CN118026127A - Method for recovering ferric phosphate from waste slag containing aluminum and ferric phosphate - Google Patents
Method for recovering ferric phosphate from waste slag containing aluminum and ferric phosphate Download PDFInfo
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- CN118026127A CN118026127A CN202410234592.7A CN202410234592A CN118026127A CN 118026127 A CN118026127 A CN 118026127A CN 202410234592 A CN202410234592 A CN 202410234592A CN 118026127 A CN118026127 A CN 118026127A
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- aluminum
- slag
- phosphate
- iron
- ferrophosphorus
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- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 title claims abstract description 206
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 202
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 193
- 239000002893 slag Substances 0.000 title claims abstract description 138
- 239000005955 Ferric phosphate Substances 0.000 title claims abstract description 135
- 229940032958 ferric phosphate Drugs 0.000 title claims abstract description 135
- 229910000399 iron(III) phosphate Inorganic materials 0.000 title claims abstract description 135
- 239000002699 waste material Substances 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 85
- 239000002253 acid Substances 0.000 claims abstract description 146
- 238000002386 leaching Methods 0.000 claims abstract description 89
- 239000007788 liquid Substances 0.000 claims abstract description 87
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 claims abstract description 39
- 150000003839 salts Chemical class 0.000 claims abstract description 21
- 230000001376 precipitating effect Effects 0.000 claims abstract description 13
- 238000005245 sintering Methods 0.000 claims abstract description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 150
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 129
- 239000000243 solution Substances 0.000 claims description 125
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 69
- 229910052742 iron Inorganic materials 0.000 claims description 52
- 239000007864 aqueous solution Substances 0.000 claims description 44
- -1 hydrogen ions Chemical class 0.000 claims description 20
- 239000002244 precipitate Substances 0.000 claims description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims description 15
- 239000001257 hydrogen Substances 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 15
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 11
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 9
- 239000011574 phosphorus Substances 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 8
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 7
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 7
- 239000003513 alkali Substances 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 229910001610 cryolite Inorganic materials 0.000 claims description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 3
- 239000011707 mineral Substances 0.000 claims description 3
- 150000007522 mineralic acids Chemical class 0.000 claims description 2
- 239000013049 sediment Substances 0.000 claims 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims 1
- 238000011084 recovery Methods 0.000 abstract description 17
- 238000004064 recycling Methods 0.000 abstract description 16
- 230000008901 benefit Effects 0.000 abstract description 8
- 239000002002 slurry Substances 0.000 description 45
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 37
- 239000012535 impurity Substances 0.000 description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 238000001914 filtration Methods 0.000 description 19
- 239000007787 solid Substances 0.000 description 19
- 239000000203 mixture Substances 0.000 description 15
- 239000010949 copper Substances 0.000 description 12
- 238000001556 precipitation Methods 0.000 description 12
- 239000002351 wastewater Substances 0.000 description 12
- 238000005406 washing Methods 0.000 description 11
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 10
- 239000000706 filtrate Substances 0.000 description 10
- 229910052802 copper Inorganic materials 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005086 pumping Methods 0.000 description 7
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 5
- 150000003254 radicals Chemical class 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- URRHWTYOQNLUKY-UHFFFAOYSA-N [AlH3].[P] Chemical compound [AlH3].[P] URRHWTYOQNLUKY-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 229910000358 iron sulfate Inorganic materials 0.000 description 4
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 238000004537 pulping Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000009388 chemical precipitation Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 102100029469 WD repeat and HMG-box DNA-binding protein 1 Human genes 0.000 description 1
- 101710097421 WD repeat and HMG-box DNA-binding protein 1 Proteins 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000011143 downstream manufacturing Methods 0.000 description 1
- 229910001447 ferric ion Inorganic materials 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 150000003017 phosphorus Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 239000010926 waste battery Substances 0.000 description 1
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- Manufacture And Refinement Of Metals (AREA)
Abstract
The application relates to the technical field of recovery of ferric phosphate, in particular to a method for recovering ferric phosphate from waste residues containing aluminum and ferric phosphate. The method comprises the following steps: leaching ferric phosphate in the aluminum-containing ferric phosphate waste residue by using a first acid solution to obtain a first inert slag and a first ferrophosphorus solution; leaching aluminum and ferric phosphate in the first inert slag by using a second acid solution to obtain a second inert slag and aluminum-containing phosphorus-iron solution; precipitating ferric phosphate in the aluminum-containing phosphorus iron liquid to obtain first phosphorus iron slag and first aluminum liquid; treating the first ferrophosphorus slag through a third acid solution and ferric salt to obtain a second ferrophosphorus slag and a second aluminum solution; leaching ferric phosphate in the second ferrophosphorus slag by using a fourth acid solution to obtain a second ferrophosphorus solution; and precipitating and sintering the first phosphorus iron liquid and the second phosphorus iron liquid to obtain ferric phosphate. The method adopts the acid leaching process for multiple times, so that the loss rate of the ferrophosphorus is low while the aluminum is deeply and effectively removed, and the recycling economic benefit is increased.
Description
Technical Field
The application relates to the technical field of recovery of ferric phosphate, in particular to a method for recovering ferric phosphate from waste residues containing aluminum and ferric phosphate.
Background
Lithium iron phosphate batteries are widely used in electric energy products, and meanwhile, the scrapping amount of the lithium iron phosphate batteries is rapidly increased. After lithium is removed from the lithium iron phosphate waste battery, aluminum-containing iron phosphate waste residue is obtained, and the aluminum-containing iron phosphate waste residue can be recycled to prepare the iron phosphate.
In the process of recovering the ferric phosphate from the aluminum-containing ferric phosphate waste residues, the aluminum impurities are difficult to remove, and the method is complicated and high in cost. How to remove aluminum on the premise of reducing the loss rate of ferrophosphorus is more difficult. The current recovery work of the aluminum-containing ferric phosphate waste residues is faced with the problem that the aluminum is difficult to deeply remove and the low phosphorus iron loss is simultaneously achieved.
