US3240591A

US3240591A - Manufacture of ferromanganese alloy

Info

Publication number: US3240591A
Application number: US354229A
Authority: US
Inventors: Naaman H Keyser
Original assignee: Interlake Steel Corp
Current assignee: Globe Metallurgical Inc
Priority date: 1964-03-24
Filing date: 1964-03-24
Publication date: 1966-03-15
Anticipated expiration: 1983-03-15

Description

2 Sheets-Sheet 1 E W L D N A E R 0 INLET OXYGEN MANUFACTURE OF FERROMANGANESE ALLOY March 15, 1966 Filed March 24, 1964 COOLING WATER\ INVENTOR.

24 25 26 NAAMAN H. KEYSER PER CENT BY ATTORNEYS SILICON CONTENT OF ALLOY,

FIG. 3

March 15, 1966 N. H. KEYSER 3,240,591

MANUFACTURE OF FERROMANGANESE ALLOY Filed March 24, 1964 2 Sheets-Sheet 2 ALLOY FROM FURNACE TRANSFER LADLE POUR ALLOY AND SLAG BACK AND FORTH TO REACT MNO IN SLAG WITH s| IN ALLOY SPENT ORE LIME SLAG w BLOW WITH OXYGEN;

@ ADD ORE AND LIME DECANT l REPOUR DECANT SLAG.AND SAVE ALLOY FOR NEXT HEAT SLAG TRANSFE R LADLE 1:1

CAST ALLOY United States Patent 3,240,591 MANUFACTURE OF FERROMANGANESE ALLOY Naaman H. Keyser, Pal-ma, Ohio, assignor to Interlalre Steel Corporation, a corporation of New York Filed Mar. 24, 1964, Ser. No. 354,229 25 Claims. (Cl. 75-80) This invention relates in general to improvements in and relating to, the manufacture of alloys of manganese, such as ferromanganese. This application is a continuation-in-part of the co-pending United States patent application Serial No. 152,794, filed November 16, 196 1, by Naaman H. Keyser, now abandoned, and entitled, Manufacture of Ferromanganese Alloy.

Commercial low-carbon and medium-carbon ferromanganese are conventionally produced by utilization of a series of electric furnaces, one furnace for smelting manganese ore to provide a crude basis alloy, and another furnace for refining such basis alloy to produce a commercial product of a low carbon or a medium carbon manganese alloy. Low carbon as used here means generally up to about 0.4 percent carbon by weight, while medium carbon means from about 0.4 percent carbon by weight up to about 2 percent. Such ferromanganese alloy is widely used in the production of steel, and in those steels where a low final carbon analysis is important, such as for instance, stainless steels, a low carbon ferromanganese alloy is highly important since it is generally much more economical to take carbon out of a relatively small amount of manganese alloy than it is to take the same amount of carbon out of a much greater amount of steel.

The present invention provides a more economical arrangement for the production of commercial high grade ferromanganese in generally the low tomedium, carbon range, and one which embodies the utilization of a relatively high manganese slag for treatment of the crude manganese basis alloy and then an oxidizing blow together with the introduction of manganese ore to the basis melt, to provide for the production of ferro-manganese having a reduced content of various impurities such as for instance silicon and carbon, and a high content of manganese.

Accordingly, it is an object of the present invention to provide a novel process for the production of low-carbon and medium-carbon ferromanganese alloys.

Another object of the invention is to provide a novel process for the production of ferromanganese alloy which is more economical as compared to processes heretofore known and used for producing ferromanganese, and which results in a product of relatively low impurtity content and relatively high manganese content.

A more specific object of the invention is to provide a process of the above type wherein a crude ferromanganese basis alloy is treated with a high manganese slag after which the slag is removed and then an oxidizing blow is applied in conjunction with the introduction of manganese ore and lime to the melt, and in a manner whereby the loss of manganese by vaporization is maintained at a minimum.

A still further object of the invention is to provide a process of the above type wherein a crude ferromanganese basis alloy is treated with a high manganese slag after which the slag is removed and then an oxidizing 3,240,591 Patented Mar. 15, 1966 blow is applied in conjunction with the introduction of manganese ore and lime to the melt, and in a manner whereby some manganese can be recovered from the addition of the manganese ore.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a generally diagrammatic sectional view of a vessel wherein the oxidizing blow and addition of manganese ore and lime to the basis melt in the process of the invention may be carried out.

FIG. 2 is a diagrammatic flow sheet illustrating a preferred process in accordance with the invention.

FIG. 3 is a graph showing the relationship between the silicon content and the ignition temperature in a basis melt of manganese-silicon alloy.

The following equations represent graphically reactions in the process.

(1) Silicomanganese alloy (basis metal)+high manganese slag=intermediate basis silicomanganese alloy (reduced silicon and higher manganese) +relatively lower manganese slag.

(2) Intermediate basis silicomanganese alloy-l-oxygen gas (O )+manganese or (MnO and/or Mn O )+burnt lime (CaO) =low silicon high grade ferro-manganese alloy+a high manganese slag.

Alternatively:

(l) Manganese-silicon alloy (basis metal) +high manganese slag=intennediate basis manganese-silicon alloy (reduced silicon and higher manganese) +relatively lower manganese slag.

(2) Intermediate basis manganese-silicon alloy+oxygen gas (O )+manganese ore (MnO and/or Mn O +burnt lime (CaO)=low silicon high grade ferromanganese alloy+a high manganese slag.

