Magnetic seed induced beneficiation of iron ores

Abstract

The application discloses a kind of magnetic seed induced mineral separation methods of iron ore, comprising the following steps: (1) processing mixed iron ore obtains dry magnetic separation concentrate and dry magnetic separation tailings;(2) dry magnetic separation tailings magnetization roasting obtains artificial magnetite;(3) dry magnetic separation concentrate is mixed with artificial magnetite;(4) the raw ore into mill is sent into one-stage closed-circuit grinding classification system, then enters one-stage low-intensity magnetic separation operation;(5) one-stage low-intensity magnetic rough concentrate is sent into two-stage closed-circuit grinding classification system, then enters two-stage low-intensity magnetic roughing operation;(6) two-stage low-intensity magnetic roughing concentrate is demagnetized after entering two-stage low-intensity magnetic cleaning operation by demagnetizer;(7) two-stage low-intensity magnetic cleaning concentrate is concentrated after demagnetization by demagnetizer, and iron concentrate product is obtained by flotation.The application adds natural magnetite contained in ore into artificial magnetite, which is easy to form magnetic chain with natural magnetite as core to strengthen the magnetic separation recovery of artificial magnetite, and the separation process has high iron recovery rate and high concentrate grade.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mineral processing, and particularly relates to a mineral processing method for iron ore. BACKGROUND

[0002] More than 97% of the iron ore in China is lean ore reserves that need to be processed, among which there are nearly 10 billion tons of siderite, limonite, oolitic hematite and very fine-grained hematite, and the resource amount is huge. At present, the dependence of the Chinese steel industry on imported iron ore is as high as more than 85%, which seriously affects the healthy development of the Chinese steel industry and the economic security of the country. If the huge amount of refractory iron ore resources in China can be reasonably utilized through technological progress, the adverse situation of the steel industry in China relying too much on imports will be greatly alleviated, and the healthy and stable development of the steel industry in China will be beneficial.

[0003] The refractory siderite (limonite) and oolitic hematite have a low theoretical grade, and the concentrate iron grade is difficult to reach more than 60% through conventional physical mineral processing methods. Even if it is purified to close to its theoretical grade, a large amount of gas will be emitted in the sintering process, resulting in the development of pores and loose structure, which seriously affects the sintering strength of the sinter. When used as a mineral mixture, the sintering strength of the sinter will be obviously affected when the proportion of the mineral mixture is more than 7-8%. The only reasonable method for effectively utilizing such complex and refractory iron ore is to use the principle process of magnetizing roasting to make the mineral phase of the ore transform into artificial magnetite, and then using weak magnetic separation + flotation.

[0004] CN103041913A discloses a mineral processing method for artificial magnetite, which specifically includes the following steps: first-stage grinding of artificial magnetite as raw material; weak magnetic separation of the discharge after the first-stage grinding to discard tailings; strong shear stress demagnetization, second-stage grinding of the mineral material after the weak magnetic separation until the artificial magnetite is produced as a single body; weak magnetic separation of the discharge after the second-stage grinding to discard tailings; demagnetization of the mineral material after the weak magnetic separation using a demagnetizer; and flotation of the demagnetized mineral material to obtain iron concentrate. The patent strengthens the demagnetization of artificial magnetite and improves the grade of the final iron concentrate by using flotation, but the weak magnetic separation alone cannot recover part of the iron resources with slightly poor magnetization effect, resulting in a relatively low comprehensive recovery rate.

