Curing roasting-water leaching-normal pressure acid leaching treatment method for lateritic nickel ore

Abstract

A curing roasting-water leaching-normal pressure acid leaching treatment method for a lateritic nickel ore, relating to the technical field of metal smelting. The treatment method comprises the following steps: uniformly mixing lateritic nickel ore dry powder, concentrated sulfuric acid and sodium fluoride, and then carrying out curing roasting in a reducing atmosphere to obtain a cured material; carrying out water leaching on the cured material, and filtering to obtain a water leaching solution and water leaching residues; and carrying out normal-pressure acid leaching on the water leaching residues, and filtering to obtain an acid leaching solution and acid leaching residues. The treatment method has the characteristics of controllable reaction, short reaction period, low reaction energy consumption and relatively low production cost; and compared with a conventional high-pressure acid leaching treatment process, the treatment method can significantly reduce the acid consumption, reduce the loss of valuable metals such as cobalt and nickel, increase the metal recovery rate and improve the economic benefit of production. The treatment method can reduce the corrosion of a strong oxidant to equipment, reduce the emission of a waste liquid in the leaching process and reduce the production cost while effectively guaranteeing the cobalt-nickel leaching rate.

Description

A method for treating laterite nickel ore by slaking, roasting, water leaching and acid leaching at normal pressure Technical Field

[0001] The invention relates to the technical field of metal smelting, in particular to a laterite nickel ore slaking-roasting-water leaching-normal pressure acid leaching treatment method. Background Art

[0002] Currently, the processing of high-iron, low-magnesium limonite-type laterite nickel ores generally utilizes hydrometallurgical techniques, broadly categorized as reduction roasting-ammonia leaching, high-pressure acid leaching, and atmospheric pressure leaching. The reduction roasting-ammonia leaching (Caron) process is suitable for processing laterite nickel ores with MgO contents exceeding 10%, offering advantages such as reagent recycling and low costs. However, it also suffers from low nickel and cobalt recovery rates (75%-80% for nickel and less than 50% for cobalt). Brazilian nickel companies use the Caron process to extract nickel from raw ore, achieving a nickel recovery rate of 70%-75%. With technological advancements, other processes have been developed, including sulfur-addition reduction roasting-ammonia leaching, reduction roasting-acid leaching, oxidation roasting-acid leaching, chlorination roasting-water leaching, sulfation roasting-water leaching, and alkaline roasting-pressure acid leaching. However, these processes have yet to achieve industrial application. High-pressure acid leaching (HPAL) offers advantages such as low energy consumption, low carbon emissions, and high nickel and cobalt recoveries (>90%), making it the primary technology for processing limonitic red nickel ore both domestically and internationally. However, this process requires high magnesium (<5%) and aluminum content in the raw ore, as these easily precipitate and scale, leading to severe corrosion of the equipment. Atmospheric pressure leaching, which utilizes appropriate surfactants and microwave enhancement during the leaching process, can improve the leaching rate of valuable metals in laterite nickel ore. This method offers advantages such as low energy consumption, simple process, compact equipment, and easy control of operation. However, it suffers from disadvantages such as low leaching rate, difficulty in leachate separation, and high nickel content in the leached residue.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies and propose a method for treating laterite nickel ore by slaking, roasting, water leaching and acid leaching at normal pressure, so as to solve the technical problems of low nickel and cobalt leaching rate and easy corrosion of equipment in the leaching method of limonite-type laterite nickel ore in the prior art.

[0005] The present invention provides a laterite nickel ore slaking-water leaching-normal pressure acid leaching method, comprising the following steps:

[0006] Pretreatment: The laterite nickel ore is subjected to impurity removal, crushing, drying, ball milling and sieving to obtain laterite nickel ore dry powder;

[0007] Matured roasting: Mix laterite nickel ore dry powder, concentrated sulfuric acid and sodium fluoride evenly, and then perform matured roasting under a reducing atmosphere to obtain matured material;

[0008] Water soaking: soak the cooked material in water, and filter to obtain the water soaking liquid and water soaking residue;

