A system and method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting

Abstract

This invention relates to the field of mineral sorting technology. It discloses a system and method for underground mining of low-grade phosphate rock based on photoelectric mineral processing pre-sorting. The system primarily utilizes a "3+2" scheme of photoelectric mineral processing technology to pre-sort the mined low-grade phosphate rock, thereby obtaining various types of phosphate rock that meet the requirements of different downstream phosphate chemical products. The mined 10-40mm low-grade phosphate rock is sequentially sorted to obtain qualified phosphate rock that meets the requirements for downstream feed-grade calcium phosphate, ammonium phosphate, and tailings utilization. Compared with the original ore, the P2O5 grade of the first two is increased, while the contents of Fe2O3, Al2O3, MgO, and SiO2 are decreased. Meanwhile, the grade of the remaining tailings is decreased, and the oxide content is increased, resulting in a comprehensive tailings rejection rate of <12%. This invention achieves graded utilization of phosphate resources, increases the pathways for phosphate resource use, alleviates or even reduces the difficulty of subsequent mineral processing and phosphate chemical production, and effectively saves production costs.

Description

Technical Field

[0001] This invention relates to the field of mineral sorting technology, and in particular to a system and method for underground mining of low-grade phosphate rock based on photoelectric mineral processing pre-sorting. Background Technology

[0002] The utilization of phosphorus resources involves multiple fields such as agriculture, chemical industry, pharmaceuticals, food, electronic semiconductor materials, and environmental protection. Phosphorus resources in various forms mainly originate from the processing of phosphate rock. Phosphorus rock is a non-renewable resource. Although the known reserves of phosphate rock in China are relatively high, most are low- to medium-grade, poor-quality ores. With the long-term mining of surface phosphate rock, this non-renewable resource can no longer meet the demand for various phosphorus or phosphate chemical products. The accompanying reduction in grade also has a significant impact on downstream phosphate chemical products. Although the source and quantity of phosphate rock have been partially resolved by shifting from surface mining to underground mining, underground mines are mostly complex, low-grade phosphate ores with high contents of major oxides that significantly affect phosphate chemical reactions, such as Fe2O3, Al2O3, MgO, and SiO2. Overall, this makes it difficult to meet the basic quality and quantity requirements of various phosphate chemical products, significantly impacting the quality and production processes of phosphorus compounds in phosphate rock flotation and downstream phosphate chemical products. Furthermore, it presents the challenge of low comprehensive utilization of phosphorus resources. Phosphate rock processing, as the primary step in other phosphorus resource utilization processes, faces significant pressure due to declining phosphate rock grades and complex compositions. Existing single or combined beneficiation methods such as chemical flotation, gravity separation, magnetic separation, and biological beneficiation also encounter challenges such as insufficient adaptability to different low-grade and complex phosphate ores, limited and singular impurity removal methods, complex processes, high costs, and lack of environmental friendliness. Therefore, using underground-mined low-grade, complex, and difficult-to-process phosphate rock to meet the raw material needs of various existing phosphate chemical products has become a problem that must be solved.

[0003] With technological advancements, photoelectric mineral processing has proven highly effective as a novel mineral processing method. Furthermore, the support of machine learning and intelligent algorithms has enabled the development of new mineral processing technologies in coal and metal mines. Its highly efficient and precise identification and sorting principles, along with its excellent processing capabilities, make it well-suited for complex phosphate ores of varying grades, providing a promising solution to the aforementioned problems. After using photoelectric mineral separators to sort low-grade complex phosphate ores mined underground, it was found that regardless of whether the ore is from surface or underground mining, or regardless of the composition of the phosphate ores, the machine can sort the raw ore into concentrate and tailings, or concentrate, middlings, and tailings, according to the sorting scheme requirements set after deep learning. Combined with diverse and adjustable sorting schemes based on the grade and oxide content of the raw ore, the resulting concentrate, middlings, and tailings can, to a certain extent, meet the raw material needs of various downstream phosphate chemical products, realizing the multi-directional utilization of low-grade, lean, and complex phosphate ores mined underground. This technology requires no added reagents or incurs additional costs; it is intelligent, efficient, and widely applicable, with broad industrial application prospects.

