Continuous Bentonite Dosing Systems for Bleaching Processes

The bleaching process, in the refining of vegetable oils — sunflower oil in particular, as well as olive oil and other vegetable oils — is a critical stage that directly determines product quality. The purpose of this process is to obtain a clearer, more stable, and higher-quality oil by removing color-imparting pigments, oxidation byproducts, and unwanted impurities from the oil. The most important raw material used in this process is bentonite, also known as "bleaching earth.".

| VOLDE's Continuous Dosing Solution Custom for the Bleaching Process

VOLDE designs and implements turnkey systems that ensure the bentonite powder used in liquid oil refining facilities is fed into the bleaching tanks continuously and proportionally. Bentonite arriving in big bags is brought into the process safely and dust-free via the FREEBAG Big Bag Discharge System. Other auxiliary raw materials arriving in bags are incorporated into the system via bag dumping bins. VACUMATE cyclone systems, positioned above the bleaching tanks, convey the bentonite powder upward by vacuum. The gravimetric feeding units located beneath the cyclones continuously (continue) feed the bentonite into the bleaching tanks with high, weighing-based precision. Thanks to this structure, dosing is based on measurement and control, rather than on manual intervention, operator experience, or guesswork.

| Bentonite: The Powder That Shapes Oil Quality

Thanks to its high adsorption capacity, bentonite:

• Lightens the color of the oil
• Increases clarity
• Improves oxidative stability
• Raises the quality of the final product

However, this effect is only possible with dosing in the correct amount and at the correct time. Too much is a loss; too little is a quality problem. This is precisely where process continuity and control precision become decisive.

Thanks to VOLDE's proportional continuous-dosing architecture, the bleaching process becomes measurable, repeatable, and stable even under variable conditions.

| Process-Linked Proportional Control

Due to the refining process, the oil level in the bleaching tanks continuously fluctuates depending on feed rate, batch transitions, and process conditions. In systems operating with fixed dosing, these fluctuations directly cause quality deviations and raw material losses.

The proportional control structure developed by VOLDE is designed to eliminate this problem at its root.

The system reads the oil level and/or flow rate signals in the bleaching tanks in real time and uses this data as a reference for the gravimetric dosing units. This way, the bentonite feed operates not based on time, but directly based on the process itself. When the oil quantity increases, the dosage automatically rises; when the oil level drops, feeding is reduced with the same precision.

Thanks to this dynamic control:

• The bentonite/oil ratio is kept at the target value at all times
• No operator intervention is needed
• No dosing deviation occurs during batch transitions or process fluctuations
• Oil losses caused by excess bentonite use are prevented
• Color and clarity problems that could arise from insufficient dosing are eliminated