The Processes of Iron and Steel Making

Total Page:16

File Type:pdf, Size:1020Kb

The Processes of Iron and Steel Making The Processes of Iron and Steel Making This page has been constructed to give the reader a more in-depth insight into the processes carried out at the Wortley Forges, associated and similar works. You will find some descriptions are duplicated on other pages in this site. Iron Mining The Bloomery Iron Making Process The Finery & Chafery Iron Making Process Iron Making by Blast Furnace The Puddling Process Making Cementation Steel Making Crucible Steel Making Bessemer Steel Making Steel by the Siemens Process Magazine Article explaining iron making Iron Mining The availability of Iron Ore was the key to the early iron industry. Even today (and more conspicuously up to the 1970s) a number of steelworks sites were directly a results of a furnace and later a works built were iron ore was available, although some sites are a result of water power, transport, fuel and other economic pressures. Iron is very common on the planet earth and the British Isles are no exception, however only where the iron content of the ore is quite high is the ore worth exploiting. This is one reason why almost all iron ore is now imported into the U.K. from the likes of Africa and Australia. It seems that iron ore was mined in many areas across the country, but these area progressively reduced as the demand increase and larger scale operations became more common. The important iron mining areas were to the south of Cumbria (near Barrow in Furnace), South Teeside, North Lincolnshire and a band across the midlands from Lincolnshire to Oxfordshire. Iron Ore, be worth working, must be high in Iron & Oxygen, but will also include such unwanted impurities as Phosphorus. Return to Top of Page The Bloomery Iron Making Process This is the process that started the Iron Age. It seems most likely that a lump of Iron Ore in a particularly hot fire lead to a strange material left in the embers of the fire. From this, the Bloomery Furnace developed, in this a mixture of Iron Ore and Charcoal was burnt with the help of a blast of air from hand worked bellows. The Output was typically a small lump of Wrought Iron of poor quality, but even this was enough to make an impact on history. Return to Top of Page The Finery & Chafery Iron Making Process Return to Top of Page Iron Making by Blast Furnace How the tower of the first Blast Furnace was developed may never be known but the associated process of iron making increase the volume of iron that could be smelted while also reducing the price. The first record of a Blast Furnace in the U.K. is in 1496. Early furnaces were best located on sloping ground, close to a reliable stream. Water was used to drive the early bellow to create the drought, while the slope helped to provide a near level roadway onto the top of the furnace. The key to the process is the removal of the oxygen from the iron ore at the same time as separating as many of the other impurities as possible. A blast furnace works on a continuous process lasting weeks, months, or in modern times, years and it will be assumed that the furnace is in the middle of a campaign and so the lighting the furnace (blowing in) can be ignored. Clean carbon (Charcoal or later Coke), Iron Ore and Limestone are added to the top of the furnace. Little and often is best as it has the least affect on the burning of the furnace. Also important is that the charge material is alternated (e.g.. Iron Ore, then Coke, then Limestone, and then more Iron Ore). At the top of the furnace the charge is heated and dried by the hot gases being blown through the furnace. Lower down, the iron ore melts as the carbon starts to burn and from just below the middle of the furnace, molten iron drips down through the remaining carbon fuel onto the hearth at the very bottom of the furnace. As there is insufficient oxygen in the air blast to properly burn the carbon fuel oxygen is captured from the iron ore, however, in spite of this, the majority of the gas produced is still Carbon Monoxide. In the lower part of the furnace, the limestone acts as a flux and draws together many impurities together into a layer of slag that floated onto of the molten iron. The molten iron and slag is drawn off periodically. The air blast is introduced a little way above the hearth and must be strong enough to stop the burning contents of the furnace stack dropping into the hearth, but must also not be so strong as to blow the contents out of the top. Until the introduction of the Blast Furnace cast iron had not existed and iron had never been seen as a liquid in any great volume. Since the start of the 18th Century the Blast Furnace has developed in a number of ways. Firstly Coke was introduced as a fuel in place of charcoal, allowing the size of furnace to be increase (charcoal would collapse under the extra weight from a large furnace). This was famously pioneered by Abraham Darby at Coalbrookdale in 1709 and was almost universal within 100 years, however a few charcoal furnace carried on until as late as 1921! Secondly the blast air was heated using heat recovered from the exhaust gases (energy conservation is not that new). Lastly, the Coke and Iron Ore are now mixed and heated, producing sinter, before they are charged into the furnace. Interestingly, you can tell from the texture and colour of the slag whether or not a furnace has had a hot or cold blast. Modern Blast Furnaces can be 35m (120ft) high, 14m (45ft) diameter and can produce 10,000 tons per day. The Iron produced by a Blast Furnace is always call 'Pig Iron'. The title of 'Cast Iron' is only generally used after the iron has been cast into a finished product. Early furnaces producing small quantities of iron could be used to cast products directly and some furnaces, such as Rockley Furnace, had casting pits for large items such as Cannon. With larger furnaces, all iron was cast into pigs and was remelted but from the 1850s molten iron was charged into other types of furnace, mixer or converter. Little if any iron is now cast into pigs in the U.K., as steel making plants are incorporated into the same works as the Blast Furnaces. Return to Top of Page The Puddling Process In 1784 Henry Cort devised a method of producing Wrought Iron from Cast Iron using a Coal fired Reverberatory Furnace. Solid Cast Iron was heated within an enclosed furnace. A Reverberatory Furnace is a long low structure built out of fire bricks. The coal fire was at one end with the hearth between the fire and the chimney. The hearth was slightly dished with a roof that directed the smoke and flame from the fire well above the iron. By keeping the smoke and flame above the iron, no carbon from the fire came in contact with the iron. Solid Pig (Cast) Iron was heated vigorously in the hearth until it was all molten. The fire was then damped down and the iron stirred so as to bring as much as possible in contact with the air. As wrought Iron has a higher melting point than Cast Iron, if the temperature in the furnace was correct the iron began to solidify as the carbon was removed. Eventually the Wrought Iron could be worked into a single lump of iron in the centre of the Hearth. Although in theory this was Wrought Iron it was not usable in this form because of the slag within the lump. For the Wrought Iron to be made usable, it was lifted from the furnace and forged using a 'Shingling Hammer'. Finally it was rolled into bars or sheet. As most of the slag was squeezed out of the iron under the Shingling Hammer this could be a dangerous job, with each drop of the hammer white hot slag would be strayed out across the forge. As the workmen had to hold and move the iron during the forging, there was no option other than for them to dress in heavy protective clothing. An improvement to Cort's puddling process came from Joseph Hall in 1816. Hall added mill scale (iron oxide formed and broken off during the forging and rolling) to the Cast Iron at the start of the Puddling process. Once the iron had melted, the carbon monoxide formed by the mill scale bubbled up through the iron giving the impression of boiling, thus the common name for this refinement 'Pig Boiling'. Return to Top of Page Making Cementation Steel Standard Wrought Iron bars were placed in the Cementation Furnace for conversion into Cementation or Blister Steel. The furnace was constructed from sandstone in the from of a large chest with a lid and was loaded with the iron bars placed in layers inter spaced with large quantities of high quality Charcoal. When fully loaded, the lid was put in place and mortar use to seal the chest. Heating was applied from a fire below the furnace where a coal fire was maintained from a pit. Heat was maintained for up to a week and a further week was taken for the chest to cool before being opened, emptied, and reloaded. The common design for cementation furnaces had two chests side by side with a fire hole in the centre of the two and the whole lot contained within a bottle shaped structure, similar to 'glass cones' and 'pottery kilns', that sheltered the furnaces from the weather and acted as a chimney.
Recommended publications
  • Society, Materials, and the Environment: the Case of Steel
    metals Review Society, Materials, and the Environment: The Case of Steel Jean-Pierre Birat IF Steelman, Moselle, 57280 Semécourt, France; [email protected]; Tel.: +333-8751-1117 Received: 1 February 2020; Accepted: 25 February 2020; Published: 2 March 2020 Abstract: This paper reviews the relationship between the production of steel and the environment as it stands today. It deals with raw material issues (availability, scarcity), energy resources, and generation of by-products, i.e., the circular economy, the anthropogenic iron mine, and the energy transition. The paper also deals with emissions to air (dust, Particulate Matter, heavy metals, Persistant Organics Pollutants), water, and soil, i.e., with toxicity, ecotoxicity, epidemiology, and health issues, but also greenhouse gas emissions, i.e., climate change. The loss of biodiversity is also mentioned. All these topics are analyzed with historical hindsight and the present understanding of their physics and chemistry is discussed, stressing areas where knowledge is still lacking. In the face of all these issues, technological solutions were sought to alleviate their effects: many areas are presently satisfactorily handled (the circular economy—a historical’ practice in the case of steel, energy conservation, air/water/soil emissions) and in line with present environmental regulations; on the other hand, there are important hanging issues, such as the generation of mine tailings (and tailings dam failures), the emissions of greenhouse gases (the steel industry plans to become carbon-neutral by 2050, at least in the EU), and the emission of fine PM, which WHO correlates with premature deaths. Moreover, present regulatory levels of emissions will necessarily become much stricter.