According to the preferred mode of operation of this invention, the improved process for the manufacture of an alloy of manganese, such as ferromanganese, comprises first producing a relatively crude ferromanganese basis alloy especially favorable to purification, by reducing a suitable reducible iron-manganese composition, such as manganese ore, and for instance in an electric furnace in the conventional well-known manner, and so as to maintain the carbon content of the basis alloy at a reasonable amount, which may be generally tolerated in the final commercial ferromanganese alloy. The molten basis alloy so produced may then be treated soas to increase the manganese content of the basis melt and materially decrease the silicon content thereof, and including the use of an oxidizing blow while coincidentally therewith adding manganese ore and another protective element (e.g. burnt lime) to the melt.

More specifically, the present invention contemplates the taking of a relatively high silicon basis alloy, such as a silicomanganese alloy, or a manganese-silicon alloy, having a manganese content in the range of approximately 52% to a silicon content in the range of approximately 15% to 37%, and a carbon content of up to approximately 3.5% carbon, and preferably in the range of .10% to 3.3% carbon, produced for instance in an electric furnace, and treating it with a high manganese slag which was produced in a previous heat, and then removing the slag and subjecting the molten alloy to an oxidizing blow in a basic or magnesia lined vessel,

while coincidentally therewith adding a preferably intimate mixture of manganese ore and burnt lime to the melt, so as to materially reduce the silicon content of the melt while recovering an increased proportion of the manganese in the final commercial ferromanganese product, and resulting in a relatively high manganese slag for use in the next heat. The high purity ferromanganese alloy may then be removed from the vessel and cast into molds, while the high manganese slag may be retained in the vessel for use in charging a new batch of the molten basis alloy into the vessel, to treat the new batch with the slag, or the slag may be removed to another vessel for the same purpose.

The basis melt before treatment with the slag may be held for a predetermined length of time (e.g. up to 75 minutes or more) to permit separation of some of the carbon from solution and thus aid in controlling the carbon content of the basis alloy.

The following are descriptions by way of examples of the application of the invention to the manufacture of a ferromanganese alloy product of desired content both in carbon and silicon:

Example I A heat of 5000 pounds of silico-manganese alloy assaying 60.20% Mn, 17.60% silicon and 1.61% carbon was produced in an electric furnace. The melt was then transferred to a magnesia lined converter or ladle and wherein it possessed a temperature of approximately 2450 F. The melt was then subjected to an oxidizing oxidizing blow of 4600 cu. ft. of oxygen at an average rate of 400 cu. ft. per minute with the stream of oxygen being directed at the surface of the molten mass, while at the same time the-re was added an intimate mixture of 3900 pounds of manganese ore plus 1400 pounds of burnt lime at a rate of 400 pounds of the mixture per minute. From this treatment there was obtained a ferro-manganese alloy assaying, by weight:

Percent Manganese 79.20 Silicon 0.63

Carbon 1.62

Example 11 A heat of 4700 pounds of silico-manganese alloy assaying 66.70% manganese, 17.70% silicon and 1.41% carbon was produced in an electric furnace to a temperature of above 2450 F. and then in a magnesia lined converter or ladle was subjected to an oxidizing blow of 4700 cu. ft. of oxygen at 400 cu. ft. per minute, while at the same time there was added 2360 pounds of manganese ore plus 1600 pounds of lime at the rate of approximately 300 pounds per minute.

There was obtained a ferro-manganese alloying assaying, by weight:

Percent Manganese 78.20 Silicon 4.10

Carbon 1.26 In the above Example I, the slag assayed as follows, by weight:

Percent Si 28.0 MgO 7.0 CaO 27.5 MnO 38.06

In above Example II, the slag assayed as follows, by weight:

Percent SiO 33.00 CaO 31.50 MnO 30.44

Example III A heat of 6000 pounds of silicomanganese alloy assaying 64.5% manganese by weight, 17.9% silicon and 3.33% carbon was produced in an electric furnace in the conventional manner. The basis melt which was tapped at a temperature of approximately 2450 F. was held in the transfer ladle for 12 minutes, and then was transferred to a magnesia-lined ladle or vessel in which a molten high manganese slag from a previous melt had been retained. Such high manganese slag had the following analysis, by weight:

Percent Manganese oxide (MnO) 44.8 Silicon dioxide (SiO 19.5 Calcium oxide (CaO) 24.0 Magnesium oxide (MgO) 10.0

The molten basis melt and high manganese slag were then poured back and forth between a pair of vessels, each of which was lined with magnesia, a number of times, and more specifically four times, to thoroughly react the manganese oxide in the slag with the silicon in the basis alloy melt. The vessel X (FIG. 2) in which the mixture of slag and melt finally remained was then set aside for a short period of time (i.e. five minutes) to permit the slag to separate from the molten metal, and then the vessel was decanted and the spent slag was removed from the vessel.

