A comprehensive utilization method for high-silicon hematite reverse flotation tailings

Abstract

This invention discloses a method for the comprehensive utilization of high-silicon hematite reverse flotation tailings. Hematite reverse flotation tailings with a TFe grade between 11.0% and 15.0%, SiO2 content >78.0%, and hematite comprising more than 95% of the total iron minerals are processed through a first-stage high-intensity magnetic separation, a first-stage grinding-second-stage high-intensity magnetic separation, and a cationic reverse flotation. The resulting products are: a first-stage high-intensity magnetic scavenging concentrate with a TFe grade >25.0%, suitable for use as an iron correcting agent in cement production; a first-stage high-intensity magnetic scavenging tailings with a SiO2 purity >96.0%, suitable for use as raw material for high-purity quartz sand production; and grinding tailings suitable for use as iron and silicon correcting agents in cement production. This method achieves comprehensive utilization of high-silicon hematite reverse flotation tailings. The method has advantages such as a short process flow, low energy consumption, and high resource utilization rate, and is particularly suitable for the efficient treatment and comprehensive utilization of high-silicon hematite reverse flotation tailings.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of tailings resources, and is particularly suitable for the comprehensive utilization of hematite reverse flotation tailings with a TFe grade between 10.0% and 15.0%, SiO2 content > 78.0%, and hematite accounting for more than 95% of the total iron minerals. Background Technology

[0002] Tailings are solid waste generated during mineral processing, containing low levels of useful components that are currently uneconomical for industrial production. They are the residue remaining after the useful minerals have been extracted. Currently, tailings are primarily disposed of through tailings ponds. However, tailings ponds occupy large amounts of agricultural and forestry land, disrupting the allocation of land resources in the affected areas and causing severe environmental pollution. Statistics show that by 2020, my country's total tailings stockpile exceeded 60 billion tons, making it the largest source of industrial solid waste in terms of both annual generation and stockpile volume.

[0003] Currently, the main utilization methods for tailings in China include backfilling underground mining areas, reprocessing valuable elements, preparing building materials, and land reclamation. Each of these methods has its advantages and disadvantages: tailings reprocessing can save grinding costs, but the recovery rate is low, the return is minimal, and the amount of tailings consumed is small, leaving a large amount of tailings still needing to be processed; backfilling mined-out areas can consume a large amount of tailings, but it consumes a large amount of cement, resulting in high costs and the waste of recoverable valuable components in the tailings; using tailings as raw materials for building materials is low-cost and has a large capacity, but it is limited by factors such as the transportation radius of building materials, excessive levels of hazardous substances, and the lack of relevant supporting regulations and standards, resulting in weak demand, difficulties in selling the produced tailings, and difficulty in large-scale application.

[0004] Among various types of tailings, iron ore tailings have the largest annual production and total stockpile. An article published in the November 2021 issue of *Modern Mining*, titled "Current Status and Significance of Comprehensive Utilization of Iron Tailings Resources," addressed the waste of iron resources and a series of environmental problems caused by the large amount of iron tailings generated during the production of iron concentrate from iron ore. Three solutions were proposed: first, to perform a series of beneficiation processes on the iron tailings to separate valuable components; second, to utilize the iron tailings directly; and third, to process the iron tailings using a new magnetic roasting-magnetic separation process. However, the first method has a low product yield, which is of little significance for the reduction of large-scale solid waste resources such as iron tailings; the second method has the problem that valuable components in iron tailings are not fully extracted and utilized; the third method is only effective when the main form of iron in iron tailings is hematite and limonite, and the magnetization roasting has high energy consumption. The reducing agent used in magnetization roasting is mostly coal powder, which will undoubtedly increase the amount of solid waste generated. It also has the problems of low utilization rate and large amount of new tailings generated.

[0005] There are four main types of iron tailings in my country: high-silicon Anshan iron tailings, high-alumina Maanshan iron tailings, high-calcium and magnesium Handan iron tailings, and low-calcium, magnesium, aluminum, and ferrosilicon tailings. Among them, high-silicon Anshan iron tailings are characterized by large quantity, high silicon content, and few associated elements. Similar types include Benxi Steel Waitoushan, Dagushan, Gongchangling, and Qidashan. The article "Current Status and Development Prospect of Comprehensive Utilization of Anshan-type Iron Tailings" published in February 2023 in "Comprehensive Utilization of Resources in China" gives the following ways to comprehensively utilize high-silicon Anshan-type iron tailings: (1) tailings re-selection, and (2) preparation of new building materials, including building bricks, road base, building insulation materials, high-performance concrete, and building finishing materials. However, both of these methods have problems such as single tailings utilization pathways, low utilization rate, and high cost, and neither can achieve large-scale, low-cost utilization of iron tailings.

