Binderless pelletizing method using phosphate rock powder and silica stone powder as raw materials

Abstract

The application discloses a binderless balling method using phosphate rock powder and silica powder as raw materials, which comprises the following steps: a. mixing and grinding, wherein the phosphate rock powder and the silica powder are mixed and ground by a ball mill until the 300-mesh passing rate is 98%, forming mixed powder; b. preparing mother balls, wherein the mixed powder is added into a mother ball machine, and the mixed powder is nucleated due to rubbing in the process of high-speed movement, and then granulated into balls, forming mother balls; c. preparing green balls, wherein the prepared mother balls are added into a pot-type granulator, and the mother balls gradually grow into 16-40mm green balls after 2.5-3h balling time; and d. discharging, wherein when the particle size reaches the requirement, the pot-type granulator is discharged through a discharge door, and the prepared green balls are smooth without burrs and have high strength. The application uses the phosphate rock powder and the silica powder as raw materials to prepare balls without using a binder, and the introduction of impurities is avoided, so that the grade of the product is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a balling technology, in particular to a binderless balling method using phosphorite powder and silica powder as raw materials. BACKGROUND

[0002] The current phosphorite powder balling method mainly uses a disc balling machine or a ball press, and before balling, the phosphorite powder needs to be mixed with a binder to make the balling raw material have certain viscosity. This balling method has the following disadvantages:

[0003] 1. The use of a binder will introduce impurities, thereby reducing the grade of the phosphorite.

[0004] 2. The balling time is short, and the green ball strength is low.

[0005] 3. The ball pocket size of the ball press is fixed, the balling particle size is fixed size, and different particle sizes of green balls cannot be manufactured.

[0006] 4. The disc balling machine or the ball press is an open device, and the dust is large on site, and the environmental protection effect is difficult to guarantee. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the disadvantages of the prior art, and to provide a binderless balling method using phosphorite powder and silica powder as raw materials, which is reasonable in design, high in grade, high in strength, adjustable in particle size, and does not use a binder.

[0008] The technical scheme of the present application is:

[0009] A binderless balling method using phosphorite powder and silica powder as raw materials, comprising the following steps:

[0010] a. Mixing and grinding, using a ball mill to mix and grind the phosphorite powder and the silica powder, grinding to 98% passing rate of 300 mesh, forming a mixed powder;

[0011] b. Preparing mother balls, adding the mixed powder into a mother ball machine, the mother ball machine uses the reverse motion between the low-speed rotating drum in the clockwise direction and the high-speed rotating rotor in the counterclockwise direction to stir the mixed powder at high speed, and the scraper is arranged at the bottom and the wall of the drum respectively, the scraper cleans the inner wall of the drum while changing the motion direction of the mixed powder to form a specific flow field under the action of the inclined drum, the mixed powder is nucleated due to the rubbing in the high-speed motion process, and then granulated into balls to form mother balls;

[0012] c. Preparing green balls, adding the prepared mother balls into a pot granulator, and after 2.5-3h of balling time, the mother balls gradually grow into 16-40mm green balls;

[0013] d, when the particle size reaches the requirement, the pot granulator is discharged through the discharge door, and the prepared green ball has a smooth surface without burrs and high strength.

[0014] Further: in step c, the pot granulator drives the cylinder to rotate by using a transmission device and a bridge device, and the axis of the cylinder forms a specific angle with the horizontal plane; after the mother ball is added into the cylinder through the feeding port, water is sprayed into the cylinder, and the wet powder gradually forms a ball core while rolling; the wet ball core gradually grows into a particle under continuous rolling, friction and collision, thereby forming the green ball.

[0015] Further: in step b, the high-speed rotating rotor in the mother ball machine uniformly mixes the fine phosphor powder and silica powder, and forms the mother ball meeting the strength requirement.

[0016] In step c, the green ball is gradually grown in the closed pot granulator, and the particle size and strength of the green ball are adjusted by controlling the rotation time of the pot granulator.

[0017] Further: the ratio of the phosphor powder and the silica powder is adjusted, so that the molar ratio of SiO2 / CaO is 0.8-1.2.

[0018] The beneficial effects of the present application are:

[0019] 1. The present application uses phosphor powder and silica powder as raw materials for ball making, does not use a binder, and eliminates the introduction of impurities, thereby improving the grade of the product.

[0020] 2. The present application adopts a sealed production process, and the dust does not spread out, which is environmentally friendly; and the particle size and strength of the green ball can be adjusted by controlling the rotation time of the pot granulator.

