CN-121990542-A - Continuous iron phosphate preparation method and system for adjusting grain size distribution

CN121990542ACN 121990542 ACN121990542 ACN 121990542ACN-121990542-A

Abstract

The invention relates to the field of iron phosphate preparation, in particular to a continuous iron phosphate preparation method and system for adjusting grain size distribution. The method comprises the steps of mixing an iron ingot with dilute phosphoric acid, performing an iron melting reaction to obtain an iron melting liquid, pumping the iron melting liquid and hydrogen peroxide with the total amount of 50-95% into a synthesis kettle with a circulation pipeline for synthesis reaction, supplementing 5-50% of the total amount of hydrogen peroxide in an aging stage, keeping constant temperature in the supplementing process, continuing the reaction after supplementing the hydrogen peroxide, finishing aging, and performing filter pressing on the obtained slurry to obtain solid ferric phosphate. The method can realize sufficient ferric phosphate dissolution, avoid formation of insoluble iron residues in the molten iron, improve the material dispersity, and fully oxidize ferrous iron, thereby improving the grain composition.

Inventors

MA HANG
Yan Yinxian
ZHOU YANJIE
ZHENG JIE
HUA TIAN
ZHANG JIAN
ZHA ZUOTONG
ZHANG JINYUAN
LI XING
LIU BINGFU
CHEN ZHANGHONG
WAN BANGLONG
ZHANG JIE

Assignees

云南云天化股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260225

Claims (10)

1. A method for preparing continuous iron phosphate with adjustable grain size distribution, which is characterized by comprising the following steps: Step (1), mixing an iron ingot with dilute phosphoric acid and performing an iron melting reaction to obtain an iron melting liquid; Step (2) pumping the molten iron and hydrogen peroxide accounting for 50-95% of the total amount into a synthesis kettle with a circulation pipeline for synthesis reaction, wherein the circulation flow is controlled to be a first flow in a first reaction period, the circulation flow is controlled to be a second flow in a second reaction period, the circulation flow is controlled to be a third flow in a third reaction period, and the circulation flow is controlled to be a third flow; And (3) after the synthesis reaction in the step (3) enters an aging stage, preserving heat at a certain temperature, then supplementing 5-50% of hydrogen peroxide in the total amount required, keeping the constant temperature in the supplementing process, continuing the reaction after supplementing the hydrogen peroxide, finishing aging, and performing filter pressing on the obtained slurry to obtain the solid ferric phosphate.
2. The method for producing continuous iron phosphate with the grain size distribution adjusted according to claim 1, wherein the step (1) specifically comprises the steps of: Step 1.1, sampling every time a period of time after the iron melting reaction occurs, detecting the concentration of iron ions in an iron melting liquid sample, calculating the ratio of phosphorus to iron in the sample, stopping heating when the rate of decrease of the ratio of phosphorus to iron is less than or equal to 0.01/h, pumping the iron melting liquid out of an iron melting tank for caching, pumping unused dilute phosphoric acid, and then starting circulation to react the dilute phosphoric acid with blocking substances generated on the surface of an iron ingot; Step 1.2, discharging the washed dilute phosphoric acid buffer memory to be used as an initial reaction liquid in the next iron melting process for recycling; And 1.3, re-pumping the buffered molten iron into an iron melting tank (1), and continuing to perform iron melting reaction with the iron ingot.
3. The continuous iron phosphate preparation method for adjusting grain size distribution according to claim 2, wherein in the step 1.1, the mass concentration of the phosphoric acid solution is 15-30wt%, the temperature is raised to 80-90 ℃ for reaction, sampling is carried out every 50-60 min, and dilute phosphoric acid reacts with the obstructing substances generated on the surface of the iron ingot for 1-3 h.
4. The continuous iron phosphate preparation method for adjusting grain composition according to claim 2, wherein in step 1.3, the iron dissolution reaction temperature is 80-90 ℃, and the concentration of iron ions in the iron melting liquid is periodically sampled and detected until the phosphorus-iron ratio is monitored and displayed in the iron melting liquid to reach 2.4-2.8, and the iron melting liquid is stored as qualified iron melting liquid for standby.
5. The continuous iron phosphate preparation method for adjusting grain size distribution according to claim 1, wherein in the step (2), the molar ratio of the total amount of hydrogen peroxide to Fe 2+ in the molten iron is 1-1.3:1, and the concentration of the hydrogen peroxide is 10-27wt%.
6. The continuous iron phosphate preparation method for adjusting grain size distribution according to claim 1, wherein in the synthesis reaction process of the step (2), a cyclic reaction is performed at 65-75 ℃, and the cyclic flow is controlled according to the following requirements: the reaction is carried out for 0 to 30 minutes, the circulation flow is 250-300 mL/min; the reaction is carried out for 30 to 60 minutes, the circulation flow rate is 200-250 mL/min; The reaction is carried out for 60 to 90 minutes, the circulation flow rate is 150-200 mL/min.
7. The continuous iron phosphate preparation method for adjusting grain composition according to claim 1, wherein in the step (3), 5-50% of hydrogen peroxide is added after heat preservation is performed for 1-3 hours at 70-80 ℃, the concentration of the hydrogen peroxide is 10-27wt% and the adding time is controlled to be 0.4-0.6 hours, the temperature is kept at 70-80 ℃ in the adding process, and the reaction is continued for 1-2 hours at 70-80 ℃ after the hydrogen peroxide is added.
8. The continuous iron phosphate preparation system for adjusting the grain composition is characterized by comprising an iron melting tank, a synthesis kettle and an aging kettle, wherein the iron melting tank, the synthesis kettle and the aging kettle are communicated; The circulating pipelines comprise circulating branch pipes, valves and circulating pumps, wherein two ends of the circulating branch pipes of the iron melting tank and the synthesizing kettle are respectively communicated with the upper end and the lower end of the side walls of the iron melting tank and the synthesizing kettle; the hydrogen peroxide conveying pipe is respectively communicated with the feed inlets of the synthesis kettle and the ageing kettle.
9. The continuous iron phosphate production system of claim 8, further comprising an iron phosphate buffer tank, a phosphoric acid recycle tank, and a feed buffer tank; The iron melting tank is communicated with the iron melting tank, and a pipeline for communicating the iron melting tank, the phosphoric acid recycling tank and the feeding buffer tank is respectively provided with a conveying pump and a valve; The feeding buffer tank is communicated with the synthesis kettle, and a conveying pump and a valve are arranged on a communicated pipeline; the ageing kettle is communicated with a circulating pump outlet pipe of the synthesis kettle, valves are arranged on the communicated pipes, valves are respectively arranged on the pipes of the hydrogen peroxide conveying pipe, the synthesis kettle and the ageing kettle, and a discharge pipe is arranged on a discharge hole of the ageing kettle.
10. The continuous iron phosphate preparation system for adjusting grain composition according to claim 8, wherein a stirrer is arranged in the synthesis kettle, and heat exchange devices are arranged outside the iron melting tank and the aging kettle.

