JPS60245735A - Operating method of installation for flash smelting furnace for smelting of copper - Google Patents

Abstract

PURPOSE:To stabilize the operation of a hot stove and to assure stability in a flash smelting furnace operation by providing means for decreasing stepwise the flow rate of the heavy oil to be used so as to optimize the regeneration of the temp. of the hot wind to be blown into flash smelting furnace for smelting of copper in which a solid carbon material is used as essential fuel. CONSTITUTION:The hot wind is fed from the hot wind furnace to the flash smelting furnace for smelting of copper in which at least 80% solid carbonaceous fuel is used as fuel. The relation indicating the optimum quantity of heat regeneration holds between the opening degree of a cold mixing valve for introducing cold wind and the waste gas temp. upon ending of combustion with respect to the temp. of said hot wind. The optimum temp. TF of the regenerative waste gas is determined from said relation and the flow rate of the heavy oil is stepwise changed to meet the increase of the waste gas temp. up to TF. The set temp. for decreasing the heavy oil is made into, for example, 4 stages; T1-T4. X is designated as the initial flow rate of the heavy oil and Y as the weight of the heavy oil to be decreased. The combustion is started at the initial flow rate Xl/hr and is decreased by Yl/hr each at the temps. T1-T4 until the optimum heat regeneration condition is attained at the temp. TF.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating a flash smelting furnace for copper smelting, and in particular to a method for more stable operation of a flash smelting furnace using stable high-temperature hot air. .

@Flash furnace for smelting is charged with sulfurized @ concentrate (hereinafter referred to as copper concentrate) along with 7 lux, etc., and air or oxygen-enriched air is blown into the pottery to absorb most of the reaction heat generated during oxidation. As a heat source, copper concentrate is melted and smelted by oxidation, and matte, a molten material mainly composed of copper sulfide and iron sulfide, and slag, a molten material mainly composed of silicate of iron oxide, are produced. It is a furnace that produces. Exhaust gas containing sulfur dioxide generated during this reaction is used as a raw material for producing concentrated sulfuric acid. Compared to other types of furnaces, flash-melting furnaces utilize the heat of the oxidation reaction of the concentrate.
It has been widely adopted in Japan because of its low fuel consumption rate and good environmental management.

In particular, in order to perform anti-Lula at high speed, 850 to 105
A hot-air operation method in which high-temperature air at 0° C. or oxygen-enriched air (hot air) is blown into the flash-melting furnace is a very advantageous method. In order to obtain the necessary hot air for hot air operation, a hot air furnace is installed as ancillary equipment to the flash furnace.

In this specification, copper smelting flash furnace equipment refers to equipment mainly consisting of a flash furnace and a hot blast furnace.

As mentioned above, flash furnaces use the heat of the oxidation reaction of raw materials as their heat source, but in the past they burned heavy oil as fuel to compensate for the lack of hot forging. However, as heavy oil prices have skyrocketed in recent years, fuel conversion measures using alternative solid carbonaceous fuels such as pulverized coal are being actively promoted.

The hot air operation of a flash-smelting furnace is particularly suited to this fuel conversion strategy, and the applicant has already succeeded in replacing more than 80% of heavy oil with solid carbonaceous fuel, and has even achieved 100% replacement with heavy oil. Success 〇Thus, we continued to operate the flash furnace using 80% or more, preferably 100% solid carbonaceous fuel, and the operation went smoothly with virtually no change in the plating grade or the Himenaka copper grade compared to previous results. However, it was found that the operation sometimes lacked stability. As a result of investigating the cause, it was found that the cause was hot air.

As shown in FIGS. 1 and 2, the hot blast furnace is composed of two or more units, each of which is a combination of a combustion furnace person and a heat storage furnace B. Each group alternately repeats the air blowing cycle and the combustion-heat storage cycle in a constant cycle so that while one is blowing air, the other is burning and storing heat. During the combustion-heat storage cycle, there is heavy oil in the lower combustion chamber 1 of the combustion furnace A.
Heavy oil is injected through the furnace 2, and fuel gas such as blast furnace gas (for example, exhaust gas from a ferronickel blast furnace called B gas), coke oven gas, and combustion air are injected, and the combustion gas flows into the regenerative furnace and its After the heat storage checker bricks 3 constituting the main body are heated, they are released into the chimney as exhaust gas. On the other hand, in the air blowing cycle, cold air taken in from the lower part of the regenerative furnace increases in temperature while passing through the checker bricks 3, and is taken out as hot air from the combustion furnace and sent to the flash furnace C.
sent to. The hot air temperature is controlled to a substantially constant value by introducing cold air through the mixed cooling valve 4, which automatically changes its opening depending on the measured hot air temperature. Dilution air is introduced into the combustion chamber when the temperature exceeds a predetermined temperature in order to protect the bricks in the furnace.

