JP2003013152A - Method for charging ore to be charged into flash furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for charging an ore to be charged into a flash smelting furnace, which can inexpensively and accurately regulate the charging amount of ore, and can stabilize the mat grade. SOLUTION: In the method for charging an ore to be charged into the flash smelting furnace, which cuts out the ore 30 into a fixed volume, carries it by a chain conveyor 12 and drops it in a chute 14, and charges it into the flash smelting furnace 1 with an oxygen-enriched air 40 from a concentrate burner 9 at the outlet of the chute, a flowmeter 15 is installed on the way to the chute, which converts a change of the capacitance detected when particulate matters pass between capacitor plates, into a flow rate of the particulate matters; the falling flow rate of the charged ore in the chute is measured with the flowmeter; and the revolution speed of a motor 13 for the chain conveyer is regulated so as to make the measured flow rate of the charged ore match with an aimed charging quantity. And also, a shutter 17 for opening/closing the chute is installed on the outlet side of the installed flow meter, and it is opened during charging and closed during the rest time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging ore charging method for a flash smelting furnace that produces mats such as Cu and Ni.

[0002]

2. Description of the Related Art The flash smelting furnace method, which is widely used for smelting non-ferrous metals, utilizes the heat of oxidation reaction of the ore charged, so the fuel consumption rate is higher than other methods (blast furnace method, reverberatory furnace method). It has low characteristics and is capable of responding to the strengthening of environmental management.
As shown in FIG. 1, the furnace body of the flash smelting furnace 1 includes a shaft 2, a setler 3, and an uptake 4. In operation, a concentrate burner 9 is used from the top of the shaft 2 to concentrate Cu, Ni, etc., flux and other charges, and pulverized coal, coke, etc. fuel (hereinafter, these charges are referred to as “charge”). Ore ”) is blown into the shaft 2 together with the hot air (preheated oxygen-enriched air) separately delivered to the furnace top duct 10. In the shaft 2, the oxidization reaction heat of the charge and the combustion heat of the fuel cause dissolution and oxidation of the concentrate and the like, and a solution composed of the mat 5 and the slag 6 and sulfur dioxide are produced. The solution accumulates in the setler 3 and forms layers separated vertically due to the difference in specific gravity. The mat 5 is intermittently extracted from the mat hole 7 and sent to the converter factory via a ladle. The slag 6 is continuously or intermittently extracted from the slag hole 8 and sent to a smelting furnace (not shown) or subjected to water granulation treatment or the like. Sulfurous acid gas flows over the slag layer, is delivered to the sulfuric acid factory via the uptake 4, and is used as a raw material for sulfuric acid production.

In the flash smelting furnace, it is necessary to match the matte quality of the produced mat (concentration of the main metal of the matte) with the converter required value (Cu: 60 to 67% in one example of Cu matte). Since the matte quality is mainly determined by the balance between the charged ore charging amount and the oxygen-enriched air amount, it is important to correctly measure and control the charged ore charging amount. The following methods are available for measuring the amount of ore charged in the flash smelting furnace.

(A) Loss-in-weight feeder The concentrate or ore charged in the hopper is measured in real time by a weighing machine, gradually cut out by a screw conveyor, and the weight reduction of the hopper is treated as the charging amount.
Before the concentrate or ore in the hopper is exhausted, it is quickly filled and continuously cut out. Mainly engineered by Autokump, many overseas smelters have recently begun to introduce it.

(B) Conversion from the drive motor output of the chain conveyor For example, a large amount of concentrate or charged ore (about 200 to 400 t)
The chain conveyor, which is attached to the lower part of the bottle stored in, is filled with concentrate or the like in a constant volume, and the charging amount is obtained from the transport speed of the chain conveyor. Usually, the transport speed of the chain conveyor is often obtained from the amount of rotation of the motor driving the chain conveyor (motor inverter output). Traditionally used in most smelters.

[0006]

Although the method (A) is considered to have excellent reliability, the introduction cost is high (100 million units).
Therefore, there is a problem that the investment amount becomes excessive. Also, the above
Method (B) is inexpensive, but mixes concentrates from multiple brands
When used as a (blend), the bulk specific gravity of the powdered ore charged to the chain conveyor changes depending on the filling degree of the bottle and the type of concentrate used. However, there is a problem that the amount of charged ore (charged amount of charged ore per unit time) deviates from the target value and the variation in mat quality becomes large.

