Verfahren zur Herstellung von Calciumsulfit

摘要

1339572 Calcium sulphite LION FAT & OIL CO Ltd 7 Dec 1970 [9 Dec 1969 12 Feb 1970] 58014/70 Heading C1A [Also in Division C3] Calcium sulphite is prepared by a method comprising the steps of reacting calcium oxide with hot water to effect a hydration reaction and neutralizing the product slaked lime with a gas containing sulphur dioxide passed into the hot suspension until the pH is within the range 7-13, in both reactions the concentration of calcium compound is 5-20% by weight and the reaction temperature above 70‹ C. The pH after the passing of the sulphur dioxide is preferably 8À5-10 and the temperatures in the two reactions are conducted preferably 90-100‹ C. The sulphur dioxide may be obtained by oxidation of hydrogen sulphide obtained by separating hydrocarbon from a by-product gas such as one produced by hydrogenation of thermocracking of petroleum fractions. Preferably the concentration of the calcium hydroxide is below 5-15%. The suspension of calcium hydroxide may contain water-soluble inorganic salts such as halides, sulphates or nitrates of sodium, potassium, calcium, magnesium, aluminium to an extent of less than 1%. Ammonia or a surface active agent may also be present. The method may be performed in batchwise operation or continuously. In the latter case a plurality of reaction vats, preferably 3 or 4, may be employed. The bulk of the slaking is carried out in the first vat and 1À3-1À7/n of total amount of sulphur dioxide is preferably introduced into this part.