Disclosure of Invention
Based on the above, the application provides a method for recycling ferric phosphate from waste slag containing aluminum and ferric phosphate, which aims at deeply removing aluminum under the condition of low phosphorus iron loss, and the technical scheme is as follows:
a method for recovering iron phosphate from aluminum-containing iron phosphate waste residues, comprising the following steps:
leaching ferric phosphate in the aluminum-containing ferric phosphate waste residue by using a first acid solution to obtain a first inert slag and a first ferrophosphorus solution;
leaching aluminum and ferric phosphate in the first inert slag by using a second acid solution to obtain second inert slag and aluminum-containing phosphorus-containing iron solution, wherein the mole number of hydrogen ions in the second acid solution is larger than that in the first acid solution;
precipitating ferric phosphate in the aluminum-containing phosphorus iron liquid to obtain first phosphorus iron slag and first aluminum liquid;
treating the first ferrophosphorus slag through a third acid solution and ferric salt to obtain a second ferrophosphorus slag and a second aluminum solution;
leaching ferric phosphate in the second ferrophosphorus slag by using a fourth acid solution to obtain a second ferrophosphorus solution;
And precipitating and sintering the first phosphorus iron liquid and the second phosphorus iron liquid to obtain ferric phosphate.
Compared with the traditional scheme, the application has the following beneficial effects:
The application adopts a composite dealumination method, in particular to a method which adopts a plurality of acid leaching processes, utilizes the cooperation of the acid leaching processes and the special treatment of the specific acid leaching processes (the first ferrophosphorus slag is treated by the third acid liquor and the ferric salt, and aluminum is leached by the third acid liquor and the ferric salt), realizes the step removal of aluminum from the aluminum-containing ferric phosphate slag, and obtains the first ferric phosphate and the second ferric phosphate with the impurity level meeting the requirement, and the aluminum impurity removal rate is high. The method has the advantages that the loss rate of ferrophosphorus is low while deep and effective aluminum removal is performed, the recovery rate of ferrophosphorus in the recycling process of the ferric phosphate waste residues is greatly increased, and the recovery economic benefit is increased. Meanwhile, the method for recycling the ferric phosphate has the advantages that the used medicament is single, for example, acid, alkali and ferric salt are used, new impurities can be prevented from being introduced in the process of recycling and removing impurities, the acid leaching process is simple, key parameters are easy to control, the requirement on equipment is low, and the four acid leaching processes can be completed in one set of equipment. The waste water/filtrate produced in the recovery process can be recycled, so that the auxiliary material investment and the waste water discharge are greatly reduced.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present application and to more fully understand the present application and its advantageous effects, the following brief description will be given with reference to the accompanying drawings, which are required to be used in the description of the embodiments. It is evident that the figures in the following description are only some embodiments of the application, from which other figures can be obtained without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow diagram of some embodiments for recovering iron phosphate from an aluminum-containing iron phosphate waste residue;
FIG. 2 is a schematic diagram showing the conversion of the various products of the process of FIG. 1.
Detailed Description
The present application will be described in further detail with reference to specific examples. The present application may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
Terminology
Unless otherwise indicated or contradicted, terms or phrases used herein have the following meanings:
In the present application, a selection range in reference to "and/or", "and/or" includes any one of two or more of the items listed in relation to each other, as well as any and all combinations of the items listed in relation to each other, including any two of the items listed in relation to each other, any more of the items listed in relation to each other, or all combinations of the items listed in relation to each other.
In the present application, the terms "plurality", "plural", "multiple", and the like are used in terms of the number of the terms "plurality", "multiple", and the like, and are not particularly limited, but are greater than 2 or equal to 2 in number. For example, "one or more" means one kind or two or more kinds.
In the present application, a numerical range (i.e., a numerical range) is referred to, and optional numerical distributions are considered to be continuous within the numerical range and include two numerical endpoints (i.e., a minimum value and a maximum value) of the numerical range and each numerical value between the two numerical endpoints unless otherwise specified.
The temperature parameter in the present application is not particularly limited, and may be a constant temperature treatment or may vary within a predetermined temperature range. It should be appreciated that the constant temperature process described allows the temperature to fluctuate within the accuracy of the instrument control. Allows for fluctuations within a range such as + -5 ℃, + -4 ℃, + -3 ℃, + -2 ℃, + -1 ℃.
In the present application,% (w/w) and wt% each represent weight percent,% (v/v) represents volume percent, and% (w/v) represents mass volume percent.
Aiming at the problems that the prior recovery of ferric phosphate from the waste slag containing aluminum and ferric phosphate is difficult to realize deep aluminum removal and low phosphorus iron loss. The present application provides a method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue, in some embodiments, referring to fig. 1 and 2, the method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue comprises the steps of:
s1, leaching ferric phosphate in the aluminum-containing ferric phosphate waste residue by using a first acid solution to obtain a first inert residue and a first ferrophosphorus solution.
The method comprises the steps of mixing aluminum-containing ferric phosphate waste residues with water according to a liquid-solid ratio (2-10) mL:1g of the aluminum-containing ferric phosphate waste residue is mixed to prepare slurry containing aluminum-containing ferric phosphate waste residue, a first acid solution is added into the slurry containing aluminum-containing ferric phosphate waste residue, ferric phosphate in the aluminum-containing ferric phosphate waste residue is leached into the first acid solution, and the first inert residue and the first ferrophosphorus solution are obtained through solid-liquid separation.
Step S1, carrying out preliminary aluminum removal on the aluminum-containing ferric phosphate waste residues by adopting a selective acid leaching method, wherein the selective acid leaching method is based on the leaching dynamic difference of metal aluminum and ferric phosphate in acid liquor, so as to realize the distributed leaching and separation of each component. The selective acid leaching method has the advantages of low cost, simple operation and the like, and can be connected with upstream and downstream processes in the whole working procedure.
Optionally, the amount of the first acid solution satisfies: the mole number of hydrogen ions in the first acid solution is not less than the total mole number of iron and aluminum in the aluminum-containing iron phosphate waste residue.
Further alternatively, the molar ratio of the total mole of iron and aluminum in the aluminum-containing iron phosphate waste residue to the mole of hydrogen ions in the first acid solution is such that: (fe+al): h + = 1: (1-2). For example, the molar ratio satisfies: (fe+al): h +＝1：1、(Fe+Al)：H+＝1：1.5、(Fe+Al)：H+ = 1:2, etc.
Optionally, the first acid solution is selected from aqueous solutions of inorganic acids.
