A method for resource utilization of laterite nickel ore iron aluminum slag

Abstract

The application discloses a method for resource utilization of laterite nickel ore iron-aluminum slag, and belongs to the technical field of resource utilization of laterite nickel ore iron-aluminum slag. The method comprises the following steps: performing acid leaching on the red mud to dissolve at least part of metal oxides in the red mud, and obtaining leaching residues and first leaching solution after solid-liquid separation; the at least part of metal oxides comprise iron oxides, aluminum oxides and scandium oxides; mixing the first leaching solution with phosphate, and obtaining iron phosphate and second leaching solution after solid-liquid separation; performing reduction roasting on a mixture of the laterite nickel ore iron-aluminum slag and a reducing agent to obtain a roasting product; separating iron in the roasting product to obtain iron concentrate and scandium-containing aluminum slag; performing high-temperature and high-pressure acid leaching reaction on the scandium-containing aluminum slag and the second leaching solution to obtain aluminum oxide and scandium-containing third leaching solution; and performing selective scandium precipitation on the third leaching solution. The method is simple in operation, low in cost, efficient in selectively recovering valuable metals iron, aluminum and scandium in the laterite nickel ore and the red mud, and high in economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource utilization of laterite nickel ore iron and aluminum slag, in particular to a resource utilization method of laterite nickel ore iron and aluminum slag. BACKGROUND

[0002] Laterite nickel ore is the main source of metal nickel, and a wet treatment process is widely used in production. In the prior art, the wet treatment process of laterite nickel ore includes adjusting the pH of laterite nickel ore leaching solution by lime milk, and selectively precipitating iron and aluminum in it to form iron and aluminum slag. This part of iron and aluminum slag is usually piled up in the tailings pond as waste, and is not fully recycled.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The present application aims to provide a resource utilization method of laterite nickel ore iron and aluminum slag to solve or improve the above technical problems.

[0005] The present application can be achieved as follows:

[0006] The present application provides a resource utilization method of laterite nickel ore iron and aluminum slag, which includes the following steps:

[0007] Acid leaching the red mud to dissolve at least part of the metal oxides in the red mud, and obtaining leaching residue and first leaching solution after solid-liquid separation; at least part of the metal oxides include iron oxides, aluminum oxides and scandium oxides; mixing the first leaching solution with phosphate, and obtaining iron phosphate and second leaching solution after solid-liquid separation;

[0008] Reducing roasting the mixture of laterite nickel ore iron and aluminum slag and reducing agent to obtain roasting product; separating iron in the roasting product to obtain iron concentrate and scandium-containing aluminum slag;

[0009] High-temperature and high-pressure acid leaching reaction of the scandium-containing aluminum slag and the second leaching solution, and obtaining aluminum oxide and scandium-containing third leaching solution after solid-liquid separation; selective scandium precipitation of the third leaching solution.

[0010] In an optional embodiment, the acid leaching includes mixing the red mud with the acid leaching agent and then reacting.

[0011] In an optional embodiment, the pH value of the mixed solution of the red mud and the acid leaching agent at the end of the acid leaching is not more than 1.5.

[0012] In an optional embodiment, the acid leaching agent includes a sulfuric acid solution; and / or, the particle size of the red mud is 100-200 mesh.

[0013] In an optional embodiment, the concentration of the sulfuric acid solution is 2-6 mol / L.

[0014] In an optional embodiment, the liquid-solid ratio of the sulfuric acid solution to the red mud is 5 mL: 1 g to 7 mL: 1 g.

[0015] In an optional embodiment, the phosphate salt comprises at least one of sodium dihydrogen phosphate and disodium hydrogen phosphate;

[0016] In an optional embodiment, the molar ratio of iron in the first leaching solution to phosphorus in the phosphate salt is 1:1 to 1.2:1.

[0017] In an optional embodiment, the pH value of the mixed solution of the first leaching solution and the phosphate salt is 1 to 3.5.

[0018] In an optional embodiment, the amount of the reducing agent added is 30 wt% to 50 wt% of the laterite nickel ore iron aluminum residue.

[0019] In an optional embodiment, the reducing agent comprises at least one of carbon powder, graphite, and coal.

[0020] In an optional embodiment, the temperature of the reduction roasting is 650°C to 900°C, and / or the time of the reduction roasting is 0.5 h to 2 h.

[0021] In an optional embodiment, the separation of iron in the roasting product is performed by magnetic separation.

