CN114150166B - Pre-enrichment and smelting method of niobium ore - Google Patents

Pre-enrichment and smelting method of niobium ore Download PDF

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CN114150166B
CN114150166B CN202111348210.6A CN202111348210A CN114150166B CN 114150166 B CN114150166 B CN 114150166B CN 202111348210 A CN202111348210 A CN 202111348210A CN 114150166 B CN114150166 B CN 114150166B
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niobium
ore
magnetic separation
roasting
niobium ore
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CN114150166A (en
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饶明军
李光辉
张树辉
姜涛
彭志伟
张鑫
罗骏
肖仁栋
游锦香
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Central South University
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/20—Obtaining niobium, tantalum or vanadium
    • C22B34/24—Obtaining niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/02—Roasting processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention belongs to the technical field of mineral smelting, and particularly discloses a method for pre-enriching niobium ores; roasting niobium ores at the temperature of 800-1100 ℃, then placing the niobium ores into water for digestion, and then performing gravity separation treatment to obtain a heavy product which is pre-enriched concentrate and a light product which is pre-enriched tailings. The invention also comprises a dressing and smelting method for carbonitriding roasting the pre-enriched concentrate. The method has the advantages of simple process, high niobium recovery rate, low energy consumption and the like, is easy for industrial implementation, and has very wide popularization and application prospects.

Description

Method for preconcentration and dressing and smelting of niobium ore
Technical Field
The invention belongs to the technical field of rare metal ore dressing and smelting, and particularly relates to a method for dressing and smelting niobium ore.
Background
Niobium is a rare refractory metal, has excellent characteristics of high temperature resistance, corrosion resistance, low vapor pressure, good ductility, high thermal conductivity and the like, is an important strategic metal, is an indispensable metal material in modern industry and advanced technology, and is widely applied to the fields of steel, chemical industry, aerospace, nuclear industry, superconduction, electrical appliances, electronic information, medicine and the like.
Around 90% of niobium resources are used in the form of ferrocolumbium for the production of microalloyed steel, the major producing and exporting countries of ferrocolumbium are brazil and canada, and the major consuming and importing countries include china, usa, japan, korea, germany, russia, etc. China is the first major iron and steel industry in the world, niobium consumption and import quantity are the first in the world, and the import quantity of the niobium-iron alloy exceeds 1/3 of the total export quantity of the world.
The niobium ore resources worldwide mainly exist in the forms of pyrochlore, niobite and tantalum-niobium ore. The ore is characterized in that: low in valuable metal content and high in gangue content. The existing sorting method of niobium ore generally comprises the steps of crushing and grinding the ore and then separating the crushed ore by flotation. However, because niobium-containing ores are brittle and fragile, gangue minerals are low in hardness, and a argillization phenomenon is very easy to occur in an ore grinding process, so that subsequent flotation operation is seriously influenced, a desliming process is generally required to be added after the ores are ground to reduce the influence of fine mud on the subsequent flotation operation, but a considerable part of valuable metals can be taken away by the desliming process. For example, in the conventional "grinding-desliming-flotation" separation method for pyrochlore-type niobium ore, the niobium loss rate in the desliming step is as high as 14%.
The niobium concentrate is usually produced into the niobium-iron alloy by an aluminothermic reduction method, and the niobium concentrate, hematite, aluminum powder, fluorite, lime and other raw materials are generally mixed and smelted in an aluminothermic reduction furnace, wherein the smelting temperature is 2200-2400 ℃. Aluminum powder is used as a reducing agent, so that the smelting energy consumption is high and the cost is high.
In conclusion, the traditional beneficiation process has the problems of complex flow, low niobium recovery rate, serious resource loss and the like due to the factors of low niobium grade in niobium ore, serious influence of slime on flotation operation and the like, and the traditional ferrocolumbium smelting method has the problems of high smelting energy consumption, high cost and the like. Therefore, the development of a new efficient niobium ore dressing and smelting technology has very important significance for the healthy and continuous development of the niobium industry in China and the world.
The invention is especially provided for solving the problems that the niobium ore separation process is easy to generate argillization, the niobium recovery rate is low, the energy consumption in the smelting process is high, the cost is high and the like.