The molten metal at this intermediate state had the following analysis, by weight:

Percent Manganese 75.6 Silicon 9.45

Carbon 1.45

The removed spent slag at this stage weighed 4000 pounds and had the following analysis, by weight:

Percent MnO 27.5 SiO 33.0 CaO 25.5 MgO 9.0

Thereafter the intermediate basis alloy in the vessel was subjected to an oxidizing blow of 499 pounds of oxygen at an approximate flow rate of 300 to 350 cu. ft. per minute and at a pressure of about psi. The oxygen was directed at the surface of the molten metal by means of an oxygen lance (as shown in FIG. 1) and coincidentally therewith there was added a mixture of 4500 pounds of manganese ore plus 1700 pounds of burnt lime at an average rate of approximately 360 pounds per minute. From this treatment there was obtained 5500 pounds of a high grade, medium carbon ferromanganese alloy plus a quantity of a relatively high manganese slag. The slag and molten finalized alloy were then separated as by means of decanting the vessel and first pouring off the slag into a vessel Y (FIG. 2) for use in treating the next heat, while the molten alloy was transferred to a transfer ladle for casting into molds.

The finalized ferromanganese alloy assayed 81.6% manganese, 1.18% silicon and approximately 0.96% carbon. The relatively high manganese slag produced by the oxidizing blow and coincident addition of manganese ore and lime assayed 31.1% MnO, 26.0% SiO 23.0% CaO, and 20.0% MgO.

The manganese ore of the type preferred for use in the above process is One that has a high manganese content and a high ratio of manganese to iron. An example of the type that is prefer-red is one that is known as Rhodesian ore and conventionally contains between 53 to 59% manganese, between 1.2 and 1.4% iron, between 2.3 and 3.8% silicon dioxide, between 0.69 and 3.0% aluminum trioxide (A1 0 plus incidental amounts of phosphorus such as for instance .02 to .06% phosphorus. However, it will be understood that other types of manganese ore may be utilized, the percentage of manganese in the ore being generally determined by its place of origin. For instance, Congo ore could be utilized but the percentage of manganese generally is somewhat less (47%52% manganese) and it generaly contains a greater percentage of silicon dioxide therein (e.g. 3%-6% The feeding of the ore and lime may be applied at the rate of approximately 300 to 530 pounds per minute for the general amount of basis metal specified in the examples and size of vessel used while the oxygen may be applied at a rate of approximately 100 to 400 cu. ft. per minute.

The oxygen utilized may be of the industrial grade, and may be applied through a water cooled lance to the top surface of the intermediate basis alloy melt in the vessel. The application of the oxygen results in a stirring and agitating action on the melt in the vessel. The reaction is exothermic and thus increases the temperature of the melt, which heat is used to melt the manganese ore and the lime added to the melt. The application of the oxygen and ore and lime to the intermediate basis melt starts a visible reaction with the evolution of a thick dark-red smoke accompanied by showers of burning sparks. As the blow continues, the smoke changes in col-or from a dark-red to a pale white, and near the end of the blow the volume of smoke decreases to a faint wisp.

When the oxygen flow rate applied to an intermediate basis melt was above about 400 cu. ft. per minute and the feed rate of the manganese ore and lime to the melt exceeded about 500 pounds per minute, overflowing of the resultant slag tended to take place. When a slag overflow occurred, and before the calculated amount of manganese or and lime and oxygen had been added to the melt, a reduction in the flow of oxygen to about 150 cu. ft. per minute while maintaining the feed rate of ore and lime, decreased the activity of the slag and helped to control the reaction.

In the above process, while pouring the slag and molten basis metal back and forth was utilized for treating the basis metal with the slag, other means or methods could be used instead of pouring. For instance, rotation and/or shaking of the melt might be utilized, or the melt could be agitated by means of some inert gas (e.g. argon); such an inert gas might even be used instead of the oxygen during addition of the manganese ore and lime, to agitate and stir the melt.

An extra step preferred for use in the above described process is that after the initial basis alloy is treated with a high manganese slag from a previous melt, and after the application of oxygen and manganese ore and lime to the intermediate basis alloy, the resultant or final alloy and high manganese slag would be repoured back and forth a number of times, say for instance four times, between a pair of basic lined vessels, or otherwise mixed before removal of the slag, which appears to improve the amount of manganese in the final alloy and occasions a reduction in the amount of silicon in such final alloy melt.

Example IV A heat of 4800 pounds of silicomanganese alloy assaying 68.1% manganese, 19.0% silicon and 1.30% carbon was produced in an electric furnace and was tapped into a transfer ladle at a temperature of approximately 2450 F. The alloy was held in the transfer ladle for 12 minutes and then was introduced into a basic lined ladle or vessel, which vessel containing a high manganese slag from a previous melt with such slag analyzing MnO 49.7%, SiO 22.5%, CaO 20.0%, plus 5.0% MgO. The basis melt and slag were poured back and forth four times between a pair of the basic lined ladles or vessels to thoroughly mix the slag and alloy and react the manganese oxide in the slag with the silicon in the alloy. The basis melt then had an intermediate composition of 78.7% manganese, 9.4% silicon and 1.09% carbon. Approximately 3000 pounds of slag were then removed from the vessel as by decanting the vessel and with the spent slag after removal having an analysis of 29.5% MnO, 36.5% SiO 25.0% CaO, plus 7.2% MgO. Such intermediate melt in the vessel was then blown with 449 pounds of oxygen at a rate of between approximately 300350 cu. ft. per minute and coincident-ally therewith there was added a mixture of 4500 pounds of manganese ore and 1700 pounds of lime at an average rate of approximately 440 pounds per minute.