[0006] In addition, iron ore tailings in countries such as India and Brazil also contain a large amount of material similar to the high-silicon Anshan iron tailings, which are iron tailings containing only unrecovered iron minerals and are mostly composed of silicon dioxide.

[0007] Therefore, there is an urgent need to develop a comprehensive utilization method for high-silicon iron tailings that has low production costs, large processing capacity, and high tailings utilization rate. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing tailings utilization technologies, such as low tailings utilization rate, high production cost, high energy consumption, and small processing capacity, by providing a comprehensive method for the full utilization of high-silicon hematite reverse flotation tailings.

[0009] To achieve the above-mentioned objectives of this invention, a method for the comprehensive utilization of high-silicon hematite reverse flotation tailings is provided, which is implemented through the following steps:

[0010] S1 section strong magnetic separation:

[0011] Hematite tailings from reverse flotation with a TFe grade between 11.0% and 15.0%, SiO2 content >78.0%, and hematite accounting for more than 95% of the total iron minerals are fed into a first-stage strong magnetic separation operation consisting of a first-stage strong magnetic roughing and a first-stage strong magnetic scavenging. This yields a first-stage strong magnetic rough concentrate with a TFe grade >41.5%, a first-stage strong magnetic scavenging concentrate with a TFe grade >25.0%, and a first-stage strong magnetic scavenging tailings with a TFe grade <1.5% and SiO2 purity >96.0%. The first-stage strong magnetic scavenging concentrate is sold as an iron-based corrective material for cement production, and the first-stage strong magnetic scavenging tailings is sold as a raw material for preparing high-purity quartz sand.

[0012] S2: First-stage grinding - Second-stage high-intensity magnetic separation

[0013] The primary strong magnetic rough concentrate with a TFe grade >41.5% obtained in step S1 is fed into a primary grinding-secondary strong magnetic separation operation to obtain a secondary strong magnetic concentrate with a TFe grade >60.5%, and the secondary strong magnetic separation tailings with a TFe grade <13.5% are discharged.

[0014] S3 cation reverse flotation:

[0015] The secondary strong magnetic concentrate with a TFe grade >60.5% obtained in step S2 is fed into a cationic reverse flotation operation. The cationic reverse flotation operation adopts an open-circuit process of one roughing and two scavenging to obtain an iron concentrate with a TFe grade >64.5%, and the reverse flotation scavenging tailings are discharged. The reverse flotation scavenging tailings and the secondary strong magnetic separation tailings discharged in step S2 are combined into grinding tailings with a TFe grade between 12.0% and 14.5% and a SiO2 content between 72% and 77%. The grinding tailings are sold as iron and silicon corrective agents for cement production.

[0016] Furthermore, in step S1, both the strong magnetic roughing and strong magnetic sweeping adopt the Slon type vertical ring pulsating high gradient strong magnetic separator, with the roughing magnetic field strength being 1.1 to 1.3T and the sweeping magnetic field strength being 1.35 to 1.5T.

[0017] Furthermore, in step S2, the grinding particle size is -0.076mm 85%~92%; the second-stage high-intensity magnetic separation operation adopts the Slon vertical ring pulsating high-gradient high-intensity magnetic separator, with a magnetic field strength of 1.1~1.3T.

[0018] Furthermore, the cationic reverse flotation operation employs a mechanically agitated flotation machine, merging the scavenging concentrate and the roughing concentrate into a total concentrate. The reverse flotation reagent system is as follows: sodium hydroxide is used as a pH adjuster, corn starch as an iron mineral depressant, and dodecylamine as a collector. The dosage of the roughing agent sodium hydroxide is 800–1200 g / t, preferably 900–1100 g / t; the dosage of the depressant corn starch is 400–600 g / t, preferably 450–550 g / t; and the dosage of the collector dodecylamine is 150–300 g / t, preferably 170–230 g / t. No reagents are added during either of the two scavenging stages.

[0019] All the above reagent addition amounts are converted to the amount of dry ore for flotation feed.

[0020] The specific values ​​of the above-mentioned grinding particle size, magnetic field strength, reagent dosage, etc., can all be determined based on the properties of the ore and the results of experimental research.

