A new beneficiation combination process for preparing super iron concentrate by using magnetite concentrate

Abstract

The application discloses a beneficiation combined new process for preparing super iron concentrate by using magnetite concentrate, adopts pre-inspection grading-control grading-tower grinding, weak magnetic roughing-weak magnetic cleaning-washing, reverse flotation roughing-reverse flotation scavenging I-reverse flotation scavenging II, thickening magnetic separation I-thickening magnetic separation II-filtration dewatering, finally obtains super iron concentrate with TFe grade being greater than or equal to 72.1% and SiO2 content being less than or equal to 0.1%, and after concentration magnetic separation, pressure filtration, drying and packaging, the super iron concentrate becomes the final product. Tailings of rough and fine magnetic separation operations, tailings of washing operations and tailings of reverse flotation are combined together and sold as common iron concentrate. The application forms a closed-circuit grinding by pre-inspection + control combined grading and tower grinding, so that the magnetite and gangue minerals are fully dissociated, and then the super iron concentrate is obtained through one rough and one fine magnetic separation operation, washing operation and one rough and two scavenging reverse flotation operations, and the application has the advantages of uniform grinding product granularity, simple process flow, stable product quality, low comprehensive energy consumption and the like.

Description

Technical Field

[0001] The present invention relates to a re-selection process for magnetite concentrate, and in particular to a beneficiation and separation process for producing super iron concentrate from magnetite concentrate, which is particularly suitable for TFe grade 66%.

[0002] -68.5% and SiO2-dominant gangue minerals are used to produce super iron concentrate with TFe grade ≥72.0% and SiO2 grade ≤0.1%. Background Art

[0003] Super iron concentrate generally refers to high-grade iron ore with an iron content exceeding 71.5%, an acid-insoluble matter content of less than 1%, and a silica content of less than 0.4%. Super iron concentrate is a fundamental material for the production of products such as powder metallurgy, magnetic materials, and direct-reduced iron (DRI). It is widely used in the production of iron powder for powder metallurgy, ferrite magnetic materials, DRI, sponge iron pellets for direct-rolled steel, and ammonia synthesis catalysts.

[0004] Currently, domestic production of magnetic materials primarily uses red iron oxide as a raw material. As the most in-demand raw material in the ferrite industry, red iron oxide is likely to face varying degrees of supply shortage for an extended period. Therefore, there is an urgent need to develop new raw materials as alternatives or supplements to red iron oxide. Magnetite can be processed into super iron concentrate, which can replace red iron oxide as a fundamental raw material for magnetic materials. Currently, super iron concentrate production processes generally include single magnetic separation, magnetic separation-flotation, gravity separation, fine screening-magnetic separation, and magnetic separation-flotation-leaching. However, while existing super iron concentrate production processes can produce an iron concentrate with an iron grade of approximately 71.5%, the silica content remains high at 0.3%-0.5%. The magnetic separation-flotation-leaching process can reduce the silica content of super iron concentrate to approximately 0.2%, but chemical leaching is costly and has certain environmental impacts, making large-scale production difficult.

[0005] To obtain super-purified iron concentrate with high iron grade and low content of impurities such as silica, the article "Experimental Study on Deep Purification of Super-Pure Iron Concentrate" published in the fourth issue of Metal Mine in 2024 employed a combined sulfuric acid-sodium fluoride treatment and a combined sulfuric acid-sodium hydroxide treatment. These treatments yielded ultra-pure iron concentrate with an iron grade of 72.14% and an iron recovery of 99.67%, with silica contents of 0.24% and 0.22%, respectively. However, both processes suffer from high leaching costs and significant environmental impacts, hindering their large-scale industrial application.

[0006] The part of magnetite mines in Huoqiu region of Anhui has good resource endowment, the raw ore has simple mineral composition, low content of harmful elements such as sulfur, phosphorus and silicon, and good ore dressing property, and the ordinary magnetite concentrate with TFe of 66-68% can be obtained through grinding and single magnetic separation, so that a new development can be provided for the production process of super iron concentrate if the ordinary magnetite concentrate is prepared into super iron concentrate through common physical beneficiation method.

[0007] Therefore, it is necessary to study an economic, reliable, environmentally-friendly and high-quality product beneficiation combination process for preparing ordinary magnetite concentrate into super iron concentrate. SUMMARY

[0008] The purpose of the present application is to solve the technical problems of high silicon dioxide content of 0.3%-0.5% in the super pure iron concentrate obtained by the current physical beneficiation method, high cost and great environmental pollution of the chemical leaching method, and provide a new beneficiation combination process for preparing super iron concentrate from magnetite concentrate, so as to obtain super iron concentrate with TFe grade of 72% or more, SiO2 grade of 0.1% or less and moisture content of 0.5% or less through the whole process of physical beneficiation method.

