METHOD FOR PRODUCING FERRONICKEL AND REMOVING CHROMIUM FROM NICKEL LATERITE ORE

Abstract

A method for producing ferronickel and removing chromium from nickel laterite ore, including the following steps: (1) subjecting the nickel laterite ore to ore washing and separating to obtain an ore slurry and a mineral aggregate, adding an alkali liquor and a bromate and introducing oxygen to the ore slurry to allow oxidation leaching, and then conducting solid-liquid separation to obtain a solid and a chromium-containing filtrate; (2) subjecting the solid obtained in step (1) to washing and solid-liquid separation to obtain a solid phase and washing water, and mixing the solid phase with quicklime and a reducing agent to obtain a mixture; and (3) subjecting the mixture obtained in step (2) to roasting and smelting successively to obtain a finished ferronickel product. The method achieves enrichment of chromium, and produces ferronickel through smelting of the nickel laterite ore while removing the impurity chromium, protecting the safety of a furnace.

Claims

1. A method for producing ferronickel and removing chromium from nickel laterite ore, comprising the following steps: (1) subjecting the nickel laterite ore to ore washing and separating to obtain an ore slurry and a mineral aggregate, adding an alkali liquor and a bromate and introducing oxygen to the ore slurry to allow oxidation leaching, and then conducting solid-liquid separation to obtain a solid and a chromium-containing filtrate; (2) subjecting the solid obtained in step (1) to washing and solid-liquid separation to obtain a solid phase and washing water, and mixing the solid phase with quicklime and a reducing agent to obtain a mixture; and (3) subjecting the mixture obtained in step (2) to roasting and smelting successively to obtain a finished ferronickel product.

2. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (1), the ore slurry has a solid content of 10% to 25%.

3. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, further comprising: subjecting the mineral aggregate obtained in step (1) to crushing and re-separation in a shaker to obtain chromium concentrate and tailings, and returning the tailings for the ore washing.

4. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (1), for the oxidation leaching, a mass ratio of the alkali liquor to the bromate to the ore slurry is (0.5-1):(1-2):100.

5. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (1), the oxidation leaching is conducted under an enclosed condition, and a pressure of the oxygen is 1.5 MPa to 4 MPa.

6. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (1), the oxidation leaching is conducted at a temperature of 100 C. to 150 C. for 1 h to 5 h.

7. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein the washing water obtained in step (2) is returned to step (1) for the ore washing.

8. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (2), a mass ratio of the quicklime to the reducing agent to the solid phase is (2-10):(3-8):100.

9. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (3), the roasting is conducted at a temperature of 600 C. to 1,000 C. for 10 min to 50 min.

10. The method for producing ferronickel and removing chromium from nickel laterite ore according to claim 1, wherein in step (3), the smelting is conducted at a temperature greater than or equal to 1,500 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The sole FIGURE is a schematic diagram illustrating a process flow of a method of Example 1 of the present disclosure.

DETAILED DESCRIPTION

[0056] The present disclosure is further described below in conjunction with specific examples. The particle size and composition of the nickel laterite ore used in Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1, wherein the term yield refers to the percentage of the relevant particle size in the whole.

TABLE-US-00001 TABLE 1 Particle size and composition of the nickel laterite ore Particle size/mm Yield/% Ni Fe MgO Al.sub.2O.sub.3 Cr.sub.2O.sub.3 Co SiO.sub.2 10 0.51 1.31 7.09 30.76 2.92 0.5 0.02 39.37 10 > x 3 0.75 0.6 18.34 17.84 6.68 1.2 0.07 32.08 3 > x 2 0.31 0.43 17.51 19.37 6.09 1.26 0.06 35.56 2 > x 1 0.6 0.32 12.6 22.14 5.7 1.24 0.06 39.43 1 > x 0.55 0.72 0.37 10.5 24.07 6.3 1.82 0.13 10.92 0.55 > x 0.2 2.57 0.66 13.33 19.9 9.84 5.53 0.31 32.12 0.2 > x 0.1 0.71 0.75 17.73 14.87 14.43 10.74 0.32 21.88 0.1 > x 0.05 3.01 0.93 23.88 10.85 12.91 7.91 0.34 18.51 0.05 > x 90.82 1.14 43.38 1.16 7.43 2.35 0.08 6.71 Total 100 1.1 40.96 2.65 7.66 2.63 0.1 8.71

Example 1

[0057] As shown in the sole FIGURE, a method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0058] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 20%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 4 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0059] (2) sodium hydroxide and sodium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 1:1.5:100, oxygen was introduced under an oxygen pressure of 3 MPa, and under an enclosed condition, a resulting system was heated to 130 C. to allow oxidation leaching for 2 h under stirring at a rotational speed of 200 r/min; [0060] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0061] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0062] (5) quicklime, semi-coke, and the solid obtained in step (4) were mixed in a mass ratio of 10:8:100 and a resulting mixture was made to pellets with a particle size of 20 mm; [0063] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 900 C. for 20 min; and [0064] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,600 C. to obtain a finished ferronickel product.

