JPH0377858B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to evaluation of the performance of a concentrate burner in a flash smelting furnace, which performs a smelting reaction by blowing concentrate and reaction air or oxygen-enriched air (hereinafter referred to as reaction gas). Regarding the method. [Prior art] In a flash furnace, dry concentrate, such as copper concentrate, is blown together with a reaction gas from a concentrate burner installed at the top of a reaction shaft, and the concentrate is instantly oxidized and melted to form copper. Concentrate valuable metals such as 〓. In this case, it is important that the concentrate and the reaction gas are uniformly mixed so that a uniform oxidation reaction proceeds within a very short period of time as they fall through the reaction shaft. If the mixing conditions are poor and unreacted and undissolved materials are generated locally, this may accumulate in the settler at the bottom of the reaction shaft, preventing the formation of molten metal, or causing large fluctuations in temperature and quality, which may cause problems during reactor operation. Not only does this cause difficulties, but also local heating occurs in areas where the reaction is concentrated, damaging the bricks of the reaction shaft.Also, the heat of the oxidation reaction of the concentrate cannot be fully utilized, making it difficult to use auxiliary fuel. resulting in an increase in volume. Here, the state of mixing of the concentrate with the reaction gas is largely controlled by the structure of the concentrate burner provided in the flash furnace and its operating conditions, that is, the performance of the concentrate burner. Conventionally, to evaluate the performance of a concentrate burner, it was possible to determine what percentage of oxygen in the reaction gas contributed to the oxidation reaction of the concentrate by examining the mass balance of oxygen in the charge and output of the flash furnace. We have determined the oxygen efficiency that represents However, this method requires quantitative evaluation of all oxides contained in the feed and products, and there are many problems in terms of analysis technology, measurement errors, time and cost required for analysis, and it is not accurate. It was difficult to anticipate. There is also a method to evaluate the performance of concentrate burners using actual operational data such as smoke generation rate and difference between It is virtually impossible to maintain fluctuations and other operating conditions constant, and there is a problem in that absolute quantitative evaluation of burner performance cannot be performed. When there is a margin in the performance of the concentrate burner during light-load operation with a small amount of concentrate charged, the minimum temperature required for the reaction in the shaft can be determined by measuring the temperature distribution in the height direction within the shaft. It is possible to evaluate the performance of the concentrate burner by determining the height, but it is difficult to complete the measurement in a short period of time, and since the metallurgical reaction inside the shaft is a high-temperature oxidation reaction, it is possible to evaluate the performance of the concentrate burner by determining the height. Determining the required height of the shaft is extremely dangerous. [Problems to be Solved by the Invention] The present invention aims to provide a method by which the performance and arrangement height of a concentrate burner can be determined without waiting for long-term operation results as in the conventional method. [Means for solving the problem] The inventors selected the oxygen partial pressure in the solution as an index representing the progress of the high-temperature oxidation metallurgy reaction inside the flash furnace, and calculated this oxygen partial pressure as the amount of oxygen in the molten steel. Using an oxygen probe with a built-in oxygen concentration battery that uses stabilized zirconia as a solid electrolyte, which has come into use in recent years, the partial pressure of oxygen in the solution in the shaft and settler parts is measured, and this value is kept constant. After correcting the oxygen partial pressure at different temperatures (hereinafter this correction value will be referred to as the standardized oxygen partial pressure), we investigated in detail the changes in the standardized oxygen partial pressure in the flash furnace, and found that the standardized oxygen partial pressure at the shaft outlet was It was discovered that the performance of a concentrate burner can be quantitatively evaluated by determining the ratio of the logarithmic value to the logarithmic value of the standardized oxygen partial pressure in the settler section. However, measuring the oxygen partial pressure in the settler section requires inserting an oxygen probe from the ceiling of the settler section, as described later, making measurement difficult. Since the oxygen partial pressure of ivy can be used as a substitute, the present invention was constructed as follows. That is, the present invention uses an oxygen probe with a built-in oxygen concentration battery to measure the partial pressure of oxygen in the melt droplets falling in the