A method of separating high-chrome ilmenite

Abstract

The application provides a high-chromium type ilmenite sorting method and relates to the technical fields of metallurgy and mineral processing. Specifically, the sorting method comprises the following steps: step one, mixing and reacting the high-chromium type ilmenite with a coal-based reducing agent, performing first magnetic separation on the obtained reduction product to obtain a titanium concentrate and a first tailing; step two, performing second magnetic separation on the first tailing to obtain a second concentrate; step three, performing oxidation roasting on the second concentrate, performing third magnetic separation on the roasting product to obtain a third tailing; step four, performing electric separation on the third tailing to obtain a fourth concentrate; and step five, mixing and reacting the fourth concentrate with a coal-based reducing agent, performing fourth magnetic separation on the obtained reduction product to obtain a chromium concentrate. The application can simultaneously obtain high-grade titanium ore, chromium ore and a series of high-value process by-products, and has the advantages of simple method process, high resource recovery rate and easy industrial implementation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy and mineral processing, in particular to a separation method of high-chromium ilmenite. BACKGROUND

[0002] At present, the production scale of titanium dioxide and titanium sponge is increasingly expanding, and the consumption of titanium ore at home and abroad is increasing year by year. With the passage of time, the reserves of high-quality and easy-to-mine ilmenite are decreasing year by year. How to utilize ilmenite with high impurity content has become a technical problem to be solved at the present stage. The problem of chromium ore is even more serious. Since there is no free chromium in nature, it usually coexists with iron, magnesium, aluminum and other metals. The reserves and production of chromium ore in China are limited and mainly rely on imports. However, as a major producer of stainless steel, the demand for chromium ore is increasing. How to expand the source of chromium ore has also become a major problem to be solved at the present stage.

[0003] The high-chromium beach placer mainly distributes on the coastline or the delta zone of the estuary and belongs to a sedimentary mineral. It contains a large amount of gangue minerals and is usually separated by means of gravity separation, magnetic separation and the like. The high-chromium beach placer with high titanium grade is a potential high-quality titanium-rich material production raw material. At the same time, if it can be effectively separated, high-quality chromium-iron ore resources can also be obtained.

[0004] At the present stage, the ilmenite containing chromium is usually subjected to oxidation and reduction roasting, and then separated by means of magnetic separation and gravity separation. Only the titanium grade of the titanium concentrate product is concerned, and the index related to the chromium-iron ore is neglected. Therefore, the chromium grade in the chromium-iron ore is low, and the impurity content such as silicon is high. Therefore, a reasonable and efficient separation method is needed to reduce the impurity content in the chromium-iron ore while ensuring the grade of the titanium concentrate, so as to improve the grade of the chromium-iron ore.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The present application aims to provide a separation method of high-chromium ilmenite, which can solve the technical problems of resource waste or low separation efficiency caused by the fact that the existing separation process of ilmenite containing chromium cannot take into account the chromium grade. The separation method of the present application can obtain high-grade titanium concentrate, high-grade chromium concentrate and a series of high-value by-products, the process flow is easy to implement, and has a high resource recycling rate.

[0007] In order to achieve the above-mentioned purpose of the present application, the following technical scheme is adopted:

[0008] A separation method of high-chromium ilmenite, comprising the following steps:

[0009] Step one, mix and react high-chromium type ilmenite with coal-based reducing agent, carry out first magnetic separation on the reduction product obtained in the reaction to obtain titanium concentrate and first tailings;

[0010] Step two, carry out second magnetic separation on the first tailings to obtain second concentrate;

[0011] Step three, carry out oxidizing roasting on the second concentrate, and carry out third magnetic separation on the roasting product to obtain third tailings;

[0012] Step four, carry out electric separation on the third tailings to obtain fourth concentrate;

[0013] Step five, mix and react the fourth concentrate with coal-based reducing agent, and carry out fourth magnetic separation on the reduction product obtained in the reaction to obtain chromium concentrate;

