Efficient and energy-saving beneficiation process for weathered crust-type magnetic-hematite-brown mixed iron ore

Abstract

The application discloses a kind of weathered crust type magnetic red-brown mixed iron ore high-efficiency energy-saving mineral processing technology, comprising the following steps: 1) raw ore is crushed-dry screening-washing ore-high pressure roller mill-wet screening to obtain qualified size of dressing product;2) the dressing product is obtained by weak magnetic separation operation magnetic separation iron concentrate and weak magnetic separation tailings;3) the weak magnetic separation tailings are obtained by strong magnetic separation-cyclone classification-chute gravity separation, and the gravity separation iron concentrate, chute gravity separation tailings, cyclone classification overflow and strong magnetic sweep tailings;4) the chute gravity separation tailings are obtained by grinding classification-strong magnetic roughing, and the strong magnetic roughing concentrate and strong magnetic roughing tailings, the strong magnetic roughing concentrate and cyclone classification overflow are combined by reverse flotation to obtain flotation iron concentrate and reverse flotation total tailings.The application can obtain more than 50% of qualified dressing product by washing operation before entering high pressure roller mill, greatly reduce the grinding amount and avoid overgrinding phenomenon, and the comprehensive utilization rate of this type of resource is significantly improved by the combined mineral processing method of magnetic separation, gravity separation and flotation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mixed iron ore dressing, and particularly relates to a weathering crust type mixed iron ore dressing method, which is particularly suitable for processing mixed iron ore with an iron grade of 35% to 45%, coexisting of magnetite, hematite and limonite, and high clay and iron content, and easy to crush and sliming. BACKGROUND

[0002] Steel is a basic and structural material in the development of national economy and is irreplaceable. The proportion of complex and difficult-to-process iron ore in China's iron ore resources is relatively high. The total reserves of typical difficult-to-use iron ore resources such as siderite, limonite and fine-grained ore are more than 20 billion tons. Due to the fine crystalline particle size, complex mineral composition and close symbiotic relationship of such iron ore resources, it is difficult to obtain good technical and economic indicators by using conventional beneficiation technology. Most of the resources have not been industrialized and utilized, and part of the resources has been developed, but the beneficiation process is complex and the cost is high. The recovery rate is generally only 60% to 65%, or even less than 50%. It is urgent to carry out research on complex and difficult-to-process iron ore resources, which is necessary for the security of China's iron ore resources.

[0003] For mixed iron ore separation, the current beneficiation process is to close-circuit grind the mixed iron ore (broken to -12 mm) to -0.076 mm content of about 65%, and then to the final iron concentrate (TFe grade of about 56%) by weak magnetic separation-strong magnetic separation and thickening filtration dewatering. In addition to the above single magnetic separation process, the current domestic mixed iron ore beneficiation process also includes stage grinding-weak magnetic separation-strong magnetic separation-cationic reverse flotation (process one); stage grinding, coarse and fine separation, gravity separation-magnetic separation-cationic reverse flotation (process two). The advantages of stage grinding-weak magnetic separation-strong magnetic separation-cationic reverse flotation process (process one) are: (1) stage grinding is adopted to realize "early rejection", and a large amount of qualified tailings is rejected under the condition of relatively coarse grinding particle size; (2) weak magnetic-strong magnetic mixed coarse concentrate regrinding is beneficial to stabilizing the flotation feed grade and adapting to changes in ore; (3) the production is stable and easy to operate. The disadvantages are: the fine concentrate regrinding quantity is large, the siderite is brittle and easy to overgrind, and it is not conducive to energy saving and consumption reduction.

[0004] In order to solve the problem of dressing mixed iron ore, the paper of "Dressing Process Research of Mixed Iron Ore" published in the 6th issue of Mining Engineering in 2012 carried out experimental research on mixed iron ore in a certain area. The main iron minerals in the raw ore are magnetic iron, hematite and carbonic acid iron. Through systematic research on the properties of iron ore, process structure and separation process, the process of "stage grinding, coarse and fine separation, spiral chute-strong magnetic centrifuge process" is finally determined, and the indexes obtained are as follows: the grade of raw ore is 30.09%, the grade of concentrate is 62.39%, the yield is 33.53%, the recovery rate is 69.52%, the grade of tailings is 13.80%, and the grade of concentrate after roasting is 64.84%. However, in general, the grade of iron concentrate obtained is low, the iron recovery rate is low, and the loss of iron in tailings is large.