[0004] To address the aforementioned issues, a system and method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting are needed. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for underground mining of low-grade phosphate ore based on photoelectric mineral processing and pre-sorting.

[0006] The solution of the present invention is:

[0007] The low-grade phosphate ore is sorted using a photoelectric concentrator. The raw phosphate ore is screened by a closed-circuit vibrating screen (10mm and 40mm) and then by a vibrating cloth screen in the photoelectric concentrator to obtain 10-40mm mineral particles. After passing through an X-ray transmission belt, the particles obtain electrical signals containing mineral information. These signals are identified by the mineral classification learning model algorithm of the photoelectric concentrator, and the central processing unit directs the injection system to separate the low-grade phosphate ore into feed-grade calcium phosphate and ammonium phosphate raw materials and tailings containing different P2O5 grades and oxide contents. The tailings rejection rate is <12%. The photoelectric concentrator performs a three-product sorting scheme, and the middlings from the three-product sorting are then further sorted by the photoelectric concentrator using a two-product sorting scheme.

[0008] As a preferred technical solution, the three-product scheme is set by the separation threshold range in the photoelectric mineral separator. The concentrate separation threshold range of the three-product scheme is ≥45, 45 > the middlings separation threshold range of the three-product scheme is >19, and the tailings separation threshold range of the three-product scheme is ≤19.

[0009] As a preferred technical solution, the two-product solution sets the separation threshold range in the photoelectric mineral sorting machine, with the concentrate separation threshold range being ≥36 and the tailings reverse separation threshold range being ≤35.

[0010] As a preferred technical solution, the three-product scheme of the photoelectric mineral separator is used to separate the mined low-grade phosphate ore into concentrate, middlings, and tailings with different P2O5 grades. The concentrate with P2O5 grade >26%, MgO content <2%, Fe2O3 content <0.85%, and Al2O3 content <0.90% is used as the raw material for feed-grade calcium phosphate. The middlings are used for further separation in the two-product scheme of the subsequent photoelectric mineral separator. The tailings with P2O5 grade of 3% to 6% and MgO content of 10% to 12% are used as backfill aggregate for the mined-out areas.

[0011] As a preferred technical solution, the middlings with a P2O5 grade of 15% to 20% obtained from the three-product separation scheme are used as new raw ore. The concentrate and tailings are obtained by separation using the two-product scheme. The concentrate with a P2O5 grade of 20% to 22% and an MgO content of 5% to 7% obtained from the two-product separation scheme is used as raw material for ammonium phosphate. The concentrate with a P2O5 grade of 4% to 8% and an MgO content of 8% to 11% obtained from the two-product separation scheme is used as aggregate for backfilling mined-out areas in underground mining.

[0012] As a preferred technical solution, the raw ore feed parameters of the photoelectric concentrator are: 10-40mm particle size and minimal surface dust; the vibrating feed screen parameters are: operating frequency 42-50Hz, current 6.0-6.5A, amplitude 7-15mm, and screen mesh size 10mm; the conveyor belt parameters are: operating frequency 45Hz, moving speed 0.4m / s, and width 2m; the X-ray source parameters are: X... The X-ray wavelength is 0.2-0.5nm, the power is 10-50kv, the source temperature is 8-40℃, and the X-ray incident angle is 30-60°. The parameters of the blowing valve of the photoelectric mineral separator are: 192 large valves with an orifice diameter of 2mm and a blowing pressure of 0.4-0.65Mpa; 382 small valves with an orifice diameter of 1mm and a blowing pressure of 0.2-0.55Mpa; the blowing angle between the large and small valves is 42-96°; and the air inlet pipe has a pressure of 0.65-0.85Mpa.

