CS273942B1 - Method of microelement long-term acting fertilizers preparation with manganese, zinc, copper, iron, cobalt and nickel content - Google Patents

Abstract

The invention involves a method of preparation of microelement fertilisers, based on multi-component tetraphosphates with cyclic anions, which are not easily soluble so they can freely release microelements for a period of up to five years. The method is based on the calcination of metallic iron and manganese, zinc, copper, cobalt and nickel oxides, hydroxides, carbonates or hydroxide-carbonates together with the same compounds of magnesium or calcium, in a mixture with phosphoric acid and ratio of all cations to phosphoric oxide of 0.90 to 0.99. The mixture is calcinated at a rate of 1 to 10 degrees C/minute to a temperature of 220 to 395 degrees C, and the vapour pressure in the calcination chamber is at least than 60 kPa. The product can easily be ground to powder. The invention can be used in phosphate technology and in production of agricultural chemicals.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of micro-element long-acting fertilizers containing manganese, zinc, copper, iron, cobalt and nickel.

For example, various simple salts of 3 elemental metal cations have been proposed as micro-element fertilizers. However, these compounds are usually well soluble, so that their application creates a risk of overdose and their action is only short-lived. Various complex compounds of organic character containing micro-elements have a long-term effect; however, they are usually more expensive substances with more complex synthesis.

Also known are siliceous frits, which are also capable of long-term exposure, »

but their preparation is very demanding from the energy and construction point of view (preparation of silicate melt at high temperatures, grinding of glassy product). Cs. No. 190,753 discloses a process for preparing trace fertilizers based on condensed phosphates. These fertilizers have a number of advantages over the previous ones. They are trace (microelement) fertilizers without ballast, their effectiveness can be long-term, there is no danger of their overdose, from the hygienic and ecological point of view they are practically problem-free, they can be used as an additive to all kinds of solid (powder) fertilizers. A process for the preparation of this type of trace fertilizers, proposed in the above-mentioned MS. however, it is energy-intensive because it requires calcination at temperatures of 400 to 1300 ° C followed by tempering at 350 to 900 ° C; most of the time, during the calcination, the intermediate product enters the aggressive melt phase, which in turn brings the constructional complexity of the equipment used, as well as the grinding of the product after tempering because it is in the form of a relatively hard compact mass. Use of trace fertilizers prepared according to the mentioned MS. The author's certificate for liquid fertilizers is also problematic in some cases.

These drawbacks are overcome by a process for the preparation of long-acting micro-element fertilizers containing manganese, zinc, copper, iron, cobalt and nickel, characterized in that from oxides, hydroxides, hydroxide-carbonates and / or manganese, zinc, copper, cobalt and / or nickel and / or metallic iron, optionally together with such an amount of oxides, hydroxides, hydroxide-carbonates and / or magnesium and / or calcium carbonates, is prepared by adding phosphoric acid with a molar ratio of cation sum to phosphorus pentoxide of 0.90 to 0.99 preferably allowed to react for at least 3 hours, preferably under agitation, in the case of the use of metallic iron under a shut-off ensuring a gradual and safe evacuation of the released hydrogen while preventing the formation of oxygen (air) into the mixture space. C / min the temperature range is 220 to 395 ° C, with a water vapor pressure of 60 to 100 kPa in the calcination space.

The ratio of manganese, zinc, copper, iron, cobalt, nickel and magnesium or calcium compounds in the starting mixture is chosen according to the requirement for their obeah in the product. Obeah of magnesium and calcium cations can range from zero to one, product formation with the desired anion is guaranteed. The amount of phosphoric acid in the starting mixture corresponds to the end product being, from a chemical point of view, a multi-component condensed phosphate with a cyclic tetraphosphate anion. It only dissolves slowly in aqueous solutions of dilute acids and bases, so it ensures long-term action of microelement fertilizer in the soil (about five years). The concentration of phosphoric acid is more advantageous in terms of controlling the condensation reactions and hence the yield and purity of the product; its calcination then presents technical problems. Allowing the mixture containing phosphate, manganese, zinc, ferrous, cobalt, nickel, magnesium or calcium ions to react spontaneously for at least 3 hours is advantageous for sufficient initial reaction of the microelemented metal compounds and compounds

