US2453050A - Process of smelting titaniferous ore - Google Patents

Description

Patented Nov. 2, 1948 rnocuss or SMEL'IING riranrrnnoos one 1 Forrest L. 'llurbett; Joplin, MO., assignor to The, Eagle-Fisher Company, a corporation at Ohio No Drawing. Application February 25,1944,

Serial No. 523,931

This invention relates to a process of smelting iron ores with particular reference to iron ores which contain fairly large percentages. of titanium, such as the titaniferous magnetite ores.

Many attempts have been made to smelt iron ores containing titanium in conventional iron blast furnaces by the usual process of reduction. These attempts have heretofore failed, because the titanium contributes to increased viscosity of the slag and also to some extent enters the iron. According to some theories, highly infusible titanium nitride crusts are formed which interfere with the normal settling of the furnace. Other attempts have been made to smelt iron and to increase the fluidity of theslag by using alkali metal. fluxes. While these attempts were in the right direction, they did not become commercial, I believe, for the reason that it is diflicult to hold an alkali metal flux in a furnace at high temperatures. Nevertheless, such fluxes benefit both the iron and the slag by promoting a clean separation of the titanium into the slag.

According to the present invention, I follow the prior art to a limited extent in that I use an alkali metal flux and carbon inthe preliminary reduction. I depart from the prior art, however, in that I very soon replace a substantial part of the alkali metal flux, which may be sodium car bonaie'by a non-volatile flux, which may be lime or limestone. carbon I use a coking coal, which enables me to produce almost complete reduction by the first smelting operation which produces a dispersion of metallic iron and sodium titanate in a mechan ically strong porous form of carbon, which is coke.

The physical state of this product is vital to the success of my process, because without mechan ical strength, it would be crushed in the furnace,

and without porosity it would be impossible to force oxidizing gases through it at a rate sufficient to. make the process fast enough for commercial success. A third difference from the prior artisj that my process is a dry one throughout; I employ no liquids to separate the slag from the iron.

The speed of my process is thereby much in'- creased,and the amount of apparatus necessary I do not require the high is much diminished. blast furnacebut only aconventional coke oven and a lqyy melting furnace of the cupola type.

My process of treating a titaniferous iron. ore

Another departure is that for the 6 clams. (Cl. 75-30) convenient. I mix the subdivided ore with finely divided coking coal, althoughthe mesh size of the coalis also not critical; ,To this mixture I add soda ash (preferably anhydrous). A typical blend maybe as followsz a 1 I r y 3 Pounds: Ground OI'GhLL. I .100 Ground coal, preferablyof .vth coking type 50-100; Soda ash=(56% NazO) a ;510 While I -have sodiumf carbonate as. source of alkali metal, I may usesodium sulphate sodium chloride, sodium hydroxide, or. the; corresponding potassium compounds.

After thoroughly blending, I l ce in any suitable type of coking oven preheated to about 190051 I continue the heating at. about 2000" F. until all volatile material such as. coal gas; and gas formed from thereduction of the; ironlis removed. This usually tak esabout 9hours for the normal volume ofcharge, but the time is regulated by the volume of charge The coking procedure takes place rnorerapidly than-if a;

solid charge of coal is usedion account Ioftha greater thermal conductivity of' the ore. When the charge is first placed in thefurnace, a very heavy flow of .gas is evolved which consists of tars and low temperature volatilecoal gas. pAs'the temperature: in the retort p rises, much carbon monoxide is produced by the reaction between.

hydrocarbon. gases and the ironore. It is probable that some of the carbon of the coal enters; into thereduction of the ore, althoughl believe: that underthe .conditionsldescribed, themajon part of thereduction is accomplished by the vola-w tile gases. dit'ions the particles ofciron ore are reducedto metallic ironalmost completely. My results show that abo've reduction is accomplishedeand possibly-over 99%. may be accomplished, and the sodium carbonate enters largelyinto combination:

which case there would also be present metallic silicates; I have called this product metallized coke, andI" prefer it =t0 run'irom20% to 27% of fixed carbon, 1. e. iust en'oughto support the iurnacecharge and to furnish heat foi' rne'ltln'g it in the nextstep Itjanalyzes also from 34 to 37% Fewith proportions of titanium silicatesl I have found that under-these con-.

calcium sodium silicates, and, if V-bearing ores have been worked, a substantial proportion of V205.

I remove the metallized coke from the coke retort. It is preferred to cool this coke in an enclosed chamber to prevent oxidation at the high temperature at which it is removed. I now complete the production of metallic-.ironabya second step which Iconsider as a process of melting'and" coalescing the finely divided iron particles. This may be done in several types of furnace, such as cupola, a regular blast furnaoe;,on-a:reuerberatory' type of furnace. Since the ordinary iron blast furnace process involves the" reduction or? the ore as well as the melting of the reduced iron; my metallized coke, which also requiresgmelting-of the iron but not its reduction, does not needzthe excessive size and costly construction of the regular iron blast furnace.vv It is probable that an" electric furnace would involve too much cost for commercial productionof pig iron, but it' would perform the operation very satisfactorily.

