A roughing and separation beneficiation method for coastal sand

Abstract

This invention discloses a roughing and separation beneficiation method for coastal sand. The method includes the following steps: the raw coastal sand ore is first screened with a grid sieve to remove sand and impurities of +2mm size. The raw ore of -2mm size is then scrubbed with a high-power scrubbing machine for 8-10 minutes, followed by further pre-classification using a high-frequency vibrating screen to separate it into -2+0.425mm and -0.425mm grades. The raw ore of -0.425mm grade is further classified using a vibrating screen to obtain two grades: -0.425+0.074mm and -0.074mm. The two grades are then subjected to gravity separation. The gravity separation process is a roughing-mid-ore re-selection-cleaning test process, which achieves effective separation of titanium and zirconium minerals of -0.15mm size from other minerals.

Description

Technical Field

[0001] This invention relates to the field of roughing technology for coastal sand, and specifically to a roughing separation and beneficiation method for coastal sand. Background Technology

[0002] Coastal placer deposits are secondary deposits formed by the separation of clastic materials transported by rivers, weathered coastal rocks, or eroded by existing deposits, resulting in the enrichment of denser heavy minerals in the wave-bearing zone or intertidal zone by waves, tides, and ocean currents. The mineral composition of coastal sand ore is complex, including more than 40 mineral resources such as ilmenite, zircon, rutile, and monazite. Currently, the commonly used roughing process for coastal sand ore production is a single gravity separation process. The raw coastal sand ore is directly fed into a spiral sluice for gravity separation two or more times to obtain a gravity concentrate. For example, CN 102614978 A discloses that the raw coastal sand ore is directly fed into a spiral sluice for roughing to obtain a comprehensive roughing concentrate. The comprehensive roughing concentrate has a titanium content of TiO2 ≥ 27%, a fineness of -0.074 mm of about 80%, and a titanium metal distribution rate of ≥ 97%. However, this technology does not effectively separate fine particles (-0.15 mm particle size) of titanium and zirconium minerals from other minerals during the roughing process. Therefore, further improvement is needed, and this invention is proposed. Summary of the Invention

[0003] The purpose of this invention is to provide a roughing and separation beneficiation method for coastal sand, which solves the problem that the existing coastal sand roughing process does not achieve effective separation of titanium and zirconium minerals with fine particles of -0.15mm from other minerals.

[0004] This invention is achieved through the following technical solutions:

[0005] A roughing and separation beneficiation method for coastal sand, the method comprising the following steps:

[0006] 1) Use a grid screen to screen out +2mm sand and impurities (i.e. tailings 1) to avoid large particles and impurities clogging the pipeline. -2mm particles enter the scrubbing process and are scrubbed for 8-10 minutes with a high-power scrubbing machine to separate the clay and fine mud adhering to its surface (to reduce the impact of clay and fine mud on the titanium and zirconium separation effect) and obtain the raw sand.

[0007] 2) The raw sand after washing in step 1) is pre-screened using a high-frequency vibrating screen and divided into -2+0.425mm and -0.425mm grades. The -2+0.425mm grade is coarse sand 2 with low titanium and zirconium content, which is tailings 2. It is removed in advance to reduce the amount of gravity separation, improve the grade of gravity separation feed and improve the equipment processing capacity.

[0008] 3) The -0.425mm grade raw ore obtained in step 2) is further pre-sorted and classified using a vibrating screen to obtain two particle sizes: -0.425 +0.074mm and -0.074mm. These are then fed into the gravity separation process to effectively recover the -0.15mm grade fine titanium and zirconium particles.

[0009] The raw ore with a particle size of -0.425 to +0.074 mm enters the gravity separation process. The specific steps are as follows: gravity separation is carried out using a spiral concentrator. The process is roughing-mid-mineral re-concentration-cleaning gravity separation process to obtain titanium-zirconium rough concentrate 1, titanium-zirconium middlings 1 and tailings 3. The gravity separation process for the raw ore with a particle size of -0.074 mm is roughing-mid-mineral re-concentration-cleaning gravity separation process to obtain titanium-zirconium rough concentrate 2, titanium-zirconium middlings 2 and tailings 4.