Further alternatively, the mineral acid is selected from sulfuric acid or hydrochloric acid.
It will be appreciated that when the mineral acid is sulfuric acid, the molar ratio of the total moles of iron and aluminum in the aluminum-containing iron phosphate waste residue to sulfuric acid is as follows: (fe+al): h 2SO4 = 1: (0.5-1). For example, the molar ratio satisfies ：(Fe+Al)：H2SO4＝1：0.5、(Fe+Al)：H2SO4＝1：0.75、(Fe+Al)：H2SO4＝1：1 and the like.
Optionally, the system temperature for leaching the ferric phosphate in the aluminum-containing ferric phosphate waste residue by using the first acid solution is 20-80 ℃. For example, the temperature is 20 ℃, 50 ℃, 80 DEG C
Optionally, the leaching time of the ferric phosphate in the aluminum-containing ferric phosphate waste residue in the first acid solution is 1-10 h. For example, the leaching time is 1h, 5h, 10h.
Optionally, before obtaining the first ferrophosphorus solution, the method further comprises the following steps: an oxidizing agent is added to remove impurity copper. For example, while adding the first acid solution, or before adding the first acid solution, or after adding the first acid solution, an oxidizing agent is added to the slurry containing the aluminum-containing iron phosphate waste residue, and as a majority of the iron phosphate in the slurry leaches into the first acid solution, the impurity copper is also removed. Wherein the oxidant comprises hydrogen peroxide, oxygen, ozone, etc.
When the oxidizing agent comprises hydrogen peroxide, a commercially available aqueous solution of hydrogen peroxide may be selected. Optionally, the hydrogen peroxide is used in an amount that: total mole ratio of Al and Cu in the aluminum-containing ferric phosphate waste residue and mole ratio of hydrogen peroxide: (cu+al) H 2O2 =1 (2 to 5). For example ,(Cu+Al):H2O2＝1:2、(Cu+Al):H2O2＝1:4、(Cu+Al):H2O2＝1:5.
Although the selective acid leaching method can remove aluminum, the loss of ferrophosphorus is relatively large. In the step S1, most of ferric phosphate (about 65% -75% of the total ferric phosphate mass) in the aluminum-containing ferric phosphate waste residues is leached by using the first acid solution, and the leached first ferric phosphate solution can meet the impurity level requirement, but a large amount of ferric phosphate is also lost in the first inert slag.
S2, leaching aluminum and ferric phosphate in the first inert slag by using a second acid solution to obtain second inert slag and aluminum-containing phosphorus-containing iron solution, wherein the mole number of hydrogen ions in the second acid solution is larger than that of the first acid solution.
In order to reduce the loss rate of the ferrophosphorus, the step S2 is continuously adopted to recycle the ferrophosphorus in the first inert slag (accounting for 25% -35% of the total mass of the ferric phosphate) by a selective acid leaching method.
In order to leach the iron phosphate in the first inert slag into the second acid solution, the mole number of hydrogen ions in the second acid solution is greater than the mole number of hydrogen ions in the first acid solution. At this time, both the aluminum and the iron phosphate in the first inert slag are leached into the second acid solution, and the second inert slag is mainly graphite slag.
Further alternatively, the molar ratio of the total mole of iron and aluminum in the aluminum-containing iron phosphate waste residue to the mole of hydrogen ions in the second acid solution is such that: (fe+al): h + = 1: (1.6-4). For example, the molar ratio satisfies: (fe+al): h +＝1：1.6、(Fe+Al)：H+＝1：2、(Fe+Al)：H+＝1：3、(Fe+Al)：H+ = 1:4, etc.
Wherein the second acid liquid and the first acid liquid have the same acid type. When the first acid solution is sulfuric acid aqueous solution, the second acid solution is sulfuric acid aqueous solution, and at this time, the molar ratio of the total mole of iron and aluminum in the aluminum-containing iron phosphate waste residue to sulfuric acid is as follows: (fe+al): h 2SO4 = 1: (0.8-2). For example, the molar ratio satisfies ：(Fe+Al)：H2SO4＝1：0.8、(Fe+Al)：H2SO4＝1：1、(Fe+Al)：H2SO4＝1：1.5、(Fe+Al)：H2SO4＝1：2 and the like.
It can be appreciated that the first inert slag can be put into water with a liquid-to-solid ratio of (2-10) mL:1g, and then adding a second acid solution.
Optionally, the system temperature for leaching aluminum and iron phosphate in the first inert slag with the second acid solution is greater than the system temperature for leaching iron phosphate in the aluminum-containing iron phosphate waste slag with the first acid solution.
Optionally, the system temperature for leaching the aluminum and the ferric phosphate in the first inert slag by using the second acid solution is 20-80 ℃. For example, the temperature is 20 ℃, 50 ℃, 80 ℃.
Optionally, the leaching time of the aluminum and the ferric phosphate in the first inert slag in the second acid solution is 1-10 h. For example, the leaching time is 1h, 5h, 10h.
S3, precipitating ferric phosphate in the aluminum-containing phosphorus iron liquid to obtain first phosphorus iron slag and first aluminum liquid.
And S3, primarily separating ferric phosphate and aluminum in the aluminum-containing phosphorus iron liquid, wherein about 75% -85% of aluminum in the aluminum-containing phosphorus iron liquid can be removed, and the subsequent impurity removal difficulty of aluminum is reduced.
Optionally, the method for precipitating iron phosphate in the aluminum-containing phosphorus iron liquid comprises the following steps: mixing the aluminum-containing phosphorus iron liquid with a first alkaline substance to generate a precipitate.
Optionally, the first alkaline substance is selected from one or more of liquid alkali and ammonia water.
Optionally, the amount of the first alkaline substance is such that: the pH value of the system is in the range of 1-4. For example, the pH of the system is set to 1, 1.7, 3, 4, etc.
Optionally, the temperature at which precipitation occurs is 20 ℃ to 90 ℃. For example, the temperature is 20 ℃, 60 ℃, 90 ℃.
Optionally, the time for generating the precipitate is 1-5 h. For example, the time is 1h, 3h, 5h.
After precipitation, solid-liquid separation is carried out, and the first aluminum liquid can realize wastewater recovery. Optionally, the first aluminum liquid is used for preparing other slurry containing aluminum-containing ferric phosphate waste residues. At this time, the first aluminum liquid can replace part of water in the slurry for slurry mixing.
