Antara Steel & HBI – 25 Years Of Adding Value To South East Asian Seelmaking
Frederick Mah And Dominic Lu
Antara Steel Mills Sdn. Bhd,
Alberto Hassan And Frank Griscom
Special Advisor Direct Reduction, IIMA,
The history of hot briquetted iron (HBI) production and use in South East Asia and the HBI plant located on Labuan Island off the coast of Sabah, Malaysia, are intimately connected. From its start-up in 1984, the plant then known as Sabah Gas Industries and today owned and operated by The Lion Group’s Antara Steel Mills Sdn. Bhd. has gained international recognition for its operational experience and expertise and its technical marketing of HBI as a value-added source of steelmaking metallics.
Today HBI is considered steel’s most versatile metallic due to its broad application potential in all types of iron and steel production processes, and the plant on Labuan Island is supplying this high quality steelmaking metallic throughout the region.
The paper will describe what HBI is and introduce the Hot Briquetted Iron Association (HBIA) (Since this report the HBI and the IPIA merged to create the IIMA (International Iron Metallics Association). Any reference to the HBIA now come under the IIMA), a not-for-profit corporation that represents the global HBI industry. We will introduce the Antara Steel Mills (Labuan) HBI Operation and use actual melting results from Megasteel Sdn. Bhd. and Amsteel Mills Sdn. Bhd. to demonstrate the value of HBI to high quality steelmaking operations.
The first modern day direct reduction plants were built adjacent to steel mills, and their product, Direct Reduced Iron or DRI, was intended for local use. As demand developed in areas where direct reduction plants were not feasible, merchant shipments of DRI began. However, incidents involving DRI cargoes raised safety concerns that resulted in increased insurance rates for shippers and a significant decline in ocean transport. A safer way to ship DRI had to be found in order for the merchant market to grow.
The answer was Hot Briquetted Iron or HBI.
The International Maritime Organization (IMO) issues guidelines for safe shipping and handling of various ocean-going cargoes. The IMO International Maritime Solid Bulk Cargoes (IMSBC) Code is the basis for national shipping regulations and insurance rates.
The IMSBC Code includes schedules for three types of Direct Reduced Iron: hot-molded briquettes or HBI is known as DRI (A); DRI in the form of cold-molded briquettes, lumps, and pellets is known as DRI (B); and byproducts of HBI and DRI production including fines are known as DRI (C).
The IMO recognizes the superior handling, shipping, and storage characteristics of HBI by recommending less stringent guidelines than for other forms of DRI. As a result, HBI is the preferred direct reduction product for long, open-ocean voyages.
What is HBI?
HBI is a dense, compacted form of DRI that was first produced by Fior de Venezuela in 1976. Today, dedicated merchant HBI plants are in operation in Venezuela, Russia, India, Malaysia, and Libya. These plants are based on direct reduction processes that use natural gas as the reductant fuel (see Figure 1).
The iron ore feed is in the form of either fines (in fluid beds) or pellets and lump (in the shaft furnaces). The feedstock is prepared to adjust the size to that required for the reduction furnace, which may require screening for separation or grinding to adjust the particle size downward.
The process gas is formed by different methods to generate the reductants H2and CO. Coal is added to the process gas in some processes to boost the reduction reactions. The prepared reducing gas enters the reduction furnace and is heated to the required temperature for reduction of the oxide feed.
In the shaft furnace processes, the mixture of lump ore and pellets flows downward by gravity. The hot reducing gas enters the shaft furnace around the exterior diameter and flows upward. When the descending ore is contacted by the upward flowing reducing gas, the ore is heated and reduction (removal of oxygen) takes place.
Once reduced, the material is either briquetted while hot as HBI (hot briquetted iron) or cooled and discharged as DRI. In the hot briquetting process, the HBI must be cooled prior to storage in piles.
In the fines-based processes, the ore fines are maintained in a fluidized condition in the reactors by the upward flowing reducing gas.The hot reducing gas enters the reactors through fluid bed grids at the bottom of each reactor. The ore flows downward by gravity and is heated and reduced by contacting the rising reducing gas.
Because of the small particle size of the reduced material, it must be briquetted following reduction.
HBI is produced in the form of briquettes at high temperature and pressure with specially designed roller presses. The typical volume of industrially manufactured briquettes is in the range of approx. 100 cm³.
