JPH06108176A - Method for adding sulfur source in smelting of nickel oxide ore - Google Patents

Abstract

PURPOSE:To ameliorate the poorness of the yield of sulfur in the method of adding a sulfur source to smelting raw materials consisting of nickel oxide ore, carbonaceous materials and line in order to improve the recovery rate of nickel at the time of heating and reducing the nickel oxide ore in a counter current type heating furnace. CONSTITUTION:The fuel contg. the sulfur source or compounded therewith is burned with a burner 6 for heating and the sulfur source is added to the smelting raw materials 4 in the method for smelting the nickel oxide ore by a dry process using the counter current type heating furnace 1. As a result, the amt. of the harmful SOx generated is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for smelting nickel oxide ore, and more particularly to a method for smelting nickel oxide ore having a high nickel recovery rate.

[0002]

2. Description of the Related Art Conventionally, as a method for smelting nickel oxide ore to produce ferro-nickel concentrate, usually, nickel ore as a main raw material, carbonaceous material as an auxiliary raw material, and limestone are respectively used in an erotic foam mill or a rod mill. Dry pulverization or wet pulverization by adding water to this with a tube mill, mixing these at a predetermined ratio, forming into briquettes, drying, and firing if necessary, such as in a rotary kiln or shaft furnace Countercurrent heating furnace at 900 ℃ ~ 14
A method of heating at a temperature of 00 ° C. is used. Various improvements have been made regarding the blending of the raw materials and the heating conditions.

When nickel laterite ores containing a considerable amount of silicate moieties are reduced in the presence of a reactant containing an alkali metal compound or an alkaline earth metal compound, the coalescence of the reduced nickel content is 1% or less. Is promoted by mixing the sulfur-containing substance of the above, as the sulfur-containing substance, by adding pyrite, pyrrhotite, elemental sulfur, sodium sulfate, calcium sulfate and other sulfur-containing substances to the ore agglomerates, nickel. Is disclosed (Japanese Patent Publication No. 57-58421).

Further, 92 of laterite ore containing 0.25 to 1.5% by weight of nickel and 10 to 50% by weight of iron is used.
At a temperature of 0 to 1120 ° C., CO and CO ₂ are 60:
During reduction with a gas mixture containing a molar ratio of 40 to 100: 0, by adding sulfur compounds such as various sulfates and sulfides to the laterite ore, the growth of the ferronickel metal phase is performed during the reaction. A means has been proposed (Japanese Patent Laid-Open No. 59-118824) for promoting the recovery and thereby advantageously recovering nickel.

On the other hand, in many metal smelting processes, a countercurrent type heating furnace represented by a rotary kiln and a shaft furnace is used. When manufacturing this ferronickel concentrate, as described above, Such a rotary furnace is used (Japanese Patent Publication No. 57-58421).
Japanese Patent Publication No. 1-28555).

[0006]

However, for example, in such a rotary kiln, the raw material is gradually heated as it moves in the furnace as shown in FIG. 1, and reaches the maximum temperature near the heating burner to react. Is going to proceed. In FIG. 1, a rotary kiln 1 is rotated by rotation of a support roller 2, a raw material 4 is supplied from a supply port 3 on the upper end side of the kiln 1, and an outlet 5 on the lower end side is provided.
Combustion gas of the fuel is blown from the burner 6 for heating into the kiln, and the high temperature gas flows countercurrently with the raw material in the kiln to heat it, and the vicinity of the exit 5 of the kiln becomes the maximum temperature range 7. The ferronickel 8 and slag generated by the heating reaction are discharged from the outlet 5, and the exhaust gas 9 is discharged from the vicinity of the supply port 3.

When dry smelting nickel oxide ore using such a countercurrent heating furnace, even if a sulfur source is added to the raw material and charged into the furnace as described above, the raw material is heated gas. Since it flows countercurrently, sulfur is evaporated and decomposed before reaching the maximum temperature range where sulfur works most effectively, resulting in many losses. It is considered that such a loss proceeds by the following reaction.

S (S) → S (vap.) S + O ₂ → SO ₂ FeS + 3 / 2O ₂ → FeO + SO ₂ CaSO ₄ + SiO ₂ → CaSiO ₃ + SO ₃ CaSO ₄ → CaO + SO ₃ And the sulfur concentration in the raw material in the maximum temperature range In order to achieve the necessary and sufficient values, it was necessary to increase the basic unit of sulfur addition.

