Iron tailings pre-throw tailings-weak magnetic strong magnetic-grinding gravity separation-reverse flotation process

Abstract

This invention relates to a pre-disposal of iron tailings – weak magnetic and strong magnetic separation – grinding and gravity separation – reverse flotation process, including a three-stage reverse flotation operation of roughing, cleaning, and scavenging for gravity separation tailings. The process is characterized by further including hydrocyclone classification and desliming with weak and strong magnetic separation, closed-circuit regrinding and classification of the strong magnetic concentrate, and gravity separation using a vibrating cone concentrator. Modified sweet potato starch is added during hydrocyclone classification and desliming and closed-circuit regrinding to selectively flocculate fine-grained iron minerals. The advantages of this invention are: for fine-grained iron tailings feed with a particle size of -38μm of 40%-60% and a grade of 20%-25%, the process of this invention can achieve a final concentrate grade of over 63%, a final concentrate recovery rate of over 70%, and a final tailings grade of less than 12%.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and comprehensive resource utilization technology, specifically relating to a process for iron tailings pre-tailings disposal-weak magnetic and strong magnetic fields-grinding gravity separation-reverse flotation. Background Technology

[0002] my country's iron ore resources are relatively poor, abundant but not plentiful. Currently, the net increase in iron tailings stockpiles is approximately 600 million tons annually, with a cumulative stockpile estimated at 8 billion tons. Therefore, conducting research on the comprehensive recycling and utilization of iron tailings resources and improving their utilization rate is of great significance for strengthening my country's iron ore resource security. The main gangue minerals in the iron tailings from Anshan-type iron mines include quartz, chlorite, and amphibole. The key issues affecting their comprehensive utilization are the fine particle size of the target minerals and the severe mudification of the gangue minerals. Currently, common iron tailings recovery processes include desliming, de-reagent pretreatment, and spiral sluice gravity separation (see...). Figure 1 This process suffers from the problem that the spiral chute of the gravity separation equipment separates large particles, making it difficult to effectively recover and utilize fine-grained iron tailings waste resources of -38μm. The concentrate grade of this process can reach about 50%, but the recovery rate is only about 30%. Another approach involves using a strong magnetic field-grinding-reverse flotation process (see...). Figure 2 This process also suffers from drawbacks: easily mud-forming minerals, after grinding and mudding to a -38μm particle size, enter the reverse flotation process, worsening the flotation environment, consuming large amounts of reagents, and resulting in poor separation of gangue and target minerals. While the concentrate grade can reach approximately 60%, the recovery rate is only around 40%, leading to significant waste of iron tailings resources. To address the problems of complex processes and poor separation of fine-grained minerals in existing iron tailings recovery technologies, developing a new iron tailings recovery process to enhance the recovery of fine-grained minerals is of significant practical importance.

[0003] Furthermore, traditional organic polymeric flocculants typically utilize natural polysaccharide starch-based agents extracted from grain crops such as corn, wheat, potatoes, and cassava. However, these natural starch-based agents have a simple structure, lack characteristic functional groups, and exhibit poor selectivity and swelling properties. This necessitates the addition of large quantities of agents during use, resulting in significant waste of grain crops, which is detrimental to my country's food supply security and national economic development. Simultaneously, the limited structural suitability of starch restricts its effectiveness in production. Currently, modification methods are often used to specifically improve starch performance, such as using bio-enzymatic modification, which effectively enhances starch's adsorption capacity. Additionally, to achieve the degradation of microplastics, organic monomers are grafted onto starch in redox systems to obtain graft copolymers. Therefore, to improve the flotation recovery efficiency of fine-grained minerals, modifying starch to enhance selective flocculation and increase apparent particle size is of significant practical importance for improving the recovery of fine-grained minerals. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides a process for iron tailings pre-disposal, weak and strong magnetic separation, grinding and gravity separation, and reverse flotation. By applying a novel gravity separation equipment, a suspended conical concentrator, to reduce the feed particle size and using novel reagents to modify sweet potato starch to improve the selective flocculation effect of fine-grained minerals, this process can effectively improve the iron concentrate grade and recovery rate of fine-grained tailings beneficiation, achieving the goal of fully recovering and utilizing tailings resources from Anshan-type iron mines.