[0022] In an optional embodiment, the magnetic separation strength is 400 GS to 2000 GS.

[0023] In an optional embodiment, the high-temperature high-pressure acid leaching reaction comprises at least one of the following features:

[0024] Feature one: the temperature of the high-temperature high-pressure acid leaching reaction is 180°C to 240°C.

[0025] Feature two: the pressure of the high-temperature high-pressure acid leaching reaction is 3 MPa to 4.5 MPa.

[0026] Feature three: the time of the high-temperature high-pressure acid leaching reaction is 0.5 h to 2 h.

[0027] Feature four: the pH value of the third leaching solution of the high-temperature high-pressure acid leaching reaction is 0.2 to 1.

[0028] In an optional embodiment, the selective scandium precipitation comprises: mixing the third leaching solution with oxalic acid, and performing solid-liquid separation to obtain scandium oxalate and an acid-containing lean solution.

[0029] In an optional embodiment, the molar amount of the oxalic acid is 1.5 times to 2 times of the scandium in the third leaching solution.

[0030] In an optional embodiment, the acid-containing lean solution is returned to the acid leaching process.

[0031] The beneficial effects of the present application include:

[0032] The present application can make the oxides of iron, aluminum and scandium in the red mud dissolve into the first leaching solution by acid leaching treatment of the red mud, and the remaining undissolved substances are left in the leaching residue.

[0033] The iron in the first leaching solution can react with the phosphate ions in the phosphate to generate iron phosphate by mixing and reacting the first leaching solution with the phosphate, and the iron phosphate and the second leaching solution are obtained after solid-liquid separation, so as to realize the purpose of selective precipitation of iron.

[0034] The iron oxide in the laterite nickel ore iron-aluminum slag is reduced by mixing the laterite nickel ore iron-aluminum slag with a reducing agent and then performing reduction roasting, and then the iron in the roasting product is selected, and the scandium and aluminum that cannot be selected are left in the scandium and aluminum-containing slag.

[0035] The scandium and aluminum-containing slag is added into the second leaching solution and high-temperature and high-pressure acid leaching reaction is performed, Al 3+ Hydrolysis occurs to form grass alum or alum precipitate and release acid, and the grass alum and the alum generate Al2O3 under high temperature conditions, and the solvent in the second leaching solution can dissolve the scandium and aluminum-containing slag, and after solid-liquid separation, aluminum oxide and scandium-containing third leaching solution are obtained, so as to realize the separation of aluminum.

[0036] The scandium is separated by selective precipitation of scandium in the third leaching solution.

[0037] The present application can efficiently and selectively recover valuable metals by designing different processes for the red mud and the laterite nickel ore iron-aluminum slag and combining the two, and high-purity iron phosphate, iron concentrate, aluminum oxide and scandium products are obtained, which is simple to operate, low in cost and high in economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0039] Figure 1 The process flow diagram of the laterite nickel ore iron-aluminum slag resource utilization method provided for the embodiment 1 of the present application. DETAILED DESCRIPTION

[0040] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted.

[0041] The method for resource utilization of laterite nickel ore iron-aluminum slag provided by the present application will be described in detail below.

[0042] At present, the iron-aluminum slag as waste contains a large amount of iron and aluminum, and also contains metal components such as scandium. The inventors point out that the composition of the iron-aluminum slag is similar to that of red mud, and the red mud is also a main solid waste in the production of alumina by the Bayer process, which is also discarded in a tailings pond in large quantities and is not effectively recycled and utilized. The reason is that if a pyrometallurgical method is used to recover the red mud, the overall energy consumption is high and the pollution is heavy; if a hydrometallurgical method is used to recover the red mud, the method generally uses strong acid for dissolution, and then selectively recovers according to the differences in the properties of different metal ions, but due to the high content of iron and aluminum in the red mud, the direct acid leaching reagent consumption is large, and the subsequent separation and recovery process is long, and the overall economic benefit is low.

[0043] In view of this, the present application creatively proposes a method for recovering aluminum, iron and scandium from laterite nickel ore iron-aluminum slag and red mud, so as to realize effective recycling and utilization of the above-mentioned solid waste.