[0021] 3. The present application discards the traditional disc balling method and the roller balling method, and adopts the combined balling method of the mother ball machine and the pot granulator, so that the green ball has the advantages of high grade, high strength and adjustable particle size, and has good economic benefits after popularization. DETAILED DESCRIPTION EMBODIMENT

[0022] A binderless balling method using phosphor powder and silica powder as raw materials, comprising the following steps:

[0023] Phosphate rock powder and silica powder are mixed and ground in a ball mill until a 300-mesh pass rate of 98% is achieved. This mixture is then used to produce master pellets. The working principle of the master pellet mill is to utilize the counter-clockwise rotation of a low-speed clockwise drum and a high-speed counter-clockwise rotor to rapidly agitate the materials. Scrapers are arranged at the bottom and walls of the drum. These scrapers, along with the inclined drum, work together to change the direction of material movement, creating a specific flow field. During this high-speed motion, the powdery material is "kneaded" and nucleated, thus forming pellets. The resulting master pellets are then fed into a pot pellet mill. After a pelletizing time of 2.5–3 hours, the master pellets gradually grow into green pellets of 16–40 mm. The working principle of a pot pellet mill is that the transmission device drives the cylinder to rotate via a bridge device, and the cylinder axis forms a specific angle with the horizontal plane. When the powder is added into the cylinder through the feed inlet, water is sprayed into the cylinder. The moistened powder gradually forms nuclei while tumbling. Under continuous tumbling, friction, and collision, the moistened nuclei gradually grow into pellets. When the particle size reaches the required level, they are discharged through the discharge gate. The resulting green pellets have a smooth, burr-free surface and high strength.

[0024] Inside the pelletizing machine, a high-speed rotating rotor is used to mix the fine powdered phosphate rock and silica powder evenly, forming pellets of a certain strength. Subsequently, the pellets gradually grow in the closed pelletizing pot cavity. The particle size and strength of the green pellets can be adjusted by controlling the rotation time of the pot pelletizer.

[0025] The ratio of phosphate rock powder to silica powder was adjusted to achieve a SiO2 / CaO molar ratio of 0.8–1.2. SiO2 acts as a flux, reacting with CaO to form low-melting-point silicates, increasing the fluidity of the reactants, effectively expanding the contact area, accelerating the reaction rate, and promoting the volatilization of elemental phosphorus. However, excessive SiO2 reduces the phosphorus grade, raises the liquidus temperature, lowers the driving force of the carbothermic reduction reaction, and inhibits phosphorus volatilization to some extent.

[0026] Furthermore, different diameter pot pellet mills have different suitable speeds. In principle, the larger the diameter, the lower the suitable speed. The specific parameters of the pot pellet mill can be adjusted at any time according to the actual situation, which is something that those skilled in the art can achieve.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications made based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A binder-free pelletizing method using phosphate rock powder and silica powder as raw materials, characterized in that: Includes the following steps: a. Mixing and grinding: Use a ball mill to mix and grind the phosphate rock powder and silica powder until the 300 mesh has a passing rate of 98%, forming a mixed powder; b. Making mother balls: The mixed powder is added to a mother ball machine. The mother ball machine uses the counter-rotation between a clockwise rotating drum at low speed and a counter-clockwise rotating rotor at high speed to stir the mixed powder at high speed. Scrapers are arranged at the bottom and wall of the drum. While cleaning the layer on the inner wall of the drum, the scrapers work together with the inclined drum to change the direction of movement of the mixed powder and form a specific flow field. During the high-speed movement, the mixed powder is kneaded and formed into nuclei, and then granulated into balls to form mother balls. c. Producing green pellets: The prepared mother pellets are added to a pot pellet mill. After a pelletizing time of 2.5 to 3 hours, the mother pellets gradually grow into green pellets of 16 to 40 mm. d. Discharge: When the particle size meets the requirements, the pot pellet mill discharges the pellets through the discharge gate. The resulting green pellets have a smooth, burr-free surface and high strength.

2. The binder-free pelletizing method using phosphate rock powder and silica powder as raw materials according to claim 1, characterized in that: In step c, the pot pellet mill uses a transmission device and a bridge device to drive the cylinder to rotate, and the cylinder axis forms a specific angle with the horizontal plane. When the mother pellet is added into the cylinder through the feed port, water is sprayed into the cylinder. The wet powder gradually forms a nucleus while rolling. The wet nucleus gradually grows into a pellet under continuous rolling, friction and collision, forming the green pellet.

3. The binder-free pelletizing method using phosphate rock powder and silica powder as raw materials according to claim 1, characterized in that: In step b, the mother ball machine uses a high-speed rotating rotor to mix the fine powdered phosphate rock powder and silica powder evenly and form the mother ball that meets the strength requirements. In step c, the mother pellets gradually grow inside the enclosed pot pellet mill. The particle size and strength of the green pellets are adjusted by controlling the rotation time of the pot pellet mill.

4. The binder-free pelletizing method using phosphate rock powder and silica powder as raw materials according to claim 1, characterized in that: Adjust the ratio of phosphate rock powder and silica powder to make the SiO2 / CaO molar ratio 0.8 to 1.2.