阅读说明：本技术 一种硝酸钾低塔造粒方法及其制备的硝酸钾颗粒 (Low-tower potassium nitrate granulation method and potassium nitrate granules prepared by same ) 是由 周宗模 于 2019-10-09 设计创作，主要内容包括：本发明属于硝酸钾制造技术领域,提供了一种硝酸钾低塔造粒方法及其制备的硝酸钾颗粒,包括如下步骤：将粉状硝酸钾投入熔融加热炉中进行加热熔融,并不断搅拌,直至原料完全熔化,得液态硝酸钾,将液态硝酸钾送至造粒塔上部的转动造粒器内,在转动造粒器的造粒头作用下均匀分散下落,形成球状硝酸钾颗粒,将球状硝酸钾颗粒通过振动流化床降温,并筛分后进行包装,得成品硝酸钾颗粒。本发明造粒方法工艺简单且能耗低,制备的硝酸钾成品颗粒破碎少,均匀圆润,无需返料,且产品空壳率几乎为零,产品流动性好,抗压性高,结块周期长,利于储存和运输,使用方便。(The invention belongs to the technical field of potassium nitrate manufacturing, and provides a low-tower potassium nitrate granulation method and potassium nitrate granules prepared by the same, which comprise the following steps: throwing powdery potassium nitrate into a melting heating furnace for heating and melting, continuously stirring until the raw materials are completely melted to obtain liquid potassium nitrate, delivering the liquid potassium nitrate into a rotary granulator on the upper part of a granulation tower, uniformly dispersing and dropping under the action of a granulation head of the rotary granulator to form spherical potassium nitrate particles, cooling the spherical potassium nitrate particles through a vibrating fluidized bed, and packaging after screening to obtain finished potassium nitrate particles. The granulation method has the advantages of simple process and low energy consumption, the prepared finished potassium nitrate product has less particle breakage, is uniform and mellow, does not need material returning, has almost zero empty shell rate, good product fluidity, high pressure resistance, long agglomeration period, is beneficial to storage and transportation, and is convenient to use.)

1. A low-tower potassium nitrate granulation method is characterized by comprising the following steps:

(1) putting powdery potassium nitrate into a melting heating furnace for heating and melting, stirring, filtering, and controlling the heating temperature to be 330-380 ℃ until the raw materials are completely melted to obtain liquid potassium nitrate;

(2) pumping the liquid potassium nitrate obtained in the step (1) into a rotary granulator on the upper part of a granulation tower;

(3) the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulating head of a rotary granulator to form spherical potassium nitrate granules;

(4) and (4) collecting the spherical potassium nitrate particles obtained in the step (3), cooling the spherical potassium nitrate particles through a vibrating fluidized bed, conveying the spherical potassium nitrate particles to a screening machine, screening the spherical potassium nitrate particles, conveying the screened spherical potassium nitrate particles to a storage bin, and packaging the particles to obtain finished potassium nitrate particles.

2. The low-tower potassium nitrate granulation method according to claim 1, wherein the height of the granulation tower is 10 to 25 m.

3. The low-tower potassium nitrate granulation method according to claim 1, wherein in the step (3), the granulation temperature is 330 to 340 ℃.

4. The low tower granulation method of potassium nitrate as claimed in claim 1, wherein the cooling temperature of the vibrated fluidized bed in the step (4) is 60 to 70 ℃.

5. The low-tower potassium nitrate granulation method according to claim 1, wherein in the step (3), the potassium nitrate granules have a particle diameter of 0.5 to 1.0 mm.

6. The low tower granulation method of potassium nitrate according to claim 1, wherein the temperature in the step (1) is 335 ℃ to 345 ℃.

7. The low-tower potassium nitrate granulation method according to claim 1, wherein the stirring time in step (1) is 10 to 30 min.

8. Potassium nitrate granules produced by the low-tower potassium nitrate granulation method according to any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of potassium nitrate manufacturing, and particularly relates to a low-tower potassium nitrate granulation method and potassium nitrate granules prepared by the same.

Background

Potassium nitrate is an important industrial raw material, is also a high-quality chlorine-free nitrogen-potassium compound fertilizer, and is widely applied to the fields of national defense, military industry, agriculture, food additives, medicines, feed additives, optical glass, electronic industry and the like. The potassium nitrate is easy to agglomerate due to the influence of the shape, composition, structure, surface area, physical and chemical properties of the crystal and the surrounding storage environment, and brings difficulty to storage, transportation, use and the like. Therefore, potassium nitrate is required to be granulated, the particle size is reduced, and the potassium nitrate is more convenient to transport, store and use.

