Test method for coke reactivity strength after reaction

1 Scope:

This standard specifies the summary of methods for determining coke reactivity strength after reaction, test instruments, equipment materials, sampling preparation of samples, test procedures, calculation precision of test results.

This standard applies to the determination of coke reactivity strength after reaction of coke used in blast furnace ironmaking, coke for other purposes can be implemented by reference.

2 Reference standards

The clauses included in the following standards constitute the clauses of this standard by being quoted in this standard. At the time of publication of the standard, the editions shown were valid. All standards will be revised, all parties using this standard should explore the possibility of using the latest version of the following standards.

The collection preparation of GB 1997-89 coke samples

GB/T 2006-94 Method for determination of mechanical strength of metallurgical coke

3 Principle

Weigh a certain mass of coke sample place it in the reactor. After reacting with carbon dioxide at 1000±5℃ for 2h, the coke reactivity (CRI%) is expressed as the percentage of coke mass loss. After the drum test, the mass percentage of coke larger than 10mm in the coke after the reaction represents the strength after the reaction (CSR%).

4 Test equipment, equipment materials

4.1 Electric stove

The furnace structure is shown in Figure 1.

Coke reactivity strength after reaction

Figure 1 Electric stove

1 a high-aluminum outer wire tube, 2 a iron-chromium-aluminum furnace wire; 3, 4 a lightweight high-alumina brick, 5-protective shell; 6 a caster, 7-furnace cover, 8 an insulator; 9 a temperature-controlled thermocouple

Furnace inner diameter 140mm, outer diameter 160mm, height 640mm high aluminum outer wire tube).

Electric furnace wire: high temperature iron-chromium-aluminum alloy resistance wire, operating temperature 1400℃, diameter 2.8m.

The main points of electric furnace installation: the bottom of the furnace shell is sealed, the upper mouth is open, casters are installed on the bottom plate in advance. Lay a layer of refractory bricks on the bottom, place the outer wire tube with the resistance wire in the middle of the bottom plate. The gap between the outer wire tube the furnace shell is filled with lightweight high-alumina brick preforms (made of standard size light

High-quality aluminum bricks are cut), the furnace wire is drawn the upper lower ends connected with the insulator fixed on the furnace shell. The lead part of the furnace wire is protected by a single-hole insulating tube, avoid overlapping each other to avoid short circuit. A hole with a diameter of 8mm is pre-drilled on the insulation brick outside the outer wire tube close to the furnace wire, the depth is 350mm top to bottom. Embed the thermowell, cover the lid, insert the temperature control couple, connect the electric furnace to the temperature controller the power supply, measure the constant temperature zone after each electric furnace is installed, so that the length of the temperature zone in the furnace is 110 0 ± 5℃ More than 150mm.

4.2 Reactor

The structure is shown in Figure 2, made of high temperature resistant alloy steel (GH23 GH44).

4.3 After the reaction strength test equipment

4.3.1 Type 1 drum: The device is shown in Figure 3. Speed 20±1.5 r/min.

4.3.1. 1 Drum body: It is made of seamless steel pipe with a thickness of ￠140mm a thickness of 5-6mm.

4.3.1 .2 Reducer: speed ratio 50 (WHT08 type).

4.3.1.3 Motor: 0.7 5 kW, 9 1 0r/min (Y905-6)

4.3.2 Rotary drum controller: total number of rotations 600r, time 30min.

4.4 Carbon dioxide supply system

4.4.1 Carbon dioxide cylinder oxygen pressure gauge. The carbon dioxide content in the cylinder is greater than 98%.

4.4.2 Rotameter: 0.6 m3/h.

4.4.3 Gas scrubber: 500mL in volume, with concentrated sulfuric acid (p=1.84 g/mL).

4.4.4 Drying tower: 500ml in volume, anhydrous calcium chloride inside.

4.4.5 Buffer bottle: the volume is 6000ml.

4.5 Nitrogen supply system

4.5.1 Nitrogen cylinder oxygen pressure gauge. The nitrogen content in the cylinder is greater than 98%.

4.5.2 Rotameter: 0.25m3/h.

4.5.3 Gas scrubber: 500mL in volume, containing an alkaline solution of charcoal gallic acid. Preparation method: 5g pyrogallic acid is dissolved in 15mL water, 48g potassium hydroxide is dissolved in 32mL water, the two are mixed. Take care to prevent air oxidation during preparation.

