JPS6070111A - Manufacture of ferronickel - Google Patents

Abstract

PURPOSE:To increase the reactivity of ore nodules in reduction and to obtain high grade ferronickel while economically using all of coke by blending the ore nodules as a starting material with coke breeze, charging the blend into a blast furnace together with lump coke, and carrying out melting and reduction. CONSTITUTION:Coke breeze is sent to a stage for crushing and screening ore nodules as a starting material such as nodules of nickel oxide ore, and they are uniformly blended. Pulverized coal may be substituted for part of the coke breeze. The blend is charged into a blast furnace together with a flux such as limestone and lump coke as a heat source and a reducing agent, and melting and reduction are carried out. By this method, crude ferronickel having a lower P content can be manufactured at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ferronickel, and particularly to a method for producing ferronickel using a blast furnace method.

Ferronickel products are widely used in the form of ingots or shots as raw materials or additives for various alloys, and are particularly important as nickel additives for special steels, especially stainless steels.

Ferronickel is mainly produced by using nickel oxide ore as a raw material ore and reducing it. Typical methods for producing 7 ferronickel include an electric furnace method, a Kurzprene method, and a blast furnace method.

In the electric furnace method, calcined red-hot raw materials are charged into a closed electric furnace for reduction, and since the amount of reducing agent used is small and the clean energy of electricity is used, the amount of ferronickel produced is It has the advantage of being low in impurities, especially P (p=o, o21°).On the other hand, it has the disadvantage of high energy costs because electricity, heavy oil, and coal are used as energy sources. Since the ore is reduced in a furnace, the amount of impurities in the produced ferronimetal is slightly higher than that in an electric furnace.
After low-temperature reduction, the metals are recovered by magnetic separation, gravity beneficiation, etc., which makes the operation complicated and the product yield is said to be low. Finally, the current blast furnace method uses coke for melting and reduction, so the energy cost is low, but
When normal coke is used, P in the coke is α0
The P content in the produced ferronickel is as high as 11%, which is about 4%. Therefore, it is usually necessary to dephosphorize the P to about 001% using an LD converter or the like.

Although the advantages and disadvantages of the three methods have been outlined above, it is expected that the cost of electrical energy will continue to increase in the future, and from a cost perspective, the blast furnace method is being reconsidered as the mainstream in the future.

In the conventional blast furnace method, ores such as nickel oxide ores are made into briquettes after preliminary processing such as drying, crushing, sizing, and kneading, and the briquettes are made using flux such as limestone and coke as a heat source and reducing agent. In addition, it is put into the blast furnace. In the blast furnace, hot air of around 1000° C. is introduced from the tuyere, and a reduction reaction proceeds within the furnace. The charge is separated into molten metal, ie crude ferronickel metal solution, and slag, the slag being discharged almost continuously, while the crude ferronickel metal solution is poured out at regular intervals. The composition of the poured ferronickel sum metal depends on the composition of the ore,
It is determined in particular by its iron and nickel content. usually,
The nickel grade is around 20 degrees.

As mentioned above, coke, especially lump coke, has been used exclusively as a carbon material as a reducing agent and a heat source in such blast furnace processes. In the blast furnace method, it is important to ensure air permeability, and carbonaceous raw materials other than coke have a large proportion of small particles, making them unsuitable for use. Only lump coke, excluding solid coke, could be used. Since the removed coke powder does not require sintering in the blast furnace method, there is no way to use it effectively, and it has no choice but to be used as an energy source in other processes or sold. Coke powder accounts for 3-4% of coke raw materials.

Since coke powder can be used in the blast furnace method, the entire amount of coke raw material can be used, and the amount of lump coke used can be reduced accordingly, which is advantageous.

The present inventors have proposed a method for utilizing coke breeze by sending the sieved coke breeze to the ore crushing and sizing process, thoroughly mixing it with the ore, and making it into a briquette without any problems. We found that this is possible.

By doing so, the fine coke is evenly distributed within the briquette, which is more convenient for producing a reducing effect. The coke powder blended briquette does not collapse when charged into a blast furnace, and there is no deterioration in air permeability. Coke acts both as a heat source and as a reducing agent, but by using coke powder, which was not previously used as at least part of the reducing agent, inside the briquette, the entire coke raw material is wasted. In addition to reducing the amount of lump coke used, the coke breeze contained within the briquette is extremely beneficial in terms of improving reduction reactivity.