After the blowing of the intermediate melt with the concurrent addition of the ore and lime, the mixture was poured back and forth four times between a pair of basic lined vessels to thoroughly mix the slag and the molten alloy metal in the vessel. The vessel was then decanted to remove the slag layer and with such slag layer having an analysis of 56.8% MnO, 17.5% SiO 18.5% CaO, and 8.0% MgO. The molten finalized alloy in the vessel was then transferred to a transfer ladle after which it was cast into the desired for-m. From such a process there was produced 4950 pounds of high grade medium carbon ferromanganese alloy analyzing 80.3% manganese, 2.66% silicon and 1.61% carbon.

Example V A heat of 5300 pounds of manganese-silicon alloy assaying 55.2% manganese, 37.3% silicon and 0.26% carbon was produced in an electric furnace and tapped therefrom into a basic lined vessel. In the basic lined vessel was a high manganese slag from a prior heat with the slag assaying 36.6% MnO, 30.0% SiO 27.5% CaO, and 8.0% MgO.

The mixture of slag and basis melt was poured back and forth approximately four times between a pair of basic lined vessles which resulted in an intermediate basis melt assaying 73.0% manganese, 23.7% silicon and 0.07% carbon. The vessel was decanted and approximately 9000 pounds of slag removed therefrom with the spent slag assaying 11.6% MnO, 50.0% SiO 30.0% CaO, and 7.0% MgO.

The intermediate basis melt in the vessel was then subjected to an oxidizing blow of 333 pounds of oxygen at the rate of between to 200 cu. ft. per minute, while coincidentally therewith there was added 8000 pounds of manganese ore and 3400 pounds of lime at an average rate of approximately 370 pounds per minute. The contents was then poured back and forth between a pair of basic lined vessels, and approximately four times, after which the melt retaining vessel was decanted and the slag removed therefrom; the slag analyzed 34.2% MnO, 26.5% SiO 29.0% CaO, and 6.0% MgO. The finalized low carbon, low silicon ferromanganese alloy in the vessel analyzed 91.5% manganese, 1.30% silicon and 0.11% carbon. Such final alloy was transferred to a ladle and poured into sand chill molds, resulting in 6640 pounds of the high grade ferromanganese metal.

Example VI A heat of 4700 pounds of manganese-silicon alloy assaying 56.7% manganese, 36.5% silicon and 0.20% carbon was produced in an electric furnace, tapped into a transfer ladle where it was held 50 minutes, and then transferred therefrom into a basic lined vessel. In the basic lined vessel was a molten high manganese slag from a prior heat with the slag assaying 35.7% MnO, 35.0% SiO 26.0% CaO, 5.7% MgO.

The slag and basis metal melt was thoroughly mixed or co-mingled, by pouring back and forth approximately four times between a pair of basic lined vessels, which resulted in an intermediate basis alloy assaying 75.2% manganese, 18.8% silicon and 0.07% carbon. The vessel was decanted and approximately 6000 pounds of slag removed therefrom with the spent slag assaying 20.8% MnO, 39.0% SiO 26.0% CaO, and 7.6% MgO.

The intermediate basis melt left in the vessel was then subjected to an oxidizing blow of 349 pounds of oxygen at the rate of between approximately 100 to 250 cu. ft. per minute, while coincidentally therewith there was added 8000 pounds of manganese ore and 3100 pounds of lime at various rates of between approximately 420 and 530 pounds per minute. The contents was then poured or mixed back and forth between a pair of basic lined vessels, and approximately four times, after which the melt retaining vessel was decanted and the slag removed therefrom; the slag analyzed 36.6% MnO, 30.0% SiO 27.5% CaO, and 8.0% MgO. The finalized low carbon, 'low silicon ferromanganese alloy in the vessel analyzed 90.1% manganese, 0.84% silicon and 0.09% carbon. Such final alloy was transferred to a ladle and poured into sand lined chill molds, resulting in 6380 pounds of the high grade alloy metal.

Example VII A heat of 5000 pounds of manganese-silicon alloy assaying 60.7% manganese, 31.2% silicon and 0.80% carbon was "produced in an electric furnace in the conventional manner, tapped into a transfer ladle, held for 75 minutes and then transferred therefrom into a basic lined vessel, at a temperature of close to the freezing temperature range. In the basic lined vessel was a molten high manganese slag from a prior heat with the slag assaying 59.1% MnO, 21.5% SiO 16.0% CaO, and 1.0% MgO.

The slag and basis metal melt was mixed by pouring back and forth approximately four times between a pair of basic lined vessels, which resulted in an intermediate basis alloy assaying 81.9% manganese, 10.0% silicon and 0.10% carbon. The vessel was decanted and the slag removed therefrom with the spent slag assaying 35.6% MnO, 36.0% SiO 19.0% CaO, and 1.0% MgO, and weighing about 7000 pounds.

The intermediate basis metal left in the vessel was then subjected to an oxidizing blow of 508 pounds of oxygen at the rate of approximately 200 cu. ft. per minute, While coincidentally therewith there was added 9000 pounds of manganese ore and 2200 pounds of lime at an average rate of approximately 370 pounds per minute. The content was then mixed or poured back and forth between a pair of basic lined vessels, and approximately four times, after which the melt retaining vessel was decanted and the slag removed therefrom; the slag which was retained for a subsequent melt analyzed 62.4% MnO, 18.5% SiO 18.5% CaO, and 1.0% MgO. The finalized low carbon, low silicon ferromanganese alloy in the vessel analyzed 91.5% manganese, 0.15% silicon and 0.11% carbon. Such final alloy was poured into molds, resulting in 3290 pounds of the high grade metal.

