CN111926193B - Method for recovering magnesium from ferronickel slag - Google Patents
Method for recovering magnesium from ferronickel slag Download PDFInfo
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- CN111926193B CN111926193B CN202010791379.8A CN202010791379A CN111926193B CN 111926193 B CN111926193 B CN 111926193B CN 202010791379 A CN202010791379 A CN 202010791379A CN 111926193 B CN111926193 B CN 111926193B
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- magnesium sulfate
- slag
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- magnesium
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- 239000002893 slag Substances 0.000 title claims abstract description 173
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 71
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 71
- 239000011777 magnesium Substances 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 49
- 229910000863 Ferronickel Inorganic materials 0.000 title claims description 105
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims abstract description 180
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims abstract description 85
- 235000019341 magnesium sulphate Nutrition 0.000 claims abstract description 85
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 claims abstract description 47
- 238000002425 crystallisation Methods 0.000 claims description 113
- 230000008025 crystallization Effects 0.000 claims description 113
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 94
- 229960003390 magnesium sulfate Drugs 0.000 claims description 83
- 239000013078 crystal Substances 0.000 claims description 72
- 229940091250 magnesium supplement Drugs 0.000 claims description 66
- 238000003756 stirring Methods 0.000 claims description 57
- 239000000843 powder Substances 0.000 claims description 50
- 238000005406 washing Methods 0.000 claims description 50
- 238000002386 leaching Methods 0.000 claims description 44
- 239000002245 particle Substances 0.000 claims description 35
- 239000000706 filtrate Substances 0.000 claims description 32
- 239000007787 solid Substances 0.000 claims description 31
- 238000001035 drying Methods 0.000 claims description 30
- 239000007788 liquid Substances 0.000 claims description 19
- 238000000227 grinding Methods 0.000 claims description 13
- 238000000926 separation method Methods 0.000 claims description 12
- 238000005470 impregnation Methods 0.000 claims description 7
- 238000012216 screening Methods 0.000 claims description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- WRUGWIBCXHJTDG-UHFFFAOYSA-L magnesium sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Mg+2].[O-]S([O-])(=O)=O WRUGWIBCXHJTDG-UHFFFAOYSA-L 0.000 claims description 3
- 229940061634 magnesium sulfate heptahydrate Drugs 0.000 claims description 3
- 229940076230 magnesium sulfate monohydrate Drugs 0.000 claims description 3
- QSOMFNQEXNFPNU-UHFFFAOYSA-L magnesium;hydrogen sulfate;hydroxide;hydrate Chemical compound O.O.[Mg+2].[O-]S([O-])(=O)=O QSOMFNQEXNFPNU-UHFFFAOYSA-L 0.000 claims description 3
- LFCFXZHKDRJMNS-UHFFFAOYSA-L magnesium;sulfate;hydrate Chemical compound O.[Mg+2].[O-]S([O-])(=O)=O LFCFXZHKDRJMNS-UHFFFAOYSA-L 0.000 claims description 3
- LVCQAASWWXWFTQ-UHFFFAOYSA-L magnesium;sulfate;pentahydrate Chemical compound O.O.O.O.O.[Mg+2].[O-]S([O-])(=O)=O LVCQAASWWXWFTQ-UHFFFAOYSA-L 0.000 claims description 3
- QIGOZTHDQZFDPY-UHFFFAOYSA-L magnesium;sulfate;trihydrate Chemical compound O.O.O.[Mg+2].[O-]S([O-])(=O)=O QIGOZTHDQZFDPY-UHFFFAOYSA-L 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 2
- 238000009826 distribution Methods 0.000 claims description 2
- SBSZHUBPJCUAAL-UHFFFAOYSA-L magnesium;sulfate;tetrahydrate Chemical compound O.O.O.O.[Mg+2].[O-]S([O-])(=O)=O SBSZHUBPJCUAAL-UHFFFAOYSA-L 0.000 claims description 2
- 238000002791 soaking Methods 0.000 claims description 2
- 238000013019 agitation Methods 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 8
- 238000004064 recycling Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 93
- 239000011550 stock solution Substances 0.000 description 45
- 238000009616 inductively coupled plasma Methods 0.000 description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 32
- 238000002156 mixing Methods 0.000 description 27
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 23
- 238000003828 vacuum filtration Methods 0.000 description 20
- 238000001816 cooling Methods 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 18
- 239000002002 slurry Substances 0.000 description 18
- 238000000498 ball milling Methods 0.000 description 16
- 238000011084 recovery Methods 0.000 description 13
- 229910052759 nickel Inorganic materials 0.000 description 12
- 239000007791 liquid phase Substances 0.000 description 10
- 239000006184 cosolvent Substances 0.000 description 9
- 239000012065 filter cake Substances 0.000 description 9
- 238000001914 filtration Methods 0.000 description 9
- 239000006260 foam Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000000047 product Substances 0.000 description 9
- 229920006395 saturated elastomer Polymers 0.000 description 9
- 238000007873 sieving Methods 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 238000012546 transfer Methods 0.000 description 9
- 238000005303 weighing Methods 0.000 description 9
- 238000001514 detection method Methods 0.000 description 8
- 239000011259 mixed solution Substances 0.000 description 8
