CN1019482B

CN1019482B - Npk complex fertilizer

Info

Publication number: CN1019482B
Application number: CN 85106816
Authority: CN
Inventors: 奥拉夫·克乔尔; 托斯坦·奥伯斯塔德; 汉斯·格罗兰德
Original assignee: Norsk Hydro ASA
Current assignee: Norsk Hydro ASA
Priority date: 1984-09-12
Filing date: 1985-09-11
Publication date: 1992-12-16
Also published as: CN85106816A

Abstract

The present invention relates to NPK fertilizer which is manufactured by using KCL and/or K2SO4 as a potassium source. The NPK fertilizer also comprises 0.2 to 3.0% (measured by Mgo) of magnesium and is added into a product by the MgO. The present invention relates to the method for manufacturing the product. The method is characterized in that before granulation or before or during the granulation, 0.2 to 3.0% of active MgO and potassium salt are added into concentrated nitrogen and phosphorus solution. The MgO which is lightly calcined is better added, the average grain size of the MgO is 0.2 to 3.0mm, and the MgO is just added in a mixer before the granulation. The new product has the tendency of reducing expansion and incrustation. A01N43/06.

Description

NpK complex fertilizer

The invention relates to manufacturing chloride-and/or the method for the NPK-fertilizer (compound manure) of vitriol, this fertilizer has the expansion and the caking trend of attenuating.This fertilizer is by with mineral acid acidifying phosphoric acid salt, removes calcium salt, evaporation, granulation or granulating then and makes.

Between the shelf lives, especially during bulk storage, caking takes place and/or expands in the particle of some NPK-fertilizer.It seems this problem partly with the potassium Source Type that uses, just KCL or K ₂SO ₄Relevant.

The fertiliser granulates of newborn output is free-pouring, but afterreaction slowly can take place, and some afterreactions cause the volume of fertiliser granulates to increase and caking significantly.If can keep low water content (＜0.35%) operational condition at production period, above mentioned problem it seems and just can avoid.Yet strict in fact like this operational condition can cause a kind of production process of high complexity.Such situation often takes place: even after it is believed that the operational condition of having observed this strictness, can the production process of this high complexity also can cause the problem that obtain qualified product stock performance.

Problem or be the storage problem that high-moisture itself causes so, or be that these free-waters cause harmful afterreaction that some is possible because the existence of (free) water of loosel bound is arranged.

From No. 2000652 Japanese patent applications, know already, stablize NPK-fertilizer by the magnesium hydroxide that adds 0.5-1.0% weight (calculating), with opposing humidity and influence of temperature variation with MgO.Yet this additive causes and mixes moisture content and can not solve the problem of facing.

Find solution to this problem, contriver to think as failing as you know and be necessary further to study, to determine to cause the true cause of storage problem.So set about from the afterreaction theory nearby.Can change the sylvite type of use here, and can stop from now on or postpone contingent bad afterreaction greatly in order to come to understand.People are from research KCL and K ₂SO ₄Possible separately afterreaction is set about.

Rule of thumb, only some NPK-prescription goes wrong, thereby people have studied some of them and had been found that the particulate prescription that contains its volume of increase (volume change percentum) between the shelf lives.This volume change has caused grain breakage and agglomeration problems.A kind of NPK-prescription like this prepares from the aqueous solution with approximately following weight % composition:

38.9% NH ₄NO ₃

12.1% NH ₄H ₂PO ₄+（NH ₄） ₂HPO ₄

25.8% K ₂SO ₄

15.2% MgSO ₄·H ₂O

0.5% H ₂O

This mixture comprises a kind of chemical system of complexity.Component concentration in the final product can not be the same with said components content.Because the humidity existence is arranged and has big temperature contrast, this system can not be regarded as a kind of mechanical mixture of salt.

A kind of most important main ingredient NH ₄NO ₃(AN) solidify and further be chilled to room temperature during may pass through mutually several.Each second phase changes and at first causes volume change.For example be converted to AN IV volume and increase about 3.6% from the AN III.