[0014] The magnetic field strength of the first magnetic separation and the fourth magnetic separation is less than the magnetic field strength of the second magnetic separation; the magnetic field strength of the first magnetic separation and the fourth magnetic separation is greater than the magnetic field strength of the third magnetic separation.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] (1) The present application provides a sorting process for high-chromium type ilmenite to obtain titanium concentrate and high-grade chromium concentrate at the same time, and to obtain process by-products such as oxidized iron series minerals, recyclable coal-based reducing agent, and gangue with different compositions, respectively; the different products obtained in each step can be transported to different downstream industrial chains to achieve a high resource recovery rate of high-chromium type ilmenite.

[0017] (2) The sorting process provided by the present application can obtain titanium concentrate and high-grade chromium concentrate at the same time, wherein the chromium-iron ratio in the chromium concentrate is greater than 1.5, the content of oxidized chromium is greater than 55%, and part of the iron in the titanium concentrate is reduced to elemental iron, which is beneficial to the production of rich-titanium materials and has a wide range of application scenarios. The method process of the present application is simple and easy to implement industrially. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0019] Figure 1 A sorting process flowchart provided by Embodiment 1 of the present application is provided. DETAILED DESCRIPTION

[0020] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market. In addition, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0021] The present application is carried out by the following specific embodiments: a high-chromium ilmenite sorting method, comprising the following steps: step one, mixing and reacting high-chromium ilmenite with coal-based reducing agent, carrying out first magnetic separation on the reduction product obtained by reaction to obtain titanium concentrate and first tailings; step two, carrying out second magnetic separation on the first tailings to obtain second concentrate; step three, carrying out oxidizing roasting on the second concentrate, and carrying out third magnetic separation on the roasting product to obtain third tailings; step four, carrying out electric separation on the third tailings to obtain fourth concentrate; step five, mixing and reacting the fourth concentrate with coal-based reducing agent, and carrying out fourth magnetic separation on the reduction product obtained by reaction to obtain chromium concentrate; wherein the magnetic field strength of the first magnetic separation and the fourth magnetic separation is less than the magnetic field strength of the second magnetic separation; the magnetic field strength of the first magnetic separation and the fourth magnetic separation is greater than the magnetic field strength of the third magnetic separation.

[0022] The present application is used to solve the technical problem that the sorting process of ilmenite containing chromium cannot take into account the chromium grade. The sorting process can be used for any ilmenite containing chromium in theory, but in order to ensure the processing efficiency and obtain high-quality chromium concentrate, as a preferred embodiment, the present application uses high-chromium ilmenite as the initial raw material, such as high-chromium titanium ore material of beach placer, wherein the mass content of chromium, calculated as Cr2O3, should be at least ≥2%.

[0023] As a more preferred embodiment, the high-chromium ilmenite includes three elements of Ti, Fe and Cr, but according to different ore sources, the high-chromium ilmenite also includes unavoidable Mg, Mn, Ca, Si, Al, V or other small amount of impurity components; the high-chromium ilmenite used in the present application should at least include the following components in mass percentage: TiO2 30% to 45%, Fe2O3 40% to 60% and Cr2O3 3% to 8%.

[0024] In step one of the present application, the magnetic enhancement of ilmenite is achieved by the first high-temperature reduction reaction of step one, in view of the different reduction temperatures of ilmenite and chromite, so as to directly separate ilmenite in the subsequent first magnetic separation; in this step, both ferric iron and ferrous iron are reduced, and a large amount of elemental iron is obtained. The main chemical reactions involved in this step include:

[0025] Fe2TiO5+ 3CO = 2Fe + TiO2+ 3CO2;

[0026] FeTiO3+ CO = Fe + TiO2+ CO2.

[0027] As a preferred embodiment, the coal-based reducing agent includes at least one of bituminous coal, anthracite, lignite or semicoke.