Disclosure of Invention
The invention aims to solve the technical problem of providing a high-efficiency preconcentration and dressing and smelting method of niobium ore, which avoids or reduces the argillization phenomenon in the ore grinding process, improves the recovery rate of niobium, and reduces the energy consumption and cost in the smelting process.
A process for pre-enriching niobium ore includes calcining niobium ore at 800-1100 deg.C, digesting in water, and gravity separation to obtain heavy concentrate and light tailings.
The research of the invention finds that the niobium ore is creatively roasted and digested, and the gravity separation treatment is creatively carried out in the digestion system, so that the effective enrichment of valuable minerals in the niobium ore can be effectively improved, and in addition, the invention is beneficial to activating the niobium ore and improving the subsequent dressing and smelting effects.
In the invention, the niobium ore comprises at least one of pyrochlore ore, columbite and tantalum-niobium ore.
Preferably, no deep crushing of the niobium ore is required. For example, the niobium ore before firing has a grain size of less than 30mm.
In the invention, the roasting temperature is controlled, which is beneficial to the separation effect of roasting, digestion and gravity separation and further beneficial to improving the enrichment effect of niobium ores; in addition, the niobium valuable mineral can be effectively activated, and the subsequent dressing and smelting are facilitated.
Preferably, the roasting temperature is 850-1050 ℃; more preferably 900 to 1000 ℃. Research finds that at the temperature, the method is favorable for further improving the pre-enrichment and dressing and smelting effects and improving the recovery rate of valuable minerals.
Preferably, the roasting time is 5-120 min, preferably 60-120 min;
preferably, the atmosphere of the calcination is an oxidizing atmosphere or a weakly reducing atmosphere. The oxidizing atmosphere is, for example, air, and the weakly reducing atmosphere is, for example, a CO-containing atmosphere having a volume concentration of 5% to 15%.
Preferably, the loss on ignition of the roasting is not less than 80% of the total loss on ignition of the ore.
In the invention, the roasted product is innovatively digested by water, and further gravity separation is carried out under a digestion system, so that the separation and enrichment effects can be synergistically improved.
Preferably, the liquid-solid ratio of the digestion starting solution is 1-6; that is, 1-6L of water is added into each kilogram of the roasted material for mixing and digestion. Further preferably, the liquid-solid ratio of the digestion starting solution is 2-4L/kg;
preferably, the temperature of the digestion process is 40-95 ℃;
preferably, the digestion time is 5 to 60min, more preferably 10 to 30min.
The invention also provides a method for dressing and smelting niobium ores, which is characterized in that the niobium ores are pre-enriched by adopting the pre-enrichment method to obtain pre-enriched concentrates;
and carrying out carbonitriding roasting on the pre-enriched concentrate, the carbon source and the nitrogen source at the temperature of 1200-1500 ℃, and carrying out low-intensity magnetic separation on the obtained roasted material to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings.
The research of the invention finds that the recovery rate and the grade of the niobium ore can be unexpectedly improved by innovatively carrying out carbonitriding roasting on the niobium ore and combining the combined control of the temperature. Research also finds that the pre-enrichment process and the carbonitriding roasting are combined, and further based on combined control of temperature, the synergy can be achieved unexpectedly, and the recovery rate of the niobium ore can be improved remarkably.
In the invention, the carbon source is a carbonaceous raw material capable of reducing, preferably, the carbon source comprises at least one of coke powder, coal powder, activated carbon and blast furnace dust;
preferably, the C/O ratio in the mixture of pre-enriched concentrate and carbon source is between 0.8 and 2.0.
That is, the carbon source is 3 to 6wt.% of the pre-enriched concentrate weight.
Preferably, the nitrogen source is nitrogen-containing atmosphere;
preferably, the nitrogen-containing atmosphere is pure nitrogen or a mixed gas of nitrogen and inert gas;
preferably, the nitrogen content is not less than 50% v in the nitrogen-containing atmosphere;
preferably, the pre-enriched concentrate is finely ground, mixed with a carbon source, agglomerated and then subjected to carbonitriding roasting in a nitrogen-containing atmosphere.
The carbonitriding baking temperature is preferably 1350 to 1500 ℃, and more preferably 1400 to 1450 ℃. At the preferable carbonitriding roasting temperature, the method can obtain better synergy with the pre-enrichment process, and can obtain better metallurgical effect.
