The concentration of the roughing slurry is 30%-35%, the slurry temperature is 15-35 DEG C, the slurry pH value is 11.5+ / -0.5, the adjusting agent NaOH is used in an amount of 400-600 g / t, the depressant is a compound of starch and k6, and is used in an amount of 1200-2000 g / t, the activator CaO is used in an amount of 1000-2500 g / t, the roughing collector is used in an amount of 900-2000 g / t, the cleaning collector is used in an amount of 400-1000 g / t.

[0018] Compared with the prior art, the application has the following advantages:

[0019] (1) The application realizes the separation of magnetite and hematite by recovering magnetite through single low-intensity magnetic separation (full magnetic) process and recovering hematite through strong magnetic-reverse flotation process, can greatly reduce the amount of floating ore and the consumption of flotation reagents, thereby improving the separation efficiency and reducing the production cost.

[0020] (2) The application cancels the traditional gravity separation operation and middling circulation, simplifies the process flow, reduces the equipment configuration, reduces the ore dressing energy consumption and maintenance cost, and improves the stability of the production index.

[0021] (3) The application is suitable for Anshan-type magnetic hematite mixed iron ore, and through the new method of separation, the final concentrate product has an iron grade of more than 68%, a recovery rate of more than 82%, and a tailing iron grade of less than 9%, and the separation efficiency and technical index are significantly better than those of the traditional "stage grinding and stage separation, coarse and fine classification-gravity-magnetic-flotation" process, and the application provides an economic and feasible new solution for the efficient development and green and low-carbon utilization of Anshan-type magnetic hematite mixed iron ore resources. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a traditional Anshan-type iron ore "stage grinding and stage separation, coarse and fine classification-gravity-magnetic-flotation" separation flowchart.

[0023] Figure 2 It is a process flowchart of the separation of Anshan-type magnetic hematite mixed iron ore according to the application.

[0024] Figure 3 , Figure 4 , Figure 5The number and mass flow charts of the Shanshan type magnetic and hematite mixed iron ore separation in the embodiment 1, the embodiment 2 and the embodiment 3 of the application are respectively shown in the following figures. DETAILED DESCRIPTION

[0025] The application will be further described below in conjunction with the drawings and the embodiments. It should be understood by those skilled in the art that the embodiments are only used to help understand the application and should not be regarded as specific limitation to the application.

[0026] Embodiment 1

[0027] A method for separating and sorting Shanshan type magnetic and hematite mixed iron ore, the process flow chart is shown in the following figure Figure 1 The number and mass flow charts are shown in the following figures Figure 2

[0028] The raw ore in the embodiment 1 of the application is taken from a Shanshan type magnetic and hematite mixed iron ore in a beneficiation plant in Liaoning, and the chemical multi-element analysis results of the raw ore are shown in Table 1.

[0029] Table 1 Chemical multi-element analysis results

[0030]

[0031] The Shanshan type magnetic and hematite mixed iron ore raw ore with an iron grade of 29.05% and a particle size of -12 mm is fed into a first closed-circuit grinding and classification system, and the sand returned to the ball mill from the cyclone constitutes a first closed circuit, so that a first classification overflow product with a particle size of -0.074 mm accounting for 55% is obtained, the first classification overflow product is fed into a second closed-circuit grinding and classification system, a second classification overflow with a particle size of -0.038 mm accounting for 70% is fed into a first cylinder type low intensity magnetic separator, and a first low intensity magnetic concentrate and a first low intensity magnetic tailings are obtained; the first low intensity magnetic concentrate is fed into a second electromagnetic cleaner, and a second electromagnetic cleaning concentrate and a second electromagnetic cleaning tailings are obtained; the second electromagnetic cleaning tailings and the first low intensity magnetic tailings are combined and fed into a high intensity magnetic separation operation, a first high intensity magnetic concentrate and a first high intensity magnetic tailings are obtained, and the high intensity magnetic tailings are directly discarded; the high intensity magnetic concentrate is fed into a reverse flotation operation, and through a flotation process of “one roughing, one cleaning and three scavenging”, the middlings product is returned in turn, and the reverse flotation operation separates a reverse flotation concentrate and a reverse flotation tailings; the reverse flotation concentrate and the second electromagnetic cleaning concentrate are combined as a final qualified concentrate, and the reverse flotation tailings and the high intensity magnetic tailings are combined as a final tailings. Specifically, the method comprises the following steps:

