Roller-type distributing device and method for preparing pellets through stepped pelletizing and sectional drying

Abstract

The invention discloses a roller-type distributing device and method for preparing pellets through stepped pelletizing and segmented drying, the roller-type distributing device comprises a roller sieve plate, an air bellow and a pellet outlet hole, the roller sieve plate is arranged in a slope mode and is arranged in a manner that a plurality of groups of rollers are rotationally combined and spliced, gaps are formed among the plurality of groups of rollers, and the air bellow is arranged in the air bellow. An arc-shaped ball blocking plate is arranged on the periphery of an under-screen area of the roller screen plate, a plurality of sets of U-shaped holes are formed in the arc-shaped ball blocking plate, an air inlet and an air outlet are formed in the left side and the right side of the air bellow respectively, one side of the arc-shaped ball blocking plate and the side edge of the roller screen plate are connected with the air outlet in one side of the air bellow respectively, and a ball outlet hole is further formed in the bottom of the arc-shaped ball blocking plate. A plurality of groups of U-shaped holes are formed in the arc-shaped ball baffle; and a belt type roasting machine is arranged close to the bottom of the roller sieve plate. The method has the advantages that the burst temperature of the pellets prepared from the hematite and limonite and the compressive strength of the green pellets are improved based on gradient pelletizing and sectional drying of the belt type roasting machine.

Description

Technical Field

[0001] The invention relates to the technical field of pellet production, and in particular to a roller distributor and a method for preparing pellets by step-by-step pelletizing and segmented drying. Background Art

[0002] The application of hematite in pellet production has become an important way for the high-quality development of pellets in the future. However, due to the high crystal water content of hematite, the decomposition of crystal water will occur during the drying process of the pellets. This not only causes the green balls to burst during the drying process, but also greatly reduces the strength of the preheated balls, affecting the quality of the pellets, and at the same time limits the application ratio of hematite in the pellets. Based on the belt roaster using 60% high-proportion hematite to prepare green balls, the bursting temperature is about 350-390℃. During the drying process, the pellets are prone to bursting and affect the stability of the pellet roasting process. If the proportion of hematite is further increased, the bursting temperature of the green balls will gradually decrease.

[0003] In the existing pellet production technology, the main measure to increase the pellet roasting temperature is to increase the bentonite ratio. Due to the water absorption characteristics of bentonite, water can be slowly released during the drying process, so the bursting temperature can be increased. However, increasing the bentonite ratio of the pellets will inevitably lead to an increase in the alkali metal load and reduce the iron quality of the pellets. In addition, in the high-proportion hematite mode, it can stabilize the number of pellet falls. Increasing the bentonite ratio and increasing the plasticity of the raw balls are not conducive to improving the quality of the pellets. The bursting temperature of the pellets prepared with a high proportion of hematite is low, and it is easy to burst and pulverize during the drying process, affecting the air permeability of the pellets during roasting. Summary of the invention

[0004] The purpose of the present invention is to provide a roller distributor and method for preparing pellets by step-by-step pelletizing and staged drying, so as to improve the bursting temperature of pellets prepared by hematite and the compressive strength of green balls by step-by-step pelletizing and staged drying based on a belt roaster.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A roller distributor for step-by-step pelletizing and staged drying to prepare pellets, characterized in that the roller distributor comprises a roller screen plate, a bellows and a ball outlet hole, the roller screen plate is arranged on an inclined surface, the roller screen plate is arranged by rotating and combining multiple groups of rollers, gaps are arranged between multiple groups of rollers, arc-shaped ball baffle plates are arranged around the screen lower area of ​​the roller screen plate, multiple groups of U-shaped holes are arranged on the arc-shaped ball baffle plate, the bellows are respectively provided with air inlets and air outlets on the left and right sides, one side of the arc-shaped ball baffle plate and the side of the roller screen plate are respectively connected to the air outlet on one side of the bellows, a ball outlet hole is also arranged at the bottom of the arc-shaped ball baffle plate, multiple groups of U-shaped holes are arranged on the arc-shaped ball baffle plate, and the bottom of the roller screen plate is close to a belt roasting machine. .

[0006] Preferably, the inclination angle of the roller screen plate is 13°-15°, the width of the roller screen plate is 4500 mm, the length is 7240 mm, the number of rollers is 80 groups, the roller closest to the belt roasting machine is numbered 80, and the farthest roller is numbered 1.