S4, treating the first ferrophosphorus slag through a third acid solution and ferric salt to obtain a second ferrophosphorus slag and a second aluminum solution.
And step S4, a selective acid leaching method is continuously adopted, which is different from the steps S1 and S2, and the aluminum in the first ferrophosphorus slag is leached into the third acid liquor in the step S4 so as to carry out deep aluminum removal, wherein about 15% -25% of the aluminum in the aluminum-containing ferrophosphorus liquid can be removed in the step. Optionally, the amount of the third acid solution satisfies: the mole number of hydrogen ions in the third acid solution is not greater than the mole number of iron in the first ferrophosphorus slag. At this time, the aluminum in the first ferrophosphorus slag is leached into the second acid solution.
Further optionally, the molar ratio of iron in the first ferrophosphorus slag to hydrogen ions in the third acid solution is as follows: fe: h + = 1: (0.2-1). For example, the molar ratio satisfies: fe: h +＝1：0.2、Fe：H+＝1：0.6、Fe：H+ = 1:1, etc.
Wherein the third acid liquid and the first acid liquid have the same acid type. When the first acid solution is sulfuric acid aqueous solution, the third acid solution is also sulfuric acid aqueous solution, and at this time, the molar ratio of sulfuric acid in the iron third acid solution in the first ferrophosphorus slag is as follows: fe: h 2SO4 = 1: (0.1 to 0.5). For example, the molar ratio satisfies the following Fe: h 2SO4＝1：0.1、Fe：H2SO4＝1：0.3、Fe：H2SO4 = 1:0.5, etc.
It can be appreciated that the first ferrophosphorus slag can be put into water with a liquid-solid ratio of (2-10) mL:1g, and then adding a third acid solution and ferric salt.
Optionally, the system temperature for leaching the aluminum in the first ferrophosphorus slag by using the third acid solution and the ferric salt is 20-80 ℃. For example, the temperature is 20 ℃, 50 ℃,80 ℃.
Optionally, the leaching time of the aluminum in the first ferrophosphorus slag in the third acid solution and the ferric salt is 1-10 h. For example, the leaching time is 1h, 5h, 10h.
And S4, adding ferric salt while adopting a selective acid leaching method, wherein the ferric salt is added to improve the concentration of Fe 3+ in the slurry, inhibit the dissolution of ferric phosphate, and prevent the ferric phosphate from leaching into the third acid liquid at the same time of leaching aluminum into the third acid liquid.
Optionally, the iron salt is selected from one or more of iron sulfate, iron phosphate, and iron oxide.
Optionally, the mass of the ferric salt is 1% -20% of the mass of the iron in the first ferrophosphorus slag.
After the aluminum is leached to the third acid liquor, the second aluminum liquor can realize wastewater recovery. Optionally, cryolite is prepared using the second aluminum liquid. At this time, the second aluminum liquid can be sent to the cryolite synthesis process, thereby realizing the recycling of aluminum.
S5, leaching the ferric phosphate in the second ferrophosphorus slag by using a fourth acid solution to obtain a second ferrophosphorus solution.
And S5, continuing the acid leaching method, and carrying out full-component leaching on the second ferrophosphorus slag by using a fourth acid liquor to obtain a second ferrophosphorus liquid with the impurity level meeting the requirement.
Optionally, the molar ratio of iron in the second ferrophosphorus slag to hydrogen ions in the fourth acid liquor is as follows: fe: h + = 1: (1-2). For example, the molar ratio satisfies: fe: h +＝1：1、Fe：H+＝1：1.5、Fe：H+ = 1:2, etc.
Wherein the fourth acid liquid and the first acid liquid have the same acid type. When the first acid solution is sulfuric acid aqueous solution, the fourth acid solution is also sulfuric acid aqueous solution, and at this time, the molar ratio of iron in the second ferrophosphorus slag to sulfuric acid in the fourth acid solution is as follows: fe: h 2SO4 = 1: (0.5-1). For example, the molar ratio satisfies: fe: h 2SO4＝1：0.5、Fe：H2SO4＝1：0.7、Fe：H2SO4 = 1:1, etc.
It can be appreciated that the second ferrophosphorus slag can be put into water with a liquid-solid ratio of (2-10) mL:1g, and then adding a fourth acid solution.
Optionally, the system temperature for leaching the ferric phosphate in the second ferrophosphorus slag by using the fourth acid solution is 20-80 ℃. For example, the temperature is 20 ℃, 50 ℃, 80 ℃.
Optionally, the leaching time of the ferric phosphate in the second ferrophosphorus slag in the fourth acid liquor is 1-10 h. For example, the leaching time is 1h, 5h, 10h.
S6, precipitating and sintering the first phosphorus iron liquid and the second phosphorus iron liquid to obtain ferric phosphate.
Optionally, precipitating and sintering the first ferrophosphorus liquid and the second ferrophosphorus liquid, and comprising the following steps:
And S61, mixing the first ferrophosphorus liquid and the second ferrophosphorus liquid to obtain mixed ferrophosphorus liquid.
Optionally, before obtaining the mixed ferrophosphorus solution, the method further comprises the following steps: and adjusting the molar ratio of iron in the first ferrophosphorus liquid to first acid radicals and/or adjusting the molar ratio of iron in the second ferrophosphorus liquid to first acid radicals, wherein the first acid radicals are acid radicals which are the same as the first acid liquid in the first ferrophosphorus liquid.
When the first acid solution, the second acid solution, the third acid solution and the fourth acid solution are sulfuric acid aqueous solutions, the first acid radical of the first phosphorus iron solution and the second phosphorus iron solution is sulfate radical, and sulfuric acid can be added for adjusting the mole ratio of iron and sulfate radical ions. Optionally, the molar ratio of iron to sulfate ions in the first phosphorus iron bath and/or the second iron phosphate is such that: fe: SO 4- = (1.0 to 1.5): 1.
Optionally, after the mixed ferrophosphorus solution is obtained, the method further comprises the following steps: and adjusting the mole ratio of iron and phosphorus in the mixed ferrophosphorus solution.
