CN109957673B - Iron ore concentrate metal ceramic and preparation method thereof - Google Patents
Iron ore concentrate metal ceramic and preparation method thereof Download PDFInfo
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- CN109957673B CN109957673B CN201910163688.8A CN201910163688A CN109957673B CN 109957673 B CN109957673 B CN 109957673B CN 201910163688 A CN201910163688 A CN 201910163688A CN 109957673 B CN109957673 B CN 109957673B
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
- C22C1/058—Mixtures of metal powder with non-metallic powder by reaction sintering (i.e. gasless reaction starting from a mixture of solid metal compounds)
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/00—Making non-ferrous alloys
- C22C1/10—Alloys containing non-metals
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/12—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on oxides
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Abstract
The invention discloses an iron ore concentrate metal ceramic and a preparation method thereof, wherein the metal ceramic is prepared by taking iron ore concentrate, bauxite, aluminum oxide and a reducing agent as main raw materials through mixing, forming and sintering, and the raw materials are as follows by mass percent: 30-60% of iron ore concentrate, 15-30% of bauxite, 10-30% of aluminum oxide and 10-30% of reducing agent. Iron oxide in the iron ore concentrate is reduced into metallic iron by a reducing agent at high temperature and is uniformly distributed in an alumina matrix. The metal ceramic has the advantages of high hardness and high strength of ceramic, high toughness of metal, low production cost and simple preparation method. The invention provides a new way for the comprehensive utilization of iron ore concentrate, which not only can reduce the discharge of solid waste, but also can increase the economic benefit.
Description
Technical Field
The invention relates to a production method of metal ceramics, in particular to metal ceramics processed by iron ore concentrate and a preparation method thereof.
Background
Cermet is a composite material consisting of a metal or alloy and one or more ceramics, typically a ceramic in an amount of about 15% to about 85% by volume. The cermet material not only maintains the characteristics of high strength, high hardness, wear resistance, high temperature resistance, oxidation resistance and the like of the ceramic, but also has high toughness of the metal. Therefore, the metal ceramic has various properties of both ceramics and metals, so the metal ceramic is a very important composite material, and has become a research hotspot of composite material developers. At present, the research on the cermet materials mainly focuses on TiC, WC and other carbides and Al2O3And the metal phase generally employs elements such as Co, W, Mo, Ni, Fe, etc. The traditional process generally adopts fine chemical powder as a raw material, has good performance, but has complex preparation process and high price, and limits the wide application of the metal ceramic.
Using iron extractsThe ore contains about 40% -65% iron oxide and a small amount of SiO2CaO and MgO, and the iron oxides are all changed into metallic iron by carbothermic reduction, while SiO2CaO and MgO are used as sintering aids to promote densification of the material. Bauxite contains more than 60-90% of alumina and is generally used as a raw material for extracting industrial alumina, but a large amount of red mud which is solid waste is generated in the extraction process and is used as a raw material for preparing high-added-value metal ceramics, so that the emission of the solid waste is reduced, and the economic benefit is remarkably increased.
Therefore, the metal ceramic prepared by the iron ore concentrate and the bauxite not only can expand the way of high-value utilization of minerals such as the iron ore concentrate, but also can provide a metal ceramic material with high performance and low cost. The technology for directly preparing the metal ceramic by using the iron ore concentrate and the bauxite still belongs to the blank at present.
The process difficulty of preparing the metal ceramic composite material by using natural minerals such as iron ore concentrate, bauxite and the like is as follows: the chemical components of natural minerals fluctuate to a certain extent, and the established process route has wide raw material adaptability; on the other hand, the chemical components in the natural minerals are complex, the invention adopts a carbothermic reduction process, and the chemical reaction of the reducing agent and other substances in the sintering process must be strictly controlled.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a metal ceramic processed by using iron ore concentrate and a preparation method thereof.
The purpose of the invention is realized by the following technical scheme:
the iron ore concentrate metal ceramic is prepared from iron ore concentrate, bauxite, aluminum oxide and a reducing agent, and comprises the following raw materials in percentage by mass: 30-60% of iron ore concentrate, 15-30% of bauxite, 10-30% of aluminum oxide and 10-30% of reducing agent.
The iron ore concentrate is iron-containing raw ore or iron-containing mineral subjected to magnetic separation process, preferablyIs sulfur-containing iron ore concentrate. Further, the iron ore concentrate contains sulfur and MnO2The iron ore concentrate of (1); further, the sulfur content is 2 to 3 wt%, MnO2The content is 1-2 wt%.
The alumina content of the bauxite is 60-90%.
