JPH10265815A - Operation of smelting reduction furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably recover valuable metal from moisture-containing sludge containing metallic oxide and/or metallic hydroxide. SOLUTION: A vertical furnace having plural tuyeres for blowing high temp. air into a packing layer of the carbon base solid reducing agent and arranged in at least two steps, is used and the moisture-containing powdery and granular metallic oxide and/or metallic hydroxide-containing raw material is injected from at least the upper step tuyere and enriched oxygen quantity for blowing from the upper step tuyere is changed according to the moisture content in the raw material. By this method, the moisture content in the raw material can effectively correspond to about 40%, and the temp. at the front of the tuyere is secured, and the operation is stably executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a metal oxide and / or metal oxide.
Alternatively, the present invention relates to a method for recovering valuable metals by melting and reducing hydrous sludge containing metal hydroxide.

[0002]

2. Description of the Related Art The form of metal oxides such as iron ore and chromium ore as underground resources is mostly powdery rather than lump, and it is expected that powdery ore will further increase in the future. You. Direct use of such an ore as it is in powder form is advantageous in terms of energy saving and production cost. In addition, dust and sludge generated in steelworks and the like often contain valuable metals, but those that have been discarded without a treatment method or that have been reused have high disposal costs, or Some have problems such as a low recovery yield. Most of the solid content of these dusts and sludges is in the form of powder and granules, and if it can be directly treated, it is advantageous in energy saving, production cost, and environmental protection.

A smelting reduction furnace of the vertical furnace type is disclosed in JP-B-59-18452 as a method of smelting and reducing such a powdery oxide-containing raw material. According to the report, the powdery raw material was blown into the vertical furnace together with the high-temperature air from at least the upper tuyere of the upper and lower two-stage tuyeres for blowing high-temperature air installed at the lower part of the furnace, and charged into the furnace. It is characterized by burning and reducing carbonaceous materials. In a vertical furnace having upper and lower tuyeres, a high temperature is generated by burning the carbon material forming a packed bed between the upper and lower tuyeres. Therefore, the raw material blown from the upper tuyere is heated and melted,
During the dropping of the packed bed, metal and slag in a molten state directly reduced by the solid carbon material are generated and accumulated at the furnace bottom.

[0004] In the above-mentioned technique, since the amount of heat absorbed by reduction during the reduction between the upper and lower tuyeres is large, it causes dropping of the melt and causes operation trouble. Injects air and oxygen-enriched air.
In a vertical smelting reduction furnace filled with carbon material, the generated melt is stored in the furnace body and discharged outside the furnace.Therefore, in order to maintain stable operation without tuyere damage or cooling, it is necessary to use a blast furnace. Similarly,
An appropriate melt temperature must be ensured. As a stable operation method in a vertical smelting reduction furnace filled with carbonaceous material, see
JP-A-4-213 and JP-B-3-59966 are disclosed. Japanese Unexamined Patent Publication (Kokai) No. 64-216 discloses a technique for determining the thermal condition between the upper and lower tuyeres according to the conditions of the apparatus, and Japanese Patent Publication No. 3-59966 controls the blowing condition by the temperature difference of the tuyere cooling water. It is.

[0005]

When a sludge containing a large amount of water is blown into a vertical smelting reduction furnace filled with carbonaceous material, the content solidifies due to insufficient heat or a decrease in the temperature in front of the tuyere. Cooling of the hearth occurs. Especially when the tuyere has one stage like a blast furnace, there is no heat compensation function below the tuyere.
A large amount of water cannot be blown. In contrast, 2
In a vertical smelting reduction furnace having a stage tuyere, since a heat compensation effect from the lower stage tuyere can be expected, smelting may be possible even if a large amount of water is blown.

[0006] However, although the above two stable operation methods provide thermal conditions between the upper and lower tuyeres, they do not take into account raw materials containing water and do not consider the treatment of hydrous sludge.
Not enough conditions. An object of the present invention is to provide a method for stably treating a hydrous sludge containing a metal oxide and / or a metal hydroxide.