- 238000007781 pre-processing Methods 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 238000007598 dipping method Methods 0.000 description 6
- 238000003723 Smelting Methods 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 230000001939 inductive effect Effects 0.000 description 4
- 239000000395 magnesium oxide Substances 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910052681 coesite Inorganic materials 0.000 description 3
- 229910052906 cristobalite Inorganic materials 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 229910052682 stishovite Inorganic materials 0.000 description 3
- 229910052905 tridymite Inorganic materials 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 206010067484 Adverse reaction Diseases 0.000 description 1
- 229910017970 MgO-SiO2 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000006838 adverse reaction Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052839 forsterite Inorganic materials 0.000 description 1
- 239000003864 humus Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000008247 solid mixture Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/04—Working-up slag
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/005—Preliminary treatment of scrap
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/20—Obtaining alkaline earth metals or magnesium
- C22B26/22—Obtaining magnesium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
- C22B7/007—Wet processes by acid leaching
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/04—Production of homogeneous polycrystalline material with defined structure from liquids
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention relates to the field of chemical industry, and particularly relates to a method for recovering magnesium from nickel-iron slag. The magnesium in the nickel-iron slag is converted into the magnesium sulfate for recycling the magnesium by adopting the all-wet process, the process is simple, the operation is easy, the requirement on equipment is low, the magnesium recycling rate is high, the application range of the magnesium sulfate is wide, the added value of the product is high, and the comprehensive utilization rate of the nickel-iron slag can be improved.
Description
Technical Field
The invention relates to the field of chemical industry, in particular to a method for recovering magnesium from ferronickel slag.
Background
The ferronickel slag is industrial waste slag produced in the ferronickel production process, and is the fourth most metallurgical waste slag after the iron slag, the steel slag and the red mud. Compared with other metallurgical slag, the valuable metal of the ferronickel slag has low recovery value and large slag discharge amount, and becomes a big problem of metallurgical slag treatment gradually, the common treatment mode of the ferronickel slag mainly comprises stockpiling and landfill, but the two treatment modes can cause a large amount of stockpiling of the ferronickel slag, not only occupies land and pollutes environment, but also brings serious challenges to sustainable development of ferronickel smelting, therefore, relevant scientific research of vigorous comprehensive utilization of the ferronickel slag is developed, and the promotion of value-added utilization of the ferronickel slag has great significance to the ferronickel industry.
According to different ferronickel production methods, the ferronickel slag can be divided into blast furnace ferronickel smelting slag, rotary kiln ferronickel smelting slag and pre-reduction-electric furnace ferronickel smelting slag, at present, the domestic ferronickel slag is mainly obtained in the process of reducing and smelting ferronickel by using humus type laterite-nickel ore in an electric furnace, and the main component of the ferronickel slag is SiO2MgO and FeO, the minor component being Cr2O3、Al2O3CaO, etc., belonging to FeO-MgO-SiO2Ternary slag system, with the nickel iron slag mineral structure dominated by the forsterite phase, XRD results showed that its main mineral composition was 2MgO SiO2、FeO﹒SiO2And MgO & lt. SiO & gt2. The recyclable valuable metals in the nickel-iron slag smelted by the pre-reduction-electric furnace are less, but the mass percentage of magnesium oxide in the nickel-iron slag is usually between 25 and 40 percent, so that the recycling of magnesium in the nickel-iron slag is of great significance for the high-value comprehensive utilization of the nickel-iron slag.
At present, although there is a report of recovering magnesium by directly preparing metal magnesium by vacuum reduction of nickel-iron slag, the magnesium oxide has high stability and needs to be recovered under the conditions of high temperature and high vacuum, so that the process has high requirements on equipment, reduction conditions and safety, and cannot be industrially applied for a while.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defects that the process for preparing metal magnesium by utilizing nickel-iron slag through vacuum reduction to recover magnesium in the prior art has high requirements on equipment, reduction conditions and safety and cannot be applied industrially, thereby providing a method for recovering magnesium from nickel-iron slag.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for recovering magnesium from ferronickel slag comprises the steps of immersing the ferronickel slag in concentrated sulfuric acid under normal pressure, adding crystal seeds, and crystallizing to separate out magnesium sulfate.
