Method of waelz process of oxidised zinc-containing materials

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.

2 tbl, 2 ex

 

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 valavanis, for example zinc-containing dusts copper production.

The known method of wellawaya oxidized zinc-containing materials, whereby to increase thermal inertia of the furnace to reduce the consumption of Corsica and zinc content in the clinker, reduced diameter discharge openings from 1400 mm to 1000 mm (see Dorofeev V.M., Kozlov, P.A., and other / non-ferrous metallurgy. Bull. CRI ENZM. 1978. No. 12. P.44-45).

The disadvantage of this method is:

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

- reduced the productivity of the furnace;

- reduced the degree of removal of lead and zinc.

The closest technical feature of the claimed is a method of wellawaya zinc-containing materials in a rotary tubular kiln feed to the discharge end of the furnace zone temperatures of 950-1000 (low pressure air P=0.1÷0.2 ATM) with the addition of oxygen (see Likiernik M.I., Pakhomov GN. // The metallurgy of zinc and cadmium - M.: metallurgy, 1969, s.401).

The disadvantage of this method is the high consumption of Corsica and significant loss of non-ferrous metals with clinker (zinc and lead). In this zone the highest content easily Lavka silicates and the lowest content of the coke breeze, one of the assignments in which the Waelz process is the absorption of the liquid phase and give the material the ability to wellawatta (roll).

In addition to blowing Corsica in this zone the temperature rises due to the exothermic reaction C+O2=CO2and reduces the carbon content in the charge.

Due to the increasing number of low-melting compounds and education "liquid pool" disrupted the process of removal of lead and zinc from charge, and for the normalization process, it is necessary to increase the consumption of coke breeze.

The basis of patentable method on the task of developing such a method which would reduce processing belizeanum oxidized zinc-containing materials with a high lead content, loss lead and zinc clinker and consumption of fuel and energy resources, in particular coke breeze.

This is achieved by the fact that in the known method of wellawaya zinc-containing materials in a rotary tubular furnace, including the filing of Corsica in furnace and air blast with the additive, where the additive use water vapor in an amount to provide its content in the blast 14-25% and sent to the zone temperature 1050-1150°C.

When the supply of steam into the furnace zone temperatures 1050-1150°C endothermic reaction proceeds

In gas phase the furnace there is a new active reducing agent hydrogen (H 2), which, falling into the reaction zone together with carbon monoxide (CO):

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

- restores the sulphates lead to legkovozvodimyh sulphides; this increases wasgonna the ability of the furnace during the processing of the rich on lead materials;

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

When applying the prototype of oxygen in the zone temperatures of 950-1000°C distillation of lead and zinc, as well as increase the productivity of the furnace by raising the temperature in the reaction zone with 1200-1300 up of 1350-1450°C (the amount of carbon required to absorb formed at elevated temperature liquid phase and requires additional consumption of carbon on the formation of reductant).

Water vapor have a high emissivity, increase thermal inertia of the furnace, therefore, despite indeterminate reaction (1), the temperature of the charge is not reduced below 1050°C. Rise in temperature above 1150° does not increase the positive effect because of the high length of the reaction zone allows the Waelz process without increasing the temperature more than 1150°C.

When the supply of steam to the zone temperature less than 1050°C dramatically reduces the rate of reaction is AI (1) and is increasing the losses of lead and zinc clinker.

When the water vapor content in the blast below 14% is not ensured complete removal of lead sublimates. When the water vapor content in the blast is more than 25% of the positive effect is not increased, but the opposite happens cooling of the material and increases the loss of zinc clinker.

Thus, in the newly developed method allows to reduce the losses of lead and zinc clinker, to reduce the fuel consumption of the reducing agent, to avoid melting of the material, recycle oxidized zinc-containing materials with a high content of lead.

The method is as follows.

