CN102583291A - Preparation process of ferric phosphate capable of simultaneously obtaining nitric acid and ammonium nitrate - Google Patents

Abstract

The invention discloses a preparation process of ferric phosphate capable of simultaneously obtaining nitric acid and ammonium nitrate, which comprises the following steps that: ferric nitrate (Fe(NO3)2.9H2O) solution with a given mol ratio is adequately mixed with orthophosphoric acid (H3PO4), ferric phosphate dehydrate (FePO4.2H2O) is added to be used as a product crystallization inducer, and crystallized precipitated products after the reaction under a given condition are filtered, washed and dried, so a ferric phosphate product and a primary byproduct of dilute nitric acid with concentration of 50g/l to 76g/l can be obtained; the filtered mother solution containing the dilute nitric acid is recycled and then is reacted with sheet iron according to a mol ratio of 1: 0.5 to 1 to produce ferrous nitrate and secondary byproduct ammonium nitrate; and the ammonium nitrate is recycled in the following way that: the mother solution simultaneously containing the dilute nitric acid with the concentration of 30g/l to 50g/l and high-concentration ammonium nitrate with concentration of 64g/l to 80g/l are neutralized by waste ammonia to obtain the byproduct ammonium nitrate. The Fe(NO3)2.9H2O is reacted with H3PO4, so as long as an appropriate temperature is maintained, the ferric phosphate with high purity can be obtained, no byproduct which is difficult to separate is produced, and the waste liquid is recyclable.

Description

It is a kind of to obtain nitric acid, the preparation technology of the ferric phosphate of ammonium nitrate simultaneously

Technical field

It is specifically a kind of that ferric phosphate is obtained by easily-controllable chemical single step reaction simple to operate the present invention relates to a kind of technique for preparing ferric phosphate.

Background technology

Ferric phosphate original research is main in fields such as agricultural, pigment industry, steel industry, glass-ceramics.Found that ferric phosphate has unique catalysis characteristics, ion-exchange capacity and chemical property etc., made its purposes more and more wider later.Because phosphoric acid body has abundant chemical constitution, a kind of iron phosphate material that battery-grade iron phosphate is researched and developed aiming at lithium iron phosphate battery positive material characteristic.Chemical molecular formula is FePO₄·2H₂O, the color of the phosphate dihydrate iron of high-purity is near-white or shallow（It is light）Yellow-white powder, with the loss of the crystallization water, color gradually turns yellow, and pure anhydride is in yellow-white powder.Ferrophosphorus ratio is the index for weighing ferric phosphate quality most critical, is also the factor for determining LiFePO4 quality most critical.The iron phosphorus of battery-grade iron phosphate, 0.97 ~ 1.02, also has strict demand than general to other impurity contents：Magnesium≤50ppm, sodium≤50ppm, potassium≤50ppm, copper≤10ppm, cadmium≤10ppm, lead≤15ppm.

Preparing the method for ferric phosphate has a many kinds, the compound of soluble iron, and phosphoric acid or soluble phosphate can be as reaction raw materials, but raw material is different, and synthesis technique and reaction condition then differ widely.Industrially conventional is with FeSO₄、H₃PO₄For reaction raw materials, pH values of the NaOH to control reaction system, NaClO₃FePO is synthesized for oxidant₄·2H₂O。

Reaction equation is：

      6FeSO₄ + 6H₃PO₄ + NaClO₃ + 12NaOH                                                6FePO₄·2H₂O + 6Na₂SO₄ + NaCl + 3H₂O

Synthesis technique is：

                 

FeSO4Dissolving

Mixing acidifying

Oxidation

Synthesis

Filtration washing

Drying

Crush

Finished product.

The production method is because using sodium chlorate, as oxidant, NaOH introduces a large amount of sodium ions in system, not only causes byproduct Na as PH conditioning agent₂SO₄, NaCl be difficult separation, and the product of gained needs to consume lot of pure water and rinsed, a large amount of waste water of generation.Further, since post processing trouble, causes unstable product quality.Present invention research is found：With Fe (NO₃)₂·9H₂O and H₃PO₄Reaction, as long as controlling suitable temperature, can obtain required product ferric phosphate, and product quality purity is high, the byproduct of no difficult separation, waste liquid reusable edible.