[0005] The objective of this invention is achieved through the following technical solution: The present invention discloses a process for iron tailings pre-disposal-weak magnetic and strong magnetic separation-grinding gravity separation-reverse flotation, wherein the iron tailings are iron tailings from Anshan-type iron mines, characterized by comprising the following steps: Step 1: Feed iron tailings slurry with a particle size of -38 μm of 40%-60% and a grade of 20%-25% into a hydrocyclone for classification and desliming, obtaining hydrocyclone underflow and overflow products. The hydrocyclone underflow product is enriched flocculated fine-grained iron concentrate, and the hydrocyclone overflow product is argillaceous gangue tailings, which are discarded. The obtained underflow product has a particle size of -74 μm to +38 μm of 60%-80% and a grade of 30%-32%. The obtained overflow product has a -38 μm content of 80%-90% and an iron grade of 8%-15%. Step 2: The obtained flocculated fine iron concentrate is fed into a weak magnetic separator and a strong magnetic separator in sequence to obtain weak magnetic concentrate, strong magnetic concentrate and strong magnetic tailings; the weak magnetic concentrate is used as magnetic concentrate, the strong magnetic tailings are discarded, and the strong magnetic concentrate is fed into a closed-circuit regrinding and classification operation to obtain regrinding and classification overflow products. Step 3: Feed the regrinding and classification overflow product into a suspended cone concentrator for gravity separation to obtain gravity concentrate and gravity tailings. After the gravity tailings are concentrated by a thickener, thickener underflow and thickener overflow are obtained. The thickener overflow is used as recycled water, and the thickener underflow is used as feed for reverse flotation. Step 4: Feed the underflow from the thickener into a reverse flotation process involving one rougher, one cleaner, and three scavengers to obtain flotation concentrate and flotation tailings. Discard the flotation tailings. Step 5: Combine the weak magnetic concentrate, gravity concentrate, and flotation concentrate into a final concentrate with a grade of 63% or higher and a recovery rate of 70% or higher; combine the mudstone tailings, strong magnetic tailings, and flotation tailings into a final tailings with a grade of less than 12%.

[0006] In step 1, modified sweet potato starch is added to the hydrocyclone to selectively flocculate fine iron minerals; in step 2, modified sweet potato starch is also added during the closed-circuit regrinding and grading process.

[0007] The modified sweet potato starch synthesis method used in step 1 is as follows: (1) Alkalization reaction of sweet potato starch After the sweet potato starch is heated and dissolved, sodium hydroxide is added under stirring to carry out an alkalization reaction to obtain alkalized sweet potato starch; wherein, the mass ratio of sodium hydroxide to sweet potato starch is (1-3):1, the alkalization reaction temperature is 40-60℃, and the time is 30-60 min. (2) Etherification and neutralization reactions: Chloroacetic acid is added to alkalized sweet potato starch at a mass ratio of (0.5-3.5):1 to carry out an etherification reaction, thereby obtaining etherified sweet potato starch. Glacial acetic acid is then added to neutralize the mixture to obtain a neutralized sweet potato starch emulsion. The etherification reaction is carried out at a temperature of 50-60℃ for 60-120 min. (3) The neutralized sweet potato starch emulsion was washed, filtered and dried to obtain modified sweet potato starch; (4) Free radical polymerization reaction: After the modified sweet potato starch is dissolved in water, sodium bisulfite and ammonium persulfate are added in a mass ratio of 2:1, with the total mass of sodium bisulfite and ammonium persulfate being 0.1%-0.5% of the mass of sweet potato starch. The mixture is then reacted with sodium bisulfite and ammonium persulfate for 30-60 min. Acrylic acid monomer is then added to carry out a free radical polymerization reaction, with the mass ratio of acrylic acid monomer to modified sweet potato starch being 0.5-1.0. The reaction time is 120-240 min, and the reaction temperature is 40-60℃, resulting in a modified sweet potato starch-acrylic acid polymer with a degree of substitution of 1.5-2.2. (5) After precipitation, washing and low-temperature drying, polymers are synthesized into high molecular weight pharmaceuticals.

