Combined beneficiation process for weathered crust type high mud content mixed iron ore of magnetite, red and brown iron

Abstract

This invention discloses a combined beneficiation process for weathered crust-type high-mud-content mixed iron ore of magnetic, red, and brown varieties. The raw ore is crushed, dry-screened, washed, high-pressure roller milled, and wet-screened to obtain qualified feed products. The feed products are then subjected to weak magnetic separation to obtain magnetic iron concentrate and weak magnetic tailings. The weak magnetic tailings are then subjected to strong magnetic separation, cyclone classification, and sluice box gravity separation to obtain gravity iron concentrate, sluice box gravity tailings, cyclone classification overflow, and strong magnetic scavenging tailings. The sluice box gravity tailings are then subjected to grinding classification and strong magnetic roughing to obtain strong magnetic roughing concentrate and strong magnetic roughing tailings. The strong magnetic roughing concentrate and cyclone classification overflow are combined and then subjected to reverse flotation to obtain flotation iron concentrate and reverse flotation total tailings. The reverse flotation collector MX is a mixture of etheramine, ether diamine, and quaternary ammonium salt with a molar ratio of 1:(1.2~2.0):(1.5~2.5). This invention has the advantages of good sorting effect, stable and reliable process flow, strong applicability, relatively low energy consumption and cost in mineral processing, minimal environmental pollution, and high comprehensive economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of mixed iron ore beneficiation technology, specifically relating to a beneficiation process for high-mud mixed iron ore, used for the beneficiation of mixed iron ore with high mud content and coexistence of magnetic, hematite, and limonite minerals, with an iron grade of 35% to 45% and a particle size content of -0.030mm ≥15.0%. Background Technology

[0002] With the rapid development of the steel industry, magnetite and hematite resources with good geological conditions, large crystals, and good beneficiation are becoming increasingly scarce. Meanwhile, iron ore resources in Kanbu with fine particle size, multiple iron minerals coexisting, high mud content, and poor beneficiation will become the focus of mineral processing technology research.

[0003] Complex and refractory iron ore constitutes a significant proportion of my country's iron ore resources. The total reserves of typical refractory iron ore resources such as siderite, limonite, and fine-grained ore alone exceed 20 billion tons. Due to the fine crystal size, complex mineral composition, and close symbiotic relationship of these iron ore resources, it is difficult to obtain good technical and economic indicators using conventional beneficiation techniques. Most of these resources have not yet been industrially developed and utilized. Although some resources have been developed, the beneficiation process is complex and costly, and the recovery rate is generally only 60% to 65%, or even less than 50%. There is an urgent need to carry out technological research on complex and refractory iron ore resources, which is essential to ensuring the security of my country's iron ore resources.

[0004] To address the beneficiation problem of mixed iron ore, Chinese patent application 201910014741.8 discloses a beneficiation process for difficult-to-process mixed iron ore containing multiple iron minerals. The process involves feeding raw ore with an iron content of 21%–23% and a particle size of 250 mm–0 mm into a primary autogenous mill to obtain an autogenous grinding product with a particle size of 30 mm–0 mm. This autogenous grinding product is then fed into a double-layer linear vibrating screen to obtain three screening products with particle sizes of +10 mm, 10 mm–1 mm, and 1 mm–0 mm. These three screening products are then subjected to targeted grinding, dry magnetic separation, wet magnetic separation, and reverse flotation to achieve a final concentrate grade of over 64.5%. However, research indicates that this beneficiation process is difficult to apply to mixed iron ore with high mud content and coexisting magnetoresin (GMO) minerals.

[0005] To address the technical challenges of beneficiating fine-grained mixed iron ore, the journal *Gansu Metallurgy* published a paper in its 2024, No. 4 issue, titled "Experimental Study on Beneficiation of Fine-Grained Strongly and Weakly Magnetic Mixed Iron Ore in Subei County, Gansu Province." The raw ore treated in the experiment contained 30% magnetic iron minerals, 19% hematite (brownish), and 3% iron carbonate. The experiment involved three stages of grinding and magnetic separation of the pre-selected concentrate, yielding a concentrate TFe content of 64.32% and a metal recovery rate of 60.92%. Clearly, this process did not adequately consider the efficient recovery of hematite (brownish) and iron carbonate from the ore, resulting in a low iron recovery rate and a high iron loss rate in the tailings.