[0005] Weathering crust type mixed iron ore is a kind of complex and difficult to choose iron ore, which has the characteristics of multiple types of iron minerals, high mud, high iron-containing clay, easy crushing and easy argillization. This type of iron ore is mainly distributed in Hunan, Hubei, Jiangxi, Guangdong, Guangxi and Hainan of China, mainly because the southern part of China is in low latitude area, belonging to tropical-subtropical climate, with warm and humid climate and strong weathering. The current dressing process has the problems of low dressing effect, low resource utilization rate and large iron loss for weathering crust type mixed iron ore.

[0006] Washing is an effective means of pretreatment for high-mud iron ore, coarse and fine classification and separate selection are important ways to improve separation efficiency, more crushing and less grinding are key ways to reduce the cost of dressing, and magnetic and heavy floating combined separation is an important dressing method for the utilization of magnetic and hematite mixed iron ore. Therefore, it is urgent to develop a kind of high-efficiency and energy-saving dressing process for mixed iron ore with multiple types of useful iron minerals, high mud, high iron-containing clay, easy crushing and easy argillization. SUMMARY

[0007] The purpose of the present application is to solve the technical problems of poor separation effect, low resource utilization rate and other technical problems of the prior art for high-mud, high-iron-containing clay, easy crushing and easy argillization of magnetic hematite mixed iron ore, and to provide a weathering crust type magnetic hematite mixed iron ore high-efficiency and energy-saving dressing process with good separation effect, stable and reliable process, strong applicability, relatively low dressing energy consumption and cost.

[0008] In order to achieve the above-mentioned purpose of the present application, the weathering crust type magnetic hematite mixed iron ore high-efficiency and energy-saving dressing process adopts the following process and steps:

[0009] S1 dry screening-crushing-washing-wet screening-high pressure roller grinding

[0010] The raw ore is subjected to dry screening to obtain dry-screened oversize product and dry-screened undersize product, the dry-screened oversize product is fed into a crushing device for crushing, and the crushed product is returned to the dry screening operation; the dry-screened undersize product is subjected to ore washing to obtain ore washing overflow and ore washing return sand, the ore washing return sand is fed into a wet screening device for screening to obtain wet-screened oversize product and wet-screened undersize product, the wet-screened oversize product is subjected to high-pressure roller grinding and then returned to the wet screening operation; and the ore washing overflow and the wet-screened undersize product are combined as the feed product;

[0011] S2 weak-magnetic - strong-magnetic

[0012] The feed product obtained in the S1 step is subjected to weak-magnetic - strong-magnetic operation, the weak-magnetic operation includes weak-magnetic roughing and weak-magnetic cleaning, the strong-magnetic operation includes strong-magnetic roughing and strong-magnetic scavenging, to obtain weak-magnetic iron concentrate, strong-magnetic roughing concentrate and strong-magnetic scavenging concentrate, the strong-magnetic roughing concentrate and the strong-magnetic scavenging concentrate are combined as strong-magnetic comprehensive concentrate, and the strong-magnetic scavenging tailings are discharged;

[0013] S3 cyclone classification - sluice re-election

[0014] The strong-magnetic comprehensive concentrate obtained in the S2 step is subjected to cyclone classification to obtain cyclone classification overflow and cyclone classification sink sand, the cyclone classification sink sand is fed into a sluice re-election operation, the sluice re-election operation includes sluice re-election roughing and sluice re-election cleaning, to obtain spiral sluice cleaning concentrate, spiral sluice roughing tailings and spiral sluice cleaning tailings are discharged, and the spiral sluice roughing tailings and the spiral sluice cleaning tailings are combined as sluice re-election tailings;