[0005] The magnetic seed induced magnetic separation technology can greatly improve the recovery of fine artificial magnetite with relatively weak magnetism through weak magnetic separation by adding magnetic seeds to make the weakly magnetic artificial magnetite and the magnetic seeds form a magnetic agglomerate with stronger magnetism through magnetic chain. Therefore, how to combine the advantages of the magnetic seed induced magnetic separation technology, fully and reasonably utilize the characteristics of the existing reverse flotation and magnetic separation process, and further develop a beneficiation process with more practical value, more suitable for the characteristics of artificial magnetite ore, and capable of further improving the grade and recovery rate of artificial magnetite beneficiation products, has a positive significance for the efficient development and utilization of complex and refractory low-grade fine-grained iron ore. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the above background art, and to provide a magnetic seed induced beneficiation method for iron ore, which has the advantages of simple and controllable process operation, high concentrate iron grade, high concentrate iron recovery rate and the like. To solve the above technical problems, the technical solution provided by the present application is:

[0007] A magnetic seed induced beneficiation method for iron ore, comprising the following steps:

[0008] (1) After crushing the mixed iron ore, dry pre-separation is performed to obtain a dry magnetic separation concentrate (rich in natural magnetite) and a dry magnetic separation tailing;

[0009] (2) The dry magnetic separation tailing is subjected to magnetization roasting to obtain artificial magnetite;

[0010] (3) The dry magnetic separation concentrate and the artificial magnetite are mixed to obtain a grinding raw ore;

[0011] (4) The grinding raw ore is fed into a first closed-circuit grinding and classification system, and the grinding and classification product is subjected to a first weak magnetic separation operation to obtain a first weak magnetic rough concentrate and a first weak magnetic tailing;

[0012] (5) The first weak magnetic rough concentrate is fed into a second closed-circuit grinding and classification system, and the grinding and classification product is subjected to a second weak magnetic rough separation operation to obtain a second weak magnetic rough separation concentrate and a second weak magnetic rough separation tailing;

[0013] (6) The second weak magnetic rough separation concentrate is subjected to demagnetization by a demagnetizer and then subjected to a second weak magnetic cleaning operation to obtain a second weak magnetic cleaning concentrate and a second weak magnetic cleaning tailing;

[0014] (7) The second weak magnetic cleaning concentrate is subjected to demagnetization by a demagnetizer and then subjected to concentration, and the concentrated underflow is subjected to a flotation operation to obtain a flotation concentrate and a flotation tailing, and the flotation concentrate is the final iron concentrate product.

[0015] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the mixed iron ore contains magnetite and red ore, and the red ore includes hematite / limonite and / or siderite, wherein the mass content of iron in the magnetite is 1-15%, and the mass content of iron in the red ore is 15-90%.

[0016] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the mass ratio of the dry magnetic separation concentrate and the artificial magnetite is (1-10):100.

[0017] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the first closed-circuit grinding and classification system controls the ore fineness to be 50-80% of -0.075 mm, and the magnetic field strength of the first low-intensity magnetic separation operation is 0.10-0.30 T; the second closed-circuit grinding and classification system controls the ore fineness to be 80-95% of -0.075 mm, and the magnetic field strength of the second low-intensity magnetic roughing operation is 0.10-0.30 T; and the magnetic field strength of the second low-intensity magnetic cleaning operation is 0.10-0.30 T.

[0018] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the demagnetizer adopts a high-field-strength and high-frequency working mode, the high-field-strength is a control field strength ≥79.58 kA / m, and the high frequency is a control oscillation frequency ≥500 Hz. The synergistic effect of the high-field-strength and the high frequency can significantly improve the demagnetization effect of the roasted ore, thereby greatly improving the grinding and classification efficiency and providing a good ore slurry dispersion environment for the magnetic separation of the roasted ore.

[0019] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the flotation operation is reverse flotation, and the reverse flotation includes, in sequence, reverse flotation roughing, cleaning and scavenging, the roughing is performed once or twice, the cleaning is performed once or twice, and the scavenging is performed twice or three times. The flotation operation provides a guarantee for the deep impurity removal of the artificial magnetite and the obtaining of high-quality iron concentrate.

[0020] Preferably, in the above-mentioned magnetic seed induced beneficiation method, during the reverse flotation, the concentration of the flotation slurry is 15-30%, and the temperature of the slurry is 15-35℃.