[0007] Preferably, the diameter of the odd-numbered rollers is set to 89 mm, the diameter of the even-numbered rollers is set to 80 mm, and the gap between adjacent rollers is set to 8 mm.

[0008] Preferably, the width of the U-shaped hole is 6 mm, the diameter of the ball outlet hole is 1000 mm, a ball outlet extension tube is provided at the bottom of the ball outlet hole, and a double-gate sealing structure is provided in the ball outlet extension tube.

[0009] Preferably, a wind hood is provided above the roller screen plate, and an electrostatic precipitator is provided in the wind hood.

[0010] A method for preparing pellets by step-by-step pelletizing and stage-by-stage drying, characterized in that it comprises the following steps: The first stage of disc ball making: through traditional disc ball making, the number of times the raw ball falls is controlled to 4-5 times; The second stage of enhanced ball making: the raw balls obtained from the disc ball making in the first stage are fed to the roller screen plate of the roller distributor through the small belt under the disc and the large conveyor belt, increasing the number of raw ball drops by 1-2 times; First stage drying: hot air is introduced into the air inlet of the roller distributor, and the balls under the screen fall onto the return belt and return to the first stage of disc ball making; Second stage drying: The balls on the screen are subsequently dried in the second stage by blowing and exhausting air in a belt roaster.

[0011] Preferably, the effective area of ​​the belt roaster is 432m 2 The number of discs matched with the belt roaster is 8, each disc has a diameter of 7.5 meters, the disc angle range is adjusted to 45°-50°, the disc speed is 6-9r / min, the pelletizing input of a single disc is 150-200t / h, and the disc side height is 550mm.

[0012] Preferably, the material layer thickness of the roller distributor is 2-3 layers of balls.

[0013] Preferably, the hot air introduced into the bellows inlet of the roller distributor is taken from the exhaust gas from the bellows of the exhaust section, and the air temperature is adjusted to 120-180°C by adding cold air from a series fan. At the same time, the wind speed is adjusted to 1.0-1.5m / s. The strength of the raw balls after passing through the roller distributor is greater than 48N / P, and the moisture is controlled to 7-8%.

[0014] Preferably, the blast air temperature of the second-stage drying is 150-200°C, the air temperature of the exhaust drying is 350-500°C, and the final green ball bursting temperature is 450-480°C.

[0015] In summary, the beneficial effects of the present invention are as follows: the present invention provides a method for improving the bursting temperature of pellets prepared by hematite based on step-by-step balling and segmented drying of a belt roaster. Under the premise of not increasing the bentonite ratio of the pellets, step-by-step balling is used to control the number of drops and improve the strength of the green balls during the rolling process of the roller screen, and provide conditions for pre-drying of the green balls. Through segmented drying, the green balls are passed through the roller screen to remove the green balls with unqualified particle sizes. During the green ball screening and rolling process, 120-180°C hot air is introduced, and the green ball strength is improved and the moisture content is controlled during the green ball screening and rolling process, and part of the capillary water is squeezed out and pre-dried, and finally the bursting temperature of the green balls in the preparation of pellets using hematite as the pellet raw material is increased to 450-480°C, and the compressive strength of the green balls reaches above 48N / P. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a roller distributor for step-by-step pelletizing and stage-by-stage drying to prepare pellets in the present invention under working state; Figure 2 It is a schematic diagram of the specific structure of a roller distributor for step-by-step pelletizing and stage-by-stage drying to prepare pellets according to the present invention; Figure 3 The present invention is a schematic diagram of the roller distribution structure of a roller distributor for step-by-step pelletizing and stage-by-stage drying to prepare pellets. DETAILED DESCRIPTION

[0017] The specific implementation manner of the present invention is further described below in conjunction with the accompanying drawings, and this embodiment does not constitute a limitation of the present invention.

[0018] like Figures 1 to 3 A roller distributor for preparing pellets by step-by-step ball making and staged drying is shown. The roller distributor includes a roller screen plate 1, a bellows 2 and a ball outlet hole 3. The roller screen plate 1 is arranged on an inclined surface. The roller screen plate 1 is arranged by rotating, combining and splicing multiple groups of rollers. Gaps are arranged between the multiple groups of rollers. Arc-shaped ball baffle plates 4 are arranged around the screen area below the roller screen plate 1. Multiple groups of U-shaped holes 5 are arranged on the arc-shaped ball baffle plates 4. The bellows 2 is respectively provided with air inlets 6 and air outlets 7 on the left and right sides. One side of the arc-shaped ball baffle plate 4 and the side of the roller screen plate 1 are respectively connected to the air outlet 7 on one side of the bellows 2. A ball outlet hole 3 is also arranged at the bottom of the arc-shaped ball baffle plate 4. Multiple groups of U-shaped holes 5 are arranged on the arc-shaped ball baffle plate 4. A belt roasting machine is arranged near the bottom of the roller screen plate 1.

