阅读说明：本技术 高压循环法合成羰基铁络合物的工艺 (Process for synthesizing carbonyl iron complex by high-pressure circulation method ) 是由 赵宝生 滕荣厚 刘龙 后超 王向东 樊华 袁红卿 王敏 于 2019-11-29 设计创作，主要内容包括：本申请公开了一种高压循环法合成羰基铁络合物的工艺,包括以下步骤：向高压反应釜中持续通入CO气体,CO气体与釜内的海绵铁进行合成反应,生成羰基铁络合物；未反应的CO气体与生成的羰基铁络合物气体排出高压反应釜,经冷凝器和多级气-液分离器,羰基铁络合物液体进入羰基铁贮罐；分离后的CO气体循环到高压反应釜内进行反应；循环通入的CO气体与新通入的CO气体总流速在合成反应的初级阶段、高潮阶段、中期阶段、尾期阶段的循环次数为3-5次/小时、8-10次/小时、5-8次/小时、3-5次/小时。本申请有利于合成反应在压力和温度波动较小的条件下平稳进行,使反应时间缩短8-10小时,同时提高合成率和产物收得率。(The application discloses a process for synthesizing carbonyl iron complex by a high-pressure circulation method, which comprises the following steps: continuously introducing CO gas into the high-pressure reaction kettle, and carrying out synthetic reaction on the CO gas and the sponge iron in the kettle to generate a carbonyl iron complex; discharging the unreacted CO gas and the generated carbonyl iron complex gas out of the high-pressure reaction kettle, and allowing the carbonyl iron complex liquid to enter a carbonyl iron storage tank through a condenser and a multi-stage gas-liquid separator; circulating the separated CO gas into the high-pressure reaction kettle for reaction; the total flow rate of the circularly introduced CO gas and the newly introduced CO gas is 3-5 times/hour, 8-10 times/hour, 5-8 times/hour and 3-5 times/hour in the primary stage, the climax stage, the middle stage and the tail stage of the synthesis reaction. The method is favorable for the stable synthesis reaction under the condition of small pressure and temperature fluctuation, shortens the reaction time by 8-10 hours, and simultaneously improves the synthesis rate and the product yield.)

1. A process for synthesizing carbonyl iron complex by a high-pressure circulation method is characterized by comprising the following steps:

and (3) synthesis reaction: continuously introducing CO gas into the high-pressure reaction kettle, and synthesizing carbonyl iron complex by the CO gas and the iron-containing active raw material which is reduced by hydrogen in the high-pressure reaction kettle; the synthesis pressure is 15-18MPaG, and the synthesis temperature is 150-180 ℃;

gas-liquid separation: discharging unreacted CO gas and carbonyl iron complex gas generated by the reaction out of the high-pressure reaction kettle, realizing condensation liquefaction of the carbonyl iron complex and gas-liquid separation of the carbonyl iron complex and the CO gas through a condenser and a multistage gas-liquid separator, and enabling the carbonyl iron complex liquid to enter a carbonyl iron storage tank;

and (3) CO circulation: circulating the CO gas after gas-liquid separation through a circulating compressor, and introducing the CO gas into a high-pressure reaction kettle for synthetic reaction; the cycle times of the total flow of the circularly introduced CO gas and the newly introduced CO gas in the primary stage, the climax stage, the middle stage and the tail stage of the synthesis reaction are as follows: 3-5 times/hour, 8-10 times/hour, 5-8 times/hour, 3-5 times/hour; the time lengths of the primary stage, the climax stage, the middle stage and the tail stage of the synthesis reaction respectively account for 25% +/-5%, 50% +/-5%, 15% +/-5% and 10 + -5% of the total time length of the synthesis cycle.

2. The autocycle process of synthesis of carbonyl iron complexes as claimed in claim 1, wherein the iron containing active material that is reduced by hydrogen is sponge iron.

3. The process for synthesizing an iron carbonyl complex according to the high-pressure cycle method of claim 1, wherein the multistage gas-liquid separator in the gas-liquid separation step comprises a high-pressure gas-liquid separator, a medium-pressure gas-liquid separator, a low-pressure gas-liquid separator and a deep cold gas-liquid separator which are arranged in this order along the flow direction of the CO gas; the pressure of the high-pressure gas-liquid separator, the pressure of the medium-pressure gas-liquid separator, the pressure of the low-pressure gas-liquid separator and the pressure of the deep cold gas-liquid separator are sequentially reduced.

4. The process for synthesizing carbonyl iron complex compound according to claim 3, wherein the pressure of the high-pressure gas-liquid separator, the pressure of the medium-pressure gas-liquid separator and the pressure of the low-pressure gas-liquid separator are 3.0MPa, 1.5MPa and 0.1-0.3MPa in sequence.