[0021] Compared with existing technologies, the comprehensive utilization method for high-silicon hematite reverse flotation tailings of the present invention has the following advantages:

[0022] ① Hematite reverse flotation tailings are subjected to high-intensity magnetic separation. After one roughing and one scavenging, three products are obtained. The high-intensity magnetic rough concentrate can be used in subsequent grinding and beneficiation operations to obtain qualified iron concentrate. The high-intensity magnetic scavenging concentrate generally has a TFe grade between 25.0% and 29.0%, which can be used as raw material for preparing cement iron correction material, with a selling price of generally between 150 and 200 yuan / t. The high-intensity magnetic scavenging tailings have a TFe grade of <1.5% and a SiO2 purity of >96.0%, which can be used as raw material for preparing quartz sand.

[0023] ② Only about 20% of the raw material is a strong magnetic rough concentrate, which enters the subsequent grinding operation, greatly reducing energy consumption.

[0024] ③ The cationic reverse flotation adopts an open-circuit flotation process with one rougher and two scavengers. The scavenger concentrate and the rougher concentrate are combined into a total concentrate, which helps to reduce the iron grade of the flotation tailings and greatly improves the recovery rate of the flotation operation.

[0025] ④ This invention realizes the full-scale comprehensive utilization of high-silicon hematite reverse flotation tailings, obtaining three products: iron concentrate, raw material for preparing cement corrective materials, and raw material for preparing quartz sand. The grinding tailings, with a yield of about 10%, have a TFe grade between 12.0% and 14.5%, a SiO2 content between 72% and 77%, and a relatively fine particle size. They can be used to provide silica and iron for cement production, with a selling price of 30 to 60 yuan / t. Ultimately, the full-scale comprehensive utilization of high-silicon hematite reverse flotation tailings has been achieved, yielding unexpected technical results. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the principle and process flow of a method for the comprehensive utilization of high-silicon hematite reverse flotation tailings according to the present invention.

[0027] Figure 2 This is a flow chart illustrating an embodiment of the comprehensive utilization method for high-silicon hematite reverse flotation tailings according to the present invention. Detailed Implementation

[0028] To further describe the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, provides a method for the comprehensive utilization of high-silicon hematite reverse flotation tailings.

[0029] The hematite reverse flotation tailings were taken from an iron ore mine abroad. The results of multi-element chemical analysis of the sample are shown in Table 1, and the results of iron phase analysis of the sample are shown in Table 2.

[0030] Table 1. Results of multi-element chemical analysis (%)

[0031] Laboratory items TFe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO content(%) 11.70 81.27 0.089 0.044 0.09 S P <![CDATA[K2O]]> <![CDATA[Na2O]]> MnO <![CDATA[TiO2]]> <0.005 0.023 <0.005 <0.005 0.022 0.017 <![CDATA[V2O5]]> CuO ZnO <![CDATA[Cr2O3]]> NiO / <0.005 0.005 <0.005 0.01 <0.005 /

[0032] Table 2. Results of iron phase analysis

[0033] Ferrous phase Iron content in the iron phase market share Iron from magnetite 0.24 2.05 Iron from pyrite / / Iron from hematite (brown iron ore) 11.16 95.39 Ferric carbonate 0.10 0.85 Iron in ferrosilicon 0.20 1.71 total 11.70 100.00

[0034] As shown in Tables 1 and 2, the hematite reverse flotation tailings are high in silica and low in iron, very similar to the high-silica Anshan iron tailings. The TFe grade is 11.70%, the SiO2 content is as high as 81.27%, and the content of other impurity elements is very low. The main recoverable useful iron minerals in the ore are hematite and abundant SiO2.

[0035] Depend on Figure 2 The diagram shown illustrates an embodiment of the present invention, a comprehensive utilization method for high-silicon hematite reverse flotation tailings, with a flow chart and accompanying data. Figure 1 As can be seen, the method of the present invention is implemented by the following steps:

[0036] S1 section strong magnetic separation:

[0037] Hematite tailings from reverse flotation with a TFe grade of 11.53% and a SiO2 content of 80.80% are fed into a first-stage magnetic separation process consisting of a first-stage strong magnetic roughing and a first-stage strong magnetic scavenging. This process yields a first-stage strong magnetic rough concentrate with a yield of 21.05% and a TFe grade of 42.51%, a first-stage strong magnetic scavenging concentrate with a yield of 5.70% and a TFe grade of 28.51%, and a first-stage strong magnetic scavenging tailings with a yield of 73.25%, a TFe grade of 1.31%, and a SiO2 content of 96.10%. The first-stage strong magnetic scavenging concentrate is sold as an iron-based corrective material for cement production, and the first-stage strong magnetic scavenging tailings is sold as a raw material for preparing high-purity quartz sand.

