US3369887A - Process for the production of manganese-silicon alloys - Google Patents

Description

United States Patent 3,359,887 PROCESS FOR THE PRODUCTION OF MANGANESE-SILECON ALLDYS Naaman H. Keyser, Parma, and Ted J. Dyrdek and Robert A. Leeper, Beverly, Ohio, assignors to Iuterlake Steel Corporation, a corporation of New York No Drawing. Filed Dec. 11, 1964, Ser. No. 417,772

20 Claims. (Cl. 75-10) ABSTRACT 6F THE DISCLOSURE A process for the production of manganese-silicon alloys, more particularly manganese-silicide, wherein a material containing manganese and silicon is provided with a suificient reducing agent to reduce all of the metallic oxides in the burden, and subsequently reduced in a furnace. The reduced manganese-silicon alloy is treated with oxygen or a material containing oxygen to reduce the aluminum content and retain substantially the same silicon content as was present in the original burden.

This invention relates in general to a process for the production of manganese-silicon alloys and more particularly to the production of manganese-silicide.

Manganese-silicide has a high manganese and silicon content and relatively low amounts of carbon, aluminum and other elements therein. A general analysis of manganese-silicide can be said to comprise approximately 60% to 66% manganese, approximately 28% to 32% silicon, approximately 0.015% to 0.15% carbon, and approximately 0.02% to 0.14% aluminum.

Such manganese-silicide alloys are widely used as additives in the steel industry. The manganese in the alloy is useful as a deoxidizer to remove oxygen and other contaminants, to remove sulfur, and to improve the physical properties in many grades of steel. The silicon is also an effective deoxidizer and perhaps more important, the content thereof is in an inverse relationship with the carboncontent. Manganese-silicide satifies all these functions and is particularly suitable for the production of steel which has low carbon and aluminum requirements.

Conventional practice for the production of manganese-silicide is to smelt a burden of manganese ore, silicon bearing materials and fluxes in an electric furnace. Predetermined amounts of carbonaceous materials are charged into the furnace so as to obtain the desired reduction of the burden materials, while the unwanted constituents of the burden combine to form a slag.

Since the chemical specification for manganese-silicide requires relatively low carbon and aluminum, the control of the electric furnace to achieve the desired selective reduction of the burden is highly critical. Deviations in burden material analysis, variations in electric furnace operations and variations in the control of Weighing of the burden or additions thereto, all efiect the end product and make difiicult and expensive the production of a high quality product. Moreover, in the prior art process, the slag produced carries away certain amounts of the principal elements desired (i.e. manganese and silicon) from the output alloy.

The present invention provides a novel process for the production of manganese-silicon alloys which embodies a complete reduction of the burden, rather than the heretofore used selective reduction of the prior art practice, and decreases the criticality required in the furnace operation and in the measuring of the weights of the input materials. The process of the invention results in consistentlyachieving the desired chemical analysis of the manganese-silicon alloy end product and especially a manganese-silicide alloy of low aluminum content, and results in recovery of more of the principal elements desired in the end product alloy.

Accordingly, an object of the invention is to provide a novel process for the manufacture of manganese-silicon alloys.

Another object of the invention is to provide a novel process for the manufacture of manganese-silicon alloys having a low aluminum content, and wherein more consistent results in achieving the desired chemical analysis is occasioned.

Another object of the invention is to provide a novel process for the production of manganese-silicon alloys comprising the reduction of manganese and silicon bearing materials in an electric furnace by providing sufficient carbonaceous materials in the burden to reduce all the metallic oxides in the burden, and then subjecting the melt to an oxygen blow to remove much of undesirable elements in the melt, such as for instance aluminum and calcium.

A further object of the invention is to provide a process of the latter mentioned type wherein an oxygen containing compound of the metal to be recovered is added to the'melt in conjunction with the oxygen blow.

A still further object of the invention is to provide a a process of the latter mentioned type wherein the oxygen containing compound is added to the melt in lieu of the application of the oxygen blow.

Other objects and advantages of the invention will be apparent from the following description:

The present process for the manufacture of manganesesilicide or any other alloy of a different name, but having substantially the same chemical anlysis, includes reducing manganese and silicon bearing materials in a conventional electric arc furnace by providing suflicient carbonaceous materials in the burden to reduce all of the metallic oxides in the burden, as opposed to selective reduction of the metallic oxides as practiced in the prior art. Accordingly, the criticality required in furnace operation and measuring weights of the input materials is materially decreased. The complete reduction of the metallic oxides in the burden yields manganese-silicide of a high manganese and silicon content but also containing relatively high traces of undesirable contaminant elements. Generally speaking, no slag is produced during V the reduction since the burden is completely reduced. AC-

ing a refractory lining, and the molten manganese-silicide is preferably subjected to an oxygen blow to remove the majority of the undesirable elements in the melt, principally aluminum and calcium.