[0013] As a preferred technical solution, the system for underground mining of low-grade phosphate ore based on photoelectric mineral processing pre-sorting includes a vibrating cloth screen, a conveyor belt, an X-ray source, a jetting system, and a central processing unit. The central processing unit includes a data analysis and processing system, an operation and online operating system. The discharge port of the vibrating cloth screen is located above the upstream of the conveyor belt. An X-ray source is provided on the conveyor belt, and the jetting system is provided at the downstream end of the conveyor belt. The sensor of the X-ray source is connected to the central processing unit.

[0014] Advantages of this invention:

[0015] This invention efficiently separates low-grade, complex phosphate rock into phosphate rocks of different grades and oxide contents. These different types of separated ore are then used to meet the needs of downstream feed-grade calcium phosphate and ammonium phosphate production. At the same time, some tailings are removed in advance, broadening the utilization of the original mined phosphate rock through multiple pathways and improving the comprehensive utilization rate of phosphate rock resources.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. Wide range of mineral applications. The photoelectric separator has multiple sorting scheme options for different minerals, grades, and oxides. The sorting scheme for phosphate rock can be changed and set according to production needs to adapt to different process mineralogical characteristics.

[0018] 2. Intelligent and efficient with high processing capacity. The photoelectric mineral processing machine itself has the advantages of machine learning, artificial intelligence and big data algorithm models, which enables it to quickly and accurately separate phosphate ore of different grades within 0.4ms with a processing capacity of 50-55t / h.

[0019] 3. Achieve multi-path utilization of phosphorus resources. By using photoelectric mineral separators and different sorting schemes set through machine learning, single raw ore can be separated into feed-grade calcium phosphate, ammonium phosphate, and tailings raw materials to meet different downstream utilization needs, thus realizing the comprehensive utilization of phosphorus resources.

[0020] 4. Green and low-cost. As a dry mineral processing equipment, the photoelectric mineral separator does not require the addition of any chemical reagents or media for separation. It only requires electricity as an energy source to carry out the separation work normally.

[0021] 5. Adjustable multi-threaded processing of high-content oxides. Unlike existing phosphate rock sorting processes, photoelectric mineral separators can simultaneously sort sesquioxides and other major oxides present in large quantities in minerals, and can also arbitrarily change different oxide sorting indicators and parameters according to different mineral categories. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the present invention;

[0023] Figure 2 This is a schematic diagram of the photoelectric mineral separator in this invention;

[0024] Figure 3 This is a framework diagram of the K-value judgment principle and calculation process of the photoelectric mineral separator in this invention;

[0025] Among them, 1-vibrating cloth distributor; 2-transmission belt; 3-X-ray source; 4-X-ray detection sensor; 5-blowing system; 6-data analysis and processing system; 7-operation and online monitoring system; 8-mined low-grade phosphate ore. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0027] Figure 2 A system for underground mining of low-grade phosphate ore based on photoelectric mineral processing and pre-sorting is shown. It includes a vibrating cloth screen, a conveyor belt, an X-ray source, a jetting system, and a central processing unit. The central processing unit includes a data analysis and processing system, an operation and online operating system. The discharge port of the vibrating cloth screen is located above the upstream of the conveyor belt. The X-ray source is installed on the conveyor belt. The jetting system is located at the downstream end of the conveyor belt. The sensor of the X-ray source is connected to the central processing unit.

[0028] Working principle:

