US 3902895 A
A method for the separation of companion elements of a nonferrous metal dissolved in a liquid bath, particularly in copper, through conversion of the companion elements into compounds which are insoluble in the liquid metal, includes blowing-on of reaction gases. More specifically, the reaction gases are blown on through at least one gas jet approximately perpendicularly to the essentially smooth bath surface and with such great force that the melt, rotating essentially like a torus about the blower impression located at the stagnation point of the jet together with the gas jet, results in a reaction unit with definite material transition, limited by the convection conditions of the system.
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Description (OCR text may contain errors)
United States Patent 1191 Wuth Sept. 2, 1975  METHOD FOR THE TREATMENT OF 3,527,449 9/1970 Worner 75 92 FUSIBLE NON FERROUS METALS 3,582,057 6/1971 B8315 61 a1 266/34 L 3,666,440 5/1972 K0110 Ct a1. 75/76 PARTICULARLY COPPER BY MEANS OF A 3,690,634 9/1972 Enya 266/34 L BLOWING-0N 0F REACTION GASES 3,743,263 7 1973 Szekely 266 34 A Inventor? Wolfgang Wuth, Tautenburger Strasse 45, 1 Berlin 46, Germany Filed: Feb. 11, 1974 Appl. No.: 441,670
Foreign Application Priority Data Feb. 9, 1973 Germany 2306398 US. Cl. 75/76; 75/72; 75/92; 75/93 E; 266/34 A Int. Cl. C22B 15/00; B6OG 11/56 Field of Search 75/76, 74, 72, 92, 93 R, 75/93 E; 266/34 L, 34 M, 34 A References Cited UNITED STATES PATENTS Primary Examiner-Walter R. Satterfield Attorney, Agent, or Firm-Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson [5 7] ABSTRACT A method for the separation of companion elements of a nonferrous metal dissolved in a liquid bath, particularly in copper, through conversion of the companion elements into compounds which are insoluble in the liquid metal, includes blowing-on of reaction gases. More specifically, the reaction gases are blown on through at least one gas jet approximately perpendicularly to the essentially smooth bath surface and with such great force that the melt, rotating essentially like a torus about the blower impression located at the stagnation point of the jet together with the gas jet, results in a reaction unit with definite material transition, limited by the convection conditions of the system.
5 Claims, 1 Drawing Figure PATENTEIilSEP 2M5 METHOD FOR THE TREATMENT OF FUSIBLE NON-FERROUS METALS, PARTICULARLY COPPER, BY MEANS OF A BLOWING-ON OF REACTION GASES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for separating companion or accompanying elements dissolved in a liquid bath of a non-ferrous metal, particularly in copper, and more specifically to such a method in which reaction gases are blown on to provide the companion elements in compounds which are insoluble in the liquid metal.
2. Description of the Prior Art The separation of companion elements dissolved in liquid metals, above all in copper, and particularly of accompanying metals with the aid of reaction gases was previously carried out in a manner wherein the liquid non-dissolved metal containing the companion metals was supplied to a revolving reverberatory furnace, a refining boiler or a stationary hearth-type furnace, and held at a temperature above the melting point, while at the same time air or air enriched with oxygen was blown into the bath. A substantial disadvantage of this method resides in the relatively long blowing times which result, and in that upon the introduction of the reaction gases directly into the metal bath, the nozzle openings facing or immersed in the bath become clogged over a period of time due to the solidification of the metal in the area of the nozzle openings, so that an accurate control of the duration of treatment becomes substantially impeded.
In the German patent application 1,122,090, which has been laid open for public inspection, a method is disclosed for refining raw or pig iron and other iron melts wherein oxygen-containing carburated fuel is employed, in which the oxygen-containing gases are blown on approximately perpendicularly to the surface of the bath which is covered with a relatively thick layer of a metallurgical slag, and with such velocity that the bath surface tears open at the point of incidence of the blower jet causing large quantities of metal to be sprayed into the furnace atmosphere in drop form. After reacting with the oxygen-containing gases of the furnace, these drops fall into the slag and are subjected to a good and repeated reaction with the metallurgical slags covering the bath due to the fine distribution of the drops over a large surface of the bath. Such a method is not applicable for the separation of companion elements of non-ferrous metals, particularly copper.
SUMMARY OF THE INVENTION The invention has as its primary object, in addition to avoiding the disadvantages of the known method, of shortening the blowing times upon the separation of companion elements in non-ferrous metals, particularly copper.
Another object of the invention is to provide reproducible material transfer conditions, and thereupon, the prerequisite for a continuous manner of processing non-ferrous metals.