[0006] Weathered crust type mixed iron ore is a complex and difficult-to-process iron ore, characterized by a variety of iron minerals, high clay content, high iron-bearing clay, easy crushing, and easy mudification. This type of iron ore is mainly distributed in Hunan, Hubei, Jiangxi, Guangdong, Guangxi, and Hainan provinces of my country. This is primarily because southern my country is mostly located in low-latitude regions, belonging to the tropical and subtropical zones, with a warm and humid climate and strong weathering. Current beneficiation processes are extremely ineffective for weathered crust type mixed iron ore, resulting in low resource utilization and significant iron loss.

[0007] Washing is an effective pretreatment method for high-mud iron ore. Coarse and fine classification, and separate beneficiation, are important ways to improve beneficiation efficiency. More crushing and less grinding are key to reducing beneficiation costs. Combined magnetic-gravity-flotation separation is an important beneficiation method for utilizing mixed iron ores containing both magnetic and reddish-brown minerals. Therefore, developing a highly efficient and energy-saving beneficiation process for mixed iron ores with multiple types of useful iron minerals, high mud content, high iron clay content, easy crushing, and easy mudification is urgently needed. Summary of the Invention

[0008] To address the problems of poor beneficiation effect and low resource utilization rate of difficult-to-benefit magnetic red and brown mixed iron ore with high mud content, high iron content, easy crushing and easy mudification in existing technologies, this invention provides a combined beneficiation process for weathered crust type high mud content magnetic, red and brown mixed iron ore with good beneficiation effect, stable and reliable process flow, strong applicability, and relatively low beneficiation energy consumption and cost.

[0009] To achieve the above-mentioned objectives of this invention, the combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) is implemented using the following processes and steps:

[0010] S1 dry screening – crushing – washing – wet screening – high-pressure roller mill

[0011] The raw ore undergoes dry screening to obtain dry screen oversize and dry screen undersize products. The dry screen oversize products are fed into crushing equipment for crushing, and the crushed products are returned to the dry screening operation. The dry screen undersize products undergo washing to obtain washing overflow and washing return sand. The washing return sand is fed into wet screening equipment to obtain wet screen oversize and wet screen undersize products. The wet screen oversize products are returned to the wet screening operation after high-pressure roller milling. The washing overflow and wet screen undersize products are combined into the feed products. Using dry pre-screening before crushing reduces the amount of ore fed into the crusher and lowers the energy consumption of the crushing operation. Using washing and wet screening operations before high-pressure roller milling not only reduces the amount of ore fed into the high-pressure roller mill and lowers the energy consumption of the high-pressure roller mill operation, but more importantly, it eliminates the adverse effects of mud lumps and agglomerates on the high-pressure roller mill operation.

[0012] S2 Weak Magnetic Field - Strong Magnetic Field

[0013] The selected product obtained in step S1 is fed into a weak magnetic-strong magnetic separation process. The weak magnetic separation process includes weak magnetic roughing and weak magnetic cleaning, while the strong magnetic separation process includes strong magnetic roughing and strong magnetic scavenging. This yields weak magnetic iron concentrate, strong magnetic roughing concentrate, and strong magnetic scavenging concentrate, respectively. The strong magnetic roughing concentrate and strong magnetic scavenging concentrate are combined into a strong magnetic composite concentrate, and the strong magnetic scavenging tailings are discharged. In this step, high-grade iron concentrate with an iron content >63.0% is obtained in advance through weak magnetic cleaning, and qualified tailings are removed in advance through strong magnetic scavenging. This reduces the amount of ore fed into subsequent gravity separation, strong magnetic roughing, grinding, and reverse flotation operations, and significantly reduces grinding energy consumption.

[0014] S3 Cyclone Classification - Sluice Reselection

[0015] The high-intensity magnetic separation concentrate obtained in step S2 is fed into a cyclone classifier to obtain cyclone classifier overflow and cyclone classifier underflow. The cyclone classifier underflow is fed into a sluice gravity separation process, which includes sluice gravity roughing and sluice gravity cleaning to obtain spiral sluice gravity cleaner concentrate. Spiral sluice gravity roughing tailings and spiral sluice gravity cleaner tailings are discharged and combined into sluice gravity cleaner tailings. In this step, the cyclone classifier underflow (coarse-grained fraction) from the cyclone classifier is further processed into high-grade iron concentrate with an iron content >62.5% through sluice gravity roughing and sluice gravity cleaning, reducing the amount of subsequent grinding operations and lowering grinding energy consumption.

