Blow lance assembly for metal manufacturing and refining

Abstract

The instant invention relates to a blow lance assembly for metal manufacturing and refining, developed so as to control slag formation and oxidation, as well as the heat capacity of the reactor, and the conservation of the operational conditions during charging and blowing, having, in its lower part, two groups of gas outlets which determine two blowing conditions, the first group consisting of oxygen passage nozzles having a converging-diverging shape, main responsible for the oxidation reactions and for the conveyance of the basic solid material, mainly calcium oxide, for initial slag formation, and dephosphorization at the final stages during batch refining; the second group consisting of secondary jets with various functions during each blowing stage, the first function, at the beginning of the process as an afterburning agent, through the reaction of oxygen with carbon monoxide generated by the main jets, and the second function being that of accelerating the reaction with carbon by increasing oxygen jet speed, accelerating scrap melting in the early stages and, finally, incrementing the oxidation of the elements of the metal bath, iron, in order to reduce the phosphorus content in the final stages of batch refining.

Description

[0001]The instant invention relates to a blow lance assembly for metal manufacturing and refining, more specifically to a blow lance assembly used in steel manufacturing and refining, developed so as to control formation and oxidation of slag, heat capacity of the reactor, and conservation of charging and blowing operational conditions.STATE OF ART[0002]The BOF (Basic Oxygen Furnace) furnace is a cylindrical vessel closed at the bottom, having its upper end shaped like a conical frustum with a large opening at the top for charging the liquid pig iron and scrap, called “mouth”, and a small side opening called “pouring channel” through which liquid steel produced at the end of the primary refining is removed.[0003]To protect the furnace metal housing, a coating with a layer of refractory bricks is used in order to contain the liquid bath at elevated temperatures around 1700 Celsius degrees.[0004]The blowing process involves performing a sequence of steps, starting with charging. The v...

AI Technical Summary

Benefits of technology

The invention allows for independent control of oxygen and combustible gases during steelmaking processes. This can be useful for increasing the calorific value during the initial stages of melting and slag formation, reducing refining time during decarburization, and promoting afterburning to ensure low levels of dephosphorization during the final blowing step.

Problems solved by technology

The supply logistics of these silos is complex, comprising several stages, including the receipt of the material through highways or railways, carried in bulk or in “big-bags” (large packs).

In both cases, in each material transposing, the pollution effect is remarkable and containment requires considerable investment in dust-removal systems.

The efficiency of transmission of this additional amount of energy to the charge may also affect the amount of scrap used.

The final blowing step has an essential condition for phosphorus removal: high level of bath and slag oxidation; however, there is also a limiting element to dephosphorization: the high pouring temperature.

There are several problems that may usually occur in the described operation: a) the formation of solidified material (“scale”) around the blow lance, causing the increase in the diameter of the lance and scale, system damage in fume capture; b) the reduction of the metallic yield of the process caused by the solidified material with metal content; c) the high logistics costs and processing costs to recover the metal content of the solidified materials in the lances; d) long time to clean the scales formed on the lance; e) damage to the outer pipe of the lance caused by scales cleaning, which produces lance maintenance expenses; f) poor thermal balance for high amounts of scrap; g) lack of control in the slag formation time and high time of dissociation of basic solid material; and h) lack of control in scrap melting and dephosphorization at the end of the blow.

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