Further, the normal-pressure impregnation comprises the step of dissolving the nickel-iron slag in concentrated sulfuric acid with the concentration of 5-18N, and stirring and leaching at 140-210 ℃, wherein the leaching solution-solid ratio of the sulfuric acid solution to the nickel-iron slag is (5-20): 1 in terms of L/Kg.
Further, in the normal-pressure dipping step, the stirring speed is 150-1500 r/min, and the leaching time is 30-240 min.
Further, the normal-pressure impregnation comprises the step of dissolving the nickel iron slag in concentrated sulfuric acid with the concentration of 8-16N, and stirring and leaching at 160-190 ℃, wherein the solid ratio of the sulfuric acid solution to the leaching solution of the nickel iron slag is (6-10) in terms of L/Kg: 1.
further, in the normal-pressure dipping step, the stirring speed is 350-1000 r/min, and the leaching time is 60-150 min.
Further, the seed crystal is at least one of anhydrous magnesium sulfate, magnesium sulfate monohydrate, magnesium sulfate dihydrate, magnesium sulfate trihydrate, magnesium sulfate tetrahydrate, magnesium sulfate pentahydrate, magnesium sulfate hexahydrate and magnesium sulfate heptahydrate.
Further, the seed crystal coefficient of the seed crystal is 0.2-1.2.
Further, the seed crystal coefficient of the seed crystal is preferably 0.4-1.
Further, in the crystallization step, the crystallization temperature is-30 to 95 ℃, the crystallization time is 3 to 20 hours, and the crystallization stirring speed is 10 to 500 r/min.
Furthermore, in the crystallization step, the crystallization temperature is preferably-20-80 ℃, the crystallization time is preferably 5-15h, and the crystallization stirring speed is preferably 30-200 r/min.
Furthermore, the particle size of the nickel-iron slag is less than or equal to 38 mu m.
Further, the method for recovering magnesium from the ferronickel slag further comprises the step of washing the crystallized magnesium sulfate by using a washing liquid.
Further, the washing solution is a saturated magnesium sulfate solution or an absolute ethyl alcohol solution, and the washing temperature is less than or equal to 25 ℃.
The technical scheme of the invention has the following advantages:
1. according to the method for recovering magnesium from the ferronickel slag, magnesium in the ferronickel slag is converted into magnesium sulfate by adopting a full-wet process for recovering magnesium, the process is simple, the operation is easy, the requirement on equipment is low, the magnesium recovery rate is high, the application range of the magnesium sulfate is wide, the added value of products is high, and the comprehensive utilization rate of the ferronickel slag can be improved.
2. According to the method for recovering magnesium from the ferronickel slag, provided by the invention, the magnesium in the ferronickel slag is converted into magnesium sulfate as much as possible to enter the solution by limiting the process parameters such as the concentration of concentrated sulfuric acid, the leaching temperature, the solid-to-solid ratio of the leaching solution and the like in the normal-pressure dipping process, so that the leaching rate of the magnesium is improved, and the recovery rate of the magnesium is improved.
3. According to the method for recovering magnesium from the ferronickel slag, provided by the invention, the magnesium sulfate can be precipitated as much as possible by limiting the technological parameters such as the crystal seed coefficient, the crystallization temperature, the crystallization time and the like in the crystallization process.
4. According to the method for recovering magnesium from the ferronickel slag, provided by the invention, the particle size of the ferronickel slag is limited, so that the magnesium can be leached without adding any cosolvent in the leaching process, thereby reducing the introduction of impurities and improving the purity of a magnesium sulfate product.
5. According to the method for recovering magnesium from the ferronickel slag, provided by the invention, the washing and drying steps are arranged, so that the magnesium sulfate crystal can be washed to remove impurities, and the purity of the magnesium sulfate product is further improved.
6. According to the method for recovering magnesium from the ferronickel slag, provided by the invention, the washing liquid and the washing temperature are limited, so that the dissolution loss of magnesium sulfate in the washing process can be reduced or even avoided, and the recovery rate of magnesium is further improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of a method for recovering magnesium from ferronickel slag in example 1 of the present invention;
FIG. 2 is an XRD pattern of a ferronickel slag feedstock used in the present invention;
figure 3 is an XRD pattern of the product (hydrated) magnesium sulfate of example 1 of the present invention.
Detailed Description
The following examples are provided to better understand the present invention, not to limit the best mode, and not to limit the content and protection scope of the present invention, and any product that is the same or similar to the present invention and is obtained by combining the present invention with other features of the prior art and the present invention falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The invention provides a method for recovering magnesium from ferronickel slag, which comprises the steps of soaking the ferronickel slag in concentrated sulfuric acid under normal pressure, adding seed crystals, and crystallizing to separate out magnesium sulfate.