CS 273942 B1 of magnesium or calcium with phosphoric acid, that is a neutralization reaction using hydroxides or, in particular, a decomposition reaction of carbonates, since the released carbon dioxide and the resulting loosening of the mixture would complicate the calcination itself. For this reason, stirring of the reacting starting mixture is also advantageous. When using metallic iron, the reactive mixture must be under a seal which allows safe removal of hydrogen (occurring in addition to the reaction of iron with acid), but at the same time prevents the formation of oxygen-containing air into the mixture space. undesirable triple-mono state and thus only passed into a divalent state (this task can also accomplish the conducting of inert gas into the space of the reacting mixture). The heating of the mixture at a rate of 1 to 10 ° C / min is chosen so that the individual dehydration and condensation reactions occurring successively in the mixture can take place at the temperatures at which they occur and at the highest yield. When selecting a very low heating rate, a disproportionate increase in product preparation time and thus a certain increase in material and energy requirements is to be expected. In addition, it will be more difficult in this case to maintain sufficient water vapor pressure in the calcined mixture space, thereby preventing possible cleavage of the intermediates. The lower limit of calcineo temperature (220 ° C) required is the temperature of the gradual formation of the first particles of the desired products. The upper limit of this preferred temperature region (395 ° C) is then determined by the fact that at this temperature the desired product formation reactions have already taken place (if advantageous heating rates have been used), even at higher water vapor pressures in the calcinae space. Maintaining a water vapor pressure in the space of the calcined mixture greater than 60 kPa is necessary to produce truly multi-component (cationically) condensation products. The water vapor present slows down the condensation reaction somewhat, but allows it to be more quantitative and also prevents the formation of undesired non-porous crust on the surface of the calcined mixture particles, which would prevent the quantitative course of the dehydration reactions. The upper limit for the water vapor pressure in the space of the calcined mixture - 100 kPa - is mainly due to the need for increased design, material and energy requirements for the calcination plant and calcineo line, at higher pressures than atmospheric pressure. Moreover, increased braking of the condensation and dehydration reactions due to a water vapor pressure above 100 kPa would again disproportionately prolong the product preparation time.

After cooling, the calcate is optionally comminuted to a final product with a fineness below 0.1 mm. Due to the semi-loose to loose nature of the calcine, this comminution is a relatively easy matter. The finished product of this fineness can then be added to solid micro-fertilizers, for example in the form of a powder for powdering their granules, or into liquid Buspension fertilizers, or it can be processed into a separate microelement fertilizer with various suitable particle characteristics (granules, lozenges and the like) .

The advantages of the method according to the invention are as follows:

- enables preparation of micro-element fertilizers, which are self-adhesive, because their anionic component is also useful by plants}

- after application of the fertilizer to the soil, very slowly hydrolytic cleavage of the tetraphosphate anions occurs and thus dissolves, and since this process is very slow, their action is long-lasting (about five years) and, since hydrolysis is temperature-dependent, monitors dissolution of these microelement fertilizers to some extent also the course of vegetation of most plants} moreover, the multi-membered phosphoric anions released by hydrolysis promote good mobility and thus the accessibility of microelements to plants}

- because of their difficult solubility they can be used as a source of microelements in liquid suspension fertilizers and for the same reason they can be used for stock fertilization without the risk of overdose.

- energetic (thermal) and material-design conditions of preparation of microelement fertilizers are available to potential manufacturers} <Γ

CS 273942 Bl

- the final comminution of the product is technologically easy to operate due to its consistency.