 

The content of the invention

The present invention main task be provide it is a kind of can be while obtaining nitric acid, the preparation technology of the ferric phosphate of ammonium nitrate；Specifically one kind can reach clean manufacturing, reduce the discharge of discarded object, and can collect the preparation technology for the ferric phosphate that accessory substance is recycled.

In order to solve the above-mentioned technical problem, the present invention is realized in：It is 1 by mol ratio:0..9 Fe (NO ~ 1.1₃)₂·9H₂O solution and H₃PO₄It is sufficiently mixed, and adds FePO42H₂O crystallizes derivant as product, and (addition is Fe (NO₃)₂·9H₂The 0.01~1% of O mass percents), it is heated to keeping constant temperature stirring after 95 DEG C ~ 100 DEG C, and it is passed through air progress oxidation reaction, air velocity is about 5 liters/min, stop reaction after about 4 hours, then filtered the precipitated product after crystallization, wash, dried 6 hours at 120 DEG C, produce phosphoric acid iron product.

Reaction equation is：

(1)、4Fe(NO₃)₂ + 4H₃PO₄+ 6H₂O + O₂ 

 4FePO₄·2H₂O + 8HNO₃

From above-mentioned reaction equation, this reaction generates one-level accessory substance nitric acid, and it recycles as follows：

The above-mentioned filtrated stock water containing concentration in 50g/l ~ 76g/l dust technologies is reclaimed, then 1 is pressed with iron sheet again：The ratio of 0.5 ~ 1.0 mol ratio, then the reaction generation ferrous nitrate in the case of iron sheet excess, if ratio does not reach requirement, can add a part of fresh nitric acid, be recycled with reaching.

Reaction equation is：

(2)、10HNO₃(dilute)+4Fe

 4Fe(NO₃) ₂ + NH₄NO₃ + 3H₂O

Recovery to secondary byproduct ammonium nitrate is as follows：

Equation can be seen that when preparing ferrous nitrate from the reactions above, also the generation of secondary byproduct ammonium nitrate, and when mother liquor water circulation use number of times is more, ammonium nitrate concn can become more and more higher in reaction system, in this case, can cause FePO₄·2H₂O product recovery rates are substantially reduced.We are at the method for use：By the mother liquid coming containing dust technology Yu high concentration ammonium nitrate simultaneously, neutralized using deposed ammonia and obtain byproduct ammonium nitrate.

Reaction equation is：

(3)、NH₄OH + HNO₃

 NH₄NO₃ + H₂O

The innovative point of the present invention：

1st, reactant species are few, are conducive to the control of raw material usage amount, and product recovery rate is up to 93.3%.；

2nd, single step reaction, it is simple to operate easy to control；

3rd, the nitric acid generated in product can react generation ferrous nitrate with iron plate under normal temperature condition, and clean manufacturing and recycling economy so then can be achieved as the raw material of synthesis ferric phosphate again, save energy resource, reduce production cost；

4th, the raw material sources of this technique synthesis ferric phosphate are extensively, cheap.

Specific embodiment 1：

Take the Fe (NO that 800ml concentration is 0.5mol/l₃)₂·9H₂O, the H with 42.3g₃PO₄It is sufficiently mixed, adds 1...1g FePO₄·2H₂After O crystallization derivants, it is heated with stirring to 95 DEG C or so rear holding constant temperature stirrings, and it is passed through air progress oxidation reaction, air velocity is about 5 liters/min, water is suitably added in insulating process, the addition of water is not vaporized completely by moisture therein and is defined, without specific requirement, stops reaction after about 4 hours.It is washed out, suction filtration is obtained after filter cake, is positioned over 120 DEG C of drying in oven, that is, it is 93.3% to obtain measuring yield after product.

