Most confectionery manufacturers face the challenge of diverting and reworking products that are unfit to sell. To rework off-spec chocolate bars, one European producer separates the chocolate from nuts and other solid ingredients using heat and two model K30-30-SS Circular Vibratory Screeners from Kason.

Chocolate bars may be the wrong size or shape, cracked or broken, or improperly packaged. Each time, the production or packaging lines are re-started, the first bars off the line must also be reworked.

Off-spec chocolate bars are ground into pieces that are heated in a vessel to 50 °C, causing the chocolate to melt without burning, caramelization or crystallization. In two production lines, the blend of molten chocolate and solid particles is then fed through double wall piping into the centre inlet of one screener dedicated to dark chocolate, or the other dedicated to white chocolate.

Special gyratory motors impart multi-plane inertial vibration, which accelerates the rate at which molten chocolate passes through 1020 µm (17 mesh) apertures in the screen, and the rate at which solid particles travel across the screen and exit through a discharge spout at the screen’s periphery. Molten chocolate passes through the screen in less than one minute and cools by no more than 0.5 °C, preventing it from solidifying.

Vibration starts automatically when the pump feeds the screener, and runs for a preset time once the pump has stopped. Each screener can handle 150 kg/h. The screener’s clamshell device raises the upper frame using gas pistons, allowing full interior access for inspection, screen changes and daily cleaning with hot water.