[0028] As a preferred embodiment, the ratio of the addition amount of the coal-based reducing agent to the mass of the high-chromium ilmenite is 0.15-0.4:1 by mass.

[0029] As a preferred embodiment, in step one, the temperature of the mixing reaction is 800-950°C, and the time of the mixing reaction is 3-6h; as an optional embodiment, in step one, the temperature of the mixing reaction includes but is not limited to 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950(°C), and the time of the mixing reaction includes but is not limited to 3, 3.5, 4, 4.5, 5, 5.5, 6(h), and the involved parameter values can adopt the point values given above or any real value within the parameter interval constituted by the point values.

[0030] In step one of the present application, the dry magnetic separation in a medium magnetic field is used to separate ilmenite concentrate and first tailings; by utilizing the difference in magnetic permeability between mineral components, the medium magnetic mineral ilmenite concentrate is obtained, and the first tailings mainly include components such as chromite, coal-based reducing agent fine particles or coal-based reducing agent ash.

[0031] As a preferred embodiment, in step one, the magnetic field strength of the first magnetic separation is 3000-6000GS; as an optional embodiment, the magnetic field strength of the first magnetic separation includes but is not limited to any value or a value interval constituted by any two values in 3000, 3200, 3500, 3800, 4000, 4500, 5000, 5500, 5800, 6000(GS).

[0032] As a preferred embodiment, since the effect of magnetic separation is related to the granularity of the mineral, before each magnetic separation in the present application, the mineral can be crushed and screened according to the actual situation to achieve higher magnetic separation efficiency. As a more preferred embodiment, in the first magnetic separation, the granularity of the reduction product is -20 mesh to +325 mesh.

[0033] In step two of the present application, the first tailings obtained in step one are further screened by high-intensity magnetic separation to obtain a second concentrate and a second tailings, wherein the effective component in the second concentrate is chromite, and the second tailings mainly include gangue and unreacted coal-based reducing agent. The gangue is a useless solid material associated with the effective mineral component, and in the present application, the gangue component in the second tailings mainly includes quartz, silicate, aluminosilicate, aluminum oxide, etc.

[0034] As a preferred embodiment, in step two, the magnetic field strength of the second magnetic separation is 9000GS to 12000GS; as an optional embodiment, the magnetic field strength of the second magnetic separation includes but is not limited to any of 9000, 9200, 9500, 9800, 10000, 10500, 11000, 11500, 11800, 12000 (GS) or a numerical interval formed by any two of them.

[0035] In step three of the present application, the second concentrate obtained in the previous step is subjected to oxidation roasting; it can be found that there are reduction roasting and separation steps in steps one and five respectively, and the process of oxidation roasting is added between the two reductions to further oxidize the iron oxides other than chromite to enhance the magnetism of the iron oxides, thereby achieving the purpose of removing free iron and improving the ratio of chromium to iron in the magnetic separation process in step three.

[0036] Reasonably control the temperature and time of oxidation roasting to achieve sufficient oxidation of iron, so that most of it is converted into trivalent iron oxide with strong magnetism. As a preferred embodiment, in step three, the temperature of the oxidation roasting is 650℃ to 800℃, and the time of the oxidation roasting is 20min to 60min; as an optional embodiment, the temperature of the oxidation roasting includes but is not limited to 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800 (℃), and the time of the oxidation roasting includes but is not limited to 20, 25, 30, 35, 40, 45, 50, 55, 60 (min), the involved parameter values can adopt the point values given above, or any real value within the parameter interval formed by the point values.

[0037] In step three of the application, a low magnetic field strength is used to implement dry magnetic separation, and the oxidized high-magnetic iron-based minerals can be separated by a lower magnetic field strength; as a preferred embodiment, in step three, the magnetic field strength of the third magnetic separation is 1000GS-2000GS; as an optional embodiment, the magnetic field strength of the third magnetic separation includes but is not limited to any of 1000, 1050, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 (GS) or a numerical interval formed by any two of them.

