In the hydrometallurgical processing of vanadium slags and the recovery of vanadium pentoxide from the slag, the main phase of the slags -the spinellide -is the phase of the greatest interest from a commercial standpoint.Experience shows that the amount of spinellide which is present varies widely from one heat to the next -from 43 to 78%. This index affects not only the composition of the pig iron being made, but also the specifications of the chosen oxidant, the composition of the additions, the temperature of the pig, and other characteristics.To establish the relationship between the chemical composition of the converter slag and the concentration of spinellide, we statistically analyzed the results from a chemical analysis of a large number of slags. We analyzed about 30 railcars of converter slag that arrived at the shop over a period of 2-2.5 months. Chemical composition was determined by sampling the slag in accordance with the method adopted at the plant: crushing, followed by separation of metallic iron in the form of inclusions, scrap, and dispersed iron. To perform a petrographic analysis, five small samples of slag up to 80 mm in size were taken from each railcar load during the crushing operation. The results of the analysis were then averaged.The slags were divided into three groups based on the concentration of spinellide: nominally, 50%, 60%, and 70%; the actual concentrations were 51.3, 59.99, and 69.7%. The ranges of spinellide concentration in the different groups were 43.4-56.1, 57.2--62.0, and 65.1-78.8%, respectively. The chemical composition of the slags in each group was averaged over 10, 12, and 8 tests (Table 1).It can be seen from the table that metallic inclusions have the greatest effect on the concentration of spinellide. The mechanism of this effect is still unclear, but it can be stated that converter slag which contains no more than 19% metallic inclusions will have a spinellide content in the range 65-75%. A relationship was found to exist between spinellide content and the content of vanadium oxides, but it was not as explicit as had been expected. No relationship was found between spinellide content and the other components of the slag.The presence of spinellide in the slag is not by itself sufficient to be able to fully extract the vanadium in the slag during hydrochemical treatment. An equally important factor is the size of the spinellide grains that are formed. According to process specifications, the optimum grain size is within the range 10-15 Bm. Under production conditions, up to 60-70% of the total mass of spinellides consists of grains of 2.5-5.0 Bin. We assumed that spinellide grains were formed not only during the formation of the slag in the converter, but also during its cooling in air after tapping. To confirm this, we conducted an experiment to establish the effect of cooling time on the granulometric composition of the spinellides in converter slag; vanadium slag from recent commercial heats was used in the experiment. After being discharged from the furnace, ...
The duplex steelmaking shop at the Chusovoi Metallurgical Plant began operation in 1946. The shop includes a 400-ton mixer, three 20-ton Bessemer converters, and two 270-ton open-hearth (OH) furnaces. The shop specializes in refining naturally alloyed vanadium pig iron in the converters to produce vanadium slag and a carbon-bearing semifinished product which is subsequently transformed into steel in the OH furnaces and into a commercial semifinished product.The vanadium pig iron is sent to the mixing department in 50-ton ladles. The pig is then transferred to a 25-ton hot-metal-car ladle which has a ladle-tilting mechanism. The car transports the hot metal to the converter department, where it is poured into the Bessemer converters. Before the pouring operation, sinter or scale is charged into the furnace by an 80/20-ton overhead travelling crane.The metal is bottom-blown by compressed air with a pressure of 0.20--0.22 MPa (2.0-2.2 psig) at a rate of 500 m3/min under normal conditions. The duration of the heat is 15-16 min, including 5-6 min of blowing. The converter has a basic (magnesite) lining except for the bottom, which has an acid (dinas) lining. These linings have a maximum life of 3000 and 400 heats, respectively.The resulting semifinished product, which contains 3.0-3.5% C and 0.04---0.07 V, is poured into a 50-ton steel-car ladle (two heats are poured into one ladle) and sent to the OH furnaces.The OH department has two OH furnaces. The furnaces are provided with evaporative cooling and are fired by natural gas (70%) and carbureted fuel oil (30%). The outgoing heat is used in waste-heat boilers. The furnaces are equipped with a system that completely automates the thermal regime. Each OH furnace is charged by two crane-type changing machines with a capacity of 5/20 tons. The liquid semifinished product is charged in 50-ton ladles with the use of an 80/20-ton crane. The steel is tapped into two 130-ton steel-pouring ladles.The pouring bay is serviced by three 180/50/15-ton cranes. The liquid metal is bottom-poured into closed-bottom ingot molds placed on 12 carts (16 molds on each cart, with another 8 molds located on a tray); each ingot weighs 1890 kg. The compositions used for refining are prepared in two bays. During 1988 the duplex shop made 395,500 tons of steel, including 182,000 tons of ordinary grades, 15,500 tons of quality grades, 4,300 tons of free-cutting steel, 61,800 tons of chromium steel, 23,700 tons of silicon steel, 92,800 tons of manganese steel, and 15,400 tons of low-alloy steel.Solving the problem of attaining high technical-economic indices will require a complete reconstruction of the shop. The metallurgical complex should include highly efficient and economical conversion of vanadium pig iron, with the recovery of 95% of the vanadium in the slag.World steelmaking practice shows that converter steelmaking is characterized by a relatively high level of technological sophistication, making it possible to produce steel from pig irons of a wide range of compositions. This is very imp...