4.5.4 Drying tower: 500mL in volume, with anhydrous block calcium chloride inside.

4.5.5 When using high-purity nitrogen (nitrogen content 99.99%), the gas scrubber 4.5.3 the drying tower 4.5.4 are required.

4.6 Precision temperature control device

Temperature control range: 0-1600℃, accuracy ±0.5℃, without isolation transformer.

4.7 Gas analyzer

Simple gas analyzer other instrument for accurately measuring carbon dioxide content.

4.8 Round hole screen

￠18mm, ￠15mm, "￠ 10mm, ￠ 5mm, ￠ 3mm, ￠ 1m, one each, the screen frame diameter is ￠200mm.

One each for ￠21mm ￠25mm, with a sieve surface of 400mm×500mm, which shall be manufactured according to the requirements of Article 4.2 of the round hole sieve in GB/T 2006.

4.9 thousand dry boxes

The volume of the working chamber is less than 0.07m3.

Temperature: 300°C.

4. 10 pan balance

Weigh 500g, with a sense of 0.5g.

4. 11 Infrared bulb

220V, 250W.

4. 12 platinum germanium-platinum thermocouple

0.5mm in diameter, 700mm in length

High aluminum thermocouple protection tube A ￠7X5×400（mm）

High-aluminum double-hole insulation tube D ￠ 4Xl×400 (mm)

High-aluminum single-hole insulation tube Ｃ　￠ 1 × 0.6 × 10 (mm)

4.13 Sieve plate

The material is high-temperature resistant alloy steel (GH23 GH44), with a thickness of 3mm a diameter of 79mm. Holes with a diameter of 3mm are evenly drilled on it with a distance of 5mm between the holes.

4.14 High aluminum ball

20mm in diameter.

4.15 bracket

As shown in Figure 4. The material is Q235A, the three branch pipes are made of 1Grl8Ni9Ti.

Coke reactivity

Figure 4 Bracket

4.16 Reactor support

The size form of the reactor are arbitrary.

5 Sample collection preparation

5.1 According to the sampling method specified in GB1997, take 20kg of coke larger than 25mm in proportion discard the soaked coke furnace head coke. Use a jaw crusher to crush, mix, reduce to 10kg, then use ￠25mm. Screened with a round hole sieve of ￠21mm, then crushed sieved the coke lump larger than ￠25mm. Take the material on the sieve of ￠21mm, remove the flake coke the bar coke, shrink the coke block to 2kg. Divide twice (1kg each time) ) Placed in an I-type rotating drum, at a speed of 20r/min, rotate to 50r, take it out then sieving with a ￠21mm round hole sieve. The sieve is reduced to 900g as a sample. The sample is divided into four parts, each less than 220g.

The coke of the test coke oven can be sampled with coke of 40mm-60mm particle size.

5.2 Put the prepared sample in a drying box, dry it at 170-180℃ for 2h, take out the coke cool it to room temperature, weigh 200g±0.5 for later use.

6 Test procedure

The test process is shown in Figure 5.