Description

Continuous iron phosphate preparation method and system for adjusting grain size distribution Technical Field The invention relates to the technical field of iron phosphate preparation, in particular to a continuous iron phosphate preparation method and system for adjusting grain size distribution. Background In the current iron phosphate preparation process, the iron phosphate preparation process mainly takes high-purity iron, purified phosphoric acid and hydrogen peroxide as core raw materials, and the preparation of the iron phosphate is completed through a plurality of key steps. In the iron melting step, high-purity iron is stacked in an iron melting kettle according to a specific shape, and 85% phosphoric acid by mass percent is diluted and then injected into the iron melting kettle to react to obtain ferrous dihydrogen phosphate solution (namely iron melting liquid). In the subsequent oxidation step, the molten iron is pumped into 2 to n serial synthesis kettles for continuous oxidation, hydrogen peroxide is added according to stoichiometric ratio, and the feeding time of the hydrogen peroxide to the synthesis kettles is controlled, so that ferrous dihydrogen phosphate is oxidized into ferric phosphate dihydrate for precipitation. In the iron melting link, a layer of compact substance is easy to generate on the surface of a newly formed iron ingot which is not dissolved in time, the substance can obviously prevent the iron ingot from being further dissolved in phosphoric acid, the reaction speed of iron melting is reduced, the iron melting efficiency is greatly reduced, the production period is prolonged, and the production cost is increased. In the oxidation synthesis link, the traditional multi-kettle process has the problem of uneven material dispersion, and the uniformity and stability of the product are affected. In addition, the aging time of the particles in the traditional process is single, and reasonable particle grading cannot be formed, so that the quality improvement of the product is further limited. Disclosure of Invention The invention aims to provide a continuous preparation method and a continuous preparation system for ferric phosphate for adjusting the grain size distribution, which can ensure that ferric phosphate in the molten iron is fully dissolved, avoid forming insoluble iron residues in the molten iron, improve the material dispersity, ensure that ferrous iron is fully oxidized and improve the grain size distribution. The technical scheme of the invention is as follows: In a first aspect, the present invention provides a continuous iron phosphate production process for adjusting grain size distribution, comprising the steps of: Step (1), mixing an iron ingot with dilute phosphoric acid and performing an iron melting reaction to obtain an iron melting liquid; Step (2) pumping the molten iron and hydrogen peroxide accounting for 50-95% of the total amount into a synthesis kettle with a circulation pipeline for synthesis reaction, wherein the circulation flow is controlled to be a first flow in a first reaction period, the circulation flow is controlled to be a second flow in a second reaction period, the circulation flow is controlled to be a third flow in a third reaction period, and the circulation flow is controlled to be a third flow; And (3) after the synthesis reaction in the step (3) enters an aging stage, preserving heat at a certain temperature, then supplementing 5-50% of hydrogen peroxide in the total amount required, keeping the constant temperature in the supplementing process, continuing the reaction after supplementing the hydrogen peroxide, finishing aging, and performing filter pressing on the obtained slurry to obtain the solid ferric phosphate. Preferably, the step (1) specifically includes the following steps: Step 1.1, sampling every time a period of time after the iron melting reaction occurs, detecting the concentration of iron ions in an iron melting liquid sample, calculating the ratio of phosphorus to iron in the sample, stopping heating when the rate of decrease of the ratio of phosphorus to iron is less than or equal to 0.01/h, pumping the iron melting liquid out of an iron melting tank for caching, pumping unused dilute phosphoric acid, and then starting circulation to react the dilute phosphoric acid with blocking substances generated on the surface of an iron ingot; Step 1.2, discharging the washed dilute phosphoric acid buffer memory to be used as an initial reaction liquid in the next iron melting process for recycling; And 1.3, re-pumping the buffered molten iron into an iron melting tank (1), and continuing to perform iron melting reaction with the iron ingot. In step 1.1, the mass concentration of the phosphoric acid solution is preferably 15-30wt%, the temperature is raised to 80-90 ℃ for reaction, sampling is carried out every 50-60 min, and the dilute phosphoric acid reacts with the obstructing substances generated on the surface of the