US3212880A

US3212880A - Method of carrying out metallurgical processes

Info

Publication number: US3212880A
Authority: US
Inventors: Rinesch Rudolf
Original assignee: Bot Brassert Oxygen Techik A G
Current assignee: Bot Brassert Oxygen Techik A G; BOT BRASSERT OXYGEN TECHIK AG
Priority date: 1959-12-24
Filing date: 1960-12-21
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19
Also published as: AT226753B; BE598355A; GB970859A; DD52149A; ES263212A1; OA01858A; LU39479A1; ES266188A1; GB970858A

Description

METHOD OF CARRYING OUT METALLURGICAL PROCESSES Filed Dec. 21, 1960 R RINESCH Oct. 19, 1965 4 Sheets-Sheet l INVENTOR. RU DOLF RI NESCH HIS ATTORN EYS Oct. 19, 1965 R. RINESCH 3,212,880

METHOD OF CARRYING OUT METALLURGICAL PROCESSES Filed Dec. 21, 1960 4 Sheets-Sheet 2 FIG. 2

INVENTOR. RUDOLF RINESCH BYd g 4;

HIS ATTORNEYS R. RINESCH 3,212,880

METHOD OF CARRYING OUT METALLURGICAL PROCESSES Oct. 19, 1965 4 Sheets-Sheet 3 Filed Dec. 21, 1960 INVENTOR. RUDOLF RI NESCH I-HS ATTORNEYS METHOD OF CARRYING OUT METALLURGICAL PROCESSES R. RINESCH Oct. 19, 1965 4 Sheets-Sheet 4 Filed Dec. 21,

INVENTOR. RU DOLF RI NESCH HIS ATTORNEYS United States Patent 3,212,880 METHOD OF CARRYING OUT METALLURGICAL PROCESSES Rudolf Rinesch, Linz, Austria, assignor to BOT Brassert Oxygen Techik A.G., Zurich, Switzerland, a company of Switzerland Filed Dec. 21, 1960, Ser. No. 77,336 Claims priority, application Austria, Dec. 24, 1959, A 9,393/59; Mar. 21, 1960, A 2,171/60; Apr. 14, 1960, A 2,837/60 Claims. (CL 7552) The invention relates to a method of carrying out metallurgical processes, e.g., for refining or pre-refining crude iron, for refining steel, for the preparation of alloys and the like.

Surface blowing processes utilizing oxygen gas, e.g., essentially pure oxygen, or oxygen-enriched gas, are already known in which crude iron is converted into steel in a crucible, open hearth furnace, converter or other reaction vessel having a refractory lining. In a preferred embodiment of such processes, an oxygen jet is blown on the surface of the bath or charge through a blowing tube or lance disposed vertically over the bath surface. It has also been proposed to introduce finely divided or particulate basic materials, such as lime, under pressure into the supply conduit for the blowing gas and to supply them to the bath together with the blowing gas. These known devices have various disadvantages. High requirements must be satisfied with regard to the purity and the physical characteristics of the materials supplied together with the blowing gas. If the materials contain combustible impurities, such as coal or iron particles, these impurities are ignited in contact with the oxygen and often cause a destruction of the hose lines. For this reason nickelchronium steels have been used for the supply conduits. As a result, the equipment becomes complicated and expensive; it is no longer possible to move the blowing tube or lance into and out of the reaction vessel with the ease required for the performance or refining processes. Besides, the equipment is subjected to considerable mechanical wear. Aggregates having a particularly uniform structure must be used to reduce this wear. Virtually only those substances which have a uniform spherical particle structure are suitable. These substances must be prepared in a special preliminary process or particularly finely divided admixtures must be used. Lime in this form, however, has the disadvantage of a great hydration.

It is an object of the invention to avoid these disadvantages. the field of application of processes and equipment using an oxygen-containing blast, e.g. oxygen or oxygen enriched gas, supplied from above and a supply of material in particulate solid, liquid or gaseous form. As applied to refining processes, the invention has as its object to provide a greater latitude in the use of the starting materials to be processed, particularly regarding the chemical heat content of the crude iron. It is a special object of the invention to enable the processing of crude irons having any desired carbon, phosphorus and silicon contents without need for an addition of scrap or with the possibility of adding any desired amounts of scrap. For this reason it is a special object of the method that it can be performed independently of a source of liquid crude iron.

The method, according to the invention, resides in that, at least during part of the blowing period, particulate solid, liquid and/ or gaseous material which is to be added to the charge or bath, is added to, and passes downwardly through, the interior of the blowing gas flowing through the tube or lance and the interior of the gas jet discharging from the tube or lance. It is believed that such ma- Another object of the invention is to expand "ice terials impinge on the surface of the charge or bath inside of the boundary of the reaction zone created by blowing of the gas jet on the surface of the charge or bath. The material is introduced through use of a tube or downcomer extending centrally downwardly of the lance within the conduit or passage provided for flow of the blowing gas. Where the material is in particulate solid form, e.g. finely divided lime, passage through the downcomer is effected under no pressure, i.e. gravity flow. However, where liquid or gaseous material is to be added it is effected under pressure.