[0044] The method for resource utilization of laterite nickel ore iron-aluminum slag provided by the present application comprises the following steps:

[0045] The red mud is subjected to acid leaching to dissolve at least part of the metal oxides in the red mud, and after solid-liquid separation, leaching residue and first leaching solution are obtained; the at least part of the metal oxides include oxides of iron, aluminum and scandium; the first leaching solution is mixed with phosphate, and after solid-liquid separation, iron phosphate and second leaching solution are obtained;

[0046] The mixture of the laterite nickel ore iron-aluminum slag and the reducing agent is subjected to reduction roasting to obtain a roasting product; the iron in the roasting product is separated to obtain iron concentrate and scandium-containing aluminum slag;

[0047] The scandium-containing aluminum slag is subjected to high-temperature and high-pressure acid leaching reaction with the second leaching solution, and after solid-liquid separation, aluminum oxide and scandium-containing third leaching solution are obtained; the third leaching solution is subjected to selective scandium precipitation.

[0048] In the present application, the acid leaching includes mixing the red mud with an acid leaching agent and then reacting.

[0049] The acid leaching reaction process can be carried out at normal temperature and pressure. Among them, "normal temperature" can be understood as room temperature, which can be 15℃-35℃, and the same below.

[0050] Before acid leaching, the red mud can be ground or the like to have a particle size of 100-200 mesh, such as 100 mesh, 120 mesh, 150 mesh, 180 mesh or 200 mesh. Controlling the particle size of the red mud in the above range is conducive to improving the reaction effect with the acid leaching agent and improving the acid leaching efficiency.

[0051] The acid leaching agent can exemplarily but non-limitingly include a sulfuric acid solution. In some embodiments, the concentration of the sulfuric acid solution can be 2-6 mol / L, such as 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L or 6 mol / L, or any other value within the range of 2-6 mol / L. Correspondingly, the liquid-solid ratio of the sulfuric acid solution to the red mud can be 5-7 mL: 1 g, such as 5 mL: 1 g, 5.5 mL: 1 g, 6 mL: 1 g, 6.5 mL: 1 g or 7 mL: 1 g, or any other value within the range of 5-7 mL: 1 g.

[0052] In the present application, the pH value of the mixed solution of the red mud and the acid leaching agent at the end of the acid leaching is not more than 1.5, that is, the pH value at the end of the acid leaching is controlled to be not more than 1.5. If the pH value at the end of the acid leaching exceeds 1.5, it is not conducive to the dissolution of valuable metals such as iron, aluminum and scandium in the red mud.

[0053] After the acid leaching is completed, solid-liquid separation can be achieved by pressure filtration to obtain leaching residue and first leaching solution.

[0054] Through the above acid leaching treatment, at least the oxides of iron, aluminum and scandium in the red mud are dissolved into the first leaching solution, and the remaining undissolved substances remain in the leaching residue.

[0055] In the present application, the phosphate can include at least one of sodium dihydrogen phosphate and disodium hydrogen phosphate.

[0056] The molar ratio of iron in the first leaching solution to phosphorus in the phosphate can be 1:1-1.2:1, such as 1:1, 1.15:1 or 1.2:1, or any other value within the range of 1:1-1.2:1.

[0057] The pH value of the mixed solution of the first leaching solution and the phosphate can be 1-3.5, such as 1, 1.5, 2, 2.5, 3 or 3.5, or any other value within the range of 1-3.5. If the pH value of the mixed solution of the first leaching solution and the phosphate exceeds 3.5, other metals will form phosphate precipitates, which is not conducive to ensuring the purity of the iron phosphate.

[0058] In some embodiments, the first leaching solution and the phosphate can be mixed at a stirring frequency of 20-30 Hz.

[0059] After the reaction of the first leaching solution and the phosphate is completed, the solid-liquid separation can be achieved by pressure filtration to obtain the iron phosphate and the second leaching solution.

[0060] By mixing the first leaching solution and the phosphate under the above pH conditions, the iron in the first leaching solution can react with the phosphate ions in the phosphate to form iron phosphate, thereby achieving the purpose of selectively precipitating iron.

[0061] In the present application, the amount of the reducing agent added can be 30wt%-50wt% of the laterite nickel ore iron-aluminum slag, such as 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, etc., or any other value within the range of 30wt%-50wt%.

[0062] In the present application, the reducing agent is a carbonaceous reducing agent, which can exemplarily but not limitatively include at least one of carbon powder, graphite and coal.

[0063] The temperature of the reduction roasting can be 650-900℃, such as 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃, etc., or any other value within the range of 650-900℃.

[0064] The time of the reduction roasting can be 0.5-2h, such as 0.5h, 1h, 1.5h or 2h, etc., or any other value within the range of 0.5-2h.

