SU1765221A1 - Method of melting secondary aluminium-containing raw materials into reverberatory furnace - Google Patents

Abstract

Usage: in the field of secondary non-ferrous metallurgy in the reflective smelting of aluminum scrap and the smelting of bronze-brass alloys. SUBSTANCE: melting is carried out in a reflective furnace. 10-15% of the charge is loaded directly under a vertical tuyere, the remaining part is evenly distributed along the furnace hearth.

Description

The invention relates to the field of secondary non-ferrous metallurgy and can be used in the reflective smelting of aluminum scrap and the smelting of bronze-brass alloys.

Analogs of the invention are known where it is recommended to install end nozzles at an angle of 12-20 ° to the horizontal, as well as to use a vertical lance in the heating system to improve the process performance. This increases the convective component of the process of heat and mass transfer and improves the thermal performance of smelting.

The prototype of the invention is a method of processing secondary aluminum-containing raw materials in a reflective furnace, where the charge is melted due to both the heat from burning fuel at the end nozzles and the supply of 25-35% of natural gas (from its total consumption) to the vertical tuyere. .

The disadvantage of the prototype is the inefficient use of heat from the combustion of fuel on a vertical tuyere, which

leads to a relative increase in the duration of melting.

The aim of the invention is to reduce the duration of the process of smelting scrap and waste in a furnace with a vertical tuyere.

This goal is achieved by the fact that 10-15% of the charge of its total amount is loaded directly under the tuyere, and the rest is evenly distributed along the furnace hearth.

Under the terms of the prototype, the smelting of scrap and waste in a furnace equipped with a tuyere can be characterized by the following value of the efficiency of the combined end-arch heating: t-1256-3700

P1 36468

„At 1256 2 36468

- HERE-100 32.6% 3500

-390-100 30.9%

where 3700 and 3500 kg / h are the specific furnace performance when burning the lance, respectively, 35 and 25% of the fuel from its consumption at the end nozzles;

WITH

WITH

vi

ON SL U

Yu

1256 kJ / kg - total heat consumption of the charge;

36468 kJ / m3 - gas heating capacity;

390 is the total amount of gas burned in the furnace, m3 / h. When vit:

L PS With OO / 1L

100 28.4%

conventional heating furnace efficiency ratio of 1256-3300

 36468

400

Wmax 0)

where: 3300 kg / h - the performance of conventional reflective melting without a tuyere;

400 m3 / h - gas consumption at the end nozzles.

The maximum filling rate for the tuyere can be determined from the relationship:

Oz -Shch

ZG

where Oz is the heat intensity of the melting chamber, kW;

d g - the change in the enthalpy of the charge during the filling period, equal to / 1/963 kJ / kg;

rj is the change in furnace efficiency due to the operation of the tuyere.

When the face-joint heating efficiency of the furnace increases by

30.9-28.4 2.5% rel. 32.6-28.4 4.2% rel. The thermal strength of the smelting chamber is defined as:

(36468-400): 3600–3900 kW After substituting the indicated data into equation (1), we obtain the values of the maximum filling rate corresponding to various increases in the efficiency of the front-end heating of the furnace:

963

W -3900 -0.042 „„ with W2963OJ5

Thus, based on the increased efficiency of the directional torch, the loading rate of the charge under the tuyere with a combined face-arch heating should be increased by 10-15%.

Loading most of the scrap under the tuyere allows organizing its melting under the conditions of simultaneous impact of the torch of the end nozzles on the side surface of the filling and the torch of the tuyere on the upper surface of the solid metal.

Intensive melting of the charge under the tuyere, followed by spraying

0

five

five

0

five

0

0

five

0

five

metal accelerates the process of melting scrap and waste in the rest of the kiln.

The charge charge less than 10% of the total mass of the filling causes the need to load additional scrap under the tuyere, which increases the duration of loading and melting. In addition, the effectiveness of direct impact of the torch of the end nozzles on the side surface of the filling decreases.

Charging the charge under the tuyere in an amount of more than 15% of the total furnace charge reduces the melting efficiency in the hearth areas where the heat exchange is dominant, i.e. The process of scrap and waste smelting mainly takes place at the expense of end nozzles. This also leads to an increase in the duration of the process.

PRI me R. In a two-chamber reflective furnace equipped with a vertical tuyere, 20 tons of aluminum scrap and waste were processed. Initially, the charge charge was evenly distributed over the bottom surface. The duration of loading and melting in this case was 6.2 hours. The fuel consumption at the end nozzles was 300 m3 / h, at the tuyere 120 m3 / h. In the subsequent melting was carried out with preloading under the torch of the vertical tuyere, respectively: 1.0; 1.5; 2.0; 2.5; 3.0; 3.5 t / h The rest of the charge was evenly distributed over the hearth of the furnace. The duration of loading and complete melting of the charge, respectively, was 6.3; 5.8; 5.7; 5.5; 5.3; 6.2; 6.4 hours

The content of alumina in the slag decreased from 24.03% by prototype to 9.67% by the claimed method. At the same time, extraction of AI into the alloy increased accordingly from 57.4% to 63.8%.

Thus, it is advisable to load 10-15% of the charge of its total amount into the area of action of the vertical tuyere, and distribute the rest of the filling evenly in the hearth of the furnace.

Claims (1)

Invention Formula The method of smelting secondary aluminum-containing raw materials in a reflective furnace, including loading the charge and melting due to heat from burning fuel at the end nozzles of the furnace and a vertical tuyere, characterized in that, in order to reduce the duration of loading and melting, 10-15% of the total charge its quantities are loaded under the tuyere, and the rest is evenly distributed along the hearth of the furnace.