While it is to be understood the invention is not so limited, it is believed that use of the centrally disposed downcomer results in impingement on the surface of the charge or bath of a jet having a configuration ranging from substantially a hollow truncated cone to a hollow cylinder, such jet providing an annular reaction zone with the added material contacting the charge inside of such reaction zone.

The method according to the invention avoids the disadvantages of the known equipment, in which finely divided material is introduced into the reaction vessel in suspension in the carrier gas. According to the invention there is no danger of combustion of inflammable mate rials and there is no mechanical wear from abrasion or other effects.

On the contrary, inflammable or combustible materials, such as coal, coke, oil, high calorific value gases, iron, silicon, maganese, aluminium or alloys of these substances can be introduced singly, in combination or in a mixture with slag-forming materials into the interior of the reaction zone if the chemical heat content of the charge to be blown is not sufficient for attaining or maintaining the desired reaction temperature. For instance, if crude iron having a low carbon content is to be converted into steel and scrap is to be melted at the same time, the heat of combustion of the impurities contained in the crude iron is not suflicient for attaining the refining temperature necessary for the conversion process, which temperature is 1600 to 1800 C., and for maintaining this temperature during the process. In such a case, coal in small lumps or other heat-delivering substances can be added according to the invention.

It has been proposed heretofore to add to the bath additional heat carriers, such as ferrosilicon, ferromanganese, natural gas, coal gas and oil gas or to add oil or coallike substances together with the refining agent. The use of heat-supplying ferrous alloys, however, is very expensive and the addition of oil and coal has not proved satisfactory because the degree of utilization is relatively low. A large part of the oil or coal added is carried into the top part of the crucible by the gas developed during the refining reaction. These substances are not burnt until they are being slopped out of the crucible mouth. As a result, only the chimney is heated and the structure in the upper part of the refining station is highly stressed whereas the bath is not heated to the desired degree. The maximum degree of utilization of the fuel supplied is 20 to 25%. Besides, special requirements regarding the purity of the material added must be met. In the case of coal it is possible to use only particularly pure grades, such as electrode carbon.

These difficulties may easily be avoided by means of the method according to the invention. Optimal results are attained, if the carbonaceous material in granular or powder form, or fuel gas, is supplied during the main boiling period, particularly between the 3rd and 15th minutes. In the known former method of working, introduction of coallike substances during the main boiling period was avoided because during the main boiling period there was the strongest development of gas and the fuel was utilized to the least degree as the fuel particles were carried upwardly into the top part of the converter.

The previous difficulties are eliminated in the method of working according to the invention. It is believed that this is accomplished due to the formation of the above referred to annular reaction zone on the surface of the molten charge which permits the carbonaceous materials supplied to become fully effective without any danger that they could be carried away before contacting the bath. For this reason the degree of utilization of the carbonaceous materials supplied in the method according to the invention is as great as 90%. According to the invention, carbonaceous or coallike materials of any desired kind may be used. It is not necessary to use particularly pure grades. Various kinds of coallike material, including inferior grades, have proved satisfactory. Suitable materials include coke, lignite, any grades of (hard) coal, even lignite for low temperature carbonization and tar coal.

The problem may also reside in melting a solid charge consisting of crude iron and scrap and in subsequently converting it into steel. In this case the necessary heat may also be supplied by an addition of coal and other combustible materials.

In a preferred embodiment of the invention, coal, iron ore and slag-forming substances are simultaneously introduced into the reaction vessel by means of a downcomer or the like into the interior of the reaction zone to form under a reducing atmosphere a liquid charge similar in composition to crude iron, and this charge is then converted into steel under an oxidizing atmosphere. The formation of a liquid charge may be begun when the vessel is empty. It is also possible to charge a portion of liquid crude iron at the beginning, and to increase this charge by the addition of coal and ore. The supply rate should be so controlled that a liquid molten bath having the necessary temperature is obtained. The conversion into steel is then carried out in the same vessel. Depending on the phosphorus content of the charge, the addition of slag-forming substances, such as CaO, during the blowing of the refining agent is continued until a reactive slag of high fluidity is formed, which takes up the major portion of the phosphorus.

After one or several deslagging operations the process may be terminated. In the last phase only oxygen is blown without an addition of admixtures.

The method according to the invention enables the very early formation of a reactive slag. The finely divided slag-forming substances supplied in the interior of the jet are melted and react quickly with the impurities in the iron. The method may be controlled in such a manner that the phosphorus content is reduced from 2.0% to 0.3-0.4% within a few minutes whereas the carbon content is still 2.0 to 2.5%. This has not been possible with any other process. A person skilled in the art will understand that the latitude thus achieved in such a wide range enables a universal application of the method. Crude irons of any desired composition, solid crude iron and even ores and scrap may be processed with or without an addition of liquid charging materials.

The method according to the invention may be combined with other measures which have proved satisfactory in special cases when refining crude iron. For instance, the liquid charge may be composed of a part of the finished steel and of the final slag of a preceding charge and may be increased by an addition of ore and coal with simultaneous blowing. During a refining phase, e.g., when the carbon content is 2.5 to 2.0% and a high phosphorus content is still present, a sudden oversupply of iron oxide, e.g., in the form of scarfing scale, may be added, followed by deslagging. This measure has the result of a very rapid removal of phosphorus.