Example 2

[0065] A method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0066] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 18%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 3.5 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0067] (2) sodium hydroxide and sodium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 0.9:1.3:100, oxygen was introduced under an oxygen pressure of 2.5 MPa, and under an enclosed condition, a resulting system was heated to 120 C. to allow oxidation leaching for 3 h under stirring at a rotational speed of 250 r/min; [0068] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0069] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0070] (5) quicklime, semi-coke, and the solid obtained in step (4) were mixed in a mass ratio of 7:6:100 and a resulting mixture was made to pellets with a particle size of 17 mm; [0071] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 850 C. for 25 min; and [0072] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,700 C. to obtain a finished ferronickel product.

Example 3

[0073] A method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0074] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 15%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 3 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0075] (2) sodium hydroxide and potassium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 0.8:1:100, oxygen was introduced under an oxygen pressure of 2 MPa, and under an enclosed condition, a resulting system was heated to 110 C. to allow oxidation leaching for 4 h under stirring at a rotational speed of 300 r/min; [0076] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0077] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0078] (5) quicklime, anthracite, and the solid obtained in step (4) were mixed in a mass ratio of 4:4:100 and a resulting mixture was made to pellets with a particle size of 15 mm; [0079] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 800 C. for 30 min; and [0080] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,800 C. to obtain a finished ferronickel product.

Comparative Example 1 (Which Was Different from Example 1 Only in That the High-Pressure Oxygen Was Not Introduced During the Oxidation Leaching of the Ore Slurry)

[0081] A method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0082] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 20%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 4 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0083] (2) sodium hydroxide and sodium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 1:1.5:100, and under an enclosed condition, a resulting system was heated to 130 C. to allow a reaction for 2 h under stirring at a rotational speed of 200 r/min; [0084] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0085] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0086] (5) quicklime, semi-coke, and the solid obtained in step (4) were mixed in a mass ratio of and a resulting mixture was made to pellets with a particle size of 20 mm; [0087] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 900 C. for 20 min; and [0088] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,600 C. to obtain a finished ferronickel product.

Comparative Example 2 (Which Was Different from Example 2 Only in That the High-Pressure Oxygen Was Not Introduced During the Oxidation Leaching of the Ore Slurry)

[0089] A method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0090] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 18%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 3.5 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0091] (2) sodium hydroxide and sodium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 0.9:1.3:100, and under an enclosed condition, a resulting system was heated to 120 C. to allow oxidation leaching for 3 h under stirring at a rotational speed of 250 r/min; [0092] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0093] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0094] (5) quicklime, semi-coke, and the solid obtained in step (4) were mixed in a mass ratio of 7:6:100 and a resulting mixture was made to pellets with a particle size of 17 mm; [0095] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 850 C. for 25 min; and [0096] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,700 C. to obtain a finished ferronickel product.

Comparative Example 3 (Which Was Different from Example 3 Only in That the High-Pressure Oxygen Was Not Introduced During the Oxidation Leaching of the Ore Slurry)

[0097] A method for producing ferronickel and removing chromium from nickel laterite ore was provided, including the following steps: [0098] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 15%; the ore slurry was subjected to oxidation leaching, the mineral aggregate was subjected to crushing to a particle size of 1.5 mm or less and re-separation in a shaker with a water flow rate of 3 L/min to obtain chromium concentrate and tailings, and the tailings were returned to the ore washing procedure; [0099] (2) sodium hydroxide and potassium bromate were added to the ore slurry in a mass ratio of sodium hydroxide to sodium bromate to the ore slurry of 0.8:1:100, and under an enclosed condition, a resulting system was heated to 110 C. to allow oxidation leaching for 4 h under stirring at a rotational speed of 300 r/min; [0100] (3) after the oxidation leaching in step (2) was completed, solid-liquid separation was conducted by a pressure filter to obtain a chromium-containing filtrate and a filter cake, and the chromium-containing filtrate and the chromium concentrate were sent to a chromium processing plant; [0101] (4) the filter cake was subjected to further washing with clean water and pressure filtration to obtain a liquid and a solid, and the liquid was sent for the ore washing and the solid was used in the following step; [0102] (5) quicklime, anthracite, and the solid obtained in step (4) were mixed in a mass ratio of 4:4:100 and a resulting mixture was made to pellets with a particle size of 15 mm; [0103] (6) the pellets were subjected to roasting in a rotary kiln at a temperature of 800 C. for 30 min; and [0104] (7) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,800 C. to obtain a finished ferronickel product.

