JPH09316551A - Production of crude zinc and lead oxide sintered block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the breathability in an ore layer to good condition and to stably and efficiently produce crude zinc and lead oxide sintered block having good quality. SOLUTION: Concentrates of zinc sulfide and lead sulfide and gas dust, returned powder and intermediate produced material in a blast furnace, are used as raw materials, and the crude zinc and lead oxide sintered block is produced with a Dwight Lloyd type top-blown sintering machine. The gas dust in the blast furnace contains low m.p. metal components. In the progressing process of sintering, after drying the raw materials, such low m.p. of metal components as Zn, Pb contained in the exhaust gas dust in the preheating zone is melt-liquefied to clog the blasting passage. In order to avoid this phenomenon, the exhaust gas dust is beforehand oxidized-roasted and charged into the sintering machine as the oxide having further higher m.p. and sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for sintering crude zinc oxide and lead by oxidizing and roasting concentrates of zinc sulfide and lead sulfide, refined powder which is a self-processed repetition product, and various intermediate products. It relates to a method for producing a lump.

[0002]

2. Description of the Related Art The ISP method currently in operation will be described as an example of obtaining a coarse zinc oxide / lead sintered mass using a Dwyroid type top-blowing sintering machine. The zinc sulfide and lead sulfide concentrates, the regenerated powder which is a repeat product of its own process, and various intermediate products are mixed in a mixing drum, and then water content is adjusted in a pelletizer to granulate. proceed. The granulation is performed here to prevent dust generation during transportation to the sintering machine or to maintain gas permeability during oxidizing and roasting in the sintering machine.

In the sintering machine, a thin charge having a thickness of about 3 to 4 cm is first stacked on a grate having a width of about 2.5 m to ignite the ore layer, and heated from above with a heavy oil burner or the like. While being sucked and blown downward, it begins to burn. After that, the second charging was carried out so that the height of the whole ore layer was about 30 cm, and it was dried from the lower layer to the upper layer sequentially while moving from the front side to the rear side by about 30 m by blowing up.
As preheating, combustion and cooling of sulfide proceed, heat generation during combustion of this sulfide promotes oxidation of the charge, and a sintered lump is generated.

Since a gas containing SO ₂ is produced in the sintering machine, the entire sintering machine is covered with a hood to prevent leakage, and the produced gas is sucked and recovered to produce sulfuric acid. The obtained sintered ingot is charged into a smelting furnace together with coke in a layered manner, where zinc oxide in the sintered ingot is reduced and sent as Zn metal vapor together with the exhaust gas to a Pb splash condenser to obtain zinc metal. Will be collected as. The lead oxide in the sintered mass is also reduced in the furnace, is periodically tapped together with the slag, is separated on the front floor by specific gravity, and is recovered as lead metal.

On the other hand, exhaust gas dust from a roasting furnace (condenser) is charged as a sintering raw material in the sintering machine at a rate of about 0.8 to 1.2%. That is, Zn and Pb metal vapors not recovered in the condenser and Pb metal scattered as splash in the condenser part are partially reoxidized and then cooled by a wet dust collector,
Collected as dust. This dust is suction-filtered to remove water, and then repeatedly returned to the sintering machine together with various intermediate products.

[0006] When a sintered mass is produced by top blowing using a Dwyroid type sintering machine, air permeability in the ore layer is very important for the oxidation reaction to proceed sufficiently. When the air permeability is impaired, not only the amount of S remaining in the sintered ingot due to unburned residue increases, but also the amount of gas blown into the ore layer, the hood for collecting generated gas and the sintering machine are not used. The amount of free air entering from the seal portion increases, and the oxygen efficiency deteriorates.

[0007]

Among various kinds of intermediate products charged into a sintering machine, it has been found that dust of blast furnace exhaust gas causes an abnormal increase in ventilation resistance. This dust is characterized by containing a metal component having a low melting point. For this reason, in the conventional method for producing a crude zinc oxide / lead sinter lump, when an intermediate product containing a low melting point metal component such as exhaust gas dust of a blast furnace is treated, air permeability deteriorates and The unburned residue caused an increase in S remaining in the sintered mass and a decrease in oxygen efficiency, resulting in deterioration of productivity.

Accordingly, in view of the above, an object of the present invention is to use a concentrate of zinc sulfide and lead sulfide, a regenerated powder which is a self-process repeating product, and various intermediate products in a Dwightroid-type top blowing sintering machine. When producing crude zinc oxide / lead sintered ingot,
Provided is a method for stably and efficiently producing a crude zinc oxide / lead sinter ingot having sufficient quality while maintaining air permeability in a ore formation even when a substance containing a low melting point metal component is treated. Especially.