[0032] ​(1) The raw ore of the Anshan type magnetic and hematite mixed iron ore is fed into a closed-circuit grinding and classifying system composed of a ball mill and a cyclone by a belt conveyor for coarse grinding and classifying. The classifying obtains a first-stage classifying overflow product with a -0.074 mm particle size content of 55% and a first-stage classifying underflow product. The first-stage classifying underflow product returns to the first-stage grinding system; meanwhile, the first-stage classifying overflow product is fed into a second-stage closed-circuit grinding and classifying system composed of a vertical stirred mill and a cyclone for fine grinding and classifying to obtain a second-stage classifying overflow product with a -0.038 mm particle size content of 70% and a second-stage classifying underflow product. The second-stage classifying underflow product returns to the second-stage grinding system to form a closed circuit.

[0033] (2) The second-stage classifying overflow product obtained in step (1) is fed into a first-stage drum type low intensity magnetic separation operation, and a first-stage low intensity magnetic concentrate and a first-stage low intensity magnetic tailings are obtained. The first-stage low intensity magnetic concentrate has an iron grade of 66.45%, an iron recovery rate of 61.85%, and a yield of 27.04%. The first-stage low intensity magnetic concentrate is further fed into a second-stage electromagnetic cleaning operation, and a second-stage electromagnetic cleaning concentrate and a second-stage electromagnetic cleaning tailings are obtained. The second-stage electromagnetic cleaning concentrate has an iron grade of 69.39%, an iron recovery rate of 59.01%, and a yield of 24.70%.

[0034] (3) The first-stage low intensity magnetic tailings and the second-stage electromagnetic cleaning tailings separated in step (2) are combined and fed into a high intensity magnetic separation operation for separation, and a high intensity magnetic concentrate and a high intensity magnetic tailings are obtained. The high intensity magnetic concentrate has an iron grade of 41.97%, an iron recovery rate of 30.91%, and a yield of 21.39%; the high intensity magnetic tailings have an iron grade of 5.44%, an iron recovery rate of 10.08%, and a yield of 53.91%. The high intensity magnetic tailings are directly discarded.

[0035] (4) The high intensity magnetic concentrate obtained in step (3) is fed into a reverse flotation operation, and a reverse flotation concentrate and a reverse flotation tailings are separated. The reverse flotation operation adopts a "one roughing, one cleaning and three scavenging" flotation process, and the middlings product returns in turn. The roughing reagent system is as follows: the pulp concentration is 35%, the pulp temperature is 30°C, the pulp pH value is 11.5, the adjusting agent NaOH is used in an amount of 400 g / t, the depressant is used in an amount of 1200 g / t, the activator CaO is used in an amount of 1000 g / t, the roughing collector is used in an amount of 900 g / t, and the cleaning collector is used in an amount of 400 g / t. Through the reverse flotation operation, the reverse flotation concentrate and the reverse flotation tailings are obtained. The reverse flotation concentrate has a yield of 10.40%, an iron grade of 65.45%, and an iron recovery rate of 23.43%; the reverse flotation tailings have a yield of 10.99%, an iron grade of 19.75%, and an iron recovery rate of 7.48%. (4) The high intensity magnetic concentrate obtained in step (3) is fed into a reverse flotation operation, and a reverse flotation concentrate and a reverse flotation tailings are separated. The reverse flotation operation adopts a "one roughing, one cleaning and three scavenging" flotation process, and the middlings product returns in turn. The roughing reagent system is as follows: the pulp concentration is 35%, the pulp temperature is 30°C, the pulp pH value is 11.5, the adjusting agent NaOH is used in an amount of 400 g / t, the depressant is used in an amount of 1200 g / t, the activator CaO is used in an amount of 1000 g / t, the roughing collector is used in an amount of 900 g / t, and the cleaning collector is used in an amount of 400 g / t. Through the reverse flotation operation, the reverse flotation concentrate and the reverse flotation tailings are obtained. The reverse flotation concentrate has a yield of 10.40%, an iron grade of 65.45%, and an iron recovery rate of 23.43%; the reverse flotation tailings have a yield of 10.99%, an iron grade of 19.75%, and an iron recovery rate of 7.48%.​

[0036] (5) The two-stage electromagnetic cleaning concentrate obtained in step (2) is combined with the reverse flotation concentrate separated in the reverse flotation operation in step (4) to serve as the final iron concentrate; the high-intensity magnetic tailings obtained in step (3) are combined with the reverse flotation tailings in step (4) to serve as the final tailings. The final concentrate has an iron grade of 68.23%, an iron recovery rate of 82.44%, and a yield of 35.10%; the final tailings have an iron grade of 7.05%, an iron recovery rate of 17.56%, and a yield of 64.90%. Compared with the traditional gravity-magnetic-flotation process, the amount of feed into the flotation in this embodiment is reduced by about 23.50%, and the dosage of flotation reagents is reduced by about 50.00% under the same conditions of unit reagent consumption.