Specifically, the normal-pressure impregnation comprises the steps of dissolving the ferronickel slag in concentrated sulfuric acid with the concentration of 5-18N, and stirring and leaching at 140-210 ℃, wherein the solid-to-solid ratio of the sulfuric acid solution to the ferronickel slag is (5-20): 1 according to L/Kg. In the normal-pressure dipping step, the stirring speed is 150-1500 r/min, and the leaching time is 30-240 min.
Preferably, the normal-pressure impregnation comprises the steps of dissolving the nickel iron slag in concentrated sulfuric acid with the concentration of 8-16N, and stirring and leaching at 160-190 ℃, wherein the solid ratio of the sulfuric acid solution to the leaching solution of the nickel iron slag is (6-10) in terms of L/Kg: 1. in the normal-pressure dipping step, the stirring speed is 350-1000 r/min, and the leaching time is 60-150 min.
Specifically, the crystal seed is magnesium sulfate, the number of crystal water carried by the magnesium sulfate is more than or equal to 0 and less than or equal to 7, and preferably, the crystal seed is at least one of anhydrous magnesium sulfate, magnesium sulfate monohydrate, magnesium sulfate dihydrate, magnesium sulfate trihydrate, magnesium sulfate pentahydrate, magnesium sulfate hexahydrate and magnesium sulfate heptahydrate. The seed crystal coefficient of the seed crystal is 0.2-1.2, preferably 0.4-1.
In the crystallization step, the crystallization temperature is-30-95 ℃, the crystallization time is 3-20h, and the crystallization stirring speed is 10-500 r/min. Preferably, the crystallization temperature is-20 to 80 ℃, the crystallization time is 5 to 15 hours, and the crystallization stirring speed is 30 to 200 r/min.
Wherein, in order to make the magnesium in the nickel-iron slag easier to leach, the particle size of the nickel-iron slag is set to be less than or equal to 38 μm. Generally, the initial shape of the ferronickel slag directly obtained from a factory is spherical or elliptical, and the particle size is generally 1-10 mm, so that the particle size of the ferronickel slag meets the requirement, and the method further comprises the step of pretreating the ferronickel slag before dipping the ferronickel slag. In addition, some cosolvent may be added to the concentrated sulfuric acid to assist the dissolution, but the addition of the cosolvent may cause the introduction of impurities.
Specifically, the pretreatment comprises the steps of drying the ferronickel slag, grinding the ferronickel slag, and then screening the ferronickel slag to obtain fine ferronickel slag powder with a certain particle size distribution.
The drying step can be carried out by adopting a blast drying oven or other drying equipment, the drying temperature is more than or equal to 100 ℃, the drying time is 4-30 hours, preferably, the drying temperature is 105-150 ℃, and the drying time is 6-12 hours. The ore grinding step can be carried out by adopting a planetary ball mill, or other ball mills, when the planetary ball mill is adopted, the rotation speed is 200-400 r/min, the revolution speed is 400-800 r/min, and the ore grinding time is more than or equal to 1 h. The screening adopts a screen with the aperture larger than or equal to 300 meshes, and the grain size of the obtained nickel iron ore slag powder for leaching is less than or equal to 38 mu m after screening.
After normal pressure leaching, ore pulp consisting of leachate and slag phase is obtained, most of magnesium and a small amount of impurities in the nickel-iron slag enter a liquid phase, and therefore, in order to separate filtrate and solid slag for crystallization, a solid-liquid separation step needs to be arranged after normal pressure leaching.
Specifically, the solid-liquid separation step comprises the steps of settling a liquid-solid mixture obtained after atmospheric leaching for a period of time, and then carrying out vacuum filtration to separate filtrate from solid slag, wherein the separated solid slag is washed and filtered by dilute sulfuric acid to reduce the carrying of the solid slag on the filtrate, the concentration of the dilute sulfuric acid used for washing is 2-10N, preferably 3-8N, the acidity in the filtrate can be diluted in a transitional manner when the concentration of the dilute sulfuric acid used for washing is too low, the viscosity is large when the concentration of the dilute sulfuric acid used for washing is too high, and the washing effect is poor. During cleaning, tap water or pure water is avoided to avoid adverse reactions such as hydrolysis.
In order to improve the purity of the product magnesium sulfate, after the magnesium sulfate is crystallized and separated out, a step of washing the crystallized and separated out magnesium sulfate by using a washing liquid is also arranged.
Wherein the washing liquid is saturated magnesium sulfate solution or absolute ethyl alcohol solution, and the washing temperature is room temperature or lower, namely the washing temperature is less than or equal to 25 ℃, so that the dissolution loss of magnesium sulfate in the washing process is avoided.
