CN101462944A - Iron oxalate crystal and preparation thereof - Google Patents

Abstract

The invention relates to a preparation method of monoclinic ferrous oxalate crystal (FeC2O4.2H2O) with particlesize less than 3mum and the monoclinic ferrous oxalate crystal with particlesize less than 3mum obtained by adopting the method. A solid-liquid two-phase method is adopted and the reaction is controlled by controlling the feeding speed of solid oxalate and the temperature and concentration of bivalence ferrous salt solution, thus achieving the purpose of generating the ferrous oxalate crystals with specific crystal formation and particlesize. The method is characterized in that: the solid oxalate is added into the bivalence ferrous salt water solution with concentration of Fe<2+> being 0.5-1.7mol/l at the temperature of 40-80 DEG C at the feeding speed of more than 500g/min for reaction by temperature preservation. The method has simple process and high yield. The ferrous oxalate crystal with particlesize less than 3mum is obtained by the method, and the crystal formation is the monoclinic crystal.

Description

A kind of Ferrox crystal and preparation method thereof

Technical field

The present invention relates to a kind of Ferrox crystal and manufacture method thereof, especially a kind of granularity is less than the Ferrox crystal and the manufacture method thereof of the monoclinic form of 3 μ m.

Background technology

Ferrox crystal (FeC ₂O ₄2H ₂O) be one of essential substance of making the anode active material of lithium ion battery LiFePO 4.

Present known Ferrox crystalline production method is with divalent iron salt solution and oxalic acid or oxalate solution mixing, control the growth of Ferrox crystalline by strict control process parameters, to reach the Ferrox crystalline purpose of producing specified particle size or crystal habit.But these processing parameters are protected with the form of secret of the trade by producer, and the public can't learn generally speaking.In addition, CN 1948259A discloses the production method of the special-purpose Ferrox of a kind of phosphoric acid (Asia) iron lithium, this method is a raw material with ferrous sulfate and oxalic acid, reaching prepared sizes by step such as Ferrox is carried out pre-treatment, the different temperature of reaction of control and different ammonium acid are compared is 10～20 μ m, and crystal habit is respectively tiltedly or the tiltedly Ferrox crystalline purposes of side of monocline, three.But though can access monocline Ferrox crystal with this method, the Ferrox crystal size is bigger, is 10～20 μ m.

Summary of the invention

The purpose of this invention is to provide a kind of Ferrox crystalline production method, this method has overcome the problem of ordinary method complex process, and adopts this method can obtain the monocline Ferrox crystal of granularity less than 3 μ m.This method comprises the steps:

A. oxalate solid and Fe ²⁺Concentration is that the aqueous solution of 0.5～1.7mol/l is at 40～80 ℃ of following stirring reactions;

B. stop insulation, still aging;

C. isolate supernatant liquid, reclaim precipitation;

D. the precipitation that obtains with deionized water wash step C is to remove foreign ion;

E. dry;

The described method of steps A according to the present invention, preferred 45～75 ℃ of following Fe ²⁺Concentration is the aqueous solution of 0.5～1.7mol/l.When temperature is higher than 80 ℃, Fe ²⁺Be oxidized to Fe easily ³⁺So solution temperature is no more than 80 ℃.The mol ratio of oxalate and divalent iron salt consumption has no particular limits, wherein a kind of excessive getting final product.The example of divalent iron salt comprises ferrous sulfate (FeSO ₄), iron protochloride (FeCl ₂), ferrous bromide (FeBr ₂), the example of oxalate comprises ammonium oxalate { (NH ₄) ₂C ₂O ₄, sodium oxalate (Na ₂C ₂O ₄), potassium oxalate (K ₂C ₂O ₄).

The oxalate solid is joined in the divalent iron salt aqueous solution, and mechanical stirring 20～120 minutes is dissolved fully up to the oxalate solid that adds.The feed rate that the oxalate solid joins in the divalent iron salt solution has no particular limits, and is preferably greater than 500g/min, and stir speed (S.S.) is decided on strength of solution, preferred 100～1000 rev/mins.