Optionally, adding an iron source and/or a phosphorus source to make the mole ratio of iron and phosphorus in the mixed ferrophosphorus solution satisfy: fe: p= (0.8 to 1.2): 1. Further alternatively, the iron source may be an iron salt and the phosphorus source may be a phosphorus salt.
S62, precipitating ferric phosphate in the mixed ferrophosphorus liquid to obtain a precipitate and filtrate.
Optionally, the method for precipitating iron phosphate in the mixed ferrophosphorus solution comprises the following steps: mixing the mixed ferrophosphorus solution with a second alkaline material to produce a precipitate.
Optionally, the second alkaline substance is selected from one or more of liquid alkali and ammonia water.
Optionally, the amount of the second alkaline substance is such that: the pH value of the system is in the range of 1.5-4. For example, the pH of the system is set to 1.5, 3, 4, etc.
Optionally, the temperature at which precipitation occurs is 20 ℃ to 80 ℃. For example, the temperature is 20 ℃, 60 ℃, 80 ℃.
Optionally, the time for generating the precipitate is 1-10 h. For example, the time is 1h, 5h, 10h.
After the ferric phosphate precipitation is obtained, solid-liquid separation is carried out, and the filtrate can realize wastewater recovery. Optionally, the filtrate is used to prepare other slurries containing aluminum-containing ferric phosphate waste residues. At this time, the filtrate can replace part of water in the slurry to carry out slurry mixing.
S63, sintering the precipitate to prepare the ferric phosphate.
Optionally, before sintering the precipitate, the method further comprises the following steps: phosphoric acid was added to the precipitate for conversion.
Through the steps, the battery grade ferric phosphate can be prepared.
The method for recycling the ferric phosphate adopts the composite dealumination, specifically adopts a plurality of acid leaching processes, utilizes the cooperation of the plurality of acid leaching processes and the special treatment of the specific acid leaching process (the first ferrophosphorus slag is treated by the third acid liquor and the ferric salt, and aluminum is leached by the third acid liquor and the ferric salt), realizes the step removal of aluminum from the aluminum-containing ferric phosphate slag, and obtains the first ferric phosphate and the second ferric phosphate with the impurity level meeting the requirement, and the aluminum impurity removal rate is high. The method has the advantages that the loss rate of ferrophosphorus is low while deep and effective aluminum removal is performed, the recovery rate of ferrophosphorus in the recycling process of the ferric phosphate waste residues is greatly increased, and the recovery economic benefit is increased. Meanwhile, the method for recycling the ferric phosphate has the advantages that the used medicament is single, for example, acid, alkali and ferric salt are used, new impurities can be prevented from being introduced in the process of recycling and removing impurities, the acid leaching process is simple, key parameters are easy to control, the requirement on equipment is low, and the four acid leaching processes can be completed in one set of equipment. The waste water/filtrate produced in the recovery process can be recycled, so that the auxiliary material investment and the waste water discharge are greatly reduced.
The method for recycling the ferric phosphate is suitable for deeply removing aluminum in the high-aluminum ferric phosphate waste residues.
Compared with the method for directly recovering the ferric phosphate from the waste slag containing the aluminum ferric phosphate by adopting the alkaline leaching method, the method for recovering the ferric phosphate can reduce the alkaline consumption and the yield of high-salt wastewater. Compared with the method for recovering the ferric phosphate from the waste residue containing the aluminum and the ferric phosphate by adopting an ion exchange method (the ion exchange method realizes separation and purification according to the difference of adsorption capacities of aluminum ions, ferrous ions, ferric ions and other different metal ions in cation exchange), the method for recovering the ferric phosphate is not limited by the adsorption capacity of ion exchange resin, has lower cost and is more suitable for industrial popularization. Compared with chemical precipitation (chemical precipitation is to control the solubility of each component in solution, and to utilize aluminum ions to complex with anions in a system such as phosphate ions, fluoride ions and the like to form insoluble compounds, thereby achieving the effect of deep impurity removal), the method for recovering the ferric phosphate from the waste residue containing aluminum and ferric phosphate has higher recovery rate and relatively loose control of process parameters (such as system pH, precipitant dosage and the like).
The following examples and comparative examples are further illustrated by the fact that the materials used, unless otherwise indicated, are commercially available and that the equipment used, unless otherwise indicated, are commercially available and that the processes involved, unless otherwise indicated, are routine selections by those skilled in the art.
Wherein, the aluminum-containing iron phosphate waste residue is waste iron phosphate residue produced after lithium extraction of lithium iron phosphate battery black powder, for convenience of comparison, the following examples and comparative examples all adopt the same batch of aluminum-containing iron phosphate waste residue obtained after lithium extraction by oxidation, and the component detection results (ICP test) are shown in Table 1:
TABLE 1
Example 1
The embodiment provides a method for recovering ferric phosphate from waste residues containing aluminum and ferric phosphate, which comprises the following steps:
s1: the aluminum-containing ferric phosphate waste residue and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and stirred uniformly at 50 ℃ to obtain the slurry containing the aluminum-containing ferric phosphate waste residues.
Pumping aqueous sulfuric acid solution and aqueous hydrogen peroxide solution into the slurry, and leaching most of ferric phosphate and Cu removal. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al) H 2SO4 =1:0.6, the amount of aqueous hydrogen peroxide solution used is as follows: total mole ratio of Al and Cu in the aluminum-containing ferric phosphate waste residue and mole ratio of hydrogen peroxide: and (Cu+Al) H 2O2 =1:2, fully mixing and stirring the sulfuric acid aqueous solution, the hydrogen peroxide aqueous solution and the slurry, and filtering to obtain the first inert slag and the first ferrophosphorus liquid with the impurity level meeting the requirement.
S2: the first inert slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first inert slag.
Pumping sulfuric acid aqueous solution with the concentration the same as that in the step S1 into slurry containing the first inert slag, and carrying out high-acid leaching on the first inert slag by adopting the sulfuric acid aqueous solution, wherein the dosage of the sulfuric acid aqueous solution is as follows: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al): h 2SO4 = 1:1.2, leaching temperature 60 ℃, leaching time 1H. Filtering to obtain second inert slag and aluminum-phosphorus-containing iron liquid.
S3: adding ammonia water into the aluminum-containing phosphorus iron liquid to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 50 ℃, and then filtering and washing to obtain first phosphorus iron slag and first aluminum liquid, wherein the first aluminum liquid can be used in the next batch S1 step pulping process, so as to realize wastewater recycling.