It will be seen that with this arrangement, the process involves starting of the purification of the silicomanganese alloy or the manganese-silicon alloy in molten form, after it has been removed, for instance, from an electric furnace, and before it has had a chance to cool off, thereby resulting in fuel savings over conventional practice. The high manganese slag taken off from the ferromanganese melt after oxygen, ore and lime treatment, for use in treating a subsequent batch of crude basis alloy is preferably maintained in a hot molten condition and at a temperature between approximately 2400 F. and 2600 F. This may be accomplished as by means of an auxiliary heater, until the slag is used in the process, or one heat may be followed by another soon enough so that the high manganese slag doesnt have an opportunity to cool. Moreover, the process reduces the capital costs involved since it is not necessary to have the usual complete series of electric furnace set ups as in prior art processes. Small batches of the product can be made as needed to satisfy sales and thus no large inventory of the product has to be maintained.

Manganese ore is added in the process so as to supply oxygen to the molten silicomanganese or manganesesilicon, for removal of the silicon and to provide a source of manganese for the alloy; to provide a source of manganese oxide for the slag since the manganese oxide would come from the silicomanganese or the manganesesilicon, if it were not added as ore; and to control the temperature of the bath during the treatment to aid in preventing excessive vaporization of the manganese. In other words, some of the excess heat that results in the earlier part of the oxygen blow may be absorbed by the melting of such ore and the associated lime.

The lime is added to the treatment to also aid in control-ling the bath temperature and to tie up the silica formed during the reaction. It is necessary to neutralize the silica to prevent reversal of the reaction and to prevent silica from attacking the basic lining of the treating vessel. An appearance of a foarming slag in the process during application of the oxidizing blow means generally that the slag is too acid. This foaming is generally alleviated by the timely addition of lime.

The gaseous oxygen used on the molten alloy also removes silicon from the alloy and stirs and agitates the melt during addition of the ore and lime. The reaction is exothermic and the heat generated aids in melting the manganese ore and lime. The more oxygen that is added as ore, the less needs to be added as gaseous oxygen. Indeed under favorable conditions of low heat losses, it is possible to eliminate the gaseous oxygen from the reaction and use gas only for agitation.

In connection with the silicon content of manganesesilicon basis alloy, there appears to be relationship between the silicon content and the temperature of ignition of the melt. Manganese-silicon with 22.4% silicon ignites with difficulty at 2500 F. When the alloy contains a higher percentage of silicon, such as approximately 24.20% silicon, the ignition proceeds slowly at 2560 F. If the temperature of the manganese-silicon alloy with approximately 21 to 23% silicon exceeds 2600 F. after reaction with the high manganese slag, ignition with oxygen proceeds quite rapidly. A silicon level of at least approximately 31% to 33% in the original or initial manganese-silicon basis alloy prior to treatment with the slag, is generally required to produce a carbon level of 0.1% or lower in the finalized low carbon manganese alloy. Accordingly, it has been determined that desirable or necessary ignition temperature of the intermediate basis melt can be approximate from the following formulation which is derived from FIG. 3 of the drawings: ignition temperature in degrees F.=1,735 F. plus 34.6 F. percent of silicon in the melt. Referring again to FIG. 3, ignition of the manganese-silicon intermediate basis melt will generally occur in the area above the line, while in the area below the line, such ignition will generally not occur. In other words, the temperature required for ignition of the molten intermediate stage basis alloy increases generally linearly with an increase in the silicon content of the alloy. In this connection, the high manganese slag used to treat the initial basis alloy, should be maintained in a predetermined heated condition as by means of a separate heater and as aforediscussed. With silicomanganese basis alloy, there are no particular problems involved in obtaining ignition during the oxidizing blow and after treatment with the slag.

The following table lists charges and pertinent analyses for steady state production of three important grades of premium commercial ferromanganese identified as product A, B and C. This information was obtained from digital computer studies of what is believed to be optimum conditions for steady state manufacturing operations for such products.

Product A in the table represents a low-silicon medium carbon ferromanganese, analysing minimum manganese, 0.3% maximum silicon, and 1.5% maximum carbon.

Product B in the table represents a low carbon ferromanganese analysing minimum manganese, 1.5% maximum silicon and 0.3% maximum carbon.

9 Product C in the table represents a low-carbon ferromanganese analysing 85% minimum manganese, 1.5%

maximum silicon and 0.1% maximum carbon.