The reducing agent is preferably one or a mixture of more of activated carbon, graphite and aluminum powder.
The preparation method of the iron ore concentrate metal ceramic comprises the following steps:
(1) weighing the following raw materials in percentage by mass: 30-60% of iron ore concentrate, 15-30% of bauxite, 10-30% of aluminum oxide and 10-30% of reducing agent;
(2) the raw materials are fully and uniformly mixed through wet ball milling, and the slurry is further dried to obtain powder;
(3) and pressing and molding the powder, and then placing the powder in a sintering furnace for sintering, or directly placing the powder in the sintering furnace for molding and sintering to obtain the iron ore concentrate metal ceramic.
In the step (2), the ball milling medium is preferably absolute ethyl alcohol or acetone, and the ball milling time is preferably 0.5-4 h.
In the step (3), the molding pressure is preferably 30-200 Mpa; the sintering furnace comprises a normal pressure sintering furnace, a hot pressing sintering furnace, a microwave sintering furnace, a plasma discharge sintering furnace and the like. Wherein the sintering temperature is 950-1450 ℃, and the heat preservation time is 30-180 minutes.
Compared with the prior art, the invention has the beneficial effects that:
(1) a certain amount of reducing agent is added into the iron ore concentrate and the bauxite, and the metal ceramic is prepared by a sintering method, so that the preparation cost of the material can be greatly reduced.
(2) Iron oxide in the iron ore concentrate is reduced into metallic iron by a reducing agent at high temperature and is uniformly distributed in an alumina matrix.
(3) The method can provide a new way for the comprehensive utilization of the iron ore concentrate by utilizing the iron ore concentrate to prepare the metal ceramic, and directly prepare minerals into materials, thereby obviously reducing the energy consumption and the emission of solid wastes.
Drawings
FIG. 1 is a flow chart of the process for preparing the iron ore concentrate cermet of the present invention.
Fig. 2 is the XRD pattern of the iron ore concentrate cermet prepared in the example. The XRD patterns of samples A1-A5 correspond to those of examples 1-5, respectively, and the samples are shown to contain mainly alumina phase and metallic iron phase.
Fig. 3 is an SEM image of iron concentrate cermet prepared in example. In the figure, (a) to (e) correspond to the samples of examples 1 to 5, respectively. The graph shows that the sample has good overall compactness and extremely low porosity, and the white round particles in the graph are metallic iron phases and are uniformly distributed in an alumina matrix. And there is a second phase precipitate between the metal phase and alumina because the S element is dissolved in the metal during high temperature sintering and precipitates at the phase boundary between the metal and the ceramic when the metal phase solidifies, using the sulfur-containing baiyuneboite concentrate. Comparing fig. 3(a) and fig. 3(e), the raw materials and process conditions are the same except that the iron concentrate contains different sulfur and manganese elements, and it can be seen that more MnS second phase is precipitated around the metal particles of the sample of example 5, which is the main reason for the best mechanical properties of the sample of example 5.
Fig. 4 is a diagram of the crack propagation path of the sample of example 1, in which (a) is a schematic diagram of crack propagation, (b) is an enlarged view of a black frame in (a), and (c) - (f) are energy spectra of (b), and the corresponding elements are iron, sulfur, manganese and aluminum. The crack extends from right to left along the grain boundary of the metal phase and the alumina from the lower part of the metal phase, and when the crack meets MnS, the crack does not continue to extend forwards, but deflects downwards and breaks through the alumina crystal. The fracture modes are mainly grain boundary fracture and transgranular fracture. Therefore, MnS precipitated around the metal phase can improve the interface bonding between the metal phase and the ceramic phase, and has a great effect on improving the mechanical property of the material.
Detailed Description
The preparation process flow of the iron ore concentrate cermet of the present invention can be as shown in fig. 1. The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
Example 1
1. Raw materials: weighing 40g of iron ore concentrate, 25g of bauxite, 20g of aluminum oxide and 15g of active carbon, wherein the total mass is 100 g. The chemical composition of the raw iron concentrate, alumina and bauxite are shown in table 1. The iron ore concentrate used was sulfur-containing baiyuneboite iron ore concentrate, and the iron ore concentrates in examples 2 to 5 described below were also all sulfur-containing baiyuneboite iron ore concentrate.