[0010] The raw ore with a particle size of -0.425 to +0.074 mm enters the gravity separation process. The roughing-mid-cleaning gravity separation process specifically includes the following steps:

[0011] (1) A spiral concentrator was used for roughing to obtain titanium-zirconium rough concentrate 11, titanium-zirconium middlings 11, and titanium-zirconium tailings 11;

[0012] (2) The titanium-zirconium middlings 11 obtained in step (1) are sorted in the middlings re-selection process to obtain titanium-zirconium rough concentrate 12 and titanium-zirconium tailings 12.

[0013] (3) The titanium zirconium rough concentrate 11 obtained in step (1) and the titanium zirconium rough concentrate 12 obtained in step (2) are combined together to obtain a rough concentrate that enters the fine treatment process and is fined by spiral concentrator to obtain titanium zirconium rough concentrate 1, titanium zirconium middlings 1 and fine tailings 13. Fine tailings 13 are combined with titanium zirconium tailings 11 obtained in step (1) and titanium zirconium tailings 12 obtained in step (2) to become tailings 3.

[0014] The process of roughing, middlings separation, and cleaning and gravity separation of 0.074mm fine-grained raw ore includes:

[0015] A: A spiral concentrator was used to rough the -0.074mm fine-grained raw ore to obtain titanium-zirconium rough concentrate 21, titanium-zirconium middlings 21, and titanium-zirconium tailings 21.

[0016] B: The titanium-zirconium middlings 21 obtained from the roughing process in step A are then further separated in the middlings re-selection process to obtain titanium-zirconium rough concentrate 22 and titanium-zirconium tailings 22.

[0017] C: The titanium-zirconium rough concentrate 21 obtained from the roughing process in step A and the titanium-zirconium rough concentrate 22 obtained from the middlings process in step B are combined together to obtain a rough concentrate that enters the fine treatment process and is finely treated using a spiral concentrator to obtain titanium-zirconium rough concentrate 2, titanium-zirconium middlings 2, and fine tailings 23. Among them, the fine tailings 23, the titanium-zirconium tailings 21 obtained from the roughing process in step A, and the titanium-zirconium tailings 22 obtained from the middlings process in step B are combined together to form tailings 4.

[0018] The most concentrated natural particle size range of the coastal sand ore is +0.074 mm, indicating that the natural particle size of the ore is relatively coarse. However, the particle size distribution of titanium and zirconium minerals is inconsistent with the natural particle size distribution of the ore. The intercalation particle size of titanium and zirconium minerals is consistent, mainly distributed in the 0.043~0.3 mm particle size range. This indicates that the intercalation particle size of titanium and zirconium in the ore is relatively fine. The influence of this particle size should be considered during gravity separation, and a graded gravity separation method should be adopted. For the +0.425 mm particle size ore, screening and classification should be used to directly discard the tailings.

[0019] The kaolinite, illite, and sericite in the raw ore are fine-grained and sticky, affecting the recovery of titanium and zirconium particles with a particle size of -0.15 mm. Therefore, a strong scrubbing method is used before classification and gravity separation to fully separate the clay micro-mud (i.e., kaolinite, illite, and sericite) adhering to the surface, which is beneficial to the effective separation of titanium and zirconium from fine-grained gangue in subsequent processes. For roughing of coastal sand containing a large amount of titanium and zirconium particles with a particle size of -0.15 mm, a conventional single-stage, wide-range gravity separation process is used to recover titanium and zirconium particles with a particle size of -0.15 mm. The recovery rate is very low. Therefore, this invention targets the raw sand after early removal of +2mm coarse sand and impurities. After the fine particles and sticky gangue are fully separated from the minerals by a strong scrubbing method, the -2+0.425mm coarse sand grade 2 (i.e. tailings 2) is removed by a pre-selection screening method. Then, it is screened and classified into two particle sizes: -0.425+0.074mm and -0.074mm. After that, gravity separation is carried out under narrow-grade conditions to improve the grade and recovery rate of -0.15mm fine titanium and zirconium particles.