[0016] S4 pre-classification – grinding – high-intensity magnetic separation

[0017] The tailings from the gravity separation sluice gate discharged in step S3 are fed into the pre-classification operation to obtain pre-classification overflow and pre-classification return sand. The pre-classification return sand is fed into the grinding equipment for grinding, and the grinding product is returned to the classification operation. The pre-classification overflow is fed into the high-intensity magnetic roughing operation to obtain high-intensity magnetic roughing concentrate, and the high-intensity magnetic roughing tailings are discharged. In this step, the overflow from the cyclone classification is further treated by high-intensity magnetic roughing to remove qualified tailings and to improve the iron grade fed into the subsequent reverse flotation operation.

[0018] S5 Concentration - Reverse Flotation

[0019] The strong magnetic roughing concentrate obtained in step S4 and the pre-classified overflow are combined and fed into the thickening operation to obtain the thickening underflow. The thickening underflow is then fed into the reverse flotation operation to obtain reverse flotation concentrate and reverse flotation tailings. The reverse flotation concentrate, the weak magnetic iron concentrate obtained in step S2, and the spiral sluice concentrator concentrate obtained in step S3 are combined to form the final iron concentrate. The reverse flotation tailings, the strong magnetic scavenging tailings discharged from step S2, and the strong magnetic roughing tailings discharged from step S4 are combined to form the final total tailings. The final total tailings are used as raw material for iron corrective agents in iron-containing silicate cement plants. The reverse flotation operation adopts a single roughing and one... For secondary refining, the reagent dosage for each operation is calculated based on the dry ore feed rate of the reverse flotation operation: sodium hydroxide (pH adjuster) 500g / t~1000g / t, sodium hexametaphosphate (dispersant) 10g / t~30g / t, starch (inhibitor) 200g / t~400g / t, and collector MX 500g / t~1000g / t; for reverse flotation refining: collector MX 200g / t~600g / t; the collector MX is a mixture of etheramine, ether diamine, and quaternary ammonium salt, with a molar ratio of 1:(1.2~2.0):(1.5~2.5). In this step, collector MX is a mixture of etheramine, ether diamine, and quaternary ammonium salt, which fully utilizes the combined and synergistic effects of the three agents. For example, etheramine is easily dispersed in the pulp, requiring a low dosage and resulting in good flotation performance; ether diamine has strong collecting performance, but when used alone, its dispersion is poor and its consumption is high. When mixed with etheramine, its dispersion in the pulp is significantly improved; quaternary ammonium salt, at appropriate dosages, has good selectivity, but its collecting performance is not ideal when used alone. Studies have shown that a suitable combination of the three agents in appropriate proportions, with appropriate dosages, can achieve the highest iron concentrate grade and iron recovery rate.

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

[0021] Preferably, in step S2, the magnetic field strength of the weak magnetic coarse separation operation is 199.04 kA / m to 318.47 kA / m, and the magnetic field strength of the weak magnetic fine separation operation is 95.54 kA / m to 159.24 kA / m; the strong magnetic coarse separation and strong magnetic sweeping both adopt the Slon vertical ring pulsating high gradient strong magnetic separator, with magnetic field strengths of 636.94 kA / m to 796.18 kA / m and 955.41 kA / m to 1194.27 kA / m, respectively.

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

[0023] Preferably, in step S4, the pre-grading operation uses a high-frequency vibrating fine screen / hydrocyclone, and the undersize / 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 636.94 kA / m to 796.18 kA / m.

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

[0025] Further; in step S2, the magnetic field strength of the weak magnetic coarse separation operation is 199.04 kA / m to 318.47 kA / m, and the magnetic field strength of the weak magnetic fine separation operation is 95.54 kA / m to 159.24 kA / m. Both the strong magnetic coarse separation and strong magnetic sweeping separation use a Slon vertical ring pulsating high gradient strong magnetic separator with magnetic field strengths of 636.94 kA / m to 796.18 kA / m and 955.41 kA / m to 1194.27 kA / m, respectively. In step S3, the cyclone classification operation uses a small cone angle hydrocyclone with a cone angle of 5° to 10° and a feed pressure of 0.05 MPa to 0.10 MPa. The overflow particle size of the cyclone classification is controlled to be -325 mesh, accounting for 85%. 95%; In step S3, the feed concentration for the sluice gravity separation roughing is controlled at 20%–30%, and the feed concentration for the sluice gravity separation cleaning is controlled at 25%–35%; In step S4, the pre-classification operation uses a high-frequency vibrating fine screen / hydrocyclone, and the undersize / overflow particle size is controlled at -200 mesh, accounting for 90%–95%; the grinding equipment uses a vertical stirred mill, and the grinding concentration is 45%–55%; the strong magnetic roughing operation uses a Slon vertical ring pulsating high gradient strong magnetic separator, and the magnetic field strength is controlled at 636.94 kA / m–796.18 kA / m; In step S5, the underflow concentration for the thickening operation is controlled at 25%–35%, and the underflow particle size for the thickening operation is controlled at -325 mesh, accounting for 80%–90%.

