Method and system for preparing pellets for yellow phosphorus production from by-product of phosphate ore beneficiation and application

Abstract

The present application relates to the field of mineral processing, and particularly to a method and system for preparing pellets for yellow phosphorus production from phosphorite beneficiation by-products, and application, the method comprising: grading demagnified phosphorite concentrate to obtain coarse-grained sand and fine-grained overflow; performing reverse flotation desilication on the coarse-grained sand to obtain desilicated concentrate and desilicated tailings; mixing the desilicated tailings with the obtained fine-grained overflow and controlling the acidity value of the mixture; filter-drying the mixture, granulating the raw material to obtain raw pellets, and controlling the water content of the raw pellets; further drying the raw pellets, and roasting the pellets to obtain clinker pellets as yellow phosphorus production feedstock. The present application realizes full-component and gradient efficient utilization of phosphorus resources, nearly zero emission, can save the cost of binding agent, at the same time avoids the introduction of additional impurities by the binding agent, is conducive to stabilizing the yellow phosphorus electric furnace slag system, reduces power consumption, and improves phosphorus recovery.

Description

Technical Field

[0001] This invention relates to the field of mineral processing, and in particular to a method, system, and application for preparing yellow phosphorus pellets from phosphate ore beneficiation byproducts. Background Technology

[0002] Phosphate rock is a basic raw material for the production of important chemical products such as phosphate fertilizers, phosphoric acid, and yellow phosphorus. my country has abundant phosphate rock resources, but a large proportion of them are of medium and low grade, and most contain impurities such as magnesium, iron, and aluminum, which need to be beneficiated to meet the requirements of subsequent processing.

[0003] Currently, phosphate rock beneficiation mainly employs processes such as reverse flotation for magnesium removal and reverse flotation for silicon removal. However, the beneficiation process generates various intermediate products and tailings: fine-grained materials (such as staged overflow) are difficult to utilize directly due to their excessively fine particle size and high impurity content; the residual phosphorus resources in the desilication tailings are not fully recovered, and their large-scale stockpiling causes environmental pressure.

[0004] In existing technologies, the pelletizing process of phosphate rock powder relies heavily on binders and requires the purchase of silica. Adding binders not only increases the cost of raw materials but also introduces additional impurities into the pellets, affecting the stability of the yellow phosphorus electric furnace slag system and increasing energy consumption.

[0005] In addition, there are also obvious defects in the selection of raw materials: mineral processing by-products (such as fine-grained materials and demagnesium and desiliconization tailings) are not included in the pelletizing system, resulting in the waste of valuable components and increased environmental pressure; siliceous raw materials rely on purchased silica, which has a long and costly pretreatment process, while endogenous desiliconization tailings are not utilized in conjunction; the particle size distribution of raw materials is uniform, and the distribution of coarse and fine particles lacks optimization, so the filling effect of fine particles and the mechanical interlocking effect between particles cannot be fully utilized, and it is difficult to form sufficient green pellet strength by relying solely on the physical properties of the raw materials themselves. This is also an important underlying reason why the existing process must rely on the addition of binders.

[0006] Therefore, how to make reasonable use of fine-grained materials and tailings generated during mineral processing, achieve efficient pelletizing without adding binders, and meet the requirements of yellow phosphorus electric furnace for the strength and chemical composition of the feed material, so as to maximize the recovery of phosphorus resources and the cascade utilization of all components, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a method, system, and application for preparing yellow phosphorus pellets from phosphate rock beneficiation byproducts. This method utilizes different materials generated during beneficiation in a graded manner, optimizes particle size distribution, and forms pellets without binders, ultimately achieving full resource recovery of all components, along with the resulting pellet products. It addresses problems in existing technologies such as the high MER value of fine ore overflow from beneficiation, making it unsuitable for wet-process phosphoric acid or heavy calcium carbonate production; the waste of desilication tailings due to stockpiling and the lack of phosphorus recovery; the high cost of purchasing silica for yellow phosphorus production; and the increased cost and impurity introduction caused by the reliance on external binders in existing powder pelletizing processes.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing yellow phosphorus pellets from phosphate rock beneficiation byproducts, comprising the following steps: Step (1) Classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow; Step (2) The coarse sand is desiliconized by reverse flotation to obtain desiliconized concentrate and desiliconized tailings; Step (3) Mix the desilication tailings with the fine overflow obtained in step (1) and control the acidity value of the mixture; Step (4) The mixture is pressed, dried, and granulated into raw material balls, and the moisture content of the raw material balls is controlled. Step (5) further dry the raw pellets and then roast the pellets to obtain calcined pellets, which are used as raw materials for yellow phosphorus production.