The foregoing objects are achieved, according to the present invention, in that reaction gases are blown through at least one gas stream, approximately perpendicularly to the substantially smooth surface of the bath, with a sufficiently great jet force that the blowing impression which arises at the stagnation point of the jet or stream on the surface of the bath, in the melt rotating in the manner of a torus, produces together with the gas jet, a reaction unit with definite material transition limited by the convective conditions of the system.
In this connection, the field of flow of a gas jet blown onto the surface of the bath and the field of flow described in greater detail in the following, while the belt rotates as a torus, together form a reaction system which, advantageously, beyond the area of the gas phase as well as in the area of the liquid phase, ensures high material transition speeds which lead to shorter blowing times.
BRIEF DESCRIPTION OF THE DRAWING Other objects, features and advantages of the invention, along with its organization, construction and operation will be best understood from the following detailed description taken in conjunction with the accompanying drawing on which there is a single figure showing three jets or lances blowing reaction gases onto the surface of a bath of non-ferrous metal.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing a reaction system, such as that generally set forth above, will be described substantially through the two convection streams which are in an equilibrium of forces with respect to each other of the gases blown through the nozzle 8 and in a predetermined area located about the point of impingement of a bath having a surface 10 and a depth 9. The convection stream 3 of the melt is a result of the convection stream of the gas jet 4 which also transports forward or away, respectively, the gaseous participants. At the junction of one of each of the jets there results on the bath surface 10 a blowing impression 2 of a predetermined diameter and depth 6, whereby substantially an equilibrium of forces is built up between the jet force and the contact force of the liquid. The friction of the jet deflected at the stagnation point 1 on the wall of this blow impression causes a reaction system 5, in cooperation with the walls of the furnace chamber, or with several jets of gas with the limiting line of the adjacent reaction system, a blower impression upward on the bath surface away from the impression and on the furnace wall or directed downwardly on the system limiting line in reference to the blower impression, accordingly in the essentially torus type of rotating flow 3. In this manner, constantly fresh melt arrives from the bottom of the bath at the bath surface where it may react with the reaction gases.
It is known that it is necessary, for example, for the removal of companion elements from liquid copper to introduce oxygen into the melt and to bring the oxygen dissolved in the copper melt into reaction with the impurities dissolved in the melt, and to bring excess oxygen out of the melt. If, on account of special measures, the individual steps should take place rapidly, the total operation for the removal of companion elements from liquid copper is also rapid. The reaction system 5 described above makes such rapid steps possible. For example, if the density ofthe stream of material of the oxygcn going into the melt, in the case of the oxidation with air, amounts to approximately 0.1 kgm zf A similar value is attained upon the reduction of oxygencontaining copper for the material stream density of the oxygen leaving the copper, if the gas jet consists predominately of hydrogen and carbon monoxide.
The jet force which is achieved by means of the blower lance 8 determines the effective range of a reaction system 5. The greater the diameter is of the nozzle located in the lance head, in the case of otherwise similar conditions of flow, the greater is also the jet force and the diameter of the impression and thereupon the dimensions of the convection fields of the melt.
Optimum material flow densities are attained if, in accordance with an advantageous construction of the invention, the melt bath of the reaction unit perpendicularly to the jet direction has a diameter of approximately 2 to 5, advantageously three, blower impression diameters 2, and the depth 9 corresponds to a value of approximately half of the melt diameter, advantageously 1.5 blower impression diameters.
If several blower lances are arranged adjacent and/or consecutively with respect to each other, according to a further advantageous construction of the invention, the distance from blower jet to blower jet corresponds approximately 2 to 5 times, preferably triple, that of the blower impression diameter.
With the values mentioned according to the foregoing invention, it is a question of the most favorable adjustment. With greater values, the reaction period is prolonged as, due to the larger volume of the bath, the equalization of concentration within the bath is necessarily prolonged. This is, however, still economical with large installations so that greater values still lie within the scope of the invention.
In order to prevent splashing of the melt, a predetermined impression depth 6 of the impression of the blower must not be exceeded. As the depth of the blower impression is increased, both with increasing force of the jet as well as through decreasing distance 7 between the nozzle aperture and the bath surface 10, the distance must be increased with increasing force of the jet, and vice versa. The critical depth of impression during which the best possible convection conditions prevail in the melt, without the melt splashing, is not a specific value for every metal, but is dependent substantially on the type of the reaction being carried out. Therefore, for the oxidation of copper, a value is measured of approximately l.8 cm; during the reduction, however, only approximately 1.5 cm. The measure of the splashing is limited by economical factors as, for example, Wear of the masonry, addition of operating apertures, etc. A small amount of splashing is of no importance for carrying out the method of the present invention. It is particularlyadvantageous in the method if, in accordance with the invention, the jet force and the distance of the nozzle opening from the bath surface corresponding to the reaction to be carried out (oxidation or reduction) are so adjusted that the metal bath, at the point of blower impression, does not splash.
