A method for making pellet ore from low-grade cyclone tailings

Abstract

The present application relates to the field of phosphorus chemical technology, and specifically discloses a method for making pellet ore from low-grade cyclone tailings, comprising the following steps: step 1: obtaining low-grade phosphate rock powder by a cyclone separation process; step 2: dehydrating the phosphate rock powder obtained in step 1 to reduce the moisture content to 12%-18%; step 3: drying the phosphate rock powder obtained in step 2; step 4: taking ingredients according to the production formula, adding 1-10 parts of phosphoric acid and 1-5 parts of adhesive by percentage by mass; through a ball making machine, obtaining phosphate rock powder bonded pellet ore; step 5: sintering the pellet ore obtained in step 4 to obtain phosphate ore pellets. The purpose of this patent is to solve the problem of low-grade phosphate tailings that do not meet the requirements after the existing cyclone being piled up and abandoned, and the utilization rate is not high.

Description

Technical Field

[0001] This invention relates to the field of phosphorus chemical technology, and in particular to a method for producing pellets from low-grade swirl tailings. Background Technology

[0002] Phosphate rock has a wide range of uses, primarily for producing phosphate fertilizers, and can also be used to manufacture yellow phosphorus, phosphoric acid, phosphates, and other phosphates. Phosphate rock is graded based on its phosphorus pentoxide (P2O5) content; the higher the content, the higher the grade. Rich phosphate ore is preferred in production. The overall grade of phosphate rock in my country is only 17%, and the average grade of recoverable reserves is only 23%, far below the global average of 30%. Lower-grade phosphate rock with a P2O5 content of less than 20% accounts for approximately 60% of the total, while high-grade phosphate rock with a P2O5 content of more than 30% accounts for only 9.4%.

[0003] With the large-scale exploitation of phosphorus resources in China, high-grade phosphate rock is gradually facing the challenges of declining production and grade; the price of rich ore is constantly rising; after beneficiation, high-grade phosphate rock powder is used to process other phosphate products, while the low-grade phosphate rock tailings that do not meet the requirements after hydrocyclone separation are difficult to process due to their high water content. Limited by geographical location or production capacity, a large amount of low-grade phosphate rock tailings are piled up or abandoned, failing to be effectively utilized. Existing technologies include methods for processing phosphate rock powder from high-grade phosphate rock into phosphate rock powder pellets for use in yellow phosphorus production. However, existing methods use bentonite, clay, and water glass as binders to produce pellets, which reduces the phosphate rock powder content within the pellets, thus lowering the grade of the pellets. Furthermore, the pellets lack heat resistance and strength, making them prone to bursting during yellow phosphorus production, affecting the production reaction. Moreover, current production technologies mainly use phosphate rock powder directly for production, rarely utilizing the low-grade hydrocyclone tailings after beneficiation.

[0004] Therefore, it is necessary to study a method for producing pellets from low-grade vortex tailings to solve the problems of vortex tailings accumulation, insufficient utilization, and unstable quality of pellets produced by existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem solved by this invention is to provide a method for producing pellets from low-grade swirl tailings, thereby solving the problems of low-grade phosphate ore tailings that do not meet the requirements being piled up and abandoned after swirl, resulting in low utilization rates, and the unstable quality of pellets produced by existing technologies.

[0006] To solve the above problems, the technical solution adopted by the present invention is: a method for producing pellets from low-grade cyclone tailings, comprising the following steps: Step 1: obtaining low-grade phosphate rock powder through a cyclone separation process; Step 2: dehydrating the phosphate rock powder obtained in Step 1 to reduce the moisture content to 12%-18%; Step 3: drying the phosphate rock powder obtained in Step 2; Step 4: according to the production formula, adding 1-10 parts of phosphoric acid, 1-5 parts of binder, and 1-2 parts of silica powder or α-gypsum powder per 100 parts by weight of phosphate rock powder; and producing phosphate rock powder-bonded pellets using a pelletizing machine; Step 5: sintering the pellets obtained in Step 4 to obtain phosphate rock pellets.