Stop insulation, after still aging 20～120 minutes, isolate supernatant liquid, reclaim precipitation, and use deionized water wash, up to removing foreign ion.Described foreign ion comprises Fe ³⁺, NH ₄ ⁺, K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure foreign ion Fe with the ICP optical spectroscopy ³⁺, NH ₄ ⁺, K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.

Since when air drying Ferrox crystal, the disengaging that causes ferrous oxidation or crystal water easily above 90 ℃, and so drying temperature is selected 50～90 ℃, preferred 70～80 ℃, be 10～18 hours time of drying.If selection vacuum-drying, then drying temperature can be 80～110 ℃, and be 2～8 hours time of drying.

By calculating, Ferrox crystalline productive rate is greater than 98%.

In addition, also may contain ferrous hydroxide { Fe (OH) in the precipitation that step D obtains ₂And ironic hydroxide { Fe (OH) ₃.For these two kinds of insolubless, can remove with the dilute hydrochloric acid of PH2～5 or dilute sulphuric acid or oxalic acid solution washing.And then with deionized water wash Ferrox crystal, up to removing Cl-or SO ₄ ^2-Or C ₂O ₄ ^2-Till.Use titration measuring Cl ^-Or SO ₄ ^2-Or C ₂O ₄ ^2-Mole % 0.5% when following, can think foreign ion Cl-or SO ₄ ^2-Or C ₂O ₄ ^2-Be removed.

Analyze dried Ferrox crystal with X-ray diffraction method (XRD), its XRD figure and JCPDS figure number are that the standard monocline Ferrox crystal XRD figure of 23-0293 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a monoclinic crystal.

Analyze dried Ferrox crystal with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL), measure granularity between 2.04 μ m～2.75 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal.

The described method of steps A according to the present invention, preferred 45～75 ℃ of following Fe ²⁺Concentration is the aqueous solution of 0.5～1.7mol/l.When temperature is higher than 80 ℃, Fe ²⁺Be oxidized to Fe easily ³⁺So solution temperature is no more than 80 ℃.The mol ratio of oxalate and divalent iron salt consumption has no particular limits, wherein a kind of excessive getting final product.The example of divalent iron salt comprises ferrous sulfate (FeSO ₄), iron protochloride (FeCl ₂), ferrous bromide (FeBr ₂), the example of oxalate comprises ammonium oxalate { (NH ₄) ₂C ₂O ₄, sodium oxalate (Na ₂C ₂O ₄), potassium oxalate (K ₂C ₂O ₄).

The oxalate solid is joined in the divalent iron salt aqueous solution, and mechanical stirring 20～120 minutes is dissolved fully up to the oxalate solid that adds.The feed rate that the oxalate solid joins in the divalent iron salt solution has no particular limits, and is preferably greater than 500g/min, and stir speed (S.S.) is decided on strength of solution, preferred 100～1000 rev/mins.

Stop insulation, after still aging 20～120 minutes, isolate supernatant liquid, reclaim precipitation, and use deionized water wash, up to removing foreign ion.Described foreign ion comprises Fe ³⁺, NH ₄ ⁺, K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure foreign ion Fe with the ICP optical spectroscopy ³⁺, NH ₄ ⁺, K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.

Since when air drying Ferrox crystal, the disengaging that causes ferrous oxidation or crystal water easily above 90 ℃, and so drying temperature is selected 50～90 ℃, preferred 70～80 ℃, be 10～18 hours time of drying.If selection vacuum-drying, then drying temperature can be 80～110 ℃, and be 2～8 hours time of drying.

By calculating, Ferrox crystalline productive rate is greater than 98%.