Although FIGS. 1 and 2 show a heavy oil/fuel gas mixed combustion type, a heavy oil only combustion type may also be used.

Combustion management in conventional hot-blast stoves is not as strict as shown above, and in addition to controlling the air-fuel ratio to determine the amount of combustion air required for combustion of heavy oil or heavy oil and fuel gas, it is also necessary to set the upper limit of the dome temperature and control the furnace temperature. The extent to which upper and lower limits were set on the outlet exhaust gas temperature was implemented. Among these, dome temperature control automatically introduces dilution air to protect bricks when the dome temperature as measured by a dome thermometer (Figure 1, reference number 5) exceeds a set value. .

Furnace exit exhaust gas temperature control is based on the exhaust gas temperature measured by the exhaust gas thermometer (Fig. 1, reference number 6), and prevents fuel from being burned at the upper limit, and prevents sulfur condensation at the lower limit. It is something. In addition, management was carried out based on comprehensive judgment based on the operator's experience and intuition, aiming for efficient operation. However, due to individual differences in the judgment of operators, detailed management was not possible, and the reality was that operations were usually carried out with excessive heat storage in order to respond to load fluctuations by burning heavy oil at a fixed location. Ta.

For this reason, the temperature of the hot air generated in the hot air stove and the lid are not stable, and the hot air fluctuates in the hot air stove, and furthermore, operational instability occurs when changing the cycle of the hot air stove. This was disrupting the stability of furnace operation. Additionally, wasting excess heavy oil in a hot blast furnace reduces the significance of the fuel conversion strategy for flash smelting furnaces.

Therefore, in order to ensure stable flash furnace operation using 80% or more, preferably 100% solid carbonaceous fuel, it is essential to first stabilize the hot blast furnace operation.

Against this background, the present invention aims to optimize and automate the operation of a hot blast furnace, and ultimately to stabilize the operation of flash furnace equipment and reduce the amount of heavy oil used.

To this end, we need to understand as quantitatively as possible the amount of heat stored in the hot-air stove, establish a combustion control method that constantly maintains an appropriate amount of stored heat so that we can quickly respond to load fluctuations, and Individual control is required, and an automatic control system must be introduced to minimize operator intervention.

In order to quantitatively grasp the amount of heat stored in the heat storage section of a heat storage furnace, it is good to be able to measure the temperature distribution and its changes in the heat storage section.
Its implementation is difficult. However, it has been found that it is possible to quantitatively determine the amount of heat storage to a considerable extent from the opening degree of the mixed cooling valve and the temperature of the flue gas during combustion.

As mentioned above, the hot air temperature is determined by the cold air passing through the bypass, which is installed between the cold air inlet and the hot air outlet of the hot air furnace, and passes through the mixed cooling valve, which automatically sets the opening degree according to the measured value of the hot air temperature. It is controlled to reach the set value by diluting it.

In normal operation, there is sufficient heat storage at the beginning of air blowing, so the hot air temperature can still be lowered to the set value, so a lot of cold air flows, but as air blowing approaches the end, the hot air temperature decreases.
The amount of cold air also decreases proportionally (see Figure 3). The amount of heat MM and cold M is controlled by the mixed cooling valve, and its opening degree at the end of air blowing is a measure of the amount of heat stored. In other words, if the mixed cooling valve is open at the end of air blowing, there is still room for heat storage, and if the opening degree is 0 and the hot air temperature is the set value, the amount of heat storage and the heat sink are balanced, and when the opening degree is 0, the hot air temperature is If it falls below the set value, it can be said that there is insufficient heat storage.

Therefore, the mixed cooling valve opening degree has a useful meaning as one of the representative values of the amount of heat storage.