[0065] By mixing the laterite nickel ore iron-aluminum slag and the reducing agent and then performing the reduction roasting, the iron oxides in the laterite nickel ore iron-aluminum slag are reduced.

[0066] In the present application, the separation of the iron in the roasting product can be performed by magnetic separation.

[0067] In some embodiments, the magnetic separation strength can be 400-2000GS, such as 400GS, 800GS, 1000GS, 1200GS, 1500GS, 1800GS or 2000GS, etc., or any other value within the range of 400-2000GS.

[0068] After the magnetic separation, the iron in the roasting product is separated out, while the scandium and aluminum cannot be separated out by the magnetic separation and are added into the second leaching solution described above to perform the high-temperature and high-pressure acid leaching reaction.

[0069] In the present application, the temperature of the high-temperature and high-pressure acid leaching reaction is 180℃ to 240℃, such as 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃ or 240℃, etc., and can also be other values within the range of 180℃ to 240℃.

[0070] The pressure of the high-temperature and high-pressure acid leaching reaction can be 3MPa to 4.5MPa, such as 3MPa, 3.5MPa, 4MPa or 4.5MPa, etc., and can also be other values within the range of 3MPa to 4.5MPa.

[0071] The time of the high-temperature and high-pressure acid leaching reaction can be 0.5h to 2h, such as 0.5h, 1h, 1.5h or 2h, etc., and can also be other values within the range of 0.5h to 2h.

[0072] The pH value of the third leaching solution of the high-temperature and high-pressure acid leaching reaction can be 0.2 to 1, such as 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc., and can also be other values within the range of 0.2 to 1.

[0073] In the above high-temperature and high-pressure acid leaching reaction process, Al 3+ hydrolysis to form grass alum or alum precipitate and release acidic solvent, and Al2O3 is generated under high-temperature conditions, and the acidic solvent in the second leaching solution can dissolve the scandium-containing aluminum residue, so that scandium in the scandium-containing aluminum residue is dissolved into the third leaching solution. By controlling the pH value of the third leaching solution, the addition amount of the scandium-containing aluminum residue can be dynamically controlled. If the addition amount of the scandium-containing aluminum residue is too small, Al 3+ The acidic solvent released by hydrolysis will inhibit the high-temperature and high-pressure acid leaching reaction; if the addition amount of the scandium-containing aluminum residue is too large, the acidic solvent produced by hydrolysis will be insufficient, which cannot quickly dissolve scandium, resulting in loss of scandium.

[0074] After the high-temperature and high-pressure acid leaching reaction is completed, solid-liquid separation can be achieved by pressure filtration to obtain aluminum oxide and a third leaching solution containing scandium. The third leaching solution may contain a small amount of Fe 3+ and Al 3+ impurities.

[0075] In the present application, the selective scandium precipitation can include mixing the third leaching solution with oxalic acid, and solid-liquid separation to obtain scandium oxalate and an acid-poor liquid. The process can be carried out under normal temperature and pressure conditions.

[0076] The molar amount of oxalic acid can be 1.5 times to 2 times the amount of scandium in the third leaching solution, such as 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times or 2 times, etc., and can also be other values within the range of 1.5 times to 2 times.

[0077] In some embodiments, the resulting acid-containing lean solution can be returned to the acid leaching process for recycling, thereby reducing the consumption of acid.

[0078] In summary, the red mud and the laterite nickel ore iron-aluminum residue used in the present application both contain a large amount of iron, aluminum and scandium. By recovering Fe from the first leaching solution corresponding to the red mud and by magnetically separating Fe from the reduced roasting product corresponding to the laterite nickel ore iron-aluminum residue, the recovery of Fe can be achieved. By subjecting the second leaching solution corresponding to the red mud and the scandium-containing aluminum residue corresponding to the laterite nickel ore iron-aluminum residue to high-temperature and high-pressure acid leaching reaction in an autoclave, the Al 3+ in the second leaching solution is hydrolyzed to release scandium and aluminum in the scandium-containing aluminum residue, and the unreacted acid produced can be recycled for the dissolution of the red mud. Since the second leaching solution contains only Al 3+ , the solid phase produced after the autoclave reaction is basically Al2O3 with high purity. In addition, by dynamically monitoring the pH in the autoclave, the amount of scandium-containing aluminum residue added can be effectively controlled, the dissolution of scandium is maximized, and the hydrolysis of Al 3+ is promoted.

[0079] The features and performances of the present application are further described in detail below in conjunction with examples.