5. The process for synthesizing carbonyl iron complex compound according to claim 3 or 4, wherein the temperature of the cooling medium of the deep cold gas-liquid separator is-12 ℃ to 0 ℃.

6. The process for synthesizing carbonyl iron complex according to claim 1, wherein in the step of synthesizing reaction, CO gas enters from the upper part of the autoclave and is discharged from the bottom.

7. The process for synthesizing carbonyl iron complex compound according to claim 6, wherein the bottom of the autoclave is equipped with a cooling water jacket.

8. The process for synthesizing carbonyl iron complex according to claim 1, wherein in the step of synthesizing reaction, the synthesizing reaction period is 52-60 h.

9. The process for synthesizing carbonyl iron complex compound according to claim 1, wherein in the CO circulation step, the CO inlet pressure of the circulation compressor is controlled at 0.1-0.3MPa, and the CO outlet pressure is controlled at 0.3-0.5MPa higher than the pressure in the high pressure reaction kettle.

10. The process for synthesizing carbonyl iron complex by high pressure cycle method according to claim 1, wherein in the CO cycle step, the temperature of the mixed gas entering the cycle compressor is 0-5 ℃, and the volume percentage of carbonyl iron complex in the mixed gas is less than 1.0%.

Technical Field

The application relates to a carbonyl iron complex synthesis process, in particular to a process for synthesizing a carbonyl iron complex by a high-pressure circulation method.

Background

The carbonyl process for refining iron belongs to a metallurgical method for extracting iron metal powder in the field of gas phase metallurgy, and the method utilizes CO gas and raw materials containing active iron as reactants to generate carbonyl iron complex-iron pentacarbonyl under certain temperature and pressure. The pentacarbonyl iron is extremely unstable, can be rapidly decomposed into metallic iron and CO gas at a certain temperature (more than or equal to 180 ℃), and can be used for obtaining metallic iron powder by a separation technology.

In the 30 s of the 20 th century, BASF in Germany first used a high pressure carbonyl process to refine iron. In the 50 s of the 20 th century, russian northern nickel corporation used high pressure CO cyclic carbonylation to refine iron. The main problems in the process for synthesizing the carbonyl iron complex by the high-pressure method are as follows:

(1) number of CO cycles and gas circulation volume

In the existing high-pressure carbonyl iron synthesis process, the CO circulation speed and the CO circulation amount in different stages of the synthesis reaction are basically constant. However, the CO reaction rate is variable, that is, the CO consumption rate and the carbonyl iron complex formation rate are variable, which causes the fluctuation of CO gas pressure in the high-pressure reactor, the temperature in the high-pressure reactor and the carbonyl iron concentration, the instantaneous low-pressure high-temperature phenomenon in the high-pressure reactor is the cause of carbonyl iron decomposition, a chain reaction occurs in the high-pressure reactor, and the carbonyl iron synthesis reaction rate and yield are seriously affected, and the reaction is as follows:

Fe(CO)₅→5CO

2CO→CO₂+C

in addition, pressure vessels are susceptible to fatigue failure under alternating pressure for extended periods of time.

(2) Range limit problem of CO gas circulation

In the synthesis process of carbonyl iron complex compound from Russian northern nickel company, the mixed gas of CO and carbonyl iron in a high-pressure circulating system enters a circulating compressor from a high-pressure condenser, and the pressure of the high-pressure condenser and the high-pressure separator is slightly lower than that of a synthesis kettle and still in a high-pressure state. According to the laboratory experiment result, when CO dissolved in the carbonyl iron liquid escapes from the carbonyl iron liquid, CO gas carries a large amount of carbonyl iron gas into the circulating compressor.

(3) Side effect of overhigh content of carbonyl iron gas in circulating CO gas

A large amount of carbonyl iron gas enters a circulating system along with CO, the content of carbonyl iron reaches 3-4% (volume percent), and finally enters a high-pressure reaction kettle in the form of liquid drops: on the one hand, the concentration of the carbonyl iron is increased, which is shown by the fact that the partial pressure of carbonyl iron vapor is increased, so that the reaction speed of carbonyl iron synthesis is reduced; on the other hand, decomposition of carbonyl iron occurs, and the generated iron (nano-scale) catalytically decomposes CO to generate free carbon, resulting in a decrease in the synthesis reaction rate and a decrease in the yield. The decomposition chemical reaction of CO under the catalysis of the nano iron is as follows:

2CO→CO₂+C

(4) CO circulation system is easy to block

As the CO circulating system contains more carbonyl iron gas, the carbonyl iron gas is decomposed to produce iron powder under the conditions of high temperature and low pressure, and the iron powder is deposited on the inner wall of the pipeline to easily cause the blockage of the CO circulating system.