[0007] Therefore, an object of the present invention is to provide a charging ore charging method for a flash smelting furnace capable of adjusting the charging ore charging amount inexpensively and accurately and stabilizing the matte quality.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a change in capacitance detected by flowing a powder or granular material between capacitor electrode plates is determined by the flow rate of the powder or granular material. A conversion type flow meter (Japanese Patent Laid-Open Nos. 11-79411 and 20
(Refer to the 01-21397 publication) to measure the flow rate of the charged ore in the chute to the concentrate burner, and to ensure that the measured charged ore flow rate matches the target charging amount, the chute has a constant volume from the bottle. It was found that the target accuracy of the charging amount of the ore is improved by controlling the motor speed of the chain conveyor that feeds the charged ore into the ground. It was also found that the shutter is provided on the flow meter outlet side of the chute to prevent heat damage to the flow meter and ensure measurement accuracy. In addition, for deviations in the true value of the measured ore flow rate due to fluctuations in the blending ratio of concentrates, etc., the reactor condition monitoring data (reactor gas temperature, waste heat boiler inlet gas temperature, slag loss of discharged slag, etc.) Based on this, it was found that the mat quality can be stabilized by adjusting the flow rate of oxygen-enriched air.

The present invention has been made on the basis of these findings, and its gist is as follows. (1) Charged ore charge in a flash smelting furnace where the charge ore is cut into a fixed volume, conveyed by a chain conveyor, dropped into a chute, and charged into the flash smelter together with oxygen-enriched air from the concentrate burner at the chute exit. In the charging method, the flow rate of the charged ore in the chute is set by installing a flow meter in the chute that converts the change in capacitance detected by flowing the powder or granules between the capacitor plates into the flow rate of the granule. Is measured and the motor rotation speed of the chain conveyor is adjusted so that the measured charging ore flow rate matches the target charging amount.

(2) A shutter for opening and closing a chute is installed on the outlet side of the flow meter installation section, and is opened during charging and closed during charging, and the flash smelting furnace according to (1) is characterized in that Concentrate charging method. (3) The shutter is installed at two or more positions, and an inert gas is allowed to flow in the chute between the closed shutters while charging is stopped. (2) Charging ore charging of a flash smelting furnace Method.

(4) When an abnormal change occurs in the flow rate of the measured charging ore during charging, and then an abnormal change occurs in the monitoring measurement data of the gas temperature in the furnace and / or the gas temperature at the waste heat boiler inlet, If the abnormal change is on the increase side, the flow rate of the oxygen-enriched air is decreased, and if the abnormal change is on the decrease side, the flow rate of the oxygen-enriched air is increased (1)-
The charging ore charging method of the flash smelting furnace according to any one of (3).

(5) When an abnormal change occurs in the measured ore flow rate during the charging operation, and then an abnormal change occurs in the monitoring analysis data of the slag loss of the discharged slag and / or the matte quality of the extraction mat, the anomaly occurs. If the change is on the increase side, the flow rate of the oxygen-enriched air is decreased, and if the abnormal change is on the decrease side, the flow rate of the oxygen-enriched air is increased (1) to (4). The method for charging ore charging of the flash smelting furnace described in.

[0013]

FIG. 2 is a schematic view showing an example of an embodiment of the present invention (1). The charged ore 30 stored in the bin 11 is cut into a constant volume (predetermined volume), carried by the chain conveyor 12, and dropped into the chute 14. The chute 14 is connected to the concentrate burner 9 on the top of the shaft 2 of the flash smelting furnace 1. The charged ore 30 reaching the concentrate burner 9 is loaded into the furnace by riding on the air flow of the oxygen-enriched air 40 from the furnace top duct 10. A flow meter 15 is installed in the middle of the chute 14 to measure the falling flow rate of the charged ore in the chute. The measurement result of the flow meter 15 (flow rate of measured ore) is sent to the controller 16. The controller 16 compares the sent measured charge ore flow rate with the target charge amount, and acts on the inverter of the motor 13 that drives the chain conveyor 12 so that the difference falls within the allowable error range. Adjust the rotation speed of 13.