[0015] S4 pre-classification - grinding - strong-magnetic separation

[0016] The sluice re-election tailings discharged in the S3 step are subjected to pre-classification to obtain pre-classification overflow and pre-classification return sand, the pre-classification return sand is fed into a grinding device for grinding, and the ground product is returned to the classification operation; the pre-classification overflow is fed into a strong-magnetic roughing operation to obtain strong-magnetic roughing concentrate, and strong-magnetic roughing tailings are discharged;

[0017] S5 thickening - reverse flotation

[0018] The strong-magnetic roughing concentrate obtained in the S4 step and the pre-classification overflow are combined and then subjected to thickening to obtain thickening underflow, the thickening underflow is subjected to reverse flotation to obtain reverse flotation concentrate and reverse flotation tailings, the reverse flotation concentrate, the weak-magnetic iron concentrate obtained in the S2 step and the spiral sluice cleaning concentrate obtained in the S3 step are combined as final iron concentrate; the reverse flotation tailings, the strong-magnetic scavenging tailings discharged in the S2 step and the strong-magnetic roughing tailings discharged in the S4 step are combined as final total tailings; the reverse flotation operation adopts one roughing and one cleaning, and the dosages of reagents for each operation are calculated according to the dry ore quantity of the reverse flotation operation as follows:

[0019] Reverse flotation roughing: sodium hydroxide dosage 1000g / t-2000g / t, dispersant sodium hexametaphosphate dosage 20g / t-40g / t, depressant starch dosage 300g / t-500g / t, collector dodecylamine dosage 600g / t-900g / t; reverse flotation cleaning: collector dodecylamine dosage 300g / t-500g / t.

[0020] Preferably, in the step S1, the dry screening operation uses a linear vibrating screen with a mesh size of 20mm-40mm; the crushing equipment uses a jaw crusher; the washing operation uses a single spiral trough washer, with a spiral lifting angle of 20°-30°, a washing concentration of 10%-20%, and a spiral rotation speed of 12r / min-20r / min; the washing overflow particle size is controlled to be 50%-60% of -200 mesh; the wet screening equipment uses an arc vibrating screen with a mesh size of 1mm-2mm, and the undersize product particle size is 50%-60% of -200 mesh; the high-pressure roller grinding operation uses a stud high-pressure roller mill, with a pressure roller surface linear velocity of 0.5m / s-0.8m / s and a hydraulic pressure of 8Mpa-10Mpa.

[0021] Preferably, in the step S2, the weak magnetic roughing operation has a magnetic field strength of 199.04kA / m-318.47kA / m, and the weak magnetic cleaning operation has a magnetic field strength of 95.54kA / m-159.24kA / m; the strong magnetic roughing and strong magnetic scavenging both use Slon vertical ring pulsating high gradient magnetic separators, with magnetic field strengths of 636.94kA / m-796.18kA / m and 955.41kA / m-1194.27kA / m, respectively.

[0022] Preferably, in the step S3, the cyclone classification operation uses a small cone angle hydrocyclone, with a hydrocyclone cone angle of 5°-10° and a feed pressure of 0.05MPa-0.10MPa; the cyclone classification overflow particle size is controlled to be 85%-95% of -325 mesh; the feed concentration of the trough gravity separation roughing is controlled to be 20%-30%, and the feed concentration of the trough gravity separation cleaning is controlled to be 25%-35%.

[0023] Preferably, in the step S4, the pre-classification operation uses a high-frequency vibration fine screen / hydrocyclone, with undersize product / overflow particle size controlled to be 90%-95% of -200 mesh; the grinding equipment uses a vertical stirred mill, with a grinding concentration of 45%-55%; the strong magnetic roughing operation uses a Slon vertical ring pulsating high gradient magnetic separator, with a magnetic field strength controlled to be 636.94kA / m-796.18kA / m.

[0024] Preferably, in the step S5, the underflow concentration of the concentration operation is controlled to be 25%-35%.