In order to obtain magnesium sulfate with different amounts of crystal water, a drying step is further arranged after washing, the drying mode is air blast drying or static drying, fluidized drying, suspension drying and the like, if the target product is hydrated magnesium sulfate, the drying temperature is less than or equal to 100 ℃, the drying temperature is different, the amount of crystal water contained in the obtained magnesium sulfate is different, the higher the temperature is, the smaller the amount of crystal water is, and if the target product is anhydrous magnesium sulfate, the higher the temperature is, the drying and even calcining are required.
The XRD (X-ray diffraction) pattern of the main phase structure of the ferronickel slag raw material used in the application is shown in figure 1, and the main chemical components are shown in table 1.
TABLE 1 table of main chemical compositions of ferronickel slag raw material
Example 1
As shown in fig. 1, the present embodiment relates to a method for recovering magnesium from ferronickel slag, which includes the following steps:
s1, preprocessing: drying the ferronickel slag at 105 ℃ for 12h, setting the rotation speed of the ferronickel slag on a planetary ball mill to be 300r/min, setting the revolution speed to be 600r/min, grinding the ore for 3h, sieving the ferronickel slag through a 300-mesh sieve after ball milling to obtain ferronickel slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained ferronickel slag fine powder is used as a solute.
S2, leaching: weighing 20g of ferronickel slag fine powder, placing the ferronickel slag fine powder into a three-neck flask, and mixing the ferronickel slag fine powder with the liquid-solid ratio of 20: 1(ml/g), adding a 15N sulfuric acid solution (N represents equivalent concentration), adding no cosolvent, moving the flask into a constant-temperature heating sleeve, heating while stirring, starting timing when the temperature of the solution rises to 180 ℃, taking out the flask after constant-temperature stirring for 120min, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing the filter cake for 2 times by using a 3N hot sulfuric acid solution after the filtration is finished to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using the 3N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma) in the solution, and obtaining the leaching rate of magnesium of 95.22%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the seed crystal coefficient is 0.5: 1 as a seed crystal, to induce crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 90 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at a stirring rate of 50r/min, taking out the slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation by using a vacuum suction filter pump, analyzing liquid phase components by adopting ICP, and calculating the crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentrations by ICP, and the crystals were dried at 30 ℃ for 24h to obtain final (hydrated) magnesium sulfate crystals.
The main chemical components of the (hydrated) magnesium sulfate crystal are shown in the table 2, the mass percentage of magnesium is 11.85 percent, and the total recovery rate of magnesium in the method reaches 79.14 percent.
TABLE 2 main chemical composition of (hydrated) magnesium sulfate crystals
Example 2
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the ferronickel slag at 105 ℃ for 8h, setting the rotation speed of the ferronickel slag on a planetary ball mill to be 250r/min, setting the revolution speed of the ferronickel slag to be 500r/min, grinding the nickel slag for 6h, sieving the nickel slag by a 300-mesh sieve to obtain ferronickel slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball mill for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches to obtain the ferronickel slag fine powder as a solute.
S2, leaching: weighing 20g of fine ferronickel slag powder, placing the fine ferronickel slag powder into a three-neck flask, and mixing the fine ferronickel slag powder and the three-neck flask in a liquid-solid ratio of 10: 1(ml/g), adding a sulfuric acid solution with the concentration of 11N, adding no cosolvent, moving a flask into a constant-temperature heating sleeve, heating while stirring, timing when the temperature of the solution rises to 170 ℃, stirring at constant temperature for 60min, taking out the flask, standing for 30min, carrying out vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using a hot sulfuric acid solution with the concentration of 5N after the filtration is finished, obtaining a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using the hot sulfuric acid solution with the concentration of 5N, analyzing the concentration of each element by using ICP (inductively coupled plasma), and obtaining the leaching rate of magnesium of 94.31%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the crystal seed coefficient is 1: 1 as a seed crystal, and inducing crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 85 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (85 deg.C), stirring at 60r/min, taking out slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation with vacuum suction filter pump, analyzing liquid phase component with ICP, and calculating crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentrations by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 11.64 percent, and the total recovery rate of the magnesium in the method reaches 78.39 percent.
