Hematite hydrogen-based ore phase conversion-magnetic separation-reverse flotation combined process

Abstract

The invention relates to the technical field of iron ore beneficiation, in particular to a hematite hydrogen-based ore phase conversion-magnetic separation-reverse flotation combined process. The hematite beneficiation process in the prior art has the problems of low concentrate grade, low iron recovery rate, underreduction of coarse-grain minerals, over-reduction of micro-fine-grain minerals and the like in a hydrogen-based mineral phase conversion technology. In order to solve the problems, hematite and diaspore are fully dissociated after ore grinding and grading, then hematite Fe2O3.nH2O is hydrolyzed into Fe2O3 and then converted into magnetite Fe3O4, diaspore Al2O3.nH2O is converted into corundum Al2O3 through hydrogen-based ore phase conversion, high-purity iron ore concentrate is obtained by combining magnetic separation and flotation processes, energy consumption is reduced, reagent use is reduced, and meanwhile the cost is reduced. And the grade and the iron recovery rate of the iron ore concentrate are improved, and double optimization of economical efficiency and environmental protection performance is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of iron ore dressing, and in particular to a hematite hydrogen-based ore phase conversion-magnetic separation-reverse flotation combined process. Background Art

[0002] The traditional iron ore beneficiation process mainly includes crushing, grinding, magnetic separation and flotation, but it has obvious shortcomings when processing complex ores such as hematite, which are manifested in low concentrate grade (total iron TFe content is usually 45%-48% and SiO2 content is higher than 12%), low iron recovery rate (only 62%-78%), complex process flow, low production efficiency and high cost, which makes it difficult to effectively improve resource utilization. In recent years, hydrogen-based mineral phase conversion technology has become a research hotspot for solving the problem of resource utilization of complex and difficult-to-select iron ores such as hematite. This technology uses hydrogen as a reducing agent to convert weakly magnetic iron minerals (such as hematite) into strongly magnetic iron minerals (such as magnetite) through low-temperature reduction, thereby significantly improving the efficiency of magnetic separation. This technology can not only reduce energy consumption, but also achieve ultra-low emissions of dust, sulfur dioxide and nitrogen oxides, which is in line with the development direction of green mining. In addition, hydrogen-based mineral phase conversion technology is closely integrated with the clean energy industry, and its large-scale promotion can also promote the development of the regional green hydrogen industry.

[0003] However, hydrogen-based ore phase conversion technology still faces many challenges in practical applications. For example, the reduction efficiency of minerals of different particle sizes varies greatly, and it is easy to have problems such as under-reduction of coarse-grained minerals and over-reduction of fine-grained minerals, which affects the separation effect of subsequent magnetic separation. In addition, the complexity of the distribution of silica-alumina gangue minerals means that the efficiency of subsequent flotation removal of impurities still needs to be improved. Therefore, further optimizing the hydrogen-based ore phase conversion process and combining it with efficient magnetic levitation combined separation technology to achieve precise control and efficient development of complex iron ore resources are of great significance to solving the current bottleneck of mineral processing. Summary of the invention

[0004] In view of the problems existing in the existing iron ore beneficiation technology, the present invention provides a combined process of hydrogen-based ore phase transformation-magnetic separation-reverse flotation for hematite. The invention mainly includes five steps of grinding classification, hydrogen-based ore phase transformation, protective gas cooling, magnetic separation and reverse flotation to achieve the removal and separation of iron concentrate and gangue minerals in hematite.

[0005] The present invention provides a hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process, comprising the following steps:

[0006] Step 1 Grinding and Classification: The hematite ore enters the conical ball mill and classification equipment, and the roasting raw material is obtained after grinding and classification.

[0007] Step 2: Hydrogen-based mineral phase conversion: The roasted raw material obtained in step 1 is placed in a suspension roasting furnace for hydrogen-based mineral phase conversion suspension roasting, so that the hematite Fe2O3·nH2O in the roasted raw material is first dehydrated to Fe2O3 and then converted into magnetite Fe3O4, and the diaspore Al2O3·nH2O is converted into corundum Al2O3, so as to obtain a mineral phase conversion product.