[0008] The aforementioned polymeric agent combines the structure of sweet potato starch containing polycarboxylic acid polar functional groups with the characteristic structure of linear long-chain polyacrylic acid, exhibiting good selectivity and agglomeration properties for fine-grained iron minerals. The selectiveness of sweet potato starch is enhanced by introducing the characteristic structure of linear long-chain polyacrylic acid, while its polycarboxylic acid polar functional groups maintain its adsorption capacity for iron ore.

[0009] In step 2, the magnetic field strength of the weak magnetic generator is above 1000 Oe; the magnetic field strength of the strong magnetic generator is above 10000 Oe; the grade of the weak magnetic concentrate is above 56%; the grade of the strong magnetic tailings is below 8%; and the content of the -38μm particle size in the regrinding and classification overflow product is 70%-95%.

[0010] In step 3, the grade of the gravity concentrate is 52% or higher; In step 4, the grade of the flotation concentrate is above 65%, and the grade of the flotation tailings is below 15%.

[0011] This invention incorporates modified sweet potato starch in both the cyclone desliming and grinding stages to flocculate the target minerals, thereby increasing their apparent particle size for easier subsequent separation and recovery. This process also ensures the complete removal of muddy minerals from the feed. Furthermore, this invention innovatively applies a suspended vibrating cone concentrator to the comprehensive recovery process of fine-grained iron tailings, avoiding the adverse effects of further mudding during grinding on subsequent recovery processes. The application of the suspended vibrating cone concentrator also demonstrates good performance in separating fine-grained minerals, ultimately reducing production costs and achieving efficient recovery and utilization of iron tailings resources.

[0012] Key points of the invention The key technical point of this invention is: (1) Targeted enhancement of fine-grained minerals in sweet potato starch modification and innovative application in cyclone desliming and grinding processes; (2) Optimize the beneficiation process and adopt new gravity separation equipment to reduce the feed particle size and enhance the recovery of fine minerals; solve the problems of large-scale waste of existing tailings resources and difficulty in recovering fine iron tailings, and achieve efficient recovery of iron tailings resources.

[0013] Compared with the prior art, the advantages of the present invention are: This invention addresses the technical challenges of severe mud formation and poor recovery of fine-grained minerals in existing comprehensive recovery processes for -38μm fine-grained iron tailings. It integrates a gravity separation device (a suspended conical concentrator) with a hydrocyclone and novel reagent-modified sweet potato starch into the comprehensive recovery and separation process for iron tailings. The proposed process is a pre-tailings disposal-weak and strong magnetic separation-grinding gravity separation-reverse flotation process, which effectively improves the grade and recovery efficiency of iron concentrate.

[0014] The advantages of this process are: (1) The ratio of amylose to amylopectin in sweet potato starch is approximately 2:8. Since amylopectin is easily soluble in cold water, it can be added to different desliming processes without heating the slurry, thus saving production costs. (2) Through multi-stage desliming operations, the mudification of gangue minerals at different stages can be effectively avoided, which will lead to the deterioration of subsequent beneficiation operations. The reduction of the processing particle size and the improvement of the processing efficiency of the gravity separation equipment can effectively reduce the reverse flotation processing volume while reducing the beneficiation production cost.

[0015] (3) The selective flocculation of the target mineral by the reagent is achieved in stages, thereby improving the separation and recovery effect. The final concentrate grade reaches more than 63%, the final concentrate recovery rate reaches more than 70%, and the final tailings grade is below 12%. Attached Figure Description

[0016] Figure 1This is the original flow chart of the desliming, de-chemical pretreatment, and spiral chute gravity separation process.

[0017] Figure 2 This is the original flow chart of the strong magnetic-grinding-reverse flotation process.

