CN103940697B - A kind of blast-furnace coke reactivity method of testing - Google Patents

Abstract

The invention provides a method for testing the reactivity of blast furnace coke, which uses existing equipment to characterize the reactivity of the coke by obtaining the change in the weight loss rate of the coke at different temperatures and the initial temperature of the carbon dissolution reaction of the coke. The method includes grinding the coke sample selected for testing into fine pieces, drying, taking out the coke sample, cooling to room temperature and sealing it for later use; weighing the spare coke sample and placing it in the test device for continuous temperature rise and introducing reaction gas CO ₂ , reaching After the end of the temperature rise, the computer data collection is completed, and the collected data is saved; finally, the data collected by the computer is processed; the reactivity of the coke is characterized by obtaining the change of the weight loss rate of the coke at different temperatures and the starting temperature of the carbon dissolution reaction of the coke. Through the method of the present invention, using test equipment such as a thermogravimetric balance, it is possible to comprehensively analyze the reaction of coke with _CO2 at different temperatures, and make a true and objective evaluation of the reactivity of coke with different qualities.

Description

A test method for blast furnace coke reactivity

technical field

The invention relates to a new method for testing the reactivity of blast furnace coke, which can also measure the reactivity of carbon-containing substances in other ironmaking raw materials, and belongs to the field of blast furnace ironmaking.

Background technique

Coke plays four roles in the blast furnace: heat source, reducing agent, skeleton and molten iron carburization. In recent years, in order to reduce coke consumption, increase blast furnace output, and improve pig iron quality, enhanced technologies such as blowing coal powder at the tuyere and oxygen-enriched air blast have been adopted. Coke as a heat source, reducing agent and carburizing can be Partially replaced, but the role of the loose skeleton as a blast furnace column cannot be replaced, and with the enlargement of the blast furnace and the strengthening of smelting, this role will become more prominent.

Coke reactivity (CRI) refers to the ability of coke to react with _CO2 to form CO ( ) at high temperature. In the process of carbon dissolution and loss reaction between coke and _CO2 , the pore wall inside the coke will be thinned, thereby reducing the strength of coke and accelerating coke damage, which will have the following adverse effects on the blast furnace smelting process: the development of direct reduction of iron, the utilization of gas Deterioration, the coke ratio increases; at the same time, the coke powder produced by coke damage deteriorates the air permeability of the blast furnace charge column and affects the smooth operation of the blast furnace. When the coke enters the region above 850°C, the carbon in it begins to react with CO ₂ in the gas to form CO; and when it enters the region above 1000°C, the dissolution reaction proceeds sharply; at 1200°C, the CO ₂ in the gas It will instantly react with the C in the coke and convert it into CO.

According to the results of research and production practice, it can be said that the quality of coke has become the decisive factor for the volume of the blast furnace, the amount of pulverized coal injected into the blast furnace, and the state of the hearth. In order to evaluate the influence of carbon dissolution rate on coke damage, improve coke quality, improve coal blending technology, and provide technical parameters for blast furnace operation, Japan first developed coke reactivity detection technology. Reactivity detection methods and standards.

The current domestic methods for detecting coke reactivity include national standards (GB/T4000-2008), patent CN101825548A, patent CN102928455A, etc. The principles adopted are all heated by high-temperature tube furnace with CO ₂ gas, and the amount of coke used in the test is large, and the experimental equipment The operation is complicated, especially the patent CN101825548A and the patent CN102928455A have improved the experimental equipment. If it is widely used, the investment or modification cost of the equipment will be large. Therefore, the national standard GB/T4000-2008 (coke reactivity and reaction post-strength test method). The national standard stipulates that the ability of coke to react with _CO2 gas at 1100 °C, that is, the reactivity and post-reaction strength, are important quality indicators to characterize the pyrometallurgical properties of coke. However, with the deepening of the research, these two indicators themselves are not perfect, and there are also some defects. First, there are data showing that the dissolution reaction of coke has already started at 800°C, and the dissolution reaction occurs within a certain temperature range, but the standard stipulates that the test temperature of 1100°C has certain limitations; second, even if Under the same reaction conditions, different cokes react with CO _The reaction rate is not the same, and there is also a deviation between the standard unified reaction time and the actual situation. The present invention can avoid the deviation caused by the different reaction rates; the third, the traditional detection method The amount of coke samples used is mostly 200g, but the amount of coke used in one experiment of the present invention is only 17-18mg, and the amount of experimental samples used is reduced by more than 99%, which greatly saves energy in a certain range.

Contents of the invention

The invention provides a new method for detecting the reactivity of carbon-containing substances such as blast furnace coke. Under the guidance of the principle of traditional test coke reactivity, the existing equipment is used to obtain the change of the weight loss rate of coke at different temperatures and the carbon content of coke. The starting temperature of the melting reaction can be used to characterize the reactivity of coke.

