Binder-free high-quality pellet production method

Abstract

The invention discloses a binder-free high-quality pellet production method. The method comprises the following steps: 1) treating sintering rich powder by using a vertical dry-method roller milling process; (2) raw materials for pellet production are subjected to high-pressure roller milling, vertical roller milling, pre-infiltration and strong mixing pretreatment; (3) proper moisture of the mixture is adjusted through the pre-infiltration procedure, it is ensured that the water adding amount is controlled to be 0.5% in the pelletizing process, the rotating speed, the inclination angle and the filling rate parameters of a pelletizing disc are adjusted, and qualified green pellets with the green pellet falling strength, the green pellet moisture and green pellet plastic deformation meeting the roasting requirement are prepared; and (4) the roasting procedure is controlled, and the binder-free high-quality pellets are obtained. According to the method, the technical problems that the soft iron ore is difficult to settle and filter after being finely ground are effectively solved by utilizing a vertical roller grinding dry-method ore grinding production process, production and application of the high-quality binder-free pellets are successfully realized by combining a fine grinding material infiltration process, reasonable green pellet preparation and a belt type roasting thermal regulation, and the production cost of the pellets is remarkably reduced.

Description

Technical Field

[0001] The invention relates to the field of pre-iron pellet processing, and in particular to a method for producing high-quality binder-free pellets. Background Art

[0002] At present, my country's steel production is mainly based on the blast furnace-converter long process. The blast furnace charge structure has long been based on a comprehensive charge consisting of "high-alkalinity sintered ore + acidic pelletized ore + natural lump ore", of which sintered ore accounts for more than 70%. Sintering is the process with the most serious gaseous pollutant emissions before ironmaking. In comparison, the gaseous pollutant emissions of the pelletizing process are much lower than those of the sintering process, and the particulate matter emissions are only 1 / 7 of those of the sintering process. SO2 and NO x The emissions are 1 / 3 and 1 / 5 of the latter respectively. At present, the average ratio of pellets entering blast furnaces in China is less than 20%, and the pellets used are all pellets containing binder (bentonite). As far as the steel industry is concerned, vigorously developing pellet production is of great significance to promoting the green transformation of the steel industry. "Sintering to pellets" will be the main technical path for low-carbon emission reduction in the long process of blast furnace-converter.

[0003] However, the high cost of pellet production and the difficulty of sedimentation and filtration of soft iron ore after fine grinding make the product market competitiveness seriously insufficient and the pellet production capacity difficult to fully utilize. Therefore, it is necessary to develop a new high-quality pellet production method to overcome the above problems. Summary of the invention

[0004] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a method for producing high-quality binderless pellets. The method utilizes the vertical roller mill dry grinding production process to effectively solve the technical problems of difficult sedimentation and filtration of soft iron ore after fine grinding. Combined with the fine grinding material infiltration process, reasonable green ball preparation, and belt roasting thermal system, the production and application of high-quality binderless pellets are successfully realized, and the production cost of pellets is significantly reduced.

[0005] Technical solution: A method for producing high-quality binder-free pellets of the present invention comprises the following steps:

[0006] 1) Use vertical dry roller milling process to process sintered rich powder;

[0007] 2) Pre-treatment of raw materials used in pellet production by high pressure roller milling, vertical roller milling, pre-wetting, and intensive mixing;

[0008] 3) Adjust the appropriate moisture content of the mixture through the pre-wetting process to ensure that the amount of water added during the ball making process is controlled at 0.5%, and adjust the rotation speed, inclination angle, and filling rate parameters of the ball making disk to prepare qualified green balls whose drop strength, green ball moisture content, and green ball plastic deformation meet the roasting requirements;

[0009] 4) Control the roasting process so that the average compressive strength of the pellets is ≥2500N·P -1 , RI ≥ 80%, RDI +3.15 ≥96%, RSI≤18%, and obtain binder-free high-quality pellets.

[0010] Wherein, the vertical dry roller milling process in step 1) is carried out by a vertical dry roller mill.

[0011] Wherein, the high-pressure roller mill, vertical roller mill, pre-wetting and strong mixing pretreatment in step 2) are respectively performed by a high-pressure roller mill, a vertical dry roller mill, an auger humidifier and a vertical strong mixer.

[0012] Wherein, the pre-wetting process of step 3) is performed by an auger humidifier.

[0013] Wherein, the adjustment of the rotation speed, inclination angle and filling rate parameters of the pelletizing disk in step 3) is performed through a disc pelletizing machine.

[0014] Wherein, the roasting process in step 4) is carried out by a belt roasting machine.

[0015] Wherein, the vertical dry roller mill, auger humidifier and vertical intensive mixer are connected in sequence; the high-pressure roller mill is connected to the vertical intensive mixer.

[0016] Wherein, the vertical strong mixer, disc pelletizing machine and belt roasting machine are connected in sequence.

[0017] Wherein, limonite and specularite are added into the vertical dry roller mill.

[0018] Wherein, solid waste and iron ore concentrate are added into the high pressure roller mill.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention provides a set of key technologies for the production of binder-free high-quality pellets, and utilizes the vertical roller mill dry grinding production process to effectively solve the technical problems of difficult sedimentation and filtration of soft iron ore after fine grinding. Combined with the fine grinding material infiltration process, reasonable green ball preparation, and belt roasting thermal system, the production and application of high-quality binder-free pellets are successfully realized, and the production cost of pellets is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] In the figure, 1 is a vertical dry roller mill; 2 is a high-pressure roller mill; 3 is an auger humidifier; 4 is a vertical high-power mixer; 5 is a disc pelletizing machine; and 6 is a belt roasting machine. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0023] The method for producing high-quality binder-free pellets of the present invention comprises the following steps:

[0024] 1) A vertical dry roller milling process is used to process sintered rich powder with coarse particle size, high water content and strong viscosity; the vertical dry roller milling process is operated by a vertical dry roller mill 1.