Calculate data as follows：

Fe(NO₃)₂·9H₂O and H₃PO₄Mol ratio be 1:1.08, then H₃PO₄It is excessive, if Fe (NO₃)₂·9H₂O reacts completely, then FePO in theory₄·2H₂O yield is：0.5*0.8*187=74.8g, by testing obtained FePO₄·2H₂O quantity is 70.9g, deducts the crystal seed quantity 1.1g being previously added, the net production actually obtained is 69.8g, so FePO₄·2H₂O yield is：69.8/74.8=93.3%

Specific implementation 2:

Take in one-level mother liquor water, concentration of nitric acid about 95g/l that 600ml contains dust technology, the stainless steel cup for placing 1 liter size, with small-sized machine,massing low rate mixing（About 30 revs/min）, then slowly it is put into 120 grams（It is excessive）Tagger（About 1 millimeter of thickness, is rolled into about 1 centimetre of diameter, long 1 ~ 1.5 centimetre garden cylindrical shape）, (15 ~ 24 DEG C) are reacted 20 hours at normal temperatures.Then stop reaction, take out reaction solution, filtering, cooling, clarification, you can obtain ferrous nitrate.

Take above-mentioned utilization one-level mother liquor water that the Fe (NO that ferrous nitrate 500ml, measured concentration are 0.46mol/l are made₃)₂·9H₂O, the H with 24...3g₃PO₄It is sufficiently mixed, adds 0.6g FePO₄·2H₂After O crystallization derivants, 95 DEG C or so rear holding constant temperature stirrings are heated with stirring to, and are passed through air progress oxidation reaction, air velocity is about 5 liters/min, and water is suitably added in insulating process, in order to avoid moisture is vaporized completely, stops reaction after about 4 hours.It is washed out, suction filtration is obtained after filter cake, is positioned over 120 DEG C of drying in oven, that is, it is 91.4% to obtain measuring yield after product.

Calculate data as follows：

Fe(NO₃)₂·9H₂O and H₃PO₄Mol ratio be 1:1.08, then H₃PO₄It is excessive, if Fe (NO₃)₂·9H₂O reacts completely, then FePO in theory₄·2H₂O yield is：0.46*0.5*187=43.0g, by testing obtained FePO₄·2H₂O quantity is 39.9g, deducts the crystal seed quantity 0.6g being previously added, the net production actually obtained is 39.3g, so FePO₄·2H₂O yield is：39.3/43.0=91.4%.

It can be seen that：The present invention not only synthesizes the ferric phosphate than higher yields but also has reclaimed two kinds of accessory substances；And consersion unit is simple, energy consumption is small, with low cost；And the problem of solve mother liquor water circulation use, really realize clean manufacturing and recycling economy.

Claims (2)

1. a kind of can obtain nitric acid, the preparation technology of the ferric phosphate of ammonium nitrate simultaneously, it is characterised in that：It is 1 by mol ratio:0.9 ~ 1. 1 Fe (NO₃)₂·9H₂O solution and H₃PO₄It is sufficiently mixed, and adds FePO42H₂O crystallizes derivant as product, it is heated to 95 DEG C ~ 100 DEG C, continue to keep constant temperature stirring, and air progress oxidation reaction is passed through, air velocity is about stopping reaction after 5 liters/min, about 4 hours, then the precipitated product after crystallization is filtered, washing, is dried 6 hours at 120 DEG C, and it is 50g/l ~ 76g/l dust technologies to produce phosphoric acid iron product and one-level by-product concentration；The above-mentioned filtrated stock water containing dust technology is reclaimed, 1 is then pressed again：0.5 ~ 1.0 mol ratio and iron sheet reaction generation ferrous nitrate and secondary byproduct ammonium nitrate；Ammonium nitrate is recovered as：It will be simultaneously the high concentration ammonium nitrate mother liquor water that 30g/l ~ 50g/l dust technologies are 64g/l ~ 80g/l with concentration containing concentration, and be neutralized using deposed ammonia and obtain byproduct ammonium nitrate.

2. according to claim 1 a kind of nitric acid, the preparation technology of the ferric phosphate of ammonium nitrate can be obtained simultaneously, it is characterised in that：FePO4·2H₂O additions are Fe (NO₃)₂·9H₂The 0.01~1% of O mass percents.