[0009] As a preferred option, in step (1), the grading is based on 400~500 mesh to obtain coarse sediment and fine overflow; the MER value of the fine overflow is >0.1, where MER is the proportion of harmful metal impurities such as magnesium, iron and aluminum in the phosphate rock relative to phosphorus.

[0010] As a preferred embodiment, in step (2), the SiO2 content in the desilication tailings is ≥50%, and the P2O5 content is <15%.

[0011] As a preferred option, the desilication concentrate obtained in step (2) is used for wet-process phosphoric acid or heavy calcium carbonate production.

[0012] As a preferred embodiment, in step (3), the acidity value of the mixture is controlled within the range of 0.75 to 0.85. The acidity value is: By mass, acidity value = (sum of mass fractions of SiO2 and Al2O3 in desilication tailings × mass of desilication tailings + sum of mass fractions of SiO2 and Al2O3 in fine overflow × mass of fine overflow) ÷ (sum of mass fractions of CaO and MgO in desilication tailings × mass of desilication tailings + sum of mass fractions of CaO and MgO in fine overflow × mass of fine overflow), i.e. .

[0013] As a preferred option, in step (4), the mixture is pressed and dried to a moisture content of <5%, the pelleting time is 2~3h, the diameter of the raw material pellets is 30~50mm, and the moisture content of the raw material pellets is controlled to <15%.

[0014] As a preferred option, in step (5), the raw pellets are first dried at 100~120℃ to a moisture content of <5%, and then the pellets are heated to 900℃~1000℃ at 8~12℃ / min and roasted for 110~130 minutes to obtain clinker pellets, which are used as raw materials for yellow phosphorus production.

[0015] Secondly, the present invention provides pellets for the production of yellow phosphorus from phosphate rock beneficiation by-products. The pellets are obtained by the above method and have an acidity value of 0.75~0.85, a clinker pellet moisture content of <5%, a compressive strength of ≥2500N, and a drum index of ≥60%.

[0016] Thirdly, the present invention provides a system for preparing yellow phosphorus production pellets from phosphate rock beneficiation byproducts, comprising: The classification unit is used to classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow. The flotation unit is used to desilicate coarse sand by reverse flotation to obtain desilication concentrate and desilication tailings; The mixing unit is used to mix the desilication tailings with the fine-particle overflow obtained in step (1) according to the acidity requirements; The filter press drying unit is used to dehydrate and dry the mixture to a certain moisture content; The pelletizing unit is used to granulate the dried mixture into raw material pellets without adding binders, control the moisture content of the raw material pellets, and dry the raw material pellets. In the roasting unit, the raw pellets are first dried and then roasted to obtain calcined pellets, which are used as raw materials for yellow phosphorus production. The output of the grading unit is connected to the flotation unit and the blending unit respectively. The output of the flotation unit is connected to the blending unit and the wet phosphate / calcium carbonate production system respectively. The blending unit, the filter press and drying unit, the pelletizing unit and the calcining unit are connected in series.

[0017] Fourthly, the present invention provides an application of yellow phosphorus production pellets in the electric furnace method for producing yellow phosphorus. The pellets described above or prepared by the above system are used to replace conventional yellow phosphorus production feedstock at a mass ratio of 20% to 40% for the production of yellow phosphorus in the electric furnace method. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of one specific embodiment of the present invention; Figure 2This is a system block diagram of one specific embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased.

[0020] Unless otherwise stated, all percentages in this invention represent mass fractions. Ratios are mass percentages, and concentrations are mass concentrations.

[0021] Unless otherwise specified, all materials, instruments, and equipment used below are conventional materials, instruments, and equipment or obtained through commercial channels; all testing methods used are existing methods unless otherwise specified.

[0022] Existing technologies disclose a method for enriching and compounding phosphorus tailings powder into pellets, which requires the addition of raffinate acid or raffinate residue as a binder and the purchase of silica powder. Other existing technologies disclose a method for producing pellets from low-grade cyclone tailings, which also requires the addition of phosphoric acid, binder, and silica powder. Still other existing technologies disclose a pelletizing binder for yellow phosphorus powder, which requires the addition of sulfate binders. Some existing technologies disclose a method for pelletizing medium- and low-grade phosphorus powder, which, although claiming to be binder-free, still requires the addition of various purchased additives such as sodium silicate, soda ash, and calcium carbonate. Some existing technologies explore the utilization of phosphorus tailings, but mainly focus on the use of magnesium components to prepare light magnesium carbonate, without involving high-value recovery for use in yellow phosphorus production for pelletizing. It can be seen that the phosphorus powder pelletizing processes mentioned in the above-mentioned existing technologies mostly rely on binders and require the purchase of silica.