The traditional potassium nitrate granulation adopts a high tower for granulation, the height of a tower body is generally 25-45 meters, the construction cost is high, and more potassium nitrate granules are easily crushed in the production process; on the other hand, the traditional method mostly adopts a guniting method to granulate, so that the potassium nitrate has the problems of uneven and mellow particle size, even micropores on the surface, overlarge particle size, more returned materials, high shell rate of the potassium nitrate granulation and the like.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a low-tower potassium nitrate granulation method and potassium nitrate granules prepared by the method, and the problems of high height of a traditional high-tower potassium nitrate granulation tower, easiness in granule crushing, uneven and mellow granulation granularity, overlarge granule granularity, much returned materials, high empty shell rate and the like are solved.

In order to achieve the above purpose, the solution adopted by the invention is as follows:

a low-tower potassium nitrate granulation method comprises the following steps:

(1) preparing powdery potassium nitrate: evaporating and concentrating the potassium nitrate solution by a multi-effect evaporator, cooling and crystallizing, and carrying out solid-liquid separation by a centrifugal machine to obtain powdery potassium nitrate;

(2) putting powdery potassium nitrate into a melting heating furnace for heating and melting, continuously stirring, controlling the heating temperature to be 330-380 ℃ until the raw materials are completely melted to obtain liquid potassium nitrate, and overflowing the liquid potassium nitrate into a liquid potassium nitrate buffer tank;

(3) pumping the liquid potassium nitrate obtained in the step (2) into a rotary granulator on the upper part of a granulation tower, and heating the rotary granulator to above 330 ℃;

(4) the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulating head of a rotary granulator to form spherical potassium nitrate granules;

(5) and (4) collecting the spherical potassium nitrate particles obtained in the step (4), cooling the spherical potassium nitrate particles through a vibrating fluidized bed, conveying the spherical potassium nitrate particles to a screening machine, screening the spherical potassium nitrate particles, conveying the screened spherical potassium nitrate particles to a storage bin, and packaging the particles to obtain finished potassium nitrate particles.

Furthermore, the tower height of the granulation tower is 10-25 m.

Further, in the step (4), the granulation temperature is 330-340 ℃.

Further, in the step (5), the cooling temperature of the vibrated fluidized bed is 60-70 ℃.

Further, in the step (5), the screening particle size of the screening machine is 0.2-1.0 mm.

Further, in the step (2), the heating temperature is 335-345 ℃.

Further, in the step (2), the stirring time is 10-30 min.

Potassium nitrate granules prepared by the potassium nitrate low-tower granulation method.

The invention has the beneficial effects that:

1. the granulation method has simple process, does not need cooling and drying in the granulation tower, greatly saves energy consumption, avoids the phenomenon of crushing potassium nitrate granules, is suitable for continuous mass production, and provides convenient conditions for automation of process control.

2. The potassium nitrate finished product prepared by adopting the method of granulating by using the rotary granulator has the advantages of good product performance, high purity, low moisture, less particle breakage, uniform particle size, round and smooth surface, no need of material return, almost zero empty shell rate of the product, good product fluidity, high pressure resistance, long anti-caking period, convenience for storage and transportation and convenience for use.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a process flow diagram of a granulation process provided by the present invention;

FIG. 2 shows a potassium nitrate granule product obtained in example 1 of the present invention;

FIG. 3 shows the potassium nitrate granular products obtained in examples 7 and 8 of the present invention;

FIG. 4 shows the products of potassium nitrate granules with different particle sizes obtained in examples 1 to 8 of the present invention under a high power microscope.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The potassium nitrate low-tower granulation method provided by the embodiment of the invention is specifically explained below.

A low-tower potassium nitrate granulation method comprises the following steps:

(1) preparing powdery potassium nitrate: evaporating and concentrating the potassium nitrate solution by a multi-effect evaporator, cooling and crystallizing, and carrying out solid-liquid separation by a centrifugal machine to obtain powdery potassium nitrate;

(2) putting powdery potassium nitrate into a melting heating furnace for heating and melting, continuously stirring, controlling the heating temperature to be 330-380 ℃ until the raw materials are completely melted to obtain liquid potassium nitrate, and overflowing the liquid potassium nitrate into a liquid potassium nitrate buffer tank;

(3) pumping the liquid potassium nitrate obtained in the step (2) into a rotary granulator on the upper part of a granulation tower, and heating the rotary granulator to above 330 ℃;

(4) uniformly dispersing and dropping the liquid potassium nitrate obtained in the step (3) under the action of a granulation head, so that potassium nitrate droplets drop in a high-temperature granulation tower to form spherical potassium nitrate granules;

(5) and (4) collecting the spherical potassium nitrate particles obtained in the step (4), cooling the spherical potassium nitrate particles through a vibrating fluidized bed, conveying the spherical potassium nitrate particles to a screening machine, screening the spherical potassium nitrate particles, conveying the screened spherical potassium nitrate particles to a storage bin, and packaging the particles to obtain finished potassium nitrate particles.