An alternative to the step of applying an oxygen blow is that an oxygen containing compound of manganese is added to the molten manganeses-silicide melt from the electric furnace, such as for instance manganese ore, together with a flux of lime.

Another alternative is to treat the molten manganesesilicide with both an oxygen containing compound of gianganese and an oxygen blow, and preferably with a Thus, it will be seen that the chemical analysis of the manganese-silicide (i.e. one with a low aluminum content) is accomplished by generally a two step process, or more specifically, reducing the manganese and silicon burden to manganese-silicide, and then treating the molten manganese-silicide to remove the undesirable elements therein such as aluminum and calcium, but in a manner that occurs without removing important amounts of either manganese or silicon.

The following is a typical analysis of the burden mixture which may be charged into a conventional electric arc furnace:

The manganese ore of the type preferred for use in the present process is one that has a high manganese content and a high ratio of manganese to iron. An analysis of such ore may range from approximately 47% to 59% manganese, approximately 1.2% to 1.5% iron, approximately 0.69% to 3.0% A1 approximately 0.01% to 0.05% phosphorous, and the usual amounts of silica. 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. A relatively low gangue ore is preferred, since this process involves substantially complete reduction, and therefore generally all of the metallic oxides in the burden will be reduced.

A satisfactory mix of carbonaceous material has been found to be 1260 pounds of wood chips, 966 pounds of buckwheat coke and 546 pounds of metallurgical coal per net ton of product.

Upon reduction of the burden in the electric furnace, certain amounts of impurities, and notably aluminum and calcium are found to exist in the manganese-silicide. A typical analysis of the manganese-silicide product produced by dry smelting, and as removed or tapped from an electric furnace may be as follows:

Percent. Manganese 60.7-62.9 Silicon 28-29 Aluminum 0.80-0.88 Calcium 0.011-0.034

The balance consists of iron, carbon (generally between approximately 0.06% to 0.24%) and traces of other elements. However, an aluminum content as high as 1.55% has been found to exist in the tapped manganese-silicide upon dry reducing of the burden in the electric furnace, as may be seen from the hereinafter set forth data.

The next step in the subject process is to decrease the amount of the impurities, mainly aluminum and calcium, which have entered the product as impurities in the burden material. The injection of gaseous oxygen, which may be of the industrial grade, has been found to be the preferred method.

The molten manganese-silicide from the electric furnace is moved or poured into a reaction ladle having a suitable heat resistant lining, such as Helspot, and which ladle preferably has the oxygen orifice located on the bottom thereof. Thus, the molten manganese-silicide is preferably treated with oxygen by bottomblowingThe oxygen is preferably turned on before the molten manganesesilicide covers the bottom of the reaction ladle.

The following example shows the chemical analysis of. one heat, identified as Heat No. 1, of manganese-silicide before application of the oxygen thereto:

HEAT NO. 1

Percent Mn 61.00 Silicon 31.60 Aluminum 1.05 'Calcium 0.034

After application of oxygen to the melt, and in an amount approximately twice the theoretical amount necessary to oxidize the aluminum and calcium, the analysis was as follows:

Percent Manganese 63.00 Silicon 31.20 Aluminum 0.068

Calcium 0.012

In another heat identified as Heat No. 2, the starting alloy had the following nominal composition:

HEAT NO. 2

Percent Manganese 62.80 Silicon 31.60 Aluminum 0.95 Calcium 0.011

After application of oxygen, the analysis was as follows:

Percent Manganese 63.00 Silicon 31.20 Aluminum 0.024 Calcium 0.011

The oxygen is preferably used at a flow rate of approx imately 60 to cubic feet per minute and the amount of oxygen used preferably varies with the aluminum content of the manganese-silicide coming from the electric furnace. The following table sets forth the preferred amounts of oxygen applied to the molten manganesesilicide when the aluminum content is within the ranges specified.