[0021] Preferably, in the above-mentioned magnetic seed induced beneficiation method, the first low-intensity magnetic tailings, the second low-intensity magnetic roughing tailings, the second low-intensity magnetic cleaning tailings and the flotation tailings are fed into a reprocessing device for tailings reprocessing, the middlings in the reprocessing are returned to the second closed-circuit grinding and classification system, and the tailings in the reprocessing are directly discarded. The flotation operation only needs to further improve the concentrate grade to obtain high-quality iron concentrate, and the control of the final tailings grade to improve the total recovery rate of the separation is completed by the magnetic separation operation, so that the functions of the operations are relatively independent, which helps to simplify the operation process.

[0022] In the above-mentioned magnetic seed induced beneficiation method, preferably, the re-concentration device is a medium magnetic machine or a tailings salvaging machine, and the magnetic field strength of the medium magnetic machine is 0.2-0.6T. The use of the medium magnetic machine or the tailings salvaging machine strengthens the recovery of iron in the tailings of the weak magnetic separation and the flotation operation, and the recovery rate of iron is high. The beneficiation method of the present application enriches the poor intergrowth with insufficient dissociation degree through tailings re-concentration, and then re-enters the second closed-circuit grinding and classification system for re-grinding, so that the grinding fineness of the last grinding can be appropriately coarsened, especially when the particle size of the iron ore is unevenly distributed, the process advantage is more obvious, and the increased grinding load of the last grinding is not large.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] 1. Generally, the hardness of artificial magnetite is less than that of natural magnetite, and the magnetism of artificial magnetite is weaker than that of natural magnetite. The present application separates the natural magnetite already contained in the ore through pre-concentration, so that the magnetite which is a strong magnetic mineral can be avoided from experiencing the invalid process of high-temperature roasting conversion again; and then the natural magnetite is added into the grinding and separation system of artificial magnetite, and in the process of weak magnetic separation, the natural magnetite is easy to form a magnetic chain as a core, so as to strengthen the magnetic separation recovery of artificial magnetite, and the iron recovery rate is high in the separation process, and the concentrate grade is high.

[0025] 2. The main role of the flotation process of the present application is to deeply remove impurities to obtain high-quality iron concentrate, and the waste is completed by the tailings re-concentration operation, and the functions of each operation are relatively independent, so that the process operation is simple and controllable, and the labor intensity of workers is small.

[0026] 3. The present application strengthens the demagnetization of artificial magnetite by using a high-field-strength and high-oscillation-frequency demagnetizer, and strengthens the dispersion of artificial magnetite with high coercivity and gangue minerals, which can significantly improve the demagnetization effect of the roasted ore, provide a good ore slurry dispersion environment for the magnetic separation of the roasted ore, and is beneficial to the separation of iron ore. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0028] Figure 1 The process flow chart of the magnetic seed induced beneficiation method in the embodiments of the present application. DETAILED DESCRIPTION

[0029] For the convenience of understanding the present application, the present application will be described more fully and completely by reference to the drawings accompanying the detailed description and preferred embodiments. However, the present application can be carried out in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these specific embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the application to those skilled in the art.

[0030] Unless otherwise defined, all terms used in the present application, including technical terms and scientific terms, have the same meanings as those generally understood by those skilled in the art. The terms used in the present application are only for the purpose of describing particular embodiments and are not intended to limit the scope of the present application.

[0031] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0032] Example 1

[0033] The main component of iron minerals in the ore processed by a certain beneficiation plant is siderite, followed by limonite and a small amount of magnetite; the gangue minerals are mainly quartz and sericite, followed by a small amount of chlorite. Siderite mineral has good crystallization, and the crystal grains are often self-shaped to semi-self-shaped granular with varying sizes, part of which is irregular, and the embedded particle size is generally between 0.02-0.3mm, and the fine ones can be less than 0.01mm, and occasionally individual coarse particles can reach more than 0.5mm. Siderite is often intergrown with gangue in a disseminated manner, and its characteristics are great change in shape, varying particle size, uneven distribution, and local directional arrangement. The internal part of limonite mineral often has pores and wrapped fine impurity minerals. Overall, there are two forms of limonite: one is mainly intergrown with gangue minerals such as quartz in a sparse to moderately dense disseminated manner, and the particle size is generally between 0.01-0.15mm; the other is part of the limonite distributed in a relatively dense lump and colloidal aggregate, and most of the aggregates often have micro-fine quartz, sericite and other gangues embedded inside, and a small amount of internal pyrite residues can be seen. The composition of part of the limonite in the lump has obvious differences, and the size of the aggregate is generally between 0.2-1.0mm.

