Method for separating micro-fine quartz and mica through selective flocculating settling

Abstract

The invention relates to the technical field of mineral separation, in particular to a method for separating micro-fine quartz and mica through selective flocculating settling. According to the technical scheme, the method comprises the following steps: providing a mixed mineral raw material of micro-fine particle quartz and mica, wherein the particle size of the mixed mineral raw material is less than 48 microns; according to the method, efficient separation of the micro-fine quartz and the mica is achieved through the selective flocculation effect of the anionic polyacrylamide under the natural pH condition, the method is simple in process and environmentally friendly, acid-base adjustment is not needed, and the operation complexity and the agent cost are remarkably reduced; the selective flocculation effect on mica is outstanding, two-phase separation can be rapidly achieved, and the problems that fine-particle minerals are low in separation efficiency and prone to entrainment in the traditional separation process are effectively solved; meanwhile, the method is high in adaptability and suitable for a micro-fine particle mineral system, and comprehensive recovery of mica is achieved while the purity of a quartz product is improved.

Description

Technical Field

[0001] This invention relates to the field of mineral separation technology, and in particular to a method for selective flocculation sedimentation to separate fine-grained quartz and mica. Background Technology

[0002] Quartz, due to its excellent thermal stability, chemical inertness, low coefficient of expansion, and high optical transmittance, has become an indispensable key raw material in high-end fields such as semiconductors, photovoltaics, fiber optic communications, precision instruments, and aerospace. Mica, as a common layered silicate mineral, is not only an important industrial mineral raw material but also serves as a carrier for valuable metals such as lithium, rubidium, and cesium, possessing high comprehensive recovery value. In granite-type deposits and their tailings, quartz and mica often coexist closely. Mica, as a major aluminum-containing impurity, significantly reduces the quality and value of quartz products. Therefore, efficient separation of fine-grained quartz and mica is of great significance for improving quartz purity and realizing the resource utilization of tailings.

[0003] Currently, industrial separation of quartz and mica primarily relies on flotation. Flotation is effective for separating minerals with particle sizes ranging from 45 to 150 micrometers, but its separation efficiency drops significantly for fine particles smaller than 45 micrometers. Fine particles have a large specific surface area and high surface energy, leading to increased hydrophilicity and decreased reagent adsorption selectivity. Simultaneously, their light weight makes them easily mechanically entrained into foam products by the water flow, causing concentrate contamination and reduced recovery rates. Furthermore, fine particles tend to coat the bubble surface, making the foam viscous and less stable, further deteriorating the separation environment. Therefore, conventional flotation techniques struggle to achieve efficient and clean separation of fine-grained quartz and mica.

[0004] To improve the separation effect of fine particles, various improved processes have emerged in existing technologies. For example, Chinese patent CN113877721B discloses a combined process of "grinding-magnetic separation-multi-stage flotation" to remove fine mica particles from tailings. However, this process is lengthy, has complex reagent formulations, and high energy consumption, making its industrial application costly and difficult to control. Another patent CN117983399A uses a multi-stage coupled process of "crushing-classification-scrubbing-gravity separation-magnetic separation-ultrasonic flotation" to purify quartz. Although ultrasonic enhancement is introduced, the overall process is complex, and the improvement in quartz yield is limited, posing challenges to its economic viability and adaptability.

[0005] Selective flocculation is an effective method for separating fine-particle minerals. Its principle involves the selective adsorption of polymeric flocculants on the mineral surface, bridging to form flocs, thereby achieving rapid sedimentation and separation of the target mineral. This technology typically possesses advantages such as simple process, adaptability to fine particles, and no need for extreme pH adjustments. However, in the quartz-mica system, conventional flocculants often lack sufficient selectivity, easily leading to co-flocculation of both, resulting in unsatisfactory separation. Furthermore, many selective flocculation methods still rely on pH adjustment or the addition of dispersants to enhance selectivity, increasing process complexity and reagent costs.

[0006] Therefore, this application proposes a method for selective flocculation sedimentation to separate fine quartz and mica particles. Summary of the Invention

[0007] The purpose of this invention is to address the issue that in the background art, conventional flocculants in the quartz-mica system often lack sufficient selectivity, which easily leads to co-flocculation of the two and unsatisfactory separation effect. This invention proposes a method for selective flocculation sedimentation to separate fine quartz and mica particles.

