JPH09287034A - Production of coarse zinc oxide and lead oxide sintered pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain permeability in an ore bed in superior state and to stably produce a product having satisfactory quality with high efficiency by specifying the maximum grain size of return powder. SOLUTION: It is found that the deterioration in permeability, due to fluctuations in the grain size distribution of return powder, is attributable to pelletizing, that is, the reason why deterioration in permeability is brought about is that, when return powder having a wide range of grain size distribution are charged, resultant pellets after pelletizing have also a wide range of grain size distribution and, as a result, the percentage of voids in the ore bed is lowered. Accordingly, in order to solve this problem, the maximum grain size of return powder is controlled to <=6mm to arrange the grain size distribution of the pellets more uniformly. By this method, a time to the completion of sintering can be shortened and productivity can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a crude zinc oxide / lead sinter lump by oxidizing and roasting a concentrate of zinc sulfide and lead sulfide and a regenerated powder which is a repeating product of its own process.

[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 concentrates of zinc sulfide and lead sulfide and the return powder, which is a repeated product of the self-process, are mixed in a mixing drum, and then water content is adjusted in a pelletizer, whereby granulation proceeds. 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.
Preheating / combustion / cooling of the sulfide progresses, and the heat generated during the combustion of the sulfide promotes the oxidation of the charging material to produce a sintered mass. A gas containing SO ₂ is generated in the sintering machine, and the entire sintering machine is covered with a hood in order to prevent the gas from leaking, and the generated gas is sucked and collected to produce sulfuric acid.

[0004] The obtained sintered mass is charged into a blast furnace together with coke in a layer form, where zinc oxide in the sintered mass is reduced and sent to a Pb splash condenser together with exhaust gas as Zn metal vapor. , Recovered as zinc metal. On the other hand, the lead oxide in the sintered mass is also reduced in the furnace, tapped together with the slag, separated from the specific gravity in the front floor, and then recovered as lead metal.

[0005] When a sintered mass is produced by blown air by using a Dwightroid type sinter, air permeability in the ore layer is very important in order to allow the oxidation reaction to proceed sufficiently. When the air permeability is impaired, not only the amount of S remaining in the sintered mass increases due to the unburned residue, but also the hood of the sintering machine and the hood for collecting the generated gas are sealed against the amount of gas blown into the ore formation. The amount of free air entering from the section increases,
Oxygen efficiency will deteriorate.

[0006] The relationship between the air permeability in the ore formation and the particle size distribution of the charge has been investigated so far, and the return powder having the largest weight ratio among the charge is an important control during operation. It is one of the items. However, it is the medium diameter of the reclaimed powder that is controlled by normal operation, and so far, little attention has been paid to the maximum particle size of the reclaimed powder. Further, under the control of the medium diameter, there is a problem that the air permeability may change and the operation may vary.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to obtain zinc sulphide and lead sulphide concentrates, regenerated powder which is a repeated product of the self-process, various intermediate products, and to produce a Dwightroid type product. When producing crude zinc oxide / lead sintered ingots with a blow-sintering machine, maintain the air permeability in the ore layer and stably and efficiently produce crude zinc oxide / lead ingots of sufficient quality. It is to provide a manufacturing method.

[0008]

In the method of the present invention for solving the above-mentioned problems, the maximum particle size of the return powder, which occupies the largest weight ratio in all the charged materials, is 6 mm.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In order to improve the productivity of a sintering machine, the present inventors have conducted an investigation to elucidate the cause of abnormal deterioration of air permeability of a charging material. Regarding the relationship between the air permeability in the ore layer and the particle size distribution of the return powder in the conventional method for producing crude zinc oxide / lead sinter, the maximum particle size of the return powder was removed from the operational control items. Property deteriorates, the amount of S remaining in the sintered mass increases due to unburned residue in the ore layer, oxygen efficiency,
The inventors of the present invention have come to the present invention by finding that the lump ratio is lowered and the productivity is deteriorated as a result.

The air flow resistance of the raw material in the sintering machine is determined by the so-called granulation, which is determined before the raw material is charged into the sintering machine, and the sintering after the raw material is charged into the sintering machine. They are roughly classified into two types, which are caused by so-called reactions that occur in the course of progress.

The present inventors have found that the cause of the abnormal deterioration of air permeability due to the variation in the particle size distribution of the return powder is due to granulation. In other words, when the reclaimed powder having a wide particle size distribution is charged, the granulated product after granulation also has a wide particle size distribution, and as a result, the porosity in the ore formation is reduced. I thought. Then, in order to eliminate this, the maximum particle diameter of the return powder is controlled to 6 mm or less to make the particle size distribution of the granulated material more uniform, to eliminate abnormal deterioration of air permeability, and to shorten the burning end time. And succeeded in improving productivity.

[0012]

EXAMPLES The present invention will be further described below with reference to examples.

[Examples] As shown in Table 1, raw materials having a particle size distribution such that the maximum particle size is 6 mm or less are shown in Table 2.
As shown in Table 3, about 3 kg of a test raw material having a general chemical composition as a zinc / lead sintering raw material was obtained as shown in Table 3 while adding water. This is 70mm in diameter
C. A test was conducted in which a small-sized sintering tester capable of firing an ore layer having a height of 300 mm was charged and a sintered ingot was manufactured at an air flow rate of 54 (l / min). Table 4 and FIG. 1 show changes in the blowing pressure during blowing with respect to the elapsed time of blowing.

[Comparative Example] Table 4 and FIG. 1 also show the results when the same test as in Example was carried out using the return powder having a wide range of particle sizes shown in Table 1.

As shown in FIG. 1 and Table 4, in the present invention, the average value of the blowing pressure during firing is lower than that of the comparative example. Therefore, as shown in Table 5, in the comparative example, the time required from the start to the end of firing was 27 minutes, while in the range of the present invention, it was reduced to 23 minutes, which is close to 15%, and the residual It can be confirmed that the S quality is also sufficiently reduced within the range of the present invention. This is because as a result of maintaining good air permeability, the oxygen efficiency for the combustion of S is also improved.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

As described above, since the air permeability was maintained good in the compact sintering tester, according to the experience of the present inventors, the same effect can be obtained also in the Dwightroid type sintering machine.

[0022]

EFFECTS OF THE INVENTION According to the present invention, the air permeability in the ore layer is maintained well until the firing is completed, so that the crude zinc oxide / lead sintered lump having sufficient quality can be stably and efficiently produced. Can be manufactured well.

[Brief description of drawings]

FIG. 1 is a graph showing a change in blowing pressure with respect to an elapsed time from the start of blowing when a crude zinc oxide-lead sintered ingot is manufactured in a small-sized sintering tester.

Claims (1)

[Claims] 1. A method for producing a crude zinc oxide / lead sinter ingot with a Dwightroid-type top-blown sinter machine from a raw material mainly composed of zinc sulfide and lead sulfide concentrate and self-process reclaimed powder, A method for producing a crude zinc oxide / lead sinter lump, characterized in that the maximum particle size of the returned powder is 6 mm.