CN113562772A - Preparation method of ferrous sulfate tetrahydrate - Google Patents
Preparation method of ferrous sulfate tetrahydrate Download PDFInfo
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- CN113562772A CN113562772A CN202110889957.6A CN202110889957A CN113562772A CN 113562772 A CN113562772 A CN 113562772A CN 202110889957 A CN202110889957 A CN 202110889957A CN 113562772 A CN113562772 A CN 113562772A
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- ferrous sulfate
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- sulfate tetrahydrate
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- 229910000359 iron(II) sulfate Inorganic materials 0.000 title claims abstract description 102
- 239000011790 ferrous sulphate Substances 0.000 title claims abstract description 91
- 235000003891 ferrous sulphate Nutrition 0.000 title claims abstract description 91
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 title claims abstract 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 69
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000013078 crystal Substances 0.000 claims abstract description 52
- 230000009466 transformation Effects 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 40
- 239000012452 mother liquor Substances 0.000 claims abstract description 39
- 229910052742 iron Inorganic materials 0.000 claims abstract description 37
- 238000000926 separation method Methods 0.000 claims abstract description 23
- 239000007791 liquid phase Substances 0.000 claims abstract description 18
- 239000007788 liquid Substances 0.000 claims abstract description 13
- 239000011259 mixed solution Substances 0.000 claims abstract description 9
- 239000002253 acid Substances 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 3
- 239000004568 cement Substances 0.000 abstract description 9
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052804 chromium Inorganic materials 0.000 abstract description 6
- 239000011651 chromium Substances 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 5
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 92
- 239000000243 solution Substances 0.000 description 26
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 20
- 230000008569 process Effects 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- -1 iron ions Chemical class 0.000 description 10
- 239000002699 waste material Substances 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000003825 pressing Methods 0.000 description 8
- XBDUTCVQJHJTQZ-UHFFFAOYSA-L iron(2+) sulfate monohydrate Chemical compound O.[Fe+2].[O-]S([O-])(=O)=O XBDUTCVQJHJTQZ-UHFFFAOYSA-L 0.000 description 7
- YDZQQRWRVYGNER-UHFFFAOYSA-N iron;titanium;trihydrate Chemical compound O.O.O.[Ti].[Fe] YDZQQRWRVYGNER-UHFFFAOYSA-N 0.000 description 7
- 238000002386 leaching Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 235000010215 titanium dioxide Nutrition 0.000 description 6
- 230000001603 reducing effect Effects 0.000 description 5
- 239000012047 saturated solution Substances 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 230000003301 hydrolyzing effect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000007790 solid phase Substances 0.000 description 4
- 239000004408 titanium dioxide Substances 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005660 chlorination reaction Methods 0.000 description 2
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/14—Sulfates
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention relates to the technical field of preparation of ferrous sulfate tetrahydrate, and particularly relates to a preparation method of ferrous sulfate tetrahydrate. The preparation method of the ferrous sulfate tetrahydrate comprises the following steps: concentrating and crystallizing the artificial rutile mother liquor, and then carrying out solid-liquid separation to obtain ferrous sulfate tetrahydrate and a liquid phase system containing the ferrous sulfate; the temperature of the concentration treatment is 60-80 ℃; concentrating until the mass percentage of iron in the mixed solution is 14-18%; the temperature of the crystal transformation treatment is 60-80 ℃. The method greatly reduces the treatment cost of the artificial rutile mother liquor, scientifically and effectively utilizes the artificial rutile mother liquor, and simultaneously produces the ferrous sulfate tetrahydrate with high added value, and the method is used for environmental protection, cement chromium removal and the like.
Description
Technical Field
The invention relates to the technical field of preparation of ferrous sulfate tetrahydrate, and particularly relates to a preparation method of ferrous sulfate tetrahydrate.
