JPS58199834A - Preliminary reduction method of chromium ore - Google Patents

Abstract

PURPOSE:To produce ferrochromium inexpensively in a high yield, by constituting a preliminary reduction furnace for chromium ore by segmenting the same into a reaction region where FeO is reduced preferentially and a reaction region where the reduction of mainly Cr2O3 is accelerated. CONSTITUTION:Chromium ore 2 and a carboneous material 3 are charged into a preliminary reduction furnace 1 for reduction of iron oxide, and the waste gas (CO+N2) 4 generated in a melt reduction furnace, gasous H2 and the waste gases 7, 8 generated from a preliminary reduction furnace 9 for reduction of chromium oxide are introduced into said furnace, where the fluidized reduction of mainly FeO is accomplished. When the preliminary reduction of the FeO progresses to a certain extent, the preliminarily reduced ore is transferred through a connecting pipe 6 into the furnace 9, where a CH4-contg. gas 12 is introduced together with the waste gas (CO+N2) 10 generated in the melt reduction furnace to the ore and the reduction of Cr2O3 is accomplished. The ore upon completion of the preliminary reduction is transferred with a transport pipe 11 to the melt reduction furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for pre-reduction of chromium ore, and in particular, the pre-reduction furnace is equipped with a reaction zone that gives priority to r. We propose a three-stage preparation method with a structure divided into reaction zones and reaction zones.Chromium ore resources are trending toward lower grade and abandoned mineralization. Ferrochrome is usually manufactured using an electric furnace from chromium ore, but the electricity consumption rate reaches several thousand units per liter, making it extremely costly.Recently, ferrochrome and other ferroalloy manufacturing technologies that do not rely on electricity have been developed. The smelting reduction method is attracting attention as a smelting reduction method.The present inventors previously used a Wl system that directly connected a preliminary reduction furnace and a smelting reduction furnace to directly convert molten metal from powdered ore by using the exhaust gas generated by the smelting reduction furnace. 4. How to manufacture? Gansho 5o-sss
・Although this method was proposed as a fourth step, it is a technology that is applied to the smelting of various ores, and is suitable for smelting ferrochrome from chromium ore, for example.

However, when high-temperature exhaust gas from a molten @ reduction furnace is used as a reducing gas for the remains of a hard-to-reducible ore such as chromium ore, chromium oxide (Or, 08) is more concentrated than iron oxide (ore) contained in the ore. Since it is difficult to reduce compared to FeO), the preliminary reduction rate of chromium ore as a whole does not increase.1
There is a point O Also, the present inventors have disclosed a method for preliminary reduction of chromium ore using heavy oil, coal, etc. This method was proposed as No. 011851, but since this method requires reduction at a high temperature while maintaining the temperature inside the reactor at 1100 to 1800°C, the exhaust gas tIs from the smelting reduction furnace, which is originally at a low temperature, is used. On the other hand, due to these circumstances, studies have been conducted on technology to reduce chromium ore at low temperatures; for example, methane (OIL) is effective as a reducing agent. Generally, the reducing power of 0T14 is better than that of H,oo. That is, when reducing the ore using Hao at an internal temperature of 1100°C,
Reduction of F・0 in Ripm ore & proceeding cleverly, but GrOC
) i17c is extremely bad O. On the other hand, when 0- is used, the reduction of both r, O, Or, and O progresses well. The problem here is that this OH4 is converted into a reducing gas. The disadvantage is that the price is high when used as a Reducing r of FeO and Or O
18 Focusing on the difference, only the reduction of G r s , which is difficult to reduce, was carried out using an OR4-containing gas such as 0 gas, and the reduction of G r s , which was easily reducible
O reduction was performed by (30,H,), so
This solution solved the key points of the conventional technology.
In the method of pre-reducing by introducing exhaust gas generated from a smelting reduction furnace containing 0 and 6 as main components, the pre-reduction furnace is provided separately into a pre-reduction area for elemental iron reduction and a pre-reduction area for chromium oxide. , First, the limestone and vertical members are
−The exhaust gas generated in the smelting reduction furnace and the exhaust gas generated in the preliminary reduction zone for chromium monoxide reduction are charged into the preliminary reduction zone for iron oxide reduction.
00. used as a preferred example. )! , N gas is introduced to perform preferential reduction of 7eO in the ore, and then the pre-reduced ore is further transferred to the pre-reduction zone for chromium oxide reduction and 01 (, containing gas and This is a preliminary reduction method for chromium ore characterized by reducing Or, O, in the exhaust gas generated by the smelting reduction furnace. Figure S shows the reduction rate characteristics of reducing gases (G4) with various compositions as shown in Fig. 04+)') and present invention 5 (OH4=late (6
0 minutes), 00. H,: Early period (oo minutes) (F1 stage reduction)
O1! is a diagram showing a comparison of reduction rate curves with O1! In the experiment, chromium ore s4 was pre-reduced at a temperature of 1100°C in a fluidized reaction vessel.0 Table 1 (Supplied gas @ //win)
The three types of reduction rates used in Figure 1 and tIIis diagram are (1
)~(8) 0 railway yuan rate defined as in formula R,,=
aoe, Fe/'r, Fe x 100 (1) Or
Reduction rate Ror= sol, Or/T, Or x 1
00 (1) What can be seen from Figure 1 is “(3r, RT
increases with the increase in CH4, but the rate of increase in R1° with respect to the increase in OH4 is small. can be obtained using 00,H, without using OH, but a high value cannot be obtained without using R0r#jOH4. In order to make R1 a low value, it is necessary to increase R6r, and for that reason, OH is absolutely necessary. The example of I gas in the figure is an example of the present invention.
When using H4-containing gas separately, the total reduction time is 1f.
The first 60 minutes of the fiO minute are used to supply Co, T (, and gases containing gas) to the preliminary reduction furnace for iron oxide reduction in the m1 stage,
0 minutes is OH to the preliminary furnace for chromium oxide reduction in the second stage.
Containing gas (C gas) was supplied. In this example, R7 was significantly improved.

