With latest oil-mill technlogy we process up to 1.000.000 tons of rapeseed.
Steps of processing
1. Seed Processing and Pressing
In the next step, the seed is purified. Iron and non-ferrous metals are separated in an all-metal separator. After this the so-called stock is sieved out.
After coarse and fine purification, the seed is crushed using roller mills and then heated and dried in a conditioner. This heating reduces the viscosity of the oil, makes the pressing procedure easier and suppresses enzyme-driven reactions in the seed that are detrimental to the product quality.
Then the oil is pressed out of the crushed pieces of seed in the presses. The so-called press oil is clarified of clouding materials and pumped into an intermediate storage unit.
After pressing the oil retained in the press cakes it will be separated in the extraction with the aid of a solvent. Hexane or a mixture of hexane and oil called Miscella runs through the extractor for this purpose and releases the oil from the solid material. Extraction waste soaked with hexane and the oil accumulate in the Miscella.
Hexane is completely recovered from the Miscella in the multi-stage distillation process and fed back to the process. The extraction oil gained in this process is pumped into the intermediate storage unit as press oil.
2.2 Benzene Removal
The solvent is removed from the rapeseed meal in a so-called toaster by means of water vapour in an energy-efficient method. Near the end of the process there is a targeted hydrothermal treatment of the meal in order to improve the digestibility and largely destroy any substances that hinder digestion and harmful substances. After it cools down the meal that is ready for shipping is stored.
3. Oil Purification
During the oil-purification any undesirable undesirable odorants, flavourings and dyes are removed from the pressed and extracted rapeseed oil in several gentle production.
The combined pressed and extracted oil will then be de-gummed and depending on the specification also de-acidified. During the de-gumming the phosphatides in the oil will be hydratised.
In this step, a defined quantity of phosphoric acid is added. Phosphoric acid and free fatty acids are saponified with sodium hydroxide. Then the separators constantly separate the gums and soaps.
Traces of residual soaps and gums will be washed out with water, centrifuged out in a second step of separation and the oil is then dried.
Either raw rapeseed oil conforming to the FEDIOL-Specification or rapeseed oil-fuel compliant with DIN V 51605 can be manufactured. The rapeseed oil conforming with FEDIOL is processed and refined in bio-diesel plants.
4. Extraction of Food-grade Oil / Refining
Extraction of cooking oil also follows this. With a capacity of 200,000 t annually, the de-acidified and de-gummed rapeseed oil can be converted to refined rapeseed oil.
In this process the oil is constantly dosed with a precisely specified quantity of bleaching earth. The mixture is held for a specific time at < 100 °C under a vacuum in an agitator vessel.
The bleaching earth adsorbs along with the dye pigments oxidising metal ions, complex compounds, residual soaps and similar materials. Small amounts of citric acid support the process.
After the reaction time, the bleaching earth is separated by filtration. The dried bleaching earth will be fed with the press cake into the extractor. This makes it possible to reclaim the oil residues.
The bleached oil will then be de-odourised. The de-odorising process removes from the oil the unwanted remaining by-products from the oil that were produced in the steps of the refining process. This step is determinative for quality with respect to the odour and taste as well as the shelf-life product.
To this end the by-products such as the free fatty acids are separated by distillation at high temperatures and high vacuum with the help of water vapours as an entrainer.
In the refined product storage unit the oil is then ready to be loaded after sampling.
The materials distilled out and the fatty acids will be fed to technical uses.