    [Show full text]
  • Iron, Steel and Swords Script - Page 1 Powder Is Difficult
    10.4. Crucible Steel 10.4.1 The Making of Crucible Steel in Antiquity Debunking the Myth of "Wootz" Before I start on "wootz" I want to be very clear on how I see this rather confused topic: There never has been a secret about the making of crucible (or "wootz") steel, and there isn't one now. Recipes for making crucible steel were well-known throughout the ages, and they were just as sensible or strange as recipes for making bloomery iron or other things. There are many ways for making crucible steel. If the crucible process worked properly, the steel produced was fully liquid, and it didn't matter much exactly how you made it. If the process did not work well and the steel was only partially molten, i.e. a mixture of liquid cast iron and solid austenite, the product was not good steel. Besides differences in the (always large) carbon concentration, the concentration of impurities might also be different - just like for bloomery steel. This might lead to differences in properties for comparable carbon concentrations, for example the susceptibility to cold shortness or the ability to form a good "watered silk" or "water" pattern. Crucible steel that has been liquid once is relatively homogeneous and slag-free - in contrast to bloomery steel. That is where crucible steel is "better" than bloomery steel. Crucible steel is always high carbon if not ultra-high carbon steel (UHCS). This is generally not so good. However, mixtures that would, for example, have produced 0.8 % carbon steel, a steel optimal for many applications, would not melt at the temperatures available.
    [Show full text]
  • Grasp Success by the Roots
    Grasp success by the roots Forming and root protection ensure perfect weld seams and roots Profit from forming For more than 40 years, root protection and forming have proven their value in welding technology. They permit an increase in weld Laminar and turbulent flow seam quality and contribute to a reduction of follow-up costs. The focus here is on reworking, pickling costs, the associated transport costs and Laminar flow instead of turbulence the not inconsiderable loss of time. With correct In order to ensure the high quality and economy forming, weld seams and roots can be produced of the work, a few basic rules must be observed. which need no reworking. One of the most important concerns the feed of the shield gas to the weld seam region. This Forming and root protection should never be uncontrolled. In an optimum Root protection is the bathing of the weld root shield gas feed, the flow is laminar. If the flow is and the heat affected zone with shield gases, turbulent, the eddies result in mixing of the while simultaneously displacing atmospheric forming gas and the atmosphere. A laminar flow oxygen (DVS Data Sheet 0937). When applied to is generated with the help of a diffusor, usually pipes and tanks, it is known as forming. This comprising pipes, sheets or mouldings of sinter technique is used for the welding of gas sensitive material. The sinter metal distributes the gas materials such as high alloyed CrNi steels, for feed over a large area, from which the forming example, to ensure the corrosion resistance of gas is emitted in laminar form.
    [Show full text]
  • Shielding Gas. Gases for All Types of Stainless Steel
    → Stainless Steel - New Zealand edition Shielding gas. Gases for all types of stainless steel. Argon 03 Stainless steel is usually defined as an iron-chromium alloy, containing at least 11% chromium. Often containing other elements such as silicon, manganese, nickel, molybdenum, titanium and niobium, it is most widely used as corrosion resistant engineering material in applications where aggressive environments or elevated temperatures are prevalent. Stainless steel is traditionally categorised into four main groups and each group is further sub-divided into specific alloys. The main groups are: austenitic, ferritic, martensitic and duplex. → Austenitic stainless steels are the most widely used, accounting for around 70% of all stainless steels fabricated. They are used in applications such as chemical processing, pharmaceutical manufacturing, food processing and brewing, and liquid gas storage. The weldability of these grades is usually very good. → Ferritic stainless steels are not as corrosion resistant or as weldable as austenitic stainless steels. They have high strength and good high temperature properties and are used for products such as exhausts, catalytic converters, air ducting systems, and storage hoppers. → Martensitic stainless steels are high strength but are more difficult to weld than other types of stainless steels. They are used for products such as vehicle chassis, railway wagons, ­ mineral handling equipment and paper and pulping equipment. → Duplex stainless steels combine the high strength of ferritic steels and the resistance of austenitic steels. They are used in corrosive environments such as offshore and ­ petrochemical plants, where the integrity of the welded material is critical. ARGOSHIELD®, ALUSHIELD® STAINSHIELD® and SPECSHIELD® are registered trademarks of BOC a Member of The Linde Group.