[0008] The mineral phase transformation equation is as follows:

[0009] Fe2O3·nH2O→Fe2O3+nH2O

[0010] 3Fe2O3+H2→2Fe3O4+H2O

[0011] Al2O3·nH2O→Al2O3+H2O

[0012] Step 3: Cooling with protective gas: After roasting, introduce protective gas to cool the mineral phase transformation product to obtain a cooled product; the protective gas can prevent the mineral phase transformation product from reverse oxidation.

[0013] Step 4: Weak magnetic separation: The cooled product is subjected to weak magnetic separation to obtain magnetic concentrate and magnetic tailings, thereby achieving a preliminary separation of gangue minerals.

[0014] Step 5: Reverse flotation separation: reverse flotation is performed on the magnetic concentrate to obtain iron concentrate.

[0015] Furthermore, in step 1, after grinding and classification, the content of particles with a diameter of 12 μm to 74 μm in the ore material accounts for 55% to 75%, and the slurry concentration corresponding to the ore material is 30% to 40%. After the slurry is dried, it becomes the roasting raw material.

[0016] Furthermore, in step 2, the raw material for calcination is first preheated in an air atmosphere at 100°C-200°C to remove all crystal water and adsorbed water, and then nitrogen and reducing gas hydrogen are introduced as calcination gases for suspension calcination. The suspension calcination temperature is 500°C-700°C, the concentration of the suspended calcination hydrogen gas is 15%-25%, and the calcination gas flow rate per ton of raw material at normal temperature and pressure is 1000m 3 / h-1400m 3 / h, and the suspension roasting time is 20min-40min.

[0017] Furthermore, in step 3, the cooling environment is nitrogen, the cooling time is 10 min-30 min, and the cooling product temperature is ≤100°C.

[0018] Furthermore, in step 4, the magnetic field strength of the weak magnetic separation is 800Oe to 3000Oe.

[0019] Furthermore, in step 5, reverse flotation of the magnetic concentrate refers to making the magnetic concentrate into reverse flotation slurry and entering the reverse flotation operation, which reverse flotation operation includes a roughing operation, a concentrating operation, and three or four scavenging operations; adding a combined collector, an inhibitor, and a pH adjuster to the reverse flotation slurry and entering the roughing operation, and obtaining a roughing concentrate slurry and a roughing tailings slurry after the roughing operation; the roughing tailings slurry enters the scavenging operation, and the gangue minerals are separated after the scavenging operation; the roughing concentrate slurry is added with a combined collector and a pH adjuster and enters the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to achieve reverse flotation, and the iron concentrate is obtained after the concentrating operation.

[0020] Further, in step 5, the pH adjuster in the reverse flotation operation includes lime and sodium carbonate, the combined collector is a mixture of dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 1:1 to 4:1, and the inhibitor includes starch;

[0021] Further, in step 5, when entering the roughing operation, the reverse flotation pulp concentration is 35wt% to 70wt%, and the materials added to each ton of reverse flotation pulp are as follows: 100g to 400g of inhibitor, 100g to 400g of combined collector, 200g to 800g of lime, and 100g to 500g of sodium carbonate to make pH = 8.8 to 9.2;

[0022] Furthermore, in step 5, when entering the concentration operation, lime is added to the roughing concentrate slurry to adjust the pH to pH=8-10 (without adding sodium carbonate), and 20g-200g of the combined collector is added per ton of the roughing concentrate slurry.

[0023] Furthermore, in step 5, the grade of the obtained iron concentrate is higher than 60%, and the iron recovery rate is higher than 90%.

[0024] Compared with the conventional technology, the combined process of hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation for preparing iron concentrate of the present invention has the following beneficial effects:

[0025] 1. The present invention achieves a narrower particle size classification by precisely controlling the grinding particle size and adopting a grinding-classification combined process to fully dissociate hematite and diaspore, thereby avoiding the secondary mudification problem caused by over-grinding of the ore and improving the sorting efficiency and the quality of the mineral output.