space below the shaft in a flash furnace and the oxygen in the mats extracted from the mats directly below the shaft in the settler section. Measure the partial pressure, find the standardized oxygen partial pressure from these values, find the ratio of the logarithm of the standardized oxygen partial pressure value at the shaft and the standardized oxygen partial pressure value in the mat, and use this to determine the performance of the concentrate burner. This is the evaluation value. The present invention will be explained in more detail below. (a) Method for measuring oxygen partial pressure Oxygen concentration batteries ₍ ). Pt/Po ₂ ()/ZrO ₂ +MgO/Po ₂ ()/Pt(1) The electromotive force E of this oxygen concentration battery 1 can be expressed by the following equation (2). E=RT/4FlnPo ₂ ()/Po ₂ () (2) where R: Gas constant T: Absolute temperature F: Faraday constant Po ₂ (): Oxygen partial pressure indicated by the reference electrode Po ₂ (): Measured electrode The reference electrode is not particularly limited as long as it exhibits a constant oxygen partial pressure at a constant temperature, but in copper smelting, the accuracy
Fe・FeO is excellent. As is clear from equation (2), if the electromotive force E and temperature T of the oxygen concentration battery 1 can be measured, the value of the oxygen partial pressure Po ₂ () indicated by the reference electrode is known [For example, if the reference electrode is Fe/FeO,
RTlnPo ₂ () = −526800 + 129.6T (J・mol ^-1 )
] Therefore, the oxygen partial pressure Po ₂ () indicated by the measuring electrode is
can be found. (b) Method for standardizing oxygen partial pressure Since the oxygen partial pressure measured by an oxygen concentration battery changes depending on the temperature, the progress of the reaction can be estimated based on the oxygen partial pressure at each measurement location in the flash furnace. However, the temperature at each measurement location is generally different, so the obtained oxygen partial pressure is set at a certain temperature (for example, 1200℃ in copper smelting
It is necessary to standardize to the oxygen partial pressure at 1250℃, etc.). This standardization method is generally evaluated based on the redox reaction equation established between the compound components that make up the reaction system.In the present invention, since the constituent elements of 〓 and 〓 contain a large amount of iron, the following reaction It's good to think of a formula. 4FeO(l)＋O ₂ (g)＝2Fe ₂ O ₃ (l) (3) The standard free energy change △G°(T) in equation (3) is
It can be expressed as follows using the activities α _FeO and α _Fe2O3 of FeO(l) and Fe ₂ O ₃ (l) and the oxygen partial pressure PO ₂ (T). △G° (T) = −RTln (α _Fe2O3 ) ² / (α _FeO ) ⁴・PO ₂ (
T)(5) Therefore, the oxygen partial pressure PO ₂ (T ₁ ) at the measurement temperature T ₁
To standardize to the oxygen partial pressure PO ₂ (T ₂ ) at the standard temperature T ₂ , assuming that the activities α _Fe2O3 and α _FeO do not change and remain constant when the temperature changes between T ₁ and T ₂ ,
The following equation (6) is obtained from equation (5). lnPO ₂ (T ₂ ) = 1/RT ₂ △G° (T ₂ ) −1/RT ₁ △G° (T ₁ ) + lnPo ₂ (T ₁ ) (6) Therefore, the measurement temperature T ₁ and the oxygen at that temperature If the partial pressure is found, the reaction free energy △G° in equation (3) is known, so by substituting these values into equation (6), the oxygen partial pressure Po ₂ at standard temperature T ₂
(T ₂ ) can be obtained. [Example of measurement experiment] In order to investigate which points in the shaft section and settler section of a flash furnace are best to measure oxygen partial pressure, oxygen partial pressure was measured at various points in the shaft and settler section. I tried. The longitudinal cross-sectional view and plan view of the furnace in FIG. 1 show the locations where the oxygen partial pressure is measured. Four measurement holes 2, 3, 4, and 5 were opened at different heights in the side wall of the shaft part 1 of the flash furnace, and the measurement holes were measured in the shaft inner height direction and radial direction (shaft radius 3).
1m and 2m from the center of the furnace wall, respectively)
The change in the standardized oxygen partial pressure was determined. In addition, for the oxygen partial pressure in the settler section 6, several locations were selected for each measurement among the outlet 7 directly below the shaft section, the outlets 8 to 12 downstream from it, and the outlets 13 and 14. In addition to determining the horizontal change in the oxygen partial pressure inside the settler, we also measured the measurement hole 1 installed in the ceiling in the center of the settler.
The change in the normalized partial pressure of oxygen in the vertical direction in the solution in the settler from 5 was also investigated. FIG. 1 shows the values of the standardized oxygen partial pressure in the shaft part and each mat hole corresponding to the distance from the shaft part inlet, and Table 1 shows the results depending on the difference in the measurement position within the shaft. Further, FIG. 3 shows the normalized partial pressure of oxygen in the vertical direction in the solution in the settler section, which was measured through the measurement hole 15.