[0025] Further; in the S2 step, the magnetic field strength of the low-intensity roughing operation is 199.04 kA / m-318.47 kA / m, the magnetic field strength of the low-intensity cleaning operation is 95.54 kA / m-159.24 kA / m, the high-intensity roughing operation and the high-intensity scavenging operation both use Slon vertical ring pulsating high-gradient magnetic separators, and the magnetic field strengths are 636.94 kA / m-796.18 kA / m and 955.41 kA / m-1194.27 kA / m, respectively; in the S3 step, the hydrocyclone with a small cone angle is used for the cyclone classification operation, the cone angle of the hydrocyclone is 5°-10°, the feeding pressure is 0.05 MPa-0.10 MPa, and the overflow particle size of the cyclone classification operation is controlled to be 85%-95% of -325 mesh; in the S3 step, the feeding concentration of the roughing operation of the chute gravity separation is controlled to be 20%-30%, and the feeding concentration of the cleaning operation of the chute gravity separation is controlled to be 25%-35%; in the S4 step, the high-frequency vibration fine screen / hydrocyclone is used for the pre-classification operation, the undersize product / overflow particle size is controlled to be 90%-95% of -200 mesh, and the grinding equipment uses a vertical stirring mill, and the grinding concentration is 45%-55%; the high-intensity roughing operation uses a Slon vertical ring pulsating high-gradient magnetic separator, and the magnetic field strength is controlled to be 636.94 kA / m-796.18 kA / m; in the S5 step, the underflow concentration of the thickening operation is controlled to be 25%-35%, and the underflow particle size of the thickening operation is controlled to be 80%-90% of -325 mesh.

[0026] The specific values of the above grinding particle size, magnetic field strength, flotation times, and reagent dosage can be determined according to the ore properties through laboratory test research results. The concentration here is the mass concentration, and the undersize product particle size ratio also refers to the mass ratio of a particle size in the undersize product.

[0027] Compared with the prior art, the weathered crust type magnetic and brown hematite mixed iron ore high-efficiency energy-saving beneficiation process has the following advantages:

[0028] (1) The present application is characterized by high mud content in the selected ore. The washing operation and wet screening operation are combined before the ore is fed into the high-pressure roller mill, and more than 50% of the particle size of the qualified product is separated out, which not only creates conditions for the high-pressure roller mill operation (material is loose, no mud ball, no clinker), greatly improves the crushing efficiency of the high-pressure roller mill, but also avoids overgrinding of the ore.

[0029] (2) The single-spiral trough type washing machine is used for the washing operation, and the arc-shaped vibrating screen is used for the wet screening operation, which improves the comprehensive efficiency of washing and screening, and is advanced in technology and reliable in operation.

[0030] (3) The present application is directed to the fact that the useful iron mineral species of the selected ore is various, and the magnetic separation, gravity separation and flotation method is sequentially used to recover the magnetite, hematite and limonite in the ore according to the principles of 'easy collection and early collection' and'staged tailing throwing', so that the separation effect is good, the process flow is stable and reliable, and the applicability is strong.

[0031] (4) The present application has obtained most of the iron concentrate before reverse flotation, and most of the tailings are thrown out, so that the flotation amount is small, the flotation reagent consumption is low, and the process flow is relatively simple, the environmental pollution is extremely small, the cost is low, and the economic benefits are high.

[0032] (5) The beneficiation process provided by the present application can make full use of a large amount of similar mixed iron ore in China, and has important significance for alleviating the situation of insufficient supply of iron ore resources in China. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The present application is a weathering crust type magnetic hematite limonite mixed iron ore efficient and energy-saving beneficiation process principle process flow chart.

[0034] Figure 2 The present application is a principle flow chart of the raw ore crushing-washing-roller grinding-screening process.

[0035] Figure 3 The present application is a principle flow chart of the selected product magnetic-heavy-floatation combined beneficiation process.

[0036] Figure 4 The present application is a numerical and quality flow chart of the raw ore crushing-washing-roller grinding-screening process in the embodiment of the present application.

[0037] Figure 5 The present application is a numerical and quality flow chart of the selected product magnetic-heavy-floatation combined beneficiation process in the embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to further describe the present application, the present application of a weathering crust type magnetic hematite limonite mixed iron ore efficient and energy-saving beneficiation process will be further described in detail in combination with the drawings and embodiments.

[0039] It should be noted that any modification, equivalent replacement, improvement, etc. within the technical idea and principles of the present application should be included in the protection scope of the present application. In addition, the embodiments described below are exemplary and should not be understood as limiting the present application.