In addition, Figure 2 shows the results under the experimental conditions shown in Table 2, but compared to the conventional method (example of D gas) in which 0H4Tt is flowed from the beginning until after 11k, CO, H, and gases are initially flowed for 60 minutes and then It was found that the method of the present invention (example of E gas) in which OH was flowed for 60 minutes had a higher R1 after 90 minutes. The reason why R1 improves in the case of the method of the present invention is because of ■OH supply amount?
//sin, and there is a lot of noise compared to the conventional method. Focusing on the Ore particles, in the case of the method of the present invention, reduction of FeO has progressed before OH4 is supplied, so pores are generated within the particles. OH, Nyoru O
r, which allows easy entry of OH4 during 08 reduction.

Table 3 Figure 8 of the drawings shows an example of equipment that is a preferred embodiment of the present invention.
It is unique in that it is supplied with the exhaust gas from the molten IIR main furnace and the exhaust gas generated from the preliminary reduction furnace for reducing chromium oxide, while the exhaust gas generated from the smelting reduction furnace, OH, and gas are used for the preliminary reduction furnace for reducing chromium oxide. . 1 in the figure is a preliminary reduction furnace for iron oxide reduction, and here, when chromium ore 2 and carbonaceous material 3 are charged, the smelting reduction furnace generates exhaust gas (OO+N,) 4
By introducing H, gas 6, and generated exhaust gas 7.8 from the preliminary reduction furnace 9 for reducing chromium oxide, fluidized reduction of F.O is mainly performed.

After that, when preliminary reduction of FeO has progressed to a certain extent,
The pre-reduced ore is transferred through the connecting pipe 6 into the pre-reduction furnace 9 for reducing chromium oxide located in the lower stage, and is then transferred to the smelting reduction furnace together with the exhaust gas (OQ+M) and the OH-containing gas 1! is introduced to perform the reduction of Or, O, and the pre-reduced ore is transferred to a smelting reduction furnace (not shown) via a transport pipe 11. Table 8 Rhium ore: Chromium ore from the Philippines Composition: Or O49,248 FsOR08 Particle size: 98~48M? , GL staff 48~100M 8t$,? Below M, No. 51 (M is mesh, 0) Omotabatake shows the effect of the present invention, and it can be seen that the reduction rate (R1) is improved compared to the conventional method.

In summary, in the case of the present invention, a high reduction rate can be obtained even in low-temperature reduction with a small amount of OH-containing gas used, and ferrochrome can be produced at a high yield and at low cost.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between reducing gas composition and reduction rate, Figure 2 is a graph showing the relationship between reduction rate and reduction time, showing a comparison between the present method and the conventional method, and Figure 8 is a graph showing the relationship between reducing gas composition and reduction rate. It is a schematic diagram of a pre-reduced lid for use. l...Preliminary reduction furnace for reducing iron oxide, 6...Connecting pipe, 9...Preliminary reduction furnace for reducing chromium oxide, 11...Transport pipe millet

Claims (1)

[Scope of Claims] 1. A method for pre-reducing chromium ore in a pre-reduction furnace forming a fluidized bed by introducing a melted amount of exhaust gas generated from the main furnace, the main components of which are 00 and N. are separated into a preliminary reduction zone for iron oxide reduction and a preliminary reduction zone for fistified ROM reduction. First, chromium ore and carbon material T# are charged into the preliminary reduction zone for iron oxide remains, and 00 ．． H,M. A gas is introduced to perform preferential reduction of 1.0 in the ore, and then the pre-reduced ore is transferred to the above-mentioned pre-reduction zone for chromium oxide reduction, where mainly an OH-containing gas is introduced to reduce Or, O. A preliminary reduction method for chromium ore, which is characterized by reducing ◎