FI59079C - FREEZING FOR SUSPENSION OF SUCTION (II) SULFATHEPTAHYDRAT - Google Patents

Description

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* (44) Date of publication and date of publication. -.

Patent and Registration Office AntOkan utlagd och utl.akrlftan publteurad 27.02.81 (31) (33) (31) Pyydetty etuoikeus — Begird prlorltst 15-02.7 ^

Federal Republic of Germany Förbundsrepubliken Tyskland (DE) P 2 ^ 07203.5 (71) Kronos Titan-GmbH, 5090 Leverkusen 1, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (72) Achim Hartmann, Leverkusen, Achim Kulling, Leverkusen,

Dieter Schinkitz, Leverkusen, Federal Republic of Germany-Förbunds-republiken Tyskland (DE) (7 * 0 Oy Kolster Ab (5 * 0 Process for the preparation of free-flowing ferrous sulphate heptahydrate

The present invention relates to a process for the preparation of free-flowing ferrous sulphate sulphate from iron (II) -succinate iheptahydrate which accumulates in industrial processes.

Iron (II) sulphate heptahydrate accumulates in large quantities in various industrial processes, such as the production of titanium dioxide pigments according to the sulfur drawing method. It contains small amounts of infectious water and sulfuric acid and is therefore not free-flowing as it comes from the process so it can only be handled with great difficulty.

U.S. Patent 2,771 3 * + 2 proposes drying iron (II) sulfate heptahydrate to a FeSO 4 content of 56-60% and then mixing the dried crystals with finely divided calcium carbonate.

Although a flowable ferrous sulfate-heptahydrate-containing product can also be obtained in this way, there are several disadvantages of this method. Drying must be done very carefully so that the product does not melt; 59079, in addition, some of the hydrate water splits during drying. Therefore, costly measures are required to control the drying supply and cleavage of hydrated water requires higher energy costs. Aggregation occurs during drying, so in this case the product must be ground. In order to achieve an even distribution of calcium carbonate in ferrous sulphate, the mixing must be very vigorous.

A new process for the preparation of free-flowing ferrous sulphate heptahydrate from ferrous sulphate heptahydrate accumulated in industrial processes has now been invented. The process is characterized in that this ferrous sulfate heptahydrate is released from the adhering water in a fluidized bed at 5-65 ° C, using air as the fluidizing gas, and that this ferrous sulfate heptahydrate is simultaneously treated with up to 10% by weight. gaseous ammonia, calculated on the amount of ferrous sulphate heptahydrate fed.

The method is easy and simple to implement and the equipment cost is low. It can be advantageously used continuously. In contrast to the known method, iron (II) sulfate heptahydrate is dried and treated simultaneously in one operation. Substantial hydrated water cleavage does not occur. Ammonia can be easily metered in, for example, by adding it together with a fluidizing gas. However, ammonia can also be added separately. Only small amounts of ammonia are needed. It is not necessary to grind the product. The resulting product has good flowability and dispensability and is durable. It can be used, for example, as an additive in feed materials, fertilizers and cement. Due to its good release properties in water, it is suitable as a floKulating agent for chemical wastewater treatment.

It is essential that the ferrous sulphate hexahydrate from the industrial process be as dry as possible, i.e. generally not contain more than 2-5% by weight of water of adhesion. Such ferrous sulfate heptahydrate can be obtained by centrifugation or other suitable measures. Further care must be taken to ensure that the ferrous sulfate heptahydrate is introduced into the fluidized bed without clumping.

In fluidized bed treatment, 3 processes take place simultaneously: evaporation of the adherent water, neutralization of the adhered free acids and partial oxidation of the divalent iron to the trivalent iron.

The amount in which ammonia is used is essential for carrying out the process according to the invention. If this is too small, then the flowability and storage stability of the resulting product will be adversely affected. On the other hand, 3,59079 ammonia is generated by increasing the amount of water-insoluble substances that can interfere with the further processing of the product. The appropriate amount of amount can be easily determined experimentally.

Arbitrary devices known per se can be used to form the fluidized space. The choice of fluidizing gas is also largely freely selectable. Air is particularly preferred.

Example

In a fluidized bed with a diameter of 1 + 90 mm and a bed height of 620 mm, ferrous sulphate heptahydrate obtained by centrifugation of a titanium sulphate solution is treated at 30 ° C. The permeability was 90 kg / h. 200 Nm'Vh of air was used, which was mixed with 0.29 kg / h of ammonia before being introduced into the fluidized bed. To maintain the required fluidized bed temperature, the air was preheated to about 60 ° C before entering the fluidized bed reactor. Calculated from the free cross section of the fluidized bed, the gas velocity in the fluidized bed was 30 cm / s.

A sandy yellow to light brown free-flowing and storage-stable product with a grain size of 86 - # greater than 0.2 inches was obtained. The experiment was stopped after 1 + 0 hours of trouble-free use.

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