Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
  • C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
  • C22B5/06—Dry methods smelting of sulfides or formation of mattes by carbides or the like

Definitions

• the invention relates to the recovery of mium in the commercially pure state. These products are widely used for the preparation of various metals, particularly ferrous compositions such as steels and rustless lIOIlS.
• a low-carbon silicon alloy of the metal to be recovered and then desiliconize this prodnot by treating it with anoxygen-containing compound of the metal to be recovered, thereby producing metal sufliciently low in both carbon and silicon.
• the silicon alloy can be made in various ways, for example by reducing an ore with carbon in the presence of a silicious charge. However produced, the silicon alloys in question are characteristically low in carbon. I effect the desiliconization referred to above in a self-propagating silico-thermic reaction and thus bring about an important saving in time, power and apparatus.
• the desiliconization of a very large quantity of silicon alloy can be carried out silico-thermically in a fraction of an hour, and often in a few minutes, and
• a refractory pot or vessel to hold the charge and the reaction products.
• this latter operation is so carried out as to produce a silicon alloy suitable for the silico-thermic reaction described above.
• This combination of steps makes it possible to operate economically even when no metal is reduced from the .ore or other metal-oxygen compound in the desiliconizing step, the ore acting merely as an oxidizing agent. It is possible, and in some cases is preferred, to increase the efficiency of the desiliconization by using a highly oxidized metal compound, for example vanadium pentoxide, vanadates, chromic anhydride, chromates, and manganese dioxide in the desiliconizing step, and to reduce little or none of such highly oxidized compound to metal.
• a highly oxidized metal compound for example vanadium pentoxide, vanadates, chromic anhydride, chromates, and manganese dioxide
• I smelt the slag with a carbonaceous reducing agent in an electric furnace in the presence of enough silica to ensure the desired content of silicon in the alloy thereby produced.
• lhe slag is itself highly silicious but additional silicious material may be added if required.
• additions may include ores,
• the silicon-bearing material and the oxygen compound which are to react in the silico-thermic stage are finely ground and intimately mixed to expedite the reaction.
• a more rapid reaction tends to be more nearly complete, and hence to liberate more heat, and it also tends to diminish heat losses because it curtails the interval during which radiation of heat occurs.
• the preferred scale of operations is one in which the weight of the charge is at least several thousand pounds.
• the charge may generally be substantially unheated when the reaction is initiated, but an initially elevated temperature promotes the reaction. The best results follow when the charge is substantially free from moisture.
• reaction products and any nonreacting materials present must be brought to the same temperature, materials other than those which directly participate in the main reaction have the effect of limiting the maximum temperatures reached. In some cases there may be an excess of heat which can be usefully employed to melt iron or other metal which it is desired to incorporate into the product, but in general it' is desirable to avoid unnecessary quantities of heat-absorb ing substances in the charge.
• the exothermicity of the reaction may be increased by incorporating substances into the charge which do not contain the metal to be recovered, but which oxidize silicon energetically.
• the choice of an oxidizing agent for this purpose raises additional problems, of which cost is one of the most important.
• Sodium nitrate is a cheap and eflicient solid oxidizer: Alkali metal chlorates are among the most energetic of oxidizers, but they are of little value for accelerating silico-thermic I reductions because they are reduced to chlorides in the process and the chlorides boil out of the charge and absorb much heat from it. Bleaching powder is an effective accelerator under some conditions.
• the percentage of silicon remaining in the purified metal may vary rather widely in different cases.
• the percentage of Vanadium incorporated into a steel is often very small, and a correspondingly small quantity of ferrovenadium is required to introduce it.
• the ferrovenadium may in some cases contain as high as 8 or 10% of Si (with a vanadium content ofsay without undulyincreasing the Si content of the finished steel.
• the product required may be one which contains a metal of the group under discussion and silicon in such proportions that the ratio of the former to the latter is considerably above 100.
• the impure oxide contained 86.12% V 0
• the ferrovanadium silicon had the following analysis:
• the products were an alloy containing approximately of the vanadium ,of the charge, and a slag containing the balance of the vanadium.
• the products analyzed as .follows:
• the slag was snielted with carbon in an elec tric furnace to produce ferro vanadium s1licon.