The flow meter 15 is of a type in which a change in capacitance detected by flowing a powder or granular material between the capacitor plates is converted into a powder or granular material flow rate. An example of the configuration is shown in FIG. One set of two sets of capacitor plates having the same structure is the measurement electrode 20, the other set is the reference electrode 21, the measurement electrode 20 is attached to the chute 14,
The measurement electrode 20 and the reference electrode 21 form a bridge circuit. While the charged ore 30, which is a granular material, passes through the measurement electrode 20 part, the capacitance of the measurement electrode 20 increases, and a difference current corresponding to the capacitance is generated between the reference electrode 21 and the bridge circuit. Is output. The difference current is detected by the amplifier 22, processed by the calculator 23 and converted into the flow rate of the granular material, which is used as the measurement result of the flow meter 15.
The calculator 23 integrates the difference current with respect to time and converts the result into a powder or granular material flow rate. The calibration curve (the relational expression between the differential current and the flow rate of the granular material) required for the conversion is experimentally obtained. As the flow meter 15 of this type, “Capacitance type granular material flow rate measuring device” manufactured by Instech Co., Ltd. can be preferably used.

The measuring method used in the present invention is the conventional method (A).
It is cheaper (about 1/10 of (A)). Further, the difference in bulk density of the granular material causes the difference in the instantaneous value of the differential current and the duration difference, but the product of the instantaneous value difference and the duration difference is constant, so the time integrated value of the differential current is It reflects only the passing weight regardless of the density. Therefore, in the present invention, the aiming accuracy of the charging amount of the ore is higher than that in the conventional method (B).

Further, in the present invention (2), as shown in FIG. 4, for example, a chute opening / closing shutter 17 is provided on the outlet side of the flowmeter installation portion (a portion between the flowmeter 15 of the chute 14 and the concentrate burner 9). Installed at, open during charging and close during charging stop. In the present invention (1), since the chute 14 is hollow in the furnace, the gas inside the furnace flows into the chute 14 from the shaft 2 when charging is stopped (particularly when charging is stopped due to operational trouble), and the flowmeter installation part May exceed the appropriate operating temperature of the flowmeter 15 (for example, room temperature to about 80 ° C) and rise to nearly 150 ° C, resulting in deterioration of the performance of the flowmeter 15. On the other hand, according to the present invention (2), the shutter 17 is stopped while charging is stopped.
Since the is closed, there is no ingress of the furnace gas containing SO ₂ gas into the flow meter installation part, and the performance deterioration of the flow meter due to abnormal temperature rise can be prevented. It is preferable to select heat-resistant and corrosion-resistant materials for the flowmeter. In addition,
The shutter 17 may not be required to be closed when the charging is stopped for a short time such as inspecting the furnace for about 10 to 15 minutes.

Further, in the present invention (3), for example, as shown in FIG. 5, the shutter 17 is installed at two or more positions, and nitrogen gas or argon is provided in the chute 14 between the closed shutters while charging is stopped. Inert gas 50 such as gas is flowed. According to this, since the shutter 17 is cooled by the inert gas 17, the temperature rise of the flow meter 15 can be prevented more reliably. Also, some of the charged ore may remain on the closed shutter,
There is also no danger of the temperature of the furnace heating up or igniting.

By the way, in the measuring method used in the present invention,
As described above, the bulk density deviates from the error factor of the measured ore flow rate, but the relative permittivity of the granular material adds to the error factor. The relative permittivity of concentrates changes depending on how they are blended. If a calibration curve is obtained for each blend type to be used and the calibration curve is switched to the one corresponding to the blend type after the change every time the blend type is changed, the flow rate measurement error due to the difference in relative permittivity can be reduced. However, when the number of blended species is large, the load of the experiment for obtaining the calibration curve for that number is too large, which is not realistic.