Initial aluminum content of manganese-silicon alloy:

Oxygen, cu. ft./net ton of final product Over 1.00% 800 0.50% to 1.00% 600- Less than 0.50% 560 At the temperatures involved (generally between approximately 2600 F. to 3300 F.) the reactions tend strongly to the right, yielding manganese and forcing aluminum and calcium to form their respective oxides. The reaction between the molten manganese-silcide and the manganese ore is sufiiciently exothermic to melt the ore in a few seconds. A lime addition may be added to quell the forming of the slag produced in this treatment. The melt after treatment with the ore is preferably held for a period of time before casting into molds, similarly to the oxygen treatment. A typical analysis of the manganese-silicide before and after the treatment with manganese ore is as follows:

HEAT N O. 3

As Tapped, After Ore Percent Addition, Percent Manganese 62.9 67. 1 Silicon 28. l 25. 2 Aluminum 0.86 0. 16

Approximately 275 pounds of manganese ore per net ton of final product is preferably added, and lime additions of aproximately 10 to 40 pounds per net'ton final product are desirable for quelling the foaming of the slag. Repouring of the melt several times from one ladle to another may be used to insure good mixing of the ore It will be noted that this method, while decreasing'the aluminum content, also causes a loss in the silicon content.

In the above ore-oxygen process, the ore is generally added to a reaction vessel with the molten manganese silicide basis melt therein, and mixed with the basis melt as for instance by pouring the mixture of ore and basis melt from one vessel into another vessel, and then back 10 again, after which the oxygen blow is applied to the mixture of manganese-silicide and ore. Contact between the manganese ore and the manganese-silicide results in a somewhat violent reaction which is sufliciently exoseconds. Occasionally there are surges of reaction which tend to foam the slag produced, and adding of lime as li id lt; aforediscussed to the foaming slag reduces the reaction 20 and quells the foaming.

The following tables list examples of recorded results 65:; fiifififig of heats of manganese-silicide treated by the above dis- Percent cussed three types of treatments. Furnace Analysis resis manganese-s1 HEAT NO. 4

As Tapped, Percent with the basis melt. While this treatment effectively lowers the aluminum content, it also generally results in an undesirable decrease in the silicon in the manganesesilicide. Thus, treatment with ore preferably includes starting with a higher silicon level in the basis manganese- 5 silicide melt.

Another alternate method of producing manganesesilicide with low aluminum and calcium content is to treat the manganese-silicide basis melt from the dry smelting in an electric arc furnace with an oxygen containing compound of the metal to be recovered and oxygen. The melt after treatment with the oxygen and ore is preferably held in the vessel for a period of time similarly to the aforediscussed treatments. A typical analysis of manganese-silicide before and after such treat- 15 thermie as f ti d to melt the ore in a few ment with manganese ore and oxygen is as follows. About 230 pounds of manganese ore per net ton of final product and about 330 cu. ft. of oxygen per net ton of final product were added to the ba a S 3a 00000000000 t .0 0000 as d e O 6 m 1 mar P m i e Rw w 6 V. n DP 4441353 t. t r O m 00000005555 N e T 1 m 36666654444 wn S 1 1 0 00 00 000 a I a O u n 0% O WWOOMMWOOMOOO e H O M 2 2333 20232400 2 M ed n m m um LLLILILLLLLII U A t am 0000000 C d s. 61 t .d 555 O O .D 777 n f t" w 0000m000000 LA p g g 0000 00000 w n .m 7877578887 1 1 y 1 1 r v 1 v v 1 n m m n 11111111111 m. Mm 000 00000000000 t M w C MUM d 555%55555555555 f 0 1 0000000 0 77777777777777 r. 0.. 0000555 A 0 t g .80. 7770777 U S y n m mm L, H e n n 8 1 78881068198 9 L o d E m. 600 606 060 66 0 E m m a R e t 84 7 6446 7 m r. m w 0 t G W N QIWOMOOOOQWOW o L s t n 1 0643447 4 Y oouaoodaaaaouuu e n .H A .W. w A 1111111 1 .X

