JPH0224898B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a technology for converting the fuel for a copper smelting flash furnace for smelting copper concentrate from conventional mineral oil to solid carbonaceous fuel. The present invention is characterized in that it aims to replace mineral oil 100% without particularly using pulverized coal. Background of the Invention In a flash furnace for copper smelting, copper sulfide concentrate (hereinafter referred to as copper concentrate) is charged together with flux, etc., and air or oxygen-enriched air is blown in at the same time, and the reaction heat generated during oxidation is used as the majority of the heat source. Copper concentrate is melted and smelted by oxidation to produce 〓 (matsuto), which is a molten substance mainly composed of copper sulfide and iron sulfide, and 〓 (slag), which is a molten substance mainly composed of silicate of iron oxide. It is a furnace. At this time, the exhaust gas containing sulfur dioxide gas generated during the reaction is used as a raw material for producing concentrated sulfuric acid. Flash melting furnaces are widely used in Japan because they utilize the heat of the oxidation reaction of concentrates, resulting in lower fuel consumption and better environmental management than other types of furnaces. As mentioned above, flash melting furnaces use the heat of the oxidation reaction of the raw materials as their heat source, but in the past, heavy oil was burned to make up for the lack of heat. However, with the recent rise in heavy oil prices, fuel conversion measures using alternative fuels such as pulverized coal are being actively promoted. However, in copper smelting flash furnaces, substantially all of the heavy oil has not yet been replaced, and the replacement rate remains at an unsatisfactory value.In addition, considerable ancillary equipment and costs are required, which makes it difficult to replace heavy oil. Less is. Prior Art and Its Problems Conventionally, pulverized coal has been considered exclusively as a substitute for mineral oil combustion in flash-smelting furnaces. This is because extremely fine particles such as pulverized coal (-200 mesh are 80
This is because it was thought that it could only be used if it was (~90%). Furthermore, at normal flash-melting furnace temperatures, it is thought that it is not possible to completely replace raw materials with low combustible components such as S, so the possibility of using coke powder was not considered. Therefore, pulverized coal was considered as a potential alternative fuel. However, the use of pulverized coal has many unsatisfactory points as follows: (1) When using pulverized coal, pulverized coal is produced by drying and pulverizing coal, which requires pulverizing equipment and increases the cost of pulverizing. It becomes a huge thing. (2) Special safety considerations are required to prevent explosions during the production and handling of pulverized coal, including transportation. (3) When pulverized coal is used, it has the drawback that it is an ultra-fine powder that is carried by air currents and scattered toward the furnace exit, and is not completely combusted in the shaft section, but instead is combusted in the waste heat recovery section at the furnace exit. (4) The damage caused by the deterioration of the working environment due to crushing is significant. (5) Stable airflow transport of pulverized coal is difficult. OBJECT OF THE INVENTION The present invention provides a method for removing mineral oil even by solid carbonaceous fuel that has not been crushed to extremely fine particle size, such as pulverized coal.
The aim is to establish an operating method for flash-melting furnaces that enables 100% replacement. SUMMARY OF THE INVENTION The inventor of the present invention has completely unexpectedly discovered that in a high-temperature hot-air flash furnace in which air or oxygen-enriched air is preheated to 650°C or higher and is blown into the flask, fine particles such as pulverized coal are It was discovered that 100% mineral oil replacement can be achieved even by using coarse solid carbonaceous fuel.
As far as the inventors are aware, there is no precedent for achieving 100% fuel conversion from heavy oil to solid carbonaceous fuel in a copper smelting flash furnace. Thus, the present invention involves charging copper concentrate, flux, and other charges, simultaneously blowing air or oxygen-enriched air preheated to above 650°C, and using solid carbonaceous fuel (as an auxiliary fuel). Provided is a method for operating a copper smelting flash-smelting furnace characterized by using only pulverized coal (excluding pulverized coal) and replacing 100% mineral oil. Here, the solid carbonaceous fuel includes various grades of coal other than pulverized coal, charcoal, and coke. The preferred solid carbonaceous fuel for use in the present invention is granular coke and/or size 40
It is lump grain powder and low quality coal of less than mm. Pulverization to pulverized coal level is not necessary. Powder coke refers to powder coke, granular coke, or a mixture of the two, and includes various types of coke other than the sized lump coke normally used for steelmaking, but especially when coke is extracted from a coke oven. It is desirable to use precipitated coke powder, which is coke mixed with powder particles that is a by-product during the cooling process.
Table 1 shows the particle size distribution, components and calorific value of the precipitated coke powder. A flow sheet for producing precipitated coke is shown in FIG. As the powder coke, in addition to the above-mentioned precipitated coke powder, undersieve coke of approximately 10 mm under size can be used alone or in combination. Lump powder low-quality coal refers to coals other than pulverized coal and sized high-grade coal, and particularly lignite is taken as an example. Table 1 shows the particle size distribution, components, and calorific value of Wanbo coal (produced in Australia), which is the lignite used in the present invention.