Preferably, the carbonitriding baking time is 1 to 4 hours.
Preferably, the roasted material is subjected to low-intensity magnetic separation after being crushed and ground;
preferably, the roasted material is ground to a particle size of-200 meshes and the mass content is not less than 90%;
preferably, the intensity of the low-intensity magnetic separation is 800-1600 Gs, and more preferably 1000-1400 Gs.
Preferably, carrying out strong magnetic separation on the tailings subjected to weak magnetic separation; obtaining strong magnetic separation concentrate;
preferably, the intensity of the strong magnetic separation is 10000 to 20000Gs.
Preferably, the strong magnetic separation concentrate is returned to the carbon nitriding roasting stage for recycling.
The preferred method for pre-enriching and dressing and smelting the niobium ore comprises the following stages and steps:
stage one: pre-enrichment stage
Step 1: crushing
The niobium ore is crushed to below 30mm.
And 2, step: pre-baking
And (3) sending the crushed material into a roasting furnace for pre-roasting, wherein the pre-roasting temperature is 800-1100 ℃, the pre-roasting time is 5-120 min, the roasting atmosphere is an oxidizing atmosphere or a weak reducing atmosphere, and the loss on ignition is not less than 80% of the total loss on ignition of the ore.
And step 3: digestion of
And placing the pre-roasted product in water for digestion, wherein the liquid-solid ratio of the digestion starting solution is 1-6.
And 4, step 4: gravity sorting
And (3) performing gravity separation on the digestion product to obtain a heavy product which is pre-enriched concentrate and a light product which is pre-enriched tailings.
And a second stage: carbonitriding roasting-magnetic separation stage
And 5: proportioning, mixing and agglomerating
And (3) finely grinding the pre-enriched concentrate, adding a carbon source, proportioning, uniformly mixing and agglomerating. The carbon source comprises coke powder, coal powder, activated carbon and blast furnace dust, and the mass of the added carbon source is that the C/O ratio of the mixture is 0.8-2.0.
And 6: carbonitriding roasting
And placing the dried agglomerate in a nitrogen atmosphere for carbonitriding roasting. The roasting temperature is 1200-1500 ℃, and the roasting time is 1-4 h.
And 7: ore grinding and low intensity magnetic separation
And after the roasted blocks are cooled, crushing, grinding and low-intensity magnetic separation are carried out to obtain the magnetic niobium-containing metal iron powder product and the low-intensity magnetic separation tailings. In the preferred scheme, the roasted blocks are ground until the granularity is-200 meshes and the mass content is not less than 90 percent, and then the low-intensity magnetic separation is carried out by a low-intensity magnetic field with the intensity of 800-1600 Gs.
And 8: high magnetic separator
And performing strong magnetic separation on the low-intensity magnetic separation tailings to obtain strong magnetic separation concentrate, which can be returned to the ingredients for further recovery of niobium. In the preferred scheme, the tailings subjected to weak magnetic separation are subjected to strong magnetic separation by a strong magnetic field with the strength of 10000-20000 Gs, and the obtained strong magnetic separation concentrate can be returned to be prepared into ingredients for further recovery of niobium.
The technical principle of the method for selecting and smelting niobium ore adopting the technical scheme is briefly described as follows:
stage one: pre-enrichment stage
In the roasting process and the digestion process, larger stress can be generated to promote the self pulverization of gangue minerals and the monomer dissociation between the gangue minerals and valuable minerals, therefore, the separation method only needs to crush the minerals to be less than 30mm, and can remove most of the gangue minerals without grinding, and then creatively carries out gravity separation in a digestion system, thereby being beneficial to realizing the high-selectivity separation of the minerals, and the pre-enriched concentrate obtained by the gravity separation carries out subsequent separation operation after grinding, avoiding or reducing the argillization phenomenon in the grinding process, and improving the separation recovery rate of niobium. A large amount of gangue minerals are removed through pre-enrichment, and valuable minerals are activated at the same time, so that the formation, migration, aggregation and growth of carbon niobium nitride and metal iron particles in the subsequent carbonitriding roasting process are facilitated, and the niobium recovery rate in the carbonitriding roasting-magnetic separation stage is improved.