[0029] Representative concentrates, middlings, and tailings that meet the requirements for feed-grade calcium phosphate and ammonium phosphate raw materials are selected from the underground low-grade phosphate ore to be sorted in advance. Then, according to the sorting requirements, a photoelectric mineral separator is used to conduct machine learning on the representative phosphate ore samples. The corresponding big data algorithm model and optimized process parameters are then tested, optimized, and developed, and a mature process scheme for sorting underground low-grade phosphate ore is obtained in sequence. After the above work is completed, the low-grade raw ore mined underground is fed into a mobile crushing station. After passing through a two-stage, closed-circuit crushing and screening system, ore particles with a diameter of 10-40mm are obtained, suitable for entering the photoelectric separator. These particles are then passed through a vibrating cloth screen 1 to form a non-overlapping ore layer before entering a conveyor belt 2. The ore particles on conveyor belt 2 are transmitted through an X-ray source 4, and the collected mineral information and spectral data are transmitted to a data analysis and processing system 6. After efficient calculation by a big data model, all the transmitted phosphate ore is labeled with digital virtual tags indicating concentrate, middlings, and tailings. When the phosphate ore on conveyor belt 2 is ejected from the belt, it is precisely sprayed by a spraying system 5 to different mining areas, thus achieving the separation of the raw ore. In the big data model, ore with a P2O5 grade >20% and MgO content <5% is defined as concentrate; ore with a P2O5 grade <6% and MgO content >8% is defined as tailings; and ore in between is defined as middlings.

[0030] Within the algorithm model, the content values ​​of the main spectral information of the ore extracted from the X-ray source, namely P2O5, MgO, Fe2O3, Al2O3, SiO2, and CaCO3, are normalized to obtain standard values. These standard values ​​are then substituted into the K-value calculation formula along with the weight values ​​of each compound component obtained from pre-machine learning to calculate the K-value for each piece of phosphate rock. This K-value is then compared with the pre-set selection threshold Ki_{\text{threshold}} for each of the two or three products. The product is selected as the corresponding product based on the K-value within the threshold range.

[0031] like Figure 1 As shown, an X-ray scanner is used to scan the lumpy raw materials and tailings from low-grade underground ore that meet the production requirements of feed-grade calcium phosphate and ammonium phosphate. The corresponding characteristic parameters of different minerals are obtained. Based on the different requirements of users for the P2O5 grade and the main oxides such as Fe2O3, Al2O3, MgO and SiO2 in the raw ore, an algorithm model is established. This model includes the setting of two or three product separation parameters and pre-production debugging. Then, through continuous optimization, the most suitable separation process parameters are achieved. Finally, two-product and three-product schemes are obtained for separating different raw ores and obtaining different utilization paths for phosphate chemical products.

[0032] After the plan is finalized, the mined raw ore undergoes screening, crushing, screening, and distribution screening at the front-end mobile crushing station to obtain a layer of non-overlapping, non-agglomerated mineral particles that meet the 10-40mm particle size requirements for photoelectric separation. This mineral layer is transported by conveyor belt to the X-ray source of the equipment for transmission. The resulting mineral sample separation information and spectral data are fed into the data processing and analysis system. After processing and analysis using a high-efficiency artificial intelligence algorithm model, the system digitally identifies ores that meet the requirements for concentrate, middlings, and tailings. The digitally identified mineral information is transmitted to the injection system for precise injection and separation into different products. The concentrate obtained from the three-product separation is used as feed-grade calcium phosphate raw material, the middlings are used as raw material for the next stage of the two-product separation, and the tailings are recycled for backfilling underground mining voids. The middlings from the first separation are used as raw material for the second separation, again entering the photoelectric separator. The concentrate from the second separation meets the requirements for ammonium phosphate raw material and is used for phosphate fertilizer production, while the tailings are recycled for backfilling underground mining voids.