An object of the present invention is to reduce the sulfur addition basic unit by improving the yield of the sulfur source added to improve the yield of nickel.

[0010]

The inventors of the present invention have found that when a sulfur source is added to a raw material in a countercurrent heating furnace, the vaporized sulfur source is discharged from the furnace without passing through the maximum temperature range described above. Therefore, the present invention has been accomplished based on the idea that all the added sulfur can be involved in the reaction if all the added sulfur sources pass through the maximum temperature range.

That is, the present invention is a method for dry smelting nickel oxide ore using a countercurrent heating furnace, in which a fuel containing or blended with a sulfur source is burned with a heating burner to produce sulfur as a smelting raw material. A sulfur source addition method in nickel oxide ore smelting, characterized by adding a source,
The above objective was achieved. The raw material used in the present invention is a mixture of nickel ore, carbonaceous material and lime, which has not been added with sulfur as in the prior art described above, and is briquette. The conventionally known conditions such as the mixing method and the mixing ratio of these can be applied as they are. The type of carbonaceous material is also the same as the conventional one except that sulfur is not particularly included. Then, this raw material briquette is charged into a countercurrent type heating furnace such as a rotary kiln and heated and reduced.

In the present invention, a burner fuel that heats the raw material contains a sulfur source or is mixed with a sulfur source. The sulfur concentration in the fuel is preferably 1 to 5 wt% for both coal and heavy oil. The fuel may be a gas fuel such as CO gas. As coal, pulverized coal is practically used, but such pulverized coal and heavy oil are commercially available with reduced sulfur content in order to prevent pollution, so when using these, the sulfur concentration is A sulfur source is added or blended so as to fall within the above range. As the sulfur source contained in or added to the fuel, all those known in the prior art can be used.

When actually using coal or heavy oil, it is better to blend several kinds of heavy oil or pulverized coal rather than simply selecting and using one having an appropriate amount of sulfur. The criteria at that time are the amount of sulfur, the amount of heat generation, the amount of volatile matter (which affects the ignition temperature), the amount of phosphorus (which should be kept low so as not to adversely affect the properties of stainless steel), and the ash content (the lower the better). Yes, decide the compounding ratio considering the whole. The content of these ash content and the like is preferably, for example, a phosphorus content of 0.01 wt% or less and an ash content of 10 wt% or less.

Further, as the sulfur basic unit, 0.5 to 2.
A range of 5 kg / t-ore is preferred. If the sulfur unit is small, the nickel yield will not be sufficiently improved, and if it is too large, S
This causes generation of O _x .

[0015]

The sulfur source in the fuel is oxidized simultaneously with the combustion of the fuel to generate SO _x , which comes into contact with the raw material which has reached the maximum temperature. At this time, SO ₂ and the like cause the following reactions with the high temperature carbon in the raw material, are absorbed in the raw material, and can be maintained at a sulfur concentration necessary and sufficient to improve the nickel recovery rate at the maximum temperature. .

