High-added-value recycling method of silicon and iron elements in iron tailings

Abstract

The invention provides a high-added-value recycling method of silicon and iron elements in iron tailings, and relates to the technical field of high-value and resource utilization of metallurgical solid wastes. The method comprises the steps of iron tailing grinding, middle-stage magnetic separation, microwave roasting, water quenching, grinding, high-stage magnetic separation, first-stage hot-pressing acid leaching, vacuum roasting, water quenching, second-stage hot-pressing acid leaching, low-stage magnetic separation of weakly magnetic minerals, ultrasonic acid leaching for iron extraction, aging reaction, filtering, drying and roasting. And finally obtaining high-purity quartz powder of more than 4N grade and nano iron oxide of which the purity of Fe2O3 is more than 95%. According to the method, silicon and iron elements in the iron tailings are recycled in a layered and stepped manner, and the acid leaching filtrate generated in the preparation process of the high-purity quartz powder is subjected to closed treatment, so that valuable components of silicon and iron in the iron tailings are utilized at a high value to the maximum extent, and no secondary waste liquid is discharged; meanwhile, the problem of fluorine pollution in the traditional process is avoided in the process of preparing the high-purity quartz powder, and the method is low-carbon and green and has remarkable economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of high-value and resource utilization of metallurgical solid waste, and in particular to a high-value-added recycling method for silicon and iron elements in iron tailings. Background Art

[0002] As my country's industrialization process continues to advance, steel, as a necessity for national development, has a large demand that has promoted the vigorous development of the iron ore industry, but at the same time has produced a huge amount of iron tailings. According to statistics, the current stockpile of iron tailings in my country is as high as more than 20 billion tons, and the annual discharge rate is increasing at a rate of tens of millions of tons, but the comprehensive utilization rate is less than 30%. Such a large output of iron tailings has brought a series of problems to the ecological environment and the safety of life and property. As a "misplaced secondary resource", iron tailings have huge potential economic value and application value.

[0003] The recycling of iron tailings at home and abroad is mainly concentrated in the fields of building materials preparation, soil remediation, backfilling of mining areas and recovery of valuables. The comprehensive utilization of iron tailings started relatively late, and most research focuses on low value-added applications. In view of the potential characteristics of iron tailings, they can be used to prepare high value-added industrial materials. Iron tailings are rich in valuable components, especially silicon and iron elements, but there is currently little research on the preparation of high-purity quartz and high-value-added nano-iron oxide from iron tailings.

[0004] As an irreplaceable key mineral raw material in the field of high-tech, high-purity quartz is widely used in high-tech industries such as aerospace, optical fiber, information technology, and national defense. Due to the shortage of domestic raw materials and the lag in key preparation technologies, the quality of high-purity quartz products is difficult to meet the needs of high technology. At present, the high price and restrictions of imported high-purity quartz restrict the development of high-end science and technology. At present, the preparation of high-purity quartz mainly adopts hydrometallurgical process, which inevitably produces a large amount of acidic waste liquid, which requires secondary treatment and has high process costs. Summary of the invention

[0005] In order to solve the above-mentioned technical problems existing in the prior art, an embodiment of the present invention provides a high value-added recycling method for silicon and iron elements in iron tailings. The method adopts a physical magnetic separation method to recover silicon and iron elements in iron tailings in a hierarchical manner, thereby avoiding the generation of wastewater in the flotation process. The addition of sodium carbonate-microwave roasting-secondary grinding process to silicon-rich powder A can effectively dissociate quartz intergrowths and inclusions in the mineral, solving the problem of difficult removal of quartz intergrowths and inclusions during the smelting process. The vacuum roasting-water quenching process is beneficial to the removal of bubbles, water marks and some encapsulated impurities inside the mineral, while opening the acid leaching channel for lattice impurities inside the quartz to promote acid leaching removal. In addition, the acid leaching filtrate generated in the preparation process of high-purity quartz powder is recycled for secondary use, and the tailings can be used as mineral micropowder in the construction industry, and the entire process has no waste discharge.