[0026] The specific values ​​of the above-mentioned grinding particle size, magnetic field strength, flotation times, and reagent dosage can be determined based on the ore properties and through laboratory experimental research results. All concentrations here are mass concentrations, and the percentage of undersize particles refers to the mass percentage of a specific particle size within the undersize product.

[0027] Compared with existing technologies, the combined beneficiation process for weathered crust-type high-mud-content mixed iron ore of the present invention has the following advantages:

[0028] (1) In view of the high mud content of the feed ore, the present invention adopts a combination of washing operation and wet screening operation before the ore is fed into the high pressure roller mill, and separates more than 50% of the qualified feed products. This not only creates conditions for the high pressure roller mill operation (the material is loose, without mud clumps or agglomerates), but also greatly improves the crushing efficiency of the high pressure roller mill and avoids the over-crushing of the ore.

[0029] (2) The washing operation of this invention adopts a single spiral trough washing machine, and the wet screening operation adopts an arc vibrating screen, which improves the overall efficiency of washing and screening. The technology is advanced and the operation is reliable.

[0030] (3) This invention addresses the issue of multiple types of useful iron minerals in the feed ore, achieving "segmented fine separation" through weak magnetic separation, spiral sluice gravity separation, and reverse flotation, and "segmented tailings removal" through strong magnetic separation and reverse flotation. The invention sequentially employs magnetic separation, gravity separation, and flotation to recover magnetite, hematite, and limonite from the ore, resulting in good separation effect, stable and reliable process flow, and strong applicability.

[0031] (4) The present invention has obtained most of the iron concentrate and discarded most of the tailings before reverse flotation. The amount of ore fed into the flotation is small and the consumption of flotation reagents is low. It has the advantages of relatively simple process flow, minimal environmental pollution, low cost and high economic benefits.

[0032] (5) In the reverse flotation operation of the present invention, a mixture of etheramine, etherdiamine and quaternary ammonium salt MX is used as a combined collector. This combined collector gives full play to the combination and synergistic effect of the three reagents. Compared with the use of a single reagent, the iron recovery rate is increased by more than 2 percentage points when the iron concentrate grade is similar, and the iron concentrate grade is increased by 0.8 to 1.2 percentage points when the iron recovery rate remains unchanged. Moreover, the amount of collector used is reduced by more than 20%.

[0033] (6) Through the mineral processing technology provided by this invention, a comprehensive iron concentrate with TFe > 62.3% and an iron recovery rate greater than 77.0% can be obtained. The final total tailings can be used as raw material for iron-containing silicate cement plants as an iron corrective agent, thus achieving full utilization and zero tailings discharge of such resources. After its widespread application, it can make full use of a large amount of similar difficult-to-process mixed iron ore in my country, which is of great significance in alleviating the shortage of iron ore resources in my country. Attached Figure Description

[0034] Figure 1 This is a process flow diagram illustrating the principle of the combined beneficiation process for weathered crust-type high-mud-content mixed iron ore of magnetic, red, and brown varieties, as described in this invention.

[0035] Figure 2 This is a flowchart illustrating the principle of the raw ore crushing-washing-roll milling-screening process used in this invention.

[0036] Figure 3 This is a flowchart illustrating the principle of the magnetic-gravity-flotation combined mineral processing technology for the selected products used in this invention.

[0037] Figure 4 This is a flow chart of the raw ore crushing-washing-roll milling-screening process used in the embodiments of the present invention.

[0038] Figure 5 This is a flow chart of the magnetic-gravity-flotation combined mineral processing technology used in the embodiments of the present invention. Detailed Implementation

[0039] To further describe the present invention, the combined beneficiation process for weathered crust-type high-mud-content mixed iron ore of magnetite, red ore, and brown ore will be described in more detail below with reference to the accompanying drawings and embodiments.

