SU1662993A1 - Method of producing granulated phosphorus fertilizers - Google Patents

Abstract

The invention relates to the production of granular phosphate fertilizers, including superphosphates, and contributes to the intensification of the process, reducing harmful emissions into the atmosphere while maintaining the quality of the product. In the process, a suspension of phosphate raw material is fed into the reactor for decomposition by mineral acid tangentially at a speed of 0.1 - 5 m / s and decomposition is carried out at 110 - 180 ° C and a pressure of 0.5 - 6 atm. A suspension of phosphate raw material is prepared at a ratio of 1: (0.4–0.9), and either 75–98% sulfuric acid and / or phosphoric acid are used as a mineral acid. The capacity of the process line is increased from 30 to 66 tons per hour, the reduction in emissions of harmful impurities into the atmosphere is 0.025-0.016% of those introduced with the raw material, the process is simplified. 1 hp ff, 4 tab.

Description

The invention relates to the preparation of granular phosphate fertilizers, including superphosphates.

The purpose of the invention is to intensify the process and reduce harmful emissions into the atmosphere.

Example 1. 1000 kg of phosphorite is mixed with absorption solutions at a ratio of 1 0.9 and the suspension is tangentially fed into the reactor at a speed of 0.5 m / s, into which concentrated sulfuric acid (92.5%) is continuously fed in an amount of 600 kg. The temperature in the reactor is maintained at 110 ° C, the pressure in the reactor is set to 0.5 atm. The resulting mass in the amount of 2481 kg is fed to the granulator at

the retour layer, the wet granules in the amount of 5420 kg are dried in the dryer. After sieving, 1590 kg of finished product is obtained. The capacity of the line is 450 tons per hour. Into the atmosphere, harmful impurities are emitted in the amount of 0.025% of the injected ones.

PRI mme R 2. 1000 kg of phosphorite is mixed with solutions at a ratio of 0.6, the suspension is tangentially introduced into the reactor at a speed of 1.5 m / s. 650 kg of concentrated sulfuric acid is continuously fed to the reactor. The temperature in the reactor is maintained at 140 ° C, and the pressure is 2 atm. The intermediate product from the reactor in the amount of 2148 kg is fed into the granulator per layer retuo

N0

yu yu

with

pa. Wet granules 4268 kg dried in the dryer. After sieving, 1580 kg of product is obtained. The capacity of the line is 66 t / h. Harmful impurities are emitted into the atmosphere in an amount of 0.016% of those introduced with the raw material.

PRI me R 3. 100 kg of phosphorite is mixed with absorption solutions at a ratio of 1: 0.4; the suspension obtained is fed into the reactor at a speed of 0.8 m / s. Concentrated phosphoric acid (54%), 1390 kg, is fed to the reactor. The temperature of the mass in the reactor is maintained at 140 ° C, and the pressure is 3 atm. The product in the amount of 2693 kg from the reactor is fed to the granulation. The 5000 kg granular mass is dried, classified and 2300 kg of finished product is obtained.

The plant capacity is 40 tons per hour of product. The amount of exhaust gases per unit of product is 4 m1 / t, with which 70 m of harmful impurities are emitted into the atmosphere.

The supply of a suspension of phosphate raw material tangentially at a speed of 0.1-5 m / s and decomposition of phosphate at 110-180 ° C and a pressure of 0.5-6 atm makes it possible to more completely separate fluoride and / or chloride compounds into the gas phase, which fall into vapor mixture formed.

In the absorption system, the fluoride and / or chloride compounds in the process of condensation of the vapor-air mixture are well captured and the amount of gases discharged into the atmosphere containing harmful impurities decreases. In addition, the transfer of part of the water into the vapor-air mixture and its suction into the absorption system makes it possible to reduce the amount of water removed during the drying of the intermediate product. This makes it possible to increase the productivity of the apparatus for drying, and therefore the process line, to reduce fuel consumption.

The feasibility of the selected process parameters is illustrated in table. 1-4.

In tab. Figure 1 shows the line capacity versus pressure change (reactor temperature 140 ° C),

Table 2 shows the performance of the line as a function of the temperature in the reactor (pressure in the reactor is 1 atm.)

As can be seen from Tables 1 and 2, when the pressure in the reactor drops below 0.5 agm. line capacity is reduced due to the low intensity of the phosphate decomposition process and the transfer of small amounts of water to the vapor state, with

This increases emissions of harmful impurities.

With an increase in pressure in the reactor of more than 6 atm, the system capacity

it stabilizes and there is no need to increase it over 6 atm. The amount of harmful impurities emitted in the atmosphere is not reduced. A decrease in temperature below 95 ° C slightly changes the performance of the system, since the viscosity of the mass increases and the rate of interaction of the phosphate raw material with sulfuric acid decreases. Increasing the temperature of the mass of more than 180 ° C is impractical

5 since the system capacity and the amount of harmful impurities emitted are stabilized and additional energy consumption is required to raise the temperature of the mass, which is impractical.

0B Table 3 shows the dependence

performance on the feed rate of reagents.

The use of acid (sulfuric) concentration of less than 75% leads to significant corrosive wear of pipelines and equipment; when sulfuric acid is used with a concentration of more than 98%, a significant amount of sulfur trioxide is released into the gas phase.

The process can use phosphoric acid with a concentration of 25-65% P20s, while the capacity of the installation will vary from 20 to 60 tons / h. 5 Table 4 presents the dependence of productivity on the concentration of phosphoric acid.

As can be seen from the table, the most appropriate concentration is 45–65% PaOs.

The process uses phosphate raw materials of various domestic and foreign deposits (Syrian, Chilisai, 5 Karatau, etc.)

Using the proposed method allows to increase the productivity of the process line (from 30 to 66 t / h), reduce emissions of harmful impurities into the atmosphere (from 0.039 by a known method to 0.016% of those introduced with raw materials), and simplify the process.

Claims (2)

Claim 1. A method of producing granular 5 phosphate fertilizers, including the decomposition of phosphate raw materials supplied to the reactor in the form of a slurry, a general acid at elevated temperature, granulating and drying the intermediate product, which is increasing the productivity of the process, reducing harmful emissions into the atmosphere, the suspension of phosphate raw material is served tangentially at a speed of 0.1-5 m / s and times2. A method according to claim 1, characterized in that the suspension of phosphate raw material is prepared at a ratio of 1: (0.4-0.9). and as a mineral acid is used or Putting is carried out at 110-180 ° С and pressure 5 sulfuric acid with a concentration of 75-98% 0.5-6 atm. and / or phosphoric acid. 2. The method according to claim 1, characterized in that the suspension of phosphate raw material is prepared at a ratio of 1: (0.4-0.9). and as a mineral acid is used or Table 1 table 2 Table 3 Table 4