JP2000129369A - Method for controlling reducing degree in copper flash smelting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the degree of reduction in a furnace by keeping coke quantity staying in a settler part to always constant, in a flash smelting furnace operation which injects copper concentrate, coke, flux and the other charging material together with oxygen-enriched air by using a concentrate burner from the top part of a shaft. SOLUTION: In the case of changing the operational condition during operation of the flash smelting furnace, a convergent calculations of the copper grade in a matte and the combustion ratio of the coke, are executed from a thermal balance and an oxygen balance in the shaft 2. Based on the obtd. combustion ratio of the coke, the feedback is executed so that the coke quantity staying in a slag 6 layer in the settler 3 becomes constant, and the supplying quantity of the coke from the concentrate burner is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copper smelting furnace which supplies copper concentrate, coke, flux and other charges together with oxygen-enriched air from a top of a shaft provided in a flash furnace using a concentrate burner. The present invention relates to a method for controlling a degree of reduction in a smelting furnace.

[0002]

2. Description of the Related Art Conventionally, a copper smelting flash furnace comprising a shaft, a settler and an uptake (hereinafter referred to as a flash furnace).
Then, using a concentrate burner from the top of the shaft, copper sulfide concentrate (hereinafter referred to as copper concentrate) obtained by blending copper concentrates with different production areas so that the composition of Cu, S, etc. is as uniform as possible Flux and other charges and fuel such as heavy oil, pulverized coal or coke are blown into the shaft together with preheated oxygen-enriched air, and the heat of combustion of the fuel is converted into the heat of reaction by oxidation of copper concentrate, which accounts for the majority of the heat source. In addition, dissolution of copper concentrate, etc. and oxidizing and smelting in the shaft are performed, and a mat consisting mainly of copper sulfide (Cu ₂ S) and iron sulfide (FeS) and a silicate of iron oxide are mainly used. Produces a slag that is a solution. At this time, the sulfurous acid gas generated by the reaction in the setter is introduced into a sulfuric acid factory via an uptake, and is used as a raw material for sulfuric acid production.

[0003] As described above, the flash smelting furnace mainly uses the heat of oxidation reaction of the raw material ore such as copper concentrate or the like, but in order to make up for the insufficient calorific value, it has conventionally burnt heavy oil as fuel. However, with the soaring price of heavy oil, pulverized coal was first actively used as an alternative solid carbonaceous material,
In addition, fuel conversion from pulverized coal to coke has been promoted, and the operation of the flash smelting furnace using 100% coke has now started.

For example, Japanese Unexamined Patent Publication (Kokai) No. 59-50132 discloses a copper smelting flash furnace in which copper concentrate, flux and other charges are charged to produce mats and slag, in order to maintain the operating temperature in the furnace. Discloses a method for operating a copper smelting flash smelting furnace in which powdery coke is charged as an auxiliary fuel.

[0005]

According to Japanese Patent Application Laid-Open No. 59-50132, when fine or granular coke is supplied from a concentrate burner, coke floats on the surface of the setter in the furnace. It is said that stable operation can be obtained by controlling furnace conditions and charging amount so that the amount does not tend to increase.
The method and the burn rate are not described in detail.

[0006] The coke staying in the slag layer in the settler affects the degree of reduction in the furnace, for example, magnetite (Fe)
₃ O ₄ ) to reduce the amount of copper loss into the slag and improve the laying. This coke has the effect of burning the slag over a wide area by burning it in the slag layer, and keeping and heating the underlying mat layer. However,
The combustion rate of the charged coke in the shaft is affected by various parameters such as the type of raw ore used, the amount charged, and the oxygen concentration in the oxygen-enriched air, and a certain amount of coke is loaded on the shaft. Even if it enters, the amount of coke that reaches the slag layer and contributes to the reduction of the slag varies widely. For this reason, for example, magnetite is not reduced due to lack of coke, and a problem has arisen in that the amount of mat that can be accumulated in the settling portion, that is, the capacity of the mat pool decreases due to the magnetite being deposited on the hearth in contact with the mat layer. Conversely, the rise was eliminated by excessive coke, and the coating that protected the hearth brick was lost, causing troubles such as wear of the hearth brick. As described above, coke has a great effect on the degree of reduction in the furnace, and it is more important to maintain a constant amount of coke remaining in the molten slag layer in the setter than to charge a fixed amount of coke to the shaft. is there.

