Dr. Joseph J Poveromo, Raw Materials & Ironmaking Global Consulting joe.poveromo@rawmaterialsiron.com DR Pellet Quality & MENA Applications
Chemistry Considerations direct reduction processes: chemical change is removal of oxygen from ore remaining constituents stay with direct reduced iron product but increase in concentration due to the removal of oxygen these affect process economics of subsequent EAF melting vessel smelting reduction processes (incl. Blast Furnace): formation of refining slag allows modification of hot metal product to meet requirements of subsequent steelmaking process
CHEMICAL PROPERTIES Direct Reduction Pellets: Maximize: Fe, total iron > 67%. Minimize: gangue, impurities, residual elements, moisture, LOI
CHEMICAL PROPERTIES Minimize: gangue SiO 2 + Al 2 O 3 + TiO 2, acid gangue prefer < 2% but accept < 3%. CaO + MgO, basic oxides basic oxides (< 3.0 %) displace purchased flux in steelmaking;
CHEMICAL PROPERTIES Minimize: impurities P, phosphorus < 0.030% P must be removed in steelmaking Mn, manganese as low as possible to reduce EAF slag formation S, sulfur < 0.008% sulfur fouls reformer catalyst in Midrex Process
CHEMICAL PROPERTIES Minimize: residuals ( Cu + Ni + Cr + Mo + Sn ) should be lower than in prime scrap; key residuals monitored in the scrap supply most important for high end flat products less important for structural steel products
DR-Grade Pellet Chemistries Canada Brazil Sweden Canada AMMC Samarco VALE LKAB IOC (ex QCM) Fe 67.70 67.90 67.80 67.90 67.75 SiO2 1.60 1.23 1.25 0.75 1.20 Al2O3 0.40 0.49 0.55 0.16 0.32 CaO 0.55 0.76 0.65 0.90 0.70 MgO 0.30 0.09 0.30 0.65 0.45 B/A 0.44 0.49 0.53 1.94 0.77 Moist. 2.0 1.5 3.0 1.6 2.0
PHYSICAL PROPERTIES shaft furnaces: DR grade pellets key physical properties are size consist, mechanical strength: economic importance (a) yield of pellet, lump ore converted to DRI (b) performance of the shaft reduction furnace unlike blast furnace, pellets (and lump ore) are only solid materials and so determine gas distribution, permeability, reduction behavior
PHYSICAL PROPERTIES Midrex Process, Pellet Size Range: 9 x 16 mm, > 85% prefer > 95% fines: -5 mm, < 5% prefer < 3% Size Range Specifics: users prefer > 50 % > 12.5 mm Fundamentals favor smaller sizes: improved heat transfer, reducibility, higher specific compression strength; fines affect permeability more than average size Practical aspects favor larger sizes: compressor pressure drop, yield after screening, compatibility with other pellet brands
PHYSICAL PROPERTIES Midrex Process, Pellet Strength : tumbler: + 6.3 mm, > 92% prefer > 95 %, abrasion - 0.5 mm, < 6%, prefer < 4% Compression > 150 kg prefer > 250 kg
Physical vs. Metallurgical Properties metallurgical properties, such as reducibility, are important but the physical characteristics will dominate the behavior and performance of the pellets: = a highly reducible but weak and/or poorly sized pellet will impair permeability and gas-solid contacting effectiveness and minimize the benefit of inherent excellent pellet reducibility
METALLURGICAL PROPERTIES Goal: highly reducible, strong, non-sticking, nonswelling pellets; key pellet metallurgical properties are reducibility, sticking tendency, and metallization
METALLURGICAL PROPERTIES Pellet sticking - major breakthrough: techniques coating coatings (limestone, dolomite, bauxite, cement, etc ) all finely ground, has virtually eliminated sticking as a factor limiting bustle temperature increase bustle temperatures by > 100 C, increased productivity by 10-20 %.
METALLURGICAL PROPERTIES reducibility, sticking tendency determine DR furnace productivity, fuel consumption metallization affects EAF performance leading DR pellets have good reducibility; can maintain 95 % metallization levels
Predicted Effect of Reducibility on DRI Cost Relative Reducibility Change in DRI Cost, $/MT 0.70 20 1.00 0 1.30-10
EFFECT OF DRI PROPERTIES ON EAF PERFORMANCE $/% SiO2 in DR pellet/t of DR pellet $ 3 6 $/% metallization/ T of DR pellet $ 2-3
DR Pellet Use In MENA
DR Pellet Use In MENA Typically 100 % DR Pellet charge minimal lump ore usage: maximum DRI production Combination of 2 4 pellet brands used; limited by day bin availability, need compatibility of pellet brands DRI produced is majority of EAF charge; limited scrap: requirement for minimal gangue, impurities
Pellet Supplier Perspective: Customer Priority Ranking DR Pellet Supply 100 % pellet operations; growing market, BF Pellet Supply to All-Pellet BF Operations proportional cutbacks in slow part of business cycle, some limited market growth BF Pellet Supply to Complement High Sinter Burdens: disproportionate cutbacks in slow business times as on site sinter operations remain maximized; also threat of displacement of acid pellets by lump ore, lesser quality (CIS) pellets; low SiO2 fluxed pellets more competitive Ranking: DR pellet>all pellet BF>Sinter/Fluxed Pellet BF>Sinter/Acid Pellet BF
What are the best practices to ensure sufficient quality and quantity of DR pellets? Value and efficiency in use how do you evaluate the different grades of feed and pellets? Diversity of suppliers and pellet quality can varying the origin and quality of pellets maximise procurement and production efficiency? Tailoring the pellet to the process how can the specific makeup of the pellets help optimise DRI production? Do long term contracts offer competitive advantages? To what extent does the dependability of demand for DR pellets give the Middle East a competitive advantage?
Thank you! Questions?