[0038] In step four of the application, the tailings component obtained by the oxidation roasting and magnetic separation in step three is subjected to electric separation, which can effectively remove the associated zirconium silicate (zircon sand) and part of the non-conductive gangue components in the high-chromium titanomagnetite, reduce the harmful elements in the chromium concentrate, and expand the downstream application range.

[0039] The electric separation voltage is reasonably set to obtain a suitable high-voltage electric field, and the difference in electrical conductivity between the chromium ore and other associated components is used to further purify the chromium ore; as a preferred embodiment, in step four, the voltage of the electric separation is 18000V-22000V; as an optional embodiment, the voltage of the electric separation includes but is not limited to any of 18000, 18500, 19000, 20000, 20500, 21000, 21500, 22000 (V) or a numerical interval formed by any two of them.

[0040] As a preferred embodiment, the third tailings are heated before being fed to the electric separation, and the heating temperature is 120℃-150℃; as an optional embodiment, the heating temperature of the feed before electric separation includes but is not limited to any of 120, 125, 130, 135, 140, 145, 150 (℃) or a numerical interval formed by any two of them.

[0041] In step five of the application, most of the impurities are removed and the magnetic property of the chromium concentrate is enhanced by performing a second high-temperature reduction, thereby obtaining a chromium concentrate with high chromium grade, which creates a good foundation for its application in downstream industries such as alloy smelting and electric furnace melting.

[0042] Reasonably control the temperature and implementation of this high temperature reduction, to maximize the high-purity chromium ore; as a preferred embodiment, in step five, the temperature of the mixed reaction is 1250℃-1350℃, and the time of the mixed reaction is 3h-6h; as an alternative embodiment, in step five, the temperature of the mixed reaction includes but is not limited to 1250, 1260, 1270, 1280, 1290, 1300, 1310, 1320, 1330, 1340, 1350(℃), and the time of the mixed reaction includes but is not limited to 3, 3.5, 4, 4.5, 5, 5.5, 6(h), the parameter values involved can adopt the point values given above, or any real value within the parameter interval composed of the point values.

[0043] As a preferred embodiment, in step five, the ratio of the mass of the coal-based reducing agent to the mass of the fourth concentrate is 0.15-0.3:1.

[0044] In step five of the present application, the chromium concentrate and the fifth tailings are obtained by dry magnetic separation in a medium magnetic field strength; wherein the main component of the fifth tailings is the unreacted coal-based reducing agent, and the impurity components including a small amount of quartz, silicate, silico-aluminate, alumina, etc.

[0045] As a preferred embodiment, in step five, the magnetic field strength of the fourth magnetic separation is 3000GS-6000GS; as an alternative embodiment, the magnetic field strength of the fourth magnetic separation includes but is not limited to any value or a value interval composed of any two values in 3000, 3200, 3500, 3800, 4000, 4500, 5000, 5500, 5800, 6000(GS).

[0046] Example 1

[0047] A sorting method of high-chromium ilmenite, comprising the following steps:

[0048] (1) Take the high-chromium ilmenite sand from a coastal sand mine, and test the composition of ilmenite as shown in Table 1.

[0049] Table 1

[0050] Composition Al2O3 CaO Cr2O3 Fe2O3 MgO MnO SiO2 TiO2 High-chrome ilmenite 1.69 0.04 3.91 50.58 0.87 1.00 1.33 38.49

[0051] (2) Mix the high-chromium ilmenite with bituminous coal at a ratio of 1:0.3, and reduce and calcine at 900℃ for 5h; perform magnetic separation on the calcined reduction product, and obtain titanium concentrate and first tailings at a magnetic field strength of 4500GS; wherein the composition of the titanium concentrate is shown in Table 2.