The method for detecting coke reactivity provided by the invention comprises the following contents:

(1) Grind the coke samples selected for testing into fine powder for later use;

(2) Put the prepared sample into an oven, dry it at 105~120°C for 2 hours, take out the coke sample, cool it to room temperature and seal it for later use;

(3) The test device is required to be able to heat up to 1200°C under a specific atmosphere, and continuously measure the weight loss of the sample at different temperatures during the heating process;

(4) Weigh 17~18mg of the spare coke sample, place it in the test device, and continuously raise the temperature at a heating rate of 20°C/min, while feeding the reaction gas CO ₂ , and controlling the gas flow rate at 60ml/min;

(5) The set heating range is from room temperature to 1200°C;

(6) After reaching the temperature rise end point, the computer data collection is completed, and the collected data is saved;

(7) When the furnace of the test device is cooled to room temperature, the sample can be taken out for the next set of experiments;

(8) The carbon dissolution loss reaction is carried out during the heating process, and finally the data collected by the computer can be processed to obtain the TG-DTA curve of the coke reacting in the continuous heating environment;

(9) By comparing the TG curve trend and weight loss rate, the change of coke weight loss rate at different temperatures and the starting temperature of coke carbon dissolution reaction can be obtained, and then the reactivity of coke can be characterized.

Further, the ground coke sample powder in the step (1) is passed through a 200-mesh sieve, and the under-sieve is taken for later use.

Further, the test device is a microcomputer differential thermal balance, and a comprehensive thermal analyzer, a synchronous thermal analyzer, a thermogravimetric analyzer or a thermal balance are selected.

Further, the method can be used to test the reactivity of coke, or test the reactivity of other carbon-containing substances; the other carbon-containing substances are coal, semi-coke, carbon-containing pellets, or biomass coke.

The invention has the advantages of avoiding the deviation caused by different reaction rates, obtaining the change of the weight loss rate of coke at different temperatures and the starting temperature of the carbon dissolution reaction of the coke, and then characterizing the reactivity of the coke. It can comprehensively analyze the reaction of coke with _CO2 at different temperatures, and make a true and objective evaluation of the reactivity of coke with different qualities. In addition, the amount of coke used in one experiment of the present invention is only 17-18mg, and the amount of experimental samples used is reduced by more than 99.9%, which greatly saves energy within a certain range.

Description of drawings

Figure 1(a) is a schematic diagram of the weight loss curves of No. 1, No. 2 and No. 3 cokes;

Figure 1(b) is a schematic diagram of the weight loss curves of the 4th, 5th and 6th cokes;

Figure 2 is a schematic diagram of the weight loss of each coke in the carbon dissolution reaction at 600 °C;

Figure 3 is a schematic diagram of the weight loss of each coke at 800 °C carbon dissolution reaction;

Figure 4 is a schematic diagram of the weight loss of each coke at 900 °C carbon dissolution reaction;

Fig. 5 is the schematic diagram of each coke starting reaction temperature;

Figure 6 is a schematic diagram of the weight loss of each coke in the carbon dissolution reaction at 1000 °C;

Figure 7 is a schematic diagram of the weight loss of each coke in the carbon dissolution reaction at 1100 °C;

Figure 8 is a schematic diagram of the weight loss of each coke in the carbon dissolution reaction at 1200 °C.

detailed description

The present invention will be further described below by specific examples.

Select 6 kinds of cokes used by a certain iron and steel company as test samples, pass through a 200 mesh sieve after being ground, and get the powder under the sieve for subsequent use;

Put the spare powder in an oven, dry it at 105~120°C for 2 hours, take it out, cool it to room temperature and seal it for later use;

The test device chooses a microcomputer differential thermal balance manufactured by a company in Beijing;

Weigh 17 mg of each of the 6 spare coke samples, place them in a differential thermal balance in sequence, and continuously raise the temperature at a heating rate of 20°C/min, while introducing reaction gas CO ₂ , and controlling the gas flow rate at 60ml/min;

The set heating range is from room temperature to 1200°C;

After reaching the heating end point, the computer data collection is completed, and the collected data is saved;

When the furnace chamber of the differential thermal balance is cooled to room temperature, the sample can be taken out for the experiment of the next sample;

The carbon dissolution loss reaction is carried out during the heating process. Finally, the data collected by the computer can be processed to obtain the TG-DTA curve of the coke reacting under the continuous temperature rising environment. Through data processing, the weight loss curves of six kinds of coke can be obtained, as shown in Figure 1 ( a) and (b). It can be seen from Figure 1(a) and (b) that the weight loss curves of the six cokes in the initial stage of reaction (<900°C) can be divided into three categories:

①Basically no weightlessness: 1# and 4#;

② A small amount of weight loss: 2# and 5#;

③ Significant weightlessness: 3# and 6#.