.m P t m E H 0 0 0 0 0 0 0 0 O 9 C m N A 1 88409229380 6 N D D .W o C e E S Z QLZLRVHHWOQQ 9 A s m t a W G m 2 333322222 2 G N A m m S Y m N .W A t 528756471720492 H S 0 6 & Li0m2 oo 0w6 5 & cm am @w M M M 1 0384689 5 m m %322%2223222%22 e s r. 7752 54 5 H T H m 2222%22 O M 2 T r n 59805031888 3 T m H m I e Am3 L2 L 162 2 W H M 66666Mm666%6 m M n H e S A S W fi n 717299034089904 3 4.31 6 Mi 3150 $7 6 w mN1 n 1241630 5 mm A M 6666%66666%666M r t .1 8 666 7 m E M h fifiwwnofifi 6 m i 4 0605 T M 7 0622mmmmm m M A m a0 L0 1 LQ0 L0 0 0 A T 57 0 E e E A 1 050062572 05731 62 R m R E .E A 334932116 30353 T e T 1 0410005 6 R n LLLQQQQQQLLLQQQ D. A 2531215 8 T W .m t QQQLLLL 0 n W 1 77844394060 7 m p 1 7 7 &La 516 c s m S 22232322 H Q A D W 1 568978209988326 G S S RWQQQWRWZZLanmLQQ-QQQL 290 m w. s zsaaass 7 e 62 U 7777 N 2222222 2 C F 77777770000 7 A m m 0 0 0 06 660 60 m N 6666 66666 0 e 1. x t 6 M F n n 355338090792155 n m n 6017020 7 5 666665556666 n n u n u M Meagan m 1 6 H m A H A H 1 1 The following table illustrates the principal chemical results using averages of the above listed recorded data from the series of heats utilizing each of the three types of treatment.

TABLE 1 Treatment With- Ore Ore and Oxygen Alone Oxygen Alone Initial Mn, average percent 63.7 62. 2 60. 7 Final Mn, average percent. 67. 65. 6 63. 3

Net Change +3. 8 +3. 4 +2. 6

Initial Si, average percent 27. 9 28. 8 28. 7 Final Si, average percent 25. 5 27. 2 29. 6

Net Change -2. 4 l. 6 +0. 9

Initial Al, average percent 0. 86 0. 0.86 Final Al, average percent p 0. 14 0.07 0.09

Net Change 0. 72 0. 68 -0. 77

Estimated manganese content.

It will be noted from the above listed averages that the treatment with the ore alone resulted in a considerable decrease in the silicon content of the manganesesilicide. Treatment with both ore and oxygen, while it depressed the silicon, did so to a lesser extent than with the ore alone.

Results of the treatment with oxygen alone showed a net chemical increase in the concentration of both manganese and silicon in the manganese-silicide and also resulted in a material decrease in the amount of aluminum. Treatment with oxygen also provided for lowering of the aluminum content of the manganese-silicide to below 0.10%.

The Helspot lining of the ladle disclosed no major erosion during the production of the low aluminum and calcium manganese-silicide using the oxygen process. There was some erosion of the lining near the oxygen orifice, but this condition was readily repairable when it became pronounced.

From the above data it is concluded that the bottom blown, oxygen method is the preferred method and is eifective in lowering the aluminum content of manganesesilicide below 0.10%. This treatment results in a net concentration of both manganese and silicon in the manganese-silicide alloy, and because of its simplicity, reliability, and its good effects upon overall analysis, such treatment is preferred. A typical treatment with the oxygen took about 20 minutes, and as can be seen from the above data, about 600 cu. ft. of oxygen at between approximately 60 to 100 cu. ft. per minute was blown for each ton of alloy.

From the foregoing discussion and accompanying drawings it will be seen that the invention provides a novel process for the production of manganese-silicide and one that gives a low content of impurities such as aluminum and calcium, and one which more consistently gives the same analysis of end product. The invention also provides a process for the production of manganese-silicide which decreases the criticality required of furnace operation, measuring of input material weights, etc., and results in a process whereby the human element has little effect upon the end result.

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.

We claim:

1. A process for the production of a manganese-silicon alloy containing aluminum therein comprising, reducing a burden of manganese and silicon bearing materials in a furnace by providing suflicient reducing materials in the burden to reduce all of the metallic oxides in the burden to provide a molten basis melt, and subjecting the reduced molten basis melt to an oxygen containing substance to cause a reduction of the aluminum content thereof while maintaining substantially all of the silicon present in said reduced molten basis melt.

2. A process in accordance with claim 1, wherein said basis melt is subjected to a gaseous oxygen blow.

3. A process in accordance with claim 1, wherein said basis melt is subjected to a treatment of manganese ore.

4. A process in accordance with claim 1, wherein said basis melt is subjected to a treatment of manganese ore and to a gaseous oxygen blow.

5. A process in accordance with claim 1, wherein the aluminum content of said burden is in the range from .l5% to 1.55% and is reduced to less than .l4% upon subjecting said melt to said oxygen containing substance.

6. A process in accordance with claim 1, wherein said basis melt is subjected to a gaseous oxygen blow of approximately 600 cubic feet of oxygen per ton of low aluminum alloy produced.