[0008] The technical solution of the present invention: A method for selectively flocculating and sedimenting to separate fine-grained quartz and mica, comprising the following steps:

[0009] S1. Provide a mixed mineral raw material of fine-grained quartz and mica, wherein the particle size of the mixed mineral raw material is less than 48 micrometers;

[0010] S2. The mixed mineral raw materials are mixed with water to form a mineral slurry;

[0011] S3. Add anionic polyacrylamide (APAM) solution to the slurry for selective flocculation treatment. The anionicity of the anionic polyacrylamide is not less than 40%, and the concentration is not less than 50 mg / L. The pH value of the slurry during the treatment process is the natural pH value, and no external acid or alkali adjustment is required.

[0012] S4. The slurry treated in step S3 is subjected to sedimentation separation for 1 to 5 minutes to obtain suspended solids with quartz as the main component and precipitates with flocculated mica as the main component.

[0013] S5. The suspended matter and precipitate are subjected to solid-liquid separation and drying treatment respectively to obtain quartz concentrate and mica concentrate.

[0014] Optionally, in step S3, the concentration of the anionic polyacrylamide is 50~250 mg / L.

[0015] Optionally, in step S3, the selective flocculation treatment includes a stirring operation, with a stirring time of 3 to 30 minutes and a stirring speed of 200 to 400 r / min.

[0016] Optionally, the stirring time is 2 to 4 minutes and the stirring speed is 280 to 320 r / min.

[0017] Optionally, in step S3, the natural pH value is 6.0 to 8.0.

[0018] Optionally, the natural pH value is 6.5 ± 0.5.

[0019] Optionally, in step S2, the concentration of the slurry is 1% to 10 wt.%.

[0020] Optionally, in step S4, the sedimentation separation is carried out in a sedimentation tube, and the sedimentation time is 45-75 seconds.

[0021] Optionally, in step S5, the solid-liquid separation is performed by filtration or pressure filtration.

[0022] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0023] The method of this invention operates under natural pH conditions, requires no acid-base adjusters, has a short process, is easy to control, and uses low amounts of anionic polyacrylamide (APAM), thus reducing reagent costs and mitigating environmental burden.

[0024] Anionic polyacrylamide exhibits highly selective flocculation of fine mica particles at natural pH, with high mica sedimentation recovery rate while quartz remains dispersed. The difference in recovery rates between the two is large, and rapid separation can be achieved within 1-5 minutes.

[0025] This invention can effectively process quartz-mica mixed minerals with a particle size of less than 48 micrometers, solving the technical problems of low separation efficiency and severe entrainment in traditional flotation within the fine particle range.

[0026] The SiO2 content in quartz concentrate can be greatly increased through a single separation process, and mica concentrate that can be utilized for resource recovery can be obtained simultaneously, realizing the high-value comprehensive utilization of tailings or low-grade raw materials.

[0027] It maintains stable separation performance over a wide range of APAM concentrations, stirring times, and settling times, demonstrating high process reliability and ease of industrial application and promotion.

[0028] This invention achieves efficient separation of fine-grained quartz and mica through the selective flocculation of anionic polyacrylamide under natural pH conditions. The method is simple, environmentally friendly, and requires no acid-base adjustment, significantly reducing operational complexity and reagent costs. Its selective flocculation effect on mica is outstanding, enabling rapid two-phase separation and effectively solving the problems of low separation efficiency and easy entrainment in traditional fine-particle mineral sorting processes. Furthermore, this method is highly adaptable and suitable for fine-particle mineral systems, achieving comprehensive mica recovery while improving the purity of quartz products. Attached Figure Description

[0029] Figure 1 This is a flowchart of a method for selective flocculation sedimentation to separate fine quartz and mica particles. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0031] Example 1

[0032] like Figure 1 3.33g of quartz powder (with a particle size of less than 48 micrometers after crushing and sieving, i.e., all passing through a 300-mesh standard sieve) and 1.67g of mica powder were mixed evenly to simulate fine-particle mixed mineral raw materials. The mixed minerals were added to a 250mL beaker, along with 50mL of anionic polyacrylamide (APAM) aqueous solution with an anionic degree of 40% and a concentration of 100mg / L. The beaker was placed on a stirrer and stirred at 300r / min for 3 minutes to ensure that the APAM was evenly dispersed in the slurry and fully contacted with the mineral particles.

