A heavy magnetic pre-selection and tailing method for complex rare earth ore with narrow particle size

Abstract

The present application provides a kind of complex rare rare earth ore narrow particle size heavy magnetic preselection tailing method, belong to the technical field of mineral separation, comprising the following steps: the raw ore is broken to first size by jaw crusher, and the broken raw ore is closed-circuit crushed to second size by high-pressure roller mill;The crushed raw ore is screened into first size, second size and third size by screening equipment;The first size raw ore is separated by heavy medium cyclone, and part of coarse-grained tailings is thrown away;The second size raw ore is separated by Nelson centrifugal gravity separation, and part of tailings is thrown away;First size and second size two kinds of relatively coarse-grained gravity separation concentrate are ground by tower mill, and grinding product is obtained, and the grinding product is subjected to high-intensity magnetic separation under a specific magnetic induction intensity, to obtain mixed concentrate and non-magnetic concentrate.Third size is relatively fine-grained, and Nelson centrifugal gravity separation is directly used, and the gravity separation concentrate is separated under a specific magnetic induction intensity, to obtain mixed concentrate and non-magnetic concentrate.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral separation, and in particular to a method for narrow-size gravity magnetic pre-selection and tailings discarding of complex rare earth ores. Background Art

[0002] For the sorting of complex rare earth ores, single physical sorting is difficult to effectively recover a variety of target minerals, and a combined sorting process of gravity, magnetic and flotation is usually adopted. Gravity separation and magnetic separation are mostly used for pre-enrichment of early minerals, while flotation is mostly used for later concentration operations. Gravity separation mainly separates rare earth and rare metal minerals from low-density gangue minerals under coarse particle size conditions to achieve the purpose of pre-discarding tailings. The main equipment includes spiral chutes, shaking tables and centrifugal concentrators. Magnetic separation utilizes the weak magnetism of rare and rare earth minerals or the weak magnetism of associated minerals with iron-containing minerals to separate them from non-magnetic gangue minerals. The Bayan Obo complex rare earth ore adopts a weak magnetic-strong magnetic-flotation process to sort rare earth ores, that is, strong magnetic pre-enrichment is adopted. After weak magnetic separation of magnetite before flotation, strong magnetic separation enriches rare earth and rare metal elements. Single strong magnetic pre-enrichment cannot guarantee the recovery of non-magnetic rare metals and rare earth ores.

[0003] The rare earth separation process in Mianning, Sichuan, adopts the gravity separation-strong magnetic separation-flotation process. Before flotation, a single shaking table is used for pre-enrichment, which will result in a small amount of low-density or fine-grained rare earth minerals entering the tailings. After optimization, strong magnetic separation is introduced, which greatly improves the recovery rate of rare earths and rare metals. The Nechalacho complex rare earth and rare metal mine in Canada explored the possibility of gravity separation tailings, and compared the pre-selection tailings removal effects of the Nelson centrifugal concentrator and spiral chute. It was found that both can remove gangue minerals such as feldspar, but the Nelson centrifugal concentrator has a more relaxed feed particle size limit.

[0004] The reason why complex rare metal and rare earth ores are difficult to be selected is that their embedded particles are fine and complex, the mineral composition of the ore is diverse, and the sorting characteristics of many minerals (specific gravity, specific magnetic susceptibility, and flotation characteristics) are very similar. A single physical field tailing can easily cause the loss of useful minerals. Summary of the Invention

[0005] In response to the aforementioned technical problems, a method for narrow-size gravity-magnetic pre-selection and tailings removal for complex rare earth ores is provided. This method combines gravity and magnetic separation after grinding, achieving dual tailings removal, ensuring the recovery of all useful elements. It also removes a large amount of gangue minerals before flotation, reducing the burden on subsequent operations, lowering costs, and improving efficiency.