[0040] The ore sample used in the embodiment is a high-silt, high-iron-containing clay, easy-to-crush, easy-to-pulverize, magnetic, red-brown mixed iron ore from a certain iron mine in China. The main chemical component analysis results of the ore are shown in Table 1, the iron phase analysis results of the ore are shown in Table 2, the main mineral composition results of the ore are shown in Table 3, and the wet screening particle size composition analysis results of the raw ore are shown in Table 4.

[0041] Table 1: Main chemical component analysis results of the ore

[0042] Ingredients TFe SiO2 Al2O3 CaO MgO [K2O] Na2O Content / % 43.60 24.89 5.64 0.18 0.39 0.07 0.10 Ingredients MnO TiO2 Cl Cr2O3 S P Loss on ignition Content / % 0.73 0.25 0.01 0.02 0.07 0.06 6.38

[0043] Table 2: Iron phase analysis results of the ore

[0044]

[0045] Table 3: Main mineral composition results

[0046] Mineral name Hematite Goethite Pseudohematite Magnetite Pyrite, pyrrhotite Content / % 21.65 18.00 14.70 7.64 0.15 Mineral name Quartz Clay Iron-bearing clay Mica Hydrous aluminosilicates Content / % 19.92 6.53 4.22 1.70 1.71 Mineral name Pyroxene Chlorite Carbonates Others Total Content / % 0.80 1.42 0.60 0.96 100.00

[0047] Table 4: Wet screening particle size composition analysis results of the raw ore

[0048]

[0049]

[0050] The analysis results of Tables 1-4 show that the TFe grade of the ore is 43.60%, the main useful minerals are magnetite, pseudomorphic hematite, red and brown iron ore, and the brown iron ore is easy to be pulverized during grinding; there is a certain amount of iron-containing clay in the gangue minerals, which is extremely easy to deteriorate the recovery index of weak magnetic minerals due to its weak magnetism; the -1mm particle size yield of the raw ore is 55.48%, indicating that more than 50% of the ore can be directly selected by screening without crushing; and the -0.030mm particle size yield of the raw ore is 16.23%, indicating that the ore has a high silt content.

[0051] As shown in the principle process flow chart of the high-efficiency and energy-saving beneficiation process for weathering crust type magnetic red-brown mixed iron ore of the present application shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that the specific process steps and parameters used in the embodiment of the present application are as follows:

[0052] S1 dry screening-crushing-washing-wet screening-high pressure roller grinding

[0053] The raw ore is subjected to dry screening to obtain dry screening oversize product and dry screening undersize product, the dry screening oversize product is fed into a crushing device for crushing, and the crushed product is returned to the dry screening operation; the dry screening undersize product is subjected to ore washing to obtain ore washing overflow and ore washing return sand, the ore washing return sand is fed into a wet screening device for screening to obtain wet screening oversize product and wet screening undersize product, and the wet screening oversize product is returned to the wet screening operation after being subjected to high-pressure roller grinding; the ore washing overflow and the wet screening undersize product are combined to obtain a feed product, and the particle size of the feed product is 57% of -200 mesh. The dry screening operation adopts a linear vibrating screen with a screen size of 30 mm; the crushing device adopts a jaw crusher; the ore washing operation adopts a single-spiral trough type ore washer, the spiral lifting angle is 25°, the ore washing concentration is 15%, and the spiral rotation speed is 16 rpm, and the particle size of the ore washing overflow is controlled to be 55% of -200 mesh; the wet screening device adopts an arc vibrating screen with a screen size of 1 mm, and the particle size of the undersize product is 59% of -200 mesh; and the high-pressure roller grinding operation adopts a stud type high-pressure roller mill, the pressure roller surface linear speed is 0.6 m / s, and the hydraulic pressure is 9 MPa.

