A method for recovering iron and rare earth elements from iron-bearing rare earth polymetallic ores through hydrogen-based mineral phase conversion.

Abstract

A method for recovering iron and rare earth in iron-containing rare earth polymetallic ores by hydrogen-based ore phase conversion belongs to the field of beneficiation and comprehensive resource recovery. The method is: dry pulverizing the raw ore, and then subjecting the ore powder to hydrogen-based ore phase conversion, the conversion process mainly includes a preheating oxidation decomposition process, a hydrogen-based ore phase conversion process and a cooling process; the hydrogen-based ore phase conversion product is subjected to ore grinding, and the mass percentage of the grinding product fineness is controlled at 80-95wt% of ‑74μm; the grinding product is subjected to weak magnetic separation, and the magnetic field strength is 2300-4500Oe to obtain magnetic iron concentrate and magnetic tailings; the magnetic iron concentrate is subjected to a "one coarse and one fine" closed-circuit reverse flotation defluorination operation to obtain iron concentrate and flotation iron tailings; the magnetic tailings are subjected to a "one coarse and three fine" closed-circuit positive flotation operation to select rare earths, and rare earth flotation concentrate and fluorite-rich tailings are obtained. The method can achieve the effective separation of iron and rare earth in iron-containing rare earth polymetallic ores and improve the sorting index.

Description

Technical Field

[0001] The invention relates to the fields of beneficiation and comprehensive resource recovery, and in particular to a method for recovering iron and rare earth from iron-containing rare earth polymetallic ores through hydrogen-based ore phase conversion. Background Art

[0002] The Bayan Obo Mine is a rare large-scale polymetallic symbiotic deposit of iron, rare earth, fluorite, etc. in the world. Due to its complex mineral composition, close symbiotic relationship, fine and uneven mineral distribution, small difference in selectivity between useful minerals and gangue minerals, and many available valuable components, the efficient sorting and comprehensive utilization of the mine has always been a difficult problem in the mineral processing industry. The Bayan Obo medium-poor oxidized ore is an ore that was piled up as rock waste when Baotou Steel used rich ore to directly enter the blast furnace for smelting in the 1960s. It is mainly fluorite-type medium-poor iron ore. The rare earth grade (REO) in the mine is about 5.5%, and the fluorite content is more than 20%. The current stockpile is large and the stacking time is long.

[0003] The main reasons why medium-poor oxidized ores are difficult to select are low iron grade, complex mineral composition, and fine embedded particle size. Due to long-term stacking, the ore has been weathered, soaked in water, and oxidized for a long time, and its surface properties have changed significantly, increasing the difficulty of recovery. In addition, the separation properties of many minerals, such as floatability, specific gravity, and specific magnetic susceptibility, are relatively close, so it is difficult to achieve effective recovery from the perspective of gravity separation, magnetic separation, or flotation.

[0004] Relevant institutions and researchers have successively investigated the process flow of Bayan Obo oxide ore using gravity separation, strong magnetic separation, reverse flotation, roasting-magnetic separation, roasting-flotation and other processes. Due to the fine particle size of the main mineral components in the medium-poor oxide ore, it is difficult to obtain good separation indicators by gravity separation; although the strong magnetic separation method can obtain some iron concentrate, the iron recovery rate is low. For such difficult-to-select poor oxide ores, roasting-magnetic separation or roasting-magnetic separation-flotation methods can obtain TFe grades greater than 60% to 65% and recovery rates greater than 60% to 70%, but such methods can only obtain a single iron concentrate product, and fail to effectively recover valuable minerals such as associated rare earths and fluorite, and the comprehensive utilization rate is low.