[0020] The beneficial effects of this invention are as follows: Compared with existing roughing and separation methods for coastal sand, this invention uses a high-power scrubbing machine to scrub the -2mm particle size raw ore for 8-10 minutes, separating the fine mud and clay adhering to its surface, reducing the impact of fine mud and clay particles on the separation effect of titanium and zirconium, and improving the recovery rate of titanium and zirconium. Then, it uses a high-frequency vibrating screen for further pre-classification into -2+0.425mm and -0.425mm grades. The -0.425mm grade raw ore is further pre-classified to obtain two particle sizes: -0.425+0.074mm and -0.074mm. Then, gravity separation is carried out at this narrow grade using a spiral chute. The gravity separation process is a roughing-mid-ore re-selection-cleaning process, which achieves effective separation of titanium and zirconium minerals with finer particles of -0.15mm from other minerals. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the test process for Example 1: sieving - vigorous scrubbing - pre-selection sieving - pre-selection grading - grading and re-selection.

[0022] Figure 2 This is a schematic diagram of the classification and gravity separation test process for the -0.425mm particle size raw ore in Example 1;

[0023] Figure 3 This is a schematic diagram of the unclassified gravity separation test procedure for the -0.425mm particle size raw ore in Comparative Example 1. Detailed Implementation

[0024] The following is a further description of the invention, but not a limitation thereof.

[0025] Example 1:

[0026] The test ore samples were taken from Lufeng, Shanwei City, Guangdong Province. Approximately 3000 kg of raw ore samples (from four mining sites) were collected. The samples from the four mining sites were blended into a composite raw ore sample with a TiO2 content of 0.511% and a ZrO2 content of 0.150% for testing. The main equipment used in the test is shown in Table 1.

[0027] Table 1. Main equipment used in the experiment

[0028] I. Sample Analysis

[0029] The elemental composition of the raw sand was qualitatively determined by X-ray fluorescence, and the results are shown in Table 2. The content of major elements was quantitatively determined by chemical analysis methods, and the results are shown in Table 3. The content and particle size distribution of the coastal sand ore were tested, and the results are shown in Tables 4-6.

[0030] Table 2 Semi-quantitative analysis results of X-ray fluorescence spectra of raw ore

[0031] As shown in Table 2, the main valence metal elements in the sample are TiO2 and ZrO2, and the other metal elements are Fe2O3; the main non-metal element is SiO2, followed by small amounts of Al2O3, K2O, CaO and MgO.

[0032] Table 3. Results of multi-element chemical analysis of the raw ore

[0033] Table 3 shows that the main valuable metal elements in the raw ore are TiO2 (0.511%) and ZrO2 (0.15%), both of which are low in content. The contents of other useful metal elements are trace and have no comprehensive recovery value. Non-metallic silicon and aluminum have the potential for comprehensive utilization. TiO2 and ZrO2 are the target elements for comprehensive recovery in this experiment.

[0034] Table 4 Quantitative Detection Results of Raw Minerals ;

[0035] Table 5. Results of raw ore particle size analysis

[0036] Table 4 shows that the titanium minerals in the samples are mainly ilmenite, ilmenite-rich ilmenite, and leucite, followed by rutile; the zircon mineral is zircon; the iron minerals include trace amounts of hematite, limonite, and magnetite; trace amounts of rare earth minerals are present, including monazite, xenotime, and cerium aluminate; the gangue minerals are mainly quartz, followed by kaolinite, with small amounts of feldspar, illite, sericite, and calcite, and other minerals are present in trace amounts. Among them, kaolinite, illite, and sericite account for 2.241% of the mineral content, are fine-grained, and have a sticky texture, which affects the recovery of fine-grained titanium and zirconium in this study.