[0040] It should be noted that any modifications, equivalent substitutions, or improvements made within the technical concept and principles of this invention should be included within the scope of protection of this invention. Furthermore, the embodiments described below are exemplary and should not be construed as limiting the invention.

[0041] The ore sample used in this embodiment is a magnetic and reddish-brown mixed iron ore from a certain iron mine in China, which is high in clay and iron content, easy to crush and easy to muddy. The main chemical composition 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 particle size distribution analysis results of the raw ore by wet screening are shown in Table 4.

[0042] Table 1. Analysis results of major chemical components of the ore.

[0043] Element TFe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO <![CDATA[K2O]]> <![CDATA[Na2O]]> content / % 43.60 24.89 5.64 0.18 0.39 0.07 0.10 Element MnO <![CDATA[TiO2]]> Cl <![CDATA[Cr2O3]]> S P burn damage content / % 0.73 0.25 0.01 0.02 0.07 0.06 6.38

[0044] Table 2 Results of iron phase analysis of ore

[0045]

[0046] Table 3. Results of major mineral composition

[0047] Mineral Name Hematite Goethite Illusory hematite magnetite Pyrite, pyrrhotite content / % 21.65 18.00 14.70 7.64 0.15 Mineral Name quartz clay Iron-containing clay mica Alumina content / % 19.92 6.53 4.22 1.70 1.71 Mineral Name Pyroxene chlorite carbonates other total content / % 0.80 1.42 0.60 0.96 100.00

[0048] Table 4. Particle size distribution analysis results of raw ore after wet screening.

[0049]

[0050]

[0051] The analysis results in Tables 1-4 show that the TFe grade in the ore is 43.60%, and the main useful minerals are magnetite, pseudomorphous hematite, hematite, and limonite. Limonite is prone to mudification during grinding. The gangue minerals contain a certain amount of iron-bearing clay, which, due to its weak magnetism, easily deteriorates the recovery index of weakly magnetic minerals. The yield of the -1mm particle size of the raw ore is 55.48%, indicating that more than 50% of the ore can be directly beneficiated after screening without crushing. The yield of the -0.030mm particle size of the raw ore is 16.23%, indicating that the ore has a high mud content.

[0052] Depend on Figure 1 The diagram shown is a process flow chart illustrating the principle of the combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) of this invention, combined with... Figure 2 , Figure 3 , Figure 4 , Figure 5 As can be seen, the specific process steps and parameters used in the embodiments of the present invention are as follows:

[0053] S1 dry screening – crushing – washing – wet screening – high-pressure roller mill

[0054] The raw ore undergoes dry screening to obtain dry screen oversize and dry screen undersize products. The dry screen oversize products are fed into crushing equipment for crushing, and the crushed products are returned to the dry screening operation. The dry screen undersize products undergo washing operations to obtain washing overflow and washing return sand. The washing return sand is fed into wet screening equipment to obtain wet screen oversize and wet screen undersize products. The wet screen oversize products are returned to the wet screening operation after high-pressure roller milling. The washing overflow and wet screen undersize products are combined into the feed product, and the feed product particle size is -200 mesh 57%. The dry screening operation uses a linear vibrating screen with a screen aperture of 30mm; the crushing equipment uses a jaw crusher; the ore washing operation uses a single spiral trough ore washing machine with a spiral lifting angle of 25°, a washing concentration of 15%, a spiral speed of 16 rpm, and the overflow particle size of the washed ore is controlled to be -200 mesh, accounting for 55%; the wet screening equipment uses an arc-shaped vibrating screen with a screen aperture of 1mm, and the undersize product particle size is -200 mesh, accounting for 59%; the high-pressure roller mill operation uses a pin-type high-pressure roller mill with a roller surface linear velocity of 0.6m / s and a hydraulic pressure of 9MPa.

