Combined high intensity magnetic separation-reverse flotation method for high calcium-magnesium fine particle grade vanadium-titanium magnetite

Abstract

The application discloses a combined strong magnetic-reverse flotation tailing discarding method for high calcium-magnesium fine particle grade vanadium-titanium magnetite, and belongs to the technical field of mineral processing. The application provides a combined strong magnetic-reverse flotation tailing discarding method for solving the problems of difficulty in deep removal of calcium-magnesium impurities, shear thickening, deterioration of mud cover, and calcium salt precipitation failure of high calcium-magnesium fine particle grade vanadium-titanium magnetite, and the method comprises the following steps: one-stage grinding-magnetic separation roughing, two-stage fine grinding-strong magnetic pre-concentration, and reverse flotation for removing calcium and magnesium: the concentration of the reverse flotation pulp is controlled to be 28wt%-35wt%, sodium hydroxide, causticizing starch, calcium chloride, sodium hexametaphosphate, and a composite collector of sodium oleate and MES are added in sequence, reverse flotation is carried out, and high-grade low-calcium-magnesium iron concentrate is obtained. According to the application, the content of CaO+MgO impurities in the iron concentrate is reduced to below 1.42wt%, the grade of total iron is above 59.50%, and the iron recovery rate is above 75.80%.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a combined strong magnetic-reverse flotation tailings removal method for high-calcium magnesium fine-grained vanadium-titanium magnetite. Background Technology

[0002] Vanadium-titanium magnetite is a typical polymetallic symbiotic iron ore resource, rich in various valuable metallic elements such as iron, vanadium, and titanium. The Panxi region and Chengde region of Hebei Province in my country possess extremely rich vanadium-titanium magnetite resources. However, with the increasing depletion of easily beneficiated ores, current mining mainly involves low-grade, fine-grained, disseminated vanadium-titanium magnetite, often accompanied by high-calcium and magnesium gangue, which is difficult to beneficiate.

[0003] In these types of ores, gangue minerals such as pyroxene and plagioclase often contain high levels of calcium and magnesium, which enhances their weak magnetic properties. In conventional weak magnetic separation processes, high-calcium and magnesium gangue minerals easily mix into the iron concentrate, resulting in persistently high SiO2 and (CaO+MgO) impurity content in the final iron concentrate (typically CaO+MgO > 3.0 wt%). This not only lowers the selling price of the iron concentrate, but the high calcium and magnesium content also easily increases slag viscosity and makes slag removal difficult during blast furnace smelting, severely impacting the normal operation and production efficiency of the blast furnace.

[0004] Furthermore, the fine-grained dispersibility necessitates grinding the ore to a minimum of -0.045mm (over 90%) to achieve monomer liberation. However, fine grinding produces severe "sludge" formation, drastically deteriorating traditional magnetic separation or single flotation performance and resulting in significant metal loss. Therefore, developing a highly efficient beneficiation process for upgrading and reducing impurities (especially calcium and magnesium impurities) in high-calcium, fine-grained vanadium-titanium magnetite concentrate has significant industrial value.

[0005] CN113560030B discloses a beneficiation method for vanadium-titanium magnetite concentrate, which is a combined magnetic separation-flotation beneficiation process for upgrading and reducing impurities in vanadium-titanium magnetite concentrate. This process involves staged grinding and staged separation, followed by multi-stage weak and strong magnetic enrichment and then flotation separation. CN105855063A discloses an anionic collector and its preparation method, which introduces an anionic surfactant, mainly sodium methyl ester sulfonate (MES), as a collector in the flotation process to improve the reagent's resistance to hard water and its room-temperature dispersion performance.

[0006] CN103495509B discloses a reverse flotation reagent for fine-grained iron ore and its application method. The reverse flotation reagent consists of a pH adjuster (sodium hydroxide), a desorbent, a depressant (caustic corn starch), an activator (calcium oxide), and a fatty acid collector. The desorbent is composed of the following raw material components by weight: 40-42 parts water glass and 4-6 parts carboxymethyl cellulose. The water glass modulus is 1-2, the carboxymethyl cellulose viscosity is 800-1200 mPa·s, and the degree of substitution is ≥0.9. In use, the raw material components in the stated weight proportions are first dissolved in water, then mixed, and water is added to prepare a desorbent solution with a mass concentration of 0.04-0.06%. The reverse flotation method involves using caustic corn starch as a depressant, calcium chloride to activate the calcium magnesium gangue, and a single fatty acid collector (such as sodium oleate) under strongly alkaline conditions (pH adjusted with NaOH) for reverse flotation.