The method according to the invention may also be used for refining and after-treating steel. The possibility of a mutual regulation of the kind and amount of the added materials relative to the blowing agent, particularly a suitable adjustment of the oxygen supplied in dependence on the amount of coal or other carbonaceous material supplied, enables the selective adjustment of an oxidizing, neutral or reducing atmosphere in the reaction vessel. For this reason it is possible, if desired, to provide for a reducing after-treating phase after the production of steel, and alloying elements, such as Mn, Cr, Ni may be added to the finished steel. In some cases it is necessary to heat the charge before adding alloying elements. This problem can also be easily solved with the aid of the method according to the invention.

A particularly advantageous and economical method of alloying is enabled by the method according to the invention in that the alloying substances are added in the form of oxides, such as chromium oxide, molybdenum oxide, manganese oxide and the like or in the form of ores containing such oxides, which ores are supplied in a mixture with reducing substances. Powdered coal or powdered aluminium are used as reducing substances and a reducing atmosphere is adjusted. Owing to the high temperature in the reduction zone it is possible in this way to reduce the oxides and to alloy the iron. This has not been possible before with any other blowing process and it was necessary to use the much more expensive pure metals or master alloys With iron as alloying admixtures.

A particularly advantageous application of the invention involves the simultaneous and continuous supply of oxygen and ores in hearth furnaces in the production of steel, using powdered or granular ores and, in addition, slag-forming substances, such as lime, if desired, as solid materials. The ores may consist of powdered or granular iron ore or of other ores. In addition to iron ores, the ores used may preferably consist of ores or ore concentrates of metals which are to remain as alloying elements in the steel. Suitable ores of this kind include particularly chromium ores, molybdenum ores and manganese ores.

With the aid of the method of working according to the invention the open-hearth furnaces can be loaded to their full heat capacity. The yield is increased and the output of existing plants is increased. The most important advantage resides in that the refining process is greatly accelerated without disturbing secondary effects.

The invention includes also apparatus for carrying out the method described. An illustrative embodiment is shown on the drawing, in which FIG. 1 is a diagrammatic representation of a plant, FIG. 2 an enlarged vertical sectional view of the mouth portion of the lance or blowing tube, and FIG. 3 a vertical sectional view of the upper part of the blowing device. FIG. 4 is a perspective view showing in section the jet produced with the device. A further embodiment is shown in FIG. 5 which is a diagrammatical longitudinal sectional view of a plant.

FIG. 1 shows a blowing tube 2 arranged to be lifted out of and lowered into a reaction vessel 1, which in this case is a converter having a refractory lining. A support 3 having a rack 4 or another guide element is provided to provide for a vertical guidance of the blowing tube. The blowing tube (FIG. 2) consists of an inner tube 5, in which the blowing fluid, such as oxygen, is supplied under pressure, and an external cooling shell 6. A guide tube 7 is arranged in the space between the inner tube 5 and the shell 6 to provide for a circulation of the cooling agent. In the mouth portion 8, which consists suitably of solid material, the inner and outer tubes are integrally connected and form the nozzle 9, which in the illustrative embodiment has the form of a Laval nozzle g iying rise to an expansion zone. Somewhat above its mouth the inner tube 5 is constricted to form a throttle 10. A downcomer 11 is centrally disposed in the blowing tube. The lower end of the downcomer is adjacent to the throttle. The upper portion of the downcomer extends through the wall 13 of the oxygen supply conduit 5, which is curved at the top. By means of a stuffing box 14 and a gasket 16 which can be tightened by screws 15 the upper part 12 of the downcomer is sealed against the insertion opening 17, which carries a flange 18 (FIG. 3). Above the stuffing box a flange 19 is welded to the downcomer and is connected to the flange 18 by screws 20. By an adjustment of the screws 20 the downcomer can be axially displaced relative to the blowing tube in the direction thereof. At the upper end the downcomer is connected to a hopper 21, which, in this case, widens like a funnel and serves for charging solid materials. The hopper 21 communicates with the outer atmosphere. 22 is a valve consisting, e.g., of a slide valve. As has been mentioned above and indicated with dash lines in FIGURES 1 and 2, the downcomer with the hopper 21 is axially displaceable relative to the inner tube 5. It is believed that when the downcomer is in its lowermost position the expansion cone has the smallest size and the annular reaction field on the surface of the charge has the smallest diameter. Lifting the downcomer causes an increase of the generating angle of the cone and of the diameter of the reaction field. This enables a very simple and practical additional adjustment for the control of metallurgical processes.

FIG. 4 shows what is believed to be the lower part of hollow-conical jets thus produced. 23 is a jet of relatively small diameter, which results in the formation of the reaction ring 24. 25 is a jet larger in diameter to form the reaction ring 26 correspondingly larger in diameter. The materials are introduced into the interior 27 of the reaction ring.

