When recycling printed circuit boards (PCBs) and other e-waste, one of the biggest challenges is separating valuable metals from non-metallic materials. Metals like copper, gold, and silver are dense and heavy, while plastics, fiberglass, and resin are light. Wet process equipment solves this problem by using water as the separation medium, and at the heart of many wet separation systems lies a simple yet effective device: the shaking table.
Understanding how shaking tables work within wet process equipment helps operators get the most out of their recycling lines. Whether you run a small recycling facility or a large-scale e-waste processing plant, the principles remain the same.
How Shaking Tables Separate Metals in Wet Process Equipment
A shaking table is a flat deck with longitudinal riffles or grooves. In water process equipment, crushed PCB particles are mixed with water to form a slurry. This slurry is fed onto the upper corner of the shaking table. At the same time, clean wash water flows across the deck surface perpendicular to the riffles.
The table moves in a reciprocating motion—slowly forward and quickly backward. This asymmetric stroke creates three forces that act on the particles simultaneously: gravity pulls heavy particles downward, water flow carries lighter particles sideways, and the table vibration moves particles along the deck. Heavy metal particles sink to the bottom of the slurry, grip the riffles, and travel toward the concentrate end of the table. Lighter non-metallic particles stay suspended in the water film and wash over the riffles into the tailings side.
The result is a clean separation. At the far end of the table, you collect three distinct streams: a heavy metal-rich concentrate, a mixed middling fraction, and light tailings consisting mostly of plastic and fiberglass dust.
The Role of Water in Metal Separation
Water is not just a carrier in this process—it is an active separation agent. In wet process equipment, the density difference between metal and non-metal particles drives separation. Copper has a density of about 8.9 g/cm³, while typical PCB resin weighs around 1.3 g/cm³. When both are suspended in water, the heavy metal particles settle rapidly, and the light materials float or remain in suspension.
The shaking table amplifies this natural density difference through mechanical action. Without water, fine metal particles would cling to plastics due to static electricity, and dust would create an unhealthy working environment. Wet separation eliminates dust entirely and prevents fragile metal flakes from breaking apart during handling.
Key Operating Parameters
Getting good separation on a shaking table requires attention to several variables:
Feed particle size matters. Most wet process equipment works best with particles between 0.5mm and 5mm. If particles are too large, they cannot stratify properly in the thin water film. If they are too fine, wash water washes them away before separation occurs. A crusher and screening stage before the shaking table ensures the right size range.
Water flow rate must be steady. Too much water washes heavy metals into the tailings. Too little water causes the bed to pack up, and particles do not stratify. Operators adjust flow valves based on the feed rate and particle size.
Table tilt angle controls how fast material moves down the deck. A steeper angle speeds up the process but may reduce separation precision. A flatter angle gives better separation but lowers throughput. Most operators find the sweet spot through trial and observation.
Stroke length and frequency affect how aggressively the table shakes. Coarse material needs longer, slower strokes. Fine material needs shorter, faster strokes. Modern tables allow operators to adjust these settings without stopping the machine.
Where Shaking Tables Fit in PCB Recycling Lines
In a typical circuit board recycling equipment line, shaking tables appear after the crushing and grinding stages. The workflow looks like this:
First, raw PCBs go into a shredder or crusher that breaks them into small pieces. Then a screen removes oversized material for regrinding. The sized particles enter a mixing tank where water creates a slurry. A slurry pump feeds this mixture onto the shaking table.
After separation, the metal concentrate goes to a filter press or dewatering screen. The recovered metal—mostly copper powder with traces of gold, silver, and palladium—can be sold directly to smelters. The tailings, consisting of plastic and fiberglass, may go through additional processing or disposal. Water from the process circulates back to the mixing tank, making the system a closed loop.
San Lan Technologies offers several wet process equipment configurations that incorporate shaking tables for PCB recycling. Their water-based separation systems handle capacities from 500 kg/hour to 2000 kg/hour, depending on the model. These systems combine wet separation with air classification and electrostatic separation to maximize metal recovery.
Advantages of Wet Separation with Shaking Tables
Wet process equipment using shaking tables offers clear benefits over dry separation methods. First, water suppresses dust completely, creating a safer workplace and eliminating airborne particle hazards. Second, wet separation handles fine particles that dry air separators miss. Third, the process does not use chemicals, making it environmentally friendly. Fourth, water circulates in a closed loop, so consumption stays low.
Shaking tables themselves are mechanically simple. They have few moving parts, require little power, and run quietly. Maintenance mainly involves checking deck wear, adjusting water nozzles, and lubricating the drive mechanism. With proper care, a shaking table can operate for years with minimal downtime.
Common Issues and Solutions
Even well-designed wet process equipment runs into problems occasionally. Here are the most common ones:
Poor separation often traces back to feed size. If the crusher produces too many fines, they wash away with the tailings. If particles are too large, they disrupt the stratification layer. Checking and adjusting the crusher screen solves this.
Uneven water distribution across the deck causes some areas to separate well while others perform poorly. Cleaning clogged spray nozzles and leveling the deck fixes this issue.
Low metal recovery sometimes means the table tilt is too steep or the stroke is too aggressive. Reducing the tilt or shortening the stroke gives heavy particles more time to settle into the riffles.
Conclusion
Shaking tables remain one of the most reliable and cost-effective tools in wet process equipment for metal separation. Their ability to exploit density differences through a simple combination of water flow and mechanical vibration makes them ideal for PCB recycling and other e-waste applications. By controlling feed size, water flow, deck angle, and stroke settings, operators can achieve clean separation of valuable metals from waste materials without dust, chemicals, or complex machinery.
For facilities looking to upgrade their e-waste recycling capabilities, wet process equipment with shaking table separation offers a proven path to higher metal recovery and cleaner operations.