[0009]

In the method of the present invention for solving the above problems, a substance containing a metal component having a low melting point is previously oxidized and roasted to be a raw material for a sintering machine.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have been investigating to elucidate the cause of abnormal deterioration of air permeability of a charge in order to improve the productivity of a sintering machine. Of particular importance in day-to-day operation management is the permeability within the mineral formation. The ventilation resistance of the raw material in the sintering machine is determined before the raw material is loaded into the sintering machine, which is caused by so-called granulation and occurs during the sintering process after the raw material is loaded into the sintering machine. There are two main categories, namely, those caused by so-called reactions.

It has been empirically said that the deterioration of air permeability has a correlation with the ratio of the powdery raw material to the total charge,
It was considered that various intermediate products having particularly fine particle sizes were adversely affected in the charge of the sintering machine. Therefore, the cause of abnormal deterioration of air permeability when the intermediate product, which is one of the charging materials for the sintering machine, was processed was investigated. Among various intermediate products that are raw materials for the sintering machine, there is a close relationship between the exhaust gas dust of the blast furnace and the condenser and the abnormal deterioration, and the low-melting-point metal component is permeable. It was found that this is the main cause of the abnormal deterioration and that the abnormal deterioration of the air permeability is eliminated by oxidizing the exhaust gas dust before charging the sintering machine.

The cause of the abnormal deterioration of air permeability due to the exhaust gas dust is due to the reaction, and is a region where the raw material is preheated after drying in the process of sintering, such as Zn and Pb contained in the exhaust gas dust. It is considered that the cause is that the low-melting metal component melts into liquid and blocks the ventilation path. , And succeeded in eliminating abnormal deterioration of air permeability in the sintering machine.
Therefore, by improving the breathability according to the present invention,
It is possible to easily improve the productivity of the crude zinc oxide / lead sintered ingot. Hereinafter, the present invention will be further described using examples.

[0013]

[Examples] Oxidation treatment in which exhaust gas dust of a smelting furnace (condenser) having the chemical composition shown in the lower part of Table 1 was subjected to oxidation roasting at about 900 ° C for 30 minutes while blowing air in a small electric furnace for testing 30 g of dust is added to 3 kg of a general sintering raw material having the chemical composition shown in the upper part of Table 1 and charged into a small sintering tester (diameter 70 mm × height 300 mm) to produce a sintered mass. The test was conducted. The air blowing resistance of the blower with respect to the elapsed time of air blowing at this time is shown in Table 2 (left column) and FIG. Also, a comparative example in which exhaust gas dust is not added,
Table 2 (middle column, right column) and FIG. 1 show the results of sintering and testing in the same manner as in the comparative example in which 30 g of exhaust gas dust not subjected to oxidation roasting was added.

When the exhaust gas dust of the blast furnace which is not subjected to oxidative roasting is added to the sintering raw material, compared with the blast pressure when the sintering raw material is fired without adding the blast furnace exhaust gas dust,
It can be seen that the ventilation pressure is high and the air permeability is significantly impaired. On the other hand, when the blast furnace exhaust gas dust is oxidized and then added to the sintering raw material, the blast pressure during firing is almost the same as when the blast furnace exhaust gas dust is not added, and good air permeability is obtained. You can see that you are maintaining.

[0015]

[0016]

[Table 2]

[0017]

According to the present invention, even when a low melting point metal component-containing substance such as exhaust gas dust of a blast furnace is treated in a sintering machine, air permeability in the ore layer is maintained and sufficient quality is obtained. It is possible to stably and efficiently produce the crude zinc oxide / lead sinter ingot.

[Brief description of drawings]

FIG. 1 is a graph showing changes in blowing pressure with respect to the elapsed time from the start of blowing air in a sintering machine in each case of addition of oxidized exhaust gas dust, addition of exhaust gas dust, and addition of exhaust gas without oxidation treatment.

Claims (2)

[Claims] 1. A method for producing a crude zinc oxide / lead sinter ingot by a Dwightroid-type top-blown sinter machine from a raw material mainly composed of zinc sulfide and lead sulfide concentrates and a substance having a low melting point metal component. 2. A method for producing a crude zinc oxide / lead sinter lump, characterized in that the low melting point metal component-containing substance is oxidized and roasted before charging. 2. The method for producing a crude zinc oxide / lead sinter ingot according to claim 1, wherein the substance having a low melting point metal component is exhaust gas dust of a blast furnace.