Example 3
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, pretreatment: drying the nickel-iron slag at 130 ℃ for 6h, setting the autorotation speed on a planetary ball mill to be 200r/min, the revolution speed to be 400r/min, grinding the ore for 5h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of fine ferronickel slag powder, placing the fine ferronickel slag powder into a three-neck flask, and mixing the fine ferronickel slag powder and the three-neck flask according to a liquid-solid ratio of 20: 1(ml/g), adding a 15N sulfuric acid solution, adding no cosolvent, moving a flask into a constant-temperature heating sleeve, heating while stirring, starting timing when the temperature of the solution rises to 160 ℃, stirring at constant temperature for 120min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using a 5N hot sulfuric acid solution after filtration is finished to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using the 5N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma), wherein the leaching rate of magnesium is 94.58%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the crystal seed coefficient is 1: 1 as a seed crystal, to induce crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 90 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at a stirring rate of 90r/min, taking out the slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation by using a vacuum suction filter pump, analyzing liquid phase components by adopting ICP, and calculating the crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for each element concentration by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
Through detection, the mass percentage of the magnesium is 10.94%, and the total recovery rate of the magnesium by the method reaches 78.61%.
Example 4
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, pretreatment: drying the nickel-iron slag at 105 ℃ for 12h, setting the autorotation speed on a planetary ball mill to be 300r/min, the revolution speed to be 600r/min, grinding the ore for 3h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of fine ferronickel slag powder, placing the fine ferronickel slag powder into a three-neck flask, and mixing the fine ferronickel slag powder and the fine ferronickel slag powder at a liquid-solid ratio of 15: 1(ml/g), adding a 13N sulfuric acid solution, adding no cosolvent, moving a flask into a constant-temperature heating sleeve, heating while stirring, starting timing when the temperature of the solution rises to 180 ℃, stirring at constant temperature for 60min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using a 5N hot sulfuric acid solution after filtration to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using the 5N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma), wherein the leaching rate of magnesium is 93.67%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the crystal seed coefficient is 0.3: 1 as a seed crystal, and inducing crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 80 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (80 deg.C), stirring at 60r/min, taking out slurry when the solution temperature is reduced to room temperature, performing solid-liquid separation with vacuum suction filter pump, analyzing liquid phase component with ICP, and calculating crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for each element concentration by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 11.33 percent, and the total recovery rate of the magnesium in the method reaches 77.86 percent.
Example 5
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the nickel-iron slag at 105 ℃ for 8h, setting the autorotation speed on a planetary ball mill to be 250r/min, the revolution speed to be 500r/min, grinding the ore for 6h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of fine ferronickel slag powder, placing the fine ferronickel slag powder into a three-neck flask, and mixing the fine ferronickel slag powder and the fine ferronickel slag powder at a liquid-solid ratio of 8: 1(ml/g) of the solution, adding 8N sulfuric acid solution, adding hydrogen peroxide, wherein the adding amount of the hydrogen peroxide is 5% of the volume of the sulfuric acid solution, then moving the flask into a constant-temperature heating sleeve, heating while stirring, timing when the temperature of the solution rises to 170 ℃, stirring at constant temperature for 60min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing the filter cake for 2 times by using 5N hot sulfuric acid solution after filtration is finished to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using 5N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma), and obtaining the leaching rate of magnesium of 95.04%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the crystal seed coefficient is 1: 1 as a seed crystal, and inducing crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 90 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at 60r/min, taking out slurry when the solution temperature is reduced to room temperature, performing solid-liquid separation with vacuum filtration pump, analyzing liquid phase component with ICP, and calculating crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentrations by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 10.82 percent, and the total recovery rate of the magnesium by the method reaches 79.00 percent.
Example 6
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the nickel-iron slag at 130 ℃ for 6h, setting the autorotation speed on a planetary ball mill to be 200r/min, the revolution speed to be 400r/min, grinding the ore for 5h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of fine ferronickel slag powder, placing the fine ferronickel slag powder into a three-neck flask, and mixing the fine ferronickel slag powder and the three-neck flask according to a liquid-solid ratio of 20: 1(ml/g), adding a 15N sulfuric acid solution, adding no cosolvent, moving a flask into a constant-temperature heating sleeve, heating while stirring, starting timing when the temperature of the solution rises to 180 ℃, stirring at constant temperature for 120min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using a 5N hot sulfuric acid solution after filtration to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using the 5N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma), wherein the leaching rate of magnesium is 93.18%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the seed crystal coefficient is 0.5: 1 as a seed crystal, to induce crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. Firstly, 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the initial crystallization temperature is set to be 90 ℃, the final crystallization temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at a stirring rate of 50r/min, taking out the slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation by using a vacuum suction filter pump, analyzing liquid phase components by adopting ICP, and calculating the crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for each element concentration by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 11.13 percent, and the total recovery rate of the magnesium by the method reaches 77.45 percent by volume.