In addition, also may contain ferrous hydroxide { Fe (OH) in the precipitation that step D obtains ₂And ironic hydroxide { Fe (OH) ₃.For these two kinds of insolubless, can remove with the dilute hydrochloric acid of PH2～5 or dilute sulphuric acid or oxalic acid solution washing.And then with deionized water wash Ferrox crystal, up to removing Cl-or SO ₄ ^2-Or C ₂O ₄ ^2-Till.With titration measuring Cl-or SO ₄ ^2-Or C ₂O ₄ ^2-Mole % 0.5% when following, can think foreign ion Cl ^-Or SO ₄ ^2-Or C ₂O ₄ ^2-Be removed.

Analyze dried Ferrox crystal with X-ray diffraction method (XRD), its XRD figure and JCPDS figure number are that the standard monocline Ferrox crystal XRD figure of 23-0293 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a monoclinic crystal.

Analyze dried Ferrox crystal with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL), measure granularity between 2.04 μ m～2.75 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, and Japanese JEOL makes) observation Ferrox crystal, prove that further its granularity is less than 3 μ m.

Description of drawings

Fig. 1: according to the Ferrox crystalline stereoscan photograph of the method for embodiment 1 preparation.

Fig. 2: according to the Ferrox crystalline stereoscan photograph of the method for Comparative Examples 1 preparation.

Fig. 3: according to the Ferrox crystalline XRD figure and the JCPDS of the method for embodiment 1 preparation

Figure number is the contrast of the standard monocline Ferrox crystal XRD figure of 23-0293.The below is a JCPDS 23-0293 standard monocline Ferrox crystal XRD figure.

Fig. 4: according to the Ferrox crystalline XRD figure and the JCPDS of the method for Comparative Examples 1 preparation

Figure number is that the standard of 22-0635 is mixed the contrast of the Ferrox crystal XRD figure of crystal formation.Down

The Ferrox crystal XRD figure of crystal formation is mixed by the side for the JCPDS22-0635 standard.

Embodiment

Divalent iron salt is dissolved in the isothermal reactor with deionization, is made into certain density solution under the certain temperature, then the oxalate solid is directly joined in this divalent iron salt aqueous solution, insulation, stirring reaction.Still aging, separate, washing and drying precipitated.

The following example will further describe the present invention.

Embodiment 1

At the volume that has stirring, heating and attemperator is to add the 4L deionized water in the isothermal reactor of 5L, adds the ferrous sulfate (FeSO of 556g (2.0mol) then ₄7H ₂O) (analytical pure), the heating unit of opening isothermal reactor makes system temperature be increased to 45 ℃, stirs simultaneously to make the ferrous sulfate dissolving.With 284g (2.0mol) ammonium oxalate solid fine grain { (NH ₄) ₂C ₂O ₄H ₂O} (analytical pure) joins in the consoluet copperas solution with the feed rate greater than 500g/min, simultaneously with 500 rev/mins stir speed (S.S.) mechanical stirring 20 minutes.This process system temperature keeps 45 ℃.

Close attemperator, still aging 30min separates out the Ferrox crystal.

Separate supernatant liquid, reclaim precipitation Ferrox crystal.With the Ferrox crystal of deionized water wash recovery, till foreign ion is removed.Described foreign ion comprises Fe ³⁺, NH ₄ ⁺, K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure K with the ICP optical spectroscopy ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.The content of described foreign ion is as shown in table 1.

Dry 12 hours of Ferrox crystal after will washing in air under 80 ℃ obtains the 355g dry product, productive rate 98.6%.Analyze the dry product obtain with X-ray diffraction (XRD), its diffractogram and JCPDS figure number are that the standard monocline Ferrox crystalline XRD of 23-0293 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a monoclinic crystal.

Measuring Ferrox crystalline granularity with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL) is 2.54 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal, prove that further its granularity is less than 3 μ m.

Embodiment 2

At the volume that has stirring, heating and attemperator is to add the 4L deionized water in the isothermal reactor of 5L, adds the ferrous sulfate (FeSO of 1335g (4.8mol) then ₄7H ₂O) (analytical pure), the heating unit of opening isothermal reactor makes system temperature be increased to 55 ℃, stirs simultaneously to make the ferrous sulfate dissolving.With 681g (4.8mol) ammonium oxalate solid fine grain { (NH ₄) ₂C ₂O ₄H ₂O} (analytical pure) joins in the consoluet copperas solution with the feed rate greater than 500g/min, simultaneously with 800 rev/mins stir speed (S.S.) mechanical stirring 120 minutes.This process system temperature keeps 55 ℃.