As a countermeasure against such a case, in the present invention (4), an abnormal fluctuation occurs in the flow rate of the measured ore charged during the charging operation, and then the gas temperature in the furnace and / or the gas temperature at the waste heat boiler inlet is measured. When an abnormal change occurs in the monitoring measurement data of, the flow rate of the oxygen-enriched air is decreased if the abnormal change is on the increase side, and the flow rate of the oxygen-enriched air is increased if the abnormal change is on the decrease side. I chose Here, the "abnormal fluctuation" or "abnormal change" means a fluctuation or change that exceeds a range specified based on the actual fluctuation range at the time of charging the same blend type (hereinafter the same). The waste heat boiler uses the heat of the exhaust gas of the furnace to obtain steam, and although it is not shown in the figure, it is arranged so as to be connected to the uptake 4 in FIG.

Anomalous fluctuations in the measured charge ore flow rate indicate that the blend species has been changed to one that does not match the current calibration curve. Therefore, the deviation of the measured ore flow rate from the true value should be large. When the measured charging ore flow rate is larger (or smaller) than the true value, the actual charging amount becomes larger (or smaller) than the target charging amount, and the O ₂ / charging ore ratio (in reactor reaction The ratio of the amount of oxygen involved and the amount of ore charged) is smaller (or larger) than the appropriate value set from the relationship with the matte quality. Factors that change with this include the furnace gas temperature and the waste heat boiler inlet gas temperature. The furnace gas temperature and the waste heat boiler inlet gas temperature are
When the O ₂ / charged ore ratio is smaller (or larger) than the appropriate value, it changes to the decreasing (or increasing) side. This change is reflected in the monitoring and measurement data of the furnace gas temperature and the waste heat boiler inlet gas temperature.

Therefore, according to the present invention (4), it is judged whether or not the change in the monitoring measurement data of the furnace gas temperature and / or the waste heat boiler inlet gas temperature is abnormal. If there is an abnormality, the change is reduced. If so, the flow rate of the oxygen-enriched air is increased, and if the change is on the increase side, the oxygen-enriched air flow rate is decreased. If there is no abnormality, the setting is not changed. As a result, the O ₂ / charged ore ratio can be returned to an appropriate value, and variations in matte quality can be suppressed.

Either one or both of the in-furnace gas temperature and the waste heat boiler inlet gas temperature can be used as an instruction factor for changing the oxygen-enriched air flow rate setting, but from the viewpoint of double checking to improve reliability. If so, it is preferable to use both. In carrying out the present invention (4),
A relational expression between the amount of change in the gas temperature in the furnace and the gas temperature at the inlet of the waste heat boiler and the setting change amount of the oxygen-enriched air flow rate is necessary
Such a relational expression can be obtained by analysis of operation result data, experiments, and the like.

Further, in the present invention (5), an abnormal fluctuation occurs in the measured charging ore flow rate during the charging operation, and then an abnormal change occurs in the monitoring analysis data of the slag loss of the discharged slag and / or the matte quality of the extraction mat. When the abnormal change occurs, the flow rate of the oxygen-enriched air is decreased if the abnormal change is on the increase side, and the flow rate of the oxygen-enriched air is increased if the abnormal change is on the decrease side.

As described above, if there is an abnormal fluctuation in the measured concentrate flow rate, the O ₂ / charged ore ratio will be smaller (or larger) than the appropriate value set from the relationship with the matte quality. Becomes Factors that change with this include the slag loss and matte grade, in addition to the above-mentioned furnace gas temperature and waste heat boiler inlet gas temperature. If the main metal of the matte (metal subject to refining) is represented by M, slag loss is M of slag.
The density and mat quality are evaluated by the M density of the mat. The slag loss and matte grade change to the decreasing (or increasing) side when the O ₂ / charged ore ratio is smaller (or larger) than the proper value. This change is reflected in the monitoring analysis data of slag loss of discharged slag and matte quality of extraction matte.

Therefore, in the present invention (5), it is determined whether or not the change in the monitoring analysis data of the slag loss of the discharged slag and / or the matte quality of the extraction mat is abnormal. For example, the flow rate of the oxygen-enriched air is increased, and if the change is on the increase side, the flow rate of the oxygen-enriched air is decreased. If there is no abnormality, the setting is not changed. As a result, the O ₂ / charged ore ratio can be returned to an appropriate value, and variations in matte quality can be suppressed.