[0007] The beneficial effects of this scheme are as follows: It transforms low-grade phosphate ore into pellets, thereby increasing the phosphorus content within the ore and converting it into high-grade phosphate ore. This allows for the full utilization of low-grade phosphate ore, reducing the amount of rich ore used in production and thus lowering the costs of mining and beneficiation of rich ore. Furthermore, it effectively reduces the production cost of phosphate products. Simultaneously, it solves the problem of low-grade phosphate ore accumulation, reducing the waste of phosphate resources. The production process of this scheme is stable, and the resulting pellets have a strength of 800N-1200N. They can remain stable without cracking for 30-60 minutes in a high-temperature environment of 800-1200°C, demonstrating stable reaction. Given the high content of low-grade phosphate ore in my country, the application prospects of this scheme are broad.

[0008] Furthermore, steps 3 and 5 both utilize yellow phosphorus tail gas as the combustion medium for heating. The main component of yellow phosphorus tail gas is carbon monoxide, with a content of approximately 75-85%, hydrogen accounting for 10-15%, and methane accounting for 4%. By purifying the yellow phosphorus tail gas and using it as fuel, and employing a yellow phosphorus tail gas combustion boiler to dry phosphate rock powder and sinter phosphate rock pellets, comprehensive utilization of the yellow phosphorus tail gas is achieved. Compared to constructing separate phosphate rock pelletizing units and separate yellow phosphorus production units, energy consumption is reduced by 11%, effectively lowering the overall energy consumption index.

[0009] Furthermore, the drying temperature in step 3 is 150–1000℃, and the moisture content of the dried phosphate rock powder is controlled to be ≤12%. Reducing the moisture content facilitates subsequent processing.

[0010] Furthermore, the phosphoric acid added in step 4 is residual raffinate with a concentration of 70%. Using waste acid from wet-process phosphoric acid production for pellet production improves the grade of phosphate rock pellets and enables the reuse of waste acid.

[0011] Furthermore, the adhesive added in step 4 is one or more of aluminum phosphate, magnesium, sodium, and organophosphorus high-performance adhesives.

[0012] Furthermore, the sintering temperature in step 5 is controlled at 500℃~1200℃, and the moisture content of the sintered phosphate ore pellets is 1%~10%. Controlling the sintering temperature and moisture content ensures the strength and thermal stability of the finished phosphate ore pellets.

[0013] Furthermore, the particle size of the granulated ore is 30–50 mm. Within this particle size range, it can be well mixed to produce yellow phosphorus.

[0014] Furthermore, the phosphate rock powder has a particle size of 10 mm or less, which facilitates uniform mixing during pellet production.

[0015] Furthermore, the pelletizing machine in step 4 includes a material bin and a pelletizing box. The material bin is divided into a mixing box and a recycling box by a sliding plate connected to the middle of the material bin. The mixing box is located above the recycling box. The discharge port of the mixing box is connected to the inlet of the pelletizing box through a feeding pipe. The mixing box is equipped with a mixing mechanism, which includes a motor located at the top of the material bin. The output shaft of the motor extends into the mixing box and is connected to a stirring shaft. The stirring shaft is detachably connected to a stirring rod. The upper end of the stirring shaft is rotatably connected to the top of the mixing box, and the lower end of the stirring shaft is detachably connected to a cylindrical cam. The sliding plate is slidably connected to the cylindrical cam. One end of the stirring rod is slidably connected to a scraper. The long side of the scraper is in contact with the inside of the mixing box, and the bottom of the scraper is in contact with the sliding plate.

[0016] 1. The stirring rod rotates, thereby mixing the phosphate rock powder and auxiliary materials evenly. The stirring rod, which is connected to a scraper, scrapes off the mixture adhering to the side wall of the mixing box when it rotates.

