RU2516191C1 - Method of waelz process of oxidised zinc-containing materials - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: oxidised zinc-containing materials with coke dross as a hard carbon reducer are supplied into a rotary tubular furnace and exposed to Waelz process with supply of blow in the form of a steam and air mixture into zone of temperatures 1050-1150°C with content of steam in the mixture 14-25%.

EFFECT: reduced consumption of a reducer and content of zinc and lead in a clinker, eliminates softening of material in a furnace.

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Description

The invention relates to the metallurgy of non-ferrous metals and can be used in the processing of zinc-containing materials with a high content of lead by Weltzing, for example, zinc-containing dusts of copper smelting production.

There is a known method of welting oxidized zinc-containing materials, according to which, in order to increase the thermal inertia of the furnace, which allows to reduce the consumption of coke and the zinc content in the clinker, the diameter of the discharge opening is reduced from 1400 mm to 1000 mm (see Dorofeev V.M., Kozlov P.A. et al. / Non-ferrous metallurgy. Bull. Central Research Institute of Encem. 1978. No. 12. S.44-45).

The disadvantage of this method is:

- increase the processing time of the material in the furnace;

- reduced furnace performance;

- the degree of distillation of lead and zinc is reduced.

The closest technical specification to the claimed one is the method of weldging zinc-containing materials in a rotary tube furnace with feeding to the discharge part of the furnace to a temperature zone of 950-1000 (low pressure air P = 0.1 ÷ 0.2 atm) with the addition of oxygen (see Lakernik M.I., Pakhomova G.N. // Metallurgy of zinc and cadmium - M.: Metallurgy, 1969, p.401).

The disadvantage of this method is the high consumption of coke and significant losses of non-ferrous metals with clinker (zinc and lead). In this zone, the highest content of fusible silicates and the lowest content of coke breeze, one of the purposes of which in the Waelz process is to absorb the liquid phase and give the material the ability to weld (roll).

When coke is added to the blast in the specified zone, the temperature rises due to the exothermic reaction С + O ₂ = СО ₂ and the carbon content in the charge decreases.

Due to the increase in the number of fusible compounds and the formation of a "liquid bath", the process of distillation of lead and zinc from the charge is disrupted, and to normalize the process it is necessary to increase the consumption of coke breeze.

The patented method is based on the task of developing such a method that would reduce the loss of lead and zinc with clinker and the consumption of fuel and energy resources, in particular coke breeze, when processing by Waelz processing oxidized zinc-containing materials with a high content of lead.

This is achieved by the fact that in the known method of Weltzinzin zinc-containing materials in a rotary tube furnace, comprising supplying coke to the charge and air blasting with an additive, where water vapor is used as an additive in an amount ensuring its content in the blast of 14-25% and sent to the zone temperatures 1050-1150 ° C.

When steam is supplied to the furnace in the temperature zone 1050-1150 ° С, an endothermic reaction proceeds

At the same time, a new active hydrogen (H ₂ ) reducing agent appears in the gas phase of the furnace, which, falling into the reaction zone together with carbon monoxide (CO):

- increases the length of the reaction zone and reduces the length of the decomposition zone of sulfates;

- Reduces lead sulfates to highly inflammable sulfides; this increases the sublimation ability of the furnace in the processing of lead-rich materials;

- increases the degree of distillation of zinc and lead, as well as the productivity of the furnace without increasing the temperature of the reaction zone.

When oxygen is supplied to the temperature zone of 950-1000 ° С according to the prototype, the distillation of lead and zinc, as well as the furnace productivity are increased by increasing the temperature in the reaction zone from 1200-1300 to 1350-1450 ° С (the carbon necessary to absorb the formed at elevated temperature is consumed liquid phase and additional carbon consumption is required for the formation of a reducing agent).

Water vapors have a high emissivity, increase the thermal inertia of the furnace, therefore, despite the endothermicity of reaction (1), the temperature of the charge does not decrease below 1050 ° C. An increase in temperature above 1150 ° does not increase the positive effect, since the high length of the reaction zone allows the Waelz process to be carried out without increasing the temperature by more than 1150 ° C.

When steam is supplied to a temperature zone of less than 1050 ° C, the reaction rate (1) sharply decreases and an increase in losses of lead and zinc with clinker occurs.

When the vapor content in the blast is below 14%, the complete recovery of lead in the sublimates is not ensured. When the vapor content in the blast is more than 25%, the positive effect does not increase, but rather the material is cooled and increases the loss of zinc with clinker.

Thus, the patented method allows to reduce the loss of lead and zinc with clinker, to reduce the fuel consumption of the reducing agent, to eliminate the melting of the material, to process oxidized zinc-containing materials with a high content of lead.