[0023] Meanwhile, yellow phosphorus production requires phosphate rock and silica as raw materials. In traditional processes, phosphate rock needs to be crushed and screened before being fed into the furnace in lump form, or it needs to be pelletized from powder before use; silica needs to be purchased externally and crushed separately before being added. In powder pelletizing technology, the current mainstream process requires the addition of binders such as bentonite, water glass, and carboxymethyl cellulose to improve the strength of green pellets. However, adding binders not only increases the cost of raw materials (approximately 20-40 yuan / ton of pellets), but also introduces additional impurities (such as sodium, aluminum, and silicon) into the pellets, affecting the stability of the yellow phosphorus electric furnace slag system, increasing power consumption, and potentially reducing phosphorus yield.

[0024] Furthermore, in the first aspect, such as Figure 1 As shown in the figure, this embodiment of the invention provides a method for preparing yellow phosphorus pellets from phosphate rock beneficiation byproducts, comprising the following steps: Step (1) Classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow; Step (2) The coarse sand is desiliconized by reverse flotation to obtain desiliconized concentrate and desiliconized tailings; Step (3) Mix the desilication tailings with the fine overflow obtained in step (1) and control the acidity value of the mixture; Step (4) The mixture is pressed, dried, and granulated into raw material balls, and the moisture content of the raw material balls is controlled. Step (5) further dry the raw pellets and then roast the pellets to obtain calcined pellets, which are used as raw materials for yellow phosphorus production.

[0025] This invention, through its embodiments, eliminates the need for any binders and external silica purchases. It utilizes the synergistic pelletizing of fine-particle overflow (a byproduct of mineral processing) and desilication tailings to achieve full-component, tiered utilization. The fine-particle overflow has a high MER value, making it unsuitable for wet-process acid production. The desilication tailings are high in silicon and phosphorus. The synergistic utilization of both produces yellow phosphorus pellets for furnace feed, achieving full-component, tiered, and highly efficient utilization of phosphorus resources with near-zero emissions. Furthermore, the fine-particle overflow and desilication tailings, through a dual synergistic mechanism, jointly achieve the goal of binder-free pelletizing and replacing purchased silica. First, there is synergy in chemical components: the fine-particle overflow is a fine-particle phosphorus-enriched material with a high P2O5 content, which is the main phosphorus source for the pellets; the desilication tailings have a high SiO2 content and can be directly used as an endogenous silicon correction raw material. When the two are matched in proportion, the requirements of yellow phosphorus electric furnace for silicon content and slag acidity in the furnace charge can be met, without the need to purchase silica from outside.

[0026] Second, synergistic particle size distribution: the fine overflow particles are too fine and have a large specific surface area. After hydration, they have a certain plasticity and self-adhesion, which can fill the gaps between coarse particles; the desilication tailings particles are relatively coarse and can form the rigid skeleton of the pellets. The combination of the two forms a continuous particle size distribution. The strength of the green pellets is improved by the mechanical interlocking and capillary force between the particles, which replaces the role of the external binder.

[0027] This invention, through particle size distribution optimization and pelletizing process, utilizes the high specific surface area and high surface activity of the fine particles themselves to achieve "self-bonding," completely replacing the addition of binders such as bentonite and water glass in traditional processes. Compared with existing technologies, this invention can save 20-40 yuan / ton of binder cost in pellets, while avoiding additional impurities (such as sodium and aluminum) introduced by binders. This is beneficial for stabilizing the yellow phosphorus electric furnace slag system, reducing power consumption, and increasing phosphorus yield.

[0028] In one implementation method, in step (1), the grading is based on 400~500 mesh, and the mesh number can be 400, 450, or 480 to obtain coarse sediment and fine overflow; the MER value of the fine overflow is >0.1, where MER = (Fe2O3 + Al2O3 + MgO) / P2O5, that is, the proportion of harmful metal impurities such as magnesium, iron, and aluminum in the phosphate rock relative to phosphorus by mass.

[0029] After classification to 400-500 mesh, the proportion of fine particles in the sediment is relatively low, which allows the flotation foam to flow and defoam normally during reverse flotation desilication operations using amine cationic desilication collectors. Otherwise, the desilication operation cannot function properly. After classification to 400-500 mesh, iron and aluminum impurities are mainly enriched in the fine particles. After multiple sampling analyses, the MER value of the fine particle overflow was greater than 0.1.