[0055] S2 Weak Magnetic Field - Strong Magnetic Field

[0056] The selected product obtained in step S1 is fed into a weak magnetic-strong magnetic separation process. The weak magnetic separation process includes weak magnetic roughing and weak magnetic cleaning, while the strong magnetic separation process includes strong magnetic roughing and strong magnetic scavenging. This yields weak magnetic iron concentrate, strong magnetic roughing concentrate, and strong magnetic scavenging concentrate, respectively. The strong magnetic roughing concentrate and strong magnetic scavenging concentrate are combined into a strong magnetic composite concentrate, and the strong magnetic scavenging tailings are discharged. The magnetic field strength of the weak magnetic roughing process is 278.66 kA / m, and the magnetic field strength of the weak magnetic cleaning process is 159.24 kA / m. Both the strong magnetic roughing and strong magnetic scavenging processes utilize a Slon vertical ring pulsating high gradient strong magnetic separator with magnetic field strengths of 796.18 kA / m and 955.41 kA / m, respectively.

[0057] S3 Cyclone Classification - Sluice Reselection

[0058] The high-intensity magnetic separation concentrate obtained in step S2 is fed into a hydrocyclone classifier to obtain hydrocyclone overflow and hydrocyclone underflow. The hydrocyclone underflow is fed into a sluice gravity separation process, which includes sluice gravity roughing and sluice gravity cleaning to obtain spiral sluice gravity concentrate. Spiral sluice roughing tailings and spiral sluice gravity cleaning tailings are discharged and combined into sluice gravity tailings. The hydrocyclone classifier uses a small cone angle hydrocyclone with an 8° cone angle and a feed pressure of 0.06 MPa. The overflow particle size of the hydrocyclone is controlled to be -325 mesh (90%). The feed concentration for the sluice gravity roughing is controlled at 25%, and the feed concentration for the sluice gravity cleaning is controlled at 30%.

[0059] S4 pre-classification – grinding – high-intensity magnetic separation

[0060] The tailings from the gravity separation sluice discharged in step S3 are fed into the pre-classification operation to obtain pre-classification overflow and pre-classification return sand. The pre-classification return sand is fed into the grinding equipment for grinding, and the grinding product is returned to the classification operation. The pre-classification overflow is fed into the high-intensity magnetic roughing operation to obtain high-intensity magnetic roughing concentrate, and the high-intensity magnetic roughing tailings are discharged. The pre-classification operation uses a high-frequency vibrating fine screen, and the undersize product / overflow particle size is controlled to be -200 mesh, accounting for 92%. The grinding equipment uses a vertical stirred mill with a grinding concentration of 50%. The high-intensity magnetic roughing operation uses a Slon vertical ring pulsating high-gradient magnetic separator, and the magnetic field strength is controlled to be 796.18 kA / m.

[0061] S5 Concentration - Reverse Flotation

[0062] The strong magnetic roughing concentrate obtained in step S4 and the pre-classified overflow are combined and fed into the thickening operation to obtain the thickening underflow. The concentration of the thickening underflow is controlled at 30%, and the particle size is -325 mesh 85%. The thickening underflow is fed into the reverse flotation operation to obtain reverse flotation concentrate and reverse flotation tailings. The reverse flotation concentrate, the weak magnetic iron concentrate obtained in step S2, and the spiral sluice concentrator 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 cleaning operation. The reagent dosage for each operation is calculated based on the dry ore feed rate of the reverse flotation operation:

[0063] Reverse flotation roughing: 800 g / t of sodium hydroxide as a pH adjuster, 20 g / t of sodium hexametaphosphate as a dispersant, 300 g / t of starch as an inhibitor, and 700 g / t of collector MX; Reverse flotation cleaning: 300 g / t of collector MX; The collector MX is a mixture of etheramine, ether diamine, and quaternary ammonium salt in a molar ratio of 1.5:2:2.5.

[0064] After processing with the above-mentioned process, the weathered crust-type magnetobrown mixed iron ore can yield magnetic iron concentrate with a yield of 19.80% and an iron grade of 63.61%, gravity iron concentrate with a yield of 23.33% and an iron grade of 62.15%, and flotation iron concentrate with a yield of 10.94% and an iron grade of 60.84%. Combining these three yields yields a comprehensive iron concentrate with a total yield of 54.07%, an iron grade of 62.42%, and an iron recovery rate of 77.42%.

[0065] Experimental studies show that the iron grade in the final total tailings discharged in the embodiments of the present invention is 21.44%, which is still relatively high. However, current beneficiation methods cannot recover the lost iron from the tailings to obtain high-grade iron concentrate (e.g., TFe ≥ 56.0%), and the beneficiation cost is very high. However, the main components of the final total tailings are quartz, clay, iron-bearing clay, and lost iron minerals, which are high-quality raw materials for iron-containing silicate cement and can be sold to iron-containing silicate cement plants for use as iron corrective agents.