[0017] 2. As the mixing shaft rotates, it drives the cylindrical cam to rotate. Since the sliding plate is connected to the side wall of the material box in the vertical direction, the sliding plate does not follow the rotation of the cam. The rotation of the cylindrical cam drives the sliding plate to move up and down. When the sliding plate moves upward, it pushes the scraper to follow the sliding plate upward. When the sliding plate moves downward, the scraper moves downward under the action of weight. This causes the scraper to follow the sliding plate to move up and down in the vertical direction, thereby scraping off the mixed material at different heights on the side wall and increasing the scraping area of ​​the scraper.

[0018] 3. When the slide plate moves downward, it compresses the space inside the recovery box, allowing the gas inside the recovery box to enter the mixing box through the second one-way valve on the slide plate. At the same time, the gas entering the mixing box creates a bubbling effect, which in turn promotes mixing and further promotes the uniform mixing of phosphate rock powder and auxiliary materials. When the slide plate moves upward, it compresses the space inside the mixing box, and the gas inside the mixing box is discharged through the third one-way valve at the top of the mixing box. This allows the slide plate to accelerate the discharge of CO2 generated during the mixing of phosphate rock powder and auxiliary materials, reducing the amount of CO2 gas remaining in the mixture and preventing the formation of air holes in the pellets, which would affect the strength of the final pellets.

[0019] Furthermore, the discharge port of the pelletizing box is connected to a downwardly inclined discharge channel, and a cover plate is rotatably connected to the end of the discharge channel. The bottom of the discharge channel is provided with several return holes, and a return channel is connected to the return holes. One end of the return channel is connected to the return port of the recycling box. The return port is provided with a first one-way valve that allows materials to enter the recycling box only from the return channel. The slide plate is provided with a second one-way valve that allows gas to flow from the recycling box to the mixing box only. The top of the mixing box is provided with a third one-way valve that allows gas to flow from the mixing box to the outside only.

[0020] As the slide plate moves upward, the space inside the recovery box increases, creating negative pressure. This negative pressure draws in material and gas from the return channel through the first one-way valve, reducing the gas level in the return channel and creating further negative pressure. This negative pressure then draws in unagglomerated material that was carried along with the pellets as they passed through the discharge channel. Because the pellets are relatively large, they roll towards the discharge gate under gravity, pushing it open and discharging the material. The reciprocating motion of the slide plate creates a piston-like extraction effect, continuously drawing unagglomerated material through the first one-way valve into the recovery box for storage. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the pelletizing machine of the present invention.

[0023] Figure 3 This is a schematic diagram of the ball-pressing mechanism of the ball-making machine of the present invention. Detailed Implementation

[0024] The reference numerals in the accompanying drawings include: material bin 1, mixing bin 11, stirring rod 110, scraper 111, third check valve 112, cam 113, feeding channel 114, slide plate 12, second check valve 121, recovery bin 13, baffle net 131, first check valve 132, return channel 133, pelletizing box 2, discharge channel 21, cover plate 22, slide rail 23, and motor 3.

[0025] The following detailed description illustrates the specific implementation method:

[0026] Example 1 is as attached. Figure 1As shown: Low-grade phosphate rock from cyclone tailings is used to produce yellow phosphorus. The requirements for producing yellow phosphorus from cyclone tailings are as follows: by mass fraction, P2O5 content 12%–32%, CaO 30%–60%, MgO ≤5%, SiO2 content 5%–28%, (Al2O3+Fe2O) ≤10.0%, and moisture content 1%–50%; the composition of low-grade phosphate rock powder from cyclone tailings by mass fraction is as follows: P2O5 content 5%–20%, CaO 30%–60%, MgO ≤5%, SiO2 ≤20%, (Al2O3+Fe2O) ≤10.0%, and moisture content 20%–60%.

