Refining

The concept of refining ( refining or refining ) referred to in the general sense of a technical process for cleaning, finishing, separation and / or concentration of raw materials, food and technical products. In a refinery, you will find plants for the refining of sugar, petroleum, metals, or other substances.

Types of refining sorted according to material groups

Petroleum

Hydrocarbons contain undesirable sulfur-, oxygen-and nitrogen-containing substances, and other unwanted substances, for example by fractional alkenes (vacuum) distillation of petroleum. These impurities can already after short use lead to aging such as darkening, increase in viscosity, formation of acids or oil sludge in lubricants. They are used in the refining process in a petroleum refinery is removed by hydrogenation, thereby an improvement in quality is achieved. There are also applied alternative cleaning methods ( Furfurolextraktion, Oleumraffination ). Furthermore, the cleaning of the lubricant base oils in the production, wherein the base oils by means of different clays are filtered called refining.

During hydrogenation resulting from the sulfur-and nitrogen-containing contaminants such as hydrogen sulfide and ammonia gases to be separated.

Vegetable oils or fats

The refining of vegetable oils and fats is a processing step in the manufacture of products according to the principle of hot-pressing. In the refining unwanted accompanying substances from the previously produced crude oil ( trub oil ) removed ( eg pigments, odor, taste and bitter substances) that can have influence on the quality of the products. It is essentially about taste, durability, technical processing, odor and color. Refining is associated with a loss of useful vegetable oil from about four to eight percent.

Two processes of refining are alternatively used. First, this is the chemical refining, the processing steps:

• Degumming
• Neutralization ( deacidification )
• Bleaching ( decoloration )
• Deodorization (attenuation)

Second, the physical refining, the processing steps:

• Degumming → ​​→ discoloration, bleaching
• Damping → ​​→ deodorization distillation deacidification

Removed in the chemical refining the first gumming phospholipids, glycolipids, sugar -free, and metal ions from the oil. In the neutralization of free fatty acids, which are included with 0.3 to 0.6% in oil, separated, bleaching removes most of the dyes as well as remains of mucilage, soaps, trace metals and oxidation products. When damping steam distillation is carried out to remove the odor and flavor intensive accompanying substances.

The physical refining separates the fatty acids from by distillation, and therefore connects this treatment step with the attenuation. Previously, the oil must be completely degummed. The discoloration occurs either in connection or linked to the degumming. So far, mainly the chemical refining was widespread, with increasing environmental regulations, however, the physical refining is becoming increasingly important, since this less chemicals are needed, incurred lower refining losses and quantities of waste water and the separated fatty acids in this process together with the distillate from the deodorization for animal nutrition can be used. After refining are " fully refined vegetable oils " are available. Because of the high temperatures in the deodorization of the content of certain impurities, and the desired nutritional positive tocopherols is reduced in the oil.

In contrast to the method of hot pressing, in which the refining of crude oils ( Truböle ) is performed, this step is omitted in the cold pressing, which is mainly used in decentralized oil mills. In this process the crude oil ( trub oil ) is only filtered.

The by-product in the production of vegetable oil, after the hot -pressing method is called seed meal, refers to the by-product in the cold-pressing, however, as a presscake.

Sugar

In the refining of sugar, the raw sugar is removed by washing with syrup and centrifugation precleaned ( Refinement ) and the Affinade by dissolving in water, decolorizing with charcoal or diatomaceous earth and concentration further processed in a vacuum. The white sugar ( refined sugar ) is crystallized and recovered by centrifugation. Higher levels of purity may be achieved by (repeated ) sequence of the process steps dissolving, bleaching, filtration, crystallization and centrifugation. In the thus- obtained crystal sugar, the sugar refined, is chemically nearly pure sucrose ( 99.8 weight percent). Refined sugar or refined sugar is the proprietary name of a type of sugar.

Metals

The metallurgical practice distinguishes between fire refining and electrolytic refining. The fire refining unwanted items according to the degree of their affinity for oxygen converter process by either, or oxidizing melts away. This requires then oxidizing furnace operation, supplemented by oxidizing melt Supplements ( melt treatment agents ). For higher purity levels, use is made of electrolytic refining. The respective raw metal, such as copper converter, is the anode and is in solution, wherein the electrolyte is a salt solution of the metal in question is, as a pure metal and is deposited on the cathode from. In the electrolysis go unedelere accompanying elements in solution, however without cathodic deposit, noble companions fall as anode slime (see Electrochemical Series ). Significant amounts of silver and gold are recovered in particular at the copper refining from the anode mud. The electrolytic refining is used particularly for copper and nickel, but also silver, lead and zinc. Aluminum is with a related refining process, the fused-salt electrolysis, won and falls into the electrolytic cells, which are fed continuously with clay and a Kryolithgemisch as the electrolyte, as well as continuously as raw aluminum for taking on. A more recent method is the refining zone melting method, which is used for the production of pure silicon or silicon monocrystals.

Table salt

Refining of sea salt refers to the washing of the industrial harvesting usually contaminated " crude salt " in saturated brine, the re- crystallization, centrifugation, drying and the displacement after grinding with brighteners, pouring agents and artificial iodination. After this treatment, the sea salt is neither optically nor taste of - to distinguish rock salt - also refined. By Liquid derived Mining brine is processed with similar cleaning process to vacuum salt.