[0007] The above method uses a single fatty acid collector (such as sodium oleate) in a strongly alkaline environment and with high calcium content (activator Ca). 2+ In this medium, sodium oleate easily forms insoluble calcium oleate, leading to a decrease in the effective collector concentration and a decline in selectivity. Although water glass and carboxymethyl cellulose are used, the problems of ore slime agglomeration, surface covering, and mechanical entrainment when the material is finely ground to an ultrafine particle size (-0.045mm accounts for more than 90wt%) are not fully resolved. This is a conventional weak magnetic coarse concentrate direct reverse flotation, without purification treatment for the fine ore slime in the pre-flotation stage, thus posing a risk of high calcium and magnesium impurities in the concentrate and low iron recovery rate. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies and provide a combined strong magnetic-reverse flotation tailings removal method for fine-grained vanadium-titanium magnetite with high calcium and magnesium content. This invention mainly solves the technical bottlenecks at the following three levels: (1) Difficulty in deep removal of calcium and magnesium impurities: Conventional reverse flotation reagents have poor selectivity and cannot effectively separate weakly magnetic gangue minerals such as calcium magnesium pyroxene and plagioclase that are closely coexisting; (2) Deterioration indicators of "shear thickening" and "mud cover" of ultrafine ore slime: The viscosity of finely ground materials increases abnormally under strong shear, and fine mud covers magnetite particles, resulting in serious non-selective entrainment; (3) Failure of calcium salting out of traditional collectors: Traditional sodium oleate collectors are prone to premature chemical precipitation (salting out) in high-calcium hard water environments, resulting in loss of activity.

[0009] To address the aforementioned technical problems, this invention provides a combined strong magnetic-reverse flotation tailings removal method for high-calcium-magnesium fine-grained vanadium-titanium magnetite. This method employs a two-stage grinding and flotation process, combining strong magnetic pre-desliming with rheology-controlled reverse flotation. Specifically, it includes the following steps:

[0010] A. First-stage grinding-weak magnetic roughing: The high-calcium magnesium fine-grained vanadium-titanium magnetite ore is ground in one stage, and the slurry after grinding is roughed under a magnetic field strength of 0.12T~0.18T to obtain a first-stage rough concentrate and weak magnetic tailings.

[0011] B. Two-stage fine grinding-strong magnetic pre-enrichment: The primary rough concentrate is subjected to two-stage fine grinding. The finely ground slurry is subjected to strong magnetic separation under a background magnetic field strength of 0.6T~0.8T and a pulsation frequency of 200Hz~300Hz to obtain strong magnetic enriched concentrate and strong magnetic tailings.

[0012] C. Reverse flotation to remove calcium and magnesium: The strongly magnetically enriched concentrate is subjected to reverse flotation to adjust the slurry concentration to 28%~35wt%. Sodium hydroxide is added in sequence: first, iron mineral inhibitor causticized starch is added; then, calcium chloride, calcium and magnesium gangue activator is added; then, sodium hexametaphosphate, an inorganic dispersant is added; finally, a composite anionic collector is added. After the reagents are added, a closed-circuit reverse flotation is carried out with one roughing, one cleaning and two scavenging processes to obtain high-grade low-calcium magnesium iron concentrate and calcium-magnesium rich tailings. In step C, the composite anionic collector is prepared by using sodium oleate and sodium methyl cocoate sulfonate at a mass ratio of 3.5~4.5:1.

[0013] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step A, the fineness of the first grinding stage is controlled to be -0.074mm, accounting for 60%~70wt%.

[0014] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, in step A, the chemical composition of the high-calcium magnesium fine-grained vanadium-titanium magnetite ore, by mass percentage, includes: TFe 18%~28%, SiO2 15%~26%, CaO 3%~8%, MgO 4%~10%, TiO 25%~12%, and the total content of CaO and MgO is not less than 8%.

[0015] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step B, the fineness of the second-stage fine grinding is controlled to be -0.045mm, accounting for 85%~95wt%.

[0016] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, in step C, the amount of sodium hydroxide added is to adjust the pH value of the slurry to 10.5~11.5.

[0017] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, the amount of causticized starch added is 800g / t~1200g / t.

[0018] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, the amount of calcium chloride added in step C is 400g / t to 600g / t.

[0019] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, the amount of sodium hexametaphosphate added in step C is 150g / t~300g / t.

[0020] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, in step C, the amount of composite anionic collector added is 600g / t~900g / t.

[0021] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, sodium hydroxide is added and stirred for 1 min to 5 min.

[0022] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, causticized starch with iron mineral inhibitor is added and stirred for 1 min to 5 min.

[0023] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, calcium chloride, a calcium magnesium gangue activator, is added and stirred for 1 min to 5 min.

[0024] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, sodium hexametaphosphate, an inorganic dispersant, is added and stirred for 1 min to 5 min.