[0018] Figure 3 This is a flow chart of the mineral processing technology of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1 like Figure 3 The present invention illustrates a mineral processing flow. In this embodiment, the ore composition comprises quartz, chlorite, amphibole, pseudomorphous hematite, hematite, specular hematite, magnetite, limonite, and goethite. The iron grade of the feed ore is 20.17%, the proportion of particles smaller than 0.038 mm in the feed is 40%, and the degree of liberation of individual iron minerals is 38%.

[0021] The process employs "cyclone desliming, weak magnetic-strong magnetic separation, grinding, classification, gravity separation, and reverse flotation". The cyclone desliming equipment has a classification particle size of 10 μm, and the modified sweet potato starch dosage is 200 g / t. The weak magnetic field strength is 2000 Oe, and the strong magnetic separation field strength is 12000 Oe. The grinding concentration is 70%, the modified sweet potato starch dosage is 100 g / t, and the gravity separation feed particle size of -0.038 mm accounts for 75%. The suspension concentrator operates with a rotation cycle of 240 s and a vibration frequency of 8 Hz. The reverse flotation feed particle size of -0.038 mm accounts for 85%, and the reverse flotation reagent regimen is as follows: roughing with 1200 g / t starch, 1000 g / t calcium oxide, and 900 g / t collector, and finishing with 400 g / t collector. The modified sweet potato starch preparation scheme is as follows: sodium hydroxide:sweet potato starch ratio is 2:1; the alkalization reaction temperature is 40℃ and the time is 30 min; chloroacetic acid is added to the alkalized sweet potato starch at a mass ratio of chloroacetic acid:alkalized sweet potato starch of 1:1 to carry out an etherification reaction, obtaining etherified sweet potato starch; glacial acetic acid is added to neutralize to obtain a neutralized sweet potato starch emulsion; wherein the etherification reaction temperature is 50℃ and the time is 60 min. After neutralization, the sweet potato starch emulsion was washed, filtered, and dried to obtain modified sweet potato starch. The modified sweet potato starch was dissolved in water, and sodium bisulfite was added to ammonium persulfate at a mass ratio of 2:1, with the total mass of sodium bisulfite and ammonium persulfate being 0.1% of the sweet potato starch mass. The mixture was then reacted for 30 minutes, followed by the addition of acrylic acid monomers for free radical polymerization at a mass ratio of acrylic acid monomers to modified sweet potato starch of 0.5, a reaction time of 120 minutes, and a reaction temperature of 40℃, yielding a modified sweet potato starch-acrylic acid polymer with a degree of substitution of 2. The iron concentrate results obtained from the above process are shown in the table below. refer to Figure 1 This invention describes a comprehensive iron tailings recycling and beneficiation process according to a specific embodiment of the present invention.

[0022] Example 2 like Figure 3 The present invention illustrates a mineral processing flow. In this embodiment, the ore composition comprises quartz, chlorite, amphibole, pseudomorphous hematite, hematite, specular hematite, magnetite, limonite, and goethite. The iron grade of the feed ore is 22.73%, the proportion of the feed particle size of -0.038mm is 45%, and the degree of liberation of the iron minerals is 40%.

