Appropriate Voltage for High-Voltage Electrostatic Separators

High-voltage electrostatic separators are essential equipment in various industries, such as recycling, mining, and plastics processing. They work based on the principle of using high-voltage electricity to separate conductor materials from non – conductor materials according to their different electrical conductivities. However, choosing the appropriate voltage is crucial for achieving efficient and effective separation. This article will explore the factors influencing the selection of voltage and the suitable voltage ranges for different applications.

Factors Affecting Voltage Selection

Material Properties

The electrical conductivity of materials is a key factor. Conductive materials, such as metals, can easily transfer charges, while non – conductive materials, like plastics and some minerals, have poor charge – transfer abilities. For materials with high conductivity, a relatively lower voltage may be sufficient to achieve separation. In contrast, non – conductive materials may require a higher voltage to ensure that they can be charged and separated effectively. For example, when separating copper and plastic mixtures, the copper, being a good conductor, can be separated at a lower voltage compared to the plastic.

Particle Size

The size of the particles to be separated also affects the voltage selection. Smaller particles generally require a higher voltage to be charged and separated. This is because smaller particles have a larger surface – to – volume ratio, and more energy is needed to overcome the surface forces and charge them. For instance, in the separation of fine mineral powders, a higher voltage is often necessary compared to the separation of larger mineral particles.

Separation Efficiency Requirements

If a high separation efficiency is required, a more precise voltage adjustment is needed. In some cases, a slightly higher voltage may increase the separation rate, but it also needs to be balanced with other factors such as safety and energy consumption. For example, in the recycling of e – waste circuit boards, where high – purity metal recovery is crucial, the voltage needs to be optimized to achieve the best separation efficiency.

Suitable Voltage Ranges for Different Applications

Recycling Industry

Metal and Plastic Separation

In the recycling of waste cable wires and aluminum – plastic separation, high – voltage electrostatic separators are commonly used. For machines like the KLAY kle – 1000 series, the voltage range is 0 – 60 kV for the kle – 1000 model, 0 – 80 kV for the kle – 1500 and kle – 1800 models, and 0 – 90 kV for the kle – 1000 – 2 and kle – 1500 – 2 models. These voltage ranges are designed to separate metals and plastics effectively according to their different conductivities. The separation rate can reach up to 99% or even 99.9% in some cases, ensuring high – quality recycling.

Electronic Waste Recycling

When recycling e – waste circuit boards, the voltage requirements may vary depending on the composition of the board. Some studies have shown that a voltage range of 27 – 29 kV can achieve high – efficiency separation due to the quadratic effect. At this voltage range, conductive components such as copper traces and non – conductive components like fiberglass can be well – separated.

Mining Industry

Mineral Separation

In the mining industry, electrostatic separators are used to separate different minerals. For example, in the separation of scheelite and cassiterite, or tantalum – niobium ore and garnet, tourmaline, etc. Different types of electrostatic separators have different voltage requirements. The arc – type electrostatic separator and the drum – type electrostatic separator are commonly used. The drum – type electric separator usually has a suitable granularity of the selected materials of 0.1 – 1 mm, and the voltage can be adjusted within a certain range. Some laboratory electrostatic separators have a high – voltage step – less adjustable range of 0 – 60,000 V. This allows operators to adjust the voltage according to the specific mineral properties and separation requirements.

Powder Coating Industry

In powder coating operations, electrostatic powder coating systems often operate at high voltages to achieve the best adhesion between the powder particles and the substrate. The voltage levels typically range from 30 to 100 kV. However, to ensure the safety of operators, the voltage should ideally be limited to below 9 kV to reduce the likelihood of static – related discomfort or sensitivity issues. Although 9 kV is sufficient for efficient powder application, lower voltage settings can create a safer work environment, especially for sensitive individuals.

Safety Considerations

Using high – voltage electrostatic separators always involves safety risks. Most electric separators use high – voltage DC power sources, and the voltage is mostly in the range of 30 – 60 kV, with a few up to 100 kV. Therefore, strict safety measures must be taken. In equipment design, over – current relays should be used to prevent damage to the high – voltage transformer. The DC output must use cables with a high safety factor. The hood should be designed with a locking device so that when the door is opened, the high – voltage power supply is cut off, and the electrode is automatically grounded. Additionally, the separator must be equipped with a special ground wire with a resistance of less than 2 – 4 ohms.

Conclusion

Selecting the appropriate voltage for high – voltage electrostatic separators is a complex task that requires considering multiple factors such as material properties, particle size, and separation efficiency requirements. Different applications, including recycling, mining, and powder coating, have different suitable voltage ranges. By understanding these factors and voltage ranges, operators can optimize the performance of the electrostatic separators, improve separation efficiency, and ensure safety in the operation process.