S4: the liquid-solid ratio of the first ferrophosphorus slag to water is 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first ferrophosphorus slag.
Adding ferric sulfate and sulfuric acid aqueous solution with the same concentration as that in the step S1 into the slurry containing the first ferrophosphorus slag to leach aluminum. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: the molar ratio of iron in the first phosphorus iron slag to sulfuric acid is as follows: fe: h 2SO4 =1:0.3, the amount of iron sulfate used satisfies: the mass of the ferric sulfate is 5% of the iron content in the first ferrophosphorus slag, the leaching temperature is 50 ℃, the leaching time is 2 hours, and the second ferrophosphorus slag and the second aluminum liquid are obtained through filtering and washing.
S5: the second ferrophosphorus slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the second ferrophosphorus slag.
And (3) adding the sulfuric acid aqueous solution with the concentration the same as that of the step S1 into the slurry containing the second ferrophosphorus slag, and carrying out full-component leaching on the second ferrophosphorus slag to obtain a second ferrophosphorus liquid with the impurity level meeting the requirement. Wherein, the mole ratio of iron in the second ferrophosphorus slag to sulfuric acid is as follows: fe: h 2SO4 = 1:1, leaching temperature 60 ℃, time 2H.
S6: adding a proper amount of sulfuric acid into the first ferrophosphorus liquid obtained in the step S1 to adjust the mole ratio of Fe/SO 4- to be 1.2: and 1, mixing the mixed solution with the second ferrophosphorus solution obtained in the step S5 to obtain mixed ferrophosphorus solution, adding ammonia water into the mixed ferrophosphorus solution to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 60 ℃, filtering to obtain precipitate and filtrate, adding phosphoric acid into the precipitate to convert, washing, drying, and sintering to obtain ferric phosphate.
Example 2
The embodiment provides a method for recovering ferric phosphate from waste residues containing aluminum and ferric phosphate, which comprises the following steps:
s1: the aluminum-containing ferric phosphate waste residue and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and stirred uniformly at 50 ℃ to obtain the slurry containing the aluminum-containing ferric phosphate waste residues.
Pumping aqueous sulfuric acid solution and aqueous hydrogen peroxide solution into the slurry, and leaching most of ferric phosphate and Cu removal. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al) H 2SO4 =1:0.6, the amount of aqueous hydrogen peroxide solution used is as follows: total mole ratio of Al and Cu in the aluminum-containing ferric phosphate waste residue and mole ratio of hydrogen peroxide: and (Cu+Al) H 2O2 =1:2, fully mixing and stirring the sulfuric acid aqueous solution, the hydrogen peroxide aqueous solution and the slurry, and filtering to obtain the first inert slag and the first ferrophosphorus liquid with the impurity level meeting the requirement.
S2: the first inert slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first inert slag.
Pumping sulfuric acid aqueous solution with the concentration the same as that in the step S1 into slurry containing the first inert slag, and carrying out high-acid leaching on the first inert slag by adopting the sulfuric acid aqueous solution, wherein the dosage of the sulfuric acid aqueous solution is as follows: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al): h 2SO4 = 1:0.8, leaching temperature 80 ℃, leaching time 1H. Filtering to obtain second inert slag and aluminum-phosphorus-containing iron liquid.
S3: adding ammonia water into the aluminum-containing phosphorus iron liquid to adjust the pH value of the system to 2.0, generating precipitation, reacting for 2 hours at 50 ℃, and then filtering and washing to obtain first phosphorus iron slag and first aluminum liquid, wherein the first aluminum liquid can be used in the next batch S1 step pulping process, so as to realize wastewater recycling.
S4: the liquid-solid ratio of the first ferrophosphorus slag to water is 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first ferrophosphorus slag.
Adding ferric sulfate and sulfuric acid aqueous solution with the same concentration as that in the step S1 into the slurry containing the first ferrophosphorus slag to leach aluminum. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: the molar ratio of iron in the first phosphorus iron slag to sulfuric acid is as follows: fe: h 2SO4 =1:0.2, the amount of iron sulfate used satisfies: the mass of the ferric sulfate is 5% of the iron content in the first ferrophosphorus slag, the leaching temperature is 50 ℃, the leaching time is 2 hours, and the second ferrophosphorus slag and the second aluminum liquid are obtained through filtering and washing.
S5: the second ferrophosphorus slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the second ferrophosphorus slag.
And (3) adding the sulfuric acid aqueous solution with the concentration the same as that of the step S1 into the slurry containing the second ferrophosphorus slag, and carrying out full-component leaching on the second ferrophosphorus slag to obtain a second ferrophosphorus liquid with the impurity level meeting the requirement. Wherein, the mole ratio of iron in the second ferrophosphorus slag to sulfuric acid is as follows: fe: h 2SO4 = 1:1, leaching temperature 60 ℃, time 2H.
S6: adding a proper amount of sulfuric acid into the first ferrophosphorus liquid obtained in the step S1 to adjust the mole ratio of Fe/SO 4- to be 1.2: and 1, mixing the mixed solution with the second ferrophosphorus solution obtained in the step S5 to obtain mixed ferrophosphorus solution, adding ammonia water into the mixed ferrophosphorus solution to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 60 ℃, filtering to obtain precipitate and filtrate, adding phosphoric acid into the precipitate to convert, washing, drying, and sintering to obtain ferric phosphate.
Example 3
The embodiment provides a method for recovering ferric phosphate from waste residues containing aluminum and ferric phosphate, which comprises the following steps:
S1: the aluminum-containing ferric phosphate waste residue and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and stirred uniformly at the temperature of 60 ℃ to obtain the slurry containing the aluminum-containing ferric phosphate waste residues.
Pumping aqueous sulfuric acid solution and aqueous hydrogen peroxide solution into the slurry, and leaching most of ferric phosphate and Cu removal. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al) H 2SO4 =1:0.8, the amount of aqueous hydrogen peroxide solution used is as follows: total mole ratio of Al and Cu in the aluminum-containing ferric phosphate waste residue and mole ratio of hydrogen peroxide: and (Cu+Al) H 2O2 =1:2, fully mixing and stirring the sulfuric acid aqueous solution, the hydrogen peroxide aqueous solution and the slurry, and filtering to obtain the first inert slag and the first ferrophosphorus liquid with the impurity level meeting the requirement.