And a second stage: carbonitriding roasting-magnetic separation stage
Nb is easy to form carbonitride, the carbonitride is easy to enrich around metal iron, and the metal iron can be used as a carrier to carry out high-efficiency separation and enrichment of niobium. During the carbonitriding roasting process, the niobium-containing mineral is firstly carbonized to generate niobium carbide, and the niobium carbide can be further nitrided to form niobium nitride. The niobium-containing metal iron particles with larger size (more than 20 mu m) in the carbonitriding roasting agglomerate have stronger magnetism and can be recovered by low-intensity magnetic separation; the niobium-containing metallic iron particles with small size (< 20 mu m) have weaker magnetism and can be recovered by strong magnetic separation. Niobium in the niobium-containing metal iron powder mainly exists in the form of niobium nitride, and the niobium-containing metal iron powder can replace a niobium-iron alloy as an additive for smelting microalloy steel after impurity removal treatment, so that the process of producing the niobium-iron alloy by an aluminothermic reduction method is omitted.
The main reactions occurring during the carbonitriding firing are:
Fe 2 O 3 +3C＝2Fe+3CO
Fe 3 O 4 +4C＝3Fe+4CO
FeNb 2 O 6 +8C = Fe +2NbC +6CO (columbite)
(Ca,Na) 2 (Nb,Ti) 2 O 6 F +9C = CaO + NaF +2NbC +2TiC +5CO (pyrochlore ore)
Nb 2 O 5 +7C＝2NbC+5CO
Nb 2 O 5 +5C+N 2 ＝2NbN+5CO
The invention has the advantages that:
1. through pre-enrichment, a large amount of gangue minerals can be removed, valuable minerals are activated at the same time, the loss rate of niobium is low, and the recovery rate is high.
2. Most gangue minerals can be removed without grinding, and the pre-enriched concentrate is ground and then subjected to subsequent separation operation, so that the argillization phenomenon in the grinding process is avoided or reduced, and the subsequent separation operation effect is greatly improved.
3. The niobium ore is innovatively subjected to carbonitriding roasting, and the pre-enrichment means and the carbonitriding roasting smelting means are combined, so that the synergy can be realized, the high-efficiency separation and enrichment of niobium can be realized by taking metal iron as a carrier, and the grade and the recovery rate are improved. Research shows that compared with the traditional separation method based on flotation, the niobium recovery rate can be improved by 20-40%.
4. Niobium in the low-intensity magnetic separation concentrate niobium-containing metal iron powder mainly exists in the form of niobium nitride, and the niobium nitride can be used as an additive for smelting microalloy steel instead of niobium-iron alloy after impurity removal treatment, so that the process of producing the niobium-iron alloy by an aluminothermic reduction method is omitted.
5. The method has the advantages of simple process, high niobium recovery rate, low energy consumption and the like, and is easy to realize industrialization.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1:
step (1): nb in a calcined chlorite ore 2 O 5 The content is 1.2%, the main gangue minerals are calcite, dolomite, feldspar and the like, the content of CaO is 34.9%, the content of MgO is 6.3%, and the total burning loss is 19.9%. Crushing pyrochlore ore to be less than 15mm, sending the pyrochlore ore to a roasting furnace for pre-roasting, wherein the pre-roasting temperature is 950 ℃, the pre-roasting time is 60min, the roasting atmosphere is an oxidizing atmosphere (air, the same applies below), and the loss on ignition is 89.4 percent of the total loss on ignition of the ore. And (3) placing the pre-roasted product in water for digestion, wherein the liquid-solid ratio of a digestion starting solution is 3. And (3) performing gravity separation on the digestion product to obtain a heavy product which is pre-enriched concentrate and a light product which is pre-enriched tailings.
Step (2): finely grinding the pre-enriched concentrate to-100 meshes, uniformly mixing the pre-enriched concentrate with coke powder (based on the pre-enriched concentrate, the same below) with the mass ratio of 6% for agglomeration, drying the obtained agglomerate, introducing nitrogen gas for carbonitriding roasting at the roasting temperature of 1400 ℃ for 120min. And after cooling the roasted blocks, crushing and grinding the roasted blocks until the mass content of the roasted blocks is not less than 90 percent in a granularity of-200 meshes, performing low-intensity magnetic separation by using a low-intensity magnetic field with the intensity of 1400Gs to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings, performing high-intensity magnetic separation on the nonmagnetic tailings by using a high-intensity magnetic field with the intensity of 15000Gs, and returning the obtained high-intensity magnetic separation concentrate to ingredients for further recovering niobium.