• the reaction produced metal and slag, the chromium being about equally divided be-
• the slag was crushed and mixed with sillcaand carbon in the following proportions:
• the process is particularly adapted to the preparation of manganese alloys low in silicon because of the fact that manganese dioxide, a peroxidized compound, occurs in many natural ores.
• the use of such ores permits the desiliconization to be effected at the expense of the loosely combined oxygen inthe dioxide, the latter being reduced only to a lower oxide, in a vigorous self-propagating reaction giving a very high temperature and fluid products. Due to the excess of oxygenin the charge a very thorough elimination of slicon from the silicon alloy, for example manganese-silicon, is readily Ibi'dught about.
• the lower oxides of manganese originally present or produced in the desiliconization combine with the silica to form a silicate slag.
• This slag is smelted, preferably in an electric furnace with carbon and suitable additions of silicious materials, to produce a high-silicon low-carbon manganese alloy, and this alloy can be desiliconized with a1further quantity of ore in a selfpropagating reaction in the manner already described.
• the proportions used are approximately two molecules of MnO to each atom of Si. This proportion usually gives a product sufiiciently low in silicon, and if a higher silicon content is permissible a little less than this proportion of maganese dioxide can be used. Increasing the proportion of ore has the opposite effect; it gives a somewhat better elimination of silicon.
• the carbon content of the desiliconized product can be predicted from that of the manganese-silicon alloy used- Since the quantity of low silicon product is less than the quantity of manganese-silicon alloy taken (little or no manganese being reduced in the desiliconization) the carbonwill be concentrated in the product. An additional small quantity of carbon is usually introduced fortuitously.
• a manganese-silicon alloy con taining 0.7% C and 24% Si is suitable for preparing a low-silicon alloy with about 1.0% C, while a maganese-silicon alloy with 1.0% carhop and 20% silicon gives a product containing about 1.5% carbon.
• the carbon in the product may be brought-still lower by using a manganese-silicon in which the'silicon is still higher and the carbon correspondingly lower.
• Manganese ores are available in which practically all of the manganese present is in the form of dioxide.
• the content of dioxide may be .Very hi h, for example 85%, but
• the slag produced may contain, for example, about 65% MnO and about 26% SiO It may be crushed, mixed with carbon and silicon and smelted in the electric furnace without difliculty.
• the charge consisted of 26,935 lbs. ore and 14.- 948 lbs. alloy, bot-h ground to pass a mesh screen andthroughly mixed and dried.
• the charge consisted of 26.389 lbs. ore and 16,443 lbs. alloy.
• the ore was the same as in the preceding example and the alloy had the following composition:
• the ferromanganese produced contained:
• the slag contained 62.99% MnO.
• silicon as used in the appended claims embraces not only the substantially pure element but also alloys thereof high enough in silicon to adapt them for use in silico-thermic charges.
• the process of recovering a metal of the group having atomic weights between 50 and 55 which comprises preparing a charge of at least several thousand pounds comprising an oxygen compound of said metal, silicon and a solid oxidizer which reacts more energetically with silicon than does the lowest natural oxide of said metal, the components of the charge being of such fineness that a large pro portion will pass a 100 mesh screen and being intimately mixed and so proportioned as to adapt the charge to self-propagating reaction in an initially unheated environment with the production of commercially siliconfree metal; locally igniting the charge; 001- lecting t e metallic product; separately collecting e slag; and smelting the latter with electrical power to form a silicon alloy adapted to provide the silicon required in the first stage.
• the process of recovering a metal of the group having atomic weights between 50 and 55 which comprises preparing a charge of at least several thousand pounds comprising an oxygen compound of said metal, silicon, and a solid oxidizer which reacts more energetically with silicon than does the lowest natural'oxide of said metal, the components of the charge being of such fineness that a large proportion will pass a 100 mesh screen. and being intimately mixed and 'so proportioned as to adapt the charge to self-propagating reaction in an initially unheated environment with the production of commercially silicon-free metal; locally igniting the FREDERICK M. BEOKET.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23029021

Family Applications (1)

Country Status (4)

Cited By (4)

• 1928
  • 1928-04-13 US US269879A patent/US1820998A/en not_active Expired - Lifetime
• 1929
  • 1929-04-07 DE DEE39084D patent/DE639497C/de not_active Expired
  • 1929-04-10 GB GB11052/29A patent/GB309594A/en not_active Expired
  • 1929-04-10 FR FR672901D patent/FR672901A/fr not_active Expired

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