[0025] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, after adding the composite anionic collector, the mixture is stirred for 1 min to 5 min.

[0026] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, the causticized starch is prepared by dry starch and NaOH, and the mass ratio of dry starch to NaOH is 4~5:1.

[0027] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, the causticized starch is added as follows: dry starch and NaOH are mixed at a mass ratio of 4~5:1 and then added to hot water at 80~95℃ to prepare a causticized starch aqueous solution with a concentration of 1%~5% based on the mass of dry starch, and then added to the reverse flotation system.

[0028] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, calcium chloride is added by preparing an aqueous solution with a mass concentration of 5% to 15% and then adding it to the reverse flotation system.

[0029] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, sodium hexametaphosphate is added by preparing an aqueous solution with a mass concentration of 1% to 10% and then adding it to the reverse flotation system.

[0030] In the above-mentioned combined strong magnetic-reverse flotation tailings removal method, in step C, the composite anionic collector is added as follows: sodium oleate and sodium methyl cocoate sulfonate are mixed at an effective component mass ratio of 3.5~4.5:1 to prepare an aqueous solution with a concentration of 1%~10% based on the total mass of the effective components of the two, and then added to the reverse flotation system.

[0031] In the aforementioned combined strong magnetic-reverse flotation tailings removal method, in step C, the active ingredient mass fraction of sodium cocoate methyl sulfonate is greater than 85%, the average carbon chain length is C12~C14, and the inorganic salt mass fraction is less than 5%.

[0032] In this invention, except for sodium hydroxide which is adjusted according to the pH value of the slurry, the amount of each reagent added in step C is based on the mass of the dry concentrate of the strong magnetic enrichment entering the reverse flotation operation; the amount of causticized starch added is based on the mass of dry starch; the amounts of calcium chloride and sodium hexametaphosphate added are based on the mass of the effective components of CaCl2 and sodium hexametaphosphate, respectively; and the amount of composite anionic collector added is based on the total mass of the effective components of sodium oleate and sodium methyl cocoate sulfonate.

[0033] The beneficial effects of this invention are:

[0034] This invention employs a compound of sodium oleate and sodium cocoyl sulfonate of a specific specification at an effective component mass ratio of 3.5:1 to 4.5:1. MES and sodium oleate form a mixed adsorption and association structure, which improves the dispersion stability of the collector and reduces the tendency of sodium oleate to form insoluble calcium oleate and become inactive when used alone; the critical micelle surface tension of the composite system is reduced to below 23.0 mN / m. Sodium hexametaphosphate is added before the collector, utilizing its complexing, dispersing, and enhanced electrostatic repulsion between particles, combined with MES to improve the dispersion state of ultrafine particles, controlling the slurry kinetic viscosity at 1.2 Pa·s to 1.5 Pa·s and the yield stress at 0.5 Pa to 0.8 Pa, thereby reducing the agglomeration of ultrafine ore slime, non-selective coating on the iron mineral surface, and mechanical entrainment.

[0035] This invention employs a "two-stage grinding and separation" process combined with "strong magnetic pulsation pre-enrichment." Before calcium and magnesium removal by reverse flotation, a two-stage fine grinding process is used in conjunction with a vertical annular pulsation high-gradient strong magnetic separation (background magnetic field 0.6T~0.8T, pulsation frequency 200Hz~300Hz). The pulsating fluid flushing action removes easily adhering non-magnetic ultrafine ore slime of -10μm in advance, purifying the flotation slurry environment from a physical separation level. The first-stage magnetic separation coarse polishing can discard 45%~55% of the coarse tailings, reducing the amount of the second-stage fine grinding and lowering the energy consumption of subsequent grinding.

[0036] The present invention reduces the CaO+MgO impurity content of the iron concentrate from more than 10.0 wt% in the raw ore to less than 1.42 wt%, the total iron (TFe) grade reaches more than 59.50%, and the iron recovery rate reaches more than 75.80%. Compared with the single sodium oleate reverse flotation process of Comparative Example 1, the iron recovery rate is increased by 3.70 percentage points. The reduction of calcium and magnesium impurities in the concentrate is beneficial to reducing the amount of smelting slag and improving the slag fluidity. Attached Figure Description

[0037] Figure 1 This is a system block diagram of the combined strong magnetic-reverse flotation tailings removal method for high-calcium-magnesium fine-grained vanadium-titanium magnetite according to the present invention.