[0080] Example 1

[0081] This example provides a method for resource utilization of laterite nickel ore iron-aluminum residue. Please refer to Figure 1 , which comprises the following steps:

[0082] Step (1): Mix the red mud with a sulfuric acid solution and react at room temperature and under normal pressure for 1 h, with the control end point pH value being 1. After the acid leaching is completed, pressure filtration is performed to obtain a leaching residue and a first leaching solution. The particle size of the red mud is 100-200 mesh, the concentration of the sulfuric acid solution is 2 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the red mud is 6 mL:1 g.

[0083] Step (2): Add disodium hydrogen phosphate to the above-mentioned first leaching solution and react under the condition of a stirring frequency of 25 Hz until the pH value of the mixed solution of the first leaching solution and the disodium hydrogen phosphate is 3. After the reaction is completed, pressure filtration is performed to obtain iron phosphate and a second leaching solution. The molar ratio of Fe 3+ in the first leaching solution to P in the disodium hydrogen phosphate is 1.2:1.

[0084] Step (3): Mix the laterite nickel ore iron-aluminum residue with a reducing agent (carbon powder) and reduce and roast at 800℃ for 1.5 h to obtain a roasting product. The addition amount of the reducing agent is 35wt% of the amount of the laterite nickel ore iron-aluminum residue. The roasting product is subjected to magnetic separation in a magnetic separator at a magnetic separation intensity of 1000 GS to obtain iron concentrate and scandium-containing aluminum residue.

[0085] Step (4): The above-mentioned scandium-containing aluminum slag and the above-mentioned second leaching solution are subjected to high-temperature and high-pressure acid leaching reaction, and after the reaction is completed, pressure filtration is performed to obtain aluminum oxide and a third leaching solution containing scandium. Among them, the autoclave reaction temperature is 240°C, the reaction kettle pressure is 4.5 MPa, the reaction time is 1 h, and the pH value of the third leaching solution in the kettle is controlled at 0.8.

[0086] Step (5): The above-mentioned third leaching solution is mixed with oxalic acid at room temperature and normal pressure to carry out a precipitation reaction, and after the reaction is completed, pressure filtration is performed to obtain scandium oxalate and an acid-containing lean solution. Among them, the molar amount of oxalic acid is 1.5 times that of scandium in the third leaching solution.

[0087] Example 2

[0088] The present embodiment provides a method for resource utilization of laterite nickel ore iron-aluminum slag, comprising the following steps:

[0089] Step (1): The red mud is mixed with a sulfuric acid solution, and reacted at room temperature and normal pressure for 1 h, with the end point pH value controlled at 1. After acid leaching, pressure filtration is performed to obtain a leaching residue and a first leaching solution. Among them, the particle size of the red mud is 100-200 mesh, the concentration of the sulfuric acid solution is 4 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the red mud is 6 mL:1 g.

[0090] Step (2): Sodium phosphate dibasic is added to the first leaching solution and reacted under the condition of a stirring frequency of 25 Hz until the pH value of the mixed solution of the first leaching solution and sodium phosphate dibasic is 3.2, and after the reaction is completed, pressure filtration is performed to obtain iron phosphate and a second leaching solution. Among them, the molar ratio of Fe in the first leaching solution to P in sodium phosphate dibasic is 1.2:1. 3+

[0091] Step (3): The laterite nickel ore iron-aluminum slag is mixed with a reducing agent (carbon powder) and reduced roasting at 800°C for 1.5 h to obtain a roasting product. Among them, the addition amount of the reducing agent is 35wt% of the amount of the laterite nickel ore iron-aluminum slag. The roasting product is subjected to magnetic separation in a magnetic separator at a magnetic separation intensity of 1000 GS to obtain iron concentrate and scandium-containing aluminum slag.

[0092] Step (4): The above-mentioned scandium-containing aluminum slag and the above-mentioned second leaching solution are subjected to high-temperature and high-pressure acid leaching reaction, and after the reaction is completed, pressure filtration is performed to obtain aluminum oxide and a third leaching solution containing scandium. Among them, the autoclave reaction temperature is 240°C, the reaction kettle pressure is 4.5 MPa, the reaction time is 1 h, and the pH value of the third leaching solution in the kettle is controlled at 0.8.