[0037] Example 2

[0038] The process flow of Example 1 is used for the separation of a type of Anshan magnetic and hematite mixed iron ore. The mass flow chart is shown in Figure 3 , and the method is the same as that of Example 1, except for the following differences:

[0039] (1) The results of the chemical multi-element analysis of the raw ore in Example 2 are shown in Table 2.

[0040]

[0041] (2) The raw ore is fed into a one-stage closed-circuit grinding and classification system composed of a ball mill and a spiral classifier for coarse grinding and classification. The one-stage classification overflow product obtained has a -0.074 mm particle size content of 70%. The one-stage classification overflow product is fed into a two-stage closed-circuit grinding and classification system composed of a vertical stirred mill and a cyclone for fine grinding and classification. The two-stage classification overflow product obtained has a -0.038 mm particle size content of 90%.

[0042] (3) The magnetic field strength of the one-stage cylinder type weak magnetic separation is 2500 Oe; the magnetic field strength of the two-stage electromagnetic cleaning is 1200 Oe; and the magnetic field strength of the high-intensity magnetic separation is 10000 Oe.

[0043] (4) The reagent system for reverse flotation is as follows: the concentration of the roughing ore slurry is 35%, the slurry temperature is 35℃, the slurry pH value is 11.8, the dosage of the adjusting agent NaOH is 600 g / t, the dosage of the depressant is 2000 g / t, the dosage of the activator CaO is 2500 g / t, the dosage of the roughing collector is 2000 g / t, and the dosage of the cleaning collector is 1000 g / t.

[0044] ​​(5) The two-stage electromagnetic concentrate and the reverse flotation concentrate are combined as the final iron concentrate, the final concentrate iron grade reaches 68.57%, the iron recovery rate is 85.17%, and the yield is 36.01%; the strong magnetic tailings and the reverse flotation tailings are combined as the final tailings. The final tailings iron grade is 6.43%, the iron recovery rate is 14.83%, and the yield is 66.90%. Compared with the traditional process, under the same conditions, the flotation feed of the embodiment is reduced by about 22.80%, and the flotation reagent consumption is reduced by about 49.00%.

[0045] Example 3

[0046] The process flow of Example 1 is used for the process flow of the Anshan type magnetic and hematite mixed type iron ore, and the quantity flow chart is as shown in Figure 4 The method is the same as that of Example 1, and the difference lies in that:

[0047] (1) The chemical multi-element analysis results of the raw ore in Example 3 are shown in Table 3.

[0048]

[0049] (2) The raw ore is fed into a one-stage closed-circuit grinding and classification system composed of a ball mill and a spiral classifier for coarse grinding and classification operation, and the one-stage classification overflow product -0.074 mm particle size content accounts for 67.66%; the one-stage classification overflow product is fed into a two-stage closed-circuit grinding and classification system composed of a vertical stirring mill and a cyclone for fine grinding and classification treatment, and the two-stage classification overflow product -0.038 mm particle size content accounts for 84.11%.

[0050] (3) The one-stage weak magnetic separation magnetic field strength is 2000 Oe; the two-stage electromagnetic concentrate magnetic field strength is 1000 Oe; and the strong magnetic separation magnetic field strength is 8000 Oe.

[0051] (4) The reagent system of the reverse flotation is that the concentration of the roughing ore slurry is 35%, the slurry temperature is 35℃, the slurry pH value is 11.0, the adjusting agent NaOH consumption is 500 g / t, the inhibitor consumption is 1500 g / t, the activator CaO consumption is 2200 g / t, the roughing collector consumption is 1500 g / t, and the cleaning stage collector consumption is 600 g / t.

[0052] (5) The two-stage electromagnetic concentration concentrate and the reverse flotation concentrate are combined as the final iron concentrate, the final concentrate iron grade reaches 69.51%, the iron recovery rate is 82.80%, and the yield is 36.48%; the strong magnetic tailings and the reverse flotation tailings are combined as the final tailings. The final tailings iron grade is 8.29%, the iron recovery rate is 17.20%, and the yield is 63.52%. Compared with the traditional process, under the same conditions, the flotation feed of the embodiment is reduced by about 27.00%, and the flotation reagent consumption is reduced by about 62.00%.