The tailing rejection rate in the pre-enrichment stage is 40%, the niobium recovery rate is 94.7%, the recovery rate in the carbonitriding roasting-magnetic separation stage is 70.5%, the recovery rate in the strong magnetic separation stage is 14.4%, and the comprehensive recovery rate in the whole process is 80.4%. The traditional ore dressing method based on flotation is used for treating the pyrochlore ore, the niobium recovery rate is only about 50%, and the dressing and smelting method based on pre-enrichment-carbonitriding roasting can improve the niobium recovery rate by about 30%.
Example 2:
the difference from example 1 is only that the temperatures of the pre-baking stages in step (1) were changed to 800 deg.C, 900 deg.C, 1000 deg.C, and 1100 deg.C, respectively.
The results at each temperature are shown in table 1:
TABLE 1 Pre-enrichment and concentration indexes of niobium ores at different pre-calcination temperatures
Figure BDA0003354756940000091
As can be seen from Table 1, as the pre-firing temperature is increased from 800 ℃ to 1100 ℃, the pre-enrichment tailing ratio is increased and then decreased, and the change trend of the total niobium recovery rate is the same.
Example 3:
the difference from example 1 is only that the temperatures in the carbonitriding firing step (2) were changed to 1200 ℃, 1300 ℃, 1400 ℃ and 1500 ℃.
The results at each temperature are shown in table 2:
TABLE 2 Pre-enrichment and concentration indexes of niobium ore at different carbonitriding roasting temperatures
Figure BDA0003354756940000101
As can be seen from Table 1, as the carbonitriding roasting temperature is increased from 1200 ℃ to 1500 ℃, the change trends of the recovery rate of the low-intensity magnetic separation niobium, the recovery rate of the high-intensity magnetic separation niobium and the total recovery rate of niobium are basically consistent, and are respectively increased and then decreased, the index when the carbonitriding roasting temperature is 1400 ℃ is optimal, and the total recovery rate of niobium is 80.4%.
Example 4
Step (1): nb in a calcined chlorite ore 2 O 5 The content is 0.54 percent, the main gangue minerals comprise calcite, dolomite and the like, the content of CaO is 32.4 percent, the content of MgO is 9.8 percent, and the total burning loss is 21.7 percent. Crushing pyrochlore ore to below 20mm, and roasting in a roasting furnace at 900 deg.c for 120min in oxidizing atmosphere in the loss rate of 92.5% of the total loss of the ore. And (3) placing the roasted product in water for digestion, wherein the liquid-solid ratio of a digestion starting solution is 3. And performing gravity separation on the digestion product to obtain a heavy product, namely pre-enriched concentrate, and a light product, namely pre-enriched tailings.
Step (2): and (3) finely grinding the pre-enriched concentrate to-100 meshes, uniformly mixing the pre-enriched concentrate with coke powder with the mass ratio of 5% for agglomeration, drying the obtained agglomerate, introducing nitrogen to carry out carbonitriding roasting at the roasting temperature of 1350 ℃ for 90min. And after cooling the roasted blocks, crushing and grinding the blocks until the mass content of the roasted blocks is not less than 90 percent in a granularity of-200 meshes, performing low-intensity magnetic separation by using a low-intensity magnetic field with the intensity of 1200Gs to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings, performing high-intensity magnetic separation on the nonmagnetic tailings by using a high-intensity magnetic field with the intensity of 18000Gs, and returning the obtained high-intensity magnetic separation concentrate to ingredients for further recovering niobium.
The tailing rejection rate in the pre-enrichment stage reaches 55%, the recovery rate of niobium is 93.0%, the recovery rate of low-intensity magnetic separation niobium is 67.4%, the recovery rate of high-intensity magnetic separation niobium is 15.6% and the comprehensive recovery rate of niobium in the whole process is 77.2% in the carbonitriding roasting-magnetic separation stage. The recovery rate of niobium is only about 50% when the pyrochlore ore is treated by the traditional flotation-based ore dressing method, and the recovery rate of niobium can be improved by about 27% by the pre-enrichment-carbonitriding roasting-based ore dressing and smelting method.