[0006] The technical solution is as follows:

[0007] A high value-added recycling method for silicon and iron elements in iron tailings, the method comprising:

[0008] S1, grinding and dissociating the iron tailings;

[0009] S2, performing mid-stage magnetic separation on the fine iron tailings obtained in step S1 to obtain weakly magnetic mineral A and silicon-rich powder A;

[0010] S3, adding sodium salt to the silicon-rich powder A obtained in step S2, quenching with water after microwave roasting, and grinding again to obtain fine silicon-rich powder B;

[0011] S4, subjecting the fine silicon-rich powder B obtained in step S3 to high-segment magnetic separation to obtain high silicon powder A and weakly magnetic mineral B;

[0012] S5, subjecting the high silicon powder A obtained in step S4 to a hot-pressing leaching step to obtain high-purity quartz powder A and acid leaching filtrate A;

[0013] S6, the high-purity quartz powder A obtained in step S5 is vacuum roasted and then water quenched, and then subjected to two-stage hot pressing leaching to obtain high-purity quartz powder B of grade 4N or above and acid leaching filtrate B;

[0014] S7, performing low-stage magnetic separation on the weakly magnetic mineral A obtained in step S2 and the weakly magnetic mineral B obtained in step S4 to recover iron-rich powder;

[0015] S8, mixing the leaching solution A obtained in step S5, the leaching solution B obtained in step S6 and the iron-rich powder and subjecting them to ultrasonic reaction to obtain an iron-rich solution and high-silicon powder B, wherein the high-silicon powder B is returned to step S5;

[0016] S9, adding hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder to the iron-rich solution obtained in step S8, then adjusting the solution pH to 5-10 and aging for 2-6 hours, then filtering, drying and roasting in sequence to obtain a highly dispersed nano-iron oxide product, wherein Fe 2 O 3 The purity reaches over 95% and the particle size is 10 to 100 nm.

[0017] In the step S1, SiO 2 Content 70~90%, Fe 2 O 3 The content is 8-25%, and the remainder is impurities; the grinding particle size is 25-47μm.

[0018] The magnetic induction intensity of the middle magnetic separation in step S2 is 15000-20000G; the pulp concentration during magnetic separation is 10-35%, and the feed flow rate is 0.1-2t / h.

[0019] The sodium salt in step S3 is NaCl, Na 2 CO 3 、NaHCO 3 、Na 2 SO 4 Or Na 2 O 2 One of the above, its addition amount is 2-9‰; microwave roasting is at 600-950°C for 0.5-4h; water quenching time is 2-7min; grinding particle size is 15-25μm.

[0020] The magnetic induction intensity of the high-stage magnetic separation in step S4 is 40000-80000G; the slurry concentration during magnetic separation is 5-20%, and the feed flow rate is 0.05-0.5 t / h.

[0021] In step S5, the temperature of the first hot-pressing leaching is 120-180° C., the time of the first hot-pressing leaching is 4-8 hours, the leaching liquid is a mixture of one or more of 15-30% hydrochloric acid, 50-80% sulfuric acid, 30-70% phosphoric acid, and 30-55% nitric acid, and the solid-liquid ratio of high silicon powder A to the leaching liquid is 1: (2-5) t / m 3 .

[0022] In step S6, the vacuum roasting is performed at 900-1100° C. for 1-6 hours; the water quenching time is 2-7 minutes; the second-stage hot pressing leaching temperature is 120-200° C., the second-stage hot pressing leaching time is 6-10 hours, the leaching liquid is a mixture of one or more of 15-30% hydrochloric acid, 30-50% sulfuric acid, 30-45% phosphoric acid, and 25-50% nitric acid, and the solid-liquid ratio of high-purity quartz powder A to the leaching liquid is 1: (3-6) t / m 3 .