Close attemperator, still aging 30min separates out the Ferrox crystal.

Separate supernatant liquid, reclaim precipitation Ferrox crystal.With the Ferrox crystal of deionized water wash recovery, till foreign ion is removed.Described foreign ion comprises K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure K with the ICP optical spectroscopy ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH4 ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.The content of described foreign ion is as shown in table 1.

Dry 12 hours of Ferrox crystal after will washing in air under 80 ℃ obtains the 846g dry product, productive rate 98.0%.Analyze the dry product obtain with X-ray diffraction (XRD), its diffractogram and JCPDS figure number are that the standard monocline Ferrox crystalline XRD of 23-0293 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a monoclinic crystal.

Measuring Ferrox crystalline granularity with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL) is 2.04 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal, prove that further its granularity is less than 3 μ m.

Embodiment 3

At the volume that has stirring, heating and attemperator is to add the 4L deionized water in the isothermal reactor of 5L, adds the ferrous sulfate (FeSO of 1890g (6.8mol) then ₄7H ₂O) (analytical pure), the heating unit of opening isothermal reactor makes system temperature be increased to 75 ℃, stirs simultaneously to make the ferrous sulfate dissolving.With 965.6g (6.8mol) ammonium oxalate solid fine grain { (NH ₄) ₂C ₂O ₄H ₂O} (analytical pure) joins in the consoluet copperas solution with the feed rate greater than 500g/min, simultaneously with 1000 rev/mins stir speed (S.S.) mechanical stirring 150 minutes.This process system temperature keeps 75 ℃.

Close attemperator, still aging 30min separates out the Ferrox crystal.

Separate supernatant liquid, reclaim precipitation Ferrox crystal.With the Ferrox crystal of deionized water wash recovery, till foreign ion is removed.Described foreign ion comprises K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure K with the ICP optical spectroscopy ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.The content of described foreign ion is as shown in table 1.

Dry 12 hours of Ferrox crystal after will washing in air under 80 ℃ obtains the 1025g dry product, productive rate 98.5%.Analyze the dry product obtain with X-ray diffraction (XRD), its diffractogram and JCPDS figure number are that the standard monocline Ferrox crystalline XRD figure of 23-0293 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a monoclinic crystal.

Measuring Ferrox crystalline granularity with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL) is 2.75 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal, prove that further its granularity is less than 3 μ m.

Comparative Examples 1

At the volume that has stirring, heating and attemperator is to add the 4L deionized water in the isothermal reactor of 5L, adds the ferrous sulfate (FeSO of 556g (2.0mol) then ₄7H ₂O) (analytical pure), the heating unit of opening isothermal reactor makes system temperature be increased to 25 ℃, stirs simultaneously to make the ferrous sulfate dissolving.With 284g (2.0mol) ammonium oxalate solid fine grain { (NH ₄) ₂C ₂O ₄H ₂O} (analytical pure) joins in the consoluet copperas solution with the feed rate greater than 500g/min, simultaneously with 100 rev/mins stir speed (S.S.) mechanical stirring 20 minutes.This process system temperature keeps 25 ℃.

Close attemperator, still aging 30min separates out the Ferrox crystal.

Separate supernatant liquid, reclaim precipitation Ferrox crystal.With the Ferrox crystal of deionized water wash recovery, till foreign ion is removed.Described foreign ion comprises K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure K with the ICP optical spectroscopy ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.The content of described foreign ion is as shown in table 1.

Dry 12 hours of Ferrox crystal after will washing in air under 80 ℃ obtains the 354g dry product, productive rate 98.3%.

Analyze the dry product obtain with X-ray diffraction (XRD), its diffractogram and JCPDS figure number are that the Ferrox crystalline XRD figure of mixing crystal formation of 22-0635 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a mixed crystal.