[0093] Step (5): The above-mentioned third leaching solution is mixed with oxalic acid at room temperature and normal pressure to carry out a precipitation reaction, and after the reaction is completed, pressure filtration is performed to obtain scandium oxalate and an acid-containing lean solution. Among them, the molar amount of oxalic acid is 1.5 times that of scandium in the third leaching solution.​

[0094] That is, the difference between the present embodiment and embodiment 1 is that the concentration of the sulfuric acid solution in step (1) is 4 mol / L; and the pH value of the mixed solution of the first leaching solution and the sodium phosphate dibasic in step (2) is 3.2.

[0095] Embodiment 3

[0096] The present embodiment provides a method for resource utilization of laterite nickel ore iron-aluminum slag, comprising the following steps:

[0097] Step (1): mixing the red mud with a sulfuric acid solution, and reacting at room temperature and under normal pressure for 1 h, with the end point pH value being controlled at 1. After acid leaching, pressure filtration is performed to obtain a leaching residue and a first leaching solution. The particle size of the red mud is 100-200 meshes, the concentration of the sulfuric acid solution is 4 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the red mud is 6 mL:1 g.

[0098] Step (2): adding sodium phosphate dibasic to the above-mentioned first leaching solution and reacting under the condition that the stirring frequency is 25 Hz, until the pH value of the mixed solution of the first leaching solution and the sodium phosphate dibasic is 3.2, and then performing pressure filtration after the reaction is completed to obtain iron phosphate and a second leaching solution. The molar ratio of Fe in the first leaching solution to P in the sodium phosphate dibasic is 1.2:1. 3+ The molar ratio of Fe in the first leaching solution to P in the sodium phosphate dibasic is 1.2:1.

[0099] Step (3): mixing the laterite nickel ore iron-aluminum slag with a reducing agent (carbon powder), and reducing roasting at 800℃ for 1.5 h to obtain a roasting product. The addition amount of the reducing agent is 40 wt% of the amount of the laterite nickel ore iron-aluminum slag. The roasting product is subjected to magnetic separation in a magnetic separator at a magnetic separation intensity of 1500 GS to obtain an iron concentrate and a scandium-containing aluminum residue.

[0100] Step (4): performing high-temperature and high-pressure acid leaching reaction of the above-mentioned scandium-containing aluminum residue with the above-mentioned second leaching solution, and then performing pressure filtration after the reaction is completed to obtain aluminum oxide and a scandium-containing third leaching solution. The reaction temperature of the autoclave is 240℃, the reaction kettle pressure is 4.5 MPa, the reaction time is 1 h, and the pH value of the third leaching solution in the kettle is controlled at 0.8.

[0101] Step (5): mixing the above-mentioned third leaching solution with oxalic acid at room temperature and under normal pressure to perform a precipitation reaction, and then performing pressure filtration after the reaction is completed to obtain scandium oxalate and an acid-containing lean solution. The molar amount of the oxalic acid is 1.5 times that of scandium in the third leaching solution.

[0102] That is, the difference between the present embodiment and embodiment 2 is that the addition amount of the reducing agent in step (3) is 40 wt% of the amount of the laterite nickel ore iron-aluminum slag; and the magnetic separation intensity is 1500 GS.

[0103] Embodiment 4

[0104] The embodiment provides a resource utilization method of laterite nickel ore iron-aluminum residue, and comprises the following steps.

[0105] Step (1): mixing the red mud and the sulfuric acid solution, and reacting at room temperature and under normal pressure for 1 h, so that the end point pH value is controlled to be 1. After the acid leaching is completed, pressure filtration is performed to obtain leaching residue and first leaching solution. The particle size of the red mud is 100-200 meshes, the concentration of the sulfuric acid solution is 4 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the red mud is 6 mL:1 g.

[0106] Step (2): adding disodium hydrogen phosphate to the first leaching solution, and reacting under the condition that the stirring frequency is 25 Hz until the pH value of the mixed solution of the first leaching solution and the disodium hydrogen phosphate is 3.2, and then performing pressure filtration after the reaction is completed to obtain iron phosphate and second leaching solution. The molar ratio of Fe in the first leaching solution to P in the disodium hydrogen phosphate is 1.2:1. 3+ The molar ratio of Fe in the first leaching solution to P in the disodium hydrogen phosphate is 1.2:1.

[0107] Step (3): mixing the laterite nickel ore iron-aluminum residue and a reducing agent (carbon powder), and reducing roasting at 800 DEG C for 1.5 h to obtain a roasting product. The adding amount of the reducing agent is 40 wt% of the amount of the laterite nickel ore iron-aluminum residue. The roasting product is subjected to magnetic separation in a magnetic separator at a magnetic separation intensity of 1500 GS to obtain iron concentrate and scandium-containing aluminum residue.