Background
The chlorination-process titanium dioxide production process is short, the production capacity is easy to expand, the continuous automation degree is high, the product quality control is more stable than that of a sulfuric acid process, the three wastes are less, the environmental protection problem is less, and the chlorination-process titanium dioxide production process becomes a mainstream titanium dioxide production technology. With the gradual expansion of the capacity of the chlorination process, the demand of raw materials is gradually increased. At present, a plurality of methods for preparing the artificial rutile exist, but the process is relatively complex, and the main methods for realizing industrialization at present are a reduced rust method and an acid leaching method. The hydrochloric acid leaching method can obtain high-grade artificial rutile, but the product granularity is too fine, the side flow is long, the production cost is high, and equipment corrosion in the production process is serious, so that the industrial application of the process is limited. With the continuous development of the technology for preparing the artificial rutile, the method for preparing the artificial rutile by leaching and reducing ilmenite by adopting titanium dioxide waste acid has the advantages of low cost, good quality, high yield and low equipment requirement, but has the problem that the artificial rutile mother liquor separated after leaching is difficult to treat, and the development of the method is directly restricted if the obtained artificial rutile mother liquor cannot be reasonably treated or utilized.
Leaching titanium white waste acid to reduce ilmenite to prepare artificial rutile, separating to obtain an artificial rutile mother liquor ferrous sulfate solution which is a saturated solution, directly cooling and crystallizing in vacuum, wherein the crystallization rate is only about 30%, and the residual solution needs further treatment; the solution is directly neutralized, and because the solution also contains about 3 percent of sulfuric acid and a large amount of iron ions, a large amount of stone powder or carbide mud is consumed, a large amount of yellow mud is generated, the yellow mud is difficult to utilize, and the resource waste is caused.
The ferrous sulfate tetrahydrate is different from ferrous sulfate monohydrate (yellow ferrous) and ferrous sulfate heptahydrate (green vanadium), the appearance of the product is light green or light yellow green crystalline solid, a certain amount of the ferrous sulfate tetrahydrate can be added to adjust the pH value of alkaline water, the ferrous sulfate tetrahydrate is organically combined with suspended matters in water and accelerates the precipitation, the ferrous sulfate tetrahydrate is mainly applied to water quality purification and industrial wastewater treatment, and meanwhile, the ferrous sulfate tetrahydrate has a sterilization effect; it can also be used as the reducer of hexavalent chromium in cement. While copperas and yellow ferrous iron can also be used as a hexavalent chromium reducing agent in cement production. Both substances have disadvantages. Copperas have the disadvantage that the material is difficult to store and handle, it easily agglomerates during storage and therefore problems are encountered when the storage tank is blanked, and the poor flow characteristics make the addition process more difficult. Furthermore, the copperas may precipitate out adhering water which then collects at the bottom of the copperas storage tank and causes problems. In this wet state, the copperas are easily oxidized by oxygen in the air, and thus the reducing effect is greatly reduced. The oxidation of copperas occurs more readily at higher temperatures. The solubility of copperas is also strongly temperature dependent. From about 40 ℃, copperas dissolves in its own crystal water and is then easily oxidized by oxygen in the air, thereby losing its role as a chromate reducing agent.