[0023] The magnetic induction intensity of the low-stage magnetic separation in step S7 is 8000-12000G; the pulp concentration during magnetic separation is 10-20%, and the feed flow rate is 0.5-2.5 t / h.

[0024] In step S8, the ultrasonic intensity is 200-400W, the reaction temperature is 50-80°C, the stirring rate is 160-250r / min, and the ultrasonic time is 2-6h; the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1: (4-7) t / m 3 .

[0025] In step S9, the amount of hydrogen peroxide used is 0.2-0.9‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution used is 0.5-1.2‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1: (50-100) kg / m 3 The drying temperature is 60°C for 4 to 6 hours, the calcination temperature is 120 to 300°C, and the calcination time is 2 to 6 hours.

[0026] The beneficial effects of the present invention include at least:

[0027] (1) Since iron tailings are mainly composed of weakly magnetic iron oxides and non-magnetic gangue, silicates, carbonates and other minerals, conventional electromagnetic separation is difficult to achieve efficient separation of valuable components. To this end, the present invention separates and extracts high silicon powder A in iron tailings through a hierarchical middle-high section strong magnetic separation process, and separates and recovers iron-rich powder in iron tailings through a middle-low section strong magnetic separation process. This process effectively improves the separation efficiency and accuracy of the target minerals, while avoiding the magnetic agglomeration of weak magnetic particles under a high-intensity magnetic field, which deteriorates the separation effect.

[0028] (2) The present invention adopts the microwave sodium roasting-water quenching-grinding-high-stage magnetic separation process for the first time, which can physically remove mineral inclusions and quartz intergrowths in the silicon-rich powder A to the maximum extent. Specifically, microwave sodium roasting will cause the structure of mineral inclusions and quartz intergrowths to be destroyed, while water quenching will increase cracks on the quartz surface, which is conducive to the dissociation of grinding minerals; high-stage magnetic separation can effectively separate and remove weak magnetic particles in the fine silicon-rich powder A.

[0029] (3) The fluorine-free two-stage hot-pressing leaching and vacuum roasting-water quenching process proposed in the present invention effectively achieves deep removal of impurities in high silicon powder and obtains high-purity SiO above 4N level. 2 Product. Specifically, the first stage hot-pressing leaching can remove impurity conjoined bodies and included minerals in high-silicon powder, but the removal effect on lattice impurities and gas-liquid / mineral inclusions in quartz is poor; therefore, the combined heating uniformity and low-pollution vacuum roasting process can deeply remove gas-liquid inclusion impurities in quartz. At the same time, the roasted sample will cause large cracks in the quartz particles after water quenching, so that the internal impurities are fully exposed, which is conducive to the second stage hot-pressing leaching of lattice impurities and mineral inclusions in quartz. The present invention breaks through the existing high-purity SiO 2 The technical barrier of fluorine-containing preparation has enabled the first purification of iron tailings without fluorine to produce high-purity quartz powder of grade 4N or above, with significant economic benefits.

[0030] (4) The acid leaching filtrate produced in the preparation process of high-purity quartz powder is used as an acid leaching agent, and the iron-rich powder is used as an iron source to prepare nano-iron oxide, thereby realizing the recycling of the acid leaching filtrate and the high-value utilization of the iron element, with significant economic benefits. Specifically, the present invention first effectively separates and enriches the iron-rich powder in the iron tailings through a mid-section-low-section strong magnetic separation process, reduces the content of impurity elements other than the Fe element, and is beneficial to improving the purity of the nano-iron oxide. In addition, the use of an ultrasonic acid leaching process helps to accelerate the leaching rate of the iron element in the iron-rich powder and reduce the amount of acid leaching filtrate used; hydrogen peroxide is beneficial to the oxidation of divalent iron ions in the solution to trivalent iron ions, thereby promoting the purity of the nano-iron oxide; carbon powder is used as a skeleton and sodium dodecylbenzene sulfonate solution is used as a dispersant, and the synergistic effect of the two effectively promotes the dispersion of the nano-iron oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0034] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] SiO in iron tailings 2 , Fe 2 O 3 The content of SiO 2 The content is 70%, Fe 2 O 3 The content is 25%.