【table】

[Table] Specific Description of the Invention Preferred embodiments of the present invention will be described below. FIG. 2 shows the flow until the copper concentrate and solid carbonaceous fuel are charged together into the flash melting furnace. As a blending hopper group 1, a copper concentrate hopper 2, a hopper 3 for granular coke as a representative solid carbonaceous fuel, and a flux hopper 4 are arranged side by side, and each is brought in from an appropriate source. For example, granular coke is carried into the hopper 3 from the granular coke mine 5 by a bucket crane or the like. A cutting device 6 such as a constant feed conveyor is provided below each hopper, and a predetermined amount of raw material is cut out from each hopper. The cut raw material components are transferred to conveyor 8
is fed into the receiving bin 10 by. Conveying equipment such as a chute or a vibrating conveyor may be used instead of the carrying conveyor. The charging material from the receiving bin is fed into the dryer kiln 12 and then into the cage mill 14.
The air flow is transported through the conduit 15 by the air flow. By mixing the solid carbonaceous fuel with the copper concentrate or the like at a stage upstream of pneumatic transport, a very uniformly mixed charge mixture is produced. The pneumatically transported mixture is supplied to the head bin 20 via the chamber 16 and the cyclone group 18. Headbin 20
The charge is introduced from the bottom of the flask through the flask concentrate burner 22, for example by means of a boiler conveyor. Collected dust from the cyclone via the dryer is also charged. The flash furnace 30 includes a shaft 31, a settler 32, and an uptake 33.
It is of a well-known structure and is also equipped with hot air blowing means (not shown). In this way, the copper concentrate, solid carbonaceous fuel, flux, etc. in a predetermined mixing ratio are charged into the flash melting furnace in an extremely uniformly mixed state, and the hot air inside the flash melting furnace allows the melting to be carried out very efficiently and effectively. reacts quickly, ensuring the required calorific value. In the flash-melting furnace, the oxidation reaction using high-temperature hot air, which was previously developed by the applicant, is carried out. This means that in conventional flash melting furnaces, the temperature of the blown air or oxygen-enriched air was 350 to 650°C;
℃ or above, preferably 900 to 1000 ℃, the copper production capacity has been successfully increased significantly, and the present invention is the first to use 100% solid carbonaceous fuel other than pulverized coal as a fuel oil conversion measure. It has been found to be highly adaptable for use. High-temperature hot air can be easily obtained, for example, by a regenerative hot-blast furnace that utilizes the combustion heat of B gas, mainly CO, generated from a smelting furnace for iron or ferroalloy smelting. As mentioned above, in the present invention, granular coke is used as one of the preferred fuels. It has been thought that coke cannot be used for high-speed combustion because of its low volatility and high ignition point.
Also, an flash-melting furnace was said to be a furnace in which the reaction should be completed while the charge is descending within the shaft. Therefore, as mentioned above, pulverized coal combustion has conventionally been considered as an alternative to mineral oil combustion in flash-smelting furnaces. However, the present inventors have discovered that even granular coke can be used as an auxiliary heat source in a flash furnace under conditions where the reaction rate in the furnace is sufficiently high due to high-temperature hot air, and that by charging granular coke, Powdered coke will float on the surface of the settler, but stable operation can be maintained by controlling the furnace conditions and the amount of coke powder charged so that the floating amount does not tend to increase. It was confirmed. Furthermore, even if the slag temperature and mat temperature are slightly lower than in the case of conventional mineral oil combustion, there is no problem in tapping (this is probably due to a decrease in the amount of magnetite in the furnace). It was confirmed that there was almost no discharge of unburned coke even if it was floating on the surface of the hot water, and that a sufficiently high thermal efficiency could be maintained. The most desirable aspect of the present invention is as follows:
Coke powder is added at a predetermined mixing ratio to the most upstream side of the copper concentrate/flux charging system to the flash furnace. Although the coke is charged into the flash-smelting furnace through an ore burner, the scope of the present invention is not limited thereto; it may be blown into the furnace through a separate system of granular coke conveying and charging equipment, or through a dedicated burner. It also includes cases. The most preferable example of the coke powder is precipitated coke whose generation flow sheet is shown in FIG. 1, but the coke is not limited to this. By adding coke powder and/or low-quality coal particles with a size of 40 mm or less to the charging system for copper concentrate, flux, etc. upstream of the dryer kiln and pneumatic conveyor, a large number of coal particles are added to the charging system for copper concentrate, flux, etc. before entering the furnace. Because of this mixing chance, when it enters the furnace, it is completely mixed with the copper concentrate, which is a sulfide that burns well in the furnace, and can be burned in the furnace more quickly. The present invention has made it possible to replace 100% of the total amount of heavy oil with solid carbonaceous fuels other than pulverized coal, which was previously impossible. Powdered coke and/or lumpy powdered low-quality coal are charged into the flash furnace together with the copper concentrate without any pretreatment or special charging equipment, resulting in a very good 〓-〓-forming reaction and Maintain the required temperature. This was achieved for the first time without any problems in a flash melting furnace that uses high-temperature hot air of 650℃ or higher, and this flash melting furnace uses high-temperature hot air to create an atmosphere that extremely speeds up the reaction rate. Therefore, it was a rather surprising effect that solid carbonaceous fuel mixed with lump powder, even if it was not pulverized coal, could be completely burned very smoothly in the flash melting furnace without any special additional equipment or additional treatment. . Example The flash melting furnace was operated for about 3 months using precipitated coke instead of using heavy oil.