[0054] S2 weak magnetic - strong magnetic

[0055] The feed product obtained in the S1 step is subjected to weak magnetic - strong magnetic operation, the weak magnetic operation includes weak magnetic roughing and weak magnetic cleaning, the strong magnetic operation includes strong magnetic roughing and strong magnetic scavenging, respectively to obtain weak magnetic concentrate, strong magnetic roughing concentrate, strong magnetic scavenging concentrate, the strong magnetic roughing concentrate and the strong magnetic scavenging concentrate are combined to obtain strong magnetic comprehensive concentrate, and the strong magnetic scavenging tailings are discharged. The magnetic field strength of the weak magnetic roughing operation is 278.66 kA / m, and the magnetic field strength of the weak magnetic cleaning operation is 159.24 kA / m; the strong magnetic roughing and the strong magnetic scavenging both adopt Slon vertical ring pulsating high gradient magnetic separators, and the magnetic field strengths are 796.18 kA / m and 955.41 kA / m, respectively.

[0056] S3 cyclone classification - chute gravity separation

[0057] The strong magnetic comprehensive concentrate obtained in the S2 step is subjected to cyclone classification operation to obtain cyclone classification overflow and cyclone classification sand, the cyclone classification sand is subjected to chute gravity separation operation, the chute gravity separation operation includes chute gravity separation roughing and chute gravity separation cleaning, to obtain spiral chute cleaning concentrate, and spiral chute roughing tailings and spiral chute cleaning tailings are discharged, the spiral chute roughing tailings and the spiral chute cleaning tailings are combined to obtain chute gravity separation tailings. The cyclone classification operation adopts a small cone angle hydrocyclone, the cone angle of the hydrocyclone is 8°, and the feeding pressure is 0.06 MPa; the particle size of the cyclone classification overflow is controlled to be 90% of -325 mesh; the feeding concentration of the chute gravity separation roughing is controlled to be 25%, and the feeding concentration of the chute gravity separation cleaning is controlled to be 30%.

[0058] S4 pre-classification-grinding-magnetic separation

[0059] The sluice tailings discharged from S3 are fed into a pre-classification operation to obtain pre-classification overflow and pre-classification return sand, the pre-classification return sand is fed into a grinding device for grinding, and the grinding product is returned to the classification operation; the pre-classification overflow is fed into a rough magnetic separation operation to obtain rough magnetic separation concentrate and discharge rough magnetic separation tailings. The pre-classification operation uses a high-frequency vibration fine screen, and the undersize product / overflow particle size is controlled to be 92% passing -200 mesh; the grinding device uses a vertical stirring mill, and the grinding concentration is 50%; the rough magnetic separation operation uses a Slon vertical ring pulsating high gradient magnetic separator, and the magnetic field strength is controlled to be 796.18 kA / m.

[0060] S5 concentration-reverse flotation

[0061] The rough magnetic separation concentrate obtained in S4 and the pre-classification overflow are combined and fed into a concentration operation to obtain a concentration operation underflow, the concentration operation underflow concentration is controlled to be 30%, and the particle size is 85% passing -325 mesh; the concentration operation underflow is fed into a reverse flotation operation to obtain reverse flotation concentrate and reverse flotation tailings, the reverse flotation concentrate and the weak magnetic separation iron concentrate obtained in S2 and the spiral sluice concentrate obtained in S3 are combined to obtain the final iron concentrate; the reverse flotation tailings and the strong magnetic scavenging tailings discharged in S2 and the rough magnetic separation tailings discharged in S4 are combined to obtain the final total tailings; the reverse flotation operation uses one roughing and one cleaning, and the reagent dosage of each operation is calculated according to the dry ore amount of the reverse flotation operation feed:

[0062] Reverse flotation roughing: sodium hydroxide dosage for pulp pH adjustment is 1600 g / t, sodium hexametaphosphate dosage for dispersant is 25 g / t, starch dosage for depressant is 400 g / t, and dodecylamine dosage for collector is 800 g / t; reverse flotation cleaning: dodecylamine dosage for collector is 400 g / t.

[0063] The weathered crust type magnetic and brown hematite mixed iron ore can obtain a magnetic separation iron concentrate with a yield of 19.80% and an iron grade of 63.61%, a gravity separation iron concentrate with a yield of 23.33% and an iron grade of 62.15%, and a flotation iron concentrate with a yield of 9.28% and an iron grade of 60.74% after the above process, and the three combined can obtain a comprehensive iron concentrate with a yield of 52.41%, an iron grade of 62.45%, and an iron recovery rate of 75.08%.