[0009] In order to achieve the above-mentioned purpose of the present application, the new beneficiation combination process for preparing super iron concentrate from magnetite concentrate adopts the following steps:

[0010] S1 Pre-inspection classification-control classification-tower mill: the magnetite concentrate slurry with particle size of-0.075mm particle size ratio of 60%-75% and TFe grade of 66%-68.5% is fed into pre-inspection classification-control classification operation, and the overflow of control classification operation is discharged; the pre-inspection classification and control classification both use hydrocyclone, and the sand of pre-inspection classification and control classification is fed into the tower mill for fine grinding, and the slurry discharged from fine grinding is returned to the pre-inspection classification operation; the fine particle material which has been single dissociated is directly fed into the next process through pre-inspection classification-control classification, so as to reduce the amount of material fed into the tower mill and avoid over-grinding and mud phenomenon. The tower mill is used for fine grinding in the present application, the tower mill is more than 50% energy-saving compared with horizontal ball mill, has higher efficiency, and the product particle size can be adjusted, intermittent, cyclic and continuous production, and the tower mill also has the characteristics of low noise, small vibration and small area.

[0011] S2 weak magnetic roughing-weak magnetic cleaning-washing: the overflow of control classification operation discharged from S1 is fed into weak magnetic roughing-weak magnetic cleaning-washing operation, and the weak magnetic roughing tailings, weak magnetic cleaning tailings and washing tailings are respectively discharged, and the washing concentrate is obtained;

[0012] S3 reverse flotation roughing - reverse flotation scavenging I - reverse flotation scavenging II: the washed concentrate obtained in step S2 is fed into reverse flotation roughing - reverse flotation scavenging I - reverse flotation scavenging II. The underflow of reverse flotation scavenging II is the reverse flotation concentrate, and the foam from reverse flotation roughing, reverse flotation scavenging I and reverse flotation scavenging II is the reverse flotation tailings.

[0013] S4 Concentrated Magnetic Separation I: The weak magnetic rougher tailings, weak magnetic concentrate tailings, elutriation tailings discharged from step S2 and the reverse flotation tailings discharged from step S3 are combined and fed into concentrated magnetic separation I. The concentrated magnetic separation I tailings are discharged to obtain concentrated magnetic separation I concentrate. The concentrated magnetic separation I concentrate is returned to the concentrator as middlings and filtered before being sold as ordinary magnetite concentrate;

[0014] S5 Concentration Magnetic Separation II - Filtration and Dehydration: The reverse flotation concentrate obtained in step S3 is fed into concentration magnetic separation II, and the concentrated magnetic separation II tailings are discharged; the concentrated magnetic separation II concentrate is fed into filtration and dehydration operation, and finally a super iron concentrate with TFe grade ≥72.1% and SiO2 content ≤0.1% is obtained.

[0015] Concentration magnetic separation I and concentration magnetic separation II have dual effects. They not only improve the concentrate grade and discard gangue tailings, but also greatly increase the concentrate concentration, creating conditions for subsequent filtration operations.

[0016] Preferably, in step S1, the overflow particle size of the pre-checked grading hydrocyclone is preferably in the range of 80% to 85% by mass of the -0.075 mm particle size, and it is best to control the overflow particle size of the grading hydrocyclone to be ≥90% by mass of the -0.075 mm particle size, so as to facilitate subsequent sorting and impurity removal.

[0017] Preferably, the mass concentration of the magnetite concentrate slurry fed into the pre-inspection classification operation in step S1 is 35%-45%. At this mass concentration, the classification efficiency of the hydrocyclone is relatively high.

[0018] Preferably, in step S2, the weak magnetic roughing-weak magnetic concentrating operation adopts a semi-countercurrent double-drum permanent magnetic separator, the roughing magnetic field strength is 0.16-0.20T, and the concentrating field strength is 0.10-0.14T; the washing operation adopts a fully automatic washing magnetic separator. The semi-countercurrent double-drum permanent magnetic separator is a sorting equipment with the integrated functions of roughing and concentrating. It is suitable for the roughing and concentrating operations of fine-grained (less than 0.2 mm) strong magnetic ores. It has a good sorting effect and can obtain higher concentrate quality and metal recovery rate. The fully automatic washing magnetic separator is a device that uses water to wash out iron ore and tailings and separate them, thereby achieving the purpose of improving the grade. The present invention adopts a semi-countercurrent double-drum permanent magnetic separator for roughing and concentrating, respectively, and then further purifies through a fully automatic washing magnetic separator, which can effectively throw out the mixed gangue minerals and significantly improve the concentrate grade.