[0038] Figure 2 This is a process flow diagram of the combined strong magnetic-reverse flotation tailings removal method for high-calcium-magnesium fine-grained vanadium-titanium magnetite in an embodiment of the present invention. Detailed Implementation

[0039] Specifically, a combined strong magnetic-reverse flotation tailings removal method for fine-grained vanadium-titanium magnetite with high calcium and magnesium content includes the following steps:

[0040] A. Primary grinding-weak magnetic roughing and tailings disposal: The high-calcium-magnesium fine-grained vanadium-titanium magnetite ore is subjected to primary grinding, with the fineness of the primary grinding controlled at -0.074mm accounting for 60%~70wt%. The ground slurry is then fed into a wet weak magnetic separator for roughing at a magnetic field strength of 0.12T~0.18T, separating the primary rough concentrate and weak magnetic tailings (directly discarded). This step can discard 40%~55% of the coarse gangue in advance, significantly reducing the amount of subsequent processing.

[0041] The main chemical components of the high-calcium-magnesium fine-grained vanadium-titanium magnetite ore processed by this invention, by mass percentage, include: TFe 18%~28%, SiO2 15%~26%, CaO 3%~8%, MgO 4%~10%, TiO2 5%~12%, and the total content of CaO and MgO is not less than 8%; for example, high-calcium-magnesium fine-grained vanadium-titanium magnetite from the Panzhihua-Xichang region of Sichuan.

[0042] B. Two-stage fine grinding-strong magnetic pre-enrichment and desliming: The primary coarse concentrate is fed into the secondary fine grinding stage, and the fineness of the secondary fine grinding stage is controlled to be -0.045mm accounting for 85%~95wt%, so as to achieve complete individual liberation of iron minerals and calcium magnesium gangue; the slurry after fine grinding is fed into a pulsating high gradient strong magnetic separator for strong magnetic separation, and the background magnetic field strength is controlled to be 0.6T~0.8T, and the pulsation frequency is 200Hz~300Hz. After separation, a strong magnetic enriched concentrate is obtained and the strong magnetic tailings are discarded; this step uses the pulsating fluid flushing action to remove non-magnetic ultrafine slime below -10μm and purify the reverse flotation slurry environment.

[0043] C. Reverse Flotation of Strong Magnetic Concentrate to Remove Calcium and Magnesium: The strong magnetic enrichment concentrate is subjected to reverse flotation to adjust the pulp concentration to 28%~35wt%. The following reagents are added and operated in sequence in the flotation cell: First, sodium hydroxide (NaOH) is added to adjust the pulp pH to 10.5~11.5, and stirred for 1min~5min; then, causticized starch, an iron mineral inhibitor, is added at a rate of 800g / t~1200g / t, and stirred for 1min~5min; finally, calcium chloride, a calcium and magnesium gangue activator, is added... The reagents are added at a rate of 400 g / t to 600 g / t, and stirred for 1 to 5 minutes. Then, the inorganic dispersant sodium hexametaphosphate is added at a rate of 150 g / t to 300 g / t, and stirred for 1 to 5 minutes. Finally, the composite anionic collector is added at a rate of 600 g / t to 900 g / t, and stirred for 1 to 5 minutes. After the reagents are added, a closed-circuit flotation process consisting of one roughing, one cleaning, and two scavenging stages is performed. The froth product is calcium-magnesium rich tailings, and the underflow is the final high-grade low-calcium magnesium iron concentrate. The closed-circuit flotation process of roughing, cleaning, and two scavenging stages is carried out using conventional methods in this field.

[0044] In this invention, except for sodium hydroxide adjusted according to the pH value of the slurry, the addition amounts of the other reagents are based on the mass of the dry magnetically enriched concentrate entering the reverse flotation operation, and are calculated according to the mass of the corresponding effective components. Causticizing starch is prepared from dry starch and NaOH, with a mass ratio of dry starch to NaOH of 4-5:1; the two are mixed and added to hot water at 80-95℃ to prepare a causticizing starch aqueous solution with a concentration of 1%-5% based on the mass of dry starch. Calcium chloride and sodium hexametaphosphate are prepared into aqueous solutions with mass concentrations of 5%-15% and 1%-10%, respectively. The composite anionic collector is composed of sodium oleate and sodium methyl cocoate sulfonate at an effective component mass ratio of 3.5-4.5:1, and is prepared into an aqueous solution with a concentration of 1%-10% based on the total mass of the effective components of both. The above reagents are generally added to the reverse flotation system in aqueous solution form.