[0030] After being classified into 400-500 mesh, the fine overflow has a high specific surface area, which is conducive to self-aggregation into balls; the coarse underflow has a suitable particle size and can be desiliconized by reverse flotation to obtain high-quality desiliconized concentrate.

[0031] Fine-particle overflow is not suitable for direct use in wet-process phosphoric acid due to its high MER value, but its extremely fine particle size and large specific surface area can play a "self-adhesive" role in the pelletizing process.

[0032] In one embodiment, in step (2), the SiO2 content in the desilication tailings is ≥50%, and the P2O5 content is <15%.

[0033] In this embodiment of the invention, reverse flotation desilication uses the classified coarse particles for reverse flotation desilication. If classification is not performed, the desilication agent used can be an amine-based cationic collector. Too many fine particles will lead to excessively viscous foam, making defoaming difficult and resulting in poor flowability, ultimately causing operational difficulties for the process unit. The reverse flotation desilication is performed at a pH of around 5, and can be carried out according to existing technologies.

[0034] The SiO2 content in the desilication tailings is ≥50%, which can completely replace the purchased silica required for the production of yellow phosphorus, significantly reducing the cost of raw materials. At the same time, the residual P2O5 in the tailings is <15%, which can be used as a silicon source in the production of yellow phosphorus to replace the purchased silica, while recovering the residual phosphorus resources and improving the comprehensive utilization rate of resources.

[0035] As one implementation method, the desilication concentrate obtained in step (2) is used for wet-process phosphoric acid or heavy calcium carbonate production, thereby further realizing the full-component, tiered, and efficient utilization of phosphorus resources with near-zero emissions.

[0036] In one implementation method, in step (3), the acidity value of the mixture is controlled within the range of 0.75 to 0.85, where the acidity value is: In terms of mass, [ .

[0037] The mixing ratio of desilication tailings and fine-particle overflow was determined through material balance calculations, which used the acidity value of the mixture as the basis for the material balance calculations. The target is to control the mass ratio within the range of 0.75 to 0.85, and the calculation formula is as follows: Acidity value = (sum of mass fractions of SiO2 and Al2O3 in desilication tailings × mass of desilication tailings + sum of mass fractions of SiO2 and Al2O3 in fine overflow × mass of fine overflow) ÷ (sum of mass fractions of CaO and MgO in desilication tailings × mass of desilication tailings + sum of mass fractions of CaO and MgO in fine overflow × mass of fine overflow). Too low an acidity can easily lead to increased slag melting point and viscosity, difficulty in slag removal, incomplete reduction, high residual phosphorus in the slag, and fluctuations in furnace conditions and nodulation. Too high an acidity will increase the amount of slag, exacerbate furnace lining corrosion, increase mud phosphorus production, and make the system prone to scaling and blockage.

[0038] In one implementation method, in step (4), the mixture is pressed and dried until the moisture content is <5%, the pelleting time is 2~3h, which can be 2h, 2.3h, or 2.8h, the diameter of the raw material pellets is 30~50mm, and the moisture content of the raw material pellets is controlled to be <15%.

[0039] Under the same pellet diameter, pelleting time is positively correlated with pellet strength: the longer the pelleting time, the more fully the powder coats and compacts the pellet core during the rolling process, resulting in denser particle packing inside the pellet and higher overall strength. Powder moisture content, on the other hand, is negatively correlated with pellet strength: excessive moisture weakens the bonding between particles, leading to higher plasticity and a softer structure in the pellets, ultimately resulting in decreased mechanical strength.

[0040] The binder-free powder pelletizing process utilizes the high specific surface area and surface activity of fine particle overflow to achieve self-bonding, without adding any binders such as bentonite, water glass, or carboxymethyl cellulose.

[0041] In one implementation method, in step (5), the raw pellets are first dried at 100-120℃ until the moisture content is <5%, and then the pellets are heated to 900-1000℃ at a rate of 8-12℃ / min and calcined for 110-130 minutes to obtain clinker pellets, which are used as raw material for yellow phosphorus production. The drying temperature can be 105℃, 110℃, or 115℃, the heating rate can be 8℃ / min, 10℃ / min, or 12℃ / min, the calcination temperature can be 900℃, 950℃, or 1000℃, and the holding time can be 115 minutes, 120 minutes, or 130 minutes.

[0042] The pellets are dried to a moisture content of less than 5%, resulting in an average pellet strength of around 600N, making them less prone to breakage during transportation and storage.