[0019] Preferably, in step S2, the washing operation is controlled at a rising water volume of 0.6-1.2 m according to the amount of slurry fed and the specifications of the selected automatic washing magnetic separator. 3 / h, by controlling the rising water consumption to control the rising water flow rate, and then control the tailings discharge amount and concentrate grade.

[0020] Preferably, in step S3, dodecylamine is used as a collector in the reverse flotation operation, the amount of the collector used in the reverse flotation roughing operation is 50-70 g / t, the amount of the collector used in the reverse flotation scavenging operation I is 20-28 g / t, and the amount of the collector used in the reverse flotation scavenging operation II is 7-13 g / t. The amounts of all the above reagents added are converted into the amount of dry ore fed to the flotation feed; the mass concentration of the reverse flotation roughing operation is 25%-40%.

[0021] Preferably, in step S4, the concentrated magnetic separation operation adopts a permanent magnetic drum magnetic separator with a magnetic field strength of 0.25-0.30T.

[0022] Preferably, in step S5, the concentration magnetic separation II uses a permanent magnetic drum magnetic separator with a magnetic field strength of 0.20-0.25 T; the filtration and dehydration operation uses a high-pressure membrane filter press with an operation cycle time of 50-70 minutes. The high-pressure membrane filter press is an intermittent pressurized filtration device with good filtration effect and low filter cake moisture content.

[0023] Preferably, it also includes a drying process. The super iron concentrate obtained after filtration and dehydration in step S5 is fed into the drying process. The drying process uses a JAHG series drum dryer to reduce the moisture content of the super iron concentrate to below 0.5%, so as to facilitate transportation and use by downstream application manufacturers.

[0024] Compared with existing technologies, the present invention uses a new combined beneficiation process to prepare super iron concentrate from magnetite concentrate. Through pre-inspection + controlled combined classification and tower milling to form a closed-circuit grinding, the magnetite and gangue minerals are fully dissociated. The super iron concentrate is then obtained through a coarse and fine magnetic separation process, elutriation, and a coarse and two-sweep reverse flotation process. The process has the advantages of uniform grinding product particle size, simple process flow, stable product quality, and low comprehensive energy consumption. Specifically, it has the following innovative and beneficial effects:

[0025] (1) The invented new mineral processing combined process is aimed at the regrinding of ordinary magnetite concentrate. It adopts a combined grading process of pre-inspection grading and controlled grading. The graded sediment is returned to the tower mill for regrinding. This process not only achieves efficient grinding operation but also takes into account accurate grading operation, and the grinding efficiency is significantly improved.

[0026] (2) The invented new combined beneficiation process is based on the characteristics of this type of ordinary magnetite concentrate, which has fine embedded particle size and high grade. It adopts weak magnetic separation, washing operation and reverse flotation operation to form a combined process flow for gradually improving the grade of iron ore concentrate. It uses three different physical beneficiation methods to prepare super iron ore concentrate with TFe grade ≥72% and SiO2 grade ≤0.1%.

[0027] (3) The invented new mineral processing combination process is aimed at the dehydration process of the super iron concentrate produced by reverse flotation. It adopts the process flow of concentrated magnetic separation, filter pressing and drying to reduce the moisture content in a step-by-step manner, making full use of the characteristics of different dehydration processes to achieve efficient dehydration of the product;

[0028] (4) The present invention combines conventional physical beneficiation processes with ordinary magnetite concentrate to prepare super iron concentrate, and high-quality super iron concentrate can be obtained without chemical leaching, which significantly reduces the beneficiation cost and the impact on the environment. The selected middlings are returned to the beneficiation plant for filtration and then sold as ordinary magnetite concentrate, thus achieving efficient utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a new process flow chart of a mineral processing combination for preparing super iron concentrate using magnetite concentrate according to the present invention. DETAILED DESCRIPTION

[0030] To further illustrate the present invention, a new combined beneficiation process for producing super iron concentrate from magnetite concentrate is described in detail below with reference to the accompanying drawings and examples. It should be noted that any modifications, equivalent substitutions, and improvements made within the technical concepts and principles of the present invention are intended to be included within the scope of protection of the present invention.

[0031] In this embodiment, the ordinary magnetite concentrate was produced by a mining company in Huoqiu, Anhui Province. The particle size screening results of the ordinary magnetite concentrate are shown in Table 1, the chemical multi-element analysis results of the ordinary magnetite concentrate are shown in Table 2, and the iron phase analysis results of the ordinary magnetite concentrate are shown in Table 3.