As is apparent from FIG. 1, the funnel-shaped hopper 21 at the upper end of the downcomer is disposed adjacent to a charging device which consists of a supply vessel 28 and a belt conveyor 29. The belt conveyor may be provided with a weighing device and may be pivotally mounted to enable the feeding operation to follow the vertical lifting and lowering movement of the downcomer and blowing tube. Instead of the belt conveyor, a feed tube with conveyor screw may be used; this feed tube is preferably filled with inert gas.

The dimensions of the blowing device and, in accord ance therewith, the size of the reaction zone may be adjusted to the size of the charge to be blown. For a charge of 5 to 6 metric tons it is desirable to use a blowing tube having an inner tube 30 mm. in diameter at the throttle 10. The axially inserted downcomer has in this case an outside diameter of about 25 mm. and an inside diameter of about 20 mm.

Correspondingly larger dimensions are used for larger charges.

FIG. 5 shows an open hearth furnace wherein 30 is the roof, 31 the bath and 32 are the doghouses of the furnaces. The blowing device 33 consists of a blowing tube 34 surrounded by a cooling shell and a downcomer 35 centrally disposed in the blowing tube extends vertically through the roof 30. The central downcomer serves for feeding solid materials and, as has been described more in detail hereinbefore, can be lifted and lowered relative to the blowing tube. The upper end 36 of the downcomer, where the latter communicates with the outside atmosphere, is suitably flared like a funnel. 37, 33 and 39, respectively, designate the oxygen supply conduit and the conduits for the supply and discharge of the coolant. Where the blowing device 33 passes through the furnace roof 30 it is surrounded by a cooling cylinder 40 having a water inlet and

outlet

41 and 42, respectively, and is guided in this cooling cylinder so that the device can be vertically lifted and lowered.

Conveyor belts

43 and 44 are disposed above the blowing device and are fed with ore and slag-forming materials from

supply containers

45 and 46. Owing to the described vertical adjustability of the blowing device over the bath surface and the controllable shape of the jet, a reaction field 47 is believed produced on the bath surface; the ore and, if desired, other materials are introduced under no pressure into the interior of this field. Thus the process can be controlled as desired without overheating and other disturbing secondary elfects.

The following examples illustrate the present invention without, however, limiting the same thereto.

Example 1.Conversion of steel-making crude iron into steel 50 kg. of scarfing scale and 30 kg. bauxite were added to a crucible charge of 400 kg. scrap and 6,540 kg. liquid crude iron having a composition of 4.12% C, 0.85% Si, 1.65% Mn, 0.196% P, 0.060% S. Then a blowing device as explained more fully in FIGS. 1 to 3 of the drawings was moved into the crucible. The inner tube had a diameter of 30 mm. at the throttle and the downcomer had an inside diameter of 20mm. and extended about 15 mm. below the throttle into the conically widening mouth portion of the nozzle. The nozzle orifice was adjusted to a distance of 400 mm. from the bath surface and oxygen blowing started with a pressure of 14 kg./sq. cm. superatmospheric pressure. A reaction zone was formed on the bath surface. 450 kg. lime dust were introduced under no pressure during a blowing period of 15.5 minutes into the interior of the jet by means of the downcomer. By the expanding gas the lime dust was sucked from the mouth of the downcomer and fell into the interior of the reaction zone. Towards the end of the blowing period, kg. broken limestone were added in portions by means of a chute while the downcomer was closed.

Then the oxygen supply was interrupted, the blowing device moved out of the crucible, the crucible was tilted and a steel sample taken, which had the following composition: 0.02% C, 0% Si, 0.20% Mn, 0.011% P, 0.014% S.

The bath was deslagged. The temperature was 1605 C. The steel was tapped. The recovery was 89%.

Example 2.C0nversion of crude iron having a particularly low carbon content and a high phosphorus content into steel 150 kg. scale and 50 kg. bauxite were added to a charge of 6,540 kg. liquid crude iron having a composition of 1.98% C, 0.72% Si, 0.15% Mn, 1.390% P, 0.052% S and having a temperature of 1350 C. A blowing device as has been described in detail in the drawings and in the foregoing example was moved into the crucible. The distance of the nozzle orifice from the bath surface was 600 mm. Oxygen blowing began at a pressure of 10 kg./sq. cm. superatmospheric pressure. A reaction zone was formed. During a blowing period of 13 minutes, 450 kg. lime dust were introduced under no pressure into the interior of the jet by means of the downcomer and were sucked from the mouth of the downcomer and fell into the interior of the reaction zone. After this first blowing period the oxygen supply was interrupted, the blowing device moved out of the crucible, the crucible tilted and samples of steel and slag taken. The steel had the following composition: 1.14% C, 0.02% Si, 0.07% Mn, 0.187% P, 0.043% S. The slag had the following composition: 15.23% FeO, 0.74% MnO, 9.84% SiO 39.40% 0.210, 4.46% MgO, 18.21% P 0 8.25% A1 0 The temperature was 1520 C.