[0045] In this invention, the composite anionic collector is prepared by compounding sodium oleate and sodium methyl cocoate sulfonate (MES) of a specific specification at an active ingredient mass ratio of 3.5~4.5:1. The MES has an active ingredient mass fraction greater than 85%, an average carbon chain length of C12~C14, and an inorganic salt mass fraction of less than 5%. It operates at pH 10.5~11.5 and contains Ca... 2+In the medium, MES can form a mixed adsorption and association structure with sodium oleate, improving the dispersion stability of the collector and reducing the tendency of sodium oleate to form insoluble calcium oleate and become inactive when used alone. The critical micelle surface tension of the composite system is reduced to below 23.0 mN / m, which is beneficial for the selective adsorption of the collector on the surface of calcium magnesium gangue such as pyroxene and plagioclase. In this invention, under the condition of reverse flotation pulp concentration of 28%~35wt%, sodium hexametaphosphate improves the dispersion state of ultrafine particles by complexing, dispersing and enhancing the electrostatic repulsion between particles, in combination with sulfonic acid-containing MES. The zeta potential of ultrafine gangue particles is -35mV~-45mV, the kinetic viscosity of the pulp is controlled at 1.2Pa·s~1.5Pa·s, and the yield stress is controlled at 0.5Pa~0.8Pa, thereby reducing the agglomeration of ultrafine slime, non-selective coverage of iron mineral surfaces, and mechanical entrainment.

[0046] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0047] The raw material ore used in the embodiments and comparative examples of this invention is low-grade, high-calcium-magnesium fine-grained vanadium-titanium magnetite from the Panzhihua-Xichang region. Its main chemical composition (mass fraction) is: total iron (TFe) 21.35wt%, silicon dioxide (SiO2) 20.48wt%, calcium oxide (CaO) 5.12wt%, magnesium oxide (MgO) 6.34wt%, and titanium dioxide (TiO2) 7.20wt% (the gangue minerals in the raw ore are mainly titanium pyroxene and plagioclase, and the total amount of CaO+MgO is 11.46wt%). The sodium methyl cocoate sulfonate (MES) used is industrial grade, with an active ingredient mass fraction of 88wt%, an average carbon chain length of C12~C14, and an inorganic salt mass fraction of 2.2wt%.

[0048] Example 1

[0049] First-stage grinding-weak magnetic roughing and tailings disposal: The raw ore is ground to -0.074mm (65wt%) and fed into a drum-type wet weak magnetic separator for first-stage magnetic separation. The magnetic field strength is controlled at 0.15T. After magnetic separation, a first-stage rough concentrate (TFe grade of 38.64wt%, yield of 46.50%) and weak magnetic tailings (directly disposed of) are obtained. This step discards 46.80% of the coarse-grained non-magnetic gangue in advance, significantly reducing the processing energy consumption of the second-stage grinding.

[0050] Two-stage fine grinding-strong magnetic pre-enrichment and desliming: The primary coarse concentrate is fed into a fine grinding mill and ground to -0.045mm (90wt%). The finely ground slurry is then fed into a vertical annular pulsating high gradient strong magnetic separator. The background magnetic field strength is set to 0.7T and the pulsation frequency to 250Hz. After strong magnetic separation, a strong magnetic enriched concentrate (TFe grade 48.12wt%, CaO+MgO content 4.65wt%) and strong magnetic tailings (discarded) are obtained. This step utilizes the pulsating fluid flushing action to remove easily adhering non-magnetic ultrafine slime below -10μm.

[0051] Reverse flotation decalcification and magnesium removal from strong magnetic enrichment concentrate: The strong magnetic enrichment concentrate is subjected to reverse flotation slurry preparation, with the slurry concentration controlled at 30 wt%, and then fed into a self-aspirating flotation machine. The slurry is prepared according to the following reagent regimen and operating sequence:

[0052] First, add NaOH to adjust the pH of the slurry to 11.0, and stir for 3 minutes;

[0053] Then add 1000g·t -1 Causticized starch (based on dry starch mass; dry starch and NaOH are mixed at a mass ratio of 4.5:1, and then stirred in 90°C hot water to prepare an aqueous solution with a dry starch mass concentration of 3%, which is then added in the form of an aqueous solution), stirred for 3 min;

[0054] Then add 500g·t -1 Add calcium chloride (calculated as CaCl2 effective ingredient; prepare a 10% (w / w) aqueous solution of calcium chloride and add it as an aqueous solution), and stir for 2 minutes.

[0055] Then add 200g·t -1 Sodium hexametaphosphate (based on the effective component of sodium hexametaphosphate; sodium hexametaphosphate is prepared into a 5% aqueous solution and added in aqueous form) is used as a dispersant, and the mixture is stirred for 2 minutes.

[0056] Finally add 800g·t -1 The composite anionic collector (based on the total mass of sodium oleate and MES active ingredients; the two are compounded at a mass ratio of 4:1 and prepared into an aqueous solution with a concentration of 5% based on the total mass of active ingredients, and added in the form of an aqueous solution) is stirred for 3 min.

[0057] After the reagents are added, a closed-circuit reverse flotation process consisting of one roughing, one cleaning, and two scavenging stages is performed.