[0034] As shown in FIG. 1, a magnetic seed induced beneficiation method of iron ore includes the following steps: Figure 1

[0035] (1) Dry pre-selection: after the raw ore is crushed, the dry pre-selection is carried out by a magnetic pulley with a field strength of 0.3T to obtain a dry magnetic separation concentrate rich in natural magnetite and a dry magnetic separation tailing;

[0036] (2) Magnetic roasting: the dry magnetic separation tailing is subjected to magnetic roasting to obtain a roasted ore product (i.e. artificial magnetite), wherein the magnetic roasting temperature is 650℃, and the roasting atmosphere is a neutral atmosphere;

[0037] (3) Ore blending and mixing: the dry magnetic separation concentrate and the roasted ore product are blended at a mass ratio of 5:95 to obtain a raw ore for grinding after blending and mixing;​

[0038] (4) One-stage grinding-magnetic separation: the raw ore is sent to a one-stage closed-circuit grinding classification system, and after grinding to about 55% of -0.075 mm, it is sent to one-stage low-intensity magnetic separation to obtain one-stage low-intensity magnetic rough concentrate and one-stage low-intensity magnetic tailings;

[0039] (5) Two-stage grinding-magnetic separation: the one-stage low-intensity magnetic rough concentrate is sent to a two-stage closed-circuit grinding classification system, and after grinding to about 80% of -0.075 mm, it is sent to two-stage low-intensity magnetic rough separation to obtain two-stage low-intensity magnetic rough separation concentrate and two-stage low-intensity magnetic rough separation tailings;

[0040] (6) The two-stage low-intensity magnetic rough separation concentrate is demagnetized by a demagnetizer and then sent to two-stage low-intensity magnetic separation to obtain two-stage low-intensity magnetic separation concentrate and two-stage low-intensity magnetic separation tailings, wherein the demagnetizing field strength of the demagnetizer is 150 kA / m, and the oscillation frequency is 800 Hz;

[0041] (7) Reverse flotation: the two-stage low-intensity magnetic separation concentrate is demagnetized by a demagnetizer and then concentrated, and the concentrated underflow is sent to one-rough-two-clean-one-scan reverse flotation to obtain flotation concentrate and flotation tailings, and the flotation concentrate is the final iron concentrate product; wherein the demagnetizing field strength of the demagnetizer is 150 kA / m, and the oscillation frequency is 800 Hz;

[0042] (8) Tailings reprocessing: the one-stage low-intensity magnetic tailings, two-stage low-intensity magnetic rough separation tailings, two-stage low-intensity magnetic separation tailings, and flotation tailings produced in steps (4), (5), (6), and (7) are reprocessed together, and the middlings of the reprocessing are returned to the two-stage grinding classification system for regrinding and then reprocessed, and the tailings of the reprocessing are directly discarded.

[0043] By using the method of the embodiment, when the grade of the raw ore TFe is about 25%, the final iron concentrate yield is 33.14%, the grade of the iron concentrate TFe is 64.85%, and the iron recovery rate is 85.86%.

[0044] Comparative Example 1:

[0045] The comparative example is different from Example 1 in that no dry magnetic separation concentrate is added in step (3), and other conditions are the same as in Example 1.

[0046] By using the conventional magnetization roasting-magnetic separation-flotation process in the comparative example, only the separation indexes of iron concentrate yield 29.14%, iron concentrate grade TFe 63.87%, and iron recovery rate 78.64% can be obtained.