Example 7
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the nickel-iron slag at 140 ℃ for 5h, setting the autorotation speed on a planetary ball mill to be 300r/min, the revolution speed to be 600r/min, grinding the ore for 3h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of ferronickel slag fine powder, placing the ferronickel slag fine powder into a three-neck flask, and mixing the ferronickel slag fine powder with the liquid-solid ratio of 20: 1(ml/g) under the condition, adding a 15N sulfuric acid solution, simultaneously adding concentrated nitric acid, wherein the addition amount of the concentrated nitric acid is 5% of the addition volume of the sulfuric acid solution, then moving the flask into a constant-temperature heating sleeve, stirring while heating, timing when the temperature of the solution rises to 180 ℃, stirring at constant temperature for 120min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing the filter cake for 2 times by using a 5N hot sulfuric acid solution after filtration to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to ICP 400ml by using the 5N hot sulfuric acid solution, analyzing the concentration of each element by using the solution, and obtaining the leaching rate of magnesium of 93.79%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the seed crystal coefficient is 0.75: 1 as a seed crystal, to induce crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 90 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 16 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at a stirring rate of 50r/min, taking out the slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation by using a vacuum suction filter pump, analyzing liquid phase components by adopting ICP, and calculating the crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentrations by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 10.88 percent, and the total recovery rate of the magnesium in the method reaches 77.96 percent.
Example 8
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the nickel-iron slag at 140 ℃ for 5h, setting the autorotation speed on a planetary ball mill to be 300r/min, the revolution speed to be 600r/min, grinding the ore for 3h, sieving the ore by a 300-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 38 mu m, returning the particles with the particle size of more than 38 mu m to the next batch of ball milling for ensuring that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the sieved materials of all batches, wherein the obtained nickel-iron slag fine powder is used as solute.
S2, leaching: weighing 20g of ferronickel slag fine powder, placing the ferronickel slag fine powder into a three-neck flask, and mixing the ferronickel slag fine powder with the liquid-solid ratio of 8: 1(ml/g), adding 11N sulfuric acid solution, adding no cosolvent, moving a flask into a constant-temperature heating sleeve, heating while stirring, starting timing when the temperature of the solution rises to 120 ℃, stirring at constant temperature for 80min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using 5N hot sulfuric acid solution after filtration is finished to obtain a washing solution, mixing the washing solution with the filtrate, adjusting the mixed solution to 400ml by using 5N hot sulfuric acid solution, analyzing the concentration of each element by using ICP (inductively coupled plasma), wherein the leaching rate of magnesium is 95.14%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the seed crystal coefficient is 0.25: 1 as a seed crystal, and inducing crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the crystallization initial temperature is set to be 85 ℃, the crystallization final temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 12 hours. Adding seed crystal into the stock solution at the beginning of cooling (85 deg.C), stirring at a stirring rate of 60r/min, taking out the slurry when the solution temperature is reduced to room temperature from the initial temperature, performing solid-liquid separation by using a vacuum suction filter pump, analyzing liquid phase components by adopting ICP, and calculating the crystallization rate of magnesium sulfate. And (3) adopting a saturated concentration magnesium sulfate solution according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentrations by ICP, and the crystals were air-dried at room temperature to obtain final (hydrated) magnesium sulfate crystals.
The detection proves that the mass percentage of the magnesium is 11.80 percent, and the total recovery rate of the magnesium by the method reaches 79.08 percent.
Example 9
The embodiment relates to a method for recovering magnesium from ferronickel slag, which comprises the following steps:
s1, preprocessing: drying the nickel-iron slag at 85 ℃ for 12h, setting the autorotation speed on a planetary ball mill to be 200r/min, the revolution speed to be 400r/min, grinding the ore for 15min, sieving the ore by a 200-mesh sieve after ball milling to obtain nickel-iron slag powder with the particle size of less than 75 microns, returning the particles with the particle size of more than 75 microns to the next batch for ball milling in order to ensure that the nickel slag used in each group of tests has the same components, repeating the steps, and finally uniformly mixing the materials after all batches of screening to obtain the nickel-iron slag fine powder as solute.
S2, leaching: weighing 20g of ferronickel slag fine powder, placing the ferronickel slag fine powder into a three-neck flask, and mixing the ferronickel slag fine powder with the liquid-solid ratio of 20: 1(ml/g) under the condition, adding 15N sulfuric acid solution, adding nitric acid solution, wherein the addition amount of the nitric acid solution is 5% of the addition volume of the sulfuric acid solution, then moving the flask into a constant-temperature heating sleeve, heating and stirring, timing when the temperature of the solution rises to 180 ℃, stirring at constant temperature for 120min, taking out the flask, standing for 30min, performing vacuum filtration on the leached slurry by using a Buchner funnel, washing a filter cake for 2 times by using 3N hot sulfuric acid solution after filtration to obtain washing liquid, mixing the washing liquid with the filtrate, adjusting the mixed liquid to ICP 400ml by using 3N hot sulfuric acid solution, analyzing the concentration of each element by using the solution, and obtaining the leaching rate of magnesium of 80.24%. The filtrate obtained under these conditions was used as a magnesium sulfate crystallization stock solution.