Yet the chemical reaction that is core reaction in mechanism of intumescence is the transformation of a pair of salt, it can be write as follows:

In research intumescent the time, prove that with the means of chemical analysis and x-ray diffractometer it is in the basic fertilizer that the conversion of this a pair of salt occurs in vitriol.This conversion just begins in blender, proceeds during bulk storage.Proved response speed at first depends primarily on water content, secondly is temperature.But also depend on chemical constitution to a great extent.

When reaction is when carrying out according to reaction formula (1), this conversion to salt will cause serious expansion.If AN exists with the III formula, expand 5.3%, if AN is that to exist with the IV formula should be 7.7%.Known when moisture exists being transformed in 32 ℃ and taking place down from the III formula to the IV formula.

To the volume increase that the conversion of salt causes swelling can not be described separately by this.Yet some studies show that.KNO ₃(NH ₄) ₂SO ₄The two will further react and generate new compound.

For the principal element that determines whether that this conversion to salt is a mechanism of intumescence, how many NH must determine has in having the sample of different turgiditys ₄NO ₃Or K ₂SO ₄Changed:

Use the method for a kind of component of slective extraction to determine conversion degree.For a large amount of sample determinations with different turgiditys unreacted NH ₄NO ₃Find as unreacted NH ₄NO ₃Amount when increasing, just work as NH ₄NO ₃Degree of conversion when increasing, expanding increases.

Have been found that at turgidity percentage ratio and unreacted NH ₄NO ₃This principal reaction with regard to having confirmed that this conversion to salt is a mechanism of intumescence of good corresponding relation is arranged between the amount.

Turgidity (S) may be defined as:

S=100K ((L ₁-L ₂))/(L ₁) in the formula

L ₁Be the litre weight before the swell test

L ₂Be the litre weight after the swell test

K is the constant that depends on fertilizer type

When using KCL to do the potassium source, the form that this conversion can be simplified is write as follows:

KCL will can not exist with free state under equilibrium state.When the amount of the KCL that is added when being known.Transformable NH ₄NO ₃Amount can easily calculate.

Have been found that when free water content is high, transform and at full speed carry out.With slective extraction NH from the finished product ₄NO ₃Method study above-mentioned reaction and proceeded to what degree to the right.

Studied a series of sample, with the NH that determines to exist ₄NO ₃There are much parts and KCl reaction to generate NH ₄Cl and KNO ₃Above-mentioned these same samples have also been measured caking trend.And find that caking trend is with the NH that changes ₄NO ₃The part increase and increase.Because top indicated reaction is the function of the free-water that exists, it is contemplated that with several different methods and reduce free water content, can stop or postpone said conversion at least.

Therefore, it seems to have in the fertilizer formula of some free-waters that afterreaction is at KCl and K at some ₂SO ₄The two takes place when being used as the potassium source, and it seems that these afterreactions give product bad character.

As having known the front, the product that obtains enough low water content with the method for general red-tape operati condition is difficult, so people begin one's study in conjunction with the possibility of the free-water in the final NPK-fertilizer.

The objective of the invention is to obtain a kind of KCl of containing and/or K ₂SO ₄This fertilizer of NPK-fertilizer between the shelf lives, especially be stable during the bulk storage.So that do not have the expansion of fertiliser granulates and/or caking to take place.

Further aim of the present invention is to obtain a kind ofly to make the simple of this product and reasonable method.

Several additives of combination water are known, for example about NH ₄NO ₃, it is significant as water in conjunction with additive because of various reasons here.Yet, do not find out obviously that such additive will be applicable to the problem that solves above-mentioned NPK-fertilizer.Therefore the inventor has to study the additive whether other is arranged and goes for this purpose.When selecting additive, also have to consider between salt in fertilizer and the additive which reaction to take place.Yet, additive should be on the agronomy qualified so that they do not reduce the agronomy quality of this product.

From the angle of above-mentioned requirement, people at first go in for the study some additive to containing K ₂SO ₄Influence as the NPK-fertilizer in potassium source.

In current test to a series of water-free Na ₂SO ₄Test.This salt can become crystal water in conjunction with reaching 10 mole of water, just every gram Na ₂So ₄In conjunction with 1.26 gram water.Thereby the result that just should provide, its condition is as long as its Fails To Respond thereby generation do not have the compound of water associativity.Further to Na ₂So ₄Studies show that.It has low water in conjunction with effectiveness in this salt system.