    [Show full text]
  • Iron and Steel: Introduction
    Iron and Steel: Introduction Iron is cheap and strong and the most used metal in the world. Iron, as produced in the blast furnace is called pig iron. This is brittle because it contains about 4% carbon and other non-metal impurities. Most of this iron is converted into a variety of steels by removing nearly all the carbon, and adding small quantities of different metals. The different steels are alloys which are mixtures of metals. They have different properties such as toughness, hardness, corrosion resistance, etc. Some background The method of using carbon to reduce iron oxide to iron was very probably discovered accidentally in prehistoric camp fires. Here, charcoal would have been the source of carbon. The iron was used to make tools and weapons and gave its name to the Iron Age. Early in the 18th century, Abraham Darby in Shropshire discovered a method of converting coal to coke as a source of carbon. This led to the modern blast furnace. In the mid-19th century, Henry Bessemer developed a steel-making process that used oxygen to burn off some of the carbon in cast iron. The Basic Oxygen Steelmaking process was introduced in the 1950s and now accounts for about two-thirds of steel production. Did you know? Stainless steel contains about 18% chromium. About three-quarters of food and drinks cans are made of steel. A car tyre contains over ½ kg of steel wire. About 400 million tonnes of steel are recycled every year worldwide. Iron and Steel: Introduction | 1 .
    [Show full text]
  • ARCHAEOLOGY DATASHEET 302 Steelmaking
    ARCHAEOLOGY DATASHEET 302 Steelmaking Introduction A single forging produced ‘shear steel’, a second operation Although an important aspect of medieval and earlier resulted in ‘double shear steel’ and so-on. societies, the manufacture of steel was industrialised during Furnace design changed over time, and also appears to the post-medieval period. Many complementary techniques have shown some regional variation. The first English steel were developed which often operated at the same time on furnaces were built at Coalbrookdale (Shropshire) by Sir the same site; there were also close links with other Basil Brooke in c1615 and c1630. These were circular in ironworking processes. This datasheet describes pre-20th plan with a central flue. They probably contained a single century steelmaking processes in the UK, their material chest and would have had a conical chimney. Other 17th- remains and metallurgical potential. century cementation furnaces were located in and around Birmingham, Wolverhampton, Stourbridge and Bristol, but Carbon steel and other alloys none of these have been excavated. The north-east became Until the late 19th century, steel was, like other types of the main area of cementation steelmaking in the late 17th iron, simply an alloy of iron and carbon (HMS datasheet and early 18th centuries. Ambrose Crowley established 201). There was considerable variation in the nature of several cementation steelworks, and others followed. Of ‘steel’ and in the properties of individual artefacts. Cast these, the oldest standing structure is at Derwentcote iron, smelted in the blast furnace usually had a carbon (County Durham), built in 1734. Unlike the West Midlands content of 5-8%, making it tough but brittle.
    [Show full text]
  • Studies of NRIM Continuous Steelmaking Process*
    UDC 669.18-932 Studies of NRIM Continuous Steelmaking Process* By Ry uichi NAKAGAWA:* S hiro YOS HIMATSU:* Taklly a UEDA:* Tatsllro M ITSUI, ** Akira FUKUZA WA:* A kira S ATO:* and TS llyoshi OZAKI** Synopsis K.)U- 13) The fundamental aspect q! the development of the NRIM multi-stage (2) Tank type continuous steelmaking process at trough type continuous steelmaking process and the results of its recent IRSID (France )14- 16) operations are presented in this jJaper. Though the scale of the plant used (3) Single stage trough type continuous steel­ was small (7.8 tlhr in hot metal flow rate), a suitable sejJaration of the making process (WORCRA process) at CRA (Austral­ steelmaking reactions to each stage of the continuous steelmaking furnace ia)17 - 20) and the know-how qf its ojJeration were satiifactorily obtained. As the (4) Single stage trough type continuous steel­ result of the separation, that is, silicon and phosphorus were mostly removed making process at Bethlehem Steel Co. (U.S.A. )21) in the first stage so that the final carbon level was controlled mainly in the second stage, the product with phosphorus as low as 0.005% (dephosjJhori­ (5) Single stage multi-chamber type continuous z ation rate 96% ) was obtained with comparable amount of lime to that steelmaking process at MISiS (U.S.S.R.)22) of the conventional batch type steelmaking processes. The industrializ a­ (6) Multi-stage trough type continuous steelmak­ tion of this process is confirmed to be feasible. ing process at NRIM (Japan)23- 34) In NRIM the research on the continuous steelmak­ I.