Zinc-containing material, such as dust copper production, composition, %: zinc - 18-20, lead - 20-25; iron - 1-5; silica - 2-4 mixed with solid carbonaceous reducing agent is loaded into a tubular rotary furnace and subjected to valavani. At the discharge end of the furnace through a nozzle, mounted parallel to the axis of the furnace, is fed into the zone temperature 1050-1150°C vapor blast with the steam content 14-25%.

Discharged from the furnace clinker is cooled and sent to the consumer. Zinc sublimates catch in gazokhodny system and used in the hydrometallurgical production of zinc.

Example 1.

Determination of the optimal temperature for the proposed method

Zinc-containing dust copper production composition, %: zinc - 18.7, lead - 23.4, W is let - 2.6, the silicon oxide - 3.1 simultaneously with coke fines were filed in the boot estrus 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, filed a vapor mixture containing a pair of 19% in zone temperature 1050-1150°C.

The flow of vapor blast - 6600 m3/h, furnace - 15 t/h dust copper production and 4.5 t/h of coke breeze, or 300 kg/h coke breeze per tonne of zinc-containing dust copper production.

For comparison conducted the experience of the prototype.

Dust the indicated composition were loaded into the furnace together with coke fines in the amount of 300 kg/t dust, gave the fan the air is enriched with oxygen content of 25% in the number of 6600 m3/H. the results of the experiments are shown in table 1.

Table 1
Determination of the optimal temperature
The name of the methodThe material temperature, °CThe content of the clinker, %The condition of the material in the furnace
zinclead
OFFER10001,91,5Cool, loose
10500,50,4Loose, valuesa, hot
11000,40,3Loose, valuesa, hot
11500,10,2Loose, valuesa, hot
12000,10,2Loose, valuesa, superheated
KNOWN10002,12,6Melt, "bath"

As can be seen from table 1, when the supply of steam-air mixture in the zone temperatures of 1000°C increases the content of zinc and lead in the clinker. When applying to the zone temperatures of 1200°C (zinc content of 0.1%, lead - 0,2%) positive effect is not increased, however, the material is overheated.

During the experiment the prototype melting material in the furnace, which leads to a sharp took the teaching of lead from 0.2 to 0.4 to 2.6%, and zinc from 0.1-0.5 to 2.1%.

For the normalization process, it is necessary to increase the load of the fuel reductant to 6.7 t/h or up to 446 kg/t of dust.

Example 2.

The determination of the effect of water vapor content in the blast of the proposed method.

The experiment was carried out with the dust on the equipment and at a flow rate of the coke breeze, the dust boot copper production, as described above.

Steam-air mixture fed into the zone temperatures of 1100°C, the steam flow in the steam-air mixture was, %: 13, 14, 19, 25, 26.

Determination of water vapor content of the proposed method

Table 2
Determination of water vapor content of the proposed method
The name of the methodThe content of steam in the steam-air mixture, %The content of the clinker, %The condition of the material in the furnace
zinclead
OFFER131,31,4Loose, cool
14 0,50,4Loose, hot, valuesa
190,40,3Loose, hot, valuesa
250,20,1Loose, hot, valuesa
261,20,9Loose, cool
KNOWN02,42,8Melt, "bath"

As can be seen from table 2, by reducing the water vapor content in the mixture is less than 14%, the content of zinc and lead increases from 0.2-0.5-1.3 0.1-0.4 to 1.4 per cent. The material cannot be fully warm.

With increasing water vapor content in the mixture of more than 25% of the material is cooled and increases the content of zinc and lead in clinker respectively to 1.2 and 0.9%.

During the experiment the prototype, but without the additive material is melted in the furnace and for the normalization process, it was necessary, as in example 1, to increase the load of coke breeze.

How wellawaya oxidized zinc-containing material in the rotation is audace tubular furnace, including the filing of Corsica to the mixture and the air blast with the additive, wherein the additive use water vapor in an amount to provide its content in air blast 14-25%, and serves air blast in zinc-containing finishing material in the zone temperatures 1050-1150°C.



 

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