Al(OH) ₃Be a kind of known water in conjunction with additive, the synthetic NPK-solution of per 100 grams adds the Al(OH that the aluminium amount is 0.1 gram) ₃Yet,, find this additive also without any significant water in conjunction with effectiveness.

The magnesium of kieserite form is a kind of suitable component in some kinds of NPK-fertilizer.Therefore having studied Mgo whether has in conjunction with the ability of remaining moisture content and thereby can use it to replace kieserite.Carried out some test, with 1% slight baked Mgo in small, broken bits and K ₂So ₄Add to together in synthetic nitrogen/phosphorus solution (NP-solution).The particle that makes from this solution has stored for some time and carried out relevant volume increases (expansion) test.Find that then adding MgO has extraordinary effect.This is likely because MgO and NP-solution reaction generate Mg(N ₃) ₂And trimagnesium phosphate (possible MgHPO ₄).Thereby good effect arranged all it so happened that.It is the ability of crystal water in conjunction with several mole of water that above-mentioned these salt have each molar salt.This effect is determined with the direct equilibrium pressure of measuring on product.Measurement points out that water vapour pressure reduces by half when adding 1.6%MgO.When also having observed MgO, in NH ₄NO ₃Water reduces in conjunction with rendeing a service in the conversion process.Be surprisingly found out that,, when sample contains 1.6%Mgo, obtain lower absorption speed although water vapour pressure is lower.

As Mgo and KCl/K ₂So ₄Some different reactions may take place when adding NP-solution together.

Following reaction may take place:

A), phosphoric acid salt

B), nitrate

C), muriate

All these magnesium compounds are combined into crystal water with water.

Above mentioned preliminary study result can be sure of that the contriver finds.Further research interpolation MgO is correct to the effect that rule of thumb may occur being produced in the fertilizer of storage problem.Also studied in process of production and should how to have added MgO.Where adds MgO.These studies show that, when using KCl and K ₂SO ₄During as the potassium source, just can obtain storing and all stable NPK-fertilizer that expands as long as add the MgO of q.s during manufacture.Adding 0.2%(weight) MgO has just obtained positive effect.Also find 1-2%(weight) add-on is only, reaches 3%(weight but can use) MgO.The contriver also obtains to make the whole suitable Production Flow Chart of this product.

Feature of the present invention is as defined in the claim.

The present invention can further be explained in the following embodiments.

Embodiment 1

Provide the comprehensive test result who makes NPK-14-4-17 in the present embodiment, use K here ₂SO ₄Do the potassium source.This fertilizer also should contain 1% Mg, and this Mg is with kieserite (MgSO ₄) add.Test is at first carried out under the MgO additive not having.To obtain with reference to sample.Add 0.6% Mgo then, and add 1% Mgo subsequently.According to the amount of the Mgo that adds, (is benchmark by Mg), the amount of minimizing kieserite.About 0.6 kilogram/liter of the loose material unit weight of the MgO that uses, its degree is distributed as: 2-6mm=0-30%, 0.5-2mm=40-70%, less than 0.5mm=20-40%.Before they are sent into blender, with MgO and K ₂SO ₄Add together with kieserite and mix with spissated NP-solution.In process of the test, get swell test and sample for chemical analysis.Test-results is listed in the table I.

The table I

MgO content after 2 days in 60 ℃ after following 2 days under 60 ℃

Sample %(weight) %NH that turgidity has transformed ₄NO ₃

1????0????100.0????65.2

2????0.6????43.6????51.8

3????1.0????39.4????45.8

4????0????101.0????64.7

Sample 1 and 4 does not contain MgO, and sample 2 and 3 respectively contains 0.6% and 1%MgO.

Swell test result under 60 ℃ and NH ₄NO ₃Degree of conversion list in the table I, from the table I as can be seen MgO provided gratifying effect.60 ℃ of results after following 2 days show that volume that the sample that do not contain MgO increases is the twice that contains the volume that the sample of MgO increases.

