DE2263334B2 - PROCESS FOR MANUFACTURING GRANULATED PK MANIFOLD FROM THOMASPHOSPHATE AND KALIDUENALZ - Google Patents

Description

To supply the soils and plants with phosphoric acid and potash, PK fertilizers are increasingly being used. Thomas phosphate has proven to be _{a particularly suitable P 2} O ₅ form, since this is easily absorbed by the plant roots _{as citric acid-soluble P 2} O _5.

According to Gericke (Analytical Chemistry of Fertilizers, Enke-Verlag, 1949, p. 28), Thomas phosphate contains 15 to 20% citric acid-soluble P _? O ₅ . With these P ₂ O ₅ contents, commercial products with 10% citric acid-soluble P ₂ O ₅ and 20% K ₂ O z. B. from chloride potash fertilizer salt. A granulate of the brand 10/20 has the following composition according to DT-PS 973396:

5.75 t Thomas phosphate (15.6% P ₂ O ₅ )
3.31 t potassium chloride (54.4% K ₂ O)

40

with a grain size of 0.5 to 4 mm.

These granules were produced by built-up granulation after moistening with 8 to 12% water.

If the soil has a good P ₂ O ₅ supply, a narrowing of the P ₂ O ₅ : K ₂ O ratio is important in practice

This ratio of z. B. P ₂ O ₅ : K ₂ O = 12:18 cannot be adjusted to 58 to 60% K _{2 O by increasing the K 2 O content.} So z. B. a mixture ■ us 35 parts by weight of potash fertilizer salt and 65 parts by weight of Thomas phosphate with 17% citric acid-soluble P ₂ O ₅ only the mark 11/20.

The German patent specification 1242 644 teaches press granulation with 2 to 4% moisture using water-soluble P ₂ O ₅ from superphosphate or triple phosphate. According to this process, water-soluble P ₂ O ₅ cannot react with Thomas phosphate because a moisture content of "2 to 4%" is set. Such fertilizers thus contain water-soluble P ₂ O ₅ , which is precisely not contained in the PK mixed fertilizer according to the invention.

The proposal of the German Auslegeschrift 17 92192 for the production of a PK fertilizer with a graduated nutrient ratio P ₂ O ₅ : K ₂ O of about 12 to 18:20 relates to reacting Thomas phosphate with triple superphosphate or with phosphoric acid in the presence of potash fertilizer salt and with water or Granulate saline solution. At a final temperature of over 90 ^° C., a residual content of water-soluble P ₂ O ₅ of less than about 0.5% by weight should be achieved by reacting the P ₂ O _{5 components.} Such PK fertilizers can also be _{adjusted with a graduated nutrient ratio P 2} O ₅ : K ₂ O of about 12 to 16:22% by weight. In such PK fertilizers, the content of free lime is saturated with water-soluble phosphates or phosphoric acid

Precise technological conditions must be observed in this process in order to achieve the low residual content of water-soluble P ₂ O ₅ . According to the method of the invention, on the other hand, a PK fertilizer is produced which does not contain any water-soluble P ₂ O ₅

The method of the invention takes a different approach to setting graded nutrient ratios P ₂ O ₅ : K ₂ O in PK fertilizers with Thomas phosphate by adding dicalcium phosphate with Thomas phosphate "with less than 16% ctrsl. P ₂ O <«is combined.

The prejudice of the technology against dicalcium phosphate lay in the uptake of water including the calcined return material. It is surprising that the return material is practically not hydrated and thus this water does not have to be evaporated.