The DRI is discharged hot from the reduction process and pushed intothe nip between two counter rotating rollers by a mechanical or hydraulic screw (see Figure 2). Pockets in the synchronously rotating rollers form the briquettes. This process occurs at high temperatures (> 650° C) and high pressing forces (120 kN per cm active roller width). The continuous string of briquettes leaving the rollers is guided by a heavy chute and separated into mostly singles for by a rotor with impact bars in the case of shaft furnace-based direct reduction processes. Briquettes produced in fluidized bed processes from fines are separated in a rotating tumbling drum.
The system for the hot briquetting of DRI typically consists of (see Figure 3):
– Briquetting press with screw feeder and material supply (1)
– Briquette string separator (impact separator (2) or tumbling drum (7)),
– Hot screen for the elimination of fines which occur during briquetting and separation (3),
– Product cooler (4),
– Bucket elevator for the recirculation of fines to the briquetting press (5),
– Chutes and accessories
The mechanism of briquetting as well as the briquette structure and, consequently, details of the equipment used in the particular system, depend on the characteristics of the material to be briquetted.
The deformed pellets and lump ore pieces originating from a gas based shaft furnace technology are still visible in the briquette structure, while a more uniformly briquette results from the fine particles of a fluidized bed process (see Figure 4).
HBI Advantages for Steelmaking
HBI is a manufactured product with an identifiable production cost structure and year-round operation (no collection season like scrap), which allows producers the option to offer long-term supply contracts. In addition, it has these unique operational characteristics and benefits:
• Density greater than 5000 kilograms per cubic meter (g/m3), which allows for rapid penetration of the furnace slag layer
• Well-defined, consistent chemistry with guaranteed specifications.
• Low residual content (Cu, Ni, Cr, Mo, Sn, Pb, and V):
– Dilutes impurities in lower quality scrap.
– Blends with other metallics for best total charge economics
• Applicable for full range of steel products
• Higher thermal and electrical conductivity for faster melting
• Less fines generation for added value
• Easy to handle, store, and transfer in all types of weather with standard materials handling equipment
• Applicable for AC or DC furnaces, long or short arc operation
• Continuous or batch feeding
• Promotes controlled slag foaming and reduces EAF nitrogen level
• Shields refractory and reduces electrode breakage.
• Boosts iron production, reduces coke rate and CO2emissions
• Compatible with injected fuels and oxygen
• Metallic yield in similar to hot metal
• Predictable mass and heat balances
Uses of HBI
Due to its physical characteristics and chemical purity (Figure 5), HBI can be used in every type of furnace for iron and steel production and iron casting.
Electric Arc Furnaces
HBI typically is used as a high density, low residualiron source to dilute obsolete scrap. In this role, HBI can make up 10-40 percent of the total charge. Melt shops that intend to use higher percentages of HBI should consider the addition of a continuous charging system.
EAF operators can benefit from HBI use in two ways:
1. High quality steels can be produced that would be impossible with purchased scrap alone due to elevated residual levels.
2. Merchant quality steel can be produced with lower grades of scrap that are easier to find and less costly to buy.
HBI has two applications in oxygen steelmaking furnaces:
1. As a cold charge material instead of scrap (to avoid chemistry or residual problems).
2. As a trim coolant to control temperature late in the heat cycle.
Typically, HBI is loaded into the scrap box by magnet in a manner similar to scrap. Melt shops equipped with sub-lance gear and using HBI as a coolant usually add the briquettes continuously or through the additive feeding system. HBI also can be used in these cases to dynamically control steel temperature.
As a trim coolant, HBI will provide better iron yield for the same amount of cooling when compared with iron ore and limestone and will not further oxidize the molten charge.
HBI can be used in almost any ladle metallurgy facility, ladle refiner, ladle furnace, or vacuum degasser as an effective trim coolant. It can be fed automatically, semi-automatically, or manually. Due to its size and density, HBI is excellent for penetrating the ladle slag and cooling the metal. It floats low at the metal line and will not sink to the bottom of the ladle and cause ladle valve or temperature stratification problems.
HBI can be added to the blast furnace burden to increase productivity and reduce coke consumption and CO2emissions. Because it is already chemically reduced, HBI passes through the furnace easily and melts along with the balance of the burden. The sizing of HBI makes it superior to scrap for use in the blast furnace.
Operators can obtain short-term increases in blast furnace output without the need for capital improvements or long lead times to change practices. Examples are period when peak output is needed to satisfy market conditions or when a blast furnace is down for relining or repairing and increased production is required from the on-line furnace.
HBI usually can be charged using the existing stock house and burden charging systems, and sticking and hanging problems sometimes encountered with scrap are avoided.