[0023] The process employs "cyclone desliming, weak magnetic-strong magnetic separation, grinding, classification, gravity separation, and reverse flotation". The cyclone desliming equipment has a classification particle size of 10 μm, and the modified sweet potato starch dosage is 150 g / t. The weak magnetic field strength is 1500 Oe, and the strong magnetic separation field strength is 13000 Oe. The grinding concentration is 70%, the modified sweet potato starch dosage is 100 g / t, and the gravity separation feed particle size of -0.038 mm accounts for 70%. The operating parameters of the suspension concentrator are a rotation cycle of 240 s and a vibration frequency of 8 Hz. The reverse flotation feed particle size of -0.038 mm accounts for 80%, and the reverse flotation reagent regimen is as follows: roughing with 1400 g / t starch, 1100 g / t calcium oxide, and 800 g / t collector, and finishing with 300 g / t collector. The modified sweet potato starch preparation scheme is as follows: sodium hydroxide:sweet potato starch ratio is 2:1, alkalization reaction temperature is 40℃, and time is 30 min; chloroacetic acid is added to the alkalized sweet potato starch at a mass ratio of chloroacetic acid:alkalized sweet potato starch of 1:1 for etherification reaction to obtain etherified sweet potato starch; glacial acetic acid is added to neutralize to obtain a neutralized sweet potato starch emulsion; the etherification reaction temperature is 50℃, and time is 60 min; the neutralized sweet potato starch emulsion is washed, filtered, and dried to obtain modified sweet potato starch; after the modified sweet potato starch is dissolved in water, sodium bisulfite:ammonium persulfate ratio is 2:1, and the total mass of sodium bisulfite and ammonium persulfate is 0.1% of the mass of sweet potato starch; then sodium bisulfite and ammonium persulfate are added and reacted for 30 min; then acrylic acid monomer is added for free radical polymerization reaction at a mass ratio of acrylic acid monomer:modified sweet potato starch = 0.5, and reaction time is 120 minutes. The reaction temperature was 40℃, and a modified sweet potato starch-acrylic acid polymer with a degree of substitution of 2 was obtained. The iron concentrate results obtained from the above process are shown in the table below: refer to Figure 1 This invention describes a comprehensive iron tailings recycling and beneficiation process according to a specific embodiment of the present invention.

[0024] Example 3 like Figure 2 The present invention illustrates a mineral processing flow. In this embodiment, the ore composition consists of quartz, chlorite, amphibole, pseudomorphous hematite, hematite, specular hematite, magnetite, limonite, and goethite. The iron grade of the feed ore is 23.94%, the proportion of particles smaller than 0.038 mm in the feed is 50%, and the degree of liberation of the iron minerals is 42%.

[0025] The process employs "cyclone desliming, weak magnetic-strong magnetic separation, grinding, classification, gravity separation, and reverse flotation". The cyclone desliming equipment has a classification particle size of 10 μm, and the modified sweet potato starch dosage is 270 g / t. The weak magnetic field strength is 1000 Oe, and the strong magnetic separation field strength is 10000 Oe. The grinding concentration is 70%, the modified sweet potato starch dosage is 200 g / t, and the gravity separation feed particle size of -0.038 mm accounts for 75%. The suspension concentrator operates with a rotation cycle of 240 s and a vibration frequency of 8 Hz. The reverse flotation feed particle size of -0.038 mm accounts for 95%, and the reverse flotation reagent regimen is as follows: rougher starch dosage 1300 g / t, calcium oxide dosage 1200 g / t, collector dosage 1000 g / t, and cleaner collector dosage 500 g / t. The modified sweet potato starch preparation scheme is as follows: sodium hydroxide:sweet potato starch ratio is 1:1, alkalization reaction temperature is 40℃, and time is 60 min; chloroacetic acid is added to the alkalized sweet potato starch at a mass ratio of chloroacetic acid:alkalized sweet potato starch of 1:1 for etherification reaction to obtain etherified sweet potato starch; glacial acetic acid is added to neutralize to obtain a neutralized sweet potato starch emulsion; the etherification reaction temperature is 50℃, and time is 60 min; the neutralized sweet potato starch emulsion is washed, filtered, and dried to obtain modified sweet potato starch; after the modified sweet potato starch is dissolved in water, sodium bisulfite:ammonium persulfate ratio is 2:1, and the total mass of sodium bisulfite and ammonium persulfate is 0.1% of the mass of sweet potato starch; then sodium bisulfite and ammonium persulfate are added and reacted for 30 min; then acrylic acid monomer is added for free radical polymerization reaction at a mass ratio of acrylic acid monomer:modified sweet potato starch = 1, and reaction time is 120 min. The reaction temperature was 50℃, and a modified sweet potato starch-acrylic acid polymer with a degree of substitution of 2.2 was obtained. The iron concentrate results obtained from the above process are shown in the table below: refer to Figure 1 This invention describes a comprehensive iron tailings recycling and beneficiation process according to a specific embodiment of the present invention.