[0038] S1. Grind the iron tailings to a particle size of 30 μm and scan them using a scanning electron microscope. At this time, the dissociation degree of the dissociated iron tailings reaches 80%;

[0039] S2. The fine iron tailings are subjected to mid-stage magnetic separation at a magnetic induction intensity of 18000G. During the magnetic separation, the slurry concentration of the magnetic separator is 20%, and the feed flow rate is 1t / h, to obtain weakly magnetic mineral A and silicon-rich powder A;

[0040] S3, adding 5‰ sodium carbonate to silicon-rich powder A, microwave roasting at 800°C for 2h, water quenching for 5min, and grinding for the second time to make the particle size of silicon-rich powder A 20μm, at which time the dissociation degree of quartz intergrowth and inclusion in silicon-rich powder A reaches 98%, and fine silicon-rich powder B is obtained;

[0041] S4, subjecting the fine silicon-rich powder B to high-stage magnetic separation at a magnetic induction intensity of 60000G, the slurry concentration of the magnetic separator during magnetic separation is 10%, and the feed flow rate is 0.3t / h, to obtain high silicon powder A and weak magnetic mineral B;

[0042] S5. The high silicon powder A is subjected to a hot press leaching at 150°C for 5 hours. The leaching solution of the hot press leaching is a mixture of 20% hydrochloric acid, 60% sulfuric acid, 50% phosphoric acid, and 40% nitric acid (the volume ratio of the acid solution is 1:4:2:6), wherein the solid-liquid ratio of the high silicon powder A to the leaching solution is 1:3t / m 3 , obtaining high-purity quartz powder A and acid leaching filtrate A;

[0043] S6. The high-purity quartz powder A is vacuum roasted at 1000°C for 3 hours and then water quenched for 5 minutes; then, it is subjected to two-stage hot-pressing leaching at 180°C for 7 hours. The leaching solution of the two-stage hot-pressing leaching is a mixture of 20% hydrochloric acid, 40% sulfuric acid, 35% phosphoric acid, and 35% nitric acid (the volume ratio of the acid solution is 2:3:3:7), wherein the solid-liquid ratio of the high-purity quartz powder A to the leaching solution is 1:5 t / m 3 , obtaining high-purity quartz powder B and acid leaching filtrate B above 4N grade;

[0044] S7, performing low-stage magnetic separation on weakly magnetic mineral A and weakly magnetic mineral B at a magnetic induction intensity of 10000G, wherein the slurry concentration of the magnetic separator is 15%, the feed flow rate is 1.5t / h, and iron-rich powder is recovered;

[0045] S8, the leaching solution A, the leaching solution B and the iron-rich powder are mixed and subjected to ultrasonic stirring reaction for 4 hours under the conditions of ultrasonic intensity of 300W, reaction temperature of 60°C and stirring rate of 200r / min to obtain an iron-rich solution and high silicon powder B; wherein the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1:5t / m 3 , wherein the volume of the leaching solution A accounts for 1.5 of the volume of the leaching solution B; high silicon powder B returns to step S5;

[0046] S9, hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder are added to the iron-rich solution obtained in step S8, wherein the amount of hydrogen peroxide is 0.5‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution is 0.8‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1:70kg / m 3 Then adjust the solution pH to 8 and age for 4 hours, filter, dry at 60°C for 5 hours, and calcine at 200°C for 4 hours to obtain a highly dispersed nano-iron oxide product. 2 O 3 The purity reaches 97% and the particle size is 50nm.

[0047] Example 2

[0048] SiO in iron tailings 2 , Fe 2 O 3 The content of SiO 2 The content is 80%, Fe 2 O 3 The content is 15%.