C + SO ₂ → S + CO _{2 The} sulfur added to the fuel here is about 1/3 of that.
There enters Ferro in the nickel product, about 1/3 enters the slag, but about one third remaining is discharged enters the exhaust gas as SO _x, SO _x in the flue gas is addition of water Alternatively, since it is removed as H ₂ SO ₄ and H ₂ SO ₃ by washing, no harmful gas is discharged.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 140 kg / t of coal and 70 kg / t of lime were added to and mixed with nickel oxide ore having the chemical composition shown in Table 1 to form a briquette. This briquette was placed in a rotary kiln having a diameter of 3.6 m and a length of 70 m and heated and reduced.
The maximum temperature range in the rotary kiln is 1380 ℃
Held at the temperature of. Then, with a heating burner, sulfur concentration is 1.5 wt%, phosphorus concentration is 0.007 wt%, and ash content is 6.0.
The pulverized coal adjusted to wt% was burned to heat the raw material and add the sulfur source. Table 2 shows the basic unit of sulfur addition, the sulfur yield and the nickel yield at this time. Example 2 140 kg / t of coal and 70 kg / t of lime were added to and mixed with nickel oxide ore having the chemical composition shown in Table 1 to form a briquette. This briquette was placed in a rotary kiln having a diameter of 3.6 m and a length of 70 m and heated and reduced.
The maximum temperature range in the rotary kiln is 1380 ℃
Held at the temperature of. Then, heavy oil having a sulfur concentration of 1.5 wt% and an ash content of 0.02 wt% (phosphorus is not contained) was burned with a heating burner to heat the raw material and add a sulfur source. Table 2 shows the basic unit of sulfur addition, the sulfur yield and the nickel yield at this time. Comparative Example 1 140 kg / t of coal, 70 kg / t of lime, and 0.8 kg / t of powdered sulfur were added to and mixed with nickel oxide ore having the chemical composition shown in Table 1 to form a briquette. This briquette was placed in a rotary kiln having a diameter of 3.6 m and a length of 70 m and heated and reduced. The maximum temperature range in the rotary kiln was maintained at a temperature of 1380 ° C. Then, the pulverized coal having a sulfur concentration of 0.2 wt% or less was burned with a heating burner to heat the raw material. In this case, the pulverized coal used had a low sulfur concentration so that it would not contain sulfur. Table 2 shows the basic unit of sulfur addition, the sulfur yield and the nickel yield at this time. Comparative Example 2 For nickel oxide ore having the chemical composition shown in Table 1, 140 kg / t of coal, 70 kg / t of lime, and F
Briquette was prepared by converting eS to sulfur and adding 0.8 kg / t and mixing. This briquette has a diameter of 3.6 m and a length of 70 m.
It was charged in a rotary kiln and heated and reduced. The maximum temperature range in the rotary kiln was maintained at a temperature of 1380 ° C. And, with the burner for heating, the sulfur concentration is 0.2w
The raw material was heated by burning pulverized coal of t% or less. The pulverized coal used had a low sulfur concentration as in Comparative Example 1. Table 2 shows the basic unit of sulfur addition, the sulfur yield and the nickel yield at this time. Comparative Example 3 For nickel oxide ore having the chemical composition shown in Table 1, 140 kg / t of coal, 70 kg / t of lime, and C
ASO ₄ was changed to sulfur and 0.8 kg / t was added and mixed to form a briquette. This briquette has a diameter of 3.6 m and a length of 7
It was put into a 0 m rotary kiln and heated and reduced. The maximum temperature range in the rotary kiln was maintained at a temperature of 1380 ° C. Then, the sulfur concentration was reduced to 0.
The raw material was heated by burning pulverized coal of 2 wt% or less. The pulverized coal used had a low sulfur concentration as in Comparative Example 1. Table 2 shows the basic unit of sulfur addition, the sulfur yield and the nickel yield at this time.

[0018]

[Table 1]

[0019]

[Table 2]

From the above results, in the present invention, the sulfur yield is remarkably improved as compared with the prior art, and as a result, when the same sulfur unit is used, nickel can be recovered in good yield as shown in Table 2. Further, this means that when the nickel recovery rate is set to be the same, the sulfur consumption rate is considerably reduced as compared with the conventional technique.

[0021]

According to the present invention, nickel can be recovered in good yield with a smaller amount of sulfur unit compared with the prior art. Further, by reducing the sulfur unit consumption, it is possible to reduce the amount of harmful SO _x generated.

[Brief description of drawings]

FIG. 1 shows a schematic view of a rotary kiln used for producing a ferronickel concentrate.

[Explanation of symbols]

 1 Rotary Kiln 2 Support Roller 3 Supply Port 4 Raw Material 5 Outlet 6 Heating Burner 7 Maximum Temperature Range 8 Ferronickel 9 Exhaust Gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Nakajima Takashi Nakajima 413 Sutsu, Miyazu City, Kyoto Prefecture Nippon Metallurgical Industry Co., Ltd. Oeyama Factory Co., Ltd. Nihon Metallurgical Industry Co., Ltd.

Claims (1)

[Claims] 1. A method for dry smelting nickel oxide ore using a countercurrent heating furnace, in which a fuel containing or blended with a sulfur source is burned with a heating burner to add the sulfur source to a smelting raw material. A method for adding a sulfur source in nickel oxide ore smelting, which is characterized by the above.