The bath was deslagged, the crucible brought into blowing position and additional slag-forming substances, consisting of kg. scarfing scale, 50 kg. bauxite and 400 kg. lime in lumps added through a chute. Then the blowing tube was inserted into the crucible and the blowing continued for 6.5 minutes under an oxygen pressure of 14 kg./ sq. cm. and with nozzle orifice at a distance of 400 mm. from the bath. During this last blowing period the downcomer was maintained closed by a valve. After the blowing was terminated a steel sample was taken and had the following values: 0.02% C, 0% Si, 0.03% Mn, 0.015% P, 0.021% S. The temperature was 1610 C.

After deslagging and thickening of the slag the steel was tapped and teerned. The recovery was 85.3%.

A charge of 4,910 kg. crude iron having a composition of 4.10% C, 0.75% Si, 1.60%.Mn, 0.170% P and 0.050% S was blown and converted into steel. The tapping temperature was to be 1640 to 1650 C. In view of the composition of this crude iron, 12% scrap, equal to 590 kg. scrap, could be melted together with the crude iron. It was desired, however, to process 1700 kg. scrap, which is 25.7%. The problem to be solved resided in the additional melting of 1110 kg. scrap. The charge was to be heated by an addition of coke breeze. The coke breeze available had the following analysis: 17.10% H O, 10.99% ash, 0.91% S (dry), 72.12% C (dry) and 1.76% volatile constituents. Its gross calorific value was 5868 kg.-cal., the net calorific value was 5754 kg.-cal. Its grain size was to 3 mm.

A charge consisting of 4,910 kg. crude iron and 1,700 kg. scrap was introduced into the crucible provided with a refractory lining. 500 kg. lump lime, 50 kg. scarfing scale, 30 kg. bauxite and 20 kg. fluorspar were added as slag-forming admixtures. A blowing device of the type described herein was set to a distance of 600 mm. from the bath surface; oxygen was supplied under a pressure of to 11 kg./sq. cm. superatmospheric pressure. From the 3rd to the 12th blow minute, 212 kg. coke breeze of the composition described hereinbefore were introduced under no pressure into the interior of the jet by means of the downcomer. Deslagging was eifected after a total blow time of 21 minutes. The final analysis of the resulting steel was: 0.05% C, 0.18% Mn, 0.011% P. The temperature was 1650 C.

The efiiciency of the fuel added according to the invention is calculated as follows: In view of the values.

C steel=0.15 kg.-cal./kg. C. 1 kg. C CO=2440 kg.-cal. s (heat of fusion of steel) =60 kg.-cal./ kg.

the following heat quantities are required for heating 1110 kg. scrap from 20 C. to 1650 C. and for supplying the heat of fusion:

192 m X 100 9 l Example 4.Heating of a charge during the main boiling period by means of powdered coal =139 kg. 0:192 kg. coke breeze Using a charge of 5,330 kg. crude iron having a similar composition as in Example 3, 1,400 kg. scrap (20.8%) were melted. Powdered coal having a grain size of 0 to 3 mm. and the following composition: 8.00% water, 6.28% ash, 0.76% S (dry), 76.65% C (dry), 4.07% H 4.39% O +N was used for heating the charge. Its gross calorific value was 7440 kg.cal., the net calorific value was 7128 kg.-cal.

The method of working was the same as in Examp1e 3. The blowing began after the charge had been introduced and 500 kg. lump lime, 50 kg. scarfing scale and 30 kg. fluorspar added. The distance of the blowing tube from the bath surface was 700 mm. By means of the downcomer, 240 kg. powdered coal were added from the 3rd to the 13th blow minutes. Deslagging was effected at the end of the refining process. The steel had a composition of 0.06% C, 0.38% Mn, 0.010% P. The temperature was 1705 C. The degree of utilization of the powdered coal'was 72%.

Example 5 .Heating of a charge during the main boiling period by means of lignite breeze Using a charge of 5320 kg. crude iron having a similar composition as in Example 3, 1400 kg. scrap (20.2%) were melted. To heat the charge, lignite breeze having the following composition: 17.41% water, 22.72% ash, 1.63% S (dry), 56.86% C (dry) and 8.33% volatiles was used. The gross calorific value was 5048 kg.-cal., the net calorific value was 4863 kg.-cal.

The method of working was the same as in Examples 3 and 4. The blowing began after the charge had been introduced and 550 kg. lump lime, 50 kg. scarfing scale, 30 kg. bauxite and 30 kg. fluorspar added. The distance of the blowing tube from the bath surface was 700 mm. By means of the downcorner, 350 kg. lignite breeze were added from the 3rd to the 14th minute of the blow. Deslagging was effected at the end of the refining process. The steel had a composition of 0.07% C, 0.37% Mn, 0.009% P. The temperature was 1645 C. The degree of utilization of the lignite breeze was 60% Example 6.Heating of a melt under reducing conditions A charge was formed from 300 kg. scrap and 6400 kg. liquid crude iron, having a composition of 4.08% C, 0.89% Si, 1.47% Mn, 0.142% P, 0.057% S. After addition of 50 kg. scale, 30 kg. bauxite and 450 kg. lime in lumps the charge was blown with oxygen using a blowing device of the type disclosed herein but with a closed downcomer (pressure 14 kg./sq. cm. superatmospheric pressure, nozzle distance 400 mm) After a blowing period of 16.5 minutes, during which kg. broken limestone were added in portions through a chute, the supply of oxygen was interrupted, the blowing tube withdrawn and samples taken. The composition of the steel was: 0.03% C, 0% Si, 0.27% Mn, 0.022% P, 0.030% S. The temperature was 1610 C.

