Question

What are the various steps involved in the production of oil by solvent extraction

Answer 1

Extraction is the first step in the refining process. Oils and fats are extracted from their original source (the seeds, fruits or other oil-bearing raw materials) using a variety of different methods. In some cases, for example virgin olive oil, the oil is extracted directly from the fruit by means of a simple mechanical press and used without the need for any further processing. This process is known as cold pressing. For most oils however, the process is more complex. Modern oil mills extract oil using a combination of pressing, cooking and solvent extraction. This process is often carried out in the country of origin The seed bean is cleaned and dried and foreign material is removed.  Crushing used to be done between mill stones that later became steel rolls.  Seeds with a high oil content like rapeseed and sunflower seed are usually mechanically pressed in expellers after a preheating step in indirectly heated conditioners.  The oil bearing material is fed into one end of a cylinder where a power-driven worm conveyor forces the material to the other end of the cylinder and out against resistance.  The pressure exerted in the process squeezes out the oil.Solvent extraction is used to separate oil from seeds/beans.  The pre-processed seeds/beans are treated in a multistage counter current process with solvent until the remaining oil content is reduced to the lowest possible level.  The mixture of oil and solvent is separated by distillation and the solvent is recycled into the extraction process and the crude oil is stored ready for refining.