[0005] Patent CN202010307653.X uses flotation to recover rare earths and fluorite from medium-lean oxide ores, and uses chlorination-reduction roasting and magnetic separation to recover reduced iron and niobium from tailings, achieving good recovery results. However, the process flow is relatively complicated, and the required roasting temperature is relatively high (900-1000°C), which consumes a lot of energy. In addition, the chlorination roasting method will produce a large amount of harmful flue gas, and the use of coke as a reducing agent also has problems such as large carbon emissions. Summary of the invention

[0006] In view of the problems of difficulty in sorting medium-lean oxide ores, poor comprehensive recovery effect of multi-component minerals, low sorting indicators, etc., the present invention aims to provide a method for recovering iron and rare earths in iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation, which can achieve effective separation of iron and rare earths in iron-containing rare earth polymetallic ores and improve sorting indicators.

[0007] The method for recovering iron and rare earth from iron-containing rare earth polymetallic ore by hydrogen-based ore phase conversion of the present invention comprises the following steps:

[0008] (1) Dry pulverizing of raw ore:

[0009] Crushing iron-containing rare earth polymetallic ore into ≤3 mm to obtain ore powder;

[0010] (2) Hydrogen-based mineral phase transformation

[0011] The mineral powder is subjected to hydrogen-based mineral phase transformation, and the transformation process mainly includes a preheating oxidation decomposition process, a hydrogen-based mineral phase transformation process and a cooling process;

[0012] The process of hydrogen-based mineral phase transformation of the mineral powder is specifically as follows: drying and preheating the mineral powder, and then oxidatively decomposing the mineral powder to obtain decomposed mineral powder; performing hydrogen-based mineral phase transformation on the decomposed mineral powder in a reducing atmosphere; cooling the converted mineral powder, and discharging it after cooling to 150° C. to 200° C., to obtain a hydrogen-based mineral phase transformation product;

[0013] In the process of hydrogen-based mineral phase transformation, the specific reaction equations of the main minerals involved are:

[0014] Fe2O3·nH2O→α-Fe2O3+nH2O (1)

[0015] 4FeCO3+O2→2α-Fe2O3+4CO2 (2)

[0016] 4Fe3O4+O2→6α-Fe2O3 (3)

[0017] CeCO3F→CeOF+CO2 (4)

[0018] 3Fe2O3+CO→2Fe3O4+CO2 (5)

[0019] 3Fe2O3+H2→2Fe3O4+H2O (6)

[0020] 2CeOF+H2O→Ce2O3+2HF (7)

[0021] 4Fe3O4+O2→6γ-Fe2O3 (8)

[0022] 14 / 3Ce2O3+O2→4 / 3Ce7O 12 (9)

[0023] Among them, formulas (1) to (4) are the main reactions occurring during the preheating oxidation decomposition process; formulas (5) to (7) are the main reactions occurring during the hydrogen-based mineral phase transformation process; formulas (8) and (9) are the main reactions occurring during the cooling process; monazite and fluorite do not participate in the reaction during the mineral phase transformation process.

[0024] (3) Grinding-magnetic separation

[0025] Grinding the hydrogen-based mineral phase transformation product, wherein the grinding product fineness is controlled at -74 μm, accounting for 80 to 95 wt% by mass;

[0026] The grinding products are subjected to weak magnetic separation with a magnetic field strength of 2300-4500Oe to obtain magnetically separated iron ore concentrate and magnetically separated tailings;

[0027] (4) Reverse flotation defluorination

[0028] The magnetically separated iron concentrate is subjected to a "one coarse and one fine" closed-circuit reverse flotation defluorination operation to obtain iron concentrate and flotation iron tailings;

[0029] (5) Rare earth flotation

[0030] The magnetic separation tailings are subjected to a "one coarse and three fine" closed-circuit direct flotation operation to select rare earths, and rare earth flotation concentrate and fluorite-rich tailings are obtained.

[0031] Furthermore, in step (1), the main mineral contents in the iron-containing rare earth polymetallic ore are: TFe 26.0% to 31.0%, REO 4.2% to 6.5%, and CaF2 17.3% to 26.0%.

[0032] The particle size of the iron-containing rare earth polymetallic ore is preferably 5 to 50 mm.