On the other hand, ferrous sulfate monohydrate has the disadvantage of having a large amount of adherent sulfuric acid, typically at 20% or more. Whereas ordinary portland cement is alkaline, the sulfuric acid reacts with the cement clinker and thus produces large lumps. Thus, the ferrous yellow iron must be neutralized with mineral additives such as lime or treated with metallic iron and alkaline iron compounds to form an additional ferrous sulfate mixture. This also applies to the use of mixtures of copperas and ferrous yellow. To improve the flow properties of the neutralized ferrous sulfate, it may be granulated. However, a disadvantage of granulation is that if the granules become too hard, the ferrous sulphate loses its reducing power. Since ferrous sulfate monohydrate (yellow ferrous) is less soluble in water than ferrous sulfate heptahydrate (copperas), the solubility can be increased by adding water to the yellow ferrous sulfate. But even so, the sulfuric acid attached to the ferrous sulfate monohydrate (ferrous yellow) must be neutralized.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a preparation method of ferrous sulfate tetrahydrate, which comprises the steps of concentrating and crystallizing artificial rutile mother liquor, and obtaining the ferrous sulfate tetrahydrate by controlling the concentration temperature, the content of iron ions in the solution and the crystallization temperature; the method greatly reduces the treatment cost of the artificial rutile mother liquor, scientifically and effectively utilizes the artificial rutile mother liquor, and simultaneously produces the ferrous sulfate tetrahydrate with high added value, and the method is used for environmental protection, cement chromium removal and the like.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
a preparation method of ferrous sulfate tetrahydrate comprises the following steps:
concentrating and crystallizing the artificial rutile mother liquor, and then carrying out solid-liquid separation to obtain ferrous sulfate tetrahydrate and a liquid phase system containing the ferrous sulfate;
the temperature of the concentration treatment is 60-80 ℃; concentrating until the mass percentage of iron in the mixed solution is 14-18%;
the temperature of the crystal transformation treatment is 60-80 ℃.
Preferably, the synthetic rutile mother liquor is pretreated, the pretreatment comprising the steps of:
mixing an iron simple substance and/or a substance containing the iron simple substance with the artificial rutile mother liquor, reacting until the mass percentage of acid in a mixed system after reaction is less than 0.1%, performing solid-liquid separation, collecting liquid, and performing the concentration treatment;
preferably, the mass percentage of the acid in the mixed system after the reaction is 0.03-0.95%.
Preferably, the reaction temperature is 15-90 ℃;
preferably, the reaction temperature is 45-70 ℃.
Preferably, the time of the crystal transformation treatment is 2-4 h;
preferably, the time of the crystal transformation treatment is 2.5-3.5 h.
Preferably, stirring is carried out during the crystal transformation treatment;
preferably, the rotating speed of the stirring is 100-300 rpm.
Preferably, the temperature of the concentration treatment is 70-80 ℃;
preferably, the concentration treatment is carried out until the mass percentage of iron in the mixed solution is 15.5-17%.
Preferably, the temperature of the crystal transformation treatment is 70-75 ℃.
Preferably, the liquid phase system containing the ferrous sulfate is subjected to heat treatment and then liquid-solid separation, and the liquid phase after the liquid-solid separation is subjected to concentration treatment and crystal transformation treatment.
Preferably, the temperature of the heat treatment is 90-95 ℃.
Preferably, the ferrous sulfate solution obtained after the separation is subjected to concentration treatment and crystal transformation treatment.
Preferably, the apparatus for concentration treatment includes at least one of a double-effect evaporator, a multiple-effect evaporator and an MVR evaporator.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention provides a brand new mother liquor recycling mode for the ferrous sulfate solution separated after the artificial rutile is prepared by leaching and reducing the ilmenite through the waste sulfuric acid, has simple process and relatively low operation cost, obtains the ferrous sulfate tetrahydrate with high added value, effectively and reasonably utilizes the artificial rutile mother liquor, can promote the development of the process technology for preparing the artificial rutile by leaching and reducing the ilmenite through the titanium white waste acid, and provides environmental protection guarantee for the process expanded production and providing high-quality artificial rutile raw materials for the chlorination process.
(2) The invention furthest promotes the utilization value of the artificial rutile mother liquor, obtains the ferrous sulfate tetrahydrate, effectively avoids the secondary pollution caused by solid matter accumulation brought by the traditional treatment method or the high treatment cost of the artificial rutile mother liquor concentration crystallization method, realizes the diversified utilization, comprehensive utilization and cyclic utilization of the waste, has good economic benefit, and changes the traditional waste extensive treatment mode.
(3) The ferrous sulfate tetrahydrate prepared by the invention is granular, is easy to disperse and does not agglomerate, and has better development prospect compared with ferrous heptahydrate when being used as a cement chromium removal agent.