    [Show full text]
  • EFFICIENT GAS HEATING of INDUSTRIAL FURNACES EFFICIENT GAS HEATING of INDUSTRIAL FURNACES COMPANY PROFILE: Gasbarre Furnace Group JANUARY/FEBRUARY 2017
    THERMAL PROCESSI NG MAGAZINE MAGAZINE NG EFFICIENT GAS HEATING OF INDUSTRIAL FURNACES FURNACES INDUSTRIAL OF GAS HEATING EFFICIENT EFFICIENT GAS HEATING OF INDUSTRIAL FURNACES COMPANY PROFILE: Gasbarre Furnace Group JANUARY/FEBRUARY 2017 JANUARY/FEBRUARY JANUARY/FEBRUARY 2017 Technologies and Processes for the Advancement of Materials thermalprocessing.com TP-2017-01-02.indb 1 12/23/16 10:43 AM Regardless of the industry you are in or the Regardless of the industry you are in or the Regardless of the industry you are in or the processes you run, The Ipsen, Harold blog is processes you run, The Ipsen, Harold blog is processes you run, The Ipsen, Harold blog is devoted to providing expert-curated best devoted to providing expert-curated best devoted to providing expert-curated best practices, maintenance tips and details about practices, maintenance tips and details about practices, maintenance tips and details about the latest industry news and innovations. the latest industry news and innovations. the latest industry news and innovations. Want to know what everyone else is reading? Want to know what everyone else isWant reading? to know what everyone else is reading? Here are our top blog posts of 2016 ... Here are our top blog posts of 2016 ... Here are our top blog posts of 2016 ... 5 Quick Tips on How to Become a Brazing Superhero 5 Quick Tips on How to Become a Brazing Superhero 5 Quick Tips on How to Become a Brazing Superhero When it comes to vacuum aluminum brazing there are a lot of advantages, but you also need to know When it comes to vacuum aluminum brazing there are a lot of advantages,When but you also need to know it comes to vacuum aluminum brazing there are a lot of advantages, but you also need to know the details on how to properly braze your parts.
    [Show full text]
  • Measuring the Dewpoint of Hydrogen Forming Gas with a Zirconia Oxygen Sensor
    Measuring the Dewpoint of Hydrogen Forming Gas with a Zirconia Oxygen Sensor By Dr M A Swetnam 1 Abstract This paper describes the uses of hydrogen forming gas in reducing and oxidising industrial applications and explains why controlling the water content is so important in the metal heat treatment industry. Measuring water at elevated temperatures is extremely difficult to do with normal equipment. Cambridge Sensotec has developed a high temperature forming gas analyser capable of measuring the hydrogen dewpoint using a series of thermodynamic calculations, based on the signals from a modified Rapidox zirconia oxygen sensor. 2 Background Forming gas is used in many heat treatment applications as a cheap way to remove oxygen and control water in an oven or heat treatment process. Forming gas is a mixture of hydrogen (H2) and an inert gas which is nearly always nitrogen (N2). It can be made chemically by cracking ammonia: 2 3 + 1 3 → 2 2 which produces a ratio of 3:1 hydrogen to nitrogen. This method is not generally used because it is chemically inefficient and costly. More commonly the hydrogen and nitrogen are either mixed together on site or purchased as a pre-mixed cylinder from the gas company. Any mix of hydrogen and nitrogen can refer to forming gas, but the most common blend is 5% H2 in 95% N2. This mix is always below the lower explosive limit (LEL) Forming Gas White Paper v1.0 1 of hydrogen and is therefore considered a safe gas which does not require any special equipment or handling. 3 Forming Gas Applications Forming gas is used in specialist soldering applications as well as some photographic applications to clean long exposed film (e.g.