[0052] Table 2

[0053] Composition TiO2 Fe SiO2 Al2O3 CaO MgO Cr2O3 Titanium concentrate 47.06 39.30 1.19 0.28 0.08 0.48 0.13

[0054] (3) The first tailings obtained in step (2) are subjected to magnetic separation, and a second concentrate and a second tailings are obtained, wherein the magnetic field strength is 10500 GS.

[0055] Table 3

[0056] Composition MgO Al2O3 SiO2 Fe2O3 CaO TiO2 Cr2O3 Second concentrate 3.53 12.92 9.10 26.68 1.43 8.32 32.56

[0057] (4) The second concentrate obtained in step (3) is subjected to oxidation roasting at 700℃ for 40 min, and the oxidation product is subjected to magnetic separation, and a third concentrate and a third tailings are obtained, wherein the magnetic field strength is 1500 GS.

[0058] (5) The third tailings obtained in step (4) are preheated to 150℃, and then are fed to electric separation, and a fourth concentrate and a fourth tailings are obtained, wherein the voltage is set to 20000V.

[0059] (6) The fourth concentrate obtained in step (5) is mixed with bituminous coal at a ratio of 1:0.25, and is subjected to reduction roasting at 1300℃ for 5h, and the reduction product is subjected to magnetic separation, and a concentrate is obtained, wherein the magnetic field strength is 4500 GS, and the concentrate corresponds to a chromium concentrate; wherein the chromium concentrate is subjected to composition detection, and mainly includes Cr2O3 62.74% and FeO 17.49%.

[0060] Example 2

[0061] The example is basically the same as example 1, and the only difference is that:

[0062] In step (2), the reduction roasting is performed at 800℃ for 6h;

[0063] In step (4), the oxidation roasting is performed at 650℃ for 60min;

[0064] In step (5), the reduction roasting is performed at 1250℃ for 6h.

[0065] The composition of the ilmenite obtained in step (1) of the example is shown in Table 4.

[0066] Table 4

[0067] Composition TiO2 Fe SiO2 Al2O3 CaO MgO Cr2O3 High-chrome ilmenite 46.57 42.30 1.03 0.43 0.06 0.60 0.18

[0068] The main components of the chromium concentrate obtained in step (6) of the example are: Cr2O3 60.87% and FeO 18.43%.

[0069] Example 3

[0070] The example is basically the same as example 1, and the only difference is that:

[0071] reduction calcination at 950°C for 3h in step (2);

[0072] oxidation roasting at 800°C for 20min in step (4);

[0073] reduction calcination at 1350°C for 3h in step (5).

[0074] The composition of ilmenite obtained in step (1) of this example is shown in Table 5 below.

[0075] Table 5

[0076] Composition TiO2 Fe SiO2 Al2O3 CaO MgO Cr2O3 High-chrome ilmenite 45.39 43.69 1.11 0.45 0.07 0.78 0.23

[0077] The composition of ilmenite obtained in step (1) of this example is shown in Table 5 below.

[0078] Example 4

[0079] The same as Example 1 except that:

[0080] the magnetic field strength in step (2) was 3000 GS;

[0081] the magnetic field strength in step (3) was 9000 GS;

[0082] the magnetic field strength in step (4) was 1000 GS;

[0083] the voltage in step (5) was 18000 V;

[0084] the magnetic field strength in step (6) was 3000 GS.

[0085] The composition of ilmenite obtained in step (1) of this example is shown in Table 6 below.

[0086] Table 6

[0087] Composition TiO2 Fe SiO2 Al2O3 CaO MgO Cr2O3 High-chrome ilmenite 44.28 37.54 1.89 0.75 0.10 0.83 0.29

[0088] The composition of ilmenite obtained in step (1) of this example is shown in Table 5 below.