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 process flow diagram for preparing ferrous sulfate tetrahydrate according to the present invention;
FIG. 2 is a diagram showing the appearance of ferrous sulfate prepared under different conditions.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
According to one aspect of the invention, the invention relates to a preparation method of ferrous sulfate tetrahydrate, which comprises the following steps:
concentrating and crystallizing the artificial rutile mother liquor, and then carrying out solid-liquid separation to obtain ferrous sulfate tetrahydrate and a liquid phase system containing the ferrous sulfate;
the temperature of the concentration treatment is 60-80 ℃; concentrating until the mass percentage of iron in the mixed solution is 14-18%;
the temperature of the crystal transformation treatment is 60-80 ℃.
The invention avoids the conditions of resource waste, high treatment cost and secondary pollution caused by direct crystallization and neutralization, and prepares the ferrous sulfate tetrahydrate with higher additional value while treating the artificial rutile mother liquor through simple concentration and low-temperature crystal transformation according to the defects of copperas, ferrous sulfate and a mixture of copperas and ferrous sulfate described by a reducing agent for a cement chromium removal agent, and is used for environmental protection, cement chromium removal and the like.
The artificial rutile mother liquor can also be replaced by other waste liquor containing ferrous sulfate.
The temperature of the concentration treatment is controlled to be 60-80 ℃, and the obtained ferrous sulfate tetrahydrate has high purity and high quality. If the temperature of the concentration treatment is too high, ferrous sulfate monohydrate is produced, and if the temperature of the concentration treatment is too low, the concentration efficiency is low, and if the temperature is too low, ferrous sulfate heptahydrate is produced.
In one embodiment, the concentration treatment temperature is 60-80 ℃, and 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃, 77 ℃, 78 ℃, 79 ℃ or 80 ℃ can be selected.
The invention comprehensively considers the yield and the purity, controls the mass percentage of the iron in the mixed solution after the concentration treatment to be 14-18 percent, and can obtain the ferrous sulfate tetrahydrate with high yield and high purity in the range. If the mass percentage of iron in the mixed liquid after the concentration treatment is less than 14%, the yield of the ferrous sulfate tetrahydrate is low. If the mass percentage of iron in the mixed liquid after the concentration treatment is more than 18%, ferrous sulfate monohydrate can be generated, and the purity of the obtained ferrous sulfate tetrahydrate is reduced.
In one embodiment, the concentration is performed until the mass percentage of iron in the mixed solution is 14% to 18%, and may be selected from 14%, 14.5%, 15%, 16%, 16.5%, 17%, 17.5% and 18%.
The temperature of the crystal transformation process is controlled to be 60-80 ℃, and if the temperature is too high, ferrous sulfate monohydrate is generated; if the temperature is too low, ferrous sulfate heptahydrate is produced.
In one embodiment, the temperature of the transcrystallization treatment is 60 to 80 ℃, and 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃, 77 ℃, 78 ℃, 79 ℃ or 80 ℃ can be selected.
Preferably, the synthetic rutile mother liquor is pretreated, the pretreatment comprising the steps of:
mixing the iron simple substance and/or the substance containing the iron simple substance with the artificial rutile mother liquor, reacting until the mass percentage of acid in the mixed system after the reaction is less than 0.1%, performing solid-liquid separation, collecting the liquid, and performing the concentration treatment.
The substance containing the iron simple substance comprises iron powder, reduced ilmenite and other substances containing metallic iron.
The iron simple substance and/or the substance containing the iron simple substance are/is mixed with the artificial rutile mother liquor for reaction, so that the mass percentage content of acid in the artificial rutile mother liquor is reduced (less than 0.1 percent), the utilization value of the obtained ferrous sulfate tetrahydrate can be improved, and the ferrous sulfate tetrahydrate can be better applied to chromium removal of cement.
In one embodiment, the acid content in the mixed system after the reaction is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.095% by mass.
Preferably, the mass percentage of the acid in the mixed system after the reaction is 0.03-0.95%.
Preferably, the reaction temperature is 15-90 ℃.
