CS231894B1 - Preparation method of powder mixture of inert substance and urea nitrate - Google Patents

Abstract

The object of the invention was to shorten the reaction time nitric acid with urea in the presence inert powdery substances. The aim was achieved by the method of the invention, when the powder is inert to the mixture the urea adds acid to the blend nitric acid at a concentration of 50 to 85% at temperature of 75 to 110 C, with constant drainage leaking water vapor.

Description

The invention relates to a process for the preparation of a mixture of a pulverulent inert substance and a urea nitrate by reacting urea with nitric acid in the presence of the inert pulverulent substance.

The production of urea nitrate in dry powder form in a mixture with a pulverulent inert substance is based on high nitric acid (96 to 100%), urea and pulverulent inert substances such as ground quartz sand, ground feldspar, etc.

The process is such that urea is mixed with an inert material in the reactor and nitric acid (96-100%) is added under stirring and cooling with water (flowing through the space between the jacket and the reactor body) to maintain the temperature of the reaction mixture at 90 ° C.

Since the urea nitrate preparation reaction is highly exothermic, it is a significant amount of heat. In addition, the direct contact of urea with nitric acid at the indicated concentration has a negative effect, since due to local overheating, partial decomposition of the formed or already formed urea nitrate occurs.

If the reaction temperature exceeds 95 ° C, the reaction mixture is usually no longer able to cool and the total decomposition of the urea nitrate and the unreacted urea takes place in the entire mass of the inert substance.

The rate of reaction heat removal (cooling) depends on the reaction, which is still feasible for small reactors (up to 0.1 m ² ), where the ratio between the

2 of the reactor (in m) and the surface of the reactor surface to be cooled (m).

As the reactor content increases, this ratio increases, which is a phenomenon unfavorable for cooling. This results in a deteriorated heat dissipation, a prolonged reaction time, and consequently a decrease in reactor production capacity.

Therefore, the preparation according to this known process can become economically unbearable for large reactors.

The above disadvantages are avoided by the process of preparing a mixture of a powdered inert substance such as ground quartz sand, ground feldspar and nitric urea. The process consists in adding to the mixture of the inert pulverulent material and urea 50 to 85% nitric acid at a temperature of 75 to 110 ° C with stirring, while continuously evolving water vapors out of the reaction space at a pressure of 10 to 120 kPa.

We have found that a low concentration of 50-85% nitric acid can be used to prepare the dry pulverulent urea nitrate in admixture with the pulverulent inert substance, or an adequate amount of water can be added to the reactor provided the generated water vapor is discharged off the reactor.

Extraction can be carried out by natural spontaneous extraction or by means of vacuum. Due to the high value of the evaporation heat of the water, intensive cooling in the reactor in the whole mass (with stirring) occurs.

We have even found that there is no local overheating and decomposition, even at temperatures above 100 ° C. The high reaction temperature and the water vapor removal do not allow the formation of a low-quality wet product and the reaction time is comparable to small reactors.

The composition prepared according to the invention can be used as a catalyst for the curing of furan resins. \

Example 1

600 kg of ground quartz sand and 100 kg of urea were charged to a 1 m ³ reactor. While stirring and naturally extracting water vapor, 160 kg of 65% nitric acid was added from the measuring cup so that the temperature did not exceed 90 ° C.

The reaction time was 3 hours. It decreased by 10 hours compared to the original method.

Example 2

300 kg of ground quartz sand and 50 kg of urea were charged to a 0.5 m ³ reactor. While stirring under vacuum, 80 kg of 65% nitric acid was added from the measuring cup so that the temperature did not exceed 90 ° C.

The reaction time was 11 1/2 hours. It decreased by 3 hours compared to the original method.

Example 3

600 kg of ground feldspar and 100 kg of urea were charged to a 1 m ³ reactor. While stirring under vacuum, 160 kg of 65% nitric acid was added such that the temperature did not exceed 105 ° C.

The reaction time was 11/5 hours. It decreased by 12 hours compared to the original method.

Example 4

A 1 m ³ reactor was charged with 600 kg of ground quartz sand and 100 kg of urine. guilt. While stirring under vacuum, 100 kg of 96% nitric acid and 60 kg of water were added alternately so that the temperature of the reaction mixture did not exceed 90 ° C.

The reaction time was 31/4 hours. It decreased by 9 3/4 hours compared to the original method.

Claims (1)

OBJECT OF CLIMBING A process for the preparation of a dry powder mixture of urea nitrate and an inert powder such as ground quartz sand or ground feldspar by reacting urea with nitric acid in the presence of the inert powdered substance, characterized in that 50 to 85% at a temperature of 75 to 110 ° C with continuous evacuation of the resulting water vapor outside the reaction space at a pressure of 10 to 120 kPa.