[0007] The present invention provides a method for controlling the degree of reduction in the furnace in a copper smelting flash smelting furnace capable of always maintaining a constant amount of coke stagnating in the setler portion of the coke charged in the shaft of the flash smelting furnace. It is intended to provide a method.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for enriching copper concentrate, coke, flux and other charges using a concentrate burner from the top of a shaft provided in a flash smelting furnace. In the method for controlling the degree of reduction in the furnace of a copper smelting flash furnace blown with air, mixing during operation of the flash furnace, raw material ore charge, oxygen concentration in oxygen-enriched air, copper grade of mat, mat temperature When changing operating conditions, such as changing the operating conditions, the convergence calculation of the copper grade of the mat and the coke combustion rate is performed from the heat balance and oxygen balance of the shaft, and the amount of coke staying in the molten slag layer in the setter is calculated based on the coke combustion rate And controlling the amount of coke supplied from the concentrate burner so that the amount of coke staying in the molten slag layer in the setter becomes constant by feeding back the excess and deficiency with the target coke amount. A method of controlling a furnace degree of reduction in the copper smelting flash furnace, characterized.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a flash smelting furnace 1 includes a cylindrical shaft 2, a settler 3, and an uptake 4, and is supplied from a concentrate burner 9 provided at the top of the shaft 2. Dry powdery copper concentrate, coke, flux and other charges are introduced into the shaft 2 together with the hot air preheated by mixing air blown from the furnace top duct 10 with oxygen produced by the oxygen plant. I will Note that a gas obtained by mixing air and oxygen produced by an oxygen plant is generally called oxygen-enriched air.

[0010] Sulfur and iron in the copper concentrate are deposited in the shaft 2.
Reacts with flux containing oxygen and silicic acid as the main component,
Main composition is Cu_TwoMelt mat 5 made of S, FeS and FeO,
Fe_ThreeO _Four, SiO_TwoTo produce a molten slag 6 consisting of
It falls on the setler 3 and is stored. In this setter 3
Coal supplied from the concentrate burner 9 is applied to the six layers of molten slag.
Most of the dust remains unburned. This retained coke
Is magnetite (Fe_ThreeO_Four) To reduce copper loss in slag
Of magnetite on the hearth with reduced loss
(Set up), melting in setter 3
Reduce the amount of coke staying in the six layers of slag
It is important to stabilize the degree.

Therefore, in the present invention, the convergence calculation of the copper grade and the coke burning rate of the mat is performed based on the heat balance and the oxygen balance in the shaft 3, and the coke amount obtained based on the coke burning rate is used as the concentrate burner. The amount of coke charged into the shaft 2 is controlled so that the amount of coke staying in the six layers of molten slag in the settler 3 is kept constant by feeding back to the amount of coke supplied from 9.

The temperature of the molten mat 5 and the molten slag 6 accumulated in the setter 3 immediately below the shaft 2 is about
The temperature is 1200 ° C. and about 1250 ° C., and the molten mat 5 is intermittently discharged from the furnace through a plurality of mat holes 7 provided at the bottom of the furnace. On the other hand, the molten slag has a layer thickness of 50 cm of the molten slag 6.
Is continuously discharged out of the furnace from one slag hole 8 arranged at the middle position in the height direction of the stage and on the uptake 4 side of the setter 3. The temperature of the exhaust gas in the setter 3 is about 1300 ° C., and is guided to a boiler (not shown) via the uptake 4 for cooling, and the steam generated in the boiler is used for a turbine generator to generate power. .

In order to operate the flash smelting furnace, as shown in FIG. 2, ore such as copper concentrate, copper slag and flux, and fumes are analyzed and obtained, and the ore composition is obtained. The target copper grade (%) of the mat to be produced is determined, and from this value, the S% and Fe% of the mat and the copper grade of the slag produced simultaneously are estimated. In addition, the amount of Fe
The amount ratio (Fe / SiO ₂ ) is set, and the mat amount, the slag amount, and the flux amount are calculated by material amount balance calculation. Also,
The amount of oxygen required for the following reactions of Fe and S required for the production of the mat and the slag is obtained, and the amount of exhaust gas containing SO ₂ gas resulting from the reaction with the ore is calculated.