[0053] The application recovers easily selected strong magnetic magnetite by a single weak magnetic separation process, and combines a strong magnetic-reverse flotation process to jointly recover weak magnetic hematite, without the need for a gravity separation operation, thereby simplifying the separation process and improving the separation efficiency and facilitating production management. Overall, the method uses a full magnetic process to treat the magnetite in the magnetic hematite mixed iron ore, greatly reduces the amount of ore entering the reverse flotation operation, thereby reducing the consumption of reagents such as collectors and depressants, effectively reducing production costs and simultaneously improving the beneficiation efficiency, which is helpful for the stable operation of the concentrator, improves the economic benefits and resource utilization level.

Claims

1. A method for separating and classifying Anshan-type magnetic hematite mixed iron ore, characterized in that, Specifically, the following steps are included: (1) The raw ore of -12mm is fed into the first closed-circuit grinding and classification operation to obtain the first-stage classification overflow product and the first-stage classification sand product. The first-stage classification sand product is returned to the first-stage grinding system to form a closed circuit. The first-stage classification overflow product enters the second closed-circuit grinding and classification operation to obtain the second-stage classification overflow product and the second-stage classification sand product. The second-stage classification sand product is returned to the second-stage grinding system to form a closed circuit. (2) The secondary graded overflow product obtained in step (1) is fed into a first-stage drum-type weak magnetic separation operation to obtain a first-stage weak magnetic concentrate and a first-stage weak magnetic tailings; the first-stage weak magnetic concentrate is further fed into a second-stage electromagnetic cleaning operation to obtain a second-stage electromagnetic cleaning concentrate and a second-stage electromagnetic cleaning tailings. (3) The weak magnetic tailings obtained in step (2) and the electromagnetic separation tailings obtained in step (2) are combined and fed into the strong magnetic separation operation to obtain strong magnetic concentrate and strong magnetic tailings. The strong magnetic tailings are discarded as tailings. (4) The strong magnetic concentrate obtained in step (3) is fed into the reverse flotation operation. The flotation process of "one rougher, one cleaner and three scavengers" is adopted. The middlings are returned to the process for processing in sequence. The reverse flotation operation separates the reverse flotation concentrate and the reverse flotation tailings. (5) The two-stage electromagnetic concentrate obtained in step (2) is combined with the reverse flotation concentrate as the final iron concentrate. The final concentrate has a TFe grade of ≥68% and a recovery rate of ≥82%. The strong magnetic tailings and reverse flotation tailings are combined as the final tailings. The final tailings have a TFe grade of ≤9%.

2. The method for separating and classifying Anshan-type magnetic hematite mixed iron ore according to claim 1, characterized in that, In step (1), the raw ore is Anshan-type magnetohematite mixed iron ore, containing 25%~32% TFe, 6%~11% FeO, 45%~55% SiO2, 0.1%~1.5% Al2O3, 0.5%~3% CaO, and 0.5%~5% MgO by weight percentage, and the particle size of the feed is less than 12mm.

3. The method for separating and classifying Anshan-type magnetic hematite mixed iron ore according to claim 1, characterized in that, In step (1), the content of -0.074mm particles in the primary grade overflow product is 55%~70%; the content of -0.038mm particles in the secondary grade overflow product is 70%~90%.

4. The method for separating and classifying Anshan-type magnetic hematite mixed iron ore according to claim 1, characterized in that, In step (2), the magnetic field strength of the first-stage cylindrical weak magnetic separation operation is 1500 Oe~2500 Oe; the magnetic field strength of the second-stage electromagnetic separation operation is 800 Oe~1200 Oe.

5. The method for separating and classifying Anshan-type magnetic hematite mixed iron ore according to claim 1, characterized in that, In step (3), the magnetic field strength of the strong magnetic separation operation is 7000 Oe to 10000 Oe.

6. The method for separating and classifying Anshan-type magnetic hematite mixed iron ore according to claim 1, characterized in that, In step (4), the reverse flotation operation is an anion reverse flotation operation, using the following reagent system: the roughing pulp concentration is 30%~35%, the pulp temperature is 15~35℃, the pulp pH is 11.5±0.5, the dosage of NaOH as a modifier is 400~600 g / t, the inhibitor is a mixture of starch and K6, the dosage is 1200~2000 g / t, the dosage of CaO as an activator is 1000~2500 g / t, and the roughing collector... Dosage is 900~2000g / t; selected harvesting agent The dosage is 400~1000g / t.

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