This temperature was increased. After the bath had been completely deslagged the crucible was again moved to its blowing position and the blowing device inserted into the crucible. The distance from the bath of the blow ing device was adjusted to 400 mm., the oxygen pressure was adjusted to 6 kg./sq. cm. superatmospheric pressure and the blowing of the bath continued for 5 minutes. At the same time, 80 kg. powdered coke and 12 kg. lime dust were introduced through the downcomer under no pressure into the interior of the reaction zone. After this heating period the oxygen supply was interrupted and another sample was taken. The composition of the steel was as follows: 0.09% C, 0% Si, 0.27% Mn, 0.025% P, 0.025% S. The temperature was 1640 C. The steel was tapped and teemed. The recovery was 88.5%.

Example 7.Heating of a melt under neutral conditions A charge was formed from 350 kg. scrap and 6330 kg. liquid crude iron, having a composition of 4.01% C, 0.90% Si, 1.40% Mn, 0.17% P, 0.050% S and 50 kg. scale, 30 kg. bauxite and 450 kg. lime in lumps were added. Then the charge was blown with oxygen using a blowing device of the kind disclosed herein but with the downcomer closed (pressure 14 kg./sq. cm., nozzle distance 400 mm.). After a blowing period of 16 minutes, during which kg. broken limestone were supplied in portions through a chute, the oxygen supply was interrupted, the blowing tube removed and samples taken. The composition of the steel was: 0.05% C, 0% Si, 0.27% Mn, 0.018% P, 0.025% S. The temperature was 1580 C.

This temperature was increased. After the bath had been completely deslagged the crucible was moved to its blowing position and the blowing device introduced into the crucible and adjusted to a distance of 400 mm. from the bath. The oxygen pressure was adjusted to 7 kg./ sq. cm. superatmospheric pressure and the blowing of the bath continued for 6 minute. At the same time, 80 kg. powdered coke and 12 kg. lime dust were introduced under no pressure through the downcomer into the interior of the reaction zone. After this heating period the oxygen supply was shut off and another sample taken. The composition of the steel was as follows: 0.05% C, Si, 0.25 Mn, 0.018% P, 0.023% S. The temperature was 1630 C. The steel was tapped and teemed. The recovery was 88.9%.

Example 8.Heating of a melt under oxidizing conditions A charge was formed from 400 kg. scrap and 6450 kg. liquid crude iron having a composition of 4.10% C, 0.95% Si, 1.50% Mn, 0.164% P, 0.055% S and 50kg. scale, 30 kg. bauxite and 450 kg. lime in lumps were added. Then the charge was blown with a blowing device as in the previous examples but with downcomer closed (pressure 14 kg./ sq. cm. superatmospheric pressure, nozzle distance 400 mrn.). After a blowing period of 16 minutes, in which 90 kg. broken limestone were added in portions through a chute, the oxygen supply was interrupted, the blowing tube removed and samples taken. The composition of the steel was: 0.04% C, 0% Si, 0.30% Mn, 0.027% P, 0.023% S. The temperature was 1590 C.

This temperature was increased. After the bath had been completely deslagged the crucible was moved to its blowing position and the blowing device inserted into the crucible and adjusted to a distance of 400 mm. from the bath. The oxygen pressure was adjusted to 7 kg./sq. cm. superatmospheric pressure and the blowing of the bath continued for 7 minutes. At the same time, 80 kg. powdered coke and 12 kg. lime dust were added under no pressure through the downcomer into the interior of the reaction zone. After the heating period the oxygen supply was shut off and another sample taken. The composition of the steel was: 0.02% C, 0% Si, 0.23% Mn, 0.018% P, 0.025% S. The temperature was then 1665 C. The steel was tapped and teemed. The recovery was 88.0%.

Example 9.Alloying a melt with simultaneous neutral heating A charge was formed from 300 kg. scrap and 6230 kg. liquid crude iron having a composition of 4.12% C, 0.97% Si, 1.42% Mn, 0.170% P and 0.044% S. After an addition of 50 kg. scale, 30 kg. bauxite and 450 kg. lime in lumps the charge was blown with the blowing device as in the previous examples but with the downcomer closed (pressure 14 kg./sq. cm. superatmospheric pressure, nozble distance 400 mrn.). After a blowing period of 15.5 minutes, between the sixth and twelfth minutes of which 80 kg. broken limestone were added in portions, the oxygen supply was interrupted, the blowing tube withdrawn and a sample taken. The composition of the steel was as follows: 0.03% C, 0% Si, 0.30% Mn, 0.018% P, 0.027% S. The temperature was 1605 C.