[0032] Table 1 Ordinary magnetite concentrate particle size sieving results

[0033]

[0034] The results of particle size screening in Table 1 show that the coarse particle size of +0.1mm in the original ore accounts for 17.66%, the monomer dissociation degree of the coarse particle size is low, the iron grade is low and the SiO2 content is high; the fine particle size of -0.030mm has the highest iron grade, but it is only 71.06% and the SiO2 content is still as high as 1.32%, indicating that fine grinding and deep selection are necessary to obtain high-quality ultra-pure iron concentrate.

[0035] Table 2 Chemical multi-element analysis results of ordinary magnetite concentrate (%)

[0036] Element Name TFe <![CDATA[SiO2]]> Al2O3 CaO MgO MnO S P content 68.60 4.45 0.189 0.282 0.305 0.052 0.024 0.001 Element Name CuO K2O <![CDATA[Na2O]]> <![CDATA[Cr2O3]]> <![CDATA[V2O5]]> ZnO NiO <![CDATA[TiO2]]> content <0.005 0.011 0.119 <0.005 0.006 0.006 <0.005 0.034

[0037] The multi-element analysis results in Table 2 show that the ore has a total iron grade of 68.60% and an alkali ratio of 0.127, making it an acidic iron concentrate. The main impurity is SiO2, with a content of 4.45%, while other impurities are present at lower levels.

[0038] Table 3 Iron phase analysis results of ordinary magnetite concentrate (%)

[0039] Name of Prime Minister magnetite hematite pyrite Pyrrhotite Iron silicate siderite Total iron Iron grade 67.68 0.59 0.038 0.036 0.19 0.16 68.69 Iron distribution rate 98.52 0.86 0.06 0.05 0.28 0.23 100.00

[0040] The iron phase analysis results in Table 3 show that the main iron mineral in the ore is magnetite, with a content of up to 98.52%, and about 0.86% of hematite. The content of other iron minerals is very small.

[0041] The new combined beneficiation process for preparing super iron concentrate from ordinary magnetite concentrate in the embodiment specifically includes the following processes and steps:

[0042] (1) Ordinary magnetite concentrate adopts tower mill and two-stage hydrocyclones of pre-inspection classification and control classification to form closed-circuit operation. The overflow of control classification hydrocyclone enters the next stage of weak magnetic roughing operation. The sand settling of pre-inspection classification and control classification hydrocyclones is returned to the tower mill. The fineness of pre-inspection classification overflow is controlled at -0.038mm 80%, and the particle size of control classification overflow is controlled at -0.038mm 90%;

[0043] (2) The finely ground slurry enters a coarse and a fine double-drum permanent magnetic separator for magnetic separation. The field strength of the weak magnetic coarse separation is controlled at 0.16T, and the field strength of the weak magnetic fine separation is controlled at 0.12T;

[0044] (3) The concentrate from the weak magnetic concentration operation enters the washing machine for washing operation. The rising water consumption of the washing operation is 0.8m 3 / h;

[0045] (4) The washed underflow concentrate enters the stirring tank and is fully mixed with the reverse flotation reagent before entering the flotation operation. The roughing reverse flotation mass concentration is 30%, the roughing reverse flotation time is 4 minutes, and the two sweeping reverse flotation times are both 3 minutes;

[0046] (5) The flotation concentrate enters the concentration magnetic separation, filtration, drying and packaging to become super iron concentrate. The concentration magnetic separation field strength is 0.2T, the filtration cycle time is 60min, and the moisture content after drying is ≤0.5%;

[0047] (6) After the tailings from the coarse and fine magnetic separation operation, the tailings from the washing operation and the tailings from the reverse flotation operation are combined, a permanent magnetic drum magnetic separator is used as the separation equipment for the concentrated magnetic separation operation, and the magnetic field strength is 0.25T.

[0048] By subjecting the ordinary magnetite concentrate to a combined beneficiation process according to the aforementioned process and steps, a super iron concentrate with a middling as a by-product can be prepared. The super iron concentrate has a TFe grade of ≥72.1%, a SiO2 grade of ≤0.1%, a yield of 33.06%, and a moisture content of ≤0.5%.

[0049] The production line scale is calculated based on processing 151,200 tons of raw ore per year, and can produce 50,000 tons of super iron ore concentrate per year. The middling ore is returned to the beneficiation plant. The new process adopts physical beneficiation technology, which has the characteristics of simple process, convenient operation and stable products. It increases the annual after-tax profit of the enterprise by 8.47 million yuan each year.