Item Product A Product 13 Product Input Mn alloy:

Weight, lb 6, 745 5, 218 5, 218 Analysis, percent Manganese 68/70 60/62 58/60 Silicon 18/20 29/30 32/33 Carbon (approx) 1.60 0.43 0. 15 Input recycle slag:

Weight, lb 7, 765 8, 339 9,184 Analysis, percent MnO 47. 6 30.8 30. 9 S102 22.9 30.5 30. 7 CaO 18. 0 27.1 26.8 MgO 6. 6. 5 6. 5 Discarded slag:

Weight, lb 7, 263 7, 805 8, 583

30.4 18. 2 17. 4 38. 0 40. 5 41.0 19. 3 28.9 29. 2 MgO 6. 9 6.9 7.0 Intermediate metal:

Weight, lb 7, 434 5, 825 5,899 Analysis, percent Manganese... 78. 0 70. 1 69. 3 Silicon... 11.1 21. 4 23. 2 Carbon... 1. 45 0.38 0. 13 Input ore: Weight 8, 566 9,135 10,075 Input burnt lime: Weight 1, 551 2, 453 2, 662 Input oxygen:

Weight, lb 270 209 209 Cubic feet. 3, 245 2, 512 2, 512 Output metal (idea Weight, lb 8, 563 7, 931 8, 231 Analysis, percent:

Manganese 90. 13 92. 38 93. 21 0.29 1. 37 1. 39 1. 26 0.28 0. 09 Output recycle slag:

Weight, 1b 8, 443 8, 856 9, 708 Analysis, percent:

Mn 47. 6 30. 8 30.9 22. 9 30.5 30.7 18. O 27. 1 26. 8 6. 5 6. 5 6. 5

Itv has been determined that the following ranges generally provide for practicing the invention as above discussed in the production of high quality low to medium carbon ferromanganese alloy metal: (a) The ratio by weight of the high manganese treating slag to the initial basis alloy prior to subjecting the latter to, the oxidizing blow is preferably between the range of approximately 0.4 and 4.3.

.(b) The ratio by weight of the initial basis alloy to the added manganese ore is preferably between the range of approximately 0.4 and 2.2.

(c) The ratio by weight of the initial basis alloy to the .added lime is preferably between the range of approximately 1.3, and 5.1.

(d) The ratio by weight of the initial basis alloy to the oxygen of, the oxidizing blow is preferably between the range. of approximately 9 and 25 or even higher.

From the foregoing description and accompanying drawings, it will be seen that the invention provides a novel processfor the production of relatively low silicon, high manganese, ferromanganese alloy, and a process resulting in considerable economic advantages over processes heretofore utilized in the production of such an alloy.

The terms and expressions which have been used are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of any of the features shown or described, or portions thereof, and it is recognized that various modifications are possible within the scope of the invention claimed.

I claim:

1. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying an oxidizing blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately to 37%, silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen resulting in agitation and ignition of the bath wherein a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy and the high manganese slag from one another, and then mixing a new batch of the molten basis alloy in a vessel with said high manganese slag to treat the new batch of basis alloy with said slag, separating said slag from said treated new batch of molten basis alloy, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten new batch.

2. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 1 including the step of pouring said new batch of molten basis alloy and high manganese slag from one vessel to another vessel to thoroughly mix the same prior to application of the last mentioned oxidizing blow.

3. The manufacture of low to medium'ferromanganese alloy metal in accordance with claim 1 including the step of setting the vessel with said high manganese slag and said new batch of molten basis alloy therein aside for a period of time to permit gravity separation of said new batch of basis alloy from the slag prior to separation of the slag from said new batch of basis alloy.

4. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 1 wherein said slag is separated from said new batch of molten basis alloy by pouring said slag from the vessel.

5. The manufacture of low to medium carbon ferromanganese in accordance with claim 1 including the step of applying heat to said high manganese slag after its separation from said ferromanganese alloy.

6. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying an oxidizing blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15% to 37% silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen, ore and lime resulting in agitation and stirring of the bath and the ignition thereof together with an emission of a dark red cloud of smoke and sparks, and

continuing the application of oxygen until the emission from the bath subsides, whereupon there is produced a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said basis alloy, together with a high manganese slag, separating the ferromanganese alloy and high manganese slag, mixing a new batch of said molten basis alloy in a vessel with said high manganese slag to treat said new batch of basis alloy with said slag, separating said slag from said treated new batch of molten basis alloy, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said treated new batch.

7. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises applying an oxidizing blow to a molten batch of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15 to 37% silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen resulting in agitation and stirring of the bath wherein a ferromanganese alloy of a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy and the high manganese slag from one another, and then mixing a new batch of said molten basis alloy in a vessel with said high manganese slag, intimately mixing said new batch of molten basis alloy and said slag to thoroughly treat the new batch of basis alloy with the slag, separating said slag from said treated new batch of molten basis alloy, and applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten new batch.

8. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 7 wherein the application of oxygen to the basis alloy is applied at the rate of approximtaely 100 to 400 cu. ft. per minute and the feeding of the manganese ore and lime into the molten bath during said oxidizing blow application is applied at the rate of approximately 300 to 530 pounds per minute.

9. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises applying an oxidizing blow to a molten batch of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15% to 37% silicon and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen resulting in agitation and stirring of the batch wherein a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy and the high manganese slag from one another and then charging a new batch of molten basis alloy into a vessel containing said high manganese slag, mixing said high manganese slag with said new batch of molten basis alloy to treat the new batch of molten basis alloy with the slag and resulting in a ferromanganese alloy with a high manganese content and a lower silicon content than that of the first mentioned basis alloy, removing said slag from the vessel, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten new batch.

10. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying from a jet source an oxidizing blow to a molten batch of manganese basis alloy in a vessel, said basis alloy containing between approximately 60% to 70% manganese, between approximately 15% to silicon and up to 2% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen resulting in agitating and stirring of the bath wherein a ferromanganese alloy of a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, removing the ferromanganese alloy from the vessel while leaving said high manganese slag in the vessel, charging a new batch of said molten basis alloy into the vessel to treat said new batch of basis alloy with said slag, removing said slag from the vessel, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten batch.

11. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying from a jet source an oxidizing blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15% to 37% silicon and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, said application of oxygen resulting in agitation and ignition of the bath wherein a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy and the high manganese slag from one another, and then mixing a new batch of the molten basis alloy in a vessel with said high manganese slag to treat the new batch of basis alloy with said slag, the ratio by weight of said high manganese slag to said new batch of molten basis alloy being within the range of approximately 1 to 2, separating said slag from said treated new batch of molten basis alloy, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said treated new batch of molten basis alloy.

12. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying from a jet source an oxidizing blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to manganese, between approximately 15% to 37% silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, the ratio by weight of the basis alloy to the added ore being less than approximately 2.2 and the ratio by weight of the basis alloy to the lime being in a range of approximately 1.3 to 5.1, said application of oxygen resulting in agitation and ignition of the bath wherein a ferromanganese alloy of a greater manganese content and a lower silicon content than that of said basis alloy is produced, together with a high manganese slag, separating the ferromanganese alloy from said high manganese slag in the vessel, mixing a new batch of said molten basis alloy in a vessel with said slag to treat such molten new batch of basis alloy with said slag, removing said slag from the vessel, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten new batch with the ratios by weight of said new batch of basis alloy to the last mentioned added ore and lime being approximately within the first mentioned ratios.

13. In the manufacture of low to medium carbon feroxidizing blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15% to 37% silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said oxidizing blow application, the ratio by weight of the basis alloy to said ore being within the range of approximately 0.4 to 2.2 and the ratio by weight of the basis alloy to the lime being in the range of approximately 1.3 to 5.1, said application of oxygen resulting in agitation and ignition of the bath wherein a ferromanganese alloy of a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy from said high manganese slag in the vessel, mixing a new batch of said molten basis alloy in a vessel with said high manganese slag to treat the new batch of molten basis alloy with said slag, the ratio by weight of said slag to said new batch of molten basis alloy being within the range of approximately 0.4 to 4.3, separating said slag from said treated new batch of molten basis alloy, and then applying an oxidizing blow and coincidentally therewith adding manganese ore and lime to said molten new batch with the ratios by weight of said new batch of basis alloy to the last mentioned added ore and lime being approximately within said ranges.

14. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises applying from a jet source an oxidizing blow to the surface of a molten bath of a manganese basis alloy at a temperature of approximately 2450 F. in a vessel, said basis alloy containing between approximately 60% to 70% manganese, between approximately 15% to 20% silicon and up to 2% carbon, introducing a mixture of manganese ore and lime into the molten bath during said oxidizing blow application, the ratio by weight of the basis alloy to the ore being in the range of approximately 1.28 to 1.99 and the ratio by weight of the basis alloy to the lime being in the vessel, charging a new batch of said molten basis tion of oxygen resulting in agitation and stirring of the bath wherein a ferromanganese alloy of a greater manganese content and a materially lower silicon content than that of said basis alloy is produced together with a high manganese slag, removing the ferromanganese alloy from the vessel while leaving said high manganese slag in the vessel, charging a new batch of said molten basis alloy into the vessel to treat said new batch of basis alloy with said slag prior to application of any oxidizing blow to said new batch of basis alloy, removing said slag from the vessel and then applying an oxidizing blow and coincidentally therewith adding a mixture of manganese ore and lime to said molten new batch with the ratios by weight of the new batch of basis alloy to the last mentioned added ore and lime being approximately within said ranges.

15. In the manufacture of low carbon ferromanganese alloy metal which comprises mixing a molten bath of an input manganese basis alloy in a vessel with a molten high manganese slag, said basis alloy comprising approximately 58 to 60% manganese, between approximately 32 to 33% silicon and approximately 0.15% carbon, said manganese slag comprising approximately 31% MnO, approximately 31% SiO approximately 27% CaO and between approximately 6 to 7% MgO, separating said slag from said basis alloy and then applying an oxidizing blow to said molten basis alloy and coincidentally therewith adding manganese ore and lime to said molten alloy, the ratio by weight of said input basis alloy to said added ore being approximately 0.5 and the ratio by weight of said input basis alloy to said added lime being approximately 2.

16. The manufacture of low carbon ferromanganese alloy metal in accordance with claim wherein said basis alloy is poured back and forth between a pair of basic lined vessels after application of said oxidizing blow and said ore and lime.

17. The manufacture of low carbon ferromanganese alloy metal in accordance with claim 15 including heating said slag prior to mixing it with said basis alloy.

18. In the manufacture of low carbon ferromanganese alloy metal which comprises mixing a molten bath of an input manganese basis alloy in a vessel with a molten high manganese slag, said basis alloy comprising between approximately 60 to 62% manganese, between approximately 29 to 30% silicon, and approximately 0.43% carbon, said manganese slag comprising approximately 30.8% MnO, approximately 30.5% SiOg, approximately 27.1% CaO and approximately 6.5% MgO, separating said slag from said basis alloy, and then applying oxidizing blow to said molten basis alloy and coincidentally therewith adding manganese ore and lime to said molten alloy, the ratio by weight of said input basis alloy to said added ore being approximately 0.6 and the ratio by weight of said input basis alloy to said added lime being approximately 2.