[0058] Indicator Testing and Results:

[0059] Sorting indicators: The final bottom flow in the trough yielded a high-grade, low-calcium-magnesium iron concentrate with a TFe grade of 59.85 wt% and a CaO+MgO content of 1.28 wt%, meeting the standards for smelting premium concentrate; compared with the original ore, the iron recovery rate reached 76.54%.

[0060] Physicochemical and rheological parameters: The critical micelle surface tension of the composite collector in the slurry was tested ( The concentration was reduced to 22.5 mN·m -1 ; Kinetic viscosity of ultrafine slurry system under reverse flotation slurry conditioning conditions ( The yield stress is 1.35 Pa·s. The Pa value was 0.65; the ultrafine sludge was well dispersed, and no obvious shear thickening or mud covering occurred.

[0061] Example 2

[0062] First-stage grinding-weak magnetic roughing and tailings disposal: The raw ore is ground to -0.074mm (60wt%), and the magnetic field strength of the first-stage magnetic separator is controlled at 0.12T to obtain a first-stage rough concentrate (TFe grade of 37.50wt%, yield of 45.00%) and a first-stage direct waste tailings.

[0063] Two-stage fine grinding-strong magnetic pre-enrichment and desliming: The first stage coarse concentrate is finely ground to -0.045mm, accounting for 85wt%. The background magnetic field strength of the strong magnetic separator is set to 0.6T and the pulsation frequency is 200Hz. After separation, strong magnetic enrichment concentrate (TFe grade is 46.80wt%, CaO+MgO content is 5.10wt%) and strong magnetic separation tailings are obtained.

[0064] High-intensity magnetic enrichment concentrate reverse flotation decalcification and magnesium removal: The pulp concentration of the high-intensity magnetic enrichment concentrate reverse flotation is controlled at 28 wt%, and it is fed into the flotation machine. The pulp is then prepared according to the following reagent regimen and operating sequence:

[0065] First, add NaOH to adjust the pH of the slurry to 10.5, and stir for 3 minutes;

[0066] Then add 800g·t -1 Causticized starch (based on dry starch mass; dry starch and NaOH are mixed at a mass ratio of 4.5:1, and then stirred in 90°C hot water to prepare an aqueous solution with a dry starch mass concentration of 3%, which is then added in the form of an aqueous solution), stirred for 3 min;

[0067] Then add 400g·t -1 Add calcium chloride (calculated as CaCl2 effective ingredient; prepare a 10% (w / w) aqueous solution of calcium chloride and add it as an aqueous solution), and stir for 2 minutes.

[0068] Then add 150g·t -1 Sodium hexametaphosphate (based on the effective component of sodium hexametaphosphate; prepare a 5% aqueous solution of sodium hexametaphosphate and add it in aqueous solution form), stir for 2 min;

[0069] Finally add 600g·t-1 The composite anionic collector (based on the total mass of sodium oleate and MES active ingredients; the two are compounded at a mass ratio of 4:1 and prepared into an aqueous solution with a concentration of 5% based on the total mass of active ingredients, and added in the form of an aqueous solution) is stirred for 3 min.

[0070] After the reagents are added, a closed-circuit reverse flotation process consisting of one roughing, one cleaning, and two scavenging stages is performed.

[0071] Indicator Testing and Results:

[0072] Sorting indicators: The final bottom flow in the tank yielded high-grade iron concentrate with a TFe grade of 59.50 wt% and a CaO+MgO content of 1.42 wt%, meeting the standards for smelting premium concentrate; compared with the original ore, the iron recovery rate reached 75.80%.

[0073] Physicochemical and rheological parameters: Critical micelle surface tension ( The value is 22.8 mN·m -1 ; Kinetic viscosity of ultrafine slurry system ( The yield stress is 1.45 Pa·s. The value is 0.78 Pa.

[0074] Example 3

[0075] First-stage grinding-weak magnetic roughing and tailings disposal: The raw ore is ground to -0.074mm (70wt%), and the magnetic field strength of the first-stage magnetic separation is controlled at 0.18T to obtain a first-stage rough concentrate (TFe grade of 39.60wt%, yield of 48.00%) and directly discarded tailings.

[0076] Two-stage fine grinding-strong magnetic pre-enrichment and desliming: The first stage coarse concentrate is finely ground to -0.045mm, accounting for 95wt%. The background magnetic field strength of the strong magnetic separator is 0.8T, and the pulsation frequency is 300Hz. After separation, strong magnetic enrichment concentrate (TFe grade is 49.40wt%, CaO+MgO content is 4.20wt%) and strong magnetic separation tailings are obtained.

