Title of Invention	PROCESS FOR PRODUCING PIG IRON IN MINI BLAST FURNACES
Abstract	This invention relates to a cost efficient process for producing pig iron by smelting in a mini blast furnace. A fuel composition of metallurgical coke containing upto 50% by weight of lignite is used as fuel and reducing agent which reduces slag formation and increases the yield of iron.

Full Text

This invention relates to a process for produc i OR pig i ron i by smelting iron ore in mini blast furnaces, .' i : i Various methods of extracting iron from natura I I y occu r i ng iron ore have been known to man for almost 5000 years, one of the most successful methods of iron ore refining is by sine 1 t i ng t he ore in blast furnaces whi ch are vert i caI shaft furnaces into the top of which ores, fuels and other required fluxes are charged. Pre-heated air with or wi thout enr i chement with oxygen is b1 own through the charge from below. The products separate into two distinct 1 ayers of s1ag 1ayer and metal 1ayer, whi ch are t apped. I ton produced by blast furnace Sme11 ing of iron ore is found i to have generally 93% Fe content and about 4% of carbon wh i ch i s stable and not reoxidizab1e. In 1arge integrated steel:plants blast furnaces hnv i ng a capacity to produce more than 10,000 tons of iron per day are commonly used. These pi ants■require mass i ve infrastructure, very hi gh capital investment, high' standards of technical skills, good and consistent raw material quality, precise and strictly disciplined operat ion technology and process control. !n India, during the sixties and sevent ies, many mini steel plants were erected. These plants mai nly used electric arc furnaces for producing rods, bars and the like for smelting scrap. Brazil and China have proved to the world that mini blast furnaces are tec h n i c a 1 1 y and e c on oni i c a 1 1 y mo r e v i a b I c i n supplying iron to foundries and mini steel plants. Various reductants are tried in blast furnace technology to i clue v i ron ore to metallic iron, but metallurgical coke is still widely used, Me t a 1lurg i ca1 coke is produced by high Iemporatu re carbon i sa t i on of coa I to produce a porous and s t rong fueI for use particularly in shaft furnaces. It has a lower i›urcentaµ.e of vo 1 at i I e ma 11 er than gas coke and practically the samr arriouii t of fired carbon. For obv i ous economic reasons, r 'h i nest' m i n i blast furnaces use coke based fuel while Brazil uses charcoa I based f ue 1 . 1 ncl i a impor t s mos t of its requ i remen t of met a 1 1urgi ca1 coke for mini blast .furnace sector. t hough substitutes like charcoal and bee-hive coke have been tried out. Lignite, which is readily available in certain parts of India, is a carbonaceous rocky material and is believed to be produced from plant materials which are- not subjected to ;is much heat or pressure as ordinary coal. It therefore has ,-« lower carbon content and higher volatile mat t er as compared to coa I , resulting in low ash content. One of the major prob,ems faced with by the iron industry in India is the high ash - mlcni of coke available for use in blast furnaces. Ncyvrlj | ienite Corpora t ion in India produces a 1 ow a si? 1 i gn i t e based b r i que ties commerc i a I 1 y available under the brand name "IKCO" . i j JM i t e has not been considered as a su i tab1e fuel For me t a 1 Iu r$ ii a I puiposes as it lacks strength to wi t h-s tand furnace opera t i ous. At present most of the mini blast furnaces in India operate on 100% imported me ta 11u rg i ca1 coke from Ch i na Japan and Australia. Tt has now been found that1 a mixture of lignite and metallurgical coke can be effectively used in iron smelting in mini blast furnaces , resulting in cons i de r ab 1 e reduction in t fie cost of product i on of i ron and sav i ng of va1uab I e fore i gn exchange. A major advantage of using a lignite-metallurgical coke admixture in blast furnace lies in the substantial reduction of s 1 ag production. Th i s is due to t he 1 o\v ash content of lignite based fuel. As the slag rate is reduced, the furnace can be operated more intensively and was te d i sposa1 becomes less prob1emat i c, thus improvi ng overaJI process efficiency and economics * Yet another advant age is t hat by cont ro11i ng lhe 1 i gn i t e percentage in the fuel mixture, the sulphur content of the molten met a 1 produced after the operation can be regu1 a(cd. A coke 1ign i te mixture cont a i n i ng up to 5 0% of 1 i gn i t e is found to be opt ima 1, and pos i t i ve • Howeve r , if an i ron me 1 t con t a i n i ng spec i f i eel su 1 phur content is required, the percentage of lignite in the fuel mixture may be kept to about 20%, Molten iron having a higher su1phur cont ent may be subjected to desuIphur i za t i on externally. In view of the foregoing