[0007]

SUMMARY OF THE INVENTION According to the present invention, water is removed by using a vertical furnace having a plurality of tuyeres provided in at least two upper and lower stages for blowing high-temperature air into a packed bed of a carbon-based solid reducing agent. This is a method for operating a smelting reduction furnace for producing a molten metal by injecting at least an upper tuyere from a powdery metal oxide and / or metal hydroxide-containing raw material containing the same. In this case, change of the upper tuyere blow-enriched oxygen amount according to the moisture content in the raw material,
Means such as a change in the blast temperature and a change in the blast volume may be used, but the change in the blast temperature and the blast volume can effectively cope with the water content in the raw material up to about 5%, and more. It is preferable to change the oxygen-enriched amount in order to secure the tuyere pre-temperature at the water content of.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a vertical smelting reduction furnace having upper and lower tuyeres and in which a raw material containing powdered metal oxide and / or metal hydroxide is blown from at least the upper tuyeres, The high temperature is generated by burning the carbon material forming the filling layer between the mouths by the heated air. The raw material blown from the upper tuyere is heated and melted, and is dropped directly by the solid carbon material to form molten metal and slag while dropping the packed bed. The direct reduction reaction of oxides and hydroxides in the raw material with solid carbon is a reaction involving a large endotherm,
This heat absorption is compensated for by blowing air from the lower tuyere.

[0009] If the amount of heat supplied between the upper and lower tuyeres is insufficient, the reduction reaction of oxides and hydroxides in the raw material becomes slow,
The melt is dropped below the lower tuyere before the reduction reaction is completed. As a result, the remaining reduction reaction occurs below the lower tuyeres without thermal compensation. Since the reduction reaction involves a large heat absorption, if the reduction reaction occurs below the lower tuyere, heat is removed from the melt or coke in the hearth, which causes cooling. By increasing the amount of heat supplied between the upper and lower tuyeres and raising the temperature in this region, the reduction reaction can proceed sufficiently and the cooling of the hearth can be prevented.

[0010] Further, if the theoretical combustion temperature (TFT) before the tuyere of the tuyere into which the raw material is blown drops, the blown raw material does not melt at once, but rises in the furnace together with the gas and is discharged from the furnace top. . Further, since the melting in front of the injected tuyere is delayed, the reduction between the upper and lower tuyeres does not completely end. A raw material containing moisture requires an extra amount of heat for smelting as much as the drying of water and the reaction between coke and water, as compared with a dried raw material. In addition, since an endothermic reaction occurs in the raceway in front of the material injection tuyere, the TFT is reduced. This shortage of heat input and the decrease in TFT can be compensated in principle by increasing the amount of air blown per blown material, increasing the temperature of blown air, and increasing the amount of oxygen enriched in blown tuyere per blown raw material. .
Effects of each factor on the compensation of the heat input and the compensation of the TFT are examined from the heat balance in the space in front of the tuyere, and are shown in FIGS. Here, Δ indicates the operating point of the example, and □ indicates the operating point of the comparative example. The operating conditions when no water is contained are as described in Example 1 of Table 1 below, and when water is contained, the enriched oxygen amount, the blast temperature, and the blast amount in each of FIGS. Only one of them was changed, and the other conditions remained constant. As for the raw material supply amount, the raw material injection amount on a dry basis was fixed. The heat input in the heat input / heat required for smelting is the sum of the sensible heat of the blast and the coke combustion up to CO. It is the sum of sensible heat.