[0037] According to the particle size analysis results of the raw ore in Table 5, the yield of the +0.71mm particle size fraction was 11.50%, with TiO2 and ZrO2 distribution rates of 0.67% and 0.23%, respectively; the yield of the -0.71mm to +0.425mm particle size fraction was 13.28%, with TiO2 distribution rate of 1.30% and ZrO2 distribution rate of 0.27%. Since the content and distribution rate of TiO2 and ZrO2 in the +0.425mm particle size fraction are both low, the +0.425mm particle size fraction of the raw ore can be directly discarded as tailings by screening and grading.

[0038] As can be seen from Table 5, the most concentrated natural particle size range of the coastal sand ore is +0.074 mm, indicating that the natural particle size of the ore is relatively coarse. However, the particle size distribution of titanium and zirconium minerals is inconsistent with the natural particle size distribution of the ore. The particle size distribution of titanium and zirconium minerals is consistent, mainly distributed in the 0.043~0.3 mm particle size range, with a yield of 55.23%. Among them, the distribution rate of TiO2 is 87.58% and the distribution rate of ZrO2 is 96.88%, indicating that the particle size of titanium and zirconium minerals in the raw ore is relatively fine. The influence of this particle size should be considered during gravity separation, and a graded gravity separation method should be adopted. For the +0.425 mm particle size raw ore, screening and classification should be used for direct tailings disposal.

[0039] II. Coarse Separation and Recovery of Fine-Grained Titanium and Zirconium from Coastal Sand

[0040] like Figure 1 As shown, the raw seaside sand ore was first screened with a 2mm sieve (LKLM1224) to remove +2mm sand and impurities. The -2mm ore was then scrubbed with a high-power scrubbing machine for 8-10 minutes to separate the fine mud and clay adhering to its surface. After that, it was further pre-screened with a high-frequency vibrating screen to separate it into -2+0.425mm and -0.425mm grades. The -0.425mm grade ore was further pre-classified with a vibrating screen to obtain two particle sizes: -0.425+0.074mm and -0.074mm. The results are shown in Table 6.

[0041] Table 6 Results of the sieving-vigorous scrubbing-pre-selection sieving-pre-selection grading test

[0042] The experimental results in Table 6 show that TiO2 and ZrO2 have low content and distribution in the +0.425mm particle size, and can be directly discarded.

[0043] The -0.425mm particle size raw ore was classified and gravity separated. The process is described in [link to process description]. Figure 2 The results of the graded reselection test are shown in Table 7.

[0044] Table 7 Results of Gravity Separation Tests for Raw Ore with a Particle Size of -0.425mm

[0045] The results in Table 7 show that after the -0.425mm particle size raw ore was separated into two particle sizes, -0.425 +0.074mm and -0.074mm, respectively, the titanium zirconium rough concentrate obtained by the two particle size fractions was of TiO2 grade above 25% and ZrO2 grade above 10%, and the quality of both particles met the grade requirements of the roughing plant.

[0046] The recovery rates of TiO2 in the gravity separation rough concentrate (-0.425 +0.074 mm particle size) were 72.94% and ZrO2 were 86.24%. The combined recovery rates of TiO2 and ZrO2 in the titanium-zirconium rough concentrate and middlings were 85.61% and 95.88%, respectively. The combined recovery rates of TiO2 and ZrO2 in the raw ore were 73.01% and 87.54%, respectively. The ZrO2 recovery rate was relatively high, while the main loss of TiO2 was in the fine-grained tailings, particularly the low recovery rate of fine-grained leucoxene.