[0033] Furthermore, in step (2), the preheating oxidation decomposition process has a drying preheating temperature of 150 to 200° C., an oxidation decomposition temperature of 450 to 750° C., and an oxidation decomposition residence time of 2 to 10 min.

[0034] Furthermore, in step (2), the temperature of the hydrogen-based mineral phase transformation process is 430-550° C., and the residence time of the hydrogen-based mineral phase transformation process is 20-90 min.

[0035] Furthermore, in step (2), the reducing atmosphere adopts a mixed reducing gas of one or more of H2, CO, natural gas, coal gas, and methane, wherein the mixed reducing gas is preferably H2 and CO, or H2 and coal gas, and preferably, the volume percentage of H2 in the mixed reducing gas is ≥55%.

[0036] Furthermore, in step (4), a reverse flotation inhibitor and a reverse flotation collector are added in sequence during the defluorination reverse flotation process, the reverse flotation temperature is 20-40° C., and the mass concentration of the reverse flotation pulp is 30-40 wt %.

[0037] Wherein, the reverse flotation depressant is water glass, and the dosage is 0.3-1.5 kg / t; the reverse flotation collector is sodium oleate, and the dosage is 0.04-1.2 kg / t.

[0038] Furthermore, in step (5), a positive flotation depressant, a positive flotation collector and a frother are added in sequence during the rare earth flotation process, the positive flotation temperature is 40-70° C., and the positive flotation pulp concentration is 35-55wt%.

[0039] Wherein, the positive flotation depressant is water glass, the dosage is 0.1-4 kg / t, the positive flotation collector is hydroxamic acid, the dosage is 0.15-5.5 kg / t, and the frother is 2# oil, the dosage is 0.01-0.1 kg / t.

[0040] In the iron concentrate obtained by the method of the present invention, the TFe grade is 63.2% to 65.9%, and the TFe recovery rate is 80.5% to 92.0%.

[0041] The rare earth concentrate obtained by the method of the present invention has a REO grade of 59.6% to 68.5% and a recovery rate of 55.2% to 65.5%.

[0042] The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores through hydrogen-based ore phase conversion of the present invention has the following beneficial effects compared with the existing method for treating iron-containing rare earth polymetallic ores:

[0043] (1) Compared with conventional mineral processing methods, the present invention realizes the directional conversion - magnetic separation - flotation quality improvement of weakly magnetic iron minerals in medium-lean ores through hydrogen-based mineral phase transformation technology, so that the difficult-to-select iron-containing components can be effectively enriched and recovered.

[0044] (2) Compared with the traditional carbon-based magnetization roasting method, the hydrogen-based mineral phase transformation technology adopted in the present invention can reduce CO2 emissions while avoiding carbon adsorption on the mineral surface caused by incomplete combustion, thereby reducing the floatability of rare earth and fluorite components and ensuring the recovery effect of subsequent flotation operations.

[0045] (3) The present invention realizes the comprehensive recovery of valuable components in lean oxide ores, and can effectively enrich both iron and rare earths. The TFe grade of iron concentrate can reach 63.2% to 65.5%, and the TFe recovery rate is 80.5% to 92.0%; the REO grade of rare earth concentrate can reach 59.6% to 68.5%, and the recovery rate is 55.2% to 65.5%. In addition, the fluorite-rich tailings obtained by flotation can also be recovered by flotation enrichment, and the product has high added value and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a specific process flow chart of the method for recovering iron and rare earth from iron-containing rare earth polymetallic ores through hydrogen-based ore phase transformation. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings and examples. The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described can be obtained from commercial channels unless otherwise specified, and the steps described are not limitations on the reaction sequence. After understanding the essence of the invention, the steps can be adjusted.

[0048] The process flow chart of the method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase conversion is shown in Figure 1 .

[0049] Example 1

[0050] Treatment object: Lean oxide ore from a dump in Baiyunebo, with an iron (TFe) grade of 28%, rare earth oxide (REO) grade of 5.5%, and fluorite grade of 22%. The main useful minerals are hematite, limonite, magnetite, fluorocarbon cerium ore, monazite and fluorite, and the main gangue minerals are dolomite, quartz, calcite and apatite.