Thereverberatory typemay also be used, but I prefer the cupola" type-of'furnace. In such a furnace I introduce the metallized coke with add'i tio'nal; from to by weight, calcium carbona-te or magnesium carbonateor both of the corresponding" oxides, depending on the desired composition of the resulting slag and also on the slag-forming impurities inthe original ore. Such additions mustbe predetermined by a knowledge of the impurities originally present andthe meltingpoint of'the; slags' which can be made from time to-time; Tlie operations-of thecupola is verysimilar to the ordinary-foundry cupola in which operation-iron or-pig-iron is mixed with coke and the-metal melted with a blast or air blown dium. Since thesulphur" and phosphorus-content:

otwestern U'. S: titaniferous iron ore is very'low; I find; that the pig' producedi frrm these ores requires: less purification for refining to steel than does the pig; fromthe usual iron ores. The pro -v duction ofpure titanium 'dioxide and from the titan-iferous; Slag: hich" I produce" by my process is very muchitsimpler' and cheaper than from the ordinary source of'titanium' which is ilmem'te ore; This process will allow; Iibe'lieva'the commercial: use'ofithe large quantitiesofi titaniferous'iron ores knownsto exist: in' this country and which. area now practically Y us el'ess.t

claim: aslmyl invention:

The processofi smelting titaniferous iron ore which-"comprises subdividing the ore,v mixingtherewithjfinely-divided coking coaland a minor proportion of: a solid, non-siliceous alkali-metali compound-giving a fusible slag, thenu'educing the.

ores-and cokingthe coal; to form; an iron sodium;

titanatedispersiominzaimechanically strong form- 0i; carbon; adding-"a1 substantial proportion off a;

flux consistingtessentially of an alkaline-earth-- metal compound; then. separating the iron from thevcokeiby burningioutlthe latter thereby reache in atemperature above the melting-point, oi? the,

iron, and then separating the molten iron from the generated slag.

2. The process of smelting titaniferous magnetite ore which comprises grinding the ore, mixing therewith a major proportion of finely divided coking coal and a minor but sufficient proportion of a solid non-siliceous sodium salt capable of giving aifusible slag, then reducing the ore and simultaneously coking the coal, adding a substantial portion of a flux consisting essentially of an alkaline earth metal compound containing chemically-boundoxygen, then separating the iron from the coke by burning out the latter to reach a temperature above the melting point of the iron and of the-titaniierous slag, and then separating the iron from theslag,

3. The process of smelting titaniferous magnetite ore which comprises reducing the size of the ore particles to about 2 mesh to 8 mesh, mixing therewith a major proportion of finely-divided coking coal: and about 3% to 10% of sodium carbonate, calculated on the anhydrous basis, subjectingr' the mixture to reduction under coking conditions for about 5 to 20 hours, adding a substantial portion of a flux consistingessentially of an: alkaline earth metal compound containing chemically bound oxygen, and then burning out;

the carbon at a temperature above the melting point of the ferrous metallic component and above slag; and then separating the molten iron from the molten slag.

4. The process ofsmelting titaniferous iron ore which comprises reducing the particle size of the ore to from 2 to 8 mesh, mixing therewith, per partsof' ore, from 50 to lbs. of finely-divided coking coal and from 3% to 10% of the weight of the'mixture of a solid non-siliceous sodium salt capable of, forming sodium titanate under smeltingconditions, coking the coal in the mixture under conditions to form a dispersion of reduced iron and sodium titanatein a mechanically strong form of? porous carbon, adding at least enough of a flux consisting essentially of an alkaline earth metal compound containing chemically bound oxygen to compensate for the loss of alkali metal by volatilization, then burning the carbon out of said. dispersion at a temperature above the melting point of iron and above the melting point of titaniferousr slag to generate a mass of molten ironin a molten mass of slag, and thereupon separating theslag from the iron.

5. The process of smelting a titaniferous iron me which comprises mixing the subdivided ore with a nearly equal weight of coking coal in finely divided condition and a minor proportion of a solid, non-siliceous alkali-metal compound giving a fusible slag, subjecting the mixture to a coking operation at a temperature of about 2000 F., thereby producing a dispersion of iron and sodium titanate inza mechanically strong form of carbon, then adding a flux consisting essentially of an alkaline-earth compound containing chemically bound oxygen, heating the so-forme-d charge with access to oxygen to burn the carbon to a temperature at which the slag and the iron will freely separate and then separating them.

6.. The process of smelting titaniferous iron ore which comprises mixing the subdivided ore with coking coal andsodaash in the approximate proportions;

Pounds Ground or e v 100 Ground coking coal 50 to 110 I Soda ash. anhydrousbasis) v v 5 to. 10-

the melting point of the so-generated titaniferous heating the charge so-formed to about 2000' F. for from 5 to 20 hours under reducing conditions.

then heating the so-formed coked mass with no oess of air and with the addition of 5% to 211%,v of its weight of a, fixed flux consisting essentially of an alkaline-earth compound containing chemically bound oxygen, to a. temperature high enough to permit clean separation or the slag from the iron and then separating these two.

FORREST L. TURBE'i'r.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date- Rossi Nov. 29, 1892 Asak Apr. 15, 1941 FOREIGN PA'I'ENTS Country Date -Great Britain 1866