[0027] Step 1: Obtain low-grade phosphate rock powder through a hydrocyclone separation process; the composition of the low-grade phosphate rock powder from the hydrocyclone tailings, by mass fraction, is: P2O5 content 13%, CaO 30%, MgO 3%, SiO2 13%, (Al2O3+Fe2O) 3.0%, moisture content 38%; phosphate rock powder particle size is less than 10mm;

[0028] Step 2: Dewater the phosphate rock powder obtained in Step 1 using a filter press to reduce the moisture content of the phosphate rock powder to 15%.

[0029] Step 3: The phosphate rock powder obtained in Step 2 is fed into the dryer through a metering and conveying device. The dryer uses a yellow phosphorus tail gas combustion device. After washing and purification, the effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The drying temperature inside the dryer is controlled at 800℃. A counter-current drying method is adopted, and the moisture content after drying is controlled at 8%.

[0030] Step 4: Add 8 parts of phosphoric acid by weight, using residual raffinate with a phosphoric acid concentration of 70%, add 1 part of silica powder, and add 4 parts of aluminum phosphate as a binder; use a pelletizing machine to obtain phosphate rock powder agglomerates.

[0031] Step 5: The pellets obtained in Step 4 are fed into a sintering machine for sintering. The combustion device of the sintering machine adopts a yellow phosphorus tail gas combustion device. The yellow phosphorus tail gas after washing and purification is introduced into the combustion device. The effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The sintering temperature is 1100℃. The moisture content of the pellets after sintering is 1%, and phosphate ore pellets are obtained. The particle size of the pellets is 40mm.

[0032] The obtained pellets were tested and found to have a strength of 1000N, and could remain intact for 50 minutes at a high temperature of 1200°C without cracking.

[0033] Based on the current energy consumption and tail gas utilization of yellow phosphorus production, the standard energy consumption for yellow phosphorus production is 2.8 tons of standard coal equivalent per ton of product. Assuming a separate pelletizing unit, the energy consumption for 1 ton of pellets is 0.02871 tons of standard coal equivalent. The industry average for yellow phosphorus production is 11.5 tons of phosphate rock, meaning the energy required to produce 1 ton of yellow phosphorus from pelletized phosphate rock is 0.3302 tons of standard coal equivalent. The combined energy consumption of the two units is 3.13 tons of standard coal equivalent per ton of yellow phosphorus product. However, if the two units are combined and the combustion devices in the dryer and sintering machine are replaced with yellow phosphorus combustion devices, fully utilizing the yellow phosphorus tail gas, the total energy consumption for both products will be reduced to 2.8 tons of standard coal equivalent, resulting in an 11% reduction in overall energy consumption.

[0034] Step 4: The pelletizing machine used to manufacture pellets of ore, such as... Figure 2 As shown, the pelletizing machine includes a material bin 1 and a pelletizing bin 2. The material bin 1 is divided into a mixing bin 11 and a recycling bin 13 by a sliding plate 12 connected to the middle of the material bin 1. The mixing bin 11 is located above the recycling bin 13. The discharge port of the mixing bin 11 is connected to the inlet of the pelletizing bin 2 through a feeding pipe. The mixing bin 11 is equipped with a mixing mechanism, which includes a motor 3 located at the top of the material bin 1. The output shaft of the motor 3 extends into the mixing bin 11 and is connected to a stirring shaft. The stirring shaft is fixed with stirring rods 110 by bolts. Multiple stirring rods 110 are arranged vertically along the stirring shaft. The upper end of the stirring shaft is rotatably connected to the top of the mixing bin 11, and the lower end of the stirring shaft is fixed with a cylindrical cam 113 by bolts. The sliding plate 12 is slidably connected to the cylindrical cam 113. Two of the stirring rods 110 are slidably connected to scrapers 111 at one end. The long side of the scraper 111 is in contact with the inside of the mixing bin 11, and the bottom of the scraper 111 is in contact with the sliding plate 12.