[0051] (1) Dry pulverizing of raw ore:

[0052] A high pressure roller mill is used to crush the ore with a particle size range of 5 to 50 mm to less than 1 mm to obtain ore powder;

[0053] (2) Hydrogen-based mineral phase transformation

[0054] The obtained mineral powder is sent to the hydrogen-based mineral phase conversion device to complete preheating oxidation decomposition, combined water removal, and hydrogen-based mineral phase conversion, wherein the preheating oxidation decomposition system temperature is 600°C, the material residence time is 8 minutes, and the hydrogen-based mineral phase conversion device is introduced into the H2 and CO mixed gas with a dosage ratio of 3:2, the conversion temperature is 450°C, and the material residence time is 60 minutes. After the conversion is completed, the material temperature drops to 160°C to obtain the mineral phase conversion product;

[0055] (3) Grinding-magnetic separation

[0056] The obtained mineral phase transformation product is subjected to ore grinding treatment, and the content of -74μm accounts for 95wt%; then the ore grinding product is subjected to weak magnetic separation, and the magnetic field strength is 3500Oe to obtain magnetic separation iron ore concentrate and magnetic separation tailings;

[0057] (4) Reverse flotation defluorination

[0058] The weak magnetic iron concentrate is subjected to a "one rough and one fine" closed-circuit reverse flotation defluorination operation. The flotation pulp concentration is controlled at 35wt%, and the flotation temperature is 40°C. During the roughing process, 1.25kg / t of water glass and 0.3kg / t of sodium oleate are added in sequence, and then the roughing concentrate is subjected to a fine concentration. The steps of adding chemicals are the same as those for the roughing, and the dosage of chemicals is 0.5kg / t of water glass and 0.1kg / t of sodium oleate. The roughing tailings are used as flotation tailings, and the fine tailings are returned to the previous level.

[0059] After one roughing and one cleaning, closed-circuit reverse flotation and defluorination, iron concentrate and flotation iron tailings were obtained. The TFe grade in the iron concentrate was 65.18%, the TFe recovery rate was 84.07%, the F grade was 0.33%, and the F recovery rate was 7.47%.

[0060] (5) Rare earth flotation

[0061] The tailings of weak magnetic separation are subjected to the closed-circuit positive flotation of rare earths in "one rough and three fines". The concentration of roughing pulp is controlled to be 50wt%, and the flotation temperature is 50℃. During the roughing process, 1.8kg / t of water glass, 4.2kg / t of hydroxamic acid, and 0.08kg / t of 2# oil are added in sequence. The roughing concentrate is subjected to three-level concentrating. The concentrating middlings are returned to the previous level in sequence, and the concentrates enter the next level. The roughing tailings are used as fluorite-rich concentrates. The dosing steps are the same as those of the roughing, and the dosage of the reagents is 0.5kg / t of water glass and 0.7kg / t of hydroxamic acid for concentrating I, 0.35kg / t of water glass and 0.5kg / t of hydroxamic acid for concentrating II, and 0.15kg / t of water glass and 0.20kg / t of hydroxamic acid for concentrating III.

[0062] After a closed-circuit flotation process of one roughing and three cleanings, rare earth flotation concentrate and fluorite-rich tailings are obtained. The REO grade in the rare earth flotation concentrate is 61.56%, the REO recovery rate is 61.79%, and the CaF2 grade in the fluorite-rich tailings is 55.23%. The rare earth tailings can be further recovered by flotation.