Disclosure of Invention

In order to solve the above technical problem (1), it is desirable to provide a process for synthesizing an iron carbonyl complex by a high-pressure cycle method.

The application provides a process for synthesizing carbonyl iron complex by a high-pressure circulation method, which comprises the following steps:

and (3) synthesis reaction: continuously introducing CO gas into the high-pressure reaction kettle, and synthesizing carbonyl iron complex by the CO gas and the iron-containing active raw material which is reduced by hydrogen in the high-pressure reaction kettle; the synthesis pressure is 15-18MPaG, and the synthesis temperature is 150-180 ℃;

gas-liquid separation: discharging unreacted CO gas and carbonyl iron complex gas generated by the reaction out of the high-pressure reaction kettle, realizing condensation liquefaction of the carbonyl iron complex and gas-liquid separation of the carbonyl iron complex and the CO gas through a condenser and a multistage gas-liquid separator, and enabling the carbonyl iron complex liquid to enter a carbonyl iron storage tank;

and (3) CO circulation: circulating the CO gas after gas-liquid separation through a circulating compressor, and introducing the CO gas into a high-pressure reaction kettle for synthetic reaction; the cycle times of the total flow of the circularly introduced CO gas and the newly introduced CO gas in the primary stage, the climax stage, the middle stage and the tail stage of the synthesis reaction are as follows: 3-5 times/hour, 8-10 times/hour, 5-8 times/hour, 3-5 times/hour; the duration of the primary stage, the climax stage, the middle stage and the tail stage of the synthesis reaction respectively accounts for 25% +/-5%, 50% +/-5%, 15% +/-5% and 10 + -5% of the total duration of the synthesis cycle.

Experiments show that the synthesis reaction of the carbonyl iron complex by the high-pressure circulation method can be divided into the following steps according to the change of the reaction speed in the whole period: the reaction comprises a primary stage, a climax stage, a middle stage and a tail stage (arranged along the time sequence), wherein the time length of each stage respectively accounts for 25%, 50%, 15% and 10% of the total period time length, and the reaction rate is increased and then decreased. In the process for synthesizing the carbonyl iron complex by the high-pressure circulation method, the total flow of the circularly introduced CO gas and the newly introduced CO gas is 3-5 times/hour, 8-10 times/hour, 5-8 times/hour and 3-5 times/hour in the primary stage, the high-tide stage, the middle stage and the tail stage of the synthesis reaction, so that the synthesis reaction is under a stable reaction condition, the smooth reaction is ensured, and the pressure of the CO gas in a high-pressure reaction kettle, the temperature in the high-pressure reaction kettle and the fluctuation of the concentration of the carbonyl iron are avoided. In the high-pressure reaction kettle, circulating CO gas is continuously introduced to enable the reaction product carbonyl iron to timely escape from the high-temperature region, so that the carbonyl iron is prevented from being decomposed in the high-pressure reaction kettle. The invention adopts the method of combining the CO circulating system with the fresh CO gas supply, can keep the CO gas in the carbonyl iron synthesis reaction in the system in dynamic balance, has small pressure fluctuation of the CO gas in the high-pressure reaction kettle, and is beneficial to the carbonyl iron synthesis reaction. In the invention, the high-pressure reaction system is in a constant-pressure state, so that the probability of damage caused by stress change can be reduced, and the service life of high-pressure equipment is prolonged.

The circulating number of the CO gas is controlled by flow, the circulating number is 1 time counted by the fact that the amount of the CO introduced into the high-pressure reaction kettle reaches the total amount of the dynamic gas in the high-pressure reaction kettle, and the more circulation times per hour indicate that the introduction amount per hour is larger, namely the flow rate is larger. The number of CO gas cycles of the primary stage, the high tide stage, the middle stage and the tail stage is respectively 3-5 times/hour, 8-10 times/hour, 5-8 times/hour and 3-5 times/hour, the reaction pressure is constant, fresh CO gas is continuously supplemented into the high-pressure reaction kettle, and carbonyl iron vapor in the high-pressure reaction kettle is kept in an unsaturated state. The operation is beneficial to the continuous alternate proceeding of the desorption process of carbonyl iron molecules from the iron surface and the adsorption process of CO gas molecules on the iron surface, and is beneficial to the reaction in the positive reaction direction.

Preferably, the iron-containing active material subjected to hydrogen reduction is sponge iron. In addition to sponge iron, pyrite, magnetite, limonite, ilmenite sand, iron bauxite, and the like, which have been subjected to hydrogen reduction, may also be used.