[0033] The flocculated slurry was transferred to a settling tube equipped with a drain valve, which was pre-filled with 450 mL of an APAM aqueous solution with a concentration of 100 mg / L. The entire system was allowed to stand at room temperature without any pH adjustment, maintaining its natural pH value (approximately 6.5). After settling for 1 minute, stratification was clearly observed: a dense mica flocculated sediment layer formed at the bottom, while the upper liquid remained turbid and suspended, mainly consisting of dispersed quartz particles.

[0034] First, open the valve at the top of the settling tube to carefully discharge and collect the upper suspension; this portion is the rough quartz concentrate. Then, collect the precipitate at the bottom of the settling tube; this portion is the rough mica concentrate. The collected quartz suspension and mica precipitate are then vacuum filtered to separate the solids. The filter cake is placed in an oven and dried at 105°C to constant weight, yielding dried quartz concentrate powder and mica concentrate powder, respectively.

[0035] The separated quartz concentrate powder was subjected to multi-element chemical analysis, and the results are shown in Table 1.

[0036] Table 1. Chemical composition analysis results (wt.%) of quartz-mica mixture and suspended quartz concentrate.

[0037]

[0038] Compared with the original mixed sample, the SiO2 content in the quartz concentrate increased significantly from 76.54 wt.% to 93.22 wt.%, while the contents of characteristic components representing mica, such as Al2O3 and K2O, decreased significantly, proving that the quartz was effectively purified. The overall recovery rate of quartz in this process was 63.3%.

[0039] Comparative Example 1

[0040] To verify the selective flocculation effect of APAM, a blank control experiment was conducted. Except for the absence of any flocculant (i.e., using only deionized water), all other conditions were identical to those in Example 1. A mixture of quartz and mica minerals was stirred in pure water and allowed to settle for the same amount of time. The supernatant was then collected and its composition analyzed. The results are shown in Table 2.

[0041] Table 2. Chemical composition analysis results (wt.%) of quartz-mica mixture and mixed mineral suspension samples settled in pure water.

[0042]

[0043] The SiO2 content in the suspension was 74.35 wt.%, which was not enriched but was slightly lower than that in the original ore mixture. This indicates that without the presence of selective flocculants, natural sedimentation alone cannot achieve effective separation of quartz and mica, and there is no purification effect.

[0044] Example 2

[0045] To illustrate the selectivity differences of APAM for different minerals, single-mineral sedimentation experiments were conducted. Equal masses of pure quartz powder and pure mica powder (particle size less than 48 micrometers) were weighed and placed in separate beakers. 100 mg / L APAM solution with an anionicity of 40% was added to each beaker. Under the same conditions, the mixtures were stirred and transferred to sedimentation tubes, where they were allowed to stand for 1 minute. The residual solid content in the upper suspension was measured, and the sedimentation recovery rates of quartz and mica were calculated. The results are shown in Table 3.

[0046] Table 3. Differences in sedimentation recovery rates of quartz and mica under different concentrations of APAM for single minerals.

[0047]

[0048] Within the APAM concentration range of 50–250 mg / L, the sedimentation recovery rate of mica remained above 95.8%, while the sedimentation recovery rate of quartz was below 18.4%, with a difference (Δ) of over 78.2%. This fully demonstrates APAM's excellent selective flocculation ability on mica particles, while having virtually no flocculation effect on quartz.

[0049] Example 3

[0050] To demonstrate the feasibility and advantages of natural pH conditions, the effect of different initial pH values ​​on the separation effect was investigated. The pulp pH was adjusted to 2, 4, 6, 8, 10, and 12 using hydrochloric acid or sodium hydroxide solution, respectively, and compared with the natural pH condition (≈6.5). At each pH, ​​a 100 mg / L APAM solution with an anion concentration of 40% was used, and single-mineral sedimentation experiments were conducted according to the steps in Example 1. The results are shown in Table 4.

[0051] Table 4 shows the difference in sedimentation recovery rates of quartz and mica by APAM under different pH conditions for single minerals.

[0052]

[0053] Data shows that under strong acid (pH=2) or strong alkaline (pH≥10) conditions, the selectivity of APAM decreases, and the difference in sedimentation recovery rates between quartz and mica narrows. However, at pH 4 to 8, especially near the natural pH (approximately 6.5), APAM exhibits the strongest selectivity for mica, resulting in the best separation effect. This demonstrates that the present invention does not require additional acid or alkaline adjustments to specific values, achieving optimal or near-optimal separation results at the natural pH of the slurry, thus simplifying the process.

