JPS6126736A - Method for judging end of operation of copper converter - Google Patents

Abstract

PURPOSE:To judge more accurately the end of operation of a copper converter as compared with a visual judgment, to lower the S content in crude copper and to reduce the loss of copper by finishing the operation of the copper converter after the lapse of a prescribed time since the time when the rate of evaporation in a waste heat boiler for the converter begins to decrease suddenly. CONSTITUTION:The extent of evaporation per unit time in a waste heat boiler for a copper converter is measured, and the time when the extent of evaporation begins to decrease suddenly in the last stage of a copper manufacturing stage is detected. The opration of the copper converter is finished when a decrease in the extent of evaporation per unit time reaches a preset value. By this end judging method, the end is judged more accurately as compared with a visual judgment, so the S content in crude copper is lowered, and the loss of copper due to the formation of copper oxide is reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for determining the end point of copper converter operation.

[Conventional technology]

Conventionally, the end point of the copper production period in copper converter operation has been determined by inserting a rod through the tuyere and examining the color of the white scum or blister deposited on the tip, or by checking the color of the gas coming out of the converter mouth. The decision is made based on the operator's many years of experience. However, this method requires skill, has individual differences, and has large variations in each determination, so a quantitative and objective end point determination method using a meter has been desired. In particular, the quality of determining the end point of the copper production stage has a large impact on operational performance, so quantitative accuracy is required. For example, if the amount of blown air is insufficient, the S content in the blister copper will increase, which will have an adverse effect such as requiring time for the desulfurization treatment in the refining furnace in the next step. Furthermore, if the amount of air blown is excessive, the oxidation loss of copper will increase, and the copper oxide will react when inserting the needle in the converter operation in the next heat, causing problems such as generation of a large amount of SO gas.

Therefore, various methods of quantitatively determining the end point using instruments have been studied, and the following three methods have been proposed.

(1) Method using a blow-in air indicator (2) Method using an exhaust gas SO concentration meter However,
In method (1), the theoretical amount of air required varies depending on the amount and composition of the charges (acupuncture needles, cold materials, etc.) and output products (blister copper, Hime, dust broom), and variations in oxygen efficiency. Determining the end point based on the calculated injection amount based on a formula is less accurate than conventional determination based on the experience of a skilled worker, and there is a risk of interfering with the next process. Furthermore, in method (2), it is difficult to directly suck only the smelting exhaust gas exiting from the furnace mouth, and the detected SO concentration value fluctuates due to variations in the amount of free air mixed in, resulting in a lack of accuracy. In addition, a method has been proposed in which the rapid change in SO concentration that appears at the end of the copper production stage is used as the criterion for determining the end point, rather than the absolute value of the S02 concentration in the exhaust gas (Japanese Patent Application Laid-Open No. 1983-1993).
-84828), copper converter exhaust gas contains a large amount of dust, so problems such as clogging of the suction pipe of the SO concentration meter frequently occur, and maintenance of the SO concentration meter requires a great deal of effort in actual operation. It has the above drawbacks.

[Problems to be solved by the present invention]

The present invention eliminates the drawbacks of the conventional end point determination method for copper converter operation as described above, and provides quantitative and highly accurate methods that are advantageous in actual operation without using an SO concentration meter that requires laborious maintenance. The purpose of this study is to provide a method for determining the end point of copper converter operation.

(Means for solving the problem) In order to achieve this objective, the present invention measures the amount of evaporation per hour of the waste heat boiler, which is ancillary equipment of the copper converter. Provided is a method for determining the end point of copper converter operation, which is characterized in that the point in time when the amount of evaporation per hour starts to decrease is detected, and the end point is determined when the amount of decrease in the amount of evaporation per hour reaches a preset value from that point.