S2: the first inert slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first inert slag.
Pumping sulfuric acid aqueous solution with the concentration the same as that in the step S1 into slurry containing the first inert slag, and carrying out high-acid leaching on the first inert slag by adopting the sulfuric acid aqueous solution, wherein the dosage of the sulfuric acid aqueous solution is as follows: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al): h 2SO4 =1:1, leaching temperature 80 ℃, leaching time 1H. Filtering to obtain second inert slag and aluminum-phosphorus-containing iron liquid.
S3: adding ammonia water into the aluminum-containing phosphorus iron liquid to adjust the pH value of the system to 2.0, generating precipitation, reacting for 2 hours at 50 ℃, and then filtering and washing to obtain first phosphorus iron slag and first aluminum liquid, wherein the first aluminum liquid can be used in the next batch S1 step pulping process, so as to realize wastewater recycling.
S4: the liquid-solid ratio of the first ferrophosphorus slag to water is 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first ferrophosphorus slag.
Adding ferric sulfate and sulfuric acid aqueous solution with the same concentration as that in the step S1 into the slurry containing the first ferrophosphorus slag to leach aluminum. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: the molar ratio of iron in the first phosphorus iron slag to sulfuric acid is as follows: fe: h 2SO4 =1:0.2, the amount of iron sulfate used satisfies: the mass of the ferric sulfate is 5% of the iron content in the first ferrophosphorus slag, the leaching temperature is 50 ℃, the leaching time is 2 hours, and the second ferrophosphorus slag and the second aluminum liquid are obtained through filtering and washing.
S5: the second ferrophosphorus slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the second ferrophosphorus slag.
And (3) adding the sulfuric acid aqueous solution with the concentration the same as that of the step S1 into the slurry containing the second ferrophosphorus slag, and carrying out full-component leaching on the second ferrophosphorus slag to obtain a second ferrophosphorus liquid with the impurity level meeting the requirement. Wherein, the mole ratio of iron in the second ferrophosphorus slag to sulfuric acid is as follows: fe: h 2SO4 = 1:1, leaching temperature 60 ℃, time 2H.
S6: adding a proper amount of sulfuric acid into the first ferrophosphorus liquid obtained in the step S1 to adjust the mole ratio of Fe/SO 4- to be 1.2: and 1, mixing the mixed solution with the second ferrophosphorus solution obtained in the step S5 to obtain mixed ferrophosphorus solution, adding ammonia water into the mixed ferrophosphorus solution to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 60 ℃, filtering to obtain precipitate and filtrate, adding phosphoric acid into the precipitate to convert, washing, drying, and sintering to obtain ferric phosphate.
Comparative example 1
This comparative example provides a method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue, which is substantially the same as in example 1, with the main difference that: step S4 is not performed, and the specific steps are as follows:
s1: the aluminum-containing ferric phosphate waste residue and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and stirred uniformly at 50 ℃ to obtain the slurry containing the aluminum-containing ferric phosphate waste residues.
Pumping aqueous sulfuric acid solution and aqueous hydrogen peroxide solution into the slurry, and leaching most of ferric phosphate and Cu removal. Wherein, the dosage of the sulfuric acid aqueous solution satisfies: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al) H 2SO4 =1:0.6, the amount of aqueous hydrogen peroxide solution used is as follows: total mole ratio of Al and Cu in the aluminum-containing ferric phosphate waste residue and mole ratio of hydrogen peroxide: and (Cu+Al) H 2O2 =1:2, fully mixing and stirring the sulfuric acid aqueous solution, the hydrogen peroxide aqueous solution and the slurry, and filtering to obtain the first inert slag and the first ferrophosphorus liquid with the impurity level meeting the requirement.
S2: the first inert slag and water are mixed according to a liquid-solid ratio of 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first inert slag.
And (2) carrying out high-acid leaching on the first inert slag by adopting a sulfuric acid aqueous solution in the slurry containing the first inert slag, wherein the concentration of the sulfuric acid aqueous solution is the same as that of the step S1, and the dosage of the sulfuric acid aqueous solution is as follows: total mole ratio of iron and aluminum in the aluminum-containing iron phosphate waste residue and mole ratio of sulfuric acid: (fe+al): h 2SO4 = 1:1.2, leaching temperature 60 ℃, leaching time 1H. Filtering to obtain second inert slag and aluminum-phosphorus-containing iron liquid.
S3: adding ammonia water into the aluminum-containing phosphorus iron liquid to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 50 ℃, and then filtering and washing to obtain first phosphorus iron slag and first aluminum liquid, wherein the first aluminum liquid can be used in the next batch S1 step pulping process, so as to realize wastewater recycling.
S4: the liquid-solid ratio of the first ferrophosphorus slag to water is 3mL:1g of the mixture is fully mixed and uniformly stirred to obtain the slurry containing the first ferrophosphorus slag.
And (3) adding a sulfuric acid aqueous solution with the concentration the same as that of the step S1 into the slurry containing the first ferrophosphorus slag, and carrying out full-component leaching on the first ferrophosphorus slag to obtain a second ferrophosphorus liquid. Wherein, the mole ratio of iron in the first ferrophosphorus slag to sulfuric acid is as follows: fe: h 2SO4 = 1:1, leaching temperature 60 ℃, time 2H.
S5: adding a proper amount of sulfuric acid into the first ferrophosphorus liquid obtained in the step S1 to adjust the mole ratio of Fe/SO 4- to be 1.2: and1, mixing the mixed solution with the second ferrophosphorus solution obtained in the step S4 to obtain mixed ferrophosphorus solution, adding ammonia water into the mixed ferrophosphorus solution to adjust the pH value of the system to be 1.7, generating precipitation, reacting for 2 hours at 60 ℃, filtering to obtain precipitate and filtrate, adding phosphoric acid into the precipitate to convert, washing, drying, and sintering to obtain ferric phosphate.
The ICP tests the concentrations of the elements listed in table 2 in the mixed ferrophosphorus solutions of the examples and comparative examples, and the results are shown in table 2.