Ideally, in combustion control, the fuel is adjusted while monitoring the change in heat storage amount so that a predetermined heat storage amount is achieved within a predetermined time.

However, as mentioned above, if you look at the amount of heat storage as a guide based on the opening of the mixed cooling valve, you can only get an estimate when the air blowing ends.
Also, there is no way to feed it back to the next combustion.

Therefore, the combustion exhaust gas temperature was adopted as another representative value in order to see the change in heat storage amount during combustion.

That is, immediately after the start of combustion, there is no heat storage, so the exhaust gas temperature is low, or the exhaust gas temperature increases as the amount of heat storage increases. Therefore, determining the target value of the exhaust gas temperature from the amount of heat storage (opening degree of the mixed cooling valve at the end of air blowing) approaches ideal combustion management to some extent.

An appropriate heat storage line can be established empirically between the opening degree of the mixed cooling valve and the exhaust gas temperature at the end of combustion. An example of this is shown in FIG. Above the appropriate heat storage line, there is insufficient heat storage, and below it there is excess heat storage.

This threshold requires that heat is stored until the exhaust gas temperature reaches 310°C with 0% poetry combustion at the end of air blowing, and when the opening is 60%, heat storage is sufficient at 220°C. It shows what will happen.

Therefore, the exhaust gas temperature at the end of combustion, which indicates the opening degree of the mixed cooling valve and the appropriate stored heat, is expressed by the following equation.

Based on the graph in Figure 4, TF = 310°C - (mixed cooling valve opening %) x 3°C/1% Once the final target exhaust gas temperature TF is determined in this way, the increase in exhaust gas temperature up to TF is In addition, by changing the flow rate of heavy oil in stages, efficient combustion is possible for each hot blast stove. This combustion method is diagrammatically shown in Figure 5.

In Figure 5, T1-Ta = heavy oil reduction set temperature, can be set arbitrarily X =
Initial heavy oil flow rate, can be set arbitrarily Y - Heavy oil reduction amount, can be arbitrarily set Appropriate temperature T1 at the temperature up to TF...
A gradual reduction in the flow rate of heavy oil is planned at...-. The number n is not limited to four as described above, but can be set arbitrarily. The amount of Y can be arbitrarily set within a range that ensures a heavy oil flow rate that does not result in insufficient combustion in a special hot stove.

The heavy oil starts to burn at an initial flow rate of XI/Hr, and the exhaust gas temperature decreases by Yl/Hr from T1 to T4.
Achieve optimal heat storage conditions. As described above, Tp is the temperature calculated from the opening degree of the mixed cooling butterfly valve at the end of air blowing before the start of combustion.

Depending on the situation, an alarm or the like may be used to prompt the operator to decide whether or not to continue combustion using TF.

In this way, an efficient combustion control method has been achieved, but by operating it under an automatic control system using an automatic control device such as a one-loose controller, a hot blast furnace operating method that meets the above objectives can be achieved. By operating the flash-melting furnace using the hot air thus generated, hot air of constant and stable quality is continuously supplied to the flash-smelting furnace without the inconvenience caused by cycle changeovers, thereby reducing copper concentrate and solids. Produces a % fast reaction that is consistent with carbonaceous fuels.

Thus, the present invention provides a flash smelting furnace for producing matte and slag by charging copper concentrate, fuel, 7 lac and other charges and blowing hot air, and for producing matte and slag by blowing hot air.
In a copper smelting flash furnace facility equipped with a hot blast furnace that alternates between a heat storage cycle and a hot air blast cycle, at least 80% solid carbonaceous fuel is used as the flash furnace fuel, and the hot blast temperature is controlled in the hot blast furnace. In order to achieve this, the optimum heat storage exhaust gas temperature TF is determined from the relational expression showing the appropriate amount of heat storage between the opening degree of the mixed cooling valve that introduces cold air and the exhaust gas temperature at the end of combustion, and multiple exhaust gas temperatures T1 to Tn up to TF are determined. Provided is a method for operating a copper smelting flash furnace facility, which is characterized by reducing the flow rate of heavy oil in stages. It is preferable to use 100% solid corrugated fuel as the flash furnace fuel.