[0108] Step (4): performing high-temperature and high-pressure acid leaching reaction on the scandium-containing aluminum residue and the second leaching solution, and then performing pressure filtration after the reaction is completed to obtain aluminum oxide and scandium-containing third leaching solution. The reaction temperature of the autoclave is 240 DEG C, the reaction kettle pressure is 4.5 MPa, the reaction time is 1 h, and the pH value of the third leaching solution in the kettle is controlled to be 0.8.

[0109] Step (5): mixing the third leaching solution and oxalic acid at room temperature and under normal pressure to perform a precipitation reaction, and then performing pressure filtration after the reaction is completed to obtain scandium oxalate and acid-containing lean solution. The molar amount of the oxalic acid is twice that of scandium in the third leaching solution.

[0110] That is, the difference between the embodiment and example 3 is that, in step (5), the molar amount of the oxalic acid is twice that of scandium in the third leaching solution.

[0111] Example 5

[0112] The embodiment provides a resource utilization method of laterite nickel ore iron-aluminum residue, and comprises the following steps.

[0113] Step (1): mixing the red mud with sulfuric acid solution, and reacting at room temperature and normal pressure for 1 h, with the end point pH value being controlled at 1.2. After the acid leaching, pressure filtration is performed to obtain leaching residue and first leaching solution. In the step, the particle size of the red mud is 100-200 mesh, the concentration of the sulfuric acid solution is 6 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the red mud is 5 mL: 1 g.

[0114] Step (2): adding disodium hydrogen phosphate to the first leaching solution, and reacting under the condition of a stirring frequency of 30 Hz until the pH value of the mixed solution of the first leaching solution and the disodium hydrogen phosphate is 3.5. After the reaction, pressure filtration is performed to obtain iron phosphate and second leaching solution. In the step, the Fe 3+ in the first leaching solution and P in the disodium hydrogen phosphate have a molar ratio of 1.1:1.

[0115] Step (3): mixing the laterite nickel ore iron-aluminum residue with a reducing agent (anthracite), and reducing roasting at 900℃ for 0.5 h to obtain a roasting product. In the step, the adding amount of the reducing agent is 50 wt% of the amount of the laterite nickel ore iron-aluminum residue. The roasting product is subjected to magnetic separation in a magnetic separator at a magnetic separation intensity of 2000 GS to obtain iron concentrate and scandium-containing aluminum residue.

[0116] Step (4): performing high-temperature and high-pressure acid leaching reaction of the scandium-containing aluminum residue with the second leaching solution, and performing pressure filtration after the reaction to obtain aluminum oxide and scandium-containing third leaching solution. In the step, the reaction temperature of the autoclave is 200℃, the reaction kettle pressure is 3.5 MPa, the reaction time is 0.5 h, and the pH value of the third leaching solution in the kettle is controlled at 1.

[0117] Step (5): mixing the third leaching solution with oxalic acid at room temperature and normal pressure to perform precipitation reaction, and performing pressure filtration after the reaction to obtain scandium oxalate and acid-poor solution. In the step, the molar amount of the oxalic acid is twice that of scandium in the third leaching solution.

[0118] Comparative Example 1

[0119] The difference between the present comparative example and Example 1 is that in Step (1), the end point pH value of the acid leaching is 2.

[0120] Comparative Example 2

[0121] The difference between the present comparative example and Example 1 is that in Step (2), the pH value of the mixed solution of the first leaching solution and the disodium hydrogen phosphate is 3.8.

[0122] Comparative Example 3

[0123] The difference between the present comparative example and Example 1 is that in Step (4), the pH value of the third leaching solution in the kettle is controlled at 0.1.

[0124] Comparative Example 4

[0125] The difference between the present comparative example and example 1 is that in step (4), the pH value of the third leaching solution in the autoclave is controlled at 1.2.

[0126] Test example

[0127] The leaching rate of iron (wt%), the leaching rate of aluminum (wt%), the leaching rate of scandium (wt%) in the red mud obtained by the method provided in examples 1-5 and comparative examples 1-4, the precipitation rate of Fe (wt%) in the process of iron phosphate precipitation, the recovery rate of Fe (wt%) in the laterite nickel ore iron aluminum slag, the purity of Al2O3 (%) and the precipitation rate of scandium (wt%) produced by the autoclave are compared, and the results are shown in Table 1.