The granulating tower is characterized in that after potassium nitrate is granulated, potassium nitrate liquid drops are solidified into spherical potassium nitrate particles under the gradient action of high temperature to low temperature in the tower in the process of falling the potassium nitrate liquid drops in the tower, and meanwhile, cold air does not need to be introduced from the bottom to cool and solidify the potassium nitrate particles in the process of falling the potassium nitrate particles in the tower, so that the phenomenon that the potassium nitrate particles are easy to break under the multiple actions of high temperature of the potassium nitrate particles in the tower and low temperature and high wind speed of the cold air in the process of falling the potassium nitrate particles in the high tower is avoided, the granulating tower performs granulation in a rotating mode by rotating the granulator, the requirement for preparing particles with the size of 0.5-1.0 mm can be met, the particles are round and uniform, the consistent electric charge attraction among the particles is reduced, the contact area among the particles is greatly reduced, the flow performance of a potassium nitrate; the prepared potassium nitrate has compact particles and stronger compression resistance, thereby being beneficial to the storage and transportation of finished products and leading the potassium nitrate to be very convenient to transport, store and use; the particles prepared in the same batch are basically consistent in size and compact, no holes exist in the surface, the contact area is small, the phenomenon of agglomeration of the product due to moisture absorption is avoided, the dissolution performance of the finished product is controllable, and the controlled release time is consistent.

The height of the granulation tower is 10-25 m. The traditional high tower has quite large construction cost, and the tower is suitable for construction and production, so that the production cost is reduced, and the energy consumption for material conveying is reduced.

In the step (3), the granulation temperature is 330-340 ℃, and the raw materials can be completely melted in the temperature range to obtain liquid potassium nitrate; the grain diameter of the potassium nitrate grains after granulation reaches 0.5 mm-1.0 mm.

It should be noted that, in order to rapidly cool the high-temperature particles collected by the granulation tower, in the step (5), the cooling temperature of the vibration fluidized bed is 60-70 ℃, and the vibration fluidized bed is flat, so that the particle damage is greatly reduced, and the full solidification of the particles is ensured.

In the step (5), the screened particle size of the screening machine is 0.2 to 1.0 mm. Thereby screening to obtain potassium nitrate granules with required grain size.

In the step (2), the heating temperature is 335-345 ℃, and the stirring time is 10-30 min. The powdery potassium nitrate can be quickly brought into a molten state, and the reaction temperature and time are controlled, so that part of energy consumption is reduced.

Potassium nitrate granules produced by the granulation method as described in any one of the above.

Example 1

Powdery potassium nitrate with the purity of 99.0 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 330 ℃, the stirring time is 10min until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the height of 10 meters through a conveying pipeline and is heated to be in a rotating granulator with the temperature of 330 ℃ through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotating granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 110 ℃, and the temperature is reduced to 60 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 2

Powdery potassium nitrate with the purity of 99.4 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 340 ℃, the stirring time is 30min until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the height of 10 meters through a conveying pipeline and is heated to be in a rotating granulator with the temperature of 330 ℃ through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotating granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 110 ℃, and the temperature is reduced to 70 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 3

Powdery potassium nitrate with the purity of 99.7 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled at 360 ℃, the stirring time is 15min until the raw materials are completely melted to obtain liquid potassium nitrate, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the height of 10 meters through a conveying pipeline and is heated to a rotating granulator with the temperature of 330 ℃ through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotating granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 110 ℃, and the temperature is reduced to 65 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 4

Powdery potassium nitrate with the purity of 99.0 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 350 ℃, the stirring time is 20min until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the tower height of 15 meters through a conveying pipeline and is heated to 335 ℃ in a rotary granulator through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotary granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 120 ℃, and the temperature is reduced to 64 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 5