[Table] Compared to the previous results shown in the far right column, there was virtually no change in the grade or middle copper grade, and stable flash-smelting furnace operation was ensured. Effects of the Invention The present invention has been explained above, and the effects of the present invention can be summarized as follows: (1) 100% of the total amount of heavy oil can be replaced, reducing energy costs and contributing to future energy situations. successfully dealt with. (2) Pretreatment such as pulverization of the solid carbonaceous fuel is not required, and the need to provide separate charging equipment for the solid carbonaceous fuel can be eliminated. (3) It is safer than pulverized coal and provides a sanitary working environment. (4) The cost is low due to the use of precipitated coke, etc. (5) Precipitated coke powder has less volatile content than coal or petroleum, and requires less combustion air and exhaust gas for the same calorific value. (6) During operation, a small amount of solid carbonaceous fuel is observed floating on the hot water surface of the flash-smelting furnace settler, but if conditions are controlled to the extent that the floating amount does not increase, there is no problem; on the contrary, the slag It is expected that the layer will have the effect of reducing the copper content in the slag by constantly exerting a reducing action on the layer.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of the process of producing precipitated coke powder, and FIG. 2 is a schematic flow chart of the process of charging copper concentrate and solid carbonaceous fuel into a flash smelting furnace under mixing. 1: Preparation hopper group, 2: Copper concentrate hopper, 3: Powdered coke hopper, 4: Flux hopper, 5:
Powdered coke building, 6: Cutting and weighing device, 8: Carrying conveyor, 10: Receiving bin, 12: Dryer kiln, 14: Cage mill, 15: Air flow transport conduit,
16: Chamber, 18: Cyclone, 22: Concentrate burner, 30: Flash furnace, 31: Shaft, 32:
Settler, 33: Uptake.

Claims (1)

[Claims] 1. Copper concentrate, flux, and other charges are charged, and at the same time air or oxygen-enriched air is preheated to 650°C or higher and blown in, and solid carbonaceous fuel (however, (excluding pulverized coal),
A method of operating a copper smelting and flash-melting furnace characterized by replacing 100% mineral oil. 2. The method according to claim 1, wherein the solid carbonaceous fuel is granular coke and/or lump powder low quality coal having a size of 40 mm or less. 3. The method according to claim 2, wherein the coke powder is precipitated coke powder. 4. The method according to claim 2, wherein the low quality coal is lignite. 5. Powdered coke and/or lumpy powdered low-quality coal with a size of 40 mm or less are added to the charging system for copper concentrate, flux, etc. upstream from the copper concentrate dryer kiln and the pneumatic conveyor, and are added together with the copper concentrate, flux, etc. 3. The method according to claim 2, wherein the material is charged into a flash-melting furnace.