Example 5
Step (1): nb in niobium iron ore 2 O 5 The content is 0.16%, the main gangue minerals are dolomite, fluorite, calcite and the like, the content of CaO is 30.7%, the content of MgO is 11.2%, and the total burning loss is 22.4%. Crushing the niobium-iron ore to be less than 10mm, and feeding the niobium-iron ore into a roasting furnace for roasting, wherein the roasting temperature is 850 ℃, the roasting time is 60min, the roasting atmosphere is an oxidizing atmosphere, and the loss on ignition is 94.2% of the total loss on ignition of the ore. And (3) placing the roasted product into water for digestion, wherein the liquid-solid ratio of the digestion starting solution is 3. And (3) performing gravity separation on the digestion product to obtain a heavy product which is pre-enriched concentrate and a light product which is pre-enriched tailings.
Step (2): and (3) finely grinding the pre-enriched concentrate to-100 meshes, uniformly mixing the pre-enriched concentrate with coke powder with the mass ratio of 3% for agglomeration, drying the obtained agglomerate, introducing nitrogen to carry out carbonitriding roasting at the roasting temperature of 1400 ℃ for 60min. And after cooling the roasted blocks, crushing and grinding the roasted blocks until the mass content of the roasted blocks is not less than 90 percent in a granularity of-200 meshes, performing low-intensity magnetic separation by using a low-intensity magnetic field with the intensity of 1000Gs to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings, performing high-intensity magnetic separation on the nonmagnetic tailings by using a high-intensity magnetic field with the intensity of 21000Gs, and returning the obtained high-intensity magnetic separation concentrate to ingredients for further recovering niobium.
The tailing rejection rate in the pre-enrichment stage reaches 49%, the recovery rate of niobium is 91.6%, the recovery rate of low-intensity magnetic separation niobium is 72.4%, the recovery rate of high-intensity magnetic separation niobium is 18.3% and the comprehensive recovery rate of niobium in the whole process is 83.1% in the carbonitriding roasting-magnetic separation stage. The traditional beneficiation method based on flotation is used for treating the niobite, the recovery rate of niobium is only about 55%, and the beneficiation method based on pre-enrichment-carbonitriding roasting can improve the recovery rate of niobium by about 28%.
Example 6:
compared with the example 1, the main difference is that the pre-roasting is carried out by adopting a reducing atmosphere, and the main difference is that:
step (1): nb in a calcined chlorite ore 2 O 5 Content (wt.)1.2 percent, the main gangue minerals are calcite, dolomite, feldspar and the like, the CaO content is 34.9 percent, the MgO content is 6.3 percent, and the total burning loss is 19.9 percent. Crushing pyrochlore ore to be less than 15mm, sending the pyrochlore ore to a roasting furnace for pre-roasting at the temperature of 950 ℃ for 60min, wherein the roasting atmosphere is a weak reduction atmosphere (the volume concentration of CO is 5-15 percent), and the loss on ignition is 93.0 percent of the total loss on ignition of the ore. And (3) placing the pre-roasted product into water for digestion, wherein the liquid-solid ratio of a digestion starting solution is 3. And (3) performing gravity separation on the digestion product to obtain a heavy product which is pre-enriched concentrate and a light product which is pre-enriched tailings.
Step (2): and (3) finely grinding the pre-enriched concentrate to-100 meshes, uniformly mixing the pre-enriched concentrate with 6% coke powder by mass for agglomeration, drying the obtained agglomerate, introducing nitrogen gas for carbonitriding roasting at the roasting temperature of 1400 ℃ for 120min. And after cooling the roasted blocks, crushing and grinding the roasted blocks until the mass content of the roasted blocks is not less than 90 percent in a granularity of-200 meshes, performing low-intensity magnetic separation by using a low-intensity magnetic field with the intensity of 1400Gs to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings, performing high-intensity magnetic separation on the nonmagnetic tailings by using a high-intensity magnetic field with the intensity of 15000Gs, and returning the obtained high-intensity magnetic separation concentrate to ingredients for further recovering niobium.