Solid carbonaceous fuels that can replace heavy oil in flash furnaces include various grades of coal, charcoal, and coke.
Particularly preferred are pulverulent coke and lump granular low-quality stone recycle.

Powdered coke refers to powder coke, granular coke, or a mixture of both, and includes various types of coke other than the sized lump coke normally used for steelmaking.
In particular, it is powdery coke that is obtained in a settling pit as a by-product when raw material return is coked in a coke oven to produce sized coke for iron W4 smelting, and the extracted coke is extinguished with cooling water in a fire extinguishing tower. It is preferable to use sedimentary coke. Table 1 shows the particle size distribution, components and calorific value of the precipitated coke powder.

As the powder coke, in addition to the above-mentioned precipitated coke powder, 10 cm or less coke can be used alone or in combination.

Lump-grained low-grade coal refers to coals other than sized high-grade coal, and lignite is an example. Table 1 shows the particle size distribution, components, and calorific value of Wanpo coal (produced in Australia), which is the horizontally corrugated charcoal used in the present invention.

Table 1 Particle size distribution, components and calorific value of precipitated coke powder and Wanpo coal FIG. 6 shows an example of a hot stove operation control system embodying the present invention. As can be understood by comparing FIGS. 1 and 2, the cold air passes through the regenerator B, the combustion furnace A, and is turned into hot air and sent to the place of use. A portion of the cold air is bypassed to the hot air passage downstream of the combustion furnace A via the mixed cooling valve 4. hot air thermometer 8
measures the hot air temperature and operates the valve actuator 1 based on the measurement signal.
0 automatically sets the opening degree of the mixed cooling valve 4 having a butterfly valve structure, for example. The temperature of the exhaust gas during the combustion-heat storage cycle is measured by an exhaust gas thermometer 6. Also, in the combustion chamber A,
Heavy oil, fuel gas, combustion air and dilution air are introduced in a controlled manner. Among these, when the temperature of the dome thermometer 5 exceeds the setting, the dilution gas is supplied to the dilution gas controller 1 to protect the bricks.
1 and valve 12.

There are two ways to operate a hot stove: a heavy oil-only combustion system and a heavy oil-fuel gas mixed combustion system, and the present invention can be applied to either of them. For example, blast furnace exhaust gas is used as the fuel gas, but its concentration may vary. Therefore, the calorific value of the fuel gas is calculated according to the concentration of the fuel gas, converted to the equivalent amount of heavy oil, and the amount obtained by subtracting the amount of fuel gas from the heavy oil amount controller is determined as the net heavy oil value. Whichever method is adopted, the present invention is equally applicable to either method. In Figure 6,
The heavy oil quantity controller 12 and the fuel gas quantity controller 14 are input with (1) a co-firing signal and (2) a heavy oil exclusive combustion signal, and a control style is determined according to the operating system.

The heavy oil flow rate is transmitted to the heavy oil amount controller 12 by a flow meter 16 . The fuel gas flow rate is transmitted to the fuel gas amount controller 14 by a flow meter 18 . The fuel gas concentration and heat generation i are calculated, and a signal obtained by converting the calculated values into heavy oil, etc. is input from the fuel gas amount controller 14 to the heavy oil amount controller 12 . Method■
According to (1) and (2), a signal for the heavy oil equivalent of heavy oil + fuel gas or for heavy oil alone is input from the heavy oil amount controller 12 to the combustion air amount controller 20, and the required amount of combustion air is calculated based on it. The required combustion air is introduced into the combustion chamber via the valve 21. Numbers 23 and 30 indicate fuel gas and heavy oil control valves, respectively. .

In order to realize the automatic control system according to the present invention, a one-loop controller is installed between the mixed cooling valve 4, the exhaust gas thermometer 6, and the heavy oil amount controller 12, which has a built-in microb 4 processor and performs control while performing calculations. be done.

The exhaust gas temperature controller 28 performs the following functions.20 Takes the exhaust gas temperature from the exhaust gas thermometer 6 as an input.

■ The opening degree of the mixed cooling valve 4 is taken in as input via the reader 29.

■ Read the mixed cooling valve opening degree using the reading timing signal,
The end point combustion temperature Tp is calculated according to the above-mentioned formula.

■ Output these signals to the heavy oil amount controller.