HBI can be successfully melted in hot blast or cold blast cupolas, coreless induction furnaces, and electric arc furnaces in foundry applications. It is of particular value in making ductile iron castings due to its extremely low tramp element content, and it can be used also for malleable iron and steel castings.
Foundry operators can benefit from using HBI in several ways:
1. It produces high quality casting due to low tramp and residual levels.
2. It allows blending with low grade, low cost scrap.
3. It can be handled, stored, and charged more effectively than scrap.
4. It is a manufactured material with consistent, guaranteed chemistry.
5. It can reduce the number of off-grade heats.
6. It can replace more expensive pig iron.
HBI and “Green” Steelmaking
An EAF melting 100 percent clean scrap has the lowest greenhouse gas emissions and is the most energy friendly of all steelmaking options. However, this practice is not feasible in many parts of the world and is not conducive to producing high quality steel products.
The increasing concern for the environmental impact of iron and steel production calls for realistic solutions. One proven approach is to use natural gas as a reductant and fuel source to produce low residual direct reduced iron in pellet and lump form or as physically enhanced hot briquetted iron.
According to figures derived from a study byMidrex Technologies Inc., the use of HBI produced by a natural gas-based direct reduction process in an electric arc furnace generates 60 percent less CO2emissions per ton of steel produced than does the BF/BOF route.
HBI also can help reduce the environmental “footprint” of the blast furnace. The high Fe content of HBI increases the overall metallization of the furnace burden, thereby decreasing the coke rate. For each 10 percent increase in burden metallization, the coke rate will decrease by 7 percent (100 kg of HBI/tonne of hot metal = -43 kg of coke/tonneof hot metal). By substituting 200 kg of HBI for coke in the furnace burden, CO2emissions can be reduced 14 percent per tonne of hot metal.
Hot Briquetted Iron Association (HBIA) (Now the IIMA)
The HBIA is a not-for-profit, international trade organization whose members include all major producers and exporters of HBI, suppliers of process technology, equipment, materials and services, including transportation to the HBI industry, and traders and brokers involved in buying and selling HBI and other metallics.
HBIA objectives are:
• To promote HBI as steel’s most versatile metallic
• To inform ship owner/operators and charterers and terminal operators of the shipping, handling, and storage benefits of HBI
• To assist iron and steel producers in the effective use of HBI HBIA has four types of members:
1. Producers – companies that manufacture HBI or have begun construction of an HBI plant, or have assumed the operations of an HBI plant
2. Associates – companies engaged on a continuing basis as either an HBI plant builder or a supplier of technology, goods or services to the HBI Industry
3. Traders – companies engaged on a continuing basis in selling or brokering HBI and other steelmaking metallics
4. Special – individuals who have made noteworthy contributions to the success of the HBI Industry
HBIA members span the gamut of the HBI supply chain, from iron ore mining to transporting and trading HBI. They are leaders in their business areas:
• Suppliers of more than 90 percent of all DR plants
• Leading supplier of pelletizing plants
• Leading supplier of hot briquetting machines
• Leading suppliers of DR-grade pellets
• Most experienced carriers of HBI
• Most experienced port terminal for shipping HBI
• Originator of soft loading method and equipment
Members are encouraged to participate in the three standing committees: Promotion, Technical, and Transportation. These committees are involved in HBI market development, industry interaction, production and shipping statistics, HBI standards and certifications programs and environmental awareness.
As an HBIA member, companies have:
• Access to and networking with the major producers, suppliers, and traders of HBI and other steelmaking metallics
• Representation at major worldwide conferences, trade shows, and meetings
• Source of news, information, and statistics about HBI and the global steel industry
• Presence in international forums that set guidelines for handling, shipping and storage of merchant steelmaking metallics
• Entry into Members Only area of the HBIA Web site (www.metallics.org.uk)
• Roster of member companies and contact information
HBIA is a member or has working relationships with
• Arab Iron and Steel Union (AISU)
• Association for Iron & Steel Technology (AIST)
• Dry Bulk Terminals Group (DBTG)
• International Pig Iron Association (IPIA)
• South East Asia Iron and Steel Institute (SEAISI)
• Sponge Iron Manufacturers Association (SIMA)
In 2008, HBIA was granted IMO consultative status, which provides a collective voice for the HBI industry in maritime shipping decisions. HBIA also is helping facilitate registration of HBI as an imported chemical substance under the European Union REACH regulations.