The oxidant usually used in the blowing of vanadium-bearing conversion pig irons in converters is a special agglomerate which ensures that the process of the removal of vanadium from the pig proceeds to completion. However, for several reasons, the composition and structure of the converter slag formed in this process does not always meet the requirements of the customers for this product.In particular, the slags formed at the Chusovoi Metallurgical Plant have a relatively high content of metal (in the form of inclusions, scrap, and dispersed iron), which increases the physical losses of the slag during separation and complicates the slag's chemical treatment during roasting and leaching. In addition, there are restrictions on the allowable concentrations of Cat, dispersed iron, and other components.In light of this situation, the plant has resorted to the use of briquets of a special composition to convert vanadium-bearing conversion pig iron. The briquets ensure that the main conditions required for the removal of vanadium from the pig will be created during the steelmaking operation. The briquets were prepared by pressing the raw material with a force of up to 200 kgf/cm 2. The strength of the finished briquets is sufficient to allow them to be transported, stored, and charged into the converter. They have a density of 2.3-2.6 tons/m 3 and a moisture content of 3.4-4.8%. Table 1 shows their chemical composition compared to sinter.The main difference between the composition of the briquets and the composition of the sinter is that the briquets contain alkalis (up to 2% Na20 ) and carbon (up to 5% crushed coke). We should also point out the relatively low content of iron oxides and the high content of Fe203 among the oxides in the briquets. The total content of oxides (Cr203 + V205 + Tit2) is more than twice as great as the content of oxides in the sinter.The process of removing vanadium from pig iron with the use of briquets having the composition shown in Table 1 was studied under production conditions at the Chusovoi plant by gradually replacing sinter with briquets until just briquets were being used in the conversion of vanadium-beating conversion pig iron (Table 2).Silicon, titanium, manganese, and chromium are oxidized in the same way as in the conventional process, regardless of the type of oxidant that is used. However, we should note that the relative concentrations of manganese and chromium present during the blow were somewhat higher -0.04--0.06% -when a high percentage of briquets was used. This trend is clearer when viewed from the standpoint of vanadium content -the degree of vanadium removal from the pig iron decreased from 92.1 to 79.1%. The oxidation loss of carbon also decreased: from 18-20 to 6-7%. Thus, the decarbonization reaction was slowed as expected, but so was the rate at which vanadium was removed from the pig iron.This raises the question of whether the result just described was related to the process of oxidation of the vanadium or to the V205 capacity of the converter slag. It is a...
Fig. 2. Appearance of the rammed hearth after 7 months of operation of the furmace.The saving with such a method of repair of the worn rammed hearth during 2 years of operation of the rotary furnace of Sinarskii Pipe Plant was 93,000 rubles. For the purpose of investigation of highly resistant refractories for use in the tuyere zones of the bottoms of converters with bottom oxygen blowing after semiproduction tests,* comparative tests were made of different domestic refractories under production conditions. COMPARATIVE TESTS OF REFRACTORIES IN THE TUYERE ZONES OFTuyere refractories in the form of 280 x 225 • 190 mm blocks with a center channel under the 30 mm diameter tuyere were produced for the investigation at Magnesite Combine in TsMI-2. Blocks of type PKhK p e r i c l a s~h r o m i t e composition, type PShGP periclase with a spinel binder, type KhM chromite--periclase, KhPT, and type MKhVP periclase--chromite were produced.For production of the PKhK parts fired magnesite powder of the 3-1 and i-0 mm fractions and the finely ground fraction of fused periclase were used, for the PShGP refractories fused periclase powders of the 3-1 and i-0 mm fractions and finely ground fused periclase, for the KhM refractories chromite ore powders of the i-0 mm fraction, periclase of the 2-0 mm fraction, and finely ground periclase powder, for the KhPT refractories chromite ore powders of the 3-1 mm fraction, periclase of the 2-0 mm fraction, and finely ground periclase-chromite mixture, and for the MKhVP refractories fused periclase--chromite. The chemical compositions of the mixtures for production of the parts are given in Table i.The mixtures for preparation of the parts were prepared i n a mixing mill with moistening with a sulfite-~east mash solution with a density of 1.22 g/cm 3 at 45~The block parts were formed on a D-2240A hydraulic press with a pressure on the manometer of 18 MPa.The formed parts were placed on the furnace cars in the two upper rows of the charge and fired in a tunnel kiln.The properties of the parts are shown in Table 2.The blocks produced were tested in the bottom lining of a 22-ton converter with oxygen bottom-blowing at Chusovoi Metallurgical Plant.The installation of the blocks in the bottom is shown in Fig. i. The remaining portion of the bottom lining was prepared from MO-91 magnesite brick.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.