[0035] like Figure 3 As shown, the ball-forming box 2 uses an existing roller-type ball-forming mechanism. The mixed material enters the middle of two relatively rotating rollers through the feed port. The rollers, which rotate at the same speed and in opposite directions, compress the material. The unit forming pressure of the material increases from small to large. The forming pressure reaches its maximum value at the center line of the rollers. After the material passes this line, the forming pressure decreases rapidly, causing the material to enter the ball-removing state and successfully remove the balls. After removing the balls, the material slides down to the discharge port through the arc-shaped slide 23 set below the rollers.

[0036] The discharge port of the pelletizing box 2 is connected to a downwardly inclined discharge channel 21. The end of the discharge channel 21 is hinged to a cover plate 22 with air holes. A torsion spring is provided at the hinge point between the cover plate 22 and the discharge channel 21, so that the cover plate 22 is tightly attached to the end of the discharge port. The bottom of the discharge channel 21 is provided with several return holes and a return channel 133 is connected to the return channel 133. One end of the return channel 133 is connected to the return port of the recycling box 13. The return port is provided with a first one-way valve 132 that allows materials to enter the recycling box 13 only from the return channel 133. The slide plate 12 is provided with multiple second one-way valves 121 that allow gas to flow from the recycling box 13 to the mixing box only. The top of the mixing box is provided with a third one-way valve 112 that allows gas to flow from the mixing box to the outside only. The upper end of the recycling box 13 is fixed with a baffle net 131 by screws. The baffle net 131 can be made of non-woven fabric, metal mesh with a pore size of less than 10mm, etc. Unagglomerated materials are recycled into the recycling box 13 through the return hole and return channel 133.

[0037] When using, take the phosphate rock powder and auxiliary materials according to the formula and put them into the mixing box 11. Start the motor 3. The rotation of the motor 3 drives the stirring shaft to rotate, thereby causing the stirring rod 110 to rotate, and then mix the phosphate rock powder and auxiliary materials evenly. When the stirring rod 110 connected to the scraper 111 rotates, the scraper 111 scrapes off the mixture adhering to the side wall of the mixing box. While the stirring shaft rotates, it drives the cylindrical cam 113 to rotate. Since the slide plate 12 is slidably connected to the side wall of the material box 1 in the vertical direction, the slide plate 12 does not rotate with the cam 113. The slide plate 12 slides along the curved groove of the cylindrical cam 113, thereby moving up and down due to the rotation of the cylindrical cam 113. When the slide plate 12 moves upward, it pushes the scraper 111 to move upward with the slide plate 12. When the slide plate 12 moves downward, the scraper 111 moves downward under the action of weight, thereby causing the scraper 111 to move up and down in the vertical direction with the slide plate 12, so as to scrape off the mixed material at different heights on the side wall and increase the scraping area of ​​the scraper 111. After the mixing is completed, the feeding door of the mixing box 11 is opened, and the material is sent to the pelletizing box 2 through the feeding pipe to make pellets. After the pelletizing box 2 completes the pelletizing, the pellets slide down from the discharge channel 21 to the discharge door, where they are collected and enter the next processing step. At the same time as the pelletizing machine, the second batch of phosphate rock powder and auxiliary materials are put into the mixing box 11 to start mixing.

[0038] When the slide plate 12 moves downward, it compresses the space inside the recovery box 13, thereby allowing the gas inside the recovery box 13 to enter the mixing box 11 through the second one-way valve 121 on the slide plate 12. At the same time, the gas entering the mixing box creates a bubbling effect on the mixture, thus achieving a mixing effect and further promoting the uniform mixing of phosphate rock powder and auxiliary materials. When the slide plate 12 moves upward, it compresses the space inside the mixing box 11, and the gas inside the mixing box 11 is discharged from the third one-way valve 112 at the top of the mixing box 11. This allows the slide plate 12 to accelerate the discharge of CO2 generated during the mixing of phosphate rock powder and auxiliary materials in the mixing box 11, reducing the amount of CO2 gas remaining in the mixture and preventing the formation of air holes in the pellets, which would affect the strength of the final pellets.