Measuring Ferrox crystalline granularity with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL) is 0.92 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal, further prove the about 1 μ m of its granularity.

Comparative Examples 2

At the volume that has stirring, heating and attemperator is to add the 4L deionized water in the isothermal reactor of 5L, adds the ferrous sulfate (FeSO of 2224g (8.0mol) then ₄7H ₂O) (analytical pure), the heating unit of opening isothermal reactor makes system temperature be increased to 80 ℃, stirs simultaneously to make the ferrous sulfate dissolving.With 1136g (8.0mol) ammonium oxalate solid fine grain { (NH ₄) ₂C ₂O ₄H ₂O} (analytical pure) joins in the consoluet copperas solution with the feed rate greater than 500g/min, simultaneously with 1000 rev/mins stir speed (S.S.) mechanical stirring 150 minutes.This process system temperature keeps 80 ℃.

Close attemperator, still aging 30min separates out the Ferrox crystal.

Separate supernatant liquid, reclaim precipitation Ferrox crystal.With the Ferrox crystal of deionized water wash recovery, till foreign ion is removed.Described foreign ion comprises K ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, SO ₄ ^2-Measure K with the ICP optical spectroscopy ⁺, Na ⁺, Ti ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺Quality % below 0.1%, use titration measuring NH ₄ ⁺, SO ₄ ^2-Mole % 0.5% when following, can think that foreign ion is removed.The content of described foreign ion is as shown in table 1.

Dry 12 hours of Ferrox crystal after will washing in air under 80 ℃ obtains the 1388g dry product, productive rate 96.4%.

Analyze the dry product obtain with X-ray diffraction (XRD), its diffractogram and JCPDS figure number are that the Ferrox crystalline XRD figure of mixing crystal formation of 22-0635 is consistent, so confirm that dry product is FeC ₂O ₄2H ₂O, and crystal habit is a mixed crystal.

Measuring Ferrox crystalline granularity with laser particle size analyzer (X100 type particles distribution instrument, U.S. HONEYWELL) is 7.62 μ m.

With scanning electron microscope (the JSM-5610LV type amplifies 2000 times, Japanese JEOL) observation Ferrox crystal, further prove the about 8 μ m of its granularity.

Table 1 is the Ferrox crystalline granularity that obtains according to the method for embodiment and Comparative Examples and the content of foreign ion.

Table 1

Claims (9)

1. a Ferrox crystal it is characterized in that this Ferrox crystal is a monoclinic form, and granularity is less than 3 μ m.

2. a Ferrox crystalline production method according to claim 1 comprises the steps:

(a) oxalate solid and Fe ²⁺Concentration is that the aqueous solution of 0.5～1.7mol/l is at 40～80 ℃ of following stirring reactions.

(b) stop insulation, still aging;

(c) isolate supernatant liquid, reclaim precipitation;

(d) precipitation that obtains with deionized water wash step (c) is to remove foreign ion;

(e) drying;

3. according to the method for claim 2, wherein oxalate solid and Fe ²⁺Concentration is that the aqueous solution of 0.5～1.7mol/l is at 45～75 ℃ of following stirring reactions.

4. according to the method for claim 2, wherein said divalent iron salt is selected from ferrous sulfate, iron protochloride, one or more in the ferrous bromide.

5. according to the method for claim 2, wherein said oxalate is selected from sodium oxalate, potassium oxalate, one or more in the ammonium oxalate.

6. according to the method for claim 2, wherein said oxalate solid join feed rate in the divalent iron salt aqueous solution greater than 500g/min.

7. according to the method for claim 2, wherein said stirring is a mechanical stirring, stirs 20～150 minutes with 100～1000 rev/mins stir speed (S.S.)s.

8. according to the method for claim 2, when air drying, wherein said drying temperature is 50～90 ℃, 10～18 hours described time of drying.

9. according to the method for claim 2, when dry in a vacuum, wherein said drying temperature is 80～110 ℃, and be 2～8 hours described time of drying.

Images