19. In the manufacture of medium carbon ferromanganese alloy metal which comprises, mixing a molten bath of an input manganese basis alloy in a vessel with a molten high manganese slag, said basis alloy comprising approximately 68 to 70% manganese, approximately 18 to silicon, and approximately 1.6% carbon, said manganese slag comprising approximately 47.6% MnO, approximately 22.9% SiO approximately 18.0% CaO and approximately 6.5 MgO, separating said slag from said basis alloy, and then applying an oxidizing blow to said molten basis alloy and coincidentally therewith adding manganese ore and lime to said molten alloy, the ratio by weight of said input basis alloy to said added ore being approximately 0.79 and the ratio by weight of said input basis alloy to said added lime being approximately 4.3.

20. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 6 wherein the rate of application of oxygen during said blow to said treated new batch is relatively fast during the initial portion of said application and until ignition occurs, and then reducing said rate during the remainder of said application.

21. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, applying an inert gaseous blow to a molten bath of manganese basis alloy in a vessel, said basis alloy containing between approximately 52% to 70% manganese, between approximately 15% to 37% silicon, and up to 3.5% carbon, introducing manganese ore and lime into the molten bath during said gaseous blow application, said application of gas and said manganese ore and lime resulting in agitation and selective oxidation of the bath, wherein a ferromanganese alloy of a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high manganese slag, separating the ferromanganese alloy and the high manganese slag from one another, and then mixing a new batch of the molten basis alloy in a vessel with said high manganese slag to treat the new batch of basis alloy with said slag, separating said slag from said treated new batch of molten basis alloy, and then applying an inert gaseous blow and coincident-ally therewith adding manganese ore and lime to said molten new batch.

22. In the manufacture of low to medium carbon ferromanganese alloy metal which comprises, mixing a molten bath of an input manganese basis alloy in a vessel with a molten high manganese slag, said basis alloy comprising between approximately 52% to manganese, between approximately 15% to 37% silicon, and up to 3.5% carbon, separating said slag from said basis alloy, and then applying a gaseous blow to said molten basis alloy and coincidentally therewith adding manganese ore and lime to said molten alloy, whereupon a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said basis alloy is produced together with a high managanese slag.

23. In the manufacture of low to medium carbon ferrom-anganese alloy metal which comprises, thoroughly mixing a molten bath of an input manganese basis alloy in a basic lined vessel with a molten high manganese slag, said basis alloy comprising between approximately 52% to 70% manganese, between approximately 15 to 37% silicon and up to 3.5% carbon, said manganese slag comprising between approximately 30% to 59% MnO, between approximately 19% to 35% SiO between approximately 16% to 32% CaO, and between approximately 1% to 10% MgO, separating the slag from said alloy, and then applying an oxidizing blow to the molten alloy and coincidentally therewith adding manganese ore and lime to said molten alloy, said application of oxygen resulting in agitatiomand ignition of the melt wherein a ferromanganese alloy with a greater manganese content and a lower silicon content than that of said input basis alloy is produced together with a high manganese slag, and then separating said ferromanganese alloy and the high manganese slag from one another.

24. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 23 including the step of mixing the second mentioned high manganese slag and said ferromanganese alloy thoroughly before separating.

25. The manufacture of low to medium carbon ferromanganese alloy metal in accordance with claim 23 including the step of holding the input manganese basis alloy for a predetermined time before said mixing of said input basis alloy and the first mentioned high manganese slag whereby carbon in said input basis input alloy comes out of solution, thus aiding in controlling the carbon content of said low to medium carbon ferromanganese alloy metal.

References Cited by the Examiner UNITED STATES PATENTS 1,363,657 12/1920 Kalling et al 80 FOREIGN PATENTS 135,186 1/1921 Great Britain. 163,262 4/ 1921 Great Britain.

DAVID L. RECK, Primary Examiner.

BENJAMIN HENKIN, Examiner.

Claims

1. IN THE MANUFACTURE OF LOW TO MEDIUM CARON FERROMANGANESE ALLOY METAL WHICH COMPRISES, APPLYING AN OXIDIZING BLOW TO A MOLTEN BATH OF MANGANESE BASIS ALLOY IN A VESSEL, SAID BASIS ALLOY CONTAINING BETWEEN APPROXIMATELY 52% TO 70% MANGANESE, BETWEEN APPROXIMATELY 15% TO 37%, SILICON, AND UP TO 3.5% CARBON, INTRODUCING MANGANESE ORE AND LIME INTO THE MOLTEN BATH DURING SAID OXIDIZING BLOW APPLICATION, SAID APPLICATION OF OXYGEN RESULTING IN AGITATION AND IGNITION OF THE BATH WHEREIN A FERROMANGANESE ALLOY WITH A GREATER MANGANESE CONTENT AND A LOWER SILICON CONTENT THAN THAT OF SAID BASIS ALLOY IS PRODUCED TOGETHER WITH A HIGH MANGANESE SLAG, SEPARATING THE FERROMANGANESE ALLOY AND THE HIGH MANGANESE SLAG FROM ONE ANOTHER, AND THEN MIXING A NEW BATCH OF THE MOLTEN BASIS ALLOY IN A VESSEL WITH SAID HIGH MANGANESE SLAG TO TREAT THE NEW BATCH OF BASIS ALLOY WITH