discussion it is clear that a fuel compos i t i on conta i n i ng up to 50% 1i gn i t e and the balance of met a 1lurgi ca1 coke in i ron ore sme11 i ng in mini blast furnaces. increases the yield of iron, decreases slag product i on. reduces cost effectively and saves fo re i gn exchahge. Accord ing1y, the present i nvent ion relates to a process for producing pig iron which compr i ses sme.1 t i ng iron ore in a mini blast furnace under known sine 1 t i ng conditions, wherein the iron ore is charged with metallurgical coke containing upt.o 50-v by we ight of 1 i gn ite, and subsequently separating the meta I 1 aye r and slag layer by known means* Lignite may be charged to the blast furnace top by any of the fo11owi ng methods. (1) The desired quantity of lignite is admixed with me tallurgi caI coke and cha rged* (2) The desired quantity of lignite is charged with the iron ore. ! (3) The des i red quant i ty of Ii gn i t e is cha rged per iod i ca1 ly. (4) The 1igni te may be added part 1 y with the iion ore and partly with metallurgical coke in layers. No abnorma1i ty either in furnace behav i on r or in the sme11 i ng process was observed when sme 11 i ng ope rat i cms were carried out b}r a process of our invention. The resulting pig i ron exhibited subs tant i a 1 re-duct ion in phosphorous ‹:‹uU en t when upto 20% by weight of lignite was used. Sulphur content of the me 11 was also found within the desired I eve 1 when upto 20'" of lignite was used. Hence the optimum percentage of lignite is considered to be about 20% of metallurgical coal. A combination of low phosphorous iron ore and lignite shall be ideal for the production of low phosphorous pig imm which is in great demand. In case higher percentage of lignite is used, the melt may cont ai n more than the desired pe rcen t age of sulphur content. Desu 1 phur i sat ion may then be carried out externally t o reduce the su 1 phu r con tent. Obv i ous mod i f i cat ions and alterations known to persons skilled in the art are within the scope and ambit ol this invent ion and the appended c1 a i ms. We Claim: 1 . A process for produc i ng pig iron comprising sine It i ng iron ,ore in a mini blast furnace under known smelting conditions, wherein the iron ore is charged with me t a I 1uig; i‹_a I c o k e containing upto 5 0% by weight of Iignite, and subsequently separat i ng t he me t a 1 1 aye r and the s1ag layer by known means. 2 . The process a is c1aimed in claim 1 where in the me 1 a I I urg i ca 1 coke contains upto 20% by we i gh t of lignite t he re by m.i int a i n i ng the sulphur content of the me It to the desired level. 3. The process as claimed in claim 1 wherein the metallurgical coke cont a ins from 2 1 to 50% by we i ght of I i pn i te and t he resulting me It is desu I phur i seel externally to reduce its su I phur content by known means, optionally. 4 . The process as c1 a i med in c1 a i ms 1 to 3 whe re in the lignite content is charged in layers, par t1y with the i ron o\e and partly with the me t a 1 .1 urg i ca 1 coke . i 5. The process as claimed in claims 1 to 3 wherein the lignite cont ent is charged along with the me t a 1 1u rg i ca1 coke , 6. The process as claimed in claims I to 3 wherein th? lignite content is added to the furnace periodically. We Claim: 1 . A process for produc i ng pig iron comprising sine It i ng iron ,ore in a mini blast furnace under known smelting conditions, wherein the iron ore is charged with me t a I 1uig; i‹_a I c o k e containing upto 5 0% by weight of Iignite, and subsequently separat i ng t he me t a 1 1 aye r and the s1ag layer by known means. 2 . The process a is c1aimed in claim 1 where in the me 1 a I I urg i ca 1 coke contains upto 20% by we i gh t of lignite t he re by m.i int a i n i ng the sulphur content of the me It to the desired level. 3. The process as claimed in claim 1 wherein the metallurgical coke cont a ins from 2 1 to 50% by we i ght of I i pn i te and t he resulting me It is desu I phur i seel externally to reduce its su I phur content by known means, optionally. 4 . The process as c1 a i med in c1 a i ms 1 to 3 whe re in the lignite content is charged in layers, par t1y with the i ron o\e and partly with the me t a 1 .1 urg i ca 1 coke . i 5. The process as claimed in claims 1 to 3 wherein the lignite cont ent is charged along with the me t a 1 1u rg i ca1 coke , 6. The process as claimed in claims I to 3 wherein th? lignite content is added to the furnace periodically.

Documents:

2243-mas-1997-abstract.pdf

2243-mas-1997-claims filed.pdf

2243-mas-1997-claims granted.pdf

2243-mas-1997-correspondnece-others.pdf

2243-mas-1997-correspondnece-po.pdf

2243-mas-1997-description(complete)filed.pdf

2243-mas-1997-description(complete)granted.pdf

2243-mas-1997-form 1.pdf

2243-mas-1997-form 19.pdf

2243-mas-1997-form 26.pdf