[0049] S1. Grind the iron tailings to a particle size of 47 μm and scan them using a scanning electron microscope. At this time, the dissociation degree of the dissociated iron tailings reaches 90%;

[0050] S2. The fine iron tailings are subjected to mid-stage magnetic separation at a magnetic induction intensity of 20,000 G. During the magnetic separation, the slurry concentration of the magnetic separator is 35%, and the feed flow rate is 2 t / h, to obtain weakly magnetic mineral A and silicon-rich powder A;

[0051] S3, adding 9‰ NaCl to the silicon-rich powder A, microwave roasting at 950°C for 4h, water quenching for 7min, and grinding for the second time to make the particle size of the silicon-rich powder A 25μm, at which time the dissociation degree of quartz intergrowth and inclusion in the silicon-rich powder A reaches 99%, and fine silicon-rich powder B is obtained;

[0052] S4, subjecting the fine silicon-rich powder B to high-stage magnetic separation at a magnetic induction intensity of 80000G, the slurry concentration of the magnetic separator during magnetic separation is 20%, and the feed flow rate is 0.5t / h, to obtain high silicon powder A and weak magnetic mineral B;

[0053] S5. The high silicon powder A is subjected to a hot press leaching at 180°C for 8 hours. The leaching solution of the hot press leaching is a mixture of 30% hydrochloric acid, 80% sulfuric acid, 70% phosphoric acid, and 55% nitric acid (the volume ratio of the acid solution is 2:1:2:5), wherein the solid-liquid ratio of the high silicon powder A to the leaching solution is 1:5 t / m 3 , obtaining high-purity quartz powder A and acid leaching filtrate A;

[0054] S6. The high-purity quartz powder A was vacuum roasted at 1100°C for 6 hours and then water quenched for 7 minutes; then, the high-purity quartz powder A was subjected to two-stage hot-pressing leaching at 200°C for 10 hours. The leaching solution of the two-stage hot-pressing leaching was a mixture of 30% hydrochloric acid, 50% sulfuric acid, 45% phosphoric acid, and 50% nitric acid (the volume ratio of the acid solution was 3:2:1:2), wherein the solid-liquid ratio of the high-purity quartz powder A to the leaching solution was 1:6 t / m 3 , obtaining high-purity quartz powder B and acid leaching filtrate B above 4N grade;

[0055] S7, performing low-stage magnetic separation on weakly magnetic mineral A and weakly magnetic mineral B at a magnetic induction intensity of 12000G, wherein the slurry concentration of the magnetic separator is 20%, the feed flow rate is 2.5t / h, and iron-rich powder is recovered;

[0056] S8, the leaching solution A, the leaching solution B and the iron-rich powder are mixed and subjected to ultrasonic stirring reaction for 6 hours under the conditions of ultrasonic intensity of 400W, reaction temperature of 80℃ and stirring rate of 250r / min to obtain an iron-rich solution and high silicon powder B; wherein the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1:7t / m 3 , wherein the volume of the leaching solution A accounts for 0.8 of the volume of the leaching solution B; high silicon powder B returns to step S5;

[0057] S9, hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder are added to the iron-rich solution obtained in step S8, wherein the amount of hydrogen peroxide is 0.9‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution is 1.2‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1:100kg / m 3 Then adjust the solution pH to 10 and age for 6 hours, filter, dry at 60°C for 6 hours, and calcine at 300°C for 6 hours to obtain a highly dispersed nano-iron oxide product. 2 O 3 The purity reaches 95% and the particle size is 80nm.

[0058] Example 3

[0059] SiO in iron tailings 2 , Fe 2 O 3 The content of SiO 2 The content is 75%, Fe 2 O 3 The content is 20%.