[0047] Example 2:

[0048] The composition of the ore is relatively simple, the iron ore is mainly siderite, followed by limonite; the metal sulfide is pyrite, but the distribution is very sporadic; the content of gangue minerals is relatively high, which is quartz and muscovite, followed by calcite and a small amount of chlorite, and other trace minerals are also seen, such as actinolite, rutile, apatite, tourmaline and zircon. Siderite is euhedral, hypautomorphic granular, part is irregular, fine is less than 0.05mm, coarse is greater than 1.5mm, generally 0.1-0.8mm, often closely inlaid to form dense clumps, the aggregate particle size is mostly between 0.3-6.0mm, and individual coarse ones can even reach about 8.0mm. Limonite is filled and replaced along the cleavage, intergranular, fissure and edge of siderite in the form of micro-fine vein, network vein, dendritic or irregular. The gangue in the ore is mainly quartz and muscovite, followed by calcite and chlorite. Among them, quartz is anhedral granular, often scattered in the form of disseminated along the edge or intergranular of siderite, locally aggregated into irregular clumps, the crystal particle size is 0.02-0.4mm, and the aggregate particle size is 0.5-1.5mm. The content of muscovite is lower than that of quartz, and the directional arrangement characteristics are more obvious, often in the form of scattered disseminated along the edge and intergranular of siderite, occasionally as inclusions distributed in siderite, the sheet width is 0.02-0.15mm, and the aggregate particle size of coarse ones can reach about 0.4mm.

[0049] The content of magnetite in the raw ore of the test is low, and it does not need to be treated by dry pre-separation operation.

[0050] A kind of magnetic seed induction beneficiation method of iron ore, comprising the following steps:

[0051] (1) magnetization roasting: the raw ore powder crushed to <1mm is subjected to magnetization roasting under the condition of neutral atmosphere and magnetization roasting temperature of 650℃ by using flash magnetization roasting process, to obtain a roasted ore product (i.e. artificial magnetite);

[0052] (2) ore blending: the natural magnetite purchased and the artificial magnetite are blended in a mass ratio of 3:97, and the mixed ore is obtained after blending and mixing;

[0053] (3) one-stage grinding-magnetic separation: the mixed ore is sent to a one-stage closed-circuit grinding classification system, and after grinding to about 70% of -0.075mm, it is subjected to one-stage low-intensity magnetic separation to obtain one-stage low-intensity magnetic rough concentrate and one-stage low-intensity magnetic tailings;

[0054] (4) two-stage grinding-magnetic separation: the one-stage low-intensity magnetic rough concentrate is fed into a two-stage closed-circuit grinding classification system, and after grinding to about 85% of -0.075mm, it is subjected to two-stage low-intensity magnetic rough separation to obtain two-stage low-intensity magnetic rough separation concentrate and two-stage low-intensity magnetic rough separation tailings;

[0055] (5) The two-stage low-intensity magnetic rough concentrate is introduced into the two-stage low-intensity magnetic separation operation after demagnetization by a demagnetizer, to obtain a two-stage low-intensity magnetic separation concentrate and a two-stage low-intensity magnetic separation tailings, wherein the demagnetization field strength of the demagnetizer is 150 kA / m, and the oscillation frequency is 800 Hz;

[0056] (6) Reverse flotation: the two-stage low-intensity magnetic separation concentrate is concentrated after demagnetization by a demagnetizer, and the concentrated underflow is introduced into the one-roughing-one-cleaning-one-scavenging reverse flotation operation, to obtain a flotation concentrate and a flotation tailings, and the flotation concentrate is the final iron concentrate product; wherein the demagnetization field strength of the demagnetizer is 150 kA / m, and the oscillation frequency is 800 Hz;

[0057] (7) Tailings reselection: the one-stage low-intensity tailings, the two-stage low-intensity roughing tailings, the two-stage low-intensity magnetic separation tailings and the flotation scavenging tailings produced in the above steps (3), (4), (5) and (6) are reselected together, and the middlings of the reselection are returned to the two-stage grinding and classification system for regrinding and then introduced into the system for separation again, and the reselection tailings are directly discarded.

[0058] By using the method of the embodiment, under the condition that the grade of the raw ore is about 33% TFe, the final iron concentrate yield is 47.64%, the grade of the iron concentrate is 64.21% TFe, and the iron recovery rate is 89.70%.