[0006] The technical means adopted in the present invention are as follows:

[0007] A complex mineral rare earth gravity magnetic combined narrow particle size tailings discarding method comprises the following steps:

[0008] Step 1: crush the raw ore to the first size by a jaw crusher, and then grind the crushed raw ore to the second size by a high pressure roller mill in a closed circuit;

[0009] Step 2: The crushed raw ore is screened into the first, second and third particle sizes by screening equipment;

[0010] Step 3: The raw ore of the first particle size is sorted by a heavy medium cyclone to discard some coarse tailings; the raw ore of the second particle size is subjected to Nelson centrifugal gravity separation to discard some tailings; the first and second particle size gravity separation concentrates are ground by a tower mill to obtain grinding products; the grinding products are subjected to strong magnetic separation under a specific magnetic induction intensity to obtain mixed concentrate and non-magnetic concentrate; the third particle size is directly subjected to Nelson centrifugal separation, and the separated concentrate is sorted under a specific magnetic induction intensity to obtain weak magnetic concentrate and non-magnetic concentrate.

[0011] Furthermore, the first size is: 20mm-50mm.

[0012] Furthermore, the second size is: 2mm-3mm.

[0013] Furthermore, the maximum size of the first particle size is equal to the second size, and the minimum size is 0.3 mm to 0.6 mm.

[0014] Furthermore, the maximum size of the particle size of the second particle size is the minimum size of the particle size of the first particle size, and the minimum size of the particle size of the second particle size is 0.045 mm-0.074 mm.

[0015] Furthermore, the maximum size of the particles of the third particle size is the minimum size of the particles of the second particle size.

[0016] Furthermore, the specific magnetic induction intensity is 10000Gs-15000Gs.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The gravity separation equipment of the present invention combines a heavy medium cyclone, a Nelson centrifugal concentrator, and a wet high-gradient magnetic separator, thereby ensuring a high recovery rate of various useful minerals and simultaneously being able to discard a large amount of gangue minerals.

[0019] The tailings discarding method of first gravity separation and then magnetic separation in the present invention is the key. For complex rare earth ores, useful mineral fine particles are embedded and evenly distributed, and the magnetic difference between useful minerals and gangue minerals is small. Gravity separation first can ensure a low distribution rate of useful minerals in the tailings. In addition, gravity separation consumes less energy than magnetic separation. Gravity separation first reduces the amount of ore and then magnetic separation, which saves more mineral processing costs.

[0020] The present invention adopts a narrow particle size preselection method, which not only reduces the burden of the grinding machine, but also effectively prevents the mineral from being over-grinded, thereby improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 This is a process flow chart for preselecting tailings for the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] like Figure 1 As shown, the present invention provides a complex mineral type rare earth gravity magnetic combined narrow particle size tailings discarding method, comprising the following steps:

[0026] Step 1: Crushing the raw ore to a first size using a jaw crusher. The crushed raw ore is then crushed to a second size using a high-pressure roller mill in a closed circuit. In this application, the first size is set to 20 mm to 50 mm, and the second size is set to 2 mm to 3 mm.

[0027] Step 2: The crushed raw ore is screened into a first, second, and third size fractions using a screening device. The maximum size of the first size fraction is equal to the second size fraction, and the minimum size fraction is 0.3 mm to 0.6 mm. The maximum size of the second size fraction is equal to the minimum size fraction of the first size fraction, and the minimum size fraction of the second size fraction is 0.045 mm to 0.074 mm. The maximum size of the third size fraction is equal to the minimum size fraction of the second size fraction.

[0028] Step 3: The raw ore of the first particle size is sorted by a heavy medium cyclone to discard some coarse tailings; the raw ore of the second particle size is subjected to Nelson centrifugal gravity separation to discard some tailings; the first and second particle size gravity separation concentrates are ground by a tower mill to obtain grinding products; the grinding products are subjected to strong magnetic separation under a specific magnetic induction intensity to obtain mixed concentrate and non-magnetic concentrate; the third particle size is directly subjected to Nelson centrifugal separation, and the separated concentrate is sorted under a specific magnetic induction intensity to obtain weak magnetic concentrate and non-magnetic concentrate.

[0029] In this application, the specific magnetic induction intensity is 10000Gs-15000Gs.

[0030] Example 1

[0031] This specific embodiment uses a narrow particle size gravity separation-high intensity magnetic separation method to separate a complex rare earth ore in Inner Mongolia. The ore contains 0.41% Nb2O5, 2.77% ZrO2, 0.50% TREO, approximately 0.02% U, 78.21% SiO2, 3.50% TFe, 0.1% BeO, 0.40% TiO2, 8.50% Al2O3, 3.00% K2O, 0.20% MgO, 0.55% CaO, and 0.01% S.