7. A process in accordance with claim 1, wherein said basis melt is subjected to a treatment of approximately 275 pounds of manganese ore per ton of low aluminum alloy produced.

8. A process in accordance with claim 1, wherein said basis melt is subjected to a treatment of manganese ore of approximately 230 pounds per ton of low aluminum alloy produced and then is subjected to a gaseous oxygen blow of approximately 330 cubic feet of oxygen per ton of low aluminum alloy produced.

9. A process in accordance with claim 6, wherein said oxygen blow is applied from the bottom of said basis melt at a flow rate of approximately 60 to cubic feet per minute.

10. A process in accordance with claim 9 including holding the treated alloy in a vessel for between approximately 15 to 60 minutes, and then pouring the treated alloy from the vessel for subsequent solidification thereof.

11. A process in accordance with claim 1, wherein said molten basis melt comprises approximately 57% to 68% manganese, approximately 23% to 32% silicon, and approximately .l5% to 1.55% aluminum.

12. A process in accordance with claim 11, wherein said basis melt is subjected to a gaseous oxygen blow of approximately 600 cubic feet of oxygen per ton of low aluminum alloy produced at a flow rate of between approximately 60 to 100 cubic feet per minute, and wherein the aluminum content is reduced below 0.10%.

13. A process for the production of a manganese silicide alloy having an aluminum content of no more than 0.10% comprising, providing a reduced molten basis melt of manganese-silicide alloy comprising between aproximately 60.7% to 62.9% manganese, between approximately 28% to 29% silicon, and between approximately 0.80% to 0.88% aluminum, subjecting said reduced basis melt to an oxyygen blow of approximately 600 cubic feet of oxygen per ton of low aluminum alloy produced at a how rate of between approximately 60 to 100 cubic feet of oxygen per minute, to reduce the aluminum content to no more than 0.10%, holding the treated alloy in a vessel for between approximately 15 to 60 minutes, and then pouring the treated alloy from the vessel to permit solidification thereof.

14. A process for the production of a manganese-silicon alloy comprising, reducing manganese and silicon bearing materials in an electric furnace by providing suflicient carbonaceous materials in the burden to reduce all of the metallic oxides in the burden, removing the molten manganese-silicide from the furnace, and subjecting the molten manganese-silicide to an oxygen containing substance to cause a reduction in the aluminum content thereof.

15. A process in accordance with claim 14, wherein said molten manganese-silicide is subjected to a gaseous oxygen blow to cause a reduction in the aluminum content thereof.

16. A process in accordance with claim 14, wherein said burden comprises approximately 2940" pounds of manganese ore per net ton of final product, approximately 1512 pounds of silicon gravel per net ton of final product, approximately 2772 pounds of carbonaceous materials per net ton of final product .and approximately 42 pounds of steel scrap material per net ton of final product.

17. A process in accordance with claim 16, wherein said carbonaceous materials comprise approximately 1260 pounds of wood chips, approximately 966 pounds of buckwheat coke and approximately 546 pounds of meallurgical coal per net ton of final product.

18. A process for the production of manganese-silicide having a low aluminum content comprising the steps of providing a burden of manganese and silicon bearing materials in an electric arc furnace, providing sutficient carbonaceous materials in the burden to reduce all of the metallic oxides in the burden, operating the furnace to completely reduce all of the metallic oxides in the burden, removing the molten manganese-silicide from the furnace and subjecting the molten manganese-silicide to an oxygen blow to reduce the aluminum content thereof to not more than 0.10% aluminum.

19. A process for the production of manganese-silicide having a low aluminum content comprising the steps of, providing a burden of manganese ore and silicon gravel in an electric arc furnace, providing sufiicient carboaluminum content thereof to no more than 0.10% and to increase the manganese and silicon contents thereof.

20. A process in accordance with claim 19', wherein said basis melt is subjected to an oxygen blow of approximately 600 cubic feet of oxygen per ton of low aluminum manganese-silicide produced at a flow rate of to 100 cubic feet of oxygen per minute.

References Cited UNITED STATES PATENTS 882,582 3/1908 Price 10 X 1,363,657 12/1920 Kalling et al. 7580 1,531,513 3/1925 Fould 7560 2,799,574 7/1957 Rasmussen 7510 2,805,933 9/ 1957 Meyer et al. 7560 2,866,701 12/1958 Strauss 7560 3,240,591 3/1966 Keyser 7580 DAVID L. RECK, Primary Examiner.

H. W. TARRING, Assistant Examiner.