After complete deslagging the crucible was moved back to its blowing position and the blowing device inserted into the crucible. The nozzle orifice was adjusted to a distance of 400 mm. from the bath, the oxygen pressure adjusted to 8 kg./sq. cm. superatmospheric pressure and the blowing of the bath continued for 4.5 minutes. At the same time, 70 kg. powdered coke and kg. lime dust were introduced under no pressure through the downcomer into the interior of the jet and thereby into the interior of the reaction zone. During the last portion of this heating period, about Z2 minute before the end of the blowing, 87 kg. ferro-chromium having a composition of 1.39% C, 0.80% Si, 0.040% P, 0.076% S, 66.10% Cr were added through a chute. Then the oxygen supply was interrupted, the blowing device moved out of the crucible and samples taken. The composition of the steel was: 0.05% C, 0% Si, 0.28% Mn, 0.018% P, 0.027% S, 0.97% Cr. The temperature was 1640 C. After tapping the recovery was 86.2%.

Example 10.Increase of a charge by reduction of are A charge was formed from 4800 kg. liquid crude iron having a composition of 4.05% C, 0.97% Si, 1.53% Mn, 1.68% P and 0.030% S. After 50 kg. scale, 30 kg. bauxite and 150 kg. lime in lumps had been added the charge was blown with the blowing device as in the previous examples but with the downcomer closed (pressure 14 kg./sq. cm., nozzle distance 400 mrn.). After a blowing period of 6.5 minutes the oxygen supply was interrupted, the blowing tube removed and a sample taken. The composition of the steel was as follows: 2.10%. C, 0% Si, 0.58% Mn, 0.104% P, 0.028% S. The temperature was 1560 C.

The crucible was moved back into blowing position and the blowing device moved into the crucible. The nozzle orifice was adjusted to a distance of 600 mm. from the bath, the oxygen pressure adjusted to 14 kg./ sq. cm. superatmospheric pressure and the blowing of the bath continued for 28.5 minutes. During this blowing period, 1,500 kg. fine ore, 1,000 kg. powdered coke and 210 kg. lime dust were simultaneously added under no pressure through the downcomer into the interior of the jet and thereby into the interior of the reaction zone. The ore had the following composition: 71% Fe, 0.1% Mn, 1.7% 306 0.05% CaO, 0.01% S, 0.08% P, 4.5% A1 0 0.1%

After this blowing period carried out under a reducing atmosphere the oxygen supply was shut down, the nozzle removed and a sample taken. The composition of the steel was as follows: 2.27% C, 0% Si, 0.25% Mn, 0.078% P, 0.035% S. The temperature was 1280 C.

After partial deslagging the crucible was moved back to its blowing position, 400 kg. lime in lumps were added through a chute, the blowing device moved into the crucible and while the downcomer was closed the blowing was continued for 13 minutes under a pressure of 14 kg./sq. cm. superatmospheric pressure and with a nozzle distance of 400 mm. Then the blowing was terminated, a sample taken and the temperature measured. The composition was: 0.03% C, 0% Si, 0.26% Mn, 0.017% P 0.026% S. The temperature was 1660 C.

After deslagging the steel was tapped and teemed. The recovery was 85.2%.

Example ]1.Conversion of high-phosphorus crude iron into steel A charge was formed from 6450 kg. liquid crude iron having a composition of 3.80% C, 0.83% Si, 0.45% Mn, 0.950% P, 0.040% S. After an addition of 150 kg. scarfing scale and 50 kg. bauxite the charge was blown by a blowing device as in the previous examples so that a reaction zone was formed. The distance of the blowing device from the bath was 400 mm., the oxygen pressure was 10 kg./sq. cm. superatmospheric pressure. During the first blowing period of 9 minutes, 400 kg. lime dust were added under no pressure through the downcomer and sucked from the mouth of the downcomer into the interior of the jet and moved into the interior of the reaction zone. After a first blowing period of 9 minutes the oxygen supply was interrupted, the blowing device withdrawn and 50 kg. ore in lumps added to the bath in one batch through a chute. A violent reaction ensued for 1 to 2 minutes. The crucible was tilted and samples taken. The composition of the steel in this stage was: 2.10% C, 0.06% Si, 0.18% Mn, 0.092% P, 0.037% S. The composition of the slag was: 18.00% FeO, 2.30% MnO, 10.75% SiO ,40.88% CaO, 4.43% MgO 12.78% P 0 7.31% A1 0 The temperature was 1520" C.