[0009] Atmospheric pressure acid leaching: The water leaching residue is subjected to atmospheric pressure acid leaching, and the acid leaching liquid and acid leaching residue are obtained after filtration.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] The present invention utilizes a laterite nickel ore slaking, roasting, water leaching, and atmospheric pressure acid leaching process, resulting in a controllable reaction, a short reaction cycle, low reaction energy consumption, and low production costs. Compared to conventional high-pressure acid leaching processes, this method significantly reduces acid consumption, reduces the loss of valuable metals such as cobalt and nickel, improves metal recovery, and increases the economic benefits of production. The treatment method of the present invention effectively ensures the leaching rate of cobalt and nickel while reducing corrosion of equipment by strong oxidants, lowering the discharge of wastewater during the leaching process, and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG1 is a process flow chart of an embodiment of a laterite nickel ore slaking-roasting-water leaching-normal pressure acid leaching treatment method provided by the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0014] Referring to FIG1 , the present invention provides a method for treating laterite nickel ore by roasting, water leaching, and acid leaching at normal pressure, comprising the following steps:

[0015] Step S1, pretreatment: removing impurities, crushing, drying, ball milling, and sieving the laterite nickel ore to obtain laterite nickel ore dry powder.

[0016] Step S2, calcination: Mix the laterite nickel ore powder, concentrated sulfuric acid and sodium fluoride evenly, and then calcine in a reducing atmosphere to obtain a calcined material. The calcination step is beneficial to converting Ni oxide into sulfate and converting most of the goethite in the original ore into insoluble hematite, which is beneficial to reducing the iron content in the subsequent water leaching solution; at the same time, Cr 6+ Reduced to Cr 3+ , which is beneficial to the removal of chromium ions.

[0017] Step S3, water leaching: The slaking material is water-leached and filtered to obtain a water leaching solution and a water leaching residue. The water leaching step can leach most of the nickel and cobalt in the slaking material and suppress the leaching of iron. The pH of the obtained water leaching solution is 1-3.

[0018] Step S4, atmospheric pressure acid leaching: The water leaching residue is subjected to atmospheric pressure acid leaching, and the acid leaching solution and acid leaching residue are filtered. This atmospheric pressure acid leaching step further recovers nickel and cobalt from the water leaching residue, thereby increasing the leaching rate of nickel and cobalt. By using the acid leaching process of the present invention, the nickel content in the acid leaching residue can be reduced to 0.005%-0.15%.

[0019] The principle of the present invention is as follows: Goethite (FeOOH) is one of the main components of laterite nickel ore. The reaction between goethite and concentrated sulfuric acid proceeds spontaneously, but temperature has little effect on this reaction. In the presence of sodium fluoride, the reaction between goethite and concentrated sulfuric acid proceeds more readily as the temperature increases. This is the key mechanism of the present invention: sodium fluoride and concentrated sulfuric acid promote the maturation of laterite nickel ore powder. Simultaneously, during the maturation process, as the temperature rises, the Gibbs free energy of the reaction between NiFe2O4, Fe2O3, and Fe3O4 and sulfuric acid slowly increases, indicating a decrease in the extent of the reaction, which facilitates the separation of the iron oxide sediment. As the temperature rises, the Gibbs free energy of the reaction between NiO and concentrated sulfuric acid decreases, accelerating the sulfuric acid maturation process of nickel and facilitating the conversion of nickel oxides into sulfates. Therefore, NaF promotes the reaction between concentrated sulfuric acid and NiO during the maturation process, inhibiting Fe leaching. The relevant reaction is as follows: Fe2(SO4)3 + 6NaF + 3H2O == Fe2O3 + 3Na2SO4 + 6HF

[0020] In addition, by introducing reducing gas during the aging and roasting process, the CrO3 in the laterite nickel ore reacts with sulfuric acid to produce Cr 6+ Reduced to Cr 3+ , the relevant reaction is as follows: CrO3+3H2SO4==Cr(SO4)3+3H2O Cr 6+ +1.5H2==Cr 3+ +3H + .

[0021] In this embodiment, the raw laterite nickel ore is low-nickel and high-magnesium laterite nickel ore.

[0022] In some specific embodiments of the present invention, the chemical composition of the laterite nickel ore includes: Ni 1%-1.5%, Co 0.09%-0.2%, Mn <1%, Fe>35%, Al <5%, Cr <1%, Ca <1%, Mg <5%, Zn <1%, and Si>10%.

[0023] In this embodiment, in the pre-treatment step, the particle size d of the laterite nickel ore dry powder is 50 The particle size is less than 100 μm; the moisture content of the laterite nickel ore dry powder is less than 0.5%.

