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A method for preparing ferrous oxalate of specific crystals by using waste liquid of cold-rolled steel hydrochloric acid pickling

A technology for ferrous oxalate and pickling waste liquor, which is applied in the fields of carboxylate preparation, carboxylate preparation, organic chemical methods, etc. Problems such as unstable quality of iron and lithium, to achieve the effect of low cost, small particle size and uniform particle size

Active Publication Date: 2018-01-19
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] 1. Because the pickling waste liquid of steelworks is generally mixed with electroplating additives, mainly composed of C, H, O and other elements, the ferrous oxalate prepared by the above method has a small and uniform particle size, but due to the concentration of electroplating additives Impurities cannot be removed, so the crystallinity is not good, which directly affects the quality of lithium batteries prepared later
[0007] 2. The temperature of the whole preparation process is too high, close to the boiling point of water, so it can only be used for relatively stable pickling solutions such as sulfuric acid pickling solution and nitric acid picking solution. It will continue to volatilize at a high temperature, resulting in poor control of the process and affecting the quality of ferrous oxalate products
[0008] 3. The crystal structure of the ferrous oxalate prepared by the prior art is not clear, and it is usually a mixed type of α-type ferrous oxalate and β-type ferrous oxalate. Since the α-type and β-type are mixed together, the ferrous phosphate prepared later Lithium quality is unstable

Method used

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  • A method for preparing ferrous oxalate of specific crystals by using waste liquid of cold-rolled steel hydrochloric acid pickling
  • A method for preparing ferrous oxalate of specific crystals by using waste liquid of cold-rolled steel hydrochloric acid pickling
  • A method for preparing ferrous oxalate of specific crystals by using waste liquid of cold-rolled steel hydrochloric acid pickling

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Prepare α-type ferrous oxalate, the steps are as follows:

[0033] (1) Pretreatment of waste hydrochloric acid pickling of cold-rolled steel: heating up the waste hydrochloric acid pickling of cold-rolled steel to more than 85°C, adding excess iron filings, and adjusting the ferrous ion content in the solution to 180g / L, Adjust the pH value to 2.5, use a straw to remove the black oily substance produced on the surface of the solution, stir and react at a constant temperature of 85°C for 6 hours, add hydrochloric acid and water to make the content of hydrochloric acid in the solution 100g / L, and filter to remove impurities after standing for 24 hours;

[0034] (2) Generate ferrous hydroxide suspension: Add ammonia or calcium oxide to the solution treated in step (1), adjust the pH value of the solution to 10.7, control the reaction temperature to 85°C, and generate ferrous hydroxide suspension ;

[0035] (3) Generate ferrous oxalate precipitation: control the reaction t...

Embodiment 2

[0039] Preparation of β-type ferrous oxalate, the steps are as follows:

[0040] (1) Pretreatment of waste hydrochloric acid pickling of cold-rolled steel: heating up the waste hydrochloric acid pickling of cold-rolled steel to more than 85°C, adding excess iron filings, and adjusting the ferrous ion content in the solution to 180g / L, Adjust the pH value to 2.5, use a straw to remove the black oily substance produced on the surface of the solution, stir and react at a constant temperature of 85°C for 6 hours, add hydrochloric acid and water to make the content of hydrochloric acid in the solution 50-100g / L, and filter it after standing for 24 hours miscellaneous;

[0041] (2) Generate ferrous hydroxide suspension: Add ammonia or calcium oxide to the solution treated in step (1), adjust the pH value of the solution to 5.8, control the reaction temperature to 30°C, and generate ferrous hydroxide suspension ;

[0042] (3) generate ferrous oxalate precipitation: the control reacti...

Embodiment 3

[0047] Example 3: Preparation of lithium iron phosphate by using α-type ferrous oxalate

[0048] Weigh 0.01M lithium hydroxide, 0.01M α-type ferrous oxalate (prepared according to Example 1), add glucose with a weight ratio of 5% of the above reaction substances, add 25ml of ethanol to dissolve, stir for 24h, and dry at 60°C. Finally, the above mixture was calcined at 700° C. for 10 h in an argon atmosphere, and cooled naturally to room temperature to obtain lithium ferrous phosphate.

[0049] Through material characterization, it was found that the (111) diffraction peak of lithium iron phosphate prepared from α-type ferrous oxalate was higher than the (211) diffraction peak, indicating that there was no dislocation and mixing of Li and Fe atoms. In addition, the higher diffraction intensity of the sample shows that the lithium ferrous phosphate prepared by α-type ferrous oxalate has better crystallinity (see image 3 ).

[0050] Through the electrochemical performance test...

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Abstract

The invention relates to a method for preparing ferrous oxalate with specific crystals from cold rolled steel chlorohydric acid pickling waste liquid. According to the method, preparation of alpha type ferrous oxalate and beta type ferrous oxalate is included, the pH value required when ferrous hydroxide is generated and the subsequent reaction temperature are adjusted, pure-phase alpha type ferrous oxalate and pure-phase beta type ferrous oxalate can be obtained, lithium iron phosphate prepared from alpha type ferrous oxalate has a higher crystallinity degree and a better crystal structure, and electrochemical performance presented by lithium iron phosphate is more excellent. A ferrous oxalate product prepared through the method is about 6-7 microns in particle size, the purity is greater than 99.5%, and no miscellaneous phase peak is found in XRD display. Due to the fact that the method is low in technical cost, in addition, the crystal structure of ferrous oxalate can be selectively adjusted and controlled, the process is simple, and the method is suitable for industrial production.

Description

technical field [0001] The invention relates to the technical field of material synthesis, in particular to a method for preparing specific crystal ferrous oxalate by using waste hydrochloric acid pickling liquid of cold-rolled steel. Background technique [0002] The pickling waste liquid produced by hot rolling of steel generally contains 0.05-5g / L H + and 60-250g / L Fe 2+ . Due to its severe corrosiveness, it has been included in the "National List of Hazardous Wastes". The direct discharge of this kind of waste liquid not only seriously pollutes the environment, but also causes great waste. At present, the treatment and application of iron and steel pickling waste liquid are mostly for the recovery of iron, or the recovery of iron oxides as fuel, or the use of pickling waste liquid to prepare sewage treatment agents. [0003] Lithium ferrous phosphate electrode material has a stable olivine structure, a high discharge voltage of 3.4V, and a theoretical capacity of 170m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/41C07C55/07
CPCC07B2200/13C07C51/412C07C55/07
Inventor 张英杰李雪梁慧新朱子翼董鹏
Owner KUNMING UNIV OF SCI & TECH
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