Either method can compensate for the amount of heat input and the temperature before the blowing tuyere. However, in reality, it is difficult to industrially achieve a blowing temperature exceeding 1300 ° C. Therefore, as shown in FIG. 2, it is possible to cope with only up to 5% moisture in the raw material when the blowing temperature is increased. Further, in the case of responding by the amount of air blow, in FIG. 3, a line with a constant TFT and a line with a constant heat input amount / a constant heat required for smelting are largely apart. This indicates that if the blowing rate is increased to keep the TFT constant, the amount of heat input / the heat required for smelting becomes excessive. Considering the heat balance of the entire furnace, the furnace top gas temperature rises too much and the operation starts. Indicates that it cannot be done. When responding with the enriched oxygen amount to the injection tuyere,
FIG. 1 shows that the amount of oxygen enrichment at a fixed TFT and the amount of heat enrichment / oxygen enrichment at a constant required smelting heat are almost the same, and it can be seen that a TFT can be secured without excessive heat input. Further, compared to the case where there is no moisture in the raw material, the amount of enriched oxygen required at 20% moisture is about 5 times, and the amount of oxygen enriched at 40% moisture is about 10 times, all of which are feasible values. . Therefore, it can be said that it is most realistic to cope with the increase in the moisture in the raw material by increasing the amount of oxygen enriched in the blowing tuyere. Here, the blowing temperature, the blowing amount, and the enriched oxygen amount are individually changed and described. However, it is natural that the blowing temperature and the blowing amount may be additionally increased with the increase of the enriched oxygen. is there.

Further, as can be seen from FIGS. 1 to 3, regardless of the amount of oxygen enriched, the temperature of the blown air, and the amount of blown air, the conditions for securing the TFT are: heat input / heat required for smelting. Conditions to be stricter. In other words, it can be said that it is necessary to change the amount of oxygen enriched in the blowing tuyere in accordance with the moisture in the raw material so as to secure the TFT of the blowing tuyere.

Since the hydrous sludge is very fine particles and a hydroxide, it has high hydrophilicity and is very difficult to dehydrate. Therefore, a large amount of energy is required for drying. On the other hand, when smelting sludge while containing sludge, the same energy is required for drying, but there is an advantage that CO and H ₂ are generated by the reaction with coke and a high calorie gas can be recovered. .

Examples of hydrous sludge include sludge containing iron, chromium, nickel, zinc, etc. generated during metal working, sludge similarly containing oil, and wet-collected dust. All of them can be treated without any problem. Can be. In the present invention, the TFT can be obtained from the heat balance before the blowing tuyere. The heat balance will be described. First, as for O ₂ (Nm ³ / min) from ventilation, enriched oxygen, and moisture, B = 0.21 BV + E. O ₂ ^T + (11.2 / 1800
0) BV · BM O ₂ (Nm ³ / min) from water in the raw material is: E = W _pow × ｛((% MO) / 100) × M _O / M _MO +
((% MOH) / 100) × M _O / M _MON ｝ × β +
((% H ₂ O) / 100) × (16/18) × α｝ ×
(22.4 / 32) H ₂ (Nm ³ / min) from moisture in the raw material is: F = W _pow × ｛Σ ((% MOH) / 100) × (M _H /
M _OH ) × β + ((% H ₂ O) / 100) × (2/18)
× α｝ × (22.4 / 2) H ₂ O (g) existing in front of the tuyere as water vapor (kmol
/ Min) is: G = W _pow × ((% H ₂ O) / 100) × (1/18)
× (1-α) Heat input is (1) sensible heat of blast + (2) sensible heat of coke + (3)
C is the heat of combustion.

(1) Sensible heat of blast A ₁ = BV × (0.362BT-24.2) + (primary EO ₂ ) × (0.373BT-26.1) + (BV ·
(BM / 1800) × (0.473BT-56.9) (2) Coke sensible heat A ₇ = (B + E) × (2 / 22.4) × 12 × (0.3
65 × 0.75 × TFT + 41.2) (3) C combustion heat A ₂ = {B- (11.2 / 18000) BV · BM)}
× {(2 × 12) /22.4} × (0.112BT + 2
391) Heat output is (4) sensible heat of Bosch gas + (5) heat of decomposition of blast moisture + (6) heat of evaporation and decomposition of water in raw material + (7) heat of reduction of raw material + (8) sensible heat of raw material moisture .