[0064] The above is the embodiment of the present application, but the above examples are only used to help understand the method of the present application and its core idea, and are not equivalent to the specific embodiments described above. For those skilled in the art, make several improvements, refinements or changes to the present application, and combine the above technical features in a proper way, or without improvement, the application of the concept and technical solution of the present application to other fields directly, should be regarded as the protection scope of the present application.

Claims

1. A high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore, characterized in that Use the following steps to implement: S1 dry screening - crushing - ore washing - wet screening - high pressure roller grinding The raw ore is dry screened to obtain dry screen oversize and dry screen undersize. The dry screen oversize is fed into the crushing equipment for crushing, and the crushed product is returned to the dry screening operation. The dry screen undersize is washed to obtain washing overflow and washing return sand. The washing return sand is fed into the wet screening equipment for screening to obtain wet screen oversize and wet screen undersize. The wet screen oversize is passed through the high-pressure roller grinding operation and returned to the wet screening operation. The washing overflow and wet screen undersize are combined into the selected product. S2 weak magnetic field - strong magnetic field The selected products obtained in step S1 are fed into a weak magnetic-strong magnetic process, wherein the weak magnetic process includes weak magnetic roughing and weak magnetic concentrating, and the strong magnetic process includes strong magnetic roughing and strong magnetic scavenging, respectively obtaining weak magnetic iron concentrate, strong magnetic roughing concentrate, and strong magnetic scavenging concentrate. The strong magnetic roughing concentrate and the strong magnetic scavenging concentrate are combined into a strong magnetic comprehensive concentrate, and the strong magnetic scavenging tailings are discharged; S3 cyclone classification-chute gravity separation The high-intensity magnetic separation comprehensive concentrate obtained in step S2 is fed into a cyclone classification operation to obtain a cyclone classification overflow and a cyclone classification sand settling, and the cyclone classification sand settling is fed into a chute gravity separation operation, wherein the chute gravity separation operation includes a chute gravity separation roughing operation and a chute gravity separation concentrating operation to obtain a spiral chute concentrating concentrate, and the spiral chute roughing tailings and the spiral chute concentrating tailings are discharged, and the spiral chute roughing tailings and the spiral chute concentrating tailings are combined into the chute gravity separation tailings; S4 Pre-classification - Grinding - High-intensity magnetic separation Feeding the chute gravity separation tailings discharged from step S3 into a pre-classification process to obtain pre-classification overflow and pre-classification return sand, feeding the pre-classification return sand into a grinding device for grinding, and returning the ground product to the classification process; The pre-classified overflow is fed into the strong magnetic roughing operation to obtain the strong magnetic roughing concentrate, and the strong magnetic roughing tailings are discharged; S5 Concentration-Reverse Flotation The strong magnetic roughing concentrate obtained in step S4 and the pre-classification overflow are combined and fed into the concentration operation to obtain the concentration operation underflow, which is fed into the reverse flotation operation to obtain the reverse flotation concentrate and reverse flotation tailings. The reverse flotation concentrate, the weak magnetic iron concentrate obtained in step S2, and the spiral chute concentrate obtained in step S3 are combined to form the final iron concentrate; the reverse flotation tailings, the strong magnetic scavenging tailings discharged in step S2, and the strong magnetic roughing tailings discharged in step S4 are combined to form the final total tailings; the reverse flotation operation adopts one roughing and one concentrating, and the amount of reagents used in each operation is calculated based on the dry ore amount fed to the reverse flotation operation: Reverse flotation roughing: the dosage of slurry pH adjuster sodium hydroxide is 1000g / t~2000g / t, the dosage of dispersant sodium hexametaphosphate is 20g / t~40g / t, the dosage of inhibitor starch is 300g / t~500g / t, the dosage of collector dodecylamine is 600g / t~900g / t; reverse flotation cleaning: the dosage of collector dodecylamine is 300g / t~500g / t.

2. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 1, characterized in that: In step S1, the dry screening operation adopts a linear vibrating screen with a mesh size of 20 mm to 40 mm; the crushing equipment adopts a jaw crusher; the ore washing operation adopts a single spiral trough ore washer, the spiral lifting angle is 20° to 30°, the ore washing concentration is 10% to 20%, the spiral speed is 12 rpm to 20 rpm, and the overflow particle size of the ore washing is controlled to -200 mesh, accounting for 50% to 60%.

3. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 2, characterized in that: In step S1, the wet screening equipment uses an arc-shaped vibrating screen with a mesh size of 1 mm to 2 mm, and the particle size of the product under the screen is -200 mesh, accounting for 50% to 60%; the high-pressure roller grinding operation uses a pin-type high-pressure roller grinding machine, the surface linear speed of the roller is 0.5 m / s to 0.8 m / s, and the hydraulic pressure is 8 MPa to 10 MPa.

4. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 1, characterized in that: In step S2, the magnetic field strength of the weak magnetic roughing operation is 199.04 kA / m to 318.47 kA / m, and the magnetic field strength of the weak magnetic cleaning operation is 95.54 kA / m to 159.24 kA / m.

5. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 4, characterized in that: In step S2, the strong magnetic roughing separation and strong magnetic sweeping separation both use a Slon vertical ring pulsating high gradient strong magnetic separator, and the magnetic field strength is 636.94kA / m~796.18kA / m and 955.41kA / m~1194.27kA / m respectively.

6. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 1, characterized in that: In step S3, the cyclone classification operation adopts a small cone angle hydrocyclone with a cone angle of 5° to 10° and a feed pressure of 0.05MPa to 0.10MPa; the overflow particle size of the cyclone classification is controlled to be -325 mesh, accounting for 85% to 95%.

7. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 6, characterized in that: In step S3, the feed concentration of the roughing chute gravity separation is controlled to be 20% to 30%, and the feed concentration of the fine chute gravity separation is controlled to be 25% to 35%.

8. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 1, characterized in that: In step S4, the pre-grading operation uses a high-frequency vibrating fine screen / hydrocyclone, and the undersize product / overflow particle size is controlled to -200 mesh, accounting for 90% to 95%; the grinding equipment uses a vertical stirred mill, and the grinding concentration is 45% to 55%; the strong magnetic roughing operation uses a Slon vertical ring pulsating high-gradient strong magnetic separator, and the magnetic field strength is controlled to be 636.94kA / m to 796.18kA / m.

9. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 1, characterized in that: In step S5, the underflow concentration of the concentration operation is controlled to be 25% to 35%.

10. The high-efficiency and energy-saving beneficiation process for weathering crust type magnetic hexagonal mixed iron ore according to claim 3, characterized in that: In step S2, the magnetic field strength of the weak magnetic roughing operation is 199.04kA / m~318.47kA / m, and the magnetic field strength of the weak magnetic concentrating operation is 95.54kA / m~159.24kA / m; the strong magnetic roughing and strong magnetic sweeping both use Slon vertical ring pulsating high gradient strong magnetic separator, and the magnetic field strength is 636.94kA / m~796.18kA / m and 955.41kA / m~1194.27kA / m respectively; In step S3, the cyclone classification operation adopts a small cone angle hydrocyclone, the cone angle of the hydrocyclone is 5° to 10°, and the feed pressure is 0.05MPa to 0.10MPa; the overflow particle size of the cyclone classification is controlled to be -325 mesh, accounting for 85% to 95%; in step S3, the feed concentration of the chute gravity separation roughing is controlled to be 20% to 30%, and the feed concentration of the chute gravity separation fine selection is controlled to be 25% to 35%; In step S4, the pre-grading operation uses a high-frequency vibrating fine screen / hydrocyclone, and the undersize product / overflow particle size is controlled to be -200 mesh, accounting for 90% to 95%; the grinding equipment uses a vertical stirred mill, and the grinding concentration is 45% to 55%; the strong magnetic roughing operation uses a Slon vertical ring pulsating high gradient strong magnetic separator, and the magnetic field strength is controlled to be 636.94kA / m to 796.18kA / m; In step S5, the concentration of the underflow of the concentration operation is controlled to be 25% to 35%, and the particle size of the underflow of the concentration operation is controlled to be 80% to 90% of -325 mesh.

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