By incorporating powdered coke into the briquette and making effective use of it, it is also possible to use carbonaceous materials such as coal, such as anthracite, which has traditionally been used because it contains a large amount of powder. It means that. As mentioned above, since coke contains about 0.04% of P, the ferronickel crude metal produced in the blast furnace has a high P content and potash, and must be charged to an LD converter to remove P. there were. In addition to being cheap, anthracite has a low P content and has good reactivity.
By at least partially replacing coke, crude ferronickel with a lower P content than before can be produced at low cost. As a result, the burden of the conventional LD converter process can be reduced, and the blast furnace process becomes even more advantageous in terms of streamlining the process.

Thus, the present invention is characterized in that raw material ore briquette mixed with coke powder or at least coke powder substituted for powdered coal is charged into a blast furnace together with lump coke, and the ore is melted and reduced. Provides a method for producing ferronickel. Furthermore, the present invention charges raw ore briquette blended with coke powder, which is at least partially substituted for pulverized coal, into a blast furnace together with lump coke, which is at least partially substituted for lump coal. Provided is a method for producing ferronickel, which is characterized by performing melt reduction of ferronickel.

The present invention will be explained in detail below.

It is thought that the carbonaceous material contained in the briquette is heated together with the briquette and reacts with crystal water to generate CO and H2 gases, and also reacts with Fe, O, etc. to generate CO gas. It is thought that the generated Co and H2 gases function effectively as reducing gases, and the fact that the carbonaceous material comes into contact with the ore and is distributed in the briquette promotes the reduction reaction.

Although briquette formation can be achieved satisfactorily without the addition of a binder,
When it is desired to produce a briquette with stronger binding strength, an appropriate amount of binder may be added in the briquette process.

The ratio of the amount required as a heat source to the amount required for reduction out of the total amount of carbon material is said to be 9:1. % anthracite) is preferably used as the briquette inner body.

The briquette is carried out by adding an appropriate amount of water and, if necessary, a binder, using equipment such as a roll press, a pelletizer, etc., which rotates two rolls having concave surfaces.

In the present invention, powder refers to those with a size of 5ML or less,
Make larger pieces into chunks.

Example 1 Fe 10-13% and Ni 2.3-2.5%
Nickel oxide ore having a grade of 27 to 30 inches and a water content of 27 to 30 inches was dried to a water content of 18 inches.

On the other hand, the coke raw material was sieved and separated into lump coke of 20 to 120 tons and other coke powder.

The coke powder was crushed and sized together with the dry ore, and after being kneaded, it was made into briquettes. The obtained briquette was charged into a blast furnace together with the coke and limestone, and the blast furnace was operated under normal operating conditions. During the one-month operational test, no problems such as deterioration of ventilation occurred, and the operation was extremely smooth. The average throughput of ore per day is 361 tons, compared to 2&2
A 10-inch lump coke and a 10-inch powder coke were used. 1
Approximately 3.74) tons of coke powder per day could be used, and lump coke could be saved by that much.

Example 2 Anthracite coal, which is often 40 mm in size, was used with the aim of substituting 5% of coke. Coke powder and anthracite powder with a size of less than 20 m were sent to a nickel ore processing process and made into briquettes. Lump coke and anthracite coal were charged into a blast furnace together with briquettes, and the furnace was operated in a normal manner. The P content of the produced crude ferronickel decreased from 0.10% to 109%. No problems related to ventilation occurred.

Claims (1)

[Scope of Claims] 1) Raw material ore briquette blended with coke powder or coke powder substituted at least partially by powdered coal is charged into a blast furnace together with lump coke, and the ore is smelted and reduced. A method for producing ferronickel characterized by: 2) Charge the raw material ore briquette blended with pulverulent coke that has at least partially replaced pulverized coal into a blast furnace together with lump coke that has at least partially replaced pulverized coal, and melt and reduce the ore. A manufacturing method for 7-Elonitsuker characterized by performing the following steps. 3) The method according to claim 2, wherein the coal is anthracite.