Claims

1. A method of magnetic seed induced beneficiation of iron ores, characterized in that, The method comprises the following steps: (1) crushing the mixed iron ore and then performing dry pre-separation to obtain dry magnetic separation concentrate and dry magnetic separation tailings; the dry magnetic separation concentrate contains natural magnetite; (2) performing magnetization roasting on the dry magnetic separation tailings to obtain artificial magnetite; (3) uniformly mixing the dry magnetic separation concentrate and the artificial magnetite to obtain the ore for grinding; (4) feeding the ore for grinding into a first closed-circuit grinding and classification system, and feeding the grinding and classification product into a first low-intensity magnetic separation operation to obtain first low-intensity magnetic rough concentrate and first low-intensity magnetic tailings; (5) feeding the first low-intensity magnetic rough concentrate into a second closed-circuit grinding and classification system, and feeding the grinding and classification product into a second low-intensity magnetic rough separation operation to obtain second low-intensity magnetic rough separation concentrate and second low-intensity magnetic rough separation tailings; (6) feeding the second low-intensity magnetic rough separation concentrate into a demagnetizer to be demagnetized, and then feeding the demagnetized product into a second low-intensity magnetic cleaning operation to obtain second low-intensity magnetic cleaning concentrate and second low-intensity magnetic cleaning tailings; (7) feeding the second low-intensity magnetic cleaning concentrate into the demagnetizer to be demagnetized, and then performing concentration on the demagnetized product, feeding the concentrated underflow into a flotation operation to obtain flotation concentrate and flotation tailings, and the flotation concentrate being the final iron concentrate product. The mixed iron ore contains magnetite and red ore, and the red ore includes hematite / limonite and / or siderite, wherein the mass content of iron in the magnetite is 1-15%, and the mass content of iron in the red ore is 15-90%; the mixed iron ore contains natural magnetite. The mass ratio of the dry magnetic separation concentrate to the artificial magnetite is (1-10):

100.

2. The magnetic seed-induced beneficiation process of claim 1, wherein, The first closed-circuit grinding and classification system controls the ore fineness to be 50-80% of -0.075 mm, and the magnetic field strength of the first low-intensity magnetic separation operation is 0.10-0.30 T; the second closed-circuit grinding and classification system controls the ore fineness to be 80-95% of -0.075 mm, the magnetic field strength of the second low-intensity magnetic rough separation operation is 0.10-0.30 T, and the magnetic field strength of the second low-intensity magnetic cleaning operation is 0.10-0.30 T.

3. The magnetic seed-induced beneficiation method according to claim 1 or 2, characterized in that, The demagnetizer adopts a high-field-strength and high-frequency working mode, the high-field-strength is a control field strength ≥79.58 kA / m, and the high frequency is a control oscillation frequency ≥500 Hz.

4. The magnetic seed-induced beneficiation process according to claim 1 or 2, characterized in that, The flotation operation is reverse flotation, and the reverse flotation comprises, in sequence, reverse flotation roughing, cleaning and scavenging, the roughing is performed once or twice, the cleaning is performed once or twice, and the scavenging is performed twice or three times.

5. The magnetic seed-induced beneficiation process of claim 4, wherein, During the reverse flotation, the concentration of the flotation slurry is 15-30%, and the slurry temperature is 15-35℃.

6. The magnetic seed-induced beneficiation process according to claim 1 or 2, characterized in that, The first low-intensity magnetic tailings, the second low-intensity magnetic rough separation tailings, the second low-intensity magnetic cleaning tailings and the flotation tailings are fed into a reprocessing device to be reprocessed, the reprocessed middlings are returned to the second closed-circuit grinding and classification system, and the reprocessed tailings are directly discarded.

7. The magnetic seed-induced beneficiation process of claim 6, wherein, The reprocessing device is a medium-intensity magnetic separator or a tailings salvaging machine, and the magnetic field strength of the medium-intensity magnetic separator is 0.2-0.6 T.

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