[0047] The recovery rates of TiO2 in the gravity separation rough concentrate of the -0.074mm particle size fraction were 33.23% and ZrO2 was 85.79%. The combined recovery rates of TiO2 in the titanium-zirconium rough concentrate and titanium-zirconium middlings were 38.99% and ZrO2 was 92.16%. The combined recovery rates of TiO2 in the raw ore of the titanium-zirconium rough concentrate and titanium-zirconium middlings were 4.78% and ZrO2 was 7.50%. While the ZrO2 recovery rate was relatively high in this particle size fraction, the TiO2 recovery rate was low. The titanium lost in the fine tailings mainly consisted of fine-grained ilmenite and leucoxene, which are difficult to recover through gravity separation.

[0048] Comparative Example 1:

[0049] Referring to Example 1, the difference is that the -0.425mm particle size raw ore was not graded for gravity separation experiments. See the flowchart below. Figure 3 The results are shown in Table 8.

[0050] Table 8 Results of Gravity Separation Tests on Raw Ore of -0.425mm Particle Size

[0051] Table 8 shows that when the -0.425mm particle size raw ore is directly subjected to spiral sluice gravity separation without classification, the grades of TiO2 and ZrO2 in the titanium and zirconium rough concentrates both decrease. The recovery rates of TiO2 and ZrO2 are also 17.15% and 15.65% lower, respectively, than those of the two-stage gravity separation of -0.425mm particle size. This is mainly because the separation zone is greatly affected by the slime during gravity separation. Gravity separation with classification of -0.425mm particle size raw ore is more effective than gravity separation without classification.

[0052] Comparative Example 2:

[0053] Referring to Example 1, the difference lies in that the -2mm particle size raw ore was scrubbed with a high-power mixer for 8-10 minutes, the pre-selected sieve particle size was different, resulting in a wider particle size, and no further screening and grading experiments were conducted. The specific steps are as follows: The raw ore was first screened with a grid sieve to remove +2mm particle size sand and impurities. The -2mm particle size raw ore was then scrubbed with a high-power mixer for 8-10 minutes. It was then graded with a vibrating screen to obtain two particle sizes: -2 +0.71mm and -0.71mm. After removing the +0.71mm coarse tailings, the -0.71mm particle size raw sand was directly gravity separated using a spiral chute. The results are shown in Table 9.

[0054] Table 9 Results of gravity separation test for raw ore with a particle size of -0.71mm

[0055] The results in Table 9 show that when the raw ore of the -0.71mm particle size is directly subjected to gravity separation without classification, the TiO2 and ZrO2 grades in the titanium and zirconium rough concentrates decrease significantly, and the recovery rates of TiO2 and ZrO2 are also lower than those of the two-stage gravity separation of the -0.425mm particle size, decreasing by 24.94% and 29.21%, respectively. The comparison between Example 1, Comparative Example 1 and Comparative Example 2 shows that when gravity separation is carried out without classification under a wider particle size range, the zoning is more affected by the slime.

[0056] Comparative Example 3:

[0057] Referring to Example 1, the difference lies in that the -2mm particle size raw ore was scrubbed with a high-power mixer for 8-10 minutes, and the -2mm particle size raw ore was directly subjected to gravity separation without pre-tailing or further classification. The specific steps are as follows: the raw ore was first screened with a grid sieve to remove +2mm particle size sand and impurities, the -2mm particle size raw ore was scrubbed with a high-power mixer for 8-10 minutes, and the -2mm particle size raw sand was directly subjected to gravity separation using a spiral chute. The results are shown in Table 10.

[0058] Table 10 Results of Gravity Separation Tests on Raw Ore with a Grain Size of -2mm Particle Size

[0059] The results in Table 10 show that when the raw ore of the -2mm particle size is directly subjected to gravity separation without classification, the enrichment of TiO2 and ZrO2 in the titanium and zirconium rough concentrate is relatively low. The recovery rates of TiO2 and ZrO2 are also lower than those of the two-stage gravity separation of -0.425mm particles, decreasing by 31.46% and 48.83% respectively. Under the condition of wider particle size, the zoning of gravity separation without classification is more affected by the slime, and it is difficult to enrich the titanium and zirconium rough concentrate to meet the requirements of market sales.

