DE4008763A1 - Urea-potassium fertiliser complex prepn. - by heating mixt. of urea, potassium chloride, ammonium sulphate and water in two stages, cooling and comminuting - Google Patents

Abstract

The prepn. of an urea-potassium complex (I) for fertilising plants comprises briefly heating urea, potassium chloride and ammonium sulphate in aq. suspension to a temp. of 120-130 deg. C with substantial evapn. of the water and then heating briefly to 130-150 deg.C so the three solids react to form a binary urea-potassium complex, which is then rapidly cooled and comminuted.

Description

The present invention relates to the production of a plant zen fertilizer from the feedstocks urea U = CO (NH₂) ₂, Potassium chloride KCl and ammonium sulfate (NH₄) ₂SO₄ in aqueous Sus Pension at about 80 to 150 ° C, evaporation of essential water Quantity and cooling - if necessary with grain-forming - to egg a glassy-hard end product. In this complex with the recipe tur scheme, for example

2 U + 2 KCl + (NH₄) ₂SO₄ = 2 NH₄Cl.U + K₂SO₄ (1)

all of the feedstocks are consumed except for traces of KCl, but two new unknown types of crystals have formed, which may possibly also be mixed-crystal phases in the case of non-quantitative partial conversion ( 1 ).

Essential, however, is the mineralogical-optical detection of the consumption of the starting materials to a complex and its now several properties. During cooling, the almost anhydrous complex mixture is readily formable up to about 90 ° C .; technically granulating or prilling (spraying) is possible here and under Umstän the compacting conceivable; cooled, the glassy-hard product is aufmahlbar to the desired grain size. Because of the softening range during cooling are compared to the scheme ( 1 ) over shot inserts of potassium chloride, for example, to 4 moles of KCl or ammonium sulfate to 3 moles possible; Here then remain in the final product surpluses of free potassium chloride or ammonium sulfate. Surpluses of urea over ( 1 ) are technically easy to implement, they are not quite indicated for application reasons, which will be discussed later.

As a singular fertilizer, potash is essentially called chloride used, besides, the somewhat less soluble sulfate; in terms of The grain form of these salts are coarser products only right up manoeuvrable and therefore less common than the fei  ner crystallized. There is coarser grained fertilizer always application-induced a market need, to whose Satisfaction contributes to this invention. Another progress in the proposed complex there is an easy replacement soluble KCl through a less soluble phase, such as wise the sulfate, which for economic-ecological reasons he wishes.

The urea-N-potassium complex is also different from others binary NK fertilizers a step forward. The market enthal usually nitrates, which are less accepted today. The NPK fertilizers, which are widely represented in the market, are included usually ammonium nitrate and are therefore verschwelbar. A Combination N and K has also become known with calcium cyanamide the latter is physiologically not unsuspicious. The before beaten combination potash with urea is neither smoldering still physiologically questionable.

The pure urea is highly active in tropical soils Biomass as a plant fertilizer quite successful. In temperate Kli In the meantime, ma zones lead to urea - with its by the way konkur Highly concentrated N-content solid fertilizer with 46% by weight N - easy to handle Primary plant damage, over-fertilization as well as undesirable leaching; that's why in the past, for example wise ammonnitrate fertilizer well enforced. Meanwhile konn Especially in horticulture technically complicated to produce and therefore expensive condensates of urea with aldehydes good Gain market importance, the braked N-long-term effect respectively. The urea-potassium Complex contains similar to the latter urea-aldehyde Condensates no free - and thus undesirable - urea son this as probably urea-ammonia or as a mixed Kri stall phase, which is why a desired delayed N-We kung this urea adduct is favored. The comparisons expensive and expensive aldehydes to be processed into fertilizer Urea condensates are dispensable here; a lot of cheap Res ammonium sulfate containing 21 wt .-% ammonium N to N balance in Contributes product is, so to speak "added instead".

example

60 g urea, 46% by weight N; Grain size ⌀ 1 mm,
10.4 g of water
66 g of ammonium sulfate, 20.8% N; Grain finer than 0.05 mm
74.5 g of potassium chloride, pure about 63.0 K₂O; Grain finer than 0.5 mm

are mixed and kneaded in a VA stainless steel casserole,
quickly heated to 142 ° C in 3 minutes (the Suspen sion mushy at 90 ° and at 110 ° homogeneous begins to boil),
held at 145 ° ± 3 ° C in a further 5 minutes with still slight evaporation of water (approximate dehydration is controlled by weighing the hot casserole with content kontrol profiled); Ammonia is not released.

There remain 202.0 g of melt (with 1.5 g of residual water), this is cooled by pouring on a cold plate, it is solid at 90 ° and solidifies as glassy, very firm Mass, which is subsequently to a desired particle size of 1.5 to 4 mm is broken and a very fine mixed Fraction for further investigations.

The subsequent investigation of the finest fraction with Refraction liquids under the polarization microscope revealed two non-cubic crystal types with refractive indices between 1,527 and 1,521 (small bars, smaller quantities) and Aggregates with refractive indices between 1.521 and 1.517 (larger Amount). These types of crystals can not be stoichiometrically bi be assigned to a salt. The starting materials - except Traces KCl - are no longer visually detectable. Moegli Of course, mixed crystals are present on the product crystal habit now involved.

The final product has arithmetically 0.75 wt .-% residual H₂O and

13.65% N-urea  6.8 N-NH₄ 20.45% Total N

and 23.2% K₂O.  

With technical reasons somewhat lower K₂O contents of the Ka Of course, liumchlorides are slightly different end product levels expectable. Fast heating up and processing is a mistake formation of undesirable biuret formation (together with ammonia release) displayed from the urea. It is also appropriate that besides the urea which first dissolved, the other reactants KCl is finer than 0.5 mm and (NH₄) ₂SO₄ finer than 0.05 mm should be. Waste or dust is here helpful. Because of the entire softening range 140 to 90 ° C the complex-use formula from (in moles)

2 U (urea) +2 KCl + (NH₄) ₂SO₄ (1)

are alternatively mitformbar until further 4 KCl or until further 3 (NH₄) ₂SO₄, which is done for example by granulation or compacting.

Claims (6)

1. A process for preparing a urea-potassium complex for plant fertilization, characterized in that urea, potassium chloride and ammonium sulfate in aqueous Sus pension under substantial evaporation of the water briefly heated to 120 to 130 ° C and briefly at 130 to 150 ° C with consumption implemented the three solid feedstocks to a binary urea-potassium complex, rapidly cooled and zer kleinert. 2. The method according to claim 1, characterized in that a mixture of 2 moles of urea, 2 moles of potassium chloride, 1 mol of ammonium sulfate and 1 to 1.3 moles of water used become. 3. Process according to Claims 1 and 2, characterized in that fine-grained potassium chloride with less than 0.5 mm grain size and fine-grained ammonium sulfate finer than 0.05 mm Grain be used. 4. Method according to the preceding claims, characterized in that
the heating-dissolving phase is preferably less than three minutes and the subsequent reaction phase is preferably less than five minutes. 5. Method according to the preceding claims, characterized in that
in the preparation of the melt or, preferably, during the cooling thereof, alternatively, up to 4 mol of potassium chloride or further up to 3 mol of ammonium sulfate may be added. 6. Method according to the preceding claims, characterized in that
starting with the reaction phase but at the latest in the cooling phase from Ab - optionally with further addition of potassium chloride or ammonium sulfate - the products of a grain shaping example by granulating or compacting be subjected to.