Antara Steel Mills (Labuan) HBI Operation The introduction of HBI in the SEAISI countries and the HBI plant owned and operated by Antara Steel Mills Sdn. Bhd. go hand-in-hand. In late 1984, the first HBI plant dedicated to the Asian market was started up on Labuan Island by Sabah Gas Industries Sdn. Bhd. in order to develop a value-added use for the natural gas in the Erb West field (see Figure 6). By early 1986, the fledgling plant had made trial shipments to India and the Philippines and was establishing a name for itself and its product from Malaysia to Europe.
The SGI plant worked closely with its early customers to determine the benefits of HBI use based on documented results. These included:
• Significant reduction of Cu, Cr, Ni, Sn, P, and S in the steel products
• Excellent results producing low card steels (AISI 1008 and 1006)
• Reduction of missed heats by 55 percent
• Significant increase of ductility in wire drawing (down to 16 gage)
• Reduction of inclusion count (17 with 20% HBI, 12 with 30% HBI)
• Improvement of tap-to-tap time (10% when batch charging 30% HBI)
• Improvement of yield (2.5% when using 20% HBI)
By 1988, the SGI plant had shipped more than one million metric tons (tonnes)of HBI to electric arc furnace (EAF) steelmakers for making everything from rebar to flat products and alloy and stainless steels. Another 400,000 tonnes had been consumed by basic oxygen furnace and open hearth furnace operators.
HBI from Malaysia also found a home in foundry operations. Cupolas and induction furnaces in Japan and Europe began using HBI to produce spheroidal graphite iron and compact graphite castings. A series of test during these applications revealed that the clean and consistent chemistry of SGI’s HBI significantly reduced downgrading, diversions, and off-grade heats. Its size, shape, and density were found to facilitate handling, shipping, and storage.
The most notable benefits of using HBI in foundry operations were:
• Significant increase in product ductility
• Reduced use of spheroidizing agent (innoculator)
• Lower levels of manganese an tramp elements in products
• Improved product consistency
• Reduced rejection rates
In October 1992, the SGI plant was acquired by The Lion Group, a diversified business group based in Peninsular Malaysia. The new owners viewed the plant’s HBI as their protection from the uncertainty of scrap supplies. The plant was renamed Amsteel Mills Sdn. Bhd. (Labuan) in 1995 in a corporate restructuring. On September 1, 2005, the HBI business was again renamed Antara Steel Mills Sdn. Bhd. (Labuan)in another corporate exercise.
The reduction furnace underwent an upgrade in October 2005, which increased its production volume by 13 percent – from 102 tonnes per hour to115 tonnes per hour. A fourth briquetting machine was installed to increase machine availability and HBI output. Other improvements to the plant site included installation of a VPSA oxygen plant, a two-cell cooling tower, an oxide coating plant, and the provision for oxygen injection into the furnace bustle gas.
The Lion Group started up a 1.5 million tonnes per year hot discharge/hot transport direct reduction plant adjacent to its Megasteel melt shop in Banting, Malaysia, in May 2008. The commissioning of the new DR plant has enabled the Antara Steel Mills (Labuan) HBI Operation plant on Labuan Island to return to its original role as a merchant source of high quality metallics for use in iron and steel production throughout the region, the Pacific Rim, and China.
Use of HBI by The Lion Group
A true measure of the value of HBI is when a producer uses the material in its own steel operations. Such is the case with The Lion Group, which has used HBI from the Antara Steel (Labuan) HBI plant to make high quality products in its steel mills operated by Megasteel Sdn. Bhd. and Amsteel Mills Sdn. Bhd.
Megasteel Sdn. Bhd.
The Megasteel mill located in Banting, Selangor, is the first integrated steel mill in Malaysia to produce flat products, with an annual production capacity of 3.2 million tonnes of hot rolled coils and 1.45 million tonnes of cold rolled coils. The fully automated, state-of-the-art facility is based on the Electric Arc Furnace-Compact Strip Production (EAF-CSP) process, which incorporates (1) a 160-tonne direct current electric arc furnace (DC EAF), (2) an advanced design ladle furnace, and (3) thin slab continuous casting technology developed by SMS of Germany.
Megasteel is located in close proximity to the Klang Valley where 70 percent of the Malaysian consumers of hot rolled coils are based. Access to the Klang Port facilities the export of its products and lowers the transportation costs for importing raw materials.
Amsteel Mills Sdn. Bhd.