[0060] S1. Grind the iron tailings to a particle size of 25 μm and scan them using a scanning electron microscope. At this time, the dissociation degree of the dissociated iron tailings reaches 80%;

[0061] S2, the fine iron tailings are subjected to mid-stage magnetic separation at a magnetic induction intensity of 15000G, the slurry concentration of the magnetic separator is 10%, and the feed flow rate is 0.1t / h, to obtain weak magnetic mineral A and silicon-rich powder A;

[0062] S3, add 2‰ NaHCO to the silicon-rich powder A 3 , after microwave roasting at 600°C for 0.5h, water quenching for 2min, and secondary grinding, the particle size of silicon-rich powder A is 15μm, at which time the dissociation degree of quartz intergrowth and inclusion in silicon-rich powder A reaches 98%, and fine silicon-rich powder B is obtained;

[0063] S4, subjecting the fine silicon-rich powder B to high-stage magnetic separation at a magnetic induction intensity of 40000G, the slurry concentration of the magnetic separator during magnetic separation is 5%, and the feed flow rate is 0.05t / h, to obtain high silicon powder A and weak magnetic mineral B;

[0064] S5. The high silicon powder A is subjected to a hot press leaching at 120°C for 4 hours. The leaching solution of the hot press leaching is a mixture of 15% hydrochloric acid, 50% sulfuric acid, 30% phosphoric acid, and 30% nitric acid (the volume ratio of the acid solution is 3:2:2:1), wherein the solid-liquid ratio of the high silicon powder A to the leaching solution is 1:2 t / m 3 , obtaining high-purity quartz powder A and acid leaching filtrate A;

[0065] S6. The high-purity quartz powder A was vacuum roasted at 900°C for 1 hour and then water quenched for 2 minutes; then, the high-purity quartz powder A was subjected to two-stage hot-pressing leaching at 120°C for 6 hours. The leaching solution of the two-stage hot-pressing leaching was a mixture of 15% hydrochloric acid, 30% sulfuric acid, 30% phosphoric acid, and 25% nitric acid (the volume ratio of the acid solution was 1:6:3:1), wherein the solid-liquid ratio of the high-purity quartz powder A to the leaching solution was 1:3 t / m 3 , obtaining high-purity quartz powder B and acid leaching filtrate B above 4N grade;

[0066] S7, performing low-stage magnetic separation on weakly magnetic mineral A and weakly magnetic mineral B at a magnetic induction intensity of 8000G, wherein the slurry concentration of the magnetic separator is 10%, the feed flow rate is 0.5t / h, and iron-rich powder is recovered;

[0067] S8, the leaching solution A, the leaching solution B and the iron-rich powder are mixed and subjected to ultrasonic stirring reaction for 2 hours under the conditions of ultrasonic intensity of 200W, reaction temperature of 50°C and stirring rate of 160r / min to obtain an iron-rich solution and high silicon powder B; wherein the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1:4t / m 3 , wherein the volume of the leaching solution A accounts for 2 of the volume of the leaching solution B; high silicon powder B returns to step S5;

[0068] S9, hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder are added to the iron-rich solution obtained in step S8, wherein the amount of hydrogen peroxide is 0.2‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution is 0.5‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1:50kg / m 3 Then adjust the solution pH to 5 and age for 2 hours, filter, dry at 60°C for 4 hours, and calcine at 120°C for 2 hours to obtain a highly dispersed nano-iron oxide product. 2 O 3 The purity reaches 97% and the particle size is 50nm.

[0069] Example 4

[0070] SiO in iron tailings 2 , Fe 2 O 3 The content of SiO 2 The content is 90%, Fe 2 O 3 The content is 8%.