There has now been a process for the production of granulated PK fertilizers from Thomas phosphate and potash fertilizer salt with a citric acid-soluble P ₂ O. content of over 10% with a K ₂ O content of over 12 to 24% while setting a nutrient ratio between 12:24 and 18:18 found, which is characterized in that the _{Thomas phosphate with a citric acid-soluble P 2} O ₅ content of less than 16% with dicalcium phosphate anhydrite up to dicalcium phosphate dihydrate and the potassium fertilizer salt with a K ₂ O content of 50 to 60% with the addition of return material in the form of fine material or comminuted material mixed with moistening, briefly subjected to pre-granulation, then further granulated, calcined and dried at such a temperature that the content of water of hydration in the good grain is practically zero

The moistening of the return material containing completely or partially calcined dihydrate can take place separately from the moistening of the feed material and this can only then be mixed with the moistened feed material. Pre-granulation can be carried out in 3 to 5 minutes. Thomas phosphate with a content of between about 12 to 16% _{citric acid-soluble P 2} O ₅ can be used, and dicalcium phosphate with a statistical content of 0.5 to 1.5% water of crystallization can be used

Chloride or sulphate potassium fertilizer salt with about 50 to 55% K ₂ O can be used, and dilute to practically cold-saturated solutions of inorganic salts, in particular solutions of MgCl ₃ , MgSO ₄ , Ca (NO ₃ ) ₂ or solid inorganic salts, can be used as binders such as finely ground kieserite (MgSO ₄ - H ₂ O) or calcined kieserite (MgSO ₄ ) can be used.

In addition, granulating screws or granulating plates can be used to pre-granulate the material to be mixed. The good grain can be sieved to a grain size of about 0.5 to 3.5 mm, and hydroxyapatitic rock phosphate with P ₂ O ₅ soluble in formic acid can be used as the P ₂ O ₅ component instead of a partial amount of Thomas' phosphate.

1 610 2 88 3 310 Return goods 300

The method of the invention is for example

described as follows: feed kg

Example 1 _{$ 2 1? G}

Type P ₂ O ₅ : K ₂ O = 12: 18 theme phosphate (1) with 3 310

13.2% citric acid soluble (ctls.) P ₂ O ₅ , 1018

Dicalcium Phosphate Monohydrate (2) (CaHPO ₄ H ₂ O)

with 45% citric acid soluble (ctls.) P ₂ O ₅ , the moistened mixture (1-3) is separated

Chloride potash fertilizer salt (3) with 58% K ₂ O io moistened return material of 470 kg corresponding to the

Weight ratio 1: 0.47 mixed in. The other

Starting product kg processing takes place according to example 2. In the calci- - nation, 18 kg of water of hydration are evaporated next to the granulating water

i5 To increase the yield of good grain from 0.8 to 3.5 mm, a MgSO ₄ solution, saturated at room temperature, is used as the granulating liquid in an amount of 2 percent by weight of MgSO ₄ , calculated on the granulating material.

2o det

The starting products (1-3) are with Example 4

fine and the crushed Rücklaufgut under humidification in a positive mixer (. Lödige) comparable Type P ₂ O _5: K ₂ O = 16:18 slag (1) with mixed and about 6min ctsl in a double-shaft 15.5%. P ₂ O ₅ , pre-granulated screw mixer, then in a 25% CaHPO ₄ H ₂ O (2) with 45% ctsl. P ₂ O _5, rotary kiln with direct heating further granulated, chloridisches Kalidüngesalz (3) with 60% K ₂ O and dried calcined The granules at the outlet of the dryer, a Gutstemperatur of 150 ⁰ C. "., ._," TI

There are 8 kg of hydration water in addition to the granulating Kg

water evaporates The granulate is reduced to a good 30 1 552

grain of 0.5 -3.5mm sifted the fine material with the. ,,

crushed oversized grain combined and in the task, "*

well returned ^J _300

1018

Example 2 35

The moistening and pre-granulation takes place according to

Type P ₂ O ₅ : K ₂ O = 12.5: 20 Thomas phosphate (1) with example 2, then the further granulation is carried out

13.2% ctsl. P ₂ O ₅ , a plate granulator using a

CaHPO ₄ · H ₂ O (2) with 45% ctsl. IP ₂ O ₅ , Ca (NO ₃ ) ₂ solution with about 1% Ca (NO ₃ J ₂ , to the

Chloride potash fertilizer salt (3) with 58% K ₂ O 40 nuliergut calculated, carried out in about 4 minutes