Amsteel Mills produces billets for rolling into bars and wire rods in its plant in Klang, Selangor, and special grade bars and wire rods in its Banting mill. Another facility operated under the name of Antara Steel Mills Sdn. Bhd. is located in Johor and produces billets and bar products for the construction industry. Together, Amsteel and Antara have a steelmaking capacity of 3.05 million tonnes of billets and a rolling capacity of 2.35 million tonnes. A commitment to prompt and reliable delivery of quality steel products has enabled Amsteel and Antara Steel to gain local and international acceptance and customer satisfaction.
Scrap availability and quality fluctuate in Malaysia; therefore, it is necessary to supplement the scrap supply and dilute the residual elements that are detrimental to producing high quality steel products.
Megasteel and Amsteel operate in a very environmentally conscious manner by melting recycled steel scrap and low residual HBI and pig iron. This results in the lowest possible CO2emissions and allows the mills to cost effectively achieve their quality specifications. Steelmaking Practices The Lion Group steel mills use HBI to meet strict chemical and physical specifications for their steel products due to its much lower residual elements content than scrap. It also tends to densify the scrap charge and allows a two-bucket charge practice. If 100 percent scrap is used, three charge buckets are required.
HBI or pig iron is arranged in the charge buckets along with various grades of scrap. Lighter scrap is placed at the bottom and top of the bucket with HBI or pig iron placed between layers of heavier scrap in the middle of the bucket. This allows the HBI or pig iron to fill the voids in the scrap charge and to settle near the bottom of the furnace after charging. The first bucket contains the greatest portion of HBI and pig iron.
After the roof is closed and melting begins, additional HBI is fed to the furnace through the flux and ferroalloy charging system. The amount of HBI is calculated carefully to improve melting practice without deviating from normal operating parameters.
Megasteel and Amsteel have found that 23-24 percent HBI and 13-14 percent pig iron in the charge, respectively, is optimum for producing low and medium carbon steel grades.
Impact on Melt Shop Operations
Figure 7 shows the production flow scheme of the Megasteel plant and Figure 8 shows a simplified melt shop flow scheme for Amsteel.
The use of HBI has provided a number of advantages to Megasteel and Amsteel in the operation of their EAF melt shops:
The use of HBI and pig iron contributes to more stable arcing and a reduction in flicker and voltage fluctuations when compared with melting 100 percent scrap. The result is improved power consumption rates.
The energy consumption for Megasteel and Amsteel when using HBI plus pig iron is very similar, as shown in Figures 9 and 10.
Based on data collected from 8650 heats, Megasteel consumed an average of 473 kWh/tonne of liquid steel. The average heat composition was 63 percent scrap, 23 percent HBI, and 14 percent pig iron.
Amsteel averaged 497 kWh/tonne of liquid steel based on data from 3411 heats. The average heat composition was 63 percent scrap, 24 percent HBI, and 13 percent pig iron.
The combination of eliminating a scrap bucket back charge and the ability to feed HBI through the furnace roof during melting has a positive effect on tap-to-tap times. As the number of bucket charges is reduced, the furnace electrodes are subjected to less mechanical damage and exposure to the atmosphere, which has the effect of reducing electrode consumption.
Megasteel averaged 75 minutes tap-to-tap times using 23 percent HBI and 14 percent pig iron during which power on time was 62 minutes.
Amsteel received similar results with tap-to-tap times averaging 77 minutes and power on time averaging 61 minutes.
The tap-to-tap times for Megasteel and Amsteelare shown in Figures 11 and 12, respectively.
Fewer Missed Heats
HBI is practically free of residual elements that are troublesome to steelmakers (i.e., Cu, Ni, Cr, Mo, Sn, Pb, and V) and continues very low levels of sulfur, phosphorus (in the form of P2O5), and copper. The known and constant chemical composition of HBI combined with pig iron greatly improves the control of heat chemistries.
Metallurgically Sound Products
Non-metallic inclusions in the liquid steel are removed in the metal bath by the liberation of CO2gas during the reaction of FeO and carbon contained in the HBI and pig iron. This and the “clean” chemistries of HBI and pig iron provide for the metallurgical soundness for which Megasteel and Amsteel products are known.
The problems inherent with dependence on scrap such as availability, chemical contamination, and quality variation can be minimized by adding HBI to your furnace charging practice. The use of low residual, high Fe content HBI in combination with scrap and other metallics such as pig iron provides steelmakers more control over their cost of liquid steel when producing any grade of steel and the ability to compete in markets that are beyond the scope of a total scrap practice.