SK191492A3 - Corrosion inhibitor for liquid nitrogeneous feltilizer - Google Patents

Abstract

Corrosion inhibitor for nitrogenous liquid fertilizers contains 10% to 40% by weight of sodium granulate, 5% to 20% by weight of sodium tetraborate, 1% to 5% by weight of sodium molybdate and 25% to 83% by weight of water. Corrosion inhibitor For nitrogenous liquid fertilizers is added to of this type of fertilizer in a concentration of 250 gt-1 to 1500 gt-i.

Description

The invention relates to a method for inhibiting the corrosive aggressiveness of nitrogenous liquid fertilizers towards metallic materials.

One of the serious problems of the production and use of liquid nitrogen fertilizers is the issue of corrosion of production, storage, transport and application equipment.

Aqueous solutions containing urea and ammonium nitrate with a total content of 28 to 32% by weight. Nitrogen at a properly adjusted pH do not have a corrosive effect on most aluminum alloys, stainless steel as well as on most plastics used today (PVC, PE, PP, fiberglass, etc.)

On the other hand, they exhibit considerable corrosion to carbon steels and non-ferrous metals, especially if they do not contain any of the corrosion inhibitors and if their pH is less than 7.

Consequently, the use of liquid, non-pressurized nitrogen fertilizers based on urea and ammonium nitrate or magnesium nitrate without proper treatment aimed at reducing their corrosive aggressiveness towards said metallic materials would encounter difficulties, especially in the post-production process (storage, handling and application).

To date, a number of inorganic and organic substances have been used as corrosion inhibitors in this type of liquid fertilizer. Of these, the most commonly mentioned are the use of ammonia, potassium or ammonium thiocyanate, sodium sulfide, polyphosphates, phosphates, arsenitams, ligninsulfonic acid and others.

One simple way to reduce the corrosive aggressiveness of liquid nitrogen fertilizers in current practice is by treating with ammonia. It is added in an amount such that the pH of the treated solution is 7 to 7.5.

This method of inhibiting the corrosive aggressiveness of nitrogenous liquid fertilizers is in many cases preferred for its simplicity and economic advantage. However, it has certain disadvantages, e.g. the effectiveness of the corrosion protection of carbon steels in this way is relatively low, but does not at all address the protection of non-ferrous metals and their alloys.

- 2

With a high content of free ammonia (pH of the nitrogen solution higher than 8) good corrosion protection of carbon steels is achieved, but the conditions of work hygiene deteriorate, the corrosive aggressiveness of the fertilizer towards non-ferrous metals and their alloys (copper, bronze brass etc.) against aluminum due to the formation of water-soluble amocomplexes and bicarbonates.

The corrosion protection of carbon steels decreases due to the gradual decrease of ammonia content in the product, handling, temperature changes and long-term storage, resulting in not quite negligible nitrogen losses, while worsening work safety conditions (possible explosive NH4-air mixture) ). The free ammonia content affects the hygroscopic properties of the product (salting-out temperature, unstable region width). In order to comply with the prescribed free ammonia in the fertilizer (maximum content usually 0.1%

Musíme ^) we must often remove its excess in the production process (eg by desorption, aeration, neutralization, etc.) ·

In view of these disadvantages, the shortcomings of a number of major world producers of liquid nitrogen fertilizers have been withdrawing recently from the use of ammonia to inhibit the corrosive action of these fertilizers.

The inhibitors used to date provide sufficient corrosion inhibition below the level of the liquid fertilizer, but there is a strong corrosion attack at the liquid-metal interface - local corrosion. Also, the protection of noble metals is insufficient.

To a certain extent, the corrosion irritator for the liquid nitrogen fertilizers according to the invention, which consists of 10 to 40% by weight, removes the shortcomings of the state of the art. sodium gluconate, 5 to 20% by weight. sodium tetraborate, 1-10% by weight. % zinc chloride, 1 to 5 wt.%. sodium molybdate and 25 to 83% by weight of water.

Said corrosion inhibitor for nitrogenous liquid fertilizer is added at a concentration of 250 to 1500 grams per tonne. In addition to its corrosive inhibitory action, this infiibler is used as trace elements (Β, Ζη, Μο) after the application of nitrogenous liquid fertilizers in plant nutrition, thereby confirming its ecological safety.

The invention and its effectiveness are explained in more detail by the description in the examples.

Example 1

Under the laboratory conditions, the efficacy of the corrosion inhibitor of the invention (30% by weight, sodium gluconate, 15% by weight, sodium tetraborate, 5% by weight, zinc chloride, 3% by weight, sodium molybdate and 47% by weight water) was investigated in static tests. , in a nitrogenous solution of DAM-390

(composed of: 32.3 wt% urea, 42.9 wt% ammonium nitrate 0.1 wt% NHp 0.1 wt% COg, 0.2 wt% biuret and 24.4 wt% water ). Specification of corrosive environment tested speed at about 30 ° 0 material corrosion (mm. r '' * ’) DAM-390 without addition of inhibitor CSN 11 373 .7310 corrosion, pH initial 7.97, 1200 hours Exposure, 7.68 . <> · DAM-390 with the addition of 250 mg.kg &quot; corrosion, pH 11SH 11 373 0.0040 Initial 7.90, 1200 hrs. exposure, 6.01 DAM-390 without addition of inhib. corrosion, pH initial Brass .1910

7.60, 336 h, 6.72

DAM-390 with addition of 250 mg.kg -1. Brass of said corrosion inhibitor, pH initial 7.58, 335 hr. exposure, 6.76

0.0925

Example 2

Under similar static test conditions, the corrosion inhibitor activity of composition 1 was investigated in a DAM-390 nitrogen containing MgO solution (composition: 35.64 wt% ammonium nitrate, 30.17 wt% urea, 7.43 wt%). magnesium nitrate, 0.70% calcium nitrate and 26.05% water)

Specification of corrosive environment Tested Speed at approx. 30 ° C Corrosion material (mm.r “ ¹ )

DAM-390 with MgO without addition of corrosion inhibitor, pH initial 7.12,

Exposure _A _6 _x 54 _____________ ČSN 11 373 ___ 0,1073

DAM-390 with MgO with addition of a corrosion inhibitor 1000 mg.kg-1 pH initial 8.05, 1200 hr. exposure, 6.36 ČSN 11 373 0.001

DAM-390 with MgO without addition of corrosion inhibitor, pH initial, 7.36,

335 hours exposure, 5.89 Moéadz 0.1910

DAM-390 with MgO with addition of corrosion inhibitor, 1000 mg.kg, pH initial 7.32, 335 hr. exposure

5.49 Brass 0.0560

The corrosion inhibitor for nitrogenous liquid fertilizers according to the formulation in Example 1 is a yellow to yellow-brown liquid with good corrosion-inhibiting activity on steel and brass.

Claims (1)

Claims: The corrosion inhibitor for nitrogenous liquid fertilizers is characterized in that it contains from 10 to 40% by weight. sodium gluconate, 5 to 20% by weight. sodium tetraborate, 1-10% by weight. zinc chloride, 1 to 5% hinot. sodium molybdate and 25 to 83% water.