2. CuFeS ₂ = Cu ₂ S + FeS + FeS ₂ FeS ₂ + O ₂ = FeS + SO ₂ 2FeS + 3O ₂ + SiO ₂ = 2FeO · SiO ₂ + 2SO ₂ 3FeS + 5O ₂ = Fe ₃ O ₄ + 3SO ₂ On the other hand, the reaction temperature and the mat and slag Set the target mat temperature which is considered to be most desirable for operation from the viscosity at the time of separating, extracting the mat or slag from the furnace, and the like. The temperature of a reaction product such as a mat or slag at the reaction end position of the shaft 2 is about 1350 ° C., which is generally assumed to be about 150 ° C. higher than the target mat temperature of the setter section. The amount of coke required to maintain the reaction temperature of the shaft 2 and to stay in the six layers of molten slag is determined by the amount of heat input determined from the reaction heat of the raw ore, coke combustion heat, blast air and other sensible heat. It is determined by calculation so that the heat balance with the heat output can be obtained. As for the heat output, the sensible heat of the molten mat 5 and the molten slag 6, the radiant heat, the radiated heat (mainly due to the cooling water of the furnace wall water cooling jacket), the sensible heat of the exhaust gas and dust, and the like are obtained by calculation.

[0015] The charge, the blast air, and the oxygen produced by the oxygen plant are contained in the total amount of oxygen brought into the flash smelting furnace, the SO ₂ gas-containing exhaust gas including coke combustion exhaust gas, the molten mat 5, and the molten slag 6, respectively. The oxygen balance is calculated by obtaining the total amount of oxygen removed from the shaft including the oxygen content. That is, the amount of oxygen required for combustion of coke is calculated in consideration of the coke combustion rate, and the amount of oxygen required for mat and slag generation described above is added thereto, taking into account the oxygen content contained in the charge. The total amount of oxygen supplied to the shaft 2 is calculated. In calculating the degree of reduction in the furnace, these calculations are used as a basis, and the amount of coke supplied to the shaft 2, the amount of air supplied, and the amount of oxygen produced in the oxygen plant are adjusted based on the calculated values.

The amount of raw ore charged, blended brand, blending ratio
Rate, oxygen concentration in oxygen-enriched air, target copper products for production mats
(%), Target of output slag Fe / SiO_TwoRatio, target mat temperature
Respond to changes in operating conditions such as degree
As the coke combustion rate changes, the amount of coke supplied and
The amount of wind and air also changes. By the way, as shown in Table 1,
Shaft from concentrate burner 9 set on top of shaft 2
Ore, raw ore: 90t / h, coke: 2.1t / h, and
Air: 22000Nm ^Three/ h and oxygen from the oxygen plant: 10000
Nm^Three/ h and oxygen-enriched air (hereinafter also referred to as total air volume)
G): 32000Nm^Three/ h (O_Two: 44.5%).

[0017]

[Table 1]

A reaction product near the outlet of the shaft 2;
That is, the temperature of gas, molten mat, molten slag, etc.
1350 ° C. The gas in the setter 3, the temperature of the molten mat 5 and the temperature of the molten slag 6 were 1300 ° C., respectively.
The temperature is 1200 ° C. and 1250 ° C., and the amount of exhaust gas discharged from the uptake 4 via the setter ³ is 30129 Nm ³ / h. Heat balance in this case: [(heat input / heat output) x 100] is 100
%, And the oxygen balance: [(input oxygen / output oxygen) × 100] is 100%, and the operation calculation of the flash smelting furnace is performed based on these.

During operation of the flash smelting furnace 1 under these conditions,
To achieve a heat balance of 100% and an oxygen balance of 100%, a convergence calculation is performed until the matte copper grade and coke burn rate are constant, and the mat copper grade becomes 61.75% and coke burn rate becomes 35%. calculated. Therefore, the amount of coke staying in the molten slag 6 layer of the setter 3 after burning in the shaft 2 is 2.1 × (1.00−0.35) = 1.37 t / h, and this retained coke reduces the degree of reduction of the molten slag 6 and the like. Contribute.

Next, the operating conditions of the flash smelting furnace 1 were changed as shown in Table 2, and the raw ore from the concentrate burner 9 in the case of Table 1 was changed.
90t / h reduced to from 10t / h less 80t / h, coke while also supplying 2.1t / h, blowing of oxygen-enriched air, air: 23000Nm ³ / h, oxygen: 8500Nm ³ / h, total 31500N
m ³ / h (O ₂ : 44.5%).