In one embodiment, the reaction temperature is 15-90 ℃, and can be selected from 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃ or 90 ℃.
Preferably, the reaction temperature is 45-70 ℃.
Preferably, the time of the crystal transformation treatment is 2-4 h.
In an embodiment, the time of the crystal transformation treatment is 2 to 4 hours, and 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, 3 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours or 4 hours can be selected.
Preferably, the time of the crystal transformation treatment is 2.5-3.5 h.
Preferably, stirring is performed during the crystal transformation.
Preferably, the rotating speed of the stirring is 100-300 rpm.
The invention can stir at the rotating speed of 100-300 rpm, can accelerate crystal transformation and can obtain high-quality ferrous sulfate tetrahydrate.
In one embodiment, the rotation speed of the stirring is 100-300 rpm, and may be selected from 110rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, 190rpm, 200rpm, 210rpm, 220rpm, 230rpm, 240rpm, 250rpm, 260rpm, 270rpm, 280rpm, 290rpm, or 300 rpm.
Preferably, the temperature of the concentration treatment is 70-80 ℃.
Preferably, the concentration treatment is carried out until the mass percentage of iron in the mixed solution is 15.5-17%.
Preferably, the temperature of the crystal transformation treatment is 70-75 ℃.
Preferably, the liquid phase system containing the ferrous sulfate is subjected to heat treatment and then liquid-solid separation, and the liquid phase after the liquid-solid separation is subjected to concentration treatment and crystal transformation treatment.
The metatitanic acid is obtained after the heat treatment of the invention. And concentrating and crystallizing the separated mixed liquid again.
Preferably, the temperature of the heat treatment is 90-95 ℃.
In one embodiment, the temperature of the heat treatment is 90-95 ℃, and may be selected from 90 ℃, 91 ℃, 92 ℃, 93 ℃, 94 ℃ or 95 ℃.
Preferably, the ferrous sulfate solution obtained after the separation is subjected to concentration treatment and crystal transformation treatment.
The mixture after the crystal transformation treatment is ferrous sulfate tetrahydrate and ferrous sulfate solution, and the ferrous sulfate solution is concentrated again.
Preferably, the apparatus for concentration treatment includes at least one of a double-effect evaporator, a multiple-effect evaporator and an MVR evaporator.
The concentration equipment adopted in the concentration treatment process can be a double-effect evaporator, a multi-effect evaporator or an MVR evaporator.
The present invention will be further explained with reference to specific examples and comparative examples.
The process flow diagram of the ferrous sulfate tetrahydrate prepared in the embodiment of the invention is shown in figure 1.
The indices of the synthetic rutile mother liquor used in the examples of the present invention and the comparative examples are shown in Table 1 below.
TABLE 1 synthetic rutile mother liquor index
Example 1
A preparation method of ferrous sulfate tetrahydrate comprises the following steps:
adding iron powder into the artificial rutile mother liquor at 25 ℃, reacting until the sulfuric acid content in the artificial rutile mother liquor is reduced to 0.1%, settling, and filtering to obtain a low-acidity ferrous sulfate saturated solution; concentrating at 60 ℃ until the iron ion content in the solution is 14%, carrying out crystal transformation, keeping the crystal transformation temperature at 60 ℃, stirring at 150rpm, carrying out centrifugal separation after crystal transformation for 3 hours to obtain ferrous sulfate tetrahydrate with the iron content of 24.65%, wherein other indexes and the primary crystal transformation yield are shown in the following table 2; and heating and hydrolyzing the liquid phase system after centrifugal separation to obtain solid phase metatitanic acid, wherein the heating temperature is 90 ℃, then performing filter pressing, and returning the liquid phase obtained after filter pressing to perform concentration treatment.