[0026] 2. The present invention realizes the stable reduction reaction of hematite through the suspension roasting technology of hydrogen-based mineral phase transformation. The fluidized roasting process has good mass transfer and heat transfer performance, which can significantly improve the reaction efficiency, while taking into account the green environmental protection goals and reducing the pollution emissions of the traditional roasting process.

[0027] 3. The present invention introduces nitrogen for cooling after roasting, which effectively prevents the magnetite in the roasting product from being reversely oxidized due to the oxidizing atmosphere, thereby improving the magnetic separation quality of the reduced product and ensuring the stability and efficiency of the process.

[0028] 4. The present invention uses a multi-step separation process of "hydrogen-based ore phase conversion-magnetic separation-reverse flotation" to first convert hematite into highly magnetic magnetite, and then remove most of the gangue minerals through weak magnetic separation, and then use the reverse flotation process to further remove silicon and aluminum impurities to obtain high-purity iron ore concentrate. This method not only reduces the use of reagents and energy consumption, but also improves the separation accuracy, achieving dual optimization of economic performance and environmental protection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic diagram of a combined process flow of hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the implementation of the present invention in conjunction with the embodiments and the accompanying drawings. It should be noted that the embodiments described in the present invention are only used to further explain and illustrate, rather than to limit the scope of application. Based on the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0031] The process of the present invention is as follows Figure 1 shown.

[0032] Example 1

[0033] This example uses hematite from a certain place as raw material, the main chemical composition of which is TFe 26.20%, SiO2 4.15%, and Al2O3 5.65%. The specific steps are as follows:

[0034] Step 1 Grinding and Classification: The hematite ore is ball-milled in a conical ball mill and a classifying device. After the ball milling, a ore material with a particle size of 12 μm to 74 μm and a content of 75% is obtained. The ball milling slurry concentration corresponding to the ore material is 35%, and the roasting raw material is obtained after drying.

[0035] Step 2 Hydrogen-based phase conversion: The roasted raw materials obtained in step 1 are put into a hydrogen-based phase conversion suspension roasting furnace, first preheated under 120°C air atmosphere, and then nitrogen and reducing gas hydrogen are introduced. The suspension roasting process controls the temperature at 600°C, and the roasting gas flow rate per ton of roasted raw materials is 1200m 3 / h, the hydrogen gas concentration is 20%, and the roasting time is 25min to obtain a mineral phase conversion product.

[0036] Step 3: Cooling with protective gas: After roasting, the mineral phase transformation product is cooled in a nitrogen atmosphere for 15 min and cooled to 80° C. to obtain a cooled product.

[0037] Step 4: Weak magnetic separation: The cooled product is subjected to magnetic separation with a magnetic field strength of 2000 Oe to obtain magnetic concentrate and magnetic tailings.

[0038] Step 5: Reverse flotation separation: The magnetic concentrate is made into reverse flotation pulp and enters the reverse flotation operation, which includes a roughing operation, a concentrating operation, and three scavenging operations. The reverse flotation pulp concentration is 45wt%. 500g / t of lime, 300g / t of sodium carbonate are added to the reverse flotation pulp to make the pH = 8.5, a combined collector (amount 400g / t, dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 3:1), and an inhibitor (starch 300g / t) are added to the reverse flotation pulp to enter the roughing operation; after the roughing operation is completed, a roughing concentrate pulp and a roughing tailings pulp are obtained. The roughing tailings pulp is subjected to a scavenging operation without the addition of a collector, and the gangue minerals are separated after the scavenging operation is completed. Lime is added to the roughing concentrate pulp to adjust the pH to pH = 9, and then 150g / t of collector is added to enter the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to achieve reverse flotation, and an iron concentrate is obtained after the concentrating operation is completed. The iron concentrate grade is 60.52% and the iron recovery rate is 91.80%.