[0024] In this embodiment, in the aging and roasting step, the mass ratio of concentrated sulfuric acid to laterite nickel ore dry powder is (0.1-0.5): 1, including but not limited to 0.1: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, etc. If the acid-ore ratio is too high, the content of impurities such as Fe and Al in the aqueous solution will increase; if the acid-ore ratio is too low, the loss of Ni in the leaching residue will increase. The mass ratio of sodium fluoride to laterite nickel ore dry powder is (0.05-0.5): 1, including but not limited to 0.05: 1, 0.1: 1, 0.15: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, etc. If the proportion of sodium fluoride is too low, the laterite nickel ore will not be fully matured, and the content of Ni and Co in the aqueous solution will decrease; if the proportion of sodium fluoride is too high, the cost will increase, and the difficulty of subsequent impurity removal will increase.

[0025] In this embodiment, in the aging and roasting step, the roasting temperature is 100-400°C, including but not limited to 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, etc., and the present invention is not limited thereto. The present invention not only promotes the reaction process of laterite nickel ore and concentrated sulfuric acid, improves nickel leaching, and inhibits iron leaching by adding sodium fluoride, but also reduces the reaction temperature of the aging and roasting step. Compared with the existing process of performing sulfuric acid aging and reduction roasting in steps, this not only simplifies the process flow but also significantly reduces the reduction roasting temperature; the roasting pressure is 0-1MPa, including but not limited to 0MPa, 0.2MPa, 0.4MPa, 0.6MPa, 0.8MPa, 1MPa, etc. The present invention can increase the gas volume per unit volume by controlling the roasting pressure, thereby making the reaction more thorough; the roasting time is 0.1-3 hours, including but not limited to 0.1 hours, 0.2 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.; and the roasting atmosphere is hydrogen.

[0026] In this embodiment, in the water immersion step, the mass ratio of the cooked material to water is 1:(1-5), including but not limited to 1:1, 1:2, 1:3, 1:4, 1:5, etc.; the water immersion temperature is 30-80°C, including but not limited to 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc.; the water immersion time is 1-3h, including but not limited to 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0027] In this embodiment, in the atmospheric pressure acid leaching step, the acid concentration is 30%-100%, including but not limited to 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 100%, etc.; the acid-ore mass ratio is (0.05-0.5):1, including but not limited to 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, etc.; the atmospheric pressure acid leaching temperature is 40-90°C, including but not limited to 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, etc.; the atmospheric pressure acid leaching time is 0.1-3h, including but not limited to 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0028] In some specific embodiments of the present invention, in the atmospheric pressure acid leaching step, the acid used is concentrated sulfuric acid. In the atmospheric pressure acid leaching step, pure water is also added, and the mass ratio of the leached residue to the pure water is 1:(1-5), including but not limited to 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0029] In this embodiment, the mass fraction of concentrated sulfuric acid is 96-98.3%, including but not limited to 96%, 96.5%, 97%, 97.5%, 98%, 98.3%, etc.

[0030] In this embodiment, both the water leaching and atmospheric pressure acid leaching steps are performed under stirring conditions. Further, the stirring speed is 100-500 r / min, including but not limited to 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, etc.

[0031] In this embodiment, the above-mentioned water leaching liquid and acid leaching liquid can enter the subsequent purification line, and nickel and cobalt can be separated separately after purification treatment, or nickel and cobalt can be jointly purified. The present invention is not limited to this, and those skilled in the art can make a choice according to actual conditions; after the above-mentioned acid leaching residue undergoes the iron removal process, iron slag can be separated to achieve iron recovery.

[0032] To avoid redundancy, in the following embodiments and comparative examples of the present invention, the mass fraction of concentrated sulfuric acid used is 98%, and the main components of the laterite nickel ore used are as follows:

[0033] Table 1

[0034] Example 1

[0035] (1) Pretreatment: The laterite nickel ore is subjected to impurity removal, crushing, drying, ball milling and sieving to obtain d 50 It is 89 micron mineral powder with a moisture content of less than 0.3%;

[0036] (2) calcination: add concentrated sulfuric acid to the laterite nickel ore powder at a mass ratio of 0.32 between the acid and ore, and add NaF at a mass ratio of 0.15. After thorough mixing, the mixture is divided into granules and placed in a tube furnace for calcination at a reaction temperature of 400°C for 2 h in a hydrogen atmosphere at a pressure of 0.5 MPa.