Example 2
A preparation method of ferrous sulfate tetrahydrate comprises the following steps:
at 50 ℃, adding reduced ilmenite into the artificial rutile mother liquor, reacting until the sulfuric acid content in the artificial rutile mother liquor is reduced to 0.08%, settling, and filtering to obtain a low-acidity ferrous sulfate saturated solution; concentrating the saturated ferrous sulfate solution at 80 ℃ until the content of iron ions in the solution is 18%, carrying out crystal transformation, keeping the crystal transformation temperature at 70 ℃, stirring at 200rpm, carrying out centrifugal separation after crystal transformation for 4 hours to obtain ferrous sulfate tetrahydrate with the iron content of 25.74%, wherein other indexes and the primary crystal transformation yield are shown in the following table 2; and heating and hydrolyzing the liquid phase system after centrifugal separation to obtain solid phase metatitanic acid, wherein the heating temperature is 93 ℃, then performing filter pressing, and returning the liquid phase obtained after filter pressing to perform concentration treatment.
Example 3
A preparation method of ferrous sulfate tetrahydrate comprises the following steps:
adding iron powder into the artificial rutile mother liquor at the temperature of 80 ℃, reacting until the content of sulfuric acid in the artificial rutile mother liquor is reduced to 0.05%, settling, and filtering to obtain a low-acidity ferrous sulfate saturated solution; concentrating the saturated ferrous sulfate solution at 75 ℃ until the content of iron ions in the solution is 16%, carrying out crystal transformation, keeping the crystal transformation temperature at 70 ℃, stirring at 300rpm, carrying out centrifugal separation after crystal transformation for 2 hours to obtain ferrous sulfate tetrahydrate with the iron content of 24.87%, wherein other indexes and the primary crystal transformation yield are shown in the following table 2; and heating and hydrolyzing the liquid phase system after centrifugal separation to obtain solid phase metatitanic acid, wherein the heating temperature is 95 ℃, then performing filter pressing, and returning the liquid phase obtained after filter pressing to perform concentration treatment.
Example 4
A preparation method of ferrous sulfate tetrahydrate comprises the following steps:
at 55 ℃, adding reduced ilmenite into the artificial rutile mother liquor, reacting until the sulfuric acid content in the artificial rutile mother liquor is reduced to 0.075%, settling, and filtering to obtain a low-acidity ferrous sulfate saturated solution; concentrating the saturated ferrous sulfate solution at 70 ℃ until the content of iron ions in the solution is 17%, carrying out crystal transformation, keeping the crystal transformation temperature at 65 ℃, stirring at 250rpm, carrying out crystal transformation for 2.5h, and then carrying out centrifugal separation to obtain ferrous sulfate tetrahydrate with the iron content of 25.45%, wherein other indexes and the primary crystal transformation yield are shown in the following table 2; and heating and hydrolyzing the liquid phase system after centrifugal separation to obtain solid phase metatitanic acid, wherein the heating temperature is 93 ℃, then performing filter pressing, and returning the liquid phase obtained after filter pressing to perform concentration treatment.
Comparative example 1
The same conditions as in example 4 were used except that the saturated ferrous sulfate solution was concentrated at 90 ℃ to obtain ferrous sulfate having the following indicators and yields as shown in Table 3 below.
Comparative example 2
The same conditions as in example 4 were used except that the solution was subjected to crystal transformation after the iron ion content was 12%, and the obtained ferrous sulfate index and yield were as shown in table 3 below.
Comparative example 3
Except that the iron ion content in the solution was 20%, the crystal transformation was performed under the same conditions as in example 4, and the obtained ferrous sulfate index and yield were as shown in table 3 below.
Comparative example 4
The same procedure as in example 4 was repeated except that the temperature of the crystal transition was kept at 40 ℃ to obtain ferrous sulfate having the following indicators and yields as shown in Table 3 below.
Comparative example 5
The same procedure as in example 4 was repeated except that the temperature of the crystal transition was kept at 90 ℃ to obtain ferrous sulfate having the following indicators and yields as shown in Table 3 below.
Examples of the experiments
The indexes of the ferrous sulfate obtained in the example of the present invention are shown in table 2 below; the indexes of ferrous sulfate obtained in the comparative example of the present invention are shown in table 3 below.