[0071] S1. Grind the iron tailings to a particle size of 25 μm and scan them using a scanning electron microscope. At this time, the dissociation degree of the dissociated iron tailings reaches 80%;

[0072] S2, the fine iron tailings are subjected to mid-stage magnetic separation at a magnetic induction intensity of 15000G, the slurry concentration of the magnetic separator is 10%, and the feed flow rate is 0.1t / h, to obtain weak magnetic mineral A and silicon-rich powder A;

[0073] S3, add 6‰ Na into the silicon-rich powder A 2 SO 4 , after microwave roasting at 700°C for 3h, water quenching for 5min, and secondary grinding, the particle size of silicon-rich powder A is 23μm, at which time the dissociation degree of quartz intergrowth and inclusion in silicon-rich powder A reaches 99%, and fine silicon-rich powder B is obtained;

[0074] S4, subjecting the fine silicon-rich powder B to high-stage magnetic separation at a magnetic induction intensity of 40000G, the slurry concentration of the magnetic separator during magnetic separation is 5%, and the feed flow rate is 0.05t / h, to obtain high silicon powder A and weak magnetic mineral B;

[0075] S5. The high silicon powder A is subjected to a hot press leaching at 160°C for 6 hours. The leaching solution of the hot press leaching is a mixture of 25% hydrochloric acid, 70% sulfuric acid, 60% phosphoric acid, and 50% nitric acid (the volume ratio of the acid solution is 2:1:2:7), wherein the solid-liquid ratio of the high silicon powder A to the leaching solution is 1:4 t / m 3 , obtaining high-purity quartz powder A and acid leaching filtrate A;

[0076] S6. The high-purity quartz powder A was vacuum roasted at 900°C for 1 hour and then water quenched for 2 minutes; then, the high-purity quartz powder A was subjected to two-stage hot-pressing leaching at 120°C for 6 hours. The leaching solution of the two-stage hot-pressing leaching was a mixture of 15% hydrochloric acid, 30% sulfuric acid, 30% phosphoric acid, and 25% nitric acid (the volume ratio of the acid solution was 4:1:2:1), wherein the solid-liquid ratio of the high-purity quartz powder A to the leaching solution was 1:3 t / m 3 , obtaining high-purity quartz powder B and acid leaching filtrate B above 4N grade;

[0077] S7, performing low-stage magnetic separation on weakly magnetic mineral A and weakly magnetic mineral B at a magnetic induction intensity of 8000G, wherein the slurry concentration of the magnetic separator is 10%, the feed flow rate is 0.5t / h, and iron-rich powder is recovered;

[0078] S8, the leaching solution A, the leaching solution B and the iron-rich powder are mixed and subjected to ultrasonic stirring reaction for 2 hours under the conditions of ultrasonic intensity of 200W, reaction temperature of 50°C and stirring rate of 160r / min to obtain an iron-rich solution and high silicon powder B; wherein the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1:4t / m 3 , wherein the volume of the leaching solution A accounts for 0.9 of the volume of the leaching solution B; high silicon powder B returns to step S5;

[0079] S9, hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder are added to the iron-rich solution obtained in step S8, wherein the amount of hydrogen peroxide is 0.2‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution is 0.5‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1:50kg / m 3 Then adjust the solution pH to 5 and age for 2 hours, filter, dry at 60°C for 4 hours, and calcine at 120°C for 2 hours to obtain a highly dispersed nano-iron oxide product. 2 O 3 The purity reaches 97% and the particle size is 50nm.