[0043] Secondly, embodiments of the present invention also provide pellets for preparing yellow phosphorus from phosphate rock beneficiation by-products. The pellets are obtained by the above method and have an acidity value of 0.75~0.85, a clinker pellet moisture content of <5%, a compressive strength of ≥2500N, and a drum index of ≥60%.

[0044] The pellets produced in this invention exhibit excellent performance. Through precise control of acidity (0.75~0.85) and high-temperature roasting (900℃~1000℃), the resulting pellets have a compressive strength ≥2500N and a drum index ≥60%, meeting the strength requirements of yellow phosphorus electric furnaces for the feed material. This effectively improves furnace permeability (small pressure fluctuation at the furnace top), stabilizes furnace conditions, and reduces furnace gas dust concentration by approximately 15%.

[0045] This invention utilizes the characteristics of extremely fine particle size, large specific surface area, and high surface activity of the fine overflow to perform particle size distribution with desilication tailings. The fine overflow fills the gaps between the desilication tailings particles, and the particles interact with each other through intermolecular forces (van der Waals forces) and capillary forces to achieve "self-adhesion" molding without the need for external binders. Thirdly, such as Figure 2 As shown, this embodiment of the invention also provides a system for preparing yellow phosphorus pellets from phosphate rock beneficiation byproducts, comprising: The classification unit is used to classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow. The flotation unit is used to desilicate coarse sand by reverse flotation to obtain desilication concentrate and desilication tailings; The mixing unit is used to mix the desilication tailings with the fine-particle overflow obtained in step (1) according to the acidity requirements; The filter press drying unit is used to dehydrate and dry the mixture to a certain moisture content; The pelletizing unit is used to granulate the dried mixture into raw material pellets without adding binders, control the moisture content of the raw material pellets, and dry the raw material pellets. In the roasting unit, the raw pellets are first dried and then roasted to obtain calcined pellets, which are used as raw materials for yellow phosphorus production. The output of the grading unit is connected to the flotation unit and the blending unit respectively. The output of the flotation unit is connected to the blending unit and the wet phosphate / calcium carbonate production system respectively. The blending unit, the filter press and drying unit, the pelletizing unit and the calcining unit are connected in series.

[0046] The process flow of this invention is clear and the combination is reasonable. The required equipment is all general equipment in the mineral processing and metallurgical industries. There is no need to carry out large-scale transformation of existing production lines. It is easy to promote industrialization and has strong process adaptability.

[0047] Fourthly, this invention also provides an application of yellow phosphorus production pellets in electric furnace yellow phosphorus production. The pellets prepared by the above-mentioned system or the above-mentioned method are used to replace the conventional yellow phosphorus production feed at a mass ratio of 20% to 40% for electric furnace yellow phosphorus production, which can improve phosphorus yield, reduce power consumption and furnace gas dust concentration.

[0048] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a method, system, and application for preparing yellow phosphorus production pellets from phosphate rock beneficiation byproducts.

[0049] Raw material specifications used in Examples 1-3 Phosphate ore composition: P2O5 21.20%, MgO 5.57%, Fe2O3 1.14%, Al2O3 1.62%, SiO2 14.59%, CaO 38.15%.

[0050] After reverse flotation to remove magnesium, the demagnesized phosphate concentrate was obtained: P2O5 28.41%, MgO 1.19%, Fe2O3 0.92%, Al2O3 1.28%, SiO2 20.01%, CaO 40.91%.

[0051] Example 1

[0052] The method for preparing yellow phosphorus production pellets from phosphate rock beneficiation by-products in this embodiment is as follows: (1) Classification: The magnesium-phosphate concentrate is classified at 400 mesh to obtain coarse sand and fine overflow.

[0053] The fine-particle overflow contains ≥95.6% -400 mesh, 26.99% P2O5, 0.66% MgO, 1.33% Fe2O3, 2.16% Al2O3, 23.16% SiO2, and 38.06% CaO. The calculated MER value is (0.66 + 1.33 + 2.16) / 26.99 = 0.154 > 0.1.

[0054] (2) Reverse flotation desilication: The coarse sand is subjected to reverse flotation desilication to obtain desilication concentrate and desilication tailings. The specific process is carried out in accordance with Example 1 and Application Example 2 of CN110721818A, with a pH of 5.0.

[0055] Composition of desilication concentrate: P2O5 32.44%, MgO 1.34%, Fe2O3 0.68%, Al2O3 0.82%, SiO2 9.67%, CaO 45.16%. Composition of desilication tailings: P2O5 11.10%, MgO 1.40%, Fe2O3 1.33%, Al2O3 6.99%, SiO2 51.98%, CaO 17.23%.