(4) Sensible heat of Bosch gas A ₈ = 0.79 × BV × (0.390 × TFT-67.1) + F × (0.374TFT-70.2) + (B + E) × 2 × (0 .393TFT-70.1) + G × (0.473TFT-56.9) = ｛0.79 × 0.39 × BV + 0.374 × (F + (BV · BM / 1000) × (22.4 / 18) + (B + E) × 2 × 0.393 + G × 0.473｝ × TFT- ｛0.79 × 67.1 × BV + 70.2 × (F + (BV · BM / 1000) × (22.4 / 18) + ( B + E) × 2 × 70.1 + G × 56.9｝ (5) Heat of decomposition of blast moisture A ₃ = (BV · BM / 1000) × (0.066BT +
3238) (6) Heat of evaporation and decomposition of water in the raw material A ₄ = W _pow × ((% H ₂ O) / 100) × ｛539+
(0.066BT + 3238) × α} (7) raw material reducing heat _{A 5 = W pow × {(} % MO) / 100 × Q MO + (% MO
H) / 100 × Q _MOH ｝ × β (8) Sensible heat of raw material moisture A ₆ = W _pow × γ × TFT + W _pow × ((% H ₂ O) /
100) × 100 The thermal balance is A ₁ + A ₇ + A ₂ = A ₈ + A ₃ + A ₄ + A ₅ + A ₆ . From this, the TFT is obtained as follows.

P = A ₁ + A ₂ −A ₃ −A ₄ −A ₅ + (B + E) × (2 × 12 / 22.4) × 41.2−0.79 × 67.1 × BV + 70.2 × (F + (BV · BM / 1000) × (22.4 / 18) + (B + E) × 2 × 70.1 + G × 56.9−W _pow × ((% H ₂ O) / 100) × 100 Q = 0.79 × 0.39 × BV + 0.374 × (F + (BV · BM / 1000) × (22.4 / 18) + (B + E) × 2 × 0.393 + G × 0.473 + W _pow × γ− ( B + E) × (2 × 12 / 22.4) × 0.365 × 0.75 TFT = P / Q (Explanation of symbols) BV: Air flow (Nm ³ / min) EO ₂ ^T : Total enriched oxygen the amount (Nm ³ / min) (primary E.O _2): amount of oxygen enriched upstream of a hot-air oven (Nm ³ / min) BM: moisture in the air blowing _{^{(g / Nm 3) W pow}} : Raw material blowing velocity at Raibesu (kg / m
in) M _O / M _MO : weight ratio of oxygen in metal oxide (−) M _H / M _MO : weight ratio of hydrogen in metal oxide (−) M _O / M _MOH : weight ratio of metal hydroxide Weight ratio of oxygen (-) _MH / _MMOH : Weight ratio of hydrogen in metal hydroxide (-) (% MO): Content of metal oxide in raw material (%) (% MOH): In raw material (% H ₂ O): Water content (%) with respect to the raw material on a dry basis BT: Blast temperature (° C.) TFT: Theoretical combustion temperature (° C.) B: Blast and blow Oxygen content from moisture and enriched oxygen (Nm ³ /
min) E: oxygen amount from moisture in raw material (Nm ³ / min) F: hydrogen amount from moisture in raw material (Nm ³ / min) G: water vapor amount in front of tuyere (Nm ³ / min) A ₁ : blowing sensible (kcal / min) A _2: carbon combustion heat (kcal / min) A _3: blowing moisture degradation heat (kcal / min) A _4: blower in water evaporation, heat of decomposition (kcal / min) A _5: material reducing heat (kcal / min) a _6: feed water sensible (kcal / min) a _7: coke sensible (kcal / min) a _8: Bosch gas sensible (kcal / min) Q _MOH: metal oxides Heat of reduction (kcal / kg) Q _MO : Heat of reduction of metal hydroxide (kcal / kg) α: Moisture decomposition rate in front of tuyere (−) β: Reduction rate of raw material in front of tuyere (−) γ: Raw material specific heat (kcal / kg) where α and β are operating conditions and equipment Since different from the matters which should seek appropriate values per the implementation.
In the following examples, α = 0.5, β = 0.
A value of 4 was employed.