Embodiment 2

Present embodiment provides the comprehensive test result who makes NPK25-3-6, uses KCL to do the potassium source here.Test is at first carried out under the MgO additive not having, and subsequently toward NP-solution, direct adding 1.6%MgO in the blender of KCl and MgO is subsequently with mixture pelleting.Make product has been measured in the granule bulk storage after 25 days pH value, also measuring its water vapour pressure " PH ₂O ".Its result provides in the table II.

The table II

Sample %MgO " PH ₂O " (millibar), 24 ℃

1????0????10.1

2????0????8.9

3????0????8.2

4????1.6????4.7

5????1.6????5.3

6????1.6????4.9

The table II clearly illustrates that MgO has very strong water in conjunction with effectiveness, thereby and has a lower water vapour pressure " PH ₂O ".

Contain and do not contain fertilizer " PH after storing 25 days of MgO ₂O " be respectively 4.7 millibars and 9.8 millibars.

" PH ₂O " be in fertilizer a kind of water in conjunction with the expression symbol.In general, think that lower " PH is arranged ₂O " thus the absorption speed of fertilizer and its caking trend be maximum.Yet be surprisingly found out that and contain 1.6%MgO and low " PH ₂O " fertilizer of value is littler than the water absorbability of the fertilizer that does not contain MgO.Can explain like this that MgO and water generate a kind of film Huo Tu layer on particle, thereby and reduce water-absorbent.

Under 65% relative humidity, also carried out caking test in 25 ℃.It the results are shown in the table III.Also studied the caking trend that contains and do not contain the fertilizer of MgO after 3 weeks of bulk storage.These studies show that the fertilizer that contains 1.6%MgO does not form crust and unrestricted flow, and do not contain the fertilizer sclerosis of MgO and trend towards forming crust.

The table III

Sample MgO %-H ₂O stores the caking value after 20 hours

1????0????0.36????170

2????0????0.30????90

3????0????0.33????330

4 1.6 0.47 (unrestricted flows fully)

5????1.6????0.48????126

6????1.6????0.47????80

Caking value (K) is the expression symbol of fertilizer agglomeration trend.Low caking value shows that fertilizer has low caking trend.When K=0, fertilizer is free-pouring fully, and K＜150 are considered to acceptable, when K＞300 may go wrong between the shelf lives.

As can be seen, the problem that some NPK-fertilizer exists is resolved by adding MgO, as KCL and K from embodiment ₂SO ₄During as the potassium source also is like this.The amount of required MgO is different, and how much it depends on the type of the NPK-fertilizer of being discussed, but studies show that further adding 0.2-3.0%MgO is just enough.When considering various condition, find to add 1-2%MgO and obtain best result.Further, should use the MgO of slight roasting type in small, broken bits better.

It is not critical where adding MgO in the production process.But must after with mineral acid acidifying phosphoric acid salt, add.Find that also MgO should just add better before granulation or granulating.Carry out adding better in the blended blender at NP-solution and interpolation salt.

Claims

1, with KC1 and/or K ₂SO ₄Reduce as having of making of potassium source that lay up period expands and the particulate state or the globular NPK-fertilizer of caking trend, it is characterized in that it contain during manufacture with balling-up before or before the granulating or during 0.2～3.0% the magnesium (with MgO) that in product, adds in the MgO form.

2, according to claim 1 particle or globular NPK-fertilizer, the MgO that it is characterized in that adding in the product is slight baked MgO.

3, make having of claim 1～2 reduce expand and caking trend contain KCl and/or K ₂SO ₄The method of NPK-fertilizer, the manufacturing processed of fertilizer is in this method: with mineral acid acidifying phosphoric acid salt, remove calcium salt then, evaporation and balling-up or granulating is characterized in that before balling-up or before the granulating/0.2～3.0% reactive MgO and sylvite are added in the solution that evaporated during the granulating.

4, according to the method for claim 3, it is characterized in that the MgO that adds is slight baked MgO, its size-grade distribution is: 2-6mm, 0-30%; 0.5-2mm, 40-70%; Less than 0.5mm, 20-40%.