[0128] Table 1 comparison results

[0129]

[0130] As can be seen from Table 1, the methods provided in examples 1-5 can obtain higher leaching rates of iron, aluminum and scandium from red mud, and can also obtain higher precipitation rates of Fe in the process of iron phosphate precipitation, in addition, can obtain higher recovery rates of Fe from laterite nickel ore iron aluminum slag, and can obtain higher purity of Al2O3 and higher precipitation rate of scandium.

[0131] As can be seen from the comparison of example 1 and comparative examples 1-4, if some conditions are not properly controlled, the resource utilization results of metal elements will be affected.

[0132] In summary, by designing different processes for red mud and laterite nickel ore iron aluminum slag and combining the two, the present application can efficiently and selectively recover valuable metals therefrom, obtain higher purity of iron phosphate, iron concentrate, aluminum oxide and scandium oxalate, and at the same time, can reduce the consumption of sulfuric acid, and has higher economic benefits.

[0133] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for resource utilization of laterite nickel ore iron-aluminum residue, characterized in that, The method comprises the following steps: carrying out acid leaching on the red mud to dissolve at least part of metal oxides in the red mud, and obtaining leaching residue and first leaching solution after solid-liquid separation; the at least part of metal oxides comprises oxides of iron, aluminum and scandium; mixing the first leaching solution with phosphate, and obtaining iron phosphate and second leaching solution after solid-liquid separation; carrying out reduction roasting on a mixture of the laterite nickel ore iron-aluminum residue and a reducing agent to obtain a roasting product; separating iron in the roasting product to obtain iron concentrate and scandium-containing aluminum residue; carrying out high-temperature and high-pressure acid leaching reaction on the scandium-containing aluminum residue and the second leaching solution, and obtaining aluminum oxide and scandium-containing third leaching solution after solid-liquid separation; and selectively precipitating scandium from the third leaching solution.

2. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The acid leaching comprises: mixing the red mud with an acid leaching agent and then reacting.

3. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 2, characterized in that, The pH value of the mixed solution of the red mud and the acid leaching agent is not more than 1.5 at the end of the acid leaching.

4. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 2 or 3, characterized in that, The acid leaching agent comprises a sulfuric acid solution; and / or, the particle size of the red mud is 100 mesh to 200 mesh.

5. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 4, characterized in that, The concentration of the sulfuric acid solution is 2 mol / L to 6 mol / L.

6. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 5, characterized in that, The liquid-solid ratio of the sulfuric acid solution to the red mud is 5 mL:1 g to 7 mL:1 g.

7. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The phosphate comprises at least one of sodium dihydrogen phosphate and disodium hydrogen phosphate; and / or, the molar ratio of iron in the first leaching solution to phosphorus in the phosphate is 1:1 to 1.2:1; and / or, the pH value of the mixed solution of the first leaching solution and the phosphate is 1 to 3.

5.

8. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The addition amount of the reducing agent is 30 wt% to 50 wt% of the laterite nickel ore iron-aluminum residue; and / or, the reducing agent comprises at least one of carbon powder, graphite and coal.

9. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The temperature of the reduction roasting is 650 DEG C to 900 DEG C, and / or the time of the reduction roasting is 0.5 h to 2 h.

10. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The separation of iron in the roasting product is carried out by magnetic separation.

11. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 10, characterized in that, The magnetic separation strength is 400 GS to 2000 GS.

12. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The high-temperature and high-pressure acid leaching reaction comprises at least one of the following features: Feature one: the temperature of the high-temperature and high-pressure acid leaching reaction is 180 DEG C to 240 DEG C; Feature two: the pressure of the high-temperature and high-pressure acid leaching reaction is 3 MPa to 4.5 MPa; Feature three: the time of the high-temperature and high-pressure acid leaching reaction is 0.5 h to 2 h; Feature four: the pH value of the third leaching solution in the high-temperature and high-pressure acid leaching reaction is 0.2 to 1.

13. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 1, characterized in that, The selective precipitation of scandium comprises: mixing the third leaching solution with oxalic acid, and carrying out solid-liquid separation to obtain scandium oxalate and acid-depleted liquid.

14. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 13, characterized in that, The molar amount of the oxalic acid is 1.5 times to 2 times of scandium in the third leaching solution.

15. The method for resource utilization of laterite nickel ore iron-aluminum residue according to claim 13, characterized in that, The acid-depleted liquid is returned to the acid leaching process.

Images