Comparative Example 4

[0105] A method for producing ferronickel by smelting nickel laterite ore was provided, including the following steps: [0106] (1) the nickel laterite ore as raw ore was subjected to ore washing in a cylindrical ore washer, a trough ore washer, and a hydrocyclone successively and separation to obtain an ore slurry and a mineral aggregate, wherein the ore washing is conducted with water, the hydrocyclone gives nickel laterite ore with a particle size of 0.05 mm, and a solid content of the ore slurry is controlled at 15%; [0107] (2) quicklime and semi-coke were added into the ore slurry obtained in step (1) in a mass ratio of the ore slurry to quicklime to semi-coke of 100:10:8, and a resulting mixture was made to pellets with a particle size of 20 mm; [0108] (3) the pellets were subjected to roasting in a rotary kiln at a temperature of 850 C. for 25 min; and [0109] (4) the roasted pellets were subjected to smelting in an electric furnace at a temperature of 1,800 C. to obtain a finished ferronickel product.

Test Example

[0110] 1. The chemical compositions of the chromium concentrates obtained in Examples 1 to 3 and the mineral aggregate in Comparative Example 4 each were tested, and test results were shown in Table 2.

TABLE-US-00002 TABLE 2 Chemical composition test results (%) Ni Fe MgO Al.sub.2O.sub.3 Cr.sub.2O.sub.3 Co SiO.sub.2 Example 1 0.12 14.97 13.03 28.37 36.37 0.25 0.29 Example 2 0.12 15.23 12.89 28.48 36.63 0.24 0.30 Example 3 0.15 15.01 12.54 28.26 36.87 0.26 0.28 Mineral aggregate 0.67 13.98 14.28 8.11 4.39 0.23 21.45 in Comparative Example 4

[0111] It can be seen from Table 2 that a percentage of Cr.sub.2O.sub.3 in the chromium concentrate obtained by the method for producing ferronickel and removing chromium from nickel laterite ore of the present disclosure is 36.37% or higher, which achieves the enrichment of chromium and reduces a chromium content in tailings. [0112] 2. The chromium-containing filtrates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 each were tested for a chromium concentration, and test results were shown in Table 3.

TABLE-US-00003 TABLE 3 Chromium concentrations in the chromium-containing filtrate Cr (g/Kg) Leaching rate/% Example 1 1.59 99.3 Example 2 1.38 95.7 Example 3 1.13 93.4 Comparative Example 1 0.91 56.8 Comparative Example 2 0.78 54.1 Comparative Example 3 0.61 50.4

[0113] It can be seen from Table 3 that a concentration of Cr in the chromium-containing filtrate obtained by the method for producing ferronickel and removing chromium from nickel laterite ore of the present disclosure reaches 1.13 g/kg or higher, and a leaching rate of chromium reaches 93.4% or higher, indicating that the chromium element is well separated from the ore slurry to reduce a chromium content in the raw material for ferronickel production, which protects a furnace and reduces a chromium impurity content in the ferronickel. In addition, it can be seen from the comparison between Example 1 and Comparative Example 1, between Example 2 and Comparative Example 2, and between Example 3 and Comparative Example 3 that, when the high-pressure oxygen is not introduced during the oxidation leaching of the ore slurry, the leaching of chromium in the ore slurry is greatly reduced. [0114] 3. The finished ferronickel products obtained in Examples 1 to 3 and Comparative Examples 1 to 4 each were tested for a chromium content, and test results were shown in Table 4.

TABLE-US-00004 TABLE 4 Chromium content in the finished ferronickel product Cr/% Example 1 0.006 Example 2 0.034 Example 3 0.053 Comparative Example 1 0.14 Comparative Example 2 0.077 Comparative Example 3 0.12 Comparative Example 4 0.23

[0115] It can be seen from Table 4 that a concentration of Cr in the finished ferronickel product obtained by the method for producing ferronickel and removing chromium from nickel laterite ore of the present disclosure is lower than 0.053%. In addition, it can be seen from the comparison between Example 1 and Comparative Example 1, between Example 2 and Comparative Example 2, and between Example 3 and Comparative Example 3 that, when the high-pressure oxygen is not introduced during the oxidation leaching of the ore slurry, the chromium content in the final ferronickel product is increased.

[0116] The above examples are preferred implementations of the present disclosure. However, the implementations of the present disclosure are not limited by the above examples. Any change, modification, substitution, combination, and simplification made without departing from the spiritual essence and principle of the present disclosure should be an equivalent replacement manner, and all are included in the protection scope of the present disclosure.