Strength after reaction

Figure 5 Test flow chart

1-Carbon dioxide cylinder; 2-Needle valve; 3-Buffer bottle; 4-Concentrated sulfuric acid gas scrubber; 5, 13-Drying tower; 6-Glass three-way piston; 7-Precision temperature control device; 8-Thermocouple 9 －Gas analyzer; 10 a nitrogen cylinder; 11,19 a rotor flow meter; 12 a coke gallic acid pickling gas cylinder; 14 a bracket; 15 a sample; 16 a reactor; 17 an electric furnace; 18 an infrared light

6.1 Lay a layer of high aluminum balls about 100mm high on the bottom of the reactor, place the sieve flat on it. Then load the prepared coke sample 200g ± 0.5. Note that before loading the sample, adjust the height of the high aluminum ball so that the coke layer in the reactor is in the constant temperature zone of the electric furnace. Insert the thermowell connected to the upper cover into the center of the material layer. Fix the cover with the reactor cylinder with screws. The reactor is placed on a bracket on the top of the furnace hung in the electric furnace, an asbestos board is placed between the bracket the electric furnace cover for heat insulation. High-aluminum lightweight bricks (cut with standard-size high-aluminum lightweight bricks, random sizes) are placed around the reactor flange to reduce heat dissipation.

6.2 Connect the reactor inlet pipe exhaust pipe to the gas supply system exhaust system respectively. Insert the temperature measuring thermoelectric corner into the reactor thermoelectric corner casing (the thermoelectric corner is protected by a high-aluminum double-hole insulation tube a high-aluminum thermoelectric corner protection tube). Check the gas path to ensure tightness.

6.3 Turn on the power supply adjust the heating of the electric furnace with a precision temperature control device. Manually adjust the current small to large, gradually adjust to the maximum value within 15 minutes, then set the button to the automatic position. The heating rate is 8-16℃/min 　. When the temperature in the center of the material bed reaches 400°C, nitrogen is passed at a flow rate of 0.8 L/mi to protect the coke prevent it burning.

6.4 When the center temperature of the material layer reaches 1050°C, turn on the infrared light to preheat the outlet of the carbon dioxide cylinder. When the temperature in the center of the material layer reaches 1,100°C, the nitrogen is cut off the carbon dioxide is changed to flow at 5 L/min, react for 2 hours. The temperature of the material bed should be restored to 1,100±5°C within 5-10 m in after the carbon dioxide is introduced. 5min after the reaction started, take the gas for analysis in the exhaust system, then take the gas every half an hour to analyze the carbon monoxide carbon dioxide content in the gas after the reaction.

6.5 Reaction for 2h, stop heating. Cut off the carbon dioxide gas circuit, change to nitrogen, control the flow rate at 2L/min. Unplug the exhaust pipe. Quickly take the reactor out of the electric furnace, place it on the support continue to pass nitrogen gas to cool the coke to below 100°C, stop the nitrogen gas flow, open the reactor cover, pour out the coke, sieving, weighing, recording.

6.6 Put all the reacted coke into an I-type drum rotate it for 30 minutes at a speed of 20r/min. The total number of revolutions is 600r. Then take out the coke, sieving, weighing, recording the quality of each sieve grade.

6.7 The sieve composition obtained in the test, the gas composition after the reaction, other observed phenomena shall be recorded in detail according to the original record sheet analyzed for reference when comprehensively inspecting the properties of coke.

6.8 The original test data shall be recorded in the format shown in Table 1.

7 Calculation of test results

7.1 Coke reactivity

The index of coke reactivity is expressed as the percentage of the lost coke mass to the total mass of the coke sample before the reaction. CRI% of coke reactivity is calculated according to (1﹚ formula:

Coke reactivity formula

: m— mass of coke sample, g; m1— mass of residual coke after reaction, g.

7.2 Strength after reaction

The strength index after the reaction is expressed as the mass percentage of coke larger than 10mm after the drum in the residual coke after the reaction. The intensity CSR% after reaction is calculated according to formula (2):

Strength formula after reaction

In the formula: m2—the mass of coke particles larger than 10mm after the drum, g.

8 precision

8.1 The repeatability r of CRI of coke reactivity CSR after reaction strength shall exceed the following values:

CRI: r≤2.4%,

CSR: r≤3.2%

8.2 The test results of coke reactivity strength after reaction are the arithmetic average of parallel tests.