Powdery potassium nitrate with the purity of 99.4 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled at 355 ℃, the stirring time is 25min until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the height of 15 meters through a conveying pipeline and is heated to 335 ℃ in a rotary granulator through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotary granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 120 ℃, and the temperature is reduced to 66 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 6

Powdery potassium nitrate with the purity of 99.7 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 360 ℃, the stirring time is 30min until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the tower height of 15 meters through a conveying pipeline and is heated to 335 ℃ in a rotary granulator through a high-frequency induction heater, the liquid potassium nitrate is uniformly dispersed and falls under the action of a granulation head of the rotary granulator, the liquid drops of the potassium nitrate fall in the high-temperature granulation tower, solidification is realized, granulation and balling are realized, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 120 ℃, and the temperature is reduced to 68 ℃ through a vibrating fluidized bed, the granules are conveyed to a sieving machine, the sieved granules are conveyed to a storage bin, and the granules are packaged to obtain finished potassium nitrate granules.

Example 7

Powdery potassium nitrate with the purity of 99.7 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 360 ℃, the stirring time is 10min, until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the tower height of 25 meters through a conveying pipeline and is heated to 340 ℃ through a high-frequency induction heater, the rotating speed of the rotating granulator is adjusted to be reduced to 80 percent of the normal rotating speed in the embodiment, the liquid potassium nitrate uniformly disperses and falls under the action of a granulation head of the rotating granulator, so that the potassium nitrate liquid drops are solidified and granulated while falling in the high-temperature granulation tower, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank and are collected, the temperature of the collected spherical potassium nitrate particles is 110 ℃, and are cooled to 65 ℃ through vibration, and conveying to a sieving machine, conveying the sieved granules to a storage bin, and packaging to obtain finished potassium nitrate granules.

Example 8

Powdery potassium nitrate with the purity of 99.7 percent is put into a melting heating furnace for heating and melting, and is continuously stirred, the heating temperature is controlled to be 380 ℃, the stirring time is 30min, until the raw materials are completely melted, liquid potassium nitrate is obtained, the liquid potassium nitrate is conveyed to the upper part of a granulation tower with the tower height of 25 meters through a conveying pipeline and is heated to 340 ℃ through a high-frequency induction heater, the rotating speed of the rotating granulator is adjusted to be reduced to 50 percent of the normal rotating speed in the embodiment, the liquid potassium nitrate uniformly disperses and falls under the action of a granulation head of the rotating granulator, so that when potassium nitrate drops fall in the granulation tower with high temperature, spherical potassium nitrate particles are formed, the spherical potassium nitrate particles fall into a collecting tank for collection, the temperature of the collected spherical potassium nitrate particles is 110 ℃, the collected potassium nitrate is cooled to 64 ℃ through a vibrating fluidized bed, the potassium nitrate is conveyed to a screening machine, and, and packaging to obtain finished potassium nitrate granules.

Comparative example

This comparative example differs from example 1 in that: and (3) conveying the liquid potassium nitrate to a granulation ejector, wherein the granulation ejector ejects uniform potassium nitrate liquid drops from the upper part of the high tower, and the liquid drops fall by 30-50 m in an air flow with the flow velocity of 2-4 m/s from bottom to top to form spherical potassium nitrate particles.

Experimental example 1

The experimental method comprises the following steps: the finished potassium nitrate granules prepared in the experimental groups 1 to 9 were tested while the examples 1 to 8 and the comparative examples were set as the experimental groups 1 to 9, respectively, and the results are shown in table 1:

TABLE 1 Performance of potassium nitrate granules obtained in Experimental groups 1-9

In conclusion, the finished potassium nitrate granules prepared by the method for granulating potassium nitrate provided by the invention have high purity and low moisture, but compared with the finished potassium nitrate granules prepared by the method for spraying slurry and granulating in a certain proportion, the finished potassium nitrate granules prepared by the method for granulating potassium nitrate by adopting a rotary drum distributor have the advantages of less granule breakage, uniformity, smoothness, no need of material return, almost zero product empty shell rate, good product flowability, high pressure resistance, long agglomeration period, convenience for storage and transportation and convenience for use. Wherein, in embodiment 7 ~ 8, reduced the rotational speed of rotating the granulator for compare the particle diameter increase in embodiment 1 ~ 6, but still enable the potassium nitrate particle diameter and keep basically even unanimous, the effectual caking time that has prolonged the potassium nitrate granule does benefit to the storage and the transportation of product more, convenient to use. But the particle crushing rate and the particle shell rate are relatively increased, so that a certain amount of powder is generated, and the production and the attractiveness of the particles are influenced.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.