[0032] First, the drill core sample is crushed to a -30mm particle size using a jaw crusher. The crushed product is then closed-circuited in a high-pressure roller mill to a -2mm particle size. It is then screened into three particle sizes: -2+0.5mm, -0.5+0.074mm, and -0.074mm. The -2+0.5mm particle size is separated using a dense medium cyclone, with some coarse tailings discarded. The -0.5+0.074mm particle size undergoes Nielsen centrifugal gravity separation, with some tailings discarded. The two coarser gravity separation concentrates are then ground in a tower mill. The ground products undergo high-intensity magnetic separation at a specific magnetic induction intensity to produce a mixed concentrate containing rare earth elements, niobium, and a small amount of zirconium, and a non-magnetic concentrate containing primarily zirconium. The -0.074mm tailings undergo Nielsen gravity separation, and the concentrate undergoes high-intensity magnetic separation to produce a mixed concentrate containing rare earth elements, niobium, and a small amount of zirconium, and a non-magnetic concentrate containing primarily zirconium. After the -0.074mm tailings undergo Nielsen gravity separation, the concentrate undergoes high-intensity magnetic separation to produce a mixed concentrate containing rare earth elements, niobium, and a small amount of zirconium, and a non-magnetic concentrate containing zirconium.

[0033] After ultra-fine crushing by high-pressure roller mill, the yield and grade of each particle size are screened as shown in Table 1.

[0034] Table 1. Screening product test results

[0035]

[0036] The results of the -2+0.5mm particle size dense medium separation test are shown in Table 2.

[0037] Table 2. Results of heavy medium separation test

[0038]

[0039] The results of -0.5+0.074mm Nielsen centrifugal sorting are shown in Table 3.

[0040] Table 3 -0.5+0074mm centrifugal separation test results

[0041]

[0042] The results of the Nielsen centrifugal separation test for the -0.074 mm particle size are shown in Table 4.

[0043] Table 4. -0.074mm centrifugal sorting test results

[0044]

[0045] The -2+0.5mm and -0.5+0.074mm gravity concentrates were mixed and ground to -0.074mm, accounting for 80%. The product analysis results obtained by strong magnetic separation are shown in Table 5.

[0046] Table 5. Strong magnetic test results of products after grinding

[0047]

[0048] The results of high-intensity magnetic separation of the concentrate after Nelson centrifugal separation of -0.074 mm particle size are shown in Table 6.

[0049] Table 6. -0.074mm gravity concentrate strong magnetic separation test results

[0050]

[0051] The serial numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts not described in detail in a particular embodiment, please refer to the relevant description of other embodiments. In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented by other means.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A complex mineral rare earth gravity magnetic combined narrow particle size tailings removal method, characterized in that: The following steps are involved: Step 1: crush the raw ore to the first size by a jaw crusher, and then grind the crushed raw ore to the second size by a high pressure roller mill in a closed circuit; Step 2: The crushed raw ore is screened into the first, second and third particle sizes by screening equipment; Step 3: The raw ore of the first particle size is sorted by a heavy medium cyclone, and some coarse tailings are discarded; the raw ore of the second particle size is subjected to Nelson centrifugal gravity separation, and some tailings are discarded; the first and second particle size gravity separation concentrates are ground by a tower mill to obtain a grinding product; the grinding product is subjected to strong magnetic separation under a specific magnetic induction intensity to obtain a mixed concentrate and a non-magnetic concentrate; the third particle size is directly subjected to Nelson centrifugal separation, and the separated concentrate is sorted under a specific magnetic induction intensity to obtain a weak magnetic concentrate and a non-magnetic concentrate; the first size is: 20mm-50mm; the second size is: 2mm-3mm; the maximum size of the particle size of the first particle size is equal to the second size, and the minimum size is 0.3mm-0.6mm; the maximum size of the particle size of the second particle size is the minimum size of the particle size of the first particle size, and the minimum size of the particle size of the second particle size is 0.045mm-0.074mm; the maximum size of the particle size of the third particle size is the minimum size of the particle size of the second particle size.

2. A complex mineral type rare earth gravity magnetic combined narrow particle size tailings removal method according to claim 1, characterized in that: The specific magnetic induction intensity is 10000Gs-15000Gs.

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