The utilization of a Laval nozzle, instead of a simple convergent nozzle has the known advantage of making possible through the disturbance-free later expansion of the jet of higher discharge speeds and, thereupon, higher jet forces under conditions otherwise the same. With reference to the present invention, the later expansion free from disturbance out of a Laval nozzle has the advantage of increasing the limit value of the critical jet force or decreasing the value of the critical distance; nozzle opening-bath surface. The dimensions of the Laval nozzles must be adapted for this purpose to the gas pressures utilized, so that compression shocks are avoided.
The oxygen intake of liquid copper, for example, is so rapid with the aid of the aforementioned reaction system, that the ordinary limit value of approximately 1 percent is attained after approximately 4 minutes. The oxidation of the impurities dissolved in the copper is, indeed, slower by means of the oxygen dissolved in the copper, and is, however, accelerated by means of higher oxygen content in the copper. It is, therefore, to the purpose, particularly with high requirements as to the purity of the refined copper with respect to predetermined impurities, to permit the oxygen content to increase up to just below the saturation limit.
As the beginning may be due to the fact that the reaction of the liquid metal bath, for example copper, takes place with the reaction gases substantially in the area of the impression point, the surface of the impression point, however, is determinable, and the possibility is obtained of calculating with the aid of measured densities of material of the reaction system, the yield capability of corresponding continuous or discontinuously driven reactors. On the basis of such an example, the invention is to be described in detail hereinbelow.
On a metal bath of liquid copper, for the separation of the dissolved companion metals, air is blown on, whereby the jet force and the spacing of the nozzle opening and bath surface are so adjusted that an impression of 1.8 cm results without notable splashing occurring. In this connection, a material flow density of 0.1 kg of oxygen per square meter of blower impression surface and seconds in the copper bath were produced. The yield of the reactor is the product of this value and the specific reaction surface in m /m", which the reaction system makes available. It is characteristic for the last-mentioned size that it becomes smaller with increasing blower impression diameter. For this reason, the distances of nozzle opening to bath surface should not be too great, the number of blower lances not too small. For a production of 100,000 Jato of refined copper, corresponding to 3.85 X 10' kg oxygen per second, if oxidized up to a content of 1 percent oxygen, for example, 20 blower lances are required with blower impression diameters of 0.157 meters.
If the production, for example, is carried out in two continuously operated furnaces with two rows per each five lances, on account of the foregoing geometrical de scription of the reaction system, the furnace width of 0.157 m 3 5 2.36 m and the bath depth 0.157 m 1.5 =0.236 m. For the correlated reduction, the corresponding holds true. The further dimensions of the furnace are, in each case, adapted to the usual technical conditions as to heat and metallurgy for the processing of the corresponding metal. In the case of a continuously operated furnace, it may be suitable to incline the blower lances in the direction of passage of the melt to the extent that the flow-through of the metal is supported without the depth effect of the metal rotating like a torus about the blower impression being affected thereby.
Although I have described my invention by reference to a particular illustrative embodiment thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. 1 therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art I claim:
1. In a method of separating companion elements of a non-ferrous metal dissolved in a liquid bath, particularly in copper, wherein the companion metals are converted into compounds which are insoluable in the liq uid metal by blowing reaction gases onto the liquid bath, the improvement therein comprising the step of:
forming a reaction unit by directing a gasjet approximately perpendicular to the smooth bath surface and with a force sufficient to cause upward blowing of the gases and a vertical toroidal-like rotation of the melt and directed upwardly about the blower impression located at the stagnation point of the jet which together with the gas jet effects a reaction unit with definite material transition limited by the convective conditions of the system, the reaction unit having a diameter in the range of two to five times the diameter of the blowing impression diameter and a depth of approximately half of the melting bath diameter 2. The improved method of claim 1, wherein the bath is copper and the gas includes oxygen, comprising the steps of: adjusting the jet force and jet-to-surface distance to prevent direct splashing of the bath on the impression point.
3. The improved method of claim 1, wherein the bath is copper and the gas includes oxygen, comprising the step of increasing the oxygen content of the bath, in accordance with the required minimum content of one or more companion elements, to just below the saturation limit.
4. The improved method of claim 1, wherein the reaction unit is formed with a diameter of 3, and a depth of 1.5, times the impression diameter.
5. The improved method of claim 1, wherein the step of forming a reaction unit is further defined by the steps of:
directing several aligned gas jets perpendicularly to the bath surface at a spacing of two to five times the blower impression diameter,