Table 1 chemical composition (wt%) of iron ore concentrate, alumina and bauxite used in example 1
2. The preparation method comprises the following steps:
putting the weighed raw materials into a planetary ball mill (QM-3SP2) for wet milling for 4h, wherein the ball-material ratio is 4:1, the ball milling medium is absolute ethyl alcohol, the rotating speed is 300rpm, and the obtained slurry is put into a constant temperature drying oven (WGL-45B) at 90 ℃ for drying for 24 h. The dried powder is placed in a tabletting machine (DY-20) for compression molding, the pressure is 30MPa, and the molded sample (cylindrical) has the diameter of 40mm and the thickness of about 4.5 mm. And (3) placing the sample in a tubular atmosphere furnace (SKL16BYL) for firing, wherein the sintering temperature is 1400 ℃, the heat preservation time is 180min, the protective gas is argon, the heating rate is 5 ℃/min, the argon flow rate is 2L/min, and after firing, cooling the sample to room temperature along with the furnace and taking out the sample.
Example 2
1. Raw materials: weighing 48g of iron ore concentrate, 22g of bauxite, 12g of aluminum oxide and 18g of graphite powder, wherein the total mass is 100 g. The chemical composition of the raw iron concentrate, alumina and bauxite are shown in table 2.
Table 2 chemical composition (wt%) of iron ore concentrate, alumina and bauxite used in example 2
2. The preparation method comprises the following steps: putting the weighed raw materials into a planetary ball mill (QM-3SP2) for wet milling for 4h, wherein the ball-material ratio is 4:1, the ball milling medium is acetone, the rotating speed is 300rpm, and the obtained slurry is put into a constant temperature drying oven (WGL-45B) at 90 ℃ for drying for 24 h. The obtained powder was press-molded by an isostatic press (DJYP-40T) under a pressure of 150MPa, and the molded sample had a diameter of 40mm and a thickness of about 4 mm. And (3) placing the sample in a tubular atmosphere furnace (SKL16BYL) for sintering, wherein the sintering temperature is 1450 ℃, the heat preservation time is 150min, the protective gas is nitrogen, the heating rate is 5 ℃/min, and the nitrogen flow rate is 2L/min, and after the sintering is finished, cooling the sample to the room temperature along with the furnace and taking out the sample.
Example 3
1. Raw materials: weighing 35g of iron ore concentrate, 30g of bauxite, 25g of aluminum oxide and 10g of aluminum powder, wherein the total mass is 100 g. The chemical composition of the raw iron concentrate, alumina and bauxite are shown in table 3.
Table 3 chemical composition (wt%) of iron ore concentrate, alumina and bauxite used in example 3
2. The preparation method comprises the following steps: putting the weighed raw materials into a planetary ball mill (QM-3SP2) for wet milling for 4h, wherein the ball-material ratio is 4:1, the ball milling medium is absolute ethyl alcohol, the rotating speed is 300rpm, and the obtained slurry is put into a constant temperature drying oven (WGL-45B) at 90 ℃ for drying for 24 h. The obtained powder is placed in a hot pressing sintering furnace (ZT-50-21Y) for sintering, the pressure is 30MPa, and the sintering system is as follows: vacuumizing to below 10Pa, heating to 1100 ℃, keeping the temperature for 1 hour, wherein the heating rate is 5 ℃/min; and continuously heating to 1350 ℃, heating at the speed of 4 ℃/min, slowly increasing the pressure to 30MPa, keeping the temperature and the pressure for 30min, cooling to room temperature along with the furnace after firing, and taking out the sample.
Example 4
1. Raw materials: 60g of iron ore concentrate, 10g of bauxite, 18g of aluminum oxide and 22g of aluminum powder are weighed, and the total mass is 100 g. The chemical composition of the raw iron concentrate, alumina and bauxite are shown in table 4.
Table 4 chemical composition (wt%) of iron ore concentrate, alumina and bauxite used in example 4
2. The preparation method comprises the following steps: putting the weighed raw materials into a planetary ball mill (QM-3SP2) for wet milling for 4h, wherein the ball-material ratio is 4:1, the ball milling medium is absolute ethyl alcohol, the rotating speed is 300rpm, and the obtained slurry is put into a constant temperature drying oven (WGL-45B) at 90 ℃ for drying for 24 h. The obtained powder is placed in a tablet press (DY-20) to be pressed and molded, the pressure is 35MPa, and the molded sample has the diameter of 40mm and the thickness of about 4.3 mm. The sample is sintered in a microwave sintering furnace (HY-MF3016), the microwave medium is graphite powder, and the microwave frequency is 2.45 GHz. The sintering system is as follows: and heating to 950 ℃, preserving the heat for 20min, cooling to room temperature along with the furnace after firing, and taking out the sample.
