Aspects of the smelting of high-vanadium pig iron

Abstract

The Chusovoi Metallurgical Plant is working constantly to increase the vanadium content of its pig iron. For example, a charge that contained vanadium converter slag was used over an 8-day period in 1964 on blast furnace (BF) No. 1. The average consumption of the slag was 222 kg/ton iron (the chemical composition of the slag and the resulting pig iron are shown in Tables 1 and 2). Thus, the V20 5 content of the furnace slag was increased from 0.14 to 0.35%, while the vanadium distribution coefficient L v = [V]/(V) was decreased from 7.5 to 6.25. The vanadium content of the commercial pig iron remained at the previous level -80.53% (81% in the control period). The pig iron was processed further in accordance with the normal flow chart [ 1 ].In 1987, ash from heating and electric power plants (HPP) was used to increase the vanadium content of the iron. Ash in amounts of 20-30% was added to the charge at the local sinter plant to obtain a special sinter ( Table 1). The percentage of sinter in the charge of 225-m 3 blast furnace No. 1 was varied from 23 to 50% (Table 2). Here, the V205 content of the furnace slag was increased from 0.23 to 0.67%, while the vanadium distribution coefficient L v was raised from 4.5 to 13.4. The losses of vanadium with the top dust were large (2.89--4.60 V205). The iron was shipped to customers as a commercial product [2].In 1997, slag formed at the Nizhniy Tagil Metallurgical Combine (NTMK) in the converter production of steel from vanadium pig iron by the monoprocess [3] was used in the charge of BF No. 2. A distinguishing feature of the converter slag (CVS) is its fairly high contents ofVeO 5 and CaO. The slag also contains 10-12% scrap.Calculations showed that since the Chusovoi plant was also using unfluxed pellets from the Kachkanar Mining-Concentration Combine (KGOK) and since the consumption of raw limestone was thus very high (127 kJton pig), the introduction of CVS would make it possible to significantly reduce the content of flux in the blast-furnace charge: 100 kg of CVS should replace 41 kg of limestone, while a CVS consumption of 100 kg/ton pig was expected to increase the vanadium content of the metal from 0.484 to 0.750%.To check these calculated results, trial heats involving the use of CVS were conducted on BF No. 2 during the period Nov. [13][14][15][16][17][18][19][20] 1997. A CVS consumption of 43 kg/ton pig kept the productivity of the furnace at 1502 tons/day, the adjusted consumptions of coke and flux were reduced by 13 and 8 kg/ton, respectively, and the vanadium content of the pig iron was increased from 0.506 to 0.638% (Table 3). No complications arose in the running of the furnace. The positive results obtained from these heats made it possible to permanently institute the use of CVS in the charge of BF No. 2 beginning in January, 1998.The operating conditions of BF No. 2 improved significantly after it was subjected to a class II overhaul (April-June 1998). In addition, reconstruction of the central trough nearly eliminated the need for slow-speed operation...