[0018]

The following describes an embodiment in a vertical smelting reduction furnace having a metal production amount of 8 t / d. Examples are shown in Table 1 and Comparative Examples are shown in Table 2. Each operating point is shown in Figure 1
In FIG. 3, they are indicated by 〇 and □. The raw material is pickling sludge generated from a rolling mill and contains hydroxides such as iron, chromium, and nickel. The operating conditions serving as standards for smelting a raw material that does not contain water are: blowing air at 16.7 Nm ³ / min, oxygen enrichment amount at 2 Nm ³ / min, blowing temperature at 800 ° C., and metal generation amount at 8 t / d. The heat input amount in the heat input amount / heat required for smelting is the sum of the sensible heat of blast and the heat of coke combustion to CO, and the heat required for smelting is the heat of reduction of the raw material, the evaporation of water, the heat of decomposition,
It is the sum of the sensible heat of the generated melt. In each operation, the raw material was blown from the upper tuyere.

Example 1 is a case where water is not contained in the raw material, which is a standard operating condition. In Example 2, the water content in the raw material was 5
%, The blow temperature was increased to 1250 ° C, and the theoretical combustion temperature of the injection tuyere and the heat input / heat required for smelting were equal to or higher than the standard conditions. No problems were found in the operation such as brightness and tapping temperature. However, since the blowing temperature could not be increased any more, the operation with a water content of 5% or more could not be performed. In Example 3, the amount of air blown was 37.4 Nm ³ with respect to the water content of 5%.
/ Min, and the theoretical combustion temperature of the injection tuyere and the heat input / heat required for smelting are equal to or higher than the standard conditions, and the brightness and tapping temperature in front of the tuyere There was no problem with the operation. However, when the water content was 5% or more, it was necessary to further increase the amount of air to secure the TFT, and the furnace top gas temperature exceeded 1100 ° C., so that it was judged that the operation could not be continued. Examples 4 to 7
Means that the upper-stage tuyere-enriched oxygen amount is 2.6, 4.6, and 7. respectively with respect to the water content of 10, 20, 30, and 40% in the raw material.
1, 10.5 Nm ³ / min, and the operation was increased. In each case, the TFT secured 1700 ° C., and the heat input / heat required for smelting exceeded the standard conditions. No problems were found in the operation such as tapping temperature and tapping temperature.

In Comparative Examples 2 to 7, the blast temperature (Comparative Example 2), the blast amount (Comparative Example 3), and the upper tuyere were adjusted in accordance with the moisture content in the raw material so that the heat input amount / heat required for smelting matched the standard conditions. Although the enriched oxygen amount (Comparative Examples 4 to 7) was increased, the operation was stopped because the upper tuyere TFT was lower than 1600 ° C and the front of the tuyere became dark during the operation.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

According to the present invention, a furnace containing water is blown into a vertical furnace having a two-stage tuyere, and the amount of oxygen-enriched oxygen is changed so as to secure a theoretical combustion temperature in accordance with the amount of water. Valuable metals can be recovered without cooling on the floor.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the moisture in the raw material and the upper-stage tuyere-enriched oxygen amount necessary for keeping the theoretical combustion temperature and the heat input amount / the heat required for smelting constant.

FIG. 2 is a graph showing the relationship between the moisture in the raw material necessary for keeping the theoretical combustion temperature and the heat input / the heat required for smelting constant, and the blowing temperature.

FIG. 3 is a graph showing the relationship between the moisture in the raw material and the amount of air blown to maintain the theoretical combustion temperature and the heat input / the heat required for smelting constant.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Miyagawa 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel (72) Inventor Hiroshi Itaya 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Research Institute

Claims (2)

[Claims] In a vertical furnace having a plurality of tuyeres provided in at least two upper and lower stages for blowing high-temperature air into a packed bed of a carbon-based solid reducing agent, a powdery metal oxide containing water and / or A method for operating a smelting reduction furnace, wherein a molten metal is produced by blowing a metal hydroxide-containing raw material from at least the upper tuyere. 2. The method according to claim 1, wherein the amount of oxygen enriched is changed in accordance with the water content of the powdery metal oxide and / or metal hydroxide-containing raw material blown from the tuyere to secure the tuyere pre-temperature. The method for operating a smelting reduction furnace according to claim 1.