Example 5
To compare the effect of pyrite on cermet, the process conditions of this example were the same as those of example 1, but using iron ore concentrate with higher sulfur and manganese elements.
1. Raw materials: weighing 40g of iron ore concentrate, 25g of bauxite, 20g of aluminum oxide and 15g of active carbon, wherein the total mass is 100 g. The chemical composition of the raw iron concentrate, alumina and bauxite are shown in table 1.
Table 5 chemical composition (wt%) of iron ore concentrate, alumina and bauxite used in example 5
2. The preparation method comprises the following steps:
putting the weighed raw materials into a planetary ball mill (QM-3SP2) for wet milling for 4h, wherein the ball-material ratio is 4:1, the ball milling medium is absolute ethyl alcohol, the rotating speed is 300rpm, and the obtained slurry is put into a constant temperature drying oven (WGL-45B) at 90 ℃ for drying for 24 h. The dried powder is placed in a tabletting machine (DY-20) for compression molding, the pressure is 30MPa, and the molded sample (cylindrical) has the diameter of 40mm and the thickness of about 4.5 mm. And (3) placing the sample in a tubular atmosphere furnace (SKL16BYL) for firing, wherein the sintering temperature is 1400 ℃, the heat preservation time is 180min, the protective gas is argon, the heating rate is 5 ℃/min, the argon flow rate is 2L/min, and after firing, cooling the sample to room temperature along with the furnace and taking out the sample.
The XRD patterns and SEM images of the iron ore concentrate cermet samples obtained in examples 1-5 are shown in figures 2 and 3, and the crack propagation path of the iron ore concentrate cermet is shown in figure 4.
The performance alkalinity of the iron ore concentrate metal ceramic sample is detected according to the following detection standards: the density was tested according to GB/T9966.3-2001; the breaking strength is tested according to GB/T6569-2006; hardness was tested according to GB/T16534-2009; acid resistance (20% H)2SO4) And alkali resistance (20% NaOH) was measured according to JC/T258-93. The results are shown in Table 5.
TABLE 5 comprehensive properties of iron concentrate cermet samples prepared with iron of the examples
| Sample (I) | Density/g.cm-3 | Flexural strength/MPa | hardness/GPa | Alkali resistance/%) | Acid resistance/% |
| Example 1 | 4.14 | 301 | 13.12 | 98.66 | 93.40 |
| Example 2 | 4.18 | 270 | 12.78 | 98.45 | 92.89 |
| Example 3 | 3.99 | 283 | 12.67 | 98.31 | 93.14 |
| Example 4 | 4.06 | 291 | 12.98 | 98.47 | 93.22 |
| Example 5 | 4.19 | 335 | 13.24 | 98.69 | 93.49 |
The above description is only exemplary of the present invention and is not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. An iron ore concentrate cermet, which is characterized in that: comprises the following raw materials in percentage by mass: 30-60% of iron ore concentrate, 15-30% of bauxite, 10-30% of aluminum oxide and 10-30% of reducing agent; the iron ore concentrate contains sulfur and MnO2The iron ore concentrate of (1).
2. The iron concentrate cermet according to claim 1, characterized in that: the alumina content of the bauxite is 60-90%.
3. The iron concentrate cermet according to claim 1, characterized in that: the reducing agent is one or a mixture of more of activated carbon, graphite and aluminum powder.
4. A method of producing an iron concentrate cermet according to any one of claims 1-3, characterized in that: the method comprises the following steps:
(1) weighing the following raw materials in percentage by mass: 30-60% of iron ore concentrate, 15-30% of bauxite, 10-30% of aluminum oxide and 10-30% of reducing agent;
(2) the raw materials are fully and uniformly mixed through wet ball milling, and the slurry is further dried to obtain powder;
(3) and pressing and molding the powder, and then sintering the powder in a sintering furnace, or directly molding and sintering the powder in the sintering furnace to obtain the iron ore concentrate metal ceramic.
5. The method of preparing iron ore concentrate cermet according to claim 4, characterized in that: in the step (2), the ball milling medium is absolute ethyl alcohol or acetone, and the ball milling time is 0.5-4 h.
6. The method of preparing iron ore concentrate cermet according to claim 4, characterized in that: in the step (3), the molding pressure is 30-200 Mpa.
7. The method of preparing iron ore concentrate cermet according to claim 4, characterized in that: in the step (3), the sintering furnace comprises a normal pressure sintering furnace, a hot pressing sintering furnace, a microwave sintering furnace and a plasma discharge sintering furnace; the sintering temperature is 950-1450 ℃, and the heat preservation time is 30-180 minutes.
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