[0063] Example 2

[0064] The method is the same as in Example 1, except that:

[0065] (1) The iron (TFe) grade of the raw ore is 31%, the rare earth oxide (REO) grade is 4.2%, and the fluorite grade is 20%;

[0066] (2) The preheating oxidation decomposition temperature of the mineral powder is 650°C, and the material residence time is 10 min; the hydrogen-based mineral phase transformation temperature is 500°C, and the material residence time is 50 min; the reducing atmosphere is CO;

[0067] (3) The mineral phase transformation product is ground to -74 μm and the content is 92 wt%; the weak magnetic separation magnetic field strength is 4000 Oe;

[0068] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.1 kg / t, and the amount of sodium oleate used in the cleaning process is 0.3 kg / t, and the amount of sodium oleate used in the cleaning process is 0.05 kg / t;

[0069] (5) In the rare earth flotation operation, the pulp concentration is 45wt%, the flotation temperature is 45°C, the roughing water glass dosage is 2.0kg / t, the hydroxamic acid is 4.5kg / t, and the 2# oil is 0.1kg / t; the concentrating I water glass dosage is 0.8kg / t, and the hydroxamic acid is 1.0kg / t; the concentrating II water glass dosage is 0.4kg / t, and the hydroxamic acid is 0.6kg / t; the concentrating III water glass dosage is 0.2kg / t, and the hydroxamic acid is 0.3kg / t;

[0070] (6) The TFe grade of the obtained iron concentrate is 64.66%, the TFe recovery rate is 89.52%, the F grade is 0.37%, and the F recovery rate is 9.62%. The REO grade of the rare earth flotation concentrate is 60.02%, and the REO recovery rate is 63.21%. The CaF2 grade of the fluorite-rich tailings is 53.10%. The rare earth tailings can be further recovered from fluorite by flotation.

[0071] Example 3

[0072] The method is the same as in Example 1, except that:

[0073] (1) The iron (TFe) grade in the raw ore is 27.42%, the rare earth oxide (REO) grade is 6.21%, and the fluorite grade is 21.33%;

[0074] (2) The preheating oxidation decomposition temperature of the mineral powder is 550°C, and the material residence time is 6 minutes; the hydrogen-based mineral phase transformation temperature is 460°C, and the material residence time is 80 minutes; the ratio of H2 to CO in the mixed reducing gas is 3:1;

[0075] (3) The mineral phase transformation product is ground to -74 μm and the content is 89 wt%; the weak magnetic separation magnetic field strength is 4200 Oe;

[0076] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.30 kg / t, and the amount of sodium oleate used in the cleaning process is 0.4 kg / t, and the amount of sodium oleate used in the cleaning process is 0.12 kg / t.

[0077] (5) In the rare earth flotation operation, the pulp concentration is 48wt%, the flotation temperature is 55°C, the roughing water glass dosage is 1.30kg / t, the hydroxamic acid is 4.0kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.45kg / t, and the hydroxamic acid is 1.0kg / t; the concentrating II water glass dosage is 0.25kg / t, and the hydroxamic acid is 0.60kg / t; the concentrating III water glass dosage is 0.15kg / t, and the hydroxamic acid is 0.30kg / t;

[0078] (6) The TFe grade of the obtained iron concentrate is 65.86%, the TFe recovery rate is 85.14%, the F grade is 0.23%, and the F recovery rate is 10.79%. The REO grade of the rare earth flotation concentrate is 63.80%, and the REO recovery rate is 57.77%. The CaF2 grade of the fluorite-rich tailings is 51.76%. The rare earth tailings can be further recovered from fluorite by flotation.

[0079] Example 4

[0080] The method is the same as in Example 1, except that:

[0081] (1) The iron (TFe) grade in the raw ore is 26.50%, the rare earth oxide (REO) grade is 5.83%, and the CaF2 grade is 24.63%;

[0082] (2) The preheating oxidation decomposition temperature of the mineral powder is 575°C, and the material residence time is 8 minutes; the hydrogen-based mineral phase transformation temperature is 460°C, and the material residence time is 60 minutes; the reducing atmosphere is single H2;

[0083] (3) The mineral phase transformation product is ground to -74 μm and the content is 94 wt%; the weak magnetic separation magnetic field strength is 4000 Oe;