[0066] Comparative Example: Dodecylamine was used instead of MX as the collector, and the reverse flotation process was the same as other reagents. The dosage of dodecylamine as the collector in the roughing stage was 800 g / t, and the dosage in the cleaning stage was 400 g / t. Reverse flotation yielded a flotation iron concentrate with a yield of 9.28% and an iron grade of 60.74%. The combined iron concentrate yield after combining the flotation iron concentrate with the magnetic and gravity concentrates was 52.41%, with an iron grade of 62.45% and an iron recovery rate of 75.08%.

[0067] In other words, this invention uses MX as a collector, and under the condition that the overall iron concentrate grade is basically the same, the iron recovery rate is increased by 2.34 percentage points.

[0068] The above descriptions are embodiments of the present invention. However, the above examples are only for the purpose of helping to understand the method and core ideas of the present invention, and are not equivalent to the specific embodiments described above. For those skilled in the art, any improvements, modifications, or variations made to the present invention, as well as the combination of the above technical features in an appropriate manner, such improvements, modifications, variations, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A combined beneficiation process for weathered crust-type high-muddy mixed iron ore containing magnetite, hematite, and limonite, used to process mixed iron ore with a high muddy content and coexistence of magnetite, hematite, and limonite minerals, containing 35%–45% iron grade and ≥15.0% -0.030mm particle size, characterized in that… The following steps are adopted: S1 dry screening – crushing – washing – wet screening – high-pressure roller mill The raw ore undergoes dry screening to obtain dry screen oversize and dry screen undersize products. The dry screen oversize products are fed into crushing equipment for crushing, and the crushed products are returned to the dry screening operation. The dry screen undersize products undergo washing to obtain washing overflow and washing return sand. The washing return sand is fed into wet screening equipment to obtain wet screen oversize and wet screen undersize products. The wet screen oversize products are returned to the wet screening operation after high-pressure roller milling. The washing overflow and wet screen undersize products are combined into the beneficiated products. S2 Weak Magnetic Field - Strong Magnetic Field The selected product obtained in step S1 is fed into a weak magnetic-strong magnetic process. The weak magnetic process includes weak magnetic roughing and weak magnetic cleaning, and the strong magnetic process includes strong magnetic roughing and strong magnetic scavenging. Weak magnetic iron concentrate, strong magnetic roughing concentrate, and strong magnetic scavenging concentrate are obtained respectively. The strong magnetic roughing concentrate and strong magnetic scavenging concentrate are combined into a strong magnetic comprehensive concentrate, and the strong magnetic scavenging tailings are discharged. S3 Cyclone Classification - Sluice Reselection The strong magnetic separation concentrate obtained in step S2 is fed into a cyclone classification operation to obtain cyclone classification overflow and cyclone classification underflow. The cyclone classification underflow is fed into a sluice gravity separation operation, which includes sluice gravity roughing and sluice gravity cleaning to obtain spiral sluice clean concentrate. Spiral sluice roughing tailings and spiral sluice cleaning tailings are discharged and combined into sluice gravity tailings. S4 pre-classification – grinding – high-intensity magnetic separation The gravity separation tailings discharged from step S3 are fed into the pre-classification operation to obtain pre-classification overflow and pre-classification return sand. The pre-classification return sand is fed into the grinding equipment for grinding, and the grinding product is returned to the classification operation. The pre-classified overflow is fed into the high-intensity magnetic roughing operation to obtain high-intensity magnetic roughing concentrate, and the high-intensity magnetic roughing tailings are discharged. S5 Concentration - Reverse Flotation The strong magnetic roughing concentrate obtained in step S4 and the pre-classified overflow are combined and fed into the thickening operation to obtain the thickening underflow. The thickening underflow is fed into the reverse flotation operation to obtain reverse flotation concentrate and reverse flotation tailings. The reverse flotation concentrate, the weak magnetic iron concentrate obtained in step S2, and the spiral sluice concentrator concentrate obtained in step S3 are combined to form the final iron concentrate. The reverse flotation tailings, the strong magnetic scavenging tailings discharged from step S2, and the strong magnetic roughing tailings discharged from step S4 are combined to form the final total tailings. The final total tailings are used as raw material for iron corrective agents in iron-containing silicate cement plants. The reverse flotation operation adopts one roughing and one cleaning operation. The reagent dosage for each operation is calculated based on the dry ore feed rate of the reverse flotation operation: Reverse flotation roughing: Sodium hydroxide pH adjuster dosage 500g / t~1000g / t, sodium hexametaphosphate dispersant dosage 10g / t~30g / t, starch inhibitor dosage 200g / t~400g / t, collector MX dosage 500g / t~1000g / t; Reverse flotation cleaning: Collector MX dosage 200g / t~600g / t; The collector MX is a mixture of etheramine, ether diamine and quaternary ammonium salt, with a molar ratio of 1:(1.2~2.0):(1.5~2.5).

2. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 1, characterized in that: In step S1, the dry screening operation uses a linear vibrating screen with a screen aperture size of 20mm to 40mm; the crushing equipment uses a jaw crusher; the ore washing operation uses a single spiral trough ore washing machine with a spiral lifting angle of 20° to 30°, a ore washing concentration of 10% to 20%, a spiral speed of 12 rpm to 20 rpm, and the overflow particle size of the ore washing is controlled to be -200 mesh, accounting for 50% to 60%.

3. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 2, characterized in that: In step S1, the wet screening equipment uses an arc-shaped vibrating screen with a screen aperture size of 1mm to 2mm, and the particle size of the undersize product is -200 mesh, accounting for 50% to 60%; the high-pressure roller mill operation uses a pin-type high-pressure roller mill, with a roller surface linear velocity of 0.5m / s to 0.8m / s and a hydraulic pressure of 8MPa to 10MPa.

4. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 1, characterized in that: In step S2, the magnetic field strength of the weak magnetic coarse separation operation is 199.04 kA / m to 318.47 kA / m, and the magnetic field strength of the weak magnetic fine separation operation is 95.54 kA / m to 159.24 kA / m.

5. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 4, characterized in that: In step S2, both the strong magnetic coarse separation and the strong magnetic sweep separation adopt the Slon vertical ring pulsating high gradient strong magnetic separator, with magnetic field strengths of 636.94kA / m~796.18kA / m and 955.41kA / m~1194.27kA / m, respectively.

6. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 1, characterized in that: In step S3, the hydrocyclone classification operation uses a small cone angle hydrocyclone with a cone angle of 5° to 10° and a feed pressure of 0.05 MPa to 0.10 MPa; the overflow particle size of the hydrocyclone classification is controlled to be -325 mesh, accounting for 85% to 95%.

7. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 6, characterized in that: In step S3, the feed concentration for the coarse gravity separation in the sluice box is controlled at 20% to 30%, and the feed concentration for the fine gravity separation in the sluice box is controlled at 25% to 35%.

8. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 1, characterized in that: In step S4, the pre-grading operation uses a high-frequency vibrating fine screen / hydrocyclone, and the undersize / 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 636.94 kA / m to 796.18 kA / m.

9. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore (magnetic, red, and brown varieties) as described in claim 1, characterized in that: In step S5, the concentration of the underflow during the concentration operation is controlled at 25% to 35%.

10. The combined beneficiation process for weathered crust-type high-mud-content mixed iron ore of magnetic, red, and brown varieties as described in claim 3, characterized in that: In step S2, the magnetic field strength for the weak magnetic coarse separation operation is 199.04 kA / m to 318.47 kA / m, and the magnetic field strength for the weak magnetic fine separation operation is 95.54 kA / m to 159.24 kA / m; both the strong magnetic coarse separation and the strong magnetic sweeping separation use a Slon vertical ring pulsating high gradient strong magnetic separator, with magnetic field strengths of 636.94 kA / m to 796.18 kA / m and 955.41 kA / m to 1194.27 kA / m, respectively. In step S3, the hydrocyclone classification operation uses a small cone angle hydrocyclone with a cone angle of 5° to 10° and a feed pressure of 0.05 MPa to 0.10 MPa; the overflow particle size of the hydrocyclone classification is controlled to be -325 mesh, accounting for 85% to 95%; in step S3, the feed concentration of the coarse gravity separation in the sluice box is controlled to be 20% to 30%, and the feed concentration of the fine gravity separation in the sluice box 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 / 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 636.94 kA / m to 796.18 kA / m. In step S5, the concentration of the underflow in the concentration operation is controlled at 25% to 35%, and the particle size of the underflow in the concentration operation is controlled at 80% to 90% of -325 mesh.

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