SU929723A1 - Method for passivating metal-plated product - Google Patents

Description

(54) METHOD OF PASSIVATION OF METALLIZED

one

The invention relates to the direct production of iron, and can also be used in the preparation of metallized raw materials for blast smelting and in powder metallurgy.

There are known methods for treating a metallized product aimed at its passivation: oxidation of the surface of pellet 1, treatment of pellets with light oils 2.

However, the methods cannot be considered effective since the former leads to a reduction in the iron content of the product, and the latter is associated with additional costs due to the use of oils.

The closest in technical essence and the achieved result is the method of passivation of the metallurgical product, which consists in treating the surface of the material with a solution of hydrophobic organic compounds fS 3.

The known passivation method has a number of disadvantages, making it non-technological. Application of product solution

due to poor wettability of the surface of the metal sponge, they cannot ensure the continuity of the protective film, and therefore; and proper passivation. The complexity of the organization of the technological process is caused by the need to prepare a mixture (according to the well-known most effective mixture of three components, one of which is polymerized silicone) and heat it to a temperature not lower than 50 ° C, and optimally to 80 ° C. In addition, the introduction of silicone contaminates the surface of the product, which is undesirable.

The aim of the invention is to increase the efficiency of passivation and reduce the cost of the method.

The goal is achieved by the fact that in the method of passivation of the metallized product, which consists in processing the surface of the material, the metal product is treated with the waste water of the coke-chemical production

the volume ratio of the metalized product and wastewater is 1: (0.5-1.5).

Wastewater from coke production is an aqueous solution of a surfactant, namely phenol. The use of a passivating surface treatment for a solution with surface-active properties leads to an improvement in wetting and ensures complete spreading of the solution on the surface of the material being processed.

Due to the adsorption of the surfactant from the wastewater of the coke-chemical production, the metallized product is coated with a monomolecular surfactant film preventing the material from oxidation.

The method is technologically simple enough, since it does not require additional wastewater treatment.

A distinctive feature of the method is that sewage from the coke chemical production, which is the unbalanced waste of the coke chemical production, is used for passivation.

An increase in the upper limit of the ratio is impractical because of the prolongation of the drying time, but a decrease in the lower limit is undesirable, since it can break the conditions for the formation of a monomolecular film.

Example. Sponge iron with a grain size of O, 315 mm is treated with waste water from coke-chemical plants. Orsk-Khalchlovsky metallurgical plant of the following composition, mg / l: Pianids.

Phenol565

Rodanidy450

Ammonia

volatile400

total900

The volume ratio of sponge iron and wastewater is 1: 1.

The oxidation rate of sponge iron at the onset temperature of oxidation (BOO after passivation is equal to 8 x 10 g / min compared with non passivated, where this is 8 x 10 g / min.

The use of the passivation method of the metallized product in comparison with the known solutions allows the use of a surfactant solution due to the formation of a continuous film, providing a 10-fold enhancement of the protective effect. The method is rather technological, as it does not require additional preparation of the solution, it is economical, since the waste water is an unbalance waste of coke production.

Reducing iron losses during the implementation of the proposed passivation method, as well as waste disposal, ensures the economic efficiency of the proposed solution.

Claims (3)

1. US patent number 3551215, class. 148-635, 1970. 2./(j bereit -TecViu, 1969, lO, No. 12, pp. 705 - 712. 3. US patent number 362986, cl. 428-405, 1971.