[0037] (3) Water immersion: After aging, pure water was added to the aging material at a mass ratio of 1:3. The stirring speed was 300 r / min, the immersion temperature was 70°C, and the immersion time was 2 hours. After filtration, the leaching rates of Ni and Co were 91.8% and 90.6%, respectively, and the leaching rate of Fe was 0.8%.

[0038] (4) Acid leaching at atmospheric pressure: pure water and concentrated sulfuric acid were added to the water leaching residue at a mass ratio of 1:2.5 and an acid-ore mass ratio of 0.36 (wet slag weight). The acid leaching temperature was 50°C, the time was 1 hour, and the stirring speed was 300 r / min. The leaching rates of Ni and Co (slag basis) were 89.5% and 87.6% respectively. The Cr content in the acid leaching solution was 0.1%. 6+ The content is 0.21 mg / L, and the nickel content in the acid leaching residue is 0.12%.

[0039] Example 2

[0040] (1) Pretreatment: The laterite nickel ore is subjected to impurity removal, crushing, drying, ball milling and sieving to obtain d 50 It is 85 micron mineral powder with a moisture content of less than 0.3%;

[0041] (2) calcination: add concentrated sulfuric acid to the laterite nickel ore powder at a mass ratio of 0.35 between the acid and ore, and add NaF at a mass ratio of 0.2. After thorough mixing, the mixture is divided into granules and placed in a tube furnace for calcination at a reaction temperature of 250°C for 2 h in a hydrogen atmosphere at a pressure of 0.41 MPa.

[0042] (3) Water immersion: After aging, pure water was added to the aging material at a mass ratio of 1:3. The stirring speed was 300 r / min, the immersion temperature was 80°C, and the immersion time was 1 hour. After filtration, the leaching rates of Ni and Co were 97.3% and 91.5%, respectively, and the leaching rate of Fe was 0.2%.

[0043] (4) Acid leaching at atmospheric pressure: pure water and concentrated sulfuric acid were added to the water leaching residue at a mass ratio of 1:2.5 and an acid-ore mass ratio of 0.36 (wet slag weight). The acid leaching temperature was 90°C for 1 hour and the stirring speed was 300 r / min. The leaching rates of Ni and Co (based on slag) were 87.2% and 84.6% respectively. The Cr content in the acid leaching solution was 1.3%. 6+ The content is 0.19 mg / L, and the nickel content in the acid leaching residue is 0.05%.

[0044] Example 3

[0045] (1) Pretreatment: The laterite nickel ore is subjected to impurity removal, crushing, drying, ball milling and sieving to obtain d 50 It is 91 micron mineral powder with a moisture content of less than 0.3%;

[0046] (2) calcination: add concentrated sulfuric acid to the laterite nickel ore powder at a mass ratio of 0.39 between the acid and ore, and add NaF at a mass ratio of 0.3. After thorough mixing, the mixture is divided into granules and placed in a tube furnace for calcination at a reaction temperature of 250°C for 3 hours in a hydrogen atmosphere at a pressure of 0.5 MPa.

[0047] (3) Water immersion: After aging, pure water was added to the aging material at a mass ratio of 1:3. The stirring speed was 300 r / min, the immersion temperature was 70°C, and the immersion time was 2 hours. After filtration, the leaching rates of Ni and Co were 98.5% and 92.7%, respectively, and the leaching rate of Fe was 0.1%.

[0048] (4) Acid leaching at atmospheric pressure: pure water and concentrated sulfuric acid were added to the water leaching residue at a mass ratio of 1:2.5 and an acid-ore mass ratio of 0.36 (wet slag weight). The leaching temperature was 90°C for 2 hours and the stirring speed was 300 r / min. The leaching rates of Ni and Co (based on slag) were 92.8% and 90.3% respectively. The Cr content in the acid leaching solution was 0.1%. 6+ The content is 0.17 mg / L, and the nickel content in the acid leaching residue is 0.07%.

[0049] Comparative Example 1

[0050] Compared with Example 1, the only difference is that in the pretreatment step, the moisture content of the laterite nickel ore powder is controlled to 20%.

[0051] Using this method, after water leaching, the leaching rates of Ni and Co were 86.3% and 85.9%, and the leaching rate of Fe was 1.1%. After atmospheric pressure acid leaching, the leaching rates of Ni and Co (based on slag) were 88.3% and 85.2%, respectively. The Cr content in the acid leaching solution was 1.1%. 6+ The content is 0.22 mg / L, and the nickel content in the acid leaching residue is 0.15%.