Preferably, the multistage gas-liquid separator in the gas-liquid separation step includes a high-pressure gas-liquid separator, a medium-pressure gas-liquid separator, a low-pressure gas-liquid separator and a deep cold gas-liquid separator which are sequentially arranged along the flow direction of the CO gas; the pressure of the high-pressure gas-liquid separator, the pressure of the medium-pressure gas-liquid separator, the pressure of the low-pressure gas-liquid separator and the pressure of the deep cold gas-liquid separator are sequentially reduced.

Preferably, the pressure of the high-pressure gas-liquid separator, the pressure of the medium-pressure gas-liquid separator and the pressure of the low-pressure gas-liquid separator are 3.0MPa, 1.5MPa and 0.1-0.3MPa in sequence. The pressure of the deep cold gas-liquid separator is slightly lower than that of the low-pressure gas-liquid separator, and is also approximately in the range of 0.1-0.3 MPa. By adopting the new CO gas circulation path, the concentration of the carbonyl iron complex in CO can be reduced to the maximum extent, so that iron powder is prevented from entering a circulation compressor, and the technical problems (2) and (3) are solved.

Preferably, the temperature of the cooling medium of the deep cold gas-liquid separator is-12 ℃ to 0 ℃. The deep cold gas-liquid separator adopts a cooling medium with the temperature of-12 ℃ to 0 ℃, reduces the concentration of carbonyl iron while cooling the mixed gas, reduces the temperature of the gas entering a circulating compressor, prevents the carbonyl iron gas from decomposing to produce iron powder, and prevents the carbonyl iron powder from depositing on the inner wall of a pipeline to cause the blockage of a CO circulating system, thereby solving the technical problem (4) and further solving the technical problems (2) and (3).

Preferably, in the synthesis reaction step, the CO gas enters from the upper part of the high-pressure reaction kettle and is discharged from the bottom. According to the characteristics of the product and the characteristics of the reaction process, the new process adopts the circulation direction that CO gas enters from the upper part of the high-pressure kettle and is discharged from the bottom of the high-pressure kettle, and the liquid in the high-pressure kettle can be discharged out of the high-pressure kettle in time and continuously.

Preferably, the bottom of the high-pressure reaction kettle is provided with a cooling water jacket, so that the carbonyl iron gas is rapidly cooled and liquefied, the carbonyl iron liquid is continuously taken out of the high-pressure reaction kettle by circulating CO, the partial pressure of the carbonyl iron in the synthesis system is rapidly reduced, and the CO is prevented from being dissolved into the carbonyl iron liquid.

Preferably, in the step of synthesis reaction, the synthesis reaction period is 52-60 h.

Preferably, in the step of synthesis reaction, the synthesis reaction period is 52-60 h.

Preferably, in the CO circulation step, the CO inlet pressure of the circulation compressor is controlled to be 0.1-0.3MPa, and the CO outlet pressure is controlled to be 0.3-0.5MPa higher than the pressure in the high-pressure reaction kettle.

Preferably, in the CO circulating step, the temperature of the mixed gas entering the circulating compressor is 0-5 ℃, and the volume percentage of the carbonyl iron complex in the mixed gas is less than 1.0%. Experiments prove that when the temperature of the mixed gas is close to 0 ℃, iron powder is still deposited on the inner wall of the conveying pipeline. In order to prevent the pipeline from being blocked, the temperature of the mixed gas entering the circulating compressor is controlled within the range of 0-5 ℃. The concentration of carbonyl iron gas in the recycle gas is controlled to less than 1% (volume percent).

The application has the advantages and positive effects that: the method correctly designs the technological process, parameter setting and operation method of the high-pressure CO gas circulation system, and can shorten the synthesis reaction time by 8-10 hours and simultaneously improve the synthesis rate and the product yield in the newly designed high-pressure carbonyl iron synthesis system under the conditions of reducing pressure and temperature.

In addition to the technical problems addressed by the present application, the technical features constituting the technical solutions, and the advantages brought by the technical features of the technical solutions described above, other technical problems solved by the present application, other technical features included in the technical solutions, and advantages brought by the technical features will be further described in detail below with reference to the accompanying drawings.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIG. 1 is a process flow diagram of the synthesis of carbonyl iron complex by high pressure cycle method provided in the examples of the present application;

FIG. 2 is a flow chart of the synthesis of carbonyl iron complex by the original laboratory high pressure method provided by the comparative example of the present application.

In the figure: 1. a CO storage tank; 2. a compressor; 3. a recycle compressor; 4. a high-pressure reaction kettle; 5. a heat exchanger; 6. a condenser; 7. a high pressure gas-liquid separator; 8. a medium pressure gas-liquid separator; 9. a low pressure gas-liquid separator; 10. a liquid carbonyl iron storage tank; 11. a deep cold gas-liquid separator; 12. a gas filter; 13. a gas holder; 14. a gas-oil separator; 15. a CO heater; 16. a collector; 17. and (3) a filter.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.