The present inventors discovered that the evaporation change curve of the converter waste heat boiler, which recovers exhaust gas heat from the copper converter, shows a unique pattern in the Hime-making period and the Copper-making period, with a particularly rapid evaporation rate at the end of the steel-making period. We focused on the fact that the process of decrease is common to all heats, and shows a nearly linear change with respect to elapsed time. 1st
A typical example is shown in the figure. In FIG. 1, a curve V shows a change in the amount of evaporation per hour in the boiler, and a curve S shows a change in the S concentration in the molten bath. Point A in FIG. 1 is the point at which the evaporation amount begins to decrease rapidly, and after this point, the evaporation amount decreases almost linearly with respect to the air blowing time.

At the point when the amount of evaporation starts to rapidly decrease, it can be judged that the reaction in the furnace is almost the same in all heats, and at the point when the rapid decrease in the S content in blister copper slows down and becomes almost steady. In the case of a converter with a processing capacity of 200 tons, the amount of decrease in evaporation per hour is measured from point A! , 7t. Therefore, the point at which a rapid decrease in the amount of evaporation per hour begins (A in Fig. 1)
An accurate end point can be obtained by detecting a point) and determining the end point when the amount of decrease in evaporation reaches a preset value. As mentioned above, the appropriate range of decrease in the amount of evaporation per hour for the end point is 200 in the case of a converter.
7t, but if the scale of the converter changes significantly, the value will be different, but this appropriate value can be easily found empirically.

(Effects of the Invention) According to the method for determining the end point of copper converter operation of the present invention described in detail above, it is possible to quantitatively determine the end point using a meter with higher accuracy than the conventional visual determination by an operator. This has the great effect of reducing the content of blister copper by 8% and preventing copper oxidation loss.Also, since an SO concentration meter is not used, there is no need for maintenance, making it suitable for actual operation. It also has the effect of being suitable.

〔Example〕

Example 1 208.5 tons of copper plated with 51.8 wt. The amount of evaporation in the boiler began to rapidly decrease, and when the amount of decrease in evaporation amount reached 4.7 tons per hour, the blowing of air was stopped and the end point was determined.

As a result, the S content was 0.018% by weight, and the 02 content was 0.01% by weight.
178 tons of blister copper containing 54% by weight was obtained, and the desulfurization treatment time in the refining furnace in the next step was extremely short, 5 minutes.

Example 2 Copper plating with 0u grade 5523% by weight was applied to each heat) 2] 0 Soil 1
The present invention detects the point in time when the amount of boiler evaporation starts to decrease rapidly during the copper making period, and the end point is when the amount of decrease in evaporation amount reaches 4.7 tons per hour from that point. The converter operation was performed 25 times using the end point determination method. Figure 2 shows the weight percent of S in the blister copper obtained in each heat. In addition, there is a conventional visual judgment method in which copper plating with the same surface quality as above is charged with 210 soil of each heat, and the worker observes the color of the rod inserted through the weak opening and the color of the gas coming out of the furnace mouth. S of blister copper obtained as a result of 19 converter operations in which the end point was determined by
The weight percentages are shown in FIG.

It is clear that the end point determination method of the present invention lowers the S content of blister copper, and also significantly reduces its variation.

[Brief explanation of drawings]

Figure 1 shows the amount of boiler evaporation and S of the bath during the copper production stage of copper converter operation.
FIG. 3 is a diagram representatively showing the relationship with concentration. Figure 2 is a diagram showing 8% of blister copper obtained by implementing the end point determination method of the present invention, and Figure 3 is a diagram showing 8% of blister copper obtained by implementing the conventional end point determination method. FIG. Agent: Patent Attorney Katsunari Donakamura ゛・,”,”(,',')”−
r', I/Figure 1 Air blowing time (8)

Claims (1)

[Claims] (1) During copper converter operation, measure the evaporation amount per hour of the converter waste heat boiler, detect the point at which the evaporation amount starts to decrease rapidly at the end of the copper production stage, and from that point on, the evaporation amount per hour decreases. A method for determining the end point of copper converter operation, characterized in that the operation ends when the width reaches a preset value.