[0084] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.20 kg / t, and the amount of sodium oleate used in the cleaning process is 0.30 kg / t; the amount of water glass used in the cleaning process is 0.2 kg / t, and the amount of sodium oleate used in the cleaning process is 0.10 kg / t;

[0085] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 60°C, the roughing water glass dosage is 0.80kg / t, the hydroxamic acid is 4.0kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.60kg / t, and the hydroxamic acid is 1.0kg / t; the concentrating II water glass dosage is 0.30kg / t, and the hydroxamic acid is 0.60kg / t; the concentrating III water glass dosage is 0.20kg / t, and the hydroxamic acid is 0.30kg / t;

[0086] (6) The TFe grade of the obtained iron concentrate is 64.23%, the TFe recovery rate is 88.23%, the F grade is 0.25%, and the F recovery rate is 9.88%. The REO grade of the rare earth flotation concentrate is 66.80%, and the REO recovery rate is 58.65%. The CaF2 grade of the fluorite-rich tailings is 47.80%. The fluorite can be further recovered from the rare earth tailings by flotation.

[0087] Example 5

[0088] The method is the same as in Example 1, except that:

[0089] (1) The iron (TFe) grade in the raw ore is 28.43%, the rare earth oxide (REO) grade is 6.12%, and the CaF2 grade is 20.13%;

[0090] (2) The preheating oxidation decomposition temperature of the mineral powder is 700°C, and the material residence time is 7 minutes; the hydrogen-based mineral phase transformation temperature is 500°C, and the material residence time is 45 minutes; the reducing atmosphere is natural gas cracking;

[0091] (3) The mineral phase transformation product is ground to -74 μm and the content is 85 wt%; the weak magnetic separation magnetic field strength is 3500 Oe;

[0092] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.50 kg / t, and the amount of sodium oleate used in the cleaning process is 0.40 kg / t; the amount of water glass used in the cleaning process is 0.5 kg / t, and the amount of sodium oleate used in the cleaning process is 0.25 kg / t;

[0093] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 60°C, the roughing water glass dosage is 1.0kg / t, the hydroxamic acid is 4.2kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.60kg / t, and the hydroxamic acid is 1.0kg / t; the concentrating II water glass dosage is 0.30kg / t, and the hydroxamic acid is 0.60kg / t; the concentrating III water glass dosage is 0.20kg / t, and the hydroxamic acid is 0.30kg / t;

[0094] (6) The TFe grade of the obtained iron concentrate is 64.86%, the TFe recovery rate is 90.27%, the F grade is 0.21%, and the F recovery rate is 11.33%. The REO grade of the rare earth flotation concentrate is 65.38%, and the REO recovery rate is 55.12%. The CaF2 grade of the fluorite-rich tailings is 53.69%. The fluorite can be further recovered from the rare earth tailings by flotation.

[0095] Example 6

[0096] The method is the same as in Example 1, except that:

[0097] (1) The iron (TFe) grade in the raw ore is 30.12%, the rare earth oxide (REO) grade is 5.45%, and the CaF2 grade is 18.96%;

[0098] (2) The preheating oxidation decomposition temperature of the mineral powder is 680°C, and the material residence time is 10 minutes; the hydrogen-based mineral phase transformation temperature is 460°C, and the material residence time is 60 minutes; the reducing atmosphere is single H2;

[0099] (3) The mineral phase transformation product is ground to -74 μm and the content is 88 wt%; the weak magnetic separation magnetic field strength is 4200 Oe;

[0100] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.30 kg / t, and the amount of sodium oleate used in the cleaning process is 0.5 kg / t, and the amount of sodium oleate used in the cleaning process is 0.25 kg / t;

[0101] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 60°C, the roughing water glass dosage is 2.0kg / t, the hydroxamic acid is 4.5kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.50kg / t, and the hydroxamic acid is 1.2kg / t; the concentrating II water glass dosage is 0.30kg / t, and the hydroxamic acid is 0.80kg / t; the concentrating III water glass dosage is 0.20kg / t, and the hydroxamic acid is 0.40kg / t;

[0102] (6) The TFe grade of the obtained iron concentrate is 65.12%, the TFe recovery rate is 89.37%, the F grade is 0.18%, and the F recovery rate is 13.10%. The REO grade of the rare earth flotation concentrate is 64.23%, and the REO recovery rate is 61.19%. The CaF2 grade of the fluorite-rich tailings is 50.03%. The rare earth tailings can be further recovered from fluorite by flotation.