[0033] like Figure 3As shown, before applying the photoelectric mineral processing two- and three-product separation scheme to the raw ore spraying process, it is necessary to first extract the main spectral information based on the X-ray transmission of the ore from the source, and calculate the contents of P2O5, MgO, Fe2O3, Al2O3, and SiO2. Then, the content values ​​of each compound are normalized to calculate the standard content values ​​of each major compound. Subsequently, these standardized values ​​and the weight values ​​of each compound obtained by earlier machine learning are substituted into the K-value calculation formula. The calculated K-value is the real-time value of a single piece of ore. Finally, the K-value is compared with the threshold Ki_{\text{threshold}} of each product pre-set in the judgment conditions. If it is greater than the threshold 1, it is selected as concentrate; if it is less than the threshold 2, it is selected as tailings; and if it is between the two thresholds, it is selected as middlings. Alternatively, if it is greater than the threshold 3, it is selected as concentrate; and if it is less than the threshold 4, it is selected as tailings. Based on the actual grade of underground phosphate ore, machine learning results, and sorting targets, the specific thresholds for each product in each sorting scheme are as follows: In the three-product scheme, the sorting threshold K is set as follows: concentrate K≥K_{\text{threshold}}=45, middlings K_{\text{threshold}}=45>K>K_{\text{threshold}}=19, and tailings K≤K_{\text{threshold}}=19; In the two-product scheme, the sorting threshold K is set as follows: concentrate K≥K_{\text{threshold}}=36, and tailings K≤K_{\text{threshold}}=35.

[0034] The process parameters for the three-product and two-product separation schemes of the photoelectric mineral separator are mainly divided into five aspects: a. Raw ore feed parameters: 10-40mm particle size, minimal surface dust. b. Vibrating cloth screen parameters: Working frequency 42-50HZ, current 6.0-6.5A, amplitude 7-15mm, screen aperture 10mm. c. Belt feeder parameters: Working frequency 45HZ, moving speed 0.4m / s, width 2m. d. X-ray source parameters: X-ray wavelength 0.2-0.5nm, power 10-50kV, source temperature 8-40℃, X-ray incident angle 30-60°. e. Pulse valve parameters. Large valve: 192 in number, 2mm orifice diameter, 0.4-0.65Mpa blowing pressure; Small valve: 382 in number, 1mm orifice diameter, 0.2-0.55Mpa blowing pressure; Blowing angle of large and small valves: 42-96°; Inlet pipe: 0.65-0.85Mpa.

[0035] Example 1

[0036] The low-grade phosphate rock mined underground with a P2O5 grade of 18.71% and MgO content of 5.74% was sorted through a three-product process to obtain a concentrate with a P2O5 grade of 26.55%, tailings with a P2O5 grade of 5.21%, and middlings with a P2O5 grade of 17.08%, which were used as the raw ore in the subsequent two-product sorting process. The concentrate had a lower content of major oxides such as Fe2O3, Al2O3, MgO, and SiO2 than the raw ore. The concentrate with a P2O5 grade >26% and MgO content <2% was used as the raw ore for feed-grade calcium phosphate. The middlings were used for further sorting in the two-product process, and the tailings were recycled and reused.

[0037]

[0038] Example 2

[0039] Using the middlings from Example 1 as the raw ore, the two-product separation process of the photoelectric mineral separator yielded a concentrate with a P2O5 grade of 20.95% and tailings with a P2O5 grade of 5.25%. The contents of major oxides such as Fe2O3, Al2O3, MgO and SiO2 in the concentrate were lower than those in the raw ore. The concentrate with a P2O5 grade of 20%-22% and a MgO content of 5%-7% was used as the raw material for ammonium phosphate. The tailings were also recycled and reused.

[0040]

[0041] Example 3

[0042] The underground-mined medium-grade phosphate rock with a P2O5 grade of 21.90% and an MgO content of 4.62% was directly sorted through a three-product process to obtain a concentrate with a P2O5 grade of 28.72%, a middlings ore of 12.03%, and a tailings ore of 4.89%. The content of major oxides such as Fe2O3, Al2O3, MgO, and SiO2 in the concentrate is lower than that in the original ore. This concentrate meets the requirements for feed-grade calcium phosphate. The middlings and tailings are then comprehensively recycled.