[0025] 2) The raw materials used for pellet production are pretreated by high-pressure roller milling, vertical roller milling, pre-wetting and intensive mixing; the high-pressure roller milling, vertical roller milling, pre-wetting and intensive mixing pretreatment are respectively operated by a high-pressure roller mill 2, a vertical dry roller mill 1, an auger humidifier 3 and a vertical intensive mixer 4.

[0026] 3) Adjust the appropriate moisture content of the mixture through the pre-impregnation process to ensure that the amount of water added during the ball making process is controlled at 0.5%, and also adjust the rotation speed, inclination angle, and filling rate parameters of the ball making disk to prepare qualified green balls whose falling strength, green ball moisture, and green ball plastic deformation meet the roasting requirements; the pre-impregnation process is operated by the auger humidifier 3; the rotation speed, inclination angle, and filling rate parameters of the ball making disk are adjusted by the disc ball making machine 5.

[0027] 4) Reasonable roasting thermal system control, for the green ball roasting system with high proportion of brown and hematite (about 80%) and large burn loss (about 7.5%), adopt the roasting strategy of "strengthening drying, increasing preheating pellet temperature, and moving the roasting high point temperature forward". Control the roasting process to make the average compressive strength of the pellet ≥2500N·P -1 , RI ≥ 80%, RDI +3.15 ≥96%, RSI≤18%, and high-quality pellets without binder are obtained; the roasting process is operated by a belt roaster 6.

[0028] The vertical dry roller mill 1, the auger humidifier 3, and the vertical intensive mixer 4 of the present invention are connected in sequence; the high-pressure roller mill 2 is connected to the vertical intensive mixer 4. The vertical intensive mixer 4, the disc pelletizer 5, and the belt roaster 6 are connected in sequence. Limonite and specularite are added to the vertical dry roller mill 1. Solid waste and iron concentrate are added to the high-pressure roller mill 2.

[0029] The present invention realizes a wide range of raw materials for pellet production, broadens the variety of pellet materials, and solves the industry problem that the high proportion of non-mainstream low-priced ores such as mirror iron ore powder and high-crystallization water brown hematite in the raw materials for pellets leads to difficulty in pelletizing and roasting. The present invention achieves a breakthrough in the production technology of binderless pellets, filling the gap in the preparation technology of binderless pellets in the field of pellet processing at home and abroad. The present invention develops and creates a set of high-proportion hematite roasting pellet production process technology using high-proportion dry finely ground ore powder as raw materials.

[0030] The present invention provides a set of key technologies for producing high-quality binderless pellets. The vertical roller mill dry grinding production process is used to effectively solve the technical problems of difficult sedimentation and filtration of soft iron ore after fine grinding. Combined with the fine grinding material infiltration process, reasonable green ball preparation, and belt roasting thermal system, the production and application of high-quality binderless pellets are successfully realized, and the production cost of pellets is significantly reduced.

Claims

1. A method for producing high-quality binder-free pellets, characterized in that: The steps include: 1) Use vertical dry roller milling process to process sintered rich powder; 2) Pre-treatment of raw materials used in pellet production by high pressure roller milling, vertical roller milling, pre-wetting, and intensive mixing; 3) Adjust the appropriate moisture content of the mixture through the pre-wetting process to ensure that the amount of water added during the ball making process is controlled at 0.5%, and adjust the rotation speed, inclination angle, and filling rate parameters of the ball making disk to prepare qualified green balls whose drop strength, green ball moisture content, and green ball plastic deformation meet the roasting requirements; 4) Control the roasting process so that the average compressive strength of the pellets is ≥2500N·P -1 , RI ≥ 80%, RDI +3.15 ≥96%, RSI≤18%, and obtain binder-free high-quality pellets.

2. The method for producing high-quality binder-free pellets according to claim 1, characterized in that: The vertical dry roller milling process in step 1) is carried out by means of a vertical dry roller mill (1).

3. The method for producing high-quality binder-free pellets according to claim 2, characterized in that: The high-pressure roller mill, vertical roller mill, pre-wetting and strong mixing pretreatment in step 2) are respectively operated by a high-pressure roller mill (2), a vertical dry roller mill (1), an auger humidifier (3) and a vertical strong mixer (4).

4. The method for producing high-quality binder-free pellets according to claim 3, characterized in that: The pre-wetting process of step 3) is performed by an auger humidifier (3).

5. The method for producing high-quality binder-free pellets according to claim 4, characterized in that: The parameters of adjusting the rotation speed, inclination angle and filling rate of the pelletizing disk in step 3) are operated by the disc pelletizing machine (5).

6. The method for producing high-quality binder-free pellets according to claim 5, characterized in that: The roasting process in step 4) is carried out by a belt roasting machine (6).

7. The method for producing high-quality binder-free pellets according to claim 6, characterized in that: The vertical dry roller mill (1), the auger humidifier (3), and the vertical intensive mixer (4) are connected in sequence; the high-pressure roller mill (2) is connected to the vertical intensive mixer (4).

8. The method for producing high-quality binder-free pellets according to claim 7, characterized in that: The vertical strong mixer (4), disc pelletizing machine (5) and belt roasting machine (6) are connected in sequence.

9. The method for producing high-quality binder-free pellets according to claim 8, characterized in that: Limonite and specularite are added into the vertical dry roller mill (1).

10. The method for producing high-quality binder-free pellets according to claim 9, characterized in that: Solid waste and iron ore concentrate are added into the high pressure roller mill (2).

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