[0103] Example 7

[0104] The method is the same as in Example 1, except that:

[0105] (1) The iron (TFe) grade in the raw ore is 29.50%, the rare earth oxide (REO) grade is 5.03%, and the CaF2 grade is 19.65%;

[0106] (2) The preheating oxidation decomposition temperature of the mineral powder is 700°C, and the material residence time is 4.5 min; the hydrogen-based mineral phase transformation temperature is 430°C, and the material residence time is 90 min; the reducing atmosphere is natural gas cracking;

[0107] (3) The mineral phase transformation product is ground to -74 μm and the content is 91 wt%; the weak magnetic separation magnetic field strength is 3800 Oe;

[0108] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.2 kg / t, and the amount of sodium oleate used in the cleaning process is 0.5 kg / t, and the amount of sodium oleate used in the cleaning process is 0.25 kg / t;

[0109] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 50°C, the roughing water glass dosage is 1.8kg / t, the hydroxamic acid is 4kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.50kg / t, and the hydroxamic acid is 1.2kg / t; the concentrating II water glass dosage is 0.30kg / t, and the hydroxamic acid is 0.80kg / t; the concentrating III water glass dosage is 0.20kg / t, and the hydroxamic acid is 0.40kg / t;

[0110] (6) The TFe grade of the obtained iron concentrate is 65.12%, and the TFe recovery rate is 85.64%. The F grade is 0.25%, and the F recovery rate is 8.65%. The REO grade of the rare earth flotation concentrate is 65.28%, and the REO recovery rate is 60.33%. The CaF2 grade of the fluorite-rich tailings is 52.33%. The rare earth tailings can be further recovered from fluorite by flotation.

[0111] Example 8

[0112] The method is the same as in Example 1, except that:

[0113] (1) The iron (TFe) grade in the raw ore is 30.45%, the rare earth oxide (REO) grade is 4.62%, and the CaF2 grade is 21.54%;

[0114] (2) The preheating oxidation decomposition temperature of the mineral powder is 500°C, and the material residence time is 6 minutes; the hydrogen-based mineral phase transformation temperature is 500°C, and the material residence time is 65 minutes; the ratio of H2 to CO in the mixed reducing gas is 2:1;

[0115] (3) The mineral phase transformation product is ground to -74 μm and the content is 95 wt%; the weak magnetic separation magnetic field strength is 4200 Oe;

[0116] (4) In the reverse flotation defluorination operation, the amount of water glass used in the roughing process is 1.1 kg / t, and the amount of sodium oleate used in the cleaning process is 0.5 kg / t, and the amount of sodium oleate used in the cleaning process is 0.25 kg / t;

[0117] (5) In the rare earth flotation operation, the pulp concentration is 55wt%, the flotation temperature is 65°C, the roughing water glass dosage is 1.6kg / t, the hydroxamic acid is 4.2kg / t, and the 2# oil is 0.05kg / t; the concentrating I water glass dosage is 0.50kg / t, and the hydroxamic acid is 1.2kg / t; the concentrating II water glass dosage is 0.30kg / t, and the hydroxamic acid is 0.80kg / t; the concentrating III water glass dosage is 0.20kg / t, and the hydroxamic acid is 0.40kg / t;

[0118] (6) The TFe grade of the obtained iron concentrate is 65.23%, the TFe recovery rate is 88.71%, the F grade is 0.33%, and the F recovery rate is 9.21%. The REO grade of the rare earth flotation concentrate is 61.55%, and the REO recovery rate is 56.95%. The CaF2 grade of the fluorite-rich tailings is 51.67%. The rare earth tailings can be further recovered from fluorite by flotation.