After deslagging the crucible was moved back to its blowing position, kg. scale, 50 kg. bauxite and 400 kg. lime in lumps introduced and blowing continued under a pressure of 8 kg./sq. cm. superatmospheric pressure and r a nozzle distance of 400 mm. while the downcomer was Example 12.-Cnversi0n of basic bessemer iron into steel To a charge of 6580 kg. liquid crude iron having a composition of 3.62% C, 0.27% Si, 1.05% Mn, 1.750% P, 0.053% S there was added 150 kg. scarfing scale and 50 kg. bauxite. The charge was blown by means of a blowing device as in the previous examples to form a reaction zone. The distance of the blowing device from the bath was 400 mm. and the oxygen pressure was 10 kg../sq. cm. superatmospheric pressure. During the first blowing period of 10.5 minutes, 450 kg. lime dust were supplied under no pressure through the downcomer and sucked up from the mouth of the downcomer into the interior of the jet and brought into the interior of the reaction zone. After the first blowing period of 10.5 minutes the oxygen supply was interrupted, the blowing device removed and 50 kg. ore in lumps added to the bath in one batch through a chute. A violent reaction ensued for 2 to 2.5 minutes. The crucible was tilted and samples taken. The compoSitiOn of the steel at this stage was: 1.98% C, 0% Si, 0.25% Mn, 0.225% P, 0.046% S. The composition of the slag was: 16.30% FeO, 6.28% MnO, 3.64% SiO 42.30% CaO, 1.64% MgO, 21.90% P 0 5.23% A1 0 The temperature was 1540 C.

After deslagging, the crucible was moved back to its blowing position. 100 kg. scale, 50 kg. bauxite and 400 kg. lime in lumps were introduced by means of a chute and the blowing continued under a pressure of 14 kg./ sq. cm. superatmospheric pressure and with .a nozzle distance of 400 mm. while the downcomer was closed. The duration of this second blowing period was 6.5 minutes.

Then the blowing device was moved out of the crucible, the crucible tilted and a steel sample taken. The composition was: 0.03% C, 0% Si, 0.10% Mn, 0.014% P, 0.020% S. The temperature is 1655 C. After deslagging, the steel was tapped and teemed. The recovery was 85.7%.

What is claimed is:

1. A method of carrying out metallurgical processes comprising blowing an oxygen-containing gas against the surface of a charge comprising molten crude iron in a vessel having a refractory lining, said gas being blown through an annular orifice to form an annular jet impinging on said surface in an annular zone, said jet bounding and defining a passage within said jet, and discharging solid particles by gravity through said passage against the surface of said charge inwardly of said annular zone during at least part of the time said gas is being blown against said surface of said charge.

2. A method according to claim 1 wherein said gas is selected from the group consisting of oxygen and oxygenenriched gases.

3. A method according to claim 1 wherein said solid particles are slag-forming substances.

4. A method according to claim 1 wherein said solid particles are heat generating substances.

5. A method according to claim 1 wherein said solid particles are iron oxides and alloying substances.

6. A method according to claim 1 wherein said solid particles are alloying substances.

7. The method set forth in claim 1 wherein said solid particles comprise carbonaceous material and the amounts of oxygen-enriched gas and carbonaceous material supplied to said charge are in such relation that an oxidizing atmosphere is produced.

8. The method set forth in claim 1 wherein said solid particles comprise carbonaceous material and the amounts of oxygen and carbonaceous material supplied to said charge are in such relation that a neutral atmosphere is produced.

9. The method set forth in claim 1 wherein said solid particles comprise carbonaceous material and the amounts of oxygen and carbonaceous material supplied to said charge are in such relation that a reducing atmosphere is produced.

10. The method set forth in claim 1 in which the solid particles are iron oxide and carbonaceous material.

References Cited by the Examiner UNITED STATES PATENTS 2,446,511 8/48 Kerry et al. -43 2,515,670 7/50 Slottman et al. 75-43 2,593,505 4/52 Wagstaff 75-60 2,598,393 5/52 Kalling et al. 75-60 2,817,584 12/57 Kootz et al. 75-60 2,836,411 5/58 Auer 266-34 2,862,811 12/58 Eketorp et al. 75-60 2,937,864 5/60 Kesterton 266-34 2,950,186 8/60 Allard et al. 75-60 3,988,443 6/61 Metz 75-52 2,990,271 6/61 Dierker 75-41 3,001,864 9/61 Muller et al. 75-129 FOREIGN PATENTS 1,226,680 2/59 France.

845,643 8/52 Germany.

898,309 11/59 Germany.

OTHER REFERENCES Jour. of Metals, June 1956, p. 762.

BENJAMIN HENKIN, Primary Examiner.

RAY K. WINDHAM, MARCUS U. LYONS, Examiners.

Claims

1. A METHOD OF CARRYING OUT METALLURIGCAL PROCESSES COMPRISING BLOWING AN OXYGEN-CONTAINING GAS AGAINST THE SURFACE OF A CHARGE COMPRISING MOLTEN CRUDE IRON IN A VESSEL HAVING A REFRACTORY LINING, SAID GAS BEING BLOWN THROUGH AN ANNULAR ORIFICE TO FORM AN ANNULAR JET IMPINGING ON SAID SURFACE IN AN ANNULAR ZONE, SAID JET BOUNDING AND DEFINING A PASSAGE WITHIN SAID JET, AND DISCHARGING SOLID PARTICLES BY GRAVITY THROUGH SAID PASSAGE AGAINST THE SURFACE OF SAID CHARGE INWARDLY OF SAID ANNULAR ZONE DURING AT LEAST PART OF THE TIME SAID GAS IS BEING BLOWN AGAINST SAID SURFACE OF SAID CHARGE.