[0039] Example 2

[0040] This example uses hematite from a certain place as raw material, the main chemical composition of which is TFe 41.58%, SiO2 8.25%, Al2O3 5.50%. The specific steps are as follows:

[0041] Step 1 Grinding and Classification: The hematite ore is ball-milled in a conical ball mill and a classifying device. After the ball milling, a ore material with a particle size of 12 μm to 74 μm and a content of 68% is obtained. The ball milling slurry concentration corresponding to the ore material is 32%. After drying, the roasting raw material is obtained.

[0042] Step 2 Hydrogen-based phase conversion: The roasted raw material obtained in step 1 is put into a hydrogen-based phase conversion suspension roasting furnace, first preheated in an air atmosphere at 100°C, and then nitrogen and reducing gas hydrogen are introduced. The suspension roasting process controls the temperature at 650°C, and the roasting gas flow rate per ton of roasted raw material is 1120m 3 / h, the hydrogen gas concentration is 15%, and the roasting time is 35min to obtain a mineral phase conversion product.

[0043] Step 3: Cooling with protective gas: After roasting, the mineral phase transformation product is cooled in a nitrogen atmosphere for 25 min to 50° C. to obtain a cooled product.

[0044] Step 4: Weak magnetic separation: The cooled product is subjected to magnetic separation with a magnetic field strength of 1500 Oe to obtain magnetic concentrate and magnetic tailings.

[0045] Step 5 reverse flotation separation: The magnetic concentrate is made into reverse flotation pulp and enters the reverse flotation operation, which includes a roughing, a concentrating, and four scavenging operations. The reverse flotation pulp concentration is 62wt%. 600g / t of lime, 350g / t of sodium carbonate are added to the reverse flotation pulp to make the pH = 8.1, a combined collector (dosage 380g / t, dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 2:1), and an inhibitor (starch 300g / t) are added to the reverse flotation pulp to enter the roughing operation; after the roughing operation is completed, a roughing concentrate pulp and a roughing tailings pulp are obtained. The roughing tailings pulp is subjected to a scavenging operation without the addition of a collector, and the gangue minerals are separated after the scavenging operation is completed. Lime is added to the roughing concentrate pulp to adjust the pH to pH = 9, and then 180g / t of collector is added to enter the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to achieve reverse flotation, and iron concentrate is obtained after the concentrating operation is completed. The iron concentrate grade is 62.73% and the iron recovery rate is 92.34%.

[0046] Example 3

[0047] This example uses hematite from a certain place as raw material, the main chemical components of which are TFe 32.80%, SiO2 9.70%, and Al2O3 3.20%. The specific steps are as follows:

[0048] Step 1 Grinding and Classification: The hematite ore is ball-milled in a conical ball mill and a classifying device. After the ball milling, a ore material with a particle size of 12 μm to 74 μm and a content of 61% is obtained. The ball milling slurry concentration corresponding to the ore material is 38%, and the roasting raw material is obtained after drying.

[0049] Step 2 Hydrogen-based mineral phase conversion: The roasted raw materials obtained in step 1 are put into a hydrogen-based mineral phase conversion suspension roasting furnace, first preheated in an air atmosphere at 150°C, and then nitrogen and reducing gas hydrogen are introduced. The suspension roasting process controls the temperature at 550°C, and the roasting gas flow rate per ton of roasted raw materials is 1400m 3 / h, the hydrogen gas concentration is 17%, the time is 33min, and the mineral phase conversion product is obtained.

[0050] Step 3: Cooling with protective gas: After roasting, the mineral phase transformation product is cooled in a nitrogen atmosphere for 20 minutes to 65° C. to obtain a cooled product.

[0051] Step 4: Weak magnetic separation: The cooled product is subjected to magnetic separation with a magnetic field strength of 2500 Oe to obtain magnetic concentrate and magnetic tailings.