[0039] Simultaneously, as the slide plate 12 moves upward, the space inside the recovery box 13 increases, generating negative pressure. This negative pressure then draws in materials and gas from the return channel 133 through the first one-way valve 132, reducing the gas level in the return channel 133 and creating further negative pressure. This draws in unagglomerated materials that were carried along with the pellets as they passed through the discharge channel 21 through the return hole. Because the agglomerated pellets are relatively large, they roll towards the discharge gate of the discharge channel 21 under gravity, pushing open the cover plate 22 and being discharged. Through the reciprocating motion of the slide plate 12, unagglomerated materials are continuously drawn into the recovery box 13 through the first one-way valve 132 for storage. Furthermore, due to the baffle net 131, materials in the recovery box 13 cannot pass through and therefore will not enter the mixing box 11 through the second one-way valve 121.

[0040] Example 2 is attached. Figure 1 As shown, the difference from Example 1 is that;

[0041] Step 1: Low-grade phosphate rock powder is obtained through hydrocyclone separation process. The particle size of the phosphate rock powder is less than 8mm. The composition of the low-grade phosphate rock powder in the hydrocyclone tailings is as follows by mass fraction: P2O5 content 12%, CaO 31%, MgO 3%, SiO2 16%, (Al2O3+Fe2O) 4.0%, and moisture content 34%.

[0042] Step 2: Dewater the phosphate rock powder obtained in Step 1 using a filter press to reduce the moisture content of the phosphate rock powder to 13%.

[0043] Step 3: The phosphate rock powder obtained in Step 2 is fed into the dryer through a metering and conveying device. The dryer uses a yellow phosphorus tail gas combustion device. After washing and purification, the effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The drying temperature inside the dryer is controlled at 850℃. A counter-current drying method is adopted, and the moisture content after drying is controlled at 6%.

[0044] Step 4: Add 9 parts of phosphoric acid by weight, using residual raffinate with a phosphoric acid concentration of 70%; add 3 parts of magnesium phosphate as a binder and 2 parts of α-gypsum powder; and use a pelletizing machine to obtain phosphate rock powder binder pellets.

[0045] Step 5: The pellets obtained in Step 4 are fed into a sintering machine for sintering. The combustion device of the sintering machine adopts a yellow phosphorus tail gas combustion device. The yellow phosphorus tail gas after washing and purification is introduced into the combustion device. The effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The sintering temperature is 1150℃. The moisture content of the pellets after sintering is 1%, and phosphate ore pellets are obtained. The particle size of the pellets is 35mm.

[0046] The obtained pellets were tested and found to have a strength of 1200N, and could remain intact for 60 minutes at a high temperature of 1200°C without cracking.

[0047] Example 3 is attached. Figure 1 As shown, the difference from Embodiment 1 and Embodiment 2 is that;

[0048] Step 1: Obtain low-grade phosphate rock powder through hydrocyclone separation process; the composition of low-grade phosphate rock powder of hydrocyclone tailings by mass fraction is: P2O5 content 14%, CaO 31%, MgO 2%, SiO2 17%, (Al2O3+Fe2O) 2.0%, and moisture content 34%.

[0049] Step 2: Dewater the phosphate rock powder obtained in Step 1 using a filter press to reduce the moisture content of the phosphate rock powder to 11%.

[0050] Step 3: The phosphate rock powder obtained in Step 2 is fed into the dryer through a metering and conveying device. The dryer uses a yellow phosphorus tail gas combustion device. After washing and purification, the effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The drying temperature inside the dryer is controlled at 700℃. A counter-current drying method is adopted, and the moisture content after drying is controlled at 5%.

[0051] Step 4: Add 7 parts phosphoric acid by weight, using residual raffinate with a phosphoric acid concentration of 70%, and 4 parts aluminum phosphate as a binder; use a pelletizing machine to produce phosphate rock powder agglomerates.