■ If necessary, generate a notification when the exhaust gas temperature reaches the end point temperature.

The heavy oil amount controller 12 performs the following functions: ■ Inputs a heavy oil amount setting signal from the exhaust gas temperature controller 28;

■ Input the heavy oil flow rate from the heavy oil flow Doso 16.

(2) Input the fuel gas composition and flow value signal (from the flow meter 14), and output the amount obtained by subtracting it from the heavy oil amount setting signal as a control signal, and transmit it to the control valve 30. (In case of co-firing method (method ①)) ■ Calculate the amount of heavy oil to perform stepwise control of the amount of heavy oil.

(2) Compute the combustion air ratio and cascade output to the combustion air controller 20.

In this way, automated hot blast stove operation according to the present invention is realized.

In the conventional combustion method, an arbitrary flow rate of heavy oil was determined, and the fuel oil was manually controlled to reach the target exhaust gas temperature by tightening the fuel midway through the combustion process while monitoring the rising trend of exhaust gas temperature. The timing of tightening the heavy oil was based on the operator's experience.

However, in reality, it was impossible to make frequent adjustments, and a fixed amount of heavy oil was burned.

In addition, the two hot air stoves had differences in air flow rate, effective area of checker bricks, etc., and even under the same operating conditions, there was a large difference in heat storage amount. Therefore, in order to adjust the target exhaust gas temperature to match the one hot air furnace with less heat storage lid (as mentioned above, it was impossible to change the heavy oil setting amount every time the two were switched), the other hot air The furnace was operating with excess heat storage.

By implementing the hot stove operation of the present invention, the following effects can be obtained: (a) Reducing the rate of increase in exhaust gas temperature and reducing wasteful combustion;
The amount of heavy oil used can be saved.

(b) Since the amount of heavy oil used at the base can be changed, there is no difference in the amount of heat storage, so the amount of heavy oil that was previously burned in one base can be reduced.

(c) It can smoothly respond to changes in air flow rate, hot air temperature, etc.

) Operation can be automated with minimal intervention from operators.

Hereinafter, actual operation examples comparing the conventional operation method and the operation method of the present invention will be shown. In operation, hot air at 990 to 1000°C was supplied to the copper smelting flash furnace using two hot blast furnaces (A1 and A2).

FIGS. 7 and 8 show changes in heavy oil flow rate between the conventional combustion method and the method of the present invention. Conventionally, operation was performed at a constant flow rate unless the flow rate was changed manually, but in the present invention, it can be seen that the exhaust gas temperature automatically decreases when it reaches the set position. FIG. 9 shows a comparison of the amount of heavy oil used when the conventional constant flow rate combustion method and combustion control are used with the exhaust gas temperature being the same.

From now on, the heavy oil that conventionally burns at about 15,607 al/Hr will now be heated to 149 al/Hr, approximately 7,017 al/Hr, through automatic control.
Hr is decreasing. Moreover, FIG. 10 is a comparison between the conventional method and the automatic control method of the present invention when combustion starts at the full specified capacity of the burner. From now on, heavy oil usage difference 1701
/Hr, and the exhaust gas temperature difference is 65°C.

The table below summarizes these data.

Here, the rate of increase in exhaust gas temperature refers to the rate of temperature increase from 20 minutes after the start of combustion, and it can be seen that in any case, self-study control is slower and can reduce wasteful combustion.

FIGS. 11 and 12 show the difference in combustion exhaust gas temperature before combustion control is started when the operation is stable and after combustion control is started.

It can be seen that before the start of control, the exhaust gas temperature at the end of combustion (the peak of exhaust gas temperature) varies from combustion to combustion, and is also different between the A1 and A2 hot blast furnaces.

However, with this improvement, the fluctuation in peak temperature has been reduced and the difference between A1 and A2 has also disappeared.

In this way, a very stable temperature of 650°C or above, preferably 8
Hot air at a temperature of 50 to 1050°C is supplied to the flash furnace.

The solid carbonaceous fuel may be added directly to the flash melting furnace, but the preferred method of addition is to install a solid carbonaceous fuel hopper in parallel with the IN concentrate hopper and carry it out by continuously extracting it. The method of adding copper concentrate, flux, etc. on a conveyor is the most desirable mode since all subsequent charging system equipment can be shared. This improves fuel mixing uniformity and improves reactivity.