The slag loss of the discharged slag and the matte quality of the extraction mat may be used as one or both of them as an instruction factor for changing the oxygen-enriched air flow rate setting. Since the slag is continuously discharged, there is no restriction on the analysis chance of the discharged slag, whereas the mat is extracted intermittently, so the analysis opportunity of the extracted mat is limited to the intermittent mat extraction opportunity. Therefore, as the instruction factor for changing the oxygen-enriched air flow rate setting, the slag loss of the exhaust slag that is analysis chance-free can be used more preferably. The matte quality of the extraction mat may be used for verifying the slag loss change tendency of the discharged slag when the matte extraction chance is synchronized with the abnormal fluctuation of the measured charging ore flow rate. In carrying out the present invention (5), a relational expression between the amount of change in the slag loss of the exhaust slag and the matte quality of the extraction mat and the amount of change in the setting of the oxygen-enriched air flow rate is necessary. It can be obtained by analyzing operation results data and experiments. Further, by using the present invention (4) and (5) together, further favorable results can be obtained.

[0027]

[Example] In the flash furnace of the form shown in FIG. 1, an ore (hereinafter referred to as Cu ore) composed of Cu concentrate or the like blended by the conventional method (B) is conventionally charged. The variation in matte quality was about σ (standard deviation) = 1 to 3%.
In this flash smelting furnace, according to the present invention (1), a flow meter 15 and a controller 16 are installed as shown in FIG. 2, and the motor speed of the chain conveyor is adjusted so that the measured value of the flow meter matches the target charging amount. The Cu ore was charged while controlling the temperature. As the flow meter, "Capacitance type granular material flow rate measuring device" manufactured by Instech Co., Ltd. having a configuration as shown in FIG. 3 was used. The proper operating temperature of this flow meter is room temperature to 80 ° C.

Conventionally, in this flash smelting furnace, the chute is hollow in the furnace, and when the charging is stopped, the gas in the furnace enters and the temperature of the flowmeter installation section rises to near 150 ° C. Therefore, the present invention (2 4), one shutter is provided on the outlet side of the flow meter of the chute as shown in FIG. 4, and the shutter is closed while charging is stopped. As a result, the temperature at the site where the flowmeter was installed during charging suspension was suppressed to around 70 ° C.

However, since the difference from the upper limit of the appropriate operating temperature is small, the shutters are arranged in two steps, as shown in FIG. 5, according to the present invention (3) for the sake of further safety. Nitrogen gas was made to flow between the shutters. As a result, the temperature of the flow meter installation site during charging suspension
It was suppressed to about 50 ℃. The accuracy of the calibration curve (correlation regression line between the flow rate of the ore sample of the same blend type and the differential current time integral value) of this flow meter (the degree of variation in the difference between the converted flow rate by the calibration curve and the measured flow rate by the electronic balance) is σ = Approx. 0.3
%Met. If this is set to 100 t / h scale, σ = about 0.
The fluctuation of 3t / h was suppressed, and the mat quality fluctuation was predicted to be σ = 0.5% or less based on the relationship between the fluctuation of the charged ore charging derived from the conventional operation record and the fluctuation of mat quality.

In practice, the following was done. (Case 1) While the operation of charging the same blend species as the sample used to determine the calibration curve continues, the mat quality fluctuation is σ = 0.3 under the condition that the oxygen-enriched air flow rate is kept constant.
It was suppressed to ~ 0.5%, and the good result as expected was obtained. (Case 2) However, if the operation of appropriately charging many different blend types continues, under the condition that the oxygen-enriched air flow rate is kept constant, the mat quality variation is σ = 0.5 to 0.7%,
Although smaller than before, it is larger than Case 1.

(Case 3) Therefore, according to the present invention (4), the indicated value of the flow meter fluctuates at a rate exceeding ± 3% during charging, and then the temperature of gas in the furnace and the temperature of gas in the waste heat boiler are changed. When the monitoring measurement data changes at a rate of more than ± 4%, the flow rate of oxygen-enriched air is decreased if the changes in these data are both increased (+), and the oxygen-enriched air is decreased if they are both decreased (-). The flow rate was increased. The change rate of the oxygen-enriched air flow rate was set to 5% per 1% change rate of the gas temperature in the furnace, based on the relational expression derived from the analysis of the operation result data. As a result, the variation of matte quality is σ = 0.4-0.6%
Then, it became about halfway between Case 2 and Case 1.