The method is as follows.

Zinc-containing material, for example, copper smelting dust, composition,%: zinc - 18-20, lead - 20-25; iron - 1-5; silicon oxide - 2-4 in a mixture with a solid carbon reducing agent is loaded into a tubular rotary kiln and subjected to Waelz. Steam-air blast with a steam content of 14-25% is supplied to the discharge end of the furnace through a nozzle mounted parallel to the axis of the furnace to a temperature zone of 1050-1150 ° C.

Clinker discharged from the furnace is cooled and sent to the consumer. Zinc-containing sublimates are captured in the gas duct system and used in the hydrometallurgical production of zinc.

Example 1

Determination of the optimum temperature by the proposed method

Zinc-containing dusts of copper smelting production composition,%: zinc - 18.7, lead - 23.4, iron - 2.6, silicon oxide - 3.1 simultaneously with coke breeze was fed into the charging heat of the Waelz kiln (diameter - 4.0 m; length - 60.0 m) .

Through a horizontal nozzle installed in the discharge opening of the furnace parallel to the axis of the furnace, a steam-air mixture with a vapor content of 19% was supplied to a temperature zone of 1050-1150 ° C.

The consumption of steam blasting is 6600 m ³ / h, furnace loading is 15 t / h of copper smelting dust and 4.5 t / h of coke breeze, or 300 kg / h of coke breeze per ton of copper-containing zinc-containing dust.

For comparison, an experiment was conducted on the prototype.

Dusts of the specified composition were loaded into the furnace together with coke breeze in an amount of 300 kg / t of dust, fan air enriched with oxygen to a content of 25% in an amount of 6600 m ³ / h was supplied. The results of the experiments are given in table 1.

Table 1 Determination of optimum temperature The name of the method Material temperature, ° С Clinker content,% Material condition in the furnace zinc lead SUGGESTED 1000 1.9 1,5 Cold, loose 1050 0.5 0.4 Loose, Veltsy, hot 1100 0.4 0.3 Loose, Veltsy, hot 1150 0.1 0.2 Loose, Veltsy, hot 1200 0.1 0.2 Loose, veltsy, overheated FAMOUS 1000 2.1 2.6 Melt, "bath"

As can be seen from table 1, when the steam-air mixture is fed into the temperature zone of 1000 ° C, the content of zinc and lead in the clinker increases. When fed to a temperature zone of 1200 ° C (zinc content 0.1%, lead 0.2%), the positive effect does not increase, however, the material overheats.

When conducting an experiment on the prototype, the material melts in the furnace, which leads to a sharp increase in lead from 0.2-0.4 to 2.6%, and zinc from 0.1-0.5 to 2.1%.

To normalize the process, it is necessary to increase the load of the reducing fuel to 6.7 t / h or up to 446 kg / t of dust.

Example 2

Determination of the influence of the vapor content in the blast according to the proposed method.

The experiment was carried out with dusts on equipment and with the consumption of coke breeze, loading dust from the smelter production, as described above.

The vapor-air mixture was supplied to a temperature zone of 1100 ° C, the steam flow rate in the vapor-air mixture was,%: 13, 14, 19, 25, 26.

Determination of steam content by the proposed method

table 2 Determination of steam content by the proposed method The name of the method The vapor content in the steam-air mixture,% Clinker content,% Material condition in the furnace zinc lead SUGGESTED 13 1.3 1.4 Loose, cold fourteen 0.5 0.4 Loose, hot, welts 19 0.4 0.3 Loose, hot, welts 25 0.2 0.1 Loose, hot, welts 26 1,2 0.9 Loose, cold FAMOUS 0 2,4 2,8 Melt, "bath"

As can be seen from table 2, with a decrease in the vapor content in the mixture of less than 14%, the content of zinc and lead increases, respectively, from 0.2-0.5 to 1.3 and from 0.1-0.4 to 1.4%. The material cannot be completely heated.

With an increase in the vapor content in the mixture of more than 25%, the material cools and the content of zinc and lead in the clinker increases to 1.2 and 0.9%, respectively.

During the experiment on the prototype, but without the addition of steam, the material in the furnace melts and to normalize the process it was necessary, as in example 1, to increase the load of coke breeze.

Claims (1)

A method of welting oxidized zinc-containing material in a rotary tube furnace, comprising supplying coke to the charge and air blast with an additive, characterized in that water vapor is used as an additive in an amount ensuring its content in the air blast of 14-25%, and air blast is fed into zinc-containing material in the temperature zone 1050-1150 ° C.