JPS58199833A - Preliminary reduction method of chromium ore - Google Patents

Abstract

PURPOSE:To stabilize the quality of preliminarily reduced ore in the stage of charging chromium ore into a preliminary reduction furnace and reducing the same preliminarily with a CH4-contg. coke oven gas, by adjusting the flow rate of the gas in such a way that the volume of the CH4 is kept constant. CONSTITUTION:The chromium ore is charged through a supply port 7 into a preliminary reduction furnace 9 and a coke oven gas is introduced through a main pipe 1 for coke oven gas into the furnace 9, whereby the ore is reduced preliminarily. The content of the CH4 in the coke oven gas to be supplied is measured with a detector 2 in this case and the opening of a flow rate controlling valve 4 is controlled with a controller 3 so that the CH4 flows always at a specified rate. The quality of the product of reduction is thus stabilized.

Description

[Detailed description of the invention] This invention is about the chromium □ ore O preliminary reduction method! MoC
)-7' available, especially ON as an active ingredient! When pre-reducing chromium powder ore by introducing coke oven gas with a variable content of We propose a method to stabilize the quality inside the pre-reducing furnace.

・Chromium ore resources tend to be of lower grade and become finer minerals. ・Production of ferrochrome by smelting ferrochrome ore usually relies on an electric furnace, but the electricity consumption rate is several thousand 11Ti/
◎Recently, the 'In fusion photoreduction method has been considered as a ferroalloy production technology for electric power as well as for 1% lI% 45 and other ferroalloys. ・The present invention They had previously used a device that included a pre-reduction reactor and a smelting reduction furnace.
1. Patent application @all-181 regarding a method for directly producing molten metal from powdered ore using exhaust gas generated from a smelting reduction furnace
Although it was proposed as No. 94, it is a technology that is applied to the smelting of various ores.
It is suitable to be made of chromium tIw.

However, - for preliminary reduction of sR elemental ores such as chromium ore, high temperature exhaust gas from the #l Kimoto reactor is used as a reducing gas.
1g! As a result, chromium oxide (orson) is more difficult to reduce than iron oxide (F@d) contained in the ore, so the preliminary reduction rate of the ore as a whole increases to 1%.
There is a ■ point between A and 1. The present inventors proposed a method for pre-reducing Tamu ore using heavy oil, coal, etc. in Japanese Patent Application Laid-Open No. 67-0813!11. In this method, the temperature inside the reactor must be maintained at 1,100 to 1,800°C for reduction at a high temperature, so it is a well-developed technology since it uses O exhaust gas from the smelting reduction furnace, which has a low temperature to begin with. Even though it is, it is powerful.

On the other hand, due to these circumstances, studies have been conducted on technology to reduce Shimu ore at low temperatures; for example, methane (OH) is known to be effective as a resolving agent.
Using liquefied natural gas (LNG) as methane increases forestry costs and is not practical. The present inventors focused on coke oven gas as a methane source that can be easily used in steel plants.

The composition of such coke oven gas is as shown below, which also contains hydrocarbons such as acetylene, ethylene, ethane, OmHn, 00 and HO in addition to methane. OOS ~ 84 Co, 1~8 Violet, To4 Omen m ~ 84 10B-1 Regret When such a coke oven gas is used for preliminary reduction, as mentioned above, the OH contained in the gas suddenly increases to 8 This causes inconvenience because it fluctuates widely within the range of 0 to 0.
Since H varies, the reduction rate of the discharged chromium ore changes in proportion to the volume of coke oven gas OE. This is because the degree of reduction of Kedashiri Sonmu ore is strongly influenced by the amount of Ol,'0. Therefore, if the OH4 content in the gas in the gas reactor is low, the pre-reduced ore with a low reduction rate will be reduced. When the OH4 content is high, chromium reserve 1-reduced ore with a high reduction rate will be produced〇ζ1)
*@ is a method developed with the aim of overcoming the operational uncertainties caused by fluctuations in the OH content in coke oven gas, and a constant rut of OH is always supplied into the pre-reducing furnace. We propose a method that stabilizes the quality of the reduction product by increasing or decreasing the amount of coke oven gas. The details of its composition are explained below. Figure 1 shows the relationship between the amount of CH4 and the reduction rate, and it is clear that the amount of OH4 has a strong influence on the rate of reduction of chromium ore. can be known.

FIG. 3 shows the variation in the content of OH in the coke oven gas, and it is clear that it varies depending on the coke oven operation. In this way, CH'1 in the coke oven gas fluctuates in the precincts, which occur in large cycles because air enters and dilutes the coking coal when it is charged into the coke oven, even though it occurs every few minutes. However, in the early stage of drying, more hydrocarbon gas is generated and in the later stage, more H and O are generated. Fig. 1 is a gas flow diagram illustrating the coke oven gas regulating means according to the present invention. When the coke oven gas flowing in the coater λ furnace gas main pipe l is supplied to the pre-reduction furnace 9, the detector 3 detects the presence of OH and OH! This is an example of a method for adjusting the flow rate control mechanism through the control device 8 according to the result. Ma is Yushigo ore supply port,
8 is a reduced ore outlet.

Next, Table 1 shows a comparison with the conventional method regarding the examples carried out to confirm the effects of the present invention. It became constant at $8. In short, according to the method of the present invention, the quality of the reduction product can be stabilized◎

[Brief explanation of the drawing]

$1115i11 is a graph showing the relationship between OH soda and reduction rate. Figure 3 is a graph showing the fluctuation of OH content in coke oven gas. Figure 8 is a graph showing the flow of coke oven gas. The route map shows: 1... Coke oven gas main, 4... Current control valve, ?
...Chrome ore supply port, 9...Preliminary reduction furnace.

Claims (1)

[Claims] L Chromium ore is charged into a preliminary reduction furnace, and a coke oven gas pipe is introduced into the furnace to form a fluidized bed.
In the method of pre-reducing OR,t' as an active component contained in this gas, the volume of the coke oven gas ollt-,ayi introduced into the pre-reduction furnace is adjusted to maintain a constant value. Preliminary method for Rishmu ore, which is characterized by performing 1 yuan while