The tailing rejection rate in the pre-enrichment stage is 42 percent, the niobium recovery rate is 96.3 percent, the recovery rate in the carbonitriding roasting-magnetic separation stage is 72.1 percent, the recovery rate in the strong magnetic separation stage is 15.6 percent, and the comprehensive recovery rate in the whole process of niobium is 84.5 percent. The traditional ore dressing method based on flotation is used for treating the pyrochlore ore, the niobium recovery rate is only about 50 percent, and the dressing and smelting method based on pre-enrichment-carbonitriding roasting can improve the niobium recovery rate by about 35 percent.
Comparative example 1:
the only difference compared to example 1 is that the pre-enrichment step of step (1) was not performed: the method comprises the following specific steps:
nb in pyrochlore ore (same as example 1) 2 O 5 The main gangue minerals with the content of 1.2 percent are calcite, dolomite, feldspar and the like, the CaO content is 34.9 percent, the MgO content is 6.3 percent, and the total burning loss is 19.9 percent. Grinding pyrochlore ore to-100 mesh, and mixing with 6 wt% of coke powderAgglomeration, drying the obtained agglomerate, introducing nitrogen gas to perform carbonitriding roasting at 1400 ℃ for 120min. And after the roasted blocks are cooled, crushing and grinding the blocks until the mass content of the roasted blocks is not less than 90 percent and the granularity is-200 meshes, carrying out low-intensity magnetic separation by using a low-intensity magnetic field with the intensity of 1400Gs to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings, carrying out high-intensity magnetic separation on non-magnetic tailings by using a high-intensity magnetic field with the intensity of 15000Gs, and returning the obtained high-intensity magnetic separation concentrate to batching for further recovering niobium.
The pyrochlore ore is not subjected to pre-enrichment, and in the stage of carbonitriding roasting-magnetic separation, the recovery rate of the low-intensity magnetic separation niobium is 58.6 percent, the recovery rate of the high-intensity magnetic separation niobium is 8.2 percent, and the comprehensive recovery rate of the niobium in the whole process is 66.8 percent. Compared with the embodiment 1, the comprehensive recovery rate of the niobium in the whole process is reduced by 13.6 percent because the subsequent carbonitriding roasting-magnetic separation effect is influenced because the pre-enrichment is not carried out.
Comparative example 2:
compared with example 1, the difference is only that the pre-roasting temperature is 700 ℃: other procedures and parameters were the same as in example 1:
the tailing rejection rate in the pre-enrichment stage is 12%, the niobium recovery rate is 96.2%, the recovery rate in the carbonitriding roasting-magnetic separation stage is 61.3%, the recovery rate in the strong magnetic separation stage is 9.6%, and the comprehensive recovery rate in the whole process is 68.2%. Because the pre-roasting temperature is not in a reasonable range, the tailing rejection rate in the pre-enrichment stage is low, the subsequent carbonitriding roasting-magnetic separation effect is influenced, and compared with the embodiment 1, the comprehensive recovery rate of the niobium in the whole process is reduced by about 12%.
Comparative example 3:
compared with example 1, the difference is only that the pre-firing temperature is 1200 ℃: other procedures and parameters were the same as in example 1:
the tailing rejection rate in the pre-enrichment stage is 10%, the niobium recovery rate is 95.1%, the recovery rate of the low-intensity magnetic separation niobium in the carbonitriding roasting-magnetic separation stage is 62.2%, the recovery rate of the high-intensity magnetic separation niobium is 9.4%, and the comprehensive recovery rate of the whole-process niobium is 68.1%. Because the pre-roasting temperature is not controlled in the range of the invention, the cooperativity of pre-enrichment and carbonitriding roasting is influenced, the tailing rejection rate in the pre-enrichment stage is low, the subsequent carbonitriding roasting-magnetic separation effect is influenced, and compared with the embodiment 1, the comprehensive recovery rate of the niobium in the whole process is reduced by about 12 percent.
Comparative example 4:
compared with the embodiment 1, the difference is that the carbon-nitrogen roasting temperature is 1100 ℃: the other steps and parameters were the same as in example 1.
The tailing rejection rate in the pre-enrichment stage is 40%, the niobium recovery rate is 94.7%, the recovery rate in the carbonitriding roasting-magnetic separation stage is 25.4%, the recovery rate in the strong magnetic separation stage is 6.6%, and the comprehensive recovery rate in the whole process is 30.3%. Since the carbonitriding roasting temperature is not controlled in the range of the invention, the cooperativity of the preconcentration and the carbonitriding roasting is influenced, and compared with the embodiment 1, the comprehensive recovery rate of the niobium in the whole process is reduced by about 50 percent.