[0038] In step S1, both the strong magnetic coarse separation and the strong magnetic sweep separation use the Slon-750 vertical ring pulsating high gradient strong magnetic separator, with a coarse magnetic field strength of 1.2T and a sweep magnetic field strength of 1.4T.

[0039] S2: First-stage grinding - Second-stage high-intensity magnetic separation

[0040] The primary strong magnetic rough concentrate with a TFe grade of 42.51% obtained in step S1 is fed into a primary grinding-secondary strong magnetic separation operation to obtain a secondary strong magnetic concentrate with a yield of 12.87% and a TFe grade of 61.20%, and the secondary strong magnetic separation tailings with a yield of 8.18% and a TFe grade of 13.11% are discharged.

[0041] In step S2, the grinding particle size is -0.076mm 90%, and the grinding is carried out using a Ф240×90 conical ball mill; the second-stage strong magnetic separation operation uses a Slon-750 vertical ring pulsating high gradient strong magnetic separator with a magnetic field strength of 1.2T.

[0042] S3 Cation Reverse Flotation

[0043] The secondary strong magnetic concentrate with a TFe grade of 61.20% obtained in step S2 is fed into a cationic reverse flotation operation. The cationic reverse flotation operation adopts an open-circuit process of one roughing and two scavenging to obtain a high-grade iron concentrate with a yield of 11.72% and a TFe grade of 64.98%, and discharges a reverse flotation scavenging tailings with a yield of 1.15% and a TFe grade of 22.46%. The reverse flotation scavenging tailings and the secondary strong magnetic separation tailings discharged from step S2 are combined to form a grinding tailings with a TFe grade of 14.25%. The SiO2 content in the grinding tailings is in the range of 72% to 77%, which can be sold as an iron and silicon corrective agent for cement production.

[0044] In step S3, the cationic reverse flotation operation uses a mechanically agitated flotation machine, and the scavenging concentrate and rougher concentrate are combined into a total concentrate. The reverse flotation reagent system is as follows: sodium hydroxide is used as a pH adjuster, corn starch as an iron mineral depressant, and dodecylamine as a collector. The dosage of sodium hydroxide as the rougher adjuster is 1000 g / t, the dosage of corn starch as the depressant is 500 g / t, and the dosage of dodecylamine as the collector is 200 g / t. No reagents are added during either of the two scavenging stages.

[0045] All the above reagent addition amounts are converted to the amount of dry ore for flotation feed.

[0046] The specific values ​​of the above-mentioned grinding particle size, magnetic field strength, reagent dosage, etc. can all be adjusted according to the properties of the ore and the results of laboratory tests.

[0047] To verify whether the strong magnetic scavenging tailings obtained in step S1 can be used to prepare high-purity quartz sand, further experimental research was conducted in this embodiment of the invention.

[0048] The tailings from the first-stage strong magnetic scavenging process, with a TFe grade of 1.31% and a SiO2 content of 96.10% obtained in step S1, underwent iron removal using a concentrated desliming-coarsening and two-scavenging anionic reverse flotation open-circuit process. The reverse flotation operation was carried out in a weakly acidic slurry medium with a pH range of 5.0–6.5. GK-68 was used as the iron mineral flotation collector at a dosage of 80–130 g / t. The removed fine mud was directly mixed into the grinding tailings as an iron and silicon correcting agent for cement production. The reverse flotation froth product, rich in iron, can be sold as an iron correcting material for cement production. The bottom of the anionic reverse flotation cell was separated into quartz sand with a SiO2 purity of 98.9%. Quartz sand with a SiO2 purity of 98.9% was concentrated, filtered, and dried. The dried quartz sand was immediately added to an impregnation tank, and hydrochloric acid and hydrofluoric acid in a mass ratio of 5:4 were rapidly added under dry and high-temperature conditions for acid leaching. The acid concentration was 15%. The mixture was stirred at a constant temperature of 30℃ to 100℃ for 3 to 20 hours, and finally a high-purity quartz sand product with a SiO2 purity of >99.9% was obtained. Among them, the high-purity quartz sand product obtained by stirring at a constant temperature of 80℃ for 5 hours had a SiO2 purity as high as 99.95%.