Wet granulate is then placed in a roller drum

Starting product kg " ^Ε ΐ ^0ΐ ! Γ ⁸ ,, ^ ^Aus ^ ^ute , ^further granulated and on

then in a drying drum with evaporation of 18 kg of hydration water and the granulating water 45 calcined and dried The outlet temperature is about 108 ° C. A finished granulate of 1: 3.5 mm screened off. The fine and shredded return material is after the separate humidification 1352 mixed with the feed material

50

The dry starting product (1 -3) and the cal example 5

cinierte return goods are moistened separately in the compulsory mixer, thereby the time of the pre-granulation type P ₂ O ₅ : K ₂ O = 18:18 Thomas phosphate (1) is shortened to about 3 min, then the combined up 15.5% ctsl. P ₂ O ₅ , further granulated in the rotary kiln, cal- 55 CaHPO ₄ -H ₂ O with 45% ctsl. P ₂ O _5, ciniert, while (3) next to the hydration water evaporates 12kg granulation chloridisches Kalidüngesalz with 60% K ₂ O lierwasser, dried and at 110 ⁰ C
Leaking granules to a grain size of 1 - 3.5 mm
Good grain sieved off 340 kg of returned goods are in accordance with the ratio of input goods: returned goods 60
like 1: 0.34 mixed with the feed material as fine material.

Example 3

Type P ₂ O ₅ : K ₂ O = 15:18 Thomas phosphate (1) with 65 13.2% ctsl.P ₂ O ₅ ,

CaHPO ₄ H ₂ O (2) with 45% ctsl. P ₂ O ₅ ,
Sulphatic potash salt with 58% K ₂ O (3) Ratio of feed material: return material = 1: 0.78

1 550 2 117 3 345 Return goods 340

Feed kg 1 494 2 230 3 300 1024 Return goods 780

Carrying out the method of the invention takes place according to example 2.

During the calcination, 24 kg of water of hydration are _{evaporated from the CaHPO 4} H ₂ O to 1000 kg of granulated material.

As a binder, 1% finely ground, calcined kieserite (MgSO ₄ ) is added to the mix when it is moistened with water to increase the granulate yield

The method of the invention offers the possibility of using Thomas phosphate with a content of less than 16% ctsl.r ₂ O ₅ and optionally with a partial amount of hydroxylapatitic rock phosphate with formic acid-soluble P ₂ O ₅ instead of Thomas phosphate with dicacium phosphate anhydrite with a statistical content of water of hydration up to the dihydrate without saturation of the free CaO content of Thomas phosphate in connection with fertilizer salts, an approaching nutrient ratio P ₂ O ₅ : K ₂ O between about 12:24 and 18:18 can be set, e.g. B.

12:18 (example 1) or from 18:18 (example 5).

The technological process conditions are not limited with regard to the nutrient forms

According to the method of the invention takes place with the calcined return material in the mixing miniem humidified feed material surprisingly practically no hydration with the granulating liquid instead of thorough this technical effect makes it possible to carry out the process of the invention without significant Quantities of dampening water are bound as water of hydration before granulating the mixture the substances takes place that would have to be removed again during drying.

The method of the invention thus offers the possibility of producing PK fertilizers with Thomas phosphate, including batches with low levels of ctsl. P _? To be able to process Os that previously could not be used for such PK fertilizers.

Claims (1)

Claim: Process for the production of granulated PK fertilizers from _{Thomas phosphate and potash fertilizer salt with a citric acid-soluble P 2} O _{: i} content of over 10% with a K ₂ O content of over 12 to 24% with a nutrient ratio between 12:24 and 18- 18, characterized in that the _{Thomas phosphate with a citric acid-soluble P 2} O ₅ -GeITaIt of less than 16% with dicalcium phosphate anhydrite to dicalcium phosphate dihydrate and the potassium fertilizer salt with a K ₂ O content of 50 to 60% with the addition of return material in Form of fine material or comminuted material mixed with moistening, briefly subjected to pre-granulation, then further granulated, calcined and dried at such a temperature that the content of water of hydration in the material grain is practically zero.