Example 1

300 g manganese carbonate (containing 48% Μη), 100 g zinc carbonate (51% Zn), 30 g copper hydroxide (57% Cu), 100 g magnesium carbonate (29% Mg) and 100 g calcium carbonate (40 % Ca) was mixed with 1930 g of phosphoric acid concentration of 45 weight% H P0 ^ _g and left with occasional stirring for 3 h to react spontaneously. Thereafter, the mixture was heated at a rate of 2 ° C / min to 390 ° C for 4 hours at this temperature. The water vapor pressure was maintained at 75 kPa in the calcined mixture. 885 g of product were obtained, which was ground to a fineness below 1 mm and represented a micro-element fertilizer with a content (mol%):

23.6% MnO, 7.3% ZnO, 2.5% CuO, 35 * 8% MgO, 25.8% CaO and 50% P ₂ 0 _g.

Example 2

200 g of manganese oxide (containing 77% Mn), 100 g of zinc hydroxide slurry (30.6% Zn), 20 g of copper oxide (79% Cu), 70 g of magnesium hydroxide slurry (24% Mg) and 50 g of calcium hydroxide slurry ( 27% Ca) was mixed with 859 g of phosphoric acid by weight concentration of 80% H PO ^ _g and left with occasional stirring for 6 hours to react freely. Thereafter, the mixture was heated at a rate of 5 ° C / min to 380 ° C for 3 hours at this temperature. The water vapor pressure was maintained at 85 kPa in the area of the calcined mixture. 714 g of the product as a micro-element fertilizer with a content (mole%) were obtained:

31.9% MnO, 5.51% ZnO, 2.93% CuO, 6.13% MgO, 3.53% CaO and 50% P ₂ 0 _g.

Example 3

100 g iron powder (containing 99.9% Fe) »20 g cobalt carbonate (49% Co), 10 g nickel hydroxide carbonate (56% Ni), 50 g magnesium carbonate (29 g Mg) and 100 g calcium carbonate (40 % Ca) was mixed with 1,326 g of phosphoric acid at a concentration of 55% by weight ^and allowed to react spontaneously under a hydraulic water seal for 8 hours with occasional stirring. The mixture was then heated at a rate of 2 ° C / min to 395 ° C, with a holding time of 5 h at this temperature. The water vapor pressure in the space of the calcined mixture was maintained at 90 kPa. 790 g of product were obtained, which was ground to a fineness below 1 mm and represented a micro-element fertilizer containing (mol%):

5.24% PEO, 2.3% CoO, 1.3% NiO, 8.2% MgO, 13.7% CaO and 50% P ₂ 0 _g.

Example 4

200 g of iron powder (containing 99.9% Pe), 10 g of cobalt hydroxide carbonate (57% Co), 5 g of nickel carbonate (48% Ni), 90 g of magnesium hydroxide slurry (24% Mg) and 70 g of calcium hydroxide slurry (27% Ca) was mixed with 12.71 g of phosphoric acid concentration of 80 weight% H P0 ^ _g and left with occasional stirring for 12 h freely react with gentle stream of nitrogen, into the reacting mixture. The mixture was then heated at a rate of 5 ° C / min to 390 ° C for 6 hours at this temperature. The water vapor pressure was maintained at 95 kPa in the area of the calcined mixture. 1080 g of the product as a micro-element fertilizer were obtained and contained (mol,%):

35.2% PEO 1% CoO, 0.4% NiO, 8.8% MgO, 4.6% CaO and 50% P ₂ 0 _g.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of micro-element long-acting fertilizers containing manganese, zinc, copper, iron, cobalt and nickel, characterized in that from oxides, hydroxides, hydroxides and / or carbonates of manganese, zinc, copper, cobalt and / or nickel; and / or with iron oxides, hydroxides, hydroxides, carbonates and / or magnesium and / or calcium carbonates, a mixture having a molar ratio of cation sum to phosphorus pentoxide of 0.90 to 0.99 is prepared by stirring for at least 3 hours. and then heated at a rate of 1 to 10 ° C / min, to a temperature in the range of 220 to 395 ° C, with a water vapor pressure of 60 to 100 kPa in the calcination space.