[0021]

[Table 2]

The temperature of the reaction product in the shaft 2 is 1330 ° C.
The temperatures of the gas in the setter section, the molten mat 5 and the molten slag 6 are 1280 ° C., 1180 ° C., and 1230 ° C., respectively, which are 20 ° C. lower than the temperatures in Table 1. This is due to a decrease in the amount of ore charged and a decrease in the heat of reaction. The amount of exhaust gas discharged from the uptake 4 via the setter ³ is 29850 Nm ³ / h. In this case, to achieve a heat balance of 100% and an oxygen balance of 100%, convergence calculations were performed until the copper quality of the mat and the coke burning rate were constant, and the copper grade of the mat was 63.52% and the coke burning rate was 42. %
It was calculated to be. Therefore, the amount of coke staying in the six layers of molten slag of the setter 3 after burning in the shaft 2 is 2.1 × (1.00−0.42) = 1.22 t / h.

To secure the same amount of coke as in Table 1 in the six layers of molten slag in the setler 3, (1.37-1.22)
/0.42=0.4 t / h coke increase is required. This is fed back, 0.4 t / h is added, and coke of (2.1 + 0.4) = 2.5 t / h is supplied from the concentrate burner 9 to secure the amount of coke in the settler 3 and to achieve the necessary reduction. The stable operation of the flash smelting furnace based on the degree can be continued. At this time, since the amount of coke supplied as fuel increases, the temperature in Table 2 slightly increases.

The uplift of the bottom of the setter 3 due to an increase in magnetite due to insufficient control of the degree of reduction in the furnace has conventionally varied in the range of 0 to 30 cm. 10 due to correction of excess and deficit
cm and reduced to about cm. As a result, the capacity of the mat pool was stabilized, and the brick at the bottom of the furnace was damaged due to the loss of the coating of the high melting point magnetite near the rise of about 0 cm. Protected by coating, no damage.

[0025]

According to the present invention, during operation of a flash smelting furnace for copper smelting in which copper concentrate, coke, flux and other charges are blown together with oxygen-enriched air using a concentrate burner from the top of the shaft. Then, the convergence calculation of the copper quality of the mat and the coke burning rate is performed based on the heat balance and oxygen balance of the shaft, and based on the obtained coke burning rate, the amount of coke staying in the molten slag layer in the setter becomes constant. To control the coke supply amount.

As a result, it is possible to control to maintain the degree of reduction caused by the coke staying in the molten slag layer in the setler at a constant level, and to reduce the trouble of laying due to insufficient control of the staying coke and the wear of the hearth brick. Is done. As a result, it is possible to secure and stabilize the capacity of the mat pool in which the mat can be sufficiently stored in the setter section, and to improve not only the productivity of the flash smelting furnace but also the stabilization of the converter operation in the next step. Achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an operation system of a flash smelting furnace according to the present invention.

FIG. 2 is an explanatory diagram showing a state of a heat balance accompanying the operation of the flash smelting furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flash furnace 2 Shaft 3 Settler 4 Uptake 5 Melt mat 6 Melt slag 7 Mat hole 8 Slag hole 9 Concentrate burner 10 Furnace top duct

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Makoto Hamamoto 6-1-1 Hibi, Tamano-shi, Okayama Mitsui Kinzoku Mining Co., Ltd. Hibiki Refinery F-term (reference) 4K001 AA09 BA04 EA03 EA07 FA09 GA04 GB11

Claims (1)

[Claims] An in-furnace refining furnace for a copper smelting furnace in which copper concentrate, coke, flux and other charges are blown together with oxygen-enriched air using a concentrate burner from the top of a shaft provided in the flash furnace. In the control method, when the operating conditions are changed during the operation of the flash smelting furnace, the convergence calculation of the copper grade and the coke combustion rate of the mat is performed based on the heat balance and the oxygen balance of the shaft. Calculate the amount of coke staying in the molten slag layer of the target and feed back the excess or deficiency with the target coke amount to determine the amount of coke supplied from the concentrate burner so that the amount of coke staying in the molten slag layer in the setter becomes constant. A method of controlling a degree of reduction in a furnace in a copper smelting flash smelting furnace.