[0052] Step 5: Reverse flotation separation: The magnetic concentrate is made into reverse flotation pulp and enters the reverse flotation operation, which includes a roughing, a concentrating, and three scavenging operations. The reverse flotation pulp concentration is 54wt%. 520g / t of lime, 340g / t of sodium carbonate are added to the reverse flotation pulp to make the pH = 8.7, a combined collector (amount 400g / t, dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 4:1), and an inhibitor (280g / t of starch) are added to the reverse flotation pulp to enter the roughing operation; after the roughing operation is completed, a roughing concentrate pulp and a roughing tailings pulp are obtained. The roughing tailings pulp is subjected to a scavenging operation without the addition of a collector, and the gangue minerals are separated after the scavenging operation is completed. Lime is added to the roughing concentrate pulp to adjust the pH to pH = 9, and then 150g / t of collector is added to enter the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to achieve reverse flotation, and an iron concentrate is obtained after the concentrating operation is completed. The iron concentrate grade is 64.89% and the iron recovery rate is 93.12%.

[0053] Example 4

[0054] This example uses hematite from a certain place as raw material, the main chemical components of which are TFe 35.95%, SiO2 9.02%, and Al2O3 3.79%. The specific steps are as follows:

[0055] Step 1 Grinding and Classification: The hematite ore is ball-milled in a conical ball mill and a classifying device. After the ball milling, a ore material with a particle size of 12 μm to 74 μm and a content of 65% is obtained. The ball milling slurry concentration corresponding to the ore material is 40%, and the roasting raw material is obtained after drying.

[0056] Step 2 Hydrogen-based phase conversion: The roasted raw materials obtained in step 1 are put into a hydrogen-based phase conversion suspension roasting furnace, first preheated under an air atmosphere at 140°C, and then nitrogen and reducing gas hydrogen are introduced. The suspension roasting process controls the temperature at 700°C, and the roasting gas flow rate per ton of roasted raw materials is 1300m 3 / h, the hydrogen gas concentration in the roasting atmosphere is 22%, and the roasting time is 25min to obtain a mineral phase conversion product.

[0057] Step 3: Cooling with protective gas: After roasting, the mineral phase transformation product is cooled in a nitrogen atmosphere for 22 minutes and cooled to 60° C. to obtain a cooled product.

[0058] Step 4: Weak magnetic separation: The cooled product is subjected to magnetic separation with a magnetic field strength of 1800 Oe to obtain magnetic concentrate and magnetic tailings.

[0059] Step 5: Reverse flotation separation: The magnetic concentrate is made into reverse flotation pulp and enters the reverse flotation operation, which includes a roughing, a concentrating, and four scavenging operations. The reverse flotation pulp concentration is 66wt%. 550g / t of lime, 330g / t of sodium carbonate are added to the reverse flotation pulp to make the pH = 9.1, a combined collector (amount 400g / t, dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 1:1), and an inhibitor (250g / t of starch) are added to the reverse flotation pulp to enter the roughing operation; after the roughing operation is completed, a roughing concentrate pulp and a roughing tailings pulp are obtained. The roughing tailings pulp is subjected to a scavenging operation without the addition of a collector, and the gangue minerals are separated after the scavenging operation is completed. Lime is added to the roughing concentrate pulp to adjust the pH to pH = 9, and then 190g / t of collector is added to enter the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to achieve reverse flotation, and an iron concentrate is obtained after the concentrating operation is completed. The iron concentrate grade is 67.41% and the iron recovery rate is 94.87%.

[0060] Comparative Example 1

[0061] Compared with Example 1, the difference is that step 3 does not use protective gas cooling, only air cooling is used, and the remaining implementation steps are the same as Example 1. The grade and recovery rate of iron concentrate in step 5 are only 47.65% and 71.28%, respectively. The possible reason is that magnetite is reversely oxidized to hematite during the cooling process, thereby affecting its magnetic separation effect, causing part of the iron minerals to enter the magnetic separation tailings.

[0062] Comparative Example 2

[0063] Compared with Example 2, the difference is that step 2 does not use hydrogen reduction, but uses CO instead of hydrogen, and the remaining implementation steps are the same as Example 2. In step 5, the iron ore grade is only 55.68%, and the recovery rate is 62.64%. The possible reason is that the reduction ability of CO is weaker than that of hydrogen, so it cannot reach the ideal index, and the reduction process will produce a large amount of greenhouse gases, which is not conducive to environmental protection.