[0043]

[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-separation, characterized in that: The low-grade phosphate ore is sorted using a photoelectric mineral separator. The raw phosphate ore is first screened by a closed-circuit vibrating screen (10mm and 40mm) and then by a vibrating cloth screen in the photoelectric mineral separator to obtain 10-40mm particles. These particles are then transmitted via X-rays on a conveyor belt to obtain electrical signals containing mineral information. The photoelectric mineral separator identifies the minerals, and the central processing unit directs the injection system to separate the low-grade phosphate ore into feed-grade calcium phosphate and ammonium phosphate raw materials and tailings containing different P2O5 grades and oxide contents. The tailings rejection rate is <12%. The photoelectric mineral separator performs a three-product sorting process, and the middlings from this process are then further sorted using a two-product sorting process in the photoelectric mineral separator. After separating the low-grade phosphate ore using a photoelectric mineral separator with a three-product scheme, concentrate, middlings, and tailings with different P2O5 grades are obtained sequentially. The concentrate with P2O5 grade >26%, MgO content <2%, Fe2O3 content <0.85%, and Al2O3 content <0.90% is used as the raw material for feed-grade calcium phosphate. The middlings are used for further separation using a photoelectric mineral separator with a two-product scheme. The tailings with P2O5 grade of 3% to 6% and MgO content of 10% to 12% are used as backfill aggregate for the mined-out areas. The middlings with a P2O5 grade of 15%–20% obtained from the three-product separation scheme are used as new raw ore. The concentrate and tailings are obtained by separation using the two-product scheme. The concentrate with a P2O5 grade of 20%–22% and an MgO content of 5%–7% obtained from the two-product separation scheme is used as raw material for ammonium phosphate. The concentrate with a P2O5 grade of 4%–8% and an MgO content of 8%–11% obtained from the two-product separation scheme is used as aggregate for backfilling mined-out areas in underground mining.

2. The method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting as described in claim 1, characterized in that: The three-product scheme is set by the separation threshold range in the photoelectric mineral separator. The concentrate separation threshold range of the three-product scheme is ≥45, 45 > the middlings separation threshold range of the three-product scheme is >19, and the tailings separation threshold range of the three-product scheme is ≤19.

3. The method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting as described in claim 1, characterized in that: The two-product scheme uses the sorting threshold range set in the photoelectric mineral separator to perform sorting. The concentrate sorting threshold range of the two-product scheme is ≥36, and the tailings reverse sorting threshold range of the two-product scheme is ≤35.

4. The method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting as described in claim 1, characterized in that: The raw ore feed parameters of the photoelectric concentrator are: particle size of 10-40mm and minimal surface dust; the vibrating feed screen parameters are: operating frequency of 42-50Hz, current of 6.0-6.5A, amplitude of 7-15mm, and screen mesh size of 10mm; the conveyor belt parameters are: operating frequency of 45Hz, moving speed of 0.4m / s, and width of 2m; the X-ray source parameters are: X-ray wavelength of 0... The X-ray intensity ranges from 0.2 to 0.5 nm, the power ranges from 10 to 50 kV, the source temperature ranges from 8 to 40°C, and the X-ray incident angle ranges from 30 to 60°. The parameters of the blowing valves in the photoelectric mineral separator are as follows: 192 large valves with an orifice diameter of 2 mm and a blowing pressure of 0.4 to 0.65 MPa; 382 small valves with an orifice diameter of 1 mm and a blowing pressure of 0.2 to 0.55 MPa; the blowing angle between the large and small valves is 42 to 96°; and the air inlet pipe has a pressure of 0.65 to 0.85 MPa.

5. The method for underground mining of low-grade phosphate rock based on photoelectric mineral processing and pre-sorting as described in claim 1, characterized in that: The system used in the method for underground mining of low-grade phosphate ore based on photoelectric mineral processing pre-sorting includes a vibrating cloth screen, a conveyor belt, an X-ray source, a jetting system, and a central processing unit. The central processing unit includes a data analysis and processing system, an operation and online operating system. The discharge port of the vibrating cloth screen is located above the upstream of the conveyor belt. An X-ray source is installed on the conveyor belt, and the jetting system is installed at the downstream end of the conveyor belt. The sensor of the X-ray source is connected to the central processing unit.

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