Claims

1. A method for the comprehensive utilization of high-silicon hematite reverse flotation tailings, characterized in that... The following steps are to be taken: S1, a single-stage strong magnetic separation: Hematite tailings from reverse flotation with a TFe grade between 11.0% and 15.0%, SiO2 content >78.0%, and hematite accounting for more than 95% of the total iron minerals are fed into a first-stage strong magnetic separation operation consisting of a first-stage strong magnetic roughing and a first-stage strong magnetic scavenging. This yields a first-stage strong magnetic rough concentrate with a TFe grade >41.5%, a first-stage strong magnetic scavenging concentrate with a TFe grade >25.0%, and a first-stage strong magnetic scavenging tailings with a TFe grade <1.5% and SiO2 purity >96.0%. The first-stage strong magnetic scavenging concentrate is sold as an iron-based corrective material for cement production, and the first-stage strong magnetic scavenging tailings is sold as a raw material for preparing high-purity quartz sand. S2, First-stage grinding - Second-stage high-intensity magnetic separation: The primary strong magnetic rough concentrate with a TFe grade >41.5% obtained in step S1 is fed into a primary grinding-secondary strong magnetic separation operation to obtain a secondary strong magnetic concentrate with a TFe grade >60.5%, and the secondary strong magnetic separation tailings with a TFe grade <13.5% are discharged. S3, Cation Reverse Flotation: The secondary strong magnetic concentrate with a TFe grade >60.5% obtained in step S2 is fed into a cationic reverse flotation operation. The cationic reverse flotation operation adopts an open-circuit process of one roughing and two scavenging to obtain an iron concentrate with a TFe grade >64.5%, and the reverse flotation scavenging tailings are discharged. The reverse flotation scavenging tailings and the secondary strong magnetic separation tailings discharged in step S2 are combined into grinding tailings with a TFe grade between 12.0% and 14.5% and a SiO2 content between 72% and 77%. The grinding tailings are sold as iron and silicon corrective agents for cement production.

2. The method for comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 1, characterized in that: For the tailings obtained in step S1 with a TFe grade <1.5% and SiO2 purity >96.0%, a strong magnetic scavenging process is used to remove iron by concentration and desliming followed by anionic reverse flotation. The removed fine mud is directly mixed into the grinding tailings as an iron and silicon correcting agent for cement production. The reverse flotation operation is carried out in a weakly acidic slurry medium with a slurry pH range of 5.0 to 6.

5. The iron mineral flotation collector used is GK-68, with a dosage of 80 to 130 g / t. The froth product is sold as an iron correcting material for cement production. The bottom of the anionic reverse flotation cell is separated into quartz sand with a SiO2 purity >98.8%.

3. The method for comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 2, characterized in that: The quartz sand with SiO2 purity >98.8% is concentrated, filtered, and dried. The dried quartz sand is then added to an impregnation tank, and sulfuric acid, hydrochloric acid, and / or hydrofluoric acid are rapidly added under high-temperature drying conditions for acid leaching. The acid concentration is 5% to 20%, and the mixture is stirred at a constant temperature of 30°C to 100°C for 3 to 20 hours to finally obtain a high-purity quartz sand product with SiO2 purity >99.9%.

4. The method for comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 3, characterized in that: The acid leaching process uses a mixture of hydrochloric acid and hydrofluoric acid, with a mass ratio of hydrochloric acid to hydrofluoric acid of 5:

4.

5. The method for comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 1, characterized in that: In step S1, both the strong magnetic roughing and strong magnetic scavenging adopt the Slon type vertical ring pulsating high gradient strong magnetic separator, with the roughing magnetic field strength being 1.1~1.3T and the scavenging magnetic field strength being 1.35~1.5T.

6. The method for comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 1, characterized in that: In step S2, the grinding particle size is -0.076mm 85%~92%; the second-stage high-intensity magnetic separation operation adopts the Slon vertical ring pulsating high-gradient high-intensity magnetic separator, with a magnetic field strength of 1.1~1.3T.

7. A method for the comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 1, 2, or 3, characterized in that: The cationic reverse flotation operation uses a mechanically agitated flotation machine, and the scavenging concentrate and roughing concentrate are combined into a total concentrate. The reverse flotation reagent system is as follows: sodium hydroxide is used as a pH adjuster, corn starch is used as an iron mineral depressant, and dodecylamine is used as a collector. The dosage of sodium hydroxide as a roughing adjuster is 800-1200 g / t, the dosage of corn starch as a depressant is 400-600 g / t, and the dosage of dodecylamine as a collector is 150-300 g / t. No reagents are added in either of the two scavenging stages.

8. A method for the comprehensive utilization of high-silicon hematite reverse flotation tailings as described in claim 1, 2, or 3, characterized in that: The dosage of sodium hydroxide as a roughing agent is 900–1100 g / t, the dosage of corn starch as an inhibitor is 450–550 g / t, and the dosage of dodecylamine as a collector is 170–230 g / t. No chemicals are added during either of the two scavenging processes.

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