ICP test the contents of the elements listed in Table 2 in the precipitates of each of the examples and comparative examples, and the recovery rates of Fe and P in the precipitates and the impurity removal rates of Al and Cu were calculated in combination with the contents of the elements in the aluminum-containing iron phosphate slag listed in Table 1. The results are shown in Table 2.
TABLE 2
From table 2, it can be seen that the effect on the recovery rate of ferrophosphorus of the final ferric phosphate after pickling with the first acid solution and the second acid solution having different sulfuric acid contents was examined in examples 1,2 and 3, respectively, and it was found that both iron and phosphorus had recovery rates exceeding 97% by the combination of multiple pickling treatments under the first acid solution and the second acid solution of different sulfuric acids. Compared with example 1, comparative example 1 did not utilize the third acid solution and the ferric salt to treat the aluminum-containing ferrophosphorus solution, and the final ferric phosphate had higher aluminum content and lower impurity removal rate of aluminum. In conclusion, by the method for recycling the ferric phosphate, aluminum can be removed in high efficiency and depth, and the prepared precipitate can be used as a precursor of battery-grade ferric phosphate to further prepare the ferric phosphate meeting various indexes of the battery-grade ferric phosphate. Meanwhile, the loss rate of iron and phosphorus is low, the reaction process is mild, the product value is high, and the industrial mass production is easy.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (11)
1. A method for recovering iron phosphate from aluminum-containing iron phosphate waste residues, comprising the steps of:
leaching ferric phosphate in the aluminum-containing ferric phosphate waste residue by using a first acid solution to obtain a first inert slag and a first ferrophosphorus solution;
leaching aluminum and ferric phosphate in the first inert slag by using a second acid solution to obtain second inert slag and aluminum-containing phosphorus-containing iron solution, wherein the mole number of hydrogen ions in the second acid solution is larger than that in the first acid solution;
precipitating ferric phosphate in the aluminum-containing phosphorus iron liquid to obtain first phosphorus iron slag and first aluminum liquid;
treating the first ferrophosphorus slag through a third acid solution and ferric salt to obtain a second ferrophosphorus slag and a second aluminum solution;
leaching ferric phosphate in the second ferrophosphorus slag by using a fourth acid solution to obtain a second ferrophosphorus solution;
And precipitating and sintering the first phosphorus iron liquid and the second phosphorus iron liquid to obtain ferric phosphate.
2. The method of recovering iron phosphate from an aluminum-containing iron phosphate waste residue of claim 1, comprising at least one of the following features:
(1) The molar ratio of the total mole of iron and aluminum in the aluminum-containing iron phosphate waste residue to the mole of hydrogen ions in the first acid solution is as follows: (fe+al): h + = 1: (1-2);
(2) The molar ratio of the total mole of iron and aluminum in the aluminum-containing iron phosphate waste residue to the mole of hydrogen ions in the second acid solution is as follows: (fe+al): h + = 1: (1.6-4).
3. The method of recovering iron phosphate from aluminum-containing iron phosphate waste residue according to claim 1, wherein a system temperature for leaching aluminum and iron phosphate in the first inert residue with the second acid solution is greater than a system temperature for leaching iron phosphate in the aluminum-containing iron phosphate waste residue with the first acid solution.
4. The method of recovering iron phosphate from an aluminum-containing iron phosphate waste residue according to claim 1, wherein the molar ratio of iron in the first iron phosphate residue to hydrogen ions in the third acid solution is such that: fe: h + = 1: (0.2-1).
5. The method of recovering iron phosphate from an aluminum-containing iron phosphate waste residue of claim 1, comprising at least one of the following features:
(1) The ferric salt is selected from one or more of ferric sulfate, ferric phosphate and ferric oxide;
(2) The mass of the ferric salt is 1% -20% of the mass of iron in the first ferrophosphorus slag.
6. The method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue according to any one of claims 1 to 5, wherein the first acid solution is selected from an aqueous solution of an inorganic acid, and the second acid solution, the third acid solution and the fourth acid solution are the same in acid type as the first acid solution.
7. The method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue according to claim 6, wherein the mineral acid is selected from sulfuric acid or hydrochloric acid.
8. The method for recovering iron phosphate from aluminum-containing iron phosphate waste slag according to any one of claims 1 to 5 and 7, wherein the method for precipitating iron phosphate in the aluminum-containing iron phosphate liquid comprises the steps of: mixing the aluminum-containing phosphorus iron liquid with a first alkaline substance to generate a precipitate.
9. The method of recovering iron phosphate from an aluminum-containing iron phosphate waste residue of claim 8, comprising at least one of the following features:
(1) The first alkaline substance is selected from one or more of liquid alkali and ammonia water;
(2) The dosage of the first alkaline substance satisfies the following conditions: the pH value of the system is in the range of 1-4;
(3) The temperature for generating the sediment is 20-90 ℃;
(4) The time for generating the sediment is 1-5 h.
10. The method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue according to any one of claims 1 to 5, 7, 9, comprising at least one of the following features:
(1) The system temperature for leaching the ferric phosphate in the aluminum-containing ferric phosphate waste residue by using the first acid solution is 20-80 ℃;
(2) The leaching time of the ferric phosphate in the aluminum-containing ferric phosphate waste residue in the first acid liquid is 1-10 h;
(3) The system temperature for leaching the aluminum and the ferric phosphate in the first inert slag by using the second acid solution is 20-80 ℃;
(4) The leaching time of the aluminum and the ferric phosphate in the first inert slag in the second acid liquid is 1-10 h;
(5) The system temperature for treating the first ferrophosphorus slag through the third acid solution and the ferric salt is 20-80 ℃;
(6) The first ferrophosphorus slag is treated by the third acid liquor and the ferric salt for 1-10 hours;
(7) The system temperature for leaching the ferric phosphate in the second ferrophosphorus slag by using the fourth acid solution is 20-80 ℃;
(8) The leaching time of the ferric phosphate in the second ferrophosphorus slag in the fourth acid liquor is 1-10 h;
(9) The molar ratio of the iron in the second ferrophosphorus slag to the hydrogen ions in the fourth acid solution is as follows: fe: h + = 1: (1-2).
11. The method for recovering iron phosphate from an aluminum-containing iron phosphate waste residue according to any one of claims 1 to 5, 7, and 9, wherein cryolite is produced using the second aluminum liquid.
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