Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Sintering which includes a chemical reaction
Patent
1995-04-13
1996-11-12
Jordan, Charles T.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Sintering which includes a chemical reaction
266164, 266166, 266172, 423 42, 75643, 75429, C21B 1102
Patent
active
055749569
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an apparatus for oxizidizing treatment of molten matte and at the same time directly smelting sulphidic concentrate in a refractory-lined metallurgical liquid bath reactor, e.g. a converter, into which oxidizing air is introduced below the surface of the liquid bath. The invention can be used for instance for producing copper from sulphide ores.
Thus, the present invention relates to a method of producing metal from sulphidic ore or sulphidic ore concentrate, wherein normally the concentrate is first treated in a smelting reactor, e.g. a reverberatory furnace, whereby molten matte is formed, whereafter the molten matte thus formed is treated in a liquid bath reactor, e.g. a converter, by means of oxidizing smelting for producing metal.
In conventional converter processes which have been developed during decades and are per se well known and easily controlled, surplus heat is produced when the molten matte is treated in the liquid bath reactor, which heat can be used for instance for smelting scrap. During the last decades attempts to use this surplus of heat have been made at several smelting plants for direct oxidizing smelting of fresh sulphidic concentrate in the liquid bath reactor. In direct oxidizing smelting of sulphidic concentrate, such as normal flotation concentrate, in a liquid bath reactor, converter or similar smelting means, for instance of shaft furnace type, with not preheated air, problems with the energy balance arise, because the oxidation reactions do not give sufficient heat for the whole converter process. External energy has to be supplied to the process. This energy can be supplied by addition of
It is known, for oxidizing smelting of matte in a conventional converter, to directly smelt at the most approximately the same amount of moist sulphidic concentrate as the supplied amount of molten matte. Then, the molten matte supplies the additional energy needed for direct smelting of the concentrate. For smelting larger amount of concentrate than molten matte, other energy supplied from an external source is needed.
The use of oxygen gas, e.g. air enriched by 35-60% oxygen gas, as an external source of energy is a simple, effective and modern method. However, injection of oxygen-enriched air by means of conventional tuyeres disposed below the liquid bath in the converter causes damages both to the lining and the tuyeres, because of the extreme heat which is produced around the tuyeres. Thus, their durability limits the enrichment of the air by oxygen. As the content of oxygen in the air blast in a converter today should not exceed 30% O.sub.2, this means that autogenous smelting of concentrate can not be achieved by the injection of oxygen-enriched air.
In order to prevent damages to the lining, the lining around the tuyeres can of course be cooled by water. However, this increases the heat losses significantly and further increases the O.sub.2 demand. Furthermore, the water cooling below the surface of the bath is a potential security risk.
It is, of course, possible to use fossil fuels to increase the heat in the converter and achieve heat balance. However, this results in a larger flow of exhaust gas and more diluted SO.sub.2 -containing gases, which increases the costs of recovery of sulphur as sulphuric acid in the sulphuric acid plant.
The object of the present invention is to provide a method and an apparatus in which the drawbacks described above have been minimized.
The object of the present invention is particularly to provide a flexible method for direct smelting of sulphidic concentrate.
The method according to the present invention for oxidizing treatment of molten matte and at the same time directly smelting sulphidic concentrate is characterized in that, for additional supply of energy in order to achieve thermal balance or increase of capacity in the liquid bath reactor, at least a portion of the sulphidic concentrate is introduced into the gas phase of the liquid bath reactor together with oxygen gas or oxygen-enriched air
REFERENCES:
patent: 3850620 (1974-11-01), Themelis et al.
patent: 4416690 (1983-11-01), Richards et al.
patent: 4544141 (1985-10-01), Mackey et al.
Chi Anthony R.
Jordan Charles T.
Outokumpu Engineering Contractors Oy
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