[0056] (3) Mixing ratio: Based on the requirement that the suitable acidity value of yellow phosphorus slag is 0.75~0.85, the mixing ratio of desiliconized tailings and fine overflow is determined by material balance calculation.

[0057] Taking a target acidity value of 0.80 as an example, the calculation formula is: acidity value = ([ Let the mass fraction of desilication tailings be x, and the mass fraction of fine-particle overflow be y, then: ((51.98+6.99)x+(23.16+2.16)y) / ((17.23+1.40)x+(38.06+0.66)y=(58.97x+25.32y) / (18.63x+38.72y)=0.80. Solving for x:y, we get x:y≈1:5.24, which means the mass ratio of desilication tailings to fine-grained overflow is 1:5.24.

[0058] (4) Pressure filtration and drying: The mixture is pressure filtered and dried at 105°C to a moisture content of 4.2%.

[0059] (5) Binder-free pelletizing: The dried mixture was pelletized without binder. The moisture content of the raw material pellets was 10.2%, the pelletizing time was 2.3 hours, and raw material pellets with a diameter of 40±5 mm were obtained, with a pelletizing rate of 88.6%. No binder was added during the process, and the raw pellets had good drop strength.

[0060] (6) Calcination: Place the raw pellets in a drying oven and keep them at 120℃ for 120 minutes. Then take the pellets out and put them into a high-temperature oven. Raise the temperature to 950℃ at 10℃ / min and keep it at 120 minutes. Let them cool naturally to obtain the cooked pellets.

[0061] Performance testing: The average compressive strength of the clinker pellets at room temperature was 3410 N (average of 20 pellets tested), the drum index was 64.8%, the moisture content was 0.3%, the measured acidity value was 0.81, and the P2O5 grade was 24.44%, which meets the requirements for yellow phosphorus feed into the furnace.

[0062] Example 2

[0063] The method for preparing yellow phosphorus production pellets from phosphate rock beneficiation byproducts in this embodiment changes the mixing ratio of desilication tailings and fine particle overflow, and controls the target acidity value to 0.75.

[0064] according to([ The calculation yielded x:y≈1:7.25, and the remaining conditions were the same as in Example 1.

[0065] The pelletizing rate of raw material pellets was 87.5%, the average compressive strength of clinker pellets was 3080N, the drum index was 61.5%, the measured acidity value was 0.76, and the P2O5 grade was 25.06%.

[0066] Example 3

[0067] The method for preparing yellow phosphorus production pellets from phosphate rock beneficiation byproducts in this embodiment changes the mixing ratio of desilication tailings and fine particle overflow, and controls the target acidity value to 0.85.

[0068] according to([ The calculation yielded x:y≈1:4.06, and the remaining conditions were the same as in Example 1.

[0069] The raw material pellets have a pelletizing rate of >87.1%, the average compressive strength of the clinker pellets is 3250N, the drum index is 63.2%, the measured acidity value is 0.84, and the P2O5 grade is 23.85%.

[0070] Example 4

[0071] The method for preparing yellow phosphorus production pellets from phosphate ore beneficiation by-products in this embodiment uses demagnesified phosphate concentrate obtained from phosphate ore beneficiation in a certain area of ​​Guizhou as another raw material source.

[0072] The raw phosphate ore composition is as follows: P2O5 19.85%, MgO 6.12%, Fe2O3 1.45%, Al2O3 1.88%, SiO2 16.73%, CaO 36.45%. After reverse flotation to remove magnesium, the demagnesized phosphate concentrate is obtained with the following composition: P2O5 27.63%, MgO 1.31%, Fe2O3 1.02%, Al2O3 1.45%, SiO2 22.34%, CaO 39.78%.

[0073] The specific steps are as follows: (1) Classification: The above-mentioned demagnesified phosphate concentrate was classified with 450 mesh as the boundary to obtain coarse underflow and fine overflow. The proportion of -450 mesh in the fine overflow was ≥93.73%, and its MER value = (1.31+1.02+1.45) / 27.63 = 0.137 > 0.1; its specific surface area was determined to be 610 m² by the BET method. 2 / kg.

[0074] (2) Reverse flotation desilication: The coarse-grained sand is subjected to reverse flotation desilication to obtain desilication concentrate and desilication tailings. Desilication concentrate composition: P2O5 31.82%, MgO 1.28%, Fe2O3 0.71%, Al2O3 0.79%, SiO2 10.05%, CaO 44.55%. Desilication tailings composition: P2O5 10.56%, MgO 1.33%, Fe2O3 1.41%, Al2O3 7.12%, SiO2 52.44%, CaO 16.82%.