[Evaluation of burner performance]

For example, by measuring the oxygen partial pressure from the measurement hole 5 in the shaft part in Fig. 1, and by measuring the oxygen partial pressure taken out from the outlet 7 directly below the shaft part, the respective standardized oxygen partial pressures can be calculated as Po ₂ (R/S) and Po ₂ (S/T). In the normal operation of copper smelting, the copper concentrate supplied from the concentrate burner contains oxide-containing mill dust and copper slag powder, and melt droplets falling down the shaft. The lower you go, the higher the quality becomes.
In general, the higher the quality, the higher the Po ₂ , so the lower the shaft, the higher the Po ₂ should be, but in reality, the FeS contained in the melt droplets is dust, and the higher oxidation in the copper slag. Po ₂ decreases as you move toward the bottom of the shaft. In such a case, the performance η of the concentrate burner is determined as follows. η=100×logPo ₂ (R/S)/logPo ₂ (S/T)(
7) The value of η can take a value from 0 to 100, but the performance of the concentrate burner is better as the value of η is larger, and it has quantitative properties.In other words, the shaft on the horizontal axis in the graph of Figure 1 Settler section 1 from the top of the section to just below the shaft section
The smaller the slope of the standardized oxygen partial pressure up to 8, the better the performance. Po ₂ value of the shaft part when calculating η Po ₂
(R/S) is preferably measured at the bottom of the shaft section, slightly above the joint between the settler section and the ceiling brick, and the Po ₂ value of the settler section.
For Po ₂ (S/T), the value of any outlet in the settler section can be used, but the value of outlet 7 directly below the shaft is preferable. A desirable value for η is 95 or more when the standardized oxygen partial pressure is measured at the bottom of the shaft and at the outlet directly below the shaft. Regarding absoluteness, Equation (7) is a thermodynamic intensive variable that indicates the final state of the smelting reaction in the flash furnace.
Since it is standardized by logPo ₂ (S/T), it is considered that all thermodynamic and operational variables are standardized. On the other hand, if the copper concentrate supplied from the concentrate burner does not contain high-grade oxides such as repetitive dust or copper slag powder, the Po ₂ value will increase toward the bottom of the shaft. Sometimes η is η=100×logPo ₂ (S/T)/logPo ₂ (R/S)(
8) Find as. [Example] Examples will be described below. Example 1 Concentration of the case where four improved concentrate burners shown in Fig. 3a are used at the top of the shaft part and the case where four conventional concentrate burners shown in Fig. 3b are used at the top of the shaft part. Used for methods to evaluate the performance of ore burners. The conventional concentrate burner shown in FIG.
A burner cone 23 with a widened base is formed below it. A tubular concentrate chute 24 is vertically disposed in the center of the concentrate burner body 21 with its lower end protruding slightly below the ventilate-shaped constriction part 22, and a heavy oil burner 25 is provided passing through the center of the concentrate chute 24. The opening at the lower end of the heavy oil burner 25 is located near the outlet of the burner cone 23. A dispersion cone 26 for dispersing falling concentrate is provided on the outer periphery of a portion of the burner cone 23 below the outlet at the lower end of the concentrate chute 24 of the heavy oil burner 25. The reactor air supplied into the concentrate burner body 21 through the blast pipe 27 is blown from the ventilate-like constriction 22 of the concentrate chute 24 into the concentrate falling through the concentrate chute 24. ing. The improved concentrate burner shown in FIG. 3a is provided with an oxygen blowing pipe 28 surrounding the heavy oil burner 25 inside the concentrate chute 24 of the conventional concentrate burner shown in FIG. 1b. An outlet portion of the concentrate chute 24 is provided closer to the lower end than the center thereof, and an opening area adjusting spacer 29 is provided in the center portion to narrow the opening area, and the opening portion is inclined at 45° with respect to the axial direction of the oxygen blowing pipe 28. Ten guide vanes 30 are provided. The lower end surface of the dispersion cone 26 attached to the outer periphery of the lower end of the heavy oil burner 25 is connected to the lower end 3 of the concentrate chute 24.
It is a flat surface with substantially the same height as 2. The slope of the conical surface on the outer periphery of the concentrate dispersion cone 26 is parallel to a line connecting the inside of the lower end 32 of the concentrate chute 24 and the inside of the lower end of the burner cone 23 . A flow rate adjusting cone 33 is attached to the outer periphery of the lower end of the concentrate chute 24 with a stopper 3 so that the position can be adjusted below and below the upper surface of the concentrate burner main body 21 by means of a hanging rod 34.
5 and is suspended. The outer surface of the lower half of the flow rate adjusting cone 33 is formed parallel to the inner surface of the concentrate burner body 21 . Then, part or all of the high concentration oxygen is blown into the concentrate chute 24 as a swirling flow through the oxygen blowing pipe 28, and the gas flow rate is set at 80 to 240 m to be supplied from the lower end 32 of the concentrate chute 24 to the ventilated constriction part 22. /sec. The operation using both concentrate burners was continued for about one month, and the average value of the operation results during that period is shown. On the other hand, the evaluation of concentrate burners is the result obtained in a very short period of time when the respective operations are stable.
The oxygen partial pressure in the shaft part 1 was measured at a point 5.0 m below the top within a height of 8 m from the top of the shaft part 1 to the bottom surface.
The value of η was determined using the value of the oxygen partial pressure measured 10 minutes after the start of extraction of the water from the water outlet 7 directly below the shaft portion 1. These results are shown in Table 2.