Claims

1. A method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation, characterized in that: The following steps are involved: (1) Dry pulverizing of raw ore: Crushing iron-containing rare earth polymetallic ore into ≤3 mm to obtain ore powder; (2) Hydrogen-based mineral phase transformation The mineral powder is subjected to hydrogen-based mineral phase transformation, and the transformation process mainly includes a preheating oxidation decomposition process, a hydrogen-based mineral phase transformation process and a cooling process; The specific operations are: The mineral powder is dried and preheated, and then oxidatively decomposed to obtain decomposed mineral powder; The decomposed mineral powder is subjected to hydrogen-based mineral phase transformation in a reducing atmosphere; After the conversion, the mineral powder is cooled to obtain a hydrogen-based mineral phase conversion product; (3) Grinding-magnetic separation Grinding the hydrogen-based mineral phase transformation product, wherein the grinding product fineness is controlled at -74 μm, accounting for 80 to 95 wt% by mass; The grinding products are subjected to weak magnetic separation with a magnetic field strength of 2300-4500Oe to obtain magnetically separated iron ore concentrate and magnetically separated tailings; (4) Reverse flotation defluorination The magnetically separated iron concentrate is subjected to a "one coarse and one fine" closed-circuit reverse flotation defluorination operation to obtain iron concentrate and flotation iron tailings; (5) Rare earth flotation The magnetic separation tailings are subjected to a "one coarse and three fine" closed-circuit direct flotation operation to select rare earths, and rare earth flotation concentrate and fluorite-rich tailings are obtained.

2. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (1), the main mineral contents of the iron-containing rare earth polymetallic ore are: TFe 26.0% to 31.0%, REO 4.2% to 6.5%, and CaF2 17.3% to 26.0%.

3. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: The particle size of the iron-containing rare earth polymetallic ore is 5 to 50 mm.

4. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (2), the preheating oxidation decomposition process has a drying preheating temperature of 150 to 200° C., an oxidation decomposition temperature of 450 to 750° C., and an oxidation decomposition residence time of 2 to 10 minutes.

5. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (2), the temperature of the hydrogen-based mineral phase transformation process is 430-550° C., and the residence time of the hydrogen-based mineral phase transformation process is 20-90 min.

6. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (2), the reducing atmosphere is one or a mixed reducing gas of H2, CO, natural gas, coal gas, and methane.

7. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: The cooling step is to cool the temperature to 150°C to 200°C.

8. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (4), a reverse flotation inhibitor and a reverse flotation collector are added in sequence during the defluorination reverse flotation process, the reverse flotation temperature is 20 to 40° C., and the mass concentration of the reverse flotation pulp is 30 to 40 wt %; Wherein, the reverse flotation depressant is water glass, and the dosage is 0.3-1.5 kg / t; the reverse flotation collector is sodium oleate, and the dosage is 0.04-1.2 kg / t.

9. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In step (5), a positive flotation depressant, a positive flotation collector and a frother are added in sequence during the rare earth flotation process, the positive flotation temperature is 40 to 70° C., and the positive flotation pulp concentration is 35 to 55 wt %; Wherein, the positive flotation depressant is water glass, the dosage is 0.1-4 kg / t, the positive flotation collector is hydroxamic acid, the dosage is 0.15-5.5 kg / t, and the frother is 2# oil, the dosage is 0.01-0.1 kg / t.

10. The method for recovering iron and rare earth from iron-containing rare earth polymetallic ores by hydrogen-based ore phase transformation according to claim 1, characterized in that: In the iron concentrate obtained by the method of recovering iron and rare earth from iron-containing rare earth polymetallic ore by hydrogen-based ore phase transformation, the TFe grade is 63.2% to 65.9%, and the TFe recovery rate is 80.5% to 92.0%; in the rare earth concentrate obtained, the REO grade is 59.6% to 68.5%, and the recovery rate is 55.2% to 65.5%.

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