[0077] High-intensity magnetic enrichment concentrate reverse flotation decalcification and magnesium removal: The pulp concentration of the high-intensity magnetic enrichment concentrate reverse flotation is controlled at 35 wt%, and it is fed into the flotation machine. The pulp is then prepared according to the following reagent regimen and operating sequence:

[0078] First, add NaOH to adjust the pH of the slurry to 11.5, and stir for 3 minutes;

[0079] Then add 1200g·t -1 Causticized starch (based on dry starch mass; dry starch and NaOH are mixed at a mass ratio of 4.5:1, and then stirred in 90°C hot water to prepare an aqueous solution with a dry starch mass concentration of 3%, which is then added in the form of an aqueous solution), stirred for 3 min;

[0080] Then add 600g·t -1 Add calcium chloride (calculated as CaCl2 effective ingredient; prepare a 10% (w / w) aqueous solution of calcium chloride and add it as an aqueous solution), and stir for 2 minutes.

[0081] Then add 300g·t -1 Sodium hexametaphosphate (based on the effective component of sodium hexametaphosphate; prepare a 5% aqueous solution of sodium hexametaphosphate and add it in aqueous solution form), stir for 2 min;

[0082] Finally add 900g·t -1 The composite anionic collector (based on the total mass of sodium oleate and MES active ingredients; the two are compounded at a mass ratio of 4:1 and prepared into an aqueous solution with a concentration of 5% based on the total mass of active ingredients, and added in the form of an aqueous solution) is stirred for 3 min.

[0083] After the reagents are added, a closed-circuit reverse flotation process consisting of one roughing, one cleaning, and two scavenging stages is performed.

[0084] Indicator Testing and Results:

[0085] Sorting indicators: The final bottom flow in the tank yielded high-grade iron concentrate with a TFe grade of 60.10 wt% and a CaO+MgO content reduced to 1.15 wt%, meeting the standards for smelting premium concentrate; compared with the original ore, the iron recovery rate reached 77.10%.

[0086] Physicochemical and rheological parameters: Critical micelle surface tension ( The value is 21.8 mN·m -1 ; Kinetic viscosity of ultrafine slurry system ( The yield stress is 1.25 Pa·s. The value is 0.52 Pa.

[0087] Comparative Example 1 (using sodium oleate collector alone without dispersant)

[0088] This comparative example uses only sodium oleate as the collector, with an addition amount of 800 g / t. -1 (Based on sodium oleate as the active ingredient; sodium oleate is prepared into an aqueous solution with an active ingredient concentration of 5% by mass and added in the form of an aqueous solution), except that sodium hexametaphosphate, a dispersant, is not added. The remaining steps, types of reagents, process parameters, and operation sequence are the same as in Example 1.

[0089] Indicator Testing and Results:

[0090] Sorting parameters: The final iron concentrate had a TFe grade of only 56.40 wt%, a high CaO+MgO content of 2.85 wt%, and an iron recovery rate of 72.10%. This indicates that sodium oleate alone, at pH 11.0 and in high-calcium (CaO) conditions, exhibits good iron recovery. 2+ In this environment, a large amount of calcium salt precipitation occurred, the reagents became ineffective, and at the same time, due to the lack of sodium hexametaphosphate dispersion, a large amount of ultrafine ore slime agglomerated and clumped in the iron concentrate under strong shear, which deteriorated the concentrate quality.

[0091] Physicochemical and rheological parameters: Critical micelle surface tension ( The value is 42.0 mN·m -1 ; Kinetic viscosity of the slurry system under agitation in the flotation cell ( The nonlinearity increased significantly to 5.20 Pa·s, and the yield stress ( The pressure reached 2.10 Pa, indicating severe slurry shear thickening and mud covering.

[0092] Comparative Example 2 (using MES collector alone)

[0093] This comparative example uses only sodium methyl cocoate sulfonate (MES) as the collector, with an addition amount of 800 g / t. -1 (Based on the effective ingredient of MES; prepare MES into an aqueous solution with an effective ingredient concentration of 5% by mass and add it in the form of an aqueous solution) The remaining steps, reagent types, process parameters, and operation sequence are the same as in Example 1.

[0094] Indicator Testing and Results:

[0095] Sorting indicators: The final iron concentrate had a TFe grade of only 55.12 wt%, a CaO+MgO content as high as 3.10 wt%, and an iron recovery rate of 74.80%. This indicates that the collection intensity of a single MES is seriously insufficient, its adhesion to the activated sites on the surface of calcium-magnesium gangue is weak, and its foam entrainment capacity is low, resulting in a large amount of calcium-magnesium minerals remaining in the bottom iron concentrate and low sorting efficiency.