Claims (24)

1. The method is characterized in that niobium ores are roasted at the temperature of 800-1100 ℃, then are placed in water for digestion, and then are subjected to gravity separation treatment, so that heavy products are pre-enriched concentrate, and light products are pre-enriched tailings.
2. The method for the pre-enrichment of niobium ore as claimed in claim 1, wherein said niobium ore comprises at least one of pyrochlore ore, niobite ore, tantalum niobium ore.
3. The method for the preconcentration of niobium ore as claimed in claim 1, wherein the niobium ore before firing has a particle size of less than 30mm.
4. The method for the preconcentration of niobium ore according to claim 1, wherein the firing temperature is 850 to 1050 ℃.
5. The method for preconcentration of niobium ore according to claim 1, wherein the calcination time is 5min to 120min.
6. The method for the pre-enrichment of niobium ore as claimed in claim 1, wherein the atmosphere for the calcination is an oxidizing atmosphere or a weakly reducing atmosphere.
7. The method for preconcentration of niobium ore according to claim 1, wherein the loss on ignition of the ore is not less than 80% of the total loss on ignition of the ore.
8. The method for preconcentration of niobium ore according to claim 1, wherein the liquid-solid ratio of the digestion starting solution is 1 to 6.
9. The process for the preconcentration of niobium ore as claimed in claim 1, wherein the temperature of the digestion process is 40 ℃ to 95 ℃.
10. The method for preconcentration of niobium ore according to claim 1, wherein the digestion time is 5min to 60min.
11. A method for dressing and smelting niobium ores, which is characterized in that the niobium ores are pre-enriched by adopting the pre-enrichment method of any one of claims 1 to 10 to obtain pre-enriched concentrates;
and carrying out carbonitriding roasting on the pre-enriched concentrate, a carbon source and a nitrogen source at the temperature of 1350-1500 ℃, and carrying out low-intensity magnetic separation on the obtained roasted material to obtain a magnetic niobium-containing metal iron powder product and low-intensity magnetic separation tailings.
12. The method of beneficiating niobium ore as claimed in claim 11, wherein the source of carbon includes at least one of coke breeze, coal fines, activated carbon, blast furnace dust.
13. The method of beneficiating niobium ore as claimed in claim 11, wherein the ratio of C/O in the mixture of pre-enriched concentrate and carbon source is 0.8 to 2.0.
14. The method of beneficiating niobium ore of claim 11, wherein said nitrogen source is a nitrogen-containing atmosphere.
15. The method of beneficiating niobium ore as claimed in claim 14, wherein the nitrogen-containing atmosphere is pure nitrogen or a mixture of nitrogen and an inert gas.
16. The method of beneficiating niobium ore as claimed in claim 15, wherein the nitrogen content of the nitrogen-containing atmosphere is not less than 50% v.
17. The method of beneficiating niobium ore of claim 11, wherein the preconcentrate concentrate is ground, mixed with a carbon source, agglomerated, and carbonitrided calcined in a nitrogen-containing atmosphere.
18. The method for dressing and smelting niobium ore according to claim 11, wherein the time for carbonitriding roasting is 1 to 4 hours.
19. The method of dressing and smelting niobium ore as claimed in claim 11, wherein the roasted material is subjected to low intensity magnetic separation after crushing and grinding.
20. The dressing and smelting method of niobium ore according to claim 19, wherein the roasted material is ground to a grain size of-200 mesh mass content of not less than 90%.
21. The method for dressing and smelting niobium ore according to claim 19, wherein the intensity of the low-intensity magnetic separation is 800 to 1600Gs.
22. The method for dressing and smelting niobium ore according to claim 11, wherein the tailings subjected to low-intensity magnetic separation are subjected to high-intensity magnetic separation; and obtaining the strong magnetic separation concentrate.
23. The method of beneficiating niobium ore as claimed in claim 22, wherein the intensity of the high magnetic field is 10000 to 20000gs.
24. The method of beneficiating niobium ore as claimed in claim 22, wherein said concentrate from the high intensity magnetic separation is recycled back to the carbonitriding roasting stage.
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