Figures 2 to 4 show the weight loss rates of cokes at 600°C, 800°C and 900°C. At 600°C, the weight loss rates of 1# and 4# cokes are less than 0.5%, and the weight loss rates of 2# and 5# cokes are between 2% to 3%, while the weight loss rates of 3# and 6# cokes are both greater than 4%.

At 900°C, the weight loss rate of 1# and 4# coke is less than 2%, the weight loss rate of 2# and 5# is between 4 and 6%, and the weight loss rate of 3# and 6# coke has exceeded 7%. Among them, the weight loss rate of 3# coke has exceeded 10%.

It can be seen that the dissolution reaction of coke will occur in the medium and low temperature zone, and the dissolution loss reaction rate of each coke is different, among which 3# and 6# cokes have higher reactivity in the medium and low temperature zone.

The intersection point of the tangent of the low-temperature reaction rate line and the high-temperature reaction rate line is defined as the starting temperature of the coke’s violent reaction, which is called the starting reaction temperature of coke. Figure 5 is a comparison chart of the starting reaction temperature of six kinds of coke. The starting reaction temperature of 2# coke is higher than 1010℃, and the lowest starting reaction temperature of 2# coke is 1018℃, and the highest starting reaction temperature of 6# coke is 1066℃, which is 48℃ later than that of 2# coke. The difference affects the position of the constant temperature zone of the blast furnace, and the coke with a large difference in the starting reaction temperature will increase the height of the constant temperature zone when it is put into the furnace. The order of the starting reaction temperature of the six cokes from low to high is: 2#<3#<4#<1#<5#<6#.

Figures 6 to 8 are the weight loss curves at 1000°C, 1100°C and 1200°C, respectively. At 1000°C, the weight loss rates of all cokes are less than 20%, and the weight loss rates of 1# and 4# cokes are less than 8%. ;When reaching 1100°C, the weight loss rate of all cokes exceeds 20%, among which 3# coke has exceeded 40%, the weight loss rate of 1# and 4# coke increases rapidly, and has exceeded 20%; when reaching 1200°C, all coke The weight loss rate of all of them has reached more than 40%, among which 3# has reached 85.58%, and the reaction is about to be complete, while 4# is only 49.22%, and the reaction is not more than half.

As described in the above example, a new blast furnace coke reactivity testing method provided by the present invention can comprehensively and meticulously characterize the coke reactivity, and at the same time determine the starting temperature of different coke melting reactions and the coke weight loss rate at different temperatures Variety. While effectively characterizing the reactivity of coke, it also greatly saves the amount of coke consumed in the experiment.

Claims (6)

1. A method for testing reactivity of blast furnace coke, characterized in that: the method comprises the following: (1) Grind the coke samples selected for testing into fine powder for later use; (2) Put the prepared sample into an oven, dry it at 105~120°C for 2 hours, take out the coke sample, cool it to room temperature and seal it for later use; (3) The test device is required to be able to heat up to 1200°C under a specific atmosphere, and continuously measure the weight loss of the sample at different temperatures during the heating process; (4) Weigh 17~18mg of the spare coke sample, place it in the test device, and continuously raise the temperature at a heating rate of 20°C/min, while feeding the reaction gas CO ₂ , and controlling the gas flow rate at 60ml/min; (5) The set heating range is from room temperature to 1200°C; (6) After reaching the temperature rise end point, the computer data collection is completed, and the collected data is saved; (7) When the furnace of the test device is cooled to room temperature, the sample can be taken out for the next set of experiments; (8) The carbon dissolution loss reaction is carried out during the heating process, and finally the data collected by the computer can be processed to obtain the TG-DTA curve of the coke reacting in the continuous heating environment; (9) By comparing the TG curve trend and weight loss rate, the change of coke weight loss rate at different temperatures and the starting temperature of coke carbon dissolution reaction can be obtained, and then the reactivity of coke can be characterized. 2. The method for testing reactivity of blast furnace coke according to claim 1, characterized in that: the ground coke sample powder in the step (1) is passed through a 200-mesh sieve, and the under-sieve is taken for later use. 3. The method for testing reactivity of blast furnace coke according to claim 1, characterized in that: the test device is a microcomputer differential thermal balance, a comprehensive thermal analyzer, a synchronous thermal analyzer or a thermogravimetric analyzer. 4. The method for testing reactivity of blast furnace coke according to claim 1, characterized in that: the method can be used to test the reactivity of coke, or test the reactivity of other carbon-containing substances. 5. The method for testing reactivity of blast furnace coke according to claim 4, characterized in that: said other carbon-containing substances are coal, semi-coke, carbon-containing pellets or biomass coke. 6. The method for testing reactivity of blast furnace coke according to claim 1, characterized in that: said test device is a thermobalance.