Mechanical classifier

Types of Mechanical Classifiers

A mechanical classifier is a key feature of many mining processing systems. The mechanical classifier divides a slurry into cleaned ore and tailings based on particle size. There are many mechanical classifiers, including spiral classifiers, vibrating screens, shaking tables, jigs, pans, hydrocyclones, and air classifiers.

• Spiral Classifier

  A spiral classifier is the most common device. It uses an Archimedes' screw to lift the fine material from the slurry. The screw's pitch determines the classifier's specific operation, such as the quantity and percentage of fine material lifted. It may be a combination of specific operations.

• Vibrating Screens

  Vibrating screens have a simple structure. They classify materials by size and separate them using vibration and mesh. The ground ore is sifted through mesh with fixed openings to let smaller particles fall through and over-sized particles move forward to the next processing stage.

• Shaking Tables

  Shaking tables sort particles based on their density by tilting the table in a controlled way while water flows across it to carry lighter materials away from heavier ones. They normally classify materials after hydrocyclones.

• Jigging Machines

  A jig mechanically sorts materials based on their density using pulsating currents of water. The jig has a permeable bed where water moves upwards carrying light particles while heavy ones remain on the bed. Jigs are suitable for ore with a high specific gravity.

• Concentrating Pans

  A pan has a fixed bed with water flowing upwards. Gravity and water flow carry lighter materials across while heavier materials remain on the bed. Concentrating pans are suitable for coarse ore.

• Hydrocyclones

  Also known as classifiers or separators, hydrocyclones are tubular devices with a conical bottom section. They classify materials depending on the centrifugal force generated when slurries enter at high pressure. Water, air, and other liquids commonly enter hydrocyclones.

• Air Classifiers

  An air classifier uses air to separate fine materials from coarser ones. It may be an upward, horizontal, or downward-flow classifier. Material enters the classifier and is subjected to air that separates fine material that goes to the collection system from over-sized material that goes back for further processing. Classifiers that separate by size are different from classifiers that separate by density.

Specifications and Maintenance of Mechanical Classifiers

Specifications

• Model Variants:

  The mechanical classifier comes as several models. As a result, users may find classifying machines with different capacities and sizes. They can settle for models that will suit their mineral processing demands.

• Materials:

  Classifiers are manufactured using a range of materials such as wear-resistant alloys, steel, and polymer composites. The material used during the construction of a classifier will affect its durability, maintenance, and overall performance.

• Working Environment:

  The working environment where the classifier will operate must be free from extreme temperatures and corrosive elements. When exposed to such conditions, the classifier's performance will decrease, and this will lead to premature failure.

• Power Requirements:

  Mechanical classifiers have different power requirements depending on the model. Sufficient power must be supplied to allow the classifier to operate smoothly and efficiently.

• Feeding Method:

  Depending on the type of classifier, the feeding method may vary. For example, mechanical classifiers with spiral or trough feeding should be uniform feeding and be diluted with water.

Maintenance tips

Administering proper maintenance to a mechanical classifier can prolong its lifespan and enhance performance. Here are a few maintenance tips that users should consider:

• Regular Inspection:

  Users should frequently check the classifier for signs of wear, damage, and leaks. Deviations from normal operational conditions should be promptly detected and corrected to prevent further issues and serious damages.

• Tightness of Fasteners:

  Users should establish maintenance schedules to check and ensure fasteners are tightly secured. They should replace missing or damaged fasteners. This will help to stabilize the mechanical classifier and subsequently reduce the risks of breakdowns and accidents.

• Lubrication:

  Users should regularly lubricate the moving parts of the classifier. This helps reduce friction and wear. It also helps to enhance the lifespan of the classifier and boost efficiency.

Scenarios of mechanical classifiers

• Mining and minerals industry:

  Mechanical classifiers are widely used in the mining and mineral processing sectors. They classify particles according to size after grinding ore with mechanical classifiers like spiral classifiers, static screens, and vibrating screens. The over-sized material can be returned to the grinding circuit for further reduction, while the correctly-sized material can be sent for further processing or recovery.

• Sand and gravel processing:

  In sand and gravel processing plants, mechanical classifiers separate sand, gravel, and other undesirable materials. For example, vibrating screens can efficiently separate fine sand and gravel aggregates that can be used in concrete and asphalt production.

• Food processing:

  In food processing, mechanical classifiers like vibratory sieves can separate flour, sugar, and spices as well as undesirable materials like foreign objects, metal fragments, and insect fragments. By-class products can be returned to the processing line for further refinement, while only the target material will be packaged for sale.

• Chemical and pharmaceutical industries:

  In chemical production and pharmaceutical companies, mechanical classifiers such as air classifiers or ball mills are commonly used to ensure fine chemicals and drugs are properly sized. They improve product quality and make it easier to dissolve and take. Mechanical classifiers also help to reduce fine chemicals and drugs that are inhaled into the air, which prevents pollution.

• Recycling and waste management:

  Mechanical classifiers are critical in recycling and waste management. They remove organic material such as plastic, paper, and metal cans and classify material according to size and weight. This enables waste management companies and recycling facilities to produce high-quality recycled materials and reduces the amount of waste sent to landfill.

How to Choose Mechanical Classifiers

The following key factors must be considered when choosing mechanical classifiers for sale for various purposes.

• Production Demand

  Given the different limits of classifiers and how they work, please check the classifier's construction capacity to ensure it can fulfill the required capacity. Pay attention to the feeding capacity each classifier has and the quantity of classifiers that are going to be used to meet the required production demand.

• Material Characteristics

  Study the features of the materials to be classified, including their sizes, density, moisture content, and corrosiveness. Different classifiers are suitable for classifying different kinds of materials. For example, wet mechanical classifiers can be used to classify ore slurry with a high concentration and fine particles; air classifiers are suitable for light, fine, and dry materials.

• Installation Requirement

  Installation requirements are also important factors to consider. Pay attention to the space needed for the classifier and the connections and fittings needed, as well as the power supply and control system. Make sure the space and installation conditions are sufficient for the classifier to be installed smoothly.

• Operating Cost

  Besides the purchase cost, the operating cost of the classifier should also be considered. This includes energy consumption, maintenance costs, and wearing parts' replacement costs. An optimal balance between operating costs and performance will be achieved by selecting a classifier with high energy efficiency and low maintenance requirements.

Mechanical classifier FAQ

Q1: What is the difference between a mechanical classifier and hydraulic classifiers?

A1: Mechanical classifiers utilize moving parts to separate materials based on particle size. On the other hand, hydraulic classifiers rely on water currents and density differences to separate materials.

Q2: What are mechanical classifiers used for?

A2: Mechanical classifiers are used to segregate finely ground material into different sizes for specific downstream processes, remove unwanted or excessive material from a product stream, and improve the efficiency of milling operations.

Q3: Do mechanical classifiers have any advantages?

A3: The advantages of mechanical classifiers are varied separation and flexibility, improved milling efficiency, water-saving, integrated desliming, reduced environmental impact, low maintenance requirements, and cost-effective operations.

Q4: How efficient are mechanical classifiers?

A4: The separation efficiency of mechanical classifiers can vary, but they typically recover 60% to 90% of the usable material.