[Table] From the results in the table above, it can be seen that the improved burner is superior to the conventional burner, and that the performance of the concentrate burner can be quantitatively evaluated using η. Example 2 Using the improved concentrate burner shown in Figure 3a,
Highly concentrated oxygen was blown into the concentrate chute 24, and the plant was operated at a total oxygen concentration of 27%. At this time, the flow velocity of the air supplied to the ventilated constriction section 22 around the outlet of the concentrate chute was 110 m/s.
The performance evaluation value η of the concentrate burner was measured in the same manner as in Example 1 and was 97%. Next, the amount of oxygen supplied from the concentrate chute 24 was increased to bring the oxygen concentration in the total blast to 38%, and the flow velocity of the air supplied to the ventilated constriction section 22 around the outlet of the concentrate chute became 61 m/s. At this time, the performance evaluation value η of the concentrate burner decreased to 94%. Therefore, the position of the flow velocity adjustment cone 33 provided at the outer lower part of the concentrate chute was lowered slightly so that the flow velocity of the air supplied to the ventilated constriction part 22 around the outlet of the concentrate chute was 100 m/s, and the measurements were taken again. The value of η was as good as 97%. These results are shown in Table 3.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the performance of a concentrate burner for self-smelting can be evaluated quantitatively, quickly, and economically, so new measurements can be carried out in place of conventionally used concentrate burners. If you replace the burner with a concentrated concentrate burner, you can easily evaluate whether the burner has superior performance or not, and based on the evaluation results, you can decide on the enrichment method for enriched oxygen or the area around the concentrate chute outlet. It is possible to maintain concentrate burner performance at a high level by changing operating conditions such as keeping the flow rate of air supplied to the ventilate section above a certain value, and it is possible to maintain concentrate burner performance at a high level. If it is a burner, the value measured at the position of the measurement point inside the shaft at a position higher than the height near the shaft exit is applied to the calculation formula for η evaluation, and the value is 97%.
If the above values are obtained, the metallurgical reaction within the shaft has essentially finished, which has the advantage of contributing to the design of a flash furnace with a short shaft height and low energy loss. be.

[Brief explanation of drawings]

Figure 1 shows the measurement position of the oxygen partial pressure in the flash furnace and the oxygen partial pressure measured at that measurement position in relation to the distance from the shaft entrance, and Figure 2 shows the depth direction of the settler part. Figure 3a is a cross-sectional view of an improved concentrate burner used in an example of the present invention, and Figure 3b is a cross-sectional view of a conventional concentrate burner used in an example of the present invention. It is a diagram. 1...Shaft part, 2, 3, 4, 5, 15...
Measurement hole, 6...Settler part, 7, 8, 9, 10,
11,12...=exit, 13,14...=exit,
16...〓, 17...〓, 18...Settler section directly below the shaft section, 21...Concentrate burner body, 2
2... Bentuary-shaped constriction part, 23... Burner cone, 24... Concentrate chute, 25... Heavy oil burner, 26... Dispersion cone, 27... Blower pipe,
28... Oxygen blowing pipe, 29... Opening area adjustment spacer, 30... Guide vane, 31... Lower end surface, 3
2...Lower end, 33...Flow rate adjustment cone, 34...
Hanging rod, 35...stop metal fitting.

Claims (1)

[Claims] 1 Using an oxygen probe with a built-in oxygen concentration battery, we measured the partial pressure of oxygen in the melt droplets falling through the space below the shaft in the flash furnace and the content of the pine extracted from the pine outlet just below the shaft in the settler section. After measuring the oxygen partial pressure of Performance evaluation method for concentrate burners for flash smelting furnaces.