[0052] Step 5: The pellets obtained in Step 4 are fed into a sintering machine for sintering. The combustion device of the sintering machine adopts a yellow phosphorus tail gas combustion device. The yellow phosphorus tail gas after washing and purification is introduced into the combustion device. The effective combustion component mass fraction in the yellow phosphorus tail gas is 95%. The sintering temperature is 1000℃. The moisture content of the pellets after sintering is 1%, and phosphate ore pellets are obtained. The particle size of the pellets is 45mm.

[0053] The obtained pellets were tested and found to have a strength of 1100N, and could remain intact for 45 minutes at a high temperature of 1100°C without cracking.

[0054] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for producing pellet ore from low-grade cyclone tailings, characterized in that: The following steps are involved: Step 1: obtaining low-grade phosphate rock powder through a cyclone separation process; Step 2: Dehydrating the phosphate rock powder obtained in step 1 to reduce the moisture content to 13%-18%; Step 3: drying the phosphate rock powder obtained in step 2; Step 4: adding 1-10 parts of phosphoric acid, 1-5 parts of binder, and 0.5-3 parts of silica powder or α-gypsum powder to every 100 parts by mass of phosphate rock powder; and making phosphate rock powder bonded ball ore through a ball making machine; Step 5: Sintering the pellets obtained in step 4 to obtain phosphate pellets; The ball making machine of step 4 comprises a material box and a ball making box, the material box is divided into a mixing box and a recycling box by a slide plate slidably connected to the middle of the material box, the mixing box is located above the recycling box, and the discharge port of the mixing box is connected to the feed port of the ball making box through a feeding pipe; a mixing mechanism is provided in the mixing box, the mixing mechanism comprises a motor arranged at the top of the material box, the output shaft of the motor extends into the mixing box and is connected to a stirring shaft, and the stirring shaft is detachably connected to a stirring rod; the upper end of the stirring shaft is rotatably connected to the top of the mixing box, the lower end of the stirring shaft is detachably connected to a cylindrical cam, and the slide plate is slidably connected to the cylindrical cam; a scraper is slidably connected to one end of the stirring rod, one side of the long side of the scraper is in contact with the inside of the mixing box, and the bottom of the scraper is in contact with the slide plate; a second one-way valve is provided on the slide plate for only allowing gas to flow from the recycling box to the mixing box; a third one-way valve is provided on the top of the mixing box for only allowing gas to flow from the mixing box to the outside.

2. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: Both step 3 and step 5 use yellow phosphorus tail gas as the combustion medium for combustion and heat supply.

3. The method for producing pellet ore from low-grade cyclone tailings according to claim 2, characterized in that: The drying temperature in step 3 is 500-1000° C., and the moisture content of the phosphate rock powder after drying is controlled to be ≤12%.

4. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: The phosphoric acid added in step 4 is raffinate, and the phosphoric acid concentration is 70%.

5. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: The adhesive added in step 4 is one or more of aluminum phosphate, magnesium, sodium, and organic phosphorus high-performance adhesives.

6. The method for producing pellet ore from low-grade cyclone tailings according to claim 2, characterized in that: The sintering temperature in step 5 is controlled to be 500° C. to 1200° C., and the moisture content of the pellets after sintering is 1% to 10%.

7. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: The particle size of the pellet ore is 30 to 50 mm.

8. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: The particle size of the phosphate rock powder is less than or equal to 10 mm.

9. The method for producing pellet ore from low-grade cyclone tailings according to claim 1, characterized in that: The discharge port of the ball making box is connected to a discharge channel arranged to be inclined downward, the end of the discharge channel is rotatably connected to a cover plate, a plurality of return holes are provided at the bottom of the discharge channel and the return holes are connected to a return channel, one end of the return channel is connected to a return port of a recovery box, and the return port is provided with a first one-way valve that only allows material to enter the recovery box from the return channel.

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