S3, crystallization: the seed crystal coefficient is 0.5: 1 as a seed crystal, to induce crystallization of magnesium sulfate in the magnesium sulfate crystallization stock solution. Firstly, 400ml of crystallization stock solution is placed in a big beaker and is placed in a water bath kettle, the top of the water bath kettle is sealed by foam, the temperature fluctuation of a heat transfer medium (water) caused by external airflow is reduced, the initial crystallization temperature is set to be 90 ℃, the final crystallization temperature is set to be room temperature (25 ℃) by controlling the cooling rate of the crystallization stock solution, and the crystallization time is set to be 10 hours. Adding seed crystal into the stock solution at the beginning of cooling (90 deg.C), stirring at 50r/min, taking out slurry when the solution is cooled to room temperature from the initial temperature, performing solid-liquid separation with vacuum suction filter pump, analyzing liquid phase component with ICP, and calculating crystallization rate of magnesium sulfate. And (3) crystallizing by adopting a magnesium sulfate solution with saturated concentration according to a liquid-solid ratio of 3: 1(ml/g), followed by slight stirring and vacuum filtration, the filtrate was analyzed for the respective element concentration by ICP, and the crystals were dried at 30 ℃ for 24 hours to obtain final (hydrated) magnesium sulfate crystals.
The (hydrated) magnesium sulfate crystal contains N element through detection, the main chemical components of the (hydrated) magnesium sulfate crystal are shown in table 3, the mass percentage of magnesium is 9.99%, and the recovery rate of magnesium is 66.70%. The XRD pattern of (hydrated) magnesium sulfate is shown in fig. 3.
TABLE 3 main chemical composition of (hydrated) magnesium sulfate crystals
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (5)
1. A method for recovering magnesium from ferronickel slag is characterized by comprising the steps of soaking the ferronickel slag in concentrated sulfuric acid under normal pressure, adding seed crystals, and crystallizing to separate out magnesium sulfate;
the normal-pressure impregnation comprises the steps of dissolving the nickel-iron slag in concentrated sulfuric acid with the concentration of 8-16N, and stirring and leaching at the temperature of 140-210 ℃, wherein the leaching solution-solid ratio of the sulfuric acid solution to the nickel-iron slag is (5-20): 1 in terms of L/kg;
before the ferronickel slag is soaked, the step of pretreating the ferronickel slag is also included; the pretreatment comprises the steps of drying the ferronickel slag, grinding the ferronickel slag, and screening to obtain fine ferronickel slag powder with a certain particle size distribution;
after leaching at normal pressure, a solid-liquid separation step is arranged, the separated solid slag is cleaned and filtered by dilute sulfuric acid to reduce the carrying of the solid slag on filtrate, and the concentration of the dilute sulfuric acid used for cleaning is 2-10N;
the drying temperature is more than or equal to 100 ℃, and the drying time is 4-30 h;
the particle size of the nickel-iron slag is less than or equal to 38 mu m;
the seed crystal coefficient of the seed crystal is 0.2-1.2; in the crystallization step, the crystallization temperature is-30-95 ℃, the crystallization time is 3-20h, and the crystallization stirring speed is 10-500 r/min;
the method for recovering magnesium from the ferronickel slag further comprises the step of washing the magnesium sulfate crystallized and separated out by adopting washing liquor, wherein the washing liquor is saturated magnesium sulfate solution or absolute ethyl alcohol solution, and the washing temperature is less than or equal to 25 ℃.
2. The method as claimed in claim 1, wherein in the step of normal pressure impregnation, the stirring speed is 150 to 1500r/min, and the leaching time is 30 to 240 min.
3. The method according to any one of claims 1 to 2, wherein the atmospheric impregnation comprises a step of agitation leaching at 160 to 190 ℃, and the leaching solution solid ratio of the sulfuric acid solution to the nickel iron slag is (6 to 10) in terms of L/kg: 1, the stirring speed is 350-1000 r/min, and the leaching time is 60-150 min.
4. The method of any one of claims 1-2, wherein the seed crystal is at least one of anhydrous magnesium sulfate, magnesium sulfate monohydrate, magnesium sulfate dihydrate, magnesium sulfate trihydrate, magnesium sulfate tetrahydrate, magnesium sulfate pentahydrate, magnesium sulfate hexahydrate, and magnesium sulfate heptahydrate.
5. The method according to any one of claims 1 to 2, wherein the seed crystal index is 0.4 to 1.
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