[0054] It is worth noting that this invention provides a selective flocculation sedimentation method for achieving efficient separation of fine-grained quartz and mica under natural pH conditions. This method overcomes the limitations of traditional flotation processes in the separation of fine-particle minerals. By employing anionic polyacrylamide (APAM) as a flocculant, it utilizes the hydrogen bonds and electrostatic adsorption between APAM and the mica surface to achieve selective flocculation of mica particles without affecting the dispersion of quartz. No acid-base adjusters are required during the process; the optimal selectivity is achieved solely by the natural pH of the slurry (approximately 6.5), simplifying the reagent formulation and process control. This method is designed for mineral systems with particle sizes less than 48 micrometers. By optimizing operating parameters such as APAM concentration, stirring intensity and time, and settling time, flocculation and separation are completed in a short time, significantly improving the separation efficiency and purity of fine-grained minerals. Furthermore, this process can directly process low-grade raw materials such as tailings, achieving comprehensive recovery of mica while obtaining high-purity quartz, demonstrating good industrial applicability and resource utilization benefits.

[0055] Furthermore, the core principle of this invention lies in utilizing the significant differences in the adsorption behavior of anionic polyacrylamide (APAM) polymer chains on mica and quartz surfaces under specific conditions. In a natural pH environment, the mica surface carries a significant permanent negative charge due to lattice substitution, but its edges or dissociation surfaces may exhibit localized positive charge or hydroxylation under near-neutral conditions. This provides specific adsorption sites for the negatively charged carboxyl groups in APAM through electrostatic attraction and hydrogen bonding. Conversely, the quartz surface is generally negatively charged within this pH range, exhibiting electrostatic repulsion with APAM segments, thus inhibiting adsorption. When APAM selectively adsorbs onto mica particles, its long molecular chains connect multiple particles through a "bridging" mechanism, forming large-sized and dense flocs, significantly accelerating their settling velocity in a gravitational field. Unadsorbed quartz particles, remaining dispersed, are retained in the suspended phase during solid-liquid separation. This adsorption selectivity based on surface property differences and the subsequent particle-floc transformation constitute the physicochemical basis for achieving efficient separation of the two. This method avoids the surface hydrophobication and bubble mineralization processes that flotation relies on, thus fundamentally eliminating problems such as severe entrainment and low separation efficiency caused by the light weight and high surface energy of fine particles. At the same time, it simplifies the process and reduces the introduction of chemical reagents because it does not require pH adjustment. Under simple operating conditions, it can directly obtain high-purity quartz products from the micro-fine particle mixture system.

[0056] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A method for the selective flocculation and sedimentation separation of fine particulate quartz from mica, characterized in that, The method comprises the following steps: S1, providing a mixed mineral raw material of fine quartz and mica, wherein the particle size of the mixed mineral raw material is less than 48 microns; S2, preparing a slurry by mixing the mixed mineral raw material with water; S3, adding an anionic polyacrylamide solution to the slurry for selective flocculation treatment, wherein the pH value of the slurry during the treatment is the natural pH value, and no additional acid or alkali is required for adjustment; S4, performing sedimentation separation on the slurry treated in step S3, wherein the sedimentation time is 1-5 minutes, and the separation obtains a suspension mainly composed of quartz and a precipitate mainly composed of flocculated and settled mica; S5, performing solid-liquid separation and drying treatment on the suspension and the precipitate respectively to obtain quartz concentrate and mica concentrate.

2. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1 characterised in that, In step S3, the anionic degree of the anionic polyacrylamide is not less than 40%, and the concentration is 50-250 mg / L.

3. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterised in that, In step S3, the selective flocculation treatment comprises stirring operation, the stirring time is 3-30 minutes, and the stirring speed is 200-400 r / min.

4. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterised in that, The stirring time is 2-4 minutes, and the stirring speed is 280-320 r / min.

5. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterised in that, In step S3, the natural pH value is 6.0-8.

0.

6. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterized in that, The natural pH value is 6.5±0.

5.

7. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterised in that, In step S2, the concentration of the slurry is 1%-10 wt.%.

8. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterized in that, In step S4, the sedimentation separation is performed in a sedimentation tube, and the sedimentation time is 45-75 seconds.

9. A process for the selective flocculation and sedimentation separation of fine particulate quartz from mica according to claim 1, characterised in that, In step S5, the solid-liquid separation is performed by filtration or pressure filtration.

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