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Les ocres/essai

Cours gratuits > Forum > Forum anglais: Questions sur l'anglais || En bas

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Les ocres/essai
Message de djoe posté le 05-09-2013 à 14:09:13 (S | E | F)
Bonjour
Je dois expliquer comment on obtient de l'ocre en poudre. Donc j'aimerais que vous corrigiez mes erreurs, SVP s'il vous plaît. Le texte est un peu long !
Merci par avance.

Ocher spread over 25 km between Apt and Bédoin. Ochre is composed of 10% iron oxide which create intense colors. Ochre is used in the manufacture of dyes and colors in the soap, paper, for coloring concrete and coating in the building, roof tiles, floor tiles. They are found in cosmetics (powders and blushes), and even in food (cheese rind, skin sausages ...).

To obtain ocher we must respect several steps:
Extraction: we start by removing the layer of soil above that of ocher. Then the ocher layer is extracted manually before (pickaxe and shovel), today bulldozer. Ochre is then carry to the plant to be washed (before car, truck today).

Washing: until 1960, the elimination of sand was by levigation: A flow of water resulted in the ore in a "cofferdam" (used to mix the layer with water). The next step is to eliminate as much as possible of sand. Sand, heavier sank to the bottom and ocher remaining in suspension in the water was driven by the latter in the tanks (200 m3). The operation was renewed daily until the ponds were full.
Today, this type of washing has changed. The "cofferdam" are deleted. Ore / water mixture is sent to a separator. Mixture comes with high pressure under the action concentrated sand on the center of the cyclone falls almost dry, ocher and water comes out then is directed to settling ponds.

Decanting: The final phase of the wash of ocher is settling. The basins are filled with water and the heavier ocher deposits at the bottom. By a cap system (un système de bouchon vidangeur) water. One person took rest ocher in ponds by color reaching a thickness of about 50cm or about 60 tons per basin. The step is realized in winter. The drying period from May to September can begin. After that, the ocher will be transported to the plant for the completion of its manufacture.

Drying: Off May, ocher was dried under the action of the sun and mistral.

Grinding: when the dough had the consistency of a modeling clay, it was cut into bricks then conducted to oven to refine the drying. Ocher consists of iron oxide after baking which allows to obtain a red color. Then the bricks were brought to the mill to grind and put in bags or barrels. Today everything is mechanized.

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Modifié par lucile83 le 05-09-2013 15:36




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