[0096] Physicochemical and rheological parameters: Critical micelle surface tension of a single MES in slurry ( The value is 38.0 mN·m -1 No synergistic reduction effect was observed in the composite collector system.

Claims

1. A combined strong magnetic-reverse flotation tailings removal method for fine-grained vanadium-titanium magnetite with high calcium and magnesium content, characterized in that: Includes the following steps: A. First-stage grinding-weak magnetic roughing: The high-calcium magnesium fine-grained vanadium-titanium magnetite ore is ground in one stage, and the slurry after grinding is roughed under a magnetic field strength of 0.12T~0.18T to obtain a first-stage rough concentrate and weak magnetic tailings. B. Two-stage fine grinding-strong magnetic pre-enrichment: The primary rough concentrate is subjected to two-stage fine grinding. The finely ground slurry is subjected to strong magnetic separation under a background magnetic field strength of 0.6T~0.8T and a pulsation frequency of 200Hz~300Hz to obtain strong magnetic enriched concentrate and strong magnetic tailings. C. Reverse flotation to remove calcium and magnesium: The strongly magnetically enriched concentrate is subjected to reverse flotation to adjust the slurry concentration to 28%~35wt%. Sodium hydroxide is added in sequence: first, iron mineral inhibitor causticized starch is added; then, calcium chloride, calcium and magnesium gangue activator is added; then, sodium hexametaphosphate, an inorganic dispersant is added; finally, a composite anionic collector is added. After the reagents are added, a closed-circuit reverse flotation is carried out with one roughing, one cleaning and two scavenging processes to obtain high-grade low-calcium magnesium iron concentrate and calcium-magnesium rich tailings. In step C, the composite anionic collector is prepared by using sodium oleate and sodium methyl cocoate sulfonate at a mass ratio of 3.5~4.5:

1.

2. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: In step A, the fineness of the first grinding stage is controlled to be -0.074 mm, accounting for 60%~70 wt%.

3. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: In step A, the chemical composition of the high-calcium-magnesium fine-grained vanadium-titanium magnetite ore by mass percentage includes: TFe 18%~28%, SiO2 15%~26%, CaO 3%~8%, MgO 4%~10%, TiO2 5%~12%, and the total content of CaO and MgO is not less than 8%.

4. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: In step B, the fineness of the second-stage fine grinding is controlled to be -0.045mm, accounting for 85%~95wt%.

5. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: At least one of the following must be met: In step C, the amount of sodium hydroxide added is to adjust the pH of the slurry to 10.5~11.5; In step C, the amount of causticized starch added is 800g / t~1200g / t; In step C, the amount of calcium chloride added is 400g / t to 600g / t; In step C, the amount of sodium hexametaphosphate added is 150g / t~300g / t; In step C, the amount of composite anionic collector added is 600g / t to 900g / t.

6. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: At least one of the following must be met: In step C, after adding sodium hydroxide, stir for 1 to 5 minutes; In step C, after adding the iron mineral inhibitor and causticizing the starch, stir for 1 to 5 minutes; In step C, calcium chloride, the calcium magnesium gangue activator, is added and stirred for 1 to 5 minutes. In step C, after adding the inorganic dispersant sodium hexametaphosphate, stir for 1 min to 5 min; In step C, after adding the composite anionic collector, stir for 1 to 5 minutes.

7. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: In step C, the causticized starch is prepared by using dry starch and NaOH, with a mass ratio of dry starch to NaOH of 4~5:

1.

8. The combined strong magnetic field-reverse flotation tail removal method according to claim 7, characterized in that: In step C, the causticized starch is added as follows: dry starch and NaOH are mixed at a mass ratio of 4~5:1 and then added to hot water at 80~95℃ to prepare a causticized starch aqueous solution with a concentration of 1%~5% based on the mass of dry starch, and then added to the reverse flotation system.

9. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: At least one of the following must be met: In step C, calcium chloride is added by preparing an aqueous solution with a mass concentration of 5% to 15% and then adding it to the reverse flotation system. In step C, sodium hexametaphosphate is added by preparing an aqueous solution with a mass concentration of 1% to 10% and then adding it to the reverse flotation system.

10. The combined strong magnetic field-reverse flotation tail removal method according to claim 1, characterized in that: At least one of the following must be met: In step C, the composite anionic collector is added as follows: sodium oleate and sodium methyl cocoate sulfonate are mixed at an effective component mass ratio of 3.5~4.5:1 to prepare an aqueous solution with a concentration of 1%~10% based on the total mass of the effective components of the two, and then added to the reverse flotation system. In step C, the active ingredient mass fraction of sodium methyl cocoate sulfonate is greater than 85%, the average carbon chain length is C12~C14, and the inorganic salt mass fraction is less than 5%.

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