[0080] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high value-added recycling method for silicon and iron elements in iron tailings, characterized in that: The method comprises: S1, grinding and dissociating the iron tailings to obtain fine iron tailings; S2, performing mid-stage magnetic separation on the fine iron tailings obtained in step S1 to obtain weakly magnetic mineral A and silicon-rich powder A; S3, adding sodium salt to the silicon-rich powder A obtained in step S2, quenching with water after microwave roasting, and grinding again to obtain fine silicon-rich powder B; S4, subjecting the fine silicon-rich powder B obtained in step S3 to high-segment magnetic separation to obtain high silicon powder A and weak magnetic mineral B; S5, subjecting the high silicon powder A obtained in step S4 to a hot-pressing leaching to obtain high-purity quartz powder A and acid leaching filtrate A; S6, the high-purity quartz powder A obtained in step S5 is vacuum roasted and then water quenched, and then subjected to two-stage hot pressing leaching to obtain high-purity quartz powder B of grade 4N or above and acid leaching filtrate B; S7, performing low-stage magnetic separation on the weakly magnetic mineral A obtained in step S2 and the weakly magnetic mineral B obtained in step S4 to recover iron-rich powder; S8, mixing the leaching solution A obtained in step S5, the leaching solution B obtained in step S6 and the iron-rich powder and subjecting them to ultrasonic reaction to obtain an iron-rich solution and high-silicon powder B, wherein the high-silicon powder B is returned to step S5; S9, adding hydrogen peroxide, sodium dodecylbenzene sulfonate solution and carbon powder to the iron-rich solution obtained in step S8, then adjusting the solution pH to 5-10 and aging for 2-6 hours, filtering, drying and calcining in sequence to obtain a highly dispersed nano-iron oxide product with a Fe2O3 purity of more than 95% and a particle size of 10-100 nm.

2. The high value-added recycling method for silicon and iron elements in iron tailings according to claim 1, characterized in that: The grinding particle size in step S1 is 25-47 μm.

3. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: The magnetic induction intensity of the middle magnetic separation in step S2 is 15000-20000G; the pulp concentration during magnetic separation is 10-35%, and the feed flow rate is 0.1-2t / h.

4. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: In step S3, the sodium salt is one of NaCl, Na2CO3, NaHCO3, Na2SO4 or Na2O2, and the amount of sodium salt added is 2-9‰; the microwave roasting is performed at 600-950°C for 0.5-4h; the water quenching time is 2-7min; and the grinding particle size is 15-25μm.

5. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: The magnetic induction intensity of the high-stage magnetic separation in step S4 is 40000-80000G; the slurry concentration during magnetic separation is 5-20%, and the feed flow rate is 0.05-0.5 t / h.

6. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: In step S5, the temperature of the first hot-pressing leaching is 120-180° C., the time of the first hot-pressing leaching is 4-8 hours, the leaching liquid is a mixture of one or more of 15-30% hydrochloric acid, 50-80% sulfuric acid, 30-70% phosphoric acid, and 30-55% nitric acid, and the solid-liquid ratio of high silicon powder A to the leaching liquid is 1: (2-5) t / m 3 .

7. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: In step S6, the vacuum roasting is performed at 900-1100° C. for 1-6 hours; the water quenching time is 2-7 minutes; the second-stage hot pressing leaching temperature is 120-200° C., the second-stage hot pressing leaching time is 6-10 hours, the leaching liquid is a mixture of one or more of 15-30% hydrochloric acid, 30-50% sulfuric acid, 30-45% phosphoric acid, and 25-50% nitric acid, and the solid-liquid ratio of high-purity quartz powder A to the leaching liquid is 1: (3-6) t / m 3 .

8. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: The magnetic induction intensity of the low-stage magnetic separation in step S7 is 8000-12000G; the pulp concentration during magnetic separation is 10-20%, and the feed flow rate is 0.5-2.5 t / h.

9. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: In step S8, the ultrasonic intensity is 200-400W, the reaction temperature is 50-80°C, the stirring rate is 160-250r / min, and the ultrasonic time is 2-6h; the solid-liquid ratio of the iron-rich powder to the leaching solution A and the leaching solution B is 1: (4-7) t / m 3 .

10. The high value-added recycling method of silicon and iron elements in iron tailings according to claim 1, characterized in that: In step S9, the amount of hydrogen peroxide used is 0.2-0.9‰ of the volume of the iron-rich solution, the amount of sodium dodecylbenzene sulfonate solution used is 0.5-1.2‰ of the volume of the iron-rich solution, and the solid-liquid ratio of carbon powder to iron-rich solution is 1: (50-100) kg / m 3 The drying temperature is 60°C for 4 to 6 hours, the calcination temperature is 120 to 300°C, and the calcination time is 2 to 6 hours.

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