    [Show full text]
  • Mathematical Modeling of Discharge Plasma Generation and Diffusion Saturation of Metals and Alloys
    Information Technologies in Science, Management, Social Sphere and Medicine (ITSMSSM 2016) Mathematical Modeling of Discharge Plasma Generation and Diffusion Saturation of Metals and Alloys Nguyen Bao Hung1, T. V. Koval2, Tran My Kim An3 1,2,3 National Research Tomsk Polytechnic University Tomsk, Russia E-mail: [email protected], [email protected], [email protected] Abstract. This paper presents a mathematical modeling of the for which it is required to provide an ion current density of plasma generation in a hollow cathode and the diffusion ~1 mA/cm2 to a treated surface and a discharge operating saturation of metals and alloys by nitrogen atoms in the plasma voltage of hundred volts [8–11]. of a low-pressure non-self-sustained glow discharge. Characteristics of gas discharge are obtained. The relations The complexity and multiple relations of nitriding process between main technological parameters and structural-phase make difficult to define the general laws in the structuration of states of nitrited material are defined. Furthermore, this paper modified layers and their properties [12-16]. Such problems leads a comparison of calculated results with the experimental can be solved by mathematical modeling of the processes in data. plasma generation and material nitriding. This is also an effective way to establish the mechanisms of forming the Keywords: hollow cathode, glow discharge, low-pressure modified layer with specified properties and their dependences discharge, plasma, plasma cathode, plasma nitriding, diffusion on
    [Show full text]
  • Confirming the Dew Point of Forming Gas Using Intrinsically Safe
    Application Note Confirming the Dew Point of Forming Gas using Intrinsically Safe Impedance Dew Point Transmitters Application Background Hydrogen gas is widely used for the bright hardening of many kinds of metals. There are two main delivery methods for this process - bulk hydrogen from storage cylinders and cracked ammonia. Both delivery methods have advantages and disadvantages - cost and fire hazard in the case of pure hydrogen and corrosion risk and human safety being the main considerations in the case of cracked ammonia. However, nowadays cracked ammonia plants are the more common method of providing a reducing/hardening atmosphere for metallurgical furnaces. What is the process in an ammonia cracker? Pressurised liquid ammonia is heated in order to vaporise it and is then passed over a nickel catalyst at a temperature of around 1000°C, which causes it to dissociate into its component parts - hydrogen and nitrogen. The chemical equation for this reaction is: 2NH3 N2 +3H2 The diagram below illustrates the cracking process: As a result of complete dissociation into hydrogen and nitrogen, very little undissociated ammonia remains and the dew-point temperature of the resulting gas should be very low (well below -30°C). This gas can also be dried further by use of a heated-regeneration twin column desiccant dryer, the molecular sieve will also adsorb traces of uncracked ammonia still present in the gas, the gas exits the system dryer than -65°Cdp, consisting of 75 Vol% hydrogen and 25 Vol% nitrogen. Applications for dissociated ammonia The forming gas is used in conveyer furnaces and in tube furnaces for annealing processes in a reducing atmosphere, such as brazing, sintering, de-oxidation, and nitrization.
    [Show full text]
  • Blended Cement Mixed with Basic Oxygen Steelmaking Slag (BOF) As an Alternative Green Building Material
    materials Article Blended Cement Mixed with Basic Oxygen Steelmaking Slag (BOF) as an Alternative Green Building Material Assel Jexembayeva 1,2, Talal Salem 1, Pengcheng Jiao 3,4,*, Bozhi Hou 3 and Rimma Niyazbekova 2 1 Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA; [email protected] (A.J.); [email protected] (T.S.) 2 Technical Faculty, Saken Seifullin Kazakh Agro Technical University, Astana 010011, Kazakhstan; [email protected] 3 Institute of Port, Coastal and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, China; [email protected] 4 Engineering Research Center of Oceanic Sensing Technology and Equipment, Zhejiang University, Ministry of Education, Hangzhou 310000, China * Correspondence: [email protected] Received: 13 June 2020; Accepted: 4 July 2020; Published: 9 July 2020 Abstract: Portland cement tends to exhibit negative environmental impacts; thus, it is required to find measures that will improve its green credentials. In this study, we report a blended Portland slag cement as an alternative environmentally-friendly building material in order to reduce the total carbon footprint resulted from the production of the ordinary Portland cement (OPC), which may resolve the environmental issues associated with carbon dioxide emissions. The ordinary Portland cement type I enhanced by basic oxygen steelmaking slag (BOF) is produced and casted into cubic and beam-like samples for the compressive and three-point bending tests, and the compressive and flexural strengths are experimentally measured. Numerical simulations are conducted to compare with the experimental result and satisfactory agreements are obtained. X-ray diffraction (XRD) investigations and porosity tests are then carried out using the semi-adiabatic calorimetry, which indicates that 5% BOF is the optimal ratio to accelerate the hydration process while increasing the amount of hydration products, especially at the early curing age of 3 days.
    [Show full text]