[0019] The inclination angle of the roller screen plate 1 is 13°-15°, the width of the roller screen plate 1 is 4500mm, the length is 7240mm, the number of rollers is 80 groups, the roller closest to the belt roasting machine is numbered 80, and the farthest roller is numbered 1.

[0020] like Figure 3 As shown, the diameter of the odd-numbered rollers is set to 89 mm, the diameter of the even-numbered rollers is set to 80 mm, and the gap between adjacent rollers is set to 8 mm. By arranging rollers of different diameters at odd and even positions at intervals, the rolling distance and disturbance of the pellets on the roller screen plate 1 are increased, and the friction rolling between the pellets is enhanced.

[0021] The width of the U-shaped hole 5 is 6 mm, the diameter of the ball outlet hole 3 is 1000 mm, and a ball outlet extension tube 8 is arranged at the bottom of the ball outlet hole 3. A double-gate sealing structure is arranged in the ball outlet extension tube 8. The upper gate remains closed during the ball outlet process, and the lower gate is closed when the upper gate is opened to discharge the balls, so as to keep the lower part of the roller screen well sealed and without air leakage.

[0022] An air hood is arranged above the roller screen plate 1, and an electric dust removal device is arranged inside the air hood.

[0023] A method for preparing pellets by step-by-step pelletizing and stage-by-stage drying, comprising the following steps: The first stage of disc ball making: through traditional disc ball making, the number of times the raw ball falls is controlled to 4-5 times; The second stage of enhanced ball making: the raw balls obtained from the disc ball making in the first stage are fed to the roller screen plate 1 of the roller distributor through the small belt under the disc and the large conveyor belt, increasing the number of raw balls falling by 1-2 times, providing conditions for pre-drying during the roller screening process; First stage drying: hot air is introduced into the air inlet 6 of the wind box 2 of the roller distributor, and the balls under the screen fall onto the return belt and return to the first stage of disc ball making. Hot air is introduced into the raw balls during rolling and screening on the roller screen plate 1. The raw balls are pre-dehydrated during rolling on the roller screen plate 1, that is, rolling squeeze water out and pre-drying are coupled to achieve the purpose of controlling the moisture content of the raw balls; Second stage drying: The balls on the screen are subsequently dried in the second stage by blowing and exhausting air in a belt roaster.

[0024] The effective area of ​​the belt roaster is 432m 2 The number of discs matched with the belt roaster is 8, each disc has a diameter of 7.5 meters, the disc angle range is adjusted to 45°-50°, the disc speed is 6-9r / min, the pelletizing input of a single disc is 150-200t / h, and the disc side height is 550mm.

[0025] Control the amount of raw balls input, control the thickness of the roller distributor material layer to 2-3 layers of balls, strengthen the rolling contact between the raw balls and the round rollers and the friction and rolling between the raw balls, squeeze out capillary water during the dense ball making process, and improve the strength of the raw balls.

[0026] The hot air introduced into the air inlet 6 of the bellows 2 of the roller distributor is taken from the exhaust gas of the bellows in the exhaust section. The air temperature is adjusted to 120-180℃ by adding cold air through the series fan. At the same time, the wind speed is adjusted to 1.0-1.5m / s. The strength of the raw balls after passing through the roller distributor is greater than 48N / P, and the moisture is controlled at 7-8%.

[0027] The blast air temperature of the second stage drying is 150-200℃, the air temperature of the exhaust drying is 350-500℃, and the final green ball bursting temperature is 450-480℃.