[0075] (3) Mixing ratio: With the target acidity value of 0.80 as the control target, the mass ratio of desilication tailings to fine overflow is determined to be 1:5.02 through material balance calculation.

[0076] (4) Pressure filtration and drying: The mixture is pressure filtered and dried at 105°C to a moisture content of 4.0%.

[0077] (5) Binderless pelletizing: The dried mixture is pelletized without binder. The moisture content of the raw material pellets is 9.6%, the pelletizing time is 2.2h, and raw material pellets with a diameter of 40±5mm are obtained with a pelletizing rate of 86.6%.

[0078] (6) Calcination: Calcination was carried out under the same conditions as in Example 1 (950°C constant temperature for 120 minutes) to obtain clinker pellets.

[0079] (7) Performance testing: The average compressive strength of the clinker pellets at room temperature was 3320 N (average of 20 pellets tested), the drum index was 63.5%, the moisture content was 0.3%, the measured acidity was 0.80, and the P2O5 grade was 23.92%. All indicators met the requirements for yellow phosphorus feed into the furnace and were close to the results of Examples 1-3, proving that the method of the present invention has good adaptability to phosphate ore beneficiation by-products from different sources.

[0080] Comparative Example 1: Conventional yellow phosphorus production furnace feed with added binder The traditional yellow phosphorus furnace charge formula was used: 65 parts of phosphate rock powder (P2O5 25%), 20 parts of silica powder (SiO2 95%), and 15 parts of coke powder. 3% bentonite was added as a binder for pelletizing, and the pellets were calcined at 950℃. The average compressive strength of the finished pellets was 3120 N, and the drum index was 61.5%.

[0081] Comparative Example 2 (using desilication tailings alone to form pellets without binder) Using desilication tailings alone (P2O5 11.10%, SiO2 51.98%), under the same conditions (moisture content 4.2%), the pelletizing rate was as low as 58%, and the green pellets were brittle. After roasting at 950℃, the average compressive strength of the clinker pellets at room temperature was 1720N, the drum index was 46.5%, and there were obvious cracks on the surface of the pellets.

[0082] The acidity value is calculated using the acidity formula: Mk=(51.98+6.99) / (17.23+1.40)=58.97 / 18.63=3.16, which is much higher than the control range of 0.75~0.85.

[0083] Comparative Example 3 (Ball formation using fine-particle overflow without binder) Using fine-particle overflow (P2O5 26.99%) alone, under the same conditions, the pelletizing rate was 61% when pelletizing without binder; after calcination at 950℃, the average compressive strength of the clinker pellets at room temperature was 2630N, and the drum index was 55.8%.

[0084] The calculated acidity value Mk = (23.16 + 2.16) / (38.06 + 0.66) = 25.32 / 38.72 = 0.65, which is lower than the lower limit requirement of 0.75.

[0085] Comparative Example 4 The moisture content of the binder-free pelletized raw material pellets from the desilication tailings and fine overflow was changed to 27.35%, while the other conditions were the same as in Example 1.

[0086] The pelletizing rate of raw material pellets was 65.5%, the average compressive strength of clinker pellets was 1801 N, and the drum index was 38.24%.

[0087] Comparative Example 5 The time for binder-free pelletizing of desilication tailings and fine-particle overflow was changed to 1 hour, while the other conditions were the same as in Example 1.

[0088] The pelletizing rate of raw material pellets was 87.04%, the average compressive strength of clinker pellets was 2587 N, and the drum index was 53.56%.

[0089] Table 1. Performance Comparison of Examples and Comparative Examples

[0090] Application examples Comparative experiments were conducted in actual electric furnaces for yellow phosphorus production, with clinker pellets from Example 1 and Comparative Example 1 added at a mass ratio of 30% to replace the conventional yellow phosphorus feedstock. The results showed that: When using pellets from Example 1, the furnace conditions were stable, the furnace top pressure fluctuated little, and the slag flowability was good. Phosphorus yield increased by approximately 3.8% compared to Comparative Example 1, and power consumption decreased by approximately 4.5%. Since no binder was added to the pellets from Example 1, the introduction of impurities such as sodium and aluminum was avoided, resulting in smaller fluctuations in slag composition and further improving production indicators. Analysis of furnace gas dust sampling showed that the furnace gas dust concentration using pellets from Example 1 was approximately 15% lower than that of Comparative Example 1.