For about three months, the flash melting furnace was operated without using heavy oil, using precipitated coke powder and hot air from an improved hot blast furnace. The table below shows the operational results.

Compared to the conventional results shown in the right column, there was virtually no change in the plating quality or copper content in iron, and stable flash furnace operation was ensured, with no problems associated with switching to the 90 hot stove cycle.

As explained above, by stabilizing the operation of the hot blast furnace, we succeeded in stabilizing the operation of the flash furnace and establishing a plan for switching to solid carbon fuel. In this way, for the entire copper smelting flash furnace equipment, the amount of heavy oil used can be greatly reduced by (1) saving 80% or more, preferably 100%, of M oil in the flash furnace and (11) minimizing wasteful combustion in hot air melting. This made reduction possible.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the operating principle of a hot blast furnace and a flash furnace, Figure 2 is an explanatory diagram showing the operating status of two hot blast furnaces, and Figure 3 is an explanatory diagram showing the operating state of two hot blast furnaces. FIG. 4 is a graph showing the relationship between the amount of cold air blown, FIG. 4 is a graph showing the relationship between the opening degree of the mixed cooling valve and the exhaust gas temperature at the end of combustion, FIG. 5 is a graph showing the heavy oil stage control according to the present invention, and FIG. A control system diagram showing an example of the control system of the present invention, Figures 7 and 8 are graphs showing examples of changes in heavy oil heated rice between the conventional method and the present invention, and Figures 9 and 10 are control system diagrams of the conventional method and the present invention. 11 and 12 are graphs showing the differences in the embodiments, and graphs showing the deterioration of the exhaust gas temperature between the conventional method and the method of the present invention. A: Combustion furnace B: Regenerative furnace C: Flash furnace 1: Combustion chamber 2: Heavy oil burner 5: Heat storage brick 4: Mixed cooling valve 5: Dome thermometer 6: Exhaust gas thermometer 8: Hot air thermometer 10: Valve operation Controller 11: Dilution gas controller 12: Heavy oil amount controller 14: Fuel gas amount controller 16: Heavy oil flow meter 18 Two fuel gas flow meters 20: Combustion air...Controller 21: Combustion air control valve 23 Two fuel gas control valves 60: Heavy oil control valve 28: Exhaust gas temperature controller 29: Mixed cooling valve opening degree reader tT"" - Name of one agent Motohiro Kurauchi, ', j・-2,, -
two. Figure 7 31 degrees Figure 8 Ontomo Figure 11 Figure 12 Indication of the case of Manabu Shiga, Director General of the Japan Patent Office, 1981, 6J1251, Title of the invention of Patent Application No. 100694 Steel Relationship with the case of a person who amends the operating method of flash smelting furnace equipment Patent 1 Junjin name Nippon Mining Co., Ltd. Agent 〒103 Izu-1'-82 Former High 2- = -Taku11-・・shi ρNo. 1 Subject of amendment, -1- In the specification ;.' - Detailed description of the invention column (Contents of amendment The specification of Japanese Patent Application No. 1983-100694 is amended as shown in the attached sheet as follows. 1 Page 18, 3 lines from the bottom: “Conventional combustion method” and “to”
Insert ``r (Figure 7)'' between ``(Figure 7)'' and ``(Figure 8)'' after ``method of the present invention''. 2. Replace the submitted drawings Figures 7 and 8 with the attached ones.

Claims (1)

[Claims] 1) A flash-melting furnace that produces matte and slag by charging #6 concentrate, fuel, 7 lux and other charges and blowing hot air, and a combustion-heat storage cycle and hot air blowing cycle to generate the hot air. In a copper smelting flash furnace equipment equipped with a hot blast furnace that alternately performs
0% solid carbonaceous fuel is used, and from the relational expression showing the appropriate heat storage between the opening degree of the mixed cooling valve that introduces cold air to control the hot air temperature in the hot blast furnace and the exhaust gas temperature at the end of combustion. A method for operating a copper smelting and flash-smelting furnace equipment, characterized by determining the optimum heat storage exhaust gas temperature Tp, and gradually reducing heavy oil heating at a plurality of exhaust gas temperatures W Tl - Tn up to TP.