[0028] The invention provides a method for improving the bursting temperature of pellets prepared by hematite based on step-by-step balling and segmented drying of a belt roaster. Under the premise of not increasing the bentonite ratio of the pellets, step-by-step balling is used to control the number of drops and improve the strength of green balls during the rolling process of a roller screen, and provide conditions for pre-drying of green balls. During the segmented drying, green balls are passed through a roller screen to remove green balls with unqualified particle sizes, and hot air at 120-180°C is introduced to improve the strength of the green balls and control the moisture content during the green ball screening and rolling process, squeeze out part of the capillary water and pre-dry, and finally improve the bursting temperature of green balls in the preparation of pellets using hematite as a pellet raw material to 450-480°C, and the compressive strength of the green balls reaches above 48N / P.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A roller distributor for step-by-step pelletizing and stage-by-stage drying to prepare pellets, characterized in that: The roller distributor includes a roller screen plate, a bellows and a ball outlet hole. The roller screen plate is arranged on an inclined surface. The roller screen plate is arranged by rotating, combining and splicing multiple groups of rollers. Gaps are arranged between the multiple groups of rollers. Arc-shaped ball baffle plates are arranged around the screen lower area of ​​the roller screen plate. Multiple groups of U-shaped holes are arranged on the arc-shaped ball baffle plates. The bellows are respectively provided with air inlets and air outlets on the left and right sides. One side of the arc-shaped ball baffle plate and the side of the roller screen plate are respectively connected to the air outlet on one side of the bellows. A ball outlet hole is also arranged at the bottom of the arc-shaped ball baffle plate. Multiple groups of U-shaped holes are arranged on the arc-shaped ball baffle plate. The bottom of the roller screen plate is close to a belt roasting machine.

2. A roller distributor for preparing pellets by step-by-step pelletizing and staged drying according to claim 1, characterized in that: The inclination angle of the roller screen plate is 13°-15°, the width of the roller screen plate is 4500mm, and the length is 7240mm. The number of rollers is 80 groups, and the roller closest to the belt roasting machine is numbered 80, and the farthest roller is numbered 1.

3. A roller distributor for preparing pellets by step-by-step pelletizing and staged drying according to claim 2, characterized in that: The diameter of the odd-numbered rollers is set to 89 mm, the diameter of the even-numbered rollers is set to 80 mm, and the gap between adjacent rollers is set to 8 mm.

4. The roller distributor for preparing pellets by step-by-step pelletizing and staged drying according to claim 1, characterized in that: The width of the U-shaped hole is 6 mm, the diameter of the ball outlet hole is 1000 mm, a ball outlet extension tube is arranged at the bottom of the ball outlet hole, and a double-gate sealing structure is arranged in the ball outlet extension tube.

5. The roller distributor for preparing pellets by step-by-step pelletizing and staged drying according to claim 1, characterized in that: A wind hood is arranged above the roller screen plate, and an electric dust removal device is arranged in the wind hood.

6. A method for preparing pellets by using the step-by-step pelletizing and staged drying method according to any one of claims 1 to 5, characterized in that: The steps include: The first stage of disc ball making: through traditional disc ball making, the number of times the raw ball falls is controlled to 4-5 times; The second stage of enhanced ball making: the raw balls obtained from the disc ball making in the first stage are fed to the roller screen plate of the roller distributor through the small belt under the disc and the large conveyor belt, increasing the number of raw ball drops by 1-2 times; First stage drying: hot air is introduced into the air inlet of the roller distributor, and the balls under the screen fall onto the return belt and return to the first stage of disc ball making; Second stage drying: The balls on the screen are subsequently dried in the second stage by blowing and exhausting air in a belt roaster.

7. The method for preparing pellets by step-by-step pelletizing and staged drying according to claim 6, characterized in that: The effective area of ​​the belt roaster is 432m 2 The number of discs matched with the belt roaster is 8, each disc has a diameter of 7.5 meters, the disc angle range is adjusted to 45°-50°, the disc speed is 6-9r / min, the pelletizing input of a single disc is 150-200t / h, and the disc side height is 550mm.

8. The method for preparing pellets by step-by-step pelletizing and staged drying according to claim 6, characterized in that: The material layer thickness of the roller distributor is 2-3 layers of balls.

9. The method for preparing pellets by step-by-step pelletizing and staged drying according to claim 6, characterized in that: The hot air introduced into the air inlet of the bellows of the roller distributor is taken from the exhaust gas of the bellows in the exhaust section. The air temperature is adjusted to 120-180°C by adding cold air through the series fan. At the same time, the wind speed is adjusted to 1.0-1.5m / s. The strength of the raw balls after passing through the roller distributor is greater than 48N / P, and the moisture is controlled to 7-8%.

10. The method for preparing pellets by step-by-step pelletizing and staged drying according to claim 6, characterized in that: The blast air temperature of the second stage drying is 150-200°C, the air temperature of the exhaust drying is 350-500°C, and the final green ball bursting temperature is 450-480°C.

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