(Case 4) Further, according to the present invention (4) and the present invention (5), the indicated value of the flow meter is ± within the charging execution.
It fluctuates at a rate exceeding 3%, then the monitoring measurement data of the furnace gas temperature and the waste heat boiler inlet gas temperature change at a rate of more than ± 4%, and the monitoring analysis data of the slag loss of the discharged slag (mat extraction chance If it is synchronized with, the monitoring analysis data of the matte quality of the extraction mat is also added) ± 7%
If the changes in these data both increase (+), the flow rate of oxygen-enriched air decreases, and if both changes (-), the flow rate of oxygen-enriched air increases. did. The rate of change of the oxygen-enriched air flow rate was set to 1% per 5% of the slag loss change rate, based on the relational expression derived from the operation result data analysis. As a result, the variation in matte quality was σ = 0.3 to 0.5%, which was the same level as in Case 1.

[0033]

According to the present invention, the charged amount of ore can be accurately controlled by an inexpensive measuring method, the O ₂ / charged ore ratio can be maintained in an appropriate range, and the stability of matte quality can be improved. Has an excellent effect that it is significantly improved. In addition, fluctuations in the furnace conditions (increased slag loss, heat excess / insufficiency) that occur due to an excess or deficiency of the supply of the ore are suppressed, and the operation rate and load rate (total efficiency) of the furnace itself are improved, and productivity is improved. The effect of improvement is also expected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a flash smelting furnace.

FIG. 2 is a schematic diagram showing an example of an embodiment of the present invention (1).

FIG. 3 is an explanatory diagram showing a configuration example of a flow meter used in the present invention.

FIG. 4 is a schematic diagram showing an example of an embodiment of the present invention (2).

FIG. 5 is a schematic diagram showing an example of an embodiment of the present invention (3).

[Explanation of symbols]

1 flash furnace 2 shafts 3 setler 4 uptake 5 mats 6 slugs 7 mat hall 8 slug halls 9 Concentrate burner 10 Furnace top duct 11 bottles 12 chain conveyor 13 motor 14 shoots 15 flow meter 16 regulator 17 Shutter 20 Measuring electrode 21 Reference electrode 22 amplifier 23 arithmetic unit 30 Charged ore 40 oxygen-enriched air 50 inert gas

Claims (5)

[Claims] 1. A flash furnace charging in which a charged ore is cut into a constant volume, carried by a chain conveyor, dropped into a chute, and charged into a flash furnace together with oxygen-enriched air from a concentrate burner at the exit of the chute. In the ore charging method, a flowmeter of the type that converts the change in capacitance detected by flowing a granular material between the capacitor plates to the granular material flow rate is installed in the chute and A method for charging ore charging of a flash smelting furnace, which comprises measuring a falling flow rate and adjusting a motor speed of a chain conveyor so that the measured charging ore flow rate matches a target charging amount. 2. The apparatus for a flash smelting furnace according to claim 1, wherein a shutter for opening and closing the chute is installed on the outlet side of the flow meter installation section, and is opened during charging and closed during charging stop. How to charge ore. 3. The shutter is installed at two or more positions,
The charging ore charging method for a flash smelting furnace according to claim 2, wherein an inert gas is allowed to flow in the chute between the closed shutters while charging is stopped. 4. When an abnormal change occurs in the measured charge ore flow rate during the charging operation and then an abnormal change occurs in the monitoring measurement data of the furnace gas temperature and / or the waste heat boiler inlet gas temperature, the abnormality occurs. The flow rate of the oxygen-enriched air is decreased when the change is on the increase side, and the flow rate of the oxygen-enriched air is increased when the change is on the decrease side.
The method for charging ore charging of the flash smelting furnace according to any one of 1. 5. An abnormal fluctuation occurs in the measured charging ore flow rate during the charging operation, and then the slag loss of the discharged slag and / or
Alternatively, when an abnormal change occurs in the monitoring analysis data of the matte quality of the extraction mat, the flow rate of the oxygen-enriched air is decreased if the abnormal change is on the increase side, and the oxygen-enriched air is decreased if the abnormal change is on the decrease side. 5. The method for charging ore charging of a flash smelting furnace according to claim 1, wherein the flow rate of the gas is increased.