Claims

1. A new mineral processing combined process for preparing super iron concentrate from magnetite concentrate, characterized in that Use the following steps to implement: S1 Pre-inspection classification - controlled classification - tower mill: magnetite concentrate slurry with a particle size of -0.075mm, a mass ratio of 60%-75%, and a TFe grade of 66%-68.5% is fed into the pre-inspection classification - controlled classification process, and the overflow of the controlled classification process is discharged; both pre-inspection classification and controlled classification use hydrocyclones, and the grit from the pre-inspection classification and controlled classification is fed into the tower mill for fine grinding, and the slurry discharged from the fine grinding is returned to the pre-inspection classification process; S2 weak magnetic roughing - weak magnetic concentrating - elutriation: The overflow from the controlled classification operation discharged from step S1 is fed into the weak magnetic roughing - weak magnetic concentrating - elutriation operation, and weak magnetic roughing tailings, weak magnetic concentrating tailings, and elutriation tailings are discharged respectively to obtain elutriated concentrate; S3 reverse flotation roughing - reverse flotation scavenging I - reverse flotation scavenging II: the washed concentrate obtained in step S2 is fed into reverse flotation roughing - reverse flotation scavenging I - reverse flotation scavenging II. The underflow of reverse flotation scavenging II is the reverse flotation concentrate, and the foam from reverse flotation roughing, reverse flotation scavenging I and reverse flotation scavenging II is the reverse flotation tailings. S4 Concentrated Magnetic Separation I: The weak magnetic rougher tailings, weak magnetic concentrate tailings, elutriation tailings discharged from step S2 and the reverse flotation tailings discharged from step S3 are combined and fed into concentrated magnetic separation I. The concentrated magnetic separation I tailings are discharged to obtain concentrated magnetic separation I concentrate. The concentrated magnetic separation I concentrate is returned to the concentrator as middlings and filtered before being sold as ordinary magnetite concentrate; S5 Concentration Magnetic Separation II - Filtration and Dehydration: The reverse flotation concentrate obtained in step S3 is fed into concentration magnetic separation II, and the concentrated magnetic separation II tailings are discharged; the concentrated magnetic separation II concentrate is fed into filtration and dehydration operation, and finally a super iron concentrate with TFe grade ≥72.1% and SiO2 content ≤0.1% is obtained.

2. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: In step S1, the overflow particle size of the grading hydrocyclone is pre-checked to be in the range of 80% to 85% by mass of the -0.075 mm particle size, and the overflow particle size of the grading hydrocyclone is controlled to be in the range of ≥90% by mass of the -0.075 mm particle size.

3. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: The mass concentration of the magnetite concentrate slurry fed into the pre-inspection classification operation in step S1 is 35%-45%.

4. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: In step S2, the weak magnetic roughing and weak magnetic cleaning operations adopt a semi-countercurrent double-drum permanent magnetic separator, the roughing magnetic field strength is 0.16-0.20T, and the cleaning field strength is 0.10-0.14T; the washing operation adopts a fully automatic washing magnetic separator.

5. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 4, characterized in that: In step S2, the washing operation is controlled at a rising water volume of 0.6-1.2 m according to the amount of slurry fed and the specifications of the selected automatic washing magnetic separator. 3 / h.

6. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: In step S3, dodecylamine is used as a collector in the reverse flotation operation. The amount of collector used in the reverse flotation roughing operation is 50-70 g / t, the amount of collector used in the reverse flotation scavenging I operation is 20-28 g / t, and the amount of collector used in the reverse flotation scavenging II operation is 7-13 g / t. The addition amounts of all the above reagents are converted into the amount of dry ore fed to the flotation feed. The mass concentration of the reverse flotation roughing operation is 25%-40%.

7. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: In step S4, the concentration magnetic separation operation uses a permanent magnetic drum magnetic separator with a magnetic field strength of 0.25-0.30T.

8. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: In step S5, the concentration magnetic separation II uses a permanent magnetic drum magnetic separator with a magnetic field strength of 0.20-0.25 T; the filtration and dehydration operation uses a high-pressure diaphragm filter press with an operation cycle time of 50-70 minutes.

9. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 1, characterized in that: The method further includes a drying process. The super iron concentrate obtained after filtration and dehydration in step S5 is fed into the drying process to reduce the moisture content of the super iron concentrate to below 0.5%.

10. The new combined beneficiation process for preparing super iron concentrate from magnetite concentrate according to claim 9, characterized in that: The drying process uses JAHG series drum dryer.

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