[0089] Example 5

[0090] The same as Example 1 except that:

[0091] the magnetic field strength in step (2) was 6000 GS;

[0092] the magnetic field strength in step (3) was 12000 GS;

[0093] The magnetic field strength in step (4) is 2000 GS;

[0094] The voltage in step (5) is 22000 V;

[0095] The magnetic field strength in step (6) is 6000 GS.

[0096] The composition of ilmenite obtained in step (1) of this example is:

[0097] Table 7

[0098] Composition TiO2 Fe SiO2 Al2O3 CaO MgO Cr2O3 High-chrome ilmenite Composition Fe CaO MgO High-chrome ilmenite 45.18 40.86 0.98 0.37 0.07 0.57 0.15

[0099] The composition of chromium concentrate obtained in step (6) of this example is: Cr203 59.49% and FeO 19.71%.

[0100] Comparative Example 1

[0101] The same as Example 1, except that step (4) is cancelled, and the second concentrate obtained in step (3) is directly used in the electric separation of step (5).

[0102] The composition of chromium concentrate obtained in step (6) of this comparative example is: Cr203 50.26% and FeO 27.37%.

[0103] Comparative Example 2

[0104] The same as Example 1, except that the reduction and calcination in step (6) is cancelled, and the fourth concentrate obtained in step (5) is directly used in the magnetic separation of step (6).

[0105] The composition of chromium concentrate obtained in step (6) of this comparative example is: Cr203 41.54% and FeO 32.96%.

[0106] Although the present application has been illustrated and described with reference to specific embodiments, it is to be understood that the above examples are merely illustrative of the present application and are not to be taken as limiting the present application in any way. It is understood that the present application covers all modifications, equivalents and alternatives falling within the spirit and scope of the present application. Accordingly, the scope of the present application is to be interpreted in the broadest manner allowable by law.

Claims

1. A method of beneficiation of high-chrome ilmenite, characterized in that, The sorting method comprises the following steps: Step one, mixing and reacting high-chromium type ilmenite with coal-based reducing agent, and performing first magnetic separation on the reduction product obtained in the reaction to obtain titanium concentrate and first tailings; Step two, performing second magnetic separation on the first tailings to obtain second concentrate; Step three, performing oxidizing roasting on the second concentrate, and performing third magnetic separation on the roasting product to obtain third tailings; Step four, performing electric separation on the third tailings to obtain fourth concentrate; Step five, mixing and reacting the fourth concentrate with coal-based reducing agent, and performing fourth magnetic separation on the reduction product obtained in the reaction to obtain chromium concentrate; The magnetic field strength of the first magnetic separation and the fourth magnetic separation is less than the magnetic field strength of the second magnetic separation; the magnetic field strength of the first magnetic separation and the fourth magnetic separation is greater than the magnetic field strength of the third magnetic separation.

2. The method of separating high-chrome ilmenite according to claim 1, characterized in that, The high-chromium type ilmenite comprises the following components in percentage by mass: TiO2 30%~45%, Fe2O3 40%~60% and Cr2O3 3%~8%.

3. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step one, the temperature of the mixing reaction is 800℃~950℃, and the time of the mixing reaction is 3h~6h.

4. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step one, the magnetic field strength of the first magnetic separation is 3000GS~6000GS.

5. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step two, the magnetic field strength of the second magnetic separation is 9000GS~12000GS.

6. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step three, the temperature of the oxidizing roasting is 650℃~800℃, and the time of the oxidizing roasting is 20min~60min.

7. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step three, the magnetic field strength of the third magnetic separation is 1000GS~2000GS.

8. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step four, the voltage of the electric separation is 18000V~22000V.

9. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: The third tailings are heated before being fed to the electric separation, and the temperature of the heating is 120℃~150℃.

10. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step five, the temperature of the mixing reaction is 1250℃~1350℃, and the time of the mixing reaction is 3h~6h.

11. The method of claim 1, wherein the high-chrome ilmenite is separated by a method comprising: In step five, the magnetic field strength of the fourth magnetic separation is 3000GS~6000GS.

Images