[0091] The above experiments demonstrate that the method for preparing yellow phosphorus pellets for furnace production using phosphate rock beneficiation by-products without binder, provided by this invention, not only realizes the resource utilization of beneficiation intermediate products and tailings, but also achieves binder-free pelletizing through particle size distribution optimization. The performance of the prepared pellets is superior to that of conventional yellow phosphorus production furnace pellets. In actual production, it exhibits synergistic advantages of improving furnace conditions, increasing phosphorus yield, and reducing energy consumption. At the same time, it saves binder costs and avoids the introduction of impurities, thus possessing extremely high industrial application value.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing yellow phosphorus production pellets from phosphate rock beneficiation byproducts, characterized in that, Includes the following steps: Step (1) Classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow; Step (2) The coarse sand is desiliconized by reverse flotation to obtain desiliconized concentrate and desiliconized tailings; Step (3) Mix the desilication tailings with the fine overflow obtained in step (1) and control the acidity value of the mixture; Step (4) The mixture is pressed, dried, and granulated into raw material balls, and the moisture content of the raw material balls is controlled. Step (5) further dry the raw pellets and then roast the pellets to obtain calcined pellets, which are used as raw materials for yellow phosphorus production.

2. The method according to claim 1, characterized in that, In step (1), the grading is based on 400~500 mesh to obtain coarse sediment and fine overflow; the MER value of the fine overflow is >0.1, where MER is the proportion of harmful metal impurities such as magnesium, iron and aluminum in the phosphate rock relative to phosphorus.

3. The method according to claim 1, characterized in that, In step (2), the SiO2 content in the desilication tailings is ≥50%, and the P2O5 content is <15%.

4. The method according to claim 1, characterized in that, The desilication concentrate obtained in step (2) is used for wet-process phosphoric acid or heavy calcium carbonate production.

5. The method according to claim 1, characterized in that, In step (3), the acidity value of the mixture is controlled within the range of 0.75 to 0.85, and the acidity value is: By mass, acidity value = (sum of mass fractions of SiO2 and Al2O3 in desilication tailings × mass of desilication tailings + sum of mass fractions of SiO2 and Al2O3 in fine overflow × mass of fine overflow) ÷ (sum of mass fractions of CaO and MgO in desilication tailings × mass of desilication tailings + sum of mass fractions of CaO and MgO in fine overflow × mass of fine overflow), i.e. .

6. The method according to claim 1, characterized in that, In step (4), the mixture is pressed and dried until the moisture content is <5%, the pelleting time is 2~3h, the diameter of the raw material pellets is 30~50mm, and the moisture content of the raw material pellets is controlled to be <15%.

7. The method according to claim 1, characterized in that, In step (5), the raw pellets are first dried at 100~120℃ to a moisture content of <5%, and then the pellets are heated to 900℃~1000℃ at 8~12℃ / min and roasted for 110~130 minutes to obtain clinker pellets, which are used as raw materials for yellow phosphorus production.

8. A pellet for producing yellow phosphorus from a byproduct of phosphate rock beneficiation, characterized in that, The pellets obtained by the method according to any one of claims 1 to 7 have an acidity value of 0.75 to 0.85, a clinker pellet moisture content of <5%, a compressive strength of ≥2500N, and a drum index of ≥60%.

9. A system for preparing yellow phosphorus pellets from phosphate rock beneficiation byproducts, characterized in that, include: The classification unit is used to classify the demagnesified phosphate concentrate to obtain coarse underflow and fine overflow. The flotation unit is used to desilicate coarse sand by reverse flotation to obtain desilication concentrate and desilication tailings; The mixing unit is used to mix the desilication tailings with the fine-particle overflow obtained in step (1) according to the acidity requirements; The filter press drying unit is used to dehydrate and dry the mixture; The pelletizing unit is used to granulate the dried mixture into raw material pellets without adding binders, control the moisture content of the raw material pellets, and dry the raw material pellets. In the roasting unit, the raw pellets are first dried and then roasted to obtain calcined pellets, which are used as raw materials for yellow phosphorus production. The output of the grading unit is connected to the flotation unit and the blending unit respectively. The output of the flotation unit is connected to the blending unit and the wet phosphate / calcium carbonate production system respectively. The blending unit, the filter press and drying unit, the pelletizing unit and the calcining unit are connected in series.

10. The application of a type of pellet for yellow phosphorus production in the electric furnace process for producing yellow phosphorus, characterized in that, The pellets prepared by the system of claim 8 or claim 9 are used to replace conventional yellow phosphorus feedstock in electric furnace production at a mass ratio of 20% to 40%.

Images