Indexes of ferrous sulfate obtained in example of Table 2
TABLE 3 index of ferrous sulfate obtained in comparative example
As can be seen from Table 2, the process of the present invention effectively utilizes the synthetic rutile mother liquor to produce ferrous sulfate tetrahydrate with high added value. Further, as shown in FIG. 2 (a), the morphology of the ferrous sulfate tetrahydrate obtained in example 4 is shown, and it is understood that the ferrous sulfate tetrahydrate obtained by the method of the present invention is granular, easily dispersible and free from aggregation; FIG. 2 (b) shows the morphology of the product obtained in comparative example 4, with severe agglomeration; FIG. 2 (c) shows the morphology of the product obtained in comparative example 5, in which agglomeration occurred.
As can be seen from the comparative example, the concentration of iron in the synthetic rutile mother liquor is low after concentration, and the yield of primary crystal transformation is low; the concentration temperature is high, the crystal transformation temperature is high, the iron concentration in the concentrated artificial rutile mother liquor is high, and ferrous monohydrate is generated in the transformed ferrous sulfate, so that the crystals are yellow, the granularity is fine, and hardening is easy to occur; the crystal transformation temperature is low, and the crystal is mainly precipitated in the form of ferrous sulfate heptahydrate.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A preparation method of ferrous sulfate tetrahydrate is characterized by comprising the following steps:
concentrating and crystallizing the artificial rutile mother liquor, and then carrying out solid-liquid separation to obtain ferrous sulfate tetrahydrate and a liquid phase system containing the ferrous sulfate;
the temperature of the concentration treatment is 60-80 ℃; concentrating until the mass percentage of iron in the mixed solution is 14-18%;
the temperature of the crystal transformation treatment is 60-80 ℃.
2. The method of claim 1, wherein the synthetic rutile mother liquor is pretreated, the pretreatment comprising the steps of:
mixing an iron simple substance and/or a substance containing the iron simple substance with the artificial rutile mother liquor, reacting until the mass percentage of acid in a mixed system after reaction is less than 0.1%, performing solid-liquid separation, collecting liquid, and performing the concentration treatment;
preferably, the mass percentage of the acid in the mixed system after the reaction is 0.03-0.95%.
3. The method for preparing ferrous sulfate tetrahydrate according to claim 2, wherein the reaction temperature is 15-90 ℃;
preferably, the reaction temperature is 45-70 ℃.
4. The method for preparing ferrous sulfate tetrahydrate according to claim 1, wherein the time of crystal transformation is 2-4 h;
preferably, the time of the crystal transformation treatment is 2.5-3.5 h.
5. The method for preparing ferrous sulfate tetrahydrate according to claim 1, wherein stirring is carried out during the crystal transformation treatment;
preferably, the rotating speed of the stirring is 100-300 rpm.
6. The method for preparing ferrous sulfate tetrahydrate according to claim 1, wherein the concentration treatment temperature is 70-80 ℃;
preferably, the concentration treatment is carried out until the mass percentage of iron in the mixed solution is 15.5-17%.
7. The method for preparing ferrous sulfate tetrahydrate according to claim 1, wherein the temperature of the crystal transformation treatment is 70-75 ℃.
8. The method for preparing ferrous sulfate tetrahydrate according to any one of claims 1 to 7, wherein the liquid phase system containing ferrous sulfate is subjected to heat treatment and then liquid-solid separation, and the liquid phase after the liquid-solid separation is subjected to concentration treatment and crystal transformation treatment.
9. The method for preparing ferrous sulfate tetrahydrate according to claim 8, wherein the temperature of the heat treatment is 90-95 ℃.
10. The method for preparing ferrous sulfate tetrahydrate according to any one of claims 1 to 7, wherein the equipment for concentration treatment comprises at least one of a double-effect evaporator, a multiple-effect evaporator and an MVR evaporator.
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