1. What is a Small-Diameter Hydrocyclone? Core Principle and Suitability for Non-Metallic Mineral Processing

A small-diameter Hydrocyclone is a hydraulic classification device that operates based on the principle of centrifugal sedimentation. While its structure is identical to that of a conventional large-diameter hydrocyclone (inner diameter ≥ 200mm) (consisting of a feed inlet, cylindrical section, conical section, overflow pipe, and underflow outlet), its smaller inner diameter allows for a stronger centrifugal field, making it more suitable for processing fine-grained non-metallic minerals (0.01-0.5mm). Its core suitability is reflected in the following two aspects:

1. Working Principle: Strong centrifugal force achieves precise separation of fine particles.

When a slurry (a solid-liquid mixture) containing fine-grained minerals is forced into the cylindrical section of the hydrocyclone at a certain pressure from the feed inlet, a high-speed rotating vortex is formed within the cylinder.

Centrifugal Force: Larger, denser mineral particles (such as coarse impurities in quartz sand) are subjected to the strong centrifugal force and are thrown toward the cylinder wall. They flow downward along the conical section and are discharged through the underflow outlet (becoming the vortex). "Underflow" refers to the coarse-grained product.

Centriptal force: Target mineral particles with smaller particle size and lower density (such as high-purity quartz fine powder and high-quality kaolin) experience less centrifugal force and follow the upward flow at the center of the vortex, discharging from the overflow pipe (becoming the "overflow" or qualified fine-grained product).

Due to the small radius of the small-diameter cyclone, the slurry rotates faster at the same feed pressure (the centrifugal acceleration can reach 50-200 times the acceleration of gravity). This allows for precise separation of near-critical size particles that are difficult to distinguish with conventional equipment (e.g., separating 0.05mm from 0.02mm quartz particles). The classification accuracy (separation efficiency) is 15%-25% higher than that of large-diameter cyclones. 2. Compatibility with Non-metallic Mineral Processing

The core requirements for fine-particle classification in non-metallic mineral processing are precision, low loss, and low pollution. Small-diameter cyclones precisely meet these requirements:

Suitable for fine-grained material characteristics: Most non-metallic minerals (such as kaolin and talc) have their high-quality components concentrated in the fine particle size (≤0.1mm). Small-diameter cyclones efficiently recover the target fine minerals, avoiding resource waste.

High classification accuracy improves product quality: For example, when purifying quartz sand, it is necessary to remove fine-grained clay impurities. Small-diameter cyclones can precisely separate clay particles smaller than 0.02mm, increasing the purity of quartz sand from 95% to over 99.5%.

Simple structure and zero secondary pollution: The main body of the equipment is made of wear-resistant ceramic or polyurethane (no metal parts come into contact with the slurry), preventing metal ion contamination of non-metallic minerals. This is particularly suitable for applications with high purity requirements, such as electronic-grade quartz and pharmaceutical talc.

Small footprint and adaptability to production line layout: A single small-diameter cyclone is only 1/3 the size of a conventional device. 1/5~1/3, multiple units can be installed in parallel, suitable for the "compact" production line design of non-metallic mineral processing plants.

II. Core Application Scenario: The Urgent Need for Fine Particle Processing in Non-metallic Mineral Processing

The application of small-diameter Hydrocyclones in non-metallic mineral processing primarily addresses three core requirements: fine particle classification, impurity removal, and concentration. Different processing scenarios for different minerals focus on specific areas:

1. Quartz Sand Processing: Purification and Particle Size Classification

Quartz sand is a key raw material for the photovoltaic, electronics, and glass industries. Fine particle classification is required to remove impurities such as clay and feldspar, and to control the particle size distribution of the finished product.

Impurity Removal Scenario: After crushing and grinding, the quartz sand ore slurry contains a large amount of 0.01-0.05mm clay fines. Using a small-diameter hydrocyclone with an inner diameter of 50-100mm removes the clay impurities from the overflow pipe, resulting in high-purity coarse quartz sand (SiO₂ content ≥ 99.8%) in the underflow.

Particle Size Classification Scenario: Production of quartz sand of varying specifications (e.g., 0.1-0.3mm sand for photovoltaic glass, 0.1-0.3mm sand for electronic-grade quartz powder, and 0.1-0.3mm sand for electronic-grade quartz powder). When using a 0.02-0.05mm powder, the overflow pipe diameter and feed pressure of the small-diameter cyclone can be adjusted to precisely control the classification particle size, ensuring a qualified particle size rate of over 98% for the finished product.

The manager of a quartz sand processing plant stated, "We previously used a vibrating screen to classify fine-grained quartz, but the pass rate was only 85%. After switching to six parallel 80mm internal diameter cyclones, the pass rate increased to 99%, clay impurity removal increased by 30%, and photovoltaic-grade quartz sand production increased by 15%."

2. Kaolin Processing: Classification, Purification, and Ash Reduction

Kaolin requires fine-grain classification to separate "coarse-grained quartz impurities" from "fine-grained kaolin concentrate," while also reducing the product ash content (increasing whiteness):

Coarse Particle Removal: After grinding, the kaolin slurry contains coarse quartz particles of 0.05-0.1mm. A small-diameter cyclone with an internal diameter of 100-125mm is used to remove the coarse impurities from the underflow, and the overflow produces fine-grained kaolin (particle size ≤ 0.04mm).

Ash Reduction and Purification: For low-grade kaolin, multiple small-diameter cyclones (2-3 in series) are used. The process gradually removes fine-grained impurities such as iron and titanium (the source of ash), increasing the kaolin's whiteness from 75% to over 88%, meeting the high-end demands of the papermaking and ceramics industries.

3. Graphite Processing: Fine-Grain Concentrate Recovery and Classification

The value of graphite increases with particle size refinement (for example, nanographite powder is much more expensive than coarse-grained graphite). Small-diameter cyclones enable efficient recovery and classification of fine-grained graphite:

Fine-Grain Recovery: After graphite flotation, 20%-30% of fine-grained graphite (≤0.02mm) remains in the coarse concentrate, lost in the tailings. Using a small-diameter cyclone with an inner diameter of 50-75mm can recover fine-grained graphite from the tailings, increasing the overall recovery rate by 5%-8%.

Particle Size Classification: When producing graphite products for different applications (e.g., 0.01-0.03mm graphite powder for lithium battery anodes and 0.05-0.1mm graphite powder for lubricants), adjusting the classification parameters using a small-diameter cyclone allows for precise control of the finished product particle size, avoiding either "too fine" (causing agglomeration) or "too coarse" (affecting performance). 4. Talc and Calcium Carbonate Processing: Fine-Grain Impurity Removal and Concentration

Non-metallic minerals such as talc and calcium carbonate require fine-grain classification to remove impurities (such as calcite in talc and quartz in calcium carbonate) and simultaneously concentrate the slurry to reduce subsequent drying costs.

Impurity Removal Scenario: Talc slurry contains calcite impurities of 0.03-0.08mm in diameter. A small-diameter cyclone with an inner diameter of 80-100mm is used to discharge the fine-grained talc through overflow (the calcite impurities are removed with the underflow), increasing the talc purity to over 98%.

Concentration Scenario: Calcium carbonate slurry after grinding typically has a concentration of 20%-30% (high water content). Using a small-diameter cyclone (with a narrow underflow outlet) can concentrate the slurry to 50%-60%, reducing energy consumption in the subsequent drying process and lowering production costs.