Claims

1. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process, characterized in that: Includes the following: Step 1: Grinding and classification: The raw hematite ore enters the ball mill and classification equipment, and the roasting raw material is obtained after grinding and classification; Step 2: Hydrogen-based mineral phase conversion: the roasted raw material obtained in step 1 is placed in a suspension roasting furnace, and subjected to hydrogen-based mineral phase conversion suspension roasting, so that the hematite Fe2O3·nH2O in the roasted raw material is first dehydrated to Fe2O3, and then converted into magnetite Fe3O4, and the diaspore Al2O3·nH2O is converted into corundum Al2O3, to obtain a mineral phase conversion product; Step 3: Cooling with protective gas: After the roasting is completed, a protective gas is introduced to cool the mineral phase conversion product to obtain a cooled product; Step 4: Weak magnetic separation: weak magnetic separation is performed on the cooled product to obtain magnetic concentrate and magnetic tailings, thereby achieving preliminary separation of gangue minerals; Step 5: Reverse flotation separation: reverse flotation is performed on the magnetic concentrate to obtain iron concentrate.

2. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 1, characterized in that: In step 1, after grinding and classification, the content of particles with a diameter of 12 μm to 74 μm in the ore material accounts for 55% to 75%, and the slurry concentration corresponding to the ore material is 30% to 40%. After the slurry is dried, it becomes the roasting raw material.

3. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 1, characterized in that: In step 2, the raw material is first preheated in an air atmosphere at 100°C-200°C to remove all crystal water and adsorbed water, and then nitrogen and reducing gas hydrogen are introduced as roasting gas for suspension roasting. The suspension roasting temperature is 500°C-700°C, the concentration of hydrogen gas for suspension roasting is 15%-25%, and the roasting gas flow rate per ton of raw material at normal temperature and pressure is 1000m 3 / h-1400m 3 / h, and the suspension roasting time is 20min-40min.

4. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 1, characterized in that: In step 3, the cooling environment is nitrogen, the cooling time is 10 min-30 min, and the cooling product temperature is ≤100°C.

5. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 1, characterized in that: In step 4, the magnetic field strength of the weak magnetic separation is 800Oe to 3000Oe.

6. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 1, characterized in that: In step 5, reverse flotation of the magnetic concentrate means that the magnetic concentrate is made into reverse flotation slurry and enters the reverse flotation operation, and the reverse flotation operation includes a roughing operation, a cleaning operation, and three or four scavenging operations; A combined collector, inhibitor and pH adjuster are added to the reverse flotation slurry and the slurry enters the roughing operation. After the roughing operation, a roughing concentrate slurry and a roughing tailings slurry are obtained; the roughing tailings slurry enters the scavenging operation, and the gangue minerals are separated after the scavenging operation; the roughing concentrate slurry is added with a collector and a pH adjuster and enters the concentrating operation, so that the silicon-aluminum gangue minerals fully adsorb the collector to realize reverse flotation, and the iron concentrate is obtained after the concentrating operation.

7. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 6, characterized in that: In step 5, the pH adjuster in the reverse flotation operation includes lime and sodium carbonate, the combined collector is a mixture of dodecylamine and hexadecyltrimethylammonium chloride in a mass ratio of 1:1 to 4:1, and the inhibitor includes starch.

8. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 6, characterized in that: In step 5, when entering the roughing operation, the reverse flotation pulp concentration is 35wt% to 70wt%, and the corresponding materials added per ton of reverse flotation pulp are as follows: 100g to 400g of inhibitor, 100g to 400g of combined collector, 200g to 800g of lime, and 100g to 500g of sodium carbonate to make the pH = 8.8 to 9.

2.

9. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 6, characterized in that: In step 5, when entering the concentration operation, lime is added to the roughing concentrate slurry to adjust the pH to pH = 8-10, and 20g-200g of the combined collector is added per ton of the roughing concentrate slurry.

10. A hematite hydrogen-based ore phase transformation-magnetic separation-reverse flotation combined process according to claim 6, characterized in that: In step 5, the grade of the obtained iron concentrate is higher than 60%, and the iron recovery rate is higher than 90%.

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