Claims

1. A roughing and separation beneficiation method for coastal sand, characterized in that, The method includes the following steps: 1) Use a grid screen to screen out sand and impurities with a particle size of +2mm. The -2mm particles enter the scrubbing process and are scrubbed for 8-10 minutes with a high-power scrubbing machine to obtain the raw sand. 2) The raw sand after washing in step 1) is pre-screened using a high-frequency vibrating screen and divided into -2+0.425mm and -0.425mm grades; 3) The -0.425mm grade raw ore obtained in step 2) is further pre-sorted and classified using a vibrating screen to obtain two particle sizes: -0.425 +0.074mm and -0.074mm. These are then fed into the gravity separation process to effectively recover the -0.15mm grade fine titanium and zirconium particles.

2. The method according to claim 1, characterized in that, In step 3), the -0.425 to +0.074 mm particle size raw ore enters the gravity separation process. The specific steps are as follows: gravity separation is carried out using a spiral concentrator. The process is roughing-mid-mineral re-concentration-cleaning gravity separation process to obtain titanium-zirconium rough concentrate 1, titanium-zirconium middlings 1 and tailings 3. The gravity separation process for the -0.074 mm fine particle size raw ore is as follows: roughing-mid-mineral re-concentration-cleaning gravity separation process to obtain titanium-zirconium rough concentrate 2, titanium-zirconium middlings 2 and tailings 4.

3. The method according to claim 2, characterized in that, The raw ore with a particle size of -0.425 to +0.074 mm enters the gravity separation process. The roughing-mid-cleaning gravity separation process specifically includes the following steps: (1) A spiral concentrator was used for roughing to obtain titanium-zirconium rough concentrate 11, titanium-zirconium middlings 11, and titanium-zirconium tailings 11; (2) The titanium-zirconium middlings 11 obtained in step (1) are sorted in the middlings re-selection process to obtain titanium-zirconium rough concentrate 12 and titanium-zirconium tailings 12. (3) The titanium zirconium rough concentrate 11 obtained in step (1) and the titanium zirconium rough concentrate 12 obtained in step (2) are combined together to obtain a rough concentrate that enters the fine treatment process and is fined by spiral concentrator to obtain titanium zirconium rough concentrate 1, titanium zirconium middlings 1 and fine tailings 13. Fine tailings 13 are combined with titanium zirconium tailings 11 obtained in step (1) and titanium zirconium tailings 12 obtained in step (2) to become tailings 3.

4. The method according to claim 2, characterized in that, The process of roughing, middlings separation, and cleaning and gravity separation of 0.074mm fine-grained raw ore includes: A: A spiral concentrator was used to rough the -0.074mm fine-grained raw ore to obtain titanium-zirconium rough concentrate 21, titanium-zirconium middlings 21, and titanium-zirconium tailings 21. B: The titanium-zirconium middlings 21 obtained from the roughing process in step A are then further separated in the middlings re-selection process to obtain titanium-zirconium rough concentrate 22 and titanium-zirconium tailings 22. C: The titanium-zirconium rough concentrate 21 obtained from the roughing process in step A and the titanium-zirconium rough concentrate 22 obtained from the middlings process in step B are combined together to obtain a rough concentrate that enters the fine treatment process and is finely treated using a spiral concentrator to obtain titanium-zirconium rough concentrate 2, titanium-zirconium middlings 2, and fine tailings 23. Among them, the fine tailings 23, the titanium-zirconium tailings 21 obtained from the roughing process in step A, and the titanium-zirconium tailings 22 obtained from the middlings process in step B are combined together to form tailings 4.

5. The method according to claim 1 or 2, characterized in that, The most concentrated natural grain size range of the coastal sand ore is +0.074 mm. The titanium and zirconium minerals have consistent grain sizes, mainly distributed in the 0.043~0.3 mm range.

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