[0026]

Claims

1. A process for pre-disposal of iron tailings – weak magnetic and strong magnetic separation – grinding and gravity separation – reverse flotation, wherein the iron tailings are iron tailings from Anshan-type iron mines, characterized in that, Includes the following steps: Step 1: Feed iron tailings slurry with a particle size of -38μm of 40%-60% and a grade of 20%-25% into a hydrocyclone for classification and desliming, obtaining hydrocyclone underflow product and hydrocyclone overflow product. The hydrocyclone underflow product is enriched flocculated fine-grained iron concentrate, and the hydrocyclone overflow product is argillaceous gangue tailings, which are discarded. The obtained underflow product has a particle size of -74μm to +38μm of 60%-80% and a grade of 30%-32%. The obtained overflow product has a -38μm content of 80%-90% and an iron grade of 8%-15%. Modified sweet potato starch is added to the hydrocyclone to selectively flocculate the fine-grained iron minerals. Step 2: The obtained flocculated fine-grained iron concentrate is fed into a weak magnetic separator and a strong magnetic separator to obtain weak magnetic concentrate, strong magnetic concentrate, and strong magnetic tailings. The weak magnetic concentrate is used as the magnetic concentrate, the strong magnetic tailings are discarded, and the strong magnetic concentrate is fed into a closed-circuit regrinding and classification operation to obtain the regrinding and classification overflow product. Modified sweet potato starch is also added in the closed-circuit regrinding and classification operation. The magnetic field strength of the weak magnetic separator is above 1000 Oe. The magnetic field strength of the strong magnetic separator is above 10000 Oe. The grade of the weak magnetic concentrate is above 56%. The grade of the strong magnetic tailings is below 8%. The content of -38μm particles in the regrinding and classification overflow product is 70%-95%. Step 3: Feed the regrinding and classification overflow product into a vibrating cone concentrator for gravity separation to obtain gravity concentrate and gravity tailings. After the gravity tailings are concentrated in a thickener, thickener underflow and thickener overflow are obtained. The thickener overflow is used as recycled water, and the thickener underflow is used as feed for reverse flotation. The grade of the gravity concentrate is above 52%. Step 4: Feed the underflow from the thickener into a reverse flotation process involving one rougher, one cleaner, and three scavengers to obtain flotation concentrate and flotation tailings. Discard the flotation tailings. Step 5: Combine the weak magnetic concentrate, gravity concentrate, and flotation concentrate into a final concentrate with a grade of 63% or higher and a recovery rate of 70% or higher. Combine the mudstone tailings, strong magnetic tailings, and flotation tailings into a final tailings with a grade of 12% or lower. The grade of the flotation concentrate is 65% or higher, and the grade of the flotation tailings is 15% or lower.

2. The iron tailings pre-disposal-weak magnetic field-strong magnetic field-grinding gravity separation-reverse flotation process according to claim 1, characterized in that, In step 1, the modified sweet potato starch synthesis process is divided into the following steps: (1) Alkalization reaction of sweet potato starch: After the sweet potato starch is heated and dissolved, sodium hydroxide is added under stirring to carry out the alkalization reaction and obtain alkalized sweet potato starch; wherein, the mass ratio of sodium hydroxide to sweet potato starch is (1-3):1, the alkalization reaction temperature is 40-60℃, and the time is 30-60 min; (2) Etherification and neutralization reaction: Chloroacetic acid is added to the alkalized sweet potato starch, and the mass ratio of chloroacetic acid to alkalized sweet potato starch is (0.5-3.5):1, to carry out the etherification reaction and obtain etherified sweet potato starch. Glacial acetic acid is added to neutralize to neutral and obtain neutralized sweet potato starch emulsion; wherein, the etherification reaction temperature is 50-60℃, and the time is 60-120 min; (3) The neutralized sweet potato starch emulsion is washed, filtered, and dried to obtain modified sweet potato starch; (4) Free radical polymerization reaction.

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