[0052] Comparative Example 2

[0053] Compared with Example 1, the only difference is that sodium fluoride is not added in the aging and roasting step.

[0054] Using this method, after water leaching, the leaching rates of Ni and Co were 76.3% and 74.9%, and the leaching rate of Fe was 1.5%; after atmospheric pressure acid leaching, the leaching rates of Ni and Co (based on slag) were 85.6% and 84.3%, respectively, and the Cr content in the acid leaching solution was 1.5%. 6+The content is 20.2 mg / L, and the nickel content in the acid leaching residue is 0.23%.

[0055] Comparative Example 3

[0056] Compared with Example 1, the only difference is that no hydrogen is introduced during the aging and roasting step.

[0057] Using this method, after water leaching, the leaching rates of Ni and Co are 91.8% and 90.8%, and the leaching rate of Fe is 0.1%; after atmospheric pressure acid leaching, the leaching rates of Ni and Co (slag basis) are 92.3% and 91.5% respectively, and the Cr content in the acid leaching solution is 0.1%. 6+ The content is 325.2 mg / L, and the nickel content in the acid leaching residue is 0.09%.

[0058] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching, characterized in that: The following steps are involved: Pretreatment: The laterite nickel ore is subjected to impurity removal, crushing, drying, ball milling and sieving to obtain laterite nickel ore dry powder; Mature roasting: the laterite nickel ore dry powder, concentrated sulfuric acid and sodium fluoride are mixed evenly, and then matured and roasted in a reducing atmosphere to obtain a mature material; Water soaking: soaking the cooked material in water, and obtaining water soaking liquid and water soaking residue after filtering; Normal pressure acid leaching: the water leaching residue is subjected to normal pressure acid leaching, and the acid leaching liquid and acid leaching residue are obtained after filtering.

2. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: In the pre-treatment step, the laterite nickel ore is low-nickel and high-magnesium laterite nickel ore.

3. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: In the pre-treatment step, the particle size d of the laterite nickel ore dry powder is 50 The particle size of the laterite nickel ore dry powder is less than 100 μm; and the moisture content of the laterite nickel ore dry powder is less than 0.5%.

4. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: In the aging and roasting step, the mass ratio of the concentrated sulfuric acid to the laterite nickel ore dry powder is (0.1-0.5):1, and the mass ratio of the sodium fluoride to the laterite nickel ore dry powder is (0.05-0.5):

1.

5. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 4, characterized in that: In the aging and roasting step, the mass ratio of the concentrated sulfuric acid to the laterite nickel ore dry powder is (0.3-0.4):1, and the mass ratio of the sodium fluoride to the laterite nickel ore dry powder is (0.15-0.3):

1.

6. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: In the aging and calcining step, the calcining temperature is 100-400° C., the calcining pressure is 0-1 MPa, the calcining time is 0.1-3 h, and the calcining atmosphere is hydrogen.

7. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 6, characterized in that: In the aging and roasting step, the roasting temperature is 250-400° C., the roasting pressure is 0.4-0.5 MPa, and the roasting time is 1-3 hours.

8. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: In the water immersion step, the mass ratio of the slaking material to water is 1:(1-5); the water immersion temperature is 30-80° C., and the water immersion time is 1-3 hours.

9. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 8, characterized in that: In the water immersion step, the mass ratio of the slaking material to water is 1:(2-4); the water immersion temperature is 70-80° C., and the water immersion time is 1-2 hours.

10. The method for treating laterite nickel ore by slaking, roasting, water leaching and acid leaching at normal pressure according to claim 1, characterized in that: In the atmospheric pressure acid leaching step, the acid concentration is 30%-100%, the acid-ore mass ratio is (0.05-0.5):1; the atmospheric pressure acid leaching temperature is 40-90°C, and the atmospheric pressure acid leaching time is 0.1-3h.

11. The method for treating laterite nickel ore by slaking, roasting, water leaching and acid leaching at normal pressure according to claim 10, characterized in that: In the normal pressure acid leaching step, the acid used is concentrated sulfuric acid; and in the normal pressure acid leaching step, pure water is also added, and the mass ratio of the water leaching residue to the pure water is 1:(1-5).

12. The method for treating laterite nickel